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Biomedical subjects

M A Ostrovskiĭ

Publications and source records attributed to M A Ostrovskiĭ.

96 records · Page 6Linked to original sources
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[Spectral sensitivity and visual pigments of the coastal crab Hemigrapsus sanguineus].

It has been shown that the compound eye of the coastal crab has one photosensitive pigment rhodopsin and screening pigments, black and orange one. The orange pigment has lambda max = 480 nm, rhodopsin in digitonin is stable towards hydroxylamin action, has lambda max = 490-495 nm and after bleaching is transformed into free retinene and opsin. The pigments with lambda max = 430 and 475 nm of the receptor part of the eye are also solubilized. These pigments are not photosensitive but they dissociate under the effect of hydroxylamine. The curye of spectral sensitivity of the coastal crab has the basic maximum at approximately 525 nm and the additional one at 450 nm, which seems to be provided by a combination of the visual pigment--rhodopsin (lambda max 500 nm) with a carotinoid filter (lambda max 480-490). Specific features of the visual system of coastal crab are discussed.

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[Study of rhodopsin sulfhydryl groups in the photoreceptor membrane].

The interaction between rhodopsin SH-groups in the photoreceptor membrane suspension with different titrating reagents (Ag HOGM, DTNB) was studied. After rhodopsin bleaching the number of free SH-groups increased from two in the dark to six after illumination. Such increase of SH-groups number was observed only by the amperometric titration procedure. The influence of the "dark" and "light exposed" SH-group modifications on regeneration ability of rhodopsin in the presence of 11-cis-retinal was investigated. No dependence of regeneration on SH-groups modification in the dark was observed, while modification of "light" SH-groups decreases rhodopsin regeneration ability. The distribution of SH-groups in rhodopsin molecules and SH-groups dependence on protein conformation are discussed.

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[Spectral filters as a method of therapeutic correction].

Spectral filters were used for additional correction of vision in 67 patients: in 15 adults with initial cataracts (intensive yellow filter), 26 children with albinism (yellow-brown filter), 14 children with macular hypoplasia (orange filter), and 12 children with aphakia after removal of congenital cataracts (yellow filter). Selection of the filter density is carried out using a special method including visocontrastometry, examination of sensitivity to lateral light, and study of color perception thresholds. Use of filters resulted in improvement of the vision acuity by 43.5% in patients with initial cataracts, by 10% in those with albinism, by 20% in those with macular hypoplasia, and by 22% in those with aphakia; moreover, an improvement of the frequency-contrast characteristics was observed, as well as a reduction of photophobia, and a reduction of vision amplitude in patients with nystagmus. The possible applications of spectral correction are discussed.

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PubMedDate not supplied

[X-ray structural study of the effect of light on isolated bovine photoreceptor membranes].

The structure of multilamellar films prepared by air-drying of bovine retinal rod photoreceptor membrane suspension has been studied by means of small-angle X-ray diffraction methods. No reliable photoreceptor membrane structure modifications were observed with 100 s temporal resolution after the illumination of the film consisting of dark-adopted membranes. The comparative study of air-dried films prepared from dark-adopted and bleached photoreceptor membranes revealed no difference in their structures too. The structure alterations of photoreceptor membranes were recorded in the case of high (damaging) doses of visible light acting on photoreceptor membranes in suspension.

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PubMedDate not supplied

[Retinal as a photo-damage sensitizer of retinal-containing retina proteins].

In vision light may act as an information bearer and a dangerous injury factor. The perfection of visual reception bases on using some "details" which promote free-radical photooxidized destruction. The samples of such "details" are retinal-chromophores of all visual pigments, polyunsaturated fatty acids of photoreceptor membrane phospholipids and thiol proteins. Reliable systems protecting structure of eyes against such damage have been formed in the course of evolution process. The review of details with photosensitizing properties of retinal and some other dangerous endogenous and exogenous sensitizers of retina and retinal pigment epithelium; with mechanisms of rhodopsin and interphotoreceptor retinal binding protein photodamage; with deterioration of structure and function of photoreceptor membrane, visual cells and retina, induced by photooxidation of proteins and lipids; with aggravation role of oxygen.

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