Biomaterial Database

Effect of temperature dependent changes in mechanical stability of red cell aggregates on relative apparent whole blood viscosity. 1987

F J Neumann, and H Schmid-Schönbein, and H Malotta

Abt. Physiologie, RWTH Aachen, F. R. Germany.

As the temperature dependence of relative apparent whole blood viscosity eta rel is still controversial, the relation between the temperature dependence of red cell aggregation (RCA) and that of eta rel was examined in normal donors and in patients with venous ulcers of the leg. Apparent whole blood viscosity was measured in the DEER-rheometer (0.01 Pa less than tau less than 2.9 Pa) at 10 degrees C, 20 degrees C, 30 degrees C and 37 degrees C. The instrument was calibrated for each temperature to correct for changes in viscometer geometry. Simultaneously the minimal shear stress tau Tmin to keep RCA dispersed was determined by photometric aggregometry. eta rel was found to increase with decreasing temperature. By basing the relative cold induced increase in eta rel on the state of RCA as defined by the ratio of tau/tau Tmin the relation between both features is verified: With increasing RCA the cold induced increase in eta rel is progressively enhanced.

UI	MeSH Term	Description	Entries
D007871	Leg Ulcer	Ulceration of the skin and underlying structures of the lower extremity. About 90% of the cases are due to venous insufficiency (VARICOSE ULCER), 5% to arterial disease, and the remaining 5% to other causes.	Leg Ulcers,Ulcer, Leg,Ulcers, Leg
D001809	Blood Viscosity	The internal resistance of the BLOOD to shear forces. The in vitro measure of whole blood viscosity is of limited clinical utility because it bears little relationship to the actual viscosity within the circulation, but an increase in the viscosity of circulating blood can contribute to morbidity in patients suffering from disorders such as SICKLE CELL ANEMIA and POLYCYTHEMIA.	Blood Viscosities,Viscosities, Blood,Viscosity, Blood
D004903	Erythrocyte Aggregation	The formation of clumps of RED BLOOD CELLS under low or non-flow conditions, resulting from the attraction forces between the red blood cells. The cells adhere to each other in rouleaux aggregates. Slight mechanical force, such as occurs in the circulation, is enough to disperse these aggregates. Stronger or weaker than normal aggregation may result from a variety of effects in the ERYTHROCYTE MEMBRANE or in BLOOD PLASMA. The degree of aggregation is affected by ERYTHROCYTE DEFORMABILITY, erythrocyte membrane sialylation, masking of negative surface charge by plasma proteins, etc. BLOOD VISCOSITY and the ERYTHROCYTE SEDIMENTATION RATE are affected by the amount of erythrocyte aggregation and are parameters used to measure the aggregation.	Erythrocyte Aggregation, Intravascular,Agglutination, Intravascular,Intravascular Agglutination,Intravascular Erythrocyte Aggregation,Rouleaux Formation, Erythrocyte,Agglutinations, Intravascular,Aggregation, Erythrocyte,Aggregation, Intravascular Erythrocyte,Aggregations, Erythrocyte,Aggregations, Intravascular Erythrocyte,Erythrocyte Aggregations,Erythrocyte Aggregations, Intravascular,Erythrocyte Rouleaux Formation,Erythrocyte Rouleaux Formations,Formation, Erythrocyte Rouleaux,Formations, Erythrocyte Rouleaux,Intravascular Agglutinations,Intravascular Erythrocyte Aggregations,Rouleaux Formations, Erythrocyte
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures