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… 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 More >

Benjamin L. Wong^*, Won C. Bae^*, Kenneth R. Gratz^*, Robert L. Sah^∗,†

Molecular & Cellular Biomechanics, Vol.5, No.3, pp. 197-206, 2008, DOI:10.3970/mcb.2008.005.197

Abstract During joint articulation, the biomechanical behavior of cartilage not only facilitates load-bearing and low-friction, but also provides regulatory cues to chondrocytes. Elucidation of cartilage kinematics under combined compression and shearing conditions clarifies these cues in health and disease. The objectives of this study were to elucidate the effects of lubricant, tissue degeneration, and stress relaxation duration on cartilage shear kinematics during articulation. Human osteochondral cores with normal and mildly degenerate surface structures were isolated. Paired blocks from each core were apposed, compressed, allowed to stress relax for 5 or 60 min, and shear tested with… More >

Hong Qian^*

Molecular & Cellular Biomechanics, Vol.5, No.2, pp. 107-118, 2008, DOI:10.3970/mcb.2008.005.107

Abstract At the molecular and cellular level, mechanics and chemistry are two aspects of the same macromolecular system. We present a bottom-up approach to such systems based on Kramers' diffusion theory of chemical reactions, the theory of polymer dynamics, and the recently developed models for molecular motors. Using muscle as an example, we develop a viscoelastic theory of muscle in terms of an simple equation for single motor protein movement. Both A.V. Hill's contractile component and A.F. Huxley's equation of sliding-filament motion are shown to be special cases of the general viscoelastic theory of the active More >

Shaohua Chen^*

Molecular & Cellular Biomechanics, Vol.5, No.2, pp. 97-106, 2008, DOI:10.3970/mcb.2008.005.097

Abstract Recently, contact mechanics has been widely used to get some understanding of the biological adhesion mechanisms, such as cell-cell adhesion, insects' adhesion and locomotion. JKR theory is usually adopted as a basis, in which the interaction of molecules is considered in contrast to the classical Hertz solution. In this paper, two problems are summarized, which may give some insights to cells or bio-molecules sensitivity to environmental signals: (1) cell reorientation on a stretched substrate; (2) spontaneous detachment between cells or bio-molecules under the variation of environmental signals. The intention here is only to illustrate the… More >

Geert W. Schmid-Schönbein^*

Molecular & Cellular Biomechanics, Vol.5, No.2, pp. 83-96, 2008, DOI:10.3970/mcb.2008.005.083

Abstract Increasing evidence suggests that most cardiovascular diseases, tumors and other ailments are associated with an inflammatory cascade. The inflammation is accompanied by activation of cells in the circulation and fundamental changes in the mechanics of the microcirculation, expression of pro-inflammatory genes and downregulation of anti-inflammatory genes, attachment of leukocytes to the endothelium, elevated permeability of the endothelium, and many other events. The evidence has opened great opportunities for medicine to develop new anti-inflammatory interventions. But it also raises a fundamental question: What is the origin of inflammation? I will discuss a basic series of studies that was… More >

Yuliya Vengrenyuk^*, Luis Cardoso^*, Sheldon Weinbaum^∗,†

Molecular & Cellular Biomechanics, Vol.5, No.1, pp. 37-48, 2008, DOI:10.3970/mcb.2008.005.037

Abstract In this paper, we further investigate the new paradigm for the rupture of thin cap fibroatheroma (TCFA) proposed in Vengrenyuk et al. (2006 PNAS 103:14678) using a multilevel micro-CT based 3D numerical modeling. The new paradigm proposes that the rupture of TCFA is due to stress-induced interfacial debonding of cellular - level, 10 -- 20 μm microcalcifications in the fibrous cap proper. Such microcalcifications, which lie below the visibility of current in vivo imaging techniques, were detected for the first time using confocal microscopy and high resolution microcomputed tomography (micro-CT) imaging in Vengrenyuk et al. (2006) In the present… More >

Jizeng Wang^*, Jin Qian^*, Huajian Gao^∗,†

Molecular & Cellular Biomechanics, Vol.5, No.1, pp. 19-26, 2008, DOI:10.3970/mcb.2008.005.019

Abstract Experiments have shown that stable adhesion of a variety of animal cells on substrates prepared with precisely controlled ligand distribution can be formed only if the ligand spacing is below 58 nm. To explain this phenomenon, here we propose a confined polymer model to study the stability of molecular adhesion mediated by polymer repellers and ligand-receptor bonds. In this model, both repellers and binders are treated as wormlike chains confined in a nanoslit, and the stability of adhesion is considered as a competition between attractive interactions of ligand-receptor binding and repulsive forces due to the More >

Jin Suo^*, John N. Oshinski^∗,†, D.P. Giddens^∗,‡

Molecular & Cellular Biomechanics, Vol.5, No.1, pp. 9-18, 2008, DOI:10.3970/mcb.2008.005.009

Abstract Atherosclerotic plaques in human coronary arteries are focal manifestations of systemic disease, and biomechanical factors have been hypothesized to contribute to plaque genesis and localization. We developed a computational fluid dynamics (CFD) model of the ascending aorta and proximal sections of the right and left coronary arteries of a normal human subject using computed tomography (CT) and magnetic resonance imaging (MRI) and determined the pulsatile flow field. Results demonstrate that flow patterns in the ascending aorta contribute to a pro-atherosclerotic flow environment, specifically through localization of low and oscillatory wall shear stress in the neighborhood… More >

Shu Chien^*

Molecular & Cellular Biomechanics, Vol.5, No.1, pp. 1-8, 2008, DOI:10.3970/mcb.2008.005.001

Abstract Fluid shear stress due to blood flow can modulate functions of endothelial cells (ECs) in blood vessels by activating mechano-sensors, signaling pathways, and gene and protein expressions. Laminar shear stress with a definite forward direction causes transient activations of many genes that are atherogenic, followed by their down-regulation; laminar shear stress also up-regulates genes that inhibit EC growth. In contrast, disturbed flow patterns with little forward direction cause sustained activations of these atherogenic genes and enhancements of EC mitosis and apoptosis. In straight parts of the arterial tree, laminar shear stress with a definite forward More >