@misc{oai:repo.qst.go.jp:00069967,
 author = {加藤, 宝光 and 加藤 宝光},
 month = {Nov},
 note = {We investigate the cell cycle dependent radiosensitivity in heavy charged particles (HCP) irradiated DNA repair deficient CHO cells. Synchronously dividing CHO cells were irradiated at various time points after mitotic shake-off (Sinclair 1969, Bird & Burki 1975). The fact what cell survival is not dependent on cell cycle with high LET irradiation is strong advantage for the particle cancer therapy compared to conventional x-ray.
   In order to study the mechanisms of cell cycle independent biological effects in heavy ion exposure, we used DNA repair deficient mutant CHO cell lines, V3.3 (DNA-PKcs) and 51D1 (Rad51D) to analyze cell survival and chromosome aberrations. Thought WT CHO cells lacked cell cycle independent cell killing, non-homologous repair deficient cell and homologous recombination repair deficient cell showed clear cell cycle effect in their survival. 
   Greater RBE was observed in S-phase cells than in G1-phase cells. RBE of NHEJ repair deficient cells was almost not dependent on LET. HR deficient cells presented higher RBE compared with WT cells. Even G1 of HR deficient cells have higher RBE compared with G1 of WT cells.
   Chromosome analysis revealed HR deficient cells had greater chromatid-type aberrations but similar chromosome-type aberrations after G1 irradiation with greater LET.
   Those results indicate that complex, dirty DNA damages produced by high LET exposure tend not to be an easy target for homologous recombination repair. And this is the reason why cell survival is not dependent on cell cycle with high LET irradiation, 日本放射線影響学会},
 title = {重粒子線によってできる複雑なＤＮＡ損傷修復と相同組み換え修復},
 year = {2009}
}