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Biomedical subjects

K O Muranov

Publications and source records attributed to K O Muranov.

13 recordsLinked to original sources
PubMed1987

[Antioxidant-induced release of calcium in biological membranes].

The effect of synthetic (BHT, 2,2,5,7,8-pentamethyl-6-hydroxychroman) and natural (alpha-tocopherol) antioxidants on Ca++-transporting systems was compared in platelets, brain synaptosomes, and skeletal muscle sarcoplasmic reticulum. It was shown that synthetic antioxidants, in contrast to alpha-tocopherol, induced Ca++-release manifested in platelet aggregation, stimulation of 5-hydroxytryptamine release by synaptosomes, synaptosome depolarization and inhibition of Ca++-transport and Ca++-ATPase activity in the sarcoplasmic reticulum. The disturbances of Ca++-homeostasis induced by synthetic antioxidants are considered as molecular mechanisms of complications encountered upon their application.

Animals↗
PubMed1986

[Inhibition of thrombocyte aggregation by antioxidants].

The effects of antioxidants (3-hydroxypyridines, 5-hydroxypyrimidines, hindered phenols) on platelet aggregation were studied. All the compounds under study possessed low anti-aggregation activity against indometacin-sensitive aggregation (activation with arachidonic acid, 50 M). Half-maximal inhibition of aggregation was achieved at a concentration similar to that of the compounds used (10(-3) M in cases of indomethacin-insensitive aggregation, platelet activation by thrombine 1.5 mu/ml and Ca2+-ionophore A23187 1.5 g/ml). 4-methyl-2.6-ditretbutyl phenol (BHT) in the concentration range of 10(-5)-4 X 10(-5) M inhibited and in the concentration range of 4 X 10(-5)-10(-4) M activated indomethacin-sensitive aggregation. The latter effect was not observed in the absence of Ca2+ ions in the incubation medium. It is concluded that the effects of the antioxidants studied on platelet aggregation were due to their non-specific action on platelet membranes.

Antioxidants↗
PubMed1986

[Changes in the cyclic nucleotide level and the inhibition of human thrombocyte aggregation in 3-hydroxypyridine exposure].

The effect of six 3-oxypiridine derivatives (at a concentration of 10(-3) and 5 X 10(-3) M) on cyclic nucleotide level in human platelets and platelet aggregation was studied. Five 3-oxypiridine derivatives were shown to depress platelet aggregation, four of them causing the increase in cAMP platelet level. The correlation between antiaggregation activity of 3-oxypiridine derivatives and their ability to rise cyclic nucleotide level in human platelets is discussed.

Aspirin↗
PubMed1984

[Inhibition of platelet aggregation and cyclic nucleotide phosphodiesterase (specifically cyclAMP) by 3-hydroxypyridine derivatives].

The effects of 3-hydroxypyridine (3-HP) derivatives on platelet aggregation and platelet phosphodiesterase (PDE) of cyclic nucleotides (cAMP-dependent) were studied. It was shown that some derivatives of 3-HP inhibit platelet aggregation (the most pronounced effect was exerted by 2-benzyl-3- oxypyridine ). Several derivatives o 3-HP given in a concentration 10(-3) M were discovered to inhibit PDE by 40 to 75%. No correlation was found between the efficacy of 3-HP as antiaggregation agents and PDE inhibitors.

1-Methyl-3-isobutylxanthine↗
PubMed1983

[Effect of antioxidants on the release of 3H-serotonin by rat brain synaptosomes].

The effects of free radical scavengers of different chemical structure (hydroxypyridines, hindered phenols, hydroxyphenothiazines) on processes of 3H-hydroxytryptamine uptake and release by rat brain synaptosomes were studied. All free radical scavengers used inhibited 3T-hydroxytryptamine uptake and stimulated 3H-hydroxytryptamine release, with the efficacy being reduced in the following order: 7-hydroxyaminazine greater than butylated hydroxytoluene greater than paginol-2-methyl-6-ethyl-3-hydroxypyridine greater than alpha-tocopherol. The effects of free radical scavengers were eliminated in the presence of EGTA or after cooling to 4 degrees C.

Animals↗
PubMedDate not supplied

Damage of photoreceptor membrane lipids and proteins induced by photosensitized generation of singlet oxygen.

It has been shown that illumination of rod outer segment suspension in the presence of photosensitizers (methylene blue lambda greater than or equal to 620 nm; retinal 370 less than or equal to lambda less than or equal to 390 nm) results in chemical modification of the lipid and protein components of the photo-receptor membranes. This modification can be registered by accumulation of lipid peroxidation (LPO) products as well as oligomerization of rhodopsin and a decrease of rhodopsin thermal stability. These effects are prevented by 'O2-quenchers and free radical scavengers. It has been found that the electric activity (ERG) of isolated frog retina is inhibited due to photosensitized generation of 'O2 which can be overcome by preliminary addition of 'O2-quenchers and free radical scavengers to the incubation medium. The LPO products are accumulated in the retinae of rats exposed to high intensity light in vivo. It is concluded that 'O2 and LPO are involved in light-induced damage of the retina.

Animals↗
PubMedDate not supplied

[Comparative study of the crystallin supramolecular structure in the carp, frog, and rat lenses by small-angle roentgen ray scattering].

The supramolecular structure of crystallins in intact ocular lenses of carp, frog and rat as well as in the interior (nuclear) and outer (cortical) parts of these lenses was studied by the small-angle X-ray scattering method. The results show that the supramolecular structure of crystallins substantially varies both in lenses of different vertebrate species and in various parts of the same lens. In carp lens and in the cortical part of rat lens, crystallins have an ordered supramolecular structure, as indicated by a small-angle X-ray diffraction maximum in the region of Bragg distances 15-20 nm, whereas in frog lens and in the nuclear part of rat lens, the supramolecular structure of these proteins is disordered. The power-law X-ray scattering by rat lens nucleus may be evidence of fractal structures in the lens. A comparison of these results with literary data indicates that there is no obvious correlation between the type of supramolecular structure of crystallins and their polypeptide composition in lenses of different vertebrate species. The results suggest that the supramolecular ordering (short-range order) of crystallins is not a necessary condition for lens transparency.

Animals↗
PubMedDate not supplied

[Studies of alpha- and betaL-crystallin complex formation in solution at 60 degrees C].

Studies of molecular mechanisms of chaperone-like activity of alpha-crystallin became an active field of research over last years. However, fine interactions between alpha-crystallin and the damaged protein and their complex organization remain largely uncovered. Complexation between alpha- and betaL-crystallins was studied with thermal denaturation of betaL-crystallin at 60 degrees C using small-angle X-ray scattering (SAXS), light scattering, gel-permeation chromatography and electrophoresis. A mixed solution of alpha- and betaL-crystallins in concentrations about 10 mg/ml incubated at 60 degrees C was found to contain their soluble complexes with mean radius of gyration approximately 14 nm, mean molecular weight approximately 4000 kDA and maximal size approximately 40 nm. In pure betaL-crystallin solution, complexes were not observed at 60 degrees C. In SAXS studies, transitions in the alpha-crystallin quaternary structure at 60 degrees C were shown to occur and result in a double increase of the molecular weight. It suggests that during the temperature-induced denaturation of betaL-crystallin it binds with modified alpha-crystallin or, alternatively, alpha-betaL-crystallin complexation and alpha-crystallin modifications are concurrent. Estimates of the alpha-betaL-crystallin dimensions and relative contents of alpha- and betaL-crystallins in the complex suggest that several alpha-crystallin molecules are involved in complex formation.

Crystallins↗