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Biomedical subjects

W Ovtscharoff

Publications and source records attributed to W Ovtscharoff.

At least 37 records · Page 2Linked to original sources
PubMed1990

Anionic sites in the myelin sheath as shown by cationized ferritin.

The distribution of anionic sites in the myelin sheath of sciatic nerves of rabbits was studied using cationized ferritin. Ferritin molecules were observed on the cytoplasmic sides of the myelin lamellae stratified in paranodes and Schmidt-Lanterman clefts. In the compact myelin, ferritin molecules have not been found in the tissue sections. They have been observed on membranes of the myelin fraction. The significance of the localization of negatively charged groups on the cytoplasmic side of membranes is discussed.

Animals↗
PubMed1990

Localization of concanavalin A--binding sites on neuroepithelial cells in early newt's neurula after treatment with noradrenalin.

The concanavalin A (Con A)--binding sites on the cell surface of newt's neural plate and groove in norm and following treatment with noradrenaline (NA) were examined ultrastructurally. The changes in the distribution of Con A--binding sites as well as structural changes of endocytic vacuoles in experimental conditions were described. The present results suggest that the differences in the Con A--binding were caused by receptor interaction of the plasma membrane glycoconjugates and the applied neurotransmitter.

Animals↗
PubMed1989

Visualization of anionic sites using polyethyleneimine-metal complexes.

17 Polyethyleneimine-metal complexes were synthesized and 3 of them were tested cytochemically for visualization of negative tissue charges. The demonstration of the anionic sites was carried out on rat cerebral cortex and on frog cutaneous pectoral muscle. As controls, neuraminidase digestion, methylation, and omission of osmium-postfixation were used. The osmiophilic properties of polyethyleneimine, polyethyleneimine salts, and polyethyleneimine-metal complexes were discussed.

Animals↗
PubMed1989

Cytochemical localization of ATPase in axon-myelin-Schwann cell complex type.

ATPase activity was studied in the structures of axon-myelin-Schwann cell complex of sciatic nerves of rabbits of pre-and postnatal development. Positive reaction was observed on the plasma membrane, mitochondria and endoplasmic reticulum of Schwann cells, on the intraperiod lines of the compact myelin, in the split myelin lamellae in the paranodal regions and Schmidt-Lanterman clefts, in segment of outermost lamellae split off from the interparanodal myelin, in the mesaxons, in the loose myelin lamellae in the earlier stages of myelinization, on the axolemma (periaxonal space) and axoplasm. The ATPase activity on the Schwannian plasmalemma, axolemma and myelin sheath surface was found to be heterogeneously distributed. An accumulated of reaction deposits at the origin of the outer mesaxon, at the axoglial contacts as well as at the terminal part of the myelin sheath was respectively observed. Alterations of the enzyme activity distribution in axon-myelin-Schwann cell complex during rabbit's development were found to be associated with the growing myelin sheath and its node-paranode. Using controls with ouabain an attempt was made the possibilities of Wachstein and Meisel's method to be shown and the place of alpha+ form of Na+, K+-ATPase in the axon-myelin-Schwann cell Complex to be establish.

Adenosine Triphosphatases↗
PubMed1989

Structure of the plasmalemma of human spermatozoa after treatment with antispermatozoa serum and concanavalin A.

Human ejaculated spermatozoa were treated with antispermatozoa serum as well as with the same serum and concanavalin. A. At both experimental conditions clusters of intramembranous particles both on P-face and on E-face in the acrosomal and postacrosomal regions were seen. The clusters were with different form and size and were built up from different number of intramembranous particles. Large areas with single particles or in some cases devoid of these particles were found out.

Autoantibodies↗
PubMed1989

Soybean agglutinin-binding sites on the human sperm surface.

Some differences in the distribution of lectin-binding sites on the surface of the plasma membrane of acrosomal and postacrosomal regions and tail of ejaculated human spermatozoa were demonstrated by means of horseradish peroxidase labeled soybean agglutinin. The acrosomal region was more densely coated with labeled lectin in comparison with the postacrosomal region. Hapten inhibition with N-acetyl-D-galactosamine was used as control.

Binding Sites↗
PubMed1988

Demonstration of negative tissue charges by means of polyethyleneimine-metal complexes.

Three polyethyleneimine-metal complexes were synthesized and cytochemically tested for demonstration of negatively charged sites. For this purpose rat cerebral cortex synaptosomes were used. It was established that both types of polyethyleneimine-copper complexes labeled the synaptosomal membrane and synaptic vesicles with electron-dense granules, whereas the polyethyleneimine-lead complex marked the anionic sites with amorphous electron-dense material.

Animals↗
PubMed1988

A method for demonstration of lectin-binding sites using a blood group substance A/ferritin conjugate.

A new technique for demonstration of lectin-binding sites is proposed. At the 1st step of the method, the lectin binds the respective monosaccharide constituent of the glycoconjugate and at the 2nd step, the blood-group substance A-ferritin conjugate is used as a marker. The following lectins were tested: wheat germ agglutinin, soybean agglutinin, mistletoe lectin I, and concanavalin A. Human red blood cells were used as material. By means of control experiments, the specificity of the proposed technique was proved.

ABO Blood-Group System↗
PubMed1988

Ultrastructural cytochemical localization of 5'-nucleotidase activity in axon-myelin-Schwann cell complex.

5'-Nucleotidase activity has been localized at the ultrastructural level in the axon-myelin-Schwann cell complex. Sciatic nerves of rabbits of pre- and postnatal development were used. Positive reaction was found on the plasma membrane, basal lamina, cytoplasm, and finger-like processes of the Schwann cells; on the intraperiod lines of the compact myelin, on the surface of myelin sheath, in the split myelin lamellae in the paranodal regions and Schmidt-Lanterman clefts, in segments of outermost and innermost lamellae, split off from the interparanodal myelin, in the mesaxons (outer and inner), in the loose myelin lamellae in the earlier stages of myelinization; on the axolemma (especially in the nodal and paranodal segments), in the periaxonal space, axoplasm. The alterations of 5'-nucleotidase distribution were associated with the developing myelin sheath.

5'-Nucleotidase↗
PubMed1987

On the concanavalin A positive layer on the skeletal muscle fibre.

The localization and distribution of mannosyl and glucosyl residues on the extrajunctional sarcolemma of skeletal muscle fibres of frog, rat and new-born rat was studied by means of concanavalin A labelled with FITC and ferritin-concanavalin A conjugate. A strong fluorescent layer surrounding the muscle fibres was found out. Ultrastructurally concanavalin A binding sites were established on the outer surface of muscle cell membrane, on the basal lamina, on the space between them, as well as on the reticular lamina, which ensheeted the muscle fibre. The width of the concanavalin A positive layer was 0.3 to 0.7 micron. On the basis of intensity of the fluorescence, some differences in the content of mannosyl and glycosyl residues during ontogeny as well between both species was admitted.

Animals↗
PubMed1987

Changes of localization of lectin-binding sites on the intestinal epithelial cell surface membrane during differentiation of the columnar intestinal cells.

Light and electron microscopically localizations of Concanavalin A, Soybean Agglutinin, and Asparagus Pea Lectin-binding sites on the intestinal microvillous membrane were studied by means of horseradish peroxidase labelled lectins. The distribution of the lectin-binding sites was composed with the cell differentiation from the crypts to the tip of the intestinal villi. The visualization of lectin receptors in the mucin vesicles in the goblet cells was established as well. The controls for the determination of the specificity of reactions were carried out.

Animals↗
PubMed1986

A method for the fine-structural demonstration of lectin receptors.

A new two-step method using an Fc-fragment/ferritin conjugate as a marker for the visualization of lectin-binding sites on neuronal and other cell membranes is described. In this study of rat synaptosomes, three lectins were tested: concanavalin A, mistletoe lectin I and wheat germ agglutinin. The specificity of the method was proved by control experiments.

Animals↗
PubMed1986

Localizations of ruthenium red positive material in rabbit peripheral nerves.

The penetration and distribution of ruthenium red in the axon-myelin-Schwann cell complex of developing rabbit peripheral nerve fibers are investigated. Ruthenium red positive material is established in the axoplasm, axolemma, periaxonal space, major dense lines and intraperiod lines of the compact myelin, mesaxons, split peripheral myelin lamellae, Schmidt-Lanterman and longitudinal incisures, paranodal loops and axo-glial contacts, Schwann cell cytoplasm and basal lamina, nodal extracellular matrix, desmosome-like structures, endoneural collagen. Some features of the distribution of the contrast material in the developing myelin sheath are described. Regional differences of the axolemma and of the Schwann cell cytoplasm and plasmalemma are established. The prevalence of glycoproteins or glycolipids in the ruthenium red stained material in its different localizations is discussed on the basis of trypsin and hyaluronidase digestion performed.

Aging↗