title: The influence of multiple mutagenic treatments on the occurrence of 6-thioguanine-resistant mutants in dividing V79 cells.
abstract: Repeated treatments of dividing Chinese hamster V79 cells with ultraviolet radiation or a simple monofunctional alkylating agent (methyl methanesulphonate, N-methyl-N'-nitro-N-nitrosoguanidine or N-methyl-N-nitrosourea) were studied with regard to the pattern of cumulative increase of 6-thioguanine-resistant mutants in the surviving population. There were 5-10 divisions of surviving cells between two successive treatments. Repeated treatments with different agents produced different effects. The observed results indicating either a higher or lower than additive effect of single doses may be explained by induced repair processes.
mesh_terms: D000818:Animals; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D006224:Cricetinae; D004334:Drug Administration Schedule; D004351:Drug Resistance; D008168:Lung; D008647:Mesocricetus; D008741:Methyl Methanesulfonate / Q000008:administration & dosage; D008769:Methylnitronitrosoguanidine / Q000008:administration & dosage; D008770:Methylnitrosourea / Q000008:administration & dosage; D009153:Mutagens / Q000008:administration & dosage*; D009154:Mutation / Q000187:drug effects / Q000528:radiation effects; D013866:Thioguanine / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D009153:Mutagens; D008769:Methylnitronitrosoguanidine; D008770:Methylnitrosourea; D008741:Methyl Methanesulfonate; D013866:Thioguanine