量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Health effects of low-dose-rate or low-dose radiation should be evaluated in combination with chemicals as humans are exposed to a variety of chemical agents. Here, we examined combined genotoxic effects of low-dose-rate radiation and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the most carcinogenic tobacco-specific nitrosamine, in the lung of gpt delta transgenic mice. Female <I>gpt<I> delta transgenic mice were either treated with gamma-irradiation alone at a dose rate of 0.5, 1.0 or 1.5 mGy/h for 22 h/day for 31 days or combined with NNK treatments at a dose of 2 mg/mouse/day, i.p. for four consecutive days in the middle course of irradiation. The NNK treatments enhanced the frequency of base substitutions significantly, but no obvious combined effects of gamma irradiation were observed. In contrast, the NNK treatments appeared to suppress radiation-induced large deletions. The frequency of large deletions more than 1 kb in size increased in a dose-dependent manner of gamma irradiation. When NNK treatments were combined, however, the dose-response curve became bell-shaped where the frequency at the highest radiation dose decreased substantially. These results suggest that NNK treatments may elicit an adaptive response that eliminates cells bearing radiation-induced double-strand breaks in DNA. Possible mechanisms underlying the combined genotoxicity of radiation and NNK are discussed.
会議概要（会議名, 開催地, 会期, 主催者等）
New Nuclear Research Symposium on Biological Response to Low Dose Radiation- New Aspects of Low Dose Radiation Effects
Evaluation of combined genotoxicity of low-dose-rate radiation and tobacco-specific nitrosamine NNK
