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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: Rheological properties of blood vessels are expected to change in disease process if the structure of the vessel wall changes. This is illustrated in diabetes, which can be induced in rat by a single injection of Streptozocin. One of the rheological properties of the blood vessel is the stress-strain relationship. The nonlinear stress-strain relationship of arteries is best expressed as derivations of a strain-energy function. In this paper, the stress-strain relations are measured and the coefficients in the strain energy function of arteries are determined for diabetic and control rats. The meaning of these coefficients are explained. The influence of…diabetes on the elastic property of the arteries is expressed by the changes of these coefficients. A point of departure of the present paper from all other blood vessel papers published so far is that all strains used here are referred to the zero-stress state of the arteries, whereas all other papers refer strains to the no-load state . The existence of a large difference between the zero-stress state and no-load state of arteries is one of our recent findings. We have explained that the use of zero-stress state as a basis of strain measurements reveals that the in vivo circumferential stress distribution is quite uniform in the vessel wall at the homeostatic condition. It also makes the strain energy function much more accurate than those in which the residual stress is ignored. Using these new results, the stress and strain distributions in normal and diabetic arteries are presented.
Keywords: Rheological properties, pulmonary and systemic arteries, diabetes
vol. 29, no. 5-6, pp. 443-457, 1992
Abstract: Epithelial wound repair represents an important process by which the epithelial barrier integrity recovers after wounding. To evaluate and quantify the dynamics of surface airway cell movement during the wound repair process, we developed an in vitro wounding model of human respiratory cells in culture and we analyzed the wound repair by using videomicroscopic and image analysis techniques. We observed that wound closure occurred within 6 hours, due to the spreading and migration of the cells surrounding the wounded surface. The migration rate of the cells at the leading edge of the wound surface increased progressively up to 26…μ m/h during the repair process which was characterized by a uniform centripetal direction of cell movement. The distance travelled by these cells was 2.5 fold longer than the distance travelled by ciliated cells which were located far from the wound area. These results suggest that cell migration after wounding is an important process by which the respiratory epithelial barrier integrity is maintained.
Abstract: The elasticity of red cell membrane was determined in a rectangular flow channel under controlled shear flow. The relation between shear stress and cell extension ratio (λ ) has been analyzed with the use of Evans’ two-dimensional model. The deformed cell shapes observed experimentally agreed well with the model with λ up to 1.4. The best correlation was found at λ = 1.2. The analysis suggests a nonlinear extensional membrane modulus in the low stress range encountered in the flow channel. In terms of an appropriate strain parameter, the elastic modulus is shown to rise toward the level…encountered in micropipette aspiration experiments. The implications of the present findings in modeling of cell mechanics and in cell hemolysis are discussed.
Abstract: The partial plug flow of a concentrated suspension of rigid particles in a circular tube has been previously studied experimentally. It has been shown that a central core may exist in which the mean velocities of the particles and the suspending fluid are equal and constant within a cylindrical core of the flow. This behavior has been attributed to hydrodynamic interaction of the particles within the core. In the present analysis this interaction is interpreted in terms of passing vs. non-passing motions of adjacent particles. A hypothesis of a critical parameter α c involving the shear stress and…the pressure gradient is explored and a new form of the relation of core diameter to particle size and concentration is developed based on α c .
Keywords: Plug flow, suspensions
vol. 29, no. 5-6, pp. 479-488, 1992
Abstract: Platelet adhesion and aggregation were induced on cultured endothelial cells using the fluorescent dye/light method. A cone-and-plate apparatus was newly developed to observe interactions between platelets and cultured endothelial cells under a shear flow condition. The platelet deposition grew on the light-irradiated area of the cells. Degree of endothelial cell injury induced by the dye/light reaction seemed to depend on the dye concentration. Application of either aspirin or indomethacin significantly inhibited the growth of platelet aggregation, but was not effective for the platelet adhesion to endothelial cells. The platelet thrombi were formed on endothelial cells without their denudation. It was…found by transmission electron microscopy that platelets directly adhered to endothelial cells which were not seriously damaged. This thrombus model is expected to be applicable to some physiological and pharmacological studies investigating platelet-endothelial cell interaction and mechanism of platelet thrombus formation in blood vessels.
Keywords: Platelet thrombus, aggregation, cultured endothelial cell, shear flow, dye/light reaction, in vitro model
vol. 29, no. 5-6, pp. 489-498, 1992
Abstract: Micropipettes as research instruments are well established in cell biology, including blood rheology. However, the experimental results are, to some extent, dependent on the quality of the pipette itself; it is usually critical to have the desired pipette internal diameter and a perpendicular tip. Pipette fabrication is a two-step procedure involving: a) the pulling of the pipette from a glass capillary; b) the trimming of the pipette tip. A common method to trim and fracture the pipette tip is the use of a melted glass bead on a heated tungsten wire. Previous devices using this method were often associated with…problems because the heated wire varied in length with temperature. As a result, the bead together with the attached pipette tip moved markedly and thus hampered the possibility to obtain a perpendicularly cut pipette tip. An improved design, based on the same principle with a melted glass bead, is thus suggested; it eliminates the problem with a moving glass bead and, in addition, allows semi-automatic pipette trimming by utilizing the heat-induced elongation/retraction of the heated wire to fracture the tip without requiring manual assistance. Furthermore, a simple pipette storing technique is suggested, based on standard laboratory utensils, in order to more easily handle fragile pipettes without risk of breakage.
Abstract: A study of the labelling of isolated resealed erythrocyte membranes by TMA-DPH has been carried out. A quantitative study shows that saturation appears to take place when increasing the relative quantity of probe bulk concentration to membrane concentration; this is readily interpreted by a simple incorporation model with a limited number of sites in the membrane. A qualitative study shows that an increase in the labelling leads to an evolution of the probe fluorescence properties; the existence of different types of sites is involved in the interpretation but the system is too complex to allow it to be represented by…a simple model. As a consequence of this study, care has to be taken in labelling biological material so as to avoid excessive probe incorporation.
Abstract: The rheological properties of the vitreous body of the eye are believed to be a function of composition and to differ among species, as well as to vary regionally within the vitreous. These properties are essential to the mechanical functioning of the eye. Although there are gross, qualitative data on vitreous rheology available in the literature, quantitative rheological measurements on human vitreous and on eyes of other species are sparse and incomplete. The aim of the research reported in this series of papers is to study the rheological behavior of human, bovine, and porcine vitreous, to measure the macromolecular and…electrolyte content of these samples, and to correlate and compare these values for the different species as a function of location in the vitreous. In this paper, the rheological model used to correlate viscoelasticity of the vitreous is presented, and a detailed description of the rheological instrumentation and methods of analysis used is given. Data on the rheological properties of human vitreous, as a function of location within the eye, are presented. The results show that in the human eye there are significant differences in a number of the viscoelastic parameters as a function of location within the vitreous body.
Keywords: Vitreous body, viscoelasticity, creep, compliance, human eye
vol. 29, no. 5-6, pp. 521-533, 1992
Abstract: A mathematical model has been constructed to investigate the alterations, in amount and in importance, of the Factors controlling interstitial fluid volume in a number of steady-state oedemas. There are many so-called “Safety Factors” (at least 15), including a whole group concerned with regulating the amount of protein in the tissues (and thus tissue colloidal osmotic pressure). They are often in long hierarchies (of even up to 11 Factors), each influencing the next. Sometimes a Factor is recursive, i.e. , it influences itself (either positively or negatively) via a Hierarchy of other Factors. The effects of some Factors differ…in different Hierarchies, i.e. , an increase in the Factor will increase VI via some of the Hierarchies and decrease it via some other Hierarchies. Which effect is most important varies with the Hierarchies and conditions existing at the time. The Factors are best compared if expressed in the same units: ml/min/100g of tissue. This is possible via appropriate multiplication factors derived from the relevant equations.
Keywords: Interstitial fluid volume—variations in, hierarchies of safety factors, steady-states, oedemas—low and high protein, proteolysis in the tissues, benzo-pyrones
vol. 29, no. 5-6, pp. 535-548, 1992
Abstract: Recent animal studies have suggested that there exists an activated subpopulation of circulating granulocytes which plays an important part in microvascular sequestration and tissue injury during shock and ischemia. In this respect, spontaneous granulocyte activation in form of pseudopod formation, a manifestation of actin polymerization, is a high risk for microvascular entrapment. The present investigation was carried out to determine if there is a significant difference in pseudopod formation in vitro between granulocytes obtained from healthy volunteers without symptoms and patients with acute cardiovascular illnesses. Blood samples from 25 healthy volunteers, 12 patients with acute myocardial infarction (AMI) and…12 patients with acute cerebral infarction (ACI) to determine spontaneous pseudopod formation in granulocytes with a high resolution light microscope over a period of several hours. The results revealed that the mean percentage of cells with pseudopod formation in the control group was below 10% in the first 3 hours, and increased to about 50% at 12 hours. In AMI patients, the level of activation within the first hour was not significantly different from the controls, but it rose rapidly to 90% in 4 to 5 hours. Patients with cerebral infarction, however, showed no significant difference from the control group. When the granulocytes of healthy subjects were incubated in plasma of AMI, the cells were activated similar to AMI granulocytes in their own plasma. When AMI plasma was serially diluted with Ringer’s solution, the activation curve fell successively. These results indicate that AMI patients’ blood contains plasma factor(s) which can activate granulocytes at a more rapid rate than controls.
Abstract: Flow studies were done in an elastic true-to-scale silicone rubber model of an aortic arch to study further hemodynamic influences on atherosclerosis. The model was prepared from a cast of a young woman. A revised model technique was used. The model had a compliance similar to that of the human aortic arch. Velocity measurements were done. in the model with a two component laser-Doppler-anemometer in steady and pulsatile flow using a calcium chloride solution with a viscosity of η = 3.18 mPas and density of ρ = 1.28 kg/m3 at 20°C. The time average Reynolds numbers over…a whole cycle in the ascending aorta was Re = 1350. The Womersley parameter for pulsatile flow was a = 20. The pulse wave velocity in the ascending aorta was about c = 5.4 m/sec. The secondary flow behavior was discussed for steady and pulsatile flow. Reverse flows were found, especially along the inner radius of the aortic arch in the descending aorta in steady and pulsatile flow and also in small areas of the ascending aorta and at the branches of the aortic arch. The formation of atherosclerotic plaques at preferred local flow regions is discussed.
Keywords: Laser-Doppler-anemometer, flow visualization, elastic true-to-scale model, human aortic arch
vol. 29, no. 5-6, pp. 563-580, 1992