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Biomedical subjects

D R Williams

Publications and source records attributed to D R Williams.

At least 253 records · Page 14Linked to original sources
PubMed1982

Hetastarch as a prime for cardiopulmonary bypass.

Hetastarch, a synthetic colloid osmotic plasma volume expander, was employed in a prime for cardiopulmonary bypass in 37 patients undergoing myocardial revascularization. Comparison of laboratory values to those of 42 patients undergoing myocardial revascularization using an albumin-containing prime showed lower postoperative platelet counts (p less than 0.02) with hetastarch. There were no differences in chest tube drainage, blood use, plasma hemoglobin, fibrinogen levels, of coagulation times. The hetastarch prime cost $119.50 per patient, whereas the albumin-containing prime cost $321.35 per patient.

Aged↗
PubMed1982

Pulmonary circulation of the llama at high and low altitudes.

We have studied the pulmonary circulation of three closely related animals, the llama, alpaca, and guanaco. The mean pulmonary arterial pressure of 12 llamas and one alpaca indigenous to high altitude in the Andes was found to be slightly but significantly higher than that of three llamas and three guanacos born and bred at low altitude in England. On the other hand, the medial thickness of the muscular pulmonary arteries and the relative weights of the two ventricles were the same in three llamas and one alpaca at high altitude as they were in one llama and two guanacos at low altitude. It is concluded that the pulmonary vasoconstrictive response to hypoxia, while present, is greatly reduced in this species and it is suggested that this may have taken place by evolutionary adaptation.

Altitude↗
PubMed1981

Metal binding by pharmaceuticals. Part 1. Copper(II) and zinc(II) interactions following ethambutol administration.

Formation constants for copper(II) and zinc(II) complexes of dextro-2,2'-(ethylenediimino)-di-1-butanol (ethambutol) and its metabolic oxidation product, 2,2'-(ethylenediimino)-dibutyric acid (EDBA) have been measured potentiometrically at 37 degrees C, I = 0.15 mol dm-3 [NaCl]. The constants are used in computer models to assess the extent of the formation of these complexes in vivo. These simulations indicate that whereas ethambutol forms metal complexes only to a limited extent in vivo, EDBA competes effectively under physiological conditions for copper(II) and zinc(II). This study suggests that zinc(II) binding by EDBA may account for a number of side effects of ethambutol treatment.

Chelating Agents↗
PubMed1981

Foveal tritanopia.

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Adaptation, Ocular↗
PubMed1981

Observations on the occurrence of Salmonella cholerae-suis and other salmonellas in two herds of feeder pigs.

Modified brilliant green agar (BGA), Muller-Kauffmann tetrathionate, Rappaport's and selenite F broths were compared for their efficiency in isolating salmonellas from pigs and their excreta. It was concluded that BGA and Rappaport's broth were the media of choice. Where searches were made for Salmonella cholerae-suis alone, the use of a trehalose McConkey agar provided a rapid method of differentiating S. cholerae-suis, which does not ferment trehalose, from the majority of other salmonellas, which do ferment trehalose. Casualties were collected from two farms where infection with S. cholerae-suis was endemic. The isolation rates of S. cholerae-suis from different carcase sites were compared in order to determine the relative importance of the salivary, upper respiratory and faecal routes of excretion. S. cholerae-suis was isolated from numerous carcase sites in carriers including the salivary glands, tonsils, trachea and lungs. However, isolations from the nasal passages, mouth, pharynx and gastro-intestinal tract of carriers were either infrequent or absent. When, in a further study, S. cholerae-suis was isolated from only 3/414 faeces, 1/170 nasal swabs and not at all from 170 oral swabs taken from live pigs, it was concluded that there must be more significant modes of transmission than from the salivary glands, upper respiratory or gastro-intestinal tracts. Cannibalism was considered to be a possibility. In contrast to S. cholerae-suis, other salmonellas were frequently isolated from randomly collected faeces and from the gastro-intestinal tract as well as other sites in casualties.

Animals↗
PubMed1981

Peptidohydrolases of Soybean Root Nodules : IDENTIFICATION, SEPARATION, AND PARTIAL CHARACTERIZATION OF ENZYMES FROM BACTEROID-FREE EXTRACTS.

Nodule extracts prepared from Glycine max var Woodworth possessed endopeptidase, aminopeptidase, and carboxypeptidase activities. Three distinct endopeptidase activities could be resolved by disc-gel electrophoresis at pH 8.8. According to their order of increasing electrophoretic mobility, the first of these enzymes hydrolyzed azocasein and n-benzoyl-l-Leu-beta-naphthylamide, while the second hydrolyzed n-benzoyl-l-Arg-beta-naphthylamine (Bz-l-Arg-betaNA), n-benzoyl-l-Arg-p-nitroanilide (Bz-l-Arg-pNA), and azocasein. The third endopeptidase hydrolyzed Bz-l-Arg-betaNA, Bz-l-Arg-pNA, and hemoglobin. Fractions of these enzymes extracted from electrophoresis gels were shown to have pH optima from 7.5 to 9.8. All of the endopeptidases were completely inhibited by diisopropylphosphorofluoridate, demonstrating that they were serine proteases.Aminopeptidase activity was measured using amino acyl-beta-naphthylamides. Electrophoresis of nodule extracts at pH 6.8 resolved the aminopeptidase activity of nodule extracts into at least four fractions based on mobility and on activities toward amino acyl-beta-naphthylamides. The major activity of two of the aminopeptidases was directed toward l-Leu- and l-Met-beta-naphthylamide, while the other two aminopeptidases exhibited broader specificity and were capable of hydrolyzing a large number of amino acyl-beta-naphthylamides. Two of the aminopeptidases extracted from electrophoresis gels were classified as thiol type enzymes, and all four aminopeptidases had neutral to basic pH optima.

Journal Article↗
PubMed1981

Effect of cigarette smoking on duodenogastric reflux of bile acids.

The possibility that smoking induces duodenogastric reflux was examined in 13 healthy male volunteers. Gastric juice was aspirated for four consecutive 20-minute periods, and reflux quantitated by measuring total bile acids (TBA), chenodeoxycholic acid (CDCA) and glycocholic acid (GCA) in the juice. One cigarette was smoked during either period 2 or period 3. Amounts of bile acids (mumoles: means +/- SEM) refluxing into stomach during the pre-smoking, smoking, and post-smoking periods respectively were: TBA-4.5 +/- 1.1, 5.4 +/- 3.0 and 3.9 +/- 1.6, CDCA-1.7 +/- 0.6, 1.5 +/- 0.9 and 2.0 +/- 1.1; GCA-1.8 +/- 1.1, 1.1 +/- 0.6 and 1.0 +/- 0.6. Paired analysis revealed no significant effect of smoking on any of these parameters. These findings, based on quantitative methods, do not confirm those of previous unblinded and semiquantitative studies. We conclude that smoking one cigarette does not provoke duodenogastric reflux.

Adolescent↗
PubMed1981

Serum lecithin: cholesterol acyltransferase activity in the bile duct-ligated rat.

Serum lipoprotein cholesterol concentration, lecithin: cholesterol acyltransferase (LCAT) activity and lipoprotein X (LP-X) were studied after acute cholestasis had been produced by ligation of the common bile duct in rats fed a liquid fat-free diet. The concentration of serum-free cholesterol, predominantly contained in the low density lipoprotein fraction, increased steadily up to 72 h after ligation. The concentration of cholesterol in the high density lipoprotein fraction did not change significantly, and similarly the serum concentration of esterified cholesterol was not altered. The activity of LCAT, expressed in molar terms as millimoles of cholesterol esterified per litre per hour, did not change during the 72-hour study period. These data indicate acute cholestasis in the rat does not result in a LCAT deficiency and suggest that the accumulation of serum-free cholesterol in this situation is independent of the serum cholesterol-esterifying mechanism.

Acute Disease↗