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Biomechanics and Modeling in Mechanobiology

Matthew D Parker, Thiranja P Babarenda Gamage, Amir HajiRassouliha, Andrew J Taberner, Martyn P Nash, Poul M F Nielsen
Many computer vision algorithms have been presented to track surface deformations, but few have provided a direct comparison of measurements with other stereoscopic approaches and physics-based models. We have previously developed a phase-based cross-correlation algorithm to track dense distributions of displacements over three-dimensional surfaces. In the present work, we compare this algorithm with one that uses an independent tracking system, derived from an array of fluorescent microspheres. A smooth bicubic Hermite mesh was fitted to deformations obtained from the phase-based cross-correlation data...
February 18, 2019: Biomechanics and Modeling in Mechanobiology
Morteza Kazempour, Majid Baniassadi, Hamid Shahsavari, Yves Remond, Mostafa Baghani
Researches, in the recent years, reveal the utmost importance of brain tissue assessment regarding its mechanical properties, especially for automatic robotic tools, surgical robots and helmet producing. For this reason, experimental and computational investigation of the brain behavior under different conditions seems crucial. However, experiments do not normally show the distribution of stress and injury in microscopic scale, and due to various factors are costly. Development of micromechanical methods, which could predict the brain behavior more appropriately, could highly be helpful in reducing these costs...
February 14, 2019: Biomechanics and Modeling in Mechanobiology
Markus von Hoegen, Michele Marino, Jörg Schröder, Peter Wriggers
This paper investigates on the relationship between the arrangement of collagen fibers within soft tissues and parameters of constitutive models. Starting from numerical experiments based on biaxial loading conditions, the study addresses both the direct (from structure to mechanics) and the inverse (from mechanics to structure) problems, solved introducing optimization problems for model calibration and regression analysis. A campaign of parametric analyses is conducted in order to consider fibers distributions with different main orientation and angular dispersion...
February 9, 2019: Biomechanics and Modeling in Mechanobiology
Václav Klika, Jonathan P Whiteley, Cameron P Brown, Eamonn A Gaffney
Articular cartilage is a complex, anisotropic, stratified tissue with remarkable resilience and mechanical properties. It has been subject to extensive modelling as a multiphase medium, with many recent studies examining the impact of increasing detail in the representation of this tissue's fine scale structure. However, further investigation of simple models with minimal constitutive relations can nonetheless inform our understanding at the foundations of soft tissue simulation. Here, we focus on the impact of heterogeneity with regard to the volume fractions of solid and fluid within the cartilage...
February 6, 2019: Biomechanics and Modeling in Mechanobiology
Xuanyu Li, Xiaosheng Liu, Xiao Li, Lijian Xu, Xin Chen, Fuyou Liang
The superficial femoral artery (SFA) is a typical atherosclerosis-prone site. We aimed to explore whether the tortuosity of the SFA associates with the occurrence of atherosclerosis and investigate how vascular tortuosity influences the characteristics of blood flow. Ten patients diagnosed with atherosclerotic disease in their SFAs while free of systemic atherosclerosis risk factors were enrolled together with ten atherosclerosis-free patients. The tortuosity of each SFA was quantitatively evaluated by calculating the averaged curvature (AC), maximum curvature (MC) and fraction of high curvature (FC) based on the geometrical model reconstructed from medical images...
January 16, 2019: Biomechanics and Modeling in Mechanobiology
Weiguang Yang, Melody Dong, Marlene Rabinovitch, Frandics P Chan, Alison L Marsden, Jeffrey A Feinstein
Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling resulting in right ventricular (RV) dysfunction and ultimately RV failure. Mechanical stimuli acting on the vessel walls of the full pulmonary tree have not previously been comprehensively characterized. The goal of this study is to characterize wall shear stress (WSS) and strain in pediatric PAH patients at different stages of disease severity using computational patient-specific modeling. Computed tomography, magnetic resonance imaging and right heart catheterization data were collected and assimilated into pulmonary artery (PA) models for patients with and without PAH...
January 12, 2019: Biomechanics and Modeling in Mechanobiology
Rudy Lapeer, Zelimkhan Gerikhanov, Said-Magomed Sadulaev, Vilius Audinis, Roger Rowland, Kenda Crozier, Edward Morris
During physiological or 'natural' childbirth, the fetal head follows a distinct motion pattern-often referred to as the cardinal movements or 'mechanisms' of childbirth-due to the biomechanical interaction between the fetus and maternal pelvic anatomy. The research presented in this paper introduces a virtual reality-based simulation of physiological childbirth. The underpinning science is based on two numerical algorithms including the total Lagrangian explicit dynamics method to calculate soft tissue deformation and the partial Dirichlet-Neumann contact method to calculate the mechanical contact interaction between the fetal head and maternal pelvic anatomy...
January 12, 2019: Biomechanics and Modeling in Mechanobiology
M C P Vila Pouca, J P S Ferreira, D A Oliveira, M P L Parente, M T Mascarenhas, R M Natal Jorge
During vaginal delivery women sustain stretching of their pelvic floor, risking tissue injury and adverse outcomes. Since studies in pregnant women are limited with ethical constraints, computational models have become an interesting alternative to elucidate the pregnancy mechanisms. This research investigates the uterine contractions during foetus expulsion without an imposed trajectory. Such physical process is captured by means of a chemo-mechanical constitutive model, where the uterine contractions are triggered by chemical stimuli...
January 11, 2019: Biomechanics and Modeling in Mechanobiology
Atte S A Eskelinen, Mika E Mononen, Mikko S Venäläinen, Rami K Korhonen, Petri Tanska
Post-traumatic osteoarthritis (PTOA) is a common disease, where the mechanical integrity of articular cartilage is compromised. PTOA can be a result of chondral defects formed due to injurious loading. One of the first changes around defects is proteoglycan depletion. Since there are no methods to restore injured cartilage fully back to its healthy state, preventing the onset and progression of the disease is advisable. However, this is problematic if the disease progression cannot be predicted. Thus, we developed an algorithm to predict proteoglycan loss of injured cartilage by decreasing the fixed charge density (FCD) concentration...
January 10, 2019: Biomechanics and Modeling in Mechanobiology
Amir Shamloo, Mohamadamin Forouzandehmehr
Endothelial inflammation as a prominent precursor to atherosclerosis elicits a distinct pathological surface expression of particular vascular proteins. To exhibit a site-specific behaviour, micro- and nanoparticles, as carriers of therapeutics or imaging agents, can distinguish and use these proteins as targeted docking sites. Here, a computational patient-specific model capturing the exclusive luminal qualities has been developed to study the transport and adsorption of particles decorated with proper antibodies over an atherosclerotic plaque located in the LAD artery of the patient...
January 7, 2019: Biomechanics and Modeling in Mechanobiology
Matthieu Caruel, Philippe Moireau, Dominique Chapelle
We propose a chemical-mechanical model of myosin heads in sarcomeres, within the classical description of rigid sliding filaments. In our case, myosin heads have two mechanical degrees-of-freedom (dofs)-one of which associated with the so-called power stroke-and two possible chemical states, i.e., bound to an actin site or not. Our major motivations are twofold: (1) to derive a multiscale coupled chemical-mechanical model and (2) to thus account-at the macroscopic scale-for mechanical phenomena that are out of reach for classical muscle models...
January 3, 2019: Biomechanics and Modeling in Mechanobiology
Amir Putra Md Saad, Akbar Teguh Prakoso, M A Sulong, Hasan Basri, Dian Agustin Wahjuningrum, Ardiyansyah Syahrom
This study employs a computational approach to analyse the impact of morphological changes on the structural properties of biodegradable porous Mg subjected to a dynamic immersion test for its application as a bone scaffold. Porous Mg was immersed in a dynamic immersion test for 24, 48, and 72 h. Twelve specimens were prepared and scanned using micro-CT and then reconstructed into a 3D model for finite element analysis. The structural properties from the numerical simulation were then compared to the experimental values...
January 3, 2019: Biomechanics and Modeling in Mechanobiology
Tanvir R Faisal, Malek Adouni, Yasin Y Dhaher
The pathogenesis and pathophysiological underpinnings of cartilage degradation are not well understood. Either mechanically or enzymatically mediated degeneration at the fibril level can lead to acute focal injuries that will, overtime, cause significant cartilage degradation. Understanding the relationship between external loading and the basic molecular structure of cartilage requires establishing a connection between the fibril-level defects and its aggregate effect on cartilage. In this work, we provide a multiscale constitutive model of cartilage to elucidate the effect of two plausible fibril degradation mechanisms on the aggregate tissue: tropocollagen crosslink failure (β) and a generalized surface degradation (δ)...
January 2, 2019: Biomechanics and Modeling in Mechanobiology
Sarah D Olson, Mansoor A Haider
Cartilage tissue engineering is commonly initiated by seeding cells in porous materials such as hydrogels or scaffolds. Under optimal conditions, the resulting engineered construct has the potential to fill regions where native cartilage has degraded or eroded. Within a cell-seeded scaffold supplied by nutrients and growth factors, extracellular matrix accumulation should occur concurrently with scaffold degradation. At present, the interplay between cell-mediated synthesis and linking of matrix constituents and the evolving scaffold properties is not well understood...
January 2, 2019: Biomechanics and Modeling in Mechanobiology
Amy M Dagro, K T Ramesh
An increase in arterial pressure within the cerebral vasculature appears to coincide with ischemia and dysfunction of the neurovascular unit in some cases of traumatic brain injury. In this study, we examine a new mechanism of brain tissue damage that results from excessive cerebral arteriole pressurization. We begin by considering the morphological and material properties of normotensive and hypertensive arterioles and present a computational model that captures the interaction of neighboring pressurized arterioles and the surrounding brain tissue...
January 2, 2019: Biomechanics and Modeling in Mechanobiology
P Wu, Q Gao, P-L Hsu
Hemolysis is a major concern in blood-circulating devices, which arises due to hydrodynamic loading on red blood cells from ambient flow environment. Hemolysis estimation models have often been used to aid hemocompatibility design. The preponderance of hemolysis models was formulated on the basis of laminar flows. However, flows in blood-circulating devices are rather complex and can be laminar, transitional or turbulent. It is an extrapolation to apply these models to turbulent flows. For the commonly used power-law models, effective stress has often been represented using Reynolds stresses for estimating hemolysis in turbulent flows...
January 2, 2019: Biomechanics and Modeling in Mechanobiology
Nikola Kuzmic, Thomas Moore, Deepika Devadas, Edmond W K Young
Tumour-induced angiogenesis is a complex biological process that involves growth of new blood vessels within the tumour microenvironment and is an important target for cancer therapies. Significant efforts have been undertaken to develop theoretical models as well as in vitro experimental models to study angiogenesis in a highly controllable and accessible manner. Various mathematical models have been developed to study angiogenesis, but these have mostly been applied to in vivo assays. Recently, microfluidic cell culture systems have emerged as useful and powerful tools for studying cell migration and angiogenesis processes, but thus far, mathematical angiogenesis models have not yet been applied to microfluidic geometries...
January 2, 2019: Biomechanics and Modeling in Mechanobiology
Ling Wang, Yingying Wang, Lei Shi, Peng Liu, Jianfeng Kang, Jiankang He, Yaxiong Liu, Dichen Li
Sheep model is the most favourable choice for animal study for functional evaluation of the cervical fusion prostheses before clinical application; however, significantly large differences between sheep and human existed in terms of morphological characteristics and daily-activity motions. Questions should be raised as whether the differences between the two species have influence on the reliability of sheep model. Finite element models (FEM) of the cervical spinal system were built to characterize the differences between the two species with respect to the range of motion (ROM) and biomechanical behaviour, and experimental cadaver tests on both species were employed for validation purposes...
December 20, 2018: Biomechanics and Modeling in Mechanobiology
P Sanaei, L J Cummings, S L Waters, I M Griffiths
Cell proliferation within a fluid-filled porous tissue-engineering scaffold depends on a sensitive choice of pore geometry and flow rates: regions of high curvature encourage cell proliferation, while a critical flow rate is required to promote growth for certain cell types. When the flow rate is too slow, the nutrient supply is limited; when it is too fast, cells may be damaged by the high fluid shear stress. As a result, determining appropriate tissue-engineering-construct geometries and operating regimes poses a significant challenge that cannot be addressed by experimentation alone...
December 12, 2018: Biomechanics and Modeling in Mechanobiology
Martin R Pfaller, Julia M Hörmann, Martina Weigl, Andreas Nagler, Radomir Chabiniok, Cristóbal Bertoglio, Wolfgang A Wall
The human heart is enclosed in the pericardial cavity. The pericardium consists of a layered thin sac and is separated from the myocardium by a thin film of fluid. It provides a fixture in space and frictionless sliding of the myocardium. The influence of the pericardium is essential for predictive mechanical simulations of the heart. However, there is no consensus on physiologically correct and computationally tractable pericardial boundary conditions. Here, we propose to model the pericardial influence as a parallel spring and dashpot acting in normal direction to the epicardium...
December 10, 2018: Biomechanics and Modeling in Mechanobiology
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