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Biomedical subjects

A I Deev

Publications and source records attributed to A I Deev.

54 records · Page 3Linked to original sources
PubMedDate not supplied

[Morphometric analysis of lens opacification].

A method of classifying cataractous changes in excised human cataracts that was based on separate and independent photographic documentation with subsequent quantitative evaluation of lens opacification has been proposed. The degree of lens clouding was evaluated quantitatively by measuring the optical density index and the area of clouding with certain optical density parameters (equidensities) by use of a texture analyzer system apparatus. This technique made it possible to obtain the contrast image of the lens clouding areas in the frontal projection and to determine their share in the total area of the lens surface. The precise topography of the opacities was established. The data obtained for different clinical types of cataracts help the scientist in his effort to measure clinically or scientifically significant quantitative associations between laboratory measures and cataractous changes.

Aged↗
PubMedDate not supplied

[Spin label study of structural changes at different depths of phospholipid membranes after their peroxidation].

Changes of structural organization of liposomal phospholipid membranes, after their Fe2+-induced peroxidation were studied at different depth using nitroxyl derivatives of stearic acid. It was established that during Fe2+-induced lipid peroxidation a strong rise in lipid polarity accompanied with immobilization of acyl chains of phospholipids at the depth of 0.6-0.8 nm from the surface was measured. At the same time no significant changes in the structural organization were seen at the depth of 20-22 nm.

Electron Spin Resonance Spectroscopy↗
PubMedDate not supplied

[Modification of membrane structures in cataract].

Early alterations relating to lenticular opacity occurred long before large protein aggregates formation in the lens and in plasma membranes of lens fibres. At the first step of human cataract development membranes contained typical knobs, sockets and fragments. Then, with development of cataract, further fragmentation and undulation of lens membranes were observed; surface of the fibre membranes was increased. At the later steps of lenticular opacity partially disintegrated fragments of lens fibres were detected, free membrane structures disappeared and the globules containing protein-lipid complexes of various size and density were formed; these globules were involved in lenticular opacity. With growing of cataract lipid fraction of the lens accumulated primary (hydroperoxides), secondary (diene conjugates and diene ketones) and the end products (Schiff bases) of lipid peroxidation. Ultrastructure modification of membranes in cataract appear to occur in response to accumulation of the lipid peroxidation products. This suggests that lipid peroxidation not only accompany the cataract development but may be among the main pathogenic factors of the disease.

Cataract↗
PubMedDate not supplied

[Cataract induction by products of lipid peroxidation].

Liposome suspension prepared from the unsaturated phospholipids exposed to lipid peroxidation (LPO) induced posterior subcapsular cataracts after injection into the posterior vitreous of rabbit eyes. In the background of this model lies a type of lens opacity formed during retinal degeneration when toxic peroxide substances diffuse anteriorly through the vitreous body resulting in vitreous opacities and complicated cataracts. Saturated liposomes (prepared from beta-oleoyl-gamma-palmitoyl) L-alpha-lecithin) did not induce lens opacities, which is the evidence that a lipid peroxidation mechanism may be responsible for the posterior cataracts. Along with cataract formation accumulation of LPO fluorescent products in vitreous, aqueous humor and lens was observed. It was followed by a decreased level of reduced glutathione in the lens. The obtained results strongly support the hypothesis of LPO initial role in cataracts.

Animals↗
PubMedDate not supplied

[Free radical oxidation of lipids and thiol groups in the formation of a cataract].

Content of primary (diene conjugates), secondary (ketodienes), end (Schiff's bases) products of free radical oxidation (FRO) of lipids was determined, as well as content of total and non-protein-bound thiols in human lens at different stages of cataractogenesis. Lens opacity was estimated by quantitative morphometric analysis. Participation of FRO of lipids in lens opacity is proved. It is shown that total thiols of lens fibres are rapidly inactivated when the intensity of lipid FRO is increased at the expense of the fall of glutathione level. These processes promote the formation of high molecular protein aggregates in the lens and cataract development. Coefficients of linear correlation between the indicated parameters are presented. A conclusion is drawn concerning possible prevention of cataract development by decreasing the level of accumulation of lipid peroxides and by maintaining high concentration of reduced glutathione in the lens.

Cataract↗
PubMedDate not supplied

[NMR study of the state of water in the human lens during cataract development].

Water proton spin-spin relaxation times (T2) and the content of bound, "non-freezable" at -9 degrees C water in both normal human lenses and human lenses of different stages of cataract progression (cataracta incipiens, nondum matura, mature hypermatura) were measured by NMR spin echoes method. By the stage of cataracta nondum matura, increase of bound water content and simultaneous, almost half decrease of the relaxation time (T2), were observed. However, on the following stages of cataract evaluation (almost mature, mature cataracts) a gradual decrease of bound water content is noted, but only for the mature cataract stage the water content significantly differs from that of the normal one. On the stage of hypermature cataract the presence of two unexchanged with each other fractions of water is found. The obtained data are explained by lens protein reconstructions during the cataract progression.

Body Water↗
PubMedDate not supplied

[Effect of peroxidation on the physical structure of phospholipid membranes].

Peroxidation of lipids caused rearrangements in physical structure of biomembranes as it was shown by a method of fluorescent probes. These structural rearrangements were accompanied by an increase in the viscosity on the surface and in the depth of the phospholipid bilayer. The increase in the viscosity was apparently due to oxidation and to elimination from the phospholipid bilayer of the unsaturated fatty acid residues. Presence of the unsaturated fatty acids in biomembranes decreases their viscosity. The fraction of saturated fatty acids after peroxidation was respectively increased in the bilayer.

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

[Increase of the water content in the lipid phase of lipoproteins during peroxidation].

By means of fluorescent probes of pyrene and 4-dimethylaminochalcone (DMC) an increase of polarity of the lipid phase of lipoproteins of low density LDL during their autooxidation was discovered. The observed change of polarity is explained by the penetration of water molecules into the LDL phospholipid layer, which form hydrogen bonds with polar groups resulting from the peroxidation of lipids. Such "water corrosion" of the membranes is suggested to bring about a change of matrix properties of the phospholipid layer, particularly a change in LDL protein conformation discovered earlier during peroxidation.

Fluorescent Dyes↗
PubMedDate not supplied

[Determination of phospholipase A2 activity in liver mitochondria using fluorescent dye 1,8-anilinonaphthalene sulfonate].

Quantitative estimation of free fatty acids was carried out in liver mitochondria of normal and thyroidectomized rabbits by means of two procedures--spectrophotometry using rhodamine 6Zh and a fluorescent method with 1,8-aniline naphthalene sulfonate /ANS/ as a dye. The use of ANS enabled to estimate quantitatively the free fatty acids beginning from 25 nmol in a sample /with eggor of about 17%/ by visual evaluation of the spot areas. As compared with the rhodamine procedure, use of ANS permitted to increase 5-fold the sensitivity of free fatty acid estimation, to elevate 6-fold the accuracy of the analysis, to overcome the step of fatty acid elution from chromatogramms and to decrease the time required for analysis. The data obtained suggest that the hyperthyroid state in rabbits was accompanied by an increase in the phospholipase A2 activity in liver mitochondria.

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

[Influence of the physical structure of phospholipid membranes on peroxidation induced by Fe2+ ions].

Kinetics of free radical lipid peroxidation, induced by Fe2+ in presence of ascorbic acid, was studied in phospholipid membranes. The maximal rate of peroxidative oxidation was observed at 2.5 muM concentration of Fe2+, in this case a half of the maximal amount of peroxidative oxidation products was formed within 20-30 min at 20 degrees and at 200 muM concentration of ascorbic acid. The rate of peroxidative oxidation depended on addition of substances modifying the membrane structure (linoleic acid, cetyl trimethylammonium, Tween-60, derivatives of phenothiazol). Charge of the membrane surface was shown to have a distinct effect on the peroxidative oxidation. Loosening of membranes by non-ion detergent (Tween-60) increased the rate of the process, whereas the increase of the membranes rigidity by cholesterol did not cause any effect. Uneffectiveness of cholesterol is discussed with relation to diffusion of radicals, participating in peroxidative oxidation, from depth of the membrane to its surface and in the opposite direction.

Ascorbic Acid↗
PubMedDate not supplied

[Changes in the serum albumin system during toxic syndrome and their pharmacologic correction].

In connection with the important role of serum albumins in pathogenesis and sanogenesis of numerous toxic states, we examined binding capacity of these proteins and conditions of their binding sites after acute poisoning with tetrachloromethane (TCM) and administration of antihypoxic agents (sodium gamma-hydroxybutirate), antioxidants (Dibunol), and actoprotector (Tomersol) to rats. We demonstrated that tetrachloromethane intoxication (3.2 g/kg over 24 h) was accompanied by a certain decrease (by 13.8%) in the total blood serum level of albumins and a tendency to a decrease in the value of the binding constant of negatively charged fluorescent probe 1-(phenylamino)-8-sulfonaphthalene. Under these conditions, the mean number of probe binding sites per albumin molecule increases, and as a result, the total concentration of albumin binding sites in the serum remains virtually unchanged. We found that accessibility of the probe to a quenching agent (potassium nitrate) increases in the protein--probe complex under intoxication conditions, suggesting that the type of interaction between the protein and the fluorescent probe changes as well. Therapeutic/prophylactic administration of an antioxidant, antihypoxic agent, or actoprotector leads to an increase in the level of albumin in the serum (Tomersol), partial normalization of its binding properties (binding constant in the case of sodium gamma-oxybutirate, mean number of binding sites per molecule for Dibunol and Tomersol), and the state of binding sites (sodium gamma-oxybutirate, Dibunol).

Anilino Naphthalenesulfonates↗
PubMedDate not supplied

[Comparative study of antiradical effects of several antiglaucoma drugs].

Studies of the in vitro inhibitory effects of drugs most often used in the treatment of primary glaucoma on the generation of the main active oxygen forms (hydroxyl radical, superoxide anion radical, singlet oxygen and radical products of hydrogen peroxide and peroxidase reaction) showed that antiradical activity is more intrinsic for thimolol and decreases in the following series: betoptic-pilocarpinclofelin. This once more validates the efficacy of beta-blockers in the treatment of glaucoma and prevention of cataract associated with it.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

[Distribution of small hydrophobic molecules in membranes. II. Heterogeneity of binding centers on a phospholipid bilayer surface].

4-dimethylaminochalcone (DMC), a hydrophobic uncharged fluorescent probe, was bound to a phospholipid bilayer surface and was distributed in different binding sites. Sites whose polar groups of phospholipid and hydration shell molecules were the least mobile had the greatest affinity to DMC. The increase DMC/phospholipid ratio resulted in DMC molecules getting bound to sites of a lesser affinity whose polar groups were more mobile. Cholesterol presence caused DMC binding to the first type of sites only.

Binding Sites↗