PubMed Health⌕ Search

Biomedical subjects

O V Alekseev

Publications and source records attributed to O V Alekseev.

12 recordsLinked to original sources
PubMed1982

[Role of cAMP in regulating the shape of thrombocytes].

Preincubation of platelet suspension with dbcAMP during 2 minutes inhibited the ADP-induced change in platelet shape. An increase of the cAMP content in the cell induced by papaverine inhibiting phosphodiesterase also blocked the change in the shape caused by ADP and prostaglandin E2 (PGE2). Incubation of platelets in medium with pH 9.0 or addition of PGE2 produced a stable change in the shape of the cells. The action of dbcAMP or papaverine on the changed cells accelerated the recovery of the native shape and the content of membrane-bound calcium.

Animals↗
PubMed1982

[Effect of prostaglandins E1 and E2 on thrombocyte form and aggregation].

Preliminary incubation of platelets with prostaglandin E1(PGE1) led to the inhibition of changes in platelet shape caused by ADP. PGE1 also blocked changes in the content of membrane-bound calcium in platelets, which are known to take place under ADP-induced changes in platelet shape. Stable changes in platelet shape were observed on incubation in the medium with pH 9.0. Addition of PGE1 in this case stimulated the normalization of the cell shape. PGE2 alone produced changes in the platelet shape and decreased the content of membrane-bound calcium. Simultaneous addition of PGE2 and ADP prevented the recovery of the native shape of the cells.

Adenosine Diphosphate↗
PubMed1981

[Erythrocyte interaction during aggregation according to scanning electron microscope findings].

Scanning electron microscopy was used to study red cell aggregation caused by intravascular injection of dextran (m. w. 500 000). Two types of aggregates were revealed. Type 1 was represented by aggregates of red cells with no substantial change in the form while type 2 by aggregates with the wrinkling of the surface of red cells and enlarged area of red cell surface contacts. Both types are prone to disaggregation after injection of rheopolyglucin.

Animals↗
PubMed1981

[Mast cells and vascular permeability in experimental aseptic peritonitis in the rat].

Mast cells and vascular permeability were examined in experimental aseptic peritonitis induced by intraperitoneal injection of starch into rats. It was established that derangement of vascular permeability in the inflammatory focus was consequent on degranulation of mast cells and release of inflammatory mediators. The model of the inflammation suggested enables the local focus to be created, with no mast cells seen for a long period of time (at least for 3 weeks).

Animals↗
PubMed1981

[Relation between changes in platelet shape, calcium balance and the separating effect of cytochalasin B].

Platelets were stimulated in vitro by different ADP concentration (10(-7)--10(-9) M). Scanning electron microscopy, light transmission recording and the Ca-sensitive fluorescent probe, chlortetracycline, were used to study the time course of changes in the shape, aggregation and the amount of membrane-bound calcium during ADP activation. It was found that ADP (10(-7)--10(-8)M) causes reversible changes in the shape of platelets without disturbing their aggregation. The changes in question were accompanied by phasic alterations of the amount of membrane-bound calcium.

Adenosine Diphosphate↗
PubMed1976

[Modeling microcirculatory disorders using an ultraviolet laser].

Reactions of microvessels and mast cells to laser irradiation were studied in rat mesentery by applying the method of intravital microscopy. An ultra-violet laser (gamma=337 nm) was used. The diameter of the laser beam was changed from 2 to 100 mum. Different irradiation doses provoked either an increase of vascular permeability or thrombus formation or hemorrhage. Apart from the vascular wall injury, factors accompanying the damage of red blood cells and other cells of the blood may play a role in the process of thrombus formation. Changes of the vascular diameter and permeability after laser irradiation of mast cells are probably connected with the release of histamine and serotonin contained in them.

Animals↗
PubMed1976

[Ultrastructural analysis of preparations impregnated with silver salts].

The work was devoted to the ultrastructural analysis of the neurohistological preparations. Sections of the tissue from the precardial parts of the pulmonary and caval dog veins were impregnated with silver salts after Campos and embedded in the araldite by a special method. Electronmicroscopi studies showed reduced silver adsorbed by the tissue of the impregnated preparations to exhibit a granular structure (the granules were 30-400 A in size). The largest of them were revealed in the axoplasm of the myelinated and unmyelinated nerve conductors, whereas the smaller ones found in various cellular and fibrous formations of the tissue substrate; silver granules were as a rule absent within the thickness of the myelin sheath. The noted regularities of adsorption and distribution of the silver granules in the impregnated preparations caused a morphologically expressed phenomenon of argentophilia.

Animals↗
PubMed1975

[The role of mast cells in vascular permeability disorders in rats subjected to immobilization stress].

Disturbances of vascular permeability were studied by the "vascular labeling" technique in the mesentry during the 24-hour immobilization of rats. Administration of dimebolin (an antihistaminic preparation) decreased the number of labeled vessels and labeling intensity. This effect was expressed in the presence of mast cells only and was accompanied by the mast cell degranulation. The authors suppose that the mast cells contain a substance preventing the disturbance of vascular permeability and released during degranulation. Such substance might be heparin. Experiments showed that small doses of heparin failed to produce such effect. These results allowed one to conclude that mast cells played a double role in the mechanisms of disturbance of vascular permeability during immobilization--the damaging (by the action of histamine and serotonine) and the protective (by the released heparin) action.

Animals↗