Degradation of GRK2 and AKT is an early and detrimental event in myocardial ischemia/reperfusion

GRK2; AKT; Ischemia-reperfusionGRK2; AKT; Isquemia-reperfusiónGRK2; AKT; Isquèmia-reperfusióBackground: Identification of signaling pathways altered at early stages after cardiac ischemia/reperfusion (I/R) is crucial to develop timely therapies aimed at reducing I/R injury. The expression of G protein-coupled receptor kinase 2 (GRK2), a key signaling hub, is up-regulated in the long-term in patients and in experimental models of heart failure. However, whether GRK2 levels change at early time points following myocardial I/R and its functional impact during this period remain to be established. Methods: We have investigated the temporal changes of GRK2 expression and their potential relationships with the cardioprotective AKT pathway in isolated rat hearts and porcine preclinical models of I/R. Findings: Contrary to the maladaptive up-regulation of GRK2 reported at later times after myocardial infarction, successive GRK2 phosphorylation at specific sites during ischemia and early reperfusion elicits GRK2 degradation by the proteasome and calpains, respectively, thus keeping GRK2 levels low during early I/R in rat hearts. Concurrently, I/R promotes decay of the prolyl-isomerase Pin1, a positive regulator of AKT stability, and a marked loss of total AKT protein, resulting in an overall decreased activity of this pro-survival pathway. A similar pattern of concomitant down-modulation of GRK2/AKT/Pin1 protein levels in early I/R was observed in pig hearts. Calpain and proteasome inhibition prevents GRK2/Pin1/AKT degradation, restores bulk AKT pathway activity and attenuates myocardial I/R injury in isolated rat hearts. Interpretation: Preventing transient degradation of GRK2 and AKT during early I/R might improve the potential of endogenous cardioprotection mechanisms and of conditioning strategies.Our laboratories are supported by Instituto de Salud Carlos III, Spain (grant PI-16/00232; RETICS-RIC-RD12/0042/0021 to DGD, co-funded with European Regional Development Fund-FEDER contribution, and grants PI14-00435 and PI17-00576 to PP), by Ministerio de Economía; Industria y Competitividad (MINECO) of Spain (grant SAF2017-84125-R to F.M.); by CIBERCV-Instituto de Salud Carlos III, Spain (grant CB16/11/00479 to DGD and CB16/11/00278 to F.M, co-funded with European Regional Development Fund-FEDER contribution), and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to F.M. We also acknowledge institutional support to the CBMSO from Fundación Ramón Areces. This work is dedicated to the memory of our colleague and friend Dr. David García-Dorado, who sadly passed away during the final revision stage of this manuscript

Ischemia/reperfusion increases the oxidized state of specific cys residues in proteins from mitochondrial supopulation from rat miocardium that are protected by ischemia preconditioning

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El precondicionamiento isquémico produce cambios en las proteínas de las fosforilación oxidativa y atenúa el daño oxidativo durante la isquemia-reperfusión por mecanismos independientes de la señalización citosólica

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On the dynamics of valley times and its application to bulk-transfer scheduling

Periods of low load have been used for the scheduling of non-interactive tasks since the early stages of computing. Nowadays, the scheduling of bulk transfers—i.e., large-volume transfers without precise timing, such as database distribution, resources replication or backups—stands out among such tasks, given its direct effect on both the performance and billing of networks. Through visual inspection of traffic-demand curves of diverse points of presence (PoP), either a network, link, Internet service provider or Internet exchange point, it becomes apparent that low-use periods of bandwidth demands occur at early morning, showing a noticeable convex shape. Such observation led us to study and model the time when such demands reach their minimum, on what we have named valley time of a PoP, as an approximation to the ideal moment to carry out bulk transfers. After studying and modeling single-PoP scenarios both temporally and spatially seeking homogeneity in the phenomenon, as well as its extension to multi-PoP scenarios or paths—a meta-PoP constructed as the aggregation of several single PoPs—, we propose a final predictor system for the valley time. This tool works as an oracle for scheduling bulk transfers, with different versions according to time scales and the desired trade-off between precision and complexity. The evaluation of the system, named VTP, has proven its usefulness with errors below an hour on estimating the occurrence of valley times, as well as errors around 10% in terms of bandwidth between the prediction and actual valley trafficThis work has been partially supported by the European Commission under the project H2020 METRO-HAUL (Project ID: 761727

Bin-CE: A comprehensive web application to decide upon the best set of outcomes to be combined in a binary composite endpoint

The estimation of the Sample Size Requirement (SSR) when using a binary composite endpoint (i.e. two or more outcomes combined in a unique primary endpoint) is not trivial. Besides information about the rate of events for each outcome, information about the strength of association between the outcomes is crucial, since it can determine an increase or decrease of the SSR. Specifically, the greater the strength of association between outcomes the higher the SSR. We present Bin-CE, a free tool to assist clinicians for computing the SSR for binary composite endpoints. In a first step, the user enters a set of candidate outcomes, the assumed rate of events for each outcome and the assumed effect of therapy on each outcome. Since the strength of the association between outcomes is usually unknown, a semi-parametric approach linking the a priori clinical knowledge of the potential degree of association between outcomes with the exact values of these parameters was programmed with Bin-CE. Bin-CE works with a recursive algorithm to choose the best combination of outcomes that minimizes the SSR. In addition, Bin-CE computes the sample size using different algorithms and shows different figures plotting the magnitude of the sample size reduction, and the effect of different combinations of outcomes on the rate of the primary endpoint. Finally, Bin-CE is programmed to perform sensitivity analyses. This manuscript presents the mathematic bases and introduces the reader to the use of Bin-CE using a real example

Role of alkali-cyano group interaction in g-C3N4 based catalysts for hydrogen photo-production

Carbon nitride based materials incorporating K and Na alkali ions were used as support(s) to deposit platinum. The systems were tested in the photo-production of hydrogen using methanol as a sacrificial molecule. Tests under UV and sunlight-type illumination conditions showed an important promoting effect of the alkali ions irrespective of the illumination source characteristics. The measurement of the quantum efficiency was used to quantitatively assess the performance of the catalysts. Outstanding results were obtained, particularly under sunlight illumination. A complete characterization study of the materials was carried out to establish a structure-activity link. This link correlates catalytic activity with the capture of charge carrier species by surface cyano groups directly associated with the presence of alkali ions at the carbon nitride componen

Ischemic Postconditioning Reduces Reperfusion arrhythmias by Adenosine Receptors and Protein Kinase C Activation but Is Independent of KATP Channels or Connexin 43

Ischemic postconditioning (IPoC) reduces reperfusion arrhythmias but the antiarrhythmic mechanisms remain unknown. The aim of this study was to analyze IPoC electrophysiological effects and the role played by adenosine A1, A2A and A3 receptors, protein kinase C, ATP-dependent potassium (KATP) channels, and connexin 43. IPoC reduced reperfusion arrhythmias (mainly sustained ventricular fibrillation) in isolated rat hearts, an effect associated with a transient delay in epicardial electrical activation, and with action potential shortening. Electrical impedance measurements and Lucifer-Yellow diffusion assays agreed with such activation delay. However, this delay persisted during IPoC in isolated mouse hearts in which connexin 43 was replaced by connexin 32 and in mice with conditional deletion of connexin 43. Adenosine A1, A2A and A3 receptor blockade antagonized the antiarrhythmic effect of IPoC and the associated action potential shortening, whereas exogenous adenosine reduced reperfusion arrhythmias and shortened action potential duration. Protein kinase C inhibition by chelerythrine abolished the protective effect of IPoC but did not modify the effects on action potential duration. On the other hand, glibenclamide, a KATP inhibitor, antagonized the action potential shortening but did not interfere with the antiarrhythmic effect. The antiarrhythmic mechanisms of IPoC involve adenosine receptor activation and are associated with action potential shortening. However, this action potential shortening is not essential for protection, as it persisted during protein kinase C inhibition, a maneuver that abolished IPoC protection. Furthermore, glibenclamide induced the opposite effects. In addition, IPoC delays electrical activation and electrical impedance recovery during reperfusion, but these effects are independent of connexin 43.Fil: Diez, Emiliano Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Sánchez, Jose Antonio. Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares; España. Universidad Autonoma de Barcelona. Hospital Vall D' Hebron. Instituto de Investigación Vall D'hebron. Serv.de Cardiología,laboratorio de Cardiología Experimenta; EspañaFil: Prado, Natalia Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Ponce Zumino, Amira Zulma. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: García-Dorado, David. Universidad Autonoma de Barcelona. Hospital Vall D' Hebron. Instituto de Investigación Vall D'hebron. Serv.de Cardiología,laboratorio de Cardiología Experimenta; España. Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares; EspañaFil: Miatello, Roberto Miguel. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Rodríguez-Sinovas, Antonio. Centro de Investigación Biomédica en Red sobre Enfermedades Cardiovasculares; España. Universidad Autonoma de Barcelona. Hospital Vall D' Hebron. Instituto de Investigación Vall D'hebron. Serv.de Cardiología,laboratorio de Cardiología Experimenta; Españ

Ischemic preconditioning and ischaemia-reperfusion: key role of connexin43 and mitochondrial complexes

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