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

Activity of glucose-6-phosphate dehydrogenase (I), fructose diphosphate aldolase (II) and succinate dehydrogenase (III) and content of pyruvate (IV) in the mycelium of the oleandomycin-producing organism were studied during increased intensity of the antibiotic synthesis. The increase in the intensity of the antibiotic synthesis was induced by exposure of the spores to a surface active substance, twin-21. After the exposure a rise in the activity of all the three enzymes in the phase of the culture intensive growth was observed. During the antibiotic intensive production the cultures with increased antibiotic production levels were characterized by significantly higher activity of I as compared to the control while the activity levels of II and III were approximately the same. It was shown that concentration of IV in the mycelium during the antibiotic intensive biosynthesis decreased and the decrease was more pronounced after exposure to twin-21.

The paper is concerned with investigation of the nature of ultrastructural alterations in Entamoeba moshkovski under the levorin effect. The studies showed that under the effect of levorin there appeared in the Entamoeba cultures diverse types of cells having chiefly the following ultrastructural alterations: a higher number and size of cytoplasmic vacuoles, lower density of the cytoplasm granular component, not intact nuclear and plasmatic membranes and cell cytolysis. Analysis of the experimental results suggested that the amebicidal effect of levorin on Entamoeba was mainly associated with its membranotropic properties.

Stability of azlocillin in aqueous solutions at pH 1.5-12.5 was studied at various temperatures. It was shown that degradation of the antibiotic proceeded as an irreversible first order reaction. Dependence of 1gk on the reverse temperature was described by the Arrhenius equation. The highest levels of azlocillin stability in solutions were observed at pH about 6.0. In solid state azlocillin was stable under the effect of the environmental factors. In the atmosphere of oxygen and carbon dioxide and on exposure to light the quality parameters of the antibiotic powder maintained at the control levels.

Streptomyces is characterized by genetic instability evident from high frequency of changes in various properties of secondary metabolites occurring spontaneously or under the influence of certain factors. Protoplast formation is one of such factors. The paper is concerned with the influence of protoplast formation and subsequent regeneration into the mycelial form on antibiotic potency of S. fradiae strain 165. It was shown that protoplast formation led to changes in antibiotic potency of separate colonies and shifts in the potency in the direction of its increasing. The antibiotic potency of certain variants after protoplast formation was 2 to 2.5 times higher than the initial one. Changes due to protoplast formation of S. fradiae strain 165 were not stable and lost after 4-5 passages on agar media. Comparative restriction analysis of total DNA of the variants with different potency levels did not provide detection of changes in the genome of the strains isolated after protoplast formation.

Eremomycin is relatively low toxic. LD50 of eremomycin on its intravenous administration to albino mice amounted to 1760 (1460-2130) mg/kg. It is 2.6, 3.5 and 6 times less toxic than ristomycin, vancomycin and teicoplanin, respectively. The rate of intravenous administration had no significant effect on eremomycin toxicity. Sensitivity of adult and preadolescent mice to eremomycin was almost the same. Eremomycin toxicity for male mice was somewhat higher than that for female mice. The use of 5 per cent glucose solution instead of distilled water as a solvent lowered 1.3-fold the toxicity of eremomycin in albino mice when it was administered intravenously. The toxic effect of eremomycin on the renal function played a significant role in the mechanism of the animal death due to the antibiotic. In experiments with guinea pigs eremomycin showed no allergenic effect. Unlike the other representatives of glycopeptide antibiotics, eremomycin had practically no local irritating effect which provided its recommendation for clinical trials not only as an intravenous but also intramuscular antibiotic.

Modified cellulose films are recommended to be used as carriers in preparing enzymatic membranes for penicillin-selective electrodes. The results of laboratory testing of the enzymatic penicillin-selective electrode based on the cellulose membrane with immobilized penicillinase are presented. In principle it was shown possible to use the enzymatic electrode in determining penicillin concentration in solutions. Dependence of the electrode reading on the buffer capacity was revealed. Optimal characteristics of the enzymatic membranes and the life-expectancy of the enzymatic electrode were determined.

Calcium salts of pantothenate (CPN), 4'-phosphopantothenate (CPP), S-sulfopantetheine (CSP), as well as pantetheine and panthenol were administered to mice by various routes and the influence of the administration route on acute toxicity of streptomycin (500 mg/kg, subcutaneously) was studied. It was shown that with subcutaneous, intramuscular, intraperitoneal and intravenous administration of CPN, CPP and CSP the acute toxicity of streptomycin was lower. The value of ED50 and the ranges of the antitoxic action (LD50/ED50) were indicative of high efficacy of CPP on its intravenous administration. In rats all the tested compounds normalized the liver excreting function (bromsulphalein test) impaired by exposure to streptomycin in subtoxic doses (200 mg/kg). The lowest levels of acetylation of the sulfacyl sodium test dose were observed in the animals treated with streptomycin in combination with CPN, CPP or CSP which could be explained by increased excretion and acetylation (detoxication) of the antibiotic.

The effect of various doses of antitumor antibiotic aclarubicin on the peripheral blood system and medullary hemopoiesis was studied on Wistar rats. It was shown that intraperitoneal administration of the drug in doses of 0.08, 0.33 and 1.2 mg/kg daily for 6 months did not induce any significant changes in the blood count of the animals. The dose of 1.2 mg/kg which is almost 2.5 times higher than the maximum course dose of aclarubicin for patients induced a decrease in the hemoglobin count recorded within the whole observation period. A single administration of aclarubicin in LD50 equal to 17.4 mg/kg resulted in marked suppression of hemopoiesis. The drug had the most prolonged suppressive effect on the bone marrow myeloid body. Depression of erythropoiesis was short-term.

A highly technological Yel-2 hybrid cell clone was isolated. The clone produces monoclonal antibodies to protein E of the yellow fever virus (Dakar strain). The Yel-2 hybridoma was cloned by the method of limiting dilutions. By the data of indirect immunofluorescence the titre of the specific antibodies reached 1:128 in the culture fluid and 1:10240 in the ascitic fluid. The Yel-2 antibodies had no cross reactions with forest-spring encephalitis, Dengue 2 and Dengue 4 viruses. In the hemagglutination inhibition test the activity of the Yel-2 ascitic preparations was observed at a dilution of 1:50000 while the complement fixation test did not reveal it. Administration of the Yel-2 cells into the abdominal cavity of mice BALB/c induced development of ascitic tumors in 97 per cent of pristane-sensitized mice and in 90 per cent of nonsensitized mice. The hybridoma was successfully transplanted from mouse to mouse (more than 20 passages during the observation period) and maintained high constant levels of specific antibody secretion. The high ascite forming capacity of the Yel-2 hybridoma provided decreasing of the cell dose administered to the mice from 10(7) to 10(4) cells per mouse.