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Biomedical subjects

R F Cosgrove

Publications and source records attributed to R F Cosgrove.

9 recordsLinked to original sources
PubMed1979

The application of cryobiology to the microbiological assay of nystatin.

Improvements in the reproducibility of nystatin agar diffusion assays have been achieved by the use of liquid nitrogen stored inocula and deep frozen standard stock solutions. The overall percentage variability of the assay has been reduced from over 5% with daily prepared standards and inocula to around 1% with a frozen inocula and to 0.6% with a combination of frozen inocula and standards. The implications of these improvements in the standardization of nystatin assays, and microbiological assays generally are discussed.

Biological Assay↗
PubMed1979

A comparative study of the microbiological assays currently available for nystatin raw material.

The classical agar diffusion and turbidimetric methods of assay for nystatin are compared with the more recently documented assays for this antibiotic which depend upon physicochemical measurement of the response of micro-organisms. Liquid nitrogen stored inocula were used throughout. It is concluded that the newer methods of assay are as reproducible and reliable as the agar diffusion and turbidimetric methods and that they are generally more sensitive. The choice between the assay methods compared can thus be based on speed, cost and sample through-put.

Biological Assay↗
PubMed1979

Long-term storage of microorganisms used in antimicrobial effectiveness tests.

Liquid nitrogen storage of organisms designated in the U.S. Pharmacopeia (XIX) for the assessment of antimicrobial effectiveness is described. By use of simple apparatus and procedures, 85-95% viabilities of pre-frozen cells are attained immediately upon freezing. Viability levels have remained constant over a 3-year period and the use of such inocula has considerably improved the reliability of the test. The superiority of liquid nitrogen storage for microbial test inocular over other types of storage is discussed.

Bacteria↗
PubMed1978

In vitro activity of chlorhydroxyquinoline against mycoplasma species.

The in vitro activities of 5-chloro-8-hydroxyquinoline (CHQ) against single strains of 12 different species of mycoplasma and the impacts of repeated exposure of these strains to CHQ on their susceptibility to this agent have been studied. On initial exposure, the minimal inhibitory concentrations for these strains ranged from 0.24 to 1.92 micrograms of CHQ per ml of test medium; activities remained unchanged during 10 serial transfers in CHQ-containing medium.

Chloroquinolinols↗
PubMed1978

In vitro studies of amphotericin B in combination with the imidazole antifungal compounds clotrimazole and miconazole.

The clinically important polyene antibiotic amphotericin B, in combination with two antifungal imidazole compounds, clotrimazole and miconazole, was studied in vitro. With use of results of cytoplasmic leakage, metabolic heat output, and minimal inhibitory concentration studies, a definite antagonistic response was demonstrated. It is suggested that, if combined antifungal drug therapy is clinically indicated, the drug combination be tested against the isolate by the simple technique of measuring cytoplasmic leakage or by the more elaborate method of flow microcalorimetry.

Adsorption↗
PubMed1977

Bioassay method for polyene antibiotics based on the measurement of rubidium efflux from rubidium-loaded yeast cells.

A bioassay method for the polyene antibiotics nystatin and amphotericin B is proposed based on the measurement of the efflux of rubidium ions from a rubidium-loaded yeast culture challenged with the antibiotics. For this purpose a major proportion of the intracellular K(+) ions in a Saccharomyces cerevisiae culture has been substituted by Rb(+) ions. The rubidium leakage is measured by atomic absorption spectrophotometry, and a straight-line, dose-response correlation has been obtained for both antibiotics.

Amphotericin B↗