Biorheology - Volume 11, issue 5

Authors: Taylor, M.G.

Article Type: Obituary

DOI: 10.3233/BIR-1974-11501

Citation: Biorheology, vol. 11, no. 5, pp. 313-314, 1974

Authors: Jackson, Julius L. | Oplatka, Avraham

Article Type: Research Article

Abstract: Equations of motions for the z -bands of a striated muscle in isometric tetanus arc written. The different kinds of forces acting on the z -bands arc considered and their properties discussed. Included arc the mechanochemical force, a damping force, and a spring force. The relevant statistical averages that one must calculate in order to compare theory with experiment are identified. By way of illustration the model is solved for the simplest non-trivial case, that wherein damping and inertial affects are neglected. For this case the basic qualitative features are: (1) the mean square fluctuation of the inter-sarcomere distance is …a minimum at the center of a muscle; (2) the mean square fluctuation of a z -bands about its average position is a maximum at the center of the muscle; (3) the mean square fluctuations of z -band positions and intersarcomere distances are greater for longer muscles. Show more

DOI: 10.3233/BIR-1974-11502

Citation: Biorheology, vol. 11, no. 5, pp. 315-322, 1974

Authors: Puchelle, E. | Zahm, J.M.

Article Type: Research Article

Abstract: Les auteurs ont étudié l’influence de l’espace-mort existant à la base des cylindres coaxiaux du rhéomètre rotatif “Rotovisko” Haake type Couette, sur les mesures des propriétés rhéologiques de l’expectoration. L’effet es[ace-mort, classiquement appelé effet-bout (end-effect), s’est révélé affecter considérablement les mesures de recouvrance, en entraînant une surestimation hautement significative des valeurs. Dans le but d’éliminer cet artéfact expérimental, l’appareillage a été modifié de façon à imposer une vitesse de déformati on uniforme à l’intérieur de l’espace de mesure. La modification apportée à la géométrie initiale présente l’avantage d’adapter un appareillage simple à l’étude rigoureuse de la recouvrance des …fluides visco-élastiques tels que l’expetoration. Show more

DOI: 10.3233/BIR-1974-11503

Citation: Biorheology, vol. 11, no. 5, pp. 323-330, 1974

Authors: Williams, A.R.

Article Type: Research Article

Abstract: The shear stress required to liberate a given quantity of haemoglobin (e.g. τ 50 per cent) from human erythrocytes was increased as the osmotic strength of the suspending medium was decreased. The position and/or shape or each haemolysis profile was changed in a characteristic and reproducible manner, suggesting that this technique might be of value in diagnostic haematology. Sugars and their derivatives which entered the cell rapidly, increased τ 50 per cent marc than similar sugars which entered very slowly. Both apparent “protection” effects described above are due to an increase in erythrocyte volume, which in turn affects the nature …of the cell’s interaction with the applied shear field. Show more

DOI: 10.3233/BIR-1974-11504

Citation: Biorheology, vol. 11, no. 5, pp. 331-336, 1974

Authors: Kholeif, Ismail A. | Weymann, Helmut D.

Article Type: Research Article

Abstract: To study the rotation and shearing deformation of a single red blood cell (RBC) in simple shear flow, a two-dimensional hydrodynamic calculation in the creeping flow approximation is made. The model particle is assumed to have a fixed shape resembling the actual cross section of an RBC. In plane polar coordinates (r ,ψ ) the cross section of the particle is described by r = a ( 1 + p cos 2 ψ ). The model cell is assumed to be bounded by an infinitesimally thin. inextensible, and completely flexible membrane and to contain a Newtonian fluid …of viscosity μ i , inside. The cell is suspended in another Newtonian fluid of viscosity μ o . The only allowed motion of the membrane is along the perimeter of the cell such that the shape of cell is not changed. In the Stokes approximation a biharmonic expansion of the stream function is obtained both in the interior and the exterior. For the deformable cell, the period of rotation and the amplitude of the displacement of the membrane are found to rise sharply with an increase in the ratio μ o /μ i . At a certain ratio, depending on the parameter p , the motion ceases to be periodic, and the cell settles at a stationary orientation with its major axis inclined at an angle less than 45° to the direction of now, while the membrane remains in continuous motion around the interior. The existence of two modes of motion is in agreement with experimental observations. Show more

DOI: 10.3233/BIR-1974-11505

Citation: Biorheology, vol. 11, no. 5, pp. 337-348, 1974

Authors: Marikovsky, Y. | Danon, D.

Article Type: Research Article

Abstract: Polylysine (pLys) agglutinates old red blood cells (RBC) at a higher rate than young ones. A gradual decrease in surface negative charge increases first the rate of agglutination due to lessen- ing of mutual repulsion. Further removal of surface charge results in decline of agglutinability because of insufficient binding sites for pLys. Two factors play a role in the agglutination by pLys: (1) the density of attachment sites; and (2) the mutual repulsion between cells.

DOI: 10.3233/BIR-1974-11506

Citation: Biorheology, vol. 11, no. 5, pp. 349-350, 1974

Authors: Singh, Megha | Balakrishnan, S.

Article Type: Research Article

Abstract: The viscosity of blood varies with tube radius, viscosity of suspending medium, flow amplitude, hematocrit, and frequency, under oscillatory flow conditions. Various factors affecting the viscosity of blood were related by an empirical relation. The viscosities calculated from this relation show good agreement with the experimental and Kline Allen’s theoretical results.

DOI: 10.3233/BIR-1974-11507

Citation: Biorheology, vol. 11, no. 5, pp. 351-353, 1974

Authors: Hartert, H.

Article Type: Research Article

Abstract: Rheo-Simulation is a method to simulate extracorporeally in vivo blood flow. It is done by “shaking” the cup of the thrombelastograph with a very small precessional movement. The radian of this movement is about 0,030 mm with a frequency of about 45 Hz. So the surface speed of the Rheo-Simulation cup is 9.5 mm/sec, resembling the velocity of blood flow in a vein. Native blood or citrated and recalcified plasma in the thrombelastograph, subjected to Rheo-Simulation during the clotting process, will clot as a very sudden event. Presumably this occurrence will be due to some extent to a new …form of clotting, according to Copley’s theory, viz. the aggregation of fibrinogen in polymolecular layers both on the cup and on the rod of the measuring device which finally and suddenly grow together. The structure of this clot is relatively independent on the presence of platelets, but strongly dependent on the presence of plasma clotting factor XIII. Its total lack will, even in the presence of platelets, not allow any clot formation in the plasma subjected to Rheo-Simulation. Plasma factor XIII in an amount of 1 per cent is sufficient to allow for a normal clot structure in the Rheo-Thrombelastogram (Rheo-TEG). Show more

DOI: 10.3233/BIR-1974-11508

Citation: Biorheology, vol. 11, no. 5, pp. 355-360, 1974

Authors: Kline, Kenneth A. | Schmid-Schönbein, Holger

Article Type: Research Article

Abstract: An estimate of red cell membrane strain is applied to the case of a dilute suspension of osmotically inflated near spherical red cells subjected to shear. The wall shear stress is related to maximum membrane strain, and predictions of theory arc compared to experimental results on hemolysis of Champion et al . (Biorheology , 8 (1971), 23). It appears membrane strain energy at hemolysis is a function of the ratio of cell to suspending fluid viscosity, so long as membrane properties are unaltered by the nature of the suspending fluid. This is seen to bc in agreement with Taylor’s …(Proc. R. Soc. Lond. Ser. A. 146 (1934), 501) results on the hurst of liquid drops. An attempt is made to compare the conditions for hemolysis obtaining in steady shear flow with those of oscillatory shear. The analytical results appear to be consistent with reported observations concerning the time dependent nature of hemolysis. Show more

DOI: 10.3233/BIR-1974-11509

Citation: Biorheology, vol. 11, no. 5, pp. 361-374, 1974

Authors: Aiache, J.M. | Molina, Cl.

Article Type: Research Article

DOI: 10.3233/BIR-1974-11510

Citation: Biorheology, vol. 11, no. 5, pp. 375-383, 1974