Fischer carbene complexes of cobalt(I) : synthesis and structure

Please read abstract in the article.Cambridge Crystallographic Data Center Crystallographic data. Data associated with the article:) CCDC 1988149: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc24qtvk&sid=DataCite)CCDC 1988148: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc24qttj&sid=DataCite)CCDC 1988152: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc24qtyn&sid=DataCite)CCDC 1988151: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc24qtxm&sid=DataCite)The National Research Foundation, South Africa and Sasol Technology R&D Pty. Ltd. (South Africa).http://www.elsevier.com/locate/molstrhj2023Chemistr

Synthesis and structure of annulated dithieno[2,3- b ;3 ʹ,2 ʹ- d ]thienyl- and ring-opened 3,3 ʹ-bithienyl Fischer carbene complexes

Please read abstract in the article.Appendix A. Supplementary data.Appendix B. checkCIF/PLATON reportResearch data for this article: Cambridge Crystallographic Data Center. Crystallographic data: CCDC 2009041: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fksz&sid=DataCite)CCDC 2009042: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fkt0&sid=DataCite)CCDC 2009043: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fkv1&sid=DataCite)CCDC 2009044: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fkw2&sid=DataCite)CCDC 2009045: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fkx3&sid=DataCite)CCDC 2009046: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fky4&sid=DataCite)CCDC 2009047: Experimental Crystal Structure Determination (https://www.ccdc.cam.ac.uk/structures/search?id=doi:10.5517/ccdc.csd.cc25fkz5&sid=DataCite)The National Research Foundation, South Africa and Sasol Technology R&D Pty. Ltd. (South Africa).http://www.elsevier.com/locate/jorganchemam2021Chemistr

Phosphoinositide 3-kinase γ-deficient hearts are protected from the PAF-dependent depression of cardiac contractility

Objectives: Following an ischemic insult, cardiac contractile recovery might be perturbed by the release of autacoids, like platelet-activating factor (PAF), that depress heart function by acting through G protein-coupled receptors (GPCRs). The signaling events downstream the PAF receptor that lead to the negative inotropic effect are still obscure. We thus investigated whether the GPCR-activated phosphoisositide 3-kinase γ (PI3Kγ) could play a role in the cardiac response to PAF. Methods: The negative inotropic effect of PAF was studied ex vivo, in isolated electrically driven atria and in Langendorff-perfused whole hearts derived from wild-type and PI3Kγ-null mice. Postischemic recovery of contractility was analyzed in normal and mutant whole hearts subjected to 30 min of ischemia and 40 min of reperfusion in the presence or absence of a PAF receptor antagonist. Results: While wild-type hearts stimulated with PAF showed increased nitric oxide (NO) production and a consequent decreased cardiac contractility, PI3Kγ-null hearts displayed reduced phosphorylation of nitric oxide synthase 3 (NOS3), blunted nitric oxide production and a complete protection from the PAF-induced negative inotropism. In addition, Langendorff-perfused PI3Kγ-null hearts showed a better contractile recovery after ischemia/reperfusion, a condition where PAF is known to be an important player in depressing contractility. In agreement with a role of PI3Kγ in this PAF-mediated signaling, postischemic contractile recovery in PI3Kγ-null mice appeared overlapping with that of normal hearts treated with the PAF receptor antagonist WEB 2170. Conclusion: These data indicate a novel PAF-dependent signaling pathway that, involving PI3Kγ and NOS3, contributes to postischemic contractile depressio

Optogenetic Hyperpolarization of Cardiomyocytes Terminates Ventricular Arrhythmia

Cardiac defibrillation to terminate lethal ventricular arrhythmia (VA) is currently performed by applying high energy electrical shocks. In cardiac tissue, electrical shocks induce simultaneously de- and hyperpolarized areas and only depolarized areas are considered to be responsible for VA termination. Because electrical shocks do not allow proper control over spatial extent and level of membrane potential changes, the effects of hyperpolarization have not been explored in the intact heart. In contrast, optogenetic methods allow cell type-selective induction of de- and hyperpolarization with unprecedented temporal and spatial control. To investigate effects of cardiomyocyte hyperpolarization on VA termination, we generated a mouse line with cardiomyocyte-specific expression of the light-driven proton pump ArchT. Isolated cardiomyocytes showed light-induced outward currents and hyperpolarization. Free-running VA were evoked by electrical stimulation of explanted hearts perfused with low K+ and the KATP channel opener Pinacidil. Optogenetic hyperpolarization was induced by epicardial illumination, which terminated VA with an average efficacy of ∼55%. This value was significantly higher compared to control hearts without illumination or ArchT expression (p = 0.0007). Intracellular recordings with sharp electrodes within the intact heart revealed hyperpolarization and faster action potential upstroke upon illumination, which should fasten conduction. However, conduction speed was lower during illumination suggesting enhanced electrical sink by hyperpolarization underlying VA termination. Thus, selective hyperpolarization in cardiomyocytes is able to terminate VA with a completely new mechanism of increased electrical sink. These novel insights could improve our mechanistic understanding and treatment strategies of VA termination

Ghrelin and des-acyl ghrelin inhibit cell death in cardiomyocytes and endothelial cells through ERK1/2 and PI 3-kinase/AKT

Ghrelin is an acyl-peptide gastric hormone acting on the pituitary and hypothalamus to stimulate growth hormone (GH) release, adiposity, and appetite. Ghrelin endocrine activities are entirely dependent on its acylation and are mediated by GH secretagogue (GHS) receptor (GHSR)-1a, a G protein–coupled receptor mostly expressed in the pituitary and hypothalamus, previously identified as the receptor for a group of synthetic molecules featuring GH secretagogue (GHS) activity. Des-acyl ghrelin, which is far more abundant than ghrelin, does not bind GHSR-1a, is devoid of any endocrine activity, and its function is currently unknown. Ghrelin, which is expressed in heart, albeit at a much lower level than in the stomach, also exerts a cardio protective effect through an unknown mechanism, independent of GH release. Here we show that both ghrelin and des-acyl ghrelin inhibit apoptosis of primary adult and H9c2 cardiomyocytes and endothelial cells in vitro through activation of extracellular signal–regulated kinase-1/2 and Akt serine kinases. In addition, ghrelin and des-acyl ghrelin recognize common high affinity binding sites on H9c2 cardiomyocytes, which do not express GHSR-1a. Finally, both MK-0677 and hexarelin, a nonpeptidyl and a peptidyl synthetic GHS, respectively, recognize the common ghrelin and des-acyl ghrelin binding sites, inhibit cell death, and activate MAPK and Akt

Macrophage-dependent IL-1β production induces cardiac arrhythmias in diabetic mice

Diabetes mellitus (DM) encompasses a multitude of secondary disorders, including heart disease. One of the most frequent and potentially life threatening disorders of DM-induced heart disease is ventricular tachycardia (VT). Here we show that toll-like receptor 2 (TLR2) and NLRP3 inflammasome activation in cardiac macrophages mediate the production of IL-1β in DM mice. IL-1β causes prolongation of the action potential duration, induces a decrease in potassium current and an increase in calcium sparks in cardiomyocytes, which are changes that underlie arrhythmia propensity. IL-1β-induced spontaneous contractile events are associated with CaMKII oxidation and phosphorylation. We further show that DM-induced arrhythmias can be successfully treated by inhibiting the IL-1β axis with either IL-1 receptor antagonist or by inhibiting the NLRP3 inflammasome. Our results establish IL-1β as an inflammatory connection between metabolic dysfunction and arrhythmias in DM.Facultad de Ciencias MédicasCentro de Investigaciones Cardiovasculare

How Carvedilol activates β₂-adrenoceptors

Carvedilol is among the most effective β-blockers for improving survival after myocardial infarction. Yet the mechanisms by which carvedilol achieves this superior clinical profile are still unclear. Beyond blockade of β(1)-adrenoceptors, arrestin-biased signalling via β(2)-adrenoceptors is a molecular mechanism proposed to explain the survival benefits. Here, we offer an alternative mechanism to rationalize carvedilol’s cellular signalling. Using primary and immortalized cells genome-edited by CRISPR/Cas9 to lack either G proteins or arrestins; and combining biological, biochemical, and signalling assays with molecular dynamics simulations, we demonstrate that G proteins drive all detectable carvedilol signalling through β(2)ARs. Because a clear understanding of how drugs act is imperative to data interpretation in basic and clinical research, to the stratification of clinical trials or to the monitoring of drug effects on the target pathway, the mechanistic insight gained here provides a foundation for the rational development of signalling prototypes that target the β-adrenoceptor system

Macrophage-dependent IL-1β production induces cardiac arrhythmias in diabetic mice

Diabetes mellitus (DM) encompasses a multitude of secondary disorders, including heart disease. One of the most frequent and potentially life threatening disorders of DM-induced heart disease is ventricular tachycardia (VT). Here we show that toll-like receptor 2 (TLR2) and NLRP3 inflammasome activation in cardiac macrophages mediate the production of IL-1β in DM mice. IL-1β causes prolongation of the action potential duration, induces a decrease in potassium current and an increase in calcium sparks in cardiomyocytes, which are changes that underlie arrhythmia propensity. IL-1β-induced spontaneous contractile events are associated with CaMKII oxidation and phosphorylation. We further show that DM-induced arrhythmias can be successfully treated by inhibiting the IL-1β axis with either IL-1 receptor antagonist or by inhibiting the NLRP3 inflammasome. Our results establish IL-1β as an inflammatory connection between metabolic dysfunction and arrhythmias in DM.Facultad de Ciencias MédicasCentro de Investigaciones Cardiovasculare

Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations

We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization Array (HERA). Using similar analysis techniques as in previously reported limits (HERA Collaboration 2022a), we find at 95% confidence that $\Delta^2(k = 0.34$ $h$ Mpc$^{-1}$) $\leq 457$ mK$^2$ at $z = 7.9$ and that $\Delta^2 (k = 0.36$ $h$ Mpc$^{-1}) \leq 3,496$ mK$^2$ at $z = 10.4$, an improvement by a factor of 2.1 and 2.6 respectively. These limits are mostly consistent with thermal noise over a wide range of $k$ after our data quality cuts, despite performing a relatively conservative analysis designed to minimize signal loss. Our results are validated with both statistical tests on the data and end-to-end pipeline simulations. We also report updated constraints on the astrophysics of reionization and the cosmic dawn. Using multiple independent modeling and inference techniques previously employed by HERA Collaboration (2022b), we find that the intergalactic medium must have been heated above the adiabatic cooling limit at least as early as $z = 10.4$, ruling out a broad set of so-called "cold reionization" scenarios. If this heating is due to high-mass X-ray binaries during the cosmic dawn, as is generally believed, our result's 99% credible interval excludes the local relationship between soft X-ray luminosity and star formation and thus requires heating driven by evolved low-metallicity stars.Comment: 57 pages, 37 figures. Updated to match the accepted ApJ version. Corresponding author: Joshua S. Dillo