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Biomedical subjects

A R Walker

Publications and source records attributed to A R Walker.

At least 19 recordsLinked to original sources
PubMed1992

Screening for colorectal carcinoma: an analysis of the sensitivity of haemoccult.

The sensitivity of Haemoccult for asymptomatic colorectal carcinoma has been estimated in a large randomized controlled trial of mass population screening, with a minimum follow-up of 2 years. A total of 111 cancers were diagnosed in those who completed the screening tests; of these, 36 appear to have been missed by Haemoccult and 75 were detected by the test, giving an overall sensitivity of 67.6 per cent. Haemoccult was shown to be significantly more sensitive for carcinoma of the sigmoid and descending colon than for rectal or right-sided cancers (81 versus 45 and 47 per cent, respectively). The sensitivity was higher when tests were completed over 6 rather than 3 days (74 versus 65 per cent), but this difference was not statistically significant. There was no evidence for a detrimental effect on tumour stage of a false-negative Haemoccult test; indeed, a higher proportion of the interval cancers were Dukes' A tumours than cancers in the control group.

Aged↗
PubMed1992

Cost savings in mass population screening for colorectal cancer resulting from the early detection and excision of adenomas.

The widely-accepted hypothesis of a development sequence from colorectal adenoma to carcinoma is felt by clinicians to legitimate adenoma excision during routine colonoscopic investigation. Using published data on adenoma development, and adenoma prevalence data derived from the Nottingham colorectal cancer screening trial, the number of carcinomas prevented by early excision as a result of screening is predicted. The cost-effectiveness of early excision is then evaluated with reference to the expected treatment costs saved. These cost savings are found to represent a discount on the overall costs of mass population screening for colorectal cancer.

Adenoma↗
PubMed1979

Serum high-density lipoprotein cholesterol, glucose tolerance and other variables in obese black adolescent girls.

Obesity is very common in South Africal Black girls aged 18 - 20 years. Severely obese White women have greatly reduced values for serum high-density lipoprotein (HDL) cholesterol. In a series of Black girls studied in rural and urban areas, mean values for HDL cholesterol were not significantly different in the obese compared with the non-obese groups. There were also no significant differences between obese and non-obese groups in mean serum cholesterol, triglyceride, uric acid, and blood glucose at fasting and 1 hour after a glucose drink. The same finding prevailed regarding blood pressures. All values for blood components were biologically more favourable in Black than in White adolescent girls (reported values). Mean sugar intakes of the obese were not significantly lower. Evidently, the metabolic and other disabilities linked with obesity in young White women have no counterpart in obese Black adolescent girls.

Adolescent↗
PubMed1979

Faecal pH value and its modification by dietary means in South African black and white schoolchildren.

Mean faecal pH values did not differ significantly in groups of rural South African Black schoolchildren of 10--12 years who ate their traditional high-fibre low-fat diet, and urban dwellers who consumed a partially westernized diet. However, both means were significantly lower than those of groups of White schoolchildren. In feeding studies of 5 days' duration, mean faecal pH value of Black children became significantly less acid when white bread replaced maize meal, and became significantly more acid when a supplement of 6 oranges was consumed daily. Supplements which consisted of skim milk, butter, and sugar had no significant effect on mean faecal pH value. In White children in an institution, the mean pH value of faeces became significantly more acid when a supplement of 6 oranges, although not of bran 'crunchies', was consumed daily.

Black or African American↗
PubMed1979

Rapid quantitative assessment of Theileria infection in ticks.

A simplified method for methyl green pyronin staining is described for Theileria parva and T. annulata in whole salivary glands of Rhipicephalus appendiculatus and Hyalomma anatolicum subspecies respectively. The stain gives results comparable with Feulgen staining and can be used after the ticks have been in cold storage for 3 days. There is considerable variability in the rate and intensity of infection of these ticks with theilerial parasites and it is concluded that the method permits large samples (60 ticks per person per day) to be examined to overcome this variability when assessing infection quantitatively.

Animals↗
PubMed1979

The production of nymphs of Hyalomma anatolicum anatolicum for experimental infection with Theileria annulata.

Methods are described for the production of nymphs of Hyalomma anatolicum anatolicum for later use in transmission experiments with Theileria annulata where the timing of the application of nymphs to infected cattle needs to be accurately controlled. Larvae are fed on the torsos of rabbits where approximately 98% undergo a two-host feeding cycle. This cycle is interrupted 2 days after the first larvae moult into nymphs by killing the rabbits and the nymphs are then collected with a suction pump. Nymphs produced by the interrupted larval feeding method feed well on cattle, in regard to timing of detachment and weight, compared with nymphs produced by interrupted feeding on rabbits.

Animals↗
PubMed1979

Mutagens in the feces of 3 South-African populations at different levels of risk for colon cancer.

The incidence of mutagens in the feces of 3 South-African populations at different risk levels for colon cancer has been determined. Lyophilized fecal samples were extracted with ether and the mutagenicity of the extracts determined using the Salmonella/mammalian microsome mutagenicity test. 19% of the samples from urban white South-Africans, a population at a high risk for colon cancer, were mutagenic using Salmonella typhimurium strain TA100. This incidence was significantly greater (p less than 0.001) than the incidence of mutagen excretion in the low-risk populations of urban blacks (2%) and rural blacks (0%). This pattern was also obtained using Salmonella typhimurium strain TA98. The incidence of mutagen excretion for urban whites was 10%, as compared to 5% and 2% for urban and rural blacks, respectively.

Black People↗