[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.

[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.

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.

[Conductivity of bilayer lipid membranes in phase transition: the role of intramolecular phosphate-phosphate hydrogen bonds].

pH effect on phase transition measured by jump of conductance in the BLM formed from DPPA and thio-DPPA was studied. The difference of pH dependence for these two lipids was shown. The corresponding calculation discovered significance of intermolecular phosphate-phosphate hydrogen bonds in induced conductance of BLM.

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.

[Ca2+ ions induce successive capacity and ion currents in BLM from phosphatidic acid as a result of phase transition].

Time dependence of Ca2+-induced electric current in BLM formed from DPPA was studied at constant temperature and pH. The phase transition in BLM is accompanied by capacity current and following appearance of single ionic channels. It was shown that transferred charge was 5 nC/F, conductivity of single ionic channels--500-100 pSm.

[Modification of the electric characteristics of bilayer lipid membranes by intramitochondrial thyroid hormone receptors].

Electric conductivity of flat bilayer lecithin membranes (BLM) which was initially equal to 10(-8) Sm/cm2 increased about 10-fold after addition to the medium of proteins isolated from rat liver mitochondria, characterized by high affinity for thyroid hormones (the association constant for 125I-thyroxine = 3.5 10(8)M-1). In that case there was an increase in electric stability of the BLM as judged from an over 2-fold increase in the potential of electric breakdown of such membranes as compared with unmodified BLM.

[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.