Changes in Surface Charge Density of Blood Cells in Fatal Accidental Hypothermia.

The objective of this research was to evaluate postmortem changes concerning electric charge of human erythrocytes and thrombocytes in fatal accidental hypothermia. The surface charge density values were determined on the basis of the electrophoretic mobility measurements of the cells conducted at various pH values of electrolyte solution. The surface charge of erythrocyte membranes after fatal accidental hypothermia increased compared to the control group within whole range of experimental pH values.

Phosphatidylcholine-fatty Alcohols Equilibria in Monolayers at the Air/Water Interface.

Monolayers of phosphatidylcholine (PC), tetradecanol (TD), hexadecanol (HD), octadecanol (OD) and eicosanol (E) and their binary mixtures were investigated at the air/water interface. The surface tension values of pure and mixed monolayers were used to calculate π-A isotherms. The surface tension measurements were carried out at 22 °C using a Teflon trough and a Nima 9000 tensiometer.

The effect of pH on the electrical capacitance of phosphatidylcholine-phosphatidylserine system in bilayer lipid membrane.

This paper reports measurements on the pH dependence of the electrical capacitance of lipid membranes formed by 1:1 phosphatidylcholine-phosphatidylserine mixtures. A theoretical model was developed to describe this dependence, in which the contributions of functional groups (as the active centers of adsorption of the hydrogen and hydroxide ions) to the overall membrane capacitance were assumed to be additive. The proposed model was verified experimentally using electrochemical impedance spectroscopy.

Electrochemical impedance spectroscopy as a method for electrical characterization of the bilayers formed from lipid-amino acid systems.

Bilayer lipid membranes composed of phosphatidylcholine and isoleucine or phosphatidylcholine and tyrosine were investigated using electrochemical impedance spectroscopy. Interaction between membrane components causes significant deviations from the additivity rule which can be explained by formation of the domain structures. The surface area of domains was calculated based on derived equations.

Pore formation in lipid bilayer membranes made of phosphatidylcholine and cholesterol followed by means of constant current.

This paper describes the application of chronopotentiometry to lipid bilayer research. The experiments were performed on bilayer lipid membranes composed of phosphatidylcholine and cholesterol and formed using the painting technique. Chronopotentiometric (U = f(t)) measurements were used to determine the membrane capacitance, resistance, and breakdown voltage as well as pore conductance and diameter.

The influence of pH on phosphatidylethanolamine monolayer at the air/aqueous solution interface.

The dependence of the interfacial tension of a phosphatidylethanolamine (PE) monolayer on the pH of the aqueous solution has been studied. A theoretical equation is derived to describe this dependence. A simple model of the influence of pH on the phosphatidylethanolamine monolayer at the air/hydrophobic chains of PE is presented.

Influence of pH on sphingomyelin monolayer at air/aqueous solution interface.

The pH dependence of the interfacial tension is an important factor in the behavior of sphingomyelin (SM) monolayers. We developed a theoretical model to describe this dependence in which the interfacial tension and molecular area contributions of each sphingomyelin form were additive and dependent on pH. The interfacial tension values and the molecular areas values for the SMH(+) and SMOH(-) forms of sphingomyelin were calculated and the proposed model was experimentally verified.

The equilibria of sphingolipid-cholesterol and sphingolipid-sphingolipid in monolayers at the air-water interface.

Monolayers of sphingomyelin (SM), ceramide (Cer) and cholesterol (Ch) and binary mixtures SM-Ch, SM-Cer and Cer-Ch were investigated at the air-water interface. SM, Cer and Ch were used in the experiment. The surface tension values of pure and mixed monolayers were used to calculate π-A isotherms.

Chronopotentiometric studies of phosphatidylcholine bilayers modified by ergosterol.

We have monitored the effect of ergosterol on electrical capacitance and electrical resistance of the phosphatidylcholine bilayer membranes using chronopotentiometry method. The chronopotentiometric characteristic of the bilayers depends on constant-current flow through the membranes. For low current values, no electroporation takes place and the membrane voltage rises exponentially to a constant value described by the Ohm's law.

Impedance analysis of complex formation equilibria in phosphatidylcholine bilayers containing decanoic acid or decylamine.

Bilayer lipid membranes composed of phosphatidylcholine and decanoic acid or phosphatidylcholine and decylamine were investigated using electrochemical impedance spectroscopy. Interaction between membrane components causes significant deviations from the additivity rule. Area, capacitance, and stability constant values for the complexes were calculated based on the model assuming 1:1 stoichiometry, and the model was validated by comparison of these values to experimental results.

Chronopotentiometric technique as a method for electrical characterization of bilayer lipid membranes.

The basic electrical parameters of bilayer lipid membranes are capacitance and resistance. This article describes the application of chronopotentiometry to the research of lipid bilayers. Membranes were made from egg yolk phosphatidylcholine.

pH Effect of the sphingomyelin membrane interfacial tension.

The effect of pH on the interfacial tension of a sphingomyelin membrane in aqueous solution has been studied. Three models describing H(+) and OH(-) ion adsorption on the bilayer lipid surface are presented. In models I and II, the membrane surface is continuous, with uniformly distributed functional groups as centers of H(+) and OH(-) ion adsorption.

Effect of monovalent ion adsorption on the electric charge of phosphatidylcholine - decylamine liposomal membranes.

We examined the effect of adsorbed monovalent ions on the surface charge of phosphatidylcholine (PC) - decylamine (DA) liposomal membranes. Surface charge density values were determined from electrophoretic mobility measurements of lipid vesicles performed at various pH levels. The interaction between solution ions and the PC-DA liposomal surface was described by a six component equilibrium model.

Impedance spectroscopic investigation of the bilayer lipid membranes formed from the phosphatidylserine-ceramide mixture.

Electrochemical impedance spectroscopy was used for the study of two-component lipid membranes. Phosphatidylserine and ceramide were to be investigated because they play an important biochemical role in cell membranes. The research on biolipid interaction was focused on a quantitative description of processes that take part in a bilayer.

Physicochemical analysis of phosphatidylcholine-ceramide system in bilayer lipid membranes.

Electrochemical impedance spectroscopy was used for the study of two-component lipid membranes. Phosphatidylcholine and ceramide were to be investigated, since they play an important biochemical role in cell membranes. The research on biolipid interaction was focused on quantitative description of processes that take part in a bilayer.

Adsorption equilibria at interface separating electrolyte solution and phosphatidylcholine-stearylamine liposome membrane.

The effect of the pH of an electrolyte solution on the electric surface charge of the liposome membrane was studied. The membrane of vesicles contained egg phosphatidylcholine (PC) with different proportions of stearylamine (ST). The surface charge density of the membrane was determined as a function of pH from electrophoretic mobility measurements.

Altered membrane free unsaturated fatty acid composition in human colorectal cancer tissue.

Polyunsaturated free fatty acids (PUFAs) participate in normal functioning of the cell, particularly in control intracellular cell signalling. As nutritional components they compose a human diet with an indirect promoting influence on tumourogenesis. The PUFAs level depends on the functional state of the membrane.

Changes in electric charge and phospholipids composition in erythrocyte membrane of ethanol--poisoned rats after administration of teas.

Erythrocyte membrane components and electric charge can be modified by ethanol and by compounds formed as a result of its metabolism, particularly be reactive oxygen species (ROS). The effects of ROS can be neutralized by administering preparations with antioxidant properties. The natural preparations of this kind are teas.