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Biomedical subjects

W S Richardson

Publications and source records attributed to W S Richardson.

14 recordsLinked to original sources
PubMed1994

Erythromycin-induced QT prolongation and polymorphic ventricular tachycardia (torsades de pointes): case report and review.

Although uncommon, ventricular arrhythmias associated with erythromycin use have been reported previously, usually in the presence of heart disease and/or situations causing abnormal cardiac electrophysiology (such as bradycardia, hypokalemia, and the administration of other cardioactive drugs). We report a case of QT prolongation and polymorphic ventricular tachycardia (torsades de pointes) that was precipitated by the intravenous administration of erythromycin. In contrast to most other previously described patients, our patient did not demonstrate significant heart disease or other apparent factors contributing to the genesis of the arrhythmia.

Adult↗
PubMed1993

Considerations of acidifying water samples for 99Tc analysis.

Environmental water samples are routinely acidified before radionuclide analysis to prevent adsorption of radionuclides on the container walls. This study addresses the concern for volatilizing 99Tc from acid solutions during evaporation before beta analysis has been addressed. Water samples can be acidified to pH 1.7 with nitric acid and evaporated to dryness on planchets without significant losses of technetium due to volatilization. However, the planchets should not be flamed unless a detergent is used, and control samples should be flamed to determine the loss of activity under the conditions used.

Environmental Pollutants↗
PubMed1985

Early clinical signs identify low-risk patients with acute upper gastrointestinal hemorrhage.

Early identification of patients at low risk for poor outcome after acute upper gastrointestinal hemorrhage would allow reduction of diagnostic and therapeutic interventions. We identified six early predictors of good outcome: age less than 75 years, no unstable comorbid illness, no ascites found on physical examination, normal prothrombin time, and, within an hour after presentation, systolic blood pressure of 100 mm Hg or greater and nasogastric aspirate free of fresh blood. Presence of all six predictors defined the low-risk population. Among 162 patients in the development and retrospective validation phases of our study, all 74 low-risk patients had good outcomes. A prospective validation study of 111 patients further established the accuracy of our predictive method; only two of 52 low-risk patients had poor outcomes. Application of our method should allow more selective management of patients with acute upper gastrointestinal hemorrhage.

Acute Disease↗
PubMed1979

Dentin proteins: chemistry, structure and biosynthesis.

One of the most abundant noncollagenous proteins of dentin is a phosphoprotein rich in aspartic acid and phosphoserine. This protein occurs in soluble and inextractable forms, the latter being associated with the insoluble collagenous matrix. This protein is capable of tightly binding a relatively high level of calcium. Biosynthetic and radioautographic data suggest that shortly after its biosynthesis, the phosphoprotein is transported and bound to the collagen at the predentin-dentin junction. This event is probably central to the mineralization process, though other glycoproteins may be involved.

Amino Acids↗
PubMed1977

Phosphoprotein from dentin. New approaches to achieve and assess purity.

Phosphorprotein extracted from rat incisors was purified by passage through a sulfonated polystyrene column. The phosphoprotein that emerged in the void volume contained 54% phosphoserine + serine and 36% aspartic acid and, in contrast to that obtained by DEAE-cellulose chromatography, was devoid of proline, valine, isoleucine, leucine, tyrosine, phenylalanine and arginine. Gel electrophoresis of the material purified on sulfonated polystyrene columns gave one major phosphate-containing band which would not stain with Coomassie Blue. EDTA or acetic acid demineralization yielded phosphoprotein preparations with identical compositions and electrophoretic properties. These data show that purification procedures reported earlier are insufficient.

Amino Acids↗
PubMed1977

The phosphoprotein of rabbit in cisors.

The phosphoprotein of continually erupting rabbit incisors was extracted from decalcified teeth and purified by gel filtration and ion-exchange chromatography. Chemical characterization revealed that its composition was very similar to that of rat incisor and bovine molar phosphoproteins. The presence of similar acidic proteins in the dentin of various mammals is consistent with the suggestion that they are involved in the mineralization process.

Amino Acids↗
PubMed1976

Purification and some properties of the phosphoprotein from rat incisors.

The phosphoprotein of rat incisors has been purified by successive gel and ion-exchange chromatography. The product gave a single band on polyacrylamide gel electrophoresis and contained approximately 34% phosphoserine and 32% aspartic acid. Alkaline elimination experiments showed all the phosphate to be present as phosphoserine. Ultraviolet spectra in the presence or absence of ATP showed that the phosphoprotein did not contain an nucleotide moiety as suggested by Veis, A., Spector, A. R. and Zamoscianyk, H. ((1972) Biochim. Biophys. Acta 257, 404-413) for bovine dentin phosphoprotein.

Amino Acids↗