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Biomedical subjects

W C Buss

Publications and source records attributed to W C Buss.

34 records · Page 2Linked to original sources
PubMed1985

Inhibitory effects of gentamicin and ethacrynic acid on mammalian microsomal protein synthesis.

The ototoxic antibiotic gentamicin, and the ototoxic diuretic ethacrynic acid, both produce inhibitory effects on protein synthesis in microsomes isolated from rat brain. Inhibitory effects appear to be essentially independent of each other. The inhibitory dose-response curve for gentamicin is logarithmic, while that for ethacrynic acid is linear. The dose-response curves make gentamicin the predominant inhibitor when the drugs are combined at low concentrations and ethacrynic acid the predominant inhibitor when the drugs are combined at high concentrations. Accumulation of aminoglycoside by tissues of the inner ear may result in inhibition of protein synthesis in spite of low and transient plasma levels of the drug. Further inhibition of translation by ethacrynic acid could account, in part, for the ototoxic interaction of aminoglycosides and high ceiling diuretics.

Animals↗
PubMed1985

Gentamicin administered in vivo reduces protein synthesis in microsomes subsequently isolated from rat kidneys but not from rat brains.

Gentamicin injected in vivo, in doses equivalent to those used therapeutically in humans, produced a decrease in the protein synthesizing capacity of microsomes subsequently isolated from rat kidneys, but not of microsomes isolated from rat whole brains. The decreases in eukaryotic cell protein synthesis observed following in-vivo administration of gentamicin were similar to those observed following the addition of gentamicin to microsomes in vitro.

Animals↗
PubMed1984

Inhibition of mammalian microsomal protein synthesis by aminoglycoside antibiotics.

The aminoglycoside antibiotics gentamicin, kanamycin and netilmicin produce a dose-dependent inhibition of amino acid incorporation in microsomes isolated from human liver and rat brain, kidney and liver. Inhibitory effects on microsomal protein synthesis occur at concentrations that have been shown to accumulate in rodent and human renal cortex and perilymph following therapeutic administration. Inhibition of translation in those tissues which specifically accumulate aminoglycoside antibiotics may, in part, explain toxicities observed following exposure to aminoglycosides.

Aminoglycosides↗
PubMed1983

Studies on the mechanism of glucocorticoid hormone induced alterations in rat thymic transcription--I. Evidence from reconstituted cross-over transcription assays that sequential increases and decreases in transcription are due to changes in the activity of RNA polymerase II rather than in the activity of chromatin template.

In experiments to determine the mechanism of glucocorticoid induced decreases in thymic transcription, adrenalectomized rats were injected with hydrocortisone (50 mg/kg) or vehicle. Thymic nuclei were used to prepare chromatins and soluble nuclear extracts containing RNA polymerase II for cross-over experiments. With calf thymus DNA or rat thymic chromatins as templates limiting RNA polymerase II from rats treated with hydrocortisone 3 h previously had 130% of the [3H]UMP incorporating activity of RNA polymerase II from control vehicle treated rats. In contrast, limiting RNA polymerase II from rats treated with hydrocortisone 12 h previously had 40-50% of the [3H]UMP incorporating activity of RNA polymerase II from controls. When limiting calf thymus DNA or rat thymic chromatins were used in 12 h cross-over experiments. Individual RNA polymerases II produced equal [3H]UMP incorporations, but RNA polymerase II activity from hydrocortisone treated rats was again only 50% of control values. Thus with template saturation, RNA polymerase II from hydrocortisone treated rats could not transcribe rat thymic chromatin templates to the level achieved by RNA polymerase II from control rats. This suggests that the activity, rather than the amount, of RNA polymerase II from hydrocortisone treated rats is reduced. Double reciprocal plots of [3H]UMP incorporation on rat chromatins with increasing concentrations of RNA polymerases II were made at 12 h. The apparent Km for RNA polymerase II from animals treated with hydrocortisone was identical to that of RNA polymerase II from controls, but the Vmax of RNA polymerase II from hydrocortisone treated animals was reduced. These data suggest the presence of an inhibitor of transcription or an RNA polymerase II defective in its capacity to initiate and/or elongate RNA transcripts. Further experiments demonstrated that these effects were not due to steroid induced changes in ribonuclease or protease activities.

Animals↗
PubMed1978

Rifampicin inhibition of protein synthesis in mammalian cells.

Rifampicin produces a dose-dependent decrease in protein synthesis in rat thymocytes. At concentrations up to 200 micrograms per milliliter, rifampicin does not alter rat thymic transcription. Rifampicin causes a direct inhibition of protein synthesis in rat thymic and hepatic microsomes, and in cadaveric human hepatic microsomes. Protein synthesis inhibition could explain the toxicity of rifampicin in man.

Animals↗
PubMed1977

The 105mm camera as a supplement to nuclear venography.

Nuclear venograms were supplemented by contrast venograms with use of a 105mm spot film camera under direct visualization. This technique is a simple effective way of resolving questionable areas observed on nuclear venograms.

Leg↗
PubMed1977

Metal ion catalyzed oxidation of the antibiotic rifampicin.

The metal ions Cu++, Mn++ and Co+++, but not Ca++, Fe+++, K+, La+++, Mg++, Na+, Sr++ or Zn++ catalyzed the oxidation of rifampicin from the naphthohydroquinone to the naphthoquinone form. This reaction was pH dependent, and occurred at neutral or basic pH more rapidly than at acidic pH. Mn++ catalyzed the most rapid oxidation, followed by Cu++ and then Co+++. Rifampicin oxidation was metal ion dependent and complete oxidation occurred at metal ion concentrations below stoichiometric values. Initial rate studies suggest that the oxidation mechanism is complex.

Catalysis↗