Showing 6 results for Atherosclerosis
Seyedeh Fatemeh Sajjadi, Mohammad Ali Boroumand, Mehrdad Behmanesh,
Volume 11, Issue 3 (10-2020)
Abstract
Atherosclerosis is a chronic vascular disease and remains the leading cause of death and morbidity worldwide. Endothelial dysfunction is an important factor in the progression of atherosclerotic disease. Increased expression of cell adhesion index genes and decreased cell-binding proteins lead to abnormal endothelial function. These molecular changes are one of the most important indicators of endothelial cell dysfunction and the progression of atherosclerosis. CXCR3 is a G-protein-coupled chemokine receptor expressed by endothelial cells. The role of the receptor CXCR3 and its ligands in endothelial cells and heart disease is not yet fully understood. In this study, we evaluated the effect of CXCR3 downregulation on the expression level of adhesion (I-CAM-1, V-CAM-1), tight junction (TJP1), related to endothelial dysfunction.
In order to reduce the expression of the CXCR3 gene, the RNA-cleaving DNAzyme was used against the mRNA of the CXCR3 gene. DNAzyme was transfused into HUVEC cells by TurboFectTM. After confirmation of decreased CXCR3 gene expression, RNA extraction and cDNA synthesis were performed and then the expression of markers was evaluated by RT-qPCR technique.
Our result was showed the expression level of I-CAM-1 and V-CAM-1 were showed significant up-regulation in transfected cells compared with control cells, while the TJP1 gene was not showed significant change. It seems that reducing the CXCR3 gene expression could induce endothelial dysfunction through the change of adhesion markers genes expression. Therefore, this receptor can be considered as a potential molecular target for a better understanding of the mechanism of atherosclerosis.
Volume 14, Issue 4 (7-2014)
Abstract
Recently, the use of coronary stents in interventional procedures has rapidly increased and different stent models, with different geometries and materials, have been introduced in the market. In order to select the most appropriate stent model, it is necessary to analyze and compare the mechanical behavior of different types of stent. In this paper, finite element method is used for investigating the effect of stent geometry and material properties on its behavior. Two commercially available stent designs with different geometries (the Palmaz–Schatz and NIR stents) and two different stent materials (stainless steel 304 and Cobalt alloy MP35N) are modeled and their behavior during the deployment is compared in terms of stress distribution in the stent and vessel, and outer diameter changes. Moreover, the effect of stent geometry and material properties on the restenosis after coronary stent placement is investigated by comparing the stress distribution in the arteries. According to the findings, the possibility of restenosis after coronary stenting is lower for NIR stent in comparison with Palmaz–Schatz stent. Moreover, stainless steel 304 is more suitable material for manufacturing stents, in comparison with the other one.
Volume 16, Issue 11 (1-2017)
Abstract
Nowadays the use of Drug Eluting Stents (DESs) is considered as a successful method for the treatment of coronary artery blockage. In order to study the impact of the presence of topcoat on heparin-eluting stents efficacy, two designs (with and without drug free topcoat) have been compared to each other. Moreover, here the importance of the plasma flow as a controversial topic among researchers has been studied. In order to closer to reality heart working, plasma flow is considered as a pulsatile fashion. Also, the injury of the coronary artery penetrated to a depth of media layer during angioplasty. Volume-averaged porous media equations which describe the drug release dynamics are employed and solved numerically by Finite Volume Method (FVM). Results put the amount of strut penetration in the forefront of importance. Local drug pharmacokinetics experiences significant changes by strut passing through endothelium, intima and Internal Elastic Lamina (IEL) and being contiguous with media layer. Although the plasma flow decreases/increases the amount of concentration level and subsequently decreases/increases the amount of drug mass in media/adventitia layer, but the results show that these effects are not significant. Among other findings, it is notable that the presence of topcoat has a negligible effect on the release characteristics.
Volume 16, Issue 11 (1-2017)
Abstract
Injection drug micro particles into arteries is one of the stenosis treatments. Micro particles scattered in blood flow collide with plaques, drug is absorbed to treat stenosis. Since the collision of drug particles with artery wall depends on blood flow pattern, the efficiency of this method relies on guiding drug particles to stenosed site, otherwise the patient must take much higher drug dosage which has various side effects. Applying magnetic field and guiding drug particles to the target area extensively increases efficiency of the treatment and cuts side effects. In the present study, efficiency of using drug particles in vertebrobasilar system to treat atherosclerosis with and without applying magnetic field has been investigated. Ansys-Fluent commercial software has been used for numerical simulation. Results indicate applying magnetic field plays an important role in drug particles circulation as drug captivation surges almost 16 times. Injecting location and the particle diameters also have been examined and found to be important in the treatment effectiveness.
Volume 17, Issue 3 (5-2017)
Abstract
In-stent restenosis is one of the important inefficient reasons about Drug Eluting Stents (DESs). Awareness of how polymer coated drug distributes by these devices provides valuable informations about its efficacy. Porous media theory has been employed in the modeling of drug polymer and the injured arterial wall composed of media and adventitia. The stabished coupled PDEs describing local pharmacokinets of heparin has been solved numerically by finite volume method. Two approaches, single phase and two phases models, has been chosen for coating and the effect of local mass non-equilibrium dynamics in the coating on drug distribution has been evaluated by allocating three magnitude for solid-liquid transfer time characteristic. Moreover, the effect of lost drug by vasavasorum and microcapilaries has been considered as well as cell metabolism. The results show a significant change in drug concentration distribution in the presence of phase change happening. Reducing in solid-liquid transfer time characteristic is associated with drastic reducing in both drug egression from polymer and wash out from adventitia and has a pleasant effect. Also, consumtion of drug declines concentration level in the wall dramatically, specially in adventitia.
Volume 19, Issue 3 (3-2019)
Abstract
Tortuosity is an abnormality that may occur in some arteries, such as carotid. It can reduce the blood flow to distal organs, and even in severe cases, causes ischemia and stroke. Tortuosity can be congenital or occurs due to hypertension and reduced axial pre-stretch of artery, in which case called buckling. Since atherosclerotic plaques disrupt the normal pattern of blood flow, and thus make the artery more susceptible to buckling, in this study, the effect of atherosclerotic plaques on arterial stability has been investigated using computational simulation of fluid-structure interaction under pulsatile flow and large deformation. Ideal and 3D geometry of normal and atherosclerotic carotid artery with different plaques (symmetric or asymmetric and in different percentage of stenosis) were constructed and used to simulate normal (1.5) and reduced (1.3) axial stretch ratio by ADINA. The blood flow was assumed to be Newtonian and laminar. Arterial wall was considered as an anisotropic and hyperelastic material based on the Ogden’s model. The results are verified by comparison with the available ones in the literature. It is observed that stenosis reduces the critical buckling pressure and arteries with asymmetric plaque have lower critical buckling pressure compared to the arteries with symmetric plaque. By reducing the axial stretch ratio from 1.5 to 1.3, the critical buckling pressure is reduced by 33-39 percent. Buckling increases the peak stress in the plaque and thus increases the risk of plaque rupture.
