Effect of dietary intake of vitamin A or E on the level of DNA damage, chromosomal aberrations, and micronuclei induced in freshly isolated rat hepatocytes by different carcinogens.

Hepatocytes freshly isolated from male Wistar rats fed a common diet or a vitamin A- or vitamin E-supplemented diet (each for 21, 28, or 41 days) were assayed for sensitivity to DNA breakage and cytogenetic changes induced by carcinogens. Different indirectly acting carcinogens were assayed. N-nitrosomorpholine (NMOR) was the only agent that induced DNA breaks, chromosomal aberrations, and micronuclei in all experiments.

Mutagenicity of 7H-dibenzo[c,g]carbazole and its tissue specific derivatives in genetically engineered Chinese hamster V79 cell lines stably expressing cytochrome P450.

Genetically engineered Chinese hamster V79 cell lines with stable expression of human cytochrome P4501A1 and 1A2 were used to characterize the particular form of P450 enzymes capable of activating 7H-dibenzo[c,g]carbazole (DBC) and its tissue- and organ-specific derivatives, N-methylDBC (N-MeDBC) and 5,9-dimethylDBC (diMeDBC). In addition, a V79 cell line with co-expression of CYP1A2 together with a phase II enzyme, N-acetyltransferase was utilized to study the role of an entire metabolic activation system in biotransformation of these carbazoles. The rise of 6-thioguanine resistant (6-TG(r)) mutations was followed as a marker of biological activity of these agents.