@article{oai:repo.qst.go.jp:00044876,
 author = {Okada, Maki and Okabe, Atsushi and Uchihori, Yukio and Kitamura, Hisashi and Sekine, Emiko and Ebisawa, Satoru and Suzuki, Masao and Okayasu, Ryuichi and 岡田 真希 and 岡部 篤史 and 内堀 幸夫 and 北村 尚 and 関根 絵美子 and 海老澤 悟 and 鈴木 雅雄 and 岡安 隆一},
 issue = {11},
 journal = {British Journal of Cancer},
 month = {Jun},
 note = {To investigate the long term biological effect of extreme low dose ionizing radiation (IR), we irradiated normal human fibroblasts (HFL III) with carbon ions (290 MeV/u, 70 keV/µm) and gamma-rays at 1 mGy (total dose) once at a low dose rate (1 mGy/6-8 h), and observed the cell growth kinetics up to five months by continuous culturing. The growth of carbon irradiated cells started to slow down considerably sooner than that of non-irradiated cells before reaching senescence. In contrast, cells irradiated with gamma-rays under similar conditions did not show significant deviation from the non-irradiated cells. A DNA double strand break (DSB) marker, gammaH2AX foci and a DSB repair marker, phosphorylated DNA-PKcs foci, increased in number when non-irradiated cells reached several passages before senescence. A single low dose/low dose rate carbon ion exposure further raised the numbers of these markers. Furthermore, the numbers of foci for these two markers were significantly reduced after the cells became fully senescent. Our results indicate that high linear energy transfer (LET) radiation (carbon ions) causes different effects than low LET radiation (gamma-rays) even at very low doses and that a single low dose of heavy ion irradiation can affect the stability of the genome many generations after irradiation.},
 pages = {1707--1710},
 title = {Single extreme low dose/low dose rate irradiation causes alteration in lifespan and genome instability in primary human cells},
 volume = {96},
 year = {2007}
}