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Biomedical subjects

A Williams

Publications and source records attributed to A Williams.

At least 433 records · Page 24Linked to original sources
PubMed1991

Erythropoietic protoporphyria: unusual skin and neurological problems after liver transplantation.

The case of a woman with protoporphyria who developed liver failure and underwent liver transplantation is described. During the pretransplant episode of liver failure she developed quadriparesis that rapidly progressed after transplantation to a severe polyneuropathy. Following transplantation she also developed a second-degree burn of the light-exposed abdominal wall. The neuropathy resembled that observed in other forms of porphyria, and it is proposed that the extreme disturbance of protoporphyrin levels associated with protoporphyrin-induced liver failure caused this neuropathy. Such a neuropathy has not previously been described in protoporphyria. Erythrocyte protoporphyrin levels remain high and fecal levels normal, although results of liver tests are normal. She remains photosensitive, which emphasizes that although liver transplantation may be lifesaving in this disorder, it is not curative, and care must be taken to prevent photosensitive damage to skin and light-exposed internal organs.

Adult↗
PubMed1991

Immunological correlates of seasonal fluctuations in mood and behavior and their relationship to phototherapy.

Immunological parameters were studied before and after phototherapy, with bright and dim light, in 38 individuals with a range of retrospectively reported seasonal changes in mood and behavior. There was a significant negative correlation between the degree of mood and behavioral difficulties in fall and winter (seasonality) and the total number of circulating natural killer cells. Changes in the numbers of circulating helper T cells correlated significantly with changes in mood following phototherapy. Moreover, mitogen-induced lymphocyte blastogenesis increased significantly after phototherapy, but there was no significant difference between the bright and dim light treatments. The results suggest that cellular immune function is associated with both seasonality and response to phototherapy.

Adult↗
PubMed1991

The role of health economics in clinical decision-making: is it ethical?

With health care resources inevitably limited, we must ensure that they are used where they will do the most good. Doing good means improving people's life expectancy and quality of life, two characteristics which are combined in the Quality-Adjusted-Life-Year, or QALY. Even with effectiveness measured in this humanitarian way some people think it is unethical to let cost-effectiveness notions guide health care priorities. But costs represent sacrifices of health imposed on others, and it cannot be ethical to ignore such sacrifices. Indeed the reverse is true, it is unethical to ignore costs, and not to seek to become more efficient.

Cost-Benefit Analysis↗
PubMed1991

Effects of self-monitored exercise on selected blood chemistry parameters of end-stage renal disease patients.

The effects of exercise on patients with end-stage renal disease (ESRD) is relatively unexplored. Of the complications associated with kidney failure, anemia and abnormal blood lipids profiles are among those that exercise may alter. Thus, the purpose of this study was to determine the effects of a self-monitored exercise program on the blood chemistry status in ESRD patients. The program consisted of aerobic activity maintained for a minimum of 15 min at least three times per week at an intensity of 10.8 +/- 2.13 on the Borg rating of perceived exertion scale (this scale correlates with heart rate and is used in cases where heart rate is not a reliable predictor of exercise intensity such as hemodialysis patients). Monthly blood samples were taken to assess the patients status regarding anemia and blood lipids. Results indicate no significant differences (P greater than 0.05) were seen from the beginning of the program until the end of the eighth month as seen below: [table; see text] Values are X +/- SEM. These data indicate that a self-monitored exercise program of moderate intensity may not be beneficial in helping regulate the anemia and altered blood lipid status of ESRD patients. Thus, since no physiological benefits are apparent with a self-monitored exercise program of low intensity, it is important to realize the potential risk involved with patients undertaking an unsupervised exercise program. These data illustrate that ESRD patients need supervised exercise programs in order to elicit a physiological training response.

Adult↗
PubMed1991

A comparison of cost-sharing versus free care in children: effects on the demand for office-based medical care.

Using data from the community based RAND Health Insurance Experiment, the effect of cost-sharing versus free care on the use of office-based medical care in children was examined. Children from families on cost-sharing plans had a 22 percent lower probability (P less than 0.005) of having an episode of care during the study year. Both the number of episodes of care and total charges for outpatient professional services were 30 percent lower (P less than 0.005) with cost-sharing. cost-sharing reduced average charges for medical services by 30 percent (P less than 0.01) and pathology charges by 45 percent (P less than 0.005). cost-sharing reduced medical services received by 26 percent (P less than 0.05) and pathology services received by 43 percent (P less than 0.05) but did not have a significant effect on either the price for medical services or pathology services. It was concluded that there is a large difference between cost-sharing insurance plans and free care in the demand for office-based medical care in children. Cost-sharing results in children receiving fewer services, not lower priced services.

Child↗
PubMed1991

Metabolic biomarkers of Parkinson's disease.

Enzymic systems involved with metabolism of foreign chemicals, xenobiotics, have been studied in Parkinson's disease. Enzymes involved with sulphur oxidation and methylation are under-active. Cysteine levels are high and sulphate levels low. Differences in the activity of the enzyme monoamine oxidase-B are evident. Pathways involved with N-methylation of pyridines are different from controls leading to a rise in potentially toxic N-methylated derivatives.

Carbocysteine↗
PubMed1991

A comparison of aminopeptidases from excised human buccal epithelium and primary cultures of hamster pouch buccal epithelium.

Aminopeptidase activity associated with human buccal tissue and primary cultures of hamster buccal epithelium homogenates was assayed fluorometrically using 4-methoxy-2-naphthylamides of leucine, alanine, and arginine. Kinetic parameters, Km and Vmax, for all substrates were estimated. Aminopeptidase parameters for human tissue were similar to those for the in-vitro system and reported literature values for rodent buccal tissue aminopeptidases. Aminopeptidases of both tissues were also found to be similarly sensitive to typical inhibitors, bestatin and puromycin. Overall results suggest that appropriate in-vitro systems derived from animal tissues may be useful in assessing the role and localization of peptidases associated with buccal tissue.

2-Naphthylamine↗
PubMed1991

Factors affecting adherence of end-stage renal disease patients to an exercise programme.

Recently it has been shown that regular exercise is both physiologically and psychologically beneficial to patients with end-stage renal disease (ESRD). However, ESRD patients traditionally have a high non-adherence level to their self-care and medical regimens. To date, their adherence to exercise programmes has not been studied. Background information about employment, medical history, previous exercise habits and locus of control was obtained from 40 volunteer ESRD patients who started exercise at home. Twenty-eight participants maintained the exercise programme, consisting of aerobic activity lasting an average of 25 min, four times per week, for 12 weeks. The adherent patients were found to have encouraging support groups (75 versus 25%), to be between 41 and 60 years of age (64 versus 33%), to have been on dialysis for between 2 and 5 years, and to have loci of control (feeling of control over life events) classed as 'internal' (68 versus 25%). Factors such as sex, race, employment status and depression were found to have little influence on adherence. The major finding of this study was that patients adherent to exercise could be distinguished by unique psychological and psychosocial factors, and that adherence in this population was higher (70 compared with 50%) than some estimates for the general population.

Adult↗
PubMed1991

Von Hippel-Lindau disease: a genetic study.

Genetic aspects of von Hippel-Lindau (VHL) disease were studied in familial and isolated cases. Complex segregation analysis with pointers was performed in 38 kindreds with two or more affected members. Dominant inheritance with almost complete penetrance in the highest age classes (0.96 at 51 to 60 and 0.99 at 61 to 70 years) was confirmed and there was no evidence of heterogeneity between families ascertained through complete and incomplete selection. The point prevalence of heterozygotes in East Anglia was 1.89/100,000 (1/53,000) persons with an estimated birth incidence of 2.73/100,000 (1/36,000) live births. Reproductive fitness was 0.83. Direct and indirect estimates of the mutation rate were 4.4 (95% CI 0.9 to 7.9) x 10(-6)/gene/generation and 2.32 x 10(-6)/gene/generation respectively. There was no significant association between parental age or birth order and new mutations for VHL disease.

Adult↗
PubMed1991

Dietary obesity and weight cycling in rats: a model of stress-induced hypertension?

The present study was designed to reproduce the mild hypertension seen in dietary obese weight-cycled rats [P. Ernsberger and D. O. Nelson. Am. J. Physiol. 254 (Regulatory Integrative Comp. Physiol. 23): R47-R55, 1988] and determine whether this mild hypertension was associated with changes in sodium excretion and pressor responsiveness to angiotensin II (ANG II). Male Sprague-Dawley rats were fed pelleted chow (Pellet group) or chow plus sweetened condensed milk (Milk group) or were exposed to four cycles of a 4-day fast alternated with 2 wk of refeeding of pelleted chow and sweetened condensed milk (Cycled group). Blood pressure and heart rate were measured by tail cuff at the onset and last day of each fast and after 3 days of refeeding. During fasting, urine sodium excretion was measured. Mean arterial pressure and heart rate responses to intravenous administration of ANG II (40, 80, and 120 ng/kg), metoprolol (1 mg/kg), and methyl scopolamine (2 mg/kg) were obtained from the femoral artery in awake unrestrained rats. Weight cycling did not lead to mild hypertension or increased bradycardic response to sympathetic blockade with metoprolol. ANG II-elicited pressor responses were similar for Pellet, Milk, and Cycled groups. Sodium excretion did not change with fasting. Mild hypertension developed when obese weight-cycled rats were housed together in groups and not when housed individually. Our preliminary data are consistent with the notion that stress associated with group housing may be a factor in the mild hypertension of obese weight-cycled rats.

Animals↗
PubMed1991

Xenobiotic enzyme profiles and Parkinson's disease.

Xenobiotic enzymic systems have been studied in Parkinson's disease. Platelet monoamine oxidase-B activity is increased by the use of phenylethylamine but decreased by the use of dopamine as substrate. Enzymes involved with sulfur oxidation and methylation are underactive.

Animals↗
PubMed1991

Motorcycle licensure, ownership, and injury crash involvement.

The interrelationships among motorcycle licensure, ownership, and injury crash involvement were investigated in a sample of 2,723 motorcycle drivers severely or fatally injured in California in 1985-86. Owners of motorcycles in such crashes ("driver-owners") were less likely to have valid licenses than a random sample of motorcycle owners who had not been in crashes (42 vs. 57 percent). Thirty-three percent of the crash-involved drivers had valid motorcycle driver's licenses; 39 percent were operating motorcycles they did not own ("driver-nonowners"). Driver-nonowners were less likely to be validly licensed than driver-owners (20 percent vs. 44 percent). The licensing rate of crash-involved driver-nonowners was 15 percent if the owner was also unlicensed. Rates of valid licensure were lowest among the youngest drivers. Virtually no crash-involved driver-nonowners under age 21 were licensed in cases in which the owner was also young and unlicensed.

Accidents, Traffic↗