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N V Prokazova

Publications and source records attributed to N V Prokazova.

At least 19 recordsLinked to original sources
PubMed2000

Ganglioside-mediated metabolic synchronization of protein synthesis activity in cultured hepatocytes.

An ultradian oscillation of protein synthesis was detected by synchronization of metabolic activity in rat hepatocyte cultures. This oscillation occurs in dense cultures in fresh medium, but not in sparse ones. Metabolic synchronization of sparse cultures, however, was initiated by conditioned medium or addition of 0.3-0.5 microm of a mixture of bovine brain gangliosides to fresh culture medium along with either 0.06-0.2 microm GM1 or 0.1-0.2 microm GDIa. GTIb and GDIb did not produce oscillations, nor did human liver ganglioside GM3. High expression of GM1 ganglioside determinants in hepatocytes maintained in the conditioned medium purified polyclonal antibodies to GM1 was coupled with protein synthetic oscillatory activity, i.e. metabolic synchronization. Incubation of dense cultures with GM1-antibodies for 24 h decreased the amplitude of these oscillations. In sparse cultures maintained in fresh medium where protein synthesis showed no oscillatory pattern, GM1 expression was low.

Activity Cycles↗
PubMed1999

Plasma sialyltransferase activity in healthy subjects and atherosclerotic patients.

Plasma sialyltransferase activity measured by incorporation of cytidine 5;-phospho[14C]acetylneuraminic acid (CMP-NeuAc) into asialofetuin was twofold higher in patients with documented atherosclerosis than in healthy donors. Kinetic studies showed that the enzyme affinity for CMP-NeuAc is the same in donors and patients. Low activity of plasma sialyltransferase in donors may be due to low blood content of this enzyme.

Arteriosclerosis↗
PubMed1998

Autoantibodies to gangliosides in sera of atherosclerotic patients.

Using ELISA we studied the levels and clinical correlation of serum antibodies against gangliosides and 5-hydroxytryptamine (5-HT) in patients with atherosclerosis and clinical manifestations of cardiovascular disease. A range of 70-80% of the patients showed higher titers of anti-GM3(L) and anti-5HT as compared to normal serum. The anti-GM3(L) antibodies appeared to be directed mainly against GM3 present in platelets and were much less reactive against GM3 isolated from the aorta. We concluded that the antigens responsible for the elevated anti-GM3(L) and anti 5-HT levels in atherosclerotic sera are released by vessel-wall activated platelets. These results provide further evidence of on-going autoimmune processes in atherosclerosis. The content of total sialic (TS) and lipid-bound sialic acid (LBS) was measured in sera of patients with IHD and of similar numbers of healthy donors. In the patient groups the average TS and LBS concentration was about 25% higher than in the control group. These changes appeared to be associated with higher degrees of protein sialylation and larger amounts of LDL in the patient sera than in those of healthy controls.

Adult↗
PubMed1998

[Effect of lysophasphatidylcholine on sensitivity of the heart to acetylcholine and binding of quinuclidinyl benzilate to myocardial membranes].

Chemical nature of the blood serum factor exerting cholinolytic effect on the animal heart, was determined. The effect is due to the serum lipid component: lysophosphatidylcholine. The latter in concentration 1-25 microM suppresses the sensitivity of the frog perfused heart ventricle to acetylcholine. Phosphatidylcholine was found to protect the heart from the lysophosphatidylcholine effect. Lysophosphatidylcholine also affected the binding of the acetylcholine high affinity antagonist [3H]-quinuclidinylbenzilate to the rabbit atria cell membranes. The mechanism of this effect is related to an increased ability of muscarinic receptors to form oligomeric complexes in presence of lysophosphatidylcholine, the latter manifesting a positive cooperativity on binding to ligand.

Acetylcholine↗
PubMed1998

Effect of lysophosphatidylcholine on transmembrane signal transduction.

Lysophosphatidylcholine (LPC), 1-acyl-sn-glycero-3-phosphocholine, is well known as an intermediate of metabolism of phosphatidylcholine (PC), the main phospholipid component in all eukaryotic and many prokaryotic cells. LPC is produced as a result of PC hydrolysis by several isoforms of phospholipase A2 (PLA2) and in the reaction mediated by lecithin-cholesterol acyltransferase that transfers the fatty acid residue from PC to cholesterol. LPC is classified as a second messengers that is produced by activation of cytosolic hormone-activated PLA2. It was shown that LPC inhibits transmembrane signaling via receptors, which in their active form are linked to G-proteins. There is a viewpoint that LPC abolishes formation of the complex between the receptor and G-protein. The effect of LPC on protein kinase C (PKC) activation is considered in this review. It was shown that low (less than 20 microM) and high (more than 30 microM) concentrations of LPC activated and inhibited PKC, respectively. The mechanism of LPC-induced activation of PKC still remains unclear. However, the studies of the effect of LPC on signal transduction through the PKC-mediated pathway showed that LPC probably plays an auxiliary role. It was suggested that LPC may prolong the effect of the direct activators of PKC (such as 1,2-diacylglycerol or phorbol esters). The physiological role of the elevation of LPC level in tissues is associated with its ability to enhance or even evoke cell proliferation, stimulate adhesion and differentiation of lymphoid cells, have mitogenic effect on macrophages, activate human T-lymphocytes, initiate monocyte chemotaxis, decrease myocardial sensitivity to cholinergic stimulation, impair contractility of arterial smooth muscle, and modulate aggregation of platelets.

Animals↗
PubMed1998

[Determination of lipid composition of high density lipoproteins by thin-layer chromatography on silica gel].

Unidimensional chromatography in a thin layer of silica gel with two solvent systems for separation of the lipid extract of high density lipoproteins (HDLP) detected 10 lipid fractions in subjects with normal lipidemia. Four phospholipid fractions were identified: three main (phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin) and one minor, phosphatidylethanolamine. HDLP lipids include free cholesterol and its esters; three glyceride fractions are detected: mono- di, and triglycerides, and free fatty acids. The ratio of individual phospholipid fractions and of free to ester-bound cholesterol in HDLP determined by computer-aided densitometry of chromatograms coincides with the data obtained routinely. Such a method for assessing the HDLP lipid composition is useful in studies of HDLP in patients with disorders of HDLP metabolism and for assessing the changes in HDLP composition during hypolipidemic therapy.

Cholesterol↗
PubMed1998

Immunoreactivity of apolipoprotein B-100 and binding to LDL-receptor of phospholipase A2-treated low density lipoproteins.

Lipid--protein particles were obtained by treatment of low density lipoproteins (LDL) with phospholipase A2 from bee venom. Under these conditions, half of the phosphatidylcholine (PC) of LDL was changed to lysophosphatidylcholine (LPC). At the same time, the composition of other lipids and the apoprotein structure were unaffected. Three monoclonal antibodies (MAbs) against various apo B epitopes were used to test immunoreactivity of phospholipase A2-treated LDL (pl-LDL). The apo B epitope interacting with MAb 4C11 (amino acid residues 2377-2658) showed significantly decreased immunoreactivity. Increase in MAb 4C11 binding was demonstrated to depend on oxidation degree of LDL. Thus, changing of half of PC to LPC modified apo B translocation in the lipoprotein globule in an opposite manner as compared with changes induced by oxidative modification. A minor increase in immunoreactivity of pl-LDL with 1D1 MAb against a large middle part of apo B (residues 1297-3249) may be due to the effect of the change of surface lipid composition on the extent of immersion of apo B into the hydrophobic phase. No changes in the interaction of pl-LDL with MAb 2G8 (residues 3748-4306) were observed in comparison with native LDL. This fact demonstrates that 50% phospholipolysis of LDL does not affect the expression of apo B C-terminal residues in pl-LDL. Twofold increase in pl-LDL affinity to immobilized LDL-receptor was shown in contrast to LDL. The data indicate that LPC accumulation in LDL results in better elimination of LDL from the blood stream than in case of accumulation of oxidative products.

Antibodies, Monoclonal↗
PubMed1997

Incorporation and localisation of ganglioside GM3 in human intimal atherosclerotic lesions.

Immunohistochemical examination showed that sections of intimal atherosclerotic plaques contained cells and cell clusters as well as areas of extracellular matrix specifically stained with antibodies against ganglioside GM3. No immunohistochemical staining was observed in areas bordering the plaques where there was no histological evidence of atherosclerosis. To determine whether the ganglioside GM3 deposits in the intimal plaques derived directly from plasma or were synthesised by intimal cells. intimal plaque and plasma LDL were assayed for ganglioside GM3 fatty acid composition. This assay showed that more than 50% of the fatty acids of GM3 isolated from both atherosclerotic and normal intima are either minor fatty acids or those absent from LDL GM3. We conclude that the GM3 deposits present in intimal plaque arise in intimal cells and do not derive from plasma LDL.

Arteriosclerosis↗
PubMed1997

Effect of lysophosphatidylcholine on the structure and function of low density lipoproteins.

The treatment of LDL with bee-venom phospholipase A2 resulted in the formation of lipid-protein particles (phl-LDL) with an increased content of lysophosphatidylcholine (LPC). At the same time, the composition of other lipids and the protein structure remained unaffected. phl-LDL, as well as LPC, abolished the hormone-induced [Ca2+] increase in platelets and platelet aggregation induced by PAF, AMP and thrombin, whereas LDL produced no effect on the hormone-stimulated increase in the intracellular [Ca2+]. The effect persisted in a Ca(2+)-free medium, indicating that phl-LDL and LPC did not abolish the mobilization of intracellular stores with the above-mentioned inducers. Neither LPC no phl-LDL affected the [Ca2+]i level in platelets and suppressed the platelet aggregation evoked by tapsigargine, a specific inhibitor of endoplasmic reticulum Ca(2+)-ATPase, or by phorbol myristate acetate. The inhibitory effect depended on the LPC concentration and the time of platelet incubation with phl-LDL or LPC. The half-maximum efficient LPC concentrations were identical for LPC and phl-LDL (2-4 microM). The inhibitory effect was dependent on the LPC structure: lysophosphatidylethanolamine and phosphatidylcholine displayed no inhibitory effect. The results suggest that when added to washed platelets, free LPC and phl-LDL inhibit only the receptor-dependent increase of [Ca2+]i.

Adenosine Diphosphate↗
PubMed1995

[Autoantibodies to ganglioside GM3 and serotonin in blood serum in atherosclerosis].

Using ELISA method, the sera from 17 patients with atherosclerosis and 13 normal controls were examined for ganglioside- and serotonin-reactive antibodies. Gangliosides from human liver (GM31) and human aorta (GM3a) as well as GM2, GM1, GT1b, human brain cerebrosides and the BSA-serotonin conjugate (5-HT) were used as antigens. A group of patients showed statistically significant higher levels of anti-GM31 (82%) and anti-5-HT (71%) as compared to the control group. Taking into account the identical fatty acid composition of GM3 from human liver and platelets, one can assume that antibodies are produced against blood clot gangliosides in atherosclerotic patients' sera. This conclusion is supported by a high correlation (r = 0.06, p < 0.01) between the level of antibodies to 5-HT and GM31 in the sera of all patients. The sera of three patients with the highest content of antibodies to GM31 were shown to contain antibodies to GM3a and GT1b which were absent in control sera. No reaction with brain cerebrosides or GM1 and GM2 was detected in the sera of the examined persons. The differences in sera reactions with GM31 and GM3a can be explained as resulting from differences in the chain length of fatty acid residues of the ceramide moiety of gangliosides. The data obtained confirm the fact that antibodies to aorta gangliosides appear in the sera of atherosclerotic patients. Thus, the formation of atherosclerotic plaques leading to platelet activation, clot formation and ganglioside accumulation in aortic cells increase the levels of anti-ganglioside GM3 antibodies.

Aorta↗
PubMed1995

[Blood sialic acids in atherosclerosis].

Determination of the total (protein- and lipid-bound) sialic acid in blood sera of atherosclerotic patients (registered thickening of coronary vessels) and donors revealed that the concentration of the both types of sialic acids in the blood sera of atherosclerotic patients are increased. The concentration of total sialic acid in patients' sera was, on the average, by 20% higher than that in donors' sera. The identity of protein content in patients' and donors' sera suggests that under atherosclerosis serum proteins are sialated in a greater degree as compared to norm. The concentration of lipid-bound sialic acid in patients' sera is higher than that in donors' sera. However, calculated per blood cholesterol, the concentration of lipid-bound sialic acid is practically identical in both patient and donors, thus indicating that increased sialoglycolipid content in patients' sera correlates with increased lipoprotein content in these sera in comparison with norm.

Adult↗
PubMed1994

Gangliosides and atherosclerosis.

The ganglioside levels in atherosclerotic lesions of human aorta are considerably higher than those in unaffected areas of aorta, and atherosclerotic patients frequently have increased concentrations of serum gangliosides. The present review summarizes recent findings that suggest the possible involvement of aortic gangliosides in platelet activation and adhesion of platelets to the vessel wall. The effect of gangliosides on the structure of low density lipoproteins (LDL), on the interaction of LDL with macrophages and hepatic cells and on the LDL-regulated biosynthesis of cholesterol is also discussed. In vitro experiments have demonstrated that a major ganglioside of the intima of atherosclerotic aorta induces rapid adhesion, aggregation and spreading of platelets. Moreover, gangliosides present in elevated amounts in the intercellular space of atherosclerotic aortic tissue modify the surface structure and stimulate aggregation of LDL. Ganglioside-modified LDL are readily recognized and taken up by macrophages, while preincubation of LDL with low concentrations of gangliosides inhibits LDL binding to hepatic cells. Thus, ganglioside enrichment of LDL is likely to interfere with LDL clearance via the hepatic cells. Thus, ganglioside enrichment of LDL is likely to interfere with LDL clearance via the hepatic LDL receptor, and to stimulate binding of LDL to the scavenger receptor of macrophages. It is postulated that high ganglioside levels in the aorta and serum may be an additional risk factor in atherosclerosis.

Arteriosclerosis↗
PubMed1992

Characteristics and regulation of ganglioside-induced elevation of free cytoplasmic Ca2+ in human blood platelets.

We have found that gangliosides GD3 and GM3 induced rapid, reversible elevation of free cytoplasmic Ca2+ in fura-2-loaded human blood platelets. The effect persisted in Ca(2+)-free medium, indicating that gangliosides stimulated mobilization of intracellular stores. The action of gangliosides was concentration-dependent with EC50 of about 1 microM. The Ca(2+)-mobilizing effects of gangliosides were potentiated by epinephrine and inhibited by substances inducing activation of protein kinase C and cAMP-dependent protein kinases. Acidic phospholipids partially mimicked the Ca(2+)-mobilizing effects of gangliosides indicating that lipid head charge is essential for this activity. While the elevation of [Ca2+]i produced by arachidonic acid was almost completely blocked by aspirin pretreatment, the effects of gangliosides were diminished only 2-fold, indicating that gangliosides activate both aspirin-sensitive and aspirin-insensitive mechanisms of [Ca2+]i elevation.

Arachidonic Acid↗
PubMed1992

Neutral glycosphingolipid content and composition of cells from normal and atherosclerotic human aorta.

We have investigated the content and composition of neutral glycosphingolipids (GSLs) in the cells isolated by enzyme digestion from elastic-hyperplastic and musculo-elastic intimal layers of grossly normal and atherosclerotic regions of human aorta. We have detected three types of neutral GSLs in the intimal cells identified as glucosylceramide, trihexosylceramide and tetrahexosylceramide. We failed to detect lactosylceramide in the intimal cells. The cells of the elastic-hyperplastic layer of grossly normal regions contained trihexosylceramide and tetrahexosylceramide, while glucosylceramide was not detected. Considerable amounts of glucosylceramide were found, and the trihexosylceramide and tetrahexosylceramide content was increased in the cells isolated from atherosclerotic regions. The cells of the musculo-elastic layer of grossly normal intimal regions contained glucosylceramide, trihexosylceramide and tetrahexosylceramide. Cells of the musculo-elastic layer of the fatty streak contained noticeable higher amounts of glucosylceramide, as well as greater amounts of trihexosylceramide and tetrahexosylceramide. Cells of the musculo-elastic layer of the plaque also appeared to contain more glucosylceramide, tetrahexosylceramide, but less trihexosylceramide as compared with grossly normal regions. In both cases cells of the fatty streak exhibited the highest total amount of neutral GSLs, but at the same time the neutral GSL composition of the fatty streak was not similar to GSL composition which is known for human blood monocytes. These findings indicate that elevation of neutral GSL level is observed in cells from atherosclerotic lesions of human aortic intima.

Adult↗
PubMed1991

Interaction of low-density lipoproteins with gangliosides.

The ganglioside uptake capacity of human serum low-density lipoproteins (LDL), the mode of ganglioside-LDL binding, and the influence of gangliosides on the floatation properties, size distribution, stability and fluorescence of LDL were investigated. The data obtained suggest that both hydrophobic and electrostatic forces are involved in formation of ganglioside-LDL complexes, but the former appear to be more important. Although association of gangliosides with LDL is predominantly unspecific, nonsaturable, and weak, a small saturable component due to specific ganglioside-apolipoprotein binding, also appears to be involved. In the presence of gangliosides the lipoprotein particles aggregate, the intrinsic fluorescence of LDL and their interaction with antibodies against apo-B change indicating that the state of apo-B [corrected] is modified by gangliosides.

Antigen-Antibody Reactions↗
PubMed1991

Ganglioside GM3 stimulates the uptake and processing of low density lipoproteins by macrophages.

Preincubation of low density lipoproteins (LDL) with low concentrations of the ganglioside GM3 (1-2x 10(-5) M/2.5 x 10(-6) M LDL-protein) results in an increase of LDL-uptake, enhances cholesterol accumulation and cholesteryl ester formation by macrophages. At the same time the lysosomal degradation of LDL in macrophages was inhibited under these conditions. These effects depended on the ganglioside structure and concentration. It is suggested that the effects observed could be caused by GM3-induced modification of LDL to a form that becomes recognized by macrophages.

Animals↗
PubMed1990

[Phospholipids and glycosphingolipids in cultured skin fibroblasts from healthy donors and patients with systemic scleroderma].

A comparative study of phospho- and glycosphingolipids of cultured skin fibroblast from healthy donors and from patients with systemic sclerodermia (SSD) was carried out. It was shown that the total phospholipid content in SSD fibroblasts is elevated. No significant changes in the concentration of neutral glycosphingolipids were observed. The ganglioside composition of SSD cell cultures differs significantly from that of healthy donor cells. The concentration of the gangliosides, GM3 and GM1, is decreased; no ganglioside GD1a was found in SSD fibroblasts. The data obtained are suggestive of changes in the properties of fibroblast surface which can be manifested both in the impaired reception of matrix proteins and in the impairment of basic properties of the membrane. These changes are well correlated with the results of previous studies on the AMP cyclase system.

Adult↗