Biophysical issues include the effects of flow on collison frequency , adhesion and de-adhesion related directly to surface molecules present on platelets and other blood cells at the time of actual collisions. The choice of flow devices, and model surfaces or model spheres in suspension, is critical to proper and biologically meaningful evaluation of the molecular biorheology of platelet-platelet and heterotypic blood cell collisions, best done with particles in suspension in couette flow. Parallel plate flow devices, on the other hand, are more appropriate for studies of platelet- thrombus collisions. He discussed biorheological issues in the design of flow devices for clinical monitoring of thrombosis and coagulation, and the relation between platelet biology, flow and the choices of anti-thrombotic drugs. Prof. Don Gabriel presented a brief overview of the clinical issues in monitoring the thrombotic state, as a complementary introduction to the use of bedside clinical devices.
Quantification is performed with videomicroscopy and computer interface.
The rectangular capillaries are good for low volume, but not practical for bedside assays at this time, largely due to need for 'unstable' protein-coated surfaces. They are, however, very useful because of direct visualisation of platelet deposition via videomicroscopy. Dr Sakariassen pointed out the importance of eventually testing fresh non-coagulated blood in platelet function testing. Prof. Yasuo Ikeda described the use of a quartz crystal microbalance for the evaluation of platelet deposition onto protein-coated surfaces. In spite of problems in analysing the cellular overlayers with standard equations applicable to molecular reactions, due to viscoelasticity of the cells, quantitative analyses were feasible and provided real-time measurements of platelet deposition under various pathological conditions.