Search PubMed⌕ Search

Biomedical subjects

E T Kozhomkulov

Publications and source records attributed to E T Kozhomkulov.

7 recordsLinked to original sources
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↗
PubMedDate not supplied

[Polymyxin B and Ca(2+) induce conductance fluctuations in the dipalmitoyl phosphatidic acid bilayer lipid membrane].

Polymyxin B in micromolar concentrations induces current fluctuations in liquid crystalline bilayer lipid membranes from dipalmitoylphosphatidic acid identified as ion channels. The appearance of ion channels correlates with phase separation of the lipid in the presence of peptide polycations detected by differential scanning calorimetry. Ca2+ also induces the formation of ion channels in liquid crystalline bilayer lipid membranes from dipalmitoylphosphatidic acid followed by the phase transition of the phospholipid. The capacitive current, which indicates the possibility of structural transformations of bilayer-non-bilayer type (hexagonal phase II), precedes the formation of Ca(2+)-induced channels in bilayer lipid membranes from dipalmitoylphosphatidic acid.

Calcium↗
PubMedDate not supplied

[Experimental hepatitis E infection in piglets].

A sample of patient's faeces containing virus-like particles (VLP) of 27-34 nm was obtained during an outbreak of hepatitis E in the Kirghiz SSR. The identity of the VLP to hepatitis E virus and etiological association with the disease were demonstrated by immune electron microscopy and infection of Macaca fascicularis monkeys. This isolate of hepatitis E virus is able to induce experimental infection in domestic piglets which was very similar to experimental hepatitis E in primates when infected orally, intravenously and by the combined routes. The clinical manifestations included acute biochemical and histological hepatitis, excretion of hepatitis E virus in faeces, icteric sclerae and skin, hepatitis virus presence in the material from mesenteric lymph nodes. Immunosuppression aggravated hepatitis E infection in piglets. Piglet-to-piglet transmission of hepatitis E virus was demonstrated. During passages of the virus in piglets a shortening of the incubation period and the absence of jaundice was observed.

Animals↗
PubMedDate not supplied

[Conductivity of bilayer lipid membranes of phosphatidic acid at phase transitions, induced by temperature and pH].

Conductivity of bilayer lipid membranes formed from synthetic phosphatic acid and its thioanalogs was studied. Conductivity of bilayer lipid membranes was shown to change spasmodically in the phase transition region. The temperature of conductivity jump decreased with pH shift from acid to alkaline region. The amplitude of conductivity jump attained 1.5-2 orders. The jump can be also obtained at constant temperature by changing the medium pH. The observed conductivity jumps are suggested to determine the phenomena of thermo- and chemoreception in biological membranes.

Electric Conductivity↗