[Influence of ionizing radiation on the parameters of oxidative stress markers in the rat liver and thymus].

Influence of ionizing radiation on the parameters of oxidative stress markers in the liver and thymus of the rats exposed to gamma-radiation 60Co at a doze of 4 Gy was investigated. The animals were decapitated on the 1, 4, 7, 10, 14, 22 and 30th day after irradiation and cell suspensions from the liver and thymus were obtained. After centrifugation, the content of MDA, the spontaneous and NADH-induced synthesis of superoxide anion radical of oxygen, the content of total and free iron were determined in the cellular sediment and centrifugate containing intercellular fluid. It is shown that the content of MDA and the levels of spontaneous and NADH-induced synthesis of superoxide anion radical of oxygen increases in intercellular fluid and thymus and liver cells on the 1st day after radiation exposure. In the liver, these parameters are normalized by the 4th day and do not significantly differ from the control level in the period of time following radiation exposure. In thymus, as compared with liver, the level of oxidative stress parameters increases by the 4th day after radiation and remains at the raised level within 22 days after irradiation exposure. It is shown that the content of free iron in thymus cells of irradiated animals increases 3.6 times by the 4th day and reliably exceeds the control level within the next 22 days. Radiation does not lead to any changes in the content of free iron in liver cells. Different levels of the free iron content can serve the reason for various sensitivity of oxidative stress markers in thymus and liver cells to radiation exposure.

[Antioxidant and prooxidant properties of the ascorbic acid, dihydroquercetine and mexidol in the radical reactions induced by the ionizing radiation and chemical reagents].

Antioxidant and prooxidant properties of dihydroquercetine, mexidol and an ascorbic acid in reactions with participation of radicals OH* and O2(-)*, induced by gamma-irradiation, iron-catalyzed decomposition of hydrogen peroxide and oxidation of reduced NADH by phenazine metosulfate are investigafed. The efficiency of scavenging of radicals OH* estimated by the results of the analysis of deoxyribose degradation, and the efficiency of scavenging of superoxide anion-radicals O2(-)* is estimated by the results of the analysis of occurrence the reduced nitrotetrazolium blue. The concentrations of analyzed compounds, scavenging on 50% (C50%) formation of radicals OH* and O2(-)* are certain. It is shown, that an ascorbic acid, dihydroquercetine and mexidol decrease the generating of superoxide anion-radicals O2(-)* in the gamma-irradiated solutions of sodium format and at oxidation of reduced NADH by phenazine metosulfate scavanged of superoxide anion-radicals O2(-)*. In the gamma-irradiated saline solutions an ascorbic acid, dihydroquercetine and mexidol protected deoxyribose from oxidizing action of hydroxyl radicals OH*. However at presence Fe(3+), EDTA and hydrogen peroxide addition of an ascorbic acid (0.1 mmol/l) increased generating of hydroxyl radicals OH* and in 2.8 times raised the maintenance of products of deoxyribose oxidation, reacting with thiobarbituric acid. Prooxidant action of an ascorbic acid is observed as well in absence of hydrogen peroxide. Obtained data testify that in various modelling systems reagents, in particular ions of iron, and the formed active intermediate products render significant influence on scavenging efficiency of investigated compounds.

[Comparative efficiency of injurious action of radiation and stress on thymus and lipid peroxidation]. / Sravnitel'naia éffektivnost' povrezhdaiushchego deistviia oblucheniia i stressa na timus i perekisnoe okisleniia lipidov.

Exposure to radiation, as well as holding under conditions of limited mobility during 24 h, induced decrease in thymus cell number, increase in number of DNA breaks. The content the products of lipid peroxidation reactive with thiobarbituric acid in blood serum of mice decreased as well. The stress effect is comparable with radiation doses in the range of 50-60 cGy.

[Effect of preliminary adaptive irradiation on the concentration of lipid peroxidation products in blood serum and degradation of DNA in thymus of irradiated mice]. / Vliianie predvaritel'nogo adaptiruiushchego oblucheniia na soderzhanie produktov perekisnogo okisleniia lipidov v syvorotke krovi i povrezhdeniie DNK v timuse obluchennykh myshei.

The animals were irradiated within adaptive dose of 0.1 Gy and 5 hours later with a challenge dose of 2 Gy. The adaptive dose reduced the effects induced by the challenge dose of 2 Gy: the increased content of the products of lipid peroxidation reactive to thiobarbituric acid in blood serum, and the increased number of breaks in thymus DNA of irradiated mice.

[The molecular, cellular and systemic mechanisms of the radioprotective action of multivitamin antioxidant complexes]. / Molekuliarnye, kletochnye i sistemnye mekhanizmy radioprotektornogo deistviia polivitaminnykh antioksidantnykh kompleksov.

Exposure to radiation, as well as holding under conditions of limited mobility during 24 h induced decrease of thymus cell number in mice. Usage of water-dispersed forms of beta-carotene with addition of vitamins E and C protected thymus against cellular devastation induced by irradiation and stress, and increased the efficiency of DNA repair in spleen of irradiated mice.

[Distribution of beta-carotene in the rat upon its intraperitoneal administration in water soluble and oil forms]. / Raspredelenie beta-karotina v organizme krys pri ego vnutribriushinnom vvedenii v vide vodorastvorimoi i maslianoi form.

Accumulation and excretion of beta-carotene in rat liver tissue were studied when the carotinoid was intraperitoneally administered as olive oil as suspension and a water liposomal suspension. Single injection of the liposomal form of beta-carotene caused an increase in its content in liver tissue. If beta-carotene was administered at a dose of 10 mg/kg its maximal content 44 mg/g of the tissue was observed within one day, and at a dose of 50 mg/kg, its maximal content constituted 178 mg/g within two days. Administration of beta-carotene as an oil suspension at a dose of 50 mg/kg led to a considerably slight accumulation in rat liver tissue with the maximal value of 12 mg/kg of the tissue within two days. Possible use of beta-carotene various forms, as well as experimental models for study their biological activity are discussed.

[The inhibition by the tumor necrosis factor of the death and DNA fragmentation of lymphoid cells in irradiated rats]. / Ingibirovanie faktorom nekroza opukholi gibeli i fragmentatsii DNK limfoidnykh kletok obluchennykh krys.

The influence of a tumor necrosis factor, administered 16 h before irradiation of rats, on the radiation response of thymus and bone marrow cells has been investigated. Three and 6 h after irradiation the following indices were analyzed: the number of apoptotic cells in the thymus; the accumulation of polydeoxyribonucleotides and the appearance of single-strand breaks in DNA of bone marrow and thymus cells; and the electrophoretic properties of thymocyte DNA. The injection of a tumor necrosis factor reduced the number of polydeoxyribonucleotides, inhibited internucleosome DNA fragmentation, and did not influence the formation of single-strand breaks in DNA.

[Electrophoretic analysis of the internucleosome fragmentation of DNA in irradiated thymocytes of rats]. / Elektroforeticheskii analiz mezhnukleosomnoi fragmentatsii DNK v obluchennykh timotsitakh krys.

Total DNA and DNA of chromatin degradation products obtained from rat thymocytes 6 h after irradiation with a dose of 10 Gy were separated electrophoretically. Relative shares of mononucleosomes and their oligomers were determined. Experimental distributions of DNA fragments differ from those calculated on the basis of the assumption of a random breakage of bonds between the nucleosomes.

[Different mechanisms of blood thymidine levels caused by irradiation and polyanion administration]. / Razlichnye mekhanizmy timidinemii, vyzvannoi oblucheniem i vvedeniem polianionov.

The administration of dextran sulfate causes an increase in the thymidine content of rat blood comparable with the postirradiation thymidinemia. In contrast to radiation dextran sulfate does not increase polydeoxynucleotide content of thymus. Isoptin, a calcium antagonist, decreases thymidinemia induced by dextran sulfate to a greater extent than that induced by ionizing radiation. Thymidinemia induced by dextran sulfate is supposed to be due to its effect on cell membranes. In radiation-induced thymidineamia this mechanism is of lesser significance.

[Endonucleolysis of chromatin in thymocytes of irradiated and non-irradiated rats]. / Endonukleoliz khromatina v timotsitakh obluchennykh i neobluchennykh krys.

It was shown that in conditions optimal for Ca/Mg endonuclease, chromatin endonucleolysis in the nuclei and thymocytes occurs due to internucleosome fragmentation of DNA. Irradiation activates chromatin degradation in thymocytes washed by a buffer containing 0.25 M sucrose, 10 mM tris-HCl, pH 7.2, 3 mM MgCl2, and does not influence this process in thymocytes washed by 10 mM tris-HCl, pH 7.2, 3 mM MgCl2.

[Chromatin degradation in white blood cells of irradiated rats]. / Raspad khromatina v kletkakh beloi krovi obluchennykh krys.

A study was made of the dose-time relationship during chromatin degradation in white blood cells of non-irradiated and irradiated rats. There was a linear increase in the release of PDN from leukocytes 1,2 and 3 days after irradiation (1-3 Gy) followed by the deceleration of the chromatin degradation at doses exceeding 3 Gy.