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Biomedical subjects

A R Walker

Publications and source records attributed to A R Walker.

At least 217 records · Page 12Linked to original sources
PubMed1991

Interethnic physiological and pathological diversities in southern African populations.

The African continent accommodates a diversity of races--Arabs, Berbers, Nilo-Saharan, Bantu, Pygmies, as well as immigrant white and Indian populations, especially in Central, East and Southern Africa. In these populations and sub-populations, differences prevail in physiological variables, in biological disorders, in measurements made by laboratory and associated means, and in disease patterns. A salient question is: which differences will persist, and which become modified or even disappear as a result of progressive urbanisation, a rise in prosperity, and changes in lifestyle, particularly when these occur in populations previously poor or who have lived in a rural traditional manner.

Black People↗
PubMed1990

Rhipicephalus appendiculatus feeding on rabbits and cattle: salivary-gland responses to varying host resistance.

Adult Rhipicephalus appendiculatus ticks were fed as three sequential infestations on both rabbits and cattle. The feedings at first infestation on naive hosts were optimum for the ticks, whereas at third infestation the hosts were resistant, as expressed by reduced tick feeding performance. Ticks from naive and resistant hosts were examined for histological differences of salivary glands. In ticks fed on resistant rabbits there was a large increase in the synthesis of glycoprotein secretory granules in the c1 cells compared with ticks fed on naive rabbits. In ticks fed on naive and resistant cattle, the activity of the c1 cells was less than in ticks fed on naive and resistant rabbits. It was concluded that the salivary glands are able to respond selectively to conditions at the feeding site, and that this may be advantageous to the tick.

Animals↗
PubMed1990

Fatal tapwater scald burns in the USA, 1979-86.

Four hundred and fifty-nine fatal tapwater scald burn injuries reported to the Injury Information Clearinghouse of the Consumer Product Safety Commission from 1979 to 1986 were studied. Data concerning the 459 deaths were abstracted from the death certificate file maintained by the Clearing house. Risk estimates were derived, using the resident population of the USA as of 1 July 1982 as the midpoint population estimate. Over half the deaths occurred in those over 75 years of age, while about one-fifth of the deaths occurred in children younger than 5 years of age. The crude mortality rate was approximately two deaths per million population over the 8-year period studied. In all age groups, black-skinned people experienced an approximate three-fold increase in risk (RR = 3.23, 95% CI: 2.87, 3.63). Among the elderly, males experienced an approximately 50 per cent increase in risk (RR = 1.47, 95% CI: 1.26, 1.72). One of every eight fatal injuries was sustained in a public building or residential institution. Implications of the current findings in terms of targetted prevention efforts are discussed.

Accidents, Home↗
PubMed1990

The occurrence of ephemeral fever in Kenya, 1968-1988.

Ephemeral fever occurs in Kenya in epidemics which have been associated with periods of unusually heavy and prolonged rainfall. The epidemics persist for 2-3 years and involve most of the country. They occur in the same years as epizootics of Rift Valley fever, which is a mosquito-borne Phlebovirus infection. Sporadic outbreaks of the disease have been associated with local heavy rains; though one outbreak occurred during a dry period. Culicoides spp. were generally present in large numbers at the site of the outbreaks. Seroconversions were detected in sentinel cattle, when there had been no apparent clinical disease.

Animals↗
PubMed1990

Resistance between stages of the tick Rhipicephalus appendiculatus (Acari: Ixodidae).

The ability of one stage of Rhipicephalus appendiculatus Neumann to induce resistance in a host to the feeding of the next stage in the life cycle was studied using Bos taurus cattle and rabbits. Simple resistance within a stage and cross-resistance between stages was generally less than 50%. The cumulative effect of simple resistance and cross-resistance over the whole life cycle in this experiment was estimated at 97% resistance measured as reduction in engorgement mass, numbers detached, and survival. Potential antigens in salivary glands of the three stages were compared by microscopy and electrophoresis and found closely similar. Production of serum antibodies against salivary antigens was examined by Western blotting of the electrophoretically separated salivary peptides. Cross reactions occurred but with little consistency. Hypersensitivity reactions were observed directly and tested immunologically. Only delayed hypersensitive reactions were directly involved in simple resistance and cross-resistance. These results can be applied in the selection of cattle for resistance to ticks, and this is discussed.

Animals↗
PubMed1990

The costing of nursing care: a study of 65 colorectal cancer patients.

Nursing care is a major factor in the cost of most medical treatments. This paper reports on two alternative techniques for estimating the costs of nursing care, in the context of colorectal cancer treatment on a surgical ward in the University Hospital, Nottingham. The simpler, but cruder, technique is based on average patient costs, whilst the other is patient-specific and incorporates the use of nursing dependency data. Results from the two estimation methods are compared and the implications for the proper costing of nursing care are discussed.

Activities of Daily Living↗
PubMed1990

Skin test to detect resistance of cattle to Rhipicephalus appendiculatus ticks.

The evaluation of a skin test to detect acquired resistance to Rhipicephalus appendiculatus Neumann ticks is described. An extract of salivary glands of partially fed female R. appendiculatus was prepared by dissection, sonication and filtration and used for intra-dermal injection. Tests were carried out on twelve calves of known resistance to R. appendiculatus and on twelve naive calves to establish threshold values for positive reactions. Four rabbits naive to ticks were skin tested repeatedly to assess immunogenicity of the test. Reactions to the test at 1 h and at 24 h after injection were significantly correlated with resistance. The correlation was higher with the reactions at 24 h. Rabbits were immunized by the test but the reactions never exceeded the positive threshold. Further development by field testing is recommended.

Animals↗
PubMed1990

Alternative pathways for hydrogen disposal during fermentation in the human colon.

Hydrogen gas, which is produced during fermentation in the human colon, is either excreted in breath or metabolised by gut bacteria through a variety of pathways. These may include methanogenesis, dissimilatory sulphate reduction, and acetogenesis. To determine which of these routes predominates in the large intestine, stools were taken from 30 healthy subjects and incubated as 5% (w/v) slurries with Lintner's starch. In 23 of 30 subjects, methane production was the main method of hydrogen disposal. In the remaining seven, high rates of sulphate reduction were recorded together with raised production of H2S. All samples showed relatively low rates of hydrogen evolution and of acetate formation from CO2 and H2. Sulphate reduction and methanogenesis seem to be mutually exclusive in the colon and this is probably linked to sulphate availability. Sulphate reduction, methanogenesis, and acetogenesis were strongly influenced by pH. Sulphate reduction was optimal at alkaline pH values whereas methane production was maximal at a neutral pH and acetogenesis favoured acidic conditions. Faecal H2S values were related to carriage of sulphate reducing bacteria. These data show that a number of competing pathways for hydrogen disposal are possible in the large gut and that a variety of factors such as colonic pH and sulphate availability can determine which of these mechanisms predominates.

Acetates↗
PubMed1990

Obesity in black women in Soweto, South Africa: minimal effects on hypertension, hyperlipidaemia and hyperglycaemia.

Studies were made on 50 South African urban black obese women aged 25-40 years, with Body Mass Index (BMI) (Kg/m2) of 29.5 or more, and on 50 non-obese women with BMI of 25 or less. In the two groups, mean triceps skinfolds were 25.5mm and 17.8mm, respectively. Hypertension (greater than or equal to 160/95mm Hg) was present in 6 and 4 women (12% and 8%), hypercholesterolaemia (greater than or equal to 5.2mmol/l) in 5 and 3 women (10% and 6%), hypertriglyceridaemia (greater than or equal to 1.8mmol/l) in 5 and 3 (10% and 6%), and hyperglycaemia (greater than or equal to 7.8mmol/l) in 2 and 1 women (4% and 2%). One or more adverse sequelae were present in 11 (22%) obese and in 9 (18%) of non-obese women, proportions not significantly different. Dietarily, mean daily intakes were--Kcals 2273 and 2240, protein 73g and 70g (12.9% and 12.5% energy), fat 65g and 67g (25.7% and 26.9% energy), carbohydrate 349g and 330g (61.4% and 60.5% energy), and dietary fibre, 12g and 13g. In this low socioeconomic and low fat dietary context, obesity in the black women studied was not specifically evocative of deleterious sequelae of obesity.

Adult↗