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Biomedical subjects

D Phillips

Publications and source records attributed to D Phillips.

At least 199 records · Page 11Linked to original sources
PubMed1983

Patterns of mortality in homes for the elderly.

High rates of mortality are an abiding feature of homes for the elderly. Almost a fifth (19.2%) of a cohort of 6947 residents died in the 12 months following initial assessment. Survival rates vary widely, however, for different groups within the residential population. Using data from a longitudinal study of 175 homes for the elderly, this paper examines the relationship between mortality, age, length of stay, and dependency. The interaction between these variables within the residential setting helps to identify the 'high risk' groups of residents who require special surveillance and care.

Activities of Daily Living↗
PubMed1983

Endogenous protein carboxyl methylation in hamster spermatozoa: changes associated with capacitation in vitro.

Protein carboxyl methylase (PCM) and its substrate(s), methyl acceptor protein(s) (MAP), are present in the spermatozoa of rat, rabbit and man. In the present study, PCM activity and MAP capacity were measured in homogenates of hamster testes and isolated spermatozoa, and found to be similar to those of other species. Using solubilized preparations of spermatozoa from the cauda epididymis of hamster, PCM activity was twice as high in sperm tails as in heads while the reverse was true for MAP capacity. Since in this and in previous studies this enzyme reaction has been measured in broken cells, we thought it pertinent to measure methylation under physiological conditions (i.e., in motile spermatozoa). To accomplish this, an assay was developed which depends upon the conversion of [3H-methyl]methionine to S-adenoxyl-L [methyl-3H]methionine which, in turn, serves as a methyl donor for PCM. In sperm that had been labelled with [3H]methionine the MAP for the endogenous methylation reaction was not solubilized with Triton X-100, and was found primarily in sperm tails. When hamster spermatozoa were incubated in medium containing taurine, epinephrine and bovine serum albumin to induce capacitation, endogenous methylation was stimulated 8- to 9-fold; when taurine was omitted from this medium, methylation was stimulated 14-fold. Taurine, however, was essential for in vitro fertilization as the number of eggs fertilized declined from 92% in complete medium to 0% in medium minus taurine. The decrease in fertilization rate was also associated with a decrease in sperm motility. In previous studies we have demonstrated an association between PCM and sperm motility, and have suggested that this enzyme system could be involved in other functions such as the acrosome reaction. From the results in the present study we conclude that the conditions that lead to capacitation in vitro are associated with a marked change in endogenous protein carboxyl methylation.

Animals↗
PubMed1983

Corticosteroid modulation of the renin system and blood pressure in the spontaneously hypertensive rat.

This study examines the role of gluco- and mineralcorticoids in the regulation of the renin-angiotensin system and blood pressure in the spontaneously hypertensive rat (SHR). Effects of adrenalectomy and selective treatment with either aldosterone (30 micrograms/kg/day) or dexamethasone (60 micrograms/kg/day) on plasma renin substrate, active renin (PRA), total renin and blood pressure were studied in 10 week old SHR and control WKY rats. Systolic blood pressure was moderately lower in adrenalectomized rats (129 +/- 2 mm Hg vs 137 +/- 4 mm Hg in control WKY and 145 +/- 4 mm Hg vs 160 +/- 3 mm Hg in control SHR) but could be restored to the control range by aldosterone. Dexamethasone repletion induced substantial increments of systolic blood pressure to comparable levels in both species (202 +/- 8 mm Hg in WKY and 192 +/- 6 mm Hg in SHR). Renin substrate was markedly lower in adrenalectomized, saline repleted rats. This could be reversed by dexamethasone in both species and by aldosterone in WKY rats only. Both PRA and total renin were higher (p less than 0.01) in the adrenalectomized, saline repleted state. This increase was not observed in aldosterone repleted rats. However, dexamethasone inhibited the adrenalectomy associated increase of PRA and total renin in SHR but not in WKY rats. Differences in blood pressure between SHR and WKY persist even in adrenalectomized state despite comparable stimulation of the renin system. Conversely, while blood pressure of both species responds similarly to selective corticosteroids therapy, the response of the renin-angiotensin system in SHR and WKY rats is distinct. Therefore factors other than the adrenal gland and the renin system must be involved in the determination of the high blood pressure in SHR.

Adrenal Cortex Hormones↗
PubMed1982

Effect of metoclopramide and domperidone on aldosterone, 18-hydroxycorticosterone and prolactin secretion in the rhesus monkey.

This study was designed to investigate dopaminergic mechanisms in the control of corticosteroid secretion. Eight rhesus monkeys received metoclopramide (200 micrograms/kg) or domperidone (200 and 400 micrograms/kg) with 5% dextrose (vehicle), or with dopamine (4 micrograms/kg/min) infusions begun 60 min before administration of the dopamine antagonist. Metoclopramide, in the presence of vehicle, increased plasma aldosterone concentrations from 4.8 +/- 0.6 ng/dl to a maximum of 36 +/- 4.7 ng/dl and PRL concentrations from 7.6 +/- 1.1 ng/ml to a maximum of 120.5 +/- 8.0 ng/ml. Administration of metoclopramide resulted in a rise in plasma 18-hydroxycorticosterone from 10.2 +/- 1.3 ng/dl to a maximum concentration of 49.6 +/- 4.5 ng/dl. Plasma concentrations of electrolytes, PRA, plasma cortisol, 11-deoxycorticosterone, corticosterone, 18-hydroxy-11-deoxocorticosterone, were not altered by metoclopramide. Domperidone, in both doses, markedly increased plasma PRL concentrations but had no effect on plasma 18-OHB or aldosterone concentrations. Dopamine infusion inhibited the aldosterone response to metoclopramide and the prolactin response to metoclopramide and domperidone. The results of this investigation demonstrate that aldosterone responses to metoclopramide and prolactin responses to metoclopramide and domperidone are mediated by their antagonist activity at dopamine receptors.

18-Hydroxycorticosterone↗
PubMed1982

Sucrose polyester and covert caloric dilution.

Total daily caloric intake was measured in 10 obese subjects when sucrose polyester (SPE), a nonabsorbable synthetic fat, covertly replaced conventional fats in a single crossover study consisting of three periods: a period of 7 to 14 days to determine baseline caloric intake and two 20-day study periods. An average of 60 g SPE/day replaced conventional fat in one of the two study periods. During both study periods, 60% of the base line caloric intake was "required intake" at mealtime; an additional 60% of base line caloric intake was allowed as "free choice" foods at a specified snacktime. It was thus possible during both study periods to consume more than 100% of the base line caloric intake. In the SPE study period, 40 g SPE replaced 40 g conventional fat for every 1200 kcal of required intake, resulting in a 30% reduction in mealtime caloric intake. Mean total caloric intake (meal and snack) fell 23% during the SPE period (p less than 0.05), despite an average daily weight loss of 0.18 kg. Snack caloric intake did not increase significantly to compensate for caloric dilution of the meals during the SPE period. These results indicate that the obese may not detect or may not compensate for covert dilution of fat calories with SPE. In addition, during the SPE period, there was a 10% reduction in total plasma cholesterol, a 14% reduction in low-density lipoprotein cholesterol, and a 10% reduction in triglyceride concentration. Thus, fat replacement with SPE may benefit weight reduction regimens in obese subjects by facilitating decreased caloric intake and by improving the circulating lipoprotein profile as well.

Adult↗
PubMed1981

Time-resolved emission spectroscopy of the dansyl fluorescence probe.

Using a cavity-dumped laser system as the light source, we have recorded time-resolved fluorescence spectra for the dansyl group in a variety of systems. The fluorescence spectrum of dansylphosphatidylethanolamine incorporated into a variety of lipid bilayer systems at ambient temperatures shows very marked time dependence, with red shifts of up to 40 nm over a 40-ns period. Similarly, large red shifts are observed for dansylamide in 1-butanol at low temperatures, which can be tentatively attributed to the initial rapid formation of an intramolecular charge transfer state, followed by reorientation of the polar solvent molecules. The time-resolved behavior in the lipid bilayer system can, by comparison, also be at least partly explained by solvent reorientation, but the possibility of heterogeneity of the binding site must also be considered. The complex time dependence of the fluorescence of the dansyl group in these lipid bilayer systems considerably complicates the interpretation of fluorescence quenching and fluorescence energy transfer experiments.

Cholesterol↗
PubMed1981

On the three-dimensional structure and catalytic mechanism of triose phosphate isomerase.

Triose phosphate isomerase is a dimeric enzyme of molecular mass 56 000 which catalyses the interconversion of dihydroxyacetone phosphate (DHAP) and D-glyceraldehyde-3-phosphate. The crystal structure of the enzyme from chicken muscle has been determined at a resolution of 2.5 A, and an independent determination of the structure of the yeast enzyme has just been completed at 3 A resolution. The conformation of the polypeptide chain is essentially identical in the two structures, and consists of an inner cylinder of eight strands of parallel beta-pleated sheet, with mostly helical segments connecting each strand. The active site is a pocket containing glutamic acid 165, which is believed to act as a base in the reaction. Crystallographic studies of the binding of DHAP to both the chicken and the yeast enzymes reveal a common mode of binding and suggest a mechanisms for catalysis involving polarization of the substrate carbonyl group.

Animals↗
PubMed1981

Importance of noninvasive ultrasonic-Doppler testing in the evaluation of patients with symptomatic carotid bruits.

An ultrasonic Duplex scanner was used to estimate the site and degree of extracranial arterial disease in two groups of patients with asymptomatic bruits. In the first 100 patients only the extent of disease was assessed with 37% of the sides with bruits having high-grade stenoses (greater than 50% diameter reduction) and one-half having lesions which narrowed the internal carotid artery by less than 50%. Seven percent were found to be normal. The remaining 6% had occlusion of the internal carotid artery. In a second group of 81 patients, the effect of the reported findings of the Duplex scan on patient management was reviewed. Only 13 patients underwent angiography and 11 of these were in patients with high-grade stenoses. Five carotid endarterectomies were performed and in each case, the patient had bilateral high-grade lesions. The implications of this diagnostic approach are discussed as well as the need for prospective studies of patients who present with an asymptomatic bruit.

Arteriosclerosis↗
PubMed1980

Angiographic evaluation of post-sternotomy arteriovenous fistula of the internal mammary artery and vein.

An arteriovenous fistula of the right internal mammary artery and vein following median sternotomy was demonstrated by angiography. This surgical complication has not been previously reported in the literature, despite the recent increase in cardiac surgery via median sternotomy. Clinical and radiologic awareness of this iatrogenic shunt and of its potential delayed appearance and cardiovascular effects are important. Arteriovenous fistulas are usually treated by surgical ligation and excision, or by transcatheter occlusion therapy.

Aged↗
PubMed1980

Faces, vases, subjective contours, and the McCollough effect.

A version of the face-vase pattern was constructed with the use of subject contours. The McCollough effect was viewed on this pattern and it was found that perceptual alteration (face to vase) does not weaken the strength of the effect's hues while a complete perceptual rearrangement (faces/vases to concentric rectangles) does.

Accommodation, Ocular↗