@article{oai:repo.qst.go.jp:00044561,
 author = {Zhou, Guangming and Kawata, Tetsuya and Furusawa, Yoshiya and Aoki, Mizuho and Hirayama, Ryoichi and Ando, Koichi and Ito, Hisao and 周 光明 and 川田 哲也 and 古澤 佳也 and 青木 瑞穂 and 平山 亮一 and 安藤 興一 and 伊東 久夫},
 issue = {2},
 journal = {Journal of Radiation Research},
 month = {Jun},
 note = {To investigate the protective effects of melatonin against high-LET ionizing radiation, V79 Chinese hamster cells were irradiated with 100 keV/um carbon beam. Parallel experiments were performed with 200 kV X-rays. To avoid the impact from extra solvents, melatonin was dissolved directly in culture medium. Cells were cultured in melatonin medium for 1 hr before irradiation. Cell inactivation was measured with conventional colony forming assay, medium containing 6-thioguanine was used for the selection of mutants at hprt locus, and the cell cycle was monitored by flow cytometry. Both carbon beam and X-rays induced cell inactivation, hprt gene mutation and cell cycle G2 block dose-dependently. But carbon beam showed stronger effects as indicated by all three endpoints and the relative biological effectiveness (RBE) was 3.5 for cell killing (at 10% survival level) and 2.9 for mutation induction (at 5x10^-5 mutants/cell level). Melatonin showed protective effects against ionizing radiation in a dose-dependent manner. In terms of cell killing, melatonin only increased the survival level of those samples exposed to 8Gy or larger of X-rays or 6 Gy or larger of carbon beam. In the induction of hprt mutation and G2 block, melatonin reduced such effects induced by carbon beam but not by X-rays. The results suggest that melatonin reduces the direct interaction of particles with cells rather than an indirect interaction. Further studies are required to disclose the underlying mechanisms.},
 pages = {175--181},
 title = {Protective Effects of Melatonin Against Low- and High-LET Irradiation},
 volume = {47},
 year = {2006}
}