[The age-related dynamics of the activity of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase in different organs of rats].

Concentrations of O6-alkylguanine-DNA alkyltransferase (AT) which repairs a procarcinogenic DNA adduct O6-alkylguanine formed following exposure to carcinogenic N-nitroso compounds were measured in the liver, kidney and peripheral blood leukocytes of male L10 rats aged 1, 4, 14, 22 and 36 months. In the liver, peak AT level was observed at the age of 14 and 22 months. No age-related differences were established for kidney and leukocytes.

[A comparative study of the cryoprotective properties of dimethylacetamide and dimethyl sulfoxide in preserving thrombocytes at moderately low temperatures].

Comparative characteristics of cryoprotective properties of dimethylacetamide and dimethyl sulfoxide (DMAC and DMSO, respectively), used for freezing and storage of platelets at -80 degrees C, have been presented. It is shown that with the studied final concentrations of the cryoprotectors (5% of DMSO, 2.5% of DMAC), solutions containing DMSO display higher cryoprotective properties.

[Capacity of rhabdomyosarcoma cells to produce substances with somatomedin and mitogenic activity].

The rats aged 1, 3, 12 and 15 months were intravenously injected with 10,000 of the rhabdomyosarcoma cells. 3 weeks following the injection multiple tumour clones were observed in the lungs of experimental animals, the rats aged 1 and 15 months showing a significantly greater tumour yield than those aged 3 and 12 months. The level of the mitogenic and somatomedin activity increased both in the blood serum and in the lung tissue, the activity varying with the number of tumour clones.

[Inactivation of O6-alkylguanine-DNA alkyltransferase in the liver of rats during administration of methylated DNA].

Intraperitoneal administration of 6.5 mg of methylated DNA, O6-methylguanine concentration being 11.5% that of guanine, to 3 month-old noninbred male rats was followed by a 5-fold decrease in the activity of O6-alkylguanine-DNA alkyltransferase (AT) within the first hour.