Izvestiia Akademii nauk SSSR. Seriia biologicheskaia最新文献

Preliminary administration of autogenic blood irradiated in vitro with ionizing radiation in small doses of 0.05, 0.3 or 0.5 Gy resulted in a pronounced increase in the radioresistance of mice [correction of rats] subsequently irradiated in a dose of 9 Gy. The optimum was autotransfusion of blood irradiated in a dose of 0.3 Gy a day or 10 days prior to the total irradiation which increased the survival rate of experimental animals to 80% while, in control groups, the survival rate was only 10%.

Meningoencephalic hernia was studied in human embryo at the 5th week (stage 15) of the development. The analysis of parietal hernia showed that the anomalous development of cerebral tissue was related with disturbed shape-forming processes in the nerve tube. The medullar toruli were not closed at the stage of nerve plate to form a free edge of neuroepithelial layer. Its relaxation resulted in a spontaneous foldness and an enhanced proliferation of neuroepithelial cells. The proliferative activity induced hyperplasia of the layer end zones a disproportionately rapid growth of the brain disturbed the integrity of cephalic ectoderm and elicited formation of external cerebral hernias. It was suggested that disturbances of tangential mechanical tensions which control the proliferative activity in the neuroepithelium underlie the overgrowth of nervous tissue.

A brief historical review of concepts on stem cells is given with a stress made on the role of Russian scientists A. A. Maksimov and A. A. Zavarzin who have formulated key problems in biology of stem cells and cell renewal. Principal stages in current studies of stem cells are considered. An outline is given of traditional and recent trends in the investigations: comparative studies of tissue systems with stem cells; molecular genetic mechanisms of the self-maintainance and the differentiation of stem cells; stem cells as a subject of gene engineering.

An analytical review of studies on human oxyhemoglobin coagulation has been performed by the author jointly with V. S. Koniaeva and L. D. Bogdanova within a period from 1985 to 1990. It was shown that the oxyhemoglobin coagulation modified by mercurials proceeded without any essential alteration of native protein conformation. A hypothesis is discussed that the oxyhemoglobin coagulation results from the primary polyaggregation of dimer fragments and that hydrophobic sites which provide for dimer-to-dimer contacts in native tetrameric oxyhemoglobin, participate in this process.

Scientific work on vitamin A research has started more than one hundred years ago. The information accumulated thus far has already been published in thousands of original papers, review articles, monographic series and books. The overall result of these investigations can be concentrated in the title of the present review. Vitamin A and its analogues, the retinoids, participate directly in several physiological functions, such as vision, growth, development and differentiation. These compounds have also found useful application in the cure of several serious dermatological diseases and in cancer therapy. Their activities are also widely exploited to study embryogenesis, teratogenesis and carcinogenesis. Recent advances ascribe to retinoic acid properties, which render it a putative candidate for the first vertebrate morphogen. These developments, in combination with progress made in the study of homeo box genes, open new ways towards elucidating the mode of action of retinoids at the molecular level. It is tempting to speculate that, understanding enough about the basic biology of retinoid action, might be beneficially exploited for the betterment of the mankind.

Main principles of the way to decompose an EPR spectrum of a multicomponent system, irradiated at 77 K, into separate radiation-induced paramagnetic centre signals are given. The decomposition is possible due to the computer assistant spectra processing, and is based on different properties of different paramagnetic centres, namely, on different thermostability of the centres, on different rate of relaxation, and on different photosensitivity. Concrete examples of the EPR spectrum decomposition into different free radical signals are given for cases of murine liver and spleen irradiated at 77 K. Radiochemical yields of different free radicals, induced by gamma radiation at 77 K in whole biological tissues, were defined. The data on nature and properties of the paramagnetic centres induced by radiation in biological tissues are shortly reviewed.

Relative electrophoretic mobility (REM) of alcohol dehydrogenases from equine hepatocyte cytoplasm was low probably due to the presence of a loop which consisted of 21 amino acid residues in the surface layer of the enzyme subunits. The REM of multiple molecular forms of alcohol dehydrogenases from yeast cell cytoplasm was higher as consistent with the absence of this loop in the surface layer of the enzyme subunits. Possible role of amino acid residues comprising the loop, in the formation of total charge and their effect on REM values of enzymes from the alcohol/polyol dehydrogenase family are discussed.

The antitumor and toxic effects of methylnitrosourea (MNU) are determined through its metabolic pathways. In organism MNU is subject to hydrolytic decomposition and denitrosation. It has been shown in vivo studies that MNU abdominal injections of therapeutic doses caused the inhibition of ribonucleotide reductase in mouse spleen, and therefore the DNA synthesis depress. The effect may apparently contribute to antitumor property of MNU. It has been estimated that destruction of M2 subunit of the enzyme is occurred. The relation between the loss of ribonucleotide reductase activity and the inhibition of protein synthesis was discussed. Besides, the cancerogenic and mutagenic properties of MNU were discussed as a result of imbalance of DNA precursor pools. Changes in contents of Fe(3+)-transferrin, ceruloplasmin, methemoglobin in blood and spleen of animals after MNU injections have been found. The changes were reversible after single MNU injection and became irreversible after multiple injections.

Stimulating effect of 1-ethoxysilatrane on healing processes of experimental stomach ulcers was studied in rats. 1-ethoxysilatrane inhibited lipid peroxidation in blood and stomach wall tissues, interacted with artificial membranes, and affected the rate of mitochondrial respiration in liver. A hypothesis is put forward on the membranotropic effect of 1-ethoxysilatrane which underlies its ulcerostatic effect.

Heparin/acetylsalicylate complexes (1:9 and 10:1) were obtained in vitro. Single or chronic (7-8 days) per os administration to white rats of 0.1% solution of the heparin/acetylsalicylate complex (0.3 ml/200 g body weight) enhanced anticoagulative properties of blood plasma, increased the fibrinolytic activity in respect of stabilized fibrin, and diminished the thrombin-induced platelet aggregation.