Biorheology - Volume 19, issue 1-2

Authors: Fukada, Eiichi

Article Type: Introduction

DOI: 10.3233/BIR-1982-191-211

Citation: Biorheology, vol. 19, no. 1-2, pp. 103-103, 1982

Authors: Wayland, Harold

Article Type: Introduction

DOI: 10.3233/BIR-1982-191-212

Citation: Biorheology, vol. 19, no. 1-2, pp. 105-108, 1982

Authors: Oka, Syoten

Article Type: Other

DOI: 10.3233/BIR-1982-191-213

Citation: Biorheology, vol. 19, no. 1-2, pp. 109-110, 1982

Authors: Silberberg, A.

Article Type: Research Article

Abstract: Steady flow of a multicomponent, incompressible fluid through a connected, solid-like network is considered. ’The network acquires a finite deformation, bears the extra stresses required for mechanical balance, but does not flow. It constitutes at least one thermodynamic component and, in terms of the thermodynamics of irreversible processes, the simplest case of the flow of a binary solution through the network creates a three-component system with three independent cross-coefficients to be determined. The number of coefficients to be determined in the case of more than three components tends to become prohibitive. Hence, the formalism, developed for three components, is often …applied, justifiably and unjustifiably, to practical problems in biology, where the system is much more complex. The conditions under which this is permissible are given and discussed. For such a case, the questions of volume and separation flows is also considered. Relationships are given in terms of the friction coefficients between the components. The important biorheological and thermodynamic role of the matrix is stressed throughout. Show more

Keywords: Poiseuille equation, extra stress in tissue, tissue pressure, separation flow, friction coefficients, reflection coefficient, permeability, diffusion coefficient

DOI: 10.3233/BIR-1982-191-214

Citation: Biorheology, vol. 19, no. 1-2, pp. 111-127, 1982

Authors: Niimi, Hideyuki | Sugihara, Masako

Article Type: Research Article

Abstract: Blood rheology at a stagnation point is studied in views of microhemorheology. Special emphasis is put on the effect of both non-Newtonian and unhomogeneous properties of blood on the fine structure of blood flow impinging on the wall. It is shown that “non-flow” region exists just at the stagnation point due to the non-Newtonian viscosity when its yield stress is large enough, compared with the viscous stress far from the wall. When the yield stress becomes negligibly small, RBC and plasma behave individually near the stagnation point; RBC is deviated from the plasma streamline and impinges on the wall. Finally, …a microhemorheological factor of legional metabolic disorder is discussed on basis of the fine structure near a stagnation point. Show more

Keywords: Microhemorheology, Non-Newtonian viscosity, RBC suspension, Stagnation-point flow

DOI: 10.3233/BIR-1982-191-215

Citation: Biorheology, vol. 19, no. 1-2, pp. 129-136, 1982

Authors: Pai, Bipin K.

Article Type: Research Article

Abstract: The principle of minimum energy of deformation is used to determine the shapes of red cells during micropipette aspiration. Both bending and shear stresses are included in the analysis. The red cell shapes are described by equations with adjustable parameters. The parameters are then used to satisfy the geometrical and mechanical constraints. The geometrical constraints are that the surface area and volume have specific values. The mechanical constraint is that the red cell satisfy the equilibrium criterion that the total energy of deformation is a minimum. A numerical procedure is used to find a variety of shapes satisfying the geometrical …constraints. The total energy of deformation, which is the sum of bending and shear energies, is calculated for each of these shapes. An optimization procedure is then used to determine the shape which has the least energy of deformation. Show more

Keywords: Red blood cells, erythrocytes, micropipette aspiration, red cell membrane, microcirculation

DOI: 10.3233/BIR-1982-191-216

Citation: Biorheology, vol. 19, no. 1-2, pp. 137-141, 1982

Authors: Fukushima, Takayoshi | Azuma, Takehiko

Article Type: Research Article

Abstract: In order to elucidate the fluid dynamic feature of arterial blood flow, the present flow visualization study was carried out with various transparent blood vessel models having a protuberance, a bifurcation, or branchings. The observed flow patterns could be understood in terms of the occurrence of a secondary flow, named the horseshoe vortex. The mode of generation of the horseshoe vortex in a tube with a protuberance projecting into the boundary layer was explained as follows. A radial pressure gradient toward the tube wall was produced along the upstream surface of the protuberance because of the interaction between the viscous …sheared flow and the wall. This pressure gradient made fluid particles turn round downward directly before the obstacle. Then they curled round on themselves and formed a bound vortex tube, the horseshoe vortex, which in turn passed round the front of the protuberance in both directions. In a tube with a Y-shaped bifurcation or rectangular side branch, the flow divider at the branching site acted in place of the protuberance to produce a vortex tube similar in pattern to the horseshoe vortex. The vortex tube extended from the high pressure region, i.e. the apex of the flow divider, to the low pressure region, i.e. the lateral margin of the branch orifice, and generated swirling secondary flows in the main and branched tubes. These results suggested that the following mechanical factors might initiate or facilitate athero- and thrombogenesis: collision of blood cells captured by the horseshoe vortex with blood vessel walls, the interaction of the walls and blood cells due to turbulence, and the occurrence of localized high wall shear stresses. Show more

Keywords: flow visualization, shear stress, turbulence, atherogenesis, thrombogenesis

DOI: 10.3233/BIR-1982-191-217

Citation: Biorheology, vol. 19, no. 1-2, pp. 143-154, 1982

Authors: Matunobu, Y. | Takemitsu, N.

Article Type: Research Article

Abstract: Our previous work demonstrated the fact that the pulsatile flow impinglng on a fixed wall could give rise to enormous wall shear stress for large frequencies. Hence it can be inferred that if the arterial blood flow includes turbulent motion at the sites of bifurcation, stenosis and bend of the vessel, high-frequency velocity components may injure the endothelial lining of the vessel and may be a possible cause of the atherogenesis at these sites. However, the actual vessel wall is by no means a fixed one, but moves, more or less, compliantly according to the intraluminal blood pressure. The present …paper deals with this situation by solving the Navier-Stokes equation of motion, based on an idealized simple model, where two-dimensional pulsatile flow impinges obliquely on a plane wall oscillating normally to its own plane with common frequencies, First the solution for the unsteady flow induced by an oscillating plate on which steady flow is impinging is derived, Then, coordinate transformation of the result makes it possible to estimate the wall shear stress at the mean position of the stagnation point as a function of the common frequency, phase difference and ratio of the amplitudes of oscillation. The results are as follows: (a) The wall shear stress decreases monotonously and tends to the steady value as the frequency increases. This tendency is quite opposite to the case of an unmovable wall. (b) The wall shear stress increases monotonously with increasing phase difference and its amplitude attains a maximum at 180 degrees of difference. For 0 degree of difference which is the most compliant state, it attains a minimum. (c) The wall shear stress becomes larger as the ratio of the amplitudes of pulsating oncoming flow to oscillating wall increases. These conclusions have the physiological significance that the compliant motion of arterial walls may protect the endothelial cells from high-frequency components of turbulent motion. Show more

Keywords: Wall-shear-stress, relaxation, unsteady flow, arterial wall, turbulent motion, Wall shear stress, Stagnation-point flow, Turbulent motion of blood, Compliant motion of vessel wall

DOI: 10.3233/BIR-1982-191-218

Citation: Biorheology, vol. 19, no. 1-2, pp. 155-163, 1982

Authors: Singh, Megha | Vatsala, T.M.

Article Type: Research Article

Abstract: The erythrocyte sedimentation profiles under gravitational field, by scanning the sample holder along the height and width, containing the blood samples with normal and crenated erythrocytes, are determined. The normal shape of erythrocytes has been altered by the controlled He-Ne laser exposures and this change, as observed microscopically, is similar to that as produced by other methods. At low exposure the erythrocytes have normal appearance, whereas, at 400 mJ/cm2 , the percentage of crenated cells is 25 ± 5 percent. It is observed that the modification of the shape influences the sedimentation characteristics of the erythrocytes. The erythrocytes tend to …move faster after being exposed to lower exposure and slower after being exposed to higher exposure compared to that of normal erythrocytes. The possible mechanism associated with this change is discussed. Show more

Keywords: Erythrocytes sedimentation profiles, laser transmitted intensity, acanthocytes, aggregation

DOI: 10.3233/BIR-1982-191-219

Citation: Biorheology, vol. 19, no. 1-2, pp. 165-173, 1982

Authors: Whittington, R.B. | Harkness, J.

Article Type: Research Article

Abstract: The viscometers used were: (a) a proprietary rotational coaxial-cylinder instrument; and (b) a Harkness capillary-tube viscometer. In (a), the mean shear-rate is selected by the choice of rotational speed. In (b), the wall shear-stress is selected by the choice of driving-pressure. If the Viscosity is varied, the mean shear-rate varies, at constant wall shear-stress. The present paper attempts to show how, in principle, a complete family of “constant-rate” (rotational) curves can be computer-plotted from two suitably-spaced capillary-tube measurements. The reverse process, involving the correction of “playback” errors, is touched upon. A variable “Einstein coefficient” is derived from the …principal parameters in the computer solution; and the basic problems of compatibility in “rates of shear” are discussed. Show more

Keywords: Viscosity, haematocrit, shear

DOI: 10.3233/BIR-1982-191-220

Citation: Biorheology, vol. 19, no. 1-2, pp. 175-184, 1982

Authors: Mitaku, Shigeki | Aruga, Shuji

Article Type: Research Article

Abstract: Elastic properties of dipalmitoyl phosphatidylcholine bilayers were studied by an ultrasonic technique as a function of the concentration of calcium ion. The ultrasonic velocity showed a broad minimum at about 10 mM CaCl2 , indicating that the bulk modulus of membrane is smallest at this calcium ion concentration. Since the amount of calcium ions adsorbed to the membrane monotonously increases, calcium ions have two kinds of effects on the phosphatidylcholine membrane, namely softening effect at lower concentration and hardening at higher concentration. It is suggested that the softening is due to some structural change of hydrated water and the hardening …is due to chelation of lipid molecules by adsorbed calcium ions. The estimation of bulk modulus and Young’s modulus revealed that Young’s modulus and rigidity are much smaller than the bulk modulus even in the gel phase. Show more

Keywords: Calcium ion, mechanical properties, Lipid bilayer membrane

DOI: 10.3233/BIR-1982-191-221

Citation: Biorheology, vol. 19, no. 1-2, pp. 185-196, 1982

Authors: Masuda, Hirotake | Kikuchi, Yoshitomo | Nemoto, Tetsu | Bukhari, Abda | Togawa, Tatsuo | Kamiya, Akira

Article Type: Research Article

Abstract: To study the morphological changes in the endothelial surface of the artery induced by wall shear stress load, an arterio-venous shunt was constructed between the common carotid artery and the external jugular vein in 21 dogs. The ultrastructural changes in the endothelial surface were observed by scanning electron microscopy after the measurement of the hemodynamic parameters. In acute experiments (3 days or 1 week postoperative), the clear ultrastructural changes, such as the disturbance of the smooth folds, the fine transverse wrinkles, the small spindle swellings, the splitting of the intercellular junction of the endothelial cells and occasionally the desquamation of …the endothelial cells, were significantly observed as proportional to the elevated flow rate ratio (fs/fc, fs: flow rate of the shunted artery, fc: flow rate of the control artery). In subacute experiments (2 or 4 weeks postoperative), the small spindle swellings were observed in the shunted artery with high flow rate ratio. In chronic experiments (5 or 6 months postoperative), these changes were less proportional to the flow rate ratio. These morphological changes were significant in the disturbance of the endothelial barrier in acute experiments and they were significant in adaptive regulatory change in the chronic experiments. These support our previous observation (Am. J. Physiol. 239, H14-21, 1980). The possibility of the wall shear stress for atherogenesis was discussed. Show more

Keywords: wall shear stress, carotid artery, arterio-venous shunt, scanning electron microscopy, endothelial cell, atherosclerosis

DOI: 10.3233/BIR-1982-191-222

Citation: Biorheology, vol. 19, no. 1-2, pp. 197-208, 1982

Authors: Tokita, Masayuki | Hikichi, Kunio | Niki, Ryoya | Arima, Shunrokuro

Article Type: Research Article

Abstract: The reaction order of the clotting process of milk-rennet system was determined by an analysis of clotting curves obtained from the measurement of the complex rigidity at various concentrations of milk and rennet under the conditions of fixed weight ratio of rennet to milk. The results obtained show that the clotting process of milk-rennet system after gelation begins is described by a single first order reaction. At constant weight ratio of rennet to skim milk, it was found that G ∞ ′ increases almost linearly with increasing temperature. Under the conditions of a …constant milk concentration and temperature, the latent period is inversely proportional to the enzyme concentration and the rate constant of gelation is proportional to the enzyme concentration. These results were discussed in terms of Payens’ theory of enzymatic clotting processes and Ziff’s theory of the kinetics of polymer gelation. Show more

Keywords: Casein Micelle, Chymosin, Complex Rigidity, Smoluchowski’s Rate Equation

DOI: 10.3233/BIR-1982-191-223

Citation: Biorheology, vol. 19, no. 1-2, pp. 209-219, 1982

Authors: Koyama, Tomiyasu | Kikuchi, Yuji | Horimoto, Masashi | Kakiuchi, Yoshihiro | Tsushima, Nobuko | Nitta, Junko

Article Type: Research Article

Abstract: The flow behaviors of white blood cells (WBCs) in frog’s pulmonary microvessels were recorded and analyzed by means of a microscope-TV camera system. When the flow velocity in arterioles was reduced to a level lower than 1 mm/sec by a moderate overinflation of the exposed lung, WBCs rolled on the endothelial surface, frequently came in contact with the capillary orifice and passed it quickly without deformation. The time length which was required for WBCs to pass through the capillary orifice was shorter than the time length for red blood cells. This observation suggested that WBCs were no hinderance to blood …delivery from arterioles to the capillary network in the normal and moderate overinflation of the lung. However, when the lung was strongly overinflated and the center line flow velocity was reduced to 0.1 mm/sec, WBCs adhered to the endothelium in ten minutes. The adhering WBCs could not be detached by the recovery of the blood flow. It seemed probable that a large shear stress up to 100 to 200 dynes/cm2 was necessary to pull down the interaction between the adhering WBCs and the endothelium. Show more

Keywords: white blood cells, adhesion to endothelium, pulmonary microvessels, shear stress, bullfrog

DOI: 10.3233/BIR-1982-191-224

Citation: Biorheology, vol. 19, no. 1-2, pp. 221-228, 1982

Authors: Niimi, Hideyuki

Article Type: Meeting Report

DOI: 10.3233/BIR-1982-191-225

Citation: Biorheology, vol. 19, no. 1-2, pp. 229-230, 1982

Authors: Scott Blair, George W.

Article Type: Introduction

DOI: 10.3233/BIR-1982-191-226

Citation: Biorheology, vol. 19, no. 1-2, pp. 231-235, 1982

Authors: Rogausch, H.

Article Type: Research Article

Abstract: The relative viscosity of normal red cell suspensions is independent of temperature at high shear rates. The relative viscosity of suspensions with normovolemic sphered erythrocytes having a reduced deformability, however, is higher at 37°C than at 20°C. It is concluded that the changes of the lipoprotein configuration within the erythrocyte membrane which are proposed to be involved in the disc-sphere-transformation of the red cell, depend on temperature and are responsible for the increased relative viscosity at 37°C.

Keywords: Erythrocyte deformability, temperature, disc-echinocyte transformation

DOI: 10.3233/BIR-1982-191-227

Citation: Biorheology, vol. 19, no. 1-2, pp. 237-244, 1982

Authors: Singh, Megha | Muthukrishnan, V.

Article Type: Research Article

Abstract: The hemorheological characteristics of the blood samples, obtained by venepuncture from various groups of patients, are determined. Shear stress-shear rate relationship were determined by capillary viscometer at various shear rates ranging from 1 sec−1 to 30 sec−1 . Erythrocyte sedimentation rate (ESR) was determined by Westergren method. The results indicate that at constant hematocrit, the slope of the line representing shear stress-shear rate relationship, and ESR of blood samples change, depending on the clinical conditions of the individuals. For various values of the hematocrits, the variation of the above mentioned parameters along with fibrinogen level & blood viscosity, in …various diseases are given. Show more

Keywords: Shear stress-shear rate, Erythrocyte sedimentation rate, Fibrinogen, Hematocrit, Diseases

DOI: 10.3233/BIR-1982-191-228

Citation: Biorheology, vol. 19, no. 1-2, pp. 245-252, 1982

Authors: Chan, Thao | Jaffrin, M.Y. | Seshadri, V. | McKay, C.

Article Type: Research Article

Abstract: Apparent viscosity and mean channel hematocrits have been measured at various shear rates and feed hematocrits for red blood cell (RBC) suspensions flowing in two-dimensional channels. Three types of RBC were used in the suspensions: normal, partially hardened by heating at 50°C and completely hardened by glutaraldehyde fixation. Channel height was varied from 20 to 200 μ and feed hematocrit from 5 to 55 %. Measurements show that RBC deformability plays a dominant role in narrow channels and viscosity increases rapidly with decreasing cell deformability. Like in narrow tubes the apparent viscosity as well as the mean channel hematocrits …decrease as the channel height is reduced. However the apparent viscosity in a channel remains slightly higher than the viscosity in a tube of diameter equal to the channel height. These results are consistent with the existence of a cell-depleted layer near the channel walls. Show more

Keywords: Blood viscosity, erythrocyte deformability

DOI: 10.3233/BIR-1982-191-229

Citation: Biorheology, vol. 19, no. 1-2, pp. 253-267, 1982

Authors: Duszyk, Marek | Doroszewski, Jan

Article Type: Research Article

Abstract: Adhesion to glass and silicone-coated surface of leukemia cells (L1210 and L5222) and their motion on an inclined plane have been investigated. The cells in quiescent fluid are subjected to the action of gravitational force: its component parallel to the surface ranges from 4.0 × 10−14 N to 4.5 × 10−13 N. The prolonged action of the gravitational force at 45° (3.3 × 10−13 N) causes the separation from the substratum of numerous cells which have adhered on a horizontal plane. When the cells passively move on the slope they are frequently arrested by adhesion which is partly …short-lived. The analysis of the leukemia cell velocity reveals good agreement with the theory describing the motion of a sphere in quiescent fluid. The translation movement of nucleated cells on an inclined plane is not, however, accompanied by rotation. On the other hand, the cells flowing in mid-stream rotate with an angular velocity predicted by the theory. Show more

Keywords: leukemia cells, inclined plane, quiescent fluid, adhesion, velocity, rotation

DOI: 10.3233/BIR-1982-191-230

Citation: Biorheology, vol. 19, no. 1-2, pp. 269-279, 1982

Authors: Dimicoli, J.L. | Nakache, M. | Péronneau, P.

Article Type: Research Article

Abstract: A new method is developed for direct visualization of the local mass transfer at solid liquid interfaces. Peroxidase is immobilized by entrapment in a polyacrylamide gel coating the interior surface of a glass tube. The reaction of oxidation of luminol by H2 O2 catalyzed by this enzyme involves light emission. Furthermore at low H2 O2 concentration (≲ 5. × 10−5 M), this reaction is controlled by the diffusion of H2 O2 from the bulk flow to the wall, as evidenced by the Re1/3 dependence of the light flux V measured in the laminar case. It is …possible in these conditions to directly relate V as measured at each point of the wall, to the local properties of the flow: (i) a decrease of V is always observed when moving downstream from the input of the tube, but it is much more pronounced for laminar flows than for turbulent ones, as theoretically expected; (ii) the sensitivity of the method has been tested for evaluating the diffusion convection phenomena at the wall downstream from a stenosis. Furthermore the local hydrodynamic properties have been characterized by measuring through pulsed Doppler velocimetry the velocity of the moving liquid phase as a function of the position in the flow. The data obtained show the presence of a maximum of V in the vicinity of the reattachment point of the liquid streamlines at the wall. This constitutes the first experimental confirmation of calculations on diffusion convection phenomena downstream from stenoses. These first experiments show one the ability of the method to detect the local properties of the parietal mass transfer phenomena, as a function of the geometry of the wall and the hydrodynamic characteristics of the flow. Show more

Keywords: Diffusion convection, visualization, chemiluminescent enzymatic immobilized system

DOI: 10.3233/BIR-1982-191-231

Citation: Biorheology, vol. 19, no. 1-2, pp. 281-300, 1982

Authors: Stanwyck, T. Scott | Fischer, Richard | Pope, Malcolm | Seligson, David

Article Type: Research Article

Abstract: Pilot studies showed the occurrence of stress relief when a sawcut was made in cortical bone next to a foil strain gauge. In these experiments, strain gauges were cemented on the surface of bovine metatarsals or ovine tibiae to determine if the observed residual strain was an artifact caused by strain gauge application or by stress relief procedures. A consistent stress relief was recorded lending further support to the concept that bone is a prestressed material.

Keywords: Prestress, Hydroxyapatite, Collagen, Bone

DOI: 10.3233/BIR-1982-191-232

Citation: Biorheology, vol. 19, no. 1-2, pp. 301-306, 1982

Authors: Walburn, Frederick J. | Stein, Paul D.

Article Type: Research Article

Abstract: The purpose of this study was to determine the shear rate at the wall in a symmetrically branched tube with a branch-to-trunk area ratio and angle of branching that were comparable to the human abdominal aorta. Velocity profiles were measured with a laser Doppler anemometer during steady and pulsatile flow in which the mean Reynolds numbers were 500, 1000, and 1500. During both steady and pulsatile flow, as the Reynolds numbers increased, the shear rates at the inner wall of the branch increased. Only slight increments of the shear rates occurred along the outer wall of the branch, however, as …the Reynolds number increased. No reversal s of flow were observed at any Reynolds number during steady flow. Transient reversals of flow (causing negative shear rates) occurred along the outer wall of the branch at a Reynolds number of 500; but such transient flow reversals were not observed at the higher Reynolds numbers during pulsatile flow. Show more

Keywords: Shear rate, transient flow reversals, laser Doppler anemometry

DOI: 10.3233/BIR-1982-191-233

Citation: Biorheology, vol. 19, no. 1-2, pp. 307-316, 1982

Authors: Jackson, Graham W. | James, David F.

Article Type: Research Article

Abstract: An experimental system was developed to measure flow rates and pressure drops across hyaluronic acid solutions. The solutions were contained r:y membranes in a test cell, and solvent was perfused through the cell at flow rates comparable to physiological conditions. The pressure drop was found to be proportional to a steady flow rate for concentrations up to 1.5%, confirming that Darcy’s Law for porous media is valid for hyaluronic acid solutions (and indicating that the polymer chains did not pile up at one end of the test cell). From the flow data, the hydrodynamic permeability of each solution was calculated …and found to be 50 times higher that whole tissue having the same hyaluronic acid concentration; hyaluronic acid on its own, therefore, is not the source of resistance to flow in tissue. The results for hyaluronic acid were then used to show that all the glycosaminoglycans together cannot cause the high resistance of ground substance in tissue, and it is argued that mucoproteins are the most likely source. A hydrodynamic model of the polymer chains was developed to predict solution permeability; the theoretical values agree closely with the experimental data. Show more

Keywords: Hydrodynamic resistance, permeability, hyaluronic acid, Darcy’s Law

DOI: 10.3233/BIR-1982-191-234

Citation: Biorheology, vol. 19, no. 1-2, pp. 317-330, 1982

Authors: Sharikov, Alexander N. | Zaiko, Valery M.

Article Type: Research Article

Abstract: During the recent years various investigators have developed the technique of kryophotometric measurements of oxyhemoglobin saturation with oxygen (Ψ) in small vessels. In this paper, on the basis of the statistical model of the organ developed by the authors, a theoretical relationship is established between the distributions of measured in various groups of experiments in the capillaries and the distributions of Ψ in the arterioles and venules. It is shown that for the description of the distribution of Ψ in a separate multicapillary unit, lying between the arteriole and the venule, it is possible to introduce a special distribution function. …In some cases this function may be determined analytically. Statistical distributions of other microcirculation parameters may be included into the statistical model of the organ using the similar procedure described in this paper for the parameters Ψa , Ψv -arteriolar and venular Ψ. Show more

Keywords: Microcirculation, Oxygen transport

DOI: 10.3233/BIR-1982-191-235

Citation: Biorheology, vol. 19, no. 1-2, pp. 331-339, 1982

Authors: Ramcharan, J.E. | Shoja, H.S. | Piggott, M. | Taylor, D.E.M.

Article Type: Research Article

Abstract: It has long been established that vibration can produce vasospastic disease with associated hyperviscosity. More recently it has been shown that short-term exposure to vibration may lead to increased blood-flow; the associated blood rheology of this has not been studied. The vibration used in this study was of the three dimensional type known as “cycloid” vibration. It is often used in physiotherapy departments and is therefore of particular interest. Investigations have been carried out to determine the effects on blood-viscosity at shear rates between 230 s−1 and 0.0734 s−1 of whole-body vibration, at a frequency of 50 Hz …for 15 minutes in the rabbit and of the effects of in vitro vibration on both human and rabbit blood. Haematocrit, yield stress, erythrocyte electrophoretic mobility and zeta-potential were also estimated. Three studies were carried out:- I. Comparison of blood with and without in vitro vibration from human volunteers with hyperviscosity (N = 5). II. Comparison of blood from lop-eared rabbits before and after whole-body vibration (N = 11). III. Comparison of blood from lop-eared rabbits after in vitro vibration and after whole-body vibration (N = 10). The frequency of vibration was 50 Hz, the amplitude was 0.8 mm and the duration was 15 minutes. It was shown that vibration of either human or rabbit blood in vitro has no effect on blood-viscosity at any shear rate, on red cell mobility, on zeta-potential or on yield stress. Whole-body vibration produced no significant effect on rheology at rates of shear above 2 s−1 , but low-shear viscosity (<1 s−1 Shear rate) became more nearly Newtonian after vibration, with a significant reduction in yield stress from 5.71 ± 0.14 mNm−2 to 3.54 ± 0.32 mNm−2 (p < 0.005). There were no significant changes in electrophoretic mobility (i.e. zeta-potential). Show more

Keywords: Vibration, Blood-Viscosity, Red Cell Mobility

DOI: 10.3233/BIR-1982-191-236

Citation: Biorheology, vol. 19, no. 1-2, pp. 341-352, 1982

Authors: Gaillard, S. | Delhon, A. | Laurresergues, H. | Stoltz, J.F.

Article Type: Research Article

Abstract: The essential part played by rheological factors in genesis of thrombosis and atherosclerosis has often been mentioned. Thus the authors have carried out a study of rheological and biochemical parameters on a genetic animal model with modifications in plasma lipids (homozygous obese “Fatty” rat) compared to the non obese heterozygous animal. The results obtained for the evolution of biochemical parameters (blood glucose, cholesterol, triglycerids) over a 16 months period confirm those published earlier. Further, a significant increase in fibrinogen level was observed in homozygous animals, and correlated with plasma viscosity. These results are also connected with changes in apparent …blood viscosity which is considerably increased in homozygous rats, particularly at low shear rates (γ ˙ < 20 s−1 ). These results show the value of this animal model and the authors suggest the application of such a genetic animal model and of its heterozygous control population to both theoretical rheological and pharmacological studies on atherogenesis and hyperlipoproteinaemia. Show more

Keywords: hemorheology, animal model, Fatty rat, fibrinogen

DOI: 10.3233/BIR-1982-191-237

Citation: Biorheology, vol. 19, no. 1-2, pp. 353-362, 1982

Authors: Kiesewetter, H. | Radtke, H. | Jung, F. | Schmid-Schönbein, H. | Wortberg, G.

Article Type: Review Article

Abstract: The question whether blood exhibits pseudoelastic behavior i.e. if it behaves like a solid under negligible external forces, is of great theoretical interest for the clarification of stasis phenomena in the microcirculation. The determination of yield point, that is the change from the solid to the fluid phase, was at first only of abstract scientific importance for blood. In the diagnosis and treatment of patients with flow anomalies this phenomenon is increasingly important, as numerous possibilities now exist to modify the flow behavior of blood by therapeutical changes of composition. Therefore it seems to be of high priority to review …and discuss the numerous methods for the quantification of a yield shear stress. Show more

Keywords: Yield shear stress, Rotational viscometer, Capillary viscometer, Sedimentation, Plug flow, Microcirculation

DOI: 10.3233/BIR-1982-191-238

Citation: Biorheology, vol. 19, no. 1-2, pp. 363-374, 1982

Article Type: Abstract

DOI: 10.3233/BIR-1982-191-239

Citation: Biorheology, vol. 19, no. 1-2, pp. 375-382, 1982

Authors: Church, Michael J.

Article Type: Announcement

DOI: 10.3233/BIR-1982-191-240

Citation: Biorheology, vol. 19, no. 1-2, pp. 383-383, 1982