[Effects of selenium on endogenous synthesis of N-nitrosamines and toxicity of nitrites in rats]. / Vliianie selena na éndogennyi sintez N-nitrozaminov i toksicheskoe deistvienitritov u krys.

Male Wistar rats were fed selenium (0.2, 2.9 or 5.5 mg/kg of dry feed) in the form of selenomethionine. They also received for 6 weeks amidopyrine (33 mg/kg b.w.) and/or sodium nitrite (20 mg/kg b.w.) administered intragastrically. The quantitation of endogenously synthetized volatile nitrosamines in the stomach, selenium in the serum, biochemically evaluated nitrite and nitrosamines toxicity revealed an inverse relationship between feed selenium concentrations and the amount of endogenously produced nitrosodimethylamine from equal precursor doses. A protective selenium effect on methemoglobin-producing action of nitrite ions was established. It is shown that introduction of precursors induces increased body need in selenium.

[Characteristics of the toxic effect of lead ingested with food in model experiments]. / Issledovanie osobennostei toksicheskogo deistviia svintsa pri postuplenii ego s pishchei v model'nom eksperimente.

A transformed form of lead was obtained in model experiments. It was established that administration of lead in the ionic form (repeated action, 21 times) in a dose of 0.2 mg/kg bw produces a toxic effect. Administration of the transformed form of lead did not bring about any statistically significant alterations on the part of the toxic and specific indicators.

[Action of aureolic acid and dactinomycin group antibiotics on human brain tumors in culture]. / Izuchenie deistviia antibiotikov gruppy aureolovoi kisloty i daktinomitsina na opukholi golovnogo mozga cheloveka v kul'ture.

The cytotoxic effect of antitumour antibiotics, such as dactinomycin, mithramycin, variamycin and olivomycin on the cells of the human brain tumours (multiform glyoblastoma, arachnoidendotelioma and astrocytoma) grown by the method of the primary plasmic culture was studied. Dactinomycin was superior to the antibiotics of the aureolic acid group in the rate and level of the cytotoxic effect on the tumour cells: 76 per cent of the above tumours were sensitive to dactinomycin, 56 per cent to mithramycin and 52 per cent to variamycin and olivomycin. Among the total number of the tumours sensitive to the drugs the number of the highly sensitive tumours amounted to 57.9 per cent for dactinomycin and 30.8--38.5 per cent for the antibiotics of the aureolic acid group. Definite differences in the efficiency of the antibiotics of the aureolic acid group with respect to different types of the brain tumours were observed.

[Results of a study of the pharmacokinetics of actinomycete RNAase in the bodies of white rats]. / Rezul'taty izucheniia farmakokinetiki aktinomitsetnoi RNK-azy v organizme belykh krys.

The pharmacokinetics of RNA-ase from Act. rimosus was studied on albino rats. The enzyme activity in the biological tests was determined spectrophotometrically by the increase of the acid-soluble products formed as a result of RNA-ase effect on RNA. The preparation was rapidly absorbed into the blood and organs, the maximum levels in the blood and organs being observed 30 minutes and 1 hour after the preparation administration. The preparation levels in the organs with the exception of the liver and kidneys were rather low. The highest levels observed in the kidneys and liver were 19.6 and 3.37 per cent respectively on the RNA-ase amount administered. Within the first 3 hours of the enzyme administration insignificant amounts of the substance were registered in the urine. Penetration of RNA-ase through the hemato-encephalic barrier was low.

[Results of an experimental study of the antitumor activity of 1-asparaginase from E. coli and Erw. carotovora]. / Rezul'taty éksperimental'nogo izucheniia protivoopukholevoi aktivnosti 1-asparaginazy iz E. coli i Erw. carotovora

The antitumour activity of the preparations of L-asparaginase from E. coli and Erw. carotovora with respect to lymphadenosis L-5178 and Yorker's carcinosarcoma (ascitic cariants) has been established. No difference in antitumour efficacy of the preparation of L-asparaginase obtained from E. coli and Erw. carotovora was noted.

[C14-variamycin content in normal and tumorous brain tissues of white rats]. / Soderzhanie C14-variamitsina v normal'noi i opukholevoi tkaniakh golovnogo mozga belykh krys

Penetration of variamycin, a new antitumor antibiotic into the normal and tumor tissues of the brain of rats with multiform glioblastoma was investigated. The content of the C14-labeled antibiotic was determined radiometrically. The radioactive label penetrated into the normal and tumor tissues of the brain during the first hours after the drug administration. The level of the radioactivity in the tumor tissue was higher than that in the normal brain tissue during the whole period of the study. The greatest deviation in the contents of the radioactive label in the tumor and normal tissues was observed 2 and 3 hours after administration of the labeled antibiotic, i. e. 4.3 and 3.6 times respectively.

[Study of the distribution of C14-variamycin and C14-mitramycim after intravenous administration to mice]. / Izuchenie raspredeleniia C14-variamitsina i C14-mitramitsina posle vnutrivennogo vvedeniia mysham

Distribution of antitumor antibiotics, i.e. C14-variamycin and C14-mitramycin in the organs of albino mice after their intravenous administration in single doses was studied. Similarity in the distribution dynamics of both the antibiotics with respect to the animal organs was found. However, the level of variamycin as compared to that of mitramycin was much higher in the liver and especially the spleen. In the experiments with variamycin the radioactivity of the kidney tissue decreased more rapidly than in the experiments with mitramycin. Chromatographic analysis of the urine of the mice treated with C14-variamycin was performed. The labeled Variamycin was detected in the animal urine within 48 hours from the moment of the antibiotic administration. Its portion in the total amount of the radioactive products in the urine was 30 to 40% at various stages of the study.

[Autoradiographic determination of the parameters of the mitotic cycle of tumors of human testis in tissue culture]. / Avtoradiograficheskoe opredelenie parametrov mitoticheskogo tsikla opukholi iaichka cheloveka v kul'ture tkani

By means of autoradiography with thymidine-H3 the authors studied the mitotic cycle of a primary culture of the human testicle tumours on the 16th day of growth. Prolonged incubation with the isotope was employed. The following parameters of the mitotic cycle for the whole cellular population were established: T-83.6 hours, G + M = 60.25 hours, S = 5.35 hours, G2 = 18.0 hours. A conclusion was drawn that it was possible to use the primary culture to determine the mitotic cycle of human tumours.