Biorheology - Volume 25, issue 1-2

Authors: Saito, N. | Moro, K. | Ito, K.

Article Type: Research Article

Abstract: The Brownian motion of a spherical particle in a generalized viscoelastic medium is discussed to obtain the complex viscosity coefficient from the photocurrent correlation function of fluorescent light radiated from the particle. This method makes it possible to measure the viscoelastic properties of a small amount of solution sample.

Keywords: Fluorescence correlation spectroscopy, Viscoelastic medium, Generalized Langevin equation

DOI: 10.3233/BIR-1988-251-220

Citation: Biorheology, vol. 25, no. 1-2, pp. 129-135, 1988

Authors: Hartert, H.

Article Type: Research Article

Abstract: Sudden increase of viscosity in former times indicated the start of coagulation. Yet its measurement destroyed the structure of coagulum. By the precursor method of thrombelastography the author 1944 found elasticity to be the essential physiological property of coagulum. In the production of elastic fibrin structure its early phase is the most efficient in this respect. The speed of prime structure formation is extremely fast in presence of enough phospholipid as well as of plasma factor XIII. Even high amounts of thrombin cannot replace one or both of these substances indispensable to grow rapidly a perfect fibrin web. This phase …yet does not become effective if it is not accompanied by the orbital micro-flow of the new orbitometry method. Its shear is comparable to that in a coronary artery. The special resonance effect of the method in combination with the early phase of fibrin production is generating some kind of a physiological feed back: increasing fibrin will strengthen shear stress as long as less platelets are entangled which will reduce the elastic flexibility of fibrin web. Some kind of a “coagulation spin effect” in optimal combination of shear stress, phospholipid and factor XIII, will extremely fast originate a firm fibrin structure, a mechanism which may be of significance for a fast occlusion of arterial stenoses. Show more

Keywords: Fibrin elasticity, orbitometer, resonance, coagulation spin effect, early phase fibrin

DOI: 10.3233/BIR-1988-251-221

Citation: Biorheology, vol. 25, no. 1-2, pp. 137-145, 1988

Authors: Hasegawa, Masamitsu | Watanabe, Yoshio

Article Type: Research Article

Abstract: The tension-strain, stress-strain and stress relaxation curves of longitudinal and circumferential strips of proximal thoracic aortas in normal and WHHL rabbits of different ages were determined using a tensile testing instrument. Wall distensibility of longitudinal and circumferential strips was the greatest in the normal aorta and decreased with advancing age in the atherosclerotic aorta. The wall thickness of the atherosclerotic aorta was positively related to age with a correlation coefficient of 0.66 (p<0.01). The incremental elastic moduli calculated from the stress-strain curves increased with advancing age in the atherosclerotic aorta. Accordingly, the decreased distensibility of the atherosclerotic wall may be …due to the increased wall thickness caused by the intimal thickening as well as to the increase in wall stiffness caused by the increased elastic modulus. The viscoelasticity of the atherosclerotic aorta was larger than that of the normal aorta. This reflects the mechanical effect of atherosclerotic changes that occurred in the thickened intima. Show more

Keywords: Stress-strain curve, Stress relaxation curve, Elastic modulus, Atherosclerosis, Intimal thickening

DOI: 10.3233/BIR-1988-251-222

Citation: Biorheology, vol. 25, no. 1-2, pp. 147-156, 1988

Authors: Dobashi, Toshiaki | Goto, Hiroshi | Sakanishi, Akio | Oka, Syoten

Article Type: Research Article

Abstract: We have measured the sedimentation curves of swine erythrocytes in a physiological saline solution in inclined glass tubes. The curves are well fitted to the exponential type equation ı = a [ 1 − exp ( − bt ) ] for the tilt angle θ in the range of θ < 80° and hematocrits from 10 to 50 %, where ı and t are the medium length along the tube and the elapsed time from the sample injection, respectively. The coefficient a increases with θ and b is proportional to …sin θ . The erythrocyte sedimentation rate ESR(θ ) = (dı /dt)t → 0 determined from the above empirical equation increases with the increase in sin θ roughly linearly. The experimental results are discussed with reference to the Ponder-Nakamura-Kuroda theory and some recent theories. Show more

Keywords: Erythrocyte sedimentation rate, swine blood, tilt angle dependence, physiological saline solution

DOI: 10.3233/BIR-1988-251-223

Citation: Biorheology, vol. 25, no. 1-2, pp. 157-164, 1988

Authors: Sakanishi, Akio | Hasegawa, Masamitsu | Dobashi, Toshiaki

Article Type: Research Article

Abstract: The stress-strain curves of the vena cava have been measured of vena cava superior, and the intrathoracic and abdominal portions of vena cava inferior excised from dogs. The stress σ is expressed by the exponential function of the strain γ as follows: σ = σ 0 [ exp ( γ / γ 0 ) − 1 ] in the longitudinal direction, and σ = σ 1 [ exp ( γ / γ 1 ) − 1 ] …+ σ 2 [ exp ( γ / γ 2 ) − 1 ] in the circumferential one for all the three kinds of veins. The constants σ 0 , γ 0 , σ 1 , γ 1 , σ 2 and γ 2 are determined by a nonlinear least squares method. Show more

Keywords: Distensibility, Stress-strain curves, Nonlinear elasticity, Caval veins, Exponential formulae

DOI: 10.3233/BIR-1988-251-224

Citation: Biorheology, vol. 25, no. 1-2, pp. 165-172, 1988

Authors: Shimura, Sanae | Sasaki, Tsukasa | Sasaki, Hidetada | Takishima, Tamotsu | Umeya, Kaoru

Article Type: Research Article

Abstract: Dynamic viscoelastic properties of 13 bronchorrhoea sputum samples from asthmatics with bronchorrhoea, defined as the production of watery sputum of 100 ml or more per day during asthmatic attacks, were examined and then compared with 7 saliva and 12 mucoid sputum samples obtained from patients during remission. Dynamic viscosity (η ′ ) and elasticity (G′) of bronchorrhoea sputum increased rapidly with time up to 2 hours after collection and slowly thereafter, whereas η ′ and G′ of saliva and mucoid sputum remained unchanged up to 6 hours after collection. …Then, η ′ and G′ of saliva, bronchorrhoea and mucoid sputum samples were measured between 2 to 4 hours after expectoration. Bronchorrhoea sputum samples showed significantly larger values at frequencies of both 0.1 and 1.0 rad/sec than did saliva samples and also significantly smaller values than did mucoid sputum samples. Thus, bronchorrhoea sputum differed in dynamic viscoelastic properties from saliva, indicating that it does not result from hypersalivation. Based on data of viscoelastic changes with time, it can be assumed that the viscoelasticity of bronchorrhoea sputum in the airways is considerably less than the optimal range reported previously for mucociliary velocity, suggesting the possibility of impaired mucociliary transport. Show more

Keywords: bronchial asthma, bronchorrhoea sputum, dynamic viscoelasticity

DOI: 10.3233/BIR-1988-251-225

Citation: Biorheology, vol. 25, no. 1-2, pp. 173-179, 1988

Authors: Skalak, Richard | Sugihara-Seki, Masako

Article Type: Research Article

Abstract: The hydrodynamic interaction of a red blood cell and a white blood cell in microvessels is studied, by use of a two-dimensional numerical model. The red blood cell, modeled as a small rigid circular cylinder, and the white blood cell, modeled as a larger rigid circular cylinder, are immersed in an incompressible Newtonian fluid in a two-dimensional channel. It is assumed that no external force or moment acts on the model cells, and the effect of inertia forces on the motion of the fluid and the cells is neglected. The velocity field of the suspending fluid and the instantaneous velocities …of the two model cells are computed by the finite element method. Using the translational velocities of the model cells obtained, the trajectories of their relative motion arc determined, for various initial positions. It is shown that the cells may or may not pass each other or separate, depending on the initial positions. The present results compare well to the experimental results. Show more

Keywords: red blood cell, white blood cell, hydrodynamic interaction, channel flow

DOI: 10.3233/BIR-1988-251-226

Citation: Biorheology, vol. 25, no. 1-2, pp. 181-189, 1988

Authors: Takaki, R. | Kurihara, T.

Article Type: Research Article

Abstract: Flow of Latex suspension with high concentration between plate glasses was observed through an optical microscope. Size of aggregates of Latex particles was estimated by measuring area of a region without particles behind an obstacle in the flow region (this technique had been developed by one of the authors). At the same time, viscosity and elasticity of the suspension were measured by a cone-plate viscometer, and relations between the aggregate size and these properties were obtained. A simple model based on the Stokes law of resistance and the Maxwell model for viscoelastic materials is proposed to explain these relations. The …theoretical results agree with the present experiment. Show more

Keywords: Aggregate, Suspension, Viscosity, Elasticity, Hele-Shaw flow

DOI: 10.3233/BIR-1988-251-227

Citation: Biorheology, vol. 25, no. 1-2, pp. 191-198, 1988

Authors: Chaturani, P. | Narasimman, S.

Article Type: Research Article

Abstract: Mathematical models for blood flow in cone-plate viscometer have been considered, by assuming blood as a Casson/Herschel-Bulkley fluid. Three different cases have been analyzed (i) when there is no shearing, (ii) partial shearing and (iii) full shearing. The relationships between the angular velocity and torque have been obtained for the above three cases. By assuming total shearing, the analytical expression for apparent viscosity has been obtained. Variation of apparent viscosity with yield stress, angular velocity, Casson co-efficient of viscosity, consistency index and flow behaviour index has been computed. It is observed that as the angular velocity increases, the apparent viscosity …decreases for both fluids. Further, it is found that as the cone angle increases, the apparent viscosity increases. This behaviour of apparent viscosity in cone-plate viscometer is interesting and unexpected and is being reported first time. Show more

Keywords: Blood rheology, viscometers, non-Newtonian fluids, mathematical modelling

DOI: 10.3233/BIR-1988-251-228

Citation: Biorheology, vol. 25, no. 1-2, pp. 199-207, 1988

Authors: Walitza, E. | Anadere, I. | Chmiel, H. | Witte, S.

Article Type: Research Article

Abstract: The dependence on hematocrit of whole blood viscoelasticity must be considered in order to compare pathological blood samples to normal ones. If one wants to calculate the measured values to a standard hematocrit value, the hematocrit dependence for the pathological sample must be available. As the latter however is unknown, the same dependence is assumed for both normal and pathological blood samples. To prove the validity of this assumption, hematocrit dependence of random blood samples from different diseases (cerebral and coronary vascular and myocardial disorders) were investigated. A statistical analysis showed the assumption as invalid. Therefore, it will be recommended …to evaluate pathological blood samples at the measured hematocrit. Show more

Keywords: Blood viscoelasticity, hematocrit, reference values

DOI: 10.3233/BIR-1988-251-229

Citation: Biorheology, vol. 25, no. 1-2, pp. 209-217, 1988