[Cytogenetic changes of the bone marrow in massive blood loss and their correction with mexidol]. / Tsitogeneticheskie izmeneniia kostnogo mozga pri massivnoi krovopotere i ikh korrektsiia meksidolom.

The citogenetic lesions were evaluated in the marrow erythroblasts of 45 anesthetized white nonlinear male rats, weight--200-300 g who were subjected to an acute blood loss with a 1-hour arterial hypotension (ABR = 40 mm Hg); the micronucleus tests was made use of. Two stages of the increase of polychromatophilic erythrocytes with micronuclei in the marrow of the animals, who underwent a massive blood loss, were registered: stage 1--an incomplete marrow ischemia with a subsequent arterial hypotension and with a reliably confirmed formation of cytogenetic lesions in the marrow polychromatophilic erythrocytes; stage 2--the reperfusion period contributed to a 1.7-fold increase of polychromatophilic erythrocytes with micronuclei versus the previous stage. Mexidole, when used at 50 mg/kg prior to blood reinfusion, decreased the quantity of polychromatophilic erythrocytes with micronuclei to the basic level, which is indicative of reversibility and instability of cytogenetics impairments in the marrow cells of animals observed in the early post-resuscitation period.

[Study of the antiradical and radioprotective properties of S-containing compounds using the complex of in vitro test-systems]. / Izluchenie antiradikal'nykh i protivoluchevykh svoistv S-soderzhashchikh soedinenii s ispol'zovaniem kompleksa test-sistem in vitro.

Capability of S-radioprotectors (AET, 2-AT, 2-ADT) to react with OH-radicals and to protect various molecular biotest systems against radiation damage was compared with that of 5-methoxytryptamine, some amino acids and t-butanol. A method of competing acceptors was used to determine rate constants in reactions of the radioprotectors with OH-radicals. A complex of biotest systems (protein, DNA, protein-lipid complex) was applied to estimate the radioprotective activity in vitro. It was found that the studied S-compounds are capable of modifying the protective effect as compared to the expectation from the competitive kinetics approach. Both enhancing and lessening of the effect was observed depending on the test system used. The obtained results can be explained by the impact of secondary radicals on the bio-target and/or by the interaction of the S-compounds with the bio-target that altered its radiosensitivity.

[The effect of ionizing radiation on human muscle tissue]. / Vliianie ioniziruiushchei radiatsii na myshechnuiu tkan' cheloveka.

The effect of ionizing radiation (gamma-irradiation of 60Co, doses from 10 Gy to 15 kGy) on human muscle tissue was studied using a biopsy material. Destructive alterations in muscle proteins were observed beginning from the dose of 1.0 kGy: appearance of new protein fractions with molecular mass 68-160 kDa and 18-36 kDa. Resistance of muscle proteins to the trypsin effect was unaltered, while the rate of pronase-induced hydrolysis was slightly increased, about 1.2-fold. Content of water and biomechanical properties of the tissue were unaltered, but the modulus of elasticity was decreased approximately 3-fold after treatment with maximal doses of the ionizing radiation used.

[Effect of ionizing radiation on the structure of human serum albumin. Effect of irradiation on the content of free amino groups and on the ability of HSA to be digested by proteinases]. / Deistvie ioniziruiushchei radiatsii na strukturu syvorotochnogo al'bumina cheloveka. Vliianie oblucheniia na soderzhanie svobodnykh aminogrupp i sposobnost' SACh perevarivat'sia proteinazami.

The effect of gamma-quanta on human serum albumin (HSA) solutions (1.6 mg/ml, borate buffer pH 7.45) in the air has been investigated. Using 2,4,6-trinitro-benzene-sulfonic acid it has been shown that 2-22 kGy radiation reduces the free amino groups content of HSA and increases its resistance to the hydrolytic effect of trypsin and pronase which is not influenced by the postirradiation exposure to heat. It is concluded that epsilon-NH2-groups of lysine residues are modified and firm cross-links are formed in HSA under the effect of radiation.

[Effect of ionizing radiation on the structure of the collagen fibers of human tendons]. / Vliianie ioniziruiushchei radiatsii na strukturu kollagenovykh volokon sukhozhilii cheloveka.

In studying the effect of ionizing radiation on the properties of human Achilles tendon collagen fibres, the following parameters were analyzed: hydrothermal contraction temperature, module of elasticity, the number of cross-links, free and bound water levels, acids-soluble fraction content, and ultrastructure. With radiation doses of 2-10 Gy no changes in the collagen status were noted. An increased (from 5 to 25 Gy) radiation dose caused changes in physicochemical properties which was indicative of the formation, in the connective tissue collagen, of radiation-induced intermolecular cross-links stabilizing the biopolymer structure.

[Radiation-induced binding of 2-amino-5,6-dihydro-1,3-4H-thiazine to DNA]. / O radiatsionno indutsirovannom sviazyvanii 2-amino-5,6-digidro-1,3-4H-tiazina s DNK.

A study was made of the nature of radiation--induced bonds between DNA and 2-amino-5,6-dehydro-4H-thiazine (2-ADT) having a radioprotective action. Using the gelfiltration method and 35S-2-ADT, it was shown that the amount of the radioprotector bound to DNA increased with radiation dose and did not depend on the postirradiation treatment with 3 M LiCl or 3 M urea. No marked binding was noted after mixing the separately exposed DNA and the protector. It is concluded that a covalent linkage of DNA and 2-ADT occurs, upon irradiation, via short-living states of DNA and (or) the protector.

[Effect of the magnitude of radiation dose on the formation of DNA double-strand breaks]. / Vliianie moshchnosti dozy oblucheniia na obrazovanie dvunitevykh razryvov DNK.

It was shown that under the effect of sparsely ionizing radiation double-strand DNA breaks in solution were formed more readily at high dose-rates (20 Gy/min) than at low ones (0.03-0.06 Gy/min). Possible mechanisms of the effect observed are discussed.

[Estimation of various quantitative methods for the determination of native and formaldehyde-treated proteins]. / Otsenka razlichnykh kolichestvennykh metodov opredeleniia belkov, nativnykh i obrabotannykh formal'degidom.

Quantitative estimation of native and treated with 4% formaldehyde albumin, pepsin, lysozyme, histone, gelatin and other proteins was carried out using four procedures--biurete, Lowry-Folin, ninhydrin and coomassy R-250. Chromogeneity of proteins in corresponding color reactions was expressed as OD per 100 micrograms of nitrogen estimated by means of Kjeldahl micromethod. The proteins were treated with formaldehyde in corresponding buffers at 20 degrees within 7 days, non-bound or loosely bound formaldehyde was dialysed. Native proteins were dissimilar in their chromogeneity; these differences were the highest for Lowry-Folin and coomassy procedures. Formalinization affected the protein chromogenencity depending on a protein nature, conditions of formaldehyde treatment and on the procedure of estimation used. As shown by analysis of the data obtained the alterations of chromogeneity did not reflect the rate of reactive group blocking by formaldehyde in a protein molecule. The quantitative methods should be used very carefully in estimation of formalinized proteins.

[Effect of low-molecular amines on DNA conformation and stability of the double helix]. / Vliianie nizhomolekuliarnykh aminov na konformatsiiu i stabil'nost' dvoinoi spirali DNK

Interaction of low-molecular amines (cystamine, cysteamine, cystaphose, asparagine, beta-alanine) with DNA was studied. The amines change the positive circular dichroism (CD) band of DNA as well as temperature and range width of melting. Effect of amines on DNA depends on ionic strength of the solvent, concentration and structure of the ligand. Monamines cause destabilization of DNA double helix followed by stabilization as ligand concentration increases. At concentrations stabilizing the double helix DNA conformation undergoes transition from the B- to C-form. The results obtained enable to relate the stabilizing effect of low-molecular amines and conformational B leads to C-transition to the non-specific interaction of ligand amino groups with DNA phosphates, and the destabilizing effect of monoamines of low concentrations to their interaction with bases, mainly in the denaturated sites of DNA. It is proposed that a stronger effectiveness of amines as compared to monovalent metals in the conformational shift of DNA towards the C-form is due to the additional effect of disturbance of hydrophobic interactions in DNA double helix.