[Changes in luminescence of the undiluted blood in patients with ischemic heart disease during laser therapy].
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Humans↗
Biomedical subjects
K N Novikov
Publications and source records attributed to K N Novikov.
[The regulation of cell volume: the mechanisms of intracellular signalling].
The mechanisms of intracellular [correction of intercellular] signalling responsible for cell volume regulation are elucidated in the 2nd part of the review. Data on a nature of the "volume" sensor and signals acting on it, the properties of structures and mechanisms regulating the cell volume, are discussed as well as genetic regulation of the cell volume responses.
Animals↗
Effect of different solubilizing agents on the aggregation state and catalytic activity of two purified rabbit cytochrome P450 isozymes, CYP1A2 (LM4) and CYP2B4 (LM2).
The effects of different ionic and nonionic detergents and lecithin/Na cholate mixtures on the aggregation state and catalytic activity of two major inducible rabbit cytochromes P450, CYP1A2 (LM4) and CYP2B4 (LM2), both of which are highly aggregated in solution, have been compared. Nonionic detergents Emulgen 913 and Lubrol PX as well as the mixture of lecithin-cholate demonstrate the ability to induce the dissociation of P450 isozymes only to dimers, accompanied by an increase in their catalytic activity, especially in lecithin proteoliposomes.
Animals↗
[The effect of methylcholanthrene and sovol induction on the functional activity of rat blood neutrophils in vivo].
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Animals↗
[The effect of lysolecithin on rat liver microsome monooxygenase activity after induction by xenobiotics of the methylcholanthrene type].
Effects of exogenous gamma-myristoyl- and gamma-palmitoyllysolecithins on physico-chemical characteristics of rat liver microsomes, such as hydrophobicity and viscosity, as well as on oxidative NADPH-dependent O-deethylation of 7-ethoxycoumarin (7-EC), O-demethylation of p-nitroanisole (p-NA) and hydroxylation of 3.4-benz(a)pyrene (BP) induced by the mechylcholanthrene xenobiotics methylcholanthrene (MCh), beta-naphthoflavone (NF) and Sovol (SV) have been investigated. The specific inducible form of P-450c showed different affinity for the substrates. Lysolecithin decreased the hydrophobicity but only slightly increased membrane viscosity, whereas the monooxygenase substrates neutralized these effects. Lysolecithin (2-20 micrograms/mg of microsomal protein) inhibited the activity of deethylase 7-EC (maximally by 11%) in NF- and SV-induced microsomes, this inhibiting effect being more pronounced than that in MCh-induced microsomes. At higher concentrations lysolecithin inhibited the rate of 7-EC deethylation in MCh-induced microsomes more strongly; the maximal inhibition (23%) was observed at the protein concentration of 60 micrograms/mg. In case of NF- and SV-induced microsomes the inhibition was 18%. The inhibiting effect of lysolecithin on 7-EC dealkylation was expressed in a lesser degree than that on p-NA O-demethylation in induced (but not intact) microsomes. A significant positive correlation has been found between the changes in hydrophobicity and inhibition rates in the presence of lysolecithin, however only for 7-EC deethylation.
Animals↗
[The antioxidative activity of drugs in the liver microsomal system of rats].
The antioxidative properties of drugs--diethylcarbamazine citrate--DECC, dipyridamole-DP, levamisole and labinzarit--have been investigated in various microsomal lipid peroxidation (LPO) models: NADPH-, ascorbate- and CCl4-dependent. The most strong antioxidant of direct action turned out to be DP, DECC exhibited the antioxidative properties as a result of metabolic activity in monooxygenases system of rat liver microsomes. Levamisole and labinzarit turned out to be weak antioxidants. The control of microsomal membrane stability against Fe(2+)-ADP, NADPH-induced LPO, after being isolated from rat liver after the action of CCl4 without and with DECC, showed that DECC protected microsomal membranes from CCl4 in vivo and they remained stable against LPO in vitro.
Animals↗
[An immunochemical analysis of the induction of cytochrome P-450 isoforms in the liver of fresh-water fishes by 3-methylcholanthrene, beta-naphthoflavone and aroclor 1254].
The cytochrome P-450 isoforms have been studied in liver microsomes of some fish species from Lake Baikal. Using the inhibitory analysis of microsomal monooxygenase activities carried out by the specific polyclonal antibodies it has been shown that 3-methylcholanthrene, beta-naphthoflavone and arochlor 1254 induce isoforms immunologically related to cytochrome P-488c but not to the rat cytochrome P-450b in fish liver microsomes. The immunologic identity in isoforms of fish and rat cytochromes induced by methylcholanthrene has not been revealed. A possibility to use the method of the inhibitory analysis of fish microsomal activities by specific antibodies to the rat cytochrome P-450 isoforms for biomonitoring and biotesting of polycyclic hydrocarbons and polychlorinated biphenyls in aquatic systems is discussed.
Animals↗
[Does alpha-tocopherol interact with the active center of cytochrome P-450 in liver microsomes?].
The interaction of alpha-tocopherol (alpha-T) and its synthetic derivative 2,2,5,7,8-pentamethyl-6-hydroxy-chroman (PMC) with cytochrome P-450 system was studied in the rat liver microsomes. Spectral differentiations of type I, increase of NADPH oxidation rate and inhibition of 7-ethoxycoumarin deethylase in microsomes were observed only in the presence of PMC. The results obtained suggest that unlike alpha-T, PMC is effectively bound and metabolized by cytochrome P-450.
7-Alkoxycoumarin O-Dealkylase↗
[Inhibition of the dealkylating activity of cytochrome P-450 isoforms in rat liver microsomes by the products of phospholipase A2-induced phospholipid hydrolysis].
The effects of exogenous phospholipase A2, oleic acid and lysolecithines on oxidative NADPH-dependent O-dealkylation of 7-ethoxycumarin in liver microsomes of phenobarbital- and 3-methylcholanthrene-induced and non-induced rats were studied. Oleic acid up to the concentration of 100 micrograms/mg of protein did not inhibit this process. gamma-Myristoyl and gamma-palmitoyl lysolecithines decreased the reaction rate already at concentrations of 2-4 micrograms/mg of protein. Oleic acid was attached to cytochrome P-450 according to type I binding, whereas lysolecithines did not bind to the cytochrome. Thus, in the presence of phospholipase A2 in liver microsomes of non-induced rats, when the phospholipid hydrolysis products are accumulated at low concentrations, 7-ethoxycumarin deethylase is inhibited by lysophospholipids but not by free fatty acids. In 3-methylcholanthrene-induced microsomes the sensitivity of O-deethylation of 7-ethoxycumarin to the inhibiting effect of phospholipase A2 or lysolecithine is lower than that in non-induced or phenobarbital-induced microsomes.
7-Alkoxycoumarin O-Dealkylase↗
[Non-antioxidative mechanism of cytochrome P-450 stabilization by alpha-tocopherol: the effectiveness in avitaminosis E].
The efficiency of alpha-tocopherol as a 7-etoxycumarine deethylase protector in rat liver microsomes damaged by phospholipase A2 at various levels of vitamin E was studied. No selective damage of cytochrome P-450 isoforms possessing a catalytic activity towards 7-etoxycumarine under vitamin E deficiency was observed. Phospholipase A2 decreased the deethylase activity of cytochrome P-450, the efficiency of the damaging action being dependent on vitamin E content in the liver. Exogenous alpha-tocopherol exerts an antiphospholipase effect and protects 7-etoxycumarine deethylase; the protective action is inversely proportional to vitamin E level in the liver. Under normal conditions the damaging effect of phospholipase A2 on cytochrome P-450 is mainly provided for by lysophospholipids, while under vitamin E deficiency both lysophospholipids and free fatty acids exert a damaging action. A possible mechanism of the stabilizing effect of alpha-tocopherol may consist in the interaction of the chromanol nucleus in the vitamin E molecyule both with lysophospholipids and with free fatty acids.
7-Alkoxycoumarin O-Dealkylase↗
[Study of the mechanism of initiation of enzymatic NADPH-dependent lipid peroxidation in membranes of the endoplasmic reticulum].
The localization and mechanism of generation of active oxygen species in the enzymatic NADPH-dependent lipid peroxidation system in liver microsomes were studied. Using the spin-trapping method, the key role of active oxygen species in the initiation of NADPH-dependent enzymatic lipid peroxidation was confirmed. It was shown that active oxygen species are generated via consecutive one-electron reduction of the oxygen molecule by NADPH-cytochrome P-450 reductase.
Animals↗
[Test systems for biomonitoring based on membrane-bound enzyme complexes. V. Mixed-function monooxygenase induction in the liver microsomes of Lake Baikal fish].
The content of cytochrome P450 and monooxygenase activity has been studied in the liver of Baikal fishes (Coregonus automnalis, Thymallus articus, Brachymystax lenok and Cottocomphorus greminsky). The administration of 3-methylcholanthrene increases considerably the level of metabolic activity of microsomal fraction and cytochrome P450 content in liver. The data of microsomal fractions of rats and fishes liver electrophoresis have shown that xenobiotic causes the synthesis of similar according to the molecular weight forms of cytochrome P450 in these animals. The induction of microsomal monooxygenase inhibits the lipid peroxidation of microsomal fraction.
Animals↗
[Hydroxylation products of hydrophobic xenobiotics--stabilizers of cytochrome P-450 in the hepatocytes].
The effects of the hydroxylation product 3,4-benzo(a)pyrene and the free radical scavenger 1,2,3-trioxybenzene on cytochrome P-450 degradation in isolated rat hepatocytes induced by the Fe2+-ADP + NADPH system activating lipid peroxidation (LPO) were investigated. During incubation of hepatocytes, cytochrome P-450 is destroyed due to accumulation of LPO products. Addition of the free radical scavenger 1,2,3-trioxybenzene and the monoxygenase substrate 3,4-benzo(a)pyrene to the incubation medium induces inhibition of LPO and simultaneous stabilization of cytochrome P-450. Deceleration of malonic dialdehyde production by the free radical scavenger of the monoxygenase substrate suggests that both the compounds stabilize cytochrome P-450. It is assumed that in liver hepatocytes, exogenous free radical scavengers of the phenolic type and the products of their decarboxylation protect cytochrome P-450 against the LPO-induced destruction via oxidative metabolism of hydrophobic substrates.
Adenosine Diphosphate↗
[Mechanisms of mixed-function oxidase system breakdown in the hepatic endoplasmic reticulum. The role of membrane phospholipid peroxidation].
It has been shown that endogenous lipid peroxidation (LPO) is an effective mechanism participating in the destruction of endoplasmic reticulum membranes (cytochrome P450) in liver. Antioxidants are able to control the rate of degradation of cytochrome P450 in vivo. Stock of the constitutive cytochrome P450 as compared with induced P450 is more resistive to LPO in vivo and in vitro. Spontaneous as well as induced by Fe2+--ADP+ +NADPH system destruction of cytochrome P450 due to accumulation of LPO products malonic dialdehyde (MDA) occurs during incubation of isolated rats hepatocytes. The LPO inhibitors (4-methyl-2,6- ditretbutilphenol , pyrogallol) stabilize cytochrome P450 preventing accumulation MDA hepatocytes. Degradation of cytochrome P450 in microsomes during trypsin proteolysis has been found to be enhanced by PLO induction. Efficiency of proteolysis depends on the way of induction and decreases in such an order: NADPH-- HNDH --ascorbate-dependent LPO. LPO may be considered as a trigger mechanism that makes some forms of cytochrome P450 available for endogenous proteases.
Animals↗
[Antioxidants as stabilizers of cytochrome P-450 in hepatocytes].
Spontaneous destruction of cytochrome P-450 arising from activation of lipid peroxidation (LPO) occurs during incubation of hepatocytes. LPO activation in hepatocyte suspension by a catalytic system containing Fe2+--ADP plus NADP X H makes the destruction of cytochrome P-450 more rapid. Supplementation of the incubation medium with the antioxidant, 2-ethyl-6-methyl-3-hydroxypyridine (HP-6), inhibits LPO, on the one hand, and stabilizes cytochrome P-450, on the other one. Ionol appeared to be a more effective LPO inhibitor in hepatocytes and, accordingly, a more effective stabilizer of cytochrome P-450 than water-soluble HP-6.
Animals↗
Lipid peroxidation and electric activity of the retina.
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Action Potentials↗
[Lipid molecular organization in the photoreceptor membranes studied by a spin probe method].
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Animals↗
[Lipid peroxidation and degeneration of the retinal photoreceptors in rats with avitaminosis E].
Alimentary E-avitaminosis in rats was accompanied (in vivo) by a sharply intensified formation of the lipid peroxidation products (hydroperoxides, dialkylperosides, "intermolecular links") in the retina and by degeneration of photoreceptors (chiefly of the external rod segment layer). Discussion of the experimental data obtained is based upon the views on the antioxidant alpha-tocopherol action mechanism in vivo.
Animals↗