title: Oxygen toxicity and chromosomal breakage in ataxia telangiectasia.
abstract: Toxic effects of ionizing radiation and elevated O2 levels (hyperoxia) are both thought to be mediated by oxidizing free radicals. In view of the reported hypersensitivity of ataxia telangiectasia (A-T) cells to the clastogenic effect of ionizing radiation, the chromosomal sensitivity of A-T cells to hyperoxic culture conditions was investigated in unirradiated and G0-irradiated A-T lymphocyte cultures. Unlike Fanconi's anaemia lymphocytes, which tend to respond to oxygen, especially after treatment with mitomycin C, both non-irradiated and G0-irradiated A-T lymphocytes failed to show an effect. We conclude that the excessive spontaneous and radiation-induced chromosomal breakage in A-T does not result from a deficiency in the cellular defences against the clastogenic effect of hyperoxia.
mesh_terms: D001260:Ataxia Telangiectasia / Q000235:genetics*; D001761:Bleomycin / Q000633:toxicity; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000187:drug effects*; D004249:DNA Damage; D005609:Free Radicals; D006801:Humans; D009153:Mutagens; D010100:Oxygen / Q000633:toxicity*; D010269:Paraquat; D013308:Streptonigrin / Q000633:toxicity
chemical_list: D005609:Free Radicals; D009153:Mutagens; D001761:Bleomycin; D013308:Streptonigrin; D010269:Paraquat; D010100:Oxygen