Biorheology - Volume 15, issue 3-4

Article Type: Correction

DOI: 10.3233/BIR-1978-153-422

Citation: Biorheology, vol. 15, no. 3-4, pp. I-XXXV, 1978

Article Type: Correction

DOI: 10.3233/BIR-1978-153-401

Citation: Biorheology, vol. 15, no. 3-4, pp. 143-143, 1978

Article Type: Announcement

DOI: 10.3233/BIR-1978-153-402

Citation: Biorheology, vol. 15, no. 3-4, pp. 145-145, 1978

Authors: Gaehtgens, P. | Albrecht, K.H. | Kreutz, F.

Article Type: Research Article

Abstract: Glass capillaries (I.D. 15–95 μ m) were perfused with red cell suspensions in buffered Ringer’s solution using driving pressures which corresponded to wall shear stresses between 5 and 400 dynes/cm2 . The hematocrit within the capillaries (HT ), in the discharge reservoir (HD ), and in the feed reservoir (HF ) as well as the volume flow rate through the capillaries were determined. It was observed that variation of flow rate resulted in significant changes of the screening effect (HD /HF < 1) and the Fahraeus effect (HT /HD < 1): cell screening increased and the Fahraeus effect …decreased upon reduction of volume flow rate (μ ¯ -values ranging from 10 to 103 sec−1 ). The combined effect of both mechanisms resulted in an increase of capillary hematocrit with decreasing flow rate. It is concluded that cellular overvelocity increases with shear stress due to shear-dependent axial concentration of flowing red cells. Show more

DOI: 10.3233/BIR-1978-153-403

Citation: Biorheology, vol. 15, no. 3-4, pp. 147-154, 1978

Authors: Gaehtgens, P. | Albrecht, K.H. | Kreutz, F.

Article Type: Research Article

Abstract: Suspensions of human red blood cells were drawn through glass capillaries (I.D. 15–95 μ m). The suspending medium contained high molecular weight dextran to induce extensive red cell aggregation. The effect of changes in flow rate on the Fahraeus effect and red cell screening was studied by determining capillary hematocrit (HT ), discharge hematocrit (HD ), feed hematocrit (HF ), and the volume flow rate through the capillaries. It was found that the flow dependence of cell screening was intensified compared to the results obtained in the absence of dextran. Furthermore the Fahraeus effect showed an inversed flow dependence: in …the range of low flow rates (u ¯ below 200 sec−1 ) reduction of flow rate resulted in a decrease of the ratio HT /HD indicating more pronounced dynamic hematocrit reduction within the capillary. Calculations of the cell-free layer of suspending medium near the tube wall showed values ranging between 10 and 30% of the tube radius (corresponding to a width between 1 and 7 μ m) depending on the diameter of the tube. The cell-free wall layer was found to increase both at low flow rates (due to increased cell aggregation) and at high flow rates (due to axial migration of disaggregated cells). Show more

DOI: 10.3233/BIR-1978-153-404

Citation: Biorheology, vol. 15, no. 3-4, pp. 155-161, 1978

Authors: Born, G.V.R. | Melling, A. | Whitelaw, J.H.

Article Type: Research Article

Abstract: Laser Doppler anemometry has been applied to the measurement of the local velocity of blood flowing in venules and in small-diameter glass tubes. As a consequence, the capabilities and limitations of the technique, for this purpose, are identified and quantified. It is shown that multiple scattering, absorption and wave front distortion preclude precise measurements at haematocrit values near those of whole blood. The location of measurement in round capillaries is impossible to identify with satisfactory resolution and it is suggested that the application of the technique, for local measurements, should be limited to plane channels with ghost cells or blood …of low haematocrit: in addition, approximate measurements of the integrated velocity can probably be obtained with whole blood in tubes of small diameter, say less than 50 μ m. Show more

DOI: 10.3233/BIR-1978-153-405

Citation: Biorheology, vol. 15, no. 3-4, pp. 163-172, 1978

Authors: Collins, R. | Kivity, Y.

Article Type: Research Article

Abstract: Shock-like waves are generated in fluid-filled silastic tubes, and their amplitudes recorded as a function of position and time. A simple theory is formulated for the steady-state “shock-structure”, based on a mathematical analogy with gas-dynamic shock waves. Comparison with the experimental results provides a general method for the evaluation of the dynamic rheology of viscoelastic biological vessels. The existence of shock-like propagation is seen to depend upon the form of the input pressure signal and most critically upon its maximum rate of rise dp/dt.

DOI: 10.3233/BIR-1978-153-406

Citation: Biorheology, vol. 15, no. 3-4, pp. 173-179, 1978

Authors: Vera, J.C. | Lefort, M.F. | L’Huillier, J.P. | Stoltz, J.F.

Article Type: Research Article

Abstract: Cette étude utilise une technique d’analyse spectrale basses fréquences, en temps réel, des signaux Doppler fournis par un débitmètre ultrasonore à émission continue. Les écoulements permanents réalisés sont engendrés, dans un tube viscoélastique, cylindrique circulaire, sur un banc de simulation hydrodynamique. La chaîne de mesures, comportant les différents capteurs et le système d’analyse, est brièvement. décrite. Les spectres d’amplitude des signaux Doppler servent de support aux informations concernant les paramètres caractéristiques des écoulements permanents (nombre de Reynolds ou vitesse moyenne débitante), quelqu’en soit la nature, laminaire ou turbulent.

DOI: 10.3233/BIR-1978-153-407

Citation: Biorheology, vol. 15, no. 3-4, pp. 181-191, 1978

Authors: Chaturani, P. | Upadhya, V.S.

Article Type: Research Article

Abstract: A method has been developed for the study of the pulsatile flow of a couple stress fluid (blood) through circular tubes. The first, second and third approximate solution for flow velocity, wall shear, flow rate and relative viscosity have been obtained in closed form in terms of couple stress parameter α ¯ and η ¯ , pulsatile Reynolds number α , phase ϕ and time factor nt. The velocity and flow rate variations with different parameter have been shown graphically which indicate that they are almost in phase with the …pressure gradient. Further, a method has been suggested to determine experimentally the value of pulsatile Reynolds number α for blood. The effects of the parameters α ¯ , η ¯ , α , ϕ and nt on relative viscosity have been discussed. It is found that the theoretical results, obtained by the present analysis, are in good agreement with the experimental and other theoretical results on blood flow. Show more

DOI: 10.3233/BIR-1978-153-408

Citation: Biorheology, vol. 15, no. 3-4, pp. 193-201, 1978

Authors: Urban, J.P.G. | Holm, S. | Maroudas, A.

Article Type: Research Article

Abstract: By comparing results obtained in vivo on penetration of (35 S) sulphate and (3 H) methyl glucose into the intervertebral disc of adult dogs, with those calculated using Fick’s law, and diffusion and partition coefficients obtained in vitro , diffusion was shown to be the main mechanism for transport of small solutes into the intervertebral disc. About 40 percent of the endplate area was found to be permeable to small solutes. However the amount of solute entering via the endplate was shown to be less for negatively charged solutes such as the sulphate ion, than for neutral solutes …such as glucose, because of charge exclusion in the region of the nucleus. The mean turnover time of 470 days found for sulphated glycosaminoglycans in the disc is similar to that reported for dog articular cartilage. Show more

DOI: 10.3233/BIR-1978-153-409

Citation: Biorheology, vol. 15, no. 3-4, pp. 203-223, 1978

Authors: Meiselman, Herbert J.

Article Type: Research Article

Abstract: Using human RBC suspended in buffer, the rheologic effects of the discocyte-ecllinocyte shape transformation have been studied via cone-plate and Couette viscometry. An isovolumic shape change, induced by nitrophenols or a substituted benzoate, results in altered flow behavior: 1) low shear rate viscosity is increased in relation to the degree of echinocyte formation; 2) at high shear rates, the rheologic behavior, regardless of initial cellular morphology, is nearly identical to normal, biconcave RBC. Restoration of the biconcave shape, in the presence of the echinocytic agent, returns the rheologic behavior toward control over the entire range of shear rates. The rheologic …changes appear to be related to increased cell-cell interaction enhanced by the echinocyte form. Correlations with other studies describing RBC shape changes are discussed. Show more

DOI: 10.3233/BIR-1978-153-410

Citation: Biorheology, vol. 15, no. 3-4, pp. 225-237, 1978

Authors: Thurston, George B.

Article Type: Research Article

Abstract: The influence of hematocrit on the viscoelasticity of human blood is examined in two contexts. First, the viscosity and elasticity vs shear rate is determined at 2 Hertz using blood from a single donor, reconstituted at hematocrits ranging from 0 to .95. The viscosity changes approximately exponentially with hematocrit for both low shear rates, γ ˙ < 1 sec−1 , and at higher shear rates, γ ˙ = 10 sec−1 . For hematocrits near .45, both viscosity and elasticity changes are well described by a power curve, viscosity being …near the second and elasticity being near the third power of hematocrit. Second, statistical analysis of a group of normal male donors shows a similar power curve dependence on hematocrit. A procedure for compensation for hematocrit differences among donors is described. It is applied to obtain normal values for viscosity and elasticity at two shear rates for the group. Under the conditions of testing and for a hematocrit of .45, the mean values for viscosity at 1 and 10 −1 are .114P and .085P, respectively, while the corresponding elasticities are .045P and .019P. Show more

DOI: 10.3233/BIR-1978-153-411

Citation: Biorheology, vol. 15, no. 3-4, pp. 239-249, 1978

Authors: Meban, C.

Article Type: Research Article

Abstract: Pulmonary surfactant was removed from the lungs of rabbits by bronchial lavage and then purified by a foam fractionation procedure. Surfactant films were adsorbed on the surface of buffered saline and a dipping plate and electrobalance were used to measure the changes in surface tension as the film areas were increased at known rates. The resulting data were used to compute the coefficient of dilatational viscosity of each film. It was found that the dilatational viscosity of the films decreased as their surfactant concentration was increased. Increasing the temperature over the range 25–41°C produced a modest increase in the viscosity …but altering the subphase pH had no significant effect. These findings help to elucidate certain aspects of the behaviour of pulmonary surfactant films. Show more

DOI: 10.3233/BIR-1978-153-412

Citation: Biorheology, vol. 15, no. 3-4, pp. 251-259, 1978

Authors: Bornstein, Alan A. | Chen, Tzeng-Ming | Dulfano, Mauricio J.

Article Type: Research Article

Abstract: The role of disulfide bonds in determining the viscoelastic properties of sputum was examined in chronic bronchitic patients during acute exacerbation and recovery. Significantly higher levels of disulfide, DNA and solid concentration were characteristic of sputum in the acute as compared to the recovery phase. At the fixed concentration of solids and pH used during viscoelastic measurements, no correlation was found between DNA concentration and viscoelasticity. However, a significant correlation was found between disulfide concentration and viscoelastic measurements in samples of both phases when the original concentration of solids in sputum was above 3.5%.

DOI: 10.3233/BIR-1978-153-413

Citation: Biorheology, vol. 15, no. 3-4, pp. 261-267, 1978

Authors: Chen, T.-M. | Dulfano, M.J.

Article Type: Research Article

Abstract: The effect of lyophilization and reconstitution on the viscosity of sputum was studied under various conditions of freezing and storage. The results indicate that: 1) the procedure produces a material of uniform rheological characteristics and 2) that preservation of the original viscosity depends on the nature of the sample. Thus, in mucoid sputum the viscosity is well preserved when the fresh sample is frozen and stored at −78°C and then lyophilized and reconstituted to the original concentration of solids. In mucopurulent samples the same could be obtained at either −78°C or −198°C, whereas neither of the above temperatures could prevent …a decrease of viscosity in frankly purulent sputum samples. Show more

DOI: 10.3233/BIR-1978-153-414

Citation: Biorheology, vol. 15, no. 3-4, pp. 269-275, 1978

Authors: Klip, Willem | Janicki, Joseph S. | Klip, Dorothea A. | Reeves, Russell C.

Article Type: Research Article

Abstract: The calculations leading to an energy density function for heart muscle encompassing both elastic and contractile properties are explicitly given. The function has two variables Q (measuring deformation) and Qc (measuring contraction). The time dependence of the contraction variable (Qc ) was found to be largely independent of preload and afterload. This increases the possibility of its clinical determination and that of the constants in the energy density function for diagnostic and prognostic purposes.

DOI: 10.3233/BIR-1978-153-415

Citation: Biorheology, vol. 15, no. 3-4, pp. 277-293, 1978

Authors: Ohshima, Norio

Article Type: Research Article

Abstract: The kinematic study of red blood cell (RBC) deformation in the clinical and experimental extracorporeal circulation was carried out in the light of hemorheological parameters such as hemolysis, whole blood viscosity and RBC osmotic fragility. Results obtained suggest that the rate of hemolysis depends strongly on the mechanical factors, namely, it increases as the blood flow increases. While, from the measurements of whole blood viscosity and RBC osmotic fragility, it seemed that the sub-hemolytic changes of the structure of the red blood cell membrane is also accompanied by the mechanical destruction of the red blood cells. Clinical implications of …these hemorheological changes of blood components in the extracorporeal circulation were also discussed. Show more

DOI: 10.3233/BIR-1978-153-416

Citation: Biorheology, vol. 15, no. 3-4, pp. 295-302, 1978

Authors: Rogausch, H. | Kaffarnik, H. | Schubotz, R. | Mühlfellner, G. | Schneider, J.

Article Type: Research Article

Abstract: Lysolecithin induces a disc-echinocyte transformation at the moment of contact with normal red cells. This is accompanied by a transient increase in the viscosity of red-cell suspensions, which returns spontaneously to normal during prolonged contact with lysolecithin. Since metabolic processes of the red cell are involved in the normalization of viscosity, the term “red-cell adaptation” is used for this property. The present paper shows that red-cell adaptation to lysolecithin is absent in hyperlipemic patients. In addition, 25% of the latter had less deformable red cells in freshly drawn venous blood samples. Interpretation of the mechanisms involved in red-cell adaptation and …its failure leads to the assumption that there may be a link between reversible (by lysolecithin) and irreversible (in venous blood) reductions of red-cell deformability. Show more

DOI: 10.3233/BIR-1978-153-417

Citation: Biorheology, vol. 15, no. 3-4, pp. 303-310, 1978

Authors: Heuser, G.

Article Type: Research Article

Abstract: If one wants to use cone and plate viscometers to study the influence of shear stress on blood damage in low viscosity suspending media, then one platen has to be rotated at high speed. In this case centrifugal forces can no longer be neglected and they influence the flow conditions within the shearing regions. A solution for the radial pressure distribution is obtained. There is a good agreement between theoretical and experimental pressure distributions for Newtonian fluids. But the experimental results for blood show marked deviations from the Newtonian behaviour. Measuring the rate of haemolysis it is found that it …depends distinctly on the gap width. The forces acting on the erythrocytes produce a shift in concentration in radial direction, which is detected by measuring the haematocrit values and is calculated by a balance of forces. Show more

DOI: 10.3233/BIR-1978-153-418

Citation: Biorheology, vol. 15, no. 3-4, pp. 311-320, 1978

Authors: Yee, James P. | Mel, Howard C.

Article Type: Research Article

Abstract: Normal human erythrocytes undergoing abrupt osmotic hemolysis display a single, transient, localized circular rupture over 15 to 20% of their total surface area. An immediate and striking drop in apparent volume for such cells, as measured by electronic “sizing” using resistive pulse spectroscopy (RPS), is ascribed primarily to a greatly increased, flow-induced, cell-membrane deformation and associated expulsion of ghost contents rather than to an intrinsic property of hemolysis per se . The time and flow-rate dependence of the RPS spectra measure the rates of ghost formation and repair of the hemolytic lesion in the membrane. Restored ghosts rehemolyze at a …critical volume and lesion size similar to those of the original lysing cells. Membrane rather than cytoplasmic (internal viscosity) properties dominate deformability measured from RPS spectral shape. Show more

DOI: 10.3233/BIR-1978-153-419

Citation: Biorheology, vol. 15, no. 3-4, pp. 321-339, 1978

Authors: Stoltz, J.F. | Renaud, M. | Gaillard, S. | Streiff, F.

Article Type: Research Article

DOI: 10.3233/BIR-1978-153-420

Citation: Biorheology, vol. 15, no. 3-4, pp. 341-345, 1978

Article Type: Abstract

DOI: 10.3233/BIR-1978-153-421

Citation: Biorheology, vol. 15, no. 3-4, pp. 347-353, 1978