Antibiotiki i meditsinskaia biotekhnologiia = Antibiotics and medical biotechnology最新文献

Photochemical (cis-trans) isomerization of levorin A2 under the effect of light at wave lengths of 313 and 365 nm (excitation of the polyenic system and p-aminobenzoylene respectively) was studied. In case of the polyenic system excitation the reaction was reversible and the process quantum yield was extremely low while the use of light at the wave length of 313 nm as photochemical activator resulted in increasing the quantum yield by two orders. In this case triplet-triplet transfer of energy took place. A calculation procedure is recommended for quantitative determination of the quantum yield of levorin isomerization including direct and reverse reactions. The procedure may be used in study of other objects with similar mechanisms of phototransformation.

It was shown that combined use of the polyene antibiotic amphoglucamine (AMG) and 5-fluorocytosine (5-FC), rifampicin, or methacycline was much more efficient in therapy of experimental generalized candidiasis. Combination of AMG with 5-FC or rifampicin proved to be the most favourable. The use of these combinations resulted in a 7-8-fold increase in the average lifespan of experimental animals, markedly increased their survival and lowered contamination of the internal organs with the fungus. Combination of AMG with 5-FC resulted in complete healing of experimental mice by the end of the treatment. Summation of the antifungal action of the drugs provided the required effect with the polyene dose 2 times lower than the therapeutic one.

Along with an increase in the activity of a superproductive strain of Str. levoris there was observed in its population an increase in the number of low active cells sensitive to high concentrations of the own antibiotic. Levorin had an especially high toxic action on viability and antibiotic activity of the low productive strain 78/19 as compared to the highly productive strain 78/72. Resistance of the levorin-producing organism to its own antibiotic was associated with composition and properties of the cytoplasmic membrane. Acridine orange had no effect on survival and morphological variation of the strains studied. It had either no effect on the antibiotic production by the low active strain 78/19. However, under the effect of the dye there was induced marked variation in the highly productive strain 78/72 with respect to the antibiotic production property: decreasing of the population activity due to elimination of highly productive variants and accumulation of low productive variants. The data suggested the presence of plasmid genes in the levorin-producing organism determining biosynthesis of the antibiotic and resistance to it.

Tissue pharmacokinetics of aclarubicin and its active metabolites was studied with high performance liquid chromatography. The drug was administered to rats intravenously in single doses of 5 and 10 mg/kg and orally in a single dose of 10 mg/kg. With both the administration routes the highest concentrations of the drug and its metabolites were attained in the lymph nodes. Then followed the spleen and lungs. The lowest content of the drug was detected in the heart. The total values of the areas under the concentration/time curves for aclarubicin and its metabolites in the tissues of the heart, lungs, lymph nodes and spleen after oral administration were respectively 2, 3, 4 and 7 times lower than those after the drug intravenous administration in the same dose. The concentrations of the active metabolites MA144N1 and MA144T1 exceeded those of aclarubicin and were detected in the tissues within a longer period as compared to the unchanged drug. With repeated administration preferential accumulation of the metabolites in the tissues and their increased contribution to the aclarubicin antitumor effect could be suspected.

Sorption of cyanocobalamin (vitamin B12) by silochrome C-120 of various graininess levels was studied under dynamic conditions. It was shown that the low-grained sorbent provided marked increasing of the cyanocobalamin sorption rate and enabled the use of the sorbent thin layers at high rates of the solution supply.

Spatial structure of polypeptide antibiotic polymyxin M in water was studied by one-and two-dimensional (COSY, COSY-45, RELAY) H NMR spectroscopy. Analysis of the signal spectral parameters revealed two intramolecular hydrogen bonds in the cyclic part of the molecule which was analogous to the structure of polymyxin B. However, configuration of both the beta-turns in the polymyxin M structure differed from that of the detected earlier beta-turns in the structure of polymyxin B.

Actinomycete plasmid pSB24.1 was cloned on vector of the E. coli pBR325 system. The following bireplicon plasmids were obtained: pSU501 and pSU502 (by XhoI site of pSB24.1 and SalGI site of pBR325), pSU503 (by Bg1II (c) site of pSB24.1 and BamHI site of pBR325) and pSU504 (by Bg1II(b) site of pSB24.1 and BamHI site of pBR325). In the cells of E. coli C600 plasmids pSU501-504 determined phenotype AprCmrTcs and were stable. In the cells of Str. lividans the initial structure pSU501 selected by Ltz+ phenotype was maintained at a frequency of 12.5 per cent. Analysis of the deletion variants of pSU501 isolated from Str. lividans showed that the deletions were induced by both the pBR325 region and the pSB24.1 DNA fragment near XhoI site. The region from SacII(a) site to Bg1II(b) site clockwise in the map of plasmid pSB24.1 was not significant for its replication and maintenance in Str. lividans. There were detected unique sites of pSB24.1 and its derivatives useful for cloning. Possible shortening of plasmid pSB24.1 by 567 kb (the length between the terminator of the open frame reading translation and XhoI site) was revealed.

Conditions for cultivation of basidiomycete Coprinus radiatus on agar media and its submersion fermentation were developed. An antibiotic was isolated from the fermentation broth filtrate by extraction with ethyl acetate followed by purification on a column with silica gel. The antibiotic had a pronounced in vivo effect on hemoblastosis La. Spectral analysis of the antibiotic (UV, IR, NMR and mass spectra) showed that it was identical to patulin (a toxin).

Ulcer microflora from 97 stomachs resected from 28 patients with gastric ulcers, 65 patients with duodenal ulcers and 4 patients with gastric and duodenal ulcers was studied. Various microorganisms were detected in 65.9 +/- 4.8 per cent of the patients with predominance of staphylococci and streptococci. At pH of the gastric juice about 4, the isolation amounted to 61.2 +/- 5.5 per cent, from 4.0 to 7.0-81.8 +/- 11.6 per cent and more than 7.0-100 +/- 4.1 per cent respectively. The levels of associations increased from 27.8 to 83.3 per cent. In patients with hypo- and achlorhydria the frequency of staphylococcus isolation from the ulcers was 2.6 times higher and that of yeast and Candida isolation was 3.7 times higher. Diphtheroids were isolated from the ulcers only of patients with normo- and hyperchlorhydria. The majority of the isolates were sensitive to gentamicin (76.7 +/- 4.6 per cent of the strains). Multiple resistance to 17-18 antibiotics was observed in enterococci.