HDL-binding lipoproteins on human fetal hepatocytes

Two types of binding sites for high-density lipoproteins (K_d=1 μg/ml and 20 μg/ml) were identified on human fetal hepatocytes and designated as P₁ and P₂. Ligand blotting has shown that P₁ site is protein with Mr 100 kD and P₂ site involves two proteins with Mr 105 and 110 kD. P₂ proteins were not detected when incubation with ligands was shortened from 24 h to 30 min. Molecular weight and activity of P₁ did not change considerably after reduction of disulfide bonds. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 459–463, October, 1998     

Chemiluminescence study of the contents of the products of Cu2+-induced lipid peroxidation in different fractions of human blood lipoproteins

It is demonstrated that the content of the primary products of lipid peroxidation reaches the maximum after about 1-h incubation with Cu²⁺ and then declines. At a Cu²⁺ concentration of about 10–15 μM, the content of lipid peroxidation products is maximal; it does not rise with a further increase in the Cu²⁺ concentration. Comparison of the kinetics of lipid peroxidation in different lipoprotein fractions shows that low density lipoproteins are much more strongly oxidized than high density lipoproteins. A strong positive correlation between the amplitude of the chemiluminescence burst and the diene conjugate content is established in 79 independent measurements. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, pp. 144–148, February, 1995     

Effect of dexamethasone on the expression of binding sites for high-density lipoproteins in cultured rat hepatocytes (Independence of the hormone effect on the intracellular cholesterol pool)

It is shown that glucocorticoids play a key regulatory role directed toward the maintenance of an optimal level of binding and internalization of HDL₃ in hepatocytes. Their stimulatory effect on the expression of HDL receptors proves to be independent of changes in the CH content in parenchymal cells. Translated fromByulleten' Eksperimentalnoi Biologii i Meditsiny, Vol. 117, N ^o 1, pp. 50–53, January, 1994     

Role of glycolysis in the maintenance of the energy-synthesizing function of hepatocytes from rats adapted and nonadapted to hypoxia at different oxygen concentrations

It is demonstrated that the lactate-Po₂ dependence is the same in hepatocytes of rats with high and low resistance to hypoxia and does not correlate with phasic changes in the ATP concentration in the 890–50 μM O₂ region. Strong activation of lactate formation against the background of ATP decrease indicates that glycolysis is not the major mechanism determining the steady-state ATP level in the cell and affecting the ATP-Po₂ relationship in a wide range of oxygen concentrations. The intensity of glycolysis in hepatocytes of rats with high resistance to hypoxia is markedly increased after periodic adaptation to hypoxia but remains practically unchanged in the hepatocytes of low-resistance rats. This indicates that fundamentally different compensatory mechanisms are involved in this process in the liver of high- and low-resistance rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 1, pp. 28–32, January, 1995     

Effect of vinpocetine on various types of high-threshold potassium currents in snail neurons

A high-threshold (−20 mV) K⁺ current was recorded from isolated edible snail neurons by a two-microelectrode voltage clamp technique. This current consisted of three components: fast-inactivating K⁺ currents (I_A), noninactivating K⁺ current (I_KD), and Ca²⁺-dependent K⁺ current (I_K(Ca)). Different cells had one to three components of K⁺ current. Vinpocetine increased I_A, moderately inhibited I_KD (by 30–50%) and strongly suppressed I_K(Ca) (by 60–90%). Inhibition of I_K(Ca) was not related to the effect of vinpocetine on the inward Ca²⁺ current. When K⁺ current consisted of all three components, the effect of vinpocetine on the ionic current amplitude was opposite at different potentials. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 408–411, October, 1998     

Morphofunctional aspects of liver regeneration in experimental correction of toxic hepatitis

It is demonstrated that cytoplasmic extract of rat pup liver stimulates cellular and intracellular regeneration of hepatocytes exposed to the toxic agent CCl₄. Injection of liver cytosol stabilizes lysosomal membranes, increases the coefficient of energy efficiency of mitochondria, and activates proliferation of polyploid hepatocytes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 656–659, June, 1995 Presented by D. S. Sarkisov, Member of the Russian Academy of Medical Sciences     

Is Na,K-ATPase the target of oxidative stress?

The susceptibility of Na,K-ATPase from bovine brain to various compounds containing active oxygen radicals is assessed. Sodium nitroprusside slightly inhibits Na,K-ATPase, while light-induced NO^o radicals (controlled by the rate of ascorbate oxidation) have no effect on the enzyme. When added in concentrations equally effective in the ascorbate oxidation assay, hydrogen peroxide and sodium hypochlorite inhibit Na,K-ATPase by 70 and 25–30%, respectively. The Fe-dinitrosyl-cysteine complex is the most potent (K_0.5=20 μM) inhibitor of Na,K-ATPase. It is demonstrated that different free oxygen radicals accumulated in the ischemic brain cause different kinds of damage to Na,K-ATPase. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 275–278, March, 1996 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Role of ATP as a sympathetic nervous system transmitter in the smoothing of rapid arterial pressure changes

Arterial pressure lability and its variations were examined in unrestrained rats following selective elimination of adrenergic or purinergic sympathetic influences on the circulatory system. Both the α₁-andrenoceptor blocker prazosin and the nonselective α-adrenoceptor blocker phentolamine lowered the arterial pressure without affecting its lability. When P_2x purine receptors were desensitized with α,β-methyleneATP, the resulting pronounced hypotension was accompanied by a two-fold increase in the lability of mean arterial pressure. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N^no 11, pp. 461–464, November, 1995 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Effect of sarcolemmal anion transport system blockers on the development of ischemia-induced myocardial edema and recovery of contractile function during reperfusion

Subtotal 30-min ischemia leads to myoglobin release and increases water content in the heart. Reperfusion partially restores the developed pressure. Addition of furosemide (a Na⁺, K⁺, 2Cl⁻-sumport blocker) or NMA (inhibitor of Na⁺/H⁺-exchange) to perfusate decreases myocardial water content, reduces myoglobin loss, and completely restores myocardial contractile function. The low-rate perfusion of isolated heart and its reperfusion with solutions containing DIOA (inhibitor of K⁺, Cl⁻-co-transport) or IAA-94 (Cl⁻ channel blocker) increases water accumulation and myoglobin release from the myocardium, and deteriorated its contractile function during reperfusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 4, pp. 400–403, April, 1999     

Assessment of the toxic and protective effects of initiators and inhibitors of free radical reactions using a wild-type strain ofEscherichia coli and a strain deficient for superoxide dismutase

The toxic effects of H₂O₂, paraquat, and oxidized low density lipoproteins are more expressed on superoxide dismutase-deficientE. coli strains than on its wild-type strains, and the effect of tert-butyl-hydroperoxide is less dependent on the presence or absence of this enzyme in the bacterium, whereas that of bleomycin does not depend on it at all. The toxicity of the agents increases in the following series: H₂O₂<oxidized low density lipoproteins<tert-butyl-hydroperoxide <paraquat≪bleomycin. A culture ofE. coli strains AB 1157 and JI 132 may be used for assessing the toxic effect of prooxidants, and anE. coli JI 132 culture with oxidative stress induced by prooxidants as a test system for detecting the potential antioxidants and assessing the mechanism of the action. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o , pp. 74–79, January, 1996 Presented by A. I. Archakov, Member of the Russian Academy of Medical Sciences     

Initiation of apoptosis in hepatocytes during prolonged arterial hypotension and postresuscitation period

An increase in activity of Ca²⁺, Mg²⁺-dependent endonucleases on the second hour of hypotension coincided with the presence of DNA fragments in agarose gel. A correlation was established between the duration of hypotension, Ca²⁺, Mg²⁺-dependent endonuclease activity, and intensity of nuclear DNA fragmention. Apopotosis of hepatocytes is triggered during ischemia and develops during reperfusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditisiny, Vol. 125, No. 3, pp. 285–288, March, 1998     

Role of the interaction between different types of serotonin and α2-adrenergic receptors in the regulation of audiogenic seizures in DBA/2 micereceptors in the regulation of audiogenic seizures in DBA/2 mice

It is shown that the serotonin receptors 5-HT_1c, 5-HT₃, and 5-HT₄ and α₂-adrenergic receptors are involved in the regulation of audiogenic seizures in DBA/2 mice, and that the effects of these serotonin receptors on the duration and magnitude of convulsive activity are the opoosite of those produced by α₂-adrenergic receptors. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp. 381–383, April, 1995     

Suppressive activity of bone marrow cells from patients with stomach cancer. Effect of prostaglandins, transforming growth factor-β, and nitric oxide

It is shown that nonadhesive bone marrow cells from patients with stomach cancer suppress phytohemagglutinin-stimulated proliferation of peripheral blood lymphocytes of healthy donors and proliferation of Molt-4-human lymphoma cellsin vitro. Suppressive activity of bone marrow cells from cancer patients is not mediated through prostaglandin secretion, since indomethacin has no effect on it. Addition of neutralizing monoclonal antibodies to transforming growth factor-2₁, 2₂, and 2₃ partially reduces this suppressive effect. Suppressive effect of bone marrow cells from patients with stomach cancer is partially mediated through production of nitric oxide, since the inhibitor of its synthesis N⁹-monomethyl-L-arginine diminishes the inhibiting effect of bone marrow cells from cancer patients on phytohemagglutinin-stimulated proliferation of peripheral blood T cells from healthy donors. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 2, pp. 217–220, February, 1998     

Effect of human defensins on the cytoplasmic Ca2+ content in platelets

The effect of the total fraction of human defensins (HNP-1, HNP-2, and HNP-3) on the cytoplasmic Ca²⁺ content ([Ca²⁺]_i) in the platelets of healthy donors was studied. At concentrations of 0.1–40 μg/ml and an incubation time of 10 min defensins have no effect on [Ca²⁺]_i in platelets labeled with Fura-2AM. However, at higher concentrations (100 μg/ml) they increased platelet [Ca²⁺]_i. In addition, defensins (40 μg/ml) inhibited the Ca²⁺ increase in platelets induced by thrombin, adenosine diphosphate, and the lipopolysaccharide ofS. typhimurium endotoxin. The most pronounced inhibitory effect was observed in a suspension of thrombin-stimulated platelets. It is shown that the effect of human defensins on the functional activity of platelets is due to the alterations in the intracellular Ca²⁺. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 600–603, December, 1994     

Inhibition of low density lipoprotein oxidation by melatonin

The antioxidant activity of the lipophilic hormone melatonin, “an ideal inhibitor of free radicals,” is studied in models of cellular (peritoneal mouse macrophages) and copper-induced oxidation of low density lipoproteins. Oxidative modification of low density lipoproteins is assessed by accumulation of thiobarbituric acid reactive substances and degradation of¹²⁵I-labeled lipoproteins in a fresh culture of macrophages. Melatonin inhibits in a dose-dependent manner cellular and copper-induced oxidation of lipoproteins and production of the superoxide anion radical by macrophages, the mean concentrations of 50% inhibition being 300, 1230, and 900 μM, respectively. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 10, pp. 399–402, October, 1996     

Structural and functional morphology of acute phase reaction in the liver in experimental hypercholesterolemia

Synthesis of acute phase transmitters, migration and degranulation of pseudoeosinophils in hepatocytes, and damage to hepatocytes are observed during, the first few weeks of atherogenic diet. It is hypothesized that the acute phase reaction determines disturbances in the synthesis and catabolism of lipoproteins in the liver. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 460–464, April, 1998     

Biological availability of endogenous calcitonin in rats

Significant correlation was established in 52-week-old rats between serum calcitonin content and density of sublemmal granules at the vascular pole of C-cells (N _Vsg)∶r _xy=0.922,p<0.001. Statistical simulation methods made it possible to determine the confidence interval of biological availability of endogenous calcitonin: 87–100% (p≥0.95). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 4, pp. 474–476, April, 1998     

Multiply modified desialylated low-density lipoproteins: Physicochemical properties

Sialylated and desialylated low-density lipoproteins from human blood are shown to differ markedly in physicochemical parameters. The latter lipoproteins have a smaller particle size, are denser and more electronegative, and tend to aggregate more readily than the former. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 42–43, January, 1996 Presented by E. I. Chazov, Member of the Russian Academy of Sciences     

Protective effect of intracerebroventricular injection of adenosine agonists during total cerebral ischemia

Adenosine and its analogs N⁶-cyclohexyladenosine (CHA) and N-ethylcarboxamideadenosine (NECA) are highly effective when injected into the lateral ventricle in very low doses (by 1–2 orders lower than subcutaneously). The protective effect of A-agonists is considered to be mediated by a central mechanism and realized via A-receptors of the brain: the effects of low doses of A-agonists are mediated by A₁-receptors, whereas higher doses exert an extra A₂-effect. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 6, pp. 622–624, June, 1994 Presented by P. V. Sergeev, Member of the Russian Academy of Medical Sciences     

Thermodynamic parameters of binding of mouse 2G3 antitheophylline monoclonal antibodies to theophylline

The binding of 2G3 mouse antitheophylline monoclonal antibodies (affinity constant K_aff=2×10¹⁰ liter/mol) to theophylline is studied using isothermal titration microcalorimetry. Thermodynamic parameters of the binding are: enthalpy change ΔH=−0.23 kcal/mol; Gibbs free energy change ΔG=−16.42 kcal/mol; entropy change ΔS=0.054 kcal/(mol×K). Regression analysis shows a two-site kinetic binding model. A great contribution of entropy component to the free energy change of 2G3 antibody binding to theophylline is indicative of an entropy-dependent process. The entropy-dependent nature of the binding presumably determines the binding kinetics. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 11, pp. 570–573, November, 1997