@misc{oai:repo.qst.go.jp:00069016,
 author = {Tsuruoka, Chizuru and Suzuki, Masao and Furusawa, Yoshiya and Okayasu, Ryuichi and Anzai, Kazunori and 鶴岡 千鶴 and 鈴木 雅雄 and 古澤 佳也 and 岡安 隆一 and 安西 和紀},
 month = {Jul},
 note = {Recent studies showed that the sharp of the LET-RBE curves of various biological effects was different, when using different ion species even if similar LET values. For explaining the LET dependence of biological effects it is necessary to investigate the effects using the same ion species with different LET values. However, the data concerning the LET dependence of biological effects using same ion species is very limited. In this study, we investigated LET and ion-species dependence of biological effects, such as cell-killing effects, mutation induction and chromosome aberration. Normal human fibroblasts were irradiated with heavy ion beams, such as carbon (135 and 290 MeV/n), neon (230 and 400 MeV/n), silicon (490 MeV/n) and iron (500 MeV/n), generated by Heavy Ion Medical Accelerator in Chiba (HIMAC) at National Institute of Radiological Sciences. The LET values were ranging from 13 to 98 keV/micrometer for carbon, from 30 to 184 keV/micrometer for neon, from 55 to 214 keV/micrometer for silicon and from 200 to 400 keV/micrometer for iron ion beams. For a comparison, we used X rays (200kV, 20mA) with 0.5-mm aluminum and 0.5-mm copper filters. Cell-killing effects were detected as a reproductive cell death using a colony formation assay. Mutation induction in HPRT locus was detected to measure 6-tioguanine (6-TG) resistant colonies. The 6-TG resistant colonies were randomly isolated and extracted genomic DNA, and the mutation spectrum of deletion patterns of HPRT exsons was analyzed by multiplex PCR. Chromosome aberration was counted as a fragmentation of prematurely condensed chromosome using a technique of premature chromosome condensation (PCC). To prevent the fast rejoining of PCC breaks, cycloheximide was added in the PCC samples of initially measured breaks during chromatin condensation. The LET-RBE curves of induction of initially measured PCC breaks were not dependent on LETs and ion species. On the other hand, the curves of cell-killing effects, mutation induction and induction of non-rejoining PCC breaks detected after 24h-postirradiation induction were changed, depending on LETs and ion-species. Furthermore, the deletion pattern of exons was different in induced mutants among different ion-species. These results suggest the LET and ion-species dependent biological effects could be affected by repair process of induced chromatin breaks., 13th International Congress of Radiation Research},
 title = {LET and ion-species dependence for cell-killing effect, mutation induction and chromosome aberration in normal human fibroblasts.},
 year = {2007}
}