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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: Background: Osteoarthritis is a common, localized joint disease that causes pain, stiffness and reduced mobility. Osteoarthritis is particularly common in the knees. The effects of osteoarthritis on the rheology of synovial fluid in the knees are not fully understood and consequently require further study. Objective: The purpose of this study is to investigate the effects of protein content on synovial fluid shear rheology. A secondary study outcome will include study of the temperature dependence of synovial fluid behaviour. Methods: 38 osteoarthritic synovial fluid samples were studied under shear flow. Shear properties were correlated with protein concentration. Viscosupplement…was used as a comparison and to verify measurement reliability. The effects of temperature were investigated at 20, 29 and 37°C. Results: Shear rheological properties were found to vary widely between samples, however all samples demonstrated clear non-Newtonian shear thinning behaviour. In general viscoelastic properties were lower in osteoarthritic samples than previously studied healthy synovial fluid. A moderate correlation was observed between synovial fluid dynamic moduli at a frequency of 2.5 Hz and protein concentration. Temperature was found to affect the rheology of osteoarthritic synovial fluid and was fitted with the Arrhenius model. Conclusions: Increased protein concentration has been correlated with decreased shear rheological parameters. Temperature dependence of synovial fluid was also demonstrated and modelled for use in Part 2 of this article.
Abstract: Background: Osteoarthritis is a common, localized joint disease that causes pain, stiffness and reduced mobility. The effects of osteoarthritis on the extensional rheology of synovial fluid in the knees are not fully understood and consequently require further study. Objective: The purpose of this work is to study the extensional rheology of osteoarthritic synovial fluid and to investigate a possible correlation between synovial fluid protein concentration and extensional rheology. The study will also investigate possible correlations with the shear rheology. Methods: 21 osteoarthritic synovial fluid samples were studied under extensional flow with a capillary breakup extensional rheometer.…Extensional rheological properties were correlated with protein concentration and with shear rheological properties measured in a prior study. Viscosupplement was also studied under extensional flow for comparison. Results: Extensional rheological properties were found to vary widely between samples, but in general were found to agree with previous studies. No statistically significant correlation was identified between extensional rheological properties and protein concentration. Positive correlations were identified between zero shear viscosity and terminal extensional viscosity (R-squared = 0.73), zero shear viscosity and extensional relaxation time (R-squared = 0.84), and shear relaxation time and extensional relaxation time (R-squared = 0.75). Conclusions: Appropriate CaBER operating parameters for study of osteoarthritic synovial fluid were identified. No statistically significant correlation was found to exist between protein concentration and extensional rheological parameters. Positive correlations were identified between several shear and extensional rheological parameters. The reported values for extensional viscosity and relaxation times for synovial fluid were found to be within one order of magnitude with a recent study of post mortem synovial fluid.
Keywords: CaBER, relaxation time, shear rheology, osteoarthritis, surface tension
vol. 53, no. 3-4, pp. 123-136, 2016
Abstract: Introduction: Despite current generation mechanical assist devices being designed to limit shear stresses and minimise damage to formed elements in blood, severe secondary complications suggestive of impaired rheological functioning are still observed. At present, the precise interactions between the magnitude-duration of shear stress exposure and the deformability of red blood cells (RBC) remain largely undescribed for repeated subhaemolytic shear stress duty-cycles of less than 15 s. Given that the time taken for blood to traverse mechanical devices (e.g., Bio Pump) typically ranges from 1.85–3.08 s, the present study examined the influence of repeated, short duration, supraphysiological shear stress exposure on RBC…function. Methods: RBC were exposed to shear stress duty-cycles of 64 Pa × 3 s or 88 Pa × 2 s, for 10 repeated bouts, in an annular Couette shearing system and ektacytometer. Laser diffractometry was used to measure RBC deformability before and after application of each duty-cycle. Free haemoglobin concentration and RBC morphology was also examined following shear exposure to determine cell viability. Results: Initial exposure to shear stress duty-cycles decreased RBC deformability and increased RBC sensitivity to mechanical damage. Interestingly, the pattern of change in these variables reversed and returned to baseline values within two successive duty-cycle exposures. Significant improvements in RBC deformability were then observed by the 9th repeated exposure to 64 Pa × 3 s. Conclusions: Repeat applications of short duration supraphysiological, subhaemolytic shear stress induces a biphasic RBC deformability response that appears to progressively improve initially impaired RBC populations.
Keywords: Hemorheology, mechanical damage, red blood cell, sublethal
vol. 53, no. 3-4, pp. 137-149, 2016
Abstract: Background: Limited attention has been paid to the role of beta-adrenergic blocking agents on large artery function/structure, despite being clinically useful for treating many forms of cardiovascular disease. Objective: To assess long-term consequences of beta-blocker administration on the biomechanical properties, geometry, and histological structure of two major elastic arteries. Methods: Healthy male rats received water with their food, while beta-blockade was produced in rats by adding propranolol in their drinking water. The thoracic aorta and carotid artery were resected after three months for biomechanical (failure and inflation–extension) testing along with geometrical and histological evaluation.…Results: The thoracic aorta presented increased strength longitudinally in propranolol-treated than untreated rats, resulting from increased adventitial collagen content. The distensibility of carotid artery increased in propranolol-treated rats at low-to-physiologic pressures, resulting from decreased medial collagen content. Structural remodeling was characterized by reduced lumen diameter, wall mass, and thickness-to-radius ratio. The latter, together with the greater resorption of the media than adventitia, related with the measured opening angle decrease in propranolol-treated rats. Conclusions: The geometrical/biomechanical remodeling was mediated by the hemodynamic effects of propranolol treatment, namely the reduced blood flow, and served to normalize in vivo hoop stresses as well as vessel compliance.
Abstract: Backround: Possible toxic effects of hyperoxia have been reported previously. However, the number of studies investigating the influence of hyperoxia on blood cells is limited and there are no data regarding its hemorheological effects. Objective: The aim of this study was to investigate the effects of acute hyperoxia, performed in human subjects at normal atmospheric pressure, on the rheological properties of blood. Method: The study was conducted with 12 brain death patients mechanically ventilated in the intensive care unit. The patients were ventilated with 21%, 40%, and 100% oxygen before induction of apnea testing performed for…diagnosis of brain death. Blood samples were obtained at each oxygen concentration value for all patients. Result: The results of the study indicated no significant change of red blood cell aggregation, deformability and plasma or whole blood viscosity associated with acute hyperoxia at normobaric conditions. Conclusion: The results of the study suggest that application of normobaric hyperoxia does not have detrimental effects on hemorheological parameters in brain death patients, and that organs considered for donation from such subjects are not adversely affected by abnormalities of blood flow and tissue perfusion.
Keywords: Oxygen, toxicity, erythrocyte, rheology
vol. 53, no. 3-4, pp. 171-177, 2016