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Biomedical subjects

W H Wilkinson

Publications and source records attributed to W H Wilkinson.

11 recordsLinked to original sources

Dietary and other characteristics relevant for coronary heart disease in men of Indian, West Indian and European descent in London.

The origins of the high standardized mortality ratio (SMR) for coronary heart disease (CHD) among Indians in Britain, and the low SMR for West Indian immigrants, have been explored by a community survey in London. Serum lipoproteins, plasma glucose, haemostatic factors and other putative risk characteristics were measured in 75 Indian, 64 European and 24 West Indian men aged 45-54 years. These represented 81% of men registered with a general practice and resident within a defined area. In 51 men, diet was assessed by 5-day weighed inventory. Plasma phospholipid fatty acids (PFA) were measured in 18 Indians and 19 Europeans with dietary records. The relatively high HDL and HDL2-cholesterol concentrations, low LDL-cholesterol concentration, reduced fat intake, increased ratio of dietary polyunsaturated/saturated fat, relatively frequent use of alcohol, and lack of obesity in West Indians accorded with their low SMR from CHD. By contrast, only the relatively low HDL and HDL2-cholesterol concentrations, infrequency of alcohol consumption, and lower proportion of PFA as n-3 fatty acids of marine origin afforded explanations for the high SMR of Indians. Hyperglycaemia appeared similarly prevalent in Indians and West Indians, but less common in Europeans. Of the haemostatic factors, West Indians had a relatively low VIIc (not statistically significant), while Indians had an increased platelet count and reduced platelet volume. Improved understanding of these ethnic differences in CHD mortality may depend upon elucidation of the contrasts in HDL-cholesterol concentration.

Blood Coagulation Tests

Association between dietary fat intake and plasma factor VII coagulant activity--a predictor of cardiovascular mortality.

Repeated measurements were made in 8 adults of factor VII coagulant activity (VIIc) and fibrinogen concentration (two haemostatic variables associated with cardiovascular mortality), together with factor VII concentration, factor X, prothrombin, and serum cholesterol and triglyceride concentrations, while the usual diet was recorded by precise weighing over 12-14 days. In 6 subjects measurements were continued while low-fat and high-fat diets were taken for a further 2 and 3 weeks respectively. Plasma VIIc was related positively and independently to fat and protein intake, whereas factor VII concentration was associated only with protein consumption. In a second study, consumption of 50% extra energy for one day increased VIIc significantly when taken mainly as fat but not when taken mostly as carbohydrate. The character of the VIIc response to fat intake suggested an association with post-prandial lipaemia. A high fat intake may lead not only to coronary atheroma but also to fibrin deposition and thrombus formation through direct activation of the coagulation system.

Adult

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Clinical Competence

Adherence properties of sickle erythrocytes in dynamic flow systems.

Sickle (SS) erythrocytes have been demonstrated to be more adherent to cultured endothelial cells than normal (AA) erythrocytes when incubated under the static conditions of the culture dish. We studied the adherence of erythrocytes to vascular endothelium under various conditions of controlled perfusion to determine whether the increased adherence of SS erythrocytes has pathophysiologic relevance to the development of vaso-occlusive crises. Freshly procured human umbilical veins were perfused once with chromium 51-labeled washed erythrocytes at a flow rate of 1 ml/min under ambient oxygen tension. After a 10-minute washout procedure, there was no significant difference in the adherence of either SS or AA cells (0.53% vs. 0.54%) to undamaged endothelium. Continuous closed-loop perfusion of labeled cells for 20 minutes also showed minimal adherence for both cell types. Scanning electron microscopy confirmed that adherence was sparse and focal. Endothelial cells were then cultured in fibronectin-coated glass capillary tubes, which served as conduits for perfused erythrocytes. Again, adherence was minimal and not significantly different for SS or AA cells (0.057% vs. 0.065%). To introduce hemodynamic variables into the system, erythrocytes were perfused into fibronectin- and endothelial cell-coated capillary tubes constructed to have multiple bends. Scanning electron microscopy showed that SS erythrocytes were significantly more adherent than AA cells in these convoluted tubes. Our findings support the notion that SS erythrocytes become trapped in the microcirculation because of a complex combination of hemodynamic forces and plasma factors as well as red cell membrane peculiarities, rather than the simple propensity of these cells to adhere to the vascular endothelium.

Anemia, Sickle Cell