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Mutability of different genetic loci in mammalian cells by metabolically activated chemical carcinogens
202 of DC in new hosts caused renewed cell growth. To test this system, the hosts were injected with the chemotherapeutic agent cyclophosphamide (CY). CY is inert in vitro but highly mutagenic and clastogenic in vivo. Injection of CY at the doses of 80--150 mg/kg of body weight caused increase of chromosome aberrations of human cells in DC in mice. The extent of aberrations was correlated with the doses. Induction of SCE in human cells and V79 in DC in mice by CY treatment at the doses of 7.5, 15 and 30 pg/g of body weight was studied. The number of SCE/cell increased from 4 to 8 folds as compared with controls and the increase was dose-dependent. Induction of 8-azaguanine and ouabain resistant mutants in human and V79 cells in DC in mice due to the CY treatment are in progress. The results so far indicate that this in vivo test system is sensitive, economical, relevant to man and especially valuable for testing compounds which need to be metabolically activated. S u p p o r t e d in p a r t b y G r a n t E S - 1 2 9 0 - 2 f r o m N I E H S a n d EPA.
97 Hubbard, S.A., and J.W. Bridges, Department of Biochemistry, University of Surrey (U.K.) and M.H.L. Green and B.A. Bridges, MRC Cell Mutation Unit, University of Sussex (U.K.) Use o f intact liver cells for metabolic activation in a simplified fluctuation test for detection o f carcinogens and mutagens
The simplified fluctuation test, for detection of mutation in appropriate tester strains of S. typhimurium or E. coli, has been adapted to incorporate metabolic activation of carcinogens or mutagens by both intact hepatocytes or microsomes (Green et al., Mutation Res., 48 (1977) 287--294). We are developing the use of freshly prepared intact hepatocytes since the ability of microsomes and established liver cell lines to activate carcinogens and mutagens differs from that of the liver in vivo. We are currently improving the procedure to prolong the viability and metabolic capability of the isolated hepatocytes. Preliminary evidence indicates that under the improved conditions, metabolic capability is demonstrable after 24 h and greater sensitivity of the test is obtained with 2-acetylamidofluorene. We also report the observation that after induction of rats with Aroclor 1254, the recovery of intact hepatocytes is significantly reduced by comparison with recovery from uninduced liver.
98 Huberman, E., Biology Division, Oak Ridge National Laboratory, Oak Ridge, TN (U.S.A.)
203 Mutability of different genetic loci in mammalian cells by metabolically activated chemical carcinogens The relationship between carcinogenesis and mutagenesis in mammalian cells has been determined with 11 polycyclic hydrocarbons with different degrees of carcinogenicity. Mutagenesis was determined in Chinese hamster cells with genetic markers that affect the surface membrane, nucleic acid synthesis and protein synthesis. The mutations were characterized by resistance to ouabain, 8-azaguanine and temperature. Mutagenesis by the carcinogens required metabolic activation and this was provided by the presence of lethally irradiated metabolizing cells. The degree of carcinogenicity was related to the degree of mutagenicity for all three genetic markers. The most potent carcinogen, 7,12
97 Hubbard, S.A., and J.W. Bridges, Department of Biochemistry, University of Surrey (U.K.) and M.H.L. Green and B.A. Bridges, MRC Cell Mutation Unit, University of Sussex (U.K.) Use o f intact liver cells for metabolic activation in a simplified fluctuation test for detection o f carcinogens and mutagens
The simplified fluctuation test, for detection of mutation in appropriate tester strains of S. typhimurium or E. coli, has been adapted to incorporate metabolic activation of carcinogens or mutagens by both intact hepatocytes or microsomes (Green et al., Mutation Res., 48 (1977) 287--294). We are developing the use of freshly prepared intact hepatocytes since the ability of microsomes and established liver cell lines to activate carcinogens and mutagens differs from that of the liver in vivo. We are currently improving the procedure to prolong the viability and metabolic capability of the isolated hepatocytes. Preliminary evidence indicates that under the improved conditions, metabolic capability is demonstrable after 24 h and greater sensitivity of the test is obtained with 2-acetylamidofluorene. We also report the observation that after induction of rats with Aroclor 1254, the recovery of intact hepatocytes is significantly reduced by comparison with recovery from uninduced liver.
98 Huberman, E., Biology Division, Oak Ridge National Laboratory, Oak Ridge, TN (U.S.A.)
203 Mutability of different genetic loci in mammalian cells by metabolically activated chemical carcinogens The relationship between carcinogenesis and mutagenesis in mammalian cells has been determined with 11 polycyclic hydrocarbons with different degrees of carcinogenicity. Mutagenesis was determined in Chinese hamster cells with genetic markers that affect the surface membrane, nucleic acid synthesis and protein synthesis. The mutations were characterized by resistance to ouabain, 8-azaguanine and temperature. Mutagenesis by the carcinogens required metabolic activation and this was provided by the presence of lethally irradiated metabolizing cells. The degree of carcinogenicity was related to the degree of mutagenicity for all three genetic markers. The most potent carcinogen, 7,12