title: DNA damage, DNA repair and chromosome aberrations of xeroderma pigmentosum cells and controls following exposure to nitrosation products of methylguanidine.
abstract: Nitrosation of methylguanidine (MG) led to products that caused DNA fragmentation  (shift in sedimentation profiles of velocity centrifugation through alkaline sucrose gradients), a DNA repair synthesis (unscheduled uptake of (3H]TdR), chromosome aberrations and a lethal effect of cultured human fibroblasts. The response of repair-deficient xeroderma pigmentosum cells did not differ from that of controls. The nitrosation of MG must be carried out at a pH level below 3, in order to obtain products that react with cellular DNA. The results show that a DNA repair synthesis of human fibroblasts appears to be a sensitive assay for carcinogenic and mutagenic nitrosation products which may be formed within an organism from non-carcinogenic compounds.
mesh_terms: D002478:Cells, Cultured; D002869:Chromosome Aberrations; D004247:DNA / Q000378:metabolism*; D004260:DNA Repair / Q000187:drug effects*; D008760:Methylguanidine / Q000031:analogs & derivatives / Q000494:pharmacology; D009604:Nitrosoguanidines / Q000494:pharmacology*; D014983:Xeroderma Pigmentosum
chemical_list: D009604:Nitrosoguanidines; D008760:Methylguanidine; D004247:DNA