1992/04/01-1993/03/31 Oda College of NutritionAnatomical physiologyadjunct instructor lecturer
1993/04/01-1996/03/31 JSPS FellowshipResearch fellow
1996/04/01-1999/04/30 Kitasato University School of Veterinary Medicine and Animal SciencesVeterinary RadiologyResearch assistant
1999/04/01-Present Iwate UniversityFaculty of Agricultureadjunct instructor lecturer
1999/05/01-2006/06/30 Kitasato University School of Veterinary Medicine and Animal SciencesVeterinary RadiologyAssistant Professor
2006/07/01-2007/06/30University of TennesseeFaculty of Veterinary MedicineResident (Veterinary radiology)
2007/04/01-2019/03/31Tokyo University of Agriculture and TechnologyFaculty of Agricultureadjunct instructor lecturer
2007/07/01-2008/03/31JARMeC; Japan Animal Referral Medical CenterRadiologyDean
2008/04/01-2013/03/31JARMeC; Japan Animal Referral Medical CenterDirector and Dean of Radiology
2013/04/01-PresentKitasato UniversitySchool of Veterinary MedicineProfessor
EDUCATION
1991/06/30 Utrecht UniversityFaculty of Veterinary Medicine as a Research fellow
1992/03/31 Graduated Tokyo University of Agriculture and TechnologyFaculty of AgricultureDepartment of Veterinary Medicine
1995/06/30 Utrecht UniversityFaculty of Veterinary MedicinePost as a doctoral trainee
1996/03/31 CompletedGifu UniversityUnited Graduate School, Division of Veterinary Medicine PhD course
The effect of exposure on cattle thyroid after the Fukushima Daiichi nuclear power plant accident Daiki Horikami, Naoya Sayama, Jun Sasaki, Haruka Kusuno, Hiroyuki Matsuzaki, et al. Scientific Reports, 2022 Nuclear plant accidents can be a risk for thyroid cancer due to iodine radioisotopes. Near the Fukushima Daiichi nuclear power plant, cattle were exposed to radiation after the accident occurred in May 2011. Here we estimated the total radiation exposure to cattle thyroid and its effects on thyroid function. Until October 2016, the estimated external exposure dose in Farm A was 1416 mGy, while internal exposure dose of 131I, 134Cs, and 137Cs were 85, 8.8, and 9.7 mGy in Farm A and 34, 0.2, and 0.3 mGy in Farm B, respectively. The exposed cattle had thyroid with relatively lower weight and lower level of stable iodine, which did not exhibit any pathological findings. Compared with the control, the plasma level of thyroid-stimulating hormone (TSH) was higher in Farm A cattle born before the accident, while the plasma thyroxine (T4) was higher in Farm A cattle born after the accident, suggesting that exposed cattle showed slight hyperactivation of the thyroid gland. In addition, Farm A cattle have higher level of cortisol, one of the anterior pituitary gland-derived hormones. However, we did not observe a causal relationship between the radiation exposure and cattle thyroid.
The Japan Health Physics Society Guideline on Dose Monitoring for the Lens of the Eye Sumi Yokoyama, Norio Tsujimura, Makoto Hashimoto, Hiroshi Yoshitomi, Masahiro Kato, et al. Journal of Radiation Protection and Research, 2022 Background: In Japan, new regulations that revise the dose limit for the lens of the eye (hereafter the lens), operational quantities, and measurement positions for the lens dose were enforced in April 2021. Based on the international safety standards, national guidelines, the results of the Radiation Safety Research Promotion Fund of the Nuclear Regulation Authority, and other studies, the Working Group of Radiation Protection Standardization Committee, the Japan Health Physics Society (JHPS) developed a guideline for radiation dose monitoring for the lens.Materials and Methods: The Working Group of the JHPS discussed the criteria of non-uniform exposure and the management criteria set not to exceed the dose limit for the lens.Results and Discussion: In July 2020, the JHPS guideline was published. The guideline consists of three parts: main text, explanations, and 26 examples. In the questions, the corresponding answers were prepared, and specific examples were provided to enable similar cases to be addressed.Conclusion: With the development of the guideline on radiation dose monitoring of the lens, radiation managers and workers will be able to smoothly comply with revised regulations and optimize radiation protection.
L-band electron paramagnetic resonance tooth dosimetry applied to affected cattle teeth in Fukushima Ichiro Yamaguchi, Kazuhiko Inoue, Masahiro Natsuhori, Chryzel Angelica B. Gonzales, Hiroshi Yasuda, et al. Applied Sciences Switzerland, 2021 We applied a non-destructive tooth dosimetry technique using L-band electron paramagnetic resonance (EPR) to assess radiation doses in cattle due to the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, which occurred 10 years ago. The radiation exposure of cattle in the area affected by the FDNPS accident was estimated retrospectively with X-band and L-band EPR devices. Characteristic radiation-induced EPR signals were obtained from the teeth of the cattle in Fukushima, confirming their exposure. The estimated doses to the teeth were found to be consistent with the dose trends estimated for individual cows, while considerable uncertainties were seen in the doses of some tooth samples. This variation might be due to errors in the accuracy of the method but also might reflect the actual exposure because the cattle may have been exposed to higher areas of radioactivity in their quest for food and/or due to irradiation from absorption of the isotopes with localization in or near the teeth. However, at a minimum, these results confirm that L-band EPR can be used for non-destructive qualitative assessment of radiation exposure to animals using their teeth, which could be very valuable. Possible causes of the uncertainties should be investigated to enhance the value of the use of this technique.
Assessments of DNA Damage and Radiation Exposure Dose in Cattle Living in the Contaminated Area Caused by the Fukushima Nuclear Accident Itaru Sato, Jun Sasaki, Hiroshi Satoh, Masahiro Natsuhori, Takahisa Murata, et al. Bulletin of Environmental Contamination and Toxicology, 2020 Since the Fukushima nuclear accident in 2011, various abnormalities have been reported in animals living in the contaminated area. In the present study, we examined DNA damage in cattle living in the "difficult-to-return zone" by 8-hydroxy-2′-deoxyguanosine, comet, and micronucleus assays using their peripheral blood. The radiation exposure dose rate at the sampling time was approximately 0.25 or 0.38 mGy/day and the cumulative dose was estimated at approximately 1000 mGy. Significant increase in DNA damage was not detected by any of the three methods. As DNA damage is a stochastic effect of radiation, it might be occurring in animals living in the contaminated area. However, the present results suggest that radiation-induced DNA damage in the cattle did not increase to the level detectable by the assays we used due to the low dose rate in this area.
ESR assessment of tooth enamel dose from cattle bred in areas contaminated due to the Fukushima Dai-ichi nuclear power plant accident Azumi Todaka, Shin Toyoda, Masahiro Natsuhori, Keiji Okada, Itaru Sato, et al. Radiation Measurements, 2020 ESR tooth enamel retrospective doses were obtained for teeth of 16 cattle bred in the two ranches located in the area contaminated by Fukushima Dai-ichi Nuclear Power accidents in 2011. The obtained doses are up to 1.0 Gy for cattle bred in both two ranches. The doses obtained for cattle in Omaru ranch, with higher contamination, are roughly consistent with the cumulative environmental dose. High dose values are also obtained for those in Okuma-Ikeda ranch, with lower contamination, which are not consistent with the cumulative environmental dose, but can be explained by the records that they were once released from the ranch and were captured in highly contaminated area. The ESR tooth enamel dose distribution within jaws were examined for two cattle of 12 years and 7 years old. The older cattle shows rather uniform distribution of the doses with slight increase in frontal teeth while the younger shows larger values in molar teeth, being consistent with the time difference in permanent tooth eruption (enamel formation). These results indicate that the cattle tooth enamel ESR dosimetry works practically and would be useful in estimating the actual environmental doses.
RETROSPECTIVE ESR RECONSTRUCTION OF CATTLE TOOTH ENAMEL DOSES FROM THE RADIOACTIVE NUCLEI RELEASED BY THE ACCIDENT OF FUKUSHIMA DAI-ICHI ATOMIC POWER PLANTS Shin Toyoda, Mika Murahashi, Masahiro Natsuhori, Setsuro Ito, Alexander Ivannikov, et al. Radiation Protection Dosimetry, 2019 The method of electron spin resonance (ESR) tooth enamel dosimetry was successfully applied to cattle molar teeth exposed in the accident of Fukushima Dai-ichi atomic power plants. Total of 10 samples from 5 cattle were examined and the doses were retrospectively reconstructed to be up to 1.2 Gy (enamel dose). The dose values are roughly consistent with those estimated from the monitored environmental dose rate and the durations of the exposure. This first successful result on ESR reconstruction of doses in the actual radiation accident indicates that ESR tooth enamel dosimetry with cattle is practically useful in the dose range of ~1 Gy.
Pathological characteristics of thyroid glands from Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident Jun Sasaki, Megumi Uehara, Itaru Sato, Hiroshi Satoh, Yoshitaka Deguchi, et al. Animal Science Journal, 2019 To study the effect of ionizing radiation on thyroid glands, 66 Japanese Black cattle residing in the restricted area of the Fukushima Daiichi Nuclear Power Plant in 2013-2017 were pathologically examined. There were no clinical symptoms of thyroid disease in these cattle. Three cases of goiter and seven of atrophy were found in two among the four farms examined. Cases of goiter exhibited normal morphological structure without mass or nodule formation in thyroid glands. Cellular atypia or capsular invasion of the follicular epithelium was absent. The estimated integrated dose of external radiation in goiter cases ranged from maximum 797 mSv to minimum 24 mSv. All lobules in the seven atrophic thyroid glands were affected, but pathological findings, such as inflammatory cell infiltration or stromal fibrosis, were not observed. The estimated integrated dose of external radiation in atrophic thyroids ranged from maximum 589 mSv to minimum 8 mSv. Immunohistochemical analysis of anti-nitroguanosine and the TUNEL method in goiter and atrophic thyroid glands did not reveal any positive findings. The present study indicates that there was no significant relationship between a radiation effect and pathological findings in any thyroid glands.
Comparison of urine and blood as a convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium Itaru Sato, Jun Sasaki, Hiroshi Satoh, Masahiro Natsuhori, Takahisa Murata, et al. Animal Science Journal, 2019 Blood and urine were compared to clarify which is a better sample for estimating the concentration of radioactive cesium in muscles of live cattle. The most probable concentration of 137 Cs in muscles was 21.0 times that in blood, and the error of this estimation was 28%. The concentration of 137 Cs in blood was estimated accurately using urine samples. The estimation error did not increase so much (33%), even when the concentration of 137 Cs in muscles was estimated using urine samples. On the other hand, the maximum volume of blood that can be collected with one syringe is 50 ml, whereas it is easy to collect 1,000 ml of urine. It took at least 360 min to confirm that a cow meets the legal standard by inspecting 50 ml of blood. However, with 1,000 ml of urine, a 20 min measurement time was sufficient for this purpose. This difference in the required measurement time is critically important for practical use. In addition, urine can be collected by farmers themselves, whereas the blood collection requires a veterinarian. Therefore, urine is a more convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium.
Estimation of bovine internal exposure dose from radiocesiumcontamination in the Fukushima restricted area by using EGS5 Proceedings of the 23rd EGS Users Meeting in Japan, 2017
Evaluation of external radiation exposure of human involved in equine bone scintigraphy (no.2) Proceedings of the 14th EGS Users Meeting in Japan, 2007
Dual-energy X-ray CT with a vertically expanded irradiation field Masami Torikoshi, Yumiko Ohno, Masahiro Natsuhori, Nobuhiko Ito, Kentaro Uesugi, et al. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment, 2007
Evaluation of external radiation dose of humans involved in veterinary nuclear medicine by using EGS4 Proceedings of the 12th EGS Users Meeting in Japan, 2005
Thyroid carcinoma in a Japanese black cow living in the Fukushima Daiichi nuclear power plant accident contamination area J Sasaki, I Sato, K Okada, Y Deguchi, M Natsuhori, T Murata, H Satoh, ... Bulletin of Environmental Contamination and Toxicology 114 (6), 89 , 2025 2025 Citations: 1
ESR tooth enamel dosimetry of cows exposed by Fukushima Dai-ichi Nuclear Power Plant accident S Toyoda, A Todaka, M Natsuhori, K Okada 2024
Temporal changes in 99mTc-MAG3 renal scintigraphy in feline polycystic kidney disease T Kakizaki, M Natsuhori, S Wada 2024
The effect of exposure on cattle thyroid after the Fukushima Daiichi nuclear power plant accident D Horikami, N Sayama, J Sasaki, H Kusuno, H Matsuzaki, A Hayashi, ... Scientific Reports 12 (1), 21754 , 2022 2022 Citations: 12
External exposure to veterinary staff and pet owners from 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography N Suwannasaeng, T Kakizaki, S Wada, M Natsuhori Radioisotopes 71 (2), 115-126 , 2022 2022 Citations: 2
The Japan health physics society guideline on dose monitoring for the lens of the eye S Yokoyama, N Tsujimura, M Hashimoto, H Yoshitomi, M Kato, ... Journal of Radiation Protection and Research 47 (1), 1-7 , 2022 2022 Citations: 5
Pharmacokinetics of Stable Caesium after Single Administration of Caesium Chloride in Japanese Black Cattle C Shimaoka, T Kakizaki, S Wada, Y Tanaka, T Abe, M Natsuhori Radioisotopes 70 (4), 261-270 , 2021 2021 Citations: 1
External exposure of veterinary staffs and pet owners from feline 99mTc-MAG3 renal scintigraphy N Suwannasaeng, T Kakizaki, S Wada, M Natsuhori Radioisotopes 70 (4), 209-217 , 2021 2021 Citations: 1
L-band electron paramagnetic resonance tooth dosimetry applied to affected cattle teeth in Fukushima I Yamaguchi, K Inoue, M Natsuhori, CAB Gonzales, H Yasuda, Y Nakai, ... Applied Sciences 11 (3), 1187 , 2021 2021 Citations: 11
Assessments of DNA damage and radiation exposure dose in cattle living in the contaminated area caused by the Fukushima nuclear accident I Sato, J Sasaki, H Satoh, M Natsuhori, T Murata, K Okada Bulletin of environmental contamination and toxicology 105 (3), 496-501 , 2020 2020 Citations: 8
ESR assessment of tooth enamel dose from cattle bred in areas contaminated due to the Fukushima Dai-ichi nuclear power plant accident A Todaka, S Toyoda, M Natsuhori, K Okada, I Sato, H Sato, J Sasaki Radiation Measurements 136, 106357 , 2020 2020 Citations: 8
Retrospective ESR reconstruction of cattle tooth enamel doses from the radioactive nuclei released by the accident of Fukushima Dai-ichi atomic power plants S Toyoda, M Murahashi, M Natsuhori, S Ito, A Ivannikov, A Todaka Radiation Protection Dosimetry 186 (1), 48-53 , 2019 2019 Citations: 8
Preliminary study on electron spin resonance dosimetry using affected cattle teeth due to the Fukushima Daiichi Nuclear Power Plant Accident K Inoue, I Yamaguchi, M Natsuhori Low-Dose Radiation Effects on Animals and Ecosystems: Long-Term Study on the … , 2019 2019 Citations: 3
Pathological characteristics of thyroid glands from Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident J Sasaki, M Uehara, I Sato, H Satoh, Y Deguchi, H Chida, M Natsuhori, ... Animal Science Journal 90 (9), 1333-1339 , 2019 2019 Citations: 10
Comparison of urine and blood as a convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium I Sato, J Sasaki, H Satoh, M Natsuhori, T Murata, K Okada Animal Science Journal 90 (8), 1090-1095 , 2019 2019 Citations: 1
Decreased blood cell counts were not observed in cattle living in the “difficult‐to‐return zone” of the Fukushima nuclear accident I Sato, J Sasaki, H Satoh, Y Deguchi, H Chida, M Natsuhori, K Otani, ... Animal Science Journal 90 (1), 128-134 , 2019 2019 Citations: 13
Pathological findings of Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident, 2013–2016 J Sasaki, K Hiratani, I Sato, H Satoh, Y Deguchi, H Chida, M Natsuhori, ... Animal Science Journal 88 (12), 2084-2089 , 2017 2017 Citations: 8
Estimation of bovine internal exposure dose from radiocesium contamination in the Fukushima restricted area by using EGS5 A Motegi, E Kobayashi, H Imai, C Shimaoka, K Mutoh, T Kakizaki, S Wada, ... EGS Users’ Meeting in Japan, 19 , 2017 2017
Whole-body counter evaluation of internal radioactive cesium in dogs and cats exposed to the Fukushima nuclear disaster S Wada, N Ito, M Watanabe, T Kakizaki, M Natsuhori, J Kawamata, ... Plos one 12 (1), e0169365 , 2017 2017 Citations: 10
Radioactive contamination profiles of soil, external and internal exposure to Japanese Black Cattle after Fukushima Daiichi Nuclear Plant Accident. M Natsuhori 2017 Citations: 3
MOST CITED SCHOLAR PUBLICATIONS
The relationship between cellular radiosensitivity and radiation-induced DNA damage measured by the comet assay S Wada, H Kurahayashi, Y Kobayashi, T Funayama, K Yamamoto, ... Journal of veterinary medical science 65 (4), 471-477 , 2003 2003 Citations: 51
Tetrahydrofolic acid as the principal congener of plasma folates in pigs M Natsuhori, M Shimoda, E Kokue, T Hayama, Y Takahashi American Journal of Physiology-Regulatory, Integrative and Comparative … , 1991 1991 Citations: 40
Detection of radiation-induced apoptosis using the comet assay S Wada, T Van Khoa, Y Kobayashi, T Funayama, K Yamamoto, ... Journal of veterinary medical science 65 (11), 1161-1166 , 2003 2003 Citations: 35
Detection of DNA damage in individual cells induced by heavy-ion irradiation with an non-denaturing comet assay S Wada, Y Kobayashi, T Funayama, M Natsuhori, N Ito, K Yamamoto Journal of Radiation Research 43 (Suppl), S153-S156 , 2002 2002 Citations: 26
Hepatic cytochrome P450 induction in goats: effects of model inducers on the metabolism of alkoxyresorufins, testosterone and ethylmorphine, and on apoprotein and mRNA levels GAE Van't Klooster, GJMJ Horbach, M Natsuhori, BJ Blaauboer, ... Biochemical pharmacology 45 (1), 113-122 , 1993 1993 Citations: 25
Kinetic analysis of bovine spleen apoferritin and recombinant H and L chain homopolymers: iron uptake suggests early stage H chain ferroxidase activity and second stage L chain … K Orino, S Harada, M Natsuhori, K Takehara, K Watanabe Biometals 17 (2), 129-134 , 2004 2004 Citations: 23
Features of dual-energy X-ray computed tomography M Torikoshi, T Tsunoo, Y Ohno, M Endo, M Natsuhori, T Kakizaki, N Ito, ... Nuclear Instruments and Methods in Physics Research Section A: Accelerators … , 2005 2005 Citations: 22
Isolation of a bovine full length cytochrome P450 (CYP3A) cDNA sequence and its functional expression in V79 cells M Natsuhori, M van Raak, M Ligtenberg, L Kleij, D ten Berge, ... Environmental toxicology and pharmacology 3 (1), 17-24 , 1997 1997 Citations: 22
Measurement of electron density and effective atomic number using dual-energy x-ray CT T Tsunoo, M Torikoshi, Y Ohno, M Endo, M Natsuhori, T Kakizaki, ... IEEE Symposium Conference Record Nuclear Science 2004. 6, 3764-3768 , 2004 2004 Citations: 21
Role of high-affinity folate-binding protein in the plasma distribution of tetrahydrofolate in pigs K Sasaki, M Natsuhori, M Shimoda, Y Saima, E Kokue American Journal of Physiology-Regulatory, Integrative and Comparative … , 1996 1996 Citations: 19
Two pathways of iron uptake in bovine spleen apoferritin dependent on iron concentration K Orino, S Kamura, M Natsuhori, S Yamamoto, K Watanabe Biometals 15 (1), 59-63 , 2002 2002 Citations: 18
Predicting metastatic potential of gastrointestinal stromal tumors in dog by ultrasonography K Hanazono, S Fukumoto, K Hirayama, K Takashima, Y Yamane, ... Journal of Veterinary Medical Science 74 (11), 1477-1482 , 2012 2012 Citations: 17
Distinct modes of cell death by ionizing radiation observed in two lines of feline T-lymphocytes T Kakizaki, N Hamada, S Wada, T Funayama, T Sakashita, T Hohdatsu, ... Journal of radiation research 47 (3+ 4), 237-243 , 2006 2006 Citations: 14
Decreased blood cell counts were not observed in cattle living in the “difficult‐to‐return zone” of the Fukushima nuclear accident I Sato, J Sasaki, H Satoh, Y Deguchi, H Chida, M Natsuhori, K Otani, ... Animal Science Journal 90 (1), 128-134 , 2019 2019 Citations: 13
The effect of exposure on cattle thyroid after the Fukushima Daiichi nuclear power plant accident D Horikami, N Sayama, J Sasaki, H Kusuno, H Matsuzaki, A Hayashi, ... Scientific Reports 12 (1), 21754 , 2022 2022 Citations: 12
Dual-energy X-ray CT with a vertically expanded irradiation field M Torikoshi, Y Ohno, M Natsuhori, N Ito, K Uesugi, N Yagi, T Tsunoo, ... Nuclear Instruments and Methods in Physics Research Section A: Accelerators … , 2007 2007 Citations: 12
L-band electron paramagnetic resonance tooth dosimetry applied to affected cattle teeth in Fukushima I Yamaguchi, K Inoue, M Natsuhori, CAB Gonzales, H Yasuda, Y Nakai, ... Applied Sciences 11 (3), 1187 , 2021 2021 Citations: 11
Alteration of plasma folates in gestating sows and newborn piglets M Natsuhori, M Shimoda, E Kokue American Journal of Physiology-Regulatory, Integrative and Comparative … , 1996 1996 Citations: 11
Pathological characteristics of thyroid glands from Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident J Sasaki, M Uehara, I Sato, H Satoh, Y Deguchi, H Chida, M Natsuhori, ... Animal Science Journal 90 (9), 1333-1339 , 2019 2019 Citations: 10
Whole-body counter evaluation of internal radioactive cesium in dogs and cats exposed to the Fukushima nuclear disaster S Wada, N Ito, M Watanabe, T Kakizaki, M Natsuhori, J Kawamata, ... Plos one 12 (1), e0169365 , 2017 2017 Citations: 10
