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Biomedical subjects

A M Belous

Publications and source records attributed to A M Belous.

At least 19 recordsLinked to original sources
PubMed2000

[The level of middle mass molecules and lipid peroxidation in blood of patients with different forms of stroke].

To elucidate correlation between processes of lipid peroxidation (LP) and accumulation of peptides from the group of "middle molecules" (PMM) in blood, we made investigation of blood of 81 patients with ischemic and hemorrhagic stroke. Gel-filtration column chromatography for PMM separation was performed. Divided fractions were registered with UV-monitor at wave length equal to 254 nm. The character of both spontaneous and Fe(2+)-induced chemiluminescence, the level of malonic dialdehyde (MDA) and conjugated dienes (CD) were estimated. It was established that the level of LP processes was significantly increased in blood and erythrocytes of patients with stroke, especially in hemorrhagic form. The total content of PMM, especially of A and A4 fractions, as well as D and F fractions was almost twice as much in blood. A correlation was observed between accumulation of PMM in blood of patients with stroke and PL induction, that may be the factor of PMM generation. A conclusion was made, that accumulation of some PMM classes in blood of patients with strokes was related to LP processes, which were responsible for the severity of the secondary pathochemical alterations in tissues of the brain. These findings should be considered in elaboration of drug treatment and estimation of the disease prognosis.

Adult↗
PubMed1990

Examination by fluorescence and EPR spectroscopy of the state of mitochondrial and lysosomal membranes upon freeze-thawing.

The results of spectroscopic examination of mitochondria and lysosomes indicate that freeze-thawing leads to alterations of different character and extent in membrane structural organization which manifest as changes in the molecular packing of the organelle membrane lipid bilayer, lateral separation of lipids into individual domains, and impairment of membrane permeability. Supercooling of organelle suspensions without crystallization of external water has been found not to affect membrane barrier function markedly; however, such a decrease in the temperature results in a slight loosening of the membrane with an increase in the volume of subcellular structures. The crystallization of external water causes dehydration of organelles, which favors a decrease in their volume, increasing the viscosity of the liquid phase inside subcellular structures and packing the lipid bilayer. Changes in the permeability of mitochondrial and lysosomal membranes manifest during thawing after the formation of an external liquid phase and might be due to the sharp rehydration of these membranes through latent membrane defects formed upon freezing.

Animals↗
PubMed1990

[Structural reorganizations of the lipids and proteins of erythrocyte membranes under the action of low temperatures].

The reversible structural rearrangement of lipids and protein oligomerization has been shown to occur during cooling in membranes of model systems (liposome, erythrocyte shadows) and native erythrocytes. Analysing the dependence of Azz in membrane probes (5- or 15-doxylstearic acids) in the Arrhenius plots a conclusion on the structural changes at 13-19 degrees C and within the range of interior water freezing from -17 up to -19 degrees C has been drawn, the last transition is smoothed out in the presence of glycerin. Using diamide joining spectrin and electrophoresis in polyacrylamide gel it has been determined that the low temperatures cause the spatial approach of proteins of spectrin-actinic complex and formation connections between the erythrocyte membrane proteins which aren't destroyed by dodecylsulfate.

Cold Temperature↗
PubMed1989

[Energy state of hepatocytes of fed rats isolated by the means of EDTA and vibration].

The energy state of mitochondria in fed rat hepatocytes isolated by the use of non-enzymatic method including liver perfusion with an EDTA-containing solution with a further mild mechanical effect of tissue fragments by vibration has been studied. The isolation procedure used permits to obtain significant amounts of hepatocytes whose viability is not less than 80%. The endogenous respiration rate (10-15 nm O2/min.mln cells) is slightly stimulated by succinate. In the course of incubation in a balanced salt medium, the cells accumulate ATP and the lipophilic cation, tetraphenylphosphonium. Data from the inhibitory analysis testify to the fact that tetraphenylphosphonium accumulation reflects the membrane potential of intact cell mitochondria, which are in a metabolic state similar to state 3.

Adenosine Triphosphate↗
PubMed1983

[Biochemical indices of erythrocytes cryopreserved with protection by 1,2-propanediol and glycerin].

Based on the data concerning the content of ATP, 2,3-DFG, K+, and Na+ in depreserved red cells stored at 4 degrees C in resuspending media TsNIIGPK 8b and 8v it has been established that blood preserved under protection of 1,2-propanediol is comparable with that preserved under glycerin protection as regards its quality and is even better from the standpoint of some other indicators. Medium TsNIIGPK 8v may be used as resuspending medium for blood exposed to low temperature preservation under protection of 1,2-propanediol.

Adenosine Triphosphate↗
PubMed1982

[Effect of freezing-thawing rates on the functional state and ionic permeability of rat liver mitochondria].

The effects of various rats of freezing-thawing reactions on the functional state and ionic permeability of rat liver mitochondria were studied. The degree of mitochondrial damage during the freezing -- thawing process depended on the rate of thawing rather than on that of freezing. The mitochondria which were slowly or rapidly frozen down to --196 degrees and subsequently slowly thawed revealed a higher membrane permeability for K+ Na+ and H+ and a more than 2-fold increase of the ATPase activity and the maximal rate of NADH oxidation via the antimycin-insensitive pathway in the presence of cytochrome c. This was concomitant with a complete inhibition of the ATP-synthetase activity and a marked inhibition of the respiratory chain function due to the efflux of cytochrome c from the inner mitochondrial membrane. After freezing and rapid thawing the functional activity of mitochondria changed insignificantly. A comparison of different cryoeffects demonstrated that the minimal damaging effects were exerted by rapid freezing -- rapid thawing, when the mitochondria partly restored their ability for oxidative phosphorylation.

ATP Synthetase Complexes↗
PubMed1982

[Effect of excess cooling on rat liver mitochondria: release of K+ and malate dehydrogenase at lipid phase transition temperatures].

The effects of cooling within the temperature range of 0-25 degrees on the state of mitochondrial membranes was studied. The increase in membrane permeability for K+ and malate dehydrogenase which is localized in mitochondrial matrix, served as an index of membrane structural damage within the given temperature interval. In order to prevent crystallization of the aqueous phase upon cooling ethylene glycol was added to the medium to reach a final concentration of 40%. The decrease of temperature resulted both in the release of K+ and in the increase of the activity of free malate dehydrogenase. A drastic increase in the mitochondrial membrane permeability to K+ and malate dehydrogenase was observed within the temperature range of -6 -- -14 degrees, showing a maximum at -10 degrees. At -14 degrees the rate of K+ and malate dehydrogenase release was lower; however, further cooling (down to -20 degrees) induced another increase of permeability. The disruption of mitochondrial at negative temperatures after addition of 1.25 M NaCl to the incubation mixture caused a temperature-dependent release of the proteins into the supernatant. After ultracentrifugation of the membrane fragments at 140 000 g for 60 min the soluble proteins were detected in the samples coled down to -10 degrees. It was concluded that the changes in the state of mitochondrial membranes are due to the phase transitions of the inner membrane lipids.

Animals↗
PubMed1982

[Effects of cryoprotectors on the properties of the mitochondrial membrane surface as determined by distribution in biphasic aqueous systems].

The effects of various cryoprotectors, e. g. dimethylsulfoxide (Me2SO), glycerol, ethylene glycol and polyethylene oxide (PEO, m. w. 400) on the distribution of rat liver mitochondria in a biphasic polymeric PEO 4000-Dextrane 500 system were studied. The type of criss-cross distribution of cryoprotector-treated mitochondria suggests that the isoelectric point for the organelles is shifted towards the acidic values of pH. The effects of these agents decrease in the following order: Me2SO greater PEO-400 greater than glycerol greater than ethylene glycol. The alteration of the distribution coefficient for the mitochondria after their incubation in aqueous polymeric systems in the presence of cryoprotectors is also indicative of a decrease of their surface charge.

Animals↗
PubMed1982

[Factors of avian erythrocyte fusion: changes in the state of plasma membrane induced by dimethylsulfoxide and temperature].

Chicken erythrocytes cooled down to +2 degrees were incubated with 39% dimethysulfoxide (Me2SO) at 37 degrees, eventually resulting in a hemoglobin release. Incubation of erythrocytes with Me2SO at +2 degrees was also accompanied by hemoglobin release; the effect of Me2SO under these conditions was enhanced by Ca2+. Hypertonic concentrations of NaCl and sucrose suppressed this effect upon erythrocyte cooling. At the same time in the absence of Me2SO the level of cold hemolysis of erythrocytes increased as the tonicity of the medium rose. In this case low concentrations of Me2SO (8-15%) exerted a protective effect. The mechanisms of action of Me2SO and temperature on the structure of erythrocyte membrane are discussed.

Animals↗
PubMed1981

[Role of lysosome permeability disorders in the mechanism of the low-temperature inhibition of protein biosynthesis in the rat liver].

The effect of the supernatants of lysosomes subjected to a rapid or slow freezing and thawing on the protein-synthesizing activity of the rat liver postmitochondrial supernatant (S15) has been studied. It has been found that the addition of supernatants obtained after a slow freezing or thawing to a cell-free system results in a significant inhibition of 14C-leucine incorporation that is in a good agreement with their RNase activity. However, the RNase activity of lysosomal supernatants or Triton-lysate appears to be higher that the inhibitory effect on protein biosynthesis. The damaging effect of supernatants obtained after 2-hour storage at 2-4 degrees C of the frozen-thawed lysosomes has not virtually changed.

Animals↗
PubMed1980

[Structural-functional state of Ca-transport system of sarcoplasmic reticulum membranes after deep freezing].

The structure and functions of the Ca-transport system of sarcoplasmic reticulum (SR) at low temperatures (-5--196 degrees) were studied. It was shown that during SR freezing-thawing the activation energy of ATP enzymatic hydrolysis as well as the Ca-ATPase sensitivity to calcium ions were changed. The Km value for the carrier seemed to be unaffected thereby. Using the EPR method it was shown that after freezing down to -196 degrees and a subsequent thawing the protein-lipil interactions and the orderliness of phospholipid fatty acid chains in the SR membranes were altered. On the contrary, the activity of Ca-ATPase isolated from SR membranes remained unchanged, which is indicative of the enzyme resistance to the cold. The mechanisms responsible for the impairment of the functioning of Ca-transport system of SR membranes due to freezing are discussed.

Animals↗
PubMed1978

[Cryoresistance of rat liver endoplasmic reticulum membranes].

The effects of freezing of microsomes in liquid nitrogen and those of storage of microsomal suspensions at 2-4 degrees C and -3 - -5 degrees C for 24 hrs, on the enzymatic activities and hydrophobicity of membranes were studied. The hydrophobicity was determined by fluorescence of bound 1,8-anilino-naphthalene sulfonate. Rapid freezing of the microsomal suspension in liquid nitrogen followed by rapid warming did not change the hydrophobicity of the membranes, the rate of enzymatic lipid peroxidation, the level of cytochrome P-450 and the activity of NADH- and NADPH-cytochrome c reductase. A considerable decrease in the rate of enzymatic lipid peroxidation and membrane hydrophobicity was observed in the microsomes stored for 24 hrs at 2-4 degrees C. The 24-hr storage at -3 - -5 degrees C with subsequent thawing resulted in a rapid aggregation of the microsomes.

Adaptation, Physiological↗
PubMed1978

[Changes in activities of DNA-dependent RNA-polymerases from rat liver under influence of glycerol, dimethyl sulfoxide and polyethylene glycol-400].

Effects of glycerol, dimethyl sulfoxide (DMSO) and polyethylene glycol (PEG) 400 on transcription of isolated nuclei and DNA in rat liver under the action of homologous RNA-polymerases I and II were studied. Addition of these organic compounds to the reaction mixture before initiation altered RNA synthesis on native DNA matrix. Addition of glycerol or DMSO to the synthesising system 1 and 5 minutes after initiation of RNA synthesis had no effect on the rate of transcription. PEG-400 inhibited incorporation of 3H-UTP into newly-synthesized independently of the time of its introduction to the reaction mixture. The data obtained suggest that the compounds under study may impair the formation of initiation complex of RNA polymerase with DNA and alter RNA synthesis in isolated nuclei of rat liver.

Animals↗
PubMed1978

[Effect of freezing-thawing on the lipid composition of mitochondria].

The effect of near- and subzero temperatures on alterations in the lipid composition of albino rat liver mitochondrial membranes has been studied. Low temperature effect has been shown to intensify peroxide processes and to activate A2 phospholipase in mitochondrial membranes. This is followed by the decrease in lecithin, ethanolaminophosphatide, cardiolipin and cholesterol contents as well as by the accumulation of free fatty acids in the different temperature regions. The dependence of lipid mitochondrial membrane modification intensity on freezing and rewarming rates has been determined.

Animals↗
PubMed1976

[Halidor, 1-benzyl-1-(3'-dimethylaminopropoxy)-cyclohep tane fumarate as an uncoupler and inhibitor of the respiratory chain].

Halidor 1-benzyl-1-(3'-dimethylaminopropoxy)-cycloheptane fumarate, activates succinate oxidation in mitochondria and inhibits reverse electron transport from succinate to NAD+ in submitochondrial partides preparations at doses of 2-10(-5)--10(-3) M. At a dose of 5--7-10(-4) M halidor cause a swelling of mitochondria incubated in 0.1 M NH4NO3. At higher concentrations (10(-3)--10(-2) M) halidor practically completely inhibits NADH and succinate oxidase activity of mitochondria and submitochondrial particles. It is suggested that vasodilating effect of halidor is due to the uncoupling of oxidative phosphorylation, thus causing a deficiency of ATP for contracting function of blood vessel muscles.

Adenosine Triphosphate↗