title: Induction of DNA DSB and its rejoining in clamped and non-clamped tumours after exposure to carbon ion beams in comparison to X rays.
abstract: We studied double-strand breaks (DSB) induction and rejoining in clamped and non-clamped transplanted tumours in mice leg after exposure to 80 keV µm(-1) carbon ions and X rays. The yields of DSB in the tumours were analysed by a static-field gel electrophoresis. The OER of DSB after X rays was 1.68±0.31, and this value was not changed after 1 h rejoining time (1.40±0.26). These damages in oxygenated conditions were rejoined 60-70% within 1 h in situ. No difference was found between the exposure to X rays and carbon ions for the induction and rejoining of DSB. Thus, the values of OER and rejoined fraction after exposure to carbon ions were similar to those after X rays, and the calculated relative biological effectivenesses of carbon ion were around 1 under both oxygen conditions. The yields of DSB in vivo depend on exposure doses, oxygen conditions and rejoining time, but not on the types of radiation quality.
authors.affiliation: Heavy-ion Radiobiology Research Group, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Hirayama
authors.forename: A
authors.initials: A
authors.lastname: Uzawa
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: M
authors.initials: M
authors.lastname: Noguchi
authors.forename: Y
authors.initials: Y
authors.lastname: Kase
authors.forename: N
authors.initials: N
authors.lastname: Takase
authors.forename: A
authors.initials: A
authors.lastname: Ito
authors.forename: S
authors.initials: S
authors.lastname: Koike
authors.forename: K
authors.initials: K
authors.lastname: Ando
authors.forename: R
authors.initials: R
authors.lastname: Okayasu
authors.forename: Y
authors.initials: Y
authors.lastname: Furusawa
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D002294:Carcinoma, Squamous Cell / Q000503:physiopathology*; D045744:Cell Line, Tumor; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000235:genetics* / Q000528:radiation effects*; D020450:Heavy Ions; D008297:Male; D051379:Mice; D010100:Oxygen / Q000378:metabolism*; D014965:X-Rays
chemical_list: D002247:Carbon Isotopes; D004273:DNA, Neoplasm; D010100:Oxygen