Biorheology - Volume 28, issue 1-2

Authors: Silberberg, Alex | Copley, Alfred L.

Article Type: Editorial

DOI: 10.3233/BIR-1991-281-201

Citation: Biorheology, vol. 28, no. 1-2, pp. 1-1, 1991

Authors: Seaman, G.V.F.

Article Type: Obituary

DOI: 10.3233/BIR-1991-281-202

Citation: Biorheology, vol. 28, no. 1-2, pp. 3-7, 1991

Authors: Hung, T.C. | Butter, D.B. | Yie, C.L. | Sun, Z. | Borovetz, H.S. | Kormos, R.L. | Griffith, B.P. | Hardesty, R.L.

Article Type: Research Article

Abstract: The rheological properties of blood were studied in patients supported by both the Jarvik-7 total artificial heart (TAH) and Novacor left ventricular assist device (LVAD) as a bridge to cardiac transplantation. Both groups of patients had abnormalities in blood rheology which differed according to the type of device implanted as well as on the clinical state of the patient. The rheology of individual patients correlated well with their clinical status and outcome, with incidences of TIA’s and/or stroke being accompanied by marked increases in relative blood viscosity, erythrocyte rigidity, fibrinogen concentration and platelet aggregation in varying combination. Observed abnormalities in …blood rheology were also crucial to thrombus formation on artificial heart valves as well. Our results show that the therapeutic management of rheological parameters should prove to be a unique and clinically rewarding approach to these patients. Show more

Keywords: blood rheology, artificial heart, blood viscosity, erythrocyte rigidity, platelet aggregation, transient ischemic attack

DOI: 10.3233/BIR-1991-281-203

Citation: Biorheology, vol. 28, no. 1-2, pp. 9-25, 1991

Authors: Charcosset, C. | Ding, L.R. | Jaffrin, M.Y.

Article Type: Research Article

Abstract: Plasma fractionation by membrane filtration permits the reinfusion of the patient with his own albumin. In this study, the influence of membrane nature and plasma flux on plasma fractionation in dead-end mode is investigated with acetate hollow fiber filters. It is found that transmembrane pressure TMP rises exponentially with time, the rate of increase being proportional to plasma flux. The faster TMP rises, the faster the drop in sieving coefficient SC. It is also found that albumin SC is a function of TMP and not of plasma flux. Theoretical analysis of the dead-end filtration was performed. This theoretical model indicates …that the observed variation of TMP with time is consistent with the assumptions that pore volume decreases proportionally to the filtrate plasma volume. Show more

Keywords: membrane plasma fractionation, dead-end filtration, membrane nature effect

DOI: 10.3233/BIR-1991-281-204

Citation: Biorheology, vol. 28, no. 1-2, pp. 27-37, 1991

Authors: Liepsch, D. | Thurston, G. | Lee, M.

Article Type: Research Article

Abstract: We studied several non-Newtonian fluids to determine how closely they simulate the flow behavior of human blood. The viscous and viscoelastic properties of these fluids were compared with human blood samples in steady flow and transient flow Couette viscometers and in an oscillatory tube flow viscoelasticity analyzer. We examined: 1) A polyacrylamide suspension (Separan AP30 and AP45) to which we added 4% isopropanol and 0.01% magnesium chloride. 2) A suspension of 2% Dextran with 16% by weight biconcave disc-shaped particles simulating red blood cells. 3) 40% ghost cells prepared according to Dodge in Tri(hydroxymethyl) aminomethane. These ghost …cells were used to simulate the two-phase flow behavior of blood. 4) A suspension of 5% Dextran (70000) with 12% polystyrene particles (diameter of 1 μ m) and 10 mMol calcium chloride. All these fluids closely approximate the flow behavior of blood and can be used in a variety of different experimental situations. To measure velocity distribution using a laser-Doppler-anemometer, we used fluids #1 and #3 in a rigid T-junction simulating the first septal branch of the left descending coronary artery. The measurements were done in steady and pulsatile flow experiments at different flow rate ratios. The fluids showed large differences in velocity profiles compared to Newtonian fluids. A polyacrylamide suspension (Separan AP30 and AP45) to which we added 4% isopropanol and 0.01% magnesium chloride. A suspension of 2% Dextran with 16% by weight biconcave disc-shaped particles simulating red blood cells. 40% ghost cells prepared according to Dodge in Tri(hydroxymethyl) aminomethane. These ghost cells were used to simulate the two-phase flow behavior of blood. A suspension of 5% Dextran (70000) with 12% polystyrene particles (diameter of 1 μ m) and 10 mMol calcium chloride. Show more

Keywords: non-Newtonian fluids, polyacrylamide solution, Couette viscometer, oscillatory tube flow viscoelasticity analyzer, laser-Doppler anemometer

DOI: 10.3233/BIR-1991-281-205

Citation: Biorheology, vol. 28, no. 1-2, pp. 39-52, 1991

Authors: Lipowsky, Herbert H. | Riedel, Dorethea | Shi, Guo Shan

Article Type: Research Article

Abstract: Transient deformations of leukocytes (WBCs) were studied during their saltation along post-capillary venous endothelium (EC) in mesentery of the rat. During intermittent adhesion of WBCs to EC, prevailing fluid shear stresses, τ wall , resulted in a stepwise loading of the WBC upon attachment with a transient increase in length, L (t), and reduction in height, H (t). Measurements of L (t) and H (t) from frame-by-frame analysis of video recordings were modelled as the simple shear of a standard linear viscoelastic solid to facilitate calculation of the elastic (k 1 , k 2 …) and viscous (μ ) elements with k 1 in parallel with serial elements k 2 and μ The magnitude of τ wall was determined from measurements of red cell velocity within the venule. During the spontaneous adhesion of WBCs, a value of cell viscosity (μ ) of 45 Poise was determined. Stimulating adhesion by topical application of the chemoattractant FMLP resulted in a 15-fold increase of μ to 668 Poise. Transient deformations during topical application of cytochalesin B to disrupt actin fibers within the WBC, yielded a 40% reduction in k 1 , compared to an 80% reduction with colchicine which disrupts the microtubule structure. Thus, colchicine treated cells appear to be twice as deformable as cells treated with cytochalesin. During adhesion stimulated by the cytokine Interleukin-1, μ increased 50% without changes in k 1 and k 2 , possibly due to slight activation of the WBC. Show more

Keywords: Leukocyte-endothelium adhesion, leukocyte deformability, leukocyte mechanics f-met-leu-phe, Interleukin 1, cytochalesin, colchicine

DOI: 10.3233/BIR-1991-281-206

Citation: Biorheology, vol. 28, no. 1-2, pp. 53-64, 1991

Authors: Kiani, Mohammad F. | Hudetz, Antal G.

Article Type: Research Article

Abstract: A semi-empirical model is developed to describe the dependence of apparent viscosity of blood on vessel diameter (2.7 to 500 microns) and vessel discharge hematocrit (5% to 60%). The blood flow is modeled as a cell-rich core and a cell-free marginal layer in the larger vessels and an axial-train in the smaller vessels. Laminar (poiseuille) flow is assumed in all cases. An equation is derived in which apparent viscosity is a function of vessel diameter, core viscosity, and width of marginal layer. This is then complemented by empirical equations in which core viscosity varies exponentially with discharge hematocrit while the …width of marginal layer varies linearly with discharge hematocrit. The model correlates well with several sets of experimental data and behaves according to the Fahraeus-Lindqvist effect. Predicted apparent viscosity tends to the expected finite value for large vessel diameters. Dependence of apparent viscosity on vessel diameter is realistically smooth in the whole diameter range. Show more

Keywords: Apparent Viscosity, Fahraeus-Lindqvist effect, Marginal Layer, Hematocrit

DOI: 10.3233/BIR-1991-281-207

Citation: Biorheology, vol. 28, no. 1-2, pp. 65-73, 1991

Authors: Engel, Jutta | Pastushenko, Vassili F. | Richter, Walter | Donath, Edwin

Article Type: Research Article

Abstract: We present a model for the calculation of intragranular vesicle adhesion energy in a two-vesicle system consisting of an external secretory vesicle (chromaffin granule) and an intragranular vesicle (IGV) that adheres from the inside to the granule membrane. The geometrical parameters characterizing the granule-IGV systems were derived from freeze-fracture electron micrographs. Adhesion is brought about by incubation of the granules in hyperosmolar sucrose solutions. It is accompanied by a deformation of the granule because the intragranular vesicle bulges it outwards, and by segregation of intramembraneous particles from the adherent part of the granule membrane. Adhesion prevents the deformed granules from …osmotic re-expansion and, therefore, causes hyperosmotic relaxation lysis. We estimated specific adhesion energy at −3 erg/cm2 , a value which is 10–1000 times larger than the energy of van der Waals interaction between membranes. This large interaction energy probably results from changes of the granule core induced by dehydration. A minimization of the interface between the granule core and adjacent membranes could exclude intragranular vesicles from the core and squeeze them towards the granule membrane. This might induce a new kind of interaction between both membranes, which is irreversible and causes lysis upon osmotic relaxation. Show more

Keywords: chromaffin granule, intragranular vesicle, membrane adhesion, membrane mechanics, catecholamines, freeze-fracture

DOI: 10.3233/BIR-1991-281-208

Citation: Biorheology, vol. 28, no. 1-2, pp. 75-87, 1991

Authors: Razavian, S.M. | Guillemin, M-Th. | Guillet, R. | Beuzard, Y. | Boynard, M.

Article Type: Research Article

Abstract: Aggregation of human red blood cells (RBCs) induced by dextrans of various molecular weight has been studied by using a new ultrasonic interferometry method. This method, based on A-mode echography, allowed for the measurement of the accumulation rate of particles on a solid plate which is related to their sedimentation rate (i.e., to their mean size). The initial aggregation process, the mean and the maximum sedimentation rate of aggregates and the packing of the sedimented RBCs have been investigated. Effects of hematocrit, molecular weight of dextrans and inhibition by dextran 40 on the RBC aggregation induced by dextran of higher …molecular weight have been determined by analysing variations of the aggregate size. Results obtained confirm the aggregation effect of dextrans of molecular weights equal or higher than 70 000 dalton and disaggregation effect of dextran 40 000 dalton on aggregation by dextrans of higher molecular weight. Show more

Keywords: RBC aggregation, dextran, ultrasonic interferometry

DOI: 10.3233/BIR-1991-281-209

Citation: Biorheology, vol. 28, no. 1-2, pp. 89-97, 1991

Authors: Feitelson, Jehuda | Yedgar, S.

Article Type: Research Article

Abstract: The migration rate of small molecules through the structure of proteins can be monitored by quenching the light emitted from an excited optical probe located within the protein. In the present study we examined the influence of the solvent viscosity on the migration rate of the quencher anthraquinone sulfonate through myoglobin towards an excited Zn protoporphyrin molecule at the binding site of the protein. The solvent viscosity was increased by adding dextrans of different molecular weight but forming isoviscous solutions. The results demonstrate that the migration rate in the protein decreases with increasing solvent viscosity. This suggests that the fluctuations …on the protein structure, which make the above migration possible, are affected by the solvent macroviscosity. Show more

Keywords: Solvent Viscosity, Myoglobin Dynamics

DOI: 10.3233/BIR-1991-281-210

Citation: Biorheology, vol. 28, no. 1-2, pp. 99-105, 1991

Authors: Hanai, S. | Yamaguchi, T. | Kikkawa, S.

Article Type: Research Article

Abstract: Turbulent velocity fluctuations were measured and analyzed in the canine ascending aorta using a hot-film anemometer. Blood flow rate and temperature were stabilized using a special bypass technique. Blood pressure was elevated by Methoxamine infusion. Turbulence components were extracted from measured data using an ensemble averaging technique. Turbulence intensity correlated best with blood flow rate although the variance was relatively large, especially when the blood flow velocity was high. When pooled data were grouped into subclasses using peak aortic flow velocity as the criteria, turbulence intensity correlated well with aortic systolic blood pressure in each of the sub- classes. Spectral …bandwidth correlated with aortic pressure in the same manner. In summary, turbulence in the aorta developed when blood pressure was high. Both an increase of turbulence intensity and an widening of turbulence spectra may be ascribed to a stiffening of the aortic wall due to an elevation of blood pressure. Show more

Keywords: Hemodynamics, Turbulence, Hypertension, Enlargement of Aortic Arch, Hot-film anemometer

DOI: 10.3233/BIR-1991-281-211

Citation: Biorheology, vol. 28, no. 1-2, pp. 107-116, 1991

Article Type: Other

DOI: 10.3233/BIR-1991-281-212

Citation: Biorheology, vol. 28, no. 1-2, pp. 117-117, 1991