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O A Nardid

Publications and source records attributed to O A Nardid.

11 recordsLinked to original sources
PubMed2005

[Examination of low temperature effect on cord blood serum by microwave dielectric method].

The influence of the freezing velocities and final temperatures of storage on the complex dielectric permittivity of cord blood serum have been studied. On the temperature dependences of the dielectric permittivity the non-monotonous changes at the characteristic temperatures accompanying with the change of the activation energy of the water molecules dielectric relaxation were found out. The drastic deflection of the temperature dependence of ?' from the monotone curve at 15 degrees C region correlates with the fracture of Arrhenius plots of the dielectric relaxation time and viscosity at the same temperature. Slow freezing (1-2 degrees C/min) of cord blood serum results in ?' diminution in comparison with control, that testifies an increase of bound water amount because of loosening in this case the surface of biomacromolecule polypeptide chains. Rapid freezing (300-400 degrees C/min) results in ?' increase of serum, that is caused, apparently, by the cryoaggregation of biomacro-molecules, which can thus happen.

Biophysical Phenomena↗
PubMed2004

Temperature-dependent changes in erythrocytes' cytosol state during natural and artificial hypobiosis.

At present, the question of how the structural state of the erythrocyte cytosol is arranged to maintain essential permeabilities successfully both at normal temperature and during periods with a significant body temperature reduction during hypobiosis remains unanswered. In the present work, we performed comparative investigations of temperature-dependent changes in the cytosol state of erythrocytes from animals subjected to natural (winter hibernating ground squirrels) or artificial hypobiosis. The cytosol state was evaluated by the ESR method of spin probes (TEMPON) within the temperature range of 0-50 degrees C. Erythrocyte resistance to acid hemolysis, which is limited by the permeability of membranes for protons and the state of the anion channel, were determined using the method described by Terskov and Getelson [Biofizika 2 (1957) 259]. A change in cytosol microviscosity of erythrocytes was found as well as a temperature-dependent increase in acid resistance of erythrocytes. Our investigations allow us to conclude that physiological changes occurring in a mammalian organism during natural and artificial hypobiosis are accompanied by structural modifications of the erythrocyte cytosol. The temperature range where these modifications are observed (8, 15, 40 degrees C) suggests that the most probable modifying link is spectrin and/or the sites of its interaction with membrane. The interaction of cytoskeletal components with the cell membrane plays a key role in regulation of membrane permeability, suggesting an important role of this interaction in the adaptive reactions of erythrocytes.

Animals↗
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↗
PubMedDate not supplied

[Study of erythrocyte dehydration using spin labels].

Possibility of studying erythrocyte dehydration by ESR-spin probe is substantiated. Dehydration of erythrocytes in relation to osmolarity of sodium chloride solutions is investigated. The results are shown to agree with the data obtained by radioisotope method.

Body Fluids↗
PubMedDate not supplied

[Effect of the permeability of lysosomal and mitochondrial membranes on the ability of their cryoextracts to inhibit the protein-synthesizing activity of cell-free systems].

Changes in permeability of lysosomal and mitochondrial membranes were studied under different temperatures at which cryoextracts from organelles inhibit most distinctly the protein synthesizing activity of the cell-free system from the rat liver. It is found that mitochondria are more sensitive to the effect of low temperature effect than lysosomes. Overcooling of the mitochondria suspension to the temperature of the free water crystallization is shown to cause no release of the protein synthesis inhibitor. The inhibitor release from organelles occurs from the moment of crystallization and reaches its maximum at the eutectic temperatures of the freezing medium which is due to the injury effect of the complex of physicochemical factors on the membrane structures, occurring during the phase transition of the solvent.

Animals↗
PubMedDate not supplied

[Study of the state of mitochondria at low temperatures by the ESR method].

Possible usage of ESR probe method for studying low temperature effect on structural and functional state of mitochondria is under study. It is shown that during freezing out of mitochondrial water there is sharp dehydration of intermitochondrial matrix and membrane thickening. The facts are given about damage of barrier function of the membrane at the moment of appearance of extramitochondrial liquid phase during thawing.

Animals↗
PubMedDate not supplied

[The effect of temperature and concentrations of various substances on the microviscosity of erythrocyte cytosol].

EPR spin-probe method was used to investigate the dependence of erythrocyte cytosol microviscosity (ECM) on the concentration of different substances and temperature. The critical ECM value has been determined after reaching of which erythrocytes become destroyed. It is shown that this ECM value is reached at different NaCl concentrations depending on the temperature.

Cytosol↗
PubMedDate not supplied

[Study of the effect of low temperatures and organic solvents on the structure of model membranes using fluorescent probes].

By means of the fluorescence probes pyrene, DSP-12 and n-terphenyl the effect of low temperature, glycerol and 1,2-propylene glycol on the structure of lecithin liposomes and proteoliposomes formed by lecithin and cytochrome P-450 has been studied. Freezing-thawing and cryoprotectants were shown to modify surface area and internal volume of the lipid bilayer.

Cold Temperature↗
PubMedDate not supplied

[Erythrocyte membrane permeability of Citellus undulatus during hibernation].

We have studied the influence of the erythrocyte hypothermic storage of long-tailed ground squirrels at various physiological states and white mongrel rats on the impairment of the barrier function of their membranes for ferricyanide. The membranes of sleeping and awakening ground squirrels demonstrate the highest stability (the structural integrity is sustained for 3-3,5 months), meanwhile rat blood erythrocytes maintain the barrier function only for 2 weeks. Beside structural and viscous changes in the erythrocyte membrane and the cytosol of hibernating ground squirrel an important role in maintaining barrier function under conditions of hypothermic storage is played by the content of animal blood plasma. Appearance of a non-typical EPR spin probe spectrum in some ground squirrel blood samples in non-equilibrium state of entering or arousing from hibernation has been observed.

Animals↗