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Currently, the major problem in the genetic transformation is to understand how such a large molecule as the plasmid DNA passes through the cell membrane. To solve this problem we used a simplified experimental model with Escherichia coli and the plasmid pBR322: the DNA-bacteria mixture was electroporated in a sucrose solution at 0 degree C and at fixed(More)
Electric field pulses used for cell manipulation can cause irreversible cell damage. The mechanisms of the processes leading to such cell damage are very complicated. Our work demonstrated that exponential electric pulses with intensity of 2-7.5 kV/cm and duration of 5.2 ms were able to initiate peroxidation of fatty acid emulsions, liposomal membranes, red(More)
The effect of integrin receptors on the level and transmembrane localization of cholesterol molecules was investigated in beta1 integrin-expressing (beta1) and beta1 integrin-deficient (beta1 null) cells. We found that the content of specific raft components-cholesterol, sphingomyelin, and caveolin-was increased in integrin-expressing cells. Integrin(More)
Investigations were carried out on the effect of plasma membrane lipid modifications on the fusogenic capacity of control and ras-transformed fibroblasts. The plasma membrane lipid composition was modified by treatment of cells with exogenous phospholipases C and D, sphingomyelinase and cyclodextrin. The used enzymes hydrolyzed definite membrane lipids thus(More)
Viscoelastic characteristics (VEC) of old rat aorta (Wistar, 10 months) were obtained by sinusoidal excitation of intraluminal pressure (p) in cylindrical arterial preparations. The pressure excitation frequency (f(exc)) was swept in the range 3-30 Hz up and down at several mean-pressure levels while response volume oscillations were recorded and resonance(More)
A simple and rapid nonenzymatic method for radioiodination of phospholipids is described. It involves oxidation of Na125I with TlCl3 (or chloramine-T) in an aqueous medium, with subsequent exposure of the phospholipids, dissolved in chloroform/methanol, to the action of the oxidizing mixture. Purification of the radiolabelled phospholipids was effected by(More)
Reassociation of typical single-copy DNAs, like E. coli DNA, even when performed at relatively low temperatures, results in the formation of perfect duplexes with thermal stability very close to that of the native DNA. In contrast, duplexes of mouse repeated DNA as well as duplexes of Streptomyces DNA prepared under the same conditions, show a low thermal(More)
Sixteen antacids were characterized as well as the milk as regards the acid-bounding properties. The study was carried out via the automatic pH-meter titrigraph (Radiometer--Copenhagen). Quantitative data on the acid-bounding capacity were obtained, as well as on the buffer properties and the duration of the interaction between the drugs studied with the(More)
The need for a quantitative evaluation of the immunologic activity of rabies vaccines led to the carrying out of comparative investigations of various methods for controlling their immunogenicity. Three methods were tested: the Bulgarian method with the use of rabbits, which did not make it possible to evaluate the amount of immunogenic power; the Soviet(More)