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Biomedical subjects

R Edwards

Publications and source records attributed to R Edwards.

At least 343 records · Page 19Linked to original sources
PubMed1981

Proteolytic activities of a rumen bacterium, Bacteroides ruminicola R8/4.

Proteolysis of leaf Fraction 1 protein, casein, azocasein and bovine serum albumin by the cell-associated proteinases of the rumen bacterium Bacteroides ruminicola R8/4 was investigated and the kinetic parameters Vmax and Km were evaluated for each substrate. A variety of proteinase inhibitors was used to show that the proteolytic activity comprises a mixture of at least three different classes of proteinase. With respect to substrate specificity and some inhibition characteristics, the proteolytic activity of B. ruminicola R8/4 was similar to that of rumen contents.

Animals↗
PubMed1981

Nature of urate transport in isolated rabbit proximal tubules.

Unidirectional fluxes of [14C]-urate from bath to lumen and from lumen to bath were measured in isolated perfused rabbit proximal tubules. The absorption of urate from the perfusate was small in magnitude and relatively insensitive to alteration by luminal probenecid or D-glucose. By contrast, peritubular probenecid inhibited urate secretion from bath to lumen in all three segments. To estimate the facilitated component of urate secretion for each bath concentration of the anion, the passive component of urate influx (probenecid-resistant influx) was subtracted from the total influx of urate. Urate secretion was strongly dependent on concentration of urate in the bath, the relationship being sigmoidal in many S1 and S2 segments. The S0.5 values of 187,251, and 234 X 10(-6) M obtained from Hill plots of mean data from S1, S2, S3 segments, respectively, indicated that the secretory mechanism had a relatively uniform affinity for urate along the proximal tubule. Vmax values for urate secretion were 568,592, and 55 X 10(-15) mol . min-1 . mm-1 for the same segments. Kinetic analysis indicated that axial heterogeneity of urate secretion is probably due to differences in the relative densities of urate transporters of common affinity along the proximal tubule. We suggest that in intact rabbits with low plasma levels urinary urate is the product of glomerular filtration, passive reabsorption, and minimal proximal secretion. With elevation of plasma urate above endogenous levels, S1 and S2 segments secrete urate at an accelerated rate, possibly reflecting action of a transporter with allosteric features.

Animals↗
PubMed1980

Alcohol abuse, anaesthesia, and intensive care.

The biochemistry, pharmaco-kinetics, and pathophysiology of alcohol and alcoholism are reviewed and approaches to the clinical management of coma, alcohol withdrawal, and anaesthesin are considered.

Adult↗
PubMed1980

Drug use among adolescents of five Southwestern Native American tribes.

Drug use by Native American adolescents from five Southwestern tribes is compared with a large national sample. Native Americans show higher use of alcohol, marijuana, and inhalants from the 7th through the 12th grade. They show lower use of barbiturates. Peyote may be seen as less dangerous than LSD. There are no significant differences for other drugs. Cultural characteristics that may inlfuence potential danger from drug use and intervention strategies are noted.

Adolescent↗
PubMed1979

A sensitive and specific assay for 5-methoxytryptophol in plasma.

5-Methoxytryptophol (ML) is found in the pineal gland and is known to have biological activity especially as an antigonadotrophic agent, but methods have been lacking for its measurement in the circulation. A gas chromatography-mass spectrometry assay using a trimethylsilyl derivative has been developed for the routine measurement of ML in plasma. The assay is of great specificity and has a sensitivity of 20 pmol/l. Studies on the levels of pineal indoles in the circulation, however, have been hampered by the possibility that extraneous compounds are being cross-measured. Thus the specificity of the routine assay has been further validated by comparing it with an alternative assay system where all the major parameters were changed, i.e. derivatizing reagent, internal standard and mass number. Results that were obtained using both assay systems were closely comparable.

Chromatography, Gas↗
PubMed1979

Drug use among native American young adults.

Young adult Native American students at a postsecondary educational institute showed a very high level of use of all drugs when compared with other samples of college age youth. Alcohol, marijuana, and amphetamines were drugs of choice: 31% had tried inhalants although there was little present use; 10% were involved in a drug subculture, using multiple drugs relatively heavily. The authors' interpretation of these findings is either the institution attracts drug users or young Native Americans from relatively isolated environments have higher susceptibility to drugs when they enter an urban (nonreservation) culture.

Adolescent↗
PubMed1978

Serum enzyme levels during experimental hypothermia in man.

Deep surgical and accidental hypothermia cause elevations in serum enzyme levels, probably because of ultrastructural cell damage. Many variables hinder work on this problem in the clinical situation and the mechanism is obscure. Accordingly, enzymes and other physiological parameters were monitored in four subjects cooled four times, under controlled conditions in the laboratory, to a mean auditory canal temperature of 35.0 degrees C. Mild hypovolaemia and acidosis is occurred. Serum enzyme levels did not change significantly and it is concluded that elevations due to hypothermia cannot be studied in laboratory experiments on healthy volunteers who can only safely be cooled to 35 degrees C.

Adult↗