Biorheology - Volume 53, issue 3-4

Authors: Madkhali, Anwar | Chernos, Michael | Grecov, Dana | Kwok, Ezra

Article Type: Research Article

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. Show more

Keywords: Rheopexy, dynamic moduli, temperature, centrifugation

DOI: 10.3233/BIR-15078

Citation: Biorheology, vol. 53, no. 3-4, pp. 111-122, 2016

Authors: Madkhali, Anwar | Chernos, Michael | Fakhraei, Samin | Grecov, Dana | Kwok, Ezra

Article Type: Research 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. Show more

Keywords: CaBER, relaxation time, shear rheology, osteoarthritis, surface tension

DOI: 10.3233/BIR-15086

Citation: Biorheology, vol. 53, no. 3-4, pp. 123-136, 2016

Authors: McNamee, Antony P. | Tansley, Geoff D. | Sabapathy, Surendran | Simmonds, Michael J.

Article Type: Research Article

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. Show more

Keywords: Hemorheology, mechanical damage, red blood cell, sublethal

DOI: 10.3233/BIR-15108

Citation: Biorheology, vol. 53, no. 3-4, pp. 137-149, 2016

Authors: Lampropoulos, Konstantinos M. | Sokolis, Dimitrios P.

Article Type: Research Article

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. Show more

Keywords: Elastic arteries, propranolol, mechanical testing, histomorphometry, beta-blockade

DOI: 10.3233/BIR-16090

Citation: Biorheology, vol. 53, no. 3-4, pp. 151-170, 2016

Authors: Ulker, Pinar

Article Type: Research Article

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. Show more

Keywords: Oxygen, toxicity, erythrocyte, rheology

DOI: 10.3233/BIR-16096

Citation: Biorheology, vol. 53, no. 3-4, pp. 171-177, 2016