Alternative translation initiation in rat brain yields K2P2.1 potassium channels permeable to sodium.

K(2P) channels mediate potassium background currents essential to central nervous system function, controlling excitability by stabilizing membrane potential below firing threshold and expediting repolarization. Here, we show that alternative translation initiation (ATI) regulates function of K(2P)2.1 (TREK-1) via an unexpected strategy. Full-length K(2P)2.1 and an isoform lacking the first 56 residues of the intracellular N terminus (K(2P)2.1Delta1-56) are produced differentially in a regional and developmental manner in the rat central nervous system, the latter passing sodium under physiological conditions leading to membrane depolarization. Control of ion selectivity via ATI is proposed to be a natural, epigenetic mechanism for spatial and temporal regulation of neuronal excitability

The pathology and treatment of cardiac arrhythmias: focus on atrial fibrillation

Atrial fibrillation (AF) is the most frequently encountered sustained cardiac arrhythmia in clinical practice and a major cause of morbidity and mortality. Effective treatment of AF still remains an unmet medical need. Treatment of AF is based on drug therapy and ablative strategies. Antiarrhythmic drug therapy is limited by a relatively high recurrence rate and proarrhythmic side effects. Catheter ablation suppresses paroxysmal AF in the majority of patients without structural heart disease but is more difficult to achieve in patients with persistent AF or with concomitant cardiac disease. Stroke is a potentially devastating complication of AF, requiring anticoagulation that harbors the risk of bleeding. In search of novel treatment modalities, targeted pharmacological treatment and gene therapy offer the potential for greater selectivity than conventional small-molecule or interventional approaches. This paper summarizes the current understanding of molecular mechanisms underlying AF. Established drug therapy and interventional treatment of AF is reviewed, and emerging clinical and experimental therapeutic approaches are highlighted

Systemic Embolization and Myocardial Infarction due to Clinically Unrecognized Left Atrial Myxoma

Myxomas are the most common primary tumors of the heart. We report an extraordinary severe case of left atrial myxoma, presenting with stroke, myocardial infarction, and multiple arterial embolism including aorta, splenic and renal arteries, and several peripheral arteries. The patient had previously been diagnosed with systemic vasculitis, a typical but less common finding caused by multiple emboli mimicking vasculitis. The myxoma was removed and atrial septum reconstruction was performed. In summary, early diagnostic differentiation of myxoma from vasculitis is critical, and immediate surgical removal of myxoma is required as the probability of thromboembolic complications increases over time

Synchrotron PXRD deconvolutes nickel particle and support changes in Ni/ZrO2_{2} methanation catalysts

Understanding catalyst deactivation is important for future knowledge-based design of catalysts with improved stability. Deactivation by thermal aging is particularly relevant for exothermic reactions, here demonstrated with CO$_{2}$ methanation using nickel-based catalysts. A series of five Ni/ZrO$_{2}$ catalysts is studied which differ by calcination temperature of the ZrO$_{2}$ support prior to Ni deposition, leading to different textural properties of the support. Artificial thermal aging of the Ni/ZrO$_{2}$ series is then performed and monitored by operando synchrotron-based powder X-ray diffraction (SPXRD). This reveals the dependence of catalyst stability on the support properties and shows that different deactivation mechanisms take place. Catalyst deactivation is mainly correlated either to changes of the support or to changes in nickel crystallite size, depending on the calcination temperature of the support before nickel deposition. By preparing a targeted series of supports with different textural properties, it is possible to deconvolute these effects. Operando SPXRD is shown as a powerful tool to follow both textural and structural changes during thermal catalyst deactivation, which is mostly only performed by post mortem ex situ analysis

Spatial activity profiling along a fixed bed of powder catalyst during selective oxidation of propylene to acrolein

Spatial profiling of the reactant and product concentration including the gas phase temperature during the selective oxidation of propylene to acrolein along a catalyst bed allowed locating and distinguishing between specific processes occurring in each individual point of a chemical reactor. For this purpose, a lab-scale testing setup capable of resolving concentration and temperature gradients in a fixed-bed reactor was developed. The local gas phase composition and temperature were determined using a sampling capillary and mass spectrometry along a multicomponent Bi–Mo–Co–Fe oxide catalyst bed during selective oxidation of propylene to acrolein under high conversion conditions. In this way, the reaction progress in terms of conversion, selectivities and yields along the reactor was revealed. While ca. 66% of the integral propylene conversion occurred in the first third of the catalyst bed with high selectivity towards acrolein, the latter third of the bed was dominated by the formation of acrylic acid and CO$_{2}$ as further and total oxidation products, respectively. Acrylic acid, which originates from the sequential oxidation of propylene to acrolein, was the by-product with the highest yield and especially formed above 440 °C. CO and CO$_{2}$ were observed directly from propylene, along with consecutive pathways of propylene oxidation, which favor CO$_{2}$ formation. The numerous insights obtained by even a single profile highlight the strong capabilities of spatially resolved activity and temperature measurements for diagnostics of packed-bed reactors and identifying the reaction pathways occurring within