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Biomedical subjects

M A Ostrovskiĭ

Publications and source records attributed to M A Ostrovskiĭ.

At least 91 records · Page 5Linked to original sources
PubMedDate not supplied

[Aggregation of rhodopsin molecules during damaging exposure of photoreceptor membranes to light].

Injuring light induced structural changes in rod outer segment (ROS) membranes are studied using "ST EST spectroscopy" for spin labelled rhodopsin, ESR of lipid spin label and SDS gel-electrophoresis. Free SH-group content of rhodopsin and lipid peroxidation level were simultaneously determined as well. A decrease of rotational mobility of rhodopsin in ROS induced by prolonged illumination is shown to result from irreversible protein aggregation caused by disulfide bond formation between "hydrophobic" SH-groups of rhodopsin. Some decrease of lipid microviscosity and degree of order are found, in contrast to considerable rise in microviscosity due to Fe2+-ascorbate induced lipid peroxidation of ROS membranes. Lipid oxidation is found to accelerate protein aggregation which in its turn influences the state of lipid bilayer.

Animals↗
PubMedDate not supplied

[Mechanism of glutathione oxidation by photosensitized retinal].

Sulphur radicals appearing in the retinal photosensitized glutathione oxidation have been recorded by spin trapping. There is no reaction in the absence of oxygen. That is why the single oxygen is supposed to take part in the reaction (IId type photosensitized reaction).

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[X-ray diffraction in the intact isolated frog ocular lens].

X-ray diffraction method has been applied for investigating ocular lens native tissue of the frog. X-ray diffraction patterns of intact lenses, their nuclei and cortices are similar and contain a set of concentric diffuse diffraction maxima. The most intensive of these maxima corresponding to the Bragg-spacings of 14.6, 9.1 and 4.6 A are presumably associated with intramolecular structure of lens proteins--crystallins. Intensive small-angle X-ray scattering and diffraction patterns isotropy indicates unavailability of crystallin molecule ordering or orientation in the lens. The shift of 14.6 A maximum up to 12.8 A being the result of nuclei drying shows the necessity of aqueous surrounding for these protein native structure maintenance.

Animals↗
PubMedDate not supplied

[Comparative study of bovine ocular lens proteins in native tissue and an extract using the x-ray diffraction method].

It has been shown that the maxima (Bragg-spacings 4,5-19 A) on the X-ray diffraction patterns of the bovine lens native tissues from nuclear and cortical parts are predominantly due to the water-soluble crystallin intramolecular structure. The structures of water-soluble and water-insoluble fractions from bovine lens nucleus and cortex were qualitatively compared. Reversible dependence of the lens water-soluble protein structure on water content in the system was demonstrated.

Animals↗
PubMedDate not supplied

[Comparative x-ray diffraction study of the crystalline lens in a number of vertebrates including man].

X-ray diffraction method has been applied for comparative investigation of native structure of eye lens proteins (crystallins). X-ray diffraction patterns of the whole lenses and/or their nuclear parts were obtained for man and vertebrate animals. Crystalline lenses of the fishes Acerina cernua and Pelmatochromis kribensis, frog Rana temporaria, bull and man contain crystallins with a very similar secondary and tertiary structure, whereas lenses of chicks and the tortoise Testudo horsfieldi contain mainly crystallins with other structure. The results obtained reveal evolutionary conservatism of crystallin structure in fishes, amphibians and mammals. It was also concluded that there is no correlation between crystallin structure of the lens, elasticity of the latter and accommodation mechanism.

Accommodation, Ocular↗
PubMedDate not supplied

[Photodamage of rhodopsin molecule. Oxidation of SH-group].

Illumination of rod outer segments with bright visible light results in the oxidation of both protein and lipid components of the photoreceptor membrane. The oxidation degree depends on the intensity and time of illumination. The inhibitors of free radical processes completely inhibit lipid oxidation and somewhat decrease protein oxidation. Photooxidation systems of lipids and rhodopsin also react differently to oxygen content in the incubation medium. Retinal is the photosensitizer of the oxidation of the photoreceptor membrane components.

Animals↗
PubMedDate not supplied

[Light adaptation shift in the spectral sensitivity of cones in the frog Rana temporaria].

Spectral properties of frog's "red" cones and their mass receptor potential during blue colour adaptation (370--500 nm) have been investigated. The spectral sensitivity maximum depended on the season: in September, frogs had mean lambda max of 572 +/- 4, whereas in December and January-- 553 +/- 4 nm. Low background light resulted in shift of the spectral sensitivity curve to short wavelengths. The background effect did not depend on the wavelength. The shift of spectral sensitivity was accompanied by the increase of LRP to green stimuli and the decrease of LRP to shorter wavelengths. This effect developed not earlier than 5 min after the beginning of light adaptation. The range of the spectral sensitivity maximum shift varied within 575--525 nm, while changes in the amplitude did not exceed 25 nm. The data obtained indicate the shift of spectral sensitivity of "red" cones due to background illumination. This shift is presumably due to ionochromic changes of the visual pigment of the cones. It its turn, chloride redistribution might take place due to light-induced changes in the membrane potential of cells.

Adaptation, Ocular↗
PubMedDate not supplied

[Antioxidative function of the melanoprotein granules of the rabbit pigment epithelium of the eye].

The intensity of peroxide oxidation of lipids in the pigmented epithelium of the eye, under hyperoxic conditions, is approximately 6 times lower in pigmented rabbits as compared to albino ones. In pigmented animals, the pigmented epithelium of the eye exerts evident protective effect during the action of oxygen on the retina. It is suggested that the observed inhibition of peroxide oxidation of lipids in the pigmented epithelium of pigmented animals is due to anti-oxidative effect of melanoprotein granules.

Animals↗