The possible importance of tRNA methylases in carcinogenesis was suggested by Srinivasan and Borek (48, 49). This hypothesis has stimulated a considerable amount of subsequent work and is currently under investigation in several laboratories. The hypothesis was based originally on the observation by Bergquist and Mathews (3) that some tumors contained higher levels of methylated RNA than their ...

Extraction with butan-1-ol of freeze-dried microsomal fractions from livers of 3-methyl-cholarthrene-pre-treated hamsters removed about 90% of the total lipid content, but the lipid remaining proved sufficient for the cytochrome P-450 enzyme system to retain about 15-40% of its original catalytic activity for dimethylnitrosamine demethylation. Addition of butan-1-ol-extracted total phospholipid...

Volatile N-nitrosamines were detected in the urine of male volunteers with gas-liquid and high-pressure liquid chromatography interfaced to the thermal energy analyzer. Of 50 samples from normal males, 10 contained nitrosodimethylamine (0.02 to 0.10 micrograms/liter), 6 contained nitrosodiethylamine (0.02 to 3.10), 9 contained nitrosomorpholine (0.006 to 0.67), and none contained nitrosodibutyl...