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Biomedical subjects

P J Wyatt

Publications and source records attributed to P J Wyatt.

14 recordsLinked to original sources
PubMed1978

Laser differential light scattering bioassays for selected antitumor agents.

Bioassay methods for actinomycin D, 6-thioguanine, and adriamycin which utilize laser light scattering from suspensions of drug-sensitive bacteria have been developed. In 3 hours, serum and urine levels of the 3 drugs can be reproducibily measured. A sample volume of 0.1 ml may be assayed with a precision of +/- 10%. The linear response range for actinomycin D was 0.03 to 3.0 microgram/ml. For 6-thioguanine and adriamycin the linear responses range was 0.03 to 10.0 and 0.25 to 10.0 microgram/ml, respectively. Thetively. The present studies further confirm the general utility of differential light scattering as a rapid and inexpensive assay procedure of broad application.

Antineoplastic Agents↗
PubMed1978

Laser light scattering bioassay for 1-beta-D-arabinofuranosylcytosine (ARA-C, NSC-63878).

A bioassay method for the estimation of ara-C in biological samples which utilizes laser light scattering from suspensions of drug-sensitive bacteria has been developed. The species employed in the assay was Streptococcus faecium var. durans resistant to methotrexate and 6-mercaptopurine. In less than four hours, serum and urine levels of ara-C can be reproducibly measured using the method. A sample volume of 0.1 ml containing 30 ng/ml may be assayed with a precision of +/-10 percent. The present studies further confirm the utility of the method as a rapid and relatively inexpensive assay methodology of broad application. Time variations of drug serum levels and urinary excretion rates in dogs are compared via the differential light scattering (DLS) assay, standard disc diffusion assay, and radiosotopic assay. The results obtained by the various methods are in excellent agreement.

Animals↗
PubMed1976

Laser differential light-scattering bioassay for methotrexate (NSC-740).

A new bioassay method utilizing laser light scattering from suspensions of drug-sensitive bacteria has been developed for the estimation of antitumor drugs in biologic samples. Changes in the light-scattering patterns of antibiotic-treated bacteria have recently been shown to provide a rapid and accurate indication of antibiotic sensitivity. Similar considerations for several antitumor drugs have shown the method capable of assaying 0.1 ml with drug concentrations as low as a few nanograms of drug per milliliter of sample. The first successful application of the methodology is described for the antitumor agent methotrexate. Studies of both drug-treated human serum specimens and dog serum levels and urinary excretion as a function of time indicate that assay results are available within 3 hours of preparing the serum. Time variations of drug serum levels and urinary excretion rates are compared via laser differential light-scattering assay, standard disc-diffusion assay, and previously published radioisotopic assays.

Animals↗
PubMed1972

Osmotic sensitivity in Staphylococcus aureux induced by streptomycin.

Differential light-scattering measurements of Staphylococcus aureus cultures were made before and after treatment with streptomycin. Changes were observed in the light-scattering characteristics of streptomycin-treated sensitive cells within 5 min after suspension in a hypotonic solution. No changes were observed with a resistant strain of cells nor with either strain in an isotonic solution. The observed effects occur more slowly when the cells are growing slowly. The physical effects consonant with the changes in the light-scattering curves are a broadening of the cell size distribution, a slight reduction in mean size, and the appearance of clumps or debris. We conclude that streptomycin rapidly alters the selective permeability of the cell membrane and makes the cells susceptible to increased osmotic stresses.

Cell Membrane Permeability↗