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Biomedical subjects

V F Antonov

Publications and source records attributed to V F Antonov.

At least 19 recordsLinked to original sources
PubMed1999

[Sub-atrophic and atrophic pharyngitis as a manifestation of dystrophic pharyngeal mucosa in presenile, senile and long living persons].

The authors consider diagnostic, clinical and symptom characteristics of atrophic pharyngitis (AP) in presenile, senile and long-living persons and conclude that AP is age-specific dystrophic lesion of the pharynx. Diagnosis formulation by three degrees are suggested: pharyngeal dystrophy (PD) of degree I (only local symptoms cured after timely treatment), PD of degree II (local symptoms + neurotic condition which manifests with cancerophobia, persistent sensation of a foreign body), PD of degree III (persistent cancerophobia demanding psychotherapeutic treatment or psychiatric care).

Aged↗
PubMed1995

[Lipid pores and stability of cell membranes].

Electric studies have ascertained that transmembrane pores appear during the gel-liquid crystalline transition phase in the bilayer lipid membrane. The longevity of the pore depends on the phase state of lipids: in gel, the pores demonstrate long-term fluctuations, which can be eliminated by heating. The molecular model of a lipid pore has been proposed. The model predicts the formation of pores whose appearance is energetically favourable. The size of a cooperative unit and the area per lipid molecule head have been shown to be responsible for membrane stability. Proceeding from the model, a hypothesis has been forwarded that phase transition may be induced in the lipid bilayer at physiological temperatures. Electric techniques and differential scanning calorimetry have established that bivalent ions of Ca2+, Cd2+, Mg2+, Sr2+, and Ba2+ are able to induce phase transition of bilayer membranes from acid lipids at physiological temperatures to give rise to through pores. An analysis of the experimental findings indicates that pores having a less critical radius themselves adhere with time.

Calorimetry↗
PubMed1992

Stable cupola-shaped bilayer lipid membranes with mobile Plateau-Gibbs border: expansion-shrinkage of membrane due to thermal transitions.

Stable bilayer lipid membranes (BLM) with mobile Plateau-Gibbs border (PGB) have been formed. The precondition of the formation was the presence of a lipid coverage on the teflon surface near the hole, where the membrane has been formed. This allowed the movement of the PGB along the teflon surface after transformation of the planar bilayer into a cupola-shaped by bowing of the bilayer due to excess hydrostatic pressure. As a result the giant bilayers were obtained with an area up to two orders larger in magnitude compared with the initial area. Changes in lipid bilayer area depend on the temperature at the phase transition of the lipid. Cooling of the expanded bilayer was followed by a significant shrinkage of the bilayer at temperatures below the main phase transition.

Chemical Phenomena↗
PubMed1990

Electric field increases the phase transition temperature in the bilayer membrane of phosphatidic acid.

The effect of the electric field on the phase transition temperature (Tc) of acidic 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA) and 1,2-dipalmitoyl-sn-glycero-3-thionphosphate (thion-DPPA) and zwitterion, i.e. 1,2-dipalmitoyl-rac-3-phosphocholine and 1,2-distearoyl-rac-glycero-3-phosphocholine (DPPC and DSPC), lipids has been investigated. The phase transition was detected using the jump-like increase effect in the conductance of the planar bilayer membrane. A voltage increase to 150 mV has been shown to increase the phase transition temperature in a bilayer lipid membrane (BLM) of phosphatidic acids (DPPA and thion-DPPA) by 8-12 degrees C while the transition temperature in the bilayer of zwitterion lipids (DPPC and DSPC) increases insignificantly. The increasing of Tt in BLM of acidic lipids is attributed to the voltage-induced changes in the molecule packing density.

Chemical Phenomena↗
PubMed1986

Permeability of bilayer lipid membranes in phase transition. The significance of intermolecular phosphate-phosphate hydrogen bonding.

The effect of pH on the phase transition temperature of 1,2-dipalmitoyl-sn-glycero-3-phosphate (DPPA) and 1,2-dipalmitoyl-sn-glycero-3-thionphosphate (thion-DPPA) has been investigated. The phase transition was detected using the jump like increase effect in the conductance of the planar bilayer membrane. It is shown that the steepness of pH-dependence of the phase transition temperature differs for these two kinds of lipids in the pH range of 3.5-8. This result is explained in terms of decreased intermolecular hydrogen bonding between the head groups of thion-DPPA. Calculations taking into account the ability of DPPA molecules to intermolecular phosphate-phosphate hydrogen bonding were made. The results of calculations are in good agreement with the experimental data obtained in this study.

Hydrogen Bonding↗
PubMed1985

Capacitive and ionic currents in BLM from phosphatidic acid in Ca2+-induced phase transition.

The development of electric current with time in a bilayer lipid membrane (BLM) formed from dipalmitoylphosphatidic acid on introducing Ca2+ ions into the medium was studied at constant temperature and pH. The phase transition in the Ca2+-induced BLM is accompanied by the initial capacitive current followed by the occurrence of single ionic channels. The amount of transported charges in the capacitive current is 5 C/ microF. The conductivity of the single ionic channels ranges from 50 to 100 pSm.

Calcium↗
PubMed1983

[Evaluation of ion activity in determining time of death].

Activity of potassium ions was examined in 3 liquid media of 54 rabbit cadavers by potentiometry with the use of a potassium-selective valinomycin electrode. The reported and obtained data were used for the development of the diagnostic regression equations and the curves to define the time of death from the activity of a complex of 3 ions (potassium, sodium and hydrogen) in the blood serum, CSF and vitreous body fluid. The method is offered for appropriate trials in human cadavers.

Animals↗
PubMed1982

[Characteristics of membrane activity of triterpene glycosides].

The membrane activity of 6 triterpenic glycosides was studied with respect to ionic permeability of the liposomes and flat bilayer lipid membranes. It was shown that the rate of the glycoside effect depended on both the sterol level in the membrane and the sterol type (cholesterol, ergosterol). The activity of cauloside C, a plant glycoside markedly depended on pH of the medium. The carbohydrate chain played an important role in the membrane activity of the glycosides. Correlation in the effect of triterpenic glycosides on the model lipid and cell membranes was noted.

Cell Membrane↗
PubMed1980

The appearance of single-ion channels in unmodified lipid bilayer membranes at the phase transition temperature.

Ion-specific channels in artificial membranes have been formed by the addition of gramicidin A, alamethicin, polyene antibiotics and some proteins to the solution surrounding the bilayer lipid membrane. Until now there have been no reports of single-ion channels in unmodified lipid membranes. We have now studied the electrical conductance of planar lipid bilayers membranes made of synthetic distearoylphosphorylcholine (DSPC). Current fluctuations of amplitude approximately 1pA and duration approximately 1 s have been discovered at phase transition temperature, which shows that the appearance of ionic channels may be the result of lipid domain interactions. This would explain the dramatic increase in ion permeability observed in liposomes during phase transition. We suggest that these channels could conduct the transmembrane ionic current in biological membranes without the involvement of peptides and proteins.

Electric Conductivity↗
PubMed1980

[Effect of the polycationic antibiotic polymyxin B on the respiratory activity of rat liver mitochondria].

the mechanism of the effect of the peptide antibiotic polymixin B on respiration of rat liver mitochondria was studied. It was shown that polymixin B at concentrations of (1,6--2,0) . 10(-3) M inhibits mitochondrial respiration in state 3 and 3u irrespective of the oxidation substrate used and activates oxygen consumption in state 4 at lower concentrations. It is assumed that the antibiotic affects mitochondrial respiration by changing the ionic permeability of the membranes.

Animals↗