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Immune storage from SARS-CoV-2 infection in hamsters supplies variant-independent security but still makes it possible for virus tranny.
External support stent is a potential means for restricting the deformation and reducing wall stress of the vein graft, thereby improving the long-term patency of the graft in coronary artery bypass surgery. However, there still lacks a theoretical reference for choosing the size of stent based on the diameter of graft. Taking the VEST (venous external support) stent currently used in the clinical practice as the object of study, we constructed three models of VEST stents with different diameters and coupled them respectively to a model of the great saphenous vein graft, and numerically simulated the expansion-contraction process of the vein graft under the constraint of the stents to quantitatively evaluate the influence of stent size on the radial deformation and wall stress of the vein graft. The results showed that while the stent with a small diameter had a high restrictive effect in comparison with larger stents, it led to more severe concentration of wall stress and sharper changes in radial deformation along the axis of the graft, which may have adverse influence on the graft. In order to solve the aforementioned problems, we ameliorated the design of the stent by means of changing the cross-sectional shape of the thick and thin alloy wires from circle into rectangle and square, respectively, while keeping the cross-sectional areas of alloy wires and stent topology unchanged. Further numerical simulations demonstrated that the ameliorated stent evidently reduced the degrees of wall stress concentration and abrupt changes in radial deformation, which may help improve the biomechanical environment of the graft while maintaining the restrictive role of the stent.Numerical simulation of stent deployment is very important to the surgical planning and risk assess of the interventional treatment for the cardio-cerebrovascular diseases. Our group developed a framework to deploy the braided stent and the stent graft virtually by finite element simulation. By using the framework, the whole process of the deployment of the flow diverter to treat a cerebral aneurysm was simulated, and the deformation of the parent artery and the distributions of the stress in the parent artery wall were investigated. The results provided some information to improve the intervention of cerebral aneurysm and optimize the design of the flow diverter. Furthermore, the whole process of the deployment of the stent graft to treat an aortic dissection was simulated, and the distributions of the stress in the aortic wall were investigated when the different oversize ratio of the stent graft was selected. The simulation results proved that the maximum stress located at the position where the bare metal ring touched the artery wall. The results also can be applied to improve the intervention of the aortic dissection and the design of the stent graft.Biodegradable stents (BDSs) are the milestone in percutaneous coronary intervention(PCI). Biodegradable polymeric stents have received widespread attention due to their good biocompatibility, moderate degradation rate and degradation products without toxicity or side effects. https://www.selleckchem.com/products/escin.html However, due to the defects in mechanical properties of polymer materials, the clinical application of polymeric BDS has been affected. In this paper, the BDS geometric configuration design was analyzed to improve the radial strength, flexibility and reduce the shrinkage rate of biodegradable polymeric stents. And from the aspects of numerical simulation, in vitro experiment and animal experiment, the configuration design and mechanical properties of biodegradable polymeric stents were introduced in detail in order to provide further references for the development of biodegradable polymeric stents.The dynamic coupling of stent degradation and vessel remodeling can influence not only the structural morphology and material property of stent and vessel, but also the development of in-stent restenosis. The research achievements of biomechanical modelling and analysis of stent degradation and vessel remodeling were reviewed; several noteworthy research perspectives were addressed, a stent-vessel coupling model was developed based on stent damage function and vessel growth function, and then concepts of matching ratio and risk factor were established so as to evaluate the treatment effect of stent intervention, which may lay the scientific foundation for the structure design, mechanical analysis and clinical application of biodegradable stent.Atherosclerosis is a complex and multi-factorial pathophysiological process. link2 Researches over the past decades have shown that the development of atherosclerotic vulnerable plaque is closely related to its components, morphology, and stress status. link3 Biomechanical models have been developed by combining with medical imaging, biological experiments, and mechanical analysis, to study and analyze the biomechanical factors related to plaque vulnerability. Numerical simulation could quantify the dynamic changes of the microenvironment within the plaque, providing a method to represent the distribution of cellular and acellular components within the plaque microenvironment and to explore the interaction of lipid deposition, inflammation, angiogenesis, and other processes. Studying the pathological mechanism of plaque development would improve our understanding of cardiovascular disease and assist non-invasive inspection and early diagnosis of vulnerable plaques. The biomechanical models and numerical methods may serve as a theoretical support for designing and optimizing treatment strategies for vulnerable atherosclerosis.Coronary artery diseases (CAD) have always been serious threats to human health. The measurement, constitutive modeling, and analysis of mechanical properties of the blood vessel wall can provide a tool for disease diagnosis, stent implantation, and artificial artery design. The vessel wall has both active and passive mechanical properties. The passive mechanical properties are mainly determined by elastic and collagen fibers, and the active mechanical properties are determined by the contraction of vascular smooth muscle cells (VSMC). Substantial studies have shown that, the two-layer model of the vessel wall can feature the mechanical properties well, and the circumferential, axial and radial strain and stress are of great significance in arterial wall mechanics. This study reviewed recent investigations of mechanical properties of the vessel wall. Challenges and opportunities in this area are discussed relevant to the clinical treatment of coronary artery diseases.With China's aging society, the number of patients with hemiplegia caused by cerebrovascular accident is increasing gradually. The risk of hip fracture in the first year after the onset of this kind of patients is 4 times higher than that of ordinary people, and most of them occur in the side of hemiplegia. For senile femoral neck fracture, artificial joint replacement is almost the first choice of treatment, with mature operation technology and good curative effect. At present, it is considered that if the muscle strength of hemiplegic side can reach grade III after cerebral vascular accident, hip arthroplasty can be the first choice for hemiplegic patients with hemiplegic femoral neck fracture. However, the situation of hemiplegic patients is different from that of ordinary people. The hemiplegic limbs may have muscle atrophy, muscle strength imbalance, osteoporosis and other problems, which brings difficulties to the formulation of surgical plan. This paper mainly discusses the choice of surgical approach, the use of total hip arthroplasty or hemiarthroplasty, the use of cemented prosthesis or cementless prosthesis, and how to reduce the incidence of postoperative dislocation The purpose is to provide more reference evidence for orthopedic doctors in clinical decision-making.
To study effects of postoperative regular training of core muscle strength guided by the concept of enhanced recovery after surgery (ERAS) on the rehabilitation of elderly patients with osteoporotic lumbar vertebral compression fracture after vertebroplasty (PVP) and kyphoplasty(PKP).

Ninety-four elderly patients with osteoporotic lumbar compression fractures who underwent PKP or PVP from January 2016 to January 2018 and met inclusion criteria were divided into observation group and control group. All the patients were treated with routine anti osteoporosis therapy after operation. There were 47 patients in the observationgroup, including 18 males and 29 females, with an average age of (62.62±3.21) years old;in the control group, there were 47 cases, including 17 males and 30 females, with an average age of (62.38±2.84) years old. The patients in the control group were trained by traditional way, and the patients in observation group were instructed to conduct regular training of core muscle strength accoen the two groups were significantly improved (
<0.05).

Early regular core strength training has a positive effect on early functional recovery and improvement of life ability after PKP or PVP for elderly patients with osteoporotic lumbar compression fractures, which is in line with the concept of accelerated rehabilitation surgery.
Early regular core strength training has a positive effect on early functional recovery and improvement of life ability after PKP or PVP for elderly patients with osteoporotic lumbar compression fractures, which is in line with the concept of accelerated rehabilitation surgery.Titanium alloy has good biological properties and is commonly used in orthopedics, but its bone integrity and antibacterial properties are poor, so surface modification is needed to make up for its shortcomings. Chitosan has good biocompatibility and film forming ability, and can be used as a carrier to introduce the target drug to the surface of titanium alloy, which can effectively improve the biological properties of titanium alloy materials and increase its application range. In this paper, the related research of chitosan surface modified titanium alloy materials in recent years is summarized. The modification methods of chitosan coating, the improvement of osteogenesisand antibacterial properties of titanium alloy materials are discussed in order to provide guidance for the clinical application of coating modification of titanium alloy materials.Proximal humerus fracture is one of the common shoulder fractures. With the increase in incidence, the proportion of surgical intervention is increasing. This paper explores the traditional and new treatment methods for proximal humerus fracture. Locking plate technology is the most commonly used method in the clinic, but its complication rate of intra-articular screw penetration and reoperation is too high.Fibular strut allografts can provide adequate support, but it is a significant trauma surgery and has a high incidence of potential disruption to necessary vascular.Arthroplasty is one of the treatments for complex proximal humerus fractures, but it has a long learning curve and high cost.In recent years, the proximal humerus cage's intervention model has emerged, which has the inherent advantagesof a three dimensional structure, which can provide adequate load bearing support for the humeral head and provide flexible screw placement Angle. The cage offers a new technical option to reduce postoperative complications and improve patients' rehabilitation safety.
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