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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: Elastic properties of dipalmitoyl phosphatidylcholine bilayers were studied by an ultrasonic technique as a function of the concentration of calcium ion. The ultrasonic velocity showed a broad minimum at about 10 mM CaCl2 , indicating that the bulk modulus of membrane is smallest at this calcium ion concentration. Since the amount of calcium ions adsorbed to the membrane monotonously increases, calcium ions have two kinds of effects on the phosphatidylcholine membrane, namely softening effect at lower concentration and hardening at higher concentration. It is suggested that the softening is due to some structural change of hydrated water and the hardening…is due to chelation of lipid molecules by adsorbed calcium ions. The estimation of bulk modulus and Young’s modulus revealed that Young’s modulus and rigidity are much smaller than the bulk modulus even in the gel phase.
Abstract: To study the morphological changes in the endothelial surface of the artery induced by wall shear stress load, an arterio-venous shunt was constructed between the common carotid artery and the external jugular vein in 21 dogs. The ultrastructural changes in the endothelial surface were observed by scanning electron microscopy after the measurement of the hemodynamic parameters. In acute experiments (3 days or 1 week postoperative), the clear ultrastructural changes, such as the disturbance of the smooth folds, the fine transverse wrinkles, the small spindle swellings, the splitting of the intercellular junction of the endothelial cells and occasionally the desquamation of…the endothelial cells, were significantly observed as proportional to the elevated flow rate ratio (fs/fc, fs: flow rate of the shunted artery, fc: flow rate of the control artery). In subacute experiments (2 or 4 weeks postoperative), the small spindle swellings were observed in the shunted artery with high flow rate ratio. In chronic experiments (5 or 6 months postoperative), these changes were less proportional to the flow rate ratio. These morphological changes were significant in the disturbance of the endothelial barrier in acute experiments and they were significant in adaptive regulatory change in the chronic experiments. These support our previous observation (Am. J. Physiol. 239, H14-21, 1980). The possibility of the wall shear stress for atherogenesis was discussed.
Abstract: The reaction order of the clotting process of milk-rennet system was determined by an analysis of clotting curves obtained from the measurement of the complex rigidity at various concentrations of milk and rennet under the conditions of fixed weight ratio of rennet to milk. The results obtained show that the clotting process of milk-rennet system after gelation begins is described by a single first order reaction. At constant weight ratio of rennet to skim milk, it was found that G ∞ ′ increases almost linearly with increasing temperature. Under the conditions of a…constant milk concentration and temperature, the latent period is inversely proportional to the enzyme concentration and the rate constant of gelation is proportional to the enzyme concentration. These results were discussed in terms of Payens’ theory of enzymatic clotting processes and Ziff’s theory of the kinetics of polymer gelation.
Abstract: The flow behaviors of white blood cells (WBCs) in frog’s pulmonary microvessels were recorded and analyzed by means of a microscope-TV camera system. When the flow velocity in arterioles was reduced to a level lower than 1 mm/sec by a moderate overinflation of the exposed lung, WBCs rolled on the endothelial surface, frequently came in contact with the capillary orifice and passed it quickly without deformation. The time length which was required for WBCs to pass through the capillary orifice was shorter than the time length for red blood cells. This observation suggested that WBCs were no hinderance to blood…delivery from arterioles to the capillary network in the normal and moderate overinflation of the lung. However, when the lung was strongly overinflated and the center line flow velocity was reduced to 0.1 mm/sec, WBCs adhered to the endothelium in ten minutes. The adhering WBCs could not be detached by the recovery of the blood flow. It seemed probable that a large shear stress up to 100 to 200 dynes/cm2 was necessary to pull down the interaction between the adhering WBCs and the endothelium.
Keywords: white blood cells, adhesion to endothelium, pulmonary microvessels, shear stress, bullfrog
vol. 19, no. 1-2, pp. 221-228, 1982
Abstract: The relative viscosity of normal red cell suspensions is independent of temperature at high shear rates. The relative viscosity of suspensions with normovolemic sphered erythrocytes having a reduced deformability, however, is higher at 37°C than at 20°C. It is concluded that the changes of the lipoprotein configuration within the erythrocyte membrane which are proposed to be involved in the disc-sphere-transformation of the red cell, depend on temperature and are responsible for the increased relative viscosity at 37°C.
Abstract: The hemorheological characteristics of the blood samples, obtained by venepuncture from various groups of patients, are determined. Shear stress-shear rate relationship were determined by capillary viscometer at various shear rates ranging from 1 sec−1 to 30 sec−1 . Erythrocyte sedimentation rate (ESR) was determined by Westergren method. The results indicate that at constant hematocrit, the slope of the line representing shear stress-shear rate relationship, and ESR of blood samples change, depending on the clinical conditions of the individuals. For various values of the hematocrits, the variation of the above mentioned parameters along with fibrinogen level & blood viscosity, in…various diseases are given.
Abstract: Apparent viscosity and mean channel hematocrits have been measured at various shear rates and feed hematocrits for red blood cell (RBC) suspensions flowing in two-dimensional channels. Three types of RBC were used in the suspensions: normal, partially hardened by heating at 50°C and completely hardened by glutaraldehyde fixation. Channel height was varied from 20 to 200 μ and feed hematocrit from 5 to 55 %. Measurements show that RBC deformability plays a dominant role in narrow channels and viscosity increases rapidly with decreasing cell deformability. Like in narrow tubes the apparent viscosity as well as the mean channel hematocrits…decrease as the channel height is reduced. However the apparent viscosity in a channel remains slightly higher than the viscosity in a tube of diameter equal to the channel height. These results are consistent with the existence of a cell-depleted layer near the channel walls.
Abstract: Adhesion to glass and silicone-coated surface of leukemia cells (L1210 and L5222) and their motion on an inclined plane have been investigated. The cells in quiescent fluid are subjected to the action of gravitational force: its component parallel to the surface ranges from 4.0 × 10−14 N to 4.5 × 10−13 N. The prolonged action of the gravitational force at 45° (3.3 × 10−13 N) causes the separation from the substratum of numerous cells which have adhered on a horizontal plane. When the cells passively move on the slope they are frequently arrested by adhesion which is partly…short-lived. The analysis of the leukemia cell velocity reveals good agreement with the theory describing the motion of a sphere in quiescent fluid. The translation movement of nucleated cells on an inclined plane is not, however, accompanied by rotation. On the other hand, the cells flowing in mid-stream rotate with an angular velocity predicted by the theory.