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Biomedical subjects

D M Pierce

Publications and source records attributed to D M Pierce.

27 records · Page 2Linked to original sources
PubMed1981

Selection of solvents for thin-layer chromatography by means of a simple ranking system based on dielectric constants.

1. A system devised for ranking t.l.c. solvent mixtures on the basis of their dielectric constants is useful in selecting mixtures for routine t.l.c. 2. For three basic compounds (tiquinamide, meptazinol and ciclazindol) and three acidic compounds (fentiazac, oxaprozin and 5, 6, 7, 8-tetrahydroquinoline-3-carboxylic acid), chromatographed on silica in the unionized state, a good correlation was found between RF and dielectric constant of the eluting solvent mixture.

Chemical Phenomena↗
PubMed1981

Studies on the biotransformation of indoramin in the patas monkey.

1. Studies on absorption, excretion and biotransformation of the antihypertensive agent indoramin (3-[2-(4-benzamidopiperidino)ethyl]indole hydrochloride) have been carried out in patas monkeys. 2. Absorption of the drug was extensive, as indicated by less than 8% of the dose appearing in faeces as the unchanged compound. 3. Approx. 35% of an orally administered dose of the 3H-labelled drug was recovered in urine while a similar amount was found in faeces. Urinary excretion of total 3H was mono-exponential with a half-life of 17 h. 4. Biotransformation was extensive, the unchanged drug constituting less than 4.5% of the urinary metabolites. The principal identified metabolites were a sulphate conjugate of 3-[2-(4-benzamidopiperidine)ethyl]indol-6-ol and an acid-labile conjugate of the parent drug. A minor metabolite resulting from N-dealkylation of the drug was identified as 4-benzamidopiperidine. Small amounts of 3-[2-(4-[4-hydroxybenzamido]piperidino)-ethyl]indole were found in a dichloromethane extract of acid-hydrolysed urine. 5. The faeces contained only negligible amounts of conjugated metabolites. The principal components were the indole-6-hydroxylated derivative of the parent drug with smaller amounts of the 5-hydroxylated compound and the unchanged compound.

Animals↗
PubMed1975

Relationship between monocular and binocular depth acuity.

Estimates of monocular and binocular depth acuity were obtained on two samples of subjects with adequate visual acuity and capacity for stereopsis. Both a method of average error and a modified method of limits were employed to secure the estimates. Eight ratios of binocular to monocular depth acuity ranged from 2.4:1 to 4.2:1 at a distance of 15 ft. The results contradict the familiar generalization that binocular depth perception is about 20 times as acute as monocular depth perception.

Adolescent↗
PubMed1975

Comparability of two methods of estimating real-depth acuity.

The purpose of this study was to determine whether a motor adjustment (method of average error) and a verbal response (method of constant stimuli) procedure would yield comparable estimates of depth acuity using the classic Howard apparatus. The findings were that: (1) thresholds derived from the two procedures were not significantly correlated under either binocular or monocular viewing conditions; (2) essentially equivalent thresholds were derived from the two procedures under the binocular viewing condition; (3) thresholds derived from the verbal procedure were significantly higher than those derived from the motor adjustment procedure under monocular viewing conditions.

Adolescent↗
PubMedDate not supplied

Pharmacokinetics of indoramin and its 6-hydroxylated metabolite after repeated oral dosing.

The pharmacokinetics of indoramin and its active 6-hydroxylated metabolite have been studied in healthy male volunteers after repeated oral dosing with 37.5 mg twice daily for 2 weeks. Plasma concentrations of indoramin accumulated, on average, three to four-fold above those anticipated on the basis of the kinetics after the first dose, though steady state was achieved by the end of the first week and no further increase was observed after 2 weeks. The degree of accumulation was consistent between subjects, with a highly significant (p less than 0.001) correlation between the concentration 2 h after a single dose and the average steady-state concentration. Possible explanations for the accumulation of indoramin are discussed. Plasma concentrations of 6-hydroxyindoramin, in contrast, did not accumulate on multiple dosing. At steady state, concentrations of the metabolite, as represented by the AUC0-8h, were approximately 30-40 per cent of those of the unchanged drug. Since the two compounds are approximately equipotent the metabolite may accounts for 25 per cent of the hypotensive activity of indoramin during a typical clinical regime of 37.5 mg twice daily.

Administration, Oral↗