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Biomedical subjects

E M Bershteĭn

Publications and source records attributed to E M Bershteĭn.

12 recordsLinked to original sources
PubMed1986

[Various ways of standardizing and unifying biological methods of determining the activity of antibiotics].

It was shown possible to use nutrient media containing only salt components and agar-agar for determination of biological activity of tetracyclines (tetracycline, morphocycline, oxytetracycline and chlortetracycline), erythromycin and oleandomycin. A uniform nutrient medium containing ammonium chloride, trisubstituted sodium citrate, disubstituted sodium phosphate and agar-agar was developed. Glucose is added to this medium simultaneously with the test microbe, B. subtilis ATCC 6633. The medium of the above composition provided readily reproducible results.

Anti-Bacterial Agents↗
PubMed1985

[Standardized nutrient medium for determining the biological activity of antibiotics of the aminoglycoside group].

The possibility of the use of nutrient media containing only salt components in addition to agar-agar in determination of the biological activity of aminoglycoside antibiotics was confirmed. The optimal results were obtained on the medium including ammonium acetate, disubstituted sodium phosphate and agar-agar. Glucose was added to the medium simultaneously with the test microbe. The medium is simple by its composition. It provides satisfactory growth of B. subtilis ATCC 6633 as the test microbe and clear inhibition growth zones of sufficient size. The results of the assay of the biological activity of neomycin, monomycin, streptomycin and kanamycin on the medium of this composition were reproducible.

Agar↗
PubMed1985

[Effect of antioxidants and complexons on the stability of the microbiological standard for mycoheptin].

Stability is one of the most important indices of the quality of antibiotic microbiological standards. At present the expiry date of the mycoheptin standard (a specially purified preparation) is 1 year when stored in sealed ampoules in an inert gas at a temperature of -20 degrees C. To prolong the expiry date of the standard the effect of various antiohidants and complexons on its stability was studied with the method of "accelerated aging". Sodium hexametaphosphate and Trilon B were tested as complexing agents and propyl gallate, ionol, N-phenyl-2-napththyl amine, mannitol and their mixtures were tested as antioxidants. The substances were applied in an amount of 3 per cent of the antibiotic weight. The favourable effect of the complexons on mycoheptin stability was shown. Their stabilizing effect was potentiated by addition of certain antioxidants.

Antibiotics, Antineoplastic↗
PubMed1984

[Growth of test microorganisms used in determining antibiotic activity on synthetic nutrient media].

The growth of gram-negative sporulating bacteria and yeast-like fungi used in a microbilogical assay of antibiotic activity was studied on solid synthetic media of simple composition. Their reproduction with the microbial growth of different density was shown to be possible on media containing available and strictly standardized components, such as salts, glucose and disubstituted sodium phosphate. The cultures tested were not similar by their growth requirements.

Anti-Bacterial Agents↗
PubMed1984

[Nutrient medium for determining the biological activity of heliomycin].

It was shown that a nutrient medium containing only salt components except agar-agar could be used for assay of the biological activity of heliomycin. The optimal results were observed on the medium containing ammonium chloride, urea, disubstituted sodium phosphate, glucose and agar-agar. The medium provided satisfactory growth of Bac. subtilis ATCC 6633 as the test culture and formation of clear inhibition growth zones of the sufficient size. The medium is standard and its use allows obtaining reproducible results in assay of the heliomycin biological activity.

Agar↗
PubMed1984

[Spectrophotometric analysis of amphotericin B in technological objects].

The same samples of the fermentation broth and mycelium of the amphotericin B-producing organism, (S. nodosus, strain 258) were assayed with the agar diffusion method and spectrophotometrically. The comparison of the results showed that the spectrophotometric findings did not depent on the wave lengths and the equation type. However, the values of the spectrophotometric assay were higher than those of the biological assay. This was partially due to the presence of a biologically inactive admixture of the heptaenic nature in the semiproducts of amphotericin B. At the same time when the strain, nutrient medium and biosynthetic conditions were stable, the results of the biological and spectrophotometric assays had a linear dependence. This allowed one to suggest equations for spectrophotometric determinations providing results correlating with those of the biological assay.

Agar↗
PubMed1980

[Physicochemical and biological characteristics of mycoheptin components A1 and A2].

Mycoheptin, an original antifungal polyenic antibiotic is a complex of several heptaen components. 2 heptaen components designated as mycoheptins A1 and A2 were isolated from the mycoheptin complex with the counter-current distribution technique in a system of methanol-chloroform-forate buffer, pH 8.3 (2:2:1). It was found that component A2 was the main one. Its content in the preparation is at least 80 per cent. The components were studied comparatively with respect to the elemental composition, UV and IR spectra, distribution coefficients in different solvent systems, specific rotation, biological activity and acute toxicity. Both components are original in the subgroup of "nonaromatic" heptaens. Mycoheptin A1 has a lower biological activity and toxicity but its chemotherapeutic efficiency is higher.

Animals↗
PubMed1977

[Optimization of conditions for determining the activity of amphotericin B].

The effect of incubation temperature, pH and medium composition on the size of the growth inhibitions zones, clearance of their borders and slope of the dose-response curve in determin ation of the biological activity of amphotericin B by the agar-diffusion method using Candida scotti, Tul-1 as the test-microbe was studied. The composition of the medium providing optimal conditions for the activity assay according to the sone size and clearness was developed. When the above medium was used for determination of the biological activity of amphotericin B, the standard deviatioos of the assay results, as well as the average results obtained at an interval of 1 month were 1.5 times lower than with the use of the medium proposed at an interval of 1 month were 1.5 times lower than with the use of the medium proposed in Specification 42 No. 3857-70. At the same time the average results of the assay on both media coincided.

Amphotericin B↗