MASAHIRO NATSUHORI

Verified email at gmail.com

Veterinary medicine
Kitasato University



                                                           

https://researchid.co/masahiro

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

RESEARCH INTERESTS

Radiology, Diagnostic imaging, Radiation therapy, Environmental radiology, Pharmacokinetics

43

Scopus Publications

415

Scholar Citations

12

Scholar h-index

15

Scholar i10-index

Scopus Publications

  • 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, Tadahiro Kurosawa, Hideo Tatsuzaki, Hiroshi Sekiguchi, Yasuhiro Koguchi, Koji Ono, Masahumi Akiyoshi, Naoki Kunugita, Masahiro Natsuhori, Yoshinori Natsume, Kuniaki Nabatame, Tsunenori Kawashima, Shunji Takagi, Kazuko Ohno, and Satoshi Iwai

    Journal of Radiation Protection and Research, ISSN: 25081888, eISSN: 24662461, Pages: 1-7, Published: 1 March 2022 Korean Association for Radiation Protection
    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, Yasuhiro Nakai, Minoru Miyake, and Harold M. Swartz

    Applied Sciences (Switzerland), eISSN: 20763417, Pages: 1-7, Published: 1 February 2021 MDPI AG
    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.

  • Radiological protection of the patient in veterinary medicine and the role of ICRP
    R.J. Pentreath, K.E. Applegate, K.A. Higley, K. Peremans, M. Natsuhori, E. Randall, and J. Gambino

    Annals of the ICRP, ISSN: 01466453, eISSN: 1872969X, Issue: 1_suppl, Pages: 169-181, Published: December 2020 SAGE Publications
    At the request of the Main Commission of the International Commission on Radiological Protection (ICRP), Task Group 107 (TG107) was set up to consider the issue of radiological protection of the patient in veterinary medicine. TG107, who authored this article, brought together information relating to the use of diagnostic imaging and radiation oncology in veterinary medicine. A number of specific areas were identified that appeared to be appropriate for attention by ICRP. These included the use of dose quantities and units, the need for re-evaluation of stochastic and deterministic risks from ionising radiation in animals, and the growing use of imaging and therapeutic equipment for animals that is little different from that available to humans. TG107 unanimously recommended that it was both appropriate and timely for ICRP to consider and advise on these issues, and the Main Commission agreed. This paper summarises the findings of TG107.

  • 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, and Keiji Okada

    Bulletin of Environmental Contamination and Toxicology, ISSN: 00074861, eISSN: 14320800, Volume: 105, Pages: 496-501, Published: 1 September 2020 Springer Science and Business Media LLC
    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, Hiroshi Sato, and Jun Sasaki

    Radiation Measurements, ISSN: 13504487, Volume: 136, Published: August 2020 Elsevier BV
    Abstract 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, and Azumi Todaka

    Radiation Protection Dosimetry, ISSN: 01448420, eISSN: 17423406, Volume: 186, Pages: 48-53, Published: 31 December 2019 Oxford University Press (OUP)
    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, Hiroyuki Chida, Masahiro Natsuhori, Takahisa Murata, Kenji Ochiai, Kumiko Otani, Keiji Okada, and Nobuhiko Ito

    Animal Science Journal, ISSN: 13443941, eISSN: 17400929, Pages: 1333-1339, Published: 1 September 2019 Wiley
    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, and Keiji Okada

    Animal Science Journal, ISSN: 13443941, eISSN: 17400929, Pages: 1090-1095, Published: 2019 Wiley
    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.

  • Decreased blood cell counts were not observed in cattle living in the “difficult-to-return zone” of the Fukushima nuclear accident
    Itaru Sato, Jun Sasaki, Hiroshi Satoh, Yoshitaka Deguchi, Hiroyuki Chida, Masahiro Natsuhori, Kumiko Otani, and Keiji Okada

    Animal Science Journal, ISSN: 13443941, eISSN: 17400929, Pages: 128-134, Published: January 2019 Wiley
    Abstract White blood cells, especially lymphocytes, are susceptible to radiation exposure. In the present study, red blood cell, total white blood cell, and lymphocyte counts were repeatedly measured in cattle living on three farms located in the “difficult‐to‐return zone” of the Fukushima nuclear accident, and compared with two control groups from unaffected areas. Blood cell counts differed significantly between the two control groups, although almost all the values fell within the normal range. The blood cell counts of the cattle in the “difficult‐to‐return zone” varied across sampling times even on the same farms, being sometimes higher or lower than either of the two control groups. However, neither a statistically significant decrease in blood cell counts nor an increase in the rate of cattle with extremely low blood cell counts was observed overall. The estimated cumulative exposure dose for the cattle on the most contaminated farm was within a range of 500–1000 mSv, exceeding the threshold for the lymphopenia. Because of the low dose rate on these farms, potential radiation damages would have been repaired and have not accumulated enough to cause deterministic effects.

  • Pathological findings of Japanese Black Cattle living in the restricted area of the Fukushima Daiichi Nuclear Power Plant accident, 2013–2016
    Jun Sasaki, Kayoko Hiratani, Itaru Sato, Hiroshi Satoh, Yoshitaka Deguchi, Hiroyuki Chida, Masahiro Natsuhori, Takahisa Murata, Kenji Ochiai, Kumiko Otani, Keiji Okada, and Nobuhiko Ito

    Animal Science Journal, ISSN: 13443941, eISSN: 17400929, Pages: 2084-2089, Published: December 2017 Wiley
    Fifty-one Japanese black cattle from four farms in the evacuation zone of the Fukushima nuclear accident were examined pathologically during the period, 2013-2016. We found no evidence of a radiation effect on pathological findings in any of these autopsy cases, although nine cases (3.7%) of enzootic bovine leukosis (EBL) and three cases (1.2%) of goiter were diagnosed. Estimated integrating dose of external exposure in EBL cases ranged from a maximum of 1200 mSv to a minimum of 72 mSv. Clinically, five cases showed wobble, dysstasia or paralysis. Exophthalmos was observed in three cases. Macroscopically, enlarged lymph nodes, multiple irregular masses of intra-abdominal and intrapelvic adipose tissue, diffuse thickening of the abomasal submucosa with ulceration, and numerous white nodules of myocardium were observed. Histologically, neoplastic lymphoid cells were extensively proliferated and infiltrated in the lesions. Lymphoid tumor cells showed mature or large lymphoblastic appearance. Immunohistochemically, tumor cells were positive for BLA-36, CD20 and CD5, and negative for CD3. Three cases showed diffuse enlargement of the thyroid gland with no mass or nodule lesion. Histologically, diffuse proliferation of follicular epithelium was observed with preservation of normal structures. There were no malignant findings such as cellular atypia or invasion to capsule.

  • 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, Pages: 19-20, Published: 1 July 2017

  • Whole-body counter evaluation of internal radioactive cesium in dogs and cats exposed to the fukushima nuclear disaster
    Seiichi Wada, Nobuhiko Ito, Masamichi Watanabe, Takehiko Kakizaki, Masahiro Natsuhori, Jun Kawamata, and Yoshio Urayama

    PLoS ONE, eISSN: 19326203, Published: January 2017 Public Library of Science (PLoS)
    As a result of the 2011 nuclear incident that occurred at the Fukushima Nuclear Power Plant, a large number of abandoned dogs and cats were left within the disaster zone. A small number of these animals were rescued and cared for at shelters. Prior to the dispersal of these animals to their owners or fosterers, we evaluated the degree of internal radiocesium contamination using a specially designed whole-body counter. We conducted 863 non-invasive measurements of gamma rays due to internal radioactive cesium for 68 dogs and 120 cats at one shelter. After plotting graphs of 137Cs density we generated exponential functions of decay from seven dogs and six cats. From the regression formulae, we were able to determine the biological half-lives as 38.2 days for dogs and 30.8 days for cats. We found that in dogs there was a correlation between the biological half-life of radioactive cesium and age. Using our data, we estimated whole-body densities for each cat and dog at the time when they were rescued. We found that there were deviations in the data distributions among the different species, likely due to the timing of rescue, or living habits prior to rescue. A significant correlation was found when extracted feline reproductive organs were analyzed; the coefficients for the estimation of whole-body densities were approximately 7-fold higher than those based on the extracted feline reproductive organs. This may be due to the fact that majority of the radioactive cesium accumulates within muscular tissue with less distribution in other organs. It is possible to plan the appropriate management period in an animal shelter based on the use of the biological half-life of radioactive cesium calculated in this study. We believe that the correlations we uncovered in this work would be of great use for the management of companion animals in the event of a future nuclear accident.

  • Local variation of soil contamination with radioactive cesium at a farm in Fukushima
    Japanese Journal of Veterinary Research, ISSN: 00471917, Pages: 95-99, Published: 2016

  • Predicting metastatic potential of gastrointestinal stromal tumors in dog by ultrasonography
    Kiwamu HANAZONO, Shinya FUKUMOTO, Kazuko HIRAYAMA, Kazuaki TAKASHIMA, Yoshihisa YAMANE, Masahiro NATSUHORI, Tsuyoshi KADOSAWA, and Tsuyoshi UCHIDE

    Journal of Veterinary Medical Science, ISSN: 09167250, eISSN: 13477439, Pages: 1477-1482, Published: 2012 Japanese Society of Veterinary Science
    Gastrointestinal stromal tumor (GIST), a mesenchymal neoplasm affecting the gastrointestinal tract, shows a variety of clinical behaviors from inactive benign to aggressive malignant in dogs. In this study, the feasibility of using clinically significant ultrasonographic features to predict the metastatic potential of canine GIST was investigated through comparison with actual metastatic incidence and findings of malignancy obtained by postoperative pathological examination. Ultrasonographic features, including large tumor size, irregular margin and heterogeneous internal echogenicity with large hypoechoic areas, related closely with the presence of metastasis as well as a high-risk ranking by the human classification system according to pathological findings. Based on these ultrasonographic features, the potential of metastasis in canine GIST could be preoperatively predicted.

  • Evaluation of external radiation exposure of human involved in equine bone scintigraphy (no.2)
    Proceedings of the 14th EGS Users' Meeting in Japan, Pages: 137-141, Published: 2007

  • Dual-energy X-ray CT with a vertically expanded irradiation field
    Masami Torikoshi, Yumiko Ohno, Masahiro Natsuhori, Nobuhiko Ito, Kentaro Uesugi, Naoto Yagi, Takanori Tsunoo, Meng De, and Masahiro Endo

    Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN: 01689002, Volume: 580, Pages: 996-999, Published: 1 October 2007 Elsevier BV
    Abstract Dual energy X-ray CT was carried out with synchrotron radiation at BL20B2 beam line of JASRI/SPring-8. The X-ray beams were vertically magnified by employing an asymmetry Bragg reflection geometry. The field size was about 25 mm×250 mm at the end of the beam line. Porcine eyes and brain and water were used as samples. The DXCT provided the highly accurate information on an electron density; the electron density of water was in agreement of about 0.6% with the theoretical value. Images of the electron density and an effective atomic number had good quality sufficient for medical applications.

  • Vulnerability of feline T-lymphocytes to charged particles
    Takehiko KAKIZAKI, Nobuyuki HAMADA, Tetsuya SAKASHITA, Seiichi WADA, Takamitsu HARA, Tomoo FUNAYAMA, Tsutomu HOHDATSU, Masahiro NATSUHORI, Tadashi SANO, Yasuhiko KOBAYASHI, and Nobuhiko ITO

    Journal of Veterinary Medical Science, ISSN: 09167250, eISSN: 13477439, Pages: 605-609, Published: June 2007 Japanese Society of Veterinary Science
    An analysis of ionizing radiation-induced damage in peripheral lymphocytes has been employed to predict the prognosis of radiotherapy in terms of toxicity in normal tissues. Therefore, understanding the sensitivity of lymphocytes to high linear energy transfer (LET)-charged particles would be indispensable for utilizing charged particle therapy in veterinary medicine. However, the availability of such information is very limited. This study aimed to compare the radiosensitivity of feline T lymphocytes to gamma-rays (0.2 keV/microm) and 4 different types of charged particles with LET values ranging from 2.8 to 114 keV/microm. It was observed that the relative biological effectiveness, inactivation cross-section, and isodose-induced apoptosis increased in an LET-dependent manner. On the other hand, no difference in apoptosis frequency was observed in the cells exposed to an isosurvival dose of all the radiation types tested. This is the first study that demonstrates the LET dependence of cell killing and apoptosis induction in feline T lymphocytes. Our results suggest that lymphocytes can be effectively used to predict the prognosis of charged-particle therapy in cat patients.

  • Killing of feline T-lymphocytes by gamma-rays and energetic carbon ions
    Takehiko KAKIZAKI, Nobuyuki HAMADA, Tomoo FUNAYAMA, Tetsuya SAKASHITA, Seiichi WADA, Tsutomu HOHDATSU, Masahiro NATSUHORI, Tadashi SANO, Yasuhiko KOBAYASHI, and Nobuhiko ITO

    Journal of Veterinary Medical Science, ISSN: 09167250, eISSN: 13477439, Pages: 1269-1273, Published: December 2006 Japanese Society of Veterinary Science
    High linear energy transfer (LET) heavy charged particles have previously been applied clinically to human cancer radiotherapy because of their excellent physical properties of selective dose distribution and higher relative biological effectiveness (RBE) for human; however, such an approach has yet to be applied to cat patients. The present study investigates the biological effectiveness of low-LET gamma-rays (0.2 keV/micro m) compared to high-LET carbon ions (114 keV/micro m) in feline T- lymphocyte FeT-J cells. Clonogenic survival analysis revealed that the RBE value of carbon ions was 2.98 relative to a 10% survival dose (D(10)) by gamma-rays, and that the inactivation cross-section in cells exposed to gamma-rays and carbon ions was 0.023 and 38.9 micro m(2), respectively. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) analysis revealed that TUNEL-positive frequency in carbon-irradiation cells is higher than for gamma-irradiated cells against exposure to the same physical doses, but that very little difference in TUNEL-positive frequency is observed between cells exposed to the respective D(10) dose of gamma-rays. Our data thus indicate that carbon ions are more effective for cell killing than gamma-rays at the same physical doses, but kill cells to an extent that is comparable to gamma-rays at the same biological doses. Carbon ion radiotherapy is therefore a promising modality for cat patients.

  • Probenecid: Its chromatographic determination, plasma protein binding, and in vivo pharmacokinetics in dogs
    Takehiko KAKIZAKI, Yukiko YOKOYAMA, Masahiro NATSUHORI, Azusa KARASAWA, Satoshi KUBO, Naoaki YAMADA, and Nobuhiko ITO

    Journal of Veterinary Medical Science, ISSN: 09167250, eISSN: 13477439, Pages: 361-365, Published: April 2006 Japanese Society of Veterinary Science
    Pharmacokinetics (PK) of probenecid including plasma probenecid concentrations, in vitro plasma protein binding properties, and in vivo PK parameters were determined in dogs. Probenecid concentrations were best determined by HPLC, which showed good linearity and good recovery with simple plasma preparation. The quantification limit of probenecid was approximately 50 ng/ml at S/N ratio = 3, by simple procedure with HCl and methanol treatment. Probenecid showed two types of binding characteristics, i.e., high-affinity with low-capacity and low-affinity with high-capacity binding. This result indicated 80-88% of probenecid was bound to plasma protein(s) at observed concentrations (< 80 microg/ml) in vivo at an intravenous dose of 20 mg/kg. Plasma probenecid concentration-time profile following i.v. administration in dogs showed biphasic decline and well fitted a two-compartment open model. The total body clearance was 0.34 +/- 0.04 ml/min/kg, volume of distribution at steady-state was 0.46 +/- 0.07 l/kg, elimination half-life was 18 +/- 6 hr, and mean residence time (MRT) was 23 +/- 6 hr. Since probenecid has been known as a potent inhibitor of renal tubular excretion of acidic drugs and highly binds to plasma proteins, our observation in relation to plasma protein binding and PK parameters will serve as the basic information concerning drug-drug interactions in dogs and in other mammalian species.


  • Distinct modes of cell death by ionizing radiation observed in two lines of feline T-lymphocytes
    Takehiko KAKIZAKI, Nobuyuki HAMADA, Seiichi WADA, Tomoo FUNAYAMA, Tetsuya SAKASHITA, Tsutomu HOHDATSU, Tadashi SANO, Masahiro NATSUHORI, Yasuhiko KOBAYASHI, and Nobuhiko ITO

    Journal of Radiation Research, ISSN: 04493060, eISSN: 13499157, Issue: 3-4, Pages: 237-243, Published: 2006 Oxford University Press (OUP)
    We have examined in vitro radiosensitivities and radioresponses to (60)Co gamma-rays irradiation in feline T-lymphocyte cell lines, FeT-J and FL-4. There seemed to be no significant difference in clonogenic survival between the two lines. The mean lethal dose for both was both 1.9 Gy, and surviving fraction at 2 Gy was 0.30 and 0.48 for FeT-J and FL-4 cells, respectively. However, TUNEL assay indicated much higher degrees of apoptosis induction in FeT-J cells (>40%) than in FL-4 cells (<10%) at 4 days after 15 Gy irradiation. Microscopic examination revealed a larger population of multi-nucleate cells in FL-4 cells (60.3%) than in FeT-J cells (16.0%) at 4 days after 15 Gy irradiation, suggesting that a larger ratio of mitotic catastrophe occurred in FL-4 cells. These results suggest that FeT-J is more likely to be induced into apoptosis and FL-4 is more likely to fall into mitotic catastrophe, and eventually necrosis; both of them showed a similar surviving fraction against gamma-rays. The results also indicate that FL-4 cells follow a process other than apoptosis to cell death, suggesting the presence of a regulatory mechanism that may control the relationship between mitotic catastrophe and apoptosis in feline T-lymphocytes.

  • Evaluation of external radiation dose of humans involved in veterinary nuclear medicine by using EGS4
    Proceedings of the 12th EGS Users' Meeting in Japan, Pages: 39-45, Published: 2005

  • Quantitative analysis of the effect of probenecid on pharmacokinetics of <sup>99m</sup>Tc-mercaptoacetyltriglycine in dogs
    T. KAKIZAKI, Y. YOKOYAMA, M. NATSUHORI, N. YAMADA, M. HASHIMOTO, K. SATO, N. ITO, and G. B. DANIEL

    Journal of Veterinary Pharmacology and Therapeutics, ISSN: 01407783, eISSN: 13652885, Pages: 559-564, Published: December 2005 Wiley
    Effect of probenecid on pharmacokinetics of 99mTc-mercaptoacetylytriglycine (99mTc-MAG3) in dogs was investigated before (control), and after 15 min and 24 h of i.v. injection of probenecid (20 mg/kg). Plasma concentration-time profiles of 99mTc-MAG3 were described with a two-compartment open model. Plasma 99mTc-MAG3 clearances (Clp, ml/min/kg) were 7.9 +/- 0.5, 3.3 +/- 0.5 and 4.8 +/- 1.3 in control, 15 min and 24 h after probenecid administration respectively. Similarly, the biological half-lives at elimination phase (t(1/2), h) were 0.61 +/- 0.09, 0.79 +/- 0.11 and 0.74 +/- 0.12, and volumes of distribution at steady state (Vdss, L/kg) were 0.29 +/- 0.04, 0.20 +/- 0.05 and 0.25 +/- 0.06 respectively. The prolonged biological half-life and decreased Vdss decreased Clp significantly. Clp was a function of plasma probenecid concentration based on Michaelis-Menten kinetics. The maximum Clp inhibition (Imax) by probenecid and the plasma probenecid concentration that induced 50% of Imax (I50) were estimated to be 72 +/- 12% and 13 +/- 8 microg/ml respectively. This means that the rest (about 28%) of the Clp is not blocked by probenecid alone, suggesting the possibility of another route(s) of elimination or renal transporters which are independent from probenecid. Moreover, inter-species correlation between Clp of 99mTc-MAG3 and body weight are discussed.

  • Features of dual-energy X-ray computed tomography
    M. Torikoshi, T. Tsunoo, Y. Ohno, M. Endo, M. Natsuhori, T. Kakizaki, N. Ito, K. Uesugi, and N. Yagi

    Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN: 01689002, Volume: 548, Issue: 1-2, Pages: 99-105, Published: 11 August 2005 Elsevier BV
    We proposed dual-energy X-ray CT for direct measurement of electron densities to make treatment planning for heavy ion radiotherapy more accurate. The accuracy was proved to be about 1% using synchrotron radiation in previous experiments carried out at SPring-8 and PF-AR. The electron densities of some porcine organs were measured in this method at SPring-8, and compared with data of ICRU Report. Besides, the atomic number of the object is also obtained as a byproduct. Comparing the CT-number given in conventional CT scanning is an important information. Images of the electron density and atomic number may give new information to medical diagnosis.

  • Study on dual-energy X-ray computed tomography using synchrotron radiation
    T. Tsunoo

    AIP Conference Proceedings, ISSN: 0094243X, eISSN: 15517616, Volume: 705, Pages: 1368-1371, Published: 12 May 2004 AIP
    The electron density is one of the most important elements for the treatment planning in the radiotherapy, because this information is used for the range estimation of the heavy‐ion beam. In order to measure more precise electron density, we have developed the dual‐energy x‐ray CT system using synchrotron radiation. The x‐ray detector consists of 256 × 96 scintillator‐array. It can take more than a hundred projection images per second. The response of the detector to x‐rays was proved to be linear up to at least 1013 photon/pixel. The experiments were carried out using two monochromatic x‐rays of 40 keV and 70 keV at the beam‐line BL20B2 of SPring‐8. As the results from samples of water, ethanol and solutions of dipotassium hydrogenphosphate with five concentrations, the electron densities measured in the dual‐energy x‐ray CT method were in agreement with the theoretical values by about ± 1%. This is almost the same level as that achieved by the one‐dimensional CT system we developed previously. In additi...

RECENT SCHOLAR PUBLICATIONS

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  • 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

  • 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

  • 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

  • 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

  • Preliminary Study on Electron Spin Resonance Dosimetry Using Affected Cattle Teeth Due to the Fukushima Daiichi Nuclear Power Plant Accident BT
    K Inoue, I Yamaguchi, M Natsuhori
    Low-Dose Radiation Effects on Animals and Ecosystems: Long-Term Study on the 2020

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • Local variation of soil contamination with radioactive cesium at a farm in Fukushima
    I Sato, M Natsuhori, J Sasaki, H Satoh, T Murata, T Nakamura, K Otani, ...
    Japanese Journal of Veterinary Research 64 (1), 95-99 2016

  • Pharmacokinetics and whole body distribution profile of 18F-fluorodeoxyglucose (FDG) by PET-CT in dogs
    M Natsuhori, M Shimoyama, T Bandai, M Fukuda, K Ono, H Ogawa, ...
    JOURNAL OF VETERINARY PHARMACOLOGY AND THERAPEUTICS 35, 173-174 2012

  • 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

  • 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

  • Vulnerability of feline T-lymphocytes to charged particles
    T Kakizaki, N Hamada, T Sakashita, S Wada, T Hara, T Funayama, ...
    Journal of veterinary medical science 69 (6), 605-609 2007

  • Biological Effects after Prenatal Irradiation (Embryo and Fetus) Biological Effects after Prenatal Irradiation (Embryo and Fetus), 2003
    C Streffer, N HAMADA, S WADA, T FUNAYAMA, T SAKASHITA, ...
    Journal of radiation research 47 (3), 237-243 2006

  • Hereditary Effects of Radiation Hereditary Effects of Radiation, 2001
    C Streffer, N HAMADA, S WADA, T FUNAYAMA, T SAKASHITA, ...
    Journal of radiation research 47 (3), 237-243 2006

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
    Citations: 48

  • 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
    Citations: 36

  • 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
    Citations: 33

  • 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
    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
    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
    Citations: 21

  • 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
    Citations: 21

  • 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
    Citations: 20

  • 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
    Citations: 18

  • 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
    Citations: 16

  • 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
    Citations: 14

  • 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, 0609010002-0609010002 2006
    Citations: 13

  • 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
    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
    Citations: 11

  • 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
    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
    Citations: 9

  • Clearance rates of biotinylated ferritins in canine: A possible physiological role of canine serum ferritin as an iron transporter
    K Orino, A Terada, A Yoshida, S Okano, S Higuchi, M Natsuhori, ...
    Biometals 16 (2), 341-347 2003
    Citations: 8

  • Nuclear Science Symposium Conference Record
    TTM Torikoshi, Y Ohno, M Endo, M Natsuhori, T Kakizaki, N Yamada, ...
    IEEE 6, 3764-3768 2004
    Citations: 7

  • Metabolism of antipyrine and sulphadimidine in dwarf goats: effects of the enzyme-inducing agents phenobarbital, troleandomycin and rifampicin
    M Natsuhori, RF Witkamp, GAE Van'T Klooster, A Van Miert
    Xenobiotica 22 (11), 1243-1250 1992
    Citations: 6

  • 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
    Citations: 5