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Biomedical subjects

L E Panin

Publications and source records attributed to L E Panin.

At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

[Lysosomes and lipoprotein metabolism in the liver].

Apoproteins were not hydrolyzed completely in liver cells after internalization of lipoproteins. They were accumulated in secondary lysosomes as a result of lipoprotein disintegration and reacted actively with lysosomal membranes, thus inducing pore-formation in the structures. Under these conditions lysosomal enzymes were not liberated into the environmental medium, while contact with the corresponding substrates was increased. Small molecular mass enabled the apoproteins to penetrate into cell cytoplasm, where they could interact with all the cytostructures: nuclei, mitochondria, microsomes and cytosol, carrying out their coenzyme properties.

Acid Phosphatase↗
PubMedDate not supplied

[Various mechanisms of lysosome involvement in the process of tissue injury].

Impairments in structural integrity of liver, heart and skeletal muscle lysosomes followed by necrotic and necrobiotic alterations in the tissues and secretion of active hydrolases in blood were detected under conditions of exhaustive physical exercises in rats when dose-dependent physical loading was studied. At the same time, in patients with hypertrophic cardiomyopathy physical loading, carried out as stepwise spiroveloergometry up to the submaximal heart rate, led to release of lysosomal enzymes into blood, which was not observed in healthy persons under similar conditions. The higher level of enzymes was found in circulation of the patients with most severe forms of the disease.

Acid Phosphatase↗
PubMedDate not supplied

[The mechanism of action of hydrocortisone and adrenaline on the hepatic lysosomal apparatus].

The mechanisms of hydrocortisone and adrenalin action on the structure and function of the lysosomal-vacuolar cell apparatus were studied in experiments on liver sections of Wistar rats. The sections were incubated in Krebs-Ringer bicarbonate buffer, pH 7.4 (95% O2 and 5% CO2) at 37 degrees C for 2 h. Hydrocortisone (10(-5) M) and adrenalin (10(-4) M), added to an incubation medium, were shown to produce a labilizing effect on lysosomal membranes, increasing free activity of acid phosphatase and cathepsin D and osmotic sensitivity of lysosomes. alpha-adrenergic blocker dihydroergotamine (3.4 x 10(-5) M) blocked an increase in free activity of acid phosphatase as a result of adrenalin action but did not eliminate hydrocortisone labilizing action. beta-adrenergic blocker propranolol (3 x 10(-4) M) lowered free activity indices and osmotic sensitivity of lysosomes to control values both in the presence of adrenalin and hydrocortisone. The labilization of lysosomal membranes in liver sections was also observed after adding dibutyril-cAMP (10(-8) M) or monobutyril-cGMP (10(-13)-10(-9) M) into the incubation medium.

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[The cooperative effect of hydrocortisone, adrenaline and high-density lipoproteins in regulating liver hexokinase activity].

The authors described a cooperative effect of glucocorticoids, catecholamines and high density lipoproteins (HDLP), based on increased hexokinase and glucokinase biosynthesis in the liver, resulting in elevated activity of the respective enzymes. This effect was completely blocked by actinomycin-D (a DNA-dependent inhibitor of RNA synthesis), vinblastine (an inhibitor of the microtubular apparatus and intracellular shift) and gordox (an inhibitor of serine proteinases). The modulating effect of HDLP with relation to the adaptive hormones emphasizes the cooperative nature of the new mechanism of enzymatic synthesis induction.

Animals↗
PubMedDate not supplied

[The role of plasma high density lipoproteins as modulators of specific hormonal effect of hydrocortisone].

Hydrocortisone affected less distinctly the gene expression in rat liver slices as compared with the simultaneous effect of the hormone and blood plasma high density lipoproteins (HDL). These substances acted cooperatively and the phenomenon observed was not reproduced by means of individual components. The protein moiety of HDL, but not of lipid part of the molecule, was of importance in realization of the effect. Inhibitors of lysosomal proteinases (pepstatin, soy bean inhibitor of trypsin and iodoacetamide) as well as inhibitors of lysosomes intracellular translocation (colchicine and vinblastine) blocked completely the cooperative action of hydrocortisone and HDL. Hydrocortisone-dependent activation of chromatin and stimulation of genes expression led to an increase in the binding constant of acridine orange with DNA, while molar concentration of binding sites of the probe was practically unaltered. At the same time, simultaneous effect of hydrocortisone and HDL did not alter the constants for acridine orange binding but concentration of the probe binding sites with DNA was distinctly increased.

Acridine Orange↗
PubMedDate not supplied

[The role of the cooperative effect of lipoproteins and hormones in the regulation of the lysosomal apparatus of the cell].

Cooperative effect of hydrocortisone, adrenaline and high density lipoproteins was found in initiation of the lysosomotropic induction of protein synthesis in liver tissue. Translocation of lysosomes into perinuclear area and transfer of lysosomal hydrolases into nuclei were responsible for specificity of the effect. As a result of consecutive action of carboxylic, serine and thiol proteinases activation of chromatin was induced in nuclei. These processes were inhibited by pepstatin, hordox and iodoacetamide, respectively, as well as by vinblastine--inhibitor of intracellular transport. Actinomycin D inhibited completely the elevated synthesis of RNA and protein under these conditions. The cooperative effect studied appears to be involved in physiological regeneration of liver cells under conditions of their increased functional activity.

Acid Phosphatase↗
PubMedDate not supplied

[Effect of blood serum hormones and lipoproteins on levels of cAMP and cGMP in viable sections of rat liver].

Cyclic nucleotides are universal intermediary agents of hormones in the target tissues, however mechanisms of the regulation of the cAMP and cGMP content in the cell are rather complex and still obscure. More data have appeared of late on the involvement of blood serum lipoproteins in the regulation of various intracellular processes including adenylate cyclase activity. Therefore the purpose of the study was to investigate the effect of adrenaline, hydrocortisone, glucagon, insulin and blood serum lipoproteins on the cAMP and cGMP content in rat liver surviving sections. An attempt was made to study a cooperative effect of the above hormones and lipoproteins of various classes. The results obtained have shown that adrenaline and glucagon raise the cAMP level in rat liver surviving sections. The effect of adrenaline is mediated by beta-adrenoreceptors. Insulin lowers an increases the level of cAMP in liver sections determined by the effect of glucagon. A decrease of the initial cAMP content in response to insulin occurs after a short lag period. High density lipoproteins (HDLP3) reduce the cAMP content in liver surviving sections. A cooperative effect of lipoproteins of a very low density and adrenaline (or hydrocortisone) in the regulation of the cAMP content in the rat liver was revealed. The cGMP content in rat liver surviving sections does not change under the influence of the above hormones and lipoproteins.

Animals↗
PubMedDate not supplied

[Transport of steroid hormones by serum lipoproteins].

Binding and distribution of glucocorticoids as well as of some of their precursors in lipoprotein fractions of human and rat blood serum were studied. Binding of the corticosteroids with blood serum lipoproteins was shown by ultracentrifugation and gel filtration. The binding of corticosteroids with lipoproteins was accompanied by alterations in the apoprotein conformation, detected by means of quenching of tryptophane fluorescence. The data obtained suggest that the lipoproteins are involved in transport of corticosteroids.

Animals↗
PubMedDate not supplied

[Effect of adrenaline, hydrocortisone and serum HDL lipoproteins on the activity of multiple forms of glucose-6-phosphate dehydrogenase in the rat liver].

A decrease in activity of glucose-6-phosphate dehydrogenase (G6PD) in Wistar rat liver tissue, caused by stress, was realized via a mechanism, involving adrenaline and hydrocortisone as first messengers and cAMP as a second messenger. In these systems G6PD II and IV isoenzymes were mainly inhibited. These are the urgent mechanisms for regulation of the enzymatic activity. Activation of G6PD within the reparative period after the stress was due to induction of the enzyme synthesis. Cooperative action of adrenaline, hydrocortisone and high density lipoproteins from blood serum, modulating the effect of adaptive hormones, was responsible for the enzyme induction. Actinomycin D and vinblastine (inhibitor of the cell microtubular apparatus) prevented the stimulation of G6PD isoenzymes caused by the cooperative hormonal effect. The data obtained suggest that the cooperative effect occurred as a result of lysosomes translocation to nucleus and the subsequent activation of chromatin.

Animals↗
PubMedDate not supplied

[Effect of nutrition on lysosomal function during physical loading].

Changes of cardiac, sceletal and hepatic lysosomes effected by three different variants of balanced isocaloric diets: 1--basic, 2--protein-lipid and 3--carbohydrate, with ratios of proteins, lipids and carbohydrates in mass 1.0:0.35:2.6; 1.0:0.48:0.67; and 1.0:1.3:10.9, respectively, were studied. Activities of enzymes participating in degradation of carbohydrates (beta-glucosidase, beta-N-acetyl-glucosaminidase) were more increased in the animals fed with the carbohydrate diet. Activation of proteolytic enzymes (cathepsin D) was observed in tissues of rats taking the protein-lipid food. As a rule physical exercise exerts lysosomal enzymes activation and their membrane labilization in rats maintained on the basic diet. Reversial reactions of lysosomes to physical exercise is observed in animals receiving the carbohydrate diet for along time that is expressed in increasing the total activity of lysosomal hydrolases and stabilizing the lysosomal membranes. On the contrary, maintaining the animals on the protein-lipid diet is followed by a more pronounced activation of the lysosomal apparatus of tissues as compared to the basic diet.

Animal Nutritional Physiological Phenomena↗
PubMedDate not supplied

[Cooperative effect of hydrocortisone, adrenaline and high-density lipoproteins in regulating the glucose-6-phosphate dehydrogenase activity of the liver].

The role of adaptive hormones and serum lipoproteins in the regulation of glucose-6-phosphate dehydrogenase (G-6-PDH) activity was investigated. The test was performed on experimental hepatic sections of Wistar rats. It was shown that timely regulation of G-6-PDH by epinephrine and hydrocortisone which inhibits the activity of enzyme is manifested through the cAMP-dependent mechanism. The cooperative effect of epinephrine, hydrocortisone and high-density lipoproteins that enables G-6-PDH activation was revealed. It was stated that only high-density lipoproteins of subpopulation III were capable of hormonal mediating. The effect was caused by the induction of enzyme synthesis and manifested through lysosome-dependent activation of chromatin.

Animals↗
PubMedDate not supplied

[Absorption of iodinated plasma lipoproteins by subpopulations of hepatocytes and sinusoid cells of the rat liver].

Individual hepatocytes and sinusoid cells were isolated from rat liver tissue within various periods after intravenous administration of 125I-lipoproteins of very low (VLDL), low (LDL) and high density (HDL). Estimation of the radioactivity per 1 mg of the cell protein showed that within 30 min absorption of VLDL was 6-fold, LDL--4-fold and HDL--14-fold as high as compared with hepatocytes. Within the first 30 min sinusoid cells accumulated 54% of 125I-HDL, while hepatocytes contained 46% of the labelled lipoprotein, absorbed in liver tissue. On the other hand, within 6 hrs and 12 hrs hepatocytes contained 80-88% and sinusoid cells--17-20% of the label. After fractionation of hepatocytes in Ficoll density gradient all the populations of hepatocytes were shown to absorb effectively VLDL fraction, while HDL and LDL were accumulated in "heavy" (centrolobular) hepatocytes. Penetration of the lipoproteins in hepatocytes appears to be carried out by means of intracellular transport from sinusoid cells.

Animals↗
PubMedDate not supplied

[Plasma lipoprotein absorption by steroid-producing organs in the rat].

A study was made of the blood plasma iodinated lipoprotein (LP) absorption by the organs and tissues of rats following i.v. injection. The adrenals and ovaries were shown to effectively absorb high density lipoproteins (HDL) as compared to the liver, spleen, kidneys, heart and lungs. HDL absorption reached its maximum 30 min after LP injection. Six hours later the adrenal tissue radioactivity level decreased by 30% and after 12 h 3-fold. The time-course of HDL absorption by the ovaries was characterized by a slow increase in radioactivity after 6 h and a gradual decrease of the label index after 12 h. Differences in HDL absorption by the adrenals and ovaries reflected some functional features of these steroid producing organs.

Absorption↗
PubMedDate not supplied

[Features of the regulation of key enzymes involved in glycolysis and the pentosephosphate shunt in tissues with different functional specializations].

Under conditions of acute and chronic stress carbohydrate metabolism was decreased in muscles and liver tissue, increased in adrenal glands and unaltered in brain. cAMP at concentration 10(-5)M decreased the rate of glycolysis in liver tissue and increased it slightly in adrenal glands. The inhibitory effect of cAMP was not decreased by 2',3'-AMP and was reversed completely by the protein inhibitor of proteinkinase. cAMP inhibited hexokinase (HK) isoenzymes 2 and 3 as well as glucose-6-phosphate dehydrogenase (G6PD) isoenzymes 1 and 2, activities of HK 1 and G6PD 3 and 4 were unaltered. The decrease in activities of HK and G6PD appears to be related to phosphorylation of proteinkinase; lack of the effect of cAMP in adrenal glands was apparently due to absence of corresponding cAMP-dependent proteinkinase in this tissue.

Adrenal Glands↗
PubMedDate not supplied

[Effect of apoproteins of blood lipoproteins on the functional state of rat liver mitochondria].

ApoLPHD and apoLPVLD affected the oxidative phosphorylation in mitochondria isolated from liver tissue of starved and intact rats depending on the dose administered; apoLPHD exhibited a partial effect, apo LPVLD--caused complete uncoupling of respiration and phosphorylation. Low concentrations of the both apoproteins increased the rate of mitochondrial respiration at the metabolic states 3 and 4 and did not alter the rate of phosphorylation. The additive effect was not observed after addition of dibutyryl-cAMP simultaneously with apoLPHD or with apoLPVLD into the incubation samples at low doses causing no uncoupling action. Under these conditions the effects of apoproteins prevailed. The apoproteins appear to participate in adaptive modifications of oxidative metabolism in stress-impaired liver mitochondria.

Animals↗