[Determination of nystatin component composition using HPLC and TLC with densitometry].

The component composition of nystatin produced by an improved strain of Streptomyces noursei was determined by HPLC on Milichrom chromatograph (USSR). It was shown that the antibiotic consisted of nystatins A1, A2, A3 and B and admixture substances. The data appeared to be in good agreement with the results of the complex TLC investigation, by using densitometry.

[A comparative study of the oxidation processes in the cells of typical forms and L forms of Vibrio cholerae].

A comparative study of metabolic processes in cells of typical forms and L-forms of cholera vibrios has determined a change in the intensity of oxidative processes demonstrated through a decrease in the activity of respiration enzymes (dehydrogenases and diaphorases) and through a restricted transport of electrons along the respiration chain. The facts established evidence for the transition of L-transformed cells into a physiological state with a deficit of substrates and energy as well as with retarded processes of vital activity and repressed mechanisms of reparation of structural elements of a cell.

[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.

[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.

[Effect of the extraction methods and drug form components on the determination of gramicidin C in buccal tablets].

The effect of solvents, extraction procedures and separate components of the troche mass on the results of biological activity determination of gramicidin S with the agar-diffusion method was studied. It was found that irrespective of the solvent and the number of extractions only 76--81 per cent of the antibiotic were determined in the troches. Fruit essence and sugar had a significant effect on the results of gramicidin S biological activity determination as compared to the other components of the dosage form.

[Effect of the cultivation conditions of Candida species yeast-like fungi on their sensitivity to levorin].

The effect of levorin on yeast-like fungi under (different) cultivation conditions was studied. It was shown that the medium composition and incubation temperature affected the results of determination of the test-culture sensitivity to levorin. There was correlation between the time of the population lag-phase and the critical time of the zone formation and these values depended on the temperature of the test-microbe vegetation.