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  • Open Access


    Partial Contact Indentation Tonometry for Measurement of Corneal Properties-Independent Intraocular Pressure

    Match W L Ko, Leo K K Leung, David C C Lam∗,†

    Molecular & Cellular Biomechanics, Vol.9, No.4, pp. 251-268, 2012, DOI:10.3970/mcb.2012.009.251

    Abstract Inter-individual differences in corneal properties are ignored in existing methods for measuring intraocular pressure IOP, a primary parameter used in screening and monitoring of glaucoma. The differences in the corneal stiffness between individuals can be more than double and this difference would lead to IOP measurement errors up to 10 mmHg. In this study, an instrumented partial-contact indentation measurement and analysis method that can account for inter-individual corneal difference in stiffness is developed. The method was tested on 12 porcine eyes ex vivo and 7 rabbit eyes in vivo, and the results were compared to the controlled IOPs to determine… More >

  • Open Access


    Effect of Matrix on Cardiomyocyte Viscoelastic Properties in 2D Culture

    Sandra Deitch, Bruce Z. Gao, Delphine Dean

    Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 227-250, 2012, DOI:10.3970/mcb.2012.009.227

    Abstract Cardiomyocyte phenotype changes significantly in 2D culture systems depending on the substrate composition and organization. Given the variety of substrates that are used both for basic cardiac cell culture studies and for regenerative medicine applications, there is a critical need to understand how the different matrices influence cardiac cell mechanics. In the current study, the mechanical properties of neonatal rat cardiomyocytes cultured in a subconfluent layer upon aligned and unaligned collagen and fibronectin matrices were assessed over a two week period using atomic force microscopy. The elastic modulus was estimated by fitting the Hertz model to force curve data and… More >

  • Open Access


    Dynamic Lung Modeling and Tumor Tracking Using Deformable Image Registration and Geometric Smoothing

    Yongjie Zhang, Yiming Jing, Xinghua Liang, Guoliang Xu, Lei Dong

    Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 213-226, 2012, DOI:10.3970/mcb.2012.009.213

    Abstract A greyscale-based fully automatic deformable image registration algorithm, based on an optical flow method together with geometric smoothing, is developed for dynamic lung modeling and tumor tracking. In our computational processing pipeline, the input data is a set of 4D CT images with 10 phases. The triangle mesh of the lung model is directly extracted from the more stable exhale phase (Phase 5). In addition, we represent the lung surface model in 3D volumetric format by applying a signed distance function and then generate tetrahedral meshes. Our registration algorithm works for both triangle and tetrahedral meshes. In CT images, the… More >

  • Open Access


    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 function of the initial tumor-to-healthy… More >

  • Open Access


    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 the myosin filament. Here, we… More >

  • Open Access


    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%; and age-stiffening from 35 to… More >

  • Open Access


    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 models. A sensitivity analysis was… More >

  • Open Access


    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


    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 comparing with the other three… More >

  • Open Access


    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 blood pressure on stress, strain,… More >

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