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Biomedical subjects

S E Esipov

Publications and source records attributed to S E Esipov.

At least 19 recordsLinked to original sources
PubMed2002

Unusual fatty acid composition of cerebrosides from the filamentous soil fungus Mortierella alpina.

The cerebrosides produced by the soil filamentous fungus Mortierella alpina strain KG-1/95 account for about 13% of the total polar lipids extractable from lyophilised cells with chloroform/methanol mixtures. By means of 1H NMR and (13)C NMR spectroscopy, matrix-assisted laser-desorption ionisation mass spectrometry, and chemical degradation experiment, they have been shown to be 1-O-beta-D-glucopyranosyl-2-N-(2'-D-hydroxyalkanoyl)-9-methylsphinga-4(E),8(E)-dienines, the fatty acid composition of which is unusual and consists of 2-hydroxytridecanoic (4%), 2-hydroxytetradecanoic (60%), 2-hydroxypentadecanoic (20%), and 2-hydroxyhexadecanoic (16%) acids.

Cerebrosides↗
PubMed2001

Two unusual glycerophospholipids from a filamentous fungus, Absidia corymbifera.

The chloroform-methanol extractable lipids of the soil filamentous fungus Absidia corymbifera VKMF-965 account for about 20% by weight of dry cells and are composed of low-polarity constituents (about 75% of the total lipids), such as triacylglycerols (mainly), diacylglycerols, sterols and free fatty acids, as well as of glycolipids (about 3%) and phospholipids. The last consist largely of components common to the fungal lipids, namely, phosphatidylethanolamine (38% of the total phospholipids), phosphatidyl-myo-inositol (16%), diphosphatidylglycerol (12%), phosphatidylcholine (7%), phosphatidic acid (6%) and phosphatidylglycerol (3%), and two unusual phospholipids, PL1 (6%) and PL2 (9%). Based on the infrared (IR), (1)H-nuclear magnetic resonance (NMR), (13)C-NMR and mass spectra along with the results of degradation experiment, these two phospholipids have been established to be 1,2-diacyl-sn-glycero-3-phospho(N-acetylethanolamine), or N-acetyl phosphatidylethanolamine, and 1,2-diacyl-sn-glycero-3-phospho(N-ethoxycarbonyl-ethanolamine), respectively. These structures have been confirmed by preparing similar phospholipids from the phosphatidylethanolamine isolated from the same fungus and correlating their chromatographic behaviour, IR and (1)H-NMR spectra with those of PL1 and PL2. So far N-acetyl phosphatidylethanolamine has been detected only in cattle and human brains and a human placenta but its structure was not rigorously proved. PL2 is a novel lipid; to our knowledge no natural phospholipid with an urethane group has yet been found. The main fatty acids of both the phospholipids are n-hexadecanoic, octadecanoic and octadecadienoic ones; PL2 contains in addition a considerable amount of octadecatrienoic acid with its greater portion located at the sn-1 position.

Absidia↗
PubMed1998

[A new mathematical approach for determining antibiotic concentrations using the agar diffusion method].

A mathematical approach using the one-point intercept form of the equation of a straight line for the assay of antibiotic biological activity by the agar diffusion method is described. Insignificant alteration in the experimental conditions made it possible to markedly lower the volume of work and materials for the statistic processing. As distinct from the routine methods, the assay substance in three different concentrations is applied to three cavities on a dish and the standard substance in one control concentration is applied to the other three cavities on the same dish. The antibiotic biological activity is estimated from the equation lg cn = lg cst + (dn - dst)/bi when the relationship between the dose logarithm and the size of the diameters of the test microbe inhibition growth zones is direct. When the relationship is inverse e.g. when the dose is expressed as the dilution, the equation lg cn = lg cst + (dst - dn)/bi is used. Factor bi is determined experimentally for every sample by the mean value of the sizes of the inhibition growth zone diameter by the programs of the simple linear-regression.

Agar↗
PubMed1998

[Novel mathematical approach to determination of antibiotics concentration by agar diffusion method. Analysis of graphical, table and mathematical options of relative biological activity estimation].

Several varieties of relative biological activity estimation are comparatively analyzed and illustrated by an example of tylosin. For visual demonstration the estimates with the equation of a straight line are represented graphically. It is concluded that the design equations in the State Pharmacopeia XI (USSR) should be respectively replaced. The advantages of the variety for the biological activity estimation with the one-point intercept form of the equation of a straight line are illustrated by particular examples.

Agar↗
PubMed1997

Fluviols, bicyclic nitrogen-rich antibiotics produced by Pseudomonas fluorescens.

Fifteen fluorescent pseudomonads, isolated from the rhizosphere of agricultural plants, were similar in both their phenotypic properties and the chemical nature of produced pigments, to the previously described Pseudomonas fluorescens var. pseudoiodinum. DNA-DNA hybridisation data showed their genetic similarity (but not identity) to different biovars of P. fluorescens. A family of antibiotics-fluviols belonging to pyrazolo-[4,3-e]as-triazine derivatives was isolated from studied strains; isolation, properties, antimicrobial and antitumour activity of fluviols are described.

Animals↗
PubMed1997

[Metabolites produced by Streptomyces kanamyceticus mutants with impaired biosynthesis of kanamycin].

Metabolites produced by Streptomyces kanamyceticus mutants with impaired kanamycin biosynthesis (kan mutants) were investigated by thin layer chromatography. With spectrophotometric scanning of the chromatograms the quantitative content of kanamycin A and 2-desoxystreptamine (2-DOS) in the culture fluid was determined. Five groups of the S.kanamyceticus mutants with impaired kanamycin biosynthesis at various stages were identified: kanA produced no D-glucosamine, kanB and kanC produced no 2-DOS, kanD was not able to transfer 2-DOS to the metabolites with the antibiotic activity, kanG synthesized no kanosamine.

Anti-Bacterial Agents↗
PubMed1996

Periodic phenomena in Proteus mirabilis swarm colony development.

Proteus mirabilis colonies exhibit striking geometric regularity. Basic microbiological methods and imaging techniques were used to measure periodic macroscopic events in swarm colony morphogenesis. We distinguished three initial phases (lag phase, first swarming phase, and first consolidation phase) followed by repeating cycles of subsequent swarming plus consolidation phases. Each Proteus swarm colony terrace corresponds to one swarming-plus-consolidation cycle. The duration of the lag phase was dependent upon inoculation density in a way that indicated the operation of both cooperative and inhibitory multicellular effects. On our standard medium, the second and subsequent swarm phases displayed structure in the form of internal waves visible with reflected and dark-field illumination. These internal waves resulted from organization of the migrating bacteria into successively thicker cohorts of swarmer cells. Bacterial growth and motility were independently modified by altering the composition of the growth medium. By varying the glucose concentration in the substrate, it was possible to alter biomass production without greatly affecting the kinetics of colony surface area expansion. By varying the agar concentration in the substrate, initial bacterial biomass production was unaffected but colony expansion dynamics were significantly altered. Higher agar concentrations led to slower, shorter swarm phases and longer consolidation phases. Thus, colony growth was restricted by higher agar concentrations but the overall timing of the swarming-plus-consolidation cycles remained constant. None of a variety of factors which had significant effects on colony expansion altered terracing frequencies at 32 degrees C, but the length of the swarming-plus-consolidation cycle was affected by temperature and medium enrichment. Some clinical isolates displayed significant differences in terracing frequencies at 32 degrees C. Our results defined a number of readily quantifiable parameters in swarm colony development. The data showed no connection between nutrient (glucose) depletion and the onset of different phases in swarm colony morphogenesis. Several observations point to the operation of density-dependent thresholds in controlling the transitions between distinct phases.

Agar↗
PubMed1988

[Allergenic properties of the substance produced by the Streptococcus strain sp. Thom-1606].

The newly isolated biologically active agent "STP" (the substance produced by Streptococcus strain sp. TOM-1606) has been found to possess no allergenic properties. This new preparation has shown hyposensitizing activity on the level with the allergen. The morphological data obtained in the study of the organs of experimental animals have revealed the immunostimulating action of preparation "STP" on the body, that is confirmed by the characteristic transformation of the internal organs of experimental animals.

Adjuvants, Immunologic↗
PubMed1988

[Structure of the reaction adduct of xanthothricin with acetone].

Reaction of xanthothricin demethylation by amines in acetone as a solvent yielded a new compound with a formula of C10H13N5O3. Mass spectrometry, 1H NMR-spectroscopy and x-ray analysis showed that the compound was 4H-1,6-dimethyl-4a(2-oxopropyl)-pyrimido-[5,4-e]-1 ,2,4-triazine-5,7-dione.

Acetone↗
PubMed1987

[Structure and physicochemical properties of isolated molecules of reumycin].

IR and electron spectra of an uracil derivative (antitumor antibiotic reumycin) were studied by low temperature spectroscopy. The experimental data corresponded to the quantum chemistry calculations of electron transmission. On the basis of the spectra interpretation the molecular structure of the reumycin isolated molecules was suggested. pKa of reumycin in aqueous medium was determined by UV spectroscopy.

Antibiotics, Antineoplastic↗
PubMed1987

[Study of alkaline hydrolysis of reumycin using NMR spectroscopy].

The transformation sequence of reumycin in aqueous (D2O) solutions with various pD was studied by NMR spectroscopy and the structures of the yielding products were determined. It was shown that formation of 6-(3-methylureido)-1,2,4-triazine-5-carboxylic acid was the first stage of reumycin alkaline hydrolysis. The subsequent cyclization of this compound resulted in obtaining 5-methyl-5H-imidazo [4,5-e]-1,2,4-triazin-6 (7H) one-4a-carboxylic acid in mono-,di- or trianionic form which depended on the medium pH and was due to dissociation of the carboxylic group, N(4)H group of the triazine ring and N(7)H group of the imidazolidinone ring.

Antibiotics, Antineoplastic↗
PubMed1986

[Isolation and characteristics of an antibacterial substance produced by a strain of Streptococcus sp. Thom-1606. A study of the biological activity of the metabolic products of Streptococcus sp. Thom-1606].

The data on the biological properties of the culture fluid of Streptococcus strain sp. TOM-1606 are presented. The native preparation has been shown to possess the capacity for stimulating the rate of the clearance of the peritoneal cavity of mice from Staphylococcus aureus cells, strain MT-1, rif. r., found to be insensitive to the action of the above-mentioned preparation in vitro. The crude preparation produces a transitory bacteriostatic effect on the streptococcal and staphylococcal strains under study. The preparation produces a prolonged bacteriostatic effect only on Micrococcus luteus test strain. All these data suggest that the crude preparation contains at least two active principles.

Animals↗
PubMed1986

[X-ray structural study of the pyrimido-[5,4-e]-1,2,4-triazine antibiotics xanthothricin and fervenulin].

The structures of xanthothricin (I) and fervenulin (II), pyrimido-[5,4-e]-1,2,4-triazine antibiotics were determined by x-ray analysis. The crystals of I and II are monoclinic: a 9.667(6), 18.270(7), b 14.029(9), 5.723(2), c 6.914(3), 18.058(7) A, beta 116.47(3), 118.90(2) degrees, Z 4,8; space group P21/c. Analysis of bond length distribution in I and II was indicative of significant alternation of the double and ordinary bonds.

Chemical Phenomena↗
PubMed1985

[Study of the stability of pyrimido-[5,4-e]-1,2,4-triazine antibiotics in acid-base media by NMR spectroscopy].

A comparative study of the NMR 1H and 13C spectra of reumycin, fervenulin and xanthothricin in aqueous acid-base media showed that at pH or pD ranging from 8.0 to 1.0 the antibiotics were chemically stable. By the ratio of the 1H and 13C chemical shifts of reumycin at pH 4.0-10.0 the pKa values of this antibiotic were determined: 6.7 in aqueous (D2O) solution and 8.76 in dimethylsulfoxide media. Alkalization of the solutions of reumycin (pH 12.0), fervenulin (pH 9.0) and xanthothricin (pH 8.0) resulted in irreversible chemical transformation of the antibiotics. The analysis of the chemical shifts in the PMR spectra of the transformation products revealed transformation of the uracil ring in reumycin and uracil and triazine rings in fervenulin and xanthothricin. Alkalization of the xanthothricin solutions resulted also in demethylation with formation of reumycin.

Anti-Bacterial Agents↗
PubMed1983

[Free radical mechanism of action of pyrimido-triazine antibiotics].

EPR spectra of anion radicals were recorded as a result of chemical or enzymatic reduction at various pH of the pyrimido-triazine antibiotics. These anion radicals easily form superoxide radicals in the presence of oxygen. It is supposed that a higher selectivity of reumycin action is due to difference in the redox potentials of the neutral and ionized antibiotic forms. A possibility of enhance the reumycin potency may involve the pH lowering inside the tumor cells - for example, by glucose injections.

Animals↗
PubMed1979

[Aminoglycoside-3'-phosphotransferase from Actinomyces fradiae. The identification of its inactivation product].

Neomycin phosphate was obtained as a result of neomycin phosphorylation with aminoglycoside-phosphotransferase from Act. fradiae. It was isolated from the reaction mixture and purified. Successive ion exchange chromatography on columns with Amberlite IRC-50 (NH+4 form), Dowex 1 X 10 (OH- form) and Amberlite CG-50 (NH+4 form) was used for purification of the inactivation product. The findings of the elementary analysis of neomycin phosphate showed the presence of 1 mole of phosphorus per 1 mole of the antibiotic. From the results of the chemical analysis, IR- and NMR-spectrometry neomycin phosphate and neamine phosphate obtained from it by methanolysis were identified as neomycin-3'-phosphate and neamine-3'-phosphate, respectively. The data indicate that the enzyme isolated from Act. fradiae is aminoglycoside-3'-phosphotransferase.

Aminoglycosides↗
PubMed1978

[Aminoglycoside-3'-phosphotransferase I from aminoglycoside-polyresistant strain E. coli 182].

An aminoglycoside-3'-phosphotransferase I catalyzing phosphorylation of some aminoglycoside antibiotics with the 3'-hydroxyl group has been purified from the cells of aminoglycoside resistant strain E. coli 182 by competitive affinity chromatography on neomycin-Sepharose and gel-filtration on Sephadex G-100. The product of enzymatic phosphorylation of kanamycin A was isolated and identified as kanamycin-3'-phosphate by NMR, thin-layer chromatography and chemical characterization. The kinetic properties of the enzyme were studied. The pH-optimum was between 7,8--8,0; the [S]0.5 values for kanamycin, neomycin and paromomycin were 2.10(-5) M, the energy of activation was 15,9 kcal/mol. The bivalent cations were required for activity of the enzyme, Mg2+ was the most effecient. The relative aminoglycoside antibiotics containing no 3'-hydroxyl group were competitive inhibitors of the enzyme activity with Ki values close to [S]0.5.

Aminoglycosides↗