Mechanical trauma in leukocytes.

Mechanical and surface traumas in cardiopulmonary bypass circuits alter the function and morphology of human leukocytes. The effect of controlled in vitro shear stess (0 to 2,000 dynes/cm2, 2 to 10 min, 37 degrees C) on electronic cell count, morphology, adhesiveness, and phosphatase cytochemical staining was studied on whole blood from normal donors. Electronic cell counts droppped significantly after shear stress exposure (25% at 600 dynes/cm2 for 10 min).

Rheological evaluation of hemoglobin S and hemoglobin C hemoglobinopathies.

The concept of optimum hematocrit was used to compare the rheology of bloods from patients with various hemoglobin S and hemoglobin C hemoglobinopathies. The technique involved the utilization of cone and plate viscometric data to predict average flow rates under representative physiological-fluid mechanical conditions. The shape of the curve relating optimum hematocrit to oxygen tension, rather than the absolute magnitude of the optimum hematocrit at fixed oxygen tension, is shown to give an indication of clinical severity of the disease.

Rheological properties of fibrin clots. Effects of fibrinogen concentration, Factor XIII deficiency, and Factor XIII inhibition.

The effect of fibrinogen concentration, Factor XIII deficiency, and Factor XIII inhibition, utilizing hydroxylamine, on the formation of clot structure in vitro was studied in human platelet-free plasma systems. Rheological and biochemical techniques were employed to relate changes in clot elasticity and viscosity to clot structure formation following recalcification of citrate anticoagulated samples. Classical theories of linear viscoelasticity for swollen crosslinked materials were shown to give an excellent estimate of the number of covalent crosslinks per fibrin monomer, which is directly attainable from rheological data.