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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: The Cell Transit Analyser (CT A) provides a means to rapidly measure the deform ability of large numbers of individual cells. It combines many of the advantages of micropipette studies with the simplicity and speed of filtrometry methods by measuring the duration of each resistive pulse generated as a cell passes through one of 30 identical micropores in a membrane. However, in our opinion, the potential of the system is limited by the microcomputer and software supplied for data analysis. We have therefore written new software for a more-powerful microcomputer to examine the shape of each resistive pulse rather than…just the duration. Seven new parameters are derived, which provide additional information regarding the passage of cells through the pores. In particular, the contribution of the entry and exit phases of the cell transit are evident in the rise time and fall time of the pulses. The software is user-friendly and allows the analysis of each pulse to be reviewed, which aids understanding of the system and helps to avoid errors in interpreting the data.
Abstract: Several previous studies have shown that exposure of RBC to temperatures in the range 47 to 48.8°C causes an irreversible alteration of RBC rheological properties; membrane elasticity and viscosity are both increased and greater pressure is required for RBC entry into pipettes. While it has been tacitly assumed that these rheologic alterations are membrane specific, no data on heat-treated hemoglobin (Hb) solutions appear to exist. The present study was thus designed to evaluate the effects of heat-treatment (48.8 ± 0.1°C, 3 to 20 min) on the viscoelasticity of Hb solutions (30 to 45 g/100 ml) prepared from normal human RBC.…Measurements of the viscous component (VC) and elastic component (BC) were made at 25°C using Couette (GDM) and capillary (OCR-D) rheometers; shear rates ranged from 1 to 200 s−1 . All unheated Hb solutions were Newtonian and did not exhibit elasticity. However, after 3 min of heating, an elastic component was measurable. Both VC and EC increased with heating time in a power law fashion. VC continued to exhibit Newtonian behavior, whereas the magnitude of EC was an inverse function of shear rate and directly related to Hb concentration and treatment time. A relaxation function applied to our data suggests a first order reaction. These results indicate that both cytoplasmic and membrane viscoelasticity should be considered in order to fully comprehend the rheologic behavior of heat-treated RBC.
Abstract: The effect of superoxide anions (O 2 − ) on red blood cells (RBC) deformability and membrane proteins was investigated using hypoxanthine-xanthine oxidase system. Exposure of RBC to O 2 − caused a marked decrease in RBC deformability with a concomitant increase in cell volume and shape changes. The RBC exposed to O 2 − also displayed pronounced degradation of membrane proteins such as band 3 protein and spectrin; new bands of low molecular weight products appeared as the original…membrane proteins tended to diminish, without the appearance of high molecular weight products. Since the membrane proteins are involved in processes regulating membrane properties such as permeability and viscoelasticity, the decreased deform ability induced by O 2 − may be attributable to changes in membrane proteins. Interestingly, resealed ghosts exposed to O 2 − did not show any significant change in membrane proteins, which suggests the existence of further generation of O 2 − and subsequent production of other active oxygen species mediated by O 2 − -initiated autoxidation of hemoglobin in intact RBC. Furthermore, electrophoretic analysis suggested that active oxygens increased the endogenous proteolytic susceptibility of RBC. In conclusion, a close linkage was suggested between RBC deformability and the membrane proteins.
Keywords: red blood cells (RBC), superoxide anion, deformability, membrane protein, band 3 protein
vol. 29, no. 2-3, pp. 217-229, 1992
Abstract: In this study rheological properties of aqueous solutions of mucin, albumin and mucin-albumin have been investigated in search for saliva substitutes. They were compared with commercially available saliva substitutes on the one hand and natural human saliva on the other hand. For the latter a few measurements on saliva are reported here in addition to previously reported measurements done in our laboratory. Proteins adsorb at the interface and saliva proteins do so strongly and rapidly. Therefore rheological measurements were carried out on the interface and on the bulk underneath the layer. In both cases the flow curve and the complex…viscosity was determined. The results show that specific mucin-albumin solutions were rheologically similar to human whole saliva with respect to both bulk liquid and surface properties. The rheological properties of commercial saliva substitutes were essentially different from those of human saliva. It is concluded that mucin-albumin solutions have good perspectives as saliva substitutes.
Keywords: saliva, human, rheology, mucin, protein adsorption
vol. 29, no. 2-3, pp. 231-249, 1992
Abstract: Two diameters of vessel and red cell column in cerebral microvessels (> 29.8 μ m in diameter) of cat were measured together with red cell velocity, using a two fluorescent tracer method. A fluorescein isothiocyanate (FITC)-labelled red cell was adopted as a flow tracer to measure the cell velocity with a dual window technique. Based on the fluorescence image, the red cell column diameter was measured. Plasma was stained with rhodamine-B isothiocyanate (RITC)-labelled dextran to measure the vessel diameter. The thickness of the cell-free plasma layer could be determined from the difference of the two diameters. The obtained thickness of…the cell-free layer was not described by a simple function of vessel diameter or red cell velocity; it was dependent on the pseudo shear rate defined by the ratio of cell velocity to vessel radius. The layer thickness increased with a decrease in the pseudo shear rate.
Abstract: The authors deduced the equation that describes the sedimentation of erythrocytes as the function of time, hematocrit, hemoglobin and some plasma protein concentrations and the citrate viscosity and density. This values served to describe plasma and erythrocyte density, plasma viscosity, erythrocyte aggregation and the influence of suspension concentration on the erythrocyte sedimentation rate. The influence of citrate on blood dilution (the reduction of hematocrit and plasma protein concentrations) was also considered. A good agreement between the observed and predicted values was obtained.
Abstract: Adsorption of bovine serum albumin onto glassy carbon is investigated by analysing the time-variation of the double-layer capacitance recorded during the adsorption process. The effect of shear rate is investigated under laminar conditions in a Couette flow. Stationary and sinusoidally modulated values of the shear rate are imposed over the (0–200 s−1 ) range. The flow conditions are shown to play an essential role by markedly modifying the rate of all the steps (three at most) involved in the adsorption mechanism. Moreover, the structure of the adsorbed layers in the intermediate and final states are also strongly modified, an increase…of the shear rate increasing the interaction between the protein and the electrode. Piezoelectric properties of albumin are invoked to account for the experimental results.
Abstract: Changes in production and in physico-chemical properties of bronchial mucus is a common denominator of many pulmonary diseases. A rheometer with innovative features aimed at bronchial mucus routine investigation in clinical practice at the bedside of the patient has been designed. Searle-type configuration with a coaxial cylinder sensor system and the Mooney-Ewart geometry has been adopted. Another new feature is that bob and cup are disposable. Dynamic viscoelasticity is calculated through a microprocessor with specific software and by means of a magnetic torque—motor electronically driven by the microprocessor. The self-zeroing procedure and the autorange greatly simplify the measuring-cycle which is…driven by only one switch. Data (η and G′) are automatically printed on paper. The whole measuring-cycle at the bedside of the patient takes 3–5 min, so that in 1h about 12 samples can be investigated.
Abstract: We measured changes in the deformability of human pro myelocytic leukemic (HL-60) cells induced to differentiate for 5–6 days along the granulocyte pathway by 1.25 % dimethylsulfoxide (DMSO). Differentiation resulted in an approximately 90 % reduction in the transit times of the cells through capillary-sized pores over a range of aspiration pressures. Cell volume, as measured by two methods, decreased by an average of 35 %. To account for the contribution of the volume decrease to the decrease in transit time, the liquid drop model, developed to describe neutrophil deformability, was used to calculate an apparent viscosity of the cells…during this deformation. The apparent viscosity of both uninduced and induced HL-60 cells was a function of aspiration pressure, and an approximately 80 % reduction in viscosity occurred with induction, as determined by regression analysis. The deformation rate-dependent viscosities of the induced cells were between 65 and 240 Pa-sec, values similar to those measured for circulating neutrophils. To assess the role of polymerized actin in these viscosity changes, intracellular F-actin content was measured, and the effect of dihydrocytochalasin B (DHB), an agent that disrupts actin polymerization, was determined. Despite the significant decrease in cellular viscosity, F-actin content per cell volume did not change significantly after induced differentiation. Treatment with 3 and 30 μ M DHB lowered cellular F-actin content in a dose-dependent manner in both uninduced and induced cells. Cellular viscosity of both uninduced and induced cells decreased sharply with 3 μ M DHB treatment (85 % and 76 % respectively). 30 μ M DHB treatment caused a further significant reduction in the viscosity of uninduced cells, but for induced cells the additional decrease in viscosity was not significant. These data indicate that reductions in both cell volume and intrinsic viscosity contribute to the increased deformability of HL-60 cells with DMSO-induced differentiation. However, changes in the concentration of F-actin cannot account for the decrease in cellular viscosity that occurs.
Abstract: As a model of the flow through the false lumen of the dissecting aortic aneurysm, the starting and stopping flows of the Casson fluid through the eccentric circular tube are studied numerically. The calculations are performed by using the one-direction fully developed unsteady flow model. The calculation results show that the non-Newtonian property of the Casson fluid has the following two effects. One is the decrease in the flow rate through the false lumen, the other is the effect to strengthen the non-uniformity of the velocity distribution in the false lumen. Moreover, the calculations based on a triphasic waveform measured…by McDonald are performed and the development of the dissecting aortic aneurysm is discussed on the basis of the calculated wall shear stress.
Abstract: We applied laser diffractometry and a linear image sensor to measurement of erythrocyte deformability to detect the light intensity pattern of the diffraction image. Deformability was evaluated as the deformability index (DI), calculated from the width and length of the diffraction pattern ellipse, estimated by the linear image sensor. With the erythrocytes under various shear stresses, the DI was linearly related to results by the geometric method (r = 0.996, P < 0.01). The coefficient of variance of DI at a shear stress of 236 dynes/cm2 was 0.2 % (seven human blood samples), which was satisfactory for practical use.…The DI was independent of the erythrocyte concentration in the range of 1.5 × 107 - 5.0 × 107 cells/ml of suspension. Correlation between the DI and the logarithm of shear stress was linear in the range of 5 to 350 dynes/cm2 of shear stress in suspension media of different viscosities. Heat-treatment, Which decreased membrane flexibility, caused parallel reduction of the DI plotted against the logarithm of shear stress. The method was sensitive and gave reproducible results. It may be useful for clinical applications.
Abstract: A model of intima thickening proposed by Friedman and his coworkers (1,2) is incorporated in our computer code to simulate the growth of intima under shear. The computer code is based on a finite volume method in a boundary-fitted coordinate system. It is found that the model yields an evenly-distributed thickening over a straight, smooth vessel wall. However, in a stenosed or a curved artery, thicker intima can be formed in preferential regions due to unevenly-distributed wall shear stresses. The results clearly demonstrate the correlations among the geometry, wall shear rate and the plaque localization in arteries. The model is…applied to a straight artery with a stenosis or sinus, a smooth curved artery and a stenosed curved artery. The effects of stenosis/sinus and lumen curvature on the flows and the intimal thickening are studied. The simulation provides a numerical visualization of the intimal thickening in a dynamic way.
Abstract: Blood cells suspended in shear flows exhibit much larger dispersive motions than those predicted by the Stokes-Einstein formula for Brownian diffusion. The lateral migration and the erratic motions of the 8IJ.m red blood cells (RBC) is thought to be analogous to a diffusive process. It is shown that the often cited convective-diffusion theory may not be an adequate model for describing the transverse migration of suspended cells in blood flow. A comprehensive review of both the classical theory and of contemporary work in particle transport is presented, with particular emphasis on low Reynolds number tube flows. The mechanisms of…Taylor dispersion, the effects of Brownian perturbations on translational and rotational motions of the suspended particles in shear fields, and the influence of integratable and chaotic advections, are individually examined. The classical experiment by Segre and Silberberg (1962) lead us to believe that particle hydrodynamics may play an important role in transverse migrations. In this light, we have further examined the hydrodynamic aspects of the so-called “tubular pinch” effect, the lateral migration of rigid spheres. We have also discussed the transverse motions of liquid drops, and the reversibility of the organization of suspensions in transport. The convective accelerations in the entrance region of a tube can produce relative velocities between fluid medium and various type of particulates if there is a difference in density. The deformable RBC, an “active-type” particle, can provide feedback to the flow from both mass and momentum considerations; the more rigid platelet, a “passive-type” particle, will experience a much smaller relative velocity as compared to the RBC. We may expect that particles of different densities are transported to different equilibrium annular positions before entering the fully developed flow region. The erratic, lateral movement of suspended particulates in steady laminar tube flow can be described by the usual Lagrangian coordinates.