Dimethylnitrosamine administration led to the produc tion of abnormal methylated purines in rat liver DNA. All of the methylated purines formed were lost from DNA to some extent over a 24-hr period although the rate of removal varied with the purine considered. The rates of loss of 1-methyladenine, 3-methyladenine, 7-methyladenine, 3-methylguanine, and 7-methylguanine were not changed significa...

Extreme caution should be exercised when one interprets results of in vitro studies on bacterial lethality, mutagenesis, and dimethylnitrosamine-demethylase activity obtained with dimethylnitrosamine at concentrations of 20 mM or higher. In fact, previous investigations in our laboratory have shown that dimethylnitrosamine as well as other nitrosamines are powerful hydrogen-bonding agents (5) a...

1. The incorporation of methyl groups into histones from dimethylnitrosamine and from methionine was studied by injection of the labelled compounds, isolation of rat liver and kidney histones, and analysis of hydrolysates by column chromatography. 2. Labelled methionine gave rise to labelled in-N-methyl-lysine, di-in-N-methyl-lysine and an amino acid presumed to be omega-N-methyl-arginine. 3. A...

background there is still no suitable mice model that can completely mimic the human fulminant hepatitis, which sets a block for drug effect evaluation and mechanism researching of human fulminant hepatitis. objectives the aim of this study was to establish an animal model able to mimic the main features of human fulminant hepatitis. materials and methods dimethylnitrosamine (dmn) was peritonea...

The correlation between the in vivo toxicity and in vitro mutagenicity of dimethylnitrosamine and the activity of dimethylnitrosamine demethylase I (DMND I) after pyrazole treatment of rats was studied. The biological effects of pyrazole were measured either as toxicity to the rats or as mutations to Salmonella TA 92. A dose-response relationship was observed between DMND I activity and the adm...

A major proportion of bacterial types, common in the gastrointestinal tract of many animals and man, were active in degrading diphenylnitrosamine and dimethylnitrosamine, the former being degraded more rapidly than the latter. At low nitrosamine concentrations (is less than 0.05 micronmol/ml), approximately 55% of added diphenylnitrosamine, 30% of N-nitrosopyrrolidine, and 4% of dimethylnitrosa...

1. After dimethylnitrosamine (DMNA) administration to mice, the content of poly(A)-containing RNA decreases rapidly in the postmicrosomal fraction of the liver. We report here that the loss of free mRNA is not a result of increased nucleolytic activity. On the contrary, a decreased activity of microsomal endonuclease, assayed by its effect on polyribosomal mRNA, was demonstrated already 15 min ...

The effect of administration of carbon tetrachloride and dimethylnitrosamine in vivo on hepatic microsomal function related to drug metabolism was measured. It was found that the capacity of isolated microsomes to demethylate dimethylaniline was diminished during the first hour after carbon tetrachloride poisoning and during the second hour after dimethylnitrosamine poisoning. Thereafter the mi...

A study was made of the effects of administration to rats of dimethylnitrosamine and diethylnitrosamine on the transition temperature (Tm) of sheared chromatin and DNA isolated from the liver. The analysis was made by thermal chromatography on hydroxylapatite with the use of DNA prelabeled with [3H]thymidine and following the elution pattern during the operation of a continuous temperature grad...

Freshly prepared rat hepatocytes isolated by perfusion with collagenase were able to metabolize microM concentrations of dimethylnitrosamine to a methylating agent. The methylation of hepatocyte DNA in this system was complete within 2 hr, and after this time, the content of O6-methylguanine in the DNA declined, showing that the repair system for this product was active in the isolated hepatocy...