@article{oai:repo.qst.go.jp:00045115,
 author = {Sekine, Emiko and Okada, Maki and Matsufuji, Naruhiro and Yu, Dong and Furusawa, Yoshiya and Okayasu, Ryuichi and 関根 絵美子 and 岡田 真希 and 松藤 成弘 and 于 冬 and 古澤 佳也 and 岡安 隆一},
 issue = {1},
 journal = {Genetic Toxicology and Environmental Mutagenesis : A Section of Mutation Research},
 month = {Mar},
 note = {We investigated the earliest possible chromosome break and repair process in
normal human fibroblasts irradiated with low and high LET (linear energy
transfer) heavy ion radiation using the modified premature chromosome
condensation (PCC) technique utilizing wortmannin (WM) during the fusion
incubation period (Okada et al Mutat. Res 2004). The initial numbers of
breaks were approximately 10 per cell per Gy in x-irradiated samples,
followed by carbon (LET: 70keV/um), neon, and the number was around 5 per
cell per Gy in silicon (LET: 70 and 200keV/um) and iron (LET: 200keV/um)
samples. If WM was not used, the initial numbers of breaks with silicon and
iron were higher than those of X-rays. To quantify these data, we used
initial repair ratio (IRR) defined as the number of G1 PCC breaks with WM
divided by the number of breaks without WM. X-irradiation gave the maximum
IRR (~ 2.0 ), while iron as well as silicon irradiation showed the minimum
IRR (~1.0), suggesting almost no rejoining at the initial stage. Although
there is a comparatively good correlation between the IRR value and the cell
survival, the survival fraction with the repair data at 2h or 6 h correlates
better statistically. Our data indicate that high LET heavy ion irradiation
induces a lower number of initial chromosome breaks with minimal repair when
compared with low LET irradiation. These results at the chromosome level
substantiate and extend the notion that high LET radiation produces complex
type DNA double strand breaks (DSBs).},
 pages = {95--101},
 title = {High LET heavy ion radiation induces lower numbers of initial chromosome breaks with minimal repair than low LET radiation in normal human cells},
 volume = {652},
 year = {2008}
}