Biorheology - Volume 27, issue 2

Article Type: Editorial

DOI: 10.3233/BIR-1990-27211

Citation: Biorheology, vol. 27, no. 2, pp. I-III, 1990

Authors: Priel, Z. | Tsoi, A.C.

Article Type: Research Article

Abstract: Mathematical models involving hydrodynamically coupled oscillators are proposed to explain some self-synchronization phenomena observed in flagella and cilia. It is shown using elementary mathematical analysis and computer simulations that the behaviors of the models proposed are similar to those observed in experiment.

Keywords: Cilia, Flagella, Synchronization

DOI: 10.3233/BIR-1990-27201

Citation: Biorheology, vol. 27, no. 2, pp. 125-134, 1990

Authors: Chien, Shu | Feng, Si-shen | Vayo, Margaret | Sung, Lanping A. | Usami, Shunichi | Skalak, Richard

Article Type: Research Article

Abstract: Red blood cell (RBC) rouleaux were formed in a flow channel in the presence of 2 g/dl dextran (molecular weight 76,000). The partial separation of RBC rouleau doublets adhering to the floor of the flow channel in response to small oscillatory shear stresses was observed experimentally. Theoretical analyses on displacement and drag force were performed to determine whether the motion of the cell involves membrane rotation (i.e., rolling) or sliding. From the experimental data and the results of theoretical analyses, it is concluded that, under the conditions of the experiments, the RBCs in a doublet separate from each other by …rolling, rather than sliding of the sheared cell. Show more

Keywords: Aggregation, Erythrocytes, Drag Force, Flow Channel, Shear Stress, Tank-treading

DOI: 10.3233/BIR-1990-27202

Citation: Biorheology, vol. 27, no. 2, pp. 135-147, 1990

Authors: Dintenfass, Leopold

Article Type: Research Article

Abstract: Although the question whether the red cell is fluid or solid has been discussed since 17th century, it was the author’s measurement of the relative viscosity of blood in 1960’s that supplied the first direct evidence that the red cell interior is fluid. Furthermore, through his application of the equations of Taylor and, later, Oldroyd, to this problem, it became evident that, for the red cell to exhibit fluid-drop-like behavior, the membrane must also be fluid. This led to his concept of the red cell membrane as a complex two-phase structure (lipoprotein micelles and two-dimensional protein networks) which was similar …to the one accepted nearly a decade later. The requirements of the theory of ideal emulsions that the shear stress be transmitted into the cell interior via low viscosity membrane, are met in the later work of other investigators using the concept of a tank-treading membrane having viscoelastic properties. This paper reviews the original work of the author which led to the development of an equation for the relative viscosity of blood as a function of volume concentration, C: η r = ( 1 − TkC ) − 2.5 , valid at shear rates above 180 sec−1 , in which T is the Taylor factor which gives a measure of fluidity of the red cell, and k is a plasma trapping factor. Both T and k increase with increasing rigidity of the red cell. Finally, the effect of the membrane viewed as a complex two-phase fluid, on the rheology of the red cell is discussed. Show more

Keywords: red cell, fluid-drop-like behavior, ideal emulsion theory, blood viscosity equation, red cell rigidity parameter, plasma trapping factor, membrane structure, two-phase system, membrane tank treading

DOI: 10.3233/BIR-1990-27203

Citation: Biorheology, vol. 27, no. 2, pp. 149-161, 1990

Authors: Van de Vosse, F.N. | Van Steenhoven, A.A. | Janssen, J.D. | Reneman, R.S.

Article Type: Research Article

Abstract: In the present study a two-dimensional finite element model for incompressible Newtonian flow is applicated to the modelling of carotid artery flow. In earlier studies, the numerical model was validated experimentally for several flow configurations. In general the pulsatile flow is characterized by reversed flow regions at the non-divider side walls of both the internal and external carotid arteries. The unsteadiness of the flow is associated with rather complex spatial and temporal velocity distributions and leads to temporal variations of the location and length of the reversed flow regions. As a consequence, pronounced spatial and temporal variations in the wall …shear stresses are found. At the non-divider side walls, wall shear stresses are relatively low and exhibits an oscillatory behaviour in space and time. At the divider side walls, wall shear stresses are relatively high and approximately follow the flow rate distribution in time. The aim of this study is not only to present two-dimensional calculations but also to compare the calculated two-dimensional velocity profiles with those from three-dimensional experiments. It is observed that in the common carotid artery and in the proximal parts of the internal and external carotid arteries, the two-dimensional numerical model provides valuable information with respect to the three-dimensional configuration. In the more distal parts of especially the internal carotid artery, deviations are found between the two-dimensional numerical and three-dimensional experimental model. These deviations can mainly be attributed to the neglect of the secondary velocity distribution in the two-dimensional model. In the two-dimensional numerical model the influence of a minor stenosis in the internal carotid artery is hardly distinguishable from a minor geometrical variation without stenosis. Full three-dimensional analyses of the influence of minor stenoses are needed to prove numerically whether in-vivo measurements of the axial velocity distribution are useful in the detection of minor stenoses. Show more

Keywords: Biofluidmechanics, carotid artery bifurcation, pulsatile flow, blood flow, finite element analysis, Laser-Doppler anemometry

DOI: 10.3233/BIR-1990-27204

Citation: Biorheology, vol. 27, no. 2, pp. 163-189, 1990

Authors: Wickham, L.L. | Bauersachs, R.M. | Wenby, R.B. | Sowemimo-Coker, S. | Meiselman, H.J. | Elsner, R.

Article Type: Research Article

Abstract: RBC aggregation and viscoelasticity parameters were determined for 40% suspensions of washed cells in autologous plasma from elephant seals (ES), Mirounga angustirostris , ringed seals (RS), Phoca hispida , and swine, (SS), Sus scrofa . Interspecific comparisons including human (HS) blood data revealed unusual rheological properties of seal blood relative to that from pigs or man: 1) RBC aggregation extent, rate and sedimentation were lower for seals (AI=0, ZSR=.40, ESR=0 for RS blood) relative to humans; 2) Viscous (η ′ ) and elastic (η ″ ) components of complex viscosity …(OCRD) were lower for both seal species relative to SS blood, but only at shear rates ⩽ 10 sec−1 (P < 0.05), while η ″ / η ′ ratios for RS blood were lower than HS blood at all shear rates (P < 0.01); 3) Blood viscosity measurements for RS and SS blood from rotational viscometry (Contraves) were consistent with OCRD data; 4) Seal plasma fibrinogen levels were low compared to pigs or humans (RS fibrinogen = -43% v. HS and -57% v. SS; ES fibrinogen = -58% v. HS and -69% v. SS). Electrophoretic mobility of RS red cells was +25% relative to those of humans. These results demonstrate differences in hemorheological indices among mammalian species and suggest the value of comparative rheologic studies. Show more

Keywords: RBC aggregation, viscoelasticity, diving physiology

DOI: 10.3233/BIR-1990-27205

Citation: Biorheology, vol. 27, no. 2, pp. 191-204, 1990

Authors: Iida, Noriko

Article Type: Research Article

Abstract: Flow autoregulation in the arteriolar network serves to maintain the capillary-tissue fluid balance by regulation of capillary pressure. In the present study, we have examined theoretically the effects of arteriolar vasomotion and venous pressure elevation on the capillary fluid exchange, the interstitial fluid pressure, and the interstitial osmotic pressure during capillary pressure regulation. We used Starling’s hypothesis and extended it to include a consideration of a parallel hetero-porous pathway and to determine the effects of plasma protein filtration on interstitial fluid pressure and osmotic pressure. We have found that arteriolar vasomotion plays a primary role in protecting the capillary-tissue fluid …balance during the elevation of capillary flow and that it is a secondary mechanism for the regulation of capillary arterial pressure. Show more

Keywords: hetero-porous membrane, venous pressure, vasomotion, interstitial fluid pressure and osmotic pressure

DOI: 10.3233/BIR-1990-27206

Citation: Biorheology, vol. 27, no. 2, pp. 205-224, 1990

Authors: Qiong, Gao | Pitt, R.E. | Ruina, A.

Article Type: Research Article

Abstract: The effect of intercellular bonding on the stress-strain behavior of soft plant tissue is considered. In our mechanical model, a conglomerate of identical cells is arranged in a regular array. Each cell is pressurized and bonded across flat contact areas with adjacent cells in the direction of the applied load. The cell wall is a finitely-deformed mechanical membrane bounding an incompressible fluid (the cytoplasm). A nonlinear elastic constitutive law is presented that describes data for apple parenchyma. Results show that intercellular bonding has a strong effect on the macroscopic properties of the whole tissue. A larger intercellular contact area increases …tissue stiffness and magnifies the effect of initial turgor pressure on tissue stiffness. Show more

Keywords: plant cells, constitutive relations, middle lamella

DOI: 10.3233/BIR-1990-27207

Citation: Biorheology, vol. 27, no. 2, pp. 225-240, 1990

Authors: Long, Mian | Toyama, Yoshiharu | Dobashi, Toshiaki | Sakanishi, Akio | Wu, Yun Peng | Oka, Syoten

Article Type: Short Communication

Keywords: Erythrocyte sedimentation rate, DC electric field, gelatin gel, swine blood, circuit current

DOI: 10.3233/BIR-1990-27208

Citation: Biorheology, vol. 27, no. 2, pp. 241-246, 1990

Article Type: Announcement

DOI: 10.3233/BIR-1990-27209

Citation: Biorheology, vol. 27, no. 2, pp. 247-251, 1990