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https://www.readbyqxmd.com/read/28433790/a-strain-mediated-corrosion-model-for-bioabsorbable-metallic-stents
#1
E Galvin, D O'Brien, C Cummins, B J Mac Donald, C Lally
This paper presents a strain-mediated phenomenological corrosion model, based on the discrete finite element modelling method which was developed for use with the ANSYS Implicit finite element code. The corrosion model was calibrated from experimental data and used to simulate the corrosion performance of a WE43 magnesium alloy stent. The model was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile. The non-linear plastic strain model, extrapolated from the experimental data, was also found to adequately capture the corrosion-induced reduction in the radial stiffness of the stent over time...
April 19, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28397881/a-promising-biodegradable-magnesium-alloy-suitable-for-clinical-vascular-stent-application
#2
Lin Mao, Li Shen, Jiahui Chen, Xiaobo Zhang, Minsuk Kwak, Yu Wu, Rong Fan, Lei Zhang, Jia Pei, Guangyin Yuan, Chengli Song, Junbo Ge, Wenjiang Ding
We report a Mg alloy Mg-2.2Nd-0.1Zn-0.4Zr (wt.%, denoted as JDBM-2) showing great potential in clinical vascular stent application by integrating the advantages of traditional medical stainless steel and polymer. This alloy exhibits high yield strength and elongation of 276 ± 6 MPa and 34.3 ± 3.4% respectively. The JDBM-2 with a stable degradation surface results in a highly homogeneous degradation mechanism and long-term structural and mechanical durability. In vitro cytotoxicity test of the Mg extract via human vascular endothelial cells (HUVECs) indicates that the corrosion products are well tolerated by the tested cells and potentially negligible toxic effect on arterial vessel walls...
April 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28290901/-ability-to-overcome-the-thrombocyte-resistance-to-acetylsalicylic-acid-in-patients-with-coronary-artery-disease-after-myocardial-revascularization-with-coronary-stenting
#3
I V Pershukov, S L Ostaschenko, T N Kuznetsova, S N Scherbo, Z A Karben, E V Sokryukina, A A Omarov, D M Ramazanov, N V Bosak, L V Shulzhenko, R K Kalmatov, T A Batyraliev, B A Sidorenko
Resistance to acetylsalicylic acid (ASA) in patients with coronary artery disease is a poor predictor for the development of atherothrombotic complications. In 277 patients with coronary artery disease suffered uncomplicated coronary angioplasty with stent implantation, we was estimated arachidon-induced platelet aggregation during treatment with acetylsalicylic acid by bedside VerifyNow Assay test at 28-90 days after the intervention. It was found that 18.9% of the 144 patients receiving a combination of ASA 75 mg with 15...
July 2016: Kardiologiia
https://www.readbyqxmd.com/read/28286555/silicone-covered-biodegradable-magnesium-stent-insertion-in-the-esophagus-a-comparison-with-plastic-stents
#4
Yue-Qi Zhu, Kai Yang, Laura Edmonds, Li-Ming Wei, Reila Zheng, Ruo-Yu Cheng, Wen-Guo Cui, Ying-Sheng Cheng
BACKGROUND: We determined the feasibility of, and tissue response to silicone-covered biodegradable magnesium- and plastic-stent insertion into the esophagus in rabbits. METHODS: The mechanical compression-recovery characteristics and degradation behaviors of the magnesium stent were investigated in vitro. A total of 45 rabbits were randomly divided into a magnesium- (n = 15) and a plastic- (n = 15) stent group, and underwent stent insertion into the lower third of the esophagus under fluoroscopic guidance; a control group (n = 15) did not undergo the intervention...
January 2017: Therapeutic Advances in Gastroenterology
https://www.readbyqxmd.com/read/28262623/second-generation-magnesium-scaffold-magmaris-device-design-and-preclinical-evaluation-in-a-porcine-coronary-artery-model
#5
Ron Waksman, Philine Zumstein, Martin Pritsch, Eric Wittchow, Michael Haude, Capucine Lapointe-Corriveau, Guy Leclerc, Michael Joner
AIMS: The second-generation drug-eluting absorbable magnesium scaffold Magmaris, recently introduced for treatment of obstructive coronary atherosclerotic lesions, suggests a good safety profile, but preclinical assessment is important for predicting clinical performance. METHODS AND RESULTS: Ninety Magmaris scaffolds were implanted into non-diseased porcine and rabbit models. A bioresorbable vascular scaffold (Absorb) and the permanent drugeluting stent (Xience Xpedition) served as controls...
March 7, 2017: EuroIntervention
https://www.readbyqxmd.com/read/28124747/intermediate-analysis-of-magnesium-alloy-covered-stent-for-a-lateral-aneurysm-model-in-the-rabbit-common-carotid-artery
#6
Hong-Kai Cui, Fen-Bao Li, Ying-Chang Guo, Yong-Li Zhao, Rui-Fang Yan, Wu Wang, Yong-Dong Li, Yong-Li Wang, Guang-Yin Yuan
OBJECTIVE: To analyze the outcomes of a magnesium alloy covered stent (MACS) for a lateral aneurysm model in common carotid artery (CCA). METHODS: In 32 rabbits, a MACS (group A, n = 17) or a Willis covered stent (WCS; group B, n = 15) was inserted and the rabbits were sacrificed 1, 3, 6, or 12 months after stenting. Angiography and intravascular ultrasound (IVUS) were performed at 3, 6, and 12 months. Scanning electron microscopy was performed for six stents in each group at 1, 3, and 6 months, and histopathology and histomorphology were conducted at 3 (n = 4), 6 (n = 4), and 12 (n = 12) months...
January 26, 2017: European Radiology
https://www.readbyqxmd.com/read/28013101/ex-vivo-blood-vessel-bioreactor-for-analysis-of-the-biodegradation-of-magnesium-stent-models-with-and-without-vessel-wall-integration
#7
Juan Wang, Lumei Liu, Yifan Wu, Manfred F Maitz, Zhihong Wang, Youngmi Koo, Ansha Zhao, Jagannathan Sankar, Deling Kong, Nan Huang, Yeoheung Yun
Current in vitro models fail in predicting the degradation rate and mode of magnesium (Mg) stents in vivo. To overcome this, the microenvironment of the stent is simulated here in an ex vivo bioreactor with porcine aorta and circulating medium, and compared with standard static in vitro immersion and with in vivo rat aorta models. In ex vivo and in vivo conditions, pure Mg wires were exposed to the aortic lumen and inserted into the aortic wall to mimic early- and long-term implantation, respectively. Results showed that: 1) Degradation rates of Mg were similar for all the fluid diffusion conditions (in vitro static, aortic wall ex vivo and in vivo); however, Mg degradation under flow condition (i...
December 21, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27869217/magnesium-alloy-covered-stent-for-treatment-of-a-lateral-aneurysm-model-in-rabbit-common-carotid-artery-an-in-vivo-study
#8
Wu Wang, Yong-Li Wang, Mo Chen, Liang Chen, Jian Zhang, Yong-Dong Li, Ming-Hua Li, Guang-Yin Yuan
Magnesium alloy covered stents have rarely been used in the common carotid artery (CCA). We evaluated the long-term efficacy of magnesium alloy covered stents in a lateral aneurysm model in rabbit CCA. Magnesium alloy covered stents (group A, n = 7) or Willis covered stents (group B, n = 5) were inserted in 12 New Zealand White rabbits and they were followed up for 12 months. The long-term feasibility for aneurysm occlusion was studied through angiograms; the changes in vessel area and lumen area were assessed with IVUS...
November 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27785607/plastic-strains-during-stent-deployment-have-a-critical-influence-on-the-rate-of-corrosion-in-absorbable-magnesium-stents
#9
Emmet Galvin, Christy Cummins, Shoichiro Yoshihara, Bryan J Mac Donald, Caitríona Lally
Magnesium stents are a promising candidate in the emerging field of absorbable metallic stents (AMSs). In this study, the mechanical and corrosion performance of dog-bone specimens and a specific stent design of a magnesium alloy, WE43, are assessed experimentally in terms of their corrosion behaviour and mechanical integrity. It is shown that plastic strains that are induced in the struts of the stent during stent deployment have a critical influence in directing subsequent corrosion behaviour within the material...
October 26, 2016: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/27704201/technical-feasibility-and-tissue-reaction-after-silicone-covered-biodegradable-magnesium-stent-insertion-in-the-oesophagus-a-primary-study-in-vitro-and-in-vivo
#10
Yue-Qi Zhu, Laura Edmonds, Li-Ming Wei, Rei-La Zheng, Ruo-Yu Cheng, Wen-Guo Cui, Ying-Sheng Cheng
OBJECTIVES: Determine the feasibility of and tissue response to biodegradable magnesium-silicone stent insertion into the oesophagus of rabbits. METHODS: Mechanical compression-recovery and degradation behaviours of the stents were investigated in vitro. Thirty rabbits were randomly divided into a magnesium-silicone stent group (n = 15) that received stent insertion into the lower 1/3 of the oesophagus under fluoroscopic guidance and a control group (n = 15)...
October 4, 2016: European Radiology
https://www.readbyqxmd.com/read/27698548/bio-adaption-between-magnesium-alloy-stent-and-the-blood-vessel-a-review
#11
Jun Ma, Nan Zhao, Lexxus Betts, Donghui Zhu
Biodegradable magnesium (Mg) alloy stents are the most promising next generation of bio-absorbable stents. In this article, we summarized the progresses on the in vitro studies, animal testing and clinical trials of biodegradable Mg alloy stents in the past decades. These exciting findings led us to propose the importance of the concept "bio-adaption" between the Mg alloy stent and the local tissue microenvironment after implantation. The healing responses of stented blood vessel can be generally described in three overlapping phases: inflammation, granulation and remodeling...
September 2016: Journal of Materials Science & Technology
https://www.readbyqxmd.com/read/27612959/design-of-magnesium-alloys-with-controllable-degradation-for-biomedical-implants-from-bulk-to-surface
#12
Xia Li, Xiangmei Liu, Shuilin Wu, K W K Yeung, Yufeng Zheng, Paul K Chu
The combination of high strength, light weight, and natural biodegradability renders magnesium (Mg)-based alloys promising in orthopedic implants and cardiovascular stents. Being metallic materials, Mg and Mg alloys made for scaffolds provide the necessary mechanical support for tissue healing and cell growth in the early stage, while natural degradation and reabsorption by surrounding tissues in the later stage make an unnecessarily follow-up removal surgery. However, uncontrolled degradation may collapse the scaffolds resulting in premature implant failure, and there has been much research in controlling the degradation rates of Mg alloys...
November 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27612743/proteomic-profile-of-mouse-fibroblasts-exposed-to-pure-magnesium-extract
#13
Zhen Zhen, Bérengère Luthringer, Li Yang, Tingfei Xi, Yufeng Zheng, Frank Feyerabend, Regine Willumeit, Chen Lai, Zigang Ge
Magnesium and its alloys gain wide attention as degradable biomaterials. In order to reveal the molecular mechanism of the influence of biodegradable magnesium on cells, proteomics analysis was performed in this work. After mouse fibroblasts (L929) were cultured with or without Mg degradation products (Mg-extract) for 8, 24, and 48h, changes in protein expression profiles were obtained using isobaric tags for relative and absolute quantitation (iTRAQ) coupled two dimensional liquid chromatography-tandem mass spectrometry (2D LC MS/MS)...
December 1, 2016: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/27592325/freedom-solo-associated-thrombocytopaenia-is-valve-dependent-and-not-due-to-in-vitro-pseudothrombocytopaenia
#14
Olaf Stanger, Brigitta Gahl, Michael Grabherr, Richard Krausler, Sarah Longnus, Andreas Meinitzer, Janne Cadamuro
BACKGROUND: Use of the Freedom SOLO (FS) stentless aortic bioprosthesis is limited by a unique and as yet unexplained severe decrease in postoperative platelet count in the absence of FS-related excess bleeding or thromboembolism. We investigated whether anticoagulant-associated pseudothrombocytopaenia could explain this complication. METHODS: Thirty consecutive patients (mean age 75.4±7.7 years, 11 [36.7%] female) underwent elective aortic valve replacement (AVR) with either the stented bovine Mitroflow (MF, n=18) or the stentless bovine FS (n=12) aortic valve bioprostheses...
August 16, 2016: Heart, Lung & Circulation
https://www.readbyqxmd.com/read/27331417/enhanced-in-vitro-and-in-vivo-performance-of-mg-zn-y-nd-alloy-achieved-with-aptes-pretreatment-for-drug-eluting-vascular-stent-application
#15
Jing Liu, Bo Zheng, Pei Wang, Xingang Wang, Bin Zhang, Qiuping Shi, Tingfei Xi, Ming Chen, Shaokang Guan
Bioabsorbable magnesium alloys are becoming prominent as temporary functional implants, as they avoid the risks generated by permanent metallic implants such as persistent inflammation and late restenosis. Nevertheless, the overfast corrosion of Mg alloys under physiological conditions hinders their wider application as medical implant materials. Here we investigate a simple one-step process to introduce a cross-linked 3-amino-propyltrimethoxysilane (APTES) silane physical barrier layer on the surface of Mg-Zn-Y-Nd alloys prior to electrostatic spraying with rapamycin-eluting poly(lactic-co-glycolic acid) (PLGA) layer...
July 20, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27266902/in-vitro-performance-investigation-of-bioresorbable-scaffolds-standard-tests-for-vascular-stents-and-beyond
#16
COMPARATIVE STUDY
Wolfram Schmidt, Peter Behrens, Christoph Brandt-Wunderlich, Stefan Siewert, Niels Grabow, Klaus-Peter Schmitz
BACKGROUND/PURPOSE: Biodegradable polymers are the main materials for coronary scaffolds. Magnesium has been investigated as a potential alternative and was successfully tested in human clinical trials. However, it is still challenging to achieve mechanical parameters comparative to permanent bare metal (BMS) and drug-eluting stents (DES). As such, in vitro tests are required to assess mechanical parameters correlated to the safety and efficacy of the device. METHODS/MATERIALS: In vitro bench tests evaluate scaffold profiles, length, deliverability, expansion behavior including acute elastic and time-dependent recoil, bending stiffness and radial strength...
September 2016: Cardiovascular Revascularization Medicine: Including Molecular Interventions
https://www.readbyqxmd.com/read/27094868/biodegradable-metals-for-cardiovascular-stents-from-clinical-concerns-to-recent-zn-alloys
#17
Patrick K Bowen, Emily R Shearier, Shan Zhao, Roger J Guillory, Feng Zhao, Jeremy Goldman, Jaroslaw W Drelich
Metallic stents are used to promote revascularization and maintain patency of plaqued or damaged arteries following balloon angioplasty. To mitigate the long-term side effects associated with corrosion-resistant stents (i.e., chronic inflammation and late stage thrombosis), a new generation of so-called "bioabsorbable" stents is currently being developed. The bioabsorbable coronary stents will corrode and be absorbed by the artery after completing their task as vascular scaffolding. Research spanning the last two decades has focused on biodegradable polymeric, iron-based, and magnesium-based stent materials...
May 2016: Advanced Healthcare Materials
https://www.readbyqxmd.com/read/27085049/biodegradable-elastomeric-coatings-with-controlled-anti-proliferative-agent-release-for-magnesium-based-cardiovascular-stents
#18
Xinzhu Gu, Zhongwei Mao, Sang-Ho Ye, Youngmi Koo, Yeoheung Yun, Tarannum R Tiasha, Vesselin Shanov, William R Wagner
Vascular stent design continues to evolve to further improve the efficacy and minimize the risks associated with these devices. Drug-eluting coatings have been widely adopted and, more recently, biodegradable stents have been the focus of extensive evaluation. In this report, biodegradable elastomeric polyurethanes were synthesized and applied as drug-eluting coatings for a relatively new class of degradable vascular stents based on Mg. The dynamic degradation behavior, hemocompatibility and drug release were investigated for poly(carbonate urethane) urea (PCUU) and poly(ester urethane) urea (PEUU) coated magnesium alloy (AZ31) stents...
August 1, 2016: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/27062241/novel-zn-based-alloys-for-biodegradable-stent-applications-design-development-and-in-vitro-degradation
#19
E Mostaed, M Sikora-Jasinska, A Mostaed, S Loffredo, A G Demir, B Previtali, D Mantovani, R Beanland, M Vedani
The search for a degradable metal simultaneously showing mechanical properties equal or higher to that of stainless steel and uniform degradation is still an open challenge. Several magnesium-based alloys have been studied, but their degradation rate has proved to be too fast and rarely homogeneous. Fe-based alloys show appropriate mechanical properties but very low degradation rate. In the present work, four novel Zn-Mg and two Zn-Al binary alloys were investigated as potential biodegradable materials for stent applications...
July 2016: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/27047673/opportunities-and-challenges-for-the-biodegradable-magnesium-alloys-as-next-generation-biomaterials
#20
REVIEW
Wenjiang Ding
In recent years, biodegradable magnesium alloys emerge as a new class of biomaterials for tissue engineering and medical devices. Deploying biodegradable magnesium-based materials not only avoids a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials are often subjected to an uncontrolled and fast degradation, acute toxic responses and rapid structural failure presumably due to a localized, too rapid corrosion process...
June 2016: Regenerative Biomaterials
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