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Biomechanics and Modeling in Mechanobiology

Max A Hammond, Joseph M Wallace, Matthew R Allen, Thomas Siegmund
Trabecular bone is composed of organized mineralized collagen fibrils, which results in heterogeneous and anisotropic mechanical properties at the tissue level. Recently, biomechanical models computing stresses and strains in trabecular bone have indicated a significant effect of tissue heterogeneity on predicted stresses and strains. However, the effect of the tissue-level mechanical anisotropy on the trabecular bone biomechanical response is unknown. Here, a computational method was established to automatically impose physiologically relevant orientation inherent in trabecular bone tissue on a trabecular bone microscale finite element model...
November 14, 2017: Biomechanics and Modeling in Mechanobiology
A M de Villiers, A T McBride, B D Reddy, T Franz, B S Spottiswoode
The flow rate inside arteriovenous fistulas is many times higher than physiological flow and is accompanied by high wall shear stress resulting in low patency rates. A fluid-structure interaction finite element model is developed to analyse the blood flow and vessel mechanics to elucidate the mechanisms that can lead to failure. The simulations are validated against flow measurements obtained from magnetic resonance imaging data.
November 14, 2017: Biomechanics and Modeling in Mechanobiology
Mohammad Akrami, Zhihui Qian, Zhemin Zou, David Howard, Chris J Nester, Lei Ren
The objective of this study was to develop and validate a subject-specific framework for modelling the human foot. This was achieved by integrating medical image-based finite element modelling, individualised multi-body musculoskeletal modelling and 3D gait measurements. A 3D ankle-foot finite element model comprising all major foot structures was constructed based on MRI of one individual. A multi-body musculoskeletal model and 3D gait measurements for the same subject were used to define loading and boundary conditions...
November 14, 2017: Biomechanics and Modeling in Mechanobiology
Shukei Sugita, Takeo Matsumoto
Although elucidation of the mechanism of aortic aneurysm rupture is important, the characteristics of crack initiation and propagation sites remain unknown. To determine the microscopic properties of these sites, the characteristics of local strains and constituents at crack initiation and propagation sites were investigated during biaxial stretching of porcine thoracic aortas (PTAs). PTAs were sliced into approximately 50-[Formula: see text]-thick sections, and the center of the sections was made especially thin using our previously developed technique...
November 13, 2017: Biomechanics and Modeling in Mechanobiology
A P G Castro, D Lacroix
Scaffolds are used in diverse tissue engineering applications as hosts for cell proliferation and extracellular matrix formation. One of the most used tissue engineering materials is collagen, which is well known to be a natural biomaterial, also frequently used as cell substrate, given its natural abundance and intrinsic biocompatibility. This study aims to evaluate how the macroscopic biomechanical stimuli applied on a construct made of polycaprolactone scaffold embedded in a collagen substrate translate into microscopic stimuli at the cell level...
November 11, 2017: Biomechanics and Modeling in Mechanobiology
A Fernández-Tena, A C Marcos, R Agujetas, C Ferrera
A method is proposed to improve the quality of the three-dimensional airway geometric models using a commercial software, checking the number of elements, meshing time, and aspect ratio and skewness parameters. The use of real and virtual topologies combined with patch-conforming and patch-independent meshing algorithms results in four different models being the best solution the combination of virtual topology and patch-independent algorithm, due to an excellent aspect ratio and skewness of the elements, and minimum meshing time...
November 5, 2017: Biomechanics and Modeling in Mechanobiology
Ana Vercher-Martínez, Eugenio Giner, Ricardo Belda, Abdelmalik Aigoun, F Javier Fuenmayor
In this work, explicit expressions to estimate all the transversely isotropic elastic constants of lamellar bone as a function of the volumetric bone mineral density (BMD) are provided. The methodology presented is based on the direct homogenization procedure using the finite element method, the continuum approach based on the Hill bounds, the least-square method and the mean field technique. Firstly, a detailed description of the volumetric content of the different components of bone is provided. The parameters defined in this step are related to the volumetric BMD considering that bone mineralization process occurs at the smallest scale length of the bone tissue...
November 5, 2017: Biomechanics and Modeling in Mechanobiology
Liqiang Lin, Xiaowei Zeng
During collective cell migration, the intercellular forces will significantly affect the collective migratory behaviors. However, the measurement of mechanical stresses exerted at cell-cell junctions is very challenging. A recent experimental observation indicated that the intercellular adhesion sites within a migrating monolayer are subjected to both normal stress exerted perpendicular to cell-cell junction surface and shear stress exerted tangent to cell-cell junction surface. In this study, an interfacial interaction model was proposed to model the intercellular interactions for the first time...
November 1, 2017: Biomechanics and Modeling in Mechanobiology
Adrian Fessel, Hans-Günther Döbereiner
Thin samples adherent to a rigid substrate are considerably less compliant to indentation when compared to specimens that are not geometrically confined. Analytical corrections to this so-called substrate effect exist for various types of indenters but are not applicable when large deformations are possible, as is the case in biological materials. To overcome this limitation, we construct a nonlinear scaling model characterized by one single exponent, which we explore employing a parametric finite element analysis...
November 1, 2017: Biomechanics and Modeling in Mechanobiology
Fangzhou Cheng, Lori A Birder, F Aura Kullmann, Jack Hornsby, Paul N Watton, Simon Watkins, Mark Thompson, Anne M Robertson
In this work, we re-evaluated long-standing conjectures as to the source of the exceptionally large compliance of the bladder wall. Whereas these conjectures were based on indirect measures of loading mechanisms, in this work we take advantage of advances in bioimaging to directly assess collagen fibers and wall architecture during biaxial loading. A custom biaxial mechanical testing system compatible with multiphoton microscopy was used to directly measure the layer-dependent collagen fiber recruitment in bladder tissue from 9 male Fischer rats (4 adult and 5 aged)...
October 16, 2017: Biomechanics and Modeling in Mechanobiology
Xiaoyan Zhang, Daeseung Kim, Shunyao Shen, Peng Yuan, Siting Liu, Zhen Tang, Guangming Zhang, Xiaobo Zhou, Jaime Gateno, Michael A K Liebschner, James J Xia
Accurate surgical planning and prediction of craniomaxillofacial surgery outcome requires simulation of soft tissue changes following osteotomy. This can only be achieved by using an anatomically detailed facial soft tissue model. The current state-of-the-art of model generation is not appropriate to clinical applications due to the time-intensive nature of manual segmentation and volumetric mesh generation. The conventional patient-specific finite element (FE) mesh generation methods are to deform a template FE mesh to match the shape of a patient based on registration...
October 12, 2017: Biomechanics and Modeling in Mechanobiology
Jiao Chen, Daphne Weihs, Fred J Vermolen
Cell migration, known as an orchestrated movement of cells, is crucially important for wound healing, tumor growth, immune response as well as other biomedical processes. This paper presents a cell-based model to describe cell migration in non-isotropic fibrin networks around pancreatic tumor islets. This migration is determined by the mechanical strain energy density as well as cytokines-driven chemotaxis. Cell displacement is modeled by solving a large system of ordinary stochastic differential equations where the stochastic parts result from random walk...
October 9, 2017: Biomechanics and Modeling in Mechanobiology
Amir H Khalighi, Andrew Drach, Robert C Gorman, Joseph H Gorman, Michael S Sacks
An essential element of cardiac function, the mitral valve (MV) ensures proper directional blood flow between the left heart chambers. Over the past two decades, computational simulations have made marked advancements toward providing powerful predictive tools to better understand valvular function and improve treatments for MV disease. However, challenges remain in the development of robust means for the quantification and representation of MV leaflet geometry. In this study, we present a novel modeling pipeline to quantitatively characterize and represent MV leaflet surface geometry...
October 5, 2017: Biomechanics and Modeling in Mechanobiology
Si Li, Chengyuan Wang, Perumal Nithiarasu
Quasi-one-dimensional microtubules (MTs) in cells enjoy high axial rigidity but large transverse flexibility due to the inter-protofilament (PF) sliding. This study aims to explore the structure-property relation for MTs and examine the relevance of the beam theories to their unique features. A molecular structural mechanics (MSM) model was used to identify the origin of the inter-PF sliding and its role in bending and vibration of MTs. The beam models were then fitted to the MSM to reveal how they cope with the distinct mechanical responses induced by the inter-PF sliding...
October 3, 2017: Biomechanics and Modeling in Mechanobiology
Mathias Peirlinck, Nic Debusschere, Francesco Iannaccone, Peter D Siersema, Benedict Verhegghe, Patrick Segers, Matthieu De Beule
In the original publication of the article, Tables 2 and 3 were published with error. The correct tables are provided below (Tables 2, 3). The original version of the article has also been corrected.
September 20, 2017: Biomechanics and Modeling in Mechanobiology
Hossein Mohammadi, Raymond Cartier, Rosaire Mongrain
Cardiovascular diseases are still the leading causes of death in the developed world. The decline in the mortality associated with circulatory system diseases is accredited to development of new diagnostic and prognostic tools. It is well known that there is an inter relationship between the aortic valve impairment and pathologies of the aorta and coronary vessels. However, due to the limitations of the current tools, the possible link is not fully elucidated. Following our previous model of the aortic root including the coronaries, in this study, we have further developed the global aspect of the model by incorporating the anatomical structure of the thoracic aorta...
September 19, 2017: Biomechanics and Modeling in Mechanobiology
Shaily Wald, Alex Liberzon, Idit Avrahami
During diastole, coronary perfusion depends on the pressure drop between the myocardial tissue and the coronary origin located at the aortic root. This pressure difference is influenced by the flow field near the closing valve leaflets. Clinical evidence is conclusive that patients with severe aortic stenosis (AS) suffer from diastolic dysfunction during hyperemia, but show increased coronary blood flow (CBF) during rest. Transcatheter aortic valve implantation (TAVI) was shown to decrease rest CBF along with its main purpose of improving the aortic flow and reducing the risk of heart failure...
September 19, 2017: Biomechanics and Modeling in Mechanobiology
E Carrera, D Guarnera, A Pagani
Static and modal responses of representative biomechanical structures are investigated in this paper by employing higher-order theories of structures and finite element approximations. Refined models are implemented in the domain of the Carrera unified formulation (CUF), according to which low- to high-order kinematics can be postulated as arbitrary and, eventually, hierarchical expansions of the generalized displacement unknowns. By using CUF along with the principle of virtual work, the governing equations are expressed in terms of fundamental nuclei of finite element arrays...
September 13, 2017: Biomechanics and Modeling in Mechanobiology
Roch Molléro, Xavier Pennec, Hervé Delingette, Alan Garny, Nicholas Ayache, Maxime Sermesant
Personalised computational models of the heart are of increasing interest for clinical applications due to their discriminative and predictive abilities. However, the simulation of a single heartbeat with a 3D cardiac electromechanical model can be long and computationally expensive, which makes some practical applications, such as the estimation of model parameters from clinical data (the personalisation), very slow. Here we introduce an original multifidelity approach between a 3D cardiac model and a simplified "0D" version of this model, which enables to get reliable (and extremely fast) approximations of the global behaviour of the 3D model using 0D simulations...
September 11, 2017: Biomechanics and Modeling in Mechanobiology
Ziying Zhang, Jun Du, Zhengying Wei, Zhen Wang, Minghui Li
Cellular adhesion plays a critical role in biological systems and biomedical applications. Cell deformation and biophysical properties of adhesion molecules are of significance for the adhesion behavior. In the present work, dynamic adhesion of a deformable capsule to a planar substrate, in a linear shear flow, is numerically simulated to investigate the combined influence of membrane deformability (quantified by the capillary number) and bond formation/dissociation rates on the adhesion behavior. The computational model is based on the immersed boundary-lattice Boltzmann method for the capsule-fluid interaction and a probabilistic adhesion model for the capsule-substrate interaction...
September 6, 2017: Biomechanics and Modeling in Mechanobiology
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