PubMed Health⌕ Search

Biomedical subjects

D N Ostrovskiĭ

Publications and source records attributed to D N Ostrovskiĭ.

At least 19 recordsLinked to original sources
PubMed2003

[Effect of fosfidomycin on development of various infections in mice].

Antibiotic fosmidomycin will know as inhibitor of the nonmevalonate pathway of isoprenoid biosynthesis and as possible antimalarial drug, was shown to possess a certain protective effect on mice experimentally infected with tularemia, tiphus or coli-septicemia. Positive effect on mice with chronic form of tuberculosis was not observed when the animals were given 1 mg of fosmidomycin per capita twice a day. Under oxidative conditions an ESR signal of long living nitroxil free radicals were registered in the water solution of fosmidomycin. The radicals are supposed to be involved in the therapeutic effect of the antibiotic.

Animals↗
PubMed1996

[Participation of 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate in reactions of bacteria on oxidative stress and their persistence in macrophages].

In aerated medium, Corynebacterium ammoniagenes cells accumulate 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC) during heat shock and in the presence of O2--generating compounds or ozone. The ability to accumulate MEC was genetically transformed from C. ammoniagenes to E. coli XL-1; transformed E. coli (2-31 clone) accumulates MEC in the presence of glucose and glucose oxidase (generation of H2O2) or benzylviologen (generation of O2-); the viability of transformed bacteria inside the murine peritoneal macrophages also significantly increases. However, model conditions of phagosomes of warm-blooded animals (NO + H2O2 + O2-) did not cause MEC accumulation by C. ammoniagenes but increased the formation of polyphosphate which can be due to selective oxidative aberration of biosynthetic processes. Growth rate of Acanthamoeba castellanii on solid medium with bacterial lawn was not significantly different in C. ammoniagenes, C. ammoniagenes with preaccumulated MEC, E. coli XL-1, and E. coli 2-31 and did not depend on the accumulation of MEC by bacteria. Unlike the recipient E. coli strain, the transformed 2-31 clone synthesizes two nonpolar lipids (Rf = = 0.85 and 0.75; TCL on Silufol in hexane) and carotinoid pigments; this can be due to changes in metabolic pathways of isopentenylpyrophosphate that can be a precursor of MEC biosynthesis. Thus, MEC is involved in bacterial responses to certain components of oxidative stress and in bacterial persistence inside the macrophages.

Animals↗
PubMed1995

[Oxidative stress and organic cyclopyrophosphates in bacteria].

Oxidative stress in nocardioform bacteria--Corynebacterium (Brevibacterium) ammoniagenes, Micrococcus luteus and Mycobacterium smegmatis--is accompanied by a significant accumulation of 2-C-methyl-D-erythrol-2,4-cyclopyrophosphate (MEC), which is correlated with the ability of the producer to grow under stress. Metabolic stability of MEC in bacterial cells, its spontaneous isomerization into 1,2-cyclophospho-4-phosphate and the possibility of a genetic transfer of the MEC-synthesizing capacity from Corynebacterium to E. coli have been demonstrated. The involvement of MEC in the response to oxidative stress via the complex formation between MEC and bivalent cations has been postulated.

Bacteria↗
PubMed1995

[Stability of a new product of oxidative stress in bacterial cells].

Data on 32P-label incorporation with subsequent addition of non-radiolabelled o-phosphate suggest that the new phosphorus compound, 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC), accumulated in the cells of some bacterial species in response to oxidative stress does not rapidly exchange phosphorus with external o-phosphate 3 hours after the introduction of its synthesis inducers into the Corynebacterium ammoniagenes culture. The accumulated MEC is retained in the cells despite the action of the cell wall synthesis inhibitor, chloramphenicol, or the energetic poisons, KCN and iodoacetate and also under anaerobic conditions. It has been shown that incubation of the cell-free lysate of a non-induced culture, Micrococcus luteus, with MEC does not result in MEC hydrolysis; therefore, MEC accumulation after the redox-mediator addition is hardly due to the hydrolase inactivation but, rather, is due to the activation of the MEC-synthesizing enzyme. The cells of C. ammoniagenes incorporate 32P from [32P]MEC but not 14C from [14C]MEC. This points to MEC hydrolysis prior to the uptake of its phosphoryl fragment by the cells. In this case 32P is found in the fractions differing by their position from MEC fractions. Experiments with sheep erythrocytes and mouse splenocytes revealed that MEC (10-100 micrograms per 1,000,000 splenocytes) does not influence the antibody production by these cells, whereas used at concentrations of 200-550 micrograms per 1,000,000 cells, MEC enhances the antibody production. However, while doing so, MEC causes the destruction of a considerable portion of splenocytes and sheep erythrocytes.

Animals↗
PubMed1983

[Submergence of Micrococcus lysodeikticus F1-ATPase into the hydrophobic phase of the membrane, using 2,4,6-trinitrobenzosulfonate and 12-0-(azidoformyl) stearic acid methyl ester].

The accessibility of F1-ATPase from Micrococcus lysodeikticus in solution and in the membrane for the specific water-soluble NH2-group reagent, 2,4,6-trinitrobenzosulfonate (TNBS), was studied. Incubation of the soluble factor F1 with 50 mM TNBS pH 8.3 results in incorporation of 58.6 +/- 4.4 trinitrophenyl residues per mole of enzyme. At the same time F1-ATPase isolated from TNBS-pretreated membranes contains 27.2 +/- 2.0 TNP-residues per mole of enzyme. It is assumed that the different accessibility of F1-ATPase for TNBS in solution and in the membrane is due to incorporation of F1-ATPase into the membrane. Study of membrane F1-ATPase interaction with the radioactive lipid-soluble photoreactive label, 12-0-(azidoformyl) stearic acid methyl ester demonstrated that F1-ATPase does not immediately interact with the lipid phase of the membrane. It is suggested that membrane F1-ATPase may be enveloped by hydrophobic proteins.

Affinity Labels↗
PubMed1983

[Generation of membrane potential by aerobic bacteria Micrococcus lysodeikticus. Correlation between coupled and uncoupled respiration].

The effects of cyanide and nonylhydroxyquinoline-N-oxide on membrane potential generation and oxidase activities in intact cells and membrane particles of M. lysodeikticus were studied. Low concentrations of the inhibitors interacting with the components of one branch of a branched respiratory chain of M. lysodeikticus strongly inhibit the membrane potential generation and only slightly reduce the total respiration rate. It was assumed that the generation of delta psi takes place in the b-c locus of the respiratory chain branch terminated with cytochrome oxidase; over 90% of total O2 uptake provides for the uncoupled respiration via cytochrome omicron. Inside the b-c locus two sites responsible for delta psi generation were singled out; these sites differ in their sensitivities towards nonylhydroxyquinoline-N-oxide. Based on the data obtained and the effect of "extra-reduction" of cytochrome b566 a hypothetical model of the respiratory chain of M. lysodeikticus was developed, which includes the branching of the electron flux to two terminal pathways and redox equivalent transport cyclization via the menaquinone cycle. The physiological role of uncoupled respiration through cytochrome omicron is discussed.

Aerobiosis↗
PubMed1983

[Study of a free radical compound from the cells of the bacteria Micrococcus lysodeikticus].

Some physico-chemical properties of a compound previously detected in M. lysodeikticus cells were studied. This compound is hydrophilic, has hydrophilic, has a low molecular weight and does not contain The redox potentials of the free radical formation in the cytoplasm and in purified preparations were determined. A hypothetical reaction scheme is proposed.

Electron Spin Resonance Spectroscopy↗
PubMed1983

[Dynamic organization of the electron transport chain in bacterial membrane by radiation inactivation].

A complete cross-linking of proteins in isolated Micrococcus lysodeikticus membranes under effect of glutaric aldehyde causes 50% inhibition of the NADH-oxidase activity. Using the irradiation inactivation procedure, it was demonstrated that the size of the irradiation target for NADH-oxidase coincides with that for NADH-dehydrogenase and makes up to about 50 KD. In glutaric aldehyde-treated membranes the target size for NADH-oxidase is 3 times more than that, i.e. 150 KD. It is assumed that the effective electron transfer is mediated by a carrier assembly united into a supramolecular complex with a terminal life-time. Different assemblies exchange their components due to lateral diffusion of proteins in the membrane, which can account for the small size of the irradiation target for the oxidase activity.

Cell Membrane↗
PubMed1983

[Interrelation between the available boundary lipids in the bacterial membrane and the respiratory chain function].

In order to establish a possible correlation between the expression of the boundary lipid and the NADH-oxidase activity, the temperature dependences of the membranes of bacteria grown at 14 and 38 degrees C were investigated. The Tmelt. for the boundary lipid determined by comparing the excimerization parameters of the fluorescent probe pyrene in the vicinity of the proteins and in the total lipid phase was directly correlated with Tgrowth. A similar temperature dependence was observed with the NADH-oxidase activity, i. e. inhibition of activity at T greater than Tmelt. coincided with the disappearance of the boundary lipid. Incorporation of a cis-unsaturated fatty acid (linoleic acid) into the membranes markedly decreased the structural heterogeneity of membrane lipids and caused a simultaneous inhibition of the NADH-oxidase activity. No structural-functional changes were observed in the case of saturated fatty acids (stearic acid). It was assumed that the presence of boundary lipids in the membrane is essential for the normal functioning of the multienzyme system of the respiratory chain. Presumably, the state of the immediate lipid environment controls the function of the micrococcal respiratory chain at the level of interaction between the carriers in the membrane.

Electron Transport↗
PubMed1981

[Immunochemical study of the proteins of the bacterial membrane outer layers].

Incubation of Micrococcus lysodeikticus protoplasts with rabbit immunoglobulins containing antibodies against micrococcal membranes and a subsequent two-dimensional immunoelectrophoresis of solubilized membrane antigens allowed to reveal four main antigens of the outer membrane, of which only two are accessible to trypsin attack. The outer antigens disappear after protoplast treatment with snail digestive juice (active substance - phospholipase) and after incubation of growing cells with cerulenin, the inhibitor of fatty acid biosynthesis. Electrophoresis of the "cerulenin" membrane proteins in the presence of SDS revealed the disappearance of five proteins with molecular weights of 120 000, 150 000, 100 000, 68 000 and 16 000. Goat antibodies against rabbit serum or Staphylococcus aureus Cowan I cells (binding IgG gamma-globulins for fragment Fc) being added to the solubilized micrococcal membranes from protoplasts pretreated with antimembrane rabbit gamma-globulins precipitate about 5% of membrane protein. This suggests that the membrane outer layer antigens make up to about 5% of total protein content. The distribution of the components between the outer and inner membrane layers is discussed.

Antigen-Antibody Complex↗
PubMed1981

[Changes in the structural state of boundary lipids in bacterial membrane under effect of the membranotropic antibiotic gramicidin S].

Using data from measurements of excimerization at different wave-lengths of fluorescence excitation of the fluorescent probe pyrene in isolated M. lysodeikticus membranes and using the phenomenon of energy transfer in the protein tryptophanyl-pyrene system, a method for monitoring the probe population localized in the immediate proximity to protein structures, has been developed. This method allows to detect the existence within the physiological temperature range of a specific lipid population or a boundary lipid vicinal to the membrane proteins. The changes in this region under membrane treatment with the cyclodecapeptide antibiotic gramicidin S were studied. Incubation of membranes with the antibiotic increases the efficiency of quenching of membrane protein fluorescence by the quenchers localized in the membrane phase, i.e. 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxasolidinyloxyl, cetylpyridinium chloride and pyrene, and changes the protein chromophore accessibility for J-. The lateral mobility of pyrene during gramicidin S adsorption on the lipid and protein-lipid membranes is decreased. The results obtained are interpreted in favour of partial disturbance in the interaction of the boundary lipid and membrane proteins under effects of gramicidin S.

Cell Membrane↗
PubMed1981

[Functional and structural changes of E. coli membranes induced by low temperature freezing].

Low temperature freezing of E. coli cells causes a fall in endogenous respiration and stimulation of respiration by the non-penetrant substrate NADH. This decrease is not due to disturbances in the function of electron transport chain, since the dehydrogenase and oxidase activities and cytochrome content in the membranes of intact and frozen cells are practically the same. Frozen E. coli cells are incapable of ATP synthesis by artificial proton motive force, although the ATPase activity of isolated membranes is not changed. The disturbances in the penetrability barrier of protons after freezing can be revealed from changes in pH of cell suspensions after rapid acidification. It is assumed that the cell penetrability barrier undergoes alterations causing a loss of respiration substrates and, probably, oxidative phosphorylation uncoupling. A correlation between constant damages of the membrane penetrability barrier and cell survival was established. Using spin labelling of different localization, the changes in the state of membrane surface at the intact hydrophobic lipid zone were demonstrated. It was found that freezing does not induce lipid peroxidation.

Adenosine Triphosphatases↗
PubMed1980

[Possibility of reversing the action of the membranotropic antibiotic, gramicidin S, on bacteria].

The study on the possibility of eliminating gramicidin S from the bacterial cells which had adsorbed it showed that a part of the labeled antibiotic bound by the bacteria may be washed out with buffer or salines. When the cells which had adsorbed gramicidin S were treated with lecithin emulsion, a significant part of the bound antibiotic was transferred to the lecithin liposomes. This turned the gramicidin S effect to the cells: significant but not complete reduction of the membrane barrier properties and dehydrogenase reactivation. Elimination of gramicidin S also reduced the colony forming capacity in a part of the cells.

Adsorption↗
PubMed1980

[Localization of polyphosphates in cells of microorganisms using 31-P-NMR-145, 75 MHz of high resolution].

Using the method of 31P-NMR of high resolution at 145,78 MHz the presence of mobile inorganic polyphosphates in the cells of actinomycetes (Mycobacterium smegmatis), yeasts (Candida albicans and Endomyces magnusii) and bacteria (E. coli) was established. A considerable increase in the intensity and a low field shift of the polyphosphate signal after addition of EDTA to the M. Smegmatis cells can be indicative of possible localization of inorganic polyphosphates in the periplasmic space. The lack of effect of exogenous EDTA and Mn2+ on the polyphosphate signal in the spectrum of E. magnusii cells is probably due to localization of polyphosphates inside the cells. A comparison of 31P-NMR spectra of living cells and bacterial extracts of Staphylococcus aureus, Micrococcus lysodeikticus, Bacillus antracoides, B. megaterium and Salmonella typhimurium is given.

Ascomycota↗