[Study of bioavailability of different forms of synthetic beta-carotene in volunteers].

The concentration of beta-carotene analyzed in blood serum of 30 healthy men and women aged 17-50 years by the method of HPLC in May-June 1990 was in range 3.3-29.5 and in average 12.

[Reconstruction of muscle glycogen phosphorylase b from an apoenzyme and pyridoxal-5'-phosphate and its analogs. Interaction of apophosphorylase and the reconstructed enzyme with specific ligands].

Sedimentation methods were used to study the effects of modification of the pyridoxal-5'-phosphate (PLP) molecule at the 5th position on the affinity of reconstituted muscle glycogen phosphorylase b for the substrate (glycogen) and the allosteric inhibitor (FMN) as well as on the enzyme capacity to association induced by AMP. Reconstituted phosphorylase b was obtained with PLP analogs containing at the 5th position -CH2-CH2-COOH (analog I), trans-CH=CH-COOH (analog II) or -C identical to COOH (analog III) residues. Reconstitution of phosphorylase b is accompanied by the recovery of the enzyme quaternary structure.

[Bioavailability and pharmacodynamics of various forms of synthetic beta-carotene in volunteers].

The biological availability of artificial beta-carotene as a water-soluble versus oily formulation based on cyclodextrin (Cyclocar tablets) was studied on volunteers given a single dose of 25 mg. The concentrations of beta-carotene and major carotenoids were measured in the blood serum during the experiment by high performance liquid chromatography. The maximum content of beta-carotene in the serum was attained 24-30 and 30-48 hrs after oily formulations and Cyclocar and were 48.

[The cytochrome P-450-dependent mono-oxygenase system of the liver and interleukin-1 production by the macrophages in adjuvant arthritis in rats under the influence of beta-carotene].

A relationship between the production of interleukin 1 (IL-1) by macrophages from adjuvant-induced arthritic rats and cytochrome P-450-dependent hepatic microsomal monooxygenase was studied. The synthesis of IL-1 by splenic and peritoneal macrophages on day 17 postadjuvant treatment was not altered, but the hepatic cytochrome P-450 levels and monooxygenase activity were significantly decreased. Beta-carotene treatment of arthritic rats reduced hind paw swelling and concurrently stimulated the ability of macrophages to secrete IL-1 and increased the cytochrome P-450 levels and the activity of hepatic monooxygenase.

[The effect of beta-carotene on the development of adjuvant arthritis and interleukin-1 production in rats].

The production of interleukin 1 (IL1) by peritoneal and splenic macrophages from rats with adjuvant-induced arthritis on day 17 postadjuvant treatment was not altered compared with normal. Treatment of arthritic rats with beta-carotene reduced hind paw swelling and significantly increased ability of macrophages to secrete IL1 as well as stimulated spontaneous proliferation of splenic lymphocytes. No direct relationship between the release of IL1 from peritoneal and splenic macrophages and increase of hind paw swelling was revealed.

[Blood cobalamins and xenobiotic-metabolizing enzymes in rat liver in adjuvant arthritis].

Changes in the total cobalamin content and spectrum of individual forms of these vitamins in blood cells and plasma as well as the activities of enzymatic systems of xenobiotic metabolism in liver microsomes of rats with experimental adjuvant arthritis (AA) have been studied. The total cobalamin content in the blood plasma of rats with AA was increased in comparison with intact animals; however, leucocytes from AA rats were deficient in methylcobalamin (MeCbl). A correlation was found between the ratios of individual cobalamin forms and their total content which was differently expressed in experimental and control animals.

[The vitamin D endocrine system and bone tissue mineral metabolism in rats with adjuvant arthritis: the effect of 1,25-dihydroxyvitamin D3].

Adjuvant arthritis was induced in male rats by injecting bacillus Calmette-Guèrin in mineral oil in a hindpaw. A decrease in bone density, calcium and phosphorus content due to polyarthritis was found in the tibia of the noninjected hind leg. Arthritic rats demonstrated serum 1,25-dihydroxyvitamin D deficiency along with constant level of 25-hydroxyvitamin D.

[The effect of ubiquinone-10 on the development of D-galactosamine-induced hepatitis in rats].

It has been shown that prophylactic administration of ubiquinone protects rats liver from the toxic damage by D-galactosamine both on ultrastructural and on cell levels. Ubiquinone administration prevents necrosis in hepatocytes and preserves their ability for compensatory reactions expressed in activation of protein-synthesis regulating structures in the cell. Ubiquinone decreases hyperfermentemia and hyperbilirubinemia as well as prevents the decrease in liver protein content caused by galactosamine.

[Vitamin B 12 metabolism and the status of sulfhydryl groups in protein-choline deficiency in rats. Effects of methyl- and adenosylcobalamins].

The effect of low protein choline-deficient diet on total vitamin B12 content and individual cobalamin level in the blood serum and liver of rats was determined. Moreover the total and non-protein SH-group content and glutathione transferase activity in the liver of rats were studied. Total cobalamin content increased in the blood serum, but it did not change in the liver of rats fed choline-deficient low protein diet.

[The monooxygenase system, lipid peroxidation in the liver and vitamin B12 metabolism in experimental poisoning of rabbits with phenylhydrazine].

It has been demonstrated that phenylhydrazine poisoning results in a significant activation of lipid peroxidation, reduction of dimethylaniline N-demethylation and NADPH-2.6-dichlorophenolindophenol and NADPH-cytochrome c-reductase activities as well as in the stimulation of the NADPH-nitrotetrazolium reductase activity in rabbit liver microsomes. In addition, phenylhydrazine administration causes disturbances in vitamin B12 metabolism which are manifested as changes in total cobalamin pool and in the spectrum of vitamin B12 individual physiologically active forms in the blood.

[Comparative study of the effect of vitamin B12 coenzymes on monooxygenase system and lipid peroxidation in the liver of rabbits poisoned with phenylhydrazine].

Distinct activation of lipid peroxidation, reduction in N-demethylation of dimethyl aniline and in NADPH-dependent electron transport chain were observed in liver microsomes of rabbits poisoned with phenyl hydrazine. Methylcobalamine and adenosyl-cobalamine, two coenzyme forms of vitamin B12, were firstly shown to serve as modulators of the monooxygenase system, whereas methyl-cobalamine proved to be inductor and adenosylcobalamine-repressor of the system. Administration of methylcobalamine into the poisoned rabbits stimulated much higher the activities of dimethyl aniline N-demethylase, aniline p-hydroxylase, NADPH-cytochrome P-450- and NODH-cytochrome b5 reductases as compared with normal state, while adenosylcobalamine inhibited the reduction of all the monooxygenase system patterns studied.

[Effect of methylcobalamin and adenosylcobalamin on the process of hematopoiesis and vitamin B12 exchange in experimental phenylhydrazine-induced anemia in rabbits].

Poisoning of rabbits with phenylhydrazine resulted in development of haemolytic hyperchromic anemia accompanied by impairment of hemopoiesis in bone marrow as well as by an increase of total vitamin B12 content in blood. The ration of individual forms of cobalamins was firstly estimated in blood serum of healthy rabbits and of the animals treated with phenylhydrazine. Distinct decrease in the methyl cobalamin content was observed in blood serum during spontaneous recovery.

[Cobalamins in normal and pathological states (review)].

Four cobalamines (methyl-, hydroxy-, adenosyl- and cyancobalamines) are considered as natural forms of vitamin B12 in human and animal tissues. Methyl- and adenosylcobalamines are the coenzymes of more than 10 enzymes, catalyzing important reactions of lipid, carbohydrate and protein metabolism. The four natural forms of vitamin B12 are interconverted in presence of corresponding enzymatic systems.

[Cobalamin-protein compounds of bacterial origin (a review)].

Main types of cobalamin-protein compounds from microorganisms are discussed. The first chapter of the review describes low-molecular weight cobalamin-protein complexes and their functional role in the bacterial cells. In the following chapters some structural peculiarities of B12-dependent enzymes and the nature of cobalamin-protein bounds are discussed.

[Coenzyme properties of adenosylcobalamin analogs with modifications in the purine nucleus of the alpha-ligand].

The interaction of cobalamin-dependent glycerol dehydratase from Klebsiella pneumoniae ATCC 25955 with two adenosylcobalamin analogs with modifications in the nucleotide alpha-ligand was studied. It was shown that substitution of 5,6-dimethylbenzimidazole of the alpha-ligand for adenine or 2-methyladenine does not alter the coenzyme activity of glycerol dehydratase and does not affect the substrate binding site of the holoenzyme. These adenosylcobalamin modifications change the affinity of the analogs for the apoenzyme.

[Substrate specificity of adenosylcobalamin-dependent glycerol dehydratase. Interaction with enantiomers of 1,2-propanediol].

Adenosylcobalamin-dependent glycerol dehydratase was shown to catalyze the conversion of both enantiomers of 1.2-propanediol. The kinetic constants for the dehydration reaction of (R)- and (S)-1.

[Interaction of substrates and their analogs with adenosylcobalamine-dependent glycerol dehydratase].

The interaction of AdoCbl-dependent glycerol dehydratase with the substrates (glycerol, 1,2-propandiol, ethylene glycol) and their analogs (aliphatic diols) was studied kinetically. It was found that all the diols tested are competitive inhibitors of the enzyme with respect to substrates. The arrangement of hydroxyl groups in the molecule, the length of the carbohydrate chain and the nature of the substituent at the C-3 atom are essential for the binding of diol in the active center.

[Effect of the structure of the nucleoside ligand of cobalamines on their enzymatic properties in a glycerol dehydratase system].

The interaction between 8 adenosyl cobalamine (AdoCbl) analogs modified in adenine and deoxyribose of the nucleoside ligand and glycerol dehydratase from Klebsiella pneumoniae ATCC 25955 was studied. It was found that araadenosyl-, 3-isoadenosyl-, aristeromycyl- and nebularyl cobalamines possess coenzymic properties. The catalytic activities of these analogs complexes with glycerol dehydratase make up to 110, 36, 30 and 6% of the enzyme activity with the natural cofactor AdoCbl.

[9-(Adenylyl)alkylcobalamins as inhibitors of adenosylcobalamin-dependent glycerol dehydratase from Aerobacter aerogenes].

The behavior of two coenzyme analogs, [(5-aden-9-yl)methoxyethyl] cob (III) alamin and [(5-aden-9-yl)pentyl] cob (III) alamin modified at the nucleoside ligand sugar moiety was studied in the system of adenosyl-cobalamin-dependent glycerol dehydratase from Aerobacter aerogenes. It was shown that neither of the analogs possesses coenzyme properties and that both are strong competitive inhibitors for adenosylcobalamin (AdoCbl). The affinity of the two analogs for the apoenzyme is higher than that of AdoCbl.

[Effect of environmental factors on inactivation of B12-dependent glycerol dehydratase from Aerobacter aerogenes].

Effect of temperature, pH and univalent cation on kinetics of self-activation of B12-dependent glycerol dehydratase (GD) from Aerobacter aerogenes with Co alpha-[alpha-(5,6-dimethylbenzimidazolyl]-Co beta-adenosylcobamide (AdoCbl) was investigated. The activation energy of the process of GD inactivation is found to be 3.9 kkal/M, the effect of pH on GD inactivation being insignificant.