Yanan Wang^∗, Qing-Hua Qin^∗, Shankar Kalyanasundaram^∗

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 101-112, 2009, DOI:10.3970/mcb.2009.006.101

Abstract A mathematical model is developed for simulating anabolic behaviour of bone affected by Parathyroid Hormone (PTH) in this paper. The model incorporates a new understanding on the interaction of PTH and other factors with the RANK-RANKL-OPG pathway into bone remodelling, which is able to simulate anabolic actions of bone induced by PTH at cellular level. The RANK-RANKL-OPG pathway together with the dual action of TGF-$\beta$, which represent the core of coupling behaviour between osteoblasts and osteoclasts which are two cell types specialising in the maintenance of bone integrity, are widely considered essential for the regulation of bone remodelling at cellular… More >

Hai-Chao Han^†

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 93-100, 2009, DOI:10.3970/mcb.2009.006.093

Abstract Though tortuosity and kinking are often observed in various arteries and arterioles, little is known about the underlying mechanisms. This paper presents a biomechanical analysis of bent buckling in long arterial segments with a small initial curvature using a thick-walled elastic cylindrical arterial model. The critical buckling pressure was established as a function of wall stiffness, wall dimensions, and the axial tension (or axial stretch ratio). The effects of both wall dimensions and axial stretch ratio on the critical pressure, as well as the thin-walled approximation were discussed. The buckling equation sheds light on the biomechanical mechanism of artery tortuosity… More >

Sangho Kim^∗,†, Peng Kai Ong^*, Paul C. Johnson^‡

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 83-92, 2009, DOI:10.3970/mcb.2009.006.083

Abstract Recently, we reported that collision efficiency (fraction of total collisions that result in the formation of aggregates) between red blood cells was an important factor in the formation of aggregates in postcapillary venules. In the present study, we focus on how high molecular weight dextran influences the overall radial migration trend of red blood cells in the postcapillary venule along a longitudinal distance of 50 μm from the bifurcation which would in turn affect collision behavior of these cells. A radial migration index, which defines the extent of radial migration of individual cells relative to the vessel center, was found… More >

Arthur J. Sit^*, John H.K. Liu^†

Molecular & Cellular Biomechanics, Vol.6, No.1, pp. 57-70, 2009, DOI:10.3970/mcb.2009.006.057

Abstract Glaucoma is a leading cause of visual impairment and blindness worldwide. The main risk factor for glaucoma is an elevated intraocular pressure (IOP), which is also the only currently treatable risk factor. Despite its importance, our understanding of IOP is incomplete and our ability to measure IOP is limited. IOP is known to undergo both random fluctuations as well as variations following a circadian pattern. In humans, IOP is highest at night and lower during the daytime, largely due to changes in body position, although other factors appear to contribute. In rabbits, IOP is also highest at night and lower… More >

Chen X.Y.^∗,†, Liu Y.^2,‡, Fu B.M.^§, Fan J.T.^¶, Yang J.M.¹

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 275-284, 2008, DOI:10.3970/mcb.2008.005.275

Abstract Surface glycocalyx, as a barrier to material exchange between circulating blood and body tissues, can be treated as a periodic square array of cylindrical fibers. Previous study treated the glycocalyx as porous media and simulated by continuum theory. However, it has recently been found that a relatively hexagonal fibre-matrix structure may be responsible for the ultrafiltration properties of microvascular walls. The fibre-matrix is an underlaying three-dimensional meshwork with a fibre diameter of 10$\sim$12 nm and characteristic spacing of about 20 nm. The porous medium model does not consider the particle size, when the particle size is comparable to the fibre… More >

Chun Yang^∗,†, Dalin Tang^∗,‡, Shunichi Kobayashi^§, Jie Zheng^¶, Pamela K. Woodard^§, Zhongzhao Teng^*, Richard Bach^||, David N. Ku^∗∗

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 259-274, 2008, DOI:10.3970/mcb.2008.005.259

Abstract Many acute cardiovascular syndromes such as heart attack and stroke are caused by atherosclerotic plaque ruptures which often happen without warning. MRI-based models with fluid-structure interactions (FSI) have been introduced to perform flow and stress/strain analysis for atherosclerotic plaques and identify possible mechanical and morphological indices for accurate plaque vulnerability assessment. In this paper, cyclic bending was added to 3D FSI coronary plaque models for more accurate mechanical predictions. Curvature variation was prescribed using the data of a human left anterior descending (LAD) coronary artery. Five computational models were constructed based on ex vivo MRI human coronary plaque data to… More >

Colin K. Choi^*, Brian P. Helmke^∗,†

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 247-258, 2008, DOI:10.3970/mcb.2008.005.247

Abstract Hemodynamic shear stress guides a variety of endothelial phenotype characteristics, including cell morphology, cytoskeletal structure, and gene expression profile. The sensing and processing of extracellular fluid forces may be mediated by mechanotransmission through the actin cytoskeleton network to intracellular locations of signal initiation. In this study, we identify rapid actin-mediated morphological changes in living subconfluent and confluent bovine aortic endothelial cells (ECs) in response to onset of unidirectional steady fluid shear stress (15 dyn/cm²). After flow onset, subconfluent cells exhibited dynamic edge activity in lamellipodia and small ruffles in the downstream and side directions for the first 12 min; activity… More >

Abhijit Sinha Roy^*, Lloyd H. Back^†, Rupak K. Banerjee^‡

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 229-246, 2008, DOI:10.3970/mcb.2008.005.229

Abstract The in vivo and ex vivo compliance of arteries are expected to be closely related and estimated. Fluid-structure interaction analysis can assess the agreement between the two compliances. To evaluate this hypothesis, a pulsatile fluid-structure interaction analysis of blood flow in femoral artery of a dog was conducted using: (1) measured in vivo mean pressure (72.5 mmHg), mean pressure drop (0.59 mmHg), mean velocity (15.1 cm/sec); and (2) ex vivo measurements of non -- linear elastic properties of femoral artery. Additional analyses were conducted for physiological pressures (104.1 and 140.7 mmHg) and blood flow using a characteristic linear pressure --… More >

Jie Wu^∗,†, Quan Long^‡, Shixiong Xu^*, Anwar R. Padhani^§, Yuping Jiang^¶

Molecular & Cellular Biomechanics, Vol.5, No.4, pp. 217-228, 2008, DOI:10.3970/mcb.2008.005.217

Abstract In this paper, a 3D mathematical model of tumour angiogenesis is developed, to generate a functional tumour vasculature for blood microcirculation. The model follows that of Anderson and Chaplain (1998) ^[1] with three exceptions: (a) extending the model from 2D to 3D, one arteriole and one venule is induced as two parent vessels to form an intact circulation network for blood flow; (b) generating networks able to penetrate into the tumour interior rather than the exterior only; (c) considering branching generations with different diameters, based on which three groups of vessels, such as arterioles, venules and capillaries are classified. The… More >

K.Y. Volokh ^*

Molecular & Cellular Biomechanics, Vol.5, No.3, pp. 207-216, 2008, DOI:10.3970/mcb.2008.005.207

Abstract One of the seminal contributions of Y.C. Fung to biomechanics of soft tissue is the introduction of the models of arterial deformation based on the exponential stored energy functions, which are successfully used in various applications. The Fung energy functions, however, explain behavior of intact arteries and do not include a description of arterial failure. The latter is done in the present work where Fung's model is enhanced with a failure description. The description is based on the introduction of a limiter for the stored energy -- the average energy of chemical bonds, which can be interpreted as a failure… More >