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Biomedical subjects

A R Walker

Publications and source records attributed to A R Walker.

At least 199 records · Page 11Linked to original sources
PubMed1991

Malabsorption of carbohydrate foods by urban blacks.

Prevalences of non-infective bowel diseases are very low in South African urban blacks compared with the white population. In seeking elucidation, using breath hydrogen measurements in series of black and white subjects, small-bowel transit time was determined, and the malabsorption of maize, wheat, and rice investigated. Median transit times in both ethnic groups were similar. Rice was fully, but wheat incompletely absorbed by both groups. Maize, the staple food of blacks, was incompletely absorbed by them, although completely absorbed by the white subjects. Carbohydrate consumption is high in the black population (60-65% of total energy intake). It is probable that in blacks, despite their now eating a low-fibre diet, an expected increase in large-bowel diseases has been inhibited in part by the protective mechanism of fermentation of malabsorbed maize and wheat.

Adult↗
PubMed1991

Glycaemic responses to different carbohydrate foods in healthy and diabetic blacks in Soweto.

Diabetes mellitus is uncommon in rural southern African blacks. With urbanisation and lifestyle changes, incidence rises to that in western populations. To assess associated changes in carbohydrate metabolism, glycaemic responses to glucose, refined maize, refined rice and bread were studied in 8 healthy and 8 non-insulin-dependent diabetic urban blacks. Additionally, in the healthy group serum insulin responses were measured. In the healthy, maize (the staple food of blacks) elicited the highest glucose response (207 mmol/l/min) and bread the lowest (107 mmol/l/min). The glycaemic indices of maize and glucose were similar. Serum insulin responses to maize were significantly lower than that of bread at 90 minutes (maize 66 muU/ml; bread 93 muU/ml; P = 0.02). In diabetics, maize and glucose elicited similar glycaemia (928 mmol/l/min and 921 mmol/l/min respectively). The high glucose response to maize could relate to its processing and physical form. The low insulin secretion could be due to inadequate stimulation by the 'entero-insular' axis. Moreover, variability in glucose insulin responses could stem from ethnic or genetic reasons. In the dietary management of black diabetics, refined maize should be replaced by other cereals.

Adult↗
PubMed1991

Histopathology of attachment sites of Amblyomma variegatum and Rhipicephalus appendiculatus on zebu cattle of varying resistance to ticks.

Mature, unimproved East African Zebu cattle (Bos indicus) naturally exposed to ticks from birth were ranked for resistance to ticks by repeated whole-body counts of infesting ticks. Four cattle of high resistance, four of low resistance and two of intermediate resistance were artificially infested with nymphs of Amblyomma variegatum and Rhipicephalus appendiculatus. Two Friesian cattle (Bos taurus) with less exposure to ticks were similarly infested. Biopsies of tick attachment sites were examined histologically. All attachment sites showed acute inflammatory lesions, and sites of both tick species on high resistance cattle showed delayed hypersensitive reactions with intra-epidermal pustulation and significant increases in the numbers of granulocytes. The predominant cells infiltrating attachment sites on high resistance cattle were eosinophils with A. variegatum and neutrophils with R. appendiculatus. Such differences need to be taken into account in developing immunological tests for selecting cattle for resistance but there are sufficient common features of reactions to the two infesting tick species to justify dermal hypersensitivity tests.

Africa, Eastern↗
PubMed1991

The hospital costs of diagnostic procedures for colorectal cancer.

Diagnosis for colorectal cancer is commonly made using either colonoscopy or double contrast barium enema techniques. To data, little attention has been paid to the comparative costs of these two procedures and the paper presents estimates of hospital costs for each, using data from the colorectal study being undertaken in Nottingham, U.K. Consideration is also given to procedure sensitivity and the frequency of referral to the alternative technique in cases of incomplete diagnosis. The paper presents the conditions under which a given technique may be considered cost-superior to its alternative but concludes that the absence of conclusive clinical trial data and other considerations precludes the identification of a definitively optimum technique from the economic point of view.

Barium Sulfate↗
PubMed1991

Limitations of faecal chymotrypsin as a screening test for chronic pancreatitis.

Faecal chymotrypsin was measured in patients with chronic pancreatitis and in healthy black urban and rural control subjects. In the patients, significantly lower values of faecal chymotrypsin were obtained (mean (SD) 2.4 1.79 U/g stool) whereas in urban control subjects, values were within the normal range (mean (SD) 13.2 (11.9)). In rural black control subjects, however, the faecal chymotrypsin value was significantly lower (mean (SD) 7.1 (5.1)) than in urban black control subjects. It is suggested that faecal pH may influence faecal chymotrypsin values. The mean faecal pH in rural black subjects (pH 6.14) was significantly lower than that in urban control subjects (pH 6.77) and in patients with chronic pancreatitis (pH 6.61). Moreover, mean faecal chymotrypsin is high (20.0 U/g stool) at a pH greater than 7. Between pH 6 and 7 the mean value drops to 8.6 U/g stool and below pH 6 mean faecal chymotrypsin is in the abnormal range (4.4 U/g stool). Hence, low values for faecal chymotrypsin may be due to lower faecal pH (less than 6) in healthy control subjects. For diagnostic purposes, the faecal pH value should be determined if a low faecal chymotrypsin value is obtained.

Adult↗
PubMed1991

Body image and eating behaviour in interethnic adolescent girls.

Reports of major dissatisfaction among adolescent girls over body shape and their associated eating behaviour, prompted determining anthropometric and questionnaire studies on series of rural and urban black, Indian, and white girls aged 14-19 years. Variables were concern over weight, desired weight loss, also practices regarding binge eating, fasting, vomiting and laxative use. Black girls have low weight-for-age, yet experience more obesity than white girls; yet weight reduction, although desired, is seldom seriously attempted. Indian girls have low weight-for-age, principally for genetic, not social class, reasons; they also, even some underweight, desired weight reduction. White girls are also dissatisfied, although less acutely than girls in the US. The current attitudes of South African adolescent girls, apart from extremes, are unlikely to seriously prejudice their health.

Adolescent↗
PubMed1991

Combating protein-energy-malnutrition in a rural/peri-urban southern African black population.

PROTEIN-ENERGY-malnutrition (PEM) is a major cause of morbidity and mortality in young children in Africa. In South Africa, in 1987, to help combating and preventing PEM in the rural black population, the Gold Fields Nutrition Unit was inaugurated at the Medical University of Southern Africa. In 1987-9, 442 patients (rural/peri-urban) plus their mothers or child carers were admitted, and 406 attended as outpatients. Average age was 15.4 +/- 7.6 months, weight 7.0 +/- 1.6kg, stay in hospital, 12 +/- 10.8 days, and daily weight gain during treatment was 31 +/- 48g. Mothers mainly were young and unmarried. Primary causative factors were infections, ignorance, and insufficiency of food. Since results from rehabilitation are usually poor, mothers and carers were taught how best to prepare meals using local foodstuffs. The interventions included teaching and demonstrations of how to grow vegetables, maintain an orchard, a fowl-run, and improve kitchen and laundry facilities. In 1990, in a follow-up of 73 patients, no deaths had occurred within a 12 month period. This far better than usual outcome is being furthered by setting up satellite nutrition clinics.

Black People↗
PubMed1991

Rehydration of guaiac-based faecal occult blood tests in mass screening for colorectal cancer. An economic perspective.

Owing to dehydration during storage, faecal occult blood tests have been found to lose sensitivity; accordingly, test rehydration before development has been advocated, although this practice has yet to be subjected to an economic evaluation. In this paper, the results from two major screening trials in Sweden and England, one using rehydration and the other not, are so evaluated, based on a costing model developed within the English trial. The higher sensitivity resulting from rehydration was found to be accompanied by losses in specificity, such that, although more cancers are detected, the costs of screening and of cancer detection are actually considerably higher under the rehydration regimen than with non-hydration.

Colorectal Neoplasms↗
PubMed1991

Obesity in indigent elderly rural African women: effects on hypertension, hyperlipidaemia and hyperglycaemia.

To learn more of the sequelae of obesity in South African elderly rural indigent black women (aged 58-85 years), studies were made on 40 women with BMI greater than or equal to 30, and on 50 non-obese women with BMI of 25 or less, all in outward good health. In the two groups, hypertension (greater than or equal to 160/95 mm Hg) was present in 9 and 5 women (22% and 10%), hypercholesterolaemia (greater than or equal to 5.2 mmol/l) in 28 and 26 women (70% and 52%), hypertriglyceridaemia (greater than or equal to 1.8 mmol/l) in 20 and 16 (50% and 32%), and hyperglycaemia (greater than or equal to 6.7 mmol/l) in 8 and 7 women (20% and 14%). Differences between the obese and non-obese attained significance with blood pressure and serum lipids (P less than 0.01), although not with blood glucose. Both groups were habituated to a low fat high fibre diet. In this context, obesity appeared less evocative of adverse sequelae than prevails in a white population. However, for appropriate validation, longitudinal studies are required.

Aged↗
PubMed1991

Serum albumin levels in elderly rural Africans.

Reports on white populations indicate an inverse relationship between serum albumin level and total death rate, also death rates from cardiovascular diseases (CHD) and cancer. Among rural African blacks, CHD is absent, and diet-related cancers rare, so that albumin levels in the elderly would be expected to be elevated. Studies on 50 men and 50 women, representative elderly rural blacks, revealed mean values to be high, 47.6 +/- 4.9 g/l and 48.2 +/- 4.2 g/l. Levels were not significantly associated with Body Mass Index, blood pressure, serum cholesterol level, nor blood glucose level. Hence, in the setting described, even elevated levels of these variables appear less noxious to health than is the case in white populations, since such levels are consistent with low mortality from the diseases mentioned. Explanation of the relationship between serum albumin and life expectancy is unknown. Longitudinal studies are necessary to clarify the situation.

Aged↗