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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: Previous numerical modeling studies on red blood cell (RBC) aggregation have elucidated the inverse relationship between shear rate and RBC aggregation under steady flow. However, information on the cyclic variation in RBC aggregation under pulsatile flow remains lacking. OBJECTIVE: RBC aggregation was simulated to investigate the complex interrelationships among the parameters of RBC motion under pulsatile flow. METHODS: A two-dimensional particle model was used to simulate RBC motion driven by hydrodynamic, aggregation, and elastic forces in a sinusoidal pulsatile flow field. The kinetics of RBCs motion was simulated on the basis of the depletion model.…RESULTS: The simulation results corresponded with previously obtained experimental results for the formation and destruction of RBC aggregates with a parabolic radial distribution during a pulsatile cycle. In addition, the results demonstrated that the cyclic variation in the mean aggregate size of RBCs increased as velocity amplitude increased from 1 cm/s to 3 cm/s under a mean steady flow of 2 cm/s, as mean steady flow velocity decreased from 6 cm/s to 2 cm/s under a velocity amplitude of 1.5 cm/s, and as stroke rate decreased from 180 beats per minute (bpm) to 60 bpm. CONCLUSIONS: The present simulation results verified previous experimental results and improved the current understanding of the complex spatiotemporal changes experienced by RBC aggregates during a sinusoidal pulsatile cycle.
Keywords: Red blood cell aggregation, rouleaux, mean aggregate size, hemodynamics, sinusoidal pulsatile cycle, Poiseuille flow
Abstract: BACKGROUND: Isokinetic exercise is used to reduce strength imbalance and to enhance performance. OBJECTIVE: The aim of this study was to investigate the acute effects of a single bout of eccentric isokinetic exercise on hemorheology (erythrocyte deformability and aggregation), total oxidant/antioxidant status (TOS/TAS) and oxidative stress index (OSI) in active individuals. METHODS: The study comprises 11 active, healthy, male subjects (mean age of 19.45 ± 0.31 years, BMI 22.05 ± 0.51 kg/m2 ). They performed single, unilateral eccentric contractions of knee flexors and extensors with dominant leg on a dynamometer. Isokinetic hamstring, quadriceps strength were recorded…at eccentric (30, 120° s−1 ) angular velocities. Eight active age-matched healthy male subjects were included as a control group, who did not receive exercise. Blood samples were obtained before, immediately after and two days after the exercise session. Hemorheological parameters were measured by an ektacytometer. TOS/TAS were determined using a commercial kit. RESULTS: A session of eccentric isokinetic exercise did not affect erythrocyte deformability and oxidative stress indices, whereas red blood cell (RBC) aggregation was increased initially and returned to pre-exercise levels after two days following exercise. CONCLUSION: Our results suggest that, increased RBC aggregation following an acute bout of isokinetic exercise may result in increased plasma skimming that augments tissue perfusion and clearance of metabolites within a period of two days following exercise.
Keywords: Hemorheology, oxidative stress, eccentric exercise, red blood cell aggregation
Abstract: BACKGROUND: The venous response to elevated blood pressure (BP) is of major importance because it is closely related to the etiology of venous diseases and the competency of vein grafts. In vitro culture experiments may provide useful information on the phenomena and mechanisms of venou remodeling, because it is easier to separate mechanical and hemodynamic effects from other systemic influences compared to in vivo experiments. OBJECTIVE: To study the effects of BP elevation on wall dimensions and mechanical properties of in vitro cultured veins. METHODS: Rabbit femoral veins were cultured in vitro under…internal pressures of 1 to 50 mmHg for 1 week, and their wall dimensions, biomechanical properties, and histology were determined. RESULTS: No significant differences were observed in internal vein diameter and wall thickness among vessels cultured at 10–50 mmHg and non-cultured control vessels. For an internal pressure of 10 mmHg applied to vessels during culture (equivalent to in vivo working BP), wall circumferential stress was maintained within control levels. There were no significant effects of pressure on basal tone and contractility of vascular smooth muscle and vascular compliance. CONCLUSIONS: The in vitro results were essentially similar to those obtained from previous in vivo animal experiments, indicating that in vitro tissue culture techniques are applicable to studies of venous remodeling.
Abstract: BACKGROUND: Hyaluronic acid (HA) is a polysaccharide present in almost all animal tissues, in which it carries out important biological functions, among them, the protection of the joints by lubricating them and dampening the tension in them. OBJECTIVE: This study compares the viscoelastic properties of several commercial preparations of HA, to determine their suitability for use as viscosupplementation therapy in joint pathology (osteoarthritis). METHODS: 4 HA hydrogels: Durolane® , Synocrom_Forte_One® , Synvisc_One® and Viscoplus_Matrix® and 4 HA solutions: Ostenil® , Ostenil_Plus® , Viscoplus_Gel® and Orthovisc® were analyzed to compare their viscoelatsic rheological parameters using an…oscillatory-rotational rheometer. RESULTS: With respect to the 4 HA hydrogels, comparison of crossover frequencies allowed division into two main groups: Synvisc_One® and Viscoplus_Matrix® , with crossover frequencies in the order of magnitude of 10−2 Hz, while Synocrom_Forte_One® and Durolane® showed crossover frequencies on the order of 10−1 Hz. Only one of the 4 HA solutions, Viscoplus_Gel® , showed a crossover frequency on the order of 10−2 , whereas Ostenil_Plus® and Orthovisc® showed crossover frequencies on the order of 10−1 , and Ostenil® remained as a predominantly viscous fluid for frequencies as high as 4.8 Hz. CONCLUSIONS: The viscoelastic properties of the HA preparations can be ordered according to the values of G ∗ (the rigidity, or vector sum of the elastic modulus G ′ and the viscous modulus G ′′ ) at both transition points (0.5 and 2.5 Hz) as follows: Viscoplus_Matrix® > Viscoplus_Gel® > Durolane® > Synocrom_Forte_One® > Ostenil_Plus® > Synvisc_One® > Orthovisc® > Ostenil® .
Abstract: BACKGROUND: It is generally unknown if taste sensitivity is dependent upon saliva viscosity. The rheological properties of saliva result from many factors and it has been shown to behave as a non-Newtonian fluid whose viscosity decreases with increasing shear rate. Taste sensitivity may be quantitatively assayed by electro-gustometry. OBJECTIVES: The aim of this work was to compare saliva rheological properties, obtained with a rotary-oscillating rheometer, to quantitative measures of taste sensitivity, using electro-gustometry. METHODS: Saliva samples were taken from 27 healthy non-smoking donors – 7 men and 20 women aged 18–65 years (mean age – 37…years). After thresholds of taste sensation were measured, the saliva samples were taken and characterized in terms of their rheological properties and pH. Saliva viscosity was measured in the order of decreasing shear rate in the range 100–0.01 s−1 . Viscoelastic properties were examined under constant frequency oscillations (with f = 0.5 Hz) and with decreasing shear effective amplitude γ e f f ′ . RESULTS and CONCLUSIONS: Saliva viscosity was found to decrease with increasing shear rate and varied with time. Analysis of the dependence of the viscosity values of saliva and components of complex viscosity did not show a significant correlation with taste sensation. A dependency of taste sensation on pH could not be discerned due to the narrow range of naturally occurring pH.