Biorheology - Volume 22, issue 4

Article Type: Editorial

DOI: 10.3233/BIR-1985-22409

Citation: Biorheology, vol. 22, no. 4, pp. I-III, 1985

Authors: Matrai, A. | Reid, H. | Bogar, L. | Flute, P.T. | Dormandy, J.A.

Article Type: Research Article

Abstract: The role of different factors contributing to red cell filterability in the Hemorheometre has been investigated. Although the original method uses a small volume of suspension to determine red cell filterability, the present experiments showed that the results obtained are still significantly affected by filter clogging. Consequently a change 1n filterability could be due to a change in filter clogging possibly by residual leucocytes. An adaptation of filter chamber and filling method is described, resulting 1n a simpler and faster measuring procedure. The inaccuracy in measuring low haematocrits contributes significantly to experimental errors. Therefore a definition of red cell filterability …based on the red cell count (instead of haematocrit) of the suspension is suggested. Show more

Keywords: red cells, deformability, filtration, filter clogging

DOI: 10.3233/BIR-1985-22401

Citation: Biorheology, vol. 22, no. 4, pp. 275-284, 1985

Authors: Jeje, Ayodeji A.

Article Type: Research Article

Abstract: The relationships between the geometric characteristics of, the local flow rates of xylem sap in, and relative pressures in the reticulate anastomosing vascular network of dicotyledonous leaves of Populus Balsamifera L. are reported. The conducting channels of cellulosic microcapillaries are covered by sheaths of chloroplast free cell s through the walls of which water withdrawn from vascular bundles percolates to reach evaporation sites. Along the mid-rib and branch generations, the population and cross-section areas of the microcapillaries decrease with distance but not in a monotonic manner. Lateral withdrawal rates from the veins were highest at the base of the …leaf lamina. More than 50% of the inlet stream had dispersed out of the conduits within the first 25% of the leaf lamina area from the petiole junction. Absolute values of pressure gradients generally decreased in the apical direction along the vein. Show more

Keywords: Fascicular flow, vascular network, dicotyledonous leaves

DOI: 10.3233/BIR-1985-22402

Citation: Biorheology, vol. 22, no. 4, pp. 285-302, 1985

Authors: Chaturani, P. | Pralhad, R.N.

Article Type: Research Article

Abstract: A steady laminar flow of blood in a uniform tapered tube has been examined. Blood rheology is assumed to be described by a polar fluid. The analytical expressions for velocities (both axial and radial), total angular velocity, wall shear and pressure drop have been obtained. In literature, the parameters N (coupling number) and L (length ratio) have been chosen independently. But, in the present analysis, it is found that they are interrelated. Variation of the flow variables with suspension concentration and tapered angle have been investigated. Some of the theoretical models for the flow through tapered tubes have been critically …examined. The pressure-flow relationship has been studied numerically over the flow rate range 0.01–0.1 cc/sec and compared with experimental results. It has been shown that the existing experimental results are for the tapered tubes of larger diameter which correspond to the flow under Newtonian conditions. Finally, some biological implications and future developments of this theory have been indicated. Show more

Keywords: Blood flow, Tapered tube, Blood rheology

DOI: 10.3233/BIR-1985-22403

Citation: Biorheology, vol. 22, no. 4, pp. 303-314, 1985

Authors: Oka, Syoten

Article Type: Research Article

Abstract: A new physical theory of erythrocyte sedimentation is proposed. Various assumptions underlying Stokes’ formula are first criticized. An explicit formula is proposed, taking into account some of the results of recent experimental investigations including the effect of upward flow of plasma and the time course of growth of aggregates. It is generally shown that the sedimentation curve without aggregation never becomes a sigmoid. Our formula is applicable to the increased ESR due to the aggregation of erythrocytes. The sedimentation velocity depends not only on the hematocrit and the ultimate size of the aggregates, but also on the retardation. time of …the growth of aggregates in conformity with the experimental result of Kernick et al. Show more

Keywords: Erythrocyte sedimentation rate, Stokes’ formula, erythrocyte aggregation

DOI: 10.3233/BIR-1985-22404

Citation: Biorheology, vol. 22, no. 4, pp. 315-321, 1985

Authors: Kon, K. | Kon, H.

Article Type: Research Article

Abstract: The electron paramagnetic resonance (EPR) spin label method was used to investigate the effect of varying hematocrit on the deformation and orientation behavior of erythrocytes in shear flow. The relative EPR spectral change due to flow, which we use as a measure of the average deformation and orientation of erythrocytes, was observed as a function of the hematocrit. The profile generally shows a rising and a declining phase with the maximum in-between. The position of the maximum with respect to the hematocrit and the level of the spectral change are influenced by the suspending medium viscosity, osmolarity, and depend upon …modifications of the red cell properties such as the internal viscosity, area-to-volume ratio and membrane rigidity. Results show that there is an upper limit of free deformation and orientation of the cell for a given hematocrit value. A possible role of the cell-cell interaction is discussed in restricting the space around a cell which is required for free deformation and orientation. A significance of the findings is that the actual deformation and orientation of an ensemble of cells which give rise to the EPR spectral change in flow is determined not only by the single cell deformability but also by the way the cells interact with each other under a given fluid dynamic condition. Show more

Keywords: Spin label, Erythrocyte, Deformation, Orientation, Shear flow, Cell-cell interaction

DOI: 10.3233/BIR-1985-22405

Citation: Biorheology, vol. 22, no. 4, pp. 323-333, 1985

Authors: Tran-Son-Tay, Roger | Nash, Gerard B. | Meiselman, Herbert J.

Article Type: Short Communication

Keywords: Erythrocyte Analysis, Membrane Viscoelasticity, RBC Deformation

DOI: 10.3233/BIR-1985-22406

Citation: Biorheology, vol. 22, no. 4, pp. 335-340, 1985

Authors: Fukada, Eiichi

Article Type: Book Review

DOI: 10.3233/BIR-1985-22407

Citation: Biorheology, vol. 22, no. 4, pp. 341-341, 1985

Article Type: Abstract

DOI: 10.3233/BIR-1985-22408

Citation: Biorheology, vol. 22, no. 4, pp. 343-376, 1985