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  • Open Access

    ARTICLE

    Tumor Growth Modeling from the Perspective of Multiphase Porous Media Mechanics

    G. Sciumè∗,†, S.E. Shelton, W.G. Gray, C.T. Miller, F. Hussain§,¶, M. Ferrari, P. Decuzzi, B.A. Schrefler∗,¶

    Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 193-212, 2012, DOI:10.3970/mcb.2012.009.193

    Abstract Multiphase porous media mechanics is used for modeling tumor growth, using governing equations obtained via the Thermodynamically Constrained Averaging Theory (TCAT). This approach incorporates the interaction of more phases than legacy tumor growth models. The tumor is treated as a multiphase system composed of an extracellular matrix, tumor cells which may become necrotic depending on nutrient level and pressure, healthy cells and an interstitial fluid which transports nutrients. The governing equations are numerically solved within a Finite Element framework for predicting the growth rate of the tumor mass, and of its individual components, as a More >

  • Open Access

    REVIEW

    The Three Filament Model of Skeletal Muscle Stability and Force Production

    Walter Herzog, Tim Leonard, Venus Joumaa, Michael DuVall§, Appaji Panchangam

    Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 175-192, 2012, DOI:10.3970/mcb.2012.009.175

    Abstract Ever since the 1950s, muscle force regulation has been associated with the cross-bridge interactions between the two contractile filaments, actin and myosin. This gave rise to what is referred to as the "two-filament sarcomere model". This model does not predict eccentric muscle contractions well, produces instability of myosin alignment and force production on the descending limb of the force-length relationship, and cannot account for the vastly decreased ATP requirements of actively stretched muscles. Over the past decade, we and others, identified that a third myofilament, titin, plays an important role in stabilizing the sarcomere and More >

  • Open Access

    ARTICLE

    Effect of Age-Stiffening Tissues and Intraocular Pressure on Optic Nerve Damages

    Leo KK Leung, Match WL Ko, David CC Lam

    Molecular & Cellular Biomechanics, Vol.9, No.2, pp. 157-174, 2012, DOI:10.3970/mcb.2012.009.157

    Abstract Age-stiffening of ocular tissues is statistically linked to glaucoma in the elderly. In this study, the effects of age-stiffening on the lamina cribrosa, the primary site of glaucomatous nerve damages, were modeled using computational finite element analysis. We showed that glaucomatous nerve damages and peripheral vision loss behavior can be phenomenologically modeled by shear-based damage criterion. Using this damage criterion, the potential vision loss for 30 years old with mild hypertension of 25mmHg intraocular pressure (IOP) was estimated to be 4%. When the IOP was elevated to 35mmHg, the potential vision loss rose to 45%; More >

  • Open Access

    ARTICLE

    Cellular Automata Modeling of Pulmonary Inflammation

    Angela Reynolds∗,†, Kittisak Koombua, Ramana M. Pidaparti†,‡, §, Kevin R. Ward†,¶

    Molecular & Cellular Biomechanics, Vol.9, No.2, pp. 141-156, 2012, DOI:10.3970/mcb.2012.009.141

    Abstract Better understanding of the acute/chronic inflammation in airways is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. Local lung inflammation is triggered by many mechanisms within the lung, including pathogens. In this study, a cellular automata based model (CA) for pulmonary inflammation that incorporates biophysical processes during inflammatory responses was developed. The developed CA results in three possible outcomes related to homeostasis (healing), persistent infection, and resolved infection with high inflammation (inflamed state). The results from the model are validated qualitatively against other existing computational More >

  • Open Access

    ARTICLE

    Computational Study of Stented and Wrapped Aortic Aneurysms

    Feng Gao∗,†, Teruo Matsuzawa, Hiroshi Okada*

    Molecular & Cellular Biomechanics, Vol.9, No.2, pp. 127-140, 2012, DOI:10.3970/mcb.2012.009.127

    Abstract Aortic aneurysm is a pathology that involves the enlargement of the aortic diameter and has risk factors including aortic dissection. Aneurysm wrapping and stent placement has been used in the treatment of aneurysms. This study aimed to investigate the biomechanical effects of wrapping and stenting on aneurysm. The three-layered aortic aneurysm were created and fluid structure interaction were simulated in wrapped model and stented model. The results provide quantitative predictions of flow patterns and wall mechanics as well as the effects of wrapping and stenting. More >

  • Open Access

    ARTICLE

    3D Numerical Study of Tumor Microenvironmental Flow in Response to Vascular-Disrupting Treatments

    Jie Wu∗,†, Yan Cai, Shixiong Xu§, Quan Long, Zurong Ding*, Cheng Dong∗,||

    Molecular & Cellular Biomechanics, Vol.9, No.2, pp. 95-126, 2012, DOI:10.3970/mcb.2012.009.095

    Abstract The effects of vascular-disrupting treatments on normalization of tumor microvasculature and its microenvironmental flow were investigated, by mathematical modeling and numerical simulation of tumor vascular-disrupting and tumor haemodynamics. Four disrupting approaches were designed according to the abnormal characteristics of tumor microvasculature compared with the normal one. The results predict that the vascular-disrupting therapies could improve tumor microenvironment, eliminate drug barrier and inhibit metastasis of tumor cells to some extent. Disrupting certain types of vessels may get better effects. In this study, the flow condition on the networks with "vascular-disrupting according to flowrate" is the best More >

  • Open Access

    ARTICLE

    IVUS-Based Computational Modeling and Planar Biaxial Artery Material Properties for Human Coronary Plaque Vulnerability Assessment

    Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 77-94, 2012, DOI:10.3970/mcb.2012.009.077

    Abstract Image-based computational modeling has been introduced for vulnerable atherosclerotic plaques to identify critical mechanical conditions which may be used for better plaque assessment and rupture predictions. In vivo patient-specific coronary plaque models are lagging due to limitations on non-invasive image resolution, flow data, and vessel material properties. A framework is proposed to combine intravascular ultrasound (IVUS) imaging, biaxial mechanical testing and computational modeling with fluid-structure interactions and anisotropic material properties to acquire better and more complete plaque data and make more accurate plaque vulnerability assessment and predictions. Impact of pre-shrink-stretch process, vessel curvature and high More >

  • Open Access

    ARTICLE

    The Effect of Collagenase on the Critical Buckling Pressure of Arteries*

    Ricky Martinez, Hai-Chao Han

    Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 55-76, 2012, DOI:10.3970/mcb.2012.009.055

    Abstract The stability of arteries is essential to normal arterial functions and loss of stability can lead to arterial tortuosity and kinking. Collagen is a main extracellular matrix component that modulates the mechanical properties of arteries and collagen degradation at pathological conditions weakens the mechanical strength of arteries. However, the effects of collagen degradation on the mechanical stability of arteries are unclear. The objective of this study was to investigate the effects of collagen degradation on the critical buckling pressure of arteries. Arterial specimens were subjected to pressurized inflation testing and fitted with nonlinear thick-walled cylindrical… More >

  • Open Access

    ARTICLE

    Transient Bioheat Simulation of the Laser-Tissue Interaction in Human Skin Using Hybrid Finite Element Formulation

    Ze-Wei Zhang*, Hui Wang, Qing-Hua Qin∗,‡

    Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 31-54, 2012, DOI:10.3970/mcb.2012.009.031

    Abstract This paper presents a hybrid finite element model for describing quantitatively the thermal responses of skin tissue under laser irradiation. The model is based on the boundary integral-based finite element method and the Pennes bioheat transfer equation. In this study, temporal discretization of the bioheat system is first performed and leads to the well-known modified Helmholtz equation. A radial basis function approach and the boundary integral based finite element method are employed to obtain particular and homogeneous solutions of the laser-tissue interaction problem. In the boundary integral based finite element formulation, two independent fields are More >

  • Open Access

    ARTICLE

    Mesoscopic Biochemical Basis of Isogenetic Inheritance and Canalization: Stochasticity, Nonlinearity, and Emergent Landscape

    Hong Qian, Hao Ge

    Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 1-30, 2012, DOI:10.3970/mcb.2012.009.001

    Abstract Biochemical reaction systems in mesoscopic volume, under sustained environmental chemical gradient(s), can have multiple stochastic attractors. Two distinct mechanisms are known for their origins: (a) Stochastic single-molecule events, such as gene expression, with slow gene on-off dynamics; and (b) nonlinear networks with feedbacks. These two mechanisms yield different volume dependence for the sojourn time of an attractor. As in the classic Arrhenius theory for temperature dependent transition rates, a landscape perspective provides a natural framework for the system's behavior. However, due to the nonequilibrium nature of the open chemical systems, the landscape, and the attractors More >

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