No abstract available

No abstract available

No abstract available

[en] It has been shown in vitro on Ehrlich ascites tumour cells that a radiosensitizing action of N-ethylmaleimide(N-EM) is a result of its interaction with the cells prior to irradiation. A high radiosensitizing activity of N-EM in the anoxic conditions and the absence of the effect in the presence of oxygen seem to be connected with the increased, under anoxia, level of endogenous thiols, which affects the intracellular distribution of N-EM

No abstract available

[en] In experiments on hybrid mice F₁CBAxC57Bl/6, it was shown that as the interval between fractions of irradiation dosage increases from 0.5 to 6 hours, the viability and average life span of the animals increase and remain at the level when the interval between irradiation doses is lengthened to 24 hours. Similarly, there is a change in the content of sulfhydryl groups in the spleen. The direct correlation between the radiosensitivity of the animals and the content of thiols in their hematopoietic tissue indicates that the changes in radiosensitivity when doses are administered fractionally are connected with changes in the thiol level caused by the first irradiation. (author)

[en] In experiments on mice and bone marrow CFUs a study was made of the radioprotective efficiency of serotonin and adrenaline depending on their concentration. It was shown that in order to protect the body a minimum amount of monoamines is requred; the amount to protect CFUs in vivo is about 5 times greater, and to protect CFUs in vitro, the dose is maximum. The animals are protected by such monoamine concentrations which cannot lessen the affection of CFUs in vivo

[en] Administration of methylhydrazine to mice has been shown to decrease nearly twice the survival of animals, inhibit by 30 per cent the growth of Ehrlich ascites tumour and to increase by 20 per cent the number of cells with chromosomal aberrations as compared to irradiated control animals. By the time of irradiation, the total level of thiols (determined by the amperometric titration of homogenates) decreases, under the effect of methylhydrazine, by 18 per cent in the spleen and 56 per cent in the tumour cells. The ability of methylhydrazine to decrease the thiol level is suggested to be responsible for its radiosensitizing activity

[en] It has been studied whether one of the most effective heterocyclic compounds, 2-amino-5,6-dehydro/4H-1,3-thiazine (2-ADT), can reduce radiation-induced damage of hemopoiesis. The process of bone marrow regeneration in the animals treated with 2-ADT is shown to begin earlier than in the untreated ones due to a more rapid recovery of myeloid and erythroid cells. The amount of CFU in the organism of 2-ADT-treated animals does not change immediately after irradiation and increases markedly if cells remain in the treated organism for 24 hours. This is suggested to be connected with the migration of stem or committed cells from the protected areas of hemopoietic tissue to the bone marrow

[en] A study of the temperature influence on the radiosensitizing effectiveness of oxygen and N-ethylmaleimide (NEM) has demonstrated that the increase in radiosensitivity of E. coli and Ehrlich's ascites tumor, induced by these agents, is independent of the temperature (37 deg and 1 deg C). It indicates that the radiosensitizing effect of oxygen and NEM is, apparently an elementary process which confines itself to decreasing the content of endogeneous radioprotective agents