A multi-method approach towards understanding the pathophysiology of aortic dissections – the complementary role of in-silico, in-vitro and in-vivo information

Management and follow-up of chronic aortic dissections continues to be a clinical challenge due to progressive aortic dilatation. To predict dilatation, guidelines suggest follow-up of the aortic diameter. However, dilatation is triggered by haemodynamic parameters (pressure and wall shear stresses (WSS)), and geometry of false (FL) and true lumen (TL). We aimed at a better understanding of TL and FL haemodynamics by performing in-silico (CFD) and in-vitro studies on an idealized dissected aorta and compared this to a typical patient. We observed an increase in diastolic pressure and wall stress in the FL and the presence of diastolic retrograde flow. The inflow jet increased WSS at the proximal FL while a large variability in WSS was induced distally, all being risk factors for wall weakening. In-silico, in-vitro and in-vivo findings were very similar and complementary, showing that their combination can help in a more integrated and extensive assessment of aortic dissections, improving understanding of the haemodynamic conditions and related clinical evolution

Ischemic postconditioning reduces reperfusion arrhythmias by adenosine receptors and protein kinase C activation but is independent of KATP channels or connexin 43

Funding: This study was supported by Secretaría de Investigación, Internacionales y Posgrado, Universidad Nacional de Cuyo (06/J505) and by the Spanish, Ministerio de Ciencia, Innovación y Universidades, Instituto de Salud Carlos III (CIBERCV), cofinanced by the European Regional Development Fund (ERDF-FEDER, a way to build Europe), and by Fundació La Marató de TV3 (n◦. 201536-10). Antonio Rodríguez-Sinovas has a consolidated Miguel Servet contract. Jose A. Sánchez was supported by the International Research Training Group 1566 on Protecting the Heart from Ischemia (PROMISE).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 A, A and A receptors, protein kinase C, ATP-dependent potassium (K) 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 A, A and A 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 K 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

Condicionantes pronósticos del ictus isquémico: utilidad de los biomarcadores sanguíneos en su predicción

Premi Extraordinari de Doctorat concedit pels programes de doctorat de la UAB per curs acadèmic 2017-2018El ictus es una de las principales causas de mortalidad y discapacidad en nuestro medio. El pronóstico del ictus depende en gran parte de factores basales no modificables como la edad o la gravedad inicial del mismo, pero también de circunstancias que ocurren durante la historia natural del mismo y conllevan un mal desenlace. En la presente tesis doctoral nos focalizamos en éstas últimas, las complicaciones del ictus. Así, nuestros objetivos en el presente trabajo son, en primer lugar, establecer cuáles de las complicaciones del ictus presentan un mayor impacto sobre el pronóstico del mismo en nuestro medio. En segundo lugar, evaluar en qué indicaciones el uso de biomarcadores sanguíneos constituye una necesidad asistencial. En tercer lugar, evaluar la asociación de los biomarcadores sanguíneos al pronóstico del ictus y las complicaciones del mismo en la literatura y, finalmente testar el valor predictivo de biomarcadores candidatos para las indicaciones identificadas en los puntos anteriores. Para esto hemos realizado un análisis del registro de ictus de la Sociedad Española de Neurología (RENISEN), en el que identificamos que el edema cerebral con hipertensión intracraneal y las infecciones respiratorias son las complicaciones con un mayor impacto sobre la mortalidad del ictus, encontrándose en un segundo escalón las complicaciones cardiológicas. Un interesante hallazgo de este análisis es que el impacto de esas complicaciones depende de la gravedad del ictus. Por otra parte, hemos realizado una encuesta a neurólogos vasculares europeos en los que vemos que la indicación más demandada para el uso de biomarcadores en el ictus es el manejo de las terapias de reperfusión. A través de revisiones sistemáticas y metaanálisis, hemos detectado que el uso de biomarcadores para el manejo de las complicaciones del ictus ha sido poco estudiado. De entre los marcadores metaanalizados, la proteína C-reactiva constituye un candidato para el manejo de las infecciones asociadas al ictus. Respecto a los estudios experimentales, hemos identificado dos candidatos nuevos para guiar las terapias de reperfusión, la proteasa activadora del factor VII (FSAP) y la proteasa de clivaje del factor de Von Willebrand (ADAMTS13), relacionadas con la recanalización arterial, y hemos descrito la utilidad de la medición de troponina I ultrasensible en la fase aguda del ictus, identificando a los pacientes con mayor riesgo de desarrollar complicaciones cardiológicas. Si nuestros resultados se confirmasen en estudios prospectivos, podríamos llegar a implementar el uso de biomarcadores sanguíneos en pacientes con ictus isquémico para el manejo de las complicaciones del mismo.Stroke represents one of the main causes of mortality and disability. Stroke outcome depends mainly on baseline, non-modifiable factors, such as age or stroke severity, but also on several conditions that may occur across the natural history of stroke and leads to a poor outcome. In the present doctoral thesis we focus on these conditions, namely post-stroke complications. Therefore, our objectives in the present project are: first, to assess which post-stroke complications have the highest impact on stroke prognosis; second, to evaluate in which indications the use of blood biomarkers is more demanded by physicians; third, to evaluate across the literature whether the association between blood biomarkers and stroke outcome and complications has been assessed; and fourth, to test the predictive value of some candidates for the previously identified indications. To assess these objectives, we performed a comprehensive analysis of the stroke registry of the Spanish Neurological Society (RENISEN), finding that brain edema with increased intracranial pressure and respiratory tract infections were the complications with the highest impact on in-hospital mortality, followed by cardiologic complications in a second step. An interesting finding of the analysis is that the impact of these complications depends on stroke severity. Moreover, we performed a survey across European stroke neurologists, finding that the indication in which the use of biomarkers is more requested is the management of reperfusion therapies. By applying systematic reviews and meta-analysis, we have found that the use of biomarkers for the management of post-stroke complications has been poorly studied. From the meta-analyzed biomarkers, C-reactive protein appears as a surrogate biomarker for the management of post-stroke infections. Regarding experimental studies, factor seven activating protease (FSAP) and ADAMTS13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13), both associated with arterial recanalization, have emerged as candidates to guide reperfusion therapies. Moreover, we have described a role for high-sensitive troponin-I determination in acute stroke, in identifying those patients at the highest risk of suffering cardiologic complications. If our results are confirmed in future prospective studies evaluating the prognostic implications of the use of these biomarkers, such biomarkers could be translated into clinical practice for the management of post-stroke complications

Accelerated inbreeding depression suggests synergistic epistasis for deleterious mutations in Drosophila melanogaster

Epistasis may have important consequences for a number of issues in quantitative genetics and evolutionary biology. In particular, synergistic epistasis for deleterious alleles is relevant to the mutation load paradox and the evolution of sex and recombination. Some studies have shown evidence of synergistic epistasis for spontaneous or induced deleterious mutations appearing in mutation-accumulation experiments. However, many newly arising mutations may not actually be segregating in natural populations because of the erasing action of natural selection. A demonstration of synergistic epistasis for naturally segregating alleles can be achieved by means of inbreeding depression studies, as deleterious recessive allelic effects are exposed in inbred lines. Nevertheless, evidence of epistasis from these studies is scarce and controversial. In this paper, we report the results of two independent inbreeding experiments carried out with two different populations of Drosophila melanogaster. The results show a consistent accelerated inbreeding depression for fitness, suggesting synergistic epistasis among deleterious alleles. We also performed computer simulations assuming different possible models of epistasis and mutational parameters for fitness, finding some of them to be compatible with the results observed. Our results suggest that synergistic epistasis for deleterious mutations not only occurs among newly arisen spontaneous or induced mutations, but also among segregating alleles in natural populationsWe acknowledge the support by Uvigo Marine Research Centre funded by the “Excellence in Research (INUGA)” Programme from the Regional Council of Culture, Education and Universities, with co-funding from the European Union through the ERDF Operational Programme Galicia 2014-2020. This work was funded by Agencia Estatal de Investigación (AEI) (CGL2016-75904-C2-1-P), Xunta de Galicia (ED431C 2016-037) and Fondos Feder: “Unha maneira de facer Europa.” SD was founded by a predoctoral (FPI) grant from Ministerio de Economía y Competitividad, SpainS

Nasopharyngeal Colonization and Invasive Disease Are Enhanced by the Cell Wall Hydrolases LytB and LytC of Streptococcus pneumoniae

Background: Streptococcus pneumoniae is a common colonizer of the human nasopharynx and one of the major pathogens causing invasive disease worldwide. Dissection of the molecular pathways responsible for colonization, invasion, and evasion of the immune system will provide new targets for antimicrobial or vaccine therapies for this common pathogen. Methodology/Principal Findings: We have constructed mutants lacking the pneumococcal cell wall hydrolases (CWHs) LytB and LytC to investigate the role of these proteins in different phases of the pneumococcal pathogenesis. Our results show that LytB and LytC are involved in the attachment of S. pneumoniae to human nasopharyngeal cells both in vitro and in vivo. The interaction of both proteins with phagocytic cells demonstrated that LytB and LytC act in concert avoiding pneumococcal phagocytosis mediated by neutrophils and alveolar macrophages. Furthermore, C3b deposition was increased on the lytC mutant confirming that LytC is involved in complement evasion. As a result, the lytC mutant showed a reduced ability to successfully cause pneumococcal pneumonia and sepsis. Bacterial mutants lacking both LytB and LytC showed a dramatically impaired attachment to nasopharyngeal cells as well as a marked degree of attenuation in a mouse model of colonization. In addition, C3b deposition and phagocytosis was more efficient for the double lytB lytC mutant and its virulence was greatly impaired in both systemic and pulmonary models of infection. Conclusions/Significance: This study confirms that the CWHs LytB and LytC of S. pneumoniae are essential virulence factor

Sex and gender differences in acute stroke care: metrics, access to treatment and outcome. A territorial analysis of the Stroke Code System of Catalonia

Introduction: Previous studies have reported differences in the management and outcome of women stroke patients in comparison with men. We aim to analyze sex and gender differences in the medical assistance, access to treatment and outcome of acute stroke patients in Catalonia. Patients and methods: Data were obtained from a prospective population-based registry of stroke code activations in Catalonia (CICAT) from January/2016 to December/2019. The registry includes demographic data, stroke severity, stroke subtype, reperfusion therapy, and time workflow. Centralized clinical outcome at 90 days was assessed in patients receiving reperfusion therapy. Results: A total of 23,371 stroke code activations were registered (54% men, 46% women). No differences in prehospital time metrics were observed. Women more frequently had a final diagnosis of stroke mimic, were older and had a previous worse functional situation. Among ischemic stroke patients, women had higher stroke severity and more frequently presented proximal large vessel occlusion. Women received more frequently reperfusion therapy (48.2% vs 43.1%, p < 0.001). Women tended to present a worse outcome at 90 days, especially for the group receiving only IVT (good outcome 56.7% vs 63.8%; p < 0.001), but not for the group of patients treated with IVT + MT or MT alone, although sex was not independently associated with clinical outcome in logistic regression analysis (OR 1.07; 95% CI, 0.94–1.23; p = 0.27) nor in the analysis after matching using the propensity score (OR 1.09; 95% CI, 0.97–1.22). Discussion and conclusion: We found some differences by sex in that acute stroke was more frequent in older women and the stroke severity was higher. We found no differences in medical assistance times, access to reperfusion treatment and early complications. Worse clinical outcome at 90 days in women was conditioned by stroke severity and older age, but not by sex itself

Effect of COMBinAtion therapy with remote ischemic conditioning and exenatide on the Myocardial Infarct size: a two-by-two factorial randomized trial (COMBAT-MI)

Remote ischemic conditioning (RIC) and the GLP-1 analog exenatide activate different cardioprotective pathways and may have additive effects on infarct size (IS). Here, we aimed to assess the efficacy of RIC as compared with sham procedure, and of exenatide, as compared with placebo, and the interaction between both, to reduce IS in humans. We designed a two-by-two factorial, randomized controlled, blinded, multicenter, clinical trial. Patients with ST-segment elevation myocardial infarction receiving primary percutaneous coronary intervention (PPCI) within 6 h of symptoms were randomized to RIC or sham procedure and exenatide or matching placebo. The primary outcome was IS measured by late gadolinium enhancement in cardiac magnetic resonance performed 3–7 days after PPCI. The secondary outcomes were myocardial salvage index, transmurality index, left ventricular ejection fraction and relative microvascular obstruction volume. A total of 378 patients were randomly allocated, and after applying exclusion criteria, 222 patients were available for analysis. There were no significant interactions between the two randomization factors on the primary or secondary outcomes. IS was similar between groups for the RIC (24 ± 11.8% in the RIC group vs 23.7 ± 10.9% in the sham group, P = 0.827) and the exenatide hypotheses (25.1 ± 11.5% in the exenatide group vs 22.5 ± 10.9% in the placebo group, P = 0.092). There were no effects with either RIC or exenatide on the secondary outcomes. Unexpected adverse events or side effects of RIC and exenatide were not observed. In conclusion, neither RIC nor exenatide, or its combination, were able to reduce IS in STEMI patients when administered as an adjunct to PPCI