title: DNA strand breakage in Chinese hamster V79 cells caused by low levels of incorporated [3H] and [14C]thymidine.
abstract: A sensitive alkali-unwinding assay was used to measure DNA strand breakage in Chinese hamster V79 cells caused by low-level incorporation of methyl-labelled [3H] and [14C] thymidine, and to estimate the effective dose per disintegration relative to low doses of gamma-irradiation. Damage equivalent to 0.0035 +/- 0.0006 and 0.0014 +/- 0.0005 Gy was observed for each 3H and 14C disintegration respectively. These values agree well with those expected from the estimated nuclear radiation dose delivered by the beta particles if a relative biological effect (r.b.e.) of 1.0 is assumed, and suggest that strand-breakage produced by these isotopes is determined by the nuclear radiation dose delivered by the beta particles.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes / Q000633:toxicity*; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004307:Dose-Response Relationship, Radiation; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000633:toxicity*
chemical_list: D002250:Carbon Radioisotopes; D014316:Tritium; D004247:DNA; D013936:Thymidine