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Biomedical subjects

A G Maksina

Publications and source records attributed to A G Maksina.

At least 19 recordsLinked to original sources
PubMed1997

[Structural organization of red blood cell membranes in pregnant women with gestosis].

Activated lipid peroxidation (LPO) was found to occur with decreased antioxidative activity (AOA) in gestosis, by deteriorating the structural and functional properties of cell membranes. This enhanced the permeability of the phospholipid bilayer and altered the function of membranous proteins and the synthesis of biologically active agents, by involving the systems responsible for microcirculatory homeostasis. Enhanced membrane hydrophilicity and increased LPO and AOA are typical of the second and third trimesters of normal pregnancy. Pregnant with gestosis generally show higher microviscosity and hydrophilicity of membranes and enhanced blood LPO.

Cell Membrane Permeability↗
PubMed1996

[The structural status of red blood cell membranes in children with insulin-dependent diabetes mellitus. Examination by spin probe].

Using spin probes-stearic acid analogues, the authors investigated the microviscosity and the a/b parameter of red blood cell membranes in children with diabetes mellitus. The structural changes were correlated with altered metabolic measurements. The change in the pathway of insulin in diabetes mellitus led to the structural state of red blood cell membranes.

Adolescent↗
PubMed1991

[The state of erythrocyte membranes in diabetes mellitus].

Study of red cell membranes in diabetics has shown that physicochemical shifts in the red cell membrane lipid bilayer, elevated lipid peroxidation, and disordered thiol compound metabolism are among the crucial aspects in the pathogenesis of diabetes mellitus. EPR spectroscopy in complex with other biochemical methods will help monitor the adequacy of therapy.

Diabetes Mellitus↗
PubMed1989

[The auditory area of the cat cerebral cortex after implantation of electrodes into the inner ear (morphologic and biophysical research)].

The article presents the findings of experimental studies of morphological and biophysical changes in the A1 hearing zone of the cerebral cortex depending on the period of the electrodes implantation in the inner ear. The studies showed that in the process of long implantation in the neurones of the hearing zone one can notice the disorders of water-electrolytic exchanges. There is a definite correlation between structural changes in microsome membranes of A1 zone and morphological data.

Animals↗
PubMed1988

[Use of the spin label method for studying the structure of the brain membranes in cats with streptomycin poisoning].

The structural changes in cat brain membranes under the injections of intramuscular streptomycin which is ototoxic antibiotic have been studied. The increase of membrane microviscosity in brain areas which are the direct projection of the auditory way has been revealed using fat acidic spin probe on the basis of stearic acid. The changes in membranes of other brain areas have not been found that exhibits a specific streptomycin influence on the auditory analyzer. The EPR spectra of the hydrocarbon spin label C12H25 localizing in near membrane region don't change in brain membranes of experimental animals compared with the normal ones.

Animals↗
PubMed1984

[Effect of hypothyroidism on the structural and functional characteristics of the sarcoplasmic reticulum of rabbit skeletal muscles].

Structural and functional characteristics of sarcoplasmic reticulum vesicles (SRV) from skeletal muscle of normal and hypothyroid rabbits were investigated. The rate of Ca2+ absorption was decreased in hypothyroid animals and Ca2-ATPase activity in SRV of these animals was lower than that of control rabbits. The transport ratio (Ca2+/ATP) in hypothyroid rabbits was higher by 20% than in controls. In SRV of hypothyroid animals a decrease in the protein/lipid interaction and higher fluidity of membrane lipids were observed. Administration of L-thyroxine (300 mg/kg of body mass, intraperitoneally) normalized the SR lipids fluidity within about 40 hrs after the injection but did not affect significantly the patterns of protein/lipid interaction. Normal and hypothyroid SRV were similar in their protein spectrum as shown by electrophoresis in polyacrylamide gel. These alterations observed in the SRV structure and function are apparently related to modifications of membrane lipids.

Absorption↗
PubMed1983

[Spin labels in the analysis of Ca-ATPase in the sarcoplasmic reticulum of rabbit skeletal muscles in hypercholesteremia].

The method of electron paramagnetic resonance with spin-labeled maleimide was used to study variation of the structure of Ca-ATPase of the sarcoplasmic reticulum (SR) in rabbit skeletal muscles under long-term hypercholesterolemia (HC). The rate of the maleimide spin label binding with Ca-ATPase of the SR was decreased in HC, which correlated with a lesser access of spin-labeled thiol groups for potassium ferricyanide and sodium ascorbate. HC led to a considerable reduction in the lability and to enhancement of hydrophobia of the spin-labeled fragment of the enzyme. It is concluded that the disordered function of the SR Ca-pump is a consequence of structural changes in the Ca-ATPase molecule in HC.

Animals↗
PubMed1983

[Modification of an enzymic system for Ca2+ transport in sarcoplasmic reticulum in lipid peroxidation. Change in the molecular organization of the lipoprotein Ca-ATPase complex].

Using ESR spectroscopy of spin probes and spin labelling, the effects of lipid peroxidation (LPO) on the molecular organization of Ca-ATPase from rabbit skeletal muscle sarcoplasmic reticulum membranes were studied. Accumulation of LPO products caused an increase of the hydrophobicity and a decrease of the mobility of the Ca-ATPase polypeptide chain fragment immediately proximal to the enzyme active site. Induction of LPO in the membranes resulted in a decrease of the thermal stability of the lipoprotein Ca-ATPase complex which occurred as a biphasic process. At temperatures of 36-38 degrees C this thermodenaturation consisted in a shift of the Ca-transport ability towards a lower temperature region corresponding to the shift in the low temperature break on the Arrhenius plots for parameter 2A'zz of the maleimide spin label. Within the temperature range of 49-52 degrees C an earlier LPO-induced denaturation determines the low temperature shift of the point for a sharp decrease of the Ca-ATPase activity and of the corresponding break for parameter 2A'zz as well as the dissociation point for the lipoprotein Ca-ATPase complex and the corresponding breaks on the Arrhenius plots for the solubilization parameter, alpha, and the order parameter of spin probes, S.

Animals↗
PubMed1982

[Interaction of spin-labelled phosphatidyl choline with Ca-dependent ATPase from sarcoplasmic reticulum].

The interaction between 3-acyl-2-(6-doxylpalmitoyl) phosphatidyl choline used as a hydrophobic spin probe and Ca2+-dependent ATPase from sarcoplasmic reticulum membranes of rabbit and carp white skeletal muscles was studied. The spin label incorporation into ATPase preparations was performed at initial steps of ATPase isolation by incubating reticulum membranes with the spin probe in the presence of cholic acid. A comparison of the molecular mobility of the probe incorporated into ATPase preparations and into liposomes formed from ATPase phospholipids demonstrated that the presence of the protein in the membrane produces the same effect on the probe mobility as does the decrease of temperature by 10-15 degrees C. The molecular mobility of the probe in the ATPase preparation is increased during protein thermal denaturation. The breaks on the Arrhenius plots for the probe molecular mobility are revealed at the same temperatures (25 degrees for rabbit reticulum and 16 degrees for carp reticulum) as those for the ATPase activity.

Animals↗
PubMed1981

[Interaction between free fatty acids and Ca2+-dependent ATPase from sarcoplasmic reticulum membranes].

The interaction between free fatty acids and Ca2+-dependent ATPase, an intrinsic protein of sarcoplasmic reticulum membranes, was studied with relevance to the changes in membrane permeability induced by free fatty acids. It was found that only unsaturated fatty acids increase the permeability of reticulum membranes for Ca2+, this effect being completely reversible. The increase in the membrane permeability by fatty acids is coupled to a generation of a channel for Ca2+ efflux under effect of Ca2+-dependent ATPase. The interaction between fatty acids and Ca2+-dependent ATPase was demonstrated by the protein fluorescence and electron paramagnetic resonance methods, using spin-labelled fatty acid derivatives. A model demonstrating the increase of sarcoplasmic reticulum membrane permeability for Ca2+ in the presence of the fatty acid-Ca2+-dependent ATPase complex is proposed.

Animals↗
PubMed1980

[Thyroxine: structural transformations in the membranes of rabbit skeletal muscle sarcoplasmic reticulum].

The structure of the membranes of sarcoplasmic reticulum fragments (SRF) normally and in thyrotoxicosis was studied by the spin-label and spin-probe methods and by chemifluorescence. The curves of temperature dependence of the regularity parameter show a typical break for the spin probe at 20 degrees C shifted by 4 degrees C to sower temperatures for thyrotoxins. The same shift was observed with temperature dependence for the correlation period of the spin label covalently bound to the thiol groups of Ca2+ dependent ATPase of sarcoplasmic reticulum. The latent period of thyrotoxins was reduced and the chemifluorescence intensity increased. The results obtained suggest the occurrence of considerable changes in the structure of SRF membranes in thyrotoxicosis.

Animals↗
PubMedDate not supplied

[Using the spin label and probe method in medical research].

Spin probe methods applied in membrane medical research are reviewed. The results of erythrocyte membrane studies in diabetes demonstrate potentialities of the methods in medical investigations. The new data on the changes occurring in the erythrocyte membranes of patients suffering from type I diabetes are under discussion.

Diabetes Mellitus, Type 1↗