1998 Fiscal Year Final Research Report Summary
Biological Effects of Tritium Radiation Quantitatively Estimated Using Mouse Fetal Cell Damage
| Project/Area Number |
08680539
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear fusion studies
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| Research Institution | Toho University School of Medicine |
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Principal Investigator |
YAMADA Takeshi Toho University School of Medicine, Department of Biology, Professor, 医学部, 教授 (30166714)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Radiation effects / beta-rays / Mice / Fetal development / Role of apoptosis / RBE |
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| Research Abstract |
Effects of beta-radiation from 4 kinds of organically bound tritium compounds (OBTs) including methyl-^3H-thymidine were investigated on cultured mouse embryonic mid brain cells (MBC). The relative biological effectiveness (RBE) values, ranging from 4.6 to 8.7, of beta ray from OBTs were obtained when compared with X-irradiation at their ID5Os (50 % inhibiton dose) on the inhibition of cell proliferation and differentiation, and on the decrease of DNA and protein contents of the cultures. Doses as low as 5 cGy from a mixed exposure resulted in detectable inhibitory effects.
Induction of apoptosis by tritium exposure was investigated in both MBC and brain sections of embryos and of newborns in mice. In the cultures of MBC, addition of methyl-^3H-thymidine (^3H-TdR) (21 kBq ml^<-1>) and tritiated water (HTO) (5.616 MBq ml^<-1>) induced late appearances and low percentages of apoptosis when compared to X-irradiation at the ID50 dose. The pregnant mice were given an intraperitoneal injection of HTO at the concentration of 481.8 kBq g^<-1> of body weight on gestation day 12.5, by which treatment behavioral changes in the offspring occurred. Increased apoptotic cells were observed in the neural tube of embryos from 1 day after the injection to 1 week postnatal age. Apoptosis induced by X-rays appeared 2 h after irradiation, with a peak at 4 h. Increase of apoptotic cells was also found in the brain cortexes of newborns. The percentage of apoptosis in the brain was higher in the prenatal HTO exposed mice than in the prenatal X-irradiated mice. Possible mechanisms on apoptosis and its relation to the higher relative biological effectiveness (RBE) value of tritium beta-rays are discussed.
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[Publications] Hama-Inaba, H., Wang, B., Mori, M., Matsushima, T., Saitoh, T., Takusagawa, M., Yamasa, T., Muto, M.and Ohyama, H.: "Radiosensitive murine thymoma cell line 3SB.Characterization of its apoptosis resistant variants induced by repeated X-irradiation." Mutat.Res.403. 85-94 (1998)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Wang, B., Ohyama, H., Nose, T., Itsukaichi, H., Nakajima, T., Yukawa, O., Odaka, T., Tanaka, K., Kojima, E., Yamada, T., and Hayata, I.: "Radioadaptation in embryogenesis : I.Dose and timing for reducing of prenatal death and congenital malformation during the late period of Organogenesis." Radiat.Res.150. 120-122 (1998)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Wang, B., Fujita, K., Ohhira, C., Watanabe, K., Odaka, T., Mitani, H., Hayata, I., Ohyama, H., Yamada, T.and Shima, A.: "Radiation-Induced Apoptosis Responsible for Limb Teratogenesis of Embryonic Mice." Radiat.Res.151. 63-68 (1999)
Description
「研究成果報告書概要(欧文)」より
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[Publications] Wang, B., Takeda, H., Gao, W., Zhou, X., Odaka, T., Ohyama, H., Yamada, T., Hayata, I.: "Radiation-induced apoptosis in the mid brain cells in embryonic mice." Health Physics. (in press). (1999)
Description
「研究成果報告書概要(欧文)」より
