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Biomechanics and Modeling in Mechanobiology

Ilaria Cinelli, Michel Destrade, Peter McHugh, Antonia Trotta, Michael Gilchrist, Maeve Duffy
The aim was to investigate mechanical and functional failure of diffuse axonal injury (DAI) in nerve bundles following frontal head impacts, by finite element simulations. Anatomical changes following traumatic brain injury are simulated at the macroscale by using a 3D head model. Frontal head impacts at speeds of 2.5-7.5 m/s induce mild-to-moderate DAI in the white matter of the brain. Investigation of the changes in induced electromechanical responses at the cellular level is carried out in two scaled nerve bundle models, one with myelinated nerve fibres, the other with unmyelinated nerve fibres...
November 14, 2018: Biomechanics and Modeling in Mechanobiology
Matthew Becton, Rodney D Averett, Xianqiao Wang
Medical studies have consistently shown that the best defense against cancer is early detection. Due to this, many efforts have been made to develop methods of screening patient blood quickly and cheaply. These methods range from separation via differences in size, electrostatic potential, chemical potential, antibody-binding affinity, among others. We propose a method of separating cells which have similar size and outer coatings, but which differ in their elastic properties. Such a method would be useful in detecting cancerous cells, which may have similar properties to leukocytes or erythrocytes but differ in their stiffness and deformation response...
November 11, 2018: Biomechanics and Modeling in Mechanobiology
F A Braeu, R C Aydin, Christian J Cyron
Growth in soft biological tissues in general results in anisotropic changes of the tissue geometry. It remains a key challenge in biomechanics to understand, quantify, and predict this anisotropy. In this paper, we demonstrate that anisotropic tissue stiffness and the well-known mechanism of tensional homeostasis induce a natural anisotropy of the geometric changes resulting from volumetric growth in soft biological tissues. As a rule of thumb, this natural anisotropy makes differential tissue volume elements dilate mainly in the direction(s) of lowest stiffness...
November 9, 2018: Biomechanics and Modeling in Mechanobiology
Minliang Liu, Liang Liang, Haofei Liu, Ming Zhang, Caitlin Martin, Wei Sun
It is well known that residual deformations/stresses alter the mechanical behavior of arteries, e.g., the pressure-diameter curves. In an effort to enable personalized analysis of the aortic wall stress, approaches have been developed to incorporate experimentally derived residual deformations into in vivo loaded geometries in finite element simulations using thick-walled models. Solid elements are typically used to account for "bending-like" residual deformations. Yet, the difficulty in obtaining patient-specific residual deformations and material properties has become one of the biggest challenges of these thick-walled models...
November 9, 2018: Biomechanics and Modeling in Mechanobiology
Alexander Synek, Christopher J Dunmore, Tracy L Kivell, Matthew M Skinner, Dieter H Pahr
Previously, a micro-finite element (micro-FE)-based inverse remodelling method was presented in the literature that reconstructs the loading history of a bone based on its architecture alone. Despite promising preliminary results, it remains unclear whether this method is sensitive enough to detect differences of bone loading related to pathologies or habitual activities. The goal of this study was to test the sensitivity of the inverse remodelling method by predicting joint loading histories of metacarpal bones of species with similar anatomy but clearly distinct habitual hand use...
November 9, 2018: Biomechanics and Modeling in Mechanobiology
Yu Li, Guohong Shi, Jianfei Du, Jianping Wang, Pingyan Bian
The swirling motion of blood flow is a widespread physiological flow phenomenon in the human body. The probability of cardiovascular and cerebrovascular diseases could be effectively reduced by swirling blood flow. In this study, first we proposed a new integrated vascular model with spiral folds on the inner wall. Based on the model, fluid-solid coupling simulation analyses of blood and blood vessels were performed. The results indicate that the spiral folds cause the swirling flow. This model provides new insights that may be of use for developing methods to generate swirling flow...
November 3, 2018: Biomechanics and Modeling in Mechanobiology
Borys I Ostapienko, Domenico Lopez, Svetlana V Komarova
Biologically guided precipitation of calcium phosphates is important for the formation of calcified human tissues, such as bone and teeth, and is of practical significance in numerous industrial and agricultural processes, such as wastewater treatment and dairy ultrafiltration. Mineral precipitation is physicochemically complex and becomes even more complex in the presence of biological materials. The theoretical foundation of phase transition in general has been developed and is vital for many applications, such as metallurgy and weather prediction...
November 2, 2018: Biomechanics and Modeling in Mechanobiology
Toshihiro Sera, Hiroaki Kobayashi, Masato Hoshino, Kentaro Uesugi, Takeshi Matsumoto, Masao Tanaka
In this study, based on the measurements of intracortical vascular canal structure, we investigated the disuse effect on local O2 supply in the cortical bones of growing rats. Hindlimb disuse was produced by unilateral sciatic neurectomy (SN) at 4 weeks age. The canal network structures within tibial cortical bone were evaluated in 8- and 12-week-old rats undergoing SN or no treatment (control) by synchrotron radiation micro-CT. Additionally, we developed an intracortical network model by combining the imaged-based canal network with a bone matrix containing theoretical lacunar-canalicular network, and determined the distribution of O2 concentration in bone tissue numerically...
November 1, 2018: Biomechanics and Modeling in Mechanobiology
Annalisa Canovetti, Francesca Rossi, Michele Rossi, Luca Menabuoni, Alex Malandrini, Roberto Pini, Paolo Ferrara
The aim of this study was to qualitatively evaluate the biomechanical load resistance of different surgical wound configurations (mushroom, zig-zag, anvil and conventional trephination) in penetrating keratoplasty (PK) by designing a 2D and a 3D finite-element biomechanical model of the cornea. A mathematical model of the human cornea was developed, and different geometric configurations for PK were designed. The internal pressure was raised until the wound misaligned; wound prolapse then occurred. Better wound resistance was found in all the laser trephined profiles tested in comparison with the conventional straight one...
October 31, 2018: Biomechanics and Modeling in Mechanobiology
Meisam Soleimani, Shahab Sahraee, Peter Wriggers
In this paper, a novel 3D numerical method has been developed to simulate red blood cells (RBCs) based on the interaction between a shell-like solid structure and a fluid. RBC is assumed to be a thin shell encapsulating an internal fluid (cytoplasm) which is submerged in an external fluid (blood plasma). The approach is entirely based on the smoothed particle hydrodynamics (SPH) method for both fluid and the shell structure. Both cytoplasm and plasma are taken to be incompressible Newtonian fluid. As the kinematic assumptions for the shell, Reissner-Mindlin theory has been introduced into the formulation...
October 30, 2018: Biomechanics and Modeling in Mechanobiology
A Korneva, L Zilberberg, D B Rifkin, J D Humphrey, C Bellini
Fibrillin-1 is an elastin-associated glycoprotein that contributes to the long-term fatigue resistance of elastic fibers as well as to the bioavailability of transforming growth factor-beta (TGFβ) in arteries. Altered TGFβ bioavailability and/or signaling have been implicated in aneurysm development in Marfan syndrome (MFS), a multi-system condition resulting from mutations to the gene that encodes fibrillin-1. We recently showed that the absence of the latent transforming growth factor-beta binding protein-3 (LTBP-3) in fibrillin-1-deficient mice attenuates the fragmentation of elastic fibers and focal dilatations that are characteristic of aortic root aneurysms in MFS mice, at least to 12 weeks of age...
October 10, 2018: Biomechanics and Modeling in Mechanobiology
Dale L Robinson, Hongyuan Jiang, Qichun Song, Christopher Yates, Peter Vee Sin Lee, John D Wark
Fracture risk assessment using dual-energy X-ray absorptiometry (DXA) frequently fails to diagnose osteoporosis amongst individuals who later experience fragility fractures. Hence, more reliable techniques that improve the prediction of fracture risk are needed. In this study, we evaluated a finite element (FE) modelling framework based on clinical peripheral quantitative computed tomography (pQCT) imaging of the tibial epiphysis and diaphysis to predict the stiffness at these locations in compression, shear, torsion and bending...
October 6, 2018: Biomechanics and Modeling in Mechanobiology
Immanuel David Madukauwa-David, Eric L Pierce, Fatiesa Sulejmani, Joshua Pataky, Wei Sun, Ajit P Yoganathan
Postoperative suture dehiscence is an important mode of short-term mitral and tricuspid valve (MV, TV) repair failure. We sought to evaluate suture pullout forces and collagen density in human atrioventricular valves for a better understanding of the comparative physiology between the valves and the underlying mechanobiological basis for suture retention. Mitral and tricuspid annuli were each excised from hearts from human donors age 60-79 with no history of heart disease (n = 6). Anchor sutures were vertically pulled until tearing through the tissue...
October 4, 2018: Biomechanics and Modeling in Mechanobiology
M Umar Qureshi, Mitchel J Colebank, L Mihaela Paun, Laura Ellwein Fix, Naomi Chesler, Mansoor A Haider, Nicholas A Hill, Dirk Husmeier, Mette S Olufsen
This study uses a one-dimensional fluid dynamics arterial network model to infer changes in hemodynamic quantities associated with pulmonary hypertension in mice. Data for this study include blood flow and pressure measurements from the main pulmonary artery for 7 control mice with normal pulmonary function and 5 mice with hypoxia-induced pulmonary hypertension. Arterial dimensions for a 21-vessel network are extracted from micro-CT images of lungs from a representative control and hypertensive mouse. Each vessel is represented by its length and radius...
October 3, 2018: Biomechanics and Modeling in Mechanobiology
Pinaki Bhattacharya, Zainab Altai, Muhammad Qasim, Marco Viceconti
Osteoporotic hip fractures are a major healthcare problem. Fall severity and bone strength are important risk factors of hip fracture. This study aims to obtain a mechanistic explanation for fracture risk in dependence of these risk factors. A novel modelling approach is developed that combines models at different scales to overcome the challenge of a large space-time domain of interest and considers the variability of impact forces between potential falls in a subject. The multiscale model and its component models are verified with respect to numerical approximations made therein, the propagation of measurement uncertainties of model inputs is quantified, and model predictions are validated against experimental and clinical data...
October 1, 2018: Biomechanics and Modeling in Mechanobiology
Matthew R Bersi, Chiara Bellini, Jay D Humphrey, Stéphane Avril
We recently developed an approach to characterize local nonlinear, anisotropic mechanical properties of murine arteries by combining biaxial extension-distension testing, panoramic digital image correlation, and an inverse method based on the principle of virtual power. This experimental-computational approach was illustrated for the normal murine abdominal aorta assuming uniform wall thickness. Here, however, we extend our prior approach by adding an optical coherence tomography (OCT) imaging system that permits local reconstructions of wall thickness...
September 24, 2018: Biomechanics and Modeling in Mechanobiology
Zong-Zheng Chen, Wei-Mo Yuan, Cheng Xiang, De-Pei Zeng, Bo Liu, Kai-Rong Qin
Intracellular calcium dynamics plays an important role in the regulation of vascular endothelial cellular functions. In order to probe the intracellular calcium dynamic response under synergistic effect of wall shear stress (WSS) and adenosine triphosphate (ATP) signals, a novel microfluidic device, which provides the adherent vascular endothelial cells (VECs) on the bottom of microchannel with WSS signal alone, ATP signal alone, and different combinations of WSS and ATP signals, is proposed based upon the principles of fluid mechanics and mass transfer...
September 6, 2018: Biomechanics and Modeling in Mechanobiology
Adela Capilnasiu, Myrianthi Hadjicharalambous, Daniel Fovargue, Dharmesh Patel, Ondrej Holub, Lynne Bilston, Hazel Screen, Ralph Sinkus, David Nordsletten
Characterisation of soft tissue mechanical properties is a topic of increasing interest in translational and clinical research. Magnetic resonance elastography (MRE) has been used in this context to assess the mechanical properties of tissues in vivo noninvasively. Typically, these analyses rely on linear viscoelastic wave equations to assess material properties from measured wave dynamics. However, deformations that occur in some tissues (e.g. liver during respiration, heart during the cardiac cycle, or external compression during a breast exam) can yield loading bias, complicating the interpretation of tissue stiffness from MRE measurements...
August 27, 2018: Biomechanics and Modeling in Mechanobiology
Rohit Y Dhume, Elizabeth D Shih, Victor H Barocas
Fatigue as a mode of failure becomes increasingly relevant with age in tissues that experience repeated fluctuations in loading. While there has been a growing focus on the mechanics of networks of collagen fibers, which are recognized as the predominant mechanical components of soft tissues, the network's fatigue behavior has received less attention. Specifically, it must be asked (1) how the fatigue of networks differs from that of its component fibers, and (2) whether this difference in fatigue behaviors is affected by changes in the network's architecture...
August 27, 2018: Biomechanics and Modeling in Mechanobiology
Zhou Zhou, Xiaogai Li, Svein Kleiven
Traumatic brain injury is a leading cause of disability and mortality. Finite element-based head models are promising tools for enhanced head injury prediction, mitigation and prevention. The reliability of such models depends heavily on adequate representation of the brain-skull interaction. Nevertheless, the brain-skull interface has been largely simplified in previous three-dimensional head models without accounting for the fluid behaviour of the cerebrospinal fluid (CSF) and its mechanical interaction with the brain and skull...
August 27, 2018: Biomechanics and Modeling in Mechanobiology
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