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Biorheology is an international interdisciplinary journal that publishes research on the deformation and flow properties of biological systems or materials. It is the aim of the editors and publishers of
Biorheology to bring together contributions from those working in various fields of biorheological research from all over the world. A diverse editorial board with broad international representation provides guidance and expertise in wide-ranging applications of rheological methods to biological systems and materials.
The aim of biorheological research is to determine and characterize the dynamics of physiological processes at all levels of organization. Manuscripts should report original theoretical and/or experimental research promoting the scientific and technological advances in a broad field that ranges from the rheology of macromolecules and macromolecular arrays to cell, tissue and organ rheology. In all these areas, the interrelationships of rheological properties of the systems or materials investigated and their structural and functional aspects are stressed.
The scope of papers solicited by
Biorheology extends to systems at different levels of organization that have never been studied before, or, if studied previously, have either never been analyzed in terms of their rheological properties or have not been studied from the point of view of the rheological matching between their structural and functional properties. This biorheological approach applies in particular to molecular studies where changes of physical properties and conformation are investigated without reference to how the process actually takes place, how the forces generated are matched to the properties of the structures and environment concerned, proper time scales, or what structures or strength of structures are required.
Biorheology invites papers in which such 'molecular biorheological' aspects, whether in animal or plant systems, are examined and discussed. While we emphasize the biorheology of physiological function in organs and systems, the biorheology of disease is of equal interest. Biorheological analyses of pathological processes and their clinical implications are encouraged, including basic clinical research on hemodynamics and hemorheology.
In keeping with the rapidly developing fields of mechanobiology and regenerative medicine,
Biorheology aims to include studies of the rheological aspects of these fields by focusing on the dynamics of mechanical stress formation and the response of biological materials at the molecular and cellular level resulting from fluid-solid interactions. With increasing focus on new applications of nanotechnology to biological systems, rheological studies of the behavior of biological materials in therapeutic or diagnostic medical devices operating at the micro and nano scales are most welcome.
Abstract: S. Oka has offered an elegant explanation of the Copley-Scott Blair phenomenon based on the inclusion of the effect of an electric double layer, which occurs at the interface of phases between the capillary wall and the dispersion medium. The latter is considered as blood, plasma or serum. This explanation has associated the Copley-Scott Blair phenomenon and changes of the apparent viscosity with such electrokinetic phenomena as an electroosmosis and a streaming potential. As has been shown by a qualitative analysis of the formulae obtained by S. Oka, the inclusion of the electrosurface features makes it possible to explain the…changes of the apparent viscosity while blood flows through capillaries. And the smaller is the capillary radius, the more substantial are these changes. At the same time, such conclusions may not be considered as a demonstration of the significance of the double layer effects in hemorheology, since the Oka theoretical model should be supplemented with an inclusion of the Debye screening radius, surface conductivity and a feasible overlap of the double layers within a capillary. Requirements on an experimental test of the Oka theoretical model have been formulated.
Keywords: Blood flow through a capillary, electric double layer, effect of a capillary surface, zeta potential
vol. 21, no. 3, pp. 297-302, 1984
Abstract: An analysis of the effects of couple stresses on the blood flow through thin artery in the presence of very mild stenosis has been carried out with the help of two nondimensional parameters, α ¯ (the length ratio parameter) and η ¯ (the parameter characterizing the antisymmetric property of the couple stress tensor). It is shown that an increase in the couple stress (small value of α ¯ and η ¯ ), increases the resistance to the flow and the wall…shear stress. These characteristics are further enhanced by the presence of the stenosis.
Abstract: Spatial orientation of blood platelets flowing in small arterioles of the rabbit mesentery was investigated using intravital fluorescence microscopy. Only platelets were studied that could be localized objectively within a thin optical section around the median plane of the vessel. The orientation of a platelet was assessed from its microscopic image and described by an angle pair, assuming the platelet to be an ellipsoidal body and using an empirical frequency distribution for its thickness to diameter ratio. The orientation of the platelets was not random; they tended to align themselves with their equatorial planes parallel to the wall. The degree…of alignment increased from the center of the vessel toward the wall. As a corollary a frequency distribution of their diameter ( 3.15 ± 0.72 µ m ( x ¯ ± sd ) ) was obtained in vivo .
Abstract: Shear-induced injury or denudation of arterial endothelium has been implicated in atherogenesis. This study reports on an in vitro technique for imposing high, controlled shear stresses on endothelium. Samples of dog aorta were mounted in a chamber so that the endothelium was 1 mm ± 0.03 mm from a rotating disc. The chamber was filled with a high viscosity solution (10% polyvinyl pyrrolidone in Tyrode’s solution, viscosity = 1.97 ± .07 Poise) which was sheared over the endothelium by the disc. A servo amplifier drove the motor that rotated the disc, so that motor RPM (therefore shear stress) could…be made to follow either steady or pulsatile signals played into the amplifier. Acute (10 min – 1 hr) exposure to steady shear stresses of up to 2000 dyne/cm2 did not cause gross endothelial injury or denudation. Exposure of endothelium to pulsatile shear stresses that followed a tape recording of physiological flow waveforms (electromagnetic flowmeter) did not cause gross injury or denudation even when peak shear exceeded 1500 dyne/cm2 . Furthermore exposure to high shear stress did not degrade the non-thrombogenic nature of the endothelium because subsequent platelet adhesion was poorly and negatively correlated with shear stress.
Keywords: atherogenesis, response to injury hypothesis, hemodynamics
vol. 21, no. 3, pp. 333-346, 1984
Abstract: A technique for measuring the diffusion coefficients of high molecular weight solutes in biological polymers, which requires only small quantities of tracer and substrate is described. The influences on the distribution of the tracer of non-ideal injections, of tracer contamination and degradation, and of various interactions between tracer and substrate are analysed theoretically in order that they may be recognised, and in some cases corrected for, in the experimental data. The experimental technique is tested by measurements of the diffusion coefficient of albumin in hyaluronate gels of 0.5%–2.5% (w/v) concentrations and preliminary data are presented on the diffusion of rabbit…lipoproteins in similar gels.
Keywords: Diffusion, Hyaluronate, Lipoprotein, Albumin
vol. 21, no. 3, pp. 347-362, 1984
Abstract: Lysophosphatidylcholine (LPC) protected against hypotonic hemolysis during rapid swelling of erythrocytes in spherocytic concentrations without any increase in the maximal cell volume. The total prelytic potassium release was increased, but the prelytic potassium release per cell was the same or decreased in the presence of LPC. The comparison of measured and calculated cell volume increase suggested that the prelytic potassium release must have been connected with a considerable sodium influx suggesting serious damage of the cell membrane already during swelling in the absence of LPC. Gradual swelling shifted hemolysis to more dilute solutions and LPC did not further increase the…shift. We suggest that LPC protects the erythrocytes against hypotonic hemolysis during rapid swelling via a prevention of the initial membrane damage through altering the interaction between lipid bilayer and membrane cytoskeleton in the same way as occurs during incubation in a medium with low ionic strength.
Abstract: The viscoelastic properties of a concentrated red cell suspension in which red cells do not form rouleaux are discussed from a theoretical point of view. An elastic spherical shell filled with a viscous fluid is considered as a model of a normal red cell. A cell method is used to consider finite concentration of suspended particles. On the assumption that the deformation from a spherical shape is very small, the shape of a deformed shell in a shear flow and the constitutive equation of the suspension are derived.
Keywords: Red cell deformation, Viscoelasticity, Blood rheology
vol. 21, no. 3, pp. 379-391, 1984
Abstract: Rouleau formation by back scattered light and flow behavior by viscometry of heat-treated (48.4, 48.8 and 49.5°C) and normal (37°C) human red blood cells (RBC) were investigated. Washed RBC were treated in PBS and afterwards resuspended in their own plasma. It was found that the time behaviour of the fibrinogen mediated weak RBC-RBC interaction is influenced (decreased) already at an incubation temperature of 48.4°C. Kinetic measurements are more sensitive than a static aggregation characterization. Beside the decreased deformability of the RBC also a heat-altered structure of the RBC-glycocalyx and the aggregating energy of the macromolecules have to be considered.
Abstract: To discuss the relaxation phenomena of biological cell suspensions, we have calculated the complex intrinsic viscosity of the dispersion of spherical cells with a viscoelastic membrane as a function of the frequency taking account of interfacial tension at both the interfaces of the membrane. The Voigt model is used to describe the viscoelasticity of the cell membrane. In general it is possible for four relaxations to exist. Under a finite membrane viscosity it is predicted that there exist two relaxations. The amplitude of relaxation for the shorter relaxation time is larger than that for the longer relaxation time. The results…are compared with the experimental ones.