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Biomedical subjects

V A Berezin

Publications and source records attributed to V A Berezin.

At least 19 recordsLinked to original sources
PubMed1996

Histological studies of atrazine toxicity on the thyroid gland in rats.

Little is known about the toxic activity of the atrazine (a herbicide, commonly used in agricultural production) on the thyroid gland. In this study the compound was administered orally in female albino rats at sublethal exposure equivalent to 0.2 LD50 doses for 6 and 12 days. At termination of dosing the anesthetized animals were killed and blood was drawn for the determination of serum triiodothyronine (T3) and thyroxin (T4). A dose-dependent decrease of serum T3 concentration was observed in all the groups (control: 0.57 nmol-L-1; 6 days: 0.35 nmol-L-1; 12 days: 0.21 nmol-L-1). The thyroid gland was examined light-microscopically. Bouin's solution-fixed thyroids were embedded in paraffin and sections cut at 6 microns, stained separately with toluidine blue according to Slinchenko's method. Histologically in experimental groups epithelium featured small cuboidal cells and occasional structures of the follicles confluence within epitheliomers. A dose-dependent changes of the following parameters were observed: (a) increasing of number of follicle-building thyroid cells; (b) increasing of follicular volume; (c) decreasing of nucleus volume. Investigation of the whole population of thyroid mast cells disclosed no change in degranulation intensity. By contrast, degranulation intensity was decreased in perifollicular mast cells from groups treated with atrazine in dose-dependent manner. There are no changes observed in degranulation of stromal mast cells. These results suggesting that differences in response to the atrazine might account for an aspect of the functional heterogeneity within the rat thyroid mast cell population.

Animals↗
PubMed1995

Neural cell adhesion molecule (N-CAM) distribution may predict the effect of neurotoxins on the brain.

The neural cell adhesion molecule (N-CAM) is a convenient neurospecific marker for investigating the effects of neurotoxins on cell migration, cell recognition and differentiation of neurons during development. In this report, we discuss the developmental toxicity of valproic acid studied by two different approaches (the immunochemical detection of N-CAM content and polypeptide composition, and immunohistochemical analysis of N-CAM topography). Immunohistochemical analysis of distribution of N-CAM as a surface marker on the neural cells predicted the effect of the neurotoxin.

Animals↗
PubMed1994

[Blood proteinase inhibitors and cathepsin D in diffuse peritonitis].

There were 52 patients with a diffuse peritonitis examined. The level of a proteinases alpha 1-inhibitor, alpha 2-macroglobulin, trypsin inhibitor, cathepsin-D was studied. Results witnesses the high activity of proteinases inhibitors cathepsin-D in the early, postoperative period. The level of alpha 2-macroglobulin and cathepsin-D in an elderly and senile patients approximated to normal values up to the 7-9th day after the operation. The dependence of proteinases inhibitors and cathepsin-D contents from the severity of peritonitis course, the number of interventions done to the patient, and the use of autologous blood photomodifization in the complex of treatment were not revealed.

Age Factors↗
PubMed1994

A novel method for evaluation of carbohydrate-binding activity: enzyme-linked carbohydrate-binding assay (ELCBA).

A highly sensitive method for detection of the carbohydrate-binding activity of proteins is described. The method is based on interactions of carbohydrate-binding proteins, immobilized on a solid phase, with an enzyme-labeled soluble polysaccharide (peroxidase conjugated glycosaminoglycans-heparin, chondroitin sulfate or hyaluronic acid. Binding capacity was measured spectrofotometrically after enzymatic reaction with chromogenic substrate. The reliability of the assay was tested by use of two heparin-binding proteins-i) fibronectin (soluble) and ii) heparin-binding protein purified from the human brain (water-insoluble). Binding of heparin was dependent on metal ions, detergents and urea. The assay is believed to be applicable for the identification and characterization of a variety of carbohydrate(glycosaminoglycan)-binding proteins, especially, when traditional methods can not be applied (e.g., when proteins are water-insoluble).

Brain↗
PubMed1993

Changes in the neural cell adhesion molecule patterns on the rat glial cell surfaces with development and contact formation in vitro.

In monolayer cultures of newborn rat hippocampal cells, immunogold-labelling at the electron microscope level was used to study quantitatively the neural cell adhesion molecule (N-CAM) arrangement on the surface of glial soma and processes on 5 and 12 days in vitro (DIV). Four corresponding samples of micrographs were formed. To quantify the labelling, a stochastic geometry approach was used. Spectra of lateral distances between labels as well as simulated images of the surface label arrangement (invisible in micrographs) were derived and compared. The data show that, on both 5 and 12 DIV, N-CAM density on the surface of processes is approximately 2 times higher than that in somata; 12-DIV cells showing a lower (approximately 25%) N-CAM surface density as compared with the 5-DIV cells. This suggests that N-CAM expression in glia surfaces decreases while the cells form contacts, and N-CAM sorting between soma and processes remains stable. The simulated topographies of the lateral N-CAM arrangement might highlight fundamental mechanisms that underlie formation of the neural network.

Animals↗
PubMed1993

Lateral patterns of the neural cell adhesion molecule on the surface of hippocampal cells developing in vitro.

In monolayer cultures of hippocampal neurons from newborn rats, an immunocytochemical quantitative study was carried out to investigate age-dependent arrangement of the neural cell adhesion molecules in different parts of cell membranes. On the fifth and 12th day in vitro, neural cell adhesion molecules were labelled with specific antibodies and protein A conjugated to colloidal gold particles. Samples of randomly selected electron micrographs that displayed labelled membrane fragments of cell bodies, growth cones, and axons were numerically analysed for the five- and 12-day in vitro neurons. Neural cell adhesion molecules surface topography was quantitatively described and compared, using a statistical stereological approach. The mean surface density of labelled neural cell adhesion molecules was found to be approximately 2.5 times higher in growth cone membranes relative to somatic and axonal membranes in five-day in vitro neurons. By the 12th day in vitro, this density decreases in somatic membranes (approximately 18%) and increases in axonal membranes (approximately 60%). Representative spectra of lateral intervals between labels as well as images that show typical topography of label on membrane surfaces were simulated. The results revealed regular patterns of neural cell adhesion molecules on the somatic surface and allowed consideration of neural cell adhesion molecules arrangement in a view of membrane adhesion properties. Participation of cytoskeleton in neural cell adhesion molecules rearrangement is discussed.

Animals↗
PubMed1991

[Expression of glial fibrillary acidic protein in the developing human brain].

It was shown that the glial fibrillary acidic protein (GFAP) content in developing (fetal) human brain is sharply increased. The expression of GFAP was observed already on the 7th-8th week after gestation, the GFAP concentration being less than 0.05% in comparison with adult brain. GFAP can be immunohistochemically detected in radial glial cells. At early stages of development the presence of antigenic determinants of 68 kDa and 100 kDa polypeptides interacting with monoclonal antibodies alongside with native GFAP (51 kDa) and its low molecular weight forms was demonstrated. These antigenic determinants cannot be detected at later stages of development and are absent in adult brain. The data obtained testify to changes in the gene expression of intermediate filament proteins at early stages of human brain ontogenesis.

Antibodies, Monoclonal↗
PubMed1988

[Localization of glycoconjugates in tissues of mammals revealed by means of labeled lectins].

Histochemical peculiarities on binding of castor-oil plant, soybean and lentil lectins with tissues of the mucous membrane in the stomach, small and large intestine have been studied in the human being, rat, mouse, as well as the lectins mentioned and the maize agglutinin with the nervous tissue of the rat cerebral tissue. The reactions are carried out with nonfixed cryostat and deparaffinized histological slices. Lectins labelled with horseradish peroxidase are used. Certain specific peculiarities and differences concerning the lectin binding with tissues of the organs studied are determined. Predominant binding is noted of the soybean lectin with parietal and mucin-producing cells of the stomach, with epitheliocytes of the duodenal glands, with the brush border of the epithelial cells of the intestinal villi. The lentil and castor-oil plant lectins make contours of the basal membrane epithelium in the stomach and intestine. The lentil lectin also reacts with the germinative centers of the stomach lymphatic nodules and the castor-oil plant agglutinin--with the brush border of the small intestine epitheliocytes. The lectins used are predominantly bound with neurons of the subcortical formations of the rat brain and cerebral cortex. By means of labelled lectins of lentil, soybean, and castor-oil plant it is possible to reveal certain modifications of the rat small intestine glycoconjugates produced by means of the immortelle extract.

Animals↗
PubMed1988

[Identification and characteristics of concanavalin A-binding neurospecific glycoproteins in human brain and brain tumors].

Soluble and membrane-bound neurospecific Con A-binding glycoproteins from human brain and tumours were identified and characterized, using a procedure which included stepwise extraction with low and high ionic strength buffers, buffered. Triton X-100 and sodium deoxycholate followed by ConA-Sepharose column chromatography, SDS-PAAG electrophoresis and immunoblotting. Adsorbed antisera against different types of neurospecific glycoproteins were used. The bulk of neurospecific glycoproteins (11 and 13) were revealed in protein fractions extracted with low ionic strength buffers and Triton X-100. In astrocytomas and glyoblastomas, some neurospecific glycoproteins were absent. Some glycoproteins were found in tumours, but were absent in brain tissue. Soluble, 77 kD glycoprotein, 11 and 16 kD glycoproteins solubilized with high ionic strength buffers and intrinsic membrane-bound 51, 57, 61, 74 and 77 kD glycoproteins can be viewed as stable neurospecific markers in malignant brain tumours.

Brain Chemistry↗
PubMed1987

[Neurospecific proteins: potentials and prospects for their use in morphological research on tumors].

Data on the application of neurospecific proteins S-100, GFAP, D2 glycoprotein and neuron-specific enolase (NSE) in the differential tumor diagnosis are reviewed. S-100 protein and GFAP are found in well differentiated astroglial tumors. S-100 protein can be used as melanoma and Schwannoma specific marker. In malignant CNS tumors there is a decrease of S-100 protein content up to its complete disappearance, while the content of GFAP is variable. D2 glycoprotein is detected in gliomas and medulloblastomas, being absent in other brain tumors. NSE is invariably present in apudomas and was also found in the majority of investigated astrocytomas, ependymomas, glioblastomas and in some medulloblastomas.

Animals↗
PubMed1985

Isolation and studies of myxovirus glycoproteins.

The isolation of ortho- and paramyxovirus glycoproteins using a new nonionic detergent (MESK) is reported. MESK was shown to solubilize most of the viral envelope glycoproteins without decreasing their biologic activity. Solubilized glycoproteins are not contaminated by any internal viral proteins or by appreciable quantities of viral envelope lipids. The removal of MESK by dialysis resulted in the formation of glycoprotein micelles. The immunogenic activity of isolated glycoproteins was compared to that of virus particles. Immunization with isolated glycoproteins was shown to protect mice against a lethal influenza infection. Virions were treated with MESK in the presence of exogenous egg phosphatidylcholine, detergent was removed by dialysis and the glycoprotein was reconstituted in the vesicles. This reconstitution was accompanied by restoration of the haemolytic activity of Sendai virus proteins up to that of native virus particles. The level of activity, also the morphology and buoyant density of the vesicle were dependent on the protein/lipid ratio. MESK proved to be of value for the selective solubilization of the surface glycoproteins of animal enveloped viruses and their reconstitution in liposomes.

Animals↗
PubMed1985

[Neurospecific proteins in human malignant brain tumors].

The content of neurospecific proteins S-100, GFA and D2 was measured in malignant cerebral tumors by electrophoresis with the use of monospecific antisera. Concomitant measurement of proteins S-100 and GFA is a more reliable diagnostic criterion as to the tumor histogenesis than study of each protein alone. D2 protein appeared to be the most stable specific marker.

Biopsy↗
PubMed1984

[Immunochemical study of the degradation of circulating glycoproteins and the neurospecific membrane glycoprotein D2 by cathepsin D of the human brain].

Cathepsin D was isolated from human brain. A consecutive use of affinity chromatography on hemoglobin-sepharose 4B and column chromatography on hydroxylapatite resulted in a homogeneous enzyme (as was demonstrated by SDS polyacrylamide gel electrophoresis) with a molecular weight of about 48,000, 2800-fold purification and 3.4% yield. Incubation of serum proteins in the presence of purified cathepsin D resulted in a gradual decrease of immunoreactive forms of albumin, orosomucoid, transferrin, and other alpha 1, alpha 2 and beta-globulins. The degradation was revealed by crossed immunoelectrophoresis. Crossed affinity immunoelectrophoresis in the presence of ConA showed specific degradation of serum glycoproteins. Rocket immunoelectrophoresis with monospecific antisera raised against human adult brain glycoprotein D2 revealed a rapid and linear degradation of detergent-solubilized and partially purified human membrane glycoprotein D2 by purified cathepsin D. Incubation of glycoprotein D2 in the presence of cathepsin D (30 min, 37 degrees C) resulted in degradation of 95% of specific protein. An exposure of human brain membrane fragments to cathepsin D resulted in linear degradation of membrane-bound glycoprotein followed by an appearance of a soluble immunoreactive form of protein D2.

Blood Proteins↗
PubMed1984

[Tissue specificity of the human brain protein D2].

Protein D2 was isolated and purified from adult human brain by extraction with Triton X-100 as well as by chromatography on phenyl-sepharose, concanavalin A-sepharose, lysine-sepharose and hydroxylapatite. Specific rabbit antisera against purified protein D2 were raised. Crossed and rocket immunoelectrophoresis revealed an immunoreactive protein D2 in the fetal heart, fetal kidney and adult heart (8-15% of total content in adult brain tissue). Rocket-on-line immunoelectrophoresis revealed additionally small amounts of D2-like antigens in adult kidney (12%), adult liver (1.5%), and in adult lung and spleen (less than 1%). The differences in tissue distribution as revealed by rocket-on-line immunoelectrophoresis suggest the existence of special D2-like protein clone in some tissues with or several immunochemically identical domains.

Adult↗