Biorheology - Volume 28, issue 5

Authors: Purvis Jr., N.B. | Giorgio, T.D.

Article Type: Research Article

Abstract: Hemodynamic shear is known to stimulate blood and endothelial cells and induce platelet activation. Many studies of shear-induced platelet stimulation have employed rotational visco meters in which secondary flow effects are assumed to be negligible. Shear induced platelet activation occurs at elevated shear rates where secondary flows may contribute a significant percentage of the total hydrodynamic force experienced by the sample. Elongational stress, one component of this secondary flow, has been shown to alter transmembrane ion flux in intact cell and the permeability of synthetic membrane preparations. Elongational flow also occurs in the vasculature at sites of elevated shear stress. …Secondary flow components may contribute to platelet activation induced during shear stress application in rotational viscometry. A unique ‘constrained convergence’ elongational flow chamber was designed and fabricated to study platelet response to elongational stress exposure. The elongational flow chamber was capable of producing an elongation rate of 2.1 s−1 with a corresponding volume averaged shear rate of 58.33 s−1 . Significant changes were observed in the total platelet volume distribution and measured response to added chemical antagonist after elongational stress exposure. The total platelet volume histogram shifted toward larger particle sizes, suggesting the formation of large aggregates as a result of elongational stress exposure. Platelets exposed to elongational stress demonstrated a dose dependent decrease in added ADP-induced aggregation rate and extent of aggregation. Show more

Keywords: Platelets, extensional, shear stress, aggregation, activation, elongational

DOI: 10.3233/BIR-1991-28501

Citation: Biorheology, vol. 28, no. 5, pp. 355-367, 1991

Authors: Diller, Kenneth R. | Dunaway, Dwayne L.

Article Type: Research Article

Abstract: The modulation of microvascular blood flow by vasomotion in the individual vessels of a simple vascular network was simulated by means of a network thermodynamic model. The flow is driven under a pulsating pressure through two arcades of branching vasoactive arterioles into a passive resistance representing the capillary and venular beds. Each vessel was assumed to have the capability of decreasing rhythmically the local diameter over a short section by a specified fraction of the maximum value and to change the average diameter along its total length in response to alterations in intraluminal pressure. Blood was assumed to exhibit a …simple linear viscous flow resistance. Alterations in flow rate and distribution through the network were determined as a function of the magnitude and frequency of vasomotion within the individual arterioles supplying blood to the microvascular bed. Specific cases are shown to illustrate how blood flow can be influenced by the patterns of vasomotion within the network. Show more

Keywords: Network thermodynamic model, vascomotion, microvascular blood flow

DOI: 10.3233/BIR-1991-28502

Citation: Biorheology, vol. 28, no. 5, pp. 369-382, 1991

Authors: Chahed, N. | Péronneau, P. | Delouche, A. | Diebold, B.

Article Type: Research Article

Abstract: Velocity fields have been measured in models simulating arterial stenoses for continuous and revolution flows. A pulsed Doppler velocimeter allows for velocity readings in the entire tube and in the wall area. Streamlines are determined by numerical solving of the system of equations defining the current function. Velocity profiles and streamlines are presented and discussed either for steady or for unsteady flows, with different Reynolds numbers and variable degrees of stenosis. There is, in the wall area, a recirculating zone made of a well-defined rouleau. Its length varies increasingly according to the increasing severity of the stenosis. The stability of …axial flow depends on the input profile, the degree of stenosis and the Reynolds number. Plotting streamlines allows to describe accurately the flow; its quantitative aspect offers advantages with respect to conventional visualization mode. Show more

Keywords: Stenosis, in vitro modelization, recirculating zone, streamlines

DOI: 10.3233/BIR-1991-28503

Citation: Biorheology, vol. 28, no. 5, pp. 383-400, 1991

Authors: Kim, Annabelle | Wang, ChunHai | Johnson, Mark | Kamm, Roger

Article Type: Research Article

Abstract: Previous studies of extracellular matrix hydraulic conductivity have characterized the flow resistance of glycosaminoglycans, proteoglycans and collagen. This work focusses on serum albumin, present in significant quantities in many connective tissues, but not previously considered for its role in determining connective tissue flow resistance. The specific hydraulic conductivity of bovine serum albumin solutions, as a function of concentration, was calculated from sedimentation and ultrafiltration data available in the literature. A rigid particle hydrodynamic model compared favorably with these results. Experimental measurements on an albumin ultrafiltration cell were in agreement with this model (within experimental error); furthermore, the experimental data …confirmed the theoretical prediction that there is no (or negligible) pressure drop through the concentration polarization layer. Use of the hydrodynamic model for albumin specific hydraulic conductivity with literature values for the hindrance of albumin when passing through a glycosaminoglycan (GAG) matrix allows an estimate of the relative importance of the albumin on tissue hydraulic conductivity: in non-cartilagineous tissues with moderate GAG concentrations, tissue levels of albumin can generate flow resistance effects comparable to those of the GAGs, although well less than the flow resistance of these tissues. Show more

Keywords: Extracellular matrix (EVM), bovine serum albumin (BSA), hydraulic conductivity, glycosaminoglycan (GAG)

DOI: 10.3233/BIR-1991-28504

Citation: Biorheology, vol. 28, no. 5, pp. 401-419, 1991

Authors: Mo, L.Y.L. | Yip, G. | Cobbold, R.S.C. | Gutt, C. | Joy, M. | Santyr, G. | Shung, K.K.

Article Type: Short Communication

Keywords: Non-Newtonian, blood velocity profiles, Erythrocyte aggregation

DOI: 10.3233/BIR-1991-28505

Citation: Biorheology, vol. 28, no. 5, pp. 421-427, 1991

Authors: Silberberg, A.

Article Type: Book Review

DOI: 10.3233/BIR-1991-28506

Citation: Biorheology, vol. 28, no. 5, pp. 429-430, 1991

Article Type: Abstract

DOI: 10.3233/BIR-1991-28507

Citation: Biorheology, vol. 28, no. 5, pp. 431-459, 1991

Article Type: Announcement

DOI: 10.3233/BIR-1991-28508

Citation: Biorheology, vol. 28, no. 5, pp. 461-461, 1991

Authors: Baquey, Ch. | Dupuy, B. | Janvier, G. | Bordenave, L. | Caix, J. | Basse-Cathalinat, B.

Article Type: Research Article

Abstract: The biocompatibility of a material can be considered as the ideally expectable result of its interactions with living tissues with which it is interfaced. This property determines the ability of devices involving this material in their constitution, to correctly assume their ascribed function; reciprocally a bad fitting, between devices and their intended use, coming from a non-optimized design or from an inappropriate prescription, may alter the original biocompatibility of constitutive materials. Accordingly, the actual biocompatibility of a biomaterial depends upon both its intrinsic properties and the application in which it is involved. Such considerations must be taken into account by …specialists who try to design more performant biomaterials, or new assist devices, should they be implantable or not; but they draw also methodological guidelines for the evaluation of the biocompatibility of these biomedical products. Show more

Keywords: Biomaterials, Biocompatibility, Bioartificial pancreas, Vascular substitutes

DOI: 10.3233/BIR-1991-28509

Citation: Biorheology, vol. 28, no. 5, pp. 463-472, 1991

Authors: Seyfert, U.T. | Hauck, W. | Kirsch, J. | Kiesewetter, H. | Albert, F.W. | Wenzel, E.

Article Type: Research Article

Abstract: Thrombogenecity is the property of a foreign surface to induce clotting processes or formation of aggregates after contact with blood. Beside the sort of anticoagulation patient’s prethrombotic state, rheological factors as well as physicochemical properties of foreign membranes decisively influence thrombogenecity. We examined the influence of chronic renal failure and different hemodialyzers and blood transfusion therapy during hemodialysis on hemorheological parameters. Different membranes cannot be discriminated by the used hemorheological parameters. We clearly could demonstrate the close relationship between the hemofiltration rate and an increase of viscosity. Blood transfusion therapy or elevated hematocrit in combination with increased hemofiltration rate have …influence on the flow behaviour of blood especially in disturbed microcirculation. Show more

Keywords: biocompatibility, hemodialysis, biorheology, hemodialyzer, blood transfusion

DOI: 10.3233/BIR-1991-28510

Citation: Biorheology, vol. 28, no. 5, pp. 473-481, 1991

Article Type: Other

DOI: 10.3233/BIR-1991-28511

Citation: Biorheology, vol. 28, no. 5, pp. 483-483, 1991