Biomedical subjects
S A Gusev
Publications and source records attributed to S A Gusev.
[Structural-functional motifs of sterol 14-alpha demethylases (CYP51)].
CYP51 family of cytochromes P450 (sterol 14-alpha-demethylases) comprises the representatives from different kingdoms of living world, thus positioning itself as the most ancient member of the superfamily. In the course of the present research the collection of 36 full-length CYP51 amino acid sequences was submitted to cluster analysis. Each node of the clustering dendrogram corresponds to the groups of proteins, located on the branches descending from the node. By making the multiple alignment of each group of protein sequences we obtained the node-specific consensus sequences. The informational content of the consensus was defined as the presence of the compact conserved sites, the motifs. The assessment of informational content was computed using Sherman's non-parametric statistical criterion. The high informational content was observed for the 100% conserved consensus sequences of the following CYP51,s groups: fungi, animal+plant, plant+protista and bacteria. These selected consensus sequences were next aligned all together to get the final consensus for the whole family. To enrich the informational content of the CYP51 consensus the level of its conservation was dropped to 75%. Regions of statistically significant conservation were unraveled in the CYP51 consensus sequence. These regions (motifs) were then correlated with the information on secondary structure elements and substrate recognition sites reported for CYP51 from Mycobacterium tuberculosis. Seven motifs appeared to be obligatory for every CYP51 protein. The motifs thus obtained were searched for among all the known cytochrome P450 proteins. Some motifs were found to be absolutely specific for 14-alpha-demethylases, whereas others were common to different species of cytochromes P450.
Cytochrome P450 database.
This paper describes a specialized database dedicated exclusively to the cytochrome P450 superfamily. The system provides the impression of superfamily's nomenclature and describes structure and function of different P450 enzymes. Information on P450-catalyzed reactions, substrate preferences, peculiarities of induction and inhibition is available through the database management system. Also the source genes and appropriate translated proteins can be retrieved together with corresponding literature references. Developed programming solution provides the flexible interface for browsing, searching, grouping and reporting the information. Local version of database manager and required data files are distributed on a compact disk. Besides, there is a network version of the software available on Internet. The network version implies the original mechanism, which is useful for the permanent online extension of the data scope.
[A quantitative analysis of the regional organizational characteristics of the aortic endotheliocyte layer in normotensive and spontaneously hypertensive rats].
Using scanning electron microscopy and semiautomatic image analyser, regularities and quantitative changes were studied in endotheliocytes in three regions of thoracic aorta during ageing of normal and spontaneously hypertensive rats of the Kyoto-Wistar line. The data of morphometric analysis and the results of simulating endothelial cell monolayer changes, by means of construction of polyrow mosaics, suggest that the number of small endotheliocytes of normotensive rats in all aorta regions is lowered in the period from 2 to 10 months to increase then from 10 to 16 months. The endothelial cell monolayer changes occur as follows: the small endotheliocytes appear and then disappear, keeping their random distribution in the endothelial layer. Within the same period, in spontaneously hypertensive rats, the behavior of the endothelial layer in the region of intercostal arteria ostia and on the dorsal surface is similar to that in normal rats, being presumably associated with age changes. In hypertensive rats, on the ventral surface of the aorta, a relative number of small cells increases at the expense of small cell foci formation. Thus, the provided evidence points to a heterogeneity of responses of endothelial layers in different regions of the aorta on the constant elevation of pressure.
[The cholesterol content of biomembranes (an electron microscopic study)].
A new specific cholesterol marker and scanning electron microscopy were used to study the quantity and distribution of cholesterol in the artifical phospholipid membranes and in the plasmalemma of animal and human endotheliocyte and erythrocytes in health and in hypercholesterolemia.
[The characteristics of the absorption in the small intestine of 2 casein hydrolysates and of an equivalent amino acid mixture].
Using casein hydrolysates and the amino-acid mixture applied to mucosal or serosal surfaces, their effect on the transport of free glycine, glycine formed during glycyl glycine hydrolysis, and galactose, was studied in the small intestine. The data obtained suggest a mechanism of peptide transport in the enterocytes as well as a possibility of a regulatory effect of the peptides contained in casein hydrolysates on the transport of some basic nutrients.
Spatial organization of digestive and barrier functions of the small intestine (new hypotheses and data).
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[The hydrolases of the mucosal, submucosal and muscular layers of the small intestine and their functions].
Proceeding from the newly obtained evidence on the distribution of digestive enzymes in mucosal, submucosal and muscular layers of the small intestine in rats, a hypothesis has been formulated: in addition to the enterocyte enzyme complex forming the epithelial barrier, there seems to exist a postepithelial barrier formed by the enzymes localized in subepithelial structures. The efficiency of this second barrier was manifested by the study of the peptide hydrolysis and transport using everted intact and de-epithelialized intestinal sacs.
[Enzymatic-transport system of epithelial cells, stroma, and the muscle-serous layer of the rat small intestine].
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[The detection of the cholesterol of the erythrocyte plasmalemma by using a latex marker].
Using a new specific cholesterol marker (SCM) and scanning electron microscopy, the distribution of cholesterol in the plasmalemma of rabbit and human erythrocytes was studied. Investigation of SCM linking with the erythrocyte membranes with different cholesterol/phospholipid indices shows that the increase of cholesterol/phospholipid index of the erythrocyte membrane correlates with the increase in the number of SCM particles on the erythrocyte surface.
Localization of peptide hydrolysis in the enterocyte and the transport mechanisms of apical membrane.
1. The absence of the effect of anoxia on the hydrolysis rate of a number of dipeptides and one tripeptide by the intact and homogenized mucosa of the small intestine in different mammals (rat, mouse and guinea pig) has been demonstrated. 2. It has been shown that in rats anoxia inhibits intestinal transport both of free glycine and glycine formed during the hydrolysis of Gly-Leu, Leu-Gly, Gly-Pro but not Pro-Gly. 3. Data obtained using the anoxic criterion suggest that the systems of membrane hydrolysis of peptides with the subsequent absorption of released amino acids presents a dominant mechanism of protein assimilation under normal physiological conditions. 4. However, they do not exclude the possibility of the transport of peptides across the apical membrane of enterocytes.
[Study of the latex agglutination reaction using a light-scattering method].
Light scattering techniques as a method for monitoring latex agglutination test were under study. The model system, employed in the studies, consisted of a suspension containing polystyrene latex microspheres with tetanus antitoxin immobilized on them (carrier particles) and antitetanus serum (3000 IU). The studies helped define approaches to the choice of the optimal conditions for monitoring the latex agglutination test. Light scattering method has proved to be highly sensitive, its sensitivity essentially surpassing that of slide tests and permitting the detection of early agglutination stages.
[Morphological substantiation of selection of the method of surgical treatment of patients with prolapse of internal genital organs].
Morphology of uterine ligaments and the vaginal mucosa has been examined in 61 patients with uterine prolapse in order to provide guidelines for an optimum management with respect to tissue functional status. Specimens were obtained intraoperatively and examined in a usual microscope and a S-570 Hitachi scanning electron microscope (Japan). The study suggests that morphologic evaluation of the vaginal walls and uterine ligaments provides an exact measure of tissue status, offering an optimum choice of treatment in these patients.
[The enzymatic and transport systems of the enterocytes during the perfusion of isolated sections of rat small intestine with different substrates in a chronic experiment].
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[A quantitative analysis of regional features in the structure of aortal endothelial cells in short-term hypertension].
The results of quantitative analysis of regional differences in the structure of thoracic aorta endotheliocytes in normal and hypertensive rats are presented. Scanning electron microscopy and semiautomatic image analyser were employed in studying the cellular structure in three regions of aorta endothelial layer: dorsal and ventral surfaces and region of the intercostal arterial ostia. The data obtained show that in cases of a short-duration hypertension the most pronounced are the alterations in endotheliocytes of the dorsal surface. Thus, the results confirm the heterogeneity of the aortic endothelium under normal conditions and demonstrate that differences in overlapping of neighbouring endotheliocytes is the cause of the observed alterations in cases of hypertension.
[Identification of digitonin binding sites on the plasma membrane of the rabbit aorta endotheliocytes].
Specific reagents comprising digitonin bound to latex spheres were used as visual markers for the detection of cholesterol sites on the endothelial cell surface by scanning electron microscopy. The distribution of latex markers in the plasmolemma of the endothelial cells was investigated. These markers have strong bonds with the ligands. This interaction guarantees high specificity of binding between labeled markers and cellular membrane cholesterol.
[Detection of the intercellular borders of the endothelium using scanning electron microscopy].
Three different approaches for studying aorta endothelial cells by scanning electron microscopy (SEM) were compared to expose cell border lines and surface shape simultaneously. Staining of aorta probes with silver nitrate leads to more specific silver deposits at cell junctions, but unsatisfactory image resolution obscures any detail of cell junctions and other fine structural features. Endothelium impregnated with tannin-osmium showed enhanced cell junction detail, but this method resulted in formation of presumably artificial structures. Osmium tetraoxide was most optimal for impregnation of aorta probes, as it exposed well cell border lines, excluded artifacts of tannin-osmium staining, provided a good image resolution in SEM, and allowed to analyse the ultrastructural features of cell surface.
[Regional characteristics of the organization of the aortic endothelium (a quantitative analysis)].
By means of SEM-analysis in 110 microphotos (from 14 aortas of white rats) with the aim to estimate heteromorphism of the thoracic part endothelium, quantitative characteristics of endotheliocytes have been studied in the ventral and dorsal surfaces, and also around the ostia of the intercostal arteries. For the quantitative analysis organization of the lines of the interendotheliocyte borders is taken into account. Endotheliocytes around the ostium are more elongated but occupy less area and have less straight contours in comparison with cells in other regions; they have also greater variability. Essential differences in arranging the endothelial cells into the layer on the ventral and dorsal surfaces of the aorta are revealed.