Shear-induced Filter Blockage. A Population Based Appraisal of a Method for the Assessment of Platelet, White Cell and von Willebrand Factor Interactions

Abstract

Blood behaviour under shear-stress is assessed by a filter method in the Caerphilly Prospective Heart Study. Associations with haemostatic and lifestyle factors in 941 men aged 55 to 69 years are reported. The importance of platelets in filter blockage is confirmed, and roles for white cells and plasma viscosity in determining flow prior to blockage are identified. The aspect of platelet activity involved in blockage appears to be independent of mechanisms mediated by cyclo-oxygenase and adenosine diphosphate. von Willebrand factor however is associated with filter blockage, probably as an inter-platelet ligand. Fibrinogen is not required for blockage. Men regularly consuming alcohol or garlic supplements show reduced blockage, and biochemical mechanisms are suggested which might explain these associations. No effects of aspirin, smoking or consumption of fish oil supplements were noted. Shear-induced filter blockage is a simple method for measuring complex flow-dependent interactions of haemostatic factors. Its application in a wide range of investigations, including epidemiological studies, would appear to be appropriate.

Platelet tests in the prediction of myocardial infarction and ischaemic stroke: evidence from the Caerphilly Prospective Study

“…The actual test results we have used in this report have already been shown to have meaningful relationships with prevalent vascular disease and with smoking, alcohol and other haematological factors (Sharp et al , 1990, 1994; Elwood et al , 1991; Renaud et al , 1992; Beswick et al , 1994). In particular, we have already reported a positive and significant association between the whole‐blood impedance aggregation test results and prevalent IHD (Elwood et al , 1990) and significant interrelationships between it and other haemostatic tests (Elwood et al , 1993; Beswick et al , 1994).…”

“…There was no evidence of prediction of the incident of ischaemic heart disease (IHD) events during the following 8–10 years (Elwood et al , 1991, 1998). We now present results on an extended follow‐up of this cohort, together with evidence on prediction using two further tests of platelet activity: aggregation to ADP in whole blood measured using an impedance method (Cardinal & Flower, 1980; Beswick et al , 1994) and a shear‐induced platelet retention filter test (O'Brien & Salmon, 1987; O'Brien, 1990). This report also includes an examination of prediction of ischaemic stroke by each of these tests.…”

“…In both phase II and phase III of the study, blood was drawn into a one‐tenth volume of 0·13 mol/l sodium citrate for the platelet tests and these were performed without delay. Two specially trained technicians performed the platelet aggregation tests (Elwood et al , 1990, 1991; Beswick et al , 1994). A large number of other haemostatic and rheological tests were performed by colleagues in collaborating laboratories (Sweetnam et al , 1996, 1997; Lowe et al , 1998).…”

Replication and hematological characterization of human platelet reactivity genetic associations in men from the Caerphilly Prospective Study (CaPS)

“…Retention of platelets after induction of shear stress filtration was measured in Phase 3 as previously described [13]. Briefly, within 5 min of a fasting venous blood draw, heparinized blood was forced at 40 mmHg through a 13 mm diameter filter with fibers ranging from 0.1–3.4 u M. Blood drops passing through filters were measured electronically over time.…”

REVIEWLaboratory investigation of platelet function

“…Filter occlusion devices have also been proposed as tools for investigating defects of shear-induced aggregation (O'Brien & Salmon 1987;Beswick et al 1994;Cattaneo et al 1995;O'Brien et al 1995;Pareti et al 1996). These devices have proven to be useful research tools but their role in routine investigation of platelet function remains to be established.…”