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Biomechanics and Modeling in Mechanobiology

S Jamaleddin Mousavi, Stéphane Avril
It is now a rather common approach to perform patient-specific stress analyses of arterial walls using finite-element models reconstructed from gated medical images. However, this requires to compute for every Gauss point the deformation gradient between the current configuration and a stress-free reference configuration. It is technically difficult to define such a reference configuration, and there is actually no guarantee that a stress-free configuration is physically attainable due to the presence of internal stresses in unloaded soft tissues...
May 23, 2017: Biomechanics and Modeling in Mechanobiology
Shakti N Menon, Cameron L Hall, Scott W McCue, D L Sean McElwain
The mechanical behaviour of solid biological tissues has long been described using models based on classical continuum mechanics. However, the classical continuum theories of elasticity and viscoelasticity cannot easily capture the continual remodelling and associated structural changes in biological tissues. Furthermore, models drawn from plasticity theory are difficult to apply and interpret in this context, where there is no equivalent of a yield stress or flow rule. In this work, we describe a novel one-dimensional mathematical model of tissue remodelling based on the multiplicative decomposition of the deformation gradient...
May 18, 2017: Biomechanics and Modeling in Mechanobiology
Young Kwan Kim, Yoshitaka Kameo, Sakae Tanaka, Taiji Adachi
To understand Wolff's law, bone adaptation by remodeling at the cellular and tissue levels has been discussed extensively through experimental and simulation studies. For the clinical application of a bone remodeling simulation, it is significant to establish a macroscopic model that incorporates clarified microscopic mechanisms. In this study, we proposed novel macroscopic models based on the microscopic mechanism of osteocytic mechanosensing, in which the flow of fluid in the lacuno-canalicular porosity generated by fluid pressure gradients plays an important role, and theoretically evaluated the proposed models, taking biological rationales of bone adaptation into account...
May 18, 2017: Biomechanics and Modeling in Mechanobiology
M Alipour, K Mithraratne, J Fernandez
The NZ white rabbit is the animal of choice for much experimental work due to its muscular frame and similar response to human diseases, and is one of the few mammals that have had their genome sequenced. However, continuum-level computational models of rabbit muscle detailing fibre architecture are limited in the literature, especially the triceps surae complex (gastrocnemius, plantaris and soleus), which has similar biomechanics and translatable findings to the human. This study presents a geometrical model of the rabbit triceps surae informed with diffusion-weighted imaging (DWI)-based fibres...
May 18, 2017: Biomechanics and Modeling in Mechanobiology
Francesc Levrero-Florencio, Krishnagoud Manda, Lee Margetts, Pankaj Pankaj
Being able to predict bone fracture or implant stability needs a proper constitutive model of trabecular bone at the macroscale in multiaxial, non-monotonic loading modes. Its macroscopic damage behaviour has been investigated experimentally in the past, mostly with the restriction of uniaxial cyclic loading experiments for different samples, which does not allow for the investigation of several load cases in the same sample as damage in one direction may affect the behaviour in other directions. Homogenised finite element models of whole bones have the potential to assess complicated scenarios and thus improve clinical predictions...
May 12, 2017: Biomechanics and Modeling in Mechanobiology
Wei Zhao, Yunliang Cai, Zhigang Li, Songbai Ji
Reliable prediction and diagnosis of concussion is important for its effective clinical management. Previous model-based studies largely employ peak responses from a single element in a pre-selected anatomical region of interest (ROI) and utilize a single training dataset for injury prediction. A more systematic and rigorous approach is necessary to scrutinize the entire white matter (WM) ROIs as well as ROI-constrained neural tracts. To this end, we evaluated injury prediction performances of the 50 deep WM regions using predictor variables based on strains obtained from simulating the 58 reconstructed American National Football League head impacts...
May 12, 2017: Biomechanics and Modeling in Mechanobiology
Julien Sigüenza, Simon Mendez, Franck Nicoud
Stretching red blood cells using optical tweezers is a way to characterize the mechanical properties of their membrane by measuring the size of the cell in the direction of the stretching (axial diameter) and perpendicularly (transverse diameter). Recently, such data have been used in numerous publications to validate solvers dedicated to the computation of red blood cell dynamics under flow. In the present study, different mechanical models are used to simulate the stretching of red blood cells by optical tweezers...
May 3, 2017: Biomechanics and Modeling in Mechanobiology
Tijana Djukic, Nenad Filipovic
Balance is achieved and maintained by a balance system called a labyrinth that is composed of three semicircular canals and the otolith organs that sense linear gravity and acceleration. Within each semicircular canal, there is a gelatinous structure called the cupula, which is deformed under the influence of the surrounding endolymph. One of the balance disorders is benign paroxysmal positional vertigo, and one of the pathological conditions that have been identified as possible causes of this syndrome is canalithiasis-disturbance of the endolymph flow and cupular displacement caused by the free-moving otoconia particles within the lumen of the canal...
May 3, 2017: Biomechanics and Modeling in Mechanobiology
Na Yin, Hongwei Yang, Wei Yao, Guanghong Ding
Acupoints (Xuewei) are the focus of acupuncture on the body in traditional Chinese medicine treatment. Mast and nerve cells share a perivascular location and are abundantly found at these acupoints. Both environmental factors and medical treatments (chemical and physical stimuli) can stimulate local mast cells (MCs) to degranulate and thus release histamine which then activates the nearby nerves and therefore contributes to a signal transmission from the peripheral to the central nervous system. In this paper, a mathematical model is constructed to describe the signaling pathways that originate from the cells located at an acupoint...
April 29, 2017: Biomechanics and Modeling in Mechanobiology
E Azizi, A R Deslauriers, N C Holt, C E Eaton
The collagenous extracellular matrix (ECM) of skeletal muscle functions to transmit force, protect sensitive structures, and generate passive tension to resist stretch. The mechanical properties of the ECM change with age, atrophy, and neuromuscular pathologies, resulting in an increase in the relative amount of collagen and an increase in stiffness. Although numerous studies have focused on the effect of muscle fibrosis on passive muscle stiffness, few have examined how these structural changes may compromise contractile performance...
April 21, 2017: Biomechanics and Modeling in Mechanobiology
Chung-Hao Lee, Will Zhang, Kristen Feaver, Robert C Gorman, Joseph H Gorman, Michael S Sacks
There continues to be a critical need for developing data-informed computational modeling techniques that enable systematic evaluations of mitral valve (MV) function. This is important for a better understanding of MV organ-level biomechanical performance, in vivo functional tissue stresses, and the biosynthetic responses of MV interstitial cells (MVICs) in the normal, pathophysiological, and surgically repaired states. In the present study, we utilized extant ovine MV population-averaged 3D fiducial marker data to quantify the MV anterior leaflet (MVAL) deformations in various kinematic states...
April 20, 2017: Biomechanics and Modeling in Mechanobiology
Masoud Ramezanzadehkoldeh, Bjørn Skallerud
Nanoindentation test results in the axial direction of mouse femurs were the basis for the current study. Although the majority of the nanoindentation curves showed a reasonable consistency, some curves showed a significantly softer response. Detailed investigation, using focused ion beam-scanning electron microscopy, provided that the softer response is due to subsurface cavities such as lacunae. Finite element models were developed to simulate the nanoindentation of mice femur cortical bone samples with and without the incorporation of a single lacuna underneath the bone surface...
April 19, 2017: Biomechanics and Modeling in Mechanobiology
Donnacha J McGrath, Anja Lena Thiebes, Christian G Cornelissen, Mary B O'Shea, Barry O'Brien, Stefan Jockenhoevel, Mark Bruzzi, Peter E McHugh
Tracheobronchial stents are most commonly used to restore patency to airways stenosed by tumour growth. Currently all tracheobronchial stents are associated with complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. The present work develops a computational framework to evaluate tracheobronchial stent designs in vivo. Pressurised computed tomography is used to create a biomechanical lung model which takes into account the in vivo stress state, global lung deformation and local loading from pressure variation...
April 19, 2017: Biomechanics and Modeling in Mechanobiology
Farshad Roohbakhshan, Roger A Sauer
This paper presents three different constitutive approaches to model thin rotation-free shells based on the Kirchhoff-Love hypothesis. One approach is based on numerical integration through the shell thickness while the other two approaches do not need any numerical integration and so they are computationally more efficient. The formulation is designed for large deformations and allows for geometrical and material nonlinearities, which makes it very suitable for the modeling of soft tissues. Furthermore, six different isotropic and anisotropic material models, which are commonly used to model soft biological materials, are examined for the three proposed constitutive approaches...
April 12, 2017: Biomechanics and Modeling in Mechanobiology
A R B Boyd, S Moore, J E Sader, P V S Lee
Simple columnar epithelia are formed by individual epithelial cells connecting together to form single cell high sheets. They are a main component of many important body tissues and are heavily involved in both normal and cancerous cell activities. Prior experimental observations have identified a series of contractile fibres around the circumference of a cross section located in the upper (apical) region of each cell. While other potential mechanisms have been identified in both the experimental and theoretical literature, these circumferential fibres are considered to be the most likely mechanism controlling movement of this cross section...
April 7, 2017: Biomechanics and Modeling in Mechanobiology
Liang Liang, Minliang Liu, Caitlin Martin, John A Elefteriades, Wei Sun
Geometric features of the aorta are linked to patient risk of rupture in the clinical decision to electively repair an ascending aortic aneurysm (AsAA). Previous approaches have focused on relationship between intuitive geometric features (e.g., diameter and curvature) and wall stress. This work investigates the feasibility of a machine learning approach to establish the linkages between shape features and FEA-predicted AsAA rupture risk, and it may serve as a faster surrogate for FEA associated with long simulation time and numerical convergence issues...
April 6, 2017: Biomechanics and Modeling in Mechanobiology
Claudio Vergari, Daniel Chan, Andrew Clarke, Jessica C Mansfield, Judith R Meakin, Peter C Winlove
The complex structure of the annulus fibrosus is strongly related to its mechanical properties. Recent work showed that it is possible to observe the relative movement of fibre bundles in loaded cow tail annulus; the aim of this work was to describe and quantify annulus fibrosus micromechanics in degenerated human disc, and compare it with cow tail annulus, an animal model often used in the literature. Second harmonic generation was used to image the collagen matrix in twenty strips of annulus fibrosus harvested from intervertebral disc of seven patients undergoing surgery...
April 4, 2017: Biomechanics and Modeling in Mechanobiology
Lucas Colabella, Adrián P Cisilino, Guillaume Häiat, Piotr Kowalczyk
Bone tissue mechanical properties and trabecular microarchitecture are the main factors that determine the biomechanical properties of cancellous bone. Artificial cancellous microstructures, typically described by a reduced number of geometrical parameters, can be designed to obtain a mechanical behavior mimicking that of natural bone. In this work, we assess the ability of the parameterized microstructure introduced by Kowalczyk (Comput Methods Biomech Biomed Eng 9:135-147, 2006. doi: 10.1080/10255840600751473 ) to mimic the elastic response of cancellous bone...
April 3, 2017: Biomechanics and Modeling in Mechanobiology
Vivek Vasudevan, Adriel Jia Jun Low, Sarayu Parimal Annamalai, Smita Sampath, Kian Keong Poh, Teresa Totman, Muhammad Mazlan, Grace Croft, A Mark Richards, Dominique P V de Kleijn, Chih-Liang Chin, Choon Hwai Yap
Cardiovascular disease is a leading cause of death worldwide, where myocardial infarction (MI) is a major category. After infarction, the heart has difficulty providing sufficient energy for circulation, and thus, understanding the heart's energy efficiency is important. We induced MI in a porcine animal model via circumflex ligation and acquired multiple-slice cine magnetic resonance (MR) images in a longitudinal manner-before infarction, and 1 week (acute) and 4 weeks (chronic) after infarction. Computational fluid dynamic simulations were performed based on MR images to obtain detailed fluid dynamics and energy dynamics of the left ventricles...
March 31, 2017: Biomechanics and Modeling in Mechanobiology
Vahhab Zarei, Chao J Liu, Amy A Claeson, Taner Akkin, Victor H Barocas
The lumbar facet capsular ligament (FCL) primarily consists of aligned type I collagen fibers that are mainly oriented across the joint. The aim of this study was to characterize and incorporate in-plane local fiber structure into a multiscale finite element model to predict the mechanical response of the FCL during in vitro mechanical tests, accounting for the heterogeneity in different scales. Characterization was accomplished by using entire-domain polarization-sensitive optical coherence tomography to measure the fiber structure of cadaveric lumbar FCLs ([Formula: see text])...
March 30, 2017: Biomechanics and Modeling in Mechanobiology
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