Biorheology - Volume 22, issue 6

Article Type: Editorial

DOI: 10.3233/BIR-1985-22607

Citation: Biorheology, vol. 22, no. 6, pp. I-III, 1985

Authors: Grebe, R. | Schmid-Schönbein, H.

Article Type: Research Article

Abstract: The resting shape of the human erythrocyte is maintained mainly by the elastic properties of its membrane. There is evidence that negative spontaneous membrane curvature is the cause of the biconcave shape; also negative membrane curvature is thought to be enhanced under “stomatocytogenic” influences and reduced under “echinocytogenic” influences. Experimental tests of these hypotheses are difficult in the absence of objective methods to quantify cell shape and/or membrane curvature. A new method is introduced to estimate the changes in convex and concave curvatures of the cell outlines in larger populations of RBC. It is based on the so-called “tangent count” …procedure, carried out on microphotographs of freely suspended, randomly oriented RBCs in isotonic solutions. The method was validated by subjective shape assessment according to BESSIS’ classification. It proved to be most sensitive in the range of moderate shape changes (classified subjectively as echinocyte II and stomatocyte II). Show more

DOI: 10.3233/BIR-1985-22601

Citation: Biorheology, vol. 22, no. 6, pp. 455-469, 1985

Authors: Ernst, E. | Monshausen, Ch. | Matrai, A.

Article Type: Research Article

Abstract: Three rotational viscometers for blood viscometry were compared at moderate and high shear. At high shear, coefficients of variation were all around 1% increasing 5-fold (Wells-Brookfield) and 3-fold (Carri-Med) when shear was lowered. Using pathological samples the coefficients of variation for the Carri Med mashine was doubled. Only the Contraves LS-30 viscometer showed neither an increasing coefficient of variation with declining shear, nor problems when measuring blood with suspension instability.

Keywords: blood viscometry, viscometers, reliability, methods, comparison

DOI: 10.3233/BIR-1985-22602

Citation: Biorheology, vol. 22, no. 6, pp. 471-475, 1985

Authors: Beissinger, Richard L. | Williams, Michael C.

Article Type: Research Article

Abstract: Data are presented on the rheological and hemolytic behavior of whole human blood as it ages while stored at 4°C (as in blood banking practice) up to 26 days. The viscometric properties of steady shear viscosity η and oscillatory (complex) viscosity η ∗ = η ′ − i η ″ reported over ranges of shear rate γ ˙ and radian frequency ω of 33 < γ ˙ < 4130 s−1 and 1.5 < ω < …48 s−1 ; data on autologous plasma are given for reference. The Cox-Merz relation, η ( γ ˙ ) = | η ∗ ( ω ) | ω = γ ˙ , is found to be a good approximation, with η ⩾ | η ∗ | , over the range studied. Release of hemoglobin (Hgb) and lactate dehydrogenase (LDH) into the plasma during shearing is tracked as a function of time for 30 min, and its sensitivity to γ ˙ magnitude is measured. Bloods from four different donors are studied, with primary attention given to one (SSR). For all bloods, the release of both Hgb and LDH increases with storage age, but differences in such aging characteristics between different bloods can be substantial (even when rheological properties are identical). A post-shear incubation at 4°C for one day shows no enhancement of plasma Hgb and LDH levels beyond those expected from normal aging after the shearing experience, demonstrating the absence of significant delayed-action effects as a consequence of shearing trauma. Show more

Keywords: blood damage, blood storage, blood rheology, hemolysis, LDH

DOI: 10.3233/BIR-1985-22603

Citation: Biorheology, vol. 22, no. 6, pp. 477-493, 1985

Authors: Gates, R.S. | Scott, N.R. | Pitt, R.E. | Bartel, D.L.

Article Type: Research Article

Abstract: Five constitutive laws are investigated to model the effect of machine milking. A nonlinear least squares procedure is employed to estimate material constants from in vivo teat inflation data. An exponential form is found to be statistically adequate as a constitutive law, and is used to determine the mechanical stresses in teat tissue during finite deformations.

Keywords: biomechanics, soft biological tissue, finite deformation, machine milking

DOI: 10.3233/BIR-1985-22604

Citation: Biorheology, vol. 22, no. 6, pp. 495-508, 1985

Authors: Charara, J. | Aurengo, A. | Lelievre, J.C. | Lacombe, C.

Article Type: Research Article

Abstract: Transient rheological behavior of blood which involves non newtonian viscosity, elasticity and thixotropy can be modelized with a Maxwell rheological state equation which depends on a structure parameter having dimension of a shear rate. Identification of the model parameters leads to use an exponential apparent shear rate step and to use recursive filters for taking into account the impulse response of the viscometer servo-control device. Typical results for a normal blood sample are given.

Keywords: blood viscosity, thixotropy, viscoelasticity, rheological model

DOI: 10.3233/BIR-1985-22605

Citation: Biorheology, vol. 22, no. 6, pp. 509-520, 1985

Authors: Chaturani, P. | Ponnalagar Samy, R.

Article Type: Research Article

Abstract: Blood flow through a stenosed artery has been investigated in this paper. Blood has been represented by a non-Newtonian fluid obeying Herschel-Bulkley equation. This model has been used to study the influence of the fluid behaviour index n, shear-dependent nonlinear viscosity K and the yield stress τ H in blood flow through stenosed arteries. The variation of the wall shear stress and the flow resistance with n, K and τ H has been shown graphically. It is observed that the wall shear stress and the flow resistance increase in Herschel-Bulkley fluid in comparison with corresponding Newtonian fluid. It …is of interest to note that, in the present model, the thickness of the plug core varies with the axial distance z in the stenotic region. Finally, some biological implications of the present model for some arterial diseases have been briefly discussed. Show more

Keywords: Stenosis, Blood flow, Non-Newtonian fluid flow

DOI: 10.3233/BIR-1985-22606

Citation: Biorheology, vol. 22, no. 6, pp. 521-531, 1985