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Biomedical subjects

R A Ward

Publications and source records attributed to R A Ward.

At least 91 records · Page 5Linked to original sources
PubMed1983

Community access and satisfaction: racial differences in later life.

Community access can be expected to have an important influence on the life satisfaction of the aged because of age-linked restrictions in social life space. Such access may be less important for older blacks, however, as a consequence of lifelong "ghettoization". These hypotheses are tested using national survey data. Community mobility is found to have a stronger association with life satisfaction for older whites, while having only an indirect effect through social interaction for older blacks. Directions for future research are suggested.

Aged↗
PubMed1983

[Long-term effects of acid-base equilibrium of bicarbonate dialysis].

The acid-base effects of long-term bicarbonate hemodialysis (BDH) were evaluated in five patients previously stabilized on acetate hemodialysis (AHD). Following 12 weeks on BHD, the patients were studied an additional 6 weeks on return to AHD. Hydrogen ion generation rate (calculated from urea generation rate), and pre- and post-dialysis pH, and blood gases were measured every 2 weeks. The results of the study show that, while pre-dialysis blood bicarbonate and pH did not change significantly during the stabilization period, during BHD, and following return to AHD, hydrogen ion generation rate increased substantially on the average during BHD (+6 mmol/24 h) and fell precipitously on return to AHD (-9 mmol/24 h). Pre- to post-dialysis changes in blood bicarbonate, and pH were significantly greater during BDH than during AHD. We conclude that the increase in hydrogen ion generation rate during BDH indicates that the patients increased their intake of fixed acid. Because of extreme increases observed intra-dialytically in blood bicarbonate and pH during BHD, the ability to vary bicarbonate delivery to the patient may have to be an integral part of equipment used in BDH.

Acid-Base Equilibrium↗
PubMed1982

African sleeping sickness: new evidence that mature tsetse flies (Glossina morsitans) can become potent vectors.

Starved mature male tsetse flies (21 to 25 days old) are capable of developing salivary gland (SG) infections of Trypanosoma brucei rhodesiense at rates nearly comparable to teneral males less than 24 hours old when given an infective meal containing parasites, horse red cells and culture medium. Although the over-all SG infection rate for mature males starved for three, four or five days before infection was about half that for teneral males less than 48 hours old (8.0% v. 15.6%), males starved for four days developed infection rates (12.3%) that were comparable to those of teneral flies less than 24 hours old (11.8%). It is suggested that the acquisition of infection by mature flies should be considered when evaluating factors contributing either to maintenance of endemic infections or perhaps even epidemic infections of human sleeping sickness.

Animals↗
PubMed1982

Acid-base and metabolic responses to anion infusion in the anesthetized dog.

This study evaluated the acid-base and metabolic effects of several organic anions which might have application in the correction of metabolic acidosis during hemodialysis. Anesthetized dogs were infused intravenously with the sodium salts of either chloride, bicarbonate, acetate, lactate, or pyruvate. Acetate perturbated metabolism more than any of the other organic anions infused. These perturbations included hypoxemia, reductions in serum potassium and phosphorus, a decrease in plasma, glucose, and increases in intermediary metabolites such as lactate, acetoacetate and beta-hydroxybutyrate. Transferance of our findings to hemodialysis suggests that acetate would compromise the ability of dialysis to reduce body burdens of potassium and phosphorus and provide proper base repletion. Pyruvate would appear superior to acetate as a base substitute by virtue of its lesser effects on oxygen consumption and electrolyte distribution and its capacity to produce glucose. However, the significant production of lactate with pyruvate infusion, coupled with diffusive losses of bicarbonate during dialysis and the possible instability of pyruvate in solution, would still hinder proper base repletion. Bicarbonate generation with lactate infusion was too slow to provide a practical alternative for base repletion in hemodialysis. Bicarbonate infusion caused minimal alterations in intermediary metabolism. This, in conjunction with obviating diffusive losses, suggests the use of bicarbonate would allow more appropriate base repletion during hemodialysis.

Acetates↗
PubMed1982

Utilization of bicarbonate for base repletion in hemodialysis.

Because of physiochemical considerations, acetate rather than bicarbonate has traditionally been used as the base repletion agent in dialysate. There are major differences in the mechanisms through which these agents neutralize the body's acid load in the circumstance of dialysis. Acetate dialysis relies on metabolism of acetate to generate bicarbonate. Loss of bicarbonate into the dialysate requires that acetate dialysis supply base far in excess of that required to buffer metabolic hydrogen ion generation alone. Consequently, net accrual of base is difficult to quantitate and may be inadequate to neutralize the excess hydrogen ion, leading to chronic buffer depletion. However, acute acid-base problems are usually avoided because of the indirect nature of base addition. In contrast, net base accrual with bicarbonate dialysis occurs in a direct and quantitative manner. While inadequate base repletion is avoided, the direct addition of base requires much tighter control if undesirable acute changes in blood pH are to be avoided.

3-Hydroxybutyric Acid↗
PubMed1981

Some phenomena associated with the development of Trypanosoma brucei rhodesiense infections in the tsetse fly, Glossina morsitans.

Immature salivary gland (SG) infections averaging 10(3) parasites per fly can apparently develop into mature gland infections averaging 10(5) parasites per fly in as little as 4 days. Frequently flies which extrude parasites in their saliva prove to have no parasites in the SG, but often show trypanosomes in the esophagus, cibarial pump, and proboscis. In some instances, SG infections have cleared, resulting in a loss of infectivity. Results of studying numbers of parasites regurgitated upon feeding or probing have shown that number to be highly variable and not necessarily related either to previous feeding status or the total number of parasites in the glands. Cloning of metacyclics in mice has been achieved, indicating that the minimum effective dose is one parasite. To date, no infections in mice have resulted from inoculation of extraglandular parasites. Histological and dissection studies support both the classical route and an alternate route of infection development in flies. No SG-infected flies have been found which did not also have proventricular and anterior and posterior midgut (AMG and PMG) infections. Although the AMG is where the heaviest MG infections occur, the PMG seems to support the last survivors in a moribund MG infection. No parasites have been found in the hindgut.

Animals↗
PubMed1980

Separation and quantification of the "middle molecules" in uremia.

A modification of a two-stage chromatographic procedure (molecular sieve followed by ion-exchange) to separate potentially toxic uremic "middle molecules" from body fluids has been established. The procedure has an analysis time less than half that previously reported with improved resolution. Elution volumes have been found to be reproducible to within 2% and concentrations (as measured by peak height) to within 10%. Careful attention, however, must be paid to artifacts that may arise from sample preparation, drug therapy, and dialysis conditions. Up to ten identifiable subpeaks were observed in sera, urine, and red cell hemolysate samples following ion-exchange separation of a molecular sieve peak in the middle molecule range (300 to 2000 daltons). Red cell concentrations of five of these moieties were significantly higher than those in serum. Four peaks were not detected at all in red cells, and one peak was not detected in sera or urine samples. In addition, although serum concentrations are elevated in uremia, red cell levels in patients with uremia are comparable with those obtained in normal subjects. If any of these species are subsequently shown to be uremic toxins, then their two-compartment distribution within the body has important ramifications in the choice of an appropriate mathematic model to program optimal dialysis therapy.

Body Fluids↗
PubMed1980

Age and acceptance of euthanasia.

Data on attitudes toward euthanasia from the 1977 NORC General Social Survey are analyzed. Women appear to be less accepting because of their greater religiosity. Less acceptance by nonwhites is associated with their lesser education and greater religiosity, and nonwhites appear additionally skeptical about institutionally-controlled decisions about life and death. Older people are apparently less accepting because lower education and increased religiosity. Among older people, acceptance of euthanasia is also greater among those who are more dissatisfied with their lives and more anomic. Death and euthanasia appear to be distinct attitude objects. Age differences in fear of death reflect aging effects, while age differences in the acceptability of euthanasia reflect cohort effects.

Adolescent↗
PubMed1979

The meaning of voluntary association participation to older people.

Studies have indicated little association between participation in voluntary associations by older people and well-being. This may reflect self-selection by well-to-do older people who are "joiners" or a lack of truly involving group roles. From interviews with 323 persons over 60, it was found that active group participation yielded more "meaningful" reasons for enjoyment, and card-playing less meaningful reasons. Such reasons for group participation as contacts with others and passing the time were associated with lower satisfaction. On the whole, however, type of activity and reasons for participation had little relationship to life satisfaction, since they largely reflected health and socioeconomic status differences.

Aged↗
PubMed1979

The never-married in later life.

Sources or consequences of singlehood are analyzed for the 162 never-married persons aged 50 and over from the six years of the NORC General Social Surveys. Highly-educated older women are most likely to remain single, but family background was not a predictor. Although the never-married find life more exciting than other marital statuses among younger (25 to 49) respondents, this reverses in later life. The never-married are also less happy than the married, and only slightly happier than the widowed and divorced. The characteristic that best explains their relative unhappiness is greater dissatisfaction with family life. The lower well-being of the never-married is attributable either to changes accompanying aging which lessen the viability of single life styles, or to less support of single living among current older cohorts.

Adult↗