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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: Laminopathies are genetic diseases caused by mutations in the nuclear lamina. OBJECTIVE: Given the clinical impact of laminopathies, understanding mechanical properties of cells bearing lamin mutations will lead to advancement in the treatment of heart failure. METHODS: Atomic force microscopy (AFM) was used to analyze the viscoelastic behavior of neonatal rat ventricular myocyte cells expressing three human lamin A/C gene (LMNA) mutations. RESULTS: Cell storage modulus was characterized, by two plateaus, one in the low frequency range, a second one at higher frequencies. The loss modulus instead showed a “bell” shape with a relaxation toward fluid properties…at lower frequencies. Mutations shifted the relaxation to higher frequencies, rendering the networks more solid-like. This increase of stiffness with mutations (solid like behavior) was at frequencies around 1 Hz, close to the human heart rate. CONCLUSIONS: These features resulted from a combination of the properties of cytoskeleton filaments and their temporary cross-linker. Our results substantiate that cross-linked filaments contribute, for the most part, to the mechanical strength of the cytoskeleton of the cell studied and the relaxation time is determined by the dissociation dynamics of the cross-linking proteins. The severity of biomechanical defects due to these LMNA mutations correlated with the severity of the clinical phenotype.
Keywords: Viscoelasticity, lamin A/C, AFM, cardiomyocytes, storage modulus, loss modulus
Abstract: BACKGROUND: Obesity-induced chronic inflammation and fibrosis in adipose tissue contributes to the progression of type 2 diabetes mellitus (DM). While fibrosis is known to induce mechanical stiffening of numerous tissue types, it is unknown whether DM is associated with alterations in adipose tissue mechanical properties. OBJECTIVE: The purpose of this study was to investigate whether DM is associated with differences in bulk viscoelastic properties of adipose tissue from diabetic (DM) and non-diabetic (NDM) obese subjects. METHODS: Bulk shear rheology was performed on visceral (VAT) and subcutaneous (SAT) adipose tissue, collected from obese subjects undergoing elective bariatric…surgery. Rheology was also performed on the remaining extracellular matrix (ECM) from decellularized VAT (VAT ECM). Linear mixed models were used to assess whether correlations existed between adipose tissue mechanical properties and DM status, sex, age, and body mass index (BMI). RESULTS: DM was not associated with significant differences in adipose tissue viscoelastic properties for any of the tissue types investigated. Tissue type dependent differences were however detected, with VAT having significantly lower shear storage and loss moduli than SAT and VAT ECM independent of DM status. CONCLUSION: Although DM is typically associated with adipose tissue fibrosis, it is not associated with differences in macroscopic adipose tissue mechanical properties.
Abstract: BACKGROUND: The gallbladder filling and emptying cycle controls bile flow into the duodenum. Disruption of this emptying and refilling cycle leads to bile stasis and subsequent gallstone formation. The bile flow rate is inversely proportional to its viscosity. Moreover, bile is a complex material with varying density in different people because of its diverse components. These density changes alter the viscosity. Prediction of shear viscosity from density measurements may thus contribute to medical assessment and treatment of the patient. OBJECTIVE: To investigate the relationship between the shear viscosity and density of bile. METHODS: Natural and filtered…bile samples were prepared for density, viscosity and pressure drop measurements. The density and shear viscosity were measured by a density meter and viscometer, respectively, and a relationship was established between them. Measurements of the pressure drop in a glass tube were used to estimate the apparent viscosity and compared with shear viscosity obtained with the viscometer. RESULTS: The natural bile with higher density showed a greater shear viscosity than the filtered bile, especially at low shear rates. Bile viscosity was proportional to density. In addition, the pressure drop of the natural samples was greater than that of the filtered sample. The viscosity measured by the viscometer deviated from the results obtained using Poiseuille’s law and the tube pressure drop measurements. The density difference between the natural and filtered bile samples was smaller than 1%. However, the viscosities of the natural and filtered bile samples varied by up to >30%. CONCLUSIONS: Porcine bile viscosity is proportional to density. Based on the bile density, one can easily evaluate the shear viscosity using a linear relationship. The density considerably influences the bile viscosity, with small density increases greatly increasing the shear viscosity.
Abstract: BACKGROUND: Despite improvements in treatment of ST-segment myocardial infarction (STEMI), thrombus formation in the left ventricle is still a concerning complication that may lead to systemic thromboembolism and stroke. OBJECTIVES: To evaluate the predictive value of estimated whole blood viscosity (WBV) for left ventricular thrombus development in patients surviving an acute anterior myocardial infarction (AAMI). MATERIALS \& METHODS: Seven hundred eighty AAMI patients who were treated percutaneously were enrolled consecutively. Serial echocardiographic examinations were performed within 24h of admission, before hospital discharge, and at 1, 3, 6 and 12 months following hospital discharge. WBV was calculated…according to de Simones formula. RESULTS: One hundred patients (12.8%) developed thrombus formation within one year following AAMI. Patients with left ventricular thrombus (LVT) had significantly higher WBV values. Supramedian values of WBV at both low (0.5 sec−1 ) and high (208 sec−1 ) shear rates were found to be an independent predictor of LVT development. CONCLUSION: As an easily accessible parameter, WBV might be a useful predictor of LVT formation within one year following acute anterior myocardial infarction.
Keywords: Blood viscosity, shear stress, left ventricular thrombus, myocardial infarction