Biorheology - Volume 9, issue 2

Article Type: Other

DOI: 10.3233/BIR-1972-9201

Citation: Biorheology, vol. 9, no. 2, pp. 49-49, 1972

Authors: LaCelle, P.L.

Article Type: Research Article

Abstract: The deformability of sphered erythrocytes produced in vitro by fragmentation loss of membrane in a glass micropipette or by heating at 48°C has been compared to spheres in metabolically depleted blood and in spheres from blood bank blood by measuring the pressure for passage through a 2.8-μ micropipette. Progressive membrane loss increased deforming pressure from 9.0 ± 0.4 mm H2 O for control cell to 190 ± 21 for cell fragmented in two steps by the micropipette and 120 ± 20 for heat-fragmented cells as compared to 405 ± 39 for metabolically depleted cells and 203 ± 9 …for cells stored 8 weeks in acid citrate dextrose (ACD) solution at 4°C. The volume of the micropipette fragmented cells, heat-induced spheres and blood bank cells were less than control erythrocytes (78 μ 3 , 82 μ 3 and 79 μ 3 vs 87 μ 3 ) and volume of the metabolically depleted cells did not differ from control. The loss of deformability in the fragmentation induced spheres appears to be related to sphericity; in blood bank spheres it is thought to relate to membrane loss and abnormal intracellular ATP/Ca2+ , and in the metabolically depleted cells which have not lost membrane area, rigidity is thought to be due to Ca2+ -induced contraction of membrane proteins and gel transition of proteins at the inner membrane surface as ATP is depleted. Chlorpromazine, known to increase membrane surface area, did not reverse the rigidity of the spheres. Show more

DOI: 10.3233/BIR-1972-9202

Citation: Biorheology, vol. 9, no. 2, pp. 51-59, 1972

Authors: Lynn, N.S. | Fox, V.G. | Ross, L.W.

Article Type: Research Article

Abstract: The two-dimensional steady state Navier-Stokes equations have been solved for branching flow, with parabolic entering flow profile. The results yield streamlines that agree well with experiment, and vorticity profiles that are sufficient to explain the migration of suspended particulates to the outer wall, in agreement with the observations of numerous investigators.

DOI: 10.3233/BIR-1972-9203

Citation: Biorheology, vol. 9, no. 2, pp. 61-66, 1972

Authors: Skalak, R. | Chen, P.H. | Chien, S.

Article Type: Research Article

Abstract: Computational results are presented for a model of capillary blood flow consisting of red-cell shaped particles suspended in a Newtonian fluid. The red cells are assumed to be axisymmetrically located in a circular tube and to maintain their biconcave disk shape during the motion. The cells are equally spaced along the tube and the motion is assumed to be sufficiently slow to make inertial terms negligible. The results show that the apparent viscosity is linear in the hematocrit at low hematocrits, but increases less rapidly at high hematocrits due to trapping of fluid between cells. The effect of rouleaux is …to slightly decrease the apparent viscosity. The most important parameter in determining the apparent viscosity is the ratio of the diameter of the red cells to capillary diameter. Show more

DOI: 10.3233/BIR-1972-9204

Citation: Biorheology, vol. 9, no. 2, pp. 67-82, 1972

Authors: Larcan, A. | Stoltz, J.F. | Vigneron, C. | Streiff, F.

Article Type: Research Article

Abstract: L’étude des paramètres d’hémolyse au cours de la conservation du sang prélevé sur ACD montre une évolution de ceux-ci entraînant une “fragilisation” des hématies. Les conséquences rhéologiques sont envisagées.

DOI: 10.3233/BIR-1972-9205

Citation: Biorheology, vol. 9, no. 2, pp. 83-85, 1972

Authors: Winet, Howard | Jahn, Theodore L.

Article Type: Research Article

Abstract: Fluid instability in cultures of Tetrahymena pyriformis termed “bioconvection” [Science 133 , 1766, 1961] was examined during various stages of population growth. Subsurface swarms and sedimenting droplets or vertical columns of cells were observed microscopically and macroscopically. Analyses of their establishment, persistence and internal dynamics support the hypothesis that (1) bioconvection by such cells may be explained as a precipitation of a randomly formed subsurface region R of swarming cells that achieves a certain minimum width (0.3 cm) density contrast (2 × 10−4 g/cm3 ) between itself and the underlying fluid and sedimentation velocity (0.07 …cm/sec). (2) viscous instability then shapes the falling R into a vertical column. Show more

DOI: 10.3233/BIR-1972-9206

Citation: Biorheology, vol. 9, no. 2, pp. 87-104, 1972

Authors: Halikas, George C.

Article Type: Research Article

Abstract: Studies of rheological properties of blood of temperate zone mammals including man has revealed that there is little species difference. One Arctic animal, the reindeer (Rangifer tarandus ) exhibits an elevated blood viscosity, especially at low temperatures. Possibly this property, which tends to reduce blood flow, is a part of a heat conservation mechanism.

DOI: 10.3233/BIR-1972-9207

Citation: Biorheology, vol. 9, no. 2, pp. 105-113, 1972

Article Type: Announcement

DOI: 10.3233/BIR-1972-9208

Citation: Biorheology, vol. 9, no. 2, pp. 115-118, 1972

Article Type: Other

DOI: 10.3233/BIR-1972-9209

Citation: Biorheology, vol. 9, no. 2, pp. 119-123, 1972

Article Type: Other

DOI: 10.3233/BIR-1972-9210

Citation: Biorheology, vol. 9, no. 2, pp. 124-124, 1972