@misc{oai:repo.qst.go.jp:00062520,
 author = {Ikeda, Megumi and Masumura, Kenichi and Sakamoto, Yasuteru and Bing, Wang and Nenoi, Mitsuru and Sakuma, Keiko and Hayata, Isamu and Nohmi, Takehiko and 池田 恵 and 増村 健一 and 坂元 康晃 and 王 冰 and 根井 充 and 早田 勇 and 能美 健彦},
 month = {Nov},
 note = {It is important to evaluate the health effects of low-dose-rate or low-dose radiation 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. In this mouse model, base substitutions and deletions can be separately analyzed by gpt and Spi- selections, respectively. Female gpt delta mice were treated either 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 its combination with NNK at a dose of 2 mg/mouse/day, i.p. for four consecutive days in the middle course of irradiation. In the gpt selection, the NNK treatments enhanced the mutation frequencies (MFs) significantly, but no obvious combined effects of gamma-irradiation were observable at any given radiation dose. In contrast, NNK treatments appeared to suppress the Spi- large deletions. In the Spi- selection, the MFs of deletions more than 1 kb in size increased in a dose-dependent manner. When NNK treatments were combined, the dose-response curve became bell-shaped where the MF 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 (DSBs) in DNA., New Nuclear Research Symposium "Biological Responses to Low Dose Radiation"},
 title = {Suppression of radiation-induced large deletions by combined treatments with a tobacco-specific nitrosamine in the lung of gpt delta transgenic mice},
 year = {2007}
}