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Biomedical subjects

L M Poliakov

Publications and source records attributed to L M Poliakov.

At least 19 recordsLinked to original sources
PubMed1996

[Effect of plasma lipoproteins and apolipoprotein A-I on lipopolysaccharide-induced production of reactive oxygen metabolites by Kupffer cells of the rat].

The effects of plasma lipoproteins on LPS-induced production of reactive oxygen intermediates (ROI) in Kupffer cells isolated from livers of zymosan-treated rats, have been studied. ROI production was low in normal Kupffer cells but increased 18-fold by LPS in Kupffer cells from zymosan-treated rats. However, preincubation of LPS with rat serum, low density lipoproteins, high density lipoproteins (HDL3) and apolipoprotein A-I (apoA-I) decreased the LPS-induced production of ROI by 1.2-, 1.3-, 2.8-, and 1.5-fold, respectively. In contrast, very low density lipoproteins and HDL2 had no significant effect on the LPS-induced production of ROI. These results provide evidence for LPS-HDL3 complex formation and suggest that HDL3 and apoA-I play an important role in host defense against endotoxemia and infection.

Animals↗
PubMed1993

[The receptor-mediated endocytosis of complexes of colloidal gold with high-density lipoproteins by the sinusoidal cells of the isolated rat liver].

Rat hepatic sinusoidal cells absorption of native high-density lipoproteins was studied by electron microscope. Visualization of the endocytosis process was achieved by binding of lipoprotein particles and colloidal gold. The study was carried out on isolated liver perfusing by oxygenated nutritional media which consist of colloidal gold-lipoproteins conjugates. Electron microscope analysis testifies that high-density lipoproteins are absorbed by hepatic sinusoidal cells by means of receptor endocytosis. Both Kupffer cells and endothelial cells have such receptors. Lipoproteins of this class reach hepatic cells in Disse's space through the endothelium, i.e. transcellularly unlike low-density lipoproteins which penetrate paracellularly--through the fenestrae and intracellular contact's ares.

Absorption↗
PubMed1992

[Lipid biosynthesis and metabolism of native and acetylated low density lipoproteins in macrophages stimulated by zymosan in vivo and in vitro].

The effects of zymosan on lipid metabolism in mouse peritoneal macrophages (MPM) in vitro and in vivo were studied with special reference to the following parameters: i) 14C-oleate incorporation into cholesteryl esters (CE), triglycerides (TG), and phospholipids (PL) in MPM incubated with low density lipoproteins (LDL) and acetylated LDL; ii) cholesteryl-14C-oleate-acetyl LDL uptake and 125I-acetyl LDL degradation; iii) oxidative modification of LDL. Zymosan administered to mice caused significant stimulation of 14C-oleate incorporation into CE, TG, and PL with no effect on 3H-cholesterol (Ch) incorporation into CE or 3H-glycerol incorporation into TG and PL in MPM. The 14C-oleate incorporation into cellular lipids was unaffected by 18-hour incubation of MPM with zymosan (100-500 micrograms/ml) but increased after incubation of unstimulated MPM with blood serum and peritoneal fluid harvested harvested from zymosan-treated mice. One possible explanation of this phenomenon is oleyl-CoA formation induction in cytokine-stimulated MPM in vivo. Zymosan decreased the Ch-14C-oleate-acetyl LDL uptake, 125I-acetyl LDL degradation, and Ch esterification in the presence of acetyl LDL in MPM both in vitro and in vivo. An increase in Ch esterification after incubation of MPM with zymosan for 6-18 hours in the presence of LDL was accompanied by an increase in lipid peroxidation of LDL and its electrophoretic mobility. The data obtained suggest that the macrophage acetyl LDL receptor pathway may be inhibited by zymosan and that cytokines released from zymosan-stimulated cells may influence the generation of foam cells.

Acetylation↗
PubMed1992

[Detection of apoprotein A-1 immunoreactivity in chromatin of rat hepatocytes].

The binding of 125I-labeled lipoproteins to subcellular structures of rat hepatocytes was studied. The protein component of HDL, LDL, and VLDL was found in large and small membranes, nuclei, mitochondria, lysosomes, microsomes, and cell cytosol. The presence in liver nuclear chromatin of proteins immunochemically related to apoA-1 was demonstrated by solid phase immunoenzymatic analysis, dot immunoanalysis, and immunoelectroblotting. The apoprotein A-1 immunoreactivity was detected in transcriptionally inactive total chromatin, transcriptionally active chromatin, and nuclear matrix. The specific apoA-1 immunoreactivity of transcriptionally active chromatin and nuclear matrix was two times as low as that of total and transcriptionally inactive chromatin. Immunoelectroblotting revealed two proteins possessing an apoA-1 immunoreactivity (M(r) 28 and 14 kDa). The 28 kDa protein was found in transcriptionally active chromatin and nuclear matrix, while the 14 kDa one--only in transcriptionally inactive chromatin. the roles of apoproteins in lipid transport to nuclei and the maintenance of chromatin in a transcriptionally active state are discussed.

Animals↗
PubMed1992

[Quantitative characteristics of interactions of blood lipoproteins and steroid hormones].

Human and serum lipoproteins interaction with steroid hormones (corticosterone and hydrocortisone) were studied. Methods of fluorescence quenching titration and equilibrium dialysis were used for quantitative evaluation of VLDL, LDL and HDL glucocorticoids binding ability. Association constants were found to be 0.6-2.0 x 10 M for corticosterone and 4.0-8.0 x 10 M for hydrocortisone. The number of binding sites ranged from 3 to 300 for different classes of lipoproteins. Our data suggest high specificity of serum lipoproteins binding with corticosterone and hydrocortisone.

Animals↗
PubMed1991

[The intracellular distribution of labelled lipoproteins in the tissues of rats under physical loading].

A study was made of the influence of a 3 hour physical loading on the intracellular distribution of 125I-labeled very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) in the rat tissues after intravenous injection. The uptake of VLDL by liver was decreased, that of LDL was not altered and that uptake of HDL was increased, Redistribution of labeled lipoproteins between the subcellular structures was found. Accumulation of labeled VLDL in cytosol, microsome and large membranes was observed in muscles. The radioactivity level of VLDL was decreased in lysosomes, whereas the level of HDL was increased, Physical loading increased the uptake of HDL in adrenal glands. Accumulation of radioactivity was found in cytosol and small membranes. The data confirm the important role of lipoproteins of cellular metabolism regulation.

Adrenal Glands↗
PubMed1991

[Determination of apoprotein B using the method of solid-phase immunoenzyme analysis].

Indirect solid-phase enzyme immunoassay was used to measure apoB in human blood serum. ApoB obtained by traditional gel filtration in sepharose 4B and high-performance liquid chromatography was used as an antigen. Anti-apoB antibodies were immunochemically identified. Working regimens for the components and conjugates employed were selected. ApoB level in human blood serum, determined by this method, has made up 0.83 +/- 0.1 g/l in men and 0.88 +/- 0.1 g/l in women.

Apolipoproteins B↗
PubMed1991

[Characteristics of binding and transport of benzo(a)pyrene by blood serum lipoproteins].

Binding and distribution of 3H-benzo[a]pyrene in lipoprotein fraction of rat blood serum were studied. The binding was enhanced in the row: LDL, VLDL, HDL, Kd lipoprotein-benzo[a]pyrene complexes had been calculated by means of tryptophan fluorescence quenching. It was found, that Kd value benzo[a]pyrene complexes with VLD was 1.5 x 10(-6) M, with LDL -6.6 x 10(-7) M and with HDL -4.2 x 10(-6) M. Radiolabeled benzo[a]pyrene uptake by rat organs and tissues was investigated after i.v. injection of benzo[a]pyrene-complexes with LP of different classes. High uptake activity was revealed for liver, adrenals and kidneys, whereas heart, spleen, thymus were characterized by low 3H-benzo[a]pyrene accumulation. Radioactivity distribution pattern was depended on the class of LP used for complexation. Ours data permit to evaluate the participation of lipoproteins in transport and metabolic pathways of xenobiotics in organism.

Animals↗
PubMed1990

[Solid-phase immunoenzyme analysis of apoprotein A-1].

The authors have optimized indirect solid-phase enzyme immunoassay for measuring human blood serum apoA-1. Immunochemical identification of the obtained apoA-1 and specific antibodies has been carried out, working regimens for the components and conjugates employed have been selected. Relationship between the method of preliminary treatment of the serum and the completeness of detected apoA-1 antigenic determinants is demonstrated. Normal blood serum apoA-1 level is 1.06 +/- 0.1 g/l in females and 1.05 +/- 0.1 g/l in male subjects.

Adult↗
PubMed1981

[Effect of cortisol, adrenaline and ACTH on the absorption and intracellular distribution of protein-labelled lipoproteins by rat liver and adrenal tissues].

One hour incubation of slices prepared from rat liver or adrenal glands with 125I labeled lipoproteins of different classes resulted in label binding and its penetration into the tissue cells. The greatest amounts of labeling were found in fractions of mitochondria, lysosomes, microsomes and the final supernatant. In relation to the weight unit, slices from adrenal glands consumed several times as much label as did liver slices. Epinephrine increased the amount of the label bound to the low density lipoproteins by several times in the fractions of large cell membranes, and decreased the 125I level in mitochondria. Cortizole increased the incorporation of the protein labeled lipoproteins very low density into the liver mitochondria. ACTH did not influence the incorporation or cellular distribution of the label in adrenal glands.

Absorption↗
PubMed1979

[Mechanism of regulation of steroidogenesis in the adrenals by blood serum lipoproteins].

It has been shown that high density lipoproteins obtained by ultracentrifugation and loaded with cholesterol and pregnenolone exert a stimulant effect on in vitro production of glucocorticoids by rat adrenals. Low density native lipoproteins possess an inhibitory effect connected with the protein component. The action of various blood serum lipoproteins on steroidogenesis in rat adrenals has significantly different mechanisms.

Adrenal Glands↗
PubMed1976

[Study of the relationship between the glucocorticoid function of the adrenal cortex and blood lipoproteins].

Single administration of hydrocortisone to rats led to elevation in the blood serum of lipoproteins of very low density; and repeated administration - of lipoproteins of very low density, low density and of high density. Lipoproteins with d less than 1.063 g/ml produced an inhibitory action on the production of steroid hormones by the adrenal glands of rats in vitro.

11-Hydroxycorticosteroids↗
PubMed1975

[Relationship between corticosteroids, catecholamines and electrolytes in rats kept on sodium-rich diet].

The changes in the content of catecholamines, electrolytes and corticosteroids were studied dynamically and simultaneously in rats under salt stimulation. Long-term maintenance of the animals on sodium-rich diets results in its accumulation in blood plasma and heart muscle, the tissue depot of catecholamines diminishing at the same time. The changes in the functional state of the adrenal glands and of the catecholamines content in the myocardium are of a phased nature. The activation of the glucocorticoid function of the adrenal glands on the 18th day of the experiment is substituted by its reduction on the 56th day. The presence of a distinct relationship between the functional state of the adrenal glands and the level af adrenalin in the heart indicates the regulatory role of glucocorticoids in this experimental situation.

11-Hydroxycorticosteroids↗
PubMedDate not supplied

Enzyme-linked immunosorbent assay for apolipoproteins A-I and B in the urine of patients with nephrotic syndrome.

Enzyme-linked immunosorbent assay (ELISA) has been used for measuring apolipoproteins A-I and B in the urine. ApoB is absent in urine of healthy subjects, and apoA-I is determined in trace quantity. In patients with chronic glomerulonephritis quantity of apoA-I in urine was 117 times as much as in control group. ApoB is present in urine of patients in considerable quantity (1528 +/- 315 micrograms/l). The ELISA method for determining apoA-I and apoB in urine makes it possible to evaluate the gravity of pathological process in kidney.

Adult↗