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Biomedical subjects

A N Polin

Publications and source records attributed to A N Polin.

At least 19 recordsLinked to original sources
PubMed1992

[Antimicrobial and membranolytic activities of anti-burn drug fenozan].

Fenozan, an anti-burn preparation, was shown to have antimicrobial activity against freshly isolated clinical strains of Staphylococcus aureus and Streptococcus faecalis, as well as against collection strains of the other gram-positive bacteria. The antimicrobial action of the preparation was possibly due to impairment of permeability of the cytoplasmic membranes in the sensitive bacterial cells and their liberation of intracellular low molecular weight compounds to the environment. The membranolytic and minimum inhibitory concentrations of fenozan with respect to the sensitive bacterial cells were one order of magnitude lower than the concentration stabilizing the membranes of animal cells in the treatment of burns. Combination of the antioxidant and antimicrobial properties in fenozan was likely to provide its satisfactory therapeutic effect in the treatment of burn wounds.

Bacillus↗
PubMed1990

[Antimicrobial and hemolytic activities of gradex].

Gradex is a polymer preparation resulting from formation of covalent bonds between the molecules of gramicidin S, a polypeptide antibiotic, and dextran, a polymeric carrier. Antimicrobial and hemolytic activities of gradex were studied. It was shown that the antimicrobial activity of gradex was due to the presence of gramicidin S in its composition. The activity level was lower than that of gramicidin S. It was also found that the gradex reduced form in concentrations up to 300 micrograms/ml had practically no hemolytic effect against human erythrocytes. The reduced form of gradex is promising for development of an artificial ++anti-brucellosis vaccine.

Bacillus↗
PubMed1989

[Study of the adaptation resistance in bacteria to membrane active polypeptide antibiotics].

Variants of Micrococcus lysodeikticus resistant to 100 micrograms/ml of gramicidin S with preserved resistance in subcultures on media without the antibiotic were isolated as a result of prolonged adaptation on a solid medium with increasing concentrations of gramicidin. The sensitive and resistant cells did not differ by their ability to bind gramicidin. Under the antibiotic effect permeability of the cytoplasmic membranes of the intact cells in the sensitive bacteria appeared to be impaired to a greater extent than that of the membranes of the cells in the resistant variant. Comparison of the lytic activity of gramicidin and its derivatives with respect to the protoplasts prepared with the cells of the initial and resistant variants of M. lysodeikticus revealed much higher resistance of the resistant variant protoplasts to the membrane-disorganizing effect of the preparations. Malate dehydrogenase and NADH-oxidase in the membrane preparations of the resistant variant cells differed from analogous enzymes from the membranes of the initial strain by the levels of their activity and sensitivity to gramicidin. It is likely that during adaptation of M. lysodeikticus to gramicidin significant changes in the cell cytoplasmic membranes occurred.

Adaptation, Physiological↗
PubMed1989

[Bacteriolytic enzymes produced by actinomycetes. II. Biosynthesis and areas of practical application].

The data on physiological conditions of the bacteriolytic enzyme formulation of actinomycetes, the population structure of producing cultures, the search of producers of enzymes able to hydrolyze the peptidoglycan of cellular walls of bacteria are reviewed. The fields of application of lytic enzymes in fundamental and applied microbiological investigations are pointed out. These enzymes are of considerable interest as potentially useful chemotherapeutics and food preservatives. They may be successfully used in biochemical and genetic investigation, in the study of peptidoglycan structure. The ability of bacteriolytic enzymes to cause the lysis of microorganisms resistant to the lysozyme action is of special importance. The application of these enzymes allows to work out gentle methods of lysis of bacterial cells used in various fields of microbiology.

Actinomycetales↗
PubMed1988

[The action of gramicidin S on the ionic permeability of bilayer lipid membranes].

The effect of cyclic decapeptide of gramicidin S on electrical conductivity of bilayer lipid membranes has been studied. The integral conductivity of bilayer has been shown to increase with the growth of antibiotic concentration. The integral conductivity increase occurs as series of conductivity discrete leaps, differing in amplitude from fluctuations of conductivity caused by linear gramicidins. In the series of selectivity of bilayer membranes for cations of alkaline metals the rubidium ion is before the cesium ion. This is the only difference between this series and the series of relative ionic mobility series of cations of alkaline metals in water solutions.

Cell Membrane Permeability↗
PubMed1988

[Effect of salts on the lytic activity of gramicidin S and its derivatives].

Potassium and sodium chlorides, sulfates, acetates and phosphates activated the lytic action of gramicidin S and its derivatives on protoplasts of M. lysodeikticus. The derivatives used were positively charged and neutral by the free amino groups in the ornithine moieties. The salts had no effect on lysis of the bacillar protoplasts by gramicidin S and its positively charged derivatives. The lytic effect of the neutral derivative on the bacillar protoplasts markedly increased in the presence of the salts, activation of the lysis by the phosphates being more pronounced than that by the other salts. Increased membrane activity of gramicidin S in the presence of the salts was not connected with association of the substance molecules in solution. Probably it was due to increased destruction of the membranes at the account of activated detergent effect of the antibiotic and its derivatives.

Bacillus subtilis↗
PubMed1988

[Bacteriolytic enzymes produced by actinomycetes. I. The physicochemical properties of the enzymes and the spectrum of their lytic action].

This review is devoted to the bacteriolytic enzymes produced by many actinomycetes, mainly by Streptomyces genus. The bacteriolytic enzymes hydrolyse the specific bonds in bacterial peptidoglycans and cause the solubilization of the cellular walls and the disintegration of the bacterial cells. Many of the enzymes are purified to the electrophoretic homogeneity. The actinomycetes form the endo-N-acetylmuramidases more often, then the endopeptidases follow according to the frequency of occurrence, while the amidases and endo-N-acetylglucosaminidases are met rather seldom among the streptomycete-producers. The known amidases and exo-enzymes which are also produced by some species of actinomycetes are not related to the lytic enzymes proper. Almost all known endopeptidases from streptomyces hydrolyse the bridge peptide bonds in which the carboxyl group of terminal D-alanyl of peptide chain is involved. The bacteriolytic spectra of the different muramidases differ from each other and essentially differ from the spectrum of the egg-white lysozyme. Some endomuramidases from streptomyces are able to hydrolyse streptococci and some other important from the practical point of view microorganisms resistant to the action of lysozyme.

Actinomycetales↗
PubMed1988

[Use of the method of protoplast fusion in the selection of a nisin producer].

Experimental data on selection of Streptococcus lactis producing the polypeptide antibiotic nisin with the method of protoplast fusing, one of the modern methods of cell engineering are presented. Four strains of Streptococcus lactis differing in their nisin-producing levels and difficult for protoplasting were used in the study. It was shown possible to transfer them to the protoplast form when respective conditions for their preliminary cultivation and regeneration are provided. Distinctive features of these strains with respect to the antibiotic resistance, sugar fermentation and growth component requirements were revealed. The protoplast fusing yielded hybrids differing from the parent strains by a number of phenotypical features and nisin-synthesizing activity.

Genetic Engineering↗
PubMed1988

[Effect of L-arabinose and sucrose on the biosynthesis of heliomycin by its producer Streptomyces olivocinereus 11-98].

When Streptomyces olivocinereus 11-98 MFU was grown in media containing L-arabinose or sucrose there was observed a converse relation between the culture growth and heliomycin biosynthesis. In media with two carbon sources: L-arabinose and glycerol or sucrose and glycerol at first L-arabinose or sucrose was consumed while the level of glycerol consumption remained low as compared to the control. After exhaustion of the first carbon source there was observed increased consumption of the second one i.e. glycerol. While the medium contained L-arabinose or sucrose the culture growth was mainly provided by these carbon sources and biosynthesis of heliomycin was inhibited. The culture started biosynthesis of heliomycin when L-arabinose or sucrose in the medium was exhausted. Probably control of heliomycin biosynthesis by L-arabinose or sucrose is achieved by catabolic type carbon regulation known as the general mechanism regulating biosynthesis of various antibiotics.

Anti-Bacterial Agents↗
PubMed1988

[Kinetic aspects of the relation of the growth of the producer and the biosynthesis of heliomycin depending on the carbon source in the medium].

Kinetic parameters of Streptomyces olivocinereus 11-98 growth and biosynthesis of heliomycin were studied. It was shown that carbon sources such as glycerol, mannitol and ramnose were the most favourable for the antibiotic biosynthesis. These carbon sources belonged to the group of substances providing high growth rates of the culture. Ranging of the culture growth rates and antibiotic production levels revealed a set of carbon sources providing a converse relationship between the growth rate and antibiotic biosynthesis i.e. L-arabinose, potassium gluconate, raffinose and sucrose. It was suggested that these compounds were catabolic type regulators of heliomycin biosynthesis.

Acids↗
PubMed1987

[Polysaccharide composition of the cell wall of Streptomyces antibioticus RIA-594(39), a producer of the antibiotic oleandomycin].

The main polysaccharide components of the cell wall in S. antibioticus RIA-594 (39) i.e. peptidoglycan, teichoic acid and polysaccharide were studied. Peptidoglycan consists of the polysaccharide fraction containing equimolar quantities of N-acetylglucosamine and muramic acid and the peptide subunits including alanine, glutamic and L,L-diaminopimelic acids and glycine at a ratio of 1.4:0.9:1:0.9. It is characteristic that certain peptide subunits of the streptomycete contain no alanine. A polysaccharide differing from glycerol teichoic acid and containing galactose and N-acetylglucosamine was isolated from the cell wall. During the streptomycete development the quantity of peptidoglycan remained constant, the quantity of teichoic acid lowered and the quantity of polysaccharide increased. Correlation between the presence of aminosugars in the composition of teichoic acid and polysaccharide specific of the streptomycete cell wall and the presence of aminosugars in the structure of oleandomycin was shown. This is probably connected with characteristic features of the organism physiology.

Amino Acids↗
PubMed1987

[Polymorphism of a culture of Streptomyces olivocinereus, the producer of heliomycin].

Polymorphism of the heliomycin-producing organism S. olivocinereus was studied and not less than 5 stable spontaneous variants differing in their differentiation levels were detected. Variant I (the main type) had the most developed cultural and morphological features characteristic of the whole population: abundant aerial mycelium with all specific subsequent stages of the development terminated by heavy sporulation and formation of long spiral spore chains. The other variants markedly differed from variant I. In variant III grey aerial mycelium (the final stage of differentiation) formed only at the colony margin. In variant IV it formed with a significant delay as a thin layer. In variant II it was very scanty and in variant V it differed by its pigmentation. Sporulation in variants II, III, IV and V was scanty and the character of the spore chains differed from that of the main type. Capacity for heliomycin production in the variants correlated with the level of morphological differentiation: the antibiotic activity of the highly differentiated variant I was the highest, while the low differentiated variant II was practically inactive.

Anti-Bacterial Agents↗
PubMed1987

[Action of thomicide on bacterial cells. The membranotropic activity of thomicide].

It was shown that a combined drug thomicide impaired permeability of cell membranes in Micrococcus luteus 2665 and Staphylococcus aureus 209P inducing production of substances with the absorption maxima at 260 nm. Active lysis of the M. luteus 2665 protoplasts under the action of thomicide used in a dose of at least 60 micrograms per 1 mg of the protoplast proteins was observed. Thomicide inhibited oxidation of the substrates by intact cells of the staphylococci and micrococci. Respiration of the micrococcal protoplasts was inhibited by thomicide in concentrations inducing lysis of the protoplasts. Impairment of function and the state of the membranes of the bacterial cells (production of compounds with the absorption maxima at 260 nm, protoplast lysis and respiration inhibition) was recorded at thomicide concentrations lower than the bactericidal ones. The membranotropic activity of thomicide was associated with thermostable component of the complex.

Animals↗
PubMed1986

[Effect of the cultivation temperature on gramicidin S biosynthesis under conditions of producer growth limitation by oxygen].

The gramicidin S-producing organisms Bacillus brevis was grown under submerged conditions in fermenters at a temperature of 32 degrees C which is the lower limit of the temperature ranges providing the culture growth. The culture was also grown under the optimal temperature conditions, i.e. 40 degrees C. At the lower temperature the biomass synthesis at the early stage of the culture development was decreased, the intensity of the cell respiration was low and solubility of oxygen in the liquid was increased. Under such conditions the decrease in the levels of dissolved oxygen in the medium was less pronounced than that under the control conditions. At the lower temperature limitation of the culture growth by the deficit of dissolved oxygen lowered and the period of the antibiotic synthesis increased which brought about a rise of the gramicidin S yield by 30-40 per cent.

Bacillus↗
PubMed1986

[Changes in the permeability of streptomycete cytoplasmic membranes due to gramicidin S and its derivatives].

Exposure of intact mycelium and protoplasts of Streptomyces sp. 26-115 to gramicidin S resulted in impairment of permeability of the cytoplasmic membranes thus inducing a loss of low molecular compounds by the cells and protoplasts. Aminoacyl and guanyl derivatives of gramicidin S with respect to the delta-amine group of ornithine were somewhat less effective with respect to the streptomycete membranes. The same as the initial antibiotic, these derivatives had positively charged groups. The changes in the membranes of the streptomycete protoplasts induced by gramicidin S and its derivatives did not result in the protoplast lysis accompanied by decreasing of the suspension optical density. The neutral derivative having no positive charge and not capable of complexing with the membrane phospholipids and the carboxyl-containing derivative with a negative charge showed a low membrane activity when applied to the protoplasts and induced no impairment of permeability of the intact mycelium membranes. The use of phosphates as factors increasing the membrane activity of the gramicidin derivatives having no positive charge is not possible since in the presence of phosphates streptomycete protoplasts are readily destroyed.

Cell Membrane Permeability↗
PubMed1986

[Comparative study of the surface-active properties of gramicidin S and its derivatives by polarography].

Gramicidin S and its derivatives by the free amino groups of the ornithine moieties were studied with respect to their effect on interface tension of mercury and the polarographic background for comparative estimation of the surface active properties of these compounds. The same way as the compounds preserving their main properties, the neutral and acid derivatives lowered the polarographic maximum. No correlation between the level of the antimicrobial and membrane activity and the surface active properties of the tested compounds was observed. It is likely that the direct cause of the induced biological effect is not connected with the surface active properties responsible for possible interaction of the tested substances with the cell (protoplast).

Cell Membrane Permeability↗