The influence of several surface-active substances on neuromuscular transmission of excitation]

Microelectrode method was applied to the study of the influence of sodium bile salts (BS), saponin and between-80 on the end-plate potentials (EPP) of m. sartorius of Rana ridibunda. Bile salts in a concentration of 10(-5) g/ml did not change these potentials significantly. With increase of the BS concentration up to 10(-4) g/ml the amplitude of EPP increased 1.5- 3 times. The action of these substances in a concentration up to 10(-3) g/ml caused similar, but more rapid, increase in the EPP amplitude, and then the amplitude decreased. Saponin and tween-80 were less efffective in their action on EPP, but evoked muscle contraction. It is suggested that an increase in the EPP amplitude as a result of the action of the mentioned agents was chiefly connected with stimulation of the acetylcholine release by the nerve terminals.     

An evaluation of the genotoxicity of nonionogenic surface-active substances]

The mutagenic activity of 16 industrial nonionic surfactant samples has been investigated in Ames-test without metabolic activation and with the use of mouse liver microsomal fraction in vitro. The genotoxical estimation of their possible biodegradation products is given. The mutagenicity of a number of high molecular polyethylene glycoles related to nonionic surfactants is shown.     

Increase in tetracycline activity by using surface-active substances]

The antimicrobial effect of cationic and anionic surface-active substances, i.e. catamine AB and sulphonol NP-3 respectively was studied in vitro with respect to gramnegative bacteria. In non-bactericidal concentrations catamine AB significantly increased the efficacy of tetracyclines, while the anionic compound had no such effect. The increase in the tetracycline activity was due to the antibiotic increased absorption (14C-oxytetracycline as an example) on the treatment of gramnegative bacteria with catamine AB and staphylococci with catamine AB and sulphonol NP-3, which was mainly associated with impairement of the cell membrane permeability by the surface-active substances.     

Effect of inhalation of surface-active substances on the surfactant system of the lung]

Surface activity, biochemical composition and morphology of the rat lungs were studied in norm, under effect of acute hypoxia and after infusion of obsidan (1 mg/100g). The data permit suggesting that under the influence of obsidan and hypoxia a stability index of surfactants and quantity of phospholipids decreased, while the quantity of lysophosphatidylcholine and lysophosphatidylethanolamine increased. Morphology studies show that after hypoxia and obsidan infusion oedema and cell destruction developed in the lung. The inhalation of exogenous surfactant increased stability index and quantity of phospholipids, decreased the quantity of lysophospholipids but did not eliminate morphological disorders in the lung induced by hypoxia and obsidan infusion.     

Effect of lactic bacteria metabolic products on the transmission of R-plasmids in enterobacteria in vitro]

The authors present data on the study of lactobacteria used in the production of dry lactobacterin (lactobacterinum siccum). Metabolic products (lactocidin) were extracted with lactic and acetic acid after Vincent et al. Two donor strains (E. coli K12 J5-3 R1-19 and E. coli K12 W1845 R26) were crossed in the conjugation process in various conbinations with six recipient strains (E. coli K12S, E. coli Su 3912/41, Sh. sonnei 263B, Sh. sonnel 3470, S. heidelberg, A161, and S. typhimurium SH3 his-). The frequency of R-plasmide transmission in enterobacteria was decreased in vitro under the effect of L. plantarum 8R-A3 and L. fermentum 90T-S4 metabolites.     

Antigenic properties of genetic recombinants of serologically typed E. coli]

The conjugation between the typed strains of E. coli belonging to various serological groups and conjugation between typed and untyped E. coli strains were studied. Genetic determinant controlling the synthesis of the O100 antigen proved to be closely linked with histidine locus. Among recombinants obtained in crossing the typed E. coli strains there were such belonging to the serological type different from the serological types of donor and recipient cells.     

alpha-Hemolysin of E. coli]

The activity of alpha-hemolysin increased at the log growth phase in the culture of E. coli P678 Hly+ hemolytic strain; this activity diminished with the change into the stationary phase, and then fell sharply. Replacement of the culture medium in the stationary growth phase by fresh one led to restoration of the hemolytic activity of the culture. The culture fluid separated from the cells at the stationary growth phase produced an inhibitory action on the alpha-hemolysin Ca ions activated and stabilized the alpha-hemolysin. Sodium citrate and sucrose served as hemolysis inhibitors. The action of alpha-hemolysin was maximal against human erythrocytes at pH 6.5. Hemolytic activity was characterized in time by a distinct lag-phase and the phase of the greatest rate of reaction. The duration of the lag-phase and also the rate of hemolysis depended on the concentration of alpha-hemolysin (with the increase of the hemolysin concentration lag-phase was shortened and the reaction was accelerated). There proved to be a linear relationship between the amount of erythrocytes taken into the reaction and the rate of hemoglobin release, and also there was noted a temperature activation of the hemolytic reaction.     

Action of surface-active substances of biological membranes. III. Comparison of hemolytic activity of ionic and nonionic surfactants

The hemolytic action of a number of homologous series of cationic surfactants on human erythrocytes was measured. The hemolytic effects of anionic, nonionic and cationic surface-active agents are compared. The relationship which exists between the key physicochemical properties of surfactants (critical micelle concentration, hydrophile-lipophile balance) and their hemolytic capacities is discussed. The parameters required to compare the actions of various surfactants on different cellular membranes are considered in relation to the study of the correlation between the surfactant lytic effects and the features of the membrane molecular organization.