17 research outputs found
Overview of the first Wendelstein 7-X long pulse campaign with fully water-cooled plasma facing components
After a long device enhancement phase, scientific operation resumed in 2022. The main new
device components are the water cooling of all plasma facing components and the new
water-cooled high heat flux divertor units. Water cooling allowed for the first long-pulse
operation campaign. A maximum discharge length of 8 min was achieved with a total heating
energy of 1.3 GJ. Safe divertor operation was demonstrated in attached and detached mode.
Stable detachment is readily achieved in some magnetic configurations but requires impurity
seeding in configurations with small magnetic pitch angle within the edge islands. Progress was
made in the characterization of transport mechanisms across edge magnetic islands:
Measurement of the potential distribution and flow pattern reveals that the islands are associated
with a strong poloidal drift, which leads to rapid convection of energy and particles from the last
closed flux surface into the scrape-off layer. Using the upgraded plasma heating systems,
advanced heating scenarios were developed, which provide improved energy confinement
comparable to the scenario, in which the record triple product for stellarators was achieved in
the previous operation campaign. However, a magnetic configuration-dependent critical heating
power limit of the electron cyclotron resonance heating was observed. Exceeding the respective
power limit leads to a degradation of the confinement
NS19504: A Novel BK Channel Activator with Relaxing Effect on Bladder Smooth Muscle Spontaneous Phasic Contractions
Large-conductance Ca2+-activated K+ channels (BK, K Ca1.1, MaxiK) are important regulators of urinary bladder function and may be an attractive therapeutic target in bladder disorders. In this study, we established a high-throughput fluorometric imaging plate reader-based screening assay for BK channel activators and identified a small-molecule positive modulator, NS19504 (5-[(4-bromophenyl)methyl]-1,3-thiazol-2-amine), which activated the BK channel with an EC50 value of 11.0 ± 1.4 μM. Hit validation was performed using high-throughput electrophysiology (QPatch), and further characterization was achieved in manual whole-cell and inside-out patch-clamp studies in human embryonic kidney 293 cells expressing hBK channels: NS19504 caused distinct activation from a concentration of 0.3 and 10 μM NS19504 left-shifted the voltage activation curve by 60 mV. Furthermore, whole-cell recording showed that NS19504 activated BK channels in native smooth muscle cells from guinea pig urinary bladder. In guinea pig urinary bladder strips, NS19504 (1 μM) reduced spontaneous phasic contractions, an effect that was significantly inhibited by the specific BK channel blocker iberiotoxin. In contrast, NS19504 (1 μM) only modestly inhibited nerve-evoked contractions and had no effect on contractions induced by a high K+ concentration consistent with a K+ channel-mediated action. Collectively, these results show that NS19504 is a positive modulator of BK channels and provide support for the role of BK channels in urinary bladder function. The pharmacologic profile of NS19504 indicates that this compound may have the potential to reduce nonvoiding contractions associated with spontaneous bladder overactivity while having a minimal effect on normal voiding. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics
Conclusion de la première partie
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Identification of a small-molecule inhibitor of the PICK1 PDZ domain that inhibits hippocampal LTP and LTD
Proteins containing PSD-95/Discs-large/ZO-1 homology (PDZ) domains play key roles in the assembly and regulation of cellular signaling pathways and represent putative targets for new pharmacotherapeutics. Here we describe the first small-molecule inhibitor (FSC231) of the PDZ domain in protein interacting with C kinase 1 (PICK1) identified by a screening of ~44,000 compounds in a fluorescent polarization assay. The inhibitor bound the PICK1 PDZ domain with an affinity similar to that observed for endogenous peptide ligands (Ki~10.1 μM). Mutational analysis, together with computational docking of the compound in simulations starting from the PDZ domain structure, identified the binding mode of FSC231. The specificity of FSC231 for the PICK1 PDZ domain was supported by the lack of binding to PDZ domains of postsynaptic density protein 95 (PSD-95) and glutamate receptor interacting protein 1 (GRIP1). Pretreatment of cultured hippocampal neurons with FSC231 inhibited coimmunopreciptation of the AMPA receptor GluR2 subunit with PICK1. In agreement with inhibiting the role of PICK1 in GluR2 trafficking, FSC231 accelerated recycling of pHluorin-tagged GluR2 in hippocampal neurons after internalization in response to NMDA receptor activation. FSC231 blocked the expression of both long-term depression and long-term potentiation in hippocampal CA1 neurons from acute slices, consistent with inhibition of the bidirectional function of PICK1 in synaptic plasticity. Given the proposed role of the PICK1/AMPA receptor interaction in neuropathic pain, excitotoxicity, and cocaine addiction, FSC231 might serve as a lead in the future development of new therapeutics against these conditions