3,091 research outputs found

    Invasive potential of Tamarix ramosissima (Saltcedar) in continental climates of North America

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    Expatriate Americans are the most important voting bloc you’ve never heard of

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    Around eight million Americans live overseas, a population which would be the 13th largest state if taken as a whole. In presidential elections overseas turnout is around 12 percent, less than a quarter of the amount in general elections. Jay Sexton and Patrick Andelic argue that despite this low turnout rate, expatriate voters can and have played a decisive role in past elections, such as 2000s recount in Florida. They write that given low turnout rates, both Democrats Abroad and Republicans Overseas have some way to go to ensure overseas voters can play a full role in US elections

    Exploring Ligand Binding to Calcitonin Gene-Related Peptide Receptors

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    Class B1 G protein-coupled receptors (GPCRs) are important targets for many diseases, including cancer, diabetes, and heart disease. All the approved drugs for this receptor family are peptides that mimic the endogenous activating hormones. An understanding of how agonists bind and activate class B1 GPCRs is fundamental for the development of therapeutic small molecules. We combined supervised molecular dynamics (SuMD) and classic molecular dynamics (cMD) simulations to study the binding of the calcitonin gene-related peptide (CGRP) to the CGRP receptor (CGRPR). We also evaluated the association and dissociation of the antagonist telcagepant from the extracellular domain (ECD) of CGRPR and the water network perturbation upon binding. This study, which represents the first example of dynamic docking of a class B1 GPCR peptide, delivers insights on several aspects of ligand binding to CGRPR, expanding understanding of the role of the ECD and the receptor-activity modifying protein 1 (RAMP1) on agonist selectivity

    Calcitonin/Amylin Receptors and Ramps

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    Our understanding of G protein-coupled receptor function has recently expanded to encompass novel protein interactions that underlie both cell surface receptor expression and the exhibited phenotype. The most notable examples are those involving receptor activity modifying proteins (RAMPs). RAMP association with the calcitonin receptor-like receptor (CRLR) traffics this receptor to the cell surface, where individual RAMPs dictate the expression of unique phenotypes

    Unpacking the elusive nature of Magnitsky sanctions : human rights and security considerations

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    International sanctions play an increasingly prevalent role in responses to global challenges. In particular, several states and the European Union have in recent years created ‘Magnitsky sanctions’ regimes that utilise travel bans and asset freezes to target persons located abroad presumed responsible for the violation of human rights. This paper seeks to explore Magnitsky sanctions, through the lenses of human rights and security, with a view to seeking clarity and stimulating further discussion on their future place, role, and regulation. Through unpacking Magnitsky sanctions’ potential aims – human rights and security – the paper exposes Magnitsky sanctions as elusive and malleable tools, that potentially reflect more overarching trends, namely the proliferation of securitisation within international relations and dissatisfaction with existing international criminal justice avenues

    Bitopic binding mode of an M1 muscarinic acetylcholine receptor agonist associated with adverse clinical trial outcomes

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    The realisation of the therapeutic potential of targeting the M1 muscarinic acetylcholine receptor (M1 mAChR) for the treatment of cognitive decline in Alzheimer's disease has prompted the discovery of M1 mAChR ligands showing efficacy in alleviating cognitive dysfunction in both rodents and humans. Among these is GSK1034702, described previously as a potent M1 receptor allosteric agonist, which showed pro-cognitive effects in rodents and improved immediate memory in a clinical nicotine withdrawal test but induced significant side-effects. Here we provide evidence using ligand binding, chemical biology and functional assays to establish that rather than the allosteric mechanism claimed, GSK1034702 interacts in a bitopic manner at the M1 mAChR such that it can concomitantly span both the orthosteric and an allosteric binding site. The bitopic nature of GSK1034702 together with the intrinsic agonist activity and a lack of muscarinic receptor subtype selectivity reported here, all likely contribute to the adverse effects of this molecule in clinical trials. We conclude that these properties, whilst imparting beneficial effects on learning and memory, are undesirable in a clinical candidate due to the likelihood of adverse side effects. Rather, our data supports the notion that "pure" positive allosteric modulators showing selectivity for the M1 mAChR with low levels of intrinsic activity would be preferable to provide clinical efficacy with low adverse responses

    Biased allosteric modulation at the CaS receptor engendered by structurally diverse calcimimetics

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    Background and Purpose Clinical use of cinacalcet in hyperparathyroidism is complicated by its tendency to induce hypocalcaemia, arising partly from activation of calcium-sensing receptors (CaS receptors) in the thyroid and stimulation of calcitonin release. CaS receptor allosteric modulators that selectively bias signalling towards pathways that mediate desired effects [e.g. parathyroid hormone (PTH) suppression] rather than those mediating undesirable effects (e.g. elevated serum calcitonin), may offer better therapies. Experimental Approach We characterized the ligand-biased profile of novel calcimimetics in HEK293 cells stably expressing human CaS receptors, by monitoring intracellular calcium (Ca2+i) mobilization, inositol phosphate (IP)1 accumulation, ERK1/2 phosphorylation (pERK1/2) and receptor expression. Key Results Phenylalkylamine calcimimetics were biased towards allosteric modulation of Ca2+i mobilization and IP1 accumulation. S,R-calcimimetic B was biased only towards IP1 accumulation. R,R-calcimimetic B and AC-265347 were biased towards IP1 accumulation and pERK1/2. Nor-calcimimetic B was unbiased. In contrast to phenylalkylamines and calcimimetic B analogues, AC-265347 did not promote trafficking of a loss-of-expression, naturally occurring, CaS receptor mutation (G670E). Conclusions and Implications The ability of R,R-calcimimetic B and AC-265347 to bias signalling towards pERK1/2 and IP1 accumulation may explain their suppression of PTH levels in vivo at concentrations that have no effect on serum calcitonin levels. The demonstration that AC-265347 promotes CaS receptor receptor signalling, but not trafficking reveals a novel profile of ligand-biased modulation at CaS receptors The identification of allosteric modulators that bias CaS receptor signalling towards distinct intracellular pathways provides an opportunity to develop desirable biased signalling profiles in vivo for mediating selective physiological responses

    4-Phenylpyridin-2-one derivatives: a novel class of positive allosteric modulator of the M1 muscarinic acetylcholine receptor

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    Positive allosteric modulators (PAMs) of the M1 muscarinic acetylcholine receptor (M1 mAChR) are a promising strategy for the treatment of the cognitive deficits associated with diseases including Alzheimer’s and schizophrenia. Herein, we report the design, synthesis, and characterization of a novel family of M1 mAChR PAMs. The most active compounds of the 4-phenylpyridin-2-one series exhibited comparable binding affinity to the reference compound, 1-(4-methoxybenzyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (BQCA) (1), but markedly improved positive cooperativity with acetylcholine, and retained exquisite selectivity for the M1 mAChR. Furthermore, our pharmacological characterization revealed ligands with a diverse range of activities, including modulators that displayed both high intrinsic efficacy and PAM activity, those that showed no detectable agonism but robust PAM activity and ligands that displayed robust allosteric agonism but little modulatory activity. Thus, the 4-phenylpyridin-2-one scaffold offers an attractive starting point for further lead optimization
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