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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: A two-fluid model for blood flow through a stenosed tube has been developed. The model consists of a core (suspension of RBCs) and peripheral plasma layer. The core is assumed to be represented by a polar fluid and the plasma layer by a Newtonian fluid. The flow is assumed to be steady and laminar, and the fluids incompressible. The flow variables are computed for normal blood and for the cases of polycythemia, plasma cell dyscrasias and for Hb SS diseases. Resistance to flow has been computed for different stenosis length and for different stenosis height. Shear stress distribution along the…axial distance has been computed for different stenosis height. The impact of size effects (particle size to tube diameter) on blood diseases is discussed.
Abstract: From 204 presumably healthy volunteers 113 (56 women, 57 men) were accepted as reference population for viscoelastic parameters of blood by medical history, physical examination and more than 20 laboratory controls. To avoid bias through processing or calculating, the reference ranges of human whole blood viscoelasticity were given at their native packed cell volumes (see figure 2). The ranges of normal plasma viscosity were determined as 1.16 to 1.41 mPas with the median of 1.31 mPas. The rheological parameters tested are independent of age and gender.
Abstract: Blood cells filtration with decreasing pressure under gravity was studied for evaluation of the cell fluidity or deformability at a low shear state. A continuum approach was made to the flow and pressure in the filter at the low flow state to relate macro- and micro-scopic quantities. The mass conservation law of each species provided a set of differential equations with respect to the pore fraction and filter resistance. The numerical calculation was made for various values of hematocrit and leukocrit. It was shown that the filter resistance might be increased with decreasing pressure, resulting from both red and…white cells. The leukocrit, more than 0.05% white cells, may influence the filtration, depending upon the cell deformation. Even in the absence of the white cell, a decrease in pressure increased the filter resistance markedly. The present result indicates that single red cell shows a nonlinear behavior of flow in pores at the low pressure level.
Abstract: To study the transit times of each red blood cell passing through cylindrical micropores and In order to evaluate sub-population of cells with regard to their deformability, we have developed a new system called the cell transit time analyser (CTTA). By using an AC voltage (100 KHz) across a special filter, we measure the electrical conductance change produced by the cells passing through the pores under a known driving pressure. This computer based device provides the distribution of transit times τ for 2000 cells in 1 minute and as a result the mean transit time < τ >…. Experiments with red cells were designed to evaluate the flow behavior of both normal cells and cells whose mechanical properties were artificially altered. Cell volume was changed by use of non-isotonic media. Cell shape and ceil volume were modified by varying the pH of the suspending buffer. Results of these experiments are: 1) a skew distribution of transit times towards high τ values for both control cells and artificially altered cells is observed; 2) < τ > is minimum for isotonic conditions and increases sharply for either hypotonic or hypertonic media: 3) < τ > is minimum at physiological pH and increases for either acide or alcaline changes of pH.
Keywords: red blood cell, deformability, filtration, transit time
vol. 25, no. 5, pp. 763-772, 1988
Abstract: A new red blood cell filtration system, termed the Cell Transit Time Analyzer (CTTA), has been developed in order to measure the individual transit times of a large number of cells through cylindrical micropores in special “oligopore” filters; the system operates on the electrical conductometric principle and employs special computer software to provide several measures of the resulting transit time histogram. Using this system with filters having pore diameters at 4.5 or 5.0 μ m and length to diameter ratios of 3.0 to 4.7, we have evaluated the effects of several experimental factors on the flow behavior of normal and…modified human RBC. Our results indicate: 1) linear RBC pressure-flow behavior over a driving pressure range of 2 to 10.5 cm H2 O with zero velocity intercepts at δ P = 0, thus suggesting the Poiseuille - like nature of the flow; 2) resistance to flow or “apparent viscosities” for normal RBC which are between 3.1 to 3.9 cPoise ana are independent at driving pressure and pore geometry; 3) increased flow resistance (i.e., increased transit times) for old versus young RBC and for RBC made less deformable by DNP-induced crenation or by heat treatment at 48°C; 4) Increased mean transit time and poorer reproducibility when using EDTA rather than heparin as the anticoagulant agent. Further, using mixtures of heat-treated and normal RBC and various percentile values of the transit time histogram, we have been able to demonstrate the presence of sub-populations of rigid cells and thus the value of measurements which allow statistical analyses of RBC populations.
Keywords: RBC deformability, transit time, filtration, sub-populations
vol. 25, no. 5, pp. 773-790, 1988
Abstract: The aim of this study was to determine the red blood cell (RBC) disaggregability dependance upon the RBC shape. The study concentrated on stored blood during bank storage and on suspensions of artificially induced echinocytes. Measurements was performed in autologous plasma of hematocrit 0.45 and at constant plasmatic content. Rheological studies using stationary viscometry, nonstationary viscometry and rheoscopy were made in order to assess different stages of the disaggregability process. Whatever the method of measurement used, the morphological interpretation of the results reveal that beyond 75 % of echinocytes within the sample, the disaggregation process is altered. The shear stresses…required to dissociate the echinocyte aggregates are significantly higher than those required to disaggregate normal RBC rouleaux.
Keywords: Red blood cell disaggregability, red blood cell morphology
vol. 25, no. 5, pp. 791-798, 1988