R. M. Ardito Marretta^*, G. Barbaraci^†

Molecular & Cellular Biomechanics, Vol.6, No.3, pp. 175-190, 2009, DOI:10.3970/mcb.2009.006.175

Abstract This study, through a typical aerospace systems architecture, suggests an engineering design of a human cancer cell circuitry in which a digital optimal control matrix is assigned to repair the DNA damage level and/or to trigger its apoptosis.
Here, the conceived machinery is proposed taking into account the state of the art in cancer investigation. However, it could be further generalized. The most recent studies on cancer pathologies give a predominant role to the oncosuppressor protein p53 and its antagonist, the oncogene Mdm2.
Experimental and theoretical approaches are in agreement in deducing a “digital” response of the p53 when genomic… More >

Yoshitaka Shimada^∗,†, Taiji Adachi^∗,†,‡, Yasuhiro Inoue^∗,†, Masaki Hojo^∗

Molecular & Cellular Biomechanics, Vol.6, No.3, pp. 161-174, 2009, DOI:10.3970/mcb.2009.006.161

Abstract The actin filament, which is the most abundant component of the cytoskeleton, plays important roles in fundamental cellular activities such as shape determination, cell motility, and mechanosensing. In each activity, the actin filament dynamically changes its structure by polymerization, depolymerization, and severing. These phenomena occur on the scales ranging from the dynamics of actin molecules to filament structural changes with its deformation due to the various forces, for example, by the membrane and solvent. To better understand the actin filament dynamics, it is important to focus on these scales and develop its mathematical model. Thus, the objectives of this study… More >

Anna M. Raskin^∗,†, Masahiko Hoshijima^†, Eric Swanson^†, Andrew D. McCulloch^*, Jeffrey H. Omens^∗,†,‡

Molecular & Cellular Biomechanics, Vol.6, No.3, pp. 145-160, 2009, DOI:10.3970/mcb.2009.006.145

Abstract Altered mechanical stress and strain in cardiac myocytes induce modifications in gene expression that affects cardiac remodeling and myocyte contractile function. To study the mechanisms of mechanotransduction in cardiomyocytes, probing alterations in mechanics and gene expression has been an effective strategy. However, previous studies are self-limited due to the general use of isolated neonatal rodent myocytes or intact animals. The main goal of this study was to develop a novel tissue culture chamber system for mouse myocardium that facilitates loading of cardiac tissue, while measuring tissue stress and deformation within a physiological environment. Intact mouse right ventricular papillary muscles were… More >

Dominik R. Haudenschild^∗,†, Jianfen Chen^∗,†, Nikolai Steklov^†, Martin K. Lotz^*, Darryl D. D’Lima^∗,‡

Molecular & Cellular Biomechanics, Vol.6, No.3, pp. 135-144, 2009, DOI:10.3970/mcb.2009.006.135

Abstract The actin cytoskeleton is a dynamic network required for intracellular transport, signal transduction, movement, attachment to the extracellular matrix, cellular stiffness and cell shape. Cell shape and the actin cytoskeletal configuration are linked to chondrocyte phenotype with regard to gene expression and matrix synthesis. Historically, the chondrocyte actin cytoskeleton has been studied after formaldehyde fixation - precluding real-time measurements of actin dynamics, or in monolayer cultured cells. Here we characterize the actin cytoskeleton of living low-passage human chondrocytes grown in three-dimensional culture using a stably expressed actin-GFP construct. GFP-actin expression does not substantially alter the production of endogenous actin at… More >

Xueying Huang^*, Chun Yang^†, Chun Yuan^‡, Fei Liu^‡, Gador Canton^‡, Jie Zheng^§, Pamela K. Woodard^§, Gregorio A. Sicard^¶, Dalin Tang^||

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 121-134, 2009, DOI:10.3970/mcb.2009.006.121

Abstract Image-based computational models for atherosclerotic plaques have been developed to perform mechanical analysis to quantify critical flow and stress/strain conditions related to plaque rupture which often leads directly to heart attack or stroke. An important modeling issue is how to determine zero stress state from in vivo plaque geometries. This paper presents a method to quantify human carotid artery axial and inner circumferential shrinkages by using patient-specific ex vivo and in vivo MRI images. A shrink-stretch process based on patient-specific in vivo plaque morphology and shrinkage data was introduced to shrink the in vivo geometry first to find the zero-stress… More >

Nikolai Steklov^*, Ajay Srivastava^*, K.L.P. Sung^†, Peter C. Chen^†, Martin K. Lotz^*, Darryl D. D’Lima^‡

Molecular & Cellular Biomechanics, Vol.6, No.2, pp. 113-119, 2009, DOI:10.3970/mcb.2009.006.113

Abstract The biomechanical properties of articular cartilage change profoundly with aging. These changes have been linked with increased potential for cartilage degeneration and osteoarthritis. However, less is known about the change in biomechanical properties of chondrocytes with increasing age. Cell stiffness can affect mechanotransduction pathways and may alter cell function. We measured aging-related changes in the biomechanical properties of chondrocytes. Human chondrocytes were isolated from knee articular cartilage within 48 hours after death or from osteochondral specimens obtained from knee arthroplasty. Cells were divided into two age groups: between 18 and 35 years (18 -- 35); and greater than 55 years… More >

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 >

Weijuan Yao^*, Lanping Amy Sung^†

Molecular & Cellular Biomechanics, Vol.6, No.1, pp. 71-82, 2009, DOI:10.3970/mcb.2009.006.071

Abstract Erythrocyte tropomodulin (E-Tmod) is a tropomyosin-binding and actin capping protein at the point end of the filaments. It is part of a molecular ruler that plays an important role in generating short actin protofilaments critical for the integrity of the cell membrane. Here, with the use of \textit {E-Tmod+/lacZ} mice, we demonstrated a specific E-Tmod expression in horizontal cells (HCs) in the retina, and analyzed the stress-strain relationship of HCs, vertically oriented neurons, and retinal ganglial cells (RGC) under normal and high intraocular pressure (IOP). Since their dendrites are oriented laterally in a plane and form most complicated synapses with… More >