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Biomechanics and Modeling in Mechanobiology

Tho N H T Tran, Lawrence H Le, Mauricio D Sacchi, Vu-Hieu Nguyen
The fundamental ultrasonic guided modes are consistently observed in long bones ex vivo and in vivo. However, the responses of ultrasonic guided waves to the changes of cortical thickness, cortical elastic parameters, and thickness of the overlying soft tissues are not comprehensively understood. This paper systematically presents a sensitivity analysis of leaky Lamb modes to the geometry and material characteristics of layered bone model by means of semi-analytical finite element modeling. The stratified bone model is consisted of a transversely isotropic cortex with an overlying soft tissue and underlying marrow...
May 18, 2018: Biomechanics and Modeling in Mechanobiology
M A Bilton, A Thambyah, R J Clarke
The remarkable compressive strength of articular cartilage arises from the mechanical interactions between the tension-resisting collagen fibrils and swelling proteoglycan proteins within the tissue. These interactions are facilitated by a significant level of interconnectivity between neighbouring collagen fibrils within the extracellular matrix. A reduction in interconnectivity is suspected to occur during the early stages of osteoarthritic degeneration. However, the relative contribution of these interconnections towards the bulk mechanical properties of articular cartilage has remained an open question...
May 18, 2018: Biomechanics and Modeling in Mechanobiology
Gabriel Balaban, Henrik Finsberg, Simon Funke, Trine F Håland, Einar Hopp, Joakim Sundnes, Samuel Wall, Marie E Rognes
In myocardial infarction, muscle tissue of the heart is damaged as a result of ceased or severely impaired blood flow. Survivors have an increased risk of further complications, possibly leading to heart failure. Material properties play an important role in determining post-infarction outcome. Due to spatial variation in scarring, material properties can be expected to vary throughout the tissue of a heart after an infarction. In this study we propose a data assimilation technique that can efficiently estimate heterogeneous elastic material properties in a personalized model of cardiac mechanics...
May 17, 2018: Biomechanics and Modeling in Mechanobiology
Fang Wang, Yong Han, Bingyu Wang, Qian Peng, Xiaoqun Huang, Karol Miller, Adam Wittek
In this study, we investigate the effects of modelling choices for the brain-skull interface (layers of tissues between the brain and skull that determine boundary conditions for the brain) and the constitutive model of brain parenchyma on the brain responses under violent impact as predicted using computational biomechanics model. We used the head/brain model from Total HUman Model for Safety (THUMS)-extensively validated finite element model of the human body that has been applied in numerous injury biomechanics studies...
May 12, 2018: Biomechanics and Modeling in Mechanobiology
J Ferruzzi, D Madziva, A W Caulk, G Tellides, J D Humphrey
Aging leads to central artery stiffening and associated hemodynamic sequelae. Because healthy arteries exhibit differential geometry, composition, and mechanical behaviors along the central vasculature, we sought to determine whether wall structure and mechanical function differ across five vascular regions-the ascending and descending thoracic aorta, suprarenal and infrarenal abdominal aorta, and common carotid artery-in 20 versus 100-week-old male wild-type mice. Notwithstanding generally consistent changes across these regions, including a marked thickening of the arterial wall, diminished in vivo axial stretch, and loss of elastic energy storage capacity, the degree of changes tended to be slightly greater in abdominal than in thoracic or carotid vessels...
May 12, 2018: Biomechanics and Modeling in Mechanobiology
André Hemmler, Brigitta Lutz, Christian Reeps, Günay Kalender, Michael W Gee
Endovascular aneurysm repair (EVAR) can involve some unfavorable complications such as endoleaks or stent-graft (SG) migration. Such complications, resulting from the complex mechanical interaction of vascular tissue, SG and blood flow or incompatibility of SG design and vessel geometry, are difficult to predict. Computational vascular mechanics models can be a predictive tool for the selection, sizing and placement process of SGs depending on the patient-specific vessel geometry and hence reduce the risk of potential complications after EVAR...
May 11, 2018: Biomechanics and Modeling in Mechanobiology
Yuxuan Jiang, Xudong Liang, Ming Guo, Yanping Cao, Shengqiang Cai
Most bacteria cells divide by binary fission which is part of a bacteria cell cycle and requires tight regulations and precise coordination. Fast separation of Staphylococcus Aureus (S. Aureus) daughter cells, named as popping event, has been observed in recent experiments. The popping event was proposed to be driven by mechanical crack propagation in the peripheral ring which connected two daughter cells before their separation. It has also been shown that after the fast separation, a small portion of the peripheral ring was left as a hinge...
May 10, 2018: Biomechanics and Modeling in Mechanobiology
Sen Zhang, Xiaoyu Luo, Zongxi Cai
We study the collapsible behaviour of a vessel conveying viscous flows subject to external pressure, a scenario that could occur in many physiological applications. The vessel is modelled as a three-dimensional cylindrical tube of nonlinear hyperelastic material. To solve the fully coupled fluid-structure interaction, we have developed a novel approach based on the Arbitrary Lagrangian-Eulerian (ALE) method and the frontal solver. The method of rotating spines is used to enable an automatic mesh adaptation...
May 9, 2018: Biomechanics and Modeling in Mechanobiology
Jianfeng Kang, Ling Wang, Chuncheng Yang, Lei Wang, Cao Yi, Jiankang He, Dichen Li
A tumour resection normally involves a large tissue resection and bone replacement. Polyether ether ketone (PEEK) has become a suitable candidate for use in various prostheses owing to its lightness in weight, modulus close to that of natural bone, and good biocompatibility, among other factors. This study proposes a new design method for a rib prosthesis using the centroid trajectory of the natural replaced rib, where the strength can be adjusted by monitoring the cross-sectional area, shape, and properties...
May 5, 2018: Biomechanics and Modeling in Mechanobiology
Adrian Moure, Hector Gomez
Amoeboid cells exhibit a highly dynamic motion that can be directed by external chemical signals, through the process of chemotaxis. Here, we propose a three-dimensional model for chemotactic motion of amoeboid cells. We account for the interactions between the extracellular substances, the membrane-bound proteins, and the cytosolic components involved in the signaling pathway that originates cell motility. We show two- and three-dimensional simulations of cell migration on planar substrates, flat surfaces with obstacles, and fibrous networks...
May 4, 2018: Biomechanics and Modeling in Mechanobiology
Shier Nee Saw, Yu Wei Poh, Dawn Chia, Arijit Biswas, Citra Nurfarah Zaini Mattar, Choon Hwai Yap
Significant reductions in blood flow and umbilical diameters were reported in pregnancies affected by intrauterine growth restriction (IUGR) from placental insufficiency. However, it is not known if IUGR umbilical blood vessels experience different hemodynamic wall shear stresses (WSS) compared to normal umbilical vessels. As WSS is known to influence vasoactivity and vascular growth and remodeling, which can regulate flow rates, it is important to study this parameter. In this study, we aim to characterize umbilical vascular WSS environment in normal and IUGR pregnancies, and evaluate correlation between WSS and vascular diameter, and gestational age...
April 24, 2018: Biomechanics and Modeling in Mechanobiology
Arnold D Gomez, Nahla Elsaid, Maureen L Stone, Jiachen Zhuo, Jerry L Prince
Mechanical modeling of tongue deformation plays a significant role in the study of breathing, swallowing, and speech production. In the absence of internal joints, fiber orientations determine the direction of sarcomeric contraction and have great influence over real and simulated tissue motion. However, subject-specific experimental observations of fiber distribution are difficult to obtain; thus, models of fiber distribution are generally used in mechanical simulations. This paper describes modeling of fiber distribution using solutions of Laplace equations and compares the effectiveness of this approach against tractography from diffusion tensor magnetic resonance imaging...
April 19, 2018: Biomechanics and Modeling in Mechanobiology
Z Wang, D Vashishth, R C Picu
Bone toughness emerges from the interaction of several multiscale toughening mechanisms. Recently, the formation of nanoscale dilatational bands and hence the accumulation of submicron diffuse damage were suggested as an important energy dissipation processes in bone. However, a detailed mechanistic understanding of the effect of this submicron toughening mechanism across multiple scales is lacking. Here, we propose a new three-dimensional ultrastructure volume element model showing the formation of nanoscale dilatational bands based on stress-induced non-collagenous protein denaturation and quantify the total energy released through this mechanism in the vicinity of a propagating crack...
April 16, 2018: Biomechanics and Modeling in Mechanobiology
Wenjun Kou, John E Pandolfino, Peter J Kahrilas, Neelesh A Patankar
The aim of this work was to develop a fully coupled bolus-esophageal-gastric model based on the immersed boundary-finite element method to study the process of esophageal emptying across the esophagogastric junction (EGJ). The model included an esophageal segment, an ellipsoid-shaped stomach, a bolus, and a simple model of the passive and active sphincteric functions of the lower esophageal sphincter (LES). We conducted three sets of case studies: (1) the effect of a non-relaxing LES; (2) the influence of the tissue anisotropy in the form of asymmetrical right- and left-sided compliance of the LES segment; and (3) the influence of LES and gastric wall stiffness on bulge formation of the distal esophageal wall...
April 11, 2018: Biomechanics and Modeling in Mechanobiology
Julio Flecha-Lescún, Begoña Calvo, Jesús Zurita, Miguel Ángel Ariza-Gracia
Keratoconus is an idiopathic, non-inflammatory and degenerative corneal disease characterised by a loss of the organisation in the corneal collagen fibrils. As a result, keratoconic corneas present a localised thinning and conical protrusion with irregular astigmatism and high myopia that worsen visual acuity. Intracorneal ring segments (ICRSs) are used in clinic to regularise the corneal surface and to prevent the disease from progressing. Unfortunately, the post-surgical effect of the ICRS is not explicitly accounted beforehand...
March 21, 2018: Biomechanics and Modeling in Mechanobiology
Ningcheng Jiang, Minghai You, Yuhua Wang, Yide Huang, Shusen Xie, Yao Lin, Hongqin Yang
Mitosis is an important physiological event accompanying with dramatic changes of cellar biophysical properties. Failure of mitosis results in cell death or chromosome aneuploidy. In this study, we used atomic force microscopy to probe and compare the biophysical properties of tumor cells at different stages during mitosis. The rounding forces of MCF-7 cells oscillated during mitosis. At anaphase, the average elasticity of cells was higher than that at other phases. Cholesterol depletion with M[Formula: see text]CD led to an increase in the average elasticity, whereas the average roughness of membrane surface decreased at the absence of cholesterol...
March 17, 2018: Biomechanics and Modeling in Mechanobiology
Julia C Quindlen-Hotek, Victor H Barocas
The Pacinian corpuscle (PC) is the cutaneous mechanoreceptor responsible for sensation of high-frequency (20-1000 Hz) vibrations. PCs lie deep within the skin, often in multicorpuscle clusters with overlapping receptive fields. We developed a finite-element mechanical model of one or two PCs embedded within human skin, coupled to a multiphysics PC model to simulate action potentials elicited by each PC. A vibration was applied to the skin surface, and the resulting mechanical signal was analyzed using two metrics: the deformation amplitude ratio ([Formula: see text], [Formula: see text] and the phase shift of the vibration ([Formula: see text], [Formula: see text] between the stimulus and the PC...
March 17, 2018: Biomechanics and Modeling in Mechanobiology
Zainab Altai, Marco Viceconti, Amaka C Offiah, Xinshan Li
Fractures of bone account 25% of all paediatric injuries (Cooper et al. in J Bone Miner Res 19:1976-1981, 2004. ). These can be broadly categorised into accidental or inflicted injuries. The current clinical approach to distinguish between these two is based on the clinician's judgment, which can be subjective. Furthermore, there is a lack of studies on paediatric bone to provide evidence-based information on bone strength, mainly due to the difficulties of obtaining paediatric bone samples...
March 10, 2018: Biomechanics and Modeling in Mechanobiology
Jorge Escribano, Raimon Sunyer, María Teresa Sánchez, Xavier Trepat, Pere Roca-Cusachs, José Manuel García-Aznar
Collective cell migration is regulated by a complex set of mechanical interactions and cellular mechanisms. Collective migration emerges from mechanisms occurring at single cell level, involving processes like contraction, polymerization and depolymerization, of cell-cell interactions and of cell-substrate adhesion. Here, we present a computational framework which simulates the dynamics of this emergent behavior conditioned by substrates with stiffness gradients. The computational model reproduces the cell's ability to move toward the stiffer part of the substrate, process known as durotaxis...
March 2, 2018: Biomechanics and Modeling in Mechanobiology
Michele Marino, Markus von Hoegen, Jörg Schröder, Peter Wriggers
Soft tissues are characterized by a nonlinear mechanical response, highly affected by the multiscale structure of collagen fibers. The effectiveness and the calibration of constitutive models play a major role on the reliability and the applicability of computational models in biomechanics. This paper presents a procedure for the identification of the relationship between collagen-related structural features in soft tissues with model parameters of classical polynomial- and exponential-based constitutive models...
February 28, 2018: Biomechanics and Modeling in Mechanobiology
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