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Ishizuka Mayumi

President/Vice-PresidentsExecutive/Vice-President
Institute for Academic InnovationExecutive/Vice-President
Center for Environmental and Health SciencesExecutive/Vice-President
Institute for Academic InnovationExecutive/Vice-President
One Health Research CenterExecutive/Vice-President

Researcher basic information

■ Degree
  • 獣医学博士, 北海道大学
■ URL
researchmap URLホームページURL■ Various IDs
J-Global ID■ Research Keywords and Fields
Research Keyword
  • シトクロムP450
  • 環境化学物質
  • エストロゲン
  • 野生動物
  • マイクロアレイ
  • アフリカ
  • ルシフェラーゼ
  • neonatal imprinting
  • レポーターアッセイ
  • アロマターゼ
  • レポーター
  • トランスジェニック
  • トキシコロジー
  • in vivoイメージング
  • ERE
  • インプリンティング
  • 視床下部
  • 環境汚染
  • ステロイドホルモン
  • 環境ホルモン
  • ビスフェノールA
  • ダイオキシン受容体
  • PPAR
  • フタル酸エステル
  • バイオマーカー
  • 環境汚染物質
  • ダイオキシン類
  • CYP1A
  • 海棲哺乳類
  • ドブネズミ
Research Field
  • Environmental Science/Agriculture Science, Landscape science
  • Environmental Science/Agriculture Science, Environmental agriculture
  • Environmental Science/Agriculture Science, Chemical substance influence on environment
  • Environmental Science/Agriculture Science, Radiation influence
  • Life Science, Applied molecular and cellular biology
  • Life Science, Hygiene and public health: excluding laboratory approach
  • Life Science, Hygiene and public health: including laboratory approach
  • Life Science, Medical management and medical sociology
  • Life Science, Veterinary medical science
■ Educational Organization

Career

■ Career
Career
  • 2011 - 2012
    北海道大学 (連合)獣医学研究科, 教授
Committee Memberships
  • Present
    日本毒性学会, 評議員, Society
  • Present
    食品安全委員会, 専門委員(動物用医薬品、添加物), Government
  • Present
    日本環境化学会, 理事, Society
  • Present
    日本獣医学会, 理事, Society
  • Present
    日本学術会議, 会員, Government
Position History
  • 教育改革室室員, 2019年4月1日 - 2020年9月30日
  • 教育改革室室員, 2020年10月12日 - 2022年3月31日
  • 教育改革室室員, 2022年4月1日 - 2024年3月31日
  • 教育改革室室員, 2024年4月1日 - 2026年3月31日
  • 教育研究評議会評議員, 2021年4月1日 - 2023年3月31日
  • 経営戦略室室員, 2017年10月26日 - 2019年3月31日
  • 経営戦略室室員, 2019年4月1日 - 2020年9月30日
  • 経営戦略室室員, 2020年10月12日 - 2021年3月31日
  • 総長補佐, 2017年4月1日 - 2019年3月31日
  • 総長補佐, 2019年4月1日 - 2020年9月30日
  • 総長補佐, 2020年10月12日 - 2022年3月31日
  • 総長補佐, 2022年4月1日 - 2024年3月31日
  • 総長補佐, 2024年4月1日 - 2024年12月31日
  • 大学院獣医学院長, 2021年4月1日 - 2023年3月31日
  • 大学院獣医学院長, 2023年4月1日 - 2025年3月31日
  • 大学院獣医学研究科副研究科長, 2013年4月1日 - 2015年3月31日
  • 大学院獣医学研究科副研究科長, 2015年4月1日 - 2017年3月31日
  • 副理事, 2025年1月1日 - 2026年3月31日

Research activity information

■ Awards
  • 2020, 日本環境化学会, 学術賞
  • 2015, ソロプチミスト日本財団, 女性研究者賞
    石塚真由美
  • 2015, 北海道大学, 研究総長賞(優秀賞)
    石塚真由美
  • 2009, 文部科学省, 科学技術分野の文部科学大臣表彰・若手科学者賞
    野生動物のシトクロムP450と汚染環境適応能力解明の研究
    石塚真由美
  • 2007, 日本農学会, 日本農学進歩賞
    環境化学物質が野生動物に引き起こす毒性と適応
    石塚真由美
  • 2007, 日本トキシコロジー学会, 奨励賞
    野生生物のシトクロムP450と汚染環境への適応機構に関する研究
    石塚真由美
■ Papers
  • Exploring the intricacies of indoor dust pollution from neonicotinoid insecticides and its human health impacts: An exemplar from eleven agricultural communities in Ghana, West Africa
    Collins Nimako; Osei Akoto; Nathaniel Boadi; Prince Ofori; Yared B. Yohannes; Shouta M. M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka
    JOURNAL OF HAZARDOUS MATERIALS, 500, 05 Dec. 2025
    English, Scientific journal
  • Exploring the intricacies of indoor dust pollution from neonicotinoid insecticides and its human health impacts: An exemplar from eleven agricultural communities in Ghana, West Africa.
    Collins Nimako; Osei Akoto; Nathaniel Boadi; Prince Ofori; Yared B Yohannes; Shouta M M Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka
    Journal of hazardous materials, 500, 140172, 140172, 05 Dec. 2025, [International Magazine]
    English, Scientific journal, Neonicotinoid insecticides are the most widely used class of insecticides globally; however, knowledge of their indoor residual pollution is limited across various regions of the world. This study aimed to investigate the intricacies of indoor dust contamination from neonicotinoid insecticides across 11 agrarian communities in Ghana, West Africa, and to assess the potential human health risks. Settled indoor dust samples were collected from 430 households and subjected to a Liquid Chromatography-Mass Spectrometry/Mass Spectrometry analysis. Following analysis, 10 neonicotinoid compounds and 6 neonicotinoid metabolites were detected, with the following frequency trend: imidacloprid and its 5 associated metabolites (Σ6IMI; detection frequency = 99.07 %) > acetamiprid compounds (Σ2ACE; detection frequency = 93.72 %) > thiamethoxam (89.53 %) > clothianidin (82.09 %) > sulfoxaflor (74.19 %) > imidaclothiz (4.88 %) > thiacloprid (4.42 %) > flupyradifurone (3.95 %) > dinotefuran (3.72 %) > nitenpyram (2.33 %). The median concentrations were as follows: imidacloprid (0.145 µg/g) > thiamethoxam (0.03 µg/g) > acetamiprid (0.014 µg/g) > sulfoxaflor (0.003 µg/g) > clothianidin (0.002 µg/g). Upon exposure assessment, the daily intakes of neonicotinoids were highest in younger populations compared to older ones, with the following values: toddlers (3338118 pg/kg/bw), infants (2677255 pg/kg/bw), children (1072966 pg/kg/bw), teenagers (74368 pg/kg/bw), and adults (53120 pg/kg/bw). However, the maximum hazard quotients for neonicotinoids across all age groups were below 1. Overall, the current study shows extensive indoor contamination by neonicotinoids in the target Ghanaian communities. Although hazard quotients are below unity, the high exposure potentials, especially for children, indicates a need for further toxicological evaluation and long-term environmental health surveillance.
  • Evaluation of ascorbic acid as an intervention of metal toxicity in dogs in Kabwe district.
    Nelly Banda; Mahongo Selwa; Rio Doya; Nyein Chan Soe; Andrew Kataba; John Yabe; Golden Zyambo; Kaampwe Muzandu; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta Mm Nakayama
    Veterinary and animal science, 30, 100519, 100519, Dec. 2025, [International Magazine]
    English, Scientific journal, Non-essential metals and metalloids are known to induce oxidative stress in exposed organisms, often leading to cellular damage and systemic toxicity. While chelation therapy remains the primary treatment for metal toxicity, its application is limited by side effects. L-ascorbic acid (L-AA), a widely available antioxidant, has emerged as a promising nutritional intervention for mitigating metal-induced oxidative stress. Dogs, whose blood lead levels (BLLs) closely mirror those of humans, have been utilized as sentinel species in environmental toxicology studies. This study aimed to evaluate the therapeutic potential of L-AA in dogs residing in Kabwe, Zambia, a former mining town where remediation of heavy metal contamination is ongoing. The reported BLLs in Kabwe dogs ranged from 0.43 µg/dL to 123.5 µg/dL. A total of 22 dogs (10 females and 12 males) received oral L-AA supplementation daily for 14 days. Blood samples were collected on Day 1 of L-AA administration and Day 14 to assess biochemical and toxicological changes. Post-treatment analysis revealed statistically significant reductions in plasma malondialdehyde, cortisol, blood urea nitrogen, and creatinine levels, as determined by Student's t-test and Wilcoxon signed-rank test. Additionally, δ-aminolaevulinic acid dehydratase activity was significantly elevated, indicating improved oxidative status. These findings support the efficacy of L-AA in attenuating oxidative stress associated with metal and metalloid exposure, even in the absence of exposure cessation. Interestingly, Pb levels declined predominantly in dogs younger than 24 months. Furthermore, reductions in Zn and Cu commonly linked to L-AA administration were observed exclusively in male dogs, suggesting a sex-specific response.
  • Technical note: Quantitative and qualitative analysis of diatom testing in methomyl poisoning case.
    Yuko Kihara; Shigeki Tsuneya; Makoto Nakajima; Suguru Torimitsu; Fumiko Chiba; Aki Tanaka; Hiroyuki Tanaka; Keigo Osada; Kanju Saka; Kanako Noritake; Mayumi Ishizuka; Yoshinori Ikenaka; Hirotaro Iwase; Yohsuke Makino
    International journal of legal medicine, 21 Nov. 2025, [International Magazine]
    English, Scientific journal, Diatom testing is conducted in forensic medicine primarily to support the diagnosis of drowning. In our previous study, a large number of diatoms, potentially originating from methomyl, were detected in the lungs of a cat found dead under circumstances suggestive of methomyl poisoning, but not involving drowning or submersion. In the present study, we collected human and animal cases suspected of methomyl poisoning, where the bodies showed no evidence of drowning or submersion. Diatom tests were performed both quantitatively and qualitatively on the gastric contents, lungs, liver, kidney, and fur samples. Quantitative analysis using light microscopy revealed a large number of Stephanodiscus spp., the same genus of diatoms found in methomyl-containing insecticides, in the gastric contents and in some of the lung samples. Although qualitative analysis with electron microscopy did not enable species-level identification, the observed Stephanodiscus spp. were presumed to be fossil species derived from diatomaceous earth. Since diatomaceous earth is sometimes added as a carrier or diluent to concentrate the active ingredient in insecticides, it is possible that diatoms may be present in the bodies of individuals that died from methomyl poisoning. Therefore, relying solely on the quantity of diatoms may result in false-positive diagnoses of drowning. To avoid such misinterpretation, it is essential to perform qualitative analyses to assess the species composition of the diatoms in addition to quantitative assessment.
  • Significant reduction of blood and tissue lead and cadmium concentrations in free-range and broiler chickens through soil remediation with biochar, phosphates, and calcined dolomite: Implications for public health and food safety
    Madalitso Tembo; Andrew Kataba; Nyein Chan Soe; Rio Doya; Richard Musonda; Golden Zyambo; Yoshinori Ikenaka; John Yabe; Kaampwe Muzandu; Mayumi Ishizuka; Shouta M. M. Nakayama
    JOURNAL OF HAZARDOUS MATERIALS ADVANCES, 20, Nov. 2025
    English, Scientific journal
  • Development of a silica gel chromatography-based cleanup method for quantification of polystyrene nanoplastics in tissue samples via pyrolysis-GC/MS
    Yurika Tokunaga; Kosuke Tanaka; Go Suzuki; Nami Shimizu; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka
    JOURNAL OF HAZARDOUS MATERIALS LETTERS, 6, Nov. 2025
    English, Scientific journal
  • Evaluation of neurotoxicity of neonicotinoid insecticides using lipidomics.
    Tomoya Koike; Anri Hirai; Kei Nomiyama; Akihumi Eguchi; Nobuhiko Hoshi; Tetsushi Hirano; Collins Nimako; Yared Beyene Yohannes; Mai Tamba; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Environmental toxicology and chemistry, 44, 11, 3212, 3224, 01 Nov. 2025, [International Magazine]
    English, Scientific journal, Neonicotinoid (NN) pesticides are widely used globally, but recent studies suggest that even nontoxic doses can induce anxiety-like behaviors and alter brain monoamine neurotransmitter levels in mice. Current neurotoxicity assays may fail to detect subtle toxic effects, such as higher brain function abnormalities caused by small molecule disruptions. These findings highlight the need for highly sensitive and reproducible neurotoxicity testing methods. The brain, a lipid-rich organ, relies on lipids for various functions, and disturbances in lipid homeostasis are linked to numerous diseases. This study uses lipidomics to analyze the cerebral cortex of mice exposed to the NN acetamiprid (ACE), aiming to identify lipid biomarkers of neurotoxicity. Thirty 12-week-old male C57BL/6J mice were randomly divided into control (0 mg/kg), low dose (65 mg/kg), and high dose (130 mg/kg) groups, with 10 mice in each group. Mice were euthanized, and cerebral cortex samples were collected 30 min after oral ACE administration. Lipids were extracted and analyzed using liquid chromatography-quadrupole time-of-flight mass spectrometry. A total of 358 lipids were annotated. Fifteen lipids exhibited a fold-change > 2.0 and significant differences between control and high-dose groups, with an area under the curve ≥ 0.900 in receiver operating characteristic analysis. Increased levels of seven fatty acids (FAs; e.g., palmitic acid) and five fatty acyl esters of hydroxy FAs (e.g., FAHFA 22:6_22:5) were observed, suggesting roles in neurodegenerative diseases and inflammation. These findings identify a promising lipid biomarker linked to NN-induced neurotoxicity and contribute to detecting neurotoxic effects from acute exposure to such substances.
  • Risk assessment of polycyclic aromatic hydrocarbons in airborne particulates of Ulaanbaatar City, Mongolia
    Javzandolgor Tserendorj; Jajinjav Yondonjamts; Bolortuya Damdinsuren; Shagjjamba Dagva; Bayanjargal Unenbat; Sukhbaatar Batchuluun; Yared Beyene; Shouta M. M. Nakayama; Mayumi Ishizuka; Chinzorig Radnaabazar; Yoshinori Ikenaka; Munkhbat Byambajav
    AIR QUALITY ATMOSPHERE AND HEALTH, 28 Oct. 2025
    English, Scientific journal
  • Lead Bullet Burden: Widespread Lead Exposure in Wild Carnivores and Unseen Consequences of Feeding Lead-Shot Meat to Captive Cheetahs (Acinonyx jubatus).
    Catherine Hauw; Laurie Marker; John Yabe; María Díez-León; Niall McCann; Gerhard Iiputa; Mark Jago; Esther Mukete-Hilundutah; Trevor Nzehengwa; Nelly Banda; Shouta M M Nakayama; Mayumi Ishizuka; Utarera Katjavivi; Jacqueline Ehrlich; Marc Humphries; Anne Schmidt-Küntzel
    Journal of wildlife diseases, 61, 4, 1038, 1049, 01 Oct. 2025, [International Magazine]
    English, Scientific journal, Lead (Pb) exposure is a global concern because of its harmful effects on the environment, animals, and humans. Although research on Pb poisoning in humans and avian species is extensive, similar literature on mammalian carnivores is limited. Only two reports of suspected Pb poisoning in captive cheetahs (Acinonyx jubatus) exist, and none in wild cheetahs. We quantified cumulative life exposure to Pb in 62 cheetahs (33 males, 29 females) and 11 (unknown sex) leopards (Panthera pardus). Cheetahs were grouped according to time spent in captivity: wild (>10% of life in the wild) and captive (10-100% of life in captivity); all leopards were wild. Bone Pb concentration (BLC) was measured in tibias to assess the effects of time in captivity, age, and sex on Pb exposure. Lead was detected in all cheetah and leopard tibias. Mean BLC was 1.11±1.92 mg/kg for all cheetahs, with a significantly higher mean in captive (1.57±2.25 mg/kg) versus wild (0.27±0.39 mg/kg) cheetahs. Time in captivity had a significant effect on BLC, with BLC increasing with years spent in human care. Wild leopards had a higher BLC than wild cheetahs, with a mean BLC of 1.02±1.56 mg/kg. Higher BLC in captive than wild cheetahs was attributed to Pb exposure from the ammunition used to shoot ungulates for their diet. Increased exposure in wild leopards might be attributable to opportunistic scavenging, a behavior not typically seen in wild cheetahs. This study highlights the need for non-Pb ammunition options in support of conservation, animal welfare, and ultimately human health.
  • Effects of Imidacloprid on Afrotropical Aquatic Ecosystems: A South African Microcosm Study.
    Marelize Marsay; Paul J van den Brink; Collins Nimako; Yoshinori Ikenaka; Mayumi Ishizuka; Victor Wepener
    Integrated environmental assessment and management, 08 Sep. 2025, [International Magazine]
    English, Scientific journal, Pesticides are widely used to meet the food demands of a growing population, with various types used to control pests depending on the crops grown. Rainfall, overspray, and runoff from agricultural fields can wash these insecticides into water bodies, posing documented environmental risks. Imidacloprid is commonly used in Afrotropical regions such as South Africa, yet limited information is available on its toxicity to aquatic ecosystems within this climate region. To address this, a 16-week outdoor microcosm study was conducted, exposing aquatic communities to 0.1, 10 and 250 µg/L imidacloprid under natural conditions. Physicochemical parameters, such as pH, dissolved oxygen, temperature, and various others, were monitored regularly. The microbial community, organic decomposition and zooplankton were largely unaffected by the exposure to imidacloprid. In contrast, 10 and 250 µg/L of imidacloprid led to long-term effects on the macroinvertebrate community, while short-term effects were found in the 0.1 µg/L treatment. Families such as Coenagrionidae were affected across all treatments, while Caenidae and Notonectidae were only affected in the highest treatment. Changes in the community structure resulted in reduced predator abundance (such as Coenagrionidae, Libellulidae and Notonectidae) and increased filter feeders (Culicidae). High temperatures likely increase the toxicity to arthropods when compared to similar studies with lower light intensities and temperatures. Recovery was limited during the post-exposure period, with some families (Baetidae) rebounding quickly, while others, Caenidae and Coenagrionidae, showed delayed recovery. Full recovery of the macroinvertebrate community systems did not occur during the 8-week recovery period, highlighting the importance of unexposed refuges for recolonization. This study provides important field-realistic evidence of the ecological risks associated with imidacloprid use in Southern African freshwater systems.
  • Anthropogenic Activities Elevate Heavy Metals Levels in Soil and Tree Bark; A Case Study of Lower Zambezi and Mosi-Oa-Tunya National Parks.
    Nelly Banda; Kanami Watanabe; Rio Doya; Nyein Chan Soe; Andrew Kataba; John Yabe; Golden Zyambo; Kaampwe Muzandu; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M M Nakayama
    Archives of environmental contamination and toxicology, 89, 2, 180, 194, Aug. 2025, [International Magazine]
    English, Scientific journal, The impact of various human activities on protected environments remains a significant concern. Mining for ores is crucial in many aspects of society. To achieve global decarbonisation, more metals are required, which will lead to increased worldwide metal exploration and mining. Zambia is primarily a mining country and has expanded exploration into protected lands (national parks). The effects of this exploration on these protected areas is ongoing. This study aimed to establish baseline data for monitoring metal pollution in the Lower Zambezi National Park before mining commenced. It also evaluated whether tourism influenced metal pollution in national parks and how these metals and metalloids correlate within tree bark and soils. To accomplish this, soil and Acacia tree bark samples were collected from Lower Zambezi National Park and Mosi-Oa-Tunya National Park. Arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were analysed in this study. The concentrations of metals and metalloids were higher in areas with vehicular traffic and mining activity in the national parks, which may directly impact the biosystems in those areas. Maximum levels of metals in soil in these areas were as follows: As 40.8 mg/kg, Cd 0.879 mg/kg, Cr 241 mg/kg, Hg 1.1 mg/kg, Pb 211 mg/kg, and Zn 1285 mg/kg. When compared to areas of lower anthropogenic activities, differences in metal concentrations were up to 1000-fold. These changes can potentially affect the adaptation of wildlife to various stressors, especially as we are facing global climate change.
  • Pilot-scale stabilization of toxic metal leachates from zinc plant residues using half-burnt dolomite: implications for remediation at Kabwe legacy mine in Zambia
    Walubita Mufalo; Takahiko Arima; Toshifumi Igarashi; Mayumi Ito; Tsutomu Sato; Shingo Tomiyama; Imasiku Nyambe; Marthias Silwamba; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Environmental Geochemistry and Health, 47, 7, Springer Science and Business Media LLC, 16 Jun. 2025
    Scientific journal
  • Lead concentration in blood of Asian black bears in two areas of Central Japan.
    Koji Yamazaki; Mayumi Ishizuka; Shouta M M Nakayama; Nelly Banda; Shinsuke Koike; Yusuke Goto; Kozo Yamazaki; Yui Nemoto; Boris Fuchs; Jon M Arnemo
    The Science of the total environment, 980, 179555, 179555, 10 Jun. 2025, [International Magazine]
    English, Scientific journal, To measure blood lead level, we collected a total of 88 blood samples from 66 Asian black bears (Ursus thibetanus japonicus) that were live-trapped in two study areas in Japan. In both areas, extensive sika deer (Cervus nippon) and wild boar (Sus scrofa) control programs and sport hunting using lead-based ammunition have been conducted. The area in the Ashio-Nikko Mountains is located near a former copper mine and smelter. The Okutama Mountains are situated in the suburbs of Tokyo, a mega-city with a population of nearly 14 million. In both study areas, the use of leaded gasoline was permitted until 1975 for regular gasoline vehicles. Our analysis revealed that Japanese black bears had higher lead compared to American black bears (U. americanus) and brown bears (U. arctos) in North America. Blood lead concentrations were higher in the Ashio-Nikko Mountains (110.4 ± 38.3 SD μg/L) than in the Okutama Mountains (49.3 ± 46.2 SD μg/L). The blood lead concentrations were particularly high in lactating females compared to most males and females. White blood cell count was decreased with increasing blood lead concentration. The source of lead contamination remains unknown at this time. However, Japanese black bears in our study areas commonly scavenge on large mammals, and lead-based ammunition could constitute a significant portion of the contamination in both areas. In addition, former mining activities could elevate the lead concentrations of bears in the Ashio-Nikko Mountains. Atmospheric lead depositions originating from former leaded gasoline use in Japan and current air pollution from the Asian continent are also potential factors in both areas. Future identification of exposure sources is necessary.
  • Exploration of functional cytochrome P450 4F enzymes in liver, intestine, and kidney from dogs, cats, pigs, and tree shrews and comparison of their metabolic capacities with human P450 4F2 and 4F12
    Yasuhiro Uno; Izumi Kawabata; Genki Ushirozako; Kyoko Tsukiyama-Kohara; Mayumi Ishizuka; Hazuki Mizukawa; Norie Murayama; Hiroshi Yamazaki
    Biochemical Pharmacology, 236, 116894, 116894, Elsevier BV, Jun. 2025
    Scientific journal
  • Assessing the efficacy of phosphate and lime amendments in immobilizing three forms of lead in contaminated soil: An in vivo study on C57/BL6 mice simulating environmentally realistic exposure pathways.
    Nyein Chan Soe; Takashi Fujimori; Kenji Shiota; Rio Doya; Walubita Mufalo; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M M Nakayama
    Chemosphere, 374, 144201, 144201, Apr. 2025, [International Magazine]
    English, Scientific journal, Lead (Pb) bioavailability differs depending on the specific Pb species present in the area. Adding organic and inorganic soil amendments can ameliorate the mobility of Pb in the soil. However, there is a scarcity of in vivo studies investigating the impact of these amendments on mammals via environmentally realistic exposure pathways. We evaluated the accumulation of Pb in blood and tissues of mice living on soils spiked with one of three Pb species (hydrocerussite [2PbCO3·Pb(OH)2], lead sulfate [PbSO4], and lead sulfide [PbS]) and compared the efficacy of phosphate (triple super phosphate [TSP] or phosphoric acid) or liming (calcined dolomite) amendments in reducing Pb accumulation from these soils via realistic exposure pathways. The Pb species in the spiked soil were investigated via X-ray absorption near edge structures (XANES) spectroscopy. C57/BL6 mice (six per group) were exposed to both Pb-spiked and amended soils by housing them on the soil for three months and thus simulating realistic exposure pathways. XANES analysis revealed that Pb carbonates were the dominant phase in all Pb-spiked soils. The group exposed to 2PbCO3·Pb(OH)2 had the greatest Pb accumulation in brain, trachea, kidneys, liver, bone, and blood, but not lungs, whereas the PbS-exposed group accumulated more Pb in the lungs. TSP was the most effective chemical stabilizer of the three amendments, facilitating reductions in the 2PbCO3·Pb(OH)2, PbSO4, and PbS exposure groups of 68-88%, 44-62%, and 6-49%, respectively. This suggests that chemical remediation using phosphate sources may be effective for immobilizing various Pb species in soils.
  • Pollution and partitioning of neonicotinoid insecticides in free-grazing ducks and their eggs: Implications for human health.
    Collins Nimako; Kraisiri Khidkhan; Sittinee Kulprasertsri; Saranya Poapolathep; Paphatsara Khunlert; Yared B Yohannes; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka; Amnart Poapolathep
    Environmental pollution (Barking, Essex : 1987), 373, 126099, 126099, 20 Mar. 2025, [International Magazine]
    English, Scientific journal, Neonicotinoid insecticides are used extensively in many pest control schemes across the globe; but little is known about their impacts on free-grazing domestic birds and the quality of meat or eggs produced from such birds. This study assessed the pollution and partitioning of neonicotinoids in serum and eggs of free-grazing ducks from 5 provinces of Thailand and elucidated the associated human health implications. Biological samples (duck serum, egg albumins, and egg yolks) and environmental samples (soil, water, feed) were collected from 9 duck farms in Thailand and subjected to LC/MS/MS analysis. Out of 6 neonicotinoid compounds targeted, five were detected in duck serum. Imidacloprid had the greatest median concentration of 1.4 ng/mL and the highest detection frequency (df) of 85.8 % in the ducks' serum, followed by acetamiprid (median concentration = 0.4 ng/mL; df = 2.8 %), clothianidin (median concentration = 0.2 ng/mL; df = 9.4 %) or thiamethoxam (median concentration = 0.2 ng/mL; df = 7.5 %) and dinotefuran (only one sample was contaminated with 6.3 ng/mL of dinotefuran). The neonicotinoids were similarly detected in soil, water, and feed samples obtained from the duck farms, suggesting that the ducks were exposed to the insecticides from the nearby agricultural fields. The neonicotinoid compounds selectively accumulated in the albumin of duck eggs compared to yolk. The median concentration ratios of albumin to yolk obtained for imidacloprid, dinotefuran, thiamethoxam, clothianidin, and acetamiprid were 694, 463, 458, 382, and 263, respectively. However, upon human health risk analysis, levels of neonicotinoids detected in duck eggs were not found to present any appreciable risks to duck egg consumers.
  • Forensic detection and quantification of methomyl in animal stomach contents using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS) in Japan
    Yared Beyene YOHANNES; Aki TANAKA; Yuko KIHARA; Tsuyoshi TAJIMA; Shouta NAKAYAMA; Collins NIMAKO; Yoshinori IKENAKA; Mayumi ISHIZUKA
    Journal of Veterinary Medical Science, Japanese Society of Veterinary Science, 2025
    Scientific journal
  • Understanding Pb contamination in wild mammals and birds and examining the potential contamination related to ammunition in Japan
    Nana USHINE; Mizuki MARUYAMA; Emmanuel Temiotan OGBOMIDA; Shouta MM NAKAYAMA; Mayumi ISHIZUKA; Takuya KATO; Shin-ichi HAYAMA
    Journal of Veterinary Medical Science, 87, 8, 911, 918, Japanese Society of Veterinary Science, 2025
    Scientific journal
  • Sex dependent intergenerational effects of lead in mouse model.
    Nelly Banda; Nyein Chan Soe; John Yabe; Rio Doya; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M M Nakayama
    Scientific reports, 14, 1, 30233, 30233, 04 Dec. 2024, [International Magazine]
    English, Scientific journal, Lead (Pb) exposure negatively impacts fertility in both males and females, pregnancy outcomes, and child brain development. We investigated the reproductive and neurological effects of Pb exposure on male and female mice via Pb-contaminated soil for 4 weeks. Breeding was conducted after completion of exposure, in four groups; group 1 consisted of exposed dams and unexposed sires, group 2 consisted of exposed sires and unexposed dams, group 3 consisted of exposed sires and exposed dams and group 4 was the control. Generally, Pb exposure reduced observed conception rates, with a cumulative decrement observed when both males and females are exposed. Gene expression of the testes revealed oxidative stress as the cause of reduced conception rates. Neurological tests: Morris water maze and rotarod were conducted on F1 generation offspring. Maternally and paternally exposed F1 mice performed poorly in the Morris water maze when compared to the control. The severity of the neurological effects was also parent-dependent and sex-dependent. Paternal Pb exposure effects were more pronounced in female offspring. A comparison of gene expression changes of the hippocampus and prefrontal cortex showed paternal Pb-exposure resulted in more prefrontal cortex changes than in the hippocampus, a trend also recorded in the exposed sires. The pronounced effects in female offspring of paternal Pb exposure may suggest that Pb neurological effects may be X-chromosome-linked.
  • Habu vipers (Protobothrops flavoviridis) are an overlooked but important reservoir of the zoonotic tick Amblyomma testudinarium (Acari: Ixodidae) in subtropical Asia.
    Mackenzie L Kwak; Shintaro Nakagawa; So Shinya; Paula Andrea Jiménez; Greg Markowsky; Daniel McInnes; Yurie Taya; Shouta M M Nakayama; Mayumi Ishizuka; Nariaki Nonaka; Ryo Nakao
    Acta tropica, 260, 107472, 107472, 17 Nov. 2024, [International Magazine]
    English, Scientific journal, Subtropical Asia has a rich diversity of reptiles and ticks, though the role of reptiles in the sylvatic cycles of medically important ticks in the region is poorly known. Habu vipers (Protobothrops flavoviridis) are widespread and common in the Japanese subtropics but their role as hosts for ticks has not been carefully explored. For 15 months in 2023/24, habu vipers were screened for ticks and were found to be important hosts for immature stages of the tick Amblyomma testudinarium, with a 22 % infestation rate. Amblyomma testudinarium was found to have weak attachment site preferences on P. flavoviridis and host body length was found to have no relationship with either the risk of infestation or the tick load in infested snakes. The phenological profile of A. testudinarium was mapped for the first time in the subtropics based on mean tick loads on P. flavoviridis and historical flagging data. March-April were identified as the period of highest activity, May to July was a period of declining activity, August-September was a period of almost complete inactivity, and October to February was a periods of increasing activity. The role of habu vipers in the sylvatic cycle of A. testudinarium in subtropical Asia is discussion. Additionally, the potential of habu vipers to serve as reservoirs of pathogens or as dilution hosts is also explored.
  • Investigating drug residues in Mongolian milk using a newly developed method with high performance liquid chromatography and a photo diode array.
    Delgermurun Dugar; Kodai Motohira; Nyamsuren Purevdorj; Bolormaa Pelden; Shouta Mm Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    The Journal of veterinary medical science, 14 Oct. 2024, [Domestic magazines]
    English, Scientific journal, Despite the beneficial impacts of using drugs in animal husbandry, the risks of drug residues in animal products are a concern worldwide. Therefore, most countries have developed systems and methods to detect and monitor drug residues in animal products using high performance liquid chromatography (HPLC) with mass spectrometry (MS). However, MS detectors are not available in all universities; thus, we developed a new method suitable for ultraviolet detection. We first validated a new method targeting tetracycline and albendazole in milk and evaluated these drug residues in 50 samples collected from farms and supermarkets in Mongolia. The practical limit of quantification (PQL) calculated in our newly developed method was suitable to detect the maximum residual limits defined in Codex Alimentarius, and the accuracy and precision of a new method were comparable to previous studies. In particular, inter-day analysis showed great precision, with albendazole showing a 99% recovery rate with ± 3.3 of relative standard deviation (RSD). In addition, we evaluated our drugs contamination, but targeted drugs residues were not detected in the current sample set. However, this may reflect the decreased use of tetracycline in the veterinary field and seasonal use of albendazole in Mongolia. Therefore, these drugs must be continuously monitored. To the best of our knowledge, this is the first report about drug residues in milk published in an international journal by a Mongolian domestic institution. Further investigations of drug residue in Mongolia are urgently needed.
  • Investigation of Functional Cytochrome P450 4A Enzymes in Liver and Kidney of Pigs, Cats, Tree Shrews, and Dogs in Comparison with the Metabolic Capacity of Human P450 4A11
    Yasuhiro Uno; Kyoko Tsukiyama-Kohara; Mayumi Ishizuka; Hazuki Mizukawa; Norie Murayama; Hiroshi Yamazaki
    Drug Metabolism and Disposition, 52, 9, 1009, 1019, 01 Sep. 2024
    Scientific journal
  • Characterization of Neonicotinoid Metabolites by Cytochrome P450-Mediated Metabolism in Poultry.
    Adisorn Dam-On; Collins Nimako; Sittinee Kulprasertsri; Yoshinori Ikenaka; Yared B Yohannes; Shouta M M Nakayama; Mayumi Ishizuka; Saranya Poapolathep; Amnart Poapolathep; Kraisiri Khidkhan
    Toxics, 12, 8, 21 Aug. 2024, [International Magazine]
    English, Scientific journal, Neonicotinoids, a neuro-effective class of insecticides, are heavily applied in agricultural activities worldwide. Poultry can be exposed to neonicotinoids by several routes, but the knowledge of neonicotinoid's metabolism in poultry and its associated interspecies differences is highly limited. Hence, this study aims to investigate the species differences in metabolite formations, as well as cytochrome P450 (CYP)-dependent metabolism of four major neonicotinoid compounds, acetamiprid, imidacloprid, clothianidin, and thiamethoxam, in poultry. In vitro biotransformation assays using hepatic microsomes of chicken, ducks, geese, quails, and rats were conducted. Metabolites of neonicotinoids were then screened by LC/Q-TOF and quantified by LC/MS/MS. The results revealed an existence of interspecies differences in the formations of N-[(6-chloro-3-pyridyl) methyl] -N-methyl acetamidine (IM-1-5) of acetamiprid and dm-clothianidin of clothianidin between chicken and other species. In addition, the greatest CYP activities in the metabolism of most neonicotinoid substrates, such as acetamiprid to dm-acetamiprid, imidacloprid to hydroxylated-imidacloprid and imidacloprid-olefin, clothianidin to dm-clothianidin, and thiamethoxam to clothianidin, were found in chicken. These results suggested that the CYPs in chicken may have a greater capacity for metabolism of neonicotinoids compared to other poultry. This study further revealed that the maximum intrinsic clearance of dn-imidacloprid and dn-clothianidin in ducks may be superintended by CYP-mediated nitro-reductions of imidacloprid and clothianidin. Further studies employing CYP recombinant enzymes may be required to elucidate the specific CYP isoforms that may be involved in neonicotinoid metabolism in avian species.
  • Anticoagulant rodenticides exposure status among wild pit vipers (Protobothrops flavoviridis) and green anoles (Anolis carolinensis) in two Japanese Islands
    Yoshiya Yamamura; Shintaro Nakagawa; Mitsuki Kondo; So Shinya; Rio Doya; Masashi Koide; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M. M. Nakayama
    EUROPEAN JOURNAL OF WILDLIFE RESEARCH, 70, 3, Jun. 2024
    English, Scientific journal
  • Role of brain monoamines in acetamiprid-induced anxiety-like behavior.
    Anri Hirai; Chitoku Toda; Yared Beyene Yohannes; Nimako Collins; Mai Tamba; Kei Nomiyama; Akifumi Eguchi; Nobuhiko Hoshi; Tetsushi Hirano; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Toxicology, 153839, 153839, 21 May 2024, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Neonicotinoid (NN) pesticides have been linked to increased brain dysfunction in mammals, such as anxiety-like behavior; this is thought to involve monoamines (MA), neurotransmitters that control behavior, memory, and learning. However, the mechanism by which NNs affect the central nervous system is not fully understood. In this study, we aimed to investigate whether MAs affect NNs-induced anxiety-like behavior. Mice were orally administered acetamiprid (ACE), an NN, at the no observed adverse effect level (NOAEL) of mouse (20mg/kg body mass) set by the Food Safety Commission of Japan, and the elevated zero-maze (EZM) test was performed 30min after administration. After behavioral analysis, levels of four MA (dopamine, 3-MT, serotonin, and histamine) in selected brain regions were determined by liquid chromatography mass spectrometry (LC/MS/MS). In the exposed group, a trend toward increased anxiety-like behavior was observed, and at least one MA concentration was significantly increased in each region. Further, significant correlations were found between behavioral test results and hippocampal serotonin and striatal dopamine concentrations, as well as between dopamine and serotonin concentrations, in the exposed group. As anxiety can influence activity in the behavioral tests, the activity of neurons in the raphe nuclei (RN), a brain region greatly involved in anxiety via the serotonergic system, was examined by staining with anti-serotonin antibodies, and increased serotonergic activity was observed. Taken together, these results suggest that ACE regulates MA levels, notably serotonin levels in the hippocampus and that RN plays an important role in ACE-induced anxiety-like behavior.
  • オオミズナギドリにおける血球と羽根の水銀濃度
    岩崎真由; 安積紗羅々; 石塚真由美; 池中良徳; 綿貫豊
    日本鳥学会誌, 73, 57, 65, May 2024, [Peer-reviewed]
    Japanese
  • Exposure of Male Farmers and Nonfarmers to Neonicotinoid Pesticides in the South-West and Littoral Regions of Cameroon: A Comparative Study.
    Faustin Pascal Tsagué Manfo; Collins Nimako; Edouard Akono Nantia; Christian Fusi Suh; Shu Policap Chenwi; Fidelis Cho-Ngwa; Paul Fewou Moundipa; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Environmental toxicology and chemistry, 43, 5, 952, 964, May 2024, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Pesticides, especially the newly developed neonicotinoids, are increasingly used in many countries around the world, including Cameroon, to control pests involved in crop destruction or disease transmission. Unfortunately, the pesticides also pose tremendous environmental problems because a predominant amount of their residues enter environmental matrices to affect other nontargeted species including humans. This therefore calls for continuous biomonitoring of these insecticides in human populations. The present study sought to assess the neonicotinoid insecticide exposures in two agrarian regions of Cameroon, the South-West region and Littoral region. The study involved 188 men, including 125 farmers and 63 nonfarmers. Spot urine samples were obtained from these subjects and subjected to liquid chromatographic-tandem mass spectrometric analysis for concentrations of neonicotinoid compounds, including acetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, nitenpyram, thiamethoxam, and N-dm-acetamiprid. Neonicotinoid compounds were detected in all study participants, and residues of all the screened pesticides were detected among participants. N-dm-Acetamiprid and imidacloprid were the most prevalent among the subjects (100.0% and 93.1%, respectively), whereas nitenpyram was less common (3.2%). The median values of imidacloprid and total urinary neonicotinoid concentrations were elevated among farmers (0.258 vs. 0.126 µg/L and 0.829 vs. 0.312 µg/L, respectively). Altogether the findings showed that both the farmer and nonfarmer study populations of Cameroon were exposed to multiple residues of neonicotinoids, with relatively higher levels of pesticides generally recorded among farmers. Although exposure levels of the neonicotinoids were generally lower than their respective reference doses, these results warrant further research on the health risk evaluation of multiple residues of the pesticides and reinforcement of control measures to minimize the exposure risks, especially among farmers. Environ Toxicol Chem 2024;43:952-964. © 2024 SETAC.
  • Current situation of lead (Pb) exposure in raptors and waterfowl in Japan and difference in sensitivity to in vitro lead exposure among avian species.
    Mizuki Maruyama; Nana Ushine; Yukiko Watanabe; Chihiro Ishii; Keisuke Saito; Hidefumi Sakai; Takeshi Kuritani; Rio Doya; Kohei Ogasawara; Yoshinori Ikenaka; Yared Beyene Yohannes; Mayumi Ishizuka; Shouta M M Nakayama
    Environmental pollution (Barking, Essex : 1987), 123907, 123907, 04 Apr. 2024, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Although lead (Pb) poisoning in wild birds has been considered a serious problem in Japan for over 30 years, there is little information about Pb exposure and its sources throughout Japan except for Hokkaido. Furthermore, to identify and effectively prioritize the conservation needs of highly vulnerable species, differences in sensitivity to Pb exposure among avian species need to be determined. Therefore, we investigated the current situation of Pb exposure in raptors (13 species, N = 82), waterfowl (eight species, N = 44) and crows (one species, N = 6) using concentration and isotope analysis. We employed blood or tissue samples collected in various Japanese facilities mainly in 2022 or 2023. We also carried out a comparative study of blood δ-ALAD sensitivity to in vitro Pb exposure using blood of nine avian species. Pb concentrations in the blood or tissues displayed increased levels (>0.1 μg/g blood) in two raptors (2.4%), ten waterfowl (23%) and one crow (17%). Among them, poisoning levels (>0.6 μg/g blood) were found in one black kite and one common teal. The sources of Pb isotope ratios in ten blood samples with high Pb levels were determined as deriving from shot pellets (N = 9) or rifle bullets (N = 1). In the δ-ALAD study, red-crowned crane showed the highest sensitivity among the nine tested avian species and was followed in order by five Accipitriformes species (including white-tailed and Steller's sea eagle), Blakiston's fish owl, Muscovy duck and chicken, suggesting a genetically driven variance in susceptibility. Further studies on contamination conditions and exposure sources are urgently needed to inform strict regulations on the usage of Pb ammunition. Furthermore, detailed examinations of δ-ALAD sensitivity, interspecific differences, and other factors involved in the variability in sensitivity to Pb are required to identify and prioritize highly sensitive species.
  • Effect of chicken manure amendment on lead burden in mice: exposure to lead-spiked soil
    Nyein Chan Soe; Yared Beyene Yohannes; Takamitsu Ohigashi; Hokuto Nakata; Chikae Tatsumi; Yoshitaka Uchida; Walubita Mufalo; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M. M. Nakayama
    Journal of Soils and Sediments, Springer Science and Business Media LLC, 13 Mar. 2024, [Peer-reviewed]
    Scientific journal
  • Pesticide Contamination Levels in the Stomach Contents of Wild Raccoons (Procyon lotor) and Masked Palm Civets (Paguma larvata) in Japan
    So Shinya; Mariko Sashika; Miku Minamikawa; Tetsuji Itoh; Tsutomu Tanikawa; Kazuyuki D. Tanaka; Shouta M. M. Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Environmental Toxicology and Chemistry, Wiley, 05 Mar. 2024, [Peer-reviewed]
    Scientific journal, Abstract

    Pesticides, which are vital for agriculture, pose a significant threat to wildlife in transformed Japanese landscapes. Despite global reports of pesticide poisoning in animals, limited studies have examined current wildlife exposure in croplands or metropolitan areas in the region. Using liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–tandem mass spectrometry (GC–MS/MS), our study aimed to assess the contamination status of 368 commonly used pesticides. The stomach contents of raccoons living in croplands contained 13 pesticides, including six herbicides and 11 fungicides. Neonicotinoid insecticides, some fungicides, and previously banned insecticides (benzene hexachloride and dichlofenthion) were most frequently detected and found at the highest concentrations, suggesting direct soil–plant transfer and direct consumption by crop‐eating species. In masked palm civets living in metropolitan areas, four insecticides and six fungicides were detected, indicating urban wildlife exposure from raided dustbins, urban gardens, and lumber from houses. Although the maximum measured concentrations of all pesticides were lower than the acceptable daily intake for humans, it remains unclear whether these concentrations may have toxic or adverse health effects on the species evaluated in these transformed landscapes. Our study is the first to examine recent pesticide exposures in wild mammals in Japan. Application of the method we developed will lay the foundation for the examination of pesticides in other wildlife species to assist conservation management efforts in the region. Environ Toxicol Chem 2024;00:1–9. © 2024 SETAC
  • Quantification of the tissue distribution and accumulation of the neonicotinoid pesticide clothianidin and its metabolites in maternal and fetal mice.
    Tetsushi Hirano; Shuji Ohno; Yoshinori Ikenaka; Kanoko Onaru; Shizuka Kubo; Yuka Miyata; Mizuki Maeda; Youhei Mantani; Toshifumi Yokoyama; Collins Nimako; Yared Beyene Yohannes; Shouta M M Nakayama; Mayumi Ishizuka; Nobuhiko Hoshi
    Toxicology and applied pharmacology, 116847, 116847, 07 Feb. 2024, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Neonicotinoids (NNs) are commonly used pesticides that have a selective agonistic action on insect nicotinic acetylcholine receptors. Recent evidence has shown that NNs have adverse effects in the next generation of mammals, but it remains unclear how NNs transferred from dams to fetuses are distributed and accumulated in fetal tissues. Here, we aimed to clarify the tissue distribution and accumulation properties of the NN clothianidin (CLO) and its 6 metabolites in 7 tissues and blood in both dams and fetuses of mice administered CLO for a single day or for 9 consecutive days. The results showed that the total concentrations of CLO-related compounds in the brain and kidney were higher in fetuses than in dams, whereas in the liver, heart, and blood they were lower in fetuses. The multi-day administration increased the total levels in heart and blood only in the fetuses of the single administration group. In addition, dimethyl metabolites of CLO showed fetus/dam ratios >1 in some tissues, suggesting that fetuses have higher accumulation property and are thus at higher risks of exposure to CLO-related compounds than dams. These findings revealed differences in the tissue-specific distribution patterns of CLO and its metabolites between dams and fetuses, providing new insights into the assessment of the developmental toxicity of NNs.
  • Insights on hazardous metal bioaccessibility, and groundwater impacted by Zn residues from a legacy mine and risk evaluation of adjacent soils
    Walubita Mufalo; Takahiko Arima; Toshifumi Igarashi; Mayumi Ito; Tsutomu Sato; Shingo Tomiyama; Imasiku Nyambe; Carlito Baltazar Tabelin; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Environmental Geochemistry and Health, 46, 2, Springer Science and Business Media LLC, 06 Feb. 2024, [Peer-reviewed]
    Scientific journal
  • Metals and arsenic distribution in stray dogs' tissues around a lead-zinc mine in Kabwe, Zambia.
    Nyein Chan Soe; Yared Beyene Yohannes; Andrew Kataba; Madalitso Tembo; John Yabe; Golden Zyambo; Kenneth Chawinga; Kaampwe Muzandu; Yoshinori Ikenaka; Mayumi Ishizuka; Shouta M M Nakayama
    Environmental science and pollution research international, 31, 8, 12083, 12093, Feb. 2024, [International Magazine]
    English, Scientific journal, Metal contamination poses a threat to human, animal, and environmental health. The purpose of the current study was to assess the accumulation of toxic and trace metal concentrations in tissues of stray dogs in Kabwe, a town known for lead pollution due to a long history of lead and zinc mining. Brain, spleen, heart, stomach, stomach content, small intestine, kidney, liver, and bone samples were collected from 29 stray dogs (14 from locations within 3 km of the mine and 15 from sites 7 km away from the mine) after necropsy. Inductively coupled plasma mass spectrometry was used to analyze toxic metals, arsenic (As), cadmium (Cd), and lead (Pb), and trace elements, copper (Cu) and zinc (Zn). The lungs (0.117 ± 0.114 mg/kg dry weight), kidney (7.515 ± 8.830 mg/kg dry weight), and bone (41.68 ± 66.83 mg/kg dry weight) were found to have the highest concentrations of As, Cd, and Pb, respectively. In contrast, higher Cu and Zn concentrations were measured in the liver than in other tissues. In all tissues analyzed, tissues sampled from dogs near the mine had significantly higher mean concentrations of Cd and Pb than dogs far away. Neither sex nor age-related differences were observed in the distribution of metals in most tissues. There were significant associations among toxic (Pb and Cd) and trace metals (Cu and Zn). In the kidney, Cd positively correlated with Pb (ρ = 0.534) and Zn (ρ = 0.600), whereas in the liver, Cu correlated with Zn (ρ = 0.565). The current study's findings suggest that environmental pollution is still a problem in Kabwe, and environmental remediation is needed to address the pollution.
  • Brood patch size as a field indicator for feather mercury concentration, but not plastic ingestion, in a harvested seabird of the high Arctic: The little auk Alle alle
    Mayuko Otsuki; Monica Ogawa; Watanuki Yutaka; Yoko Mitani; Mayumi Ishizuka; Yoshinori Ikenaka; Jean-Baptiste Thiebot
    Polar Science, Feb. 2024
    Scientific journal
  • Lead speciation in body tissues, gastrointestinal contents, and feces of lead-exposed wild rats (Rattus rattus)
    Takashi Fujimori; Haruya Toyomaki; Kenji Shiota; Hokuto Nakata; John Yabe; Kaampwe Muzandu; Kenneth Chawinga; Rio Doya; Nyein Chan Soe; Mayumi Ishizuka; Shouta M.M. Nakayama
    Science of The Total Environment, 908, 168297, 168297, Elsevier BV, Jan. 2024
    Scientific journal
  • 半焼成ドロマイトおよびリン酸塩を用いたカブウェ鉱山鉱さい中の重金属不溶化特性
    Takahiko ARIMA; Kenta NOTO; Walubita MUFALO; Toshifumi IGARASHI; Mayumi ITO; Tsutomu SATO; Hokuto NAKATA; Shouta NAKAYAMA; Mayumi ISHIZUKA
    Resources Processing, 70, 3, 141, 150, The Resources Processing Society of Japan, 2024
    Scientific journal
  • Assessment of Organohalogen Compounds Contamination in Pet Food and Associated Health Risks: A Case Study in Japan
    Kei NOMIYAMA; Fuka SATO; Makoto SHIMASAKI; Hazuki MIZUKAWA; Kraisiri KHIDKHAN; Yoshinori IKENAKA; Mayumi ISHIZUKA
    Environmental Monitoring and Contaminants Research, 4, 38, 54, Japan Society for Environmental Chemistry, 2024, [Peer-reviewed]
    Scientific journal
  • Evaluation of anticoagulant rodenticide sensitivity by examining in vivo and in vitro responses in avian species, focusing on raptors
    Kraisiri Khidkhan; Fuyu Yasuhira; Aksorn Saengtienchai; Chaiyan Kasorndorkbua; Ratiwan Sitdhibutr; Kohei Ogasawara; Hikaru Adachi; Yukiko Watanabe; Keisuke Saito; Hidefumi Sakai; Kazuo Horikoshi; Hajime Suzuki; Yusuke K. Kawai; Kazuki Takeda; Yared B. Yohannes; Yoshinori Ikenaka; Barnett A. Rattner; Mayumi Ishizuka; Shouta M.M. Nakayama
    Environmental Pollution, 122837, 122837, Elsevier BV, Nov. 2023, [Peer-reviewed]
    Scientific journal
  • Surveys of eleven species of wild and zoo birds and feeding experiments in white-tailed eagles reveal differences in the composition of the avian gut microbiome based on dietary habits between and within species.
    Kohei Ogasawara; Naoki Yamada; Shouta Mm Nakayama; Yukiko Watanabe; Keisuke Saito; Akane Chiba; Yoshitaka Uchida; Kaoru Ueda; Yasunori Takenaka; Kentaro Kazama; Mami Kazama; Junya Yamagishi; Hazuki Mizukawa; Yoshinori Ikenaka; Mayumi Ishizuka
    The Journal of veterinary medical science, 31 Oct. 2023, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, The composition of the gut microbiome varies due to dietary habits. We investigated influences of diet on the composition of the gut microbiome using the feces of 11 avian species, which consumed grain-, fish- and meat-based diets. We analyzed gut microbiome diversity and composition by next-generation sequencing (NGS) of 16S ribosomal RNA. The grain-diet group had higher gut microbiome diversity than the meat- and fish-diet group. The ratio of Bacteroidetes and Firmicutes phyla was higher in the grain-diet group than in the meat- and fish-diet groups. The grain-diet group had a higher ratio of Veillonellaceae than the meat-diet group and a higher ratio of Eubacteriaceae than the fish-diet habit group. To clarify the influence of diet within the same species, white-tailed eagles (Haliaeetus albicilla, n=6) were divided into two groups, and given only deer meat or fish for approximately one month. The composition of the gut microbiome of individuals in both groups were analyzed by NGS. There were indications of fluctuation in the levels of some bacteria (Lactobacillus, Coriobacteriales, etc.) in each diet group. Moreover, one individual for each group which switched each diet in last week changed to each feature of composition of bacterial flora. The above results show that the composition of the gut microbiome differ depending on diet, even within the same species.
  • A stable isotope analysis of the dietary patterns of the aquatic apex predator, the African tigerfish (Hydrocynus vittatus).
    Ruan Gerber; Lizaan de Necker; Johan H J van Vuren; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka; Victor Wepener; Nico J Smit
    Journal of fish biology, 27 Jul. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Stable isotope analyses, specifically δ13 C and δ15 N, are useful tools increasingly used to understand ecosystem function, food web structures and consumer diets. Although the iconic tigerfish, Hydrocynus vittatus, is regarded as an apex predator in southern African freshwater systems, little information is available regarding their feeding behaviour and how this may change with growth or differ between ecosystems with most information stemming from stomach content analyses (SCA). The aim of the present study was to address this lack of information through a baseline study of the diet of large and small tigerfish in various lentic and lotic ecosystems in South Africa using stable isotope methods. Fish and various food web components and food sources were collected from two river and two lake ecosystems from the Lower Phongolo River floodplain, SA. The δ13 C and δ15 N values for all samples were determined and multivariate analyses and Bayesian analytical techniques applied to determine the feeding ecology of H. vittatus and how this may differ with size and habitat type. Analyses revealed a substantial difference in the type and abundance of food sources contributing to the diet of H. vittatus between ecosystems, most prominently between the lotic systems, where less dietary specialisation was observed, and lentic systems where more specialisation was observed. Furthermore, there was a distinct difference in diet between small and large tigerfish, especially in the lotic system, indicating an ontogenetic diet shift as tigerfish grow and further supporting previous SCA studies. This is the first study of its kind on the African continent for H. vittatus and the findings illustrate the value of stable isotope analysis in providing in-depth information into the feeding ecology of consumers and how this may differ between size classes and habitat types. This article is protected by copyright. All rights reserved.
  • Evaluation of the Effect of Pb Pollution on Avian Influenza Virus-Specific Antibody Production in Black-Headed Gulls (Chroicocephalus ridibundus)
    Nana; Makoto Ozawa; Shouta; Mayumi Ishizuka; Takuya Kato; Shin-ichi Hayama
    Animals, Jul. 2023, [Peer-reviewed]
    Scientific journal
  • A Comparative Genomic and Phylogenetic Investigation of the Xenobiotic Metabolism Enzymes of Cytochrome P450 in Elephants Shows Loss in CYP2E and CYP4A.
    Kanami Watanabe; Mitsuki Kondo; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka
    Animals : an open access journal from MDPI, 13, 12, 09 Jun. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Cytochrome P450 is an important enzyme that metabolizes a variety of chemicals, including exogenous substances, such as drugs and environmental chemicals, and endogenous substances, such as steroids, fatty acids, and cholesterol. Some CYPs show interspecific differences in terms of genetic variation. As little is known about the mechanisms of elephant metabolism, we carried out a comparative genomic and phylogenetic analysis of CYP in elephants. Our results suggest that elephant CYP genes have undergone independent duplication, particularly in the CYP2A, CYP2C, and CYP3A genes, a unique cluster specific to elephant species. However, while CYP2E and CYP4A were conserved in other Afrotheria taxa, their decay in elephants resulted in genetic dysfunction (pseudogene). These findings outline several remarkable characteristics of elephant CYP1-4 genes and provide new insights into elephant xenobiotic metabolism. Further functional investigations are necessary to characterize elephant CYP, including expression patterns and interactions with drugs and sensitivities to other chemicals.
  • Estimation of the relationship between Pb contamination and feeding history of black-headed gulls (Chroicocephalus ridibundus) using stable isotopes
    Nana Ushine; Shouta MM Nakayama; Mayumi Ishizuka; Takuya Kato; Shin-ichi Hayama
    Japanese Journal of Environmental Toxicology, 26, 25, 37, Jun. 2023, [Peer-reviewed]
    English, Scientific journal
  • Immobilization of Pb and Zn leached from mining residue materials in Kabwe, Zambia: Performance of calcined dolomite in column experiments
    Walubita Mufalo; Pawit Tangviroon; Takahiko Arima; Toshifumi Igarashi; Mayumi Ito; Tsutomu Sato; Kenta Noto; Takeshi Kawashima; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Journal of Geochemical Exploration, 249, 107209, 107209, Elsevier BV, Jun. 2023, [Peer-reviewed]
    Scientific journal
  • Association between Chronic Environmental Lead (Pb) Exposure and Cytokines in Males and Females of Reproductive Age from Kabwe, Zambia.
    Andrew Kataba; Yared Beyene Yohannes; Hokuto Nakata; John Yabe; Haruya Toyomaki; Kaampwe Muzandu; Golden Zyambo; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka; Shouta M M Nakayama
    International journal of environmental research and public health, 20, 8, 20 Apr. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Lead (Pb) poisoning remains a great public health challenge globally known to induce a wide range of ailments in both children and adults. The current study investigated the association of chronic environmental Pb exposure and immunomodulatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin-8 (IL-8) in adult males and females living in Kabwe, Zambia. The standard human cytokine/chemokine Milliplex assay was used to quantify plasma cytokines from four groups categorized as low (<10 μg/dL) and high (>10 μg/dL) blood lead level (BLL) groups, namely, low BLL female (n = 47; BLL = 3.76 μg/dL), low BLL Male (n = 43; BLL = 4.13 μg/dL), high BLL female (n = 21; BLL = 23.5 μg/dL), and high BLL male (n = 18; BLL = 23.7 μg/dL), respectively. The low BLL group was associated with increased TNF-α levels, and the high BLL group was associated with reduced TNF-α levels in female subjects. No associations between BLL and the levels of IL-8 and TNF-α cytokines were observed in either females or males, respectively. A negative correlation between BLL and TNF-α was found in female subjects, suggesting that an increase in BLL accompanied by a reduction in TNF-α. The reduced levels of circulating TNF-α in female subjects suggest that chronic Pb exposure could predispose females to immune and inflammation-related disorders than their male counterparts. Further studies are recommended to ascertain the impact of chronic Pb exposure on immunomodulatory cytokines, especially in females.
  • X-ray analytic microscopy with CT-guided sample extraction to analyze potential projectile fragments in a dead serow.
    Yuko Kihara; Yohsuke Makino; Masaaki Yokoyama; Fumiko Chiba; Aki Tanaka; Shouta M M Nakayama; Shin-Ichi Hayama; Mayumi Ishizuka; Kurt B Nolte; Hirotaro Iwase
    Legal medicine (Tokyo, Japan), 63, 102257, 102257, 11 Apr. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, In forensic pathology, it is important to detect and recover as evidence residual metal particles and projectiles when evaluating potential gunshot wounds. This process can be challenging when the bullets are fragmented. This report presents our experience using multiple modalities to analyze the wound of an illegally killed Japanese serow (Capricornis crispus) found in a mountainous region without its head and hind limbs. We performed postmortem computed tomography (PMCT) and necropsy that showed a distant-range gunshot wound of the neck likely created by a centerfire rifle. A postmortem cut through the neck and absent head precluded a complete evaluation. To determine the composition of the metal-like fragments in the neck, sampling and metal analysis were performed in two ways. Samples extracted from the exposed wound surface without CT guidance were analyzed directly using inductively coupled plasma mass spectrometry (ICP-MS). Samples from the bone, muscles, and cervical cord extracted under CT guidance were analyzed using x-ray analytic microscopy (XGT-9000, HORIBA, Kyoto, Japan). In wound surface samples, silicon and iron were detected as the main components on ICP-MS, suggesting that the materials were gravel. The samples taken under CT guidance and analyzed with XGT-9000 revealed that the high-density CT areas were mainly composed of lead. Combining CT-guided sample extraction and XGT-9000 can be useful for retrieving true projectile fragments and avoiding the confusion created by erroneously sampling non-projectile surface materials.
  • Effects of Diazinon Exposure on Urinary Shedding of Leptospira interrogans Serogroup Hebdomadis in Mice
    So Shinya; Devinda S. Muthusinghe; Nobuo Koizumi; Kumiko Yoshimatsu; Shouta M. M. Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Toxics, 11, 4, 11 Apr. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Wild rodents are natural hosts of Leptospira spp. and are exposed to various pesticides, some of which are immunotoxic. Rodent urine is an important source of infection for humans and other animals. We evaluated the effects of pesticide exposure on Leptospira growth in mice. Diazinon, at doses of 0.2, 1, and 5 mg/kg/day, was orally administered continuously to mice infected with Leptospira interrogans serogroup Hebdomadis for 32 days. The numbers of L. interrogans in urine and kidney tissues were significantly lower in mice exposed to 5 mg/kg/day diazinon than in unexposed mice (p < 0.05). The urinary concentration of 2-isopropyl-6-methyl-4-pyrimidinol, the metabolite of diazinon, was comparable with the concentration at which viability of L. interrogans was decreased in in vitro assay, suggesting that it had toxic effects on L. interrogans in the proximal renal tubules. Diazinon exposure reinforced Leptospira-induced expression of inflammatory cytokine genes in kidney tissues, and an enhanced immune system might suppress Leptospira growth. These results suggest that diazinon exposure may not increase the risk of Leptospira transmission to humans through mice. This novel study evaluated the relationship between pesticide exposure and Leptospira infection in mice, and the results could be useful for risk assessment of leptospirosis.
  • Characteristics of tissue distribution, metabolism, effects on brain catecholamines, and environmental exposure of frogs to neonicotinoid insecticides.
    So Shinya; Fumiya Nishibe; Yared Beyene Yohannes; Mayumi Ishizuka; Shouta M Nakayama; Yoshinori Ikenaka
    Aquatic toxicology (Amsterdam, Netherlands), 257, 106437, 106437, Apr. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Pesticide exposure is considered to be one important factor responsible for declining amphibian populations worldwide. The usage of neonicotinoid insecticides (NNIs) has markedly increased in recent years, and there are concerns regarding the effects of NNI-induced toxicity on the development and behavior of amphibians. However, there have been few reports on the metabolism, distribution, and neurotoxicity of NNIs in amphibians. In this study, we exposed the Western clawed frog (Silurana tropicalis) to clothianidin (CLT) in water. After 24 h of exposure, the highest concentrations were detected in the skin, indicating that frogs are at a high risk of absorbing CLT through their skin along with water. Excretion of CLT was estimated based on the concentrations of CLT metabolites in the water until 48 h of exposure. The findings showed that frogs had higher CLT metabolic ability than zebrafish. Serotonin levels in the brain were lower in the high-concentration CLT exposure group than in the control group, although the difference was not statistically significant. This suggested that catecholamine-related effects of CLT on the brain cannot be disregarded. In addition, quantitative analyses of NNI residue in wild frogs, soil, and water in agricultural areas in Hokkaido, Japan, were performed and four NNIs were detected. These results indicated the possible risk of NNI-induced toxicity in frogs. This is the first report of the characteristics of tissue distribution and metabolism of NNIs in frogs, which may facilitate the design of appropriate conservation programs for amphibians.
  • Characteristics of cytochrome P450-dependent metabolism against acetamiprid in the musk shrew (Suncus murinus).
    So Shinya; Yusuke Kawai; Mitsuki Kondo; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 265, 109537, 109537, Mar. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Soricidae spp. (shrews) play an essential role in soil ecosystems and, due to their habitat and behavior, are exposed to soil pollutants, such as pesticides. Still, toxicity risk in Soricidae spp. has not been appropriately assessed. In this study, the musk shrew (Suncus murinus) was used as a model organism for toxicity assessment in Soricidae. Considering their carnivorous diet, it is reasonable to assume that the musk shrew has unique metabolic traits that are different from those of other common experimental models. This study describes the cytochrome P450 (CYP)-dependent metabolism affected by acetamiprid (ACP), a neonicotinoid insecticide. Pharmacokinetics analysis, an in vitro metabolic assay, and genetic analysis of CYP were performed and compared with data from mice and rats. Through phylogenetic and syntenic analyses, three families of CYP were identified in the musk shrew. Pharmacokinetic analysis showed that the blood concentration of ACP decreased more quickly in musk shrews than in mice. Moreover, the in vitro metabolic assay suggested more efficient metabolic responses toward ACP in musk shrews than in mice or rats. One of the CYP2A isoforms in musk shrews might be linked to a better ACP metabolism. From the results above, we describe novel metabolic traits of the musk shrew. Future research on recombinant CYP enzymes is necessary to fully understand CYP-dependent metabolism of xenobiotics in musk shrews.
  • Social cost of mining-related lead (Pb) pollution in Kabwe, Zambia, and potential remediation measures
    Daichi Yamada; Masato Hiwatari; Daiju Narita; Peter Hangoma; Bona Chitah; Hokuto Nakata; Shouta M.M. Nakayama; John Yabe; Mayumi Ito; Toshifumi Igarashi; Mayumi Ishizuka; Golden Zyambo
    Science of The Total Environment, 865, 161281, 161281, Elsevier BV, Mar. 2023, [Peer-reviewed]
    Scientific journal
  • Investigation of dichlorodiphenyltrichloroethane (DDT) on xenobiotic enzyme disruption and metabolomic bile acid biosynthesis in DDT-sprayed areas using wild rats.
    Kodai Motohira; Yared Beyene Yohannes; Yoshinori Ikenaka; Akifumi Eguchi; Shouta Mm Nakayama; Victor Wepener; Nico J Smit; Johan Hj VAN Vuren; Mayumi Ishizuka
    The Journal of veterinary medical science, 85, 2, 236, 243, 02 Jan. 2023, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, Dichlorodiphenyltrichloroethane (DDT) is an organochlorine insecticide used worldwide. Several studies have reported the toxic effects of DDT and its metabolites on steroid hormone biosynthesis; however, its environmental effects are not well understood. This study examined wild rats collected in DDT-sprayed areas of South Africa and quantified plasma metabolites using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). Fold change analysis of the metabolome revealed the effect of DDT on bile acid biosynthesis. Gene expression of the related enzyme in rat liver samples was also quantified. Significant association was found between DDT and gene expression levels related to constitutive androstane receptor mediated enzymes, such as Cyp2b1 in rat livers. However, our results could not fully demonstrate that enzymes related to bile acid biosynthesis were strongly affected by DDT. The correlation between DDT concentration and gene expression involved in steroid hormone synthesis in testis was also evaluated; however, no significant correlation was found. The disturbance of metabolic enzymes occurred in rat liver in the target area. Our results suggest that DDT exposure affects gene expression in wild rats living in DDT-sprayed areas. Therefore, there is a need for DDT toxicity evaluation in mammals living in DDT-sprayed areas. We could not find an effective biomarker that could reflect the mechanism of DDT exposure; however, this approach can provide new insights for future research to evaluate DDT effects in sprayed areas.
  • Status Report on Neonicotinoid Pollution in Japan: Emphasis on Human, Animal, and Environmental Health
    NIMAKO Collins; NAKAYAMA Shouta M. M.; YOHANNES Yared Beyene; IKENAKA Yoshinori; ISHIZUKA Mayumi
    Environmental Monitoring and Contaminants Research, 3, 69, 91, Japan Society for Environmental Chemistry, 2023, [Peer-reviewed]
    English, Neonicotinoid insecticides are exclusively used for insect control in many parts of the globe. Since early 1992, various neonicotinoid active compounds have been used for pest control in Japan. At present, all seven major neonicotinoid active compounds, imidacloprid, acetamiprid, dinotefuran, clothianidin, thiamethoxam, thiacloprid, and nitenpyram, are used in Japan, and the total shipment amount of these chemicals in the country was estimated 337.9 tons in 2022. Due to the massive neonicotinoid application in Japan, concerns have been raised about their potential infiltrations into nontarget ecosystems and their effects on human and ecological species. These concerns have inspired several studies, extensively investigating the environmental contamination levels and exposure tendencies in humans and several other invertebrate species. The current status report harmonized the up-to-date data on neonicotinoids in Japan and identified the incoherencies or knowledge gaps existing in the neonicotinoid literature reported in Japan. The report further summarized extensive neonicotinoid publications globally to illustrate the distributions of various neonicotinoid compounds in agricultural soils and surface waters and their exposures in humans and nontarget animal species. This report represents a few perspectives with detailed data from Japan into perspective.
  • Sensitivity Assessment of Diphacinone by Pharmacokinetic Analysis in Invasive Black Rats in the Bonin (Ogasawara) Archipelago, Japan
    Kazuki Takeda; Keita Shimizu; Miyu Sato; Masafumi Katayama; Shouta MM Nakayama; Kotaro Tanaka; Yoshinori Ikenaka; Takuma Hashimoto; Ryuichi Minato; Yusuke Oyamada; Kazuyuki D. Tanaka; Goro Kimura; Tsutomu Tanikawa; Keisuke Kato; Taichi Kusakabe; Mayumi Ishizuka; Ryo Kamata
    Elsevier BV, 2023
  • Biological effects related to exposure to polychlorinated biphenyl (PCB) and decabromodiphenyl ether (BDE-209) on cats
    Khidkhan K; Mizukawa H; Ikenaka Y; Nakayama SMM; Nomiyama K; Yokoyama N; Ichii O; Takiguchi M; Tanabe S; Ishizuka M
    PLOS ONE, 18, 1, e0277689, Jan. 2023, [Peer-reviewed], [International Magazine]
    English, Scientific journal, As an animal familiar to humans, cats are considered to be sensitive to chemicals; cats may be exposed to polychlorinated biphenyls (PCBs) and decabromodiphenyl ether (BDE-209) from indoor dust, household products, and common pet food, leading to adverse endocrine effects, such as thyroid hormone dysfunction. To elucidate the general biological effects resulting from exposure of cats to PCBs and PBDEs, cats were treated with a single i.p. dose of a principal mixture of 12 PCBs and observed for a short-term period. Results revealed that the testis weight, serum albumin, and total protein of the treated group decrease statistically in comparison with those in the control group. The negative correlations suggested that the decrease in the total protein and albumin levels may be disturbed by 4'OH-CB18, 3'OH-CB28 and 3OH-CB101. Meanwhile, the serum albumin level and relative brain weight decreased significantly for cats subjected to 1-year continuous oral administration of BDE-209 in comparison to those of control cats. In addition, the subcutaneous fat as well as serum high-density lipoprotein (HDL) and triglycerides (TG) levels increased in cats treated with BDE-209 and down-regulation of stearoyl-CoA desaturase mRNA expression in the liver occurred. These results suggested that chronic BDE-209 treatment may restrain lipolysis in the liver, which is associated with lipogenesis in the subcutaneous fat. Evidence of liver and kidney cell damage was not observed as there was no significant difference in the liver enzymes, blood urea nitrogen and creatinine levels between the two groups of both experiments. To the best of our knowledge, this is the first study that provides information on the biochemical effects of organohalogen compounds in cats. Further investigations on risk assessment and other potential health effects of PCBs and PBDEs on the reproductive system, brain, and lipid metabolism in cats are required.
  • Sulfotransferases (SULTs), enzymatic and genetic variation in Carnivora: Limited sulfation capacity in pinnipeds.
    Mitsuki Kondo; Yoshinori Ikenaka; Shouta M M Nakayama; Yusuke K Kawai; Hazuki Mizukawa; Yoko Mitani; Kei Nomyama; Shinsuke Tanabe; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 263, 109476, 109476, Jan. 2023, [International Magazine]
    English, Scientific journal, Wild carnivorans are one of the most important species due to their high positions in the food chain. They are also highly affected by numerous environmental contaminants through bioaccumulation and biomagnification. Xenobiotic metabolism is a significant chemical defense system from xenobiotics because it degrades the activity of a wide range of chemicals, generally into less active forms, resulting in their deactivation. Sulfotransferases (SULTs) are one of the most important xenobiotic metabolic enzymes, which catalyze the sulfonation of a variety of endogenous and exogenous chemicals, such as hormones, neurotransmitters, and a wide range of xenobiotic compounds. Although SULTs are of such high importance, little research has focused on these enzymes in wild carnivorans. In this study, we clarified the genetic properties of SULTs in a wide range of mammals, focusing on carnivorans, using in silico genetic analyses. We found genetic deficiencies of SULT1E1 and SULT1D1 isoforms in all pinnipeds analyzed and nonsense mutations in SULT1Cs in several carnivorans including pinnipeds. We further investigated the enzymatic activity of SULT1E1 in vitro using liver cytosols from pinnipeds. Using a SULT1E1 probe substrate, we found highly limited estradiol sulfonation in pinnipeds, whereas other mammals had relatively high sulfation. These results suggest that pinnipeds have severely or completely absent SULT1E1 activity, which importantly catalyzes the metabolism of estrogens, drugs, and environmental toxins. This further implies a high susceptibility to a wide range of xenobiotics in these carnivorans, which are constantly exposed to environmental chemicals throughout their lifetime.
  • Contamination Status of Pet Cats in Thailand with Organohalogen Compounds (OHCs) and Their Hydroxylated and Methoxylated Derivatives and Estimation of Sources of Exposure to These Contaminants
    Makoto Shimasaki; Hazuki Mizukawa; Kohki Takaguchi; Aksorn Saengtienchai; Araya Ngamchirttakul; Disdanai Pencharee; Kraisiri Khidkhan; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka; Kei Nomiyama
    Animals, 12, 24, 3520, 3520, MDPI AG, 13 Dec. 2022, [Peer-reviewed], [Invited], [Internationally co-authored], [International Magazine]
    English, Scientific journal, In this study, we analyzed serum samples of pet cats from Thailand and estimated the contribution to organohalogen compounds (OHCs) exposure through cat food and house dust intake. BDE-209 was predominant in cat sera and accounted for 76% of all polybrominated diphenyl ethers (PBDEs). Decabromodiphenyl ether (BDE-209) is a major contaminant in dry cat food and house dust, which has been estimated to be a source of exposure for Thai pet cats. BDE-209 is a major contaminant of OHCs in dry cat food and house dust, which was estimated to be a source of exposure for Thai pet cats. On the other hand, the level of contamination by PCBs was lower than in other countries. Analysis of pet foods suggested that BDE-209 in pet cat serum was attributable to the consumption of dry cat food. On the other hand, house dust also contained high concentrations of BDE-209. Thus, high levels of BDE-209 in pet cat sera can be attributed to the consumption of dry cat food and house dust. These results suggest that pet cats are routinely exposed to non-negligible levels of OHCs.
  • Accumulation of Metals in the Environment and Grazing Livestock near A Mongolian Mining Area.
    Bayartogtokh Bataa; Kodai Motohira; Delgermurun Dugar; Tsend-Ayush Sainnokhoi; Lkhamjav Gendenpil; Tserenchimed Sainnokhoi; Bolormaa Pelden; Yared Beyene Yohannes; Sumiya Ganzorig; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Toxics, 10, 12, 10 Dec. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, The Mongolian economy is supported by rich deposits of natural resources, such as copper, coal, and gold. However, the risk of heavy metal pollution to livestock and human have been recently discussed. This research collected various samples from soil and animal (sheep, goat, horse, cow, and camel), blood and organs (kidney and liver) in the Mongolian countryside. These samples were processed, and the concentration of metals was quantified using inductively coupled plasma-mass spectrometry (ICP/MS). As previously reported, arsenic was found at high levels of accumulation in soil. Selenium is another concern, as median concentration in one area exceeded the maximum allowable level. Cadmium and selenium were found to be highly accumulated in animal kidney. This research revealed the current pollution level in Mongolia based on evaluation of soil and animals. The concentration in animals could not indicate that animals had severe effects because of heavy metal exposure. However, kidney is eaten in Mongolia, and so there is a direct connection to human health, and this research suggested the possible risks posed by each edible animal. In particular, evaluation of metals in livestock is rare in Mongolia. This result can contribute to animal and human health in Mongolian communities.
  • Methylation profiles of global LINE-1 DNA and the GSTP1 promoter region in children exposed to lead (Pb).
    Yared Beyene Yohannes; Shouta M M Nakayama; John Yabe; Haruya Toyomaki; Andrew Kataba; Hokuto Nakata; Kaampwe Muzandu; Chihiro Miyashita; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Epigenetics, 17, 13, 2377, 2388, Dec. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Lead (Pb) exposure has adverse health effects and altered DNA methylation may contribute to Pb toxicity. LINE-1 is an interspersed repeated DNA that is used as a surrogate marker for estimating genomic DNA methylation levels, and GSTP1 is an isozyme that detoxifies xenobiotics like Pb, and its expression is inhibited by methylation. Thus, to assess the effects of Pb exposure on global hypomethylation and gene-specific promoter hypermethylation, we examined DNA methylation at LINE-1 repetitive elements and the GSTP1 promoter region. Blood samples were obtained from children (N = 123) living in Pb-polluted areas (as exposed children) and children (N = 63) living in Pb-unpolluted areas (as control children) in Kabwe, Zambia. ICP-MS was used to determine blood lead levels (BLLs), and pyrosequencing and a fluorescence-based polymerase chain reaction assay were used to determine levels of LINE-1 methylation and GSTP1 promoter methylation, respectively. Inverse association was found between BLLs and LINE-1 methylation (β = - 0.046, p = 0.006). The highest quartile of BLL had significant hypomethylation of LINE-1 (p for trend = 0.03), suggesting the higher the BLL, the lower LINE-1 methylation. GSTP1 methylation levels did not differ significantly between the two areas (p = 0.504), nor was it associated with Pb poisoning risk (OR = 1.03, p = 0.476), indicating GSTP1 methylation may not be a reliable biomarker of Pb exposure in healthy people. Therefore, Pb-related health problems could result from global DNA methylation changes due to high BLLs.
  • Detection of Changes in Monoamine Neurotransmitters by the Neonicotinoid Pesticide Imidacloprid Using Mass Spectrometry.
    Anri Hirai; Ryo Yamazaki; Atsushi Kobayashi; Takashi Kimura; Kei Nomiyama; Shuichi Shimma; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Toxics, 10, 11, 17 Nov. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Monoamine neurotransmitters (MAs), including dopamine (DA) and serotonin (5-HT), regulate brain functions such as behavior, memory, and learning. Neonicotinoids are pesticides that are being used more frequently. Neonicotinoid exposure has been observed to produce neurological symptoms, such as altered spontaneous movements and anxiety-like behaviors, which are suspected to be caused by altered MA levels. However, current neurotoxicity tests are not sufficiently sensitive enough to make these determinations. In this study, we performed some behavior tests, and derivatization reagents to improve the ionization efficiency, which was applied to liquid chromatography mass spectrometry (LC-MS/MS) to reveal the effect of neonicotinoid administration on MAs in the brain. We orally administered the neonicotinoid imidacloprid (0, 10, and 50 mg/kg body weight) to C57BL/6NCrSlc mice. In the behavior tests, a decrease in activity was observed. The LC-MS/MS quantification of MAs in various brain regions showed a decrease in some MA levels in the olfactory bulb and the striatum. These results showed, for the first time, that even a low dose of imidacloprid could alter MA levels in various parts of the brain.
  • Characteristics of cytochrome P450-dependent metabolism in the liver of the wild raccoon, Procyon lotor.
    So Shinya; Yared Beyene Yohannes; Yoshinori Ikenaka; Shouta Mm Nakayama; Mayumi Ishizuka; Shoichi Fujita
    The Journal of veterinary medical science, 84, 12, 1665, 1672, 02 Nov. 2022, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal, Wildlife is exposed to a wide range of xenobiotics in the natural environment. In order to appropriately assess xenobiotic-induced toxicity in wildlife, it is necessary to understand metabolic capacities. Carnivores, in general, have low metabolic abilities, making them vulnerable to a variety of chemicals. Raccoons (Procyon lotor) in the wild have been found to have high levels of xenobiotics. However, little is known about the metabolic capacity of the cytochrome P450 (CYP) enzymes in this species. Thus, this study used liver samples to investigate the characteristics of CYP enzymes in wild raccoons. In 22 wild raccoons, CYP concentrations in hepatic microsomes were examined. To better understand the properties of CYP-dependent metabolism, in vitro metabolic activity studies were performed using ethoxyresorufin, pentoxyresorufin and testosterone as substrates. In addition, three raccoons were fed commercial dog food in the laboratory for one week, and the effects on CYP-dependent metabolism were investigated. In comparison to other mammalian species, raccoons had very low concentrations of CYP in their livers. In an in vitro enzymatic analysis, raccoons' ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-depentylase (PROD) metabolic capacities were less than one-fifth and one-tenth of rats', respectively. These results indicate the possible high risk in raccoons if exposed to high levels of environmental xenobiotics because of their poor CYP activity. In this study, the features of CYP-dependent metabolism in wild raccoons are described for the first time.
  • Duplication, Loss, and Evolutionary Features of Specific UDP-Glucuronosyltransferase Genes in Carnivora (Mammalia, Laurasiatheria).
    Mitsuki Kondo; Yoshinori Ikenaka; Shouta M M Nakayama; Yusuke K Kawai; Mayumi Ishizuka
    Animals : an open access journal from MDPI, 12, 21, 27 Oct. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, UDP-glucuronosyltransferases (UGTs) are one of the most important enzymes for xenobiotic metabolism or detoxification. Through duplication and loss of genes, mammals evolved the species-specific variety of UGT isoforms. Among mammals, Carnivora is one of the orders that includes various carnivorous species, yet there is huge variation of food habitat. Recently, lower activity of UGT1A and 2B were shown in Felidae and pinnipeds, suggesting evolutional loss of these isoforms. However, comprehensive analysis for genetic or evolutional features are still missing. This study was conducted to reveal evolutional history of UGTs in Carnivoran species. We found specific gene expansion of UGT1As in Canidae, brown bear and black bear. We also found similar genetic duplication in UGT2Bs in Canidae, and some Mustelidae and Ursidae. In addition, we discovered contraction or complete loss of UGT1A7-12 in phocids, some otariids, felids, and some Mustelids. These studies indicate that even closely related species have completely different evolution of UGTs and further imply the difficulty of extrapolation of the pharmacokinetics and toxicokinetic result of experimental animals into wildlife carnivorans.
  • Specific Gene Duplication and Loss of Cytochrome P450 in Families 1-3 in Carnivora (Mammalia, Laurasiatheria).
    Mitsuki Kondo; Yoshinori Ikenaka; Shouta M M Nakayama; Yusuke K Kawai; Mayumi Ishizuka
    Animals : an open access journal from MDPI, 12, 20, 18 Oct. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Cytochrome P450s are among the most important xenobiotic metabolism enzymes that catalyze the metabolism of a wide range of chemicals. Through duplication and loss events, CYPs have created their original feature of detoxification in each mammal. We performed a comprehensive genomic analysis to reveal the evolutionary features of the main xenobiotic metabolizing family: the CYP1-3 families in Carnivora. We found specific gene expansion of CYP2Cs and CYP3As in omnivorous animals, such as the brown bear, the black bear, the dog, and the badger, revealing their daily phytochemical intake as providing the causes of their evolutionary adaptation. Further phylogenetic analysis of CYP2Cs revealed Carnivora CYP2Cs were divided into CYP2C21, 2C41, and 2C23 orthologs. Additionally, CYP3As phylogeny also revealed the 3As' evolution was completely different to that of the Caniformia and Feliformia taxa. These studies provide us with fundamental genetic and evolutionary information on CYPs in Carnivora, which is essential for the appropriate interpretation and extrapolation of pharmacokinetics or toxicokinetic data from experimental mammals to wild Carnivora.
  • Sex-specific behavioral effects of acute exposure to the neonicotinoid clothianidin in mice.
    Shizuka Kubo; Tetsushi Hirano; Yuka Miyata; Shuji Ohno; Kanoko Onaru; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka; Youhei Mantani; Toshifumi Yokoyama; Nobuhiko Hoshi
    Toxicology and applied pharmacology, 456, 116283, 116283, 14 Oct. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Although neonicotinoids are among the major classes of pesticides that affect mammalian nervous systems, little is known about sex differences in their effects. This study aimed to examine whether the neurobehavioral effects of a neonicotinoid, clothianidin (CLO), differed between sexes. Male and female C57BL/6 N mice were orally administered CLO (5 or 50 mg/kg) at or below the chronic no-observed-adverse-effect-level (NOAEL) and subjected to behavioral tests of emotional and learning functions. Changes in neuroactivity in several brain regions and the concentrations of CLO and its metabolites in blood and urine were measured. Acute CLO exposure caused sex-related behavioral effects; decreases in locomotor activities and elevation of anxiety-like behaviors were more apparent in males than in females. In addition, male-specific impairment of short- and long-term learning memory by CLO exposure was observed in both the novel recognition test and the Barnes maze test. Male-dominant increases in the number of c-fos positive cells were observed in the paraventricular thalamic nucleus in the thalamus and in the dentate gyrus in the hippocampus, which are related to the stress response and learning function, respectively. The concentrations of CLO and most metabolites in blood and urine were higher in males. These results support the notion that male mice are more vulnerable than females to the neurobehavioral effects of CLO and provide novel insights into the risk assessment of neonicotinoids in mammalian neuronal function.
  • Does Moringa Oleifera affect element accumulation patterns and lead toxicity in Sprague–Dawley rats?
    Hokuto Nakata; Shouta M.M. Nakayama; Andrew Kataba; Haruya Toyomaki; Rio Doya; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka
    Journal of Functional Foods, 97, 105242, Elsevier BV, Oct. 2022
  • Toxicokinetic analysis of the anticoagulant rodenticides warfarin & diphacinone in Egyptian fruit bats (Rousettus aegyptiacus) as a comparative sensitivity assessment for Bonin fruit bats (Pteropus pselaphon)
    Kazuki Takeda; Kosuke Manago; Ayuko Morita; Yusuke K. Kawai; Nobuaki Yasuo; Masakazu Sekijima; Yoshinori Ikenaka; Takuma Hashimoto; Ryuichi Minato; Yusuke Oyamada; Kazuo Horikoshi; Hajime Suzuki; Mayumi Ishizuka; Shouta M.M. Nakayama
    Ecotoxicology and Environmental Safety, 243, 113971, 113971, Elsevier BV, Sep. 2022, [Peer-reviewed]
    Scientific journal
  • Drought altered trophic dynamics of an important natural saline lake: A stable isotope approach.
    Lizaan de Necker; Luc Brendonck; Ruan Gerber; Pieter Lemmens; David X Soto; Yoshinori Ikenaka; Mayumi Ishizuka; Victor Wepener; Nico J Smit
    The Science of the total environment, 834, 155338, 155338, 15 Aug. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Narrative review of lead poisoning in humans caused by industrial activities and measures compatible with sustainable industrial activities in Republic of Zambia
    Hokuto Nakata; Shouta M.M. Nakayama; John Yabe; Kaampwe Muzandu; Andrew Kataba; Atsuko Ikeda-Araki; Marie-Noel Brune Drisse; Lesley Jayne Onyon; Julia Gorman; Poudel Kritika; Hisanori Fukunaga; Yoshinori Ikenaka; Reiko Kishi; Mayumi Ishizuka
    Science of The Total Environment, 157833, 157833, Elsevier BV, Aug. 2022, [Peer-reviewed]
    Scientific journal
  • Clarifying expression patterns by renal lesion using transcriptome analysis and vanin-1 as a potential novel biomarker for renal injury in chickens.
    Chihiro Ishii; Yusuke K Kawai; Yoshinori Ikenaka; Naoya Maekawa; Osamu Ichii; Shouta M M Nakayama; Mayumi Ishizuka
    Poultry science, 101, 9, 102011, 102011, 16 Jun. 2022, [International Magazine]
    English, Scientific journal, Bird death is often caused by renal lesions induced by chemicals. The avian kidney has a renal portal system with significant blood flow that is sensitive to many chemicals. However, early avian biomarkers for kidney injury are yet to be identified. This study aimed to identify novel renal biomarkers. Acute kidney injury (AKI) can be divided into acute interstitial nephritis (AIN) and acute tubular necrosis (ATN). A chicken model of kidney damage was created by an injection of diclofenac or cisplatin, which caused either AIN or ATN, respectively. Microarray analysis was performed to profile the gene expression patterns in the chickens with nephropathy. A gene enrichment analysis suggested that the genes related to responses to external stimuli showed expression changes in both AIN and ATN. However, hierarchical clustering analyses suggested that gene expression patterns differed between AIN and ATN, and the number of biomarkers relating to renal damage was low. To identify early biomarkers for nephropathy, we focused on genes that were induced at various levels of renal damage. The gene, vanin-1 (VNN1) was highly induced in the early stages of renal damage. A quantitative real-time PCR analysis supported this finding. These results suggest VNN1 could be a useful early biomarker of kidney injury in avian species.
  • Cytochrome P450 2J (CYP2J) Genes in Dogs, Cats, and Pigs Are Expressed and Encode Functional Drug-Metabolizing Enzymes.
    Yasuhiro Uno; Norie Murayama; Moe Ijiri; Hiroaki Kawaguchi; Osamu Yamato; Mitsuya Shiraishi; Atsushi Asano; Hiroki Teraoka; Hazuki Mizukawa; Shouta M M Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka; Hiroshi Yamazaki
    Drug metabolism and disposition: the biological fate of chemicals, 50, 11, 1434, 1441, 14 Jun. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Cytochromes P450 (P450 or CYP) have been identified and analyzed in dogs and pigs, species that are often used in preclinical drug studies. Moreover, P450s are clinically important for drug therapy not only in humans but also in species under veterinary care, including dogs and cats. In the present study, seven P450s homologous to human CYP2J2, namely, dog CYP2J2; cat CYP2J2; and pig CYP2J33, CYP2J34, CYP2J35, CYP2J91, and CYP2J93, were newly identified and characterized. The cDNAs of these CYP2Js contained open reading frames of 502 amino acids, except for CYP2J35 (498 amino acids), and shared high sequence identity (77-80%) with human CYP2J2. Phylogenetic analysis revealed that dog and cat CYP2J2 were closely related, whereas pig CYP2Js formed a cluster. All seven CYP2J genes contain nine coding exons and are located in corresponding genomic regions, with the pig CYP2J genes forming a gene cluster. These CYP2J2 mRNAs were predominantly expressed in small intestine with additional expression in kidney and brain for dog CYP2J2 and pig CYP2J91 mRNAs, respectively. All seven CYP2Js metabolized human CYP2J2 substrates terfenadine, ebastine, and astemizole, indicating that they are functional enzymes. Dog CYP2J2 and pig CYP2J34 and CYP2J35 efficiently catalyzed ebastine primary hydroxylation and secondary carebastine formation at low substrate concentrations, just as human CYP2J2 does. Velocity-versus-substate plots exhibited sigmoidal relationships for dog CYP2J2, cat CYP2J2, and pig CYP2J33, indicating allosteric interactions. These results suggest that dog, cat, and pig CYP2Js have similar functional characteristics to human CYP2J2, with slight differences in ebastine and astemizole oxidations. Significance Statement New dog cytochrome P450 2J2 (CYP2J2); cat CYP2J2; and pig CYP2J33, CYP2J34, CYP2J35, CYP2J91, and CYP2J93, homologous to human CYP2J2, were identified and characterized by sequence, phylogenetic, and genomic structure analyses. Intestinal expression patterns of CYP2J mRNAs were characteristic in dogs, cats, and pigs. Dog, cat, and pig CYP2Js likely play roles as drug-metabolizing enzymes in small intestine, similar to human CYP2J2.
  • Molecular and functional characterization of flavin-containing monooxygenases in pigs, dogs, and cats.
    Yasuhiro Uno; Makiko Shimizu; Yurie Ogawa; Miaki Makiguchi; Hiroaki Kawaguchi; Osamu Yamato; Mayumi Ishizuka; Hiroshi Yamazaki
    Biochemical pharmacology, 202, 115125, 115125, 08 Jun. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Flavin-containing monooxygenases (FMOs) are drug-oxygenating enzymes that are present in the human genome as FMO1-5 and FMO6P. Among pig, dog, and cat FMOs, pig and dog FMO1 and FMO3 have been partly characterized, but other FMOs have not been systematically identified. In this study, orthologous FMO cDNAs were isolated from pig, dog, and cat livers and evaluated by sequence and phylogenetic analyses, tissue expression, and catalytic function. The amino acid sequences of pig, dog, and cat FMO1-5 shared high sequence identities (83-89%) with human FMO1-5 and were closely clustered in a phylogenetic tree. The gene structure and genomic organization of FMO1-5 were conserved across these species. Dog and pig FMO6P contained insertions of 1 and 83 bases, respectively, and are possibly pseudogenes similar to human FMO6P. Among the tissue types analyzed, pig FMO1 mRNA was abundant in liver, kidney, and lung; dog FMO3, FMO2, and FMO5 mRNAs were abundant in liver, lung, and kidney, respectively; cat FMO1 and FMO3 mRNAs were abundant in kidney and liver, respectively. Recombinant pig and dog FMO1-5 and cat FMO1-6 all mediated benzydamine and trimethylamine N-oxygenations and methyl p-tolyl sulfoxide S-oxygenation. The selective human FMO3 substrate trimethylamine was predominantly metabolized by pig FMO1, dog FMO3, and cat FMO3. Cat FMO6 was also active toward trimethylamine. These results suggest some similarities in the drug-metabolizing capabilities of FMO3 in dogs, cats, and humans and that dog and cat FMO3 generally have molecular and functional characteristics similar to human FMO3, being the major FMO in human liver.
  • Behavior and toxic effects of Pb in a waterfowl model with oral exposure to Pb shots: Investigating Pb exposure in wild birds.
    Hiroshi Sato; Chihiro Ishii; Shouta M M Nakayama; Takahiro Ichise; Keisuke Saito; Yukiko Watanabe; Kohei Ogasawara; Ryota Torimoto; Atsushi Kobayashi; Takashi Kimura; Yukiko Nakamura; Junya Yamagishi; Yoshinori Ikenaka; Mayumi Ishizuka
    Environmental pollution (Barking, Essex : 1987), 308, 119580, 119580, 06 Jun. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Among wild birds, lead (Pb) exposure caused by ingestion of ammunition is a worldwide problem. We aimed to reveal the behavior and toxic effect of Pb caused by ingesting Pb shots in waterfowl. Four male, eight-week old Muscovy ducks (Cairina moschata) were given three Pb shots (approximately 240 mg in total) orally and then fed for 29 days after exposure, simulating a low-dose Pb exposure in wild waterfowl. During the breeding period, blood samples were collected 10 times, and fecal samples every day. Additionally, 22 fresh tissue and 6 bone samples were obtained from each duck through the dissection. Although there were no gross abnormalities, the maximum blood Pb concentration of each duck ranged from 0.6 to 3.7 mg/L, reaching a threshold concentration indicative of clinical symptoms (>0.5 mg/L). δ-aminolevulinic acid dehydratase declined one day after exposure and remained low throughout the feeding period. Hematocrit also tended to decrease, indicating signs of anemia. The highest Pb accumulation was observed in the bones, followed by the kidneys, intestinal tracts, and liver. High Pb accumulation in the bones, which are known to have a long Pb half-life, suggested that Pb would remain in the body and possibly affect bird health beyond 28 days after exposure. Gene expression analysis showed a significant increase in the expression of the toll-like receptor-3 gene, which is involved in virus discrimination in the liver, suggesting a disruption of the immune system. Microbiota analyses showed a correlation between the blood Pb concentration and the abundances of Lachnospiraceae and Ruminococcaceae, suggesting that Pb affects lipid metabolism. These results provide fundamental data on Pb exposure in wild birds and a new perspective on the damage such exposure causes.
  • Health impact assessment of pet cats caused by organohalogen contaminants by serum metabolomics and thyroid hormone analysis.
    Kei Nomiyama; Yasuo Yamamoto; Akifumi Eguchi; Hiroyuki Nishikawa; Hazuki Mizukawa; Nozomu Yokoyama; Osamu Ichii; Mitsuyoshi Takiguchi; Shouta M M Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka
    The Science of the total environment, 842, 156490, 156490, 03 Jun. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Companion animals are in close contact with the human surroundings, and there is growing concern about the effects of harmful substances on the health of pet cats. In this study, we investigated the potential health effects of organohalogen compounds (OHCs) on thyroid hormone (TH) homeostasis and metabolomics in Japanese pet cats. There was a significant negative correlation between concentrations of several contaminants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), hydroxylated PCBs (OH-PCBs), hydroxylated PBDEs (OH-PBDEs), and THs in cat serum samples. These results suggested that exposure to OHCs causes a decrease in serum TH levels in pet cats. In this metabolomics study, each exposure level of parent compounds (PCBs and PBDEs) and their hydroxylated compounds (OH-PCBs and OH-PBDEs) were associated with their own unique primary metabolic pathways, suggesting that parent and phenolic compounds exhibit different mechanisms of action and biological effects. PCBs were associated with many metabolic pathways, including glutathione and purine metabolism, and the effects were replicated in in-vivo cat PCB administration studies. These results demonstrated that OHC exposure causes chronic oxidative stress in pet cats. PBDEs were positively associated with alanine, aspartate, and glutamate metabolism. Due to the chronic exposure of cats to mixtures of these contaminants, the combination of their respective metabolic pathways may have a synergistic effect.
  • Impacts of Surface Water on Windborne Lead Dispersion from the Zinc Plant Leach Residue in Kabwe, Zambia
    Shinsaku Nakamura; Toshifumi Igarashi; Yoshitaka Uchida; Mayumi Ito; Kazuyo Hirose; Tsutomu Sato; Walubita Mufalo; Meki Chirwa; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Minerals, 12, 5, May 2022, [Peer-reviewed]
    Scientific journal
  • Geospatial approach to investigate spatial clustering and hotspots of blood lead levels in children within Kabwe, Zambia.
    Given Moonga; Moses N Chisola; Ursula Berger; Dennis Nowak; John Yabe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka; Stephan Bose-O'Reilly
    Environmental research, 207, 112646, 112646, 01 May 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Estimation of the Effects of Neonicotinoid Insecticides on Wild Raccoon, Procyon lotor, in Hokkaido, Japan: Urinary Concentrations and Hepatic Metabolic Capability of Neonicotinoids.
    So Shinya; Mariko Sashika; Miku Minamikawa; Tetsuji Itoh; Yared Beyene Yohannes; Shouta M M Nakayama; Mayumi Ishizuka; Collins Nimako; Yoshinori Ikenaka
    Environmental toxicology and chemistry, 41, 8, 1865, 1874, 22 Apr. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Human Health Risk Assessment from Lead Exposure through Consumption of Raw Cow Milk from Free-Range Cattle Reared in the Vicinity of a Lead-Zinc Mine in Kabwe.
    Golden Zyambo; John Yabe; Kaampwe Muzandu; Ethel M'kandawire; Kennedy Choongo; Andrew Kataba; Kenneth Chawinga; Allan Liazambi; Shouta M M Nakayama; Hokuto Nakata; Mayumi Ishizuka
    International journal of environmental research and public health, 19, 8, 14 Apr. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Geochemical identification of particulate lead pollution in shallow groundwater in inhabited areas in Kabwe, Zambia
    Kazuhiro Toyoda; Shota Nakano; Shunitz Tanaka; Kawawa Banda; Imasiku A. Nyambe; Tsuyoshi Ishikawa; Shouta Nakayama; Mayumi Ishizuka
    Applied Geochemistry, 139, Apr. 2022, [Peer-reviewed]
    Scientific journal
  • Alkaline Leaching and Concurrent Cementation of Dissolved Pb and Zn from Zinc Plant Leach Residues
    Marthias Silwamba; Mayumi Ito; Naoki Hiroyoshi; Carlito Baltazar Tabelin; Ryota Hashizume; Tomoki Fukushima; Ilhwan Park; Sanghee Jeon; Toshifumi Igarashi; Tsutomu Sato; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Minerals, 12, 4, Apr. 2022, [Peer-reviewed]
    Scientific journal
  • Assessment of ameliorative effects of organic dietary interventions on neonicotinoid exposure rates in a Japanese population.
    Collins Nimako; Takahiro Ichise; Hiroshi Hasegawa; Osei Akoto; Nathaniel O Boadi; Kumiko Taira; Kazutoshi Fujioka; Norikazu Isoda; Shouta M M Nakayama; Mayumi Ishizuka; Yoshinori Ikenaka
    Environment international, 162, 107169, 107169, Apr. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Ca2+ imaging with two-photon microscopy to detect the disruption of brain function in mice administered neonicotinoid insecticides.
    Anri Hirai; Shouta Sugio; Collins Nimako; Shouta M M Nakayama; Keisuke Kato; Keisuke Takahashi; Koji Arizono; Tetsushi Hirano; Nobuhiko Hoshi; Kazutoshi Fujioka; Kumiko Taira; Mayumi Ishizuka; Hiroaki Wake; Yoshinori Ikenaka
    Scientific reports, 12, 1, 5114, 5114, 24 Mar. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Foraging ecology of mature male Antarctic minke whales (Balaenoptera bonaerensis) revealed by stable isotope analysis of baleen plates
    Hiroshi Ishikawa; Mayuko Otsuki; Tsutomu Tamura; Kenji Konishi; Takaharu Bando; Mayumi Ishizuka; Yoshinori Ikenaka; Shouta M.M. Nakayama; Yoko Mitani
    Polar Science, 31, Mar. 2022, [Peer-reviewed]
    Scientific journal
  • Environmentally relevant lead (Pb) water concentration induce toxicity in zebrafish (Danio rerio) larvae.
    Andrew Kataba; Tarryn L Botha; Shouta M M Nakayama; Yared B Yohannes; Yoshinori Ikenaka; Victor Wepener; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 252, 109215, 109215, Feb. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Metabolomic Alteration in the Plasma of Wild Rodents Environmentally Exposed to Lead: A Preliminary Study.
    Hokuto Nakata; Akifumi Eguchi; Shouta M M Nakayama; John Yabe; Kaampwe Muzandu; Yoshinori Ikenaka; Chisato Mori; Mayumi Ishizuka
    International journal of environmental research and public health, 19, 1, 04 Jan. 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Wild Lizards as a Target of Heavy Metal Biomonitoring Focusing on Land Use Patterns; An Example from a Former Mining Site in Zambia
    DOYA Rio; NAKAYAMA Shouta M. M.; NAKATA Hokuto; KONDO Mitsuki; ZYAMBO Golden; MUZANDU Kaampwe; YABE John; IKENAKA Yoshinori; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 49.1, P-133, The Japanese Society of Toxicology, 2022
    Japanese, In Kabwe town in the Republic of Zambia, heavy metal pollution has been widespread due to lead and zinc mining activities since the early 20th, and it continues even after the official cessation of industrial operation in 1994. In addition to soil, high concentrations of lead have been detected in humans, domestic animals, and wild rodents (Yabe et al. 2015, Nakata et al. 2017, Nakayama et al. 2011).

    We employed a species of wild lizards (Trachylepis wahlbergii) as a target organism for biomonitoring focusing on land use patterns. This species was considered to be suitable because they live in relatively small home ranges, they only prey on insects, and they are widely distributed from residential areas to grasslands.

    An initial field survey was conducted in 2017 to collect the lizards and soil of their habitat. Liver and other organs were collected from 224 lizards. Metal analysis of lizard and soil samples was performed by ICP-MS after acid digestion with a microwave system. The highest concentration in the liver was 200μg/g, which is much higher than the previous result in the same area using other animal species. Also, biological concentrations were relatively high in places near the mine and areas without vegetation. A follow-up survey was conducted in 2021 to further investigate the species-specificity of accumulation pattern, chronological shift, and relationship of these points with changes in land use pattern. The analytical results of 112 lizards are presented together with environmental parameters and geographical analysis.
  • Assessing the Net Benefits of Organic Farming interventions in Ecosystem Preservation against Emerging Pesticides
    NIMAKO Collins; HIRAI Anri; ICHISE Takahiro; NAKAYAMA Shouta M.M.; ISHIZUKA Mayumi; IKENAKA Yoshinori
    Annual Meeting of the Japanese Society of Toxicology, 49.1, P-108, The Japanese Society of Toxicology, 2022
    Japanese, Organic farming practices are generally considered potential countermeasures against pesticide exposure in human populations. However, little is known if current organic interventional measures adopted in Japan can mitigate neonicotinoid (NNI) exposures or otherwise. The current validates the efficacies of organic dietary interventions in ameliorating NNIs exposures within the Japanese population. Firstly, 103 Japanese volunteers were recruited and fed strictly with either organic diets for 5 or 30 days or with conventional diets. Then the exposure rates of 8 NNIs were determined in the population, by LC-MS/MS analysis. After analysis, 8 NNIs were detected in the target population; but the detection rates were far lower in the organic diet consumers compared to conventional diet consumers. The organic dietary intervention drastically reduced the cumulative levels and the daily intake rates of NNIs in the Japanese population. Subsequently, the residual levels of NNIs were determined in organic and conventional green tea leaves produced in Japan. Seven NNIs compounds and one NNI metabolite were detected in tea leaves cultivated by strict organic farming methods. However, the detection rates of NNIs were relatively lower in organic tea leaves than conventional tea leaves. Moreover, the daily exposure rates of NNIs through green tea consumption were far lower for organic tea leaves than conventional tea leaves. These findings ultimately show that the adoption of organic farming interventions may offer optimum ameliorative outcomes on NNI exposure rates Japanese population.
  • Estimation of the reference lead (Pb) concentration levels affecting immune cells in the blood of Black-headed Gulls (Chroicocephalus ridibundus, Laridae)
    Nana Ushine; Osamu Kurata; Yoshikazu Tanaka; Shouta M.M Nakayama; Mayumi Ishizuka; Takuya Kato; Shin-Ichi Hayama
    Avian Conservation and Ecology, 17, 2, Resilience Alliance, Inc., 2022
    Scientific journal
  • A GCDGC-specific DNA (cytosine-5) methyltransferase that methylates the GCWGC sequence on both strands and the GCSGC sequence on one strand.
    Yoshikazu Furuta; Fumihito Miura; Takahiro Ichise; Shouta M M Nakayama; Yoshinori Ikenaka; Tuvshinzaya Zorigt; Mai Tsujinouchi; Mayumi Ishizuka; Takashi Ito; Hideaki Higashi
    PloS one, 17, 3, e0265225, 2022, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Editorial: Animal Poisoning and Biomarkers of Toxicity.
    Fernando Capela E Silva; Ana Catarina Sousa; Manuel Ramiro Pastorinho; Hazuki Mizukawa; Mayumi Ishizuka
    Frontiers in veterinary science, 9, 891483, 891483, 2022, [Peer-reviewed], [International Magazine]
    English
  • Urinary concentrations of neonicotinoid insecticides were related to renal tubular dysfunction and neuropsychological complaints in Dry-zone of Sri Lanka.
    Kumiko Taira; Tomonori Kawakami; Sujithra Kaushaliya Weragoda; H M Ayala S Herath; Yoshinori Ikenaka; Kazutoshi Fujioka; Madhubhani Hemachandra; Nirmalie Pallewatta; Yoshiko Aoyama; Mayumi Ishizuka; Jean-Marc Bonmatin; Makiko Komori
    Scientific reports, 11, 1, 22484, 22484, 18 Nov. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Solid-Phase Partitioning and Leaching Behavior of Pb and Zn from Playground Soils in Kabwe, Zambia.
    Walubita Mufalo; Pawit Tangviroon; Toshifumi Igarashi; Mayumi Ito; Tsutomu Sato; Meki Chirwa; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Toxics, 9, 10, 04 Oct. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Genome-wide DNA methylation analysis of dogs with high lead exposure living near a lead mining area in Kabwe, Zambia
    Jumpei Yamazaki; Haruya Toyomaki; Shouta M.M. Nakayama; John Yabe; Kaampwe Muzandu; Jaroslav Jelinek; Shoko Yokoyama; Yoshinori Ikenaka; Mitsuyoshi Takiguchi; Mayumi Ishizuka
    Environmental Pollution, 286, 117229, 117229, 01 Oct. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Lead concentrations and isotope ratios in blood, breastmilk and feces: contribution of both lactation and soil/dust exposure to infants in a lead mining area, Kabwe, Zambia
    Haruya Toyomaki; John Yabe; Shouta M.M. Nakayama; Yared B. Yohannes; Kaampwe Muzandu; Tiza Mufune; Hokuto Nakata; Yoshinori Ikenaka; Takeshi Kuritani; Mitsuhiro Nakagawa; Kennedy Choongo; Mayumi Ishizuka
    Environmental Pollution, 286, 117456, 117456, 01 Oct. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Simultaneous steroids measurement in dogs with hyperadrenocorticism using a column-switching liquid chromatography-tandem mass spectrometry method.
    Noboru Sasaki; Thandar Oo; Yoshikazu Yasuda; Takahiro Ichise; Noriyuki Nagata; Nozomu Yokoyama; Kazuyoshi Sasaoka; Keitaro Morishita; Shouta Mm Nakayama; Mayumi Ishizuka; Kensuke Nakamura; Mitsuyoshi Takiguchi; Yoshinori Ikenaka
    The Journal of veterinary medical science, 83, 11, 1634, 1642, 17 Sep. 2021, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Effects of zinc on tissue uptake and toxicity of lead in Sprague Dawley rat.
    Andrew Kataba; Shouta M M Nakayama; Yared Beyene Yohannes; Haruya Toyomaki; Hokuto Nakata; Yoshinori Ikenaka; Mayumi Ishizuka
    The Journal of veterinary medical science, 83, 11, 1674, 1685, 16 Sep. 2021, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • The impact of elevated blood lead levels in children on maternal health-related quality of life
    Hokuto Nakata; Harukazu Tohyama; Wakako Fujita; Shouta M.M. Nakayama; Mayumi Ishizuka; John Yabe; Nosiku S. Munyinda; Doreen Sakala; Kennedy Choongo; Shojiro Yamasaki; Natsumi Nagai; Takahiko Yoshida; Takeshi Saito
    Chemosphere, 279, 130490, 130490, Sep. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Geolocators link marine mercury with levels in wild seabirds throughout their annual cycle: Consequences for trans-ecosystem biotransport
    Akiko Shoji; Kyle H. Elliott; Yutaka Watanuki; Niladri Basu; Shannon Whelan; Joshua Cunningham; Scott Hatch; Hazuki Mizukawa; Shouta M.M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka; Stéphane Aris-Brosou
    Environmental Pollution, 284, 117035, 117035, 01 Sep. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Simultaneous quantification of imidacloprid and its metabolites in tissues of mice upon chronic low-dose administration of imidacloprid
    Collins Nimako; Yoshinori Ikenaka; Osei Akoto; Kazutoshi Fujioka; Kumiko Taira; Koji Arizono; Keisuke Kato; Keisuke Takahashi; Shouta M.M. Nakayama; Takahiro Ichise; Mayumi Ishizuka
    Journal of Chromatography A, 1652, 462350, 462350, 30 Aug. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Glutathione S-transferase gene polymorphisms in association with susceptibility to lead toxicity in lead- and cadmium-exposed children near an abandoned lead-zinc mining area in Kabwe, Zambia.
    Yared Beyene Yohannes; Shouta M M Nakayama; John Yabe; Haruya Toyomaki; Andrew Kataba; Hokuto Nakata; Kaampwe Muzandu; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Environmental science and pollution research international, 29, 5, 6622, 6632, 28 Aug. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Effect of prenatal exposure to phthalates on epigenome-wide DNA methylations in cord blood and implications for fetal growth: The Hokkaido Study on Environment and Children's Health
    Ryu Miura; Atsuko Ikeda-Araki; Toru Ishihara; Kunio Miyake; Chihiro Miyashita; Tamie Nakajima; Sumitaka Kobayashi; Mayumi Ishizuka; Takeo Kubota; Reiko Kishi
    Science of the Total Environment, 783, 147035, 147035, 20 Aug. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Analysis of lead distribution in avian organs by LA-ICP-MS: Study of experimentally lead-exposed ducks and kites
    Ryouta Torimoto; Chihiro Ishii; Hiroshi Sato; Keisuke Saito; Yukiko Watanabe; Kohei Ogasawara; Ayano Kubota; Takehisa Matsukawa; Kazuhito Yokoyama; Atsushi Kobayashi; Takashi Kimura; Shouta M.M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka
    Environmental Pollution, 283, 117086, 117086, 15 Aug. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Evaluation of dispersion of lead-bearing mine wastes in kabwe district, zambia
    Shinsaku Nakamura; Toshifumi Igarashi; Yoshitaka Uchida; Mayumi Ito; Kazuyo Hirose; Tsutomu Sato; Walubita Mufalo; Meki Chirwa; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Minerals, 11, 8, Aug. 2021
    Scientific journal
  • Human Exposures to Neonicotinoids in Kumasi, Ghana
    Collins Nimako; Yoshinori Ikenaka; Osei Akoto; Nesta Bortey-Sam; Takahiro Ichise; Shouta M.M. Nakayama; Kwadwo A. Asante; Kazutoshi Fujioka; Kumiko Taira; Mayumi Ishizuka
    Environmental Toxicology and Chemistry, 40, 8, 2306, 2318, Aug. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • 二光子顕微鏡を用いた、ニコチン性アセチルコリン受容体アゴニストによる脳機能障害の検出
    平井 杏梨; 杉尾 翔太; Nimako Collins; 中山 翔太; 加藤 恵介; 高橋 圭介; 有薗 幸司; 平野 哲史; 星 信彦; 藤岡 一俊; 平 久美子; 石塚 真由美; 和氣 弘明; 池中 良徳
    The Journal of Toxicological Sciences, 46, Suppl., S102, S103, (一社)日本毒性学会, Jul. 2021
    English
  • Bioaccumulation of DDT and other organochlorine pesticides in amphibians from two conservation areas within malaria risk regions of South Africa
    Nico J. Wolmarans; Lieven Bervoets; Ruan Gerber; Yared Beyene Yohannes; Shouta MM Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka; Patrick Meire; Nico J. Smit; Victor Wepener
    Chemosphere, 274, 129956, 129956, Jul. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • The effects of fipronil on emotional and cognitive behaviors in mammals
    Tomohiro Suzuki; Anri Hirai; Kraisiri Khidkhan; Collins Nimako; Takahiro Ichise; Kazuki Takeda; Hazuki Mizukawa; Shouta M.M. Nakayama; Kei Nomiyama; Nobuhiko Hoshi; Mizuki Maeda; Tetsushi Hirano; Kazuyoshi Sasaoka; Noboru Sasaki; Mitsuyoshi Takiguchi; Mayumi Ishizuka; Yoshinori Ikenaka
    Pesticide Biochemistry and Physiology, 175, 104847, 104847, Jun. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Aging-related changes in the sensitivity of behavioral effects of the neonicotinoid pesticide clothianidin in male mice
    Tetsushi Hirano; Yuka Miyata; Shizuka Kubo; Shuji Ohno; Kanoko Onaru; Mizuki Maeda; Sayaka Kitauchi; Misaki Nishi; Yoshiaki Tabuchi; Yoshinori Ikenaka; Takahiro Ichise; Shouta M.M. Nakayama; Mayumi Ishizuka; Koji Arizono; Keisuke Takahashi; Keisuke Kato; Youhei Mantani; Toshifumi Yokoyama; Nobuhiko Hoshi
    Toxicology Letters, 342, 95, 103, 15 May 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Assessment of LeadCare® II analysis for testing of a wide range of blood lead levels in comparison with ICP–MS analysis
    Hokuto Nakata; Shouta M.M. Nakayama; John Yabe; Kaampwe Muzandu; Haruya Toyomaki; Yared Beyene Yohannes; Andrew Kataba; Golden Zyambo; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Chemosphere, 271, 129832, 129832, May 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Sensitivity of turtles to anticoagulant rodenticides: Risk assessment for green sea turtles (Chelonia mydas) in the Ogasawara Islands and comparison of warfarin sensitivity among turtle species
    Yoshiya Yamamura; Kazuki Takeda; Yusuke K. Kawai; Yoshinori Ikenaka; Chiyo Kitayama; Satomi Kondo; Chiho Kezuka; Mari Taniguchi; Mayumi Ishizuka; Shouta M.M. Nakayama
    Aquatic Toxicology, 233, 105792, 105792, Apr. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Estimation of the feeding record of pregnant Antarctic minke whales (Balaenoptera bonaerensis) using carbon and nitrogen stable isotope analysis of baleen plates
    Mayuka Uchida; Ippei Suzuki; Keizo Ito; Mayumi Ishizuka; Yoshinori Ikenaka; Shouta M.M. Nakayama; Tsutomu Tamura; Kenji Konishi; Takeharu Bando; Yoko Mitani
    Polar Biology, 44, 3, 621, 629, Mar. 2021, [Peer-reviewed]
    Scientific journal
  • The VKORC1 ER-luminal loop mutation (Leu76Pro) leads to a significant resistance to warfarin in black rats (Rattus rattus)
    Kazuki Takeda; Yoshinori Ikenaka; Denis Fourches; Kazuyuki D. Tanaka; Shouta M.M. Nakayama; Dhoha Triki; Xinhao Li; Manabu Igarashi; Tsutomu Tanikawa; Mayumi Ishizuka
    Pesticide Biochemistry and Physiology, 173, 104774, 104774, Mar. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Evaluation of the ameliorative effect of Spirulina (Arthrospira platensis) supplementation on parameters relating to lead poisoning and obesity in C57BL/6J mice
    Hokuto Nakata; Shouta M.M. Nakayama; Andrew Kataba; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka
    Journal of Functional Foods, 77, Feb. 2021, [Peer-reviewed]
    Scientific journal
  • Delta-aminolevulinic acid dehydratase (ALAD) and vitamin D receptor (VDR) genes polymorphisms in children residing in an abandoned lead‑zinc mine area in Kabwe, Zambia
    Yared B. Yohannes; Shouta M.M. Nakayama; John Yabe; Haruya Toyomaki; Andrew Kataba; Hokuto Nakata; Kaampwe Muzandu; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Meta Gene, 27, Feb. 2021, [Peer-reviewed]
    English, Scientific journal
  • Levels of DDTs and other organochlorine pesticides in healthy wild Nile crocodiles (Crocodylus niloticus) from a flagship conservation area
    Ruan Gerber; Hindrik Bouwman; Danny Govender; Mayumi Ishizuka; Yoshinori Ikenaka; Yared B. Yohannes; Nico J. Smit; Victor Wepener
    Chemosphere, 264, Pt 1, 128368, 128368, Feb. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • An investigation of the wild rat crown incisor as an indicator of lead (Pb) exposure using inductively couple plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS
    Andrew Kataba; Shouta M.M. Nakayama; Hokuto Nakata; Haruya Toyomaki; Yared B. Yohannes; John Yabe; Kaampwe Muzandu; Golden Zyambo; Ayano Kubota; Takehisa Matsukawa; Kazuhito Yokoyama; Yoshinori Ikenaka; Mayumi Ishizuka
    International Journal of Environmental Research and Public Health, 18, 2, 1, 15, 02 Jan. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Simultaneous Detection Technique and Chronic Low-dose Accumulation Trends of Imidacloprid and its Metabolites in Tissues of C57BL/6J Mice
    NIMAKO Collins; IKENAKA Yoshinori; AKOTO Osei; FUJIOKA Kazutoshi; TAIRA Kumiko; ARIZONO Koji; KATO Keisuke; TAKAHASHI Keisuke; NAKAYAMA Shouta M.M.; ICHISE Takahiro; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 48.1, P-154E, The Japanese Society of Toxicology, 2021
    Japanese, The present study aimed to (i) develop a sensitive LC-MS/MS-based technique for simultaneous detection and quantification of Imidacloprid (IMI) and its metabolites in tissue specimens, and to (ii) determine the specific bioaccumulation trends of the IMI compounds in organs of C57BL/6J male mice; after exposure to 0.6 mg/kg bw/day of IMI (10% of NOAEL) through a powdered diet for 24 weeks. We successfully developed a method which was accurate (recoveries were ≥ 70% for most compounds), sensitive (LODs ≤ 0.47 ng/mL, LOQs ≤ 1.43 ng/mL and R2 ≥ 0.99) and precise (RSDs ≤ 20%) for routine analysis of IMI and seven of its metabolites in in blood and various tissues of mice. Upon biodistribution analysis, IMI and five of its metabolites were detected in various organs within mice. Blood, liver, mesenteric white adipose tissue and pancreas mainly accumulated IMI-olefin; brain, testis, inguinal white adipose tissue and gonadal white adipose tissue mainly accumulated IMI, whereas the kidney mainly accumulated 4-hydroxy-IMI. The N-desnitro-IMI metabolite showed unique accumulation in brain and testis by recording brain-blood and testis-blood detection ratios of 8.4 and 7.6, respectively. Cumulative levels of the six detected IMI compounds (Σ6 IMI compounds) were found in the decreasing order; blood > testis > iWAT > kidney > brain > gWAT > mWAT > pancreas > liver. The current study provides essential data needed for effective mechanistic elucidation of compound-specific adverse outcomes associated with chronic exposures to IMI in mammalian species.
  • Introduction: Cooperation with Mongolian University of Life Sciences in research activity
    Motohira Kodai; Dugar Delgermurun; Ikenaka Yoshinori; Nakayama Shouta; Pelden Bolormaa; Gendenpil Lkhamjav; Ishizuka Mayumi
    Proceedings of the Annual Meeting of Japan Society for Science Education, 45, 563, 564, Japan Society for Science Education, 2021
    Japanese, 発表者は北海道大学のJICAを通じたプロジェクトの一環で2019年に青年海外協力隊(獣医師)としてモンゴル生命科学大学獣医学部に短期派遣され、約1か月の研究支援を実施した。モンゴル国では残留抗生物質の検査体制の拡大が望まれており、発表者の活動により、日本から大学研究レベルの検査手法の開発とその研究プロセスの伝達、共有が実現された。帰国後も、現在に至るまでFacebook Messengerなどのツールを利用し、追加の検査手法開発に向けた継続的な研究協力関係を構築した。結果として、国際会議における科学的成果発表など、今回の活動により一定の進展があったことを社会に報告できた。しかし、専門性の高い研究レベルの支援を遠隔で実施する過程で双方、難点を抱える場面があった。本発表により発表者が実施した研究支援を踏まえ、開発途上国に対する大学研究レベルの支援の一例紹介、またその課題を共有する。
  • Neonicotinoid residues in commercial Japanese tea leaves produced by organic and conventional farming methods.
    Collins Nimako; Anri Hirai; Takahiro Ichise; Osei Akoto; Shouta M M Nakayama; Kumiko Taira; Kazutoshi Fujioka; Mayumi Ishizuka; Yoshinori Ikenaka
    Toxicology reports, 8, 1657, 1664, 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Chronic low-dose exposure to imidacloprid potentiates high fat diet-mediated liver steatosis in c57bl/6j male mice
    Collins Nimako; Yoshinori Ikenaka; Yuko Okamatsu-Ogura; Jussiaea V. Bariuan; Atsushi Kobayashi; Ryo Yamazaki; Kumiko Taira; Nobuhiko Hoshi; Tetsushi Hirano; Shouta M.M. Nakayama; Mayumi Ishizuka
    Journal of Veterinary Medical Science, 83, 3, 487, 500, 2021, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Urinary free metanephrines measurement in dogs with adrenal gland diseases using a new simple liquid chromatography tandem mass spectrometry method
    Noboru Sasaki; Yoshinori Ikenaka; Yumiko Inoue; Takahiro Ichise; Noriyuki Nagata; Mayumi Ishizuka; Syouta M.M. Nakayama; Kensuke Nakamura; Mitsuyoshi Takiguchi
    Journal of Veterinary Medical Science, 83, 4, 648, 655, 2021, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Interspecies differences in cytochrome P450-mediated metabolism of neonicotinoids among cats, dogs, rats, and humans
    Kraisiri Khidkhan; Yoshinori Ikenaka; Takahiro Ichise; Shouta M.M. Nakayama; Hazuki Mizukawa; Kei Nomiyama; Hisato Iwata; Koji Arizono; Keisuke Takahashi; Keisuke Kato; Mayumi Ishizuka
    Comparative Biochemistry and Physiology Part - C: Toxicology and Pharmacology, 239, 108898, 108898, Jan. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Clinical biochemical parameters associated with the exposure to multiple environmental metals in residents from Kabwe, Zambia
    Hokuto Nakata; Shouta M.M. Nakayama; John Yabe; Kaampwe Muzandu; Haruya Toyomaki; Yared Beyene Yohannes; Andrew Kataba; Golden Zyambo; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Chemosphere, 262, 127788, 127788, Jan. 2021, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Assessing the population-wide exposure to lead pollution in Kabwe, Zambia: an econometric estimation based on survey data
    Daichi Yamada; Masato Hiwatari; Peter Hangoma; Daiju Narita; Chrispin Mphuka; Bona Chitah; John Yabe; Shouta M.M. Nakayama; Hokuto Nakata; Kennedy Choongo; Mayumi Ishizuka
    Scientific Reports, 10, 1, 15092, 15092, 01 Dec. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Biosorption of Pb (II) and Zn (II) from aqueous solution by Oceanobacillus profundus isolated from an abandoned mine
    Wilson Mwandira; Kazunori Nakashima; Satoru Kawasaki; Allison Arabelo; Kawawa Banda; Imasiku Nyambe; Meki Chirwa; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Scientific Reports, 10, 1, 21189, 21189, Dec. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Lead, zinc and cadmium accumulation, and associated health risks, in maize grown near the kabwe mine in Zambia in response to organic and inorganic soil amendments
    Patricia N. Mwilola; Ikabongo Mukumbuta; Victor Shitumbanuma; Benson H. Chishala; Yoshitaka Uchida; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    International Journal of Environmental Research and Public Health, 17, 23, 1, 15, 01 Dec. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Land Use in Habitats Affects Metal Concentrations in Wild Lizards around a Former Lead Mining Site
    Rio Doya; Shouta M.M. Nakayama; Hokuto Nakata; Haruya Toyomaki; John Yabe; Kaampwe Muzandu; Yared B. Yohannes; Andrew Kataba; Golden Zyambo; Takahiro Ogawa; Yoshitaka Uchida; Yoshinori Ikenaka; Mayumi Ishizuka
    Environmental Science and Technology, 54, 22, 14474, 14481, 17 Nov. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Evaluation of phytoremediation effects of chicken manure, urea and lemongrass on remediating a lead contaminated soil in Kabwe, Zambia
    Yui Yoshii; Isabell von Rein; Kabenuka Munthali; Mukuka Mwansa; Hokuto Nakata; Shota Nakayama; Mayumi Ishizuka; Yoshitaka Uchida
    SOUTH AFRICAN JOURNAL OF PLANT AND SOIL, 37, 5, 351, 360, Nov. 2020, [Peer-reviewed]
    English, Scientific journal
  • Acute exposure to environmentally relevant lead levels induces oxidative stress and neurobehavioral alterations in larval zebrafish (Danio rerio)
    Andrew Kataba; Tarryn L. Botha; Shouta M.M. Nakayama; Yared B. Yohannes; Yoshinori Ikenaka; Victor Wepener; Mayumi Ishizuka
    Aquatic Toxicology, 227, 105607, 105607, Oct. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Immobilization of lead and zinc leached from mining residual materials in kabwe, zambia: Possibility of chemical immobilization by dolomite, calcined dolomite, and magnesium oxide
    Pawit Tangviroon; Kenta Noto; Toshifumi Igarashi; Takeshi Kawashima; Mayumi Ito; Tsutomu Sato; Walubita Mufalo; Meki Chirwa; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Minerals, 10, 9, 1, 16, Sep. 2020, [Peer-reviewed]
    Scientific journal
  • Blood lead levels and aberrant DNA methylation of the ALAD and p16 gene promoters in children exposed to environmental-lead
    Yared B. Yohannes; Shouta MM Nakayama; John Yabe; Hokuto Nakata; Haruya Toyomaki; Andrew Kataba; Kaampwe Muzandu; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Environmental Research, 188, 109759, 109759, Sep. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Relationship between blood test values and blood lead (Pb) levels in Black-headed gull (Chroicocephalus ridibundus: Laridae).
    Nana Ushine; Shouta M M Nakayama; Mayumi Ishizuka; Tatsuo Sato; Yoshihiro Kurahashi; Emu Wakayama; Natsuko Sugiura; Shin-Ichi Hayama
    The Journal of veterinary medical science, 82, 8, 1124, 1129, 19 Aug. 2020, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Current situation regarding lead exposure in birds in Japan (2015-2018); lead exposure is still occurring.
    Chihiro Ishii; Yoshinori Ikenaka; Shouta M M Nakayama; Takeshi Kuritani; Mitsuhiro Nakagawa; Keisuke Saito; Yukiko Watanabe; Kohei Ogasawara; Manabu Onuma; Atsushi Haga; Mayumi Ishizuka
    The Journal of veterinary medical science, 82, 8, 1118, 1123, 19 Aug. 2020, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Trophic transfer of pollutants within two intertidal rocky shore ecosystems in different biogeographic regions of South Africa
    Anja Erasmus; Yoshinori Ikenaka; Shouta M.M. Nakayama; Mayumi Ishizuka; Nico J. Smit; Victor Wepener
    Marine Pollution Bulletin, 157, 111309, 111309, Aug. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Detoxification of lead-bearing zinc plant leach residues from Kabwe, Zambia by coupled extraction-cementation method
    Marthias Silwamba; Mayumi Ito; Naoki Hiroyoshi; Carlito Baltazar Tabelin; Tomoki Fukushima; Ilhwan Park; Sanghee Jeon; Toshifumi Igarashi; Tsutomu Sato; Imasiku Nyambe; Meki Chirwa; Kawawa Banda; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Journal of Environmental Chemical Engineering, 8, 4, 104197, 104197, Elsevier BV, Aug. 2020, [Peer-reviewed]
    Scientific journal
  • Altered hepatic cytochrome p450 expression in cats after chronic exposure to decabromodiphenyl ether (Bde-209)
    Kraisiri Khidkhan; Hazuki Mizukawa; Yoshinori Ikenaka; Shouta M.M. Nakayama; Kei Nomiyama; Nozomu Yokoyama; Osamu Ichii; Mitsuyoshi Takiguchi; Shinsuke Tanabe; Mayumi Ishizuka
    Journal of Veterinary Medical Science, 82, 7, 978, 982, Jul. 2020, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • エジプシャンルーセットオオコウモリ(Rousettus aegyptiacus)における抗血液凝固系殺鼠剤の薬物動態学/薬力学的解析
    武田 一貴; 真砂 皓大; 中山 翔太; 川合 佑典; 池中 良徳; 石塚 真由美
    The Journal of Toxicological Sciences, 45, Suppl., S181, S182, (一社)日本毒性学会, Jun. 2020
    Japanese
  • Comparison of two reducing agents dithiothreitol and tris(3-hydroxypropyl)phosphine for in vitro kinetic assay of vitamin K epoxide reductase
    Kazuki Takeda; Ayuko Morita; Yoshinori Ikenaka; Shouta M.M. Nakayama; Mayumi Ishizuka
    Veterinary and Animal Science, 9, 100095, 100095, Jun. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Using Stable Î13C and Î15N Isotopes to Assess Foodweb Structures in an African Subtropical Temporary Pool
    L. De Necker; A. Manfrin; Y. Ikenaka; M. Ishizuka; L. Brendonck; J. H.J. Van Vuren; B. Sures; V. Wepener; N. J. Smit
    African Zoology, 55, 1, 79, 92, May 2020, [Peer-reviewed]
    Scientific journal
  • Factors associated with lead (Pb) exposure on dogs around a Pb mining area, Kabwe, Zambia
    Haruya Toyomaki; John Yabe; Shouta M.M. Nakayama; Yared B. Yohannes; Kaampwe Muzandu; Allan Liazambi; Yoshinori Ikenaka; Takeshi Kuritani; Mitsuhiro Nakagawa; Mayumi Ishizuka
    Chemosphere, 247, 125884, 125884, May 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Recovery of lead and zinc from zinc plant leach residues by concurrent dissolution-cementation using zero-valent aluminum in chloride medium
    Marthias Silwamba; Mayumi Ito; Naoki Hiroyoshi; Carlito Baltazar Tabelin; Ryota Hashizume; Tomoki Fukushima; Ilhwan Park; Sanghee Jeon; Toshifumi Igarashi; Tsutomu Sato; Meki Chirwa; Kawawa Banda; Imasiku Nyambe; Hokuto Nakata; Shouta Nakayama; Mayumi Ishizuka
    Metals, 10, 4, 531, 531, MDPI AG, Apr. 2020, [Peer-reviewed]
    Scientific journal
  • Quantitative elucidation of maternal-to-fetal transfer of neonicotinoid pesticide clothianidin and its metabolites in mice
    Shuji Ohno; Yoshinori Ikenaka; Kanoko Onaru; Shizuka Kubo; Nanami Sakata; Tetsushi Hirano; Youhei Mantani; Toshifumi Yokoyama; Keisuke Takahashi; Keisuke Kato; Koji Arizono; Takahiro Ichise; Shouta M.M. Nakayama; Mayumi Ishizuka; Nobuhiko Hoshi
    Toxicology Letters, 322, 32, 38, Apr. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Combined exposure to dinotefuran and chronic mild stress counteracts the change of the emotional and monoaminergic neuronal activity induced by either exposure singly despite corticosterone elevation in mice.
    Tadashi Takada; Naoki Yoneda; Tetsushi Hirano; Kanoko Onaru; Youhei Mantani; Toshifumi Yokoyama; Hiroshi Kitagawa; Yoshiaki Tabuchi; Collins Nimako; Mayumi Ishizuka; Yoshinori Ikenaka; Nobuhiko Hoshi
    The Journal of veterinary medical science, 82, 3, 350, 359, 24 Mar. 2020, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Current trends of blood lead levels, distribution patterns and exposure variations among household members in Kabwe, Zambia
    John Yabe; Shouta MM Nakayama; Hokuto Nakata; Haruya Toyomaki; Yared B. Yohannes; Kaampwe Muzandu; Andrew Kataba; Golden Zyambo; Masato Hiwatari; Daiju Narita; Daichi Yamada; Peter Hangoma; Nosiku Sipilanyambe Munyinda; Tiza Mufune; Yoshinori Ikenaka; Kennedy Choongo; Mayumi Ishizuka
    Chemosphere, 243, 125412, 125412, Mar. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • In Vivo Accumulation of Plastic-Derived Chemicals into Seabird Tissues.
    Kosuke Tanaka; Yutaka Watanuki; Hideshige Takada; Mayumi Ishizuka; Rei Yamashita; Mami Kazama; Nagako Hiki; Fumika Kashiwada; Kaoruko Mizukawa; Hazuki Mizukawa; David Hyrenbach; Michelle Hester; Yoshinori Ikenaka; Shouta M M Nakayama
    Current biology : CB, 30, 4, 723, 728, 24 Feb. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Avian interspecific differences in VKOR activity and inhibition: Insights from amino acid sequence and mRNA expression ratio of VKORC1 and VKORC1L1.
    Shouta M M Nakayama; Ayuko Morita; Yoshinori Ikenaka; Yusuke K Kawai; Kensuke P Watanabe; Chihiro Ishii; Hazuki Mizukawa; Yared B Yohannes; Keisuke Saito; Yukiko Watanabe; Masaki Ito; Natsuo Ohsawa; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 228, 108635, 108635, Feb. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Signal toxicity caused by nicotinic acetylcholine receptor agonist and development of detection method using two-photon microscope
    HIRAI Anri; SUGIO Shouta; IKENAKA Yoshinori; COLLINS Nimako; NAKAYAMA Shouta M.M; HOSHI Nobuhiko; WAKE Hiroaki; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 47.1, P-4S, The Japanese Society of Toxicology, 2020
    Japanese, By acting on receptors in the brain, some chemicals exhibit "signal toxicity" that disrupts intracellular and intercellular signaling, causing unexpected effects. In particular, in brain function, a complex signal network between neurons and glial cells is formed, and disruption of this network can be a critical endpoint of signal toxicity. However, “disruption of brain function” due to signal toxicity is often not accompanied by cell death and accompanying brain tissue degeneration, and cannot be detected by current neurotoxicity test methods. In this study, we used neonicotinoids (NNs) and nicotine, which are agonists of the nicotinic acetylcholine receptor (nAChR), as model compounds, and detected changes in neuronal activity in the somatosensory cortex using a two-photon microscope. The aim was to detect disruption of brain function associated with signal toxicity.

    C57BL/6N were orally administered ACE at 20 mg/kg (with reference to LOAEL in general pharmacology test of the central nervous system) and their blood was collected over time. It was analyzed quantitatively using LC-MS/MS. Then, we exposed mice to ACE at 20 mg/kg or 7.1 mg/kg (with reference to NOAEL to rats), and their behavior was observed using openfield (OF) test 1 hour after the administration at the former concentration, and using elevated plus maze (EPM) test 1 hour after the administration at the latter concentration. In addition, C57BL/6J were administered ACE at 30 mg/kg (with reference to NOAEL in the subacute toxicity test) and Nicotine, which is the typical agonist of nAChR, at 1.6 mg/kg (with reference to 1/2 LD50), and the neuronal activity in somatosensory cortex was observed over time by using two-photon microscope.

    As a result, ACE absorbed quickly and the Tmax of ACE was around 25 minutes after administration. In comparison, dm-ACE, which is one of its major metabolites, absorbed a bit slower and the Tmax was around 150 minutes. An hour after the administration, the activity of mice decreased, and the anxiety-like behavior increased. In the somatosensory cortex, the firing frequency of nerve cells decreased, and the synchronous firing increased, 1 hour and 2.5 hour after ACE administration. Similarly, the firing frequency tended to decrease, and the synchronous firing increased, 5 minutes and 30 minutes after the administration of Nicotine. This suggest that changes in neuronal activity after administration of ACE are the result of ACE acting as a ligand for nAChR because we can see the same trends between ACE and Nicotine. In summary, it was observed that administration of ACE at a concentration that is originally non-toxic, such as NOAEL, affects the behavior and neural activities. This suggests that cranial nerve activity is responsible for changes in behavior.
  • Review on counter measures to coronavirus disease 2019 (COVID-19) pandemic, May 2020
    Taishi Kidaka; Sithumini M.W. Lokupathirage; Bungiriye Devinda Shameera Muthusinghe; Boniface Lombe Pongombo; Christida Estu Wastika; Zhouxing Wei; Shizuka Yoshioka; Mayumi Ishizuka; Yoshihiro Sakoda; Hiroaki Kariwa; Norikazu Isoda
    Japanese Journal of Veterinary Research, 68, 3, 133, 150, 2020
    Scientific journal
  • Bioimaging of Pb and STIM1 in mice liver, kidney and brain using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) and immunohistochemistry.
    Masao Togao; Shouta M M Nakayama; Yoshinori Ikenaka; Hazuki Mizukawa; Yoshiki Makino; Ayano Kubota; Takehisa Matsukawa; Kazuhito Yokoyama; Takafumi Hirata; Mayumi Ishizuka
    Chemosphere, 238, 124581, 124581, Jan. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Occurrence and concentrations of chemical additives in plastic fragments on a beach on the island of Kauai, Hawaii.
    Kosuke Tanaka; Hideshige Takada; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka
    Marine pollution bulletin, 150, 110732, 110732, Jan. 2020, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Elucidation of indoor pollution and risk assessment seen from pet animals
    水川葉月; 野見山桂; 池中良徳; 中山翔太; 石塚真由美; 高橋真
    環境ホルモン学会研究発表会プログラム・要旨集, 22回, 45, 45, 環境ホルモン学会(日本内分泌撹乱化学物質学会), Dec. 2019
    Japanese
  • Tissue distribution and characterization of feline cytochrome P450 genes related to polychlorinated biphenyl exposure.
    Kraisiri Khidkhan; Hazuki Mizukawa; Yoshinori Ikenaka; Shouta M M Nakayama; Kei Nomiyama; Nozomu Yokoyama; Osamu Ichii; Wageh Sobhy Darwish; Mitsuyoshi Takiguchi; Shinsuke Tanabe; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 226, 108613, 108613, Dec. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Dichlorodiphenyltrichloroethane (DDT) levels in rat livers collected from a malaria vector control region.
    Kodai Motohira; Yoshinori Ikenaka; Yared Beyene Yohannes; Shouta M M Nakayama; Victor Wepener; Nico J Smit; Johan H J VAN Vuren; Ana Catarina Sousa; Alex Ajeh Enuneku; Emmanuel Temiotan Ogbomida; Mayumi Ishizuka
    The Journal of veterinary medical science, 81, 11, 1575, 1579, 14 Nov. 2019, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Effects of the organochlorine p,p'-DDT on MCF-7 cells: Investigating metabolic and immune modulatory transcriptomic changes.
    Lesa A Thompson; Yoshinori Ikenaka; Wageh Sobhy Darwish; Shouta M M Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    Environmental toxicology and pharmacology, 72, 103249, 103249, Nov. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Effects of PCB exposure on serum thyroid hormone levels in dogs and cats.
    Kohki Takaguchi; Hiroyuki Nishikawa; Hazuki Mizukawa; Rumi Tanoue; Nozomu Yokoyama; Osamu Ichii; Mitsuyoshi Takiguchi; Shouta M M Nakayama; Yoshinori Ikenaka; Tatsuya Kunisue; Mayumi Ishizuka; Shinsuke Tanabe; Hisato Iwata; Kei Nomiyama
    The Science of the total environment, 688, 1172, 1183, 20 Oct. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Bioaccumulation of persistent organic pollutants and their trophic transfer through the food web: Human health risks to the rural communities reliant on fish from South Africa's largest floodplain
    C.M. Volschenk; R. Gerber; M.T. Mkhonto; Y. Ikenaka; Y.B. Yohannes; S. Nakayama; M. Ishizuka; J.H.J. van Vuren; V. Wepener; N.J. Smit
    Science of The Total Environment, 685, 1116, 1126, Elsevier BV, Oct. 2019
    Scientific journal
  • How toxic is a non-toxic nanomaterial: Behaviour as an indicator of effect in Danio rerio exposed to nanogold.
    Tarryn L Botha; Sarel J Brand; Yoshinori Ikenaka; Shouta M M Nakayama; Mayumi Ishizuka; Victor Wepener
    Aquatic toxicology (Amsterdam, Netherlands), 215, 105287, 105287, Oct. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • One year exposure to Cd- and Pb-contaminated soil causes metal accumulation and alteration of global DNA methylation in rats.
    Shouta M M Nakayama; Hokuto Nakata; Yoshinori Ikenaka; John Yabe; Balazs Oroszlany; Yared B Yohannes; Nesta Bortey-Sam; Kaampwe Muzandu; Kennedy Choongo; Takeshi Kuritani; Mitsuhiro Nakagawa; Mayumi Ishizuka
    Environmental pollution (Barking, Essex : 1987), 252, Pt B, 1267, 1276, Sep. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • An epigenome-wide analysis of cord blood DNA methylation reveals sex-specific effect of exposure to bisphenol A.
    Ryu Miura; Atsuko Araki; Machiko Minatoya; Kunio Miyake; Mei-Lien Chen; Sumitaka Kobayashi; Chihiro Miyashita; Jun Yamamoto; Toru Matsumura; Mayumi Ishizuka; Takeo Kubota; Reiko Kishi
    Scientific reports, 9, 1, 12369, 12369, 26 Aug. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Solidification of sand by Pb(II)-tolerant bacteria for capping mine waste to control metallic dust: Case of the abandoned Kabwe Mine, Zambia.
    Wilson Mwandira; Kazunori Nakashima; Satoru Kawasaki; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Meki Chirwa; Kawawa Banda; Imasiku Nyambe; Shouta Nakayama; Hokuto Nakata; Mayumi Ishizuka
    Chemosphere, 228, 17, 25, Aug. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Zinc and Lead Biosorption by Oceanobacillus Profundus Kbz 3-2: a Bacterial Strain Resistant to Metals Isolated from Metal polluted Soils in Kabwe, Zambia
    Wilson Mwandira; Kazunori Nakashima; Satoru Kawasaki; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Meki Chirwa; Kawawa Banda; Imasiku Nyambe; Shouta Nakayama; Mayumi Ishizuka
    Proceedings of the 14th Asian Congress on Biotechnology (ACB2019), Jul. 2019, [Peer-reviewed]
    English, International conference proceedings
  • ネオニコチノイド系殺虫剤と農薬の現状と今後の展望〜毒性学・農学・行政の視点から〜 ネオニコチノイド系殺虫剤の曝露実態の解明と毒性評価
    池中 良徳; 一瀬 貴大; Nimako Collins; 中山 翔太; 平野 哲史; 市川 剛; 加藤 恵介; 高橋 圭介; 長谷川 浩; 平 久美子; 有薗 幸司; 星 信彦; 藤岡 一俊; 石塚 真由美
    The Journal of Toxicological Sciences, 44, Suppl., S53, S53, (一社)日本毒性学会, Jun. 2019
    Japanese
  • Evidence of impacts from DDT in pelican, cormorant, stork, and egret eggs from KwaZulu-Natal, South Africa.
    H Bouwman; Y B Yohannes; S M M Nakayama; K Motohira; M Ishizuka; M S Humphries; V van der Schyff; M du Preez; A Dinkelmann; Y Ikenaka
    Chemosphere, 225, 647, 658, Jun. 2019, [International Magazine]
    English, Scientific journal
  • Baseline bio-accumulation concentrations and resulting oxidative stress in Synodontis zambezensis after an acute laboratory exposure to 4,4'-DDT.
    C M Volschenk; Y Ikenaka; Y B Yohannes; S M Nakayama; M Ishizuka; E Smit; J H J van Vuren; R Greenfield
    Pesticide biochemistry and physiology, 156, 44, 55, May 2019, [International Magazine]
    English, Scientific journal
  • Functional and molecular characterization of UDP-glucuronosyltransferase 2 family in cynomolgus macaques.
    Yasuhiro Uno; Rika Takahira; Norie Murayama; Shunsuke Onozeki; Shu Kawamura; Shotaro Uehara; Yoshinori Ikenaka; Mayumi Ishizuka; Shinichi Ikushiro; Hiroshi Yamazaki
    Biochemical pharmacology, 163, 335, 344, May 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Efficacy of biocementation of lead mine waste from the Kabwe Mine site evaluated using Pararhodobacter sp.
    Wilson Mwandira; Kazunori Nakashima; Satoru Kawasaki; Mayumi Ito; Tsutomu Sato; Toshifumi Igarashi; Kawawa Banda; Meki Chirwa; Imasiku Nyambe; Shouta Nakayama; Mayumi Ishizuka
    Environmental science and pollution research international, 26, 15, 15653, 15664, May 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Characterization of function and genetic feature of UDP-glucuronosyltransferase in avian species.
    Yusuke K Kawai; So Shinya; Yoshinori Ikenaka; Aksorn Saengtienchai; Takamitsu Kondo; Wageh Sobhy Darwish; Shota M M Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 217, 5, 14, Mar. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • A review: poisoning by anticoagulant rodenticides in non-target animals globally.
    Shouta M M Nakayama; Ayuko Morita; Yoshinori Ikenaka; Hazuki Mizukawa; Mayumi Ishizuka
    The Journal of veterinary medical science, 81, 2, 298, 313, 28 Feb. 2019, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • Biotransport of metallic trace elements from marine to terrestrial ecosystems by seabirds.
    Shoji A; Elliott KH; Aris-Brosou S; Mizukawa H; Nakayama SMM; Ikenaka Y; Ishizuka M; Kuwae T; Watanabe K; Escoruela Gonzalez J; Watanuki Y
    Environmental toxicology and chemistry, 38, 1, 106, 114, Jan. 2019, [Peer-reviewed]
    Scientific journal
  • Exposures of children to neonicotinoids in pine wilt disease control areas.
    Yoshinori Ikenaka; Yuichi Miyabara; Takahiro Ichise; Shouta Nakayama; Collins Nimako; Mayumi Ishizuka; Chiharu Tohyama
    Environmental toxicology and chemistry, 38, 1, 71, 79, Jan. 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • LC-ESI/MS/MS analysis of neonicotinoids in urine of very low birth weight infants at birth.
    Go Ichikawa; Ryota Kuribayashi; Yoshinori Ikenaka; Takahiro Ichise; Shouta M M Nakayama; Mayumi Ishizuka; Kumiko Taira; Kazutoshi Fujioka; Toshimi Sairenchi; Gen Kobashi; Jean-Marc Bonmatin; Shigemi Yoshihara
    PloS one, 14, 7, e0219208, 2019, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Comparison of xenobiotic metabolism in phase I oxidation and phase II conjugation between rats and bird species.
    Aksorn Saengtienchai; Yoshinori Ikenaka; Minami Kawata; Yusuke Kawai; Kazuki Takeda; Takamitsu Kondo; Nesta Bortey-Sam; Shouta M M Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    Comparative biochemistry and physiology. Toxicology & pharmacology : CBP, 214, 28, 35, Dec. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Characterization and imaging of lead distribution in bones of lead-exposed birds by ICP-MS and LA-ICP-MS.
    Chihiro Ishii; Shouta M M Nakayama; Andrew Kataba; Yoshinori Ikenaka; Keisuke Saito; Yukiko Watanabe; Yoshiki Makino; Takehisa Matsukawa; Ayano Kubota; Kazuhito Yokoyama; Hazuki Mizukawa; Takafumi Hirata; Mayumi Ishizuka
    Chemosphere, 212, 994, 1001, Dec. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Linking organochlorine exposure to biomarker response patterns in Anurans: a case study of Muller's clawed frog (Xenopus muelleri) from a tropical malaria vector control region
    Nico J. Wolmarans; Louis H. Du Preez; Yared Beyene Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Nico J. Smit; Victor Wepener
    ECOTOXICOLOGY, 27, 9, 1203, 1216, Nov. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Molecular and functional characterization of UDP-glucuronosyltransferase 1A in cynomolgus macaques.
    Yasuhiro Uno; Rika Takahira; Norie Murayama; Yu Ishii; Yoshinori Ikenaka; Mayumi Ishizuka; Hiroshi Yamazaki; Shinichi Ikushiro
    Biochemical pharmacology, 155, 172, 181, Sep. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Characterization, Spatial Variation and Risk Assessment of Heavy Metals and a Metalloid in Surface Soils in Obuasi, Ghana.
    Osei Akoto; Nesta Bortey-Sam; Shouta M M Nakayama; Yoshinori Ikenaka; Elvis Baidoo; Joseph Apau; Jemima Tiwaa Marfo; Mayumi Ishizuka
    Journal of health & pollution, 8, 19, 180902, 180902, Sep. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Fish consumption from urban impoundments: What are the health risks associated with DDTs and other organochlorine pesticides in fish to township residents of a major inland city.
    Wihan Pheiffer; Nico J Wolmarans; Ruan Gerber; Yared B Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Nico J Smit; Victor Wepener; Rialet Pieters
    The Science of the total environment, 628-629, 517, 527, 01 Jul. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Lead and cadmium excretion in feces and urine of children from polluted townships near a lead-zinc mine in Kabwe, Zambia
    John Yabe; Shouta M. M. Nakayama; Yoshinori Ikenaka; Yared B. Yohannes; Nesta Bortey-Sam; Abel Nketani Kabalo; John Ntapisha; Hazuki Mizukawa; Takashi Umemura; Mayumi Ishizuka
    CHEMOSPHERE, 202, 48, 55, Jul. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Serologic Evidence of Tick-Borne Encephalitis Virus Infection in a Patient with Suspected Lyme Disease in Japan.
    Yoshii K; Sato K; Ishizuka M; Kobayashi S; Kariwa H; Kawabata H
    The American journal of tropical medicine and hygiene, 99, 1, 180, 181, Jul. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal, Tick-borne encephalitis (TBE) is widely prevalent on the Eurasian continent, including Japan, but four cases of TBE have been reported in Japan. To inspect unconfirmed TBE cases in Japan, we conducted a retrospective seroepidemiological study of a total of 158 samples from 81 meningoencephalitis patients suspected as Lyme disease. Two serum samples from one patient showed neutralizing antibodies against TBE virus. The patient with severe and progressive encephalitis had a history of tick bite in Hokkaido in 2012. These results demonstrated that tick-borne encephalitis virus (TBEV) case was actually unconfirmed in Japan. Further seroepidemiological surveys are required to identify unconfirmed TBEV infections to consider the pros and cons of introducing specific countermeasures including vaccination in Japan.
  • An epigenome-wide study of cord blood DNA methylations in relation to prenatal perfluoroalkyl substance exposure: The Hokkaido study
    Ryu Miura; Atsuko Araki; Chihiro Miyashita; Sumitaka Kobayashi; Sachiko Kobayashi; Shu-Li Wang; Chung-Hsing Chen; Kunio Miyake; Mayumi Ishizuka; Yusuke Iwasaki; Yoichi M. Ito; Takeo Kubota; Reiko Kishi
    Environment International, 115, 21, 28, Elsevier Ltd, 01 Jun. 2018, [Peer-reviewed]
    English, Scientific journal
  • Investigation of hepatic warfarin metabolism activity in rodenticide-resistant black rats (Rattus rattus) in Tokyo by in situ liver perfusion.
    Kazuki Takeda; Yoshinori Ikenaka; Kazuyuki D Tanaka; Shouta M M Nakayama; Tsutomu Tanikawa; Hazuki Mizukawa; Mayumi Ishizuka
    Pesticide biochemistry and physiology, 148, 42, 49, Jun. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • A glycomics approach to discover novel renal biomarkers in birds by administration of cisplatin and diclofenac to chickens.
    Ishii C; Ikenaka Y; Ichii O; Nakayama SMM; Nishimura SI; Ohashi T; Tanaka M; Mizukawa H; Ishizuka M
    Poultry science, 97, 5, 1722, 1729, May 2018, [Peer-reviewed]
    Scientific journal
  • Accumulation patterns and risk assessment of metals and metalloid in muscle and offal of free-range chickens, cattle and goat in Benin City, Nigeria.
    Emmanuel Temiotan Ogbomida; Shouta M M Nakayama; Nesta Bortey-Sam; Balazs Oroszlany; Isioma Tongo; Alex Ajeh Enuneku; Ogbeide Ozekeke; Martins Oshioriamhe Ainerua; Iriagbonse Priscillia Fasipe; Lawrence Ikechukwu Ezemonye; Hazuki Mizukawa; Yoshinori Ikenaka; Mayumi Ishizuka
    Ecotoxicology and environmental safety, 151, 98, 108, 30 Apr. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Association between human exposure to heavy metals/metalloid and occurrences of respiratory diseases, lipid peroxidation and DNA damage in Kumasi, Ghana.
    Nesta Bortey-Sam; Yoshinori Ikenaka; Osei Akoto; Shouta M M Nakayama; Kwadwo A Asante; Elvis Baidoo; Christian Obirikorang; Hazuki Mizukawa; Mayumi Ishizuka
    Environmental pollution (Barking, Essex : 1987), 235, 163, 170, Apr. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Sex and site differences in urinary excretion of conjugated pyrene metabolites in the West African Shorthorn cattle.
    Nesta Bortey-Sam; Yoshinori Ikenaka; Osei Akoto; Shouta M M Nakayama; Jemima T Marfo; Aksorn Saengtienchai; Hazuki Mizukawa; Mayumi Ishizuka
    The Journal of veterinary medical science, 80, 2, 375, 381, 02 Mar. 2018, [Peer-reviewed], [Domestic magazines]
    English, Scientific journal
  • β-carotene and retinol reduce benzo[a]pyrene-induced mutagenicity and oxidative stress via transcriptional modulation of xenobiotic metabolizing enzymes in human HepG2 cell line.
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta Nakayama; Hazuki Mizukawa; Lesa A Thompson; Mayumi Ishizuka
    Environmental science and pollution research international, 25, 7, 6320, 6328, Mar. 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Evaluation of mitochondrial redox status and energy metabolism of X-irradiated HeLa cells by LC/UV, LC/MS/MS and ESR
    Kumiko Yamamoto; Yoshinori Ikenaka; Takahiro Ichise; Tomoki Bo; Mayumi Ishizuka; Hironobu Yasui; Wakako Hiraoka; Tohru Yamamori; Osamu Inanami
    FREE RADICAL RESEARCH, 52, 6, 648, 660, 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Contamination by neonicotinoid insecticides and their metabolites in Sri Lankan black tea leaves and Japanese green tea leaves.
    Yoshinori Ikenaka; Kazutoshi Fujioka; Tomonori Kawakami; Takahiro Ichise; Nesta Bortey-Sam; Shouta M M Nakayama; Hazuki Mizukawa; Kumiko Taira; Keisuke Takahashi; Keisuke Kato; Koji Arizono; Mayumi Ishizuka
    Toxicology reports, 5, 744, 749, 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Investigation of mRNA expression changes associated with field exposure to DDTs in chickens from KwaZulu-Natal, South Africa.
    Lesa A Thompson; Yoshinori Ikenaka; Wageh S Darwish; Yared B Yohannes; Johan J van Vuren; Victor Wepener; Nico J Smit; Atnafu G Assefa; Ahmed Tharwat; Walaa Fathy Saad Eldin; Shouta M M Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    PloS one, 13, 10, e0204400, 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • ポリ塩化ビフェニル曝露によるイヌ・ネコの甲状腺ホルモン恒常性への影響
    高口倖暉; 野見山桂; 西川博之; 水川葉月; 田上瑠美; 草木桃子; 横山望; 市居修; 滝口満喜; 中山翔太; 池中良徳; 石塚真由美; 岩田久人; 国末達也; 田辺信介
    Journal of Toxicological Sciences, 43, Supplement, S245, S245, (一社)日本毒性学会, 2018, [Peer-reviewed]
    Japanese
  • Regulatory science on AI-based medical devices and systems
    Kiyoyuki Chinzei; Akinobu Shimizu; Kensaku Mori; Kanako Harada; Hideaki Takeda; Makoto Hashizume; Mayumi Ishizuka; Nobumasa Kato; Ryuzo Kawamori; Shunei Kyo; Kyosuke Nagata; Takashi Yamane; Ichiro Sakuma; Kazuhiko Ohe; Mamoru Mitsuishi
    Advanced Biomedical Engineering, 7, 118, 123, 2018
  • The evolution of UDP-glycosyl/glucuronosyltransferase 1E (UGT1E) genes in bird lineages is linked to feeding habits but UGT2 genes is not.
    Yusuke K Kawai; Yoshinori Ikenaka; Mayumi Ishizuka; Akira Kubota
    PloS one, 13, 10, e0205266, 2018, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Lead exposure in raptors from Japan and source identification using Pb stable isotope ratios
    Chihiro Ishii; Shouta M. M. Nakayama; Yoshinori Ikenaka; Hokuto Nakata; Keisuke Saito; Yukiko Watanabe; Hazuki Mizukawa; Shinsuke Tanabe; Kei Nomiyama; Terutake Hayashi; Mayumi Ishizuka
    CHEMOSPHERE, 186, 367, 373, Nov. 2017, [Peer-reviewed]
    English, Scientific journal
  • Spatial and temporal profile of cisplatin delivery by ultrasound-assisted intravesical chemotherapy in a bladder cancer model
    Noboru Sasaki; Kazuhiro Ishi; Nobuki Kudo; Shouta M. M. Nakayama; Kensuke Nakamura; Keitaro Morishita; Hiroshi Ohta; Mayumi Ishizuka; Mitsuyoshi Takiguchi
    PLOS ONE, 12, 11, e0188093, Nov. 2017, [Peer-reviewed]
    English, Scientific journal
  • Anthropogenic and Naturally Produced Brominated Phenols in Pet Blood and Pet Food in Japan
    Hazuki Mizukawa; Kei Nomiyama; Susumu Nakatsu; Miyuki Yamamoto; Mayumi Ishizuka; Yoshinori Ikenaka; Shouta M. M. Nakayama; Shinsuke Tanabe
    ENVIRONMENTAL SCIENCE & TECHNOLOGY, 51, 19, 11354, 11362, Oct. 2017, [Peer-reviewed]
    English, Scientific journal
  • Assessment of DDT contamination in house rat as a possible bioindicator in DDT-sprayed areas from Ethiopia and South Africa
    Yared Beyene Yohannes; Yoshinori Ikenaka; Gengo Ito; Shouta M. M. Nakayama; Hazuki Mizukawa; Victor Wepener; Nico J. Smit; Johan H. J. Van Vuren; Mayumi Ishizuka
    ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 24, 30, 23763, 23770, Oct. 2017, [Peer-reviewed]
    English, Scientific journal
  • Oxidative stress and respiratory symptoms due to human exposure to polycyclic aromatic hydrocarbons (PAHs) in Kumasi, Ghana
    Nesta Bortey-Sam; Yoshinori Ikenaka; Osei Akoto; Shouta M. M. Nakayama; Kwadwo A. Asante; Elvis Baidoo; Christian Obirikorang; Aksorn Saengtienchai; Norikazu Isoda; Collins Nimako; Hazuki Mizukawa; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 228, 311, 320, Sep. 2017, [Peer-reviewed]
    English, Scientific journal
  • Gender-specific association of exposure to non-dioxin-like polychlorinated biphenyls during pregnancy with methylation levels of H19 and long interspersed nuclear element-1 in cord blood in the Hokkaido study
    Sumitaka Kobayashi; Fumihiro Sata; Chihiro Miyashita; Ryu Miura; Kaoru Azumi; Sachiko Kobayashi; Houman Goudarzi; Atsuko Araki; Mayumi Ishizuka; Takashi Todaka; Jumboku Kajiwara; Tsuguhide Hori; Reiko Kishi
    TOXICOLOGY, 390, 135, 145, Sep. 2017, [Peer-reviewed]
    English, Scientific journal
  • Contamination Levels and Sources of Heavy Metals and a Metalloid in Surface Soils in the Kumasi Metropolis, Ghana.
    Osei Akoto; Nesta Bortey-Sam; Yoshinori Ikenaka; Shouta M M Nakayama; Elvis Baidoo; Yared Beyene Yohannes; Mayumi Ishizuka
    Journal of health & pollution, 7, 15, 28, 39, Sep. 2017, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Uridine Diphosphate-Glucuronosyltransferase (UGT) 2B Subfamily Interspecies Differences in Carnivores
    Takamitsu Kondo; Yoshinori Ikenaka; Shouta M. M. Nakayama; Yusuke K. Kawai; Hazuki Mizukawa; Yoko Mitani; Kei Nomiyama; Shinsuke Tanabe; Mayumi Ishizuka
    TOXICOLOGICAL SCIENCES, 158, 1, 90, 100, Jul. 2017, [Peer-reviewed]
    English, Scientific journal
  • Effects of prenatal perfluoroalkyl acid exposure on cord blood IGF2/H19 methylation and ponderal index: The Hokkaido Study
    Sachiko Kobayashi; Kaoru Azumi; Houman Goudarzi; Atsuko Araki; Chihiro Miyashita; Sumitaka Kobayashi; Sachiko Itoh; Seiko Sasaki; Mayumi Ishizuka; Hiroyuki Nakazawa; Tamiko Ikeno; Reiko Kishi
    JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, 27, 3, 251, 259, May 2017, [Peer-reviewed]
    English, Scientific journal
  • Organochlorine pesticide contamination of foods in Africa: incidence and public health significance
    Lesa A. Thompson; Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 79, 4, 751, 764, Apr. 2017, [Peer-reviewed]
    English
  • Contamination status and accumulation characteristics of heavy metals and arsenic in five seabird species from the central Bering Sea
    Chihiro Ishii; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Yared Beyene Yohannes; Yutaka Watanuki; Masaaki Fukuwaka; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 79, 4, 807, 814, Apr. 2017, [Peer-reviewed]
    English, Scientific journal
  • Characterization of Species Differences in Xenobiotic Metabolism in Non-experimental Animals
    Hazuki Mizukawa; Yoshinori Ikenaka; Mayu Kakehi; Shouta Nakayama; Mayumi Ishizuka
    YAKUGAKU ZASSHI-JOURNAL OF THE PHARMACEUTICAL SOCIETY OF JAPAN, 137, 3, 257, 263, Mar. 2017, [Peer-reviewed]
    Chinese
  • Trace Element Contamination in Tissues of Four Bird Species from the Rift Valley Region, Ethiopia
    Yared Beyene Yohannes; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 98, 2, 172, 177, Feb. 2017, [Peer-reviewed]
    English, Scientific journal
  • Monitoring Lead (Pb) Pollution and Identifying Pb Pollution Sources in Japan Using Stable Pb Isotope Analysis with Kidneys of Wild Rats.
    Hokuto Nakata; Shouta M M Nakayama; Balazs Oroszlany; Yoshinori Ikenaka; Hazuki Mizukawa; Kazuyuki Tanaka; Tsunehito Harunari; Tsutomu Tanikawa; Wageh Sobhy Darwish; Yared B Yohannes; Aksorn Saengtienchai; Mayumi Ishizuka
    International journal of environmental research and public health, 14, 1, 10 Jan. 2017, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • The Hokkaido birth cohort study on environment and children's health: Cohort profile-updated 2017
    Reiko Kishi; Atsuko Araki; Machiko Minatoya; Tomoyuki Hanaoka; Chihiro Miyashita; Sachiko Itoh; Sumitaka Kobayashi; Yu Ait Bamai; Keiko Yamazaki; Ryu Miura; Naomi Tamura; Kumiko Ito; Houman Goudarzi; S. Sasaki; T. Ikeno; E. Okada; S. Nishihara; R. M. Ketema; T. Kita; I. Kashino; T. Baba; T. S. Braimoh; S. Minakami; K. Cho; N. Shinohara; K. Moriya; T. Mitsui; T. Saito; S. Suyama; T. Nomura; S. Konno; H. Matsuura; M. Ishizuka; T. Endo; T. Baba; F. Sata; K. Sengoku; Y. Saijo; E. Yoshioka; T. Miyamoto; M. Yuasa; J. Kajiwara; T. Hori; Y. Chisaki; T. Matsumura; F. Mizutani; J. Yamamoto; Y. Onoda; T. Kawai; T. Tsuboi
    Environmental Health and Preventive Medicine, 22, 1, 2017
    Scientific journal
  • ネコの甲状腺機能に対するポリ塩化ビフェニル(PCBs)の影響評価~甲状腺ホルモンの脱ヨード化と代謝能の解析~
    水川葉月; 高居名菜; 横山望; 市居修; 滝口満喜; 野見山桂; 高口倖暉; 西川博之; 池中良徳; 池中良徳; 中山翔太; SAINNOXOI Tsend-Ayush; 田辺信介; 石塚真由美
    Journal of Toxicological Sciences, 42, Supplement, S236, S236, (一社)日本毒性学会, 2017, [Peer-reviewed]
    Japanese
  • Monitoring Lead (Pb) Pollution and Identifying Pb Pollution Sources in Japan Using Stable Pb Isotope Analysis with Kidneys of Wild Rats
    Hokuto Nakata; Shouta M. M. Nakayama; Balazs Oroszlany; Yoshinori Ikenaka; Hazuki Mizukawa; Kazuyuki Tanaka; Tsunehito Harunari; Tsutomu Tanikawa; Wageh Sobhy Darwish; Yared B. Yohannes; Aksorn Saengtienchai; Mayumi Ishizuka
    INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, 14, 1, Jan. 2017, [Peer-reviewed]
    English, Scientific journal
  • DDTs and other organochlorine pesticides in tissues of four bird species from the Rift Valley region, Ethiopia
    Yared Beyene Yohannes; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    SCIENCE OF THE TOTAL ENVIRONMENT, 574, 1389, 1395, Jan. 2017, [Peer-reviewed]
    English, Scientific journal
  • The African hedgehog (Atelerix albiventris): Low phase I and phase II metabolism activities
    Aksorn Saengtienchai; Yoshinori Ikenaka; Nesta Bortey-Sam; Usuma Jermnark; Hazuki Mizukawa; Yusuke K. Kawai; Shouta M. M. Nakayama; Mayumi Ishizuka
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY, 190, 38, 47, Dec. 2016, [Peer-reviewed]
    English, Scientific journal
  • Excretion of polycyclic aromatic hydrocarbon metabolites (OH-PAHs) in cattle urine in Ghana
    Nesta Bortey-Sam; Yoshinori Ikenaka; Osei Akoto; Shouta M. M. Nakayama; Jemima Marfo; Aksorn Saengtienchai; Hazuki Mizukawa; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 218, 331, 337, Nov. 2016, [Peer-reviewed]
    English, Scientific journal
  • Novel revelation of warfarin resistant mechanism in roof rats (Rattus rattus) using pharmacokinetic/pharmacodynamic analysis
    Kazuki Takeda; Yoshinori Ikenaka; Tsutomu Tanikawa; Kazuyuki D. Tanaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY, 134, 1, 7, Nov. 2016, [Peer-reviewed]
    English, Scientific journal
  • Heavy metals and metalloid accumulation in livers and kidneys of wild rats around gold-mining communities in Tarkwa, Ghana
    Bortey Sam Nesta; M M Nakayama Shouta; Ikenaka Yoshinori; Akoto Osei; Baidoo Elvis; Mizukawa Hazuki; Ishizuka Mayumi
    Journal of Environmental Chemistry and Ecotoxicology, 8, 7, 58, 68, Academic Journals, 31 Jul. 2016
    Scientific journal
  • Strain differences in cytochrome P450 mRNA and protein expression, and enzymatic activity among Sprague Dawley, Wistar, Brown Norway and Dark Agouti rats
    Yoshihiro Nishiyama; Shouta M. M. Nakayama; Kensuke P. Watanabe; Yusuke K. Kawai; Marumi Ohno; Yoshinori Ikenaka; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 78, 4, 675, 680, Apr. 2016, [Peer-reviewed]
    English, Scientific journal
  • Bioaccumulation and human health risk assessment of DDT and other organochlorine pesticides in an apex aquatic predator from a premier conservation area
    Ruan Gerber; Nico J. Smit; Johan H. J. Van Vuren; Shouta M. M. Nakayama; Yared B. Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Victor Wepener
    SCIENCE OF THE TOTAL ENVIRONMENT, 550, 522, 533, Apr. 2016, [Peer-reviewed]
    English, Scientific journal
  • Characterization of equine cytochrome P450: role of CYP3A in the metabolism of diazepam.
    Nakayama SM; Ikenaka Y; Hayami A; Mizukawa H; Darwish WS; Watanabe KP; Kawai YK; Ishizuka M
    Journal of veterinary pharmacology and therapeutics, 39, 5, 478, 487, Mar. 2016, [Peer-reviewed]
    Scientific journal
  • Distribution and health risk assessment of organochlorine pesticides (OCPs) residue in edible cattle tissues from northeastern part of Egypt: High accumulation level of OCPs in tongue
    Abdallah Fikry A. Mahmoud; Yoshinori Ikenaka; Yared B. Yohannes; Wageh S. Darwish; Elsaid A. Eldaly; Alaa Eldin M. A. Morshdy; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    CHEMOSPHERE, 144, 1365, 1371, Feb. 2016, [Peer-reviewed]
    English, Scientific journal
  • beta-carotene and retinol contents in the meat of herbivorous ungulates with a special reference to their public health importance
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Alaa Eldin Morshdy; Kamal Ibrahim Eldesoky; Shouta Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 78, 2, 351, 354, Feb. 2016, [Peer-reviewed]
    English, Scientific journal
  • ポリ塩化ビフェニル(PCBs)のin vivo暴露によるネコの異物代謝解明と甲状腺ホルモンへの影響評価
    水川葉月; 前原美咲; 横山望; 市居修; 滝口満喜; 野見山桂; 西川博之; 池中良徳; 中山翔太; 高口倖暉; 田辺信介; 石塚真由美
    Journal of Toxicological Sciences, 41, Supplement, S215, S215, (一社)日本毒性学会, 2016, [Peer-reviewed]
    Japanese
  • Reliability of stable Pb isotopes to identify Pb sources and verifying biological fractionation of Pb isotopes in goats and chickens
    Hokuto Nakata; Shouta M. M. Nakayama; John Yabe; Allan Liazambi; Hazuki Mizukawa; Wageh Sobhy Darwish; Yoshinori Ikenaka; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 208, Pt B, 395, 403, Jan. 2016, [Peer-reviewed]
    English, Scientific journal
  • Constitutive Effects of Lead on Aryl Hydrocarbon Receptor Gene Battery and Protection by beta-carotene and Ascorbic Acid in Human HepG2 Cells
    Wageh S. Darwish; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    JOURNAL OF FOOD SCIENCE, 81, 1, T275, T281, Jan. 2016, [Peer-reviewed]
    English, Scientific journal
  • Organohalogen Compounds in Pet Dog and Cat: Do Pets Biotransform Natural Brominated Products in Food to Harmful Hydroxlated Substances?
    Hazuki Mizukawa; Kei Nomiyama; Susumu Nakatsu; Hisato Iwata; Jean Yoo; Akira Kubota; Miyuki Yamamoto; Mayumi Ishizuka; Yoshinori Ikenaka; Shouta M. M. Nakayama; Tatsuya Kunisue; Shinsuke Tanabe
    ENVIRONMENTAL SCIENCE & TECHNOLOGY, 50, 1, 444, 452, Jan. 2016, [Peer-reviewed]
    English, Scientific journal
  • Application of a Sediment Quality Index for the assessment and monitoring of metals and organochlorines in a premier conservation area
    Ruan Gerber; Nico J. Smit; Johan H. J. van Vuren; Shouta M. M. Nakayama; Yared B. Yohannes; Yoshinori Ikenaka; Mayumi Ishizuka; Victor Wepener
    ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 22, 24, 19971, 19989, Dec. 2015, [Peer-reviewed]
    English, Scientific journal
  • Accumulation properties of inorganic mercury and organic mercury in the red-crowned crane Grus japonensis in east Hokkaido, Japan
    Hiroki Teraoka; Erika Okamoto; Moe Kudo; Shouta M. M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka; Tetsuya Endo; Takio Kitazawa; Takeo Hiraga
    ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, 122, 557, 564, Dec. 2015, [Peer-reviewed]
    English, Scientific journal
  • Relationship between Urinary N-Desmethyl-Acetamiprid and Typical Symptoms including Neurological Findings: A Prevalence Case-Control Study
    Jemima Tiwaa Mario; Kazutoshi Fujioka; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Yoshiko Aoyama; Mayumi Ishizuka; Kumiko Taira
    PLOS ONE, 10, 11, e0142172, Nov. 2015, [Peer-reviewed]
    English, Scientific journal
  • Mutagenicity of modelled-heat-treated meat extracts: Mutagenicity assay, analysis and mechanism of mutagenesis
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 63, 4, 173, 182, Nov. 2015, [Peer-reviewed]
    English, Scientific journal
  • Cytochrome P450-mediated warfarin metabolic ability is not a critical determinant of warfarin sensitivity in avian species: In vitro assays in several birds and in vivo assays in chicken
    Kensuke P. Watanabe; Minami Kawata; Yoshinori Ikenaka; Shouta M. M. Nakayama; Chihiro Ishii; Wageh Sobhi Darwish; Aksorn Saengtienchai; Hazuki Mizukawa; Mayumi Ishizuka
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 34, 10, 2328, 2334, Oct. 2015, [Peer-reviewed]
    English, Scientific journal
  • Metal extent in blood of livestock from Dandora dumping site, Kenya: Source identification of Pb exposure by stable isotope analysis
    Hokuto Nakata; Shouta M. M. Nakayama; Yoshinori Ikenaka; Hazuki Mizukawa; Chihiro Ishii; Yared B. Yohannes; Satoru Konnai; Wageh Sobhy Darwish; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 205, 8, 15, Oct. 2015, [Peer-reviewed]
    English, Scientific journal
  • Characterization and tissue distribution of conjugated metabolites of pyrene in the rat
    Aksorn Saengtienchai; Yoshinori Ikenaka; Wageh Sobhy Darwish; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 77, 10, 1261, 1267, Oct. 2015, [Peer-reviewed]
    English, Scientific journal
  • Uridine Diphosphate-Glucuronosyltransferase (UGT) Xenobiotic Metabolizing Activity and Genetic Evolution in Pinniped Species
    Mayu Kakehi; Yoshinori Ikenaka; Shouta M. M. Nakayama; Yusuke K. Kawai; Kensuke P. Watanabe; Hazuki Mizukawa; Kei Nomiyama; Shinsuke Tanabe; Mayumi Ishizuka
    TOXICOLOGICAL SCIENCES, 147, 2, 360, 369, Oct. 2015, [Peer-reviewed]
    English, Scientific journal
  • Ecological Risk of Heavy Metals and a Metalloid in Agricultural Soils in Tarkwa, Ghana.
    Nesta Bortey-Sam; Shouta M M Nakayama; Osei Akoto; Yoshinori Ikenaka; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    International journal of environmental research and public health, 12, 9, 11448, 65, 11 Sep. 2015, [Peer-reviewed], [International Magazine]
    English, Heavy metals and a metalloid in agricultural soils in 19 communities in Tarkwa were analyzed to assess the potential ecological risk. A total of 147 soil samples were collected in June, 2012 and analyzed for As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. Mean concentrations (mg/kg dw) of heavy metals in the communities decreased in order of Zn (39) ˃ Cr (21) ˃ Pb (7.2) ˃ Cu (6.2) ˃ As (4.4) ˃ Ni (3.7) ˃ Co (1.8) ˃ Hg (0.32) ˃ Cd (0.050). Correlations among heavy metals and soil properties indicated that soil organic matter could have substantial influence on the total contents of these metals in soil. From the results, integrated pollution (C(deg)) in some communities such as, Wangarakrom (11), Badukrom (13) and T-Tamso (17) indicated high pollution with toxic metals, especially from As and Hg. Potential ecological risk (RI) indices indicated low (Mile 7) to high risks (Wangarakrom; Badukrom) of metals. Based on pollution coefficient (C(i)(f)), C(deg), monomial ecological risk (E(i)(r)) and RI, the investigated soils fall within low to high contamination and risk of heavy metals to the ecological system especially plants, soil invertebrates and/or mammalian wildlife. This represented moderate potential ecological risk in the study area, and mining activities have played a significant role.
  • Ecological Risk of Heavy Metals and a Metalloid in Agricultural Soils in Tarkwa, Ghana
    Nesta Bortey-Sam; Shouta M. M. Nakayama; Osei Akoto; Yoshinori Ikenaka; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, 12, 9, 11448, 11465, Sep. 2015, [Peer-reviewed]
    English, Scientific journal
  • Accumulation of Heavy Metals and Metalloid in Foodstuffs from Agricultural Soils around Tarkwa Area in Ghana, and Associated Human Health Risks
    Nesta Bortey-Sam; Shouta M. M. Nakayama; Osei Akoto; Yoshinori Ikenaka; Julius N. Fobil; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, 12, 8, 8811, 8827, Aug. 2015, [Peer-reviewed]
    English, Scientific journal
  • Accumulation of Heavy Metals and Metalloid in Foodstuffs from Agricultural Soils around Tarkwa Area in Ghana, and Associated Human Health Risks.
    Nesta Bortey-Sam; Shouta M M Nakayama; Osei Akoto; Yoshinori Ikenaka; Julius N Fobil; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    International journal of environmental research and public health, 12, 8, 8811, 27, 28 Jul. 2015, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Mercury concentrations in primary feathers reflect pollutant exposure in discrete non-breeding grounds used by Short-tailed Shearwaters
    Yutaka Watanuki; Takashi Yamamoto; Ai Yamashita; Chihiro Ishii; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka; Yuya Suzuki; Yasuaki Niizuma; C. E. Meathrel; R. A. Phillips
    JOURNAL OF ORNITHOLOGY, 156, 3, 847, 850, Jul. 2015, [Peer-reviewed]
    English, Scientific journal
  • Levels, potential sources and human health risk of polycyclic aromatic hydrocarbons (PAHs) in particulate matter (PM10) in Kumasi, Ghana
    Nesta Bortey-Sam; Yoshinori Ikenaka; Osei Akoto; Shouta M. M. Nakayama; Yared Beyene Yohannes; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 22, 13, 9658, 9667, Jul. 2015, [Peer-reviewed]
    English, Scientific journal
  • Health risk assessment of heavy metals and metalloid in drinking water from communities near gold mines in Tarkwa, Ghana
    Nesta Bortey-Sam; Shouta M. M. Nakayama; Yoshinori Ikenaka; Osei Akoto; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    ENVIRONMENTAL MONITORING AND ASSESSMENT, 187, 7, 397, 12, Jul. 2015, [Peer-reviewed]
    English, Scientific journal
  • Metabolic Activation of Heterocyclic Amines and Expression of Xenobiotic-Metabolizing Enzymes in the Gastrointestinal Tract of Rats
    Wageh S. Darwish; Shouta M. M. Nakayama; Yuumi Itotani; Marumi Ohno; Yoshinori Ikenaka; Mayumi Ishizuka
    JOURNAL OF FOOD SCIENCE, 80, 7, T1627, T1632, Jul. 2015, [Peer-reviewed]
    English, Scientific journal
  • Are red gourami (Colisa labiosa) low xenobiotic metabolizers? Elucidation of in vivo pharmacokinetics of pyrene as a model substrate
    Yoshinori Ikenaka; Shouta M. M. Nakayama; Mami Oguri; Aksorn Saengtienchai; Hazuki Mizukawa; Jun Kobayashi; Wageh Sobhy Darwish; Mayumi Ishizuka
    ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY, 39, 3, 1148, 1153, May 2015, [Peer-reviewed]
    English, Scientific journal
  • Partial cloning of CYP2C23a genes and hepatic protein expression in eight representative avian species
    K. P. Watanabe; Y. K. Kawai; S. M.M. Nakayama; Y. Ikenaka; H. Mizukawa; N. Takaesu; M. Ito; S. I. Ikushiro; T. Sakaki; M. Ishizuka
    Journal of Veterinary Pharmacology and Therapeutics, 38, 2, 190, 195, Blackwell Publishing Ltd, 01 Apr. 2015, [Peer-reviewed]
    English, Scientific journal
  • Organohalogens and their hydroxylated metabolites in the blood of pigs from an open waste dumping site in south India: Association with hepatic cytochrome P450
    Hazuki Mizukawa; Kei Nomiyama; Tatsuya Kunisue; Michio X. Watanabe; Annamalai Subramanian; Hisato Iwata; Mayumi Ishizuka; Shinsuke Tanabe
    ENVIRONMENTAL RESEARCH, 138, 255, 263, Apr. 2015, [Peer-reviewed]
    English, Scientific journal
  • Lead poisoning in children from townships in the vicinity of a lead-zinc mine in Kabwe, Zambia
    John Yabe; Shouta M. M. Nakayama; Yoshinori Ikenaka; Yared B. Yohannes; Nesta Bortey-Sam; Balazs Oroszlany; Kaampwe Muzandu; Kennedy Choongo; Abel Nketani Kabalo; John Ntapisha; Aaron Mweene; Takashi Umemura; Mayumi Ishizuka
    CHEMOSPHERE, 119, 941, 947, Jan. 2015, [Peer-reviewed]
    English, Scientific journal
  • Human health risks from metals and metalloid via consumption of food animals near gold mines in Tarkwa, Ghana: Estimation of the daily intakes and target hazard quotients (THQs)
    Nesta Bortey-Sam; Shouta M. M. Nakayama; Yoshinori Ikenaka; Osei Akoto; Elvis Baidoo; Yared Beyene Yohannes; Hazuki Mizukawa; Mayumi Ishizuka
    ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, 111, 160, 167, Jan. 2015, [Peer-reviewed]
    English, Scientific journal
  • Occurrence, distribution, sources and toxic potential of polycyclic aromatic hydrocarbons (PAHs) in surface soils from the Kumasi Metropolis, Ghana
    Nesta Bortey-Sam; Yoshinori Ikenaka; Shouta M. M. Nakayama; Osei Akoto; Yared Beyene Yohannes; Elvis Baidoo; Hazuki Mizukawa; Mayumi Ishizuka
    SCIENCE OF THE TOTAL ENVIRONMENT, 496, 471, 478, Oct. 2014, [Peer-reviewed]
    English, Scientific journal
  • TCDD-induced chick cardiotoxicity is abolished by a selective cyclooxygenase-2 (COX-2) inhibitor NS398
    Nozomi Fujisawa; Shouta M. M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka
    ARCHIVES OF TOXICOLOGY, 88, 9, 1739, 1748, Sep. 2014, [Peer-reviewed]
    English, Scientific journal
  • IDENTIFICATION OF INTERSPECIFIC DIFFERENCES IN PHASE II REACTIONS: DETERMINATION OF METABOLITES IN THE URINE OF 16 MAMMALIAN SPECIES EXPOSED TO ENVIRONMENTAL PYRENE
    Aksorn Saengtienchai; Yoshinori Ikenaka; Shouta M. M. Nakayama; Hazuki Mizukawa; Mayu Kakehi; Nesta Bortey-Sam; Wageh Sobhy Darwish; Toshio Tsubota; Masanori Terasaki; Amnart Poapolathep; Mayumi Ishizuka
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 33, 9, 2062, 2069, Sep. 2014, [Peer-reviewed]
    English, Scientific journal
  • Organochlorine pesticides in bird species and their prey (fish) from the Ethiopian Rift Valley region, Ethiopia
    Yared Beyene Yohannes; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 192, 121, 128, Sep. 2014, [Peer-reviewed]
    English, Scientific journal
  • Clofibric acid induces hepatic CYP 2B1/2 via constitutive androstane receptor not via peroxisome proliferator activated receptor alpha in rat
    Zein Shaban Ibrahim; Mohamed Mohamed Ahmed; Samir Ahmed El-Shazly; Mayumi Ishizuka; Shoichi Fujita
    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY, 78, 9, 1550, 1559, Sep. 2014, [Peer-reviewed]
    English, Scientific journal
  • Repression of Hepatic Cytochrome P450 2D Expression in Mice during Babesia microti Infection
    Yoshinori Shimamoto; Kensuke Watanabe; Hiromi Ikadai; Masashi Okamura; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 76, 8, 1147, 1151, Aug. 2014, [Peer-reviewed]
    English, Scientific journal
  • Concentrations and human health risk assessment of organochlorine pesticides in edible fish species from a Rift Valley lake-Lake Ziway, Ethiopia
    Yared B. Yohannes; Yoshinori Ikenaka; Aksorn Saengtienchai; Kensuke P. Watanabe; Shouta M. M. Nakayam; Mayumi Ishizuka
    ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, 106, 95, 101, Aug. 2014, [Peer-reviewed]
    English, Scientific journal
  • Apoptosis and gene expression in the developing mouse brain of fusarenon-X-treated pregnant mice
    Samak Sutjarit; Shota M. M. Nakayama; Yoshinori Ikenaka; Mayumi Ishizuka; Wijit Banlunara; Worawut Rerkamnuaychoke; Susumu Kumagai; Amnart Poapolathep
    TOXICOLOGY LETTERS, 229, 1, 292, 302, Aug. 2014, [Peer-reviewed]
    English, Scientific journal
  • Contamination status and possibility of toxic effects of co-planar polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and dichlorodiphenyltrichloroethane in large Japanese field mouse (Apodemus speciosus) collected from Hokkaido and Aomori
    Hazuki Mizukawa; Yoshinori Ikenaka; Shouta M. M. Nakayama; Kentaro Q. Sakamoto; Shoichi Fujita; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 62, 3, 107, 115, Aug. 2014, [Peer-reviewed]
    English, Scientific journal
  • Contamination status and accumulation characteristics of metals and a metalloid in birds on Teuri Island, Hokkaido, Japan
    Chihiro Ishii; Yoshinori Ikenaka; Shouta M. M. Nakayama; Yuya Suzuki; Yutaka Watanuki; Yuji Watanabe; Yared Beyene Yohannes; Hazuki Mizukawa; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 62, 3, 143, 149, Aug. 2014, [Peer-reviewed]
    English, Scientific journal
  • An Overview on Mycotoxin Contamination of Foods in Africa
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 76, 6, 789, 797, Jun. 2014, [Peer-reviewed]
    English
  • The Effect of Copper on the mRNA Expression Profile of Xenobiotic-Metabolizing Enzymes in Cultured Rat H4-II-E Cells
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta Nakayama; Mayumi Ishizuka
    BIOLOGICAL TRACE ELEMENT RESEARCH, 158, 2, 243, 248, May 2014, [Peer-reviewed]
    English, Scientific journal
  • Toxicokinetics and tissue depletion of Fusarenon-X and its metabolite nivalenol in piglets
    Thanit Saengtienchai; Saranya Poapolathep; Supaporn Isariyodom; Yoshinori Ikenaka; Mayumi Ishizuka; Amnart Poapolathep
    FOOD AND CHEMICAL TOXICOLOGY, 66, 307, 312, Apr. 2014, [Peer-reviewed]
    English, Scientific journal
  • Molecular Characterization and mRNA Expression of Cytochrome P450 1A1 and Cytochrome P450 3A in Liver of Kafue Lechwe (Kobus leche kafuensis) as Potential Biomarkers of Pollution of the Kafue River Basin, Zambia
    M'kandawire, Ethel; Syakalima, Michelo; Muzandu, Kaampwe; Pandey, Girja; Simuunza, Martin; Nakayama; Shouta M. M; Kawai, Yusuke K; Ikenaka, Yoshinori; Ishizuka, Mayumi
    Engineering, 6, 2, 51, 58, Feb. 2014, [Peer-reviewed]
    English, Scientific journal
  • Heavy metal contamination of soil and sediment in Zambia
    Yoshinori Ikenaka; Shouta M.M. Nakayama; Kaampwe Muzandu; Kennedy Choongo; Hiroki Teraoka; Naoharu Mizuno; Mayumi Ishizuka
    Heavy Metal Contamination of Water and Soil: Analysis, Assessment, and Remediation Strategies, 109, 128, 01 Jan. 2014
    In book
  • SPECIES DIFFERENCE OF WARFARIN SENSITIVITY AMONG BIRDS CAN BE EXPLAINED BY THE TWO ENZYMES, CYTOCHROME P450 AND VITAMIN K EPOXIDE REDUCTASE
    Watanabe Kensuke P; Kawai Yusuke K; Kawata Minami; Nakayama Shouta M. M; Ikenaka Yoshinori; Ishizuka Mayumi
    DRUG METABOLISM REVIEWS, 45, 92, Jan. 2014, [Peer-reviewed]
  • Ubiquitin-specific protease 2-69 in macrophages potentially modulates metainflammation
    Hiroshi Kitamura; Shunsuke Kimura; Yoshinori Shimamoto; Jun Okabe; Masatoshi Ito; Tomomi Miyamoto; Yoshinori Naoe; Chisato Kikuguchi; Bob Meek; Chitoku Toda; Shiki Okamoto; Katsushi Kanehira; Koji Hase; Hiroshi Watarai; Mayumi Ishizuka; Assam El-Osta; Osamu Ohara; Ichiro Miyoshi
    FASEB Journal, 27, 12, 4940, 4953, Dec. 2013, [Peer-reviewed]
    English, Scientific journal
  • Occurrence, distribution, and ecological risk assessment of DDTs and heavy metals in surface sediments from Lake Awassa-Ethiopian Rift Valley Lake
    Yared Beyene Yohannes; Yoshinori Ikenaka; Aksorn Saengtienchai; Kensuke P. Watanabe; Shouta M. M. Nakayama; Mayumi Ishizuka
    ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH, 20, 12, 8663, 8671, Dec. 2013, [Peer-reviewed]
    English, Scientific journal
  • Dioxin Sensitivity-Related Two Critical Amino Acids of Arylhydrocarbon Receptor May Not Correlate with the Taxonomy or Phylogeny in Avian Species
    Nozomi Fujisawa; Yusuke K. Kawai; Shouta M. M. Nakayama; Yoshinori Ikenaka; Hideaki Yamamoto; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 75, 12, 1577, 1583, Dec. 2013, [Peer-reviewed]
    English, Scientific journal
  • Ubiquitin-specific protease 2-69 in macrophages potentially modulates metainflammation
    Hiroshi Kitamura; Shunsuke Kimura; Yoshinori Shimamoto; Jun Okabe; Masatoshi Ito; Tomomi Miyamoto; Yoshinori Naoe; Chisato Kikuguchi; Bob Meek; Chitoku Toda; Shiki Okamoto; Katsushi Kanehira; Koji Hase; Hiroshi Watarai; Mayumi Ishizuka; Assam El-Osta; Osamu Ohara; Ichiro Miyoshi
    FASEB JOURNAL, 27, 12, 4940, 4953, Dec. 2013, [Peer-reviewed]
    English, Scientific journal
  • Selection of suitable reference genes for mRNA quantification studies using common marmoset tissues
    Yoshinori Shimamoto; Hiroshi Kitamura; Kimie Niimi; Yasunaga Yoshikawa; Fumio Hoshi; Mayumi Ishizuka; Eiki Takahashi
    MOLECULAR BIOLOGY REPORTS, 40, 12, 6747, 6755, Dec. 2013, [Peer-reviewed]
    English, Scientific journal
  • Repeated Treatment with Furazolidone Induces Multiple Cytochrome P450-Related Activities in Chicken Liver, but Not in Rat Liver
    Nobuo Sasaki; Tomoyuki Matumoto; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka; Akio Kazusaka; Shoichi Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 75, 11, 1497, 1502, Nov. 2013, [Peer-reviewed]
    English, Scientific journal
  • De novo sequence analysis of cytochrome P450 1-3 genes expressed in ostrich liver with highest expression of CYP2G19
    Yusuke K. Kawai; Kensuke P. Watanabe; Akihiro Ishii; Aiko Ohnuma; Hirofumi Sawa; Yoshinori Ikenaka; Mayumi Ishizuka
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY D-GENOMICS & PROTEOMICS, 8, 3, 201, 208, Sep. 2013, [Peer-reviewed]
    English, Scientific journal
  • Characterization of phase-II conjugation reaction of polycyclic aromatic hydrocarbons in fish species: unique pyrene metabolism and species specificity observed in fish species.
    Yoshinori Ikenaka; Mami Oguri; Aksorn Saengtienchai; Shouta M M Nakayama; Shigeho Ijiri; Mayumi Ishizuka
    Environmental toxicology and pharmacology, 36, 2, 567, 578, Sep. 2013, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Avian Cytochrome P450 (CYP) 1-3 Family Genes: Isoforms, Evolutionary Relationships, and mRNA Expression in Chicken Liver
    Kensuke P. Watanabe; Yusuke K. Kawai; Yoshinori Ikenaka; Minami Kawata; Shin-Ichi Ikushiro; Toshiyuki Sakaki; Mayumi Ishizuka
    PLOS ONE, 8, 9, e75689, Sep. 2013, [Peer-reviewed]
    English, Scientific journal
  • Accumulation and biological effects of metals in wild rats in mining areas of Zambia
    Shouta M. M. Nakayama; Yoshinori Ikenaka; Kyohei Hamada; Kaampwe Muzandu; Kennedy Choongo; John Yabe; Takashi Umemura; Mayumi Ishizuka
    ENVIRONMENTAL MONITORING AND ASSESSMENT, 185, 6, 4907, 4918, Jun. 2013, [Peer-reviewed]
    English, Scientific journal
  • Organochlorine pesticides and heavy metals in fish from Lake Awassa, Ethiopia: Insights from stable isotope analysis
    Yared Beyene Yohannes; Yoshinori Ikenaka; Shouta M. M. Nakayama; Aksorn Saengtienchai; Kensuke Watanabe; Mayumi Ishizuka
    CHEMOSPHERE, 91, 6, 857, 863, May 2013, [Peer-reviewed]
    English, Scientific journal
  • A Novel Mutation in VKORC1 and Its Effect on Enzymatic Activity in Japanese Warfarin-Resistant Rats
    Kazuyuki D. Tanaka; Yusuke K. Kawai; Yoshinori Ikenaka; Tsunehito Harunari; Tsutomu Tanikawa; Shoichi Fujita; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 75, 2, 135, 139, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Effects of polycyclic aromatic hydrocarbons (PAHs) on an aquatic ecosystem: acute toxicity and community-level toxic impact tests of benzo[a]pyrene using lake zooplankton community
    Yoshinori Ikenaka; Masaki Sakamoto; Takamaru Nagata; Hirokazu Takahashi; Yuichi Miyabara; Takayuki Hanazato; Mayumi Ishizuka; Tomohiko Isobe; Jun-Woo Kim; Kwang-Hyeon Chang
    JOURNAL OF TOXICOLOGICAL SCIENCES, 38, 1, 131, 136, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Antibiotic residues in food: the African scenario
    Wageh Sobhy Darwish; Elsaid A. Eldaly; Mohamed Tharwat E-Abbasy; Yoshinori Ikenaka; Shouta Nakayama; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S13, S22, Feb. 2013, [Peer-reviewed]
    English
  • Biological responses of xenobiotic metabolizing enzymes to lead exposure in cultured H4IIE rat cells.
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Mayumi Ishizuka
    The Japanese journal of veterinary research, 61 Suppl, SUPPL., S48-53, 53, Feb. 2013, [Peer-reviewed], [Domestic magazines]
    English
  • Determination of organochlorine pesticides (OCPs) in the edible offal of Egyptian buffalo.
    Abdallah Fikry A Mahmoud; Wageh Sobhy Darwish; Alaa Eldin M A Morshdy; Elsaid A Eldaly; Yoshinori Ikenaka; Mayumi Ishizuka
    The Japanese journal of veterinary research, 61 Suppl, SUPPL., S58-63, 63, Feb. 2013, [Peer-reviewed], [Domestic magazines]
    English
  • Distribution of metals in organs of Clarias gariepinus, Heterobranchus bidorsalis, and Chrysichthys nigrodigitatus from the Offin River at Dunkwa-on-Offin, Ghana.
    Jemima T Marfo; Osei Akoto; Shouta M M Nakayama; Elvis Baidoo; Yoshinori Ikenaka; Mayumi Ishizuka
    The Japanese journal of veterinary research, 61 Suppl, SUPPL., S69-71, 71, Feb. 2013, [Peer-reviewed], [Domestic magazines]
    English
  • Determination of benzo[a]pyrene levels in ambient air and the source of polycyclic aromatic hydrocarbons using a diagnostic ratio method in Ghana
    Nesta Bortey-Sam; Osei Akoto; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S72, S74, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Heavy metal pollution in Japanese seabirds
    Chihiro Ishii; Yoshinori Ikenaka; Shouta M. M. Nakayama; Yuya Suzuki; Yutaka Watanuki; Yuji Watanabe; Masa-aki Fukuwaka; Yared B. Yohannes; Yusuke K. Kawai; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S75, S76, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Metabolism of pyrene, a polycyclic aromatic hydrocarbon in freshwater turtles
    Balazs Oroszlany; Yoshinori Ikenaka; Aksorn Saengtiengchan; Mami Oguri; Shouta M. M. Nakayama; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S77, S78, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Metal contaminated soil from mining area caused metal accumulation and biological responses in rats
    Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Kennedy Choongo; John Yabe; Takashi Umemura; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S79, S81, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • In vitro diazepam metabolism in horses
    Aki Hayami; Wageh Sobhy Darwish; Yoshinori Ikenaka; Shouta M. M. Nakayama; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 61, SUPPL., S82, S84, Feb. 2013, [Peer-reviewed]
    English, Scientific journal
  • Geographic information system-based source estimation of copper pollution in Lake Itezhi-tezhi and metal-accumulation profiles in Oreochromis spp. from both field and laboratory studies.
    Shouta M M Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Kennedy Choongo; John Yabe; Taro Muroya; Shigeho Ijiri; Masao Minagawa; Takashi Umemura; Mayumi Ishizuka
    Archives of environmental contamination and toxicology, 64, 1, 119, 29, Jan. 2013, [Peer-reviewed], [International Magazine]
    English, Scientific journal
  • Metal distribution in tissues of free-range chickens near a lead-zinc mine in Kabwe, Zambia
    John Yabe; Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Kennedy Choongo; Geoffrey Mainda; Matthew Kabeta; Mayumi Ishizuka; Takashi Umemura
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 32, 1, 189, 192, Jan. 2013, [Peer-reviewed]
    English, Scientific journal
  • Cytochrome P450 3A mRNA expression along goat and rat gastrointestinal tracts
    Dominic Mureithi; Wageh Sobhy Darwish; Yoshinori Ikenaka; Laetitia Kanja; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 60, 4, 205, 210, Nov. 2012, [Peer-reviewed]
    English, Scientific journal
  • Accumulation of Metals in the Liver and Kidneys of Cattle from Agricultural Areas in Lusaka, Zambia
    John Yabe; Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Mayumi Ishizuka; Takashi Umemura
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 74, 10, 1345, 1347, Oct. 2012, [Peer-reviewed]
    English, Scientific journal
  • EFFECTS OF ENVIRONMENTAL LEAD CONTAMINATION ON CATTLE IN A LEAD/ZINC MINING AREA: CHANGES IN CATTLE IMMUNE SYSTEMS ON EXPOSURE TO LEAD IN VIVO AND IN VITRO
    Yoshinori Ikenaka; Shouta M. M. Nakayama; Taro Muroya; John Yabe; Satoru Konnai; Wageh Sobhy Darwish; Kaampwe Muzandu; Kennedy Choongo; Geoffrey Mainda; Hiroki Teraoka; Takashi Umemura; Mayumi Ishizuka
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 31, 10, 2300, 2305, Oct. 2012, [Peer-reviewed]
    English, Scientific journal
  • The nucleotide sequence of metallothioneins (MT) in liver of the Kafue lechwe (Kobus leche kafuensis) and their potential as biomarkers of heavy metal pollution of the Kafue River
    Ethel M'kandawire; Michelo Syakalima; Kaampwe Muzandu; Girja Pandey; Martin Simuunza; Shouta M. M. Nakayama; Yusuke K. Kawai; Yoshinori Ikenaka; Mayumi Ishizuka
    GENE, 506, 2, 310, 316, Sep. 2012, [Peer-reviewed]
    English, Scientific journal
  • Transcriptional profiling of inflammatory cytokine genes in African, buffaloes (Syncerus caffer) infected with Theileria parva
    Tomohiro Okagawa; Satoru Konnai; Hirohisa Mekata; Naftaly Githaka; Saori Suzuki; Edward Kariuki; Francis Gakuya; Esther Kanduma; Tatsuya Shirai; Ryoyo Ikebuchi; Yoshinori Ikenaka; Mayumi Ishizuka; Shiro Murata; Kazuhiko Ohashi
    VETERINARY IMMUNOLOGY AND IMMUNOPATHOLOGY, 148, 3-4, 373, 379, Aug. 2012, [Peer-reviewed]
    English, Scientific journal
  • Cytochrome P450 (CYP) in fish
    Tomohide Uno; Mayumi Ishizuka; Takao Itakura
    ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY, 34, 1, 1, 13, Jul. 2012, [Peer-reviewed]
    English
  • Metal and metalloid levels and bio-accumulation characteristics in soil, sediment, land plants and hippopotami (Hippopotamus amphibius L) from the South Luangwa National Park, Zambia
    Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Kennedy Choongo; Ethel M'kandawire; Jun Yasuda; Mayumi Ishizuka
    ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY, 80, 333, 338, Jun. 2012, [Peer-reviewed]
    English, Scientific journal
  • Inhibitory effects of dopamine on spinal synaptic transmission via dopamine D 1-like receptors in neonatal rats
    K. Kawamoto; K. Otsuguro; M. Ishizuka; S. Ito
    British Journal of Pharmacology, 166, 2, 788, 800, May 2012
    Scientific journal
  • Expressional repression of hepatic cytochrome P450 2d in ICR mice infected with Babesia microti
    Shimamoto Yoshinori; Watanabe Kensuke; Sasaki Mizuki; Ikadai Hiromi; Ishizuka Mayumi; Hoshi Fumio; Yokoyama Naoaki; Igarashi Ikuo; Kitamura Hiroshi
    FASEB JOURNAL, 26, Apr. 2012, [Peer-reviewed]
  • Molecular cloning and characterization of Th1 and Th2 cytokines of African buffalo (Syncerus caffer)
    Suzuki S; Konnai S; Okagawa T; Githaka NW; Kariuki E; Gakuya F; Kanduma E; Shirai T; Ikebuchi R; Ikenaka Y; Ishizuka M; Murata S; Ohashi K
    Int J Immunogenet., 39, 2, 170, 82, Apr. 2012, [Peer-reviewed]
    English, Scientific journal
  • Downregulation of Hepatic Cytochrome P450 3A in Mice Infected with Babesia microti
    Yoshinori Shimamoto; Mizuki Sasaki; Hiromi Ikadai; Mayumi Ishizuka; Naoaki Yokoyama; Ikuo Igarashi; Fumio Hoshi; Hiroshi Kitamura
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 74, 2, 241, 245, Feb. 2012, [Peer-reviewed]
    English, Scientific journal
  • Cross-talks between heavy metals and xenobiotics metabolizing enzymes
    DARWISH Wageh S.; IKENAKA Yoshinori; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 39, O, 6, The Japanese Society of Toxicology, 2012
    Japanese, [Introduction] The growing exposure of the human and animals to heavy metal pollution generates modulation in xenobiotics-metabolizing enzymes (XMEs) response. In this study, the modulation of Ahr ligand-dependent toxicities by heavy metals and the molecular basis of this modulation were investigated.[Materials and Methods] Samples were collected from different edible offal of cattle slaughtered at Zagazig abattoir, Egypt. Different heavy metals were measured using atomic absorption spectrophotometer. Human and rat liver hepatoma cell lines (HEPG2 and H4IIE) were treated with Lead and Copper under different concentrations ranged between permissible and toxic doses. The effects of these treatments on various XMEs and regulatory elements were screened using the methods of qPCR and Western Blotting.[Results and Discussion] Liver, kidney and tongue showed the highest contents of the various heavy metal residues compared to other tissues. Lead, copper, cadmium, zinc and nickel exceeded the maximum permissible limits of Egyptian Standards and WHO. Interestingly, both copper and lead could induce CYP1A1 mRNA expression under low doses in the treated cell cultures. This expression level was markedly decreased under high concentrations. Effects of copper and lead on CYP1A1 expression was parallel to their effects on Ahr suggesting that those effects were in response to Ahr. All tested phase II enzymes were severely down regulated by exposure to lead in a concentration dependent manner. In conclusion, there were clear cross-talks between copper, lead and pase I, II enzymes and regulatory elements in the cultured cells.
  • The identification of the important CYP isoforms in avian xenobiotic metabolism and its species difference among bird species
    WATANABE Kensuke P; KAWATA Minami; KAWAI Yusuke; IKENAKA Yoshinori; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 39, AP, 223, The Japanese Society of Toxicology, 2012
    Japanese, [Background and aim]In wild bird species, the metabolic activity of warfarin by cytochrome P450 (CYP) was reported to be much lower compared to chicken. However, even the important CYP isoforms in avian xenobiotic metabolism have not been clarified due to the lack of information about the expression level and the function of each isoforms. Thus, the reported species difference of metabolic ability cannot be attributed to any isoform. In this study, we aimed to identify the isoform dominant in avian xenobiotic metabolism and to characterize the species difference of the isoform.[Method and result]We compared the mRNA copy number among CYP isoforms in chicken liver. CYP1A5, 2C23 and 2C45 were highly expressed in liver, while CYP3A37, which has been well studied in poultry species, showed lower expression level. Therefore, we focused on CYP2C23 of avian species. Partial sequences of CYP2C23 from 8 avian species were cloned and the anti-peptide antibody was synthesized against the conserved amino acid sequence among them. In immunoblot with the antibody and the microsomes of the avian species, we could detect CYP2C23s from all the avian species.[Discussion]With mRNA expression, CYP2C subfamily was assumed to be important isoforms in chicken xenobiotics metabolism. The expression levels of CYP2C23 proteins showed not as much difference among bird species as the metabolic activity. With all results above, the species difference of metabolic ability among bird species cannot be attributed to the protein expression levels, but the functional difference.
  • The study of polycyclic aromatic hydrocarbons (PAHs) and its metabolite as a biomarker for PAH exposures in wildlife animals
    SAENGTIENCAHI Aksorn; IKENAKA Yoshinori; LEE Kyunglee; TSUBOTA Toshio; ISHIZUKA Mayumi
    Annual Meeting of the Japanese Society of Toxicology, 39, P, 125, The Japanese Society of Toxicology, 2012
    Japanese, [Introduction] Polycyclic aromatic hydrocarbons (PAHs) distribute ubiquitously as complex mixtures in the environment. Pyrene is one of PAHs that is widely used as model of PAH contamination in environment. Pyrene is metabolized by cytochrome P450s in phase I reaction then conjugated in phase II metabolism, and excreted into urine and feces. Although their metabolites are available for use in human as indicator for PAH exposure, there are still less information in wildlife. In present study, we focus on the elucidation of pyrene metabolites in wild animals. [Materials and Methods] Urine of 10 male sika deer (Cervus nippon), 1 to 5 year olds were collected from Hokkaido, Japan. All samples were extracted by Oasis WAX cartridge and they were analyzed by High performance liquid chromatography with fluorescence detector. [Results and Discussions] We could detect pyrene-1-glucuronide largely in urine. Moreover, pyrene-1-sulfate, and 1-hydroxypyrene also detected. When we compared this results with other ruminant as cattle, pyrene-1-glucuronide was main metabolites same as sika deer. Pyrene conjugate compounds were easily detected in urine. Due to observe the amount of polluted chemical as PAHs in environment, we could suggest that not only elucidate PAH concentration, but also its metabolite as 1-hydroxypyrene, pyrene 1-glucuronide, and sulfate conjugates were important to establish the appropriate biomarker for the assessment for PAH exposures in various wildlife animal species in environment.
  • All-trans retinoic acid inhibits the recruitment of ARNT to DNA, resulting in the decrease of CYP1A1 mRNA expression in HepG2 cells
    Marumi Ohno; Yoshinori Ikenaka; Mayumi Ishizuka
    BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 417, 1, 484, 489, Jan. 2012, [Peer-reviewed]
    English, Scientific journal
  • Sudan III dye strongly induces CYP1A1 mRNA expression in HepG2 cells
    Marumi Ohno; Yoshinori Ikenaka; Mayumi Ishizuka
    JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, 26, 1, 16, 22, Jan. 2012, [Peer-reviewed]
    English, Scientific journal
  • Phase-II conjugation ability for PAH metabolism in amphibians: Characteristics and inter-species differences
    Haruki Ueda; Yoshinori Ikenaka; Shouta M. M. Nakayama; Tomoko Tanaka-Ueno; Mayumi Ishizuka
    AQUATIC TOXICOLOGY, 105, 3-4, 337, 343, Oct. 2011, [Peer-reviewed]
    English, Scientific journal
  • UPTAKE OF LEAD, CADMIUM, AND OTHER METALS IN THE LIVER AND KIDNEYS OF CATTLE NEAR A LEAD-ZINC MINE IN KABWE, ZAMBIA
    John Yabe; Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Mayumi Ishizuka; Takashi Umemura
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 30, 8, 1892, 1897, Aug. 2011, [Peer-reviewed]
    English, Scientific journal
  • Astaxanthin can alter CYP1A-dependent activities via two different mechanisms: Induction of protein expression and inhibition of NADPH P450 reductase dependent electron transfer
    Marumi Ohno; Wageh S. Darwish; Yoshinori Ikenaka; Wataru Miki; Mayumi Ishizuka
    FOOD AND CHEMICAL TOXICOLOGY, 49, 6, 1285, 1291, Jun. 2011, [Peer-reviewed]
    English, Scientific journal
  • Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia
    Shouta M. M. Nakayama; Yoshinori Ikenaka; Kyohei Hamada; Kaampwe Muzandu; Kennedy Choongo; Hiroki Teraoka; Naoharu Mizuno; Mayumi Ishizuka
    ENVIRONMENTAL POLLUTION, 159, 1, 175, 181, Jan. 2011, [Peer-reviewed]
    English, Scientific journal
  • Carotenoids as regulators for inter-species difference in cytochrome P450 1A expression and activity in ungulates and rats
    Wageh S. Darwish; Yoshinori Ikenaka; Marumi Ohno; Elsaid A. Eldaly; Mayumi Ishizuka
    FOOD AND CHEMICAL TOXICOLOGY, 48, 11, 3201, 3208, Nov. 2010, [Peer-reviewed]
    English, Scientific journal
  • Current levels of heavy metal pollution in Africa
    John Yabe; Mayuni Ishizuka; Takashi Umemura
    Journal of Veterinary Medical Science, 72, 10, 1257, 1263, Oct. 2010
  • Identification and Phylogenetic Analysis of Novel Cytochrome P450 1A Genes from Ungulate Species
    Wageh Sobhy Darwish; Yusuke Kawai; Yoshinori Ikenaka; Hideaki Yamamoto; Tarou Muroya; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 72, 9, 1237, 1241, Sep. 2010, [Peer-reviewed]
    English, Scientific journal
  • Genetic Polymorphisms of 17 beta-Hydroxysteroid Dehydrogenase 3 and the Risk of Hypospadias
    Fumihiro Sata; Norie Kurahashi; Susumu Ban; Kimihiko Moriya; Kazuyuki D. Tanaka; Mayumi Ishizuka; Hiroyuki Nakao; Yuichiro Yahata; Hirohisa Imai; Hidehiro Kakizaki; Katsuya Nonomura; Reiko Kishi
    JOURNAL OF SEXUAL MEDICINE, 7, 8, 2729, 2738, Aug. 2010, [Peer-reviewed]
    English, Scientific journal
  • Heavy Metal Accumulation in Lake Sediments, Fish (Oreochromis niloticus and Serranochromis thumbergi), and Crayfish (Cherax quadricarinatus) in Lake Itezhi-tezhi and Lake Kariba, Zambia
    Shouta M. M. Nakayama; Yoshinori Ikenaka; Kaampwe Muzandu; Kennedy Choongo; Balazs Oroszlany; Hiroki Teraoka; Naoharu Mizuno; Mayumi Ishizuka
    ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 59, 2, 291, 300, Aug. 2010, [Peer-reviewed]
    English, Scientific journal
  • Metabolic Activation of Heterocyclic Amines and Expression of CYP1A1 in the Tongue
    Mami Takiguchi; Wageh S. Darwish; Yoshinori Ikenaka; Marumi Ohno; Mayumi Ishizuka
    TOXICOLOGICAL SCIENCES, 116, 1, 79, 91, Jul. 2010, [Peer-reviewed]
    English, Scientific journal
  • Comparison of warfarin sensitivity between rat and bird species
    Kensuke P. Watanabe; Aksorn Saengtienchai; Kazuyuki D. Tanaka; Yoshinori Ikenaka; Mayumi Ishizuka
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY, 152, 1, 114, 119, Jun. 2010, [Peer-reviewed]
    English, Scientific journal
  • The CYP1D subfamily of genes in mammals and other vertebrates
    Yusuke K. Kawai; Yoshinori Ikenaka; Shoichi Fujita; Mayumi Ishizuka
    MAMMALIAN GENOME, 21, 5-6, 320, 329, Jun. 2010, [Peer-reviewed]
    English, Scientific journal
  • Sodium 2-propenyl thiosulfate derived from garlic induces phase II detoxification enzymes in rat hepatoma H4IIE cells
    Hye-Sook Chang; Miyan Ko; Mayumi Ishizuka; Shoichi Fujita; Akira Yabuki; Mohammad Alamgir Hossain; Osamu Yamato
    NUTRITION RESEARCH, 30, 6, 435, 440, Jun. 2010, [Peer-reviewed]
    English, Scientific journal
  • Cytochrome P450 1A-Dependent Activities in Deer, Cattle and Horses
    Wageh Sobhy Darwish; Yoshinori Ikenaka; Elsaid Abozeid Eldaly; Marumi Ohno; Kentaro Q. Sakamoto; Shoichi Fujita; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 72, 5, 561, 566, May 2010, [Peer-reviewed]
    English, Scientific journal
  • Metabolic Alkalosis due to Feeding Chicks in Breeding Adelie Penguins Pygoscelis adeliae under Natural Conditions
    Kentaro Q. Sakamoto; Katsufumi Sato; Akiko Kato; Daisuke Fukui; Gen Bando; Yasuhiko Naito; Yoshiaki Habara; Mayumi Ishizuka; Shoichi Fujita
    PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY, 83, 2, 232, 238, Mar. 2010, [Peer-reviewed]
    English, Scientific journal
  • Expression and Sequence of CYP1A1 in the Camel
    Wageh Sobhy Darwish; Alaa Eldin Morshdy; Yoshinori Ikenaka; Zein Shaban Ibrahim; Shoichi Fujita; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 72, 2, 221, 224, Feb. 2010, [Peer-reviewed]
    English, Scientific journal
  • Diazepam Metabolism in the Kidneys of Male and Female Rats of Various Strains
    Hyung-Sub Kim; Noriaki Sakai; Konomu Saito; Shoichi Fujita; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 72, 1, 7, 11, Jan. 2010, [Peer-reviewed]
    English, Scientific journal
  • Impact of rat P450 genetic polymorphism on diazepam metabolism
    Noriaki Sakai; Mayumi Ishizuka
    EXPERT OPINION ON DRUG METABOLISM & TOXICOLOGY, 5, 11, 1421, 1433, Nov. 2009, [Peer-reviewed]
    English
  • Molecular Cloning of Novel Cytochrome P450 1A Genes from Nine Japanese Amphibian Species
    Shouta M. M. Nakayama; Tomoko Tanaka-Ueno; Kentaro Q. Sakamoto; Shoichi Fujita; Mayumi Ishizuka
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 71, 10, 1407, 1411, Oct. 2009, [Peer-reviewed]
    English, Scientific journal
  • Crude Cacao Theobroma cacao Extract Reduces Mutagenicity Induced by Benzo[a]pyrene Through Inhibition of CYP1A Activity In Vitro
    Marumi Ohno; Kentaro Q. Sakamoto; Mayumi Ishizuka; Shoichi Fujita
    PHYTOTHERAPY RESEARCH, 23, 8, 1134, 1139, Aug. 2009, [Peer-reviewed]
    English, Scientific journal
  • The Importance of Heterogeneous Nuclear Ribonucleoprotein K on Cytochrome P450 2D2 Gene Regulation: Its Binding Is Reduced in Dark Agouti Rats
    Noriaki Sakai; Kentaro Q. Sakamoto; Shoichi Fujita; Mayumi Ishizuka
    DRUG METABOLISM AND DISPOSITION, 37, 8, 1703, 1710, Aug. 2009, [Peer-reviewed]
    English, Scientific journal
  • Protective effect of Pleurotus cornucopiae mushroom extract on carbon tetrachloride-induced hepatotoxicity
    Khlood M. El Bohi; Yoshiharu Hashimoto; Kaampwe Muzandu; Yoshinori Ikenaka; Zein Shaban Ibrahim; Akio Kazusaka; Shoichi Fujita; Mayumi Ishizuka
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 57, 2, 109, 118, Aug. 2009, [Peer-reviewed]
    English, Scientific journal
  • Absolute requirement for iron in the development of chemically induced uroporphyria in mice treated with 3-methylcholanthrene and 5-aminolevulinate
    Kenzi Nakano; Mayumi Ishizuka; Kentaro Q. Sakamoto; Shoichi Fujita
    BIOMETALS, 22, 2, 345, 351, Apr. 2009, [Peer-reviewed]
    English, Scientific journal
  • Can Ethograms Be Automatically Generated Using Body Acceleration Data from Free-Ranging Birds?
    Kentaro Q. Sakamoto; Katsufumi Sato; Mayumi Ishizuka; Yutaka Watanuki; Akinori Takahashi; Francis Daunt; Sarah Wanless
    PLOS ONE, 4, 4, e5379, Apr. 2009, [Peer-reviewed]
    English, Scientific journal
  • Morphological Features and Blood Parameters of Weddell Seal (Leptonychotes weddellii) Mothers and Pups during the Breeding Season
    Kentaro Q. Sakamoto; Katsufumi Sato; Yasuhiko Naito; Yoshiaki Habara; Mayumi Ishizuka; Shoichi Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 71, 3, 341, 344, Mar. 2009, [Peer-reviewed]
    English, Scientific journal
  • Genetic Basis of Inter- and Intrastrain Differences in Diazepam p-Hydroxylation in Rats
    Noriaki Sakai; Konomu Saito; Kentaro Q. Sakamoto; Mayumi Ishizuka; Shoichi Fujita
    DRUG METABOLISM AND DISPOSITION, 37, 2, 268, 271, Feb. 2009, [Peer-reviewed]
    English, Scientific journal
  • Protection by Nigella sativa against carbon tetrachloride-induced downregulation of hepatic cytochrome P450 isozymes in rats
    Zein S. Ibrahim; Mayumi Ishizuka; Mohamed Soliman; Khlood ElBohi; Wageh Sobhy; Kaampwe Muzandu; Azza M. Elkattawy; Kentaro Q. Sakamoto; Shoichi Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 56, 3, 119, 128, Nov. 2008, [Peer-reviewed]
    English, Scientific journal
  • Genetic and antigenic analyses of a Puumala virus isolate as a potential vaccine strain.
    Abu Daude NH; Kariwa H; Tkachenko E; Dzagurnova T; Medvedkina O; Tkachenko P; Ishizuka M; Seto T; Miyashita D; Sanada T; Nakauchi M; Yoshii K; Maeda A; Yoshimatsu K; Arikawa J; Takashima I
    The Japanese journal of veterinary research, 56, 3, 151, 165, 3, Nov. 2008, [Peer-reviewed]
    English, Puumala virus (PUUV), a causative agent of hemorrhagic fever with renal syndrome (HFRS), is prevalent in Europe and European Russia. No vaccine has been developed for PUUVassociated HFRS, primarily because of the low viral yield in cultured cells. A PUUV strain known as DTK/Ufa-97 was isolated in Russia and adapted for growth in Vero E6 cells maintained in serum-free medium. The DTK/Ufa-97 strain produced a higher viral titer in serumfreemedium, suggesting that it may prove useful in the development of an HFRS vaccine.When PUUV-infected Vero E6 cells were grown in serum-free medium, the DTK/Ufa-97 strain yielded more copies of intracellular viral RNA and a higher viral titer in the culture fluid than did the Sotkamo strain. Phylogenetic analysis revealed that PUUVs can be classified into multiple lineages according to geographical origin, and that the DTK/Ufa-97 strain is a member of the Bashkiria-Saratov lineage. The deduced amino acid sequences of the small, medium, and large segments of the DTK/Ufa-97 strain were 99.2% to 100%, 99.3% to 99.8%, and 99.8% identical, respectively, to those of the Bashkirian PUUV strains and 96.9%, 92.6%, and 97.4% identical, respectively, to those of the Sotkamo strain, indicating that the PUUVs are genetically diverse. However, DTK/Ufa-97 and other strains of PUUV exhibited similar patterns of binding to a panel of monoclonal antibodies against Hantaan virus. In addition, diluted antisera (i.e., ranging from 1:160 to 1:640) specific to three strains of PUUV neutralized both homologous and heterologous viruses. These results suggest that the DTK/Ufa-97 strain is capable of extensive growth and is antigenically similar to genetically distant strains of PUUV.
  • Analysis of acrylamide in a complex matrix of polyacrylamide solutions treated by heat and ultraviolet light
    Mayumi Ishizuka; Kazutoshi Fujioka; Takayuki Shibamoto
    JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 56, 15, 6093, 6096, Aug. 2008, [Peer-reviewed]
    English, Scientific journal
  • Pesticide resistance in wild mammals - Mechanisms of anticoagulant resistance in wild rodents
    Mayumi Ishizuka; Tsutomu Tanikawa; Kazuyuki D. Tanaka; Min Heewon; Fumie Okajima; Kentaro Q. Sakamoto; Shoichi Fujita
    JOURNAL OF TOXICOLOGICAL SCIENCES, 33, 3, 283, 291, Aug. 2008, [Peer-reviewed]
    English
  • Downregulation of male-specific cytochrome P450 by profenofos
    Gihan G. Moustafa; Zein S. Ibrahim; Mohamed M. Ahmed; Mervat H. Ghoneim; Kentaro Q. Sakamoto; Mayumi Ishizuka; Shoichi Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 56, 2, 109, 118, Aug. 2008, [Peer-reviewed]
    English, Scientific journal
  • Adverse birth outcomes associated with maternal smoking and polymorphisms in the N-nitrosamine-metabolizing enzyme genes NQO1 and CYP2E1
    Seiko Sasaki; Fumihiro Sata; Shizue Katoh; Yasuaki Saijo; Sonomi Nakajima; Noriaki Washino; Kanae Konishi; Susumu Ban; Mayumi Ishizuka; Reiko Kishi
    AMERICAN JOURNAL OF EPIDEMIOLOGY, 167, 6, 719, 726, Mar. 2008, [Peer-reviewed]
    English, Scientific journal
  • Antibiotic furazolidone induces CYP1A but not CYP2E1 subfamily in rat liver
    Nobuo Sasaki; Noriaki Sakai; Yoshinori Ikenaka; Tomomi Kamiya; Min Heewon; Kentaro Q. Sakamotoo; Mayumi Ishizuka; Shoichi Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 70, 3, 223, 226, Mar. 2008, [Peer-reviewed]
    English, Scientific journal
  • The induction of cytochrome P450 1A1 by sudan dyes
    Nahla A. G. Ahmed Refat; Zein Shaban Ibrahim; Gihan Gamal Moustafa; Kentaro Q. Sakamoto; Mayumi Ishizuka; Shoichi Fujita
    JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, 22, 2, 77, 84, 2008, [Peer-reviewed]
    English, Scientific journal
  • Testicular toxicity of profenofos in matured male rats
    Gihan Gamal Moustafa; Zein Shaban Ibrahim; Yoshiharu Hashimoto; M. Alkelch Alkelch; Kentaro Q. Sakamoto; Mayumi Ishizuka; Shoichi Fujita
    ARCHIVES OF TOXICOLOGY, 81, 12, 875, 881, Dec. 2007, [Peer-reviewed]
    English, Scientific journal
  • Using microarray analysis to evaluate genetic polymorphisms involved in the metabolism of environmental chemicals.
    Ban S; Kondo T; Ishizuka M; Sasaki S; Konishi K; Washino N; Fujita S; Kishi R
    Fukuoka igaku zasshi = Hukuoka acta medica, 98, 5, 208, 214, 5, May 2007, [Peer-reviewed]
    Scientific journal
  • Elevated warfarin metabolism in warfarin-resistant roof rats (Rattus rattus) in Tokyo
    Mayumi Ishizuka; Fumie Okajima; Tsutomu Tanikawa; Heewon Min; Kazuyuki D. Tanaka; Kentaro Q. Sakamoto; Shoichi Fujita
    DRUG METABOLISM AND DISPOSITION, 35, 1, 62, 66, Jan. 2007, [Peer-reviewed]
    English, Scientific journal
  • Plasma pharmacokinetics and CYP3A12-dependent metabolism of c-kit inhibitor imatinib in dogs
    M. Ishizuka; S. Nagai; K. Q. Sakamoto; S. Fujita
    XENOBIOTICA, 37, 5, 503, 513, 2007, [Peer-reviewed]
    English, Scientific journal
  • Effect of lycopene and beta-carotene on peroxynitrite-mediated cellular modifications
    Kaampwe Muzandu; Mayumi Ishizuka; Kentaro Q. Sakamoto; Zein Shaban; Khlood El Bohi; Akio Kazusaka; Shoichi Fujita
    TOXICOLOGY AND APPLIED PHARMACOLOGY, 215, 3, 330, 340, Sep. 2006, [Peer-reviewed]
    English, Scientific journal
  • CYP2D-related metabolism in animals of the Canoidea superfamily - Species differences
    M. Ishizuka; J. J. Lee; M. Masuda; F. Akahori; A. Kazusaka; S. Fujita
    Veterinary Research Communications, 30, 5, 505, 512, Jul. 2006, [Peer-reviewed]
    English, Scientific journal
  • Maternal smoking during pregnancy and genetic polymorphisms in the Ah receptor, CYP1A1 and GSTM1 affect infant birth size in Japanese subjects
    S Sasaki; T Kondo; F Sata; Y Saijo; S Katoh; S Nakajima; M Ishizuka; S Fujita; R Kishi
    MOLECULAR HUMAN REPRODUCTION, 12, 2, 77, 83, Feb. 2006, [Peer-reviewed]
    English, Scientific journal
  • Induction of cytochrome P450-1A by the equine estrogen equilenin, a new endogenous aryl hydrocarbon receptor ligand
    A Jinno; Y Maruyama; M Ishizuka; A Kazusaka; A Nakamura; S Fujita
    JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 98, 1, 48, 55, Jan. 2006, [Peer-reviewed]
    English, Scientific journal
  • Importance of CYP2D3 in polymorphism of diazepam P-hydroxylation in rats
    N Sakai; K Saito; HS Kim; A Kazusaka; M Ishizuka; Y Funae; S Fujita
    DRUG METABOLISM AND DISPOSITION, 33, 11, 1657, 1660, Nov. 2005, [Peer-reviewed]
    English, Scientific journal
  • Nitric oxide enhances catechol estrogen-induced oxidative stress in LNCaP cells
    K Muzandu; Z Shaban; M Ishizuka; A Kazusaka; S Fujita
    FREE RADICAL RESEARCH, 39, 4, 389, 398, Apr. 2005, [Peer-reviewed]
    English, Scientific journal
  • Antigenotoxic effect of Pleurotus cornucopiae extracts on the mutagenesis of Salmonella typhimurium TA98 elicited by benzo [a] pyrene and oxidative DNA lesions in V79 hamster lung cells
    KM El Bohi; L Sabik; K Muzandu; Z Shaban; M Soliman; M Ishizuka; A Kazusaka; S Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 52, 4, 163, 172, Feb. 2005, [Peer-reviewed]
    English, Scientific journal
  • Lycopene and beta-carotene ameliorate catechol estrogen-mediated DNA damage
    K Muzandu; K El Bohi; Z Shaban; M Ishizuka; A Kazusaka; S Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 52, 4, 173, 184, Feb. 2005, [Peer-reviewed]
    English, Scientific journal
  • Effect of components of green tea extracts, caffeine and catechins on hepatic drug metabolizing enzyme activities and mutagenic transformation of carcinogens
    S Nikaidou; M Ishizuka; Y Maeda; Y Hara; A Kazusaka; S Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 52, 4, 185, 192, Feb. 2005, [Peer-reviewed]
    English, Scientific journal
  • Effect of catechins on mutagenesis of Salmonella typhimurium TA 102 elicited by tert-butyl hydroperoxide (t-BuOOH)
    S Nikaidou; M Ishizuka; Y Maeda; Y Hara; A Kazusaka; S Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 67, 1, 137, 138, Jan. 2005, [Peer-reviewed]
    English, Scientific journal
  • AhR and PPAR alpha: antagonistic effects on CYP2B and CYP3A, and additive inhibitory effects on CYP2C11
    Z Shaban; M Soliman; S El-Shazly; K El-Bohi; A Abdelazeez; K Kehelo; HS Kim; K Muzandu; M Ishizuka; A Kazusaka; S Fujita
    XENOBIOTICA, 35, 1, 51, 68, Jan. 2005, [Peer-reviewed]
    English, Scientific journal
  • Down regulation of hepatic PPAR alpha function by AhR ligand
    Z Shaban; S El-Shazly; S Abdelhady; Fattouh, I; K Muzandu; M Ishizuka; K Kimura; A Kazusaka; S Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 66, 11, 1377, 1386, Nov. 2004, [Peer-reviewed]
    English, Scientific journal
  • PPAR alpha-dependent modulation of hepatic CYP1A by clofibric acid in rats
    Z Shaban; S El-Shazly; M Ishizuka; K Kimura; A Kazusaka; S Fujita
    ARCHIVES OF TOXICOLOGY, 78, 9, 496, 507, Sep. 2004, [Peer-reviewed]
    English, Scientific journal
  • Strain differences in diazepam metabolism at its three metabolic sites in Sprague-Dawley, Brown Norway, Dark Agouti, and Wistar strain rats
    K Saito; N Sakai; HS Kim; M Ishizuka; A Kazusaka; S Fujita
    DRUG METABOLISM AND DISPOSITION, 32, 9, 959, 965, Sep. 2004, [Peer-reviewed]
    English, Scientific journal
  • Alterations of activities of cytosolic phospholipase A(2) and arachidonic acid-metabolizing enzymes in Di-(2-ethylhexyl)phthalate-induced testicular atrophy
    HS Kim; M Ishizuka; A Kazusaka; S Fujita
    JOURNAL OF VETERINARY MEDICAL SCIENCE, 66, 9, 1119, 1124, Sep. 2004, [Peer-reviewed]
    English, Scientific journal
  • Iodine intake as a possible cause of discontinuous decline in sperm counts: A re-evaluation of historical and geographic variation in semen quality
    KQ Sakamoto; M Ishizuka; A Kazusaka; S Fujita
    JAPANESE JOURNAL OF VETERINARY RESEARCH, 52, 2, 85, 94, Aug. 2004, [Peer-reviewed]
    English, Scientific journal
  • Polymorphism in diazepam metabolism in Wistar rats
    K Saito; HS Kim; N Sakai; M Ishizuka; A Kazusaka; S Fujita
    JOURNAL OF PHARMACEUTICAL SCIENCES, 93, 5, 1271, 1278, May 2004, [Peer-reviewed]
    English, Scientific journal
  • Cytochrome P450 induction and gonadal status alteration in common carp (Cyprinus carpio) associated with the discharge of dioxin contaminated effluent to the Hikiji River, Kanagawa Prefecture, Japan
    KQ Sakamoto; K Nakai; T Aoto; A Yokoyama; R Ushikoshi; H Hirose; M Ishizuka; A Kazusaka; S Fujita
    CHEMOSPHERE, 51, 6, 491, 500, May 2003, [Peer-reviewed]
    English, Scientific journal
  • Short period exposure to di-(2-ethylhexyl) phthalate regulates testosterone metabolism in testis of prepubertal rats
    HS Kim; K Saito; M Ishizuka; A Kazusaka; S Fujita
    ARCHIVES OF TOXICOLOGY, 77, 8, 446, 451, 2003, [Peer-reviewed]
    English, Scientific journal
  • Perinatal exposure to low doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin alters sex-dependent expression of hepatic CYP2C11
    M Ishizuka; J Yonemoto; H Zaha; C Tohyama; H Sone
    JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, 17, 5, 278, 285, 2003, [Peer-reviewed]
    English, Scientific journal
  • Organochlorine compound accumulation in Steller sea lion Eumetopias jubatus migrating along the coast of Hokkaido in northern Japan.
    Hoshino, H; Fujita, S; Goto, Y; Isono, T; Ishinazaka, T; Sakurai, Y; Iwata, H; Kazusaka, A; Ishizuka, M; Tanabe, S
    Japanese Journal of Environmental Toxicology, 6, 1, 1, 10, 2003, [Peer-reviewed]
  • Hepatic microsomal cytochrome P450S and chlorinated hydrocarbons in largha and ribbon seals from Hokkaido, Japan: Differential response of seal species to AH receptor agonist exposure
    Chiba, I; A Sakakibara; H Iwata; M Ishizuka; S Tanabe; F Akahori; A Kazusaka; S Fujita
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 21, 4, 794, 806, Apr. 2002, [Peer-reviewed]
    English, Scientific journal
  • Accumulation patterns of polychlorinated biphenyl congeners and organochlorine pesticides in Steller's sea eagles and white-tailed sea eagles, threatened species, in Hokkaido, Japan
    KQ Sakamoto; T Kunisue; M Watanabe; Y Masuda; H Iwata; S Tanabe; F Akahori; M Ishizuka; A Kazusaka; S Fujita
    ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, 21, 4, 842, 847, Apr. 2002, [Peer-reviewed]
    English, Scientific journal
  • The loss of enzyme activities by a single amino acid substitution of a newly cloned rabbit CYP2D isozyme, CYP2D24
    Mayumi Ishizuka; Yukio Yamamoto; Ayato Takada; Akio Kazusaka; Shoichi Fujita
    International Congress Series, 1233, C, 121, 126, 2002, [Peer-reviewed]
    English, Scientific journal
  • P450 in wild animals as a biomarker of environmental impact
    Shoichi Fujita; Issei Chiba; Mayumi Ishizuka; Hidenobu Hoshi; Hisato Iwata; Akihito Sakakibara; Shinsuke Tanabe; Akio Kazusaka; Makihiko Masuda; Yasushi Masuda; Hajime Nakagawa
    Biomarkers, 6, 1, 6(1): 19-25, 25, 03 Feb. 2001, [Peer-reviewed]
    Scientific journal
  • Increased mutant frequency and altered mutation spectrum of the lacI transgene in Wilson disease rats with hepatitis
    H. Sone; Ying Jie Li; M. Ishizuka; Y. Aoki; M. Nagao
    Cancer Research, 60, 18, 5080, 5086, 15 Sep. 2000, [Peer-reviewed]
    English, Scientific journal
  • Comparative effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on MCF-7, RL95-2, and LNCaP cells: Role of target steroid hormones in cellular responsiveness to CYP1A1 induction
    Nihar Ranjan Jana; Shubhashishi Sarkar; Mayumi Ishizuka; Junzo Yonemoto; Chiharu Tohyama; Hideko Sone
    Molecular Cell Biology Research Communications, 4, 3, 174, 180, Academic Press Inc., 2000, [Peer-reviewed]
    English, Scientific journal
  • Role of estradiol receptor-alpha in differential expression of 2,3,7,8-tetrachlorodibenzo-p-dioxin-inducible genes in the RL95-2 and KLE human endometrial cancer cell lines
    NR Jana; S Sarkar; M Ishizuka; J Yonemoto; C Tohyama; H Sone
    ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 368, 1, 31, 39, Aug. 1999, [Peer-reviewed]
    English, Scientific journal
  • Accumulation of halogenated aromatic hydrocarbons and activities of cytochrome P450 and glutathione S-transferase in crabs (Eriocheir Japonicus) from Japanese rivers
    Mayumi Ishizuka; Takanori Sakiyama; Hisato Iwata; Minoru Fukushima; Akio Kazusaka; Shoichi Fujita
    Environmental Toxicology and Chemistry, 17, 8, 1490, 1498, 24 Aug. 1998, [Peer-reviewed]
    Scientific journal
  • Cloning, tissue distribution, and functional expression of two novel rabbit cytochrome P450 isozymes, CYP2D23 and CYP2D24
    Yukio Yamamoto; Mayumi Ishizuka; Ayato Takada; Shoichi Fujita
    Journal of Biochemistry, 124, 3, 503, 508, Japanese Biochemical Society, 1998, [Peer-reviewed]
    English, Scientific journal
  • Effects of the agrochemicals butachlor, pretilachlor and isoprothiolane on rat liver xenobiotic-metabolizing enzymes
    Mayumi Ishizuka; Hisato Iwata; Akio Kazusaka; Shigehisa Hatakeyama; Shoichi Fujita
    Xenobiotica, 28, 11, 1029, 1039, 01 Jan. 1998
    Scientific journal
  • Isozyme selective alterations of the expression of cytochrome P450 during regeneration of male rat liver following partial hepatectomy
    M. Ishizuka; S. Yoshino; Y. Yamamoto; H. Yamamoto; S. Imaoka; Y. Funae; M. Masuda; H. Iwata; A. Kazusaka; S. Fujita
    Xenobiotica, 27, 9, 923, 931, 29 Sep. 1997, [Peer-reviewed]
    Scientific journal
  • Alterations of cytochrome p450-dependent monooxygenase activities in Eriocheir japonicus in response to water pollution
    Mayumi Ishizuka; Hidenobu Hoshi; Nobuyuki Minamoto; Makihiko Masuda; Akio Kazusaka; Shoichi Fujita
    Environmental Health Perspectives, 104, 7, 774, 778, Public Health Services, US Dept of Health and Human Services, 1996, [Peer-reviewed]
    English, Scientific journal
■ Other Activities and Achievements
■ Books and other publications
■ Syllabus
  • 研究・臨床セミナー, 2024年, 学士課程, 獣医学部
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • アドバンスト演習, 2024年, 学士課程, 獣医学部
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • 研究機器演習, 2024年, 博士後期課程, 国際感染症学院
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • 獣医科学特別研究, 2024年, 博士後期課程, 獣医学院
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • 獣医科学特論演習, 2024年, 博士後期課程, 獣医学院
  • 大学院共通授業科目(一般科目):自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 研究機器演習, 2024年, 博士後期課程, 獣医学院
  • 大学院共通授業科目(一般科目):自然科学・応用科学, 2024年, 修士課程, 大学院共通科目
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • 大学院共通授業科目(一般科目):複合領域, 2024年, 修士課程, 大学院共通科目
  • インターンシップ, 2024年, 博士後期課程, 獣医学院
  • 専門獣医科学特論, 2024年, 博士後期課程, 獣医学院
  • 環境毒性学演習, 2024年, 博士後期課程, 獣医学院
  • ケミカルハザード対策専門特論, 2024年, 博士後期課程, 獣医学院
  • 研究機器演習(総合成績), 2024年, 博士後期課程, 獣医学院
  • 研究機器演習(総合成績), 2024年, 博士後期課程, 国際感染症学院
  • 環境獣医科学特論, 2024年, 博士後期課程, 獣医学院
  • HSI extension/professional program, 2024年, 学士課程, HSI
  • 基礎毒性学, 2024年, 学士課程, 獣医学部
  • 専門横断科目(一般科目):複合領域, 2024年, 学士課程, 専門横断科目
  • HSI extension/professional program, 2024年, 学士課程, HSI
  • 環境毒性学・環境衛生学, 2024年, 学士課程, 獣医学部
  • アドバンスト演習, 2024年, 学士課程, 獣医学部
  • アドバンスト演習, 2024年, 学士課程, 獣医学部
  • アドバンスト演習, 2024年, 学士課程, 獣医学部
  • 帯広基礎獣医学演習, 2024年, 学士課程, 獣医学部
  • 獣医倫理・動物福祉, 2024年, 学士課程, 獣医学部
  • 生物科学基礎演習(PBL), 2024年, 学士課程, 獣医学部
  • 獣医英語演習, 2024年, 学士課程, 獣医学部
  • 札幌基礎獣医学演習・獣医学概論, 2024年, 学士課程, 獣医学部
  • 研究スタートアップ演習, 2024年, 学士課程, 獣医学部
  • 獣医法規, 2024年, 学士課程, 獣医学部
  • 応用毒性学, 2024年, 学士課程, 獣医学部
  • 毒性学実習, 2024年, 学士課程, 獣医学部
■ Affiliated academic society
  • JAPANESE SOCIETY OF ZOO AND WILDLIFE MEDICINE
  • Japan Society of Endocrine Disrupter Research
  • JAPAN SOCIETY FOR ENVIRONMENTAL CHEMISTRY
  • THE JAPANESE SOCIETY OF VETERINARY SCIENCE
  • THE JAPANESE SOCIETY OF TOXICOLOGY
■ Research Themes
  • Global Monitoring of Nanoplastics and Additives in Wildlife Using Metal Analysis Techniques
    Grants-in-Aid for Scientific Research
    27 Jun. 2025 - 31 Mar. 2028
    石塚 真由美; 田中 厚資; 中山 翔太
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Pioneering), Hokkaido University, 25K21816
  • Creation of a platform for the evaluation of signal toxicity, starting with the development of methods for the detection and diagnosis of brain function disruption.
    Grants-in-Aid for Scientific Research
    01 Apr. 2023 - 31 Mar. 2027
    池中 良徳; 星 信彦; 野見山 桂; 杉尾 翔太; 石塚 真由美; 戸田 知得; 江口 哲史; 池中 建介; 平野 哲史
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 23H00512
  • アフリカの環境汚染によるヒトと動物の毒性学的影響とそのメカニズム解析
    科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
    07 Oct. 2022 - 31 Mar. 2026
    石塚 真由美; 武田 一貴; 池中 良徳; 江口 哲史; 中山 翔太
    日本学術振興会, 国際共同研究加速基金(国際共同研究強化(B)), 北海道大学, 22KK0163
  • Adaptive evolution/change in mammals to exogenous chemicals (xenobiotics)
    Grants-in-Aid for Scientific Research
    05 Apr. 2021 - 31 Mar. 2026
    石塚 真由美
    我々はこれまでの研究により、高次の動物が外来性の化学物質(Xenobiotics)への「適応」ために、化学物質の代謝や排泄など、解毒のカスケードに沿って薬物代謝酵素などの一連の多様性を発展させてきたとの仮説を立てた。化学物質感受性には多様性があり、解毒代謝酵素の解析から、この多様性獲得の主要因は食餌由来の化学物質である可能性を報告した。本研究では食性の観点および重度環境汚染域に棲息する動物を中心に、哺乳類が日常的に曝露される化学物質にどのように適応してきたのか、多様な種を用いてその進化を機能面から明らかにする。これまでの研究で構築してきた多様な動物試料を用いた研究体制を生かし、食性のユニークな動物種を対象としたウェットな実験や、データベースを用いた網羅的解析により、外来性の化学物質に対する動物の「適応」と「共存」メカニズムを明らかにする。


    今年度は、食肉目クマ科、スカベンジャー種(腐肉食類)等について、ゲノムデータベースを用いた遺伝子解析を行った。外来化学物質の代謝を担う第I相反応酵素シトクロムP450、第II相反応のグルクロン酸転移酵素や硫酸転移酵素について、種間比較を行い、食性との関連性について解析した。特に硫酸転移酵素についてはこれまで分子進化と食性に関するデータは少なく、研究成果については、現在論文を作成している。野生げっ歯類、トカゲ、一部の食肉性哺乳類について、次世代シークエンサーを用いて、エクソーム解析およびトランスクリプトームを行っている。また農薬や重金属の環境汚染地域に生活・棲息している野生げっ歯類及びヒトについてメタボローム解析を行った。現在データを解析中であるが、野生げっ歯類についてはDDT高濃度汚染域に棲息している野生げっ歯類のステロイド代謝への影響が認められた。現在、野生げっ歯類をDDT環境汚染レベル下で世代飼育し、フィールドデータの検証を行っている。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 21H04919
  • Construction and practice of MITA system for more sensitive and efficient toxicity testing
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Pioneering)
    30 Jun. 2022 - 31 Mar. 2025
    池中 良徳; 野見山 桂; 新間 秀一; 杉尾 翔太; 石塚 真由美; 江口 哲史; 中山 翔太; 星 信彦; 平野 哲史
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Pioneering), Hokkaido University, 22K18425
  • Large scale mapping of marine pollution risk using seabirds as a standardized sampling device
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    01 Apr. 2019 - 31 Mar. 2024
    綿貫 豊; 依田 憲; 石塚 真由美; 力石 嘉人; 高田 秀重
    本研究では,海鳥をデバイスとする新しいアイデアで,生物多様性・資源保全に資する,広域スケールの汚染マップを作る。そのため,北太平洋西部において,①バイオロギング(動物装着型データロガー)により多数の外洋性海鳥(オオミズナギドリ)個体の移動を通年追跡して,集中度が高いホットスポットを抽出する,②全個体の血液・羽根など体組織の汚染物質濃度を,栄養段階に対して標準化し,体組織形成時期に対応する各個体の利用場所に関連付けることで,汚染度を地図化する,そして③体組織中のストレスマーカーで汚染物質の生体影響を知り,ホットスポットのリスクを評価する,の3つを達成する汎用性の高い手法を開発することを目的としている。R1年度は,新潟県粟島において、雛を育てている40個体のオオミズナギドリに追跡装置(ジオロケーター:光強度を記録することで日の出日の入り時刻を知り、1年間の毎日の位置を推定する、超小型記録装置)を足輪にて装着した。一方で、繁殖期間中の採食場所と行動を調べるために、GPS・加速度データロガーを装着回収し、回収時にその胃内容を採取した。また,オオミズナギドリを中心とした既存の海鳥体組織標本(一部はes-BANKより資料提供)をつかって,さまざまな部位の羽や血液、体脂肪などの窒素・炭素安定同位体比、酸化ストレス指標やストレス関連ステロイドや汚染物質などの予備的化学分析を実施し、問題点について検討し、追跡個体の体組織の分析に備えた。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 19H01157
  • アフリカにおける新興・再興の環境汚染のフィールドベースの毒性メカニズム解析
    科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))
    09 Oct. 2018 - 31 Mar. 2022
    石塚 真由美; 池中 良徳; 中山 翔太; 中田 北斗
    近年、アフリカ諸国では急速な資源開発がすすめられている。そのため急激な環境の汚染が顕在化しており、一部の国では生態 系や家畜・ヒトにおける健康被 害が報告されるようになった。化学物質は、食糧生産や感染症制圧には必要不可欠であるが、途上国では化学物質汚染によるリスクを度外視して使用している現 状がある。2018年度に発表された大気汚染度を国別で分析した データでは世界ワースト10のうち7か国はアフリカで占められている。化学物質による脅威(ケミ カルハザード)については、 目に見えにくい潜在的な性質のため、対策が後手に回される傾向が強い。本研究では、アフリカでもっとも問題となっている金属、農薬についてその現状を明ら かにすること、およびフィールドトキシコ ロジーの概念により、そのメカニズムと現象を結 びつけることを目的としてい る。当該研究では、ザンビア大学(金属)および南アフリカのノースウェスト大学(再興農薬)、ガーナのクワメエンクルマ科学技術大学(KNUST 、新興農薬)と共 同研究を計画した。


    ザンビアでは鉛による環境汚染がヒトおよび動物に及ぼす毒性学的影響について調査を行った。特に、イヌを歩哨動物とした汚染モニタリング方法について報告した。また、乳児における鉛汚染の状況について調査を行った。ガーナではヒト試料の最終に向けた準備を行うとともに、ネオニコチノイドが神経系や脂肪代謝等に及ぼす影響について動物を用いた実験を行った。南アフリカではDDTが引き起こす毒性学的影響について、家畜や野生動物を用いてオミクス解析を行い、バイオマーカーの探索を行った。
    日本学術振興会, 国際共同研究加速基金(国際共同研究強化(B)), 北海道大学, 18KK0287
  • Evaluation of Chemical Susceptibility Diversity by mlAOP Concept and its Application to Understanding Insecticide Poisoning
    Grants-in-Aid for Scientific Research
    01 Apr. 2018 - 31 Mar. 2022
    IKENAKA Yoshinori
    In this study, we tested a new assessment concept, mlAOP, to evaluate species diversity in toxic effects. As a model compound, we focused on neonicotinoids (NN) and compared their neurotoxic effects on mice, zebrafish, and Xenopus. As a result, behavioral abnormalities and neurotransmitter disturbances were observed in both species at exposure levels below the non-toxic dose (NOAEL). Furthermore, in order to evaluate the sensitivity of a wide range of wild animal species, this study constructed an evaluation system focusing on skin fibroblasts, and evaluated the effects of NN in diverse species.
    Clinical studies conducted to evaluate human exposure and health effects were the first in the world to identify the source of exposure to neonicotinoids.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 18H04132
  • ザンビアにおける鉛汚染のメカニズムの解明と健康・経済リスク評価手法および予防・修復技術の開発
    国際的な科学技術共同研究などの推進 SATREPS
    2015 - 2021
    石塚 真由美
    汚染除去法を最適化し、健康リスク評価に基づく経済効果を定量化 鉛汚染が深刻なザンビアにおいて生態系および人への汚染メカニズムとリスクを解明し、経済的損失を可視化することで、汚染防御対策や環境修復へと結びつける。リモートセンシングによる調査、地上調査による土壌や植物のキャラクテリゼーション、人の鉛汚染のメカニズム、健康ハザードと経済リスクの可視化、環境修復技術の確立と同時に、モニタリングシステムの構築とキャパシティビルディングによる各専門家の持続的育成を行う。 環境修復、健康・経済リスク評価をもとに、汚染低減に貢献! ザンビアの未来を担う人(特に幼児)の鉛レベルに低下が見られる。ザンビアにおける環境修復、健康リスク評価の新規プロトコルなどの政策に採用される。将来的には、アフリカを中心とした世界的に主要なハザードである金属汚染対策に貢献する。
    科学技術振興機構, 北海道大学
  • Development of new "cocktail type" rodenticide
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
    29 Jun. 2018 - 31 Mar. 2020
    Ishizuka Mayumi
    Currently, secondary damage to birds of prey from rodenticides is frequently occurring. Therefore, no effective and safe control measures exist for rodenticide-resistant rats. This is due to the lack of research on resistance acquisition mechanisms and the lack of methods for assessing susceptibility in wildlife. The purpose of this study was to elucidate the causes of the acquisition of rodenticide resistance and to obtain data that will contribute to the development of rodenticides and their conservation to non-target species. This study demonstrated that mutations in the binding pocket and within the binding pocket of vitamin K epoxide reductase contribute to the acquisition of resistance in wild rodents as a cause of rodenticide resistance, and revealed a new mechanism of resistance acquisition through enhanced NADPH production and subsequent activation of rodenticide metabolism by cytochrome P450.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 18K19847
  • Elucidation of species differences and adaptive evolution of chemical sensitivity in mammal and bird species
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    01 Apr. 2016 - 31 Mar. 2020
    Ishizuka Mayumi
    We cloned P450 and UGT, the major pathways of xenobiotic metabolism in the liver, in mammals and birds, and characterized them enzymatically, identifying species in which UGT and ST are deficient or extremely inactive and the causes. In addition, anticoagulant rodenticides are currently used primarily for the control of exotic small mammals worldwide. Therefore, we evaluated the susceptibility of a wide range of animal species to rodenticides and clarified the differences in the metabolic capacity of P450 and UGT.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 16H01779
  • Contraction of wild-life iHep cell and development of the evaluation method for metabolism of the top predator
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
    30 Jun. 2017 - 31 Mar. 2019
    Ikenaka Yoshinori
    The purpose of this study is to develop the evaluation method of metabolism, which is the key to chemical sensitivity, and to clarify the chemical metabolic ability of rare top predator. Fresh liver is required for the evaluation of metabolism, but rare species are difficult to obtain. Therefore, in this study, we attempted to differentiate and induce liver-like cells (iHep cells) from skin fibroblasts by direct reprogramming. First, as a result of this study, we succeeded in culturing fibroblasts of several top predators such as brown bear and Sea lion. Furthermore, as a result of attempting to induce iHep cells using cultured fibroblasts, it was found that the cells were transformed into epithelial cells expressing albumin by introducing a specific factor. In this study, it is highly probable that iHep cells were successfully generated starting from wild animals.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 17K20038
  • Toxicological assessment of organohalogen contaminants in cat (Felis catus) omics approach
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2016 - 31 Mar. 2019
    Nomiyama Kei; Ishizuka Mayumi; Iwata Hisato
    In vivo exposure of 12 PCB congeners mixture were conducted on cats, and analyzed transcriptome and metabolome in blood, liver and brain.
    Of the 21890 genes in the transcriptome, 531 genes showed significant differences in the PCBs-exposed group. As a result of the pathway analysis, the inflammation and infection related pathways are affected, and the influence on the immune system by PCBs was suggested.
    In metabolome analysis of serum, 122 metabolites showed significant difference. As a result of pathway analysis, metabolome related to central carbon metabolism such aspentose phosphate pathway and histidine metabolic system decreased, suggesting suppression of these metabolic pathways accompanying PCBs exposure.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Ehime University, 16H02989
  • Investigation of hepatic warfarin metabolism activity in rodenticide-resistant black rats (Rattus rattus)
    Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
    01 Apr. 2016 - 31 Mar. 2018
    Ishizuka Mayumi
    Anti-blood coagulation rodenticides, such as warfarin, have been used all over the world. They inhibit vitamin K epoxide reductase (VKOR), which is necessary for producing several blood clotting factors. This inhibition by rodenticides results in lethal hemorrhage in rodents. However, heavy usage of these agents has led to the appearance of rodenticide-resistant rats. The mutation of the target enzyme of warfarin, VKOR, is considered as major cause for rodenticide resistance in wild rats. However, there have been few studies regarding the hepatic metabolism of warfarin. We investigated warfarin metabolism in resistant rats, and our results showed new mechanism for the rodenticide resistance in wild black rats in Japan.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 16K15034
  • Elucidation of useful livestock/poultry for Pb source estimation and its molecular mechanisms underlying species differences by integrated metallomics approaches
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    01 Apr. 2016 - 31 Mar. 2018
    Nakayama Shouta; Ishizuka Mayumi; Ikenaka Yoshinori; Mizukawa Hazuki; Hirata Takafumi
    According to WHO, approximately 230,000 people annually die mainly from lead (Pb) poisoning derived from mineral deposits and affect the intellectual development of more than 600,000 children, but useful methods for estimating pollution sources have not been established. In this study, we aimed to elucidate useful livestock and poultry species for source estimation of Pb contamination. From the high precision lead isotope ratio analysis, it was revealed that it is possible to estimate the source of Pb contamination by using goats and chickens distributed in developing countries including Africa and also used as human food sources. Local distribution of Pb in mice was analyzed by LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry). High Pb accumulation in the hippocampus area of the brain and Pb accumulation at a higher concentration than in the cortex than the medulla of the kidney was revealed.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 16K16197
  • Risk assessment of vector control chemicals to wild animals and development of novel method to determine the chemical sensitivity
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2015 - 31 Mar. 2018
    Ikenaka Yoshinori
    In this study, attention was paid to the KwaZulu-Natal state in South Africa, a vector control area in Africa, and its threat situation was investigated and toxicity impact assessment was conducted on living organisms.
    As a result of investigation focusing on poultry, the DDT concentration in the liver showed a very high value of 920 ng / g ww in the median and 14,400 ng / g ww in the maximum value. As a result of gene expression analysis by real-time RT-PCR method, it became clear that it affected genetic group involved in lipid metabolism, synthesis and sex steroid hormone synthesis. The results of this study suggest that DDT gives certain effects to the living body, suggesting the need to implement more appropriate Vector control in the future.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 15H02825
  • Elucidation for metabolic capacities of organologen compounds and assessment of thyroid function
    Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
    01 Apr. 2015 - 31 Mar. 2018
    MIZUKAWA HAZUKI; ISHIZUKA Mayumi; IKENAKA Yoshinori; NAKAYAMA Shouta; TAKIGUCHI Mitsuyoshi; NOMIYAMA Kei
    To clarify the in vivo kinetics (absorption, distribution, metabolism, and excretion) of organohalogen compounds in cats, PCBs short-term administration test and long-term administration test of BDE 209 were carried out. Also, I have evaluated the influence on thyroid function and risk assessment by chemical and toxicological analysis. As a result, exposure to PCBs and BDE 209 not only affected thyroid function but also increased oxidative stress, disturbance of production of NADPH, disturbance of lipid metabolism function and immune function were expected.
    Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Hokkaido University, 15K16132
  • Ecological and human risk assessment of vector control pesticides
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
    01 Apr. 2014 - 31 Mar. 2017
    Ikenaka Yoshinori; SAKURAI Tatsuya; MIYABARA Yuichi; SHIMOZURU Michito; NAKAYAMA Shouta; MIZUKAWA Hazuki; Johan van Vuren; Vlok Wynand; Smit Nico; Grobler Paul; Beyene Yared; Teju Endale
    WHO recommended to use DDT for controlling Anopheles, and allow to use more than 5000 tons as indoor residual spraying (IRS) in developing countries mainly in Africa. On the other hand, DDT is well known chemical that is persistence in the environment and has long half-life, with carcinogenicity and endocrine disruption. IRS is considered low environmental burden because spraying occurs inside the house, however, there is insufficient research about the effect on human and animals. From our data, chicken accumulated very high concentration of DDT with the cancer risk for humans health. Moreover, wild rats was accumulated DDT with exceeded the levels that in experimentally exposed rat had cause the liver function disorder. Furthermore, I could detect DDTs from all the examined eggs from wild birds.
    These results indicated that DDT IRS that has been considered as low environmental impact has potential toxicological effects and environmental risks.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 26304043
  • Development of analytical method for the organohalogen metabolites elucidation of metavolic capacities and risk assessment in the pet cat
    Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity Start-up
    30 Aug. 2013 - 31 Mar. 2015
    MIZUKAWA Hazuki; ISHIZUKA Mayumi; IKENAKA Yoshinori; NAKAYAMA Shouta; TAKIGUCHI Mitsuyoshi; NOMIYAMA Kei
    This study was develop the analyzing method for hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and the glucuronidation compounds of OH-PCBs using liquid chromatography tandem mass spectrometry (LC-MS/MS). Moreover, it was measured the glucuronidation activities using the liver microsomes of the cats. I also attempted the evaluation of metabolic capacities of PCBs and PBDEs in the cats.
    Japan Society for the Promotion of Science, Grant-in-Aid for Research Activity Start-up, Hokkaido University, 25892001
  • カロテノイド/レチノイド類による有蹄類の異物代謝の新たな調節機構の解明
    科学研究費助成事業 特別研究員奨励費
    2011 - 2013
    石塚 真由美; DARWISH Abdallah; DARWISH ABDALLAH
    シトクロムP450の分子種のひとつCYPIA1は様々な発がん物質や変異原物質を代謝的に活性化し、化学物質の毒性を決定する重要な異物代謝酵素である。CYPIA1はAhR(アリルハイドロカーボン受容体)によって転写調節を受けており、CYPIA1の上流域のXRE (Xenobiotic Response Element)に結合してその転写を活性化することが知られている。最近、我々はカロテノイド類がAhRの機能に影響を及ぼすことを見出しており、カロテノイドがCYPIA1の生理的な動態の決定因子の一つである可能性を見出している。そこで、本研究では、カロテノイド類がAhRに及ぼす影響、およびその他のシトクロムP450分子種を制御する転写調節因子とのクロストークを明らかにし、カロテノイド類の新たな機能を明らかにすることを目的とする。
    本年度は、実際に産業動物などがどの程度の重金属類を蓄積しているのかを明らかにし、実施に環境中で人や動物が暴露されている範囲での金属暴露を細胞を用いて行った。H4IIE細胞、およびHepG2細胞を用いて実際に動物が暴露される可能性のある濃度で金属類及びカロテノイドの暴露が異物代謝酵素群にどのような影響を及ぼすのかについて調べた。金属類の曝露によりシトクロムP450、グルクロン酸抱合酵素等の発現量が減少した。メカニズムとして酸化ストレスの介在が考えられたが、同時に転写調節因子の発現量も減少していた。
    日本学術振興会, 特別研究員奨励費, 北海道大学, 11F01097
  • Effects of environmental pollutants on cancer in wildlife
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    2007 - 2010
    FUJITA Shoichi; IKENAKA Yoshinori; ISHIZUKA Mayumi; SAKAMOTO Kentaro
    We investigated bioaccumulation levels of environmental chemicals, e.g., carcinogens and pro-carcinogens, in wildlife and elucidated the effects of these environmental toxic compounds. We cloned cytochrome P450 1 subfamilies, arylhydrocarbon receptors and phase II enzymes, which contribute to activation or detoxification of carcinogens and procarcinogens, from bird and mammalian species including rare wildlife, and characterized these molecules. We also reported the molecular evolution of these enzymes and regulation receptors in wildlife.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 19208028
  • A birth cohort study to detect adverse health effects of environmental chemicals on the next generation and gene-environment interaction
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    2007 - 2009
    KISHI Reiko; SATA Fumihiro; YOSHIOKA Eiji; BAN Susumu; NAKAJIMA Sonomi; SASAKI Seiko; MUROHASHI Harumitsu; KAMIO Youko; SENGOKU Ysuhito; HANAOKA Tomoyuki; SAIJO Yasuaki; FUJITA Shoichi; NAKANAWA Hiroyuki; KAJIWARA Junboku; YUASA Motoyuki; ISHIZUKA Mayumi
    The prospective birth cohort with one obstetric hospital in Sapporo City has been conducted to investigate the association between child growth, neuro-development, and allergy, and low-level exposure to environmental chemicals during pregnancy, infancy and up to school age. A follow-up questionnaire was used at 18, 42, and 84 months of age to obtain relevant information including allergy prevalence, dietary habits, and smoking history of mother and the partner. The levels of PCDDs/PCDFs and PCBs in maternal blood and breast milk were measured using a high-resolution gas chromatography/high-resolution mass spectrometer (HRGC/HRMS). PFOS and PFOA levels in maternal blood were analyzed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). We assessed the influence of low level intrauterine exposure of toxic chemicals on childhood neurodevelopment at 6, 18 and 42 months of age using the Bayley Scales of Infant Development second edition (BSID-II) and Japanese version of the Kaufman Assessment Battery for Children (K-ABC). The Japanese version of the Child Behavior Checklist (CBCL) was used to collect information on child behavior at age 43 months.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 19209024
  • ホルムアルデヒドはパーキンソン氏病の原因となりえるか?
    科学研究費助成事業 萌芽研究
    2007 - 2008
    藤田 正一; 石塚 真由美; 坂本 健太郎
    ホルムアルデヒドはシックハウス症候群の1原因物質としてその詳細が調べられてきた。しかし、長期曝露による神経毒性は、「神経変性」という観点からは不明であり、さらに、ホルムアルデヒドとドパミンの縮合によって合成されるノルサルソリノールに着目してその毒性やパーキンソン氏病との関連を研究した報告は殆どない。そこで、本研究では、上記仮説の検証を含め、ホルムアルデヒドの内因性の発生や消去能の低下、ホルムアルデヒドを発生させる環境化学物質への曝露が弧発性パーキンソン氏病の原因となりえるのかを究明することを目的とする。
    本年度は、脳におけるホルムアルデヒドの解毒に重要なADH3のノックアウト(KO)マウスの繁殖を行い、材料採集と受容体発現の変化について調べた。また、行動を詳細に解析するために、データロガーを用いた毒性学的な行動解析方法を確立した。
    一方、シトクロムP450の分子種のひとつCYP2Dの遺伝的多型がパーキンソン氏病の発症とかかわりがあるとの報告があることから、ドパミンの代謝へのCYP2Dの関与について同定を行った。CYP2Dを欠損するDAラットを用いてカテコールアミン濃度や代謝に対し、P450がどのように関与するのか、明らかにした。また、その過程ではDAラットにおけるCYP2D2mRNAの低発現は、CYP2D2遺伝子の転写調節領域内の一塩基置換により、hnRNP K蛋白質のDNA結合が低下する事が原因である事を初めて明らかにした。
    日本学術振興会, 萌芽研究, 北海道大学, 19658111
  • 凍結ケナガマンモスのチトクロームP450を用いた更新世の古環境復元
    科学研究費助成事業 萌芽研究
    2006 - 2007
    坂本 健太郎; 藤田 正一; 石塚 真由美
    チトクロームP450(CYP)は外来異物を主な基質とする事を特徴とする酵素である。天然物質としては植物性アルカロイドなどが基質として知られている。これは植物側が捕食されないための防衛手段として毒性のあるアルカロイドを産生し、草食動物がそれを解毒するための酵素を進化させたと考える事が出来る。従って、解素酵素を解析することによって、餌生物に関する情報を得る事が出来るのではないかと考えた。本研究の最終的な目標は、既に絶滅してしまったケナガマンモスのCYPの解析を通して、その種が生息していた環境に関する情報を得ることである。本年度は下記の成果を得た。
    CYPの種間差を比較検討するために、哺乳類の12目、38種の試料採集を行った。このサンプルを元に、CYP1AのcDNAをクローニングし、その塩基配列について比較検討を行った。また、酵素活性と基質特異性について調べた。
    哺乳動物目間の比較では、食肉目内で塩基配列の種差が比較的少ない傾向が明らかとなった。また、酵素活性を調べたところ、草食獣では他の食性をもつ動物種に比べ、酵素活性が高いことが明らかとなった。これらの草食獣では、肝臓におけるCYP1Aの発現レベルも高かったことから、草食性の動物ではCYPをより多く発現させることで酵素活性を高く保っていると考えられた。食性の違いで代謝の動物種差があることから、これらの傾向は動物の生息状況を反映している可能性が示唆された。
    日本学術振興会, 萌芽研究, 北海道大学, 18658129
  • Development of Environmental Risk Assessment System
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    2003 - 2006
    FUJITA Shoichi; ISHIZUKA Mayumi; SAKAMOTO Kentaro
    The DNA microarray techniques are useful method to determine toxicological effects of xenobiotics, such as drugs and environmental chemicals, on the cells or experimental animals. To clarify the usefulness of DNA microarray method for wildlife samples, we collected wild Norway rats (rats) from urban areas, landfill and isolated island in Japan. Laboratory rats (Wistar) were used as control animals in this study. We measured the accumulation levels of polychlorinated dibenzo-p-dioxins (PCDD), furans (PCDF), polychlorinated biphenyls (PCBs), and organochlorine insecticides. We also examined the residue levels of polybrominated diphenyl ether (PBDE) in rat livers, which are used as flame retardants in plastics and rubbers. Additionally, we screened the alterations of mRNA in liver and testis of wild rats using DNA chip technique, and reported the relationships between accumulated contaminants and expression profiles of RNA. In this study, we also showed the genes which can be used as biomarkers.
    To develop the DNA microarray for wild animals, we collected samples of wild and captive animals to compare the gene sequences. We cloned P450 and nuclear receptor genes from broad spectrum mammalians, birds and amphibians. We elucidated the possibility of microarray development for several wildlife species.
    In current study, we also aimed at establishment of functional array which can assess the affinity of environmental chemicals to nuclear receptors. We determined the ligand affinities of nuclear receptors and cross-talk among xenobiotic receptors, e.g., arylhydrocarbon receptor, constitutive active receptor and peroxisome proliferator-activated receptors.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 15201009
  • 狂牛病原因物質プリオン・モデルペプチドの変成機序に関する分光学的研究
    科学研究費助成事業 萌芽研究
    2002 - 2003
    数坂 昭夫; 佐々木 一正; 石塚 真由美; 藤田 正一
    狂牛病を始めとするプリオン病研究において、PrPcからPrPScへの変性機序の解明と、それに基ずく発病機序の解明が重要と考え、幾つかの検討を行ってきた。その後、諸外国での研究成果の蓄積が多く重ねられている。それらの成果を考慮し本年は以下の研究を進めてきた。幾つかの成果を得た。
    1.生体中で、変性によって生ずる異常タンパク質を高選択・高感度に検出するバイオセンサーの開発を試みた。
    2.研究分担者が従来行ってきた、光ファイバセンシング・システムの改良を行い、目的達成を試みた。本システムでは、従来の蛍光発光の測定に加え、光屈折を利用する表面プラズモン測定を検出系とするシステム開発を継続中である。
    3.光ファイバに先端にPrPScに特異的に反応する抗体を固定化し、高選択バイオセンサの作成を試みている。光ファイバ先端を金微粒子を含む高分子で加工することにより抗体を安定に固定化することが可能であることが明らかになった。金微粒子の調製と高分子の選択が現在の課題である。
    4.タンパク質変性状態をより詳しく調べることを目的として、捕捉されたタンパク質のラマンスペクトル観測の有効性が期待される。その時、タンパク質に銀微粒子等を加えることにより、Surface enhanced ramanスペクトルの観測も期待され、高感度バイオセンサーへの拡張を今後の検討課題と考えている。
    日本学術振興会, 萌芽研究, 北海道大学, 14657091
  • 哺乳類の生殖および行動異常の現状と汚染の関係
    科学研究費助成事業 特定領域研究
    2001 - 2003
    藤田 正一; 昆 泰寛; 石塚 真由美; 数坂 昭夫
    環境汚染による野生動物への影響として、野生生物における個体数の減少、奇形の発生、性比のバランスの変化、繁殖能低下や行動異常が懸念されている。特に、PCBなどの有機塩素系化合物は、環境中において安定で脂溶性に富むため、食物連鎖の上位に立つ生物に高濃度の濃縮されることが知られている。当該研究では、アザラシやイルカ等の海棲哺乳類に、生物濃縮によって高濃度の有機塩素系化合物が蓄積されていることや、それらが内分泌系を撹乱している可能性を報告した。
    前述の海棲哺乳類については残留性の高い環境汚染物質が高濃度に蓄積しているため、他にも多くの毒性学的データが得られている。しかし、一方で、陸棲哺乳類については、魚食性の海棲哺乳類に比べると汚染レベルも低いため、環境汚染物質曝露がこれらの生物にもたらす影響については報告が少ない。そこで、我々は本研究において、陸生野生げっ歯類(アカネズミ、エゾヤチネズミ、ドブネズミ)に関し、生体に蓄積する環境汚染物質(ダイオキシン類、そのほかの有機塩素系化合物、臭素系難燃剤)や、土壌など棲息環境の汚染(PCB、DDTなどの有機塩素系化合物、多環芳香族)の分析を行い、また、生殖行動を調節するステロイドホルモンに関して、生合成・代謝を行う代謝酵素シトクロムP450(P450、CYP)の発現や活性、生殖器の発現遺伝子プロファイルや病理的変化との関係について調べた。また、野生げっ歯類のモデルとして、ラットを用いて、環境化学物質がどのような影響をもたらす可能性があるのかについて明らかにした。
    日本学術振興会, 特定領域研究, 北海道大学, 13027201
  • ヒト生殖毒性および次世代影響のバイオマーカーとしての神経内分泌動態の有効性
    科学研究費助成事業 萌芽研究
    2001 - 2002
    岸 玲子; 佐田 文宏; 小橋 元; 本間 研一; 石塚 真由美
    「目的」近年、内分泌かく乱物質に関する問題が重要視され、スチレン、2-ブロモプロパンなどの有機溶剤曝露労働者での無月経、不正月経周期、不正出血、受精率の減少が報告されている。その作用機序を解明するために、内分泌かく乱物質も含めた環境化学物質曝露による神経内分泌物質の動態と、生殖毒性の発現について知見を得ることを目的とした。
    「方法」産業分野での用途の広さ、また、日常的にも食品容器としての使用頻度の高さに伴い、取り扱い作業者の数も多いことから、内分泌かく乱作用の疑いのある有機溶剤スチレンモノマーを使用した。8週令オスラットに150ppm吸入曝露8時間/日で12日間行い、血漿中プロラクチン、成長ホルモン、甲状腺刺激ホルモンレベルをELISAにより測定した。また、精巣、血液を採取し、リアルタイムPCRによる精巣ステロイド合成酵素mRNAの定量と組織学的検討、RIAによる血中テストステロン濃度の検討を行った。
    「結果と考察」曝露により、血漿中のプロラクチンがメスで、甲状腺刺激ホルモンがオスで有意に増加していた。精巣毒性の検討で、血漿中テストステロン濃度、精巣組織への曝露影響は見られなかった。また、ステロイド合成酵素であるP450scc,3-beta-hydroxysteroid dehydrogenase, CYP17,CYP19 mRNAの発現には、どれも有意な差は見られなかった。プロラクチンに関しては、労働者で有意に増加するという報告があることから、疫学的報告を裏付ける結果を得た。また、結果の雌雄差については、血中スチレン濃度に雌雄差があったことから、代謝能力の違いによるものと考えられる。生殖毒性に関しては、短期間曝露であったため影響が見られなかったと考えられるため、今後より高濃度、長期間曝露の検討が必要である。
    日本学術振興会, 萌芽研究, 北海道大学, 13877057
  • The effects of endocrine disrupting chemicals on wildlife
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    1999 - 2002
    FUJITA Shoichi; HIDENOBU Hoshi; ISHIZUKA Mayumi; KAZUSAKA Akio
    In this study, we investigated the accumulation levels of environmental pollutants and their effects on the hormonal homeostasis in reproductive organs and livers of wild life or experimental animals. Especially, we focused on the effects of environmental pollutants on fish-eating wild life, since numerous lipophilic compounds were accumulated in these species.
    Chlorinated hydrocarbon (CHCs) levels in the blubber of Larga seals and Ribbon seals collected from the coastal waters of Hokkaido, Japan were determined in order to assess the hormonal effects of CHC exposure. In Ribbon seals, total T3 levels significantly decreased with an increase of di-ortho PCB (PCB170 and 180) residues. We also determined the organochlorine concentrations in the breaset muscle of Steller's sea eagles and white-tail sea eagles. We detected PCB, DDT and other organopesticides at high levels, which was possible to cause reproductive toxicity. Furthermore, we investigated the accumulation levels of other heavy metals and detected tri-butyltin (TBT) in wild life at high concentration. Thus, we investigated the effects of TBT on the developing experimental animals. The pregnant rats were administrated corn oil or TBT from gestation day (GD 5) through postnatal day (PND) 25. The glial cell differentiations in hypothalamus and cerebellum of pups were transiently suppressed by TBT treatment.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 11306021
  • The risk assessment and clarification of endocrine disrupting chemicals in environment. Use of P450 for the biomonitoring and bioremediation of environmental pollution-
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
    1999 - 2002
    FUJITA Shoichi; HOSHI Hidenobu; ISHIZUKA Mayumi; KAZUSAKA Akio
    The usefulness of P450 as a biomarker and an assessing tool for the impact of environmental endocrine disrupting chemicals on the wild animals was studied.
    Chlorinated hydrocarbon (CHC) levels in the blubber of Larga seals and Ribbon seals collected from the coastal waters of Hokkaido, Japan were determined in order to assess the hormonal effects of CHC exposure. In these animals, CYP1A expression levels were coincided with CHC accumulation levels. We also tried to isolate P450 isoforms such as CYP1A and CYP3A subfamilies, which contributed to elimination of xenobiotic and to catabolism of steroid hormone in mammals. We detemined the sequences and enzymatic characters of CYP1A1, CYP1A2 and CYP3A forms.
    We also investigated the CHC effects on xenobiotic metabolisms and hormonal homeostasis in fish. We collected male and female carps from Hikiji river, where raw sewage containing dioxins had been released into river water for seven and a half years. The expression levels of CYP1A subfamily were coincided with dioxin accumulation levels. In contrast, estrogen level and GSI (gonadal somatic index) value were reduced in female carps collected from dioxin-contaminated river.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 11358009