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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
PubMed1998

[Antimicrobial and membranolytic activity of sterically hindered phenols].

Antimicrobial activity of some complicated space phenols (screened) was studied. The compounds had different activities against grampositive bacteria and were inactive against gramnegative microbes. Di-tertiary butyl derivatives of pyrocatechol and resorcin showed the highest activities. The MICs of such derivatives for the collection strains of Bacillus megaterium, Bacillus subtilis and Staphylococcus aureus were 8 to 30 micrograms/ml and exceeded 6-25 times those of the nonsubstituted analogs. The derivatives of pyrocatechol and resorcin impaired the membrane permeability in susceptible intact cells of B.megaterium and S.aureus 209P and had no effect on the membrane permeability of the Escherichia coli resistant cells. In concentrations up to 200 micrograms/ml the nonsubstituted analogs of pyrocatechol and resorcin did not impair the membrane permeability in the intact cells of the above bacteria. Di-tertiary butyl derivatives of pyrocatechol and resorcin had lytic activity with respect to cytoplasmic membranes (protoplasts) of B.megaterium and had no lytic action on E.coli spheroplasts. The antimicrobial spectrum correlated with the membranotropic properties of the compounds. It was suggested that the target of the antimicrobial action of the screened phenols was the bacterial cell cytoplasmic membrane.

Anti-Bacterial Agents↗
PubMed1997

[A conjugate of ristomycin A ristosaminylaglycon-polymyxin B: the spectrum of its antimicrobial action and its membranolytic activity].

Antimicrobial activity of a conjugate based on two antibiotics, i.e. ristomycin A and polymyxin B was studied. The conjugate was shown to have a broad antimicrobial spectrum. In concentrations of 5 to 30 micrograms/ml it inhibited the growth of gram-positive and gram-negative bacteria and in concentrations of 5 to 40 micrograms/ml it inhibited the growth of the pathogenic clinical strains. An insignificant membranolytic action of the conjugate with respect to membranes of the susceptible bacteria and no hemolytic action on human red blood cells were detected.

Anti-Bacterial Agents↗
PubMed1997

[Interaction of actinomycin D with suspended mycelium of streptomyces].

Binding of exogenous actinomycin D (AMD) by washed mycelium of streptomycetes i.e. variants of Streptomyces chrysomallus producing and not producing actinomycins and Streptomyces lividans not synthesizing the antibiotics was studied. Dependence of the bound quantity of AMD on its concentration, incubation time and temperature, energy source availability, influence of respiration inhibitors and the membranotropic antibiotic gramicidin S was shown. The intracellularly localized portion of the bound AMD likely penetrated to the cells by diffusion and was strongly bound presumably to DNA in the AMD sensitive S.lividans and to the specific intracellular actinomycin-binding proteins in the AMD resistant variants of S.chrysomallus. The ratio of AMD strongly bound by the mycelium and AMD easily washed with physiological solution and probably localized on the surface was determined. The ratio depended on sensitivity of the culture to AMD and for the variants of S.chrysomallus on the age of the culture and its ability to synthesize actinomycins.

Anti-Bacterial Agents↗
PubMed1996

[Actinomycin D resistance of gramicidin-resistant strains of Staphylococcus].

Factors defining actinomycin D resistance in Staphylococcus aureus resistant to gramicidin S were investigated. The results of the thin layer chromatography, high-voltage electrophoresis and bioautography showed that the resistant cells did not inactivate actinomycin D by the hydrolysis of the lactone bond in the antibiotic molecule. The estimation of the cell ability to bind actinomycin D revealed that the antibiotic binding to the resistant cells was lower by 70-75 per cent as compared to the cells of the susceptible strains. Gramicidin S impaired the intactness of the cytoplasmic membranes and increased the absorption of actinomycin D by the susceptible cells and to a much lesser extent by the cells of the resistant strains. Actinomycin D bound by the susceptible cells could not be washed out with a buffer solution. It could be separated from the cells only by extraction with an organic solvent. Comparative electron microscopy of the susceptible and resistant cells demonstrated that the cell walls in the resistant strains were 1.5-2-fold thicker than the cell walls in the susceptible strains. The actinomycin D resistance of the Staphylococcus strains resistant gramicidin S was likely conditioned by the barrier properties of the morphologically changed cell walls.

Absorption↗
PubMed1996

[Absorption of various actinomycins by Staphylococcus aureus cells].

The absorption of actinomycin D by the cell suspension of Staphylococcus aureus via diffusion linearly depended on the antibiotic concentration in the suspension within the ranges of 2 to 15 micrograms/ml. The absorption of active actinomycins C2, C3 and Au6 was the same as that of actinomycin D. The Staphylococcus intact membranes limited the inlet of the actinomycins to the cells since the membranotropic substances such as gramicidin S and its derivatives and thyrocidin increased their absorption by 30-70 per cent. The absorption of a low active actinomycin D0 and inactive actinomycinic acid even after the exposure to the membranotropic substances was not detectable. These compounds did not form any complexes with DNA. The level of the absorption of the actinomycins by the cells was likely defined by their ability to complex with DNA.

Absorption↗
PubMed1993

[Comparative study on the activity of some enzyme systems in cells of gramicidin S sensitive and resistant strains of Staphylococcus aureus].

Polarographic determination of the rate of endogenic respiration of the cells of Staphylococcus aureus 209P showed that the respiration activity of the cells of the strain resistant to 20 micrograms/ml of gramicidin S was 20 to 30 per cent lower than that of the sensitive strain. The rate of oxygen consumption in oxidation of NADH by the membrane preparations of the resistant cells was also 25 to 30 per cent lower. By comparison with the initial sensitive strain the activity of endogenic DPI-reductases of the intact cells and NADH-dehydrogenases of the membranes of the resistant strain was also lower. The velocity of the valine transport to the resistant cells was much lower than that of the amino acid transport to the cells of the sensitive strain. Development of gramicidin S resistance in the staphylococcal strain was likely accompanied by a decrease in the activity of the energy metabolism in the membranes.

Amino Acids↗
PubMed1993

[Metabolism of alpha-ketoacids in erythromycin biosynthesis in various strains of Saccharopolyspora erythraea].

The absence of pyruvate and insignificant levels of alpha-keto-glutarate in the mycelium during the fermentation cycle were characteristic of a highly active erythromycin-producing strain of Saccharopolyspora erythraea. Alpha-keto-glutarate partially excreted to the fermentoffon broth. The activity of pyruvate decarboxylase and alpha-keto-glutarate decarboxylase was detected in the cells during the entire period of the cultivation. The same regularities were observed in the chloramphenicol resistant mutant of the strain. The mycelium of a low productive strain of S.erythraea contained not only alpha-keto-glutarate but also pyruvate and excreted large amounts of keto-acids. By the activity levels of the decarboxylases the low productive strain did not differ from the highly productive one. Propanol did not influence the growth of the low productive strain and the synthesis of erythromycin by it. However, it stimulated accumulation of keto-acids and especially pyruvate in both the mycelium and fermentation broth. Relation between the intensity of keto-acid metabolism and erythromycin biosynthesis is discussed.

Carboxy-Lyases↗
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↗