Biomedical subjects

G I Muzya

Publications and source records attributed to G I Muzya.

9 recordsLinked to original sources

PubMed2000

Bioactive amide of prostaglandin E1 and ethanolamine plasmalogen analog of platelet-activating factor inhibits several pathways of human platelet aggregation.

The influence of an amide of prostaglandin E1 and ethanolamine plasmalogen platelet-activating factor analog 1-O-alk-1;-enyl-2-acetyl-sn-glycero-3-phospho-(N-11alpha, 15alpha-dioxy-9-keto-13-prostenoyl)ethanolamine (PGE1-PPAF) on platelet-activating factor (PAF)-, ADP-, and thrombin-induced human platelet aggregation has been studied. It was found that PGE1-PPAF inhibits the PAF-, ADP-, and thrombin-induced platelet aggregation in platelet-rich plasma. 1-O-alk-1;-enyl-2-acetyl-sn-glycero-3-phosphoethanolamine inhibited PAF-induced aggregation up to 50% but had no influence on platelet aggregation induced by ADP or thrombin. The ethanolamine plasmalogen analog of PAF 1-O-alk-1;-enyl-2-acetyl-sn-glycero-3-phospho-(N-palmitoyl)ethanolami ne, having a palmitoyl residue instead of PGE1, did not inhibit platelet aggregation induced by PAF, ADP, or thrombin. We propose that inhibition of human platelet aggregation by PGE1-PPAF is mediated by its action on platelet PAF-receptors and the adenylate cyclase system.

Alprostadil↗

PubMed1999

Mechanisms of interaction of a plasmalogenic analog of platelet-activating factor with human platelets.

The interaction of a plasmalogenic analog of platelet-activating factor (1-O-alk-1;-enyl-2-acetyl-sn-glycero-3-phosphocholine; 1-alkenyl-PAF) with human platelets was studied. 1-Alkenyl-PAF induced an increase in intracellular Ca2+ concentration and inhibition of adenylate cyclase at significantly higher concentrations than PAF. 1-Alkenyl-PAF inhibits PAF-induced platelet aggregation but has no effect on ADP- or thrombin-induced aggregation of human platelets. In contrast to PAF, 1-alkenyl-PAF increases [3H]PGE1 binding with human platelets. The properties of 1-alkenyl-PAF as an agonist or antagonist of PAF receptors apparently depend on its concentration in the cell medium. Under physiological conditions 1-alkenyl-PAF might be a natural PAF antagonist acting in the human cardiovascular system.

Adenylyl Cyclase Inhibitors↗

PubMed1998

The bioregulatory role of platelet-activating factor in intracellular processes and cell-cell interactions.

The role of platelet-activating factor (PAF, a phospholipid compound) in regulation of cell functions and cell-cell interactions is reviewed. The biological effects of PAF on platelets, neutrophils, basophils, eosinophiles, lymphocytes, and endothelial cells are described. Mechanisms of cell activation by PAF are discussed. Interactions of PAF with other biological regulators (prostaglandins, leukotrienes, NO, tumor necrosis factor, and interleukins) are considered.

Animals↗

PubMed1997

Ether lipids and platelet-activating factor: evolution and cellular function.

This review considers the relation between the evolution of ether lipids and platelet-activating factor (PAF) in living organisms for the first time. Ether lipids are shown to be the main structural lipid components in the cells of the most primitive organisms on the Earth; during evolution they were gradually substituted for lipids with ester and vinyl bonds. Synthesis of PAF has been found in some bacteria, protozoans, yeasts, plants, marine invertebrates, lower vertebrates, and mammals. The regulatory role of PAF is suggested to already appear in protozoans and later be maintained during the subsequent evolution of living organisms. During evolution, functions of PAF in the cell have been changing and enlarging, while ether lipids have been gradually losing their role as the main structural lipid component of the cells of living organisms.

Animals↗

PubMed1988

The interaction of prostaglandins with serum low-density lipoproteins.

The interaction of human serum low-density lipoproteins (LDL) with various types of prostaglandins (PG) was studied using equilibrium dialysis, steady-state fluorescence polarization spectroscopy and photolabeling methods. Low concentrations (10(-13)-10(-9) M) of PGE1 and PGF2 alpha were shown to induce specific rearrangements of the lipids on the LDL surface, whereas the closely related PGE2 and PGF1 alpha had no effect. With fluorescent labeled LDL, the PGE1-induced changes of the steady-state fluorescence polarization (P) were shown to be time- and concentration-dependent, saturable and reversible. However, equilibrium dialysis revealed a very low binding capacity of LDL for PGE1 (approx. 1 prostaglandin molecule per 600 LDL particles). Approximately the same PGE1 concentration was sufficient to cause maximal changes of P, to enhance the binding to apolipoprotein B of a photoreactive sphingomyelin analogue inserted into the LDL surface and to alter the thermal phase behavior of the LDL surface lipids. It is proposed that the LDL surface rearrangement caused by prostaglandins is due to the interaction of prostaglandins with apolipoprotein B, resulting in formation of short-lived complexes. The mechanism of this interaction is discussed in terms of the non-equilibrium ligand-receptor interaction model proposed earlier to explain the interaction of prostaglandins with high-density lipoproteins (Bergelson, L.D. et al. (1987) Biochim. Biophys. Acta 921, 182-190). It is suggested that direct prostaglandin-lipoprotein interactions may play a role in the homeostasis of cholesterol.

Alprostadil↗

PubMed1987

The interaction of prostaglandins with high-density lipoproteins: a non-equilibrium model of ligand-receptor interaction.

Using high-density lipoproteins (HDL) labeled with a fluorescent phospholipid probe (an anthrylvinyl-labeled analogue of sphingomyelin) it was found that low amounts (10(-12) M) of the prostaglandins E1 and F2 alpha induced different structural changes of the HDL surface, whereas prostaglandin E2 had no effect. The effects of prostaglandin E1 on HDL were largely paralleled by those of this prostaglandin on synthetic recombinants prepared from apolipoprotein A1, phospholipids and cholesterol. The prostaglandin E1-HDL interaction resembled that of a ligand with a receptor site because it was specific, reversible, concentration- and temperature-dependent and saturable. However, the maximal HDL retaining capacity for prostaglandin E1 as determined by equilibrium dialysis was very low, and a single prostaglandin E1 molecule was able to induce structural changes in a large number of discrete lipoprotein particles. To explain this remarkable fact, a non-equilibrium model of ligand-receptor interaction is proposed. According to this model in open systems characterized by a short life-time of the ligand-receptor complex, high diffusion rates of the ligand and long relaxation times which exceed the interval between two successive ligand-receptor occupations, the ligand-induced changes will accumulate, resulting in amplification of the primary biological signal. It is emphasized that the low mobility of lipids constituting the environment of the receptor protein plays a critical role in this type of signal amplification.

Alprostadil↗

PubMed1987

Influence of prostaglandins on the lipid transfer between human high density and low density lipoproteins.

Prostaglandin (PG) E1 was demonstrated to stimulate the transfer of phosphatidylcholine and cholesterol esters from human high density lipoproteins (HDL3) to low density lipoproteins (LDL). The enhancement effect of PGE1 on the interlipoprotein lipid transfer was seen at low PG concentrations under conditions of spontaneous exchange as well as in the presence of lipoprotein-depleted plasma, or partly purified plasma lipid exchange protein. PGE2 and PGF2 alpha showed no significant influence on the interlipoprotein lipid transfer. Evidence is presented suggesting that the PGE1-induced stimulation of interlipoprotein lipid exchange results in enhancement of LCAT-catalyzed cholesterol esterification in plasma. It is proposed that the effect of PGE1 is due to the previously described PGE1-induced reorganization of the HDL surface [(1984) FEBS Lett. 173, 291-293] and that PG-lipoprotein interaction may be a factor regulating cholesterol homeostasis.

Alprostadil↗

PubMed1984

Interaction of prostaglandin E1 with human high density lipoproteins.

Prostaglandin E1 has been shown to interact with serum high density lipoproteins (HDL) in a manner resembling the interaction of a ligand with a high affinity binding site. The presence of 10(-12)-10(-10) M prostaglandin E1 induces a rearrangement of the HDL surface lipids and probably influences the biological functions of the lipoproteins.

Alprostadil↗

PubMed1982

A sphingomyelin transfer protein in rat tumors and fetal liver.

The binding of the disaccharides methyl beta-D-lactoside and 2-acetamido-2-deoxy-3-O-(beta-D-galactopyranosyl)-beta-D-galactopyranose [beta-D-Gal-(l leads to 3)-D-GalNAc] to peanut agglutinin was studied by ultraviolet difference spectroscopy. The magnitude of the difference spectra varied with the concentration of the carbohydrates; association constants and thermodynamic parameters were determined from titration experiments at different temperatures. The enthalpy and entropy changes for binding of methyl beta-D-lactoside were found to be delta H degree = -65 +/- 4 kJ mol-1, delta S degree = -156 +/- 14 J mol-1 K-1. For beta-D-Gal-(1 leads to 3)-D-GalNAc the observed thermodynamic parameters were delta H degree = -78 +/- 5 kJ mol-1, delta S degree = -177 +/- 16 J mol-1 K-1. For both disaccharides, the enthalpy change upon binding to the lectin is much larger than found for the binding site on peanut agglutinin. The observed parameters are compared with those found for the binding of monosaccharides and oligosaccharides to other lectins and to lysozyme. Molecular models of the minimum energy conformers of beta-D-Gal(1 leads to 3)-D-GalNAc and methyl beta-D-lactoside are used to interpret the interaction of these, and structurally related ligands, with the peanut agglutinin binding site.

Androgen-Binding Protein↗