6,963 publications from this institution
Cumulative evidence has demonstrated that transcatheter aortic valve implantation (TAVI) constitutes an effective treatment option for patients with severe symptomatic aortic stenosis and a high operative risk. New valve designs and TAVI-enabling devices have simplified the procedure, reduced the risk of complications, and broadened the applications of this treatment. The global adoption of TAVI allows us to appreciate the advantages, potentialities and caveats of the technology, identify patients who would benefit from TAVI and stratify more accurately the risk of complications. The focus of this article is to discuss the advances in this field, present the current evidence, and highlight the developments and strategies proposed to address the limitations of TAVI treatment.
A 65-year old patient was referred to our institution for a diagnostic catheterization. 23 years before, a direct surgical myocardial procedure using the Vineberg technique was performed. Currently, the angiogram shows patent left and right internal mammary arteries implanted directly into the myocardium and connecting with the native circulation through collaterals. As the native coronary artery tree shows very severe three vessel disease, it is hypothesized that the major contribution of myocardial perfusion comes from the implanted vessels. This is the first case to show a long-term success of the Vineberg operation, with persistence of myocardial perfusion through newly formed vasculature.
No abstract is provided for this article.
Geometric imperfections have an important influence on the buckling response of structural components. This paper describes an experimental technique for determining imperfections in long (5.7 m) structural members using a series of overlapping measurements. Measurements were performed on 31 austenitic stainless steel sections formed from three different production routes: hot-rolling, cold-rolling and press-braking. Spectral analysis was carried out on the imperfections to obtain information on the periodic nature of the profiles. Two series were used to model the profile firstly the orthogonal cosine and sine functions in a classic Fourier transform and secondly a half sine series. Results were compared to the relevant tolerance standards. Simple predictive tools for both local and global imperfections have been developed to enable representative geometric imperfections to be incorporated into numerical models and design methods.
Abstract Experiments were designed to investigate whether leukotriene (LTB4) receptors can couple directly to phospholipase A2 (PLA2) in guinea pig eosinophils and the role of endogenous arachidonic acid (AA) in LTB4-induced activation of the NADPH oxidase. LTB4 (EC50 ∼ 16 nM) and AA (EC50 ∼ 6 μM) generated hydrogen peroxide (H2O2) in a concentration-dependent manner and at an equivalent maximum rate (5–6 nmol/min/106 cells). LTB4 stimulated PLA2 over a similar concentration range that activated the NADPH oxidase, although kinetic studies revealed that the release of [3H]AA (t1/2 ∼ 2 s) preceded H2O2 generation (t1/2 > 30 s). Pretreatment of eosinophils with pertussis toxin abolished the increase in inositol(1,4,5)trisphosphate mass, [Ca2+]c, [3H]AA release, and H2O2 generation evoked by LTB4. Qualitatively identical results were obtained in eosinophils in which phospholipase C (PLC) was desensitized by 4β-phorbol 12,13-dibutyrate with the exception that [3H]AA release was largely unaffected. Additional studies performed with the protein kinase C inhibitor, Ro 31-8220, and under conditions in which Ca2+ mobilization was abolished, provided further evidence that LTB4 released [3H]AA independently of signal molecules derived from the hydrolysis of phosphatidylinositol(4,5)bisphosphate by PLC. Pretreatment of eosinophils with the PLA2 inhibitor, mepacrine, abolished LTB4-induced [3H]AA release at a concentration that inhibited H2O2 by only 36%. Collectively, the results of this study indicate that agonism of LTB4 receptors on guinea pig eosinophils mobilizes AA by a mechanism that does not involve the activation of PLC. In addition, although LTB4 effectively stimulated PLA2, a central role for AA in the activation of the NADPH oxidase was excluded.