170,214 research outputs found
beta 1-Adrenergic receptor polymorphisms are correlated with exercise capacity in patients with idiopathic dilated cardiomyopathy
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Prevalence, timing, and haemodynamic correlates of prodromes in patients with vasovagal syncope induced by head-up tilt test
No full textAimsTo evaluate the prevalence, timing, and haemodynamic characteristics of prodromal symptoms in patients experiencing vasovagal syncope (VVS) during a head-up tilt test (HUT) potentiated with nitroglycerin, and their relationships with those reported before spontaneous episodes.Methods and resultsSymptoms preceding HUT-induced syncope were recorded, together with heart rate (HR) and arterial blood pressure (BP) values, in 149 otherwise healthy and drug-free subjects with recurrent unexplained syncope. Head-up tilt test significantly increase the number of patients capable of recognizing the premonitory symptoms of VVS than before spontaneous episodes (96 vs. 79; P < 0.001). The nine most frequent symptoms were stratified into three groups on the basis of their characteristics: headache, hot flashes, and palpitations occurred more than 3 min before syncope, with a very slight reduction in BP; nausea, asthenia, diaphoresis, vertigo, and epigastric discomfort preceded syncope by 1-3 min and were associated with a slight reduction in BP; and blurred vision appeared the last minute before syncope and was characterized by the lowest BP and HR values.ConclusionIn comparison with spontaneous syncopal episodes, HUT allows the more frequent recognition of prodromes also providing useful information in terms of timing and haemodynamic characteristics of symptoms that may allow more tailored patient counselling
Uno standard di accessibilità relazionale delle organizzazioni. Spunti di riflessione dalla fruizione del patrimonio naturale
No full textObiettivi. Obiettivo del lavoro è proporre una norma volontaria finalizzata a migliorare l’accessibilità relazionale delle organizzazioni e i rapporti con l’utenza esterna. L’aggettivazione posta al termine di accessibilità prende le distanze da concetti fisici o virtuali, richiamando l’attenzione sulla relazionalità.
Metodologia. Inquadrato il concetto di accessibilità relazionale, si definiscono l’approccio e lo schema logico della norma attingendo ad approcci teorici manageriali e multidisciplinari. Da un punto di vista empirico, spunti utili sono stati tratti dall’ambito ambientale secondo una duplice prospettiva: dalle esperienze in tema, quindi da una prospettiva d’offerta; dal punto di vista degli utenti, per cogliere la prospettiva della domanda. Mettendo a sistema i contributi teorici e le risultanze empiriche, si definiscono lo schema logico ed alcune linee guida utili a migliorare l’accessibilità relazionale di differenti contesti organizzativi e settoriali.
Risultati. La norma, nel perseguire il fine dell’accessibilità relazionale, può consentire alle organizzazioni di accrescere il loro valore sociale ed economico - in termini di vantaggi competitivi, immagine, rapporti con i soggetti esterni.
Limiti della ricerca. Lo schema proposto presenta limiti connessi all’applicazione della norma che, definita a partire da una specifica realtà di utenza (minori) e di organizzazione (un parco naturale), è in corso di sperimentazione in altri contesti organizzativi al fine di verificarne la fungibilità.
Implicazioni pratiche. La sua applicazione nelle diverse organizzazioni collegate alla gestione del patrimonio culturale potrebbe intensificare l’adozione di approcci manageriali.
Originalità del lavoro. Il lavoro è originale nella metodologia e nello strumento, non essendovi a conoscenza degli Autori proposte simili.Objectives. This work aims to propose a standard on relationship accessibility of organizations, oriented to reduce drawbacks and improve the relationship with external users. The term used is not meant as physical or virtual accessibility; on the contrary, it refers to relationship accessibility.
Methodology. After having defined a relationship concept, the approach and logical frame of standard are defined based on managerial literature. Useful ideas have come out from the environmental field according to a double perspective: from the experience realized on the topic, therefore from a supply perspective; from the users point of view, to catch a demand perspective. Putting together theoretical insights and empirical results, the logical frame and some useful guidelines to improve the accessibility of different organizational contexts are defined.
Findings. The standard, to pursue the aim of relationship accessibility, could allow the organizations to increase the social and economic value - e.g. in terms of competitive advantages, image, and relationships with the different external users-.
Research limits. The scheme proposed shows limits related to the application of the standard that, defined from a specific target of users (minors) and organization (a natural park), is being tested in other organizational contexts in order to verify its fungibility.
Pratical implications. Its application in the organizational contexts connected to the cultural heritage world could intensify the adoption of managerial approaches.
Originality of the study. The work is original in its methodology and tool, since the Authors have no knowledge of standard on the issue
A structure-based proposal for the catalytic mechanism of the bacterial acid phosphatase AphA belonging to the DDDD superfamily of phosphohydrolases
No full textThe Escherichia coli gene aphA codes for a periplasmic acid phosphatase called AphA, belonging to class B bacterial phosphatases, which is part of the DDDD superfamily of phosphohydrolases. After our first report about its crystal structure, we have started a series of crystallographic studies aimed at understanding of the catalytic mechanism of the enzyme. Here, we report three crystal structures of the AphA enzyme in complex with the hydrolysis products of nucleoside monophosphate substrates and a fourth with a proposed intermediate analogue that appears to be covalently bound to the enzyme. Comparison with the native enzyme structure and with the available X-ray structures of different phosphatases provides clues about the enzyme chemistry and allows us to propose a catalytic mechanism for AphA, and to discuss it with respect to the mechanism of other bacterial and human phosphatases. (c) 2005 Elsevier Ltd. All rights reserved
Shortened head-up tilting test guided by systolic pressure reductions in neurocardiogenic syncope
No full textBACKGROUND: Asymptomatic reductions in arterial pressure have been reported to occur before the onset of tilt-induced syncope. We investigated the predictive value of these reductions for a positive tilt result.
METHODS AND RESULTS: In a first study, 238 consecutive healthy subjects with unexplained syncope underwent a passive tilt table test. Finger systolic arterial pressure (SAP) recordings made it possible to calculate how many of the beat-to-beat SAP values during the first 15 minutes of tilt were lower than the lowest value recorded at baseline. Neurocardiogenic syncope was diagnosed in 73 subjects; 28 fainted after 15 minutes of tilt and experienced more pressure reductions than did the subjects with a negative test (328+/-400 versus 119+/-284; P<0.01). More than 14 SAP reductions during the first 15 minutes of tilt allowed us to predict a positive test with 93% sensitivity, 58% specificity, and positive and negative predictive values of 28% and 98%, respectively. In a second prospective study (80 consecutive subjects), the online analysis of this criterion by visually inspecting a Finapres monitor showed 80% sensitivity, 85% specificity, and positive and negative predictive values of 57% and 94%.
CONCLUSIONS: In healthy subjects with unexplained syncope, the evaluation of SAP reductions during the first 15 minutes of tilt is a marker of systolic pressure instability preceding syncope and constitutes a simple and good predictor of tilt outcome that could be used to guide test duration
The first structure of a bacterial class B acid phosphatase reveals further structural heterogeneity among phosphatases of the haloacid dehalogenase fold
No full textAphA is a periplasmic acid phosphatase of Escherichia coli belonging to class B bacterial phosphatases, which is part of the DDDD superfamily of phosphohydrolases. The crystal structure of AphA has been determined at 2.2 Angstrom and its resolution extended to 1.7 Angstrom on an AuCl3 derivative. This represents the first crystal structure of a class B bacterial phosphatase. Despite the lack of sequence homology, the AphA structure reveals a haloacid dehalogenase-like fold. This finding suggests that this fold could be conserved among members of the DDDD superfamily of phosphohydrolases. The active enzyme is a homotetramer built by using an extended N-terminal arm intertwining the four monomers. The active site of the native enzyme, as prepared, hosts a magnesium ion, which can be replaced by other metal ions. The structure explains the nonspecific behaviour of AphA towards substrates, while a structure-based alignment with other phosphatases provides clues about the catalytic mechanism. (C) 2003 Elsevier Ltd. All rights reserved
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