Molecular & Cellular Biomechanics最新文献

{"title":"Fluid Structure Interactions in Ascending Thoracic Aortic Aneurysms","authors":"S. Avril","doi":"10.32604/mcb.2019.05705","DOIUrl":"https://doi.org/10.32604/mcb.2019.05705","url":null,"abstract":"The fluid mechanics community has been interested for many years in hemodynamics. More recently, significant endeavours of the solid mechanics community have permitted to establish constitutive equations and to achieve stress analyses in arterial lesions (atheromatous plaque in coronary or carotid arteries, aneurysms of the aorta). The mechanical properties of blood vessels have often been characterized ex vivo, but medical imaging, including MRI, now allows non-intrusive identifications in vivo. The spatial heterogeneity of these mechanical properties, even at the macroscopic scale, remains poorly explored despite its undeniable interest in understanding the mechanisms of remodeling and degeneration of the tissue. We are interested in the problem of identifying the fields of mechanical properties of aneurysms of the aorta. Scientific barriers are related to the complex geometry, the nonlinear and anisotropic behavior of tissues, the multiaxial loading conditions, and to the measurement of a local response in these tissues. Our identification approaches, based on digital image correlation field measurements and inverse methods, have demonstrated the link between the heterogeneity of mechanical properties and the existence of localized failure modes. A micromechanical approach has also made it possible to develop a mechanobiological model to reproduce the behavior of the aorta in surgical situations and a simulation software is being developed for assistance to personalized surgery in the cardiovascular field.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86789427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical Analysis of a Novel Biodegradable Zinc Alloy Stent Based on Degradation Model","authors":"Kun Peng, Xinyang Cui, A. Qiao, M. Ohta, K. Shimoyama, Y. Mu","doi":"10.32604/mcb.2019.05729","DOIUrl":"https://doi.org/10.32604/mcb.2019.05729","url":null,"abstract":"Biodegradable stents which can avoid risks caused by incompatibility between artery and permanent stents are attracting much interests. However, biodegradable stents have not been extensively applied in clinical therapy because of their insufficient scaffold performance as a result of poor Young’s Modulus of biodegradable materials and weaken structures in degradation process. In this study, a patented stent and a common stent were simulated to degrade in a 40% stenotic vesel based on a corrosion model involving uniform corrosion and stress corrosion. In the degradation process, the scaffold performance of the two stents and their functionality on reshaping diseased vessels are analyzed. The results showed that radial recoiling ratio and mass loss ratio of the common stent is 22.6% and 14.1%, respectively. In comparison, radial recoiling ratio and mass loss ratio of the common stent are definitely lower than those of the common stent, at the value of 7.19% and 3.1%. It is indicated that the patented stent still has a stronger scaffold performance compared with the common stent. Besides, with positive influence of the patented stent on stenotic vessel, a larger and flatter lumen was observed in the plaque deployed with the patented stent. It implies that mechanical performance of biodegradable stents and their functionality highly depend on their geometries. Owing to improved mechanical performance induced by structural innovation, the novel biodegradable zinc alloy stent is promised to be an alternative choice in intervention surgeries.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89986114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atherosclerotic Plaque Rupture Prediction: Imaging-Based Computational Simulation and Multiphysical Modelling","authors":"Zhiyong Li","doi":"10.32604/mcb.2019.06308","DOIUrl":"https://doi.org/10.32604/mcb.2019.06308","url":null,"abstract":"In this article, we summarize our previous work in imaging-based computational modelling and simulation of the interaction between blood flow and atherosclerotic plaque. We also discussed our recent developments in multiphysical modelling of plaque progression and destabilization. Significance and translation of the modelling study to clinical practice are discussed in order to better assess plaque vulnerability and accurately predict a possible rupture.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"2029 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91319109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Approach to the Flow Rate Distribution of Coronary Branches in the Calculation of Fractional Flow Reserve","authors":"A. Qiao, Honghui Zhang, Jun Xia","doi":"10.32604/MCB.2019.05715","DOIUrl":"https://doi.org/10.32604/MCB.2019.05715","url":null,"abstract":"In order to improve the calculation accuracy of computed tomography angiography-derived fractional flow reserve (FFRCT), a mathematical model for setting the patient-specific flow boundary condition was proposed, in which some independent physiological parameters, such as myocardial mass, diastolic blood pressure, heart rate and vessel volume were considered. This model was employed to simulate hemodynamics in sixteen patients with coronary stenosis. The results of FFRCT demonstrated good consistency with invasively measured FFR. The diagnostic accuracy of FFRCT was 85%. The proposed model offers a new approach to improve the accuracy of FFRCT, as well as promotes the clinical application of FFRCT.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90272344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of Autophagy in the Differentiation of EPCs Induced by Shear Stress","authors":"Xiumei Guan, Hong Li, Xin Li, Xiaoyun Zhang, Xiaodong Cui, Hong Yan, YuzhenWang, Shunmei Liu, Min Cheng","doi":"10.32604/MCB.2019.05755","DOIUrl":"https://doi.org/10.32604/MCB.2019.05755","url":null,"abstract":"Endothelial progenitor cells (EPCs) play an important role in postnatal angiogenesis and neovascularization. Previous studies have revealed shear stress could accelerate EPC proliferation, differentiation, migration and so on, which contribute to postnatal angiogenesis and neovascularization. Moreover, some studies indicate that autophagy actively participates angiogenesis by affecting EPC migration and differentiation. Here, we try to elucidate the possible roles of autophagy of EPC differentiation induced by shear stress. Methods and Results：EPCs were exposed to shear stress (12 dyne/cm2). And then the expression of autophagy markers, such as LC3Ⅱ/Ⅰ,P62andATG5, were analyzed using Western blot. The results have shown that in EPCs, shear stress triggered an increase in LC3Ⅱ/Ⅰ and ATG5 at 10 min, which was then followed by a decrease. In contrast, shear stress caused a decrease in P62 at 10 min, which was then followed by an increase. Furthermore, immunostaining revealed that the unsheared cells showed only weak LCⅡ staining. However, shear stress increased LCⅡ staining. Bafromycin experiment confirmed that the increase of autophagy caused by shear stress was due to an increase in the formation of autophagy rather than a decrease in the degradation of autophagosomes. To examine the role of autophagy in the shear stress-induced EPC differentiation, we pretreated late EPCs with 3-MA, an inhibitor of autophagy, before the application of shear stress. Through real time RT-PCR and FACS analyses, we observed that the pretreatment of EPCs with 3-MA significantly inhibited the shear stress induced up-regulation of vWF and CD31. In the mean time, treatment of EPCs with LY294002 (a small molecule inhibitor of PI3K) or KLF2 siRNA inhibited the shear stress-induced EPC autophagy and differentiation. Conclusion：Autophagy is involved in the shear stress-upregulated expression of endothelial markers vWF and CD31 in EPCs. Moreover, this increase was observed to be mediated by PI3K and KLF2. Although further studies are needed to confirm the relationship between these mechanosensitive molecules, the present results may provide new insights into the relationship between EPC autophagy and differentiation induced by shear stress.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82189195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Some Aspects in Mechano-Biology of Platelet and Leukocyte in Blood Flows","authors":"Ying Fang, Jianhua Wu","doi":"10.32604/MCB.2019.05695","DOIUrl":"https://doi.org/10.32604/MCB.2019.05695","url":null,"abstract":"For hemostasis and thrombosis, some proteins, such as Von Willebrand Factor (VWF, a multimeric plasma glycoprotein synthesized in endothelial cells and megakaryocytes and secreted to circulation or attached to endothelial cells), the metalloprotease ADAMTS13 (a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13), P-selectin (one of three selectin family members with a N-terminal C-type lectin domain, an epidermal growth factor (EGF)-like module, a series of consensus repeat (CR) units, a transmembrane segment and a short cyto-plasmic domain) and β2 integrin. In adhesion and aggregation of circulating platelets towards to the sites of vascular injury, VWF on vascular wall captures and activates the circulating platelets through interaction with platelet receptor glycoprotein Ibα (GPIbα). The activated platelets will secrete P-selectin, mediating flowing leukocytes to be captured first to and then rolled on the platelets. Activation of β2 integrin on leukocytes makes the rolling cells slow down and adhere firmly to platelet. Pathological hemodynamic environment may cause platelet-induced inflammation overreaction of leukocytes, leading to mechanical instability of thrombotic plaque. Above mentioned events all are referred to their respective un-well known mechano-chemistry processes. For better understanding on the mechano-chemistry mechanism of interaction of leukocyte with platelet under flows, we have investigated the force-dependent Structure-function of VWF-A domain, force-regulated cleavage of A2 domain of von Willebrand factor (vWF) by ADAMTS13, P-selectin secretion from activated platelet, and P-selectin-mediated Activation of β2 integrin on leukocytes under shear stresses, and so on through AFM and flow chamber experiments and molecular dynamics simulation. Our data showed that, these events mentioned above were biphasic force-dependent. Increasing force stabilizes the globular VWF-A conformation first and then makes it become a spread one with higher affinity with platelet receptor glycoprotein Ibα (GPIbα), the force-regulated cleavage of VWF-A2 domain by ADAMTS13 maybe closely related to the induced-fit of ADMATS13 and VWF-A2, Force triggers and quickens P-selectin-induced Activation of β2 integrin on leukocytes.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73068386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of Coronary Atherosclerotic Plaque Composition Based on Convolutional Neural Network (CNN)","authors":"Yifan Yin, Chunliu He, Biao Xu, Zhiyong Li","doi":"10.32604/MCB.2019.05732","DOIUrl":"https://doi.org/10.32604/MCB.2019.05732","url":null,"abstract":"The tissue composition and morphological structure of atherosclerotic plaques determine its stability or vulnerability. Intravascular optical coherence tomography (IVOCT) has rapidly become the method of choice for assessing the pathology of the coronary arterial wall in vivo due to its superior resolution. However, in clinical practice, the analysis of plaque composition of OCT images mainly relies on the interpretation of images by well-trained experts, which is a time-consuming, labor-intensive procedure and it is also subjective. The purpose of this study is to use the Convolutional neural network (CNN) method to automatically extract the best feature information from the OCT images to characterize the three basic components of atherosclerotic plaque (fibrous, lipid, and calcification). This study selected the OCT images of 20 patients from Nanjing Drum Tower Hospital from 2015.12 to 2016.12. The OCT-reading expert first excluded the images containing the brackets, and then divided all the remaining images, resulting in 1500 plaque OCT images. The expert labeled plaque composition in each image, cutting it into 11*11 image patches and obtained 87390 patches. 75000 of them were set as training examples and the others were set for testing. The classification accuracy of the test set served as the evaluation criterion. The experimental results show that the average classification accuracy of the fibrous, calcification, and lipid patches by the CNN classifier was over 75%, especially to characterize the fibrous patches, whose accuracy could reach more than 80%. The proposed method is effective and robust in the analysis of atherosclerotic plaque composition in coronary OCT images, providing a base for further segmentation study.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80948180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Finite Element Analysis of Fatigue Behavior of Stent in Tapered Arteries","authors":"Xiang Shen, Hongfei Zhu, Ji Song, Jiabao Jiang, Deng Yongquan","doi":"10.32604/MCB.2019.05737","DOIUrl":"https://doi.org/10.32604/MCB.2019.05737","url":null,"abstract":"In order to open up the blocked lumen and remodel the blood environment, vascular stents were usually used to transplant into narrowed blood vessels. Due to its minimally invasive and highly efficiency, stenting has achieved great success in the treatment of cardiovascular diseases. However, failure of stents due to its fatigue will damage the arterial wall, leading to adverse reactions such as thrombosis and in-stent restenosis (ISR), which severely limited its long-term outcome. Therefore, it was very important to predict the service life of stents, especially in tapered arteries. \u0000FEA was adopted to study the effects of arterial tapering and stent material on the fatigue life of stents. Balloon-stent-plaque-vessel coupling systems were established to simulate the working environment of stents in vivo. Five different tapered vessel models were established to study the vessel tapering level on the fatigue life of stents. Besides, the fatigue life of 316L stainless steel stent and L605 cobalt-chromium (Co-Cr) alloy stent deployed into a 0.43° tapered vessel were analyzed and compared. The Goodman diagram method was adopted to evaluate the fatigue resistance of stents. \u0000Results showed that the stress concentration was found on the inner crown of the strut when the stent was subjected to pulsating blood pressure. It was similar to the stress distribution on the stent after expansion. This also indicated that the crown of the strut played a decisive role in the long-term efficacy of the stent. The maximum average stress of Co-Cr alloy stent was higher than 316L stainless stent. However, the fatigue resistance of stents was improved by simply changing stent material from 316L stainless to L605 cobalt-chromium alloy. So the L605 Co-Cr alloy stent can withstand greater stress without fatigue. In addition, the tapering of the vessel will also affect the fatigue performance of the stent. The stent implantation in tapered vessels could lead to greater residual stress and shorter fatigue life of the stent. With the tapering level gradually increased, the minimum fatigue safety factor of the stent decreased, which indicated the stent was more likely to fatigue. Compared to a straight vessel, the fatigue life of the stent was shortened by 9.8%, when it was deployed in a 1.13° tapered vessel. \u0000The obtained results showed that finite element analysis was an effective tool to predict stent fatigue life. The method that predicted stent fatigue life in tapered vessels can help clinicians select stents that are more suitable for tapered vessels and help stent engineers design stents that are more resistant to fatigue.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77803589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Investigation of the Hemodynamic Environment Change in Patient-Specific Intracranial Aneurysm with Progressive Stenosis in Unilateral Internal Carotid Artery","authors":"Guangyu Zhu, Yuan Wei, Q. Yuan, Ge Yan, Jian Yang","doi":"10.32604/MCB.2019.05730","DOIUrl":"https://doi.org/10.32604/MCB.2019.05730","url":null,"abstract":"Intracranial aneurysm (IAs) is a frequently localized cerebral vascular disorder of an overall prevalence of 5-8% [Cebral (2013)]. Subarachnoid hemorrhage (SAH) caused by IAs rupture is one of the major causes of mortality and morbidity in the modern world. Local hemodynamic characteristics played important roles in the rupture of IAs and has been studied extensively from different perspectives [Liu (2015); Brinjikji (2017)]. However, the influence of progressive cerebral stenosis on the hemodynamic of the distal cerebral aneurysm is yet to be further investigated. In this study, a set of patient-specific computational fluid dynamics (CFD) simulations were performed to investigate the impact of internal carotid artery (ICA) stenosis growing on the hemodynamic environments in an anterior communicating artery aneurysm (ACoAA).","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"132 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80014748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Aortic Flow Patterns in Patients with and without Aortic Valve Disease: Hemodynamic Simulation Based on PC-MRI and CTA Data","authors":"Lijian Xu, Lekang Yin, F. Liang","doi":"10.32604/MCB.2019.05741","DOIUrl":"https://doi.org/10.32604/MCB.2019.05741","url":null,"abstract":"Recent studies have revealed that aortic valve diseases are associated with the increased incidence of the aortopathy development. However, the influence of aortic valve diseases on aortic hemodynamics remains unclear. The purpose of this study was therefore to investigate the hemodynamic differenecs in patients with and without aortic valve disease through patient-specific simulations performed on two aorta models (BAV with severe stenosis vs. normal tricuspid aortic valve (TAV)). Realistic geometries and boundary conditions were obtained from computed tomography angiography (CTA) and phase-contrast magnetic resonance imaging (PC-MRI) measurements, respectively. In addition, 4D-MRI were performed to validate the the numerical methods used to simulate transient flow characteristics. Obtained results shown that the 3D streamlines in the patient with normal TAV were relatively symmetric and evenly distributed. For the patient with BAV, concentrated and high-speed inflow jets were found to impinge on the ascending aorta accompanied by strong vortices. These results indicate that the aortic valve phenotype plays a crucial role in featuring the disturbed flows primarily in ascending aorta, which may relate to the development of aortic diseases.","PeriodicalId":48719,"journal":{"name":"Molecular & Cellular Biomechanics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88781948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}