[Oxidized derivatives of thiamine: formation, properties, biological role].

The data available in literature about formation, properties, possible biological role and practical application of the oxidized derivatives of B1 vitamin (thiamine) is first generalized and analysed in the review. It is known that at the values of pH > 7.0 the molecule of thiamine is able to undergo two-phase reaction of opening of thiazole ring with formation of anion of thiol form of thiamine and unstable tricyclic form. In the presence of oxidants in an alkaline environment a thiol form of thiamine is oxidized to thiamine disulfide, tricyclic form--to thiochrome. Oxidative transformation of thiamine molecule is promoted by phenoxyl radicals, their level can be substantially increased in animal tissues at oxidizing stress of different origin when the level of reactive forms of oxygen sharply increases and content of hemoproteins oxoferryl forms is raised. The analysis of literature data gives grounds to assume that thiamine and its hydrophobic metabolite--thiochrome--under certain conditions can perform an important antioxidant function in protection of cell structures against damaging action of peroxinitrite, nitrogen dioxide, peroxide. The presence of oxidized metabolites of thiamine and its phosphates in the cells of animals, even in minor quantities, is an established fact and, consequently, there is a possibility, that they can interact specifically with cellular structures or proteins to effect cellular processes in certain conditions.

[Effects of alpha-tocopherol and its anologues on rat thymocytes programmed death induced by protein kinase inhibitors].

It is established that alpha-tocopherol (alpha-TPh) shows cytoprotective effect at the induction of rats' thymocytes apoptosis by endocellular protein kinase inhibitors--staurosporine and phorbol ether in high concentration, and also on necrosis of the cells caused by sphyngosine. The effect of alpha-TPh on thymocytes death caused by protein phosphatase type 2A inhibitor ocadaic acid is much less expressed. The obtained data testify that the known ability of alpha-TPh to the inhibition of PKC and to the activation of protein phosphatase type 2A is not the main mechanism of its cytoprotective action. Partial reproduction of alpha-TPh effects by its analogue alpha-tocopheryl acetate which is not capable to enter in redox reactions, and the absence of influence on the studied processes of an antioxidant of N-acetyl-L-cysteine do not confirm the antioxidant mechanism of alpha-TPh action in this case. The inhibition by alpha-TPh of the release of cytochrome c in the cytosol of cells testifies to the implementation of its cytoprotective effect at the level of mitochondrial membranes. We assume the existence of the universal mechanism of alpha-TPh cytoprotective action that does not depend on the nature of apoptogenes and realized on the general for the majority of them stage of the cells death induction. The prevention by alpha-TPh of mitochondria dysfunction by stabilizing mitochondrial membranes and reduction of their permeabilization is supposed as that.

[Existence of two different active sites on thiamine binding protein in plasma membranes of synaptosomes].

The current work is aimed at understanding the structure and functionality of thiamine binding protein (TBP) in neural cells plasma membranes. The influence of thiamine triphosphate on thiamine binding by TBP in synaptic plasma membranes (SPM) isolated from the rat brain was investigated. It was shown that thiamine triphosphate inhibits thiamine binding activity of SPM in concurrent manner (K(i) = 1.0 +/- 0.3 microM). At the same time thiamine had no effect on thiamine triphosphatase (ThTPase) activity at the concentration range 0.5-20 microM. Otherwise, ThTPase activation with the maximum at the concentration about 2.5 microM was observed. Further, the influence of classic thiamine antagonists (amprolium, oxythiamine and pyrithiamine) on both biological activities of TBP in SPM was studied. The IC50 value for inhibition of thiamine binding on SPM by amprolium comprised 50 +/- 4.0 microM. Still, this antagonist had no effect on ThTPase activity. For the oxythiamine inhibition of both TBP activities was detected. The values of IC50 were 125 +/- 28 and 1000 +/- 95 microM for thiamine binding and ThTPase activity, respectively. The values of IC50 for thiamine binding and ThTPase activity inhibition differed by more than one order of magnitude and comprised 2.2 +/- 0.2 and 43 +/- 9 microM, respectively. The obtained data indicate that the active sites on SPM responsible for thiamine binding and ThTPase activity have different sensitivity to thiamine antagonists. Our results allow us to suppose that different active protein sites are responsible for the specific binding and for thiamine phosphates hydrolysis by TBP of synaptic membranes.

[Effect of precursors and modulators of coenzyme Q biosynthesis on the heart mitochondria function in aged rats].

Our research demonstrate that ageing leads to changes in activity of electron-transporting enzyme complexes in myocardial mitochondria of old rats and to increased sensitivity of mitochondrial permeability transition pore to inductors of its opening--Ca2+ and phenylarsine oxide. We also observed activation of lipid and protein free-radical peroxidation processes. Administration of a complex of biologically active substances that included precursors and modulators of coenzyme Q biosynthesis (alpha-tocopherol acetate, 4-hydroxybenzoic acid, and methionine) we observed the increase in coenzyme Q content, correction of functional activity of mitochondrial electron-transport chain enzyme complexes, the decrease in intensivity of lipid and protein free-radical peroxidation in the heart and the decrease in sensitivity of mitochondrial permeability transition pore to inductors of its opening. This complex may be used to treat mitochondrial dysfunction under numerous pathologies of cardiovascular system, as well as in ageing.

[Cytotoxicity of troglitazone, structural analogue of alpha-tocopherol is mediated by inhibition of NAD(P)H:quinone oxidoreductase].

It is established, that alpha-tocopherol and pioglitazone in concentration up to 100 microM did not change the rat thymocytes viability while troglitazone and alpha-tocopherol with a short side chain up to 6 atoms of carbon (alpha-tocopherol C6) have the expressed cytotoxic effect. This is the first report demonstrating that troglitazone and alpha-tocopherol C6, unlike a-tocopherol and pioglitazone substantially inhibited the activity of NAD(P)H:quinone oxidoreductase (DT-diaphorase) and this effect is increased with specific DT-diaphorase inhibitor, dicoumarol. Based on these observations, we generalize that cytotoxic action of troglitazone and alpha-tocopherol C6 is connected with the presence in their structure of chroman ring with a lateral chain modified in relation to alpha-tocopherol and is mediated by inhibition of DT-diaphorase, a detoxifying enzyme of xenobiotics.

[Role of alpha-tocopherol in oxidative stress of rat thymocytes induced by hydrogen peroxide and menadione].

T paper deals with studying the effect of alpha-tocopherol and its analogues (alpha-tocopheryl acetate and alpha-tocopheryl quinine) showing no antioxidant properties on rat thymocytes survival and intracellular content of reactive oxygen species (ROS) at H2O2 and menadione-induced oxidative stress. It is established, that the ability of alpha-tocopherol to inhibit the thymocytes destruction induced by the development of oxidative stress is insignificant. It does not depend on the presence of free OH-group in the structure of alpha-tocopherol molecule responsible for development of antioxidant properties, and does not correlate with its influence on intracellular ROS content. The efficiency of the glutathione synthesis predecessor N-acetyl-L-cysteine in the given model testifies to the involving of other systems of antioxidative protection in these processes. The obtained data allow to conclude, that alpha-tocopherol does not play the main role in the protection of cells against ROS damaging action that calls into question its ability to prevent the oxidative stress.

[Thiamine metabolism disorders in the rat brain in experimental alcoholism and a possibility of their correction by vitamin E].

The influence of the chronic consumption of alcohol on biochemical reactions of thiamine metabolism in the rat brain is investigated. It is shown that the content of thiamine diphosphate (ThDP) in the brain tissue does not change at these conditions, though there is an essential decrease in the thiamine-kinase activity. The ability of the isolated nerve terminals (synaptosomes) to absorb labelled thiamine also decreases under this condition. The specified disturbances are probably the reason for deceleration of exchange of free (uncombined with proteins) thiamine and its phosphates in nervous cells, that results in the observed reduction in activity of pyruvate dehydrogenase complex (PDC) due to inactivation by phosphorylation. Thiamine-binding and thiaminetriphosphatase activities of thiamine-binding protein (ThBP) in the structure of synaptic plasma membranes (SPM), isolated from the rat brain in various experimental groups, have been investigated. The increase, with respect to control, in the both enzymes activity in SPM, isolated from the brain of rats with chronic alcoholism has been shown. Kinetic researches testify to an increase of affinity of SPM (ThBP) for thiamine and thiaminetriphosphate in these conditions. When vitamin E was given to animals with a model of chronic alcoholism the normalization of PDC activity in nervous cells was observed, that can testify to the transient character of these changes. Inability of vitamin E to normalize biological activities of ThBP in PMS, that has been analyzed, can testify to more deep disturbances in the structure of SPM or thiamine binding protein in their structure.

[Characteristic metabolic disturbances in the rat tissues caused by long-term use of alcohol].

In the researches carried out on rats with models of chronic alcoholism and alcohol abstinence the most vulnerable to chronic action of alcohol biochemical parameters are revealed: a level of reduced glutathione (it was estimated by the content of free SH-groups in tissues), the content of thiamine diphosphate and thiaminekinase activity in a brain, the content of folic acid in the blood, the content of ubiquinone in the cardiac muscle, RNA/DNA relation in the liver. The data obtained demonstrate first of all the negative influence of alcohol on metabolism of sulfur-containing substances and processes of transmethylation. The results of our investigation have also shown that the part of metabolic changes caused by long-term usage of alcohol, can be caused by direct influence of ethanol or its metabolites on those or other enzymatic proteins or receptors, and their functions can quickly be normalized after the abolition of alcohol (NAD+ contents, alpha-ketoglutarate dehydrogenase activity and some others). More stable changes in other parts of metabolism, that were specified earlier, may be also a result of long-term alcohol consumption.

[To the 20th anniversary of the Chornobyl accident study of vitamin status and provision with micro- and macroelements of limited groups of people at different time periods since the accident at Chornobyl nuclear power plant].

Results of the study of the provision with vitamins and some micro- and macroelements of limited groups of people, who suffered from the accident at the Chornobyl nuclear power plant (ChNPP), which have been carried out by Ukrainian and Russian scientists during various periods after the accident, are generalized in the paper. Persons which participated in liquidation of the accident and lived during the accident in the territory, adjoining to Pripyat (the Kyiv region, town of Slavutich), people which worked at the object "Shelter" and ChNPP were involved in the inspection. It was noted, that in 1-4 years after the ChNPP accident in blood of liquidators the biochemical parameters displaying security of their organism by vitamins A and B1, remain lower in comparison with the same parameters in a group of relatively healthy persons which were not affected by the accident (control), that testifies to stable metabolic disturbance in the organism of people under irradiation influence. Selective inspection of the vitamin status of ChNPP and object "Shelter" personnel in 1992 has shown, that provision with vitamins C, B1, B2, B6 of the overwhelming majority of these people (67-91%) are much below the norm. Deficiency of vitamins C, B1, B6, folate and selenium is also revealed in an organism of 50-90% of women and children living in Slavutich. Deficit of vitamins in most of persons was characterized by polyhypovitaminoses, that is a combination of several group B vitamins deficiency at simultaneously low provision with selenium, and in a part of women and children--by low amount of iron. The results of long-term complex studies by groups of authors give evidence on importance and urgency of formulation and execution of International program on optimisation of nutrition, micronutrition status and health among population of affected areas in Ukraine, Bielorus' and Russia.

[To 20-years anniversary of Chernobyl catastrophe: an attempt to study the vitamin, calcium, iron and selenium status of children and adult population in Slavutich and to correct elicited deficiencies].

The article concisely illustrates the vitamin and mineral state of population of town of Slavutich, including personal of Chernobyl Nuclear Power Station, children of pre-school age and pregnancy women, studied in 1992. Vitamins and minerals deficiency in the main of C and B vitamins and selenium was revealed in all the studied groups. Appropriate measures were developed and introduced to eliminate the detected dusturbances; but however some unsolved problems remained. Taking into account the forthcoming 20th anniversary of Chernobyl disarter, the authors of the come back to considering the obtained data in hope to atlract attention of medical scientific and public to the remained unsolved problems of micronutrient deficiency.

[Viruses as the etiological factor of type 1 diabetes. Animal models].

Type 1 diabetes (TID) results from the destruction of pancreatic beta-cells. In spite of genetic pre-disposition, being the major component for the development of this type of diabetes, nongenetic factors also play an important role in the disease development. Among these factors viruses are implicated in the pathogenesis of TID. Basing on the literature data we have attempted to elucidate possible role of viruses in TID pathogenesis. Viruses may be involved in the TID pathogenesis in at least two distinct mechanisms. Firstly, viruses may trigger beta-cell-specific autoimmunity with or without direct infection of beta-cells. Secondly, viruses may directly infect and destroy beta-cells resulting in TID. Moreover viruses not only cause diabetes, but also may prevent from the disease in animals susceptible to diabetes. Further studies are necessary to understand the mechanisms of the pathogenesis of human virus-induced TID.

[Effect of alpha-tocopherol and its derivatives on actinomycin D induced apoptosis of rat thymocytes].

The induction of rat thymocyte apoptosis by actinomycin D was associated with the increased caspase-3 activity and DNA fragmentation, the both effects were attenuated by alpha-tocopherol. Apoptosis was also decreased by alpha-tocopheryl acetate, but these suppressive effects were less than those of alpha-tocopherol. Tocopheryl quinone had no pronounced antiapoptotic effect. It was proposed that the difference in antiapoptotic effects of alpha-tocopherol derivatives is attributed to structure properties of the chroman head group and to the ability for scavenging reactive oxygen species but it is not excluded that antiapoptotic activity of alpha-tocopherol may exceed that of a mere antioxidant.

[Cytotoxic effect of vitamin E short-chain derivatives on rat thymocytes].

It is established, that alpha-tocopherol, alpha-tocopheryl acetate and tocopheryl quinone with carbon lateral chains shortened to 6 atoms inhibited the viability of primary culture rats thymocytes in a dose-dependent manner. Absence of the DNA internucleosomal degradation side by side with cytosolic lactate-dehydrogenase outlet from the cells testifies to the benefit of necrotic way of thymocytes destruction. The outlet from cells of acid phosphatase, lysosomal marker enzyme, testifies to destabilization of lysosomal membranes by the researched compounds. The possible mechanism of cytotoxication of vitamin E short-chain derivatives in cell cultures is offered, namely: their high permeability through a plasmatic membrane allows to create inside the cells a concentration, sufficient for detergent-like rupture of the lysosomal membranes, that results in the entering of lysosomal enzymes in cytosol and destruction of cells by necrosis.

[Effect of alpha-tocopherol on apoptosis and necrosis of rat thymocytes induced by calcium ionophore A23187 in various concentrations]. / Vliianie al'fa-tokoferola na apoptoz i nekroz timotsitov krys, indutsirovannye Ca2+-ionoforom A23187 v razlichnykh kontsentratsiiakh.

It has been established that alpha-tocopherol prevented rat thymocytes apoptotic death induced by low concentration (250 nM) of calcium ionophore A23187. When necrotic cell death was induced high concentration (10 microM) of calcium ionophore A23187 alpha-tocopherol was able to alter necrosis to apoptosis. It was proposed that such effect can be explained by the ability of alpha-tocopherol to prevent the mitochondrial permeability transition--a key event in apoptosis and necrosis induction.

[Effect of iodine and cobalt salts on content of biologically active substances in spirulina biomass]. / Vliianie solei ioda i kobal'ta na soderzhanie biologicheski aktivnykh veshchestv v biomasse spiruliny.

Production technology of iodinized spirulina biomass at vertical panel airlifted photobioreactor has been developed. The influence of different concentrations of iodine ions at certain combinations with cobalt ions on iodine-accumulative properties of spirulina has been studied. It has been shown that it is possible to obtain spirulina biomass containing certain amount of organically bound iodine by varying cobalt and iodine ions combinations and by staged addition of ions to incubation medium. This technique of staged addition of iodine and cobalt salt allowed to adopt spirulina to their high amount in the incubation medium, to increase spirulina productivity during growth, and to produce biomass with large iodine content.

[Antihypoxic effect of vitamin E and its derivative in rats under modeling of hypoxic conditions of different origin]. / Antigipoksicheskii éffekt vitamina E i ego proizvodnogo v usloviiakh modelirovaniia gipoksicheskikh sostoianii razlichnogo geneza u krys.

The increase of ubiquinone content in myocardial mitochondria and succinateubiquinone reductase activity in rat blood leucocytes under hypoxic hypoxia and acute microfocal myocardial damage [table: see text] have been shown. At the same time the succinateubiquinone reductase activity of rat myocardial mitochondria do not change substantially. We simultaneously observe the dramatic drop in NADH-ubiquinone reductase activity under experimental myocarditis. This fact demonstrates higher stability of succinateubiquinone reductase system and differences in metabolical processes under hypoxic conditions of different origin. All vitamin E derivatives studied demonstrate substantial antihypoxic activity, which is connected with increased animals' survivability, ubiquinone content in myocardial mitochondria and stabilization and leveling of succinateubiquinone reducatse activity in rat blood leucocytes. alpha-Tocopherolacetate with shortened to six carbon atoms side chain is the most effective in this respect. We discuss possible mechanisms for the realization of vitamin E and its active derivative's antihypoxic effect.

[Ubiquinone content and function in the mitochondrial electron transport chain in experimental focal myocarditis in rats]. / Soderzhanie i funktsionirovanie ubikhinona v tsepi transporta élektronov mitokhondrii pri éksperimental'nom ochagovom miokardite u krys.

The content of ubiquinone and vitamin E and functioning of ubiquinone-dependent enzyme systems in myocardial mitochondria and blood leucocytes of rats under experimental microfocal myocard damage, and the effect of vitamin E under given pathology have been studied. Direct dependence between the content of ubiquinone, vitamin E and activity of succinateubiquinone reductase system of blood leucocytes has been established. Vitamin E demonstrates the normalizing effect on the subjects of our study.

[Comparative study of the effect of alpha-tocopherol, its synthetic metabolite and ionol on dexamethasone-induced apoptosis in rat thymocytes]. / Sravitel'noe issledovanie deistviia alpha-tokoferola, ego sinteticheskogo metabolita i ionola na indutsirovannyi deksametazonom apoptoz timotsitov krys.

alpha-Tocopherol was found to decrease the level of rat thymocytes DNA fragmentation and to increase the viability of these cells under apoptosis induction by dexamethazone. So the antiapoptotic role of this vitamin is suggested. In contrast to alpha-tocopherol synthetic antioxidant ionol and alpha-tocopherylacetate, contained only 6 carbon atoms in its isoprenoid side chain caused the cell death from necrosis. This process preceded the apoptosis stimulated by dexamethazone.

[Vitamin E and apoptosis]. / Vitamin E i apoptoz.

The literature data concerning the participation of tocopherol in apoptosis are discussed. Acting as antioxidant this vitamin exerts a complex effect on apoptosis mechanisms. Its action on this process is caused by involvement of some different mechanisms transducing the apoptotic signal. Among them are caspase and Fas-receptor activation, sphingosine metabolism, processes carried out in nuclei and mitochondria and signal transduction pathways. The specific mechanisms connected with interaction of this vitamin with tocopherol-binding proteins may be also involved in this vitamin action.

[Intracellular localization of thiamine-binding proteins in the liver and kidneys of rats]. / Vnutrikletochnaia lokalizatsiia tiaminsviazyvaiushchikh belkov pecheni i pochek krys.

The distribution of thiamine-binding and thiamine triphosphatase activity typical of thiamine-binding proteins was studied in intracellular structures of rats liver and kidneys. It was found that the fraction of microsomes has the highest rate of specific thiamine-binding activity amide fractions of subcellular structures that was isolated using differential centrifugation in the both organs. Hydrolysis of thiamine triphosphate (pH 7.4) was also extremely active in these structures. The results of our research allow to make a conclusion that subcellular structures precipitated as fraction of microsomes (endoplasmic reticulum and vesicled parts of plasma membranes) are the sites of the most probable localisation of thiamine-binding proteins of liver and kidneys.