title: A simple modification of the Salmonella liquid-incubation assay. Increased sensitivity for detecting mutagens in human urine.
abstract: A simple modification of the Salmonella/microsome liquid-incubation procedure improves the sensitivity of the assay for detecting mutagens in human urine. Extracts from cigarette smokers' urine were used as a model complex mutagenic mixture for validation of the assay. The modification consists of adding increased numbers of bacterial cells (approximately 10(9] in a concentrated suspension to liver homogenate mix and urine extract, all in 0.2-ml volume. After 90 min incubation at 37 degrees C, the mixture is processed according to the standard Ames test protocol. This procedure is 20 times more sensitive than the standard plate-incorporation test and 13 times more sensitive than a previously reported liquid-incubation protocol. The number of spontaneous revertants did not increase under these conditions and, compared to the plate-incorporation test, 10-fold less liver homogenate and 5-fold less enzymatic cofactors were needed per plate. The procedure was approximately 14 times more sensitive in detecting the mutagenic activity of benzo[ a ]pyrene. We also used the modification to determine mutagenic activity in urine from a group of nonsmokers. The method may be generally useful for investigations of mutagenic activity in human urine samples.
mesh_terms: D000328:Adult; D001564:Benzo(a)pyrene; D001580:Benzopyrenes / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology; D009152:Mutagenicity Tests / Q000379:methods*; D009153:Mutagens / Q000032:analysis*; D009154:Mutation; D012475:Salmonella / Q000235:genetics; D012907:Smoking; D014556:Urine / Q000032:analysis*
chemical_list: D001580:Benzopyrenes; D009153:Mutagens; D001564:Benzo(a)pyrene