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Biomechanics and Modeling in Mechanobiology

You Chang, Namkeun Kim, Stefan Stenfelt
Bone conduction (BC) sound is the perception of sound transmitted in the skull bones and surrounding tissues. To better understand BC sound perception and the interaction with surrounding tissues, the power transmission of BC sound is investigated in a three-dimensional finite-element model of a whole human head. BC sound transmission was simulated in the FE model and the power dissipation as well as the power flow following a mechanical vibration at the mastoid process behind the ear was analyzed. The results of the simulations show that the skull bone (comprises the cortical bone and diploë) has the highest BC power flow and thereby provide most power transmission for BC sound...
July 17, 2018: Biomechanics and Modeling in Mechanobiology
Christian Contarino, Eleuterio F Toro
We propose a one-dimensional model for collecting lymphatics coupled with a novel Electro-Fluid-Mechanical Contraction (EFMC) model for dynamical contractions, based on a modified FitzHugh-Nagumo model for action potentials. The one-dimensional model for a deformable lymphatic vessel is a nonlinear system of hyperbolic Partial Differential Equations (PDEs). The EFMC model combines the electrical activity of lymphangions (action potentials) with fluid-mechanical feedback (circumferential stretch of the lymphatic wall and wall shear stress) and lymphatic vessel wall contractions...
July 14, 2018: Biomechanics and Modeling in Mechanobiology
Francesco Regazzoni, Luca Dedè, Alfio Quarteroni
We propose a reduced ODE model for the mechanical activation of cardiac myofilaments, which is based on explicit spatial representation of nearest-neighbour interactions. Our model is derived from the cooperative Markov Chain model of Washio et al. (Cell Mol Bioeng 5(1):113-126, 2012), under the assumption of conditional independence of specific sets of events. This physically motivated assumption allows to drastically reduce the number of degrees of freedom, thus resulting in a significantly large computational saving...
July 12, 2018: Biomechanics and Modeling in Mechanobiology
William J Richardson, Brian Kegerreis, Stavros Thomopoulos, Jeffrey W Holmes
Tendon mechanical function after injury and healing is largely determined by its underlying collagen structure, which in turn is dependent on the degree of mechanical loading experienced during healing. Experimental studies have shown seemingly conflicting outcomes: although collagen content steadily increases with increasing loads, collagen alignment peaks at an intermediate load. Herein, we explored potential collagen remodeling mechanisms that could give rise to this structural divergence in response to strain...
July 12, 2018: Biomechanics and Modeling in Mechanobiology
J Alsayednoor, L Metcalf, J Rochester, E Dall'Ara, E McCloskey, D Lacroix
The calcaneus bone is formed of extensive trabecular bone and is therefore well suited to be used as an example of loaded bone to establish the ability of combining microfinite element (microFE) technique with high-resolution peripheral quantitative computed tomography (HR-pQCT) in determining its mechanical properties. HR-pQCT is increasingly used as a tool for in vivo bone clinical research, but its use has been limited to the distal radius and tibia. The goal of this study was to determine the applicability of HR-pQCT-derived microFE models of the calcaneus trabecular bone with 82 μm voxel size with reference to higher-resolution microCT-based models taken as gold standard...
July 10, 2018: Biomechanics and Modeling in Mechanobiology
S S Shishvan, A Vigliotti, V S Deshpande
Cells are quintessential examples of out-of-equilibrium systems, but they maintain a homeostatic state over a timescale of hours to days. As a consequence, the statistics of all observables is remarkably consistent. Here, we develop a statistical mechanics framework for living cells by including the homeostatic constraint that exists over the interphase period of the cell cycle. The consequence is the introduction of the concept of a homeostatic ensemble and an associated homeostatic temperature, along with a formalism for the (dynamic) homeostatic equilibrium that intervenes to allow living cells to evade thermodynamic decay...
July 10, 2018: Biomechanics and Modeling in Mechanobiology
Pengcheng Xu, Xin Liu, Heye Zhang, Dhanjoo Ghista, Dong Zhang, Changzheng Shi, Wenhua Huang
Computational fluid dynamics (CFD) is an increasingly used method for investigation of hemodynamic parameters and their alterations under pathological conditions, which are important indicators for diagnosis of cardiovascular disease. In hemodynamic simulation models, the employment of appropriate boundary conditions (BCs) determines the computational accuracy of the CFD simulation in comparison with pressure and velocity measurements. In this study, we have first assessed the influence of inlet boundary conditions on hemodynamic CFD simulations...
July 7, 2018: Biomechanics and Modeling in Mechanobiology
Shiliang Feng, Lüwen Zhou, Yan Zhang, Shouqin Lü, Mian Long
Directional neutrophil migration during human immune responses is a highly coordinated process regulated by both biochemical and biomechanical environments. In this paper, we developed an integrative mathematical model of neutrophil migration using a lattice Boltzmann-particle method built in-house to solve the moving boundary problem with spatiotemporal regulation of biochemical components. The mechanical features of the cell cortex are modeled by a series of spring-connected nodes representing discrete cell-substrate adhesive sites...
July 2, 2018: Biomechanics and Modeling in Mechanobiology
Michael R Hill, Christopher J Philp, Charlotte K Billington, Amanda L Tatler, Simon R Johnson, Reuben D O'Dea, Bindi S Brook
Inflammation, airway hyper-responsiveness and airway remodelling are well-established hallmarks of asthma, but their inter-relationships remain elusive. In order to obtain a better understanding of their inter-dependence, we develop a mechanochemical morphoelastic model of the airway wall accounting for local volume changes in airway smooth muscle (ASM) and extracellular matrix in response to transient inflammatory or contractile agonist challenges. We use constrained mixture theory, together with a multiplicative decomposition of growth from the elastic deformation, to model the airway wall as a nonlinear fibre-reinforced elastic cylinder...
July 2, 2018: Biomechanics and Modeling in Mechanobiology
Seifollah Gholampour, Amin Jalali
The objective of this study is to compare the thermal stress changes in the tooth microstructures and the hydrodynamic changes of the dental fluid under hot and cold stimuli. The dimension of the microstructures of eleven cats' teeth was measured by scanning electron microscopy, and the changes in thermal stress during cold and hot stimulation were calculated by 3D fluid-structure interaction modeling. Evaluation of results, following data validation, indicated that the maximum velocities in cold and hot stimuli were - 410...
June 28, 2018: Biomechanics and Modeling in Mechanobiology
Heiko Topol, Kun Gou, Hasan Demirkoparan, Thomas J Pence
A continuum mechanics constitutive model is presented for the interaction between swelling and collagen remodeling in biological soft tissue. The model is inherently two-way: swelling stretches the collagen fibers which affects their rate of degradation-the remodeled fibrous microarchitecture provides selective directional stiffening that causes the swollen tissue to expand more in the unreinforced directions. The constitutive model specifically treats stretch-stabilization wherein the rate of enzymatic-induced degradation of collagen is a decreasing function of fiber stretch...
June 21, 2018: Biomechanics and Modeling in Mechanobiology
Benjamin Owen, Nicholas Bojdo, Andrey Jivkov, Bernard Keavney, Alistair Revell
Computational modelling of the cardiovascular system offers much promise, but represents a truly interdisciplinary challenge, requiring knowledge of physiology, mechanics of materials, fluid dynamics and biochemistry. This paper aims to provide a summary of the recent advances in cardiovascular structural modelling, including the numerical methods, main constitutive models and modelling procedures developed to represent cardiovascular structures and pathologies across a broad range of length and timescales; serving as an accessible point of reference to newcomers to the field...
June 18, 2018: Biomechanics and Modeling in Mechanobiology
C D Bertram, C Macaskill, M J Davis, J E Moore
The paper describes the extension of a previously developed model of pressure-dependent contraction rate to the case of multiple lymphangions. Mechanical factors are key modulators of active lymphatic pumping. As part of the evolution of our lumped-parameter model to match experimental findings, we have designed an algorithm whereby the time until the next contraction depends on lymphangion transmural pressure in the contraction just completed. The functional dependence of frequency on pressure is quantitatively matched to isobaric contraction experiments on isolated lymphatic segments...
June 8, 2018: Biomechanics and Modeling in Mechanobiology
Marcos Latorre, Jay D Humphrey
Uncontrolled hypertension is a primary risk factor for diverse cardiovascular diseases and thus remains responsible for significant morbidity and mortality. Hypertension leads to marked changes in the composition, structure, properties, and function of central arteries; hence, there has long been interest in quantifying the associated wall mechanics. Indeed, over the past 20 years there has been increasing interest in formulating mathematical models of the evolving geometry and biomechanical behavior of central arteries that occur during hypertension...
June 7, 2018: Biomechanics and Modeling in Mechanobiology
Paul F Egan, Kristina A Shea, Stephen J Ferguson
Experiments have demonstrated biological tissues grow by mechanically sensing their localized curvature, therefore making geometry a key consideration for tissue scaffold design. We developed a simulation approach for modeling tissue growth on beam-based geometries of repeating unit cells, with four lattice topologies considered. In simulations, tissue was seeded on surfaces with new tissue growing in empty voxels with positive curvature. Growth was fastest on topologies with more beams per unit cell when unit cell volume/porosity was fixed, but fastest for topologies with fewer beams per unit cell when beam width/porosity was fixed...
June 6, 2018: Biomechanics and Modeling in Mechanobiology
Marzieh Ovesy, Benjamin Voumard, Philippe Zysset
Stability of an implant is defined by its ability to undergo physiological loading-unloading cycles without showing excessive tissue damage and micromotions at the interface. Distinction is usually made between the immediate primary stability and the long-term, secondary stability resulting from the biological healing process. The aim of this research is to numerically investigate the effect of initial implantation press-fit, bone yielding, densification and friction at the interface on the primary stability of a simple bone-implant system subjected to loading-unloading cycles...
June 1, 2018: Biomechanics and Modeling in Mechanobiology
Hua Wang, Christopher B Rodell, Xiaoyan Zhang, Neville N Dusaj, Joseph H Gorman, James J Pilla, Benjamin M Jackson, Jason A Burdick, Robert C Gorman, Jonathan F Wenk
Injectable hydrogels are a potential therapy for mitigating adverse left ventricular (LV) remodeling after myocardial infarction (MI). Previous studies using magnetic resonance imaging (MRI) have shown that hydrogel treatment improves systolic strain in the borderzone (BZ) region surrounding the infarct. However, the corresponding contractile properties of the BZ myocardium are still unknown. The goal of the current study was to quantify the in vivo contractile properties of the BZ myocardium post-MI in an ovine model treated with an injectable hydrogel...
May 31, 2018: Biomechanics and Modeling in Mechanobiology
Mohd Almie Alias, Pascal R Buenzli
The geometric control of bone tissue growth plays a significant role in bone remodelling, age-related bone loss, and tissue engineering. However, how exactly geometry influences the behaviour of bone-forming cells remains elusive. Geometry modulates cell populations collectively through the evolving space available to the cells, but it may also modulate the individual behaviours of cells. To factor out the collective influence of geometry and gain access to the geometric regulation of individual cell behaviours, we develop a mathematical model of the infilling of cortical bone pores and use it with available experimental data on cortical infilling rates...
May 30, 2018: Biomechanics and Modeling in Mechanobiology
Jiao Chen, Daphne Weihs, Marcel Van Dijk, Fred J Vermolen
Cell migration plays an essential role in cancer metastasis. In cancer invasion through confined spaces, cells must undergo extensive deformation, which is a capability related to their metastatic potentials. Here, we simulate the deformation of the cell and nucleus during invasion through a dense, physiological microenvironment by developing a phenomenological computational model. In our work, cells are attracted by a generic emitting source (e.g., a chemokine or stiffness signal), which is treated by using Green's Fundamental solutions...
May 29, 2018: Biomechanics and Modeling in Mechanobiology
Ahmet Demirtas, Ani Ural
The recent studies have shown that long-term bisphosphonate use may result in a number of mechanical alterations in the bone tissue including a reduction in compositional heterogeneity and an increase in microcrack density. There are limited number of experimental and computational studies in the literature that evaluated how these modifications affect crack initiation and propagation in cortical bone. Therefore, in this study, the entire crack growth process including initiation and propagation was simulated at the microscale by using the cohesive extended finite element method...
May 28, 2018: Biomechanics and Modeling in Mechanobiology
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