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

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

Genetic diversity, demographic history and neo-sex chromosomes in the Critically Endangered Raso lark

Small effective population sizes could expose island species to inbreeding and loss of genetic variation. Here, we investigate factors shaping genetic diversity in the Raso lark, which has been restricted to a single islet for approximately 500 years, with a population size of a few hundred. We assembled a reference genome for the related Eurasian skylark and then assessed diversity and demographic history using RAD-seq data (75 samples from Raso larks and two related mainland species). We first identify broad tracts of suppressed recombination in females, indicating enlarged neo-sex chromosomes. We then show that genetic diversity across autosomes in the Raso lark is lower than in its mainland relatives, but inconsistent with long-term persistence at its current population size. Finally, we find that genetic signatures of the recent population contraction are overshadowed by an ancient expansion and persistence of a very large population until the human settlement of Cape Verde. Our findings show how genome-wide approaches to study endangered species can help avoid confounding effects of genome architecture on diversity estimates, and how present-day diversity can be shaped by ancient demographic events

A Systematic Search for Molecular Outflows Toward Candidate Low-Luminosity Protostars and Very Low Luminosity Objects

We present a systematic single-dish search for molecular outflows toward a sample of 9 candidate low-luminosity protostars and 30 candidate Very Low Luminosity Objects (VeLLOs; L_int < 0.1 L_sun). The sources are identified using data from the Spitzer Space Telescope catalogued by Dunham et al. toward nearby (D < 400 pc) star forming regions. Each object was observed in 12CO and 13CO J = 2-1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30 arcsecond resolution. Using 5-point grid maps we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A IRS3 outflow is detected but not remapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.Comment: 42 pages, 19 figures, Accepted for publication in the Astronomical Journa

Importance of the Active Site "Canopy" Residues in an O_2-Tolerant [NiFe]-Hydrogenase

The active site of Hyd-1, an oxygen-tolerant membrane-bound [NiFe]-hydrogenase from Escherichia coli, contains four highly conserved residues that form a “canopy” above the bimetallic center, closest to the site at which exogenous agents CO and O_2 interact, substrate H_2 binds, and a hydrido intermediate is stabilized. Genetic modification of the Hyd-1 canopy has allowed the first systematic and detailed kinetic and structural investigation of the influence of the immediate outer coordination shell on H_2 activation. The central canopy residue, arginine 509, suspends a guanidine/guanidinium side chain at close range above the open coordination site lying between the Ni and Fe atoms (N–metal distance of 4.4 Å): its replacement with lysine lowers the H_2 oxidation rate by nearly 2 orders of magnitude and markedly decreases the H_2/D_2 kinetic isotope effect. Importantly, this collapse in rate constant can now be ascribed to a very unfavorable activation entropy (easily overriding the more favorable activation enthalpy of the R509K variant). The second most important canopy residue for H_2 oxidation is aspartate 118, which forms a salt bridge to the arginine 509 headgroup: its mutation to alanine greatly decreases the H_2 oxidation efficiency, observed as a 10-fold increase in the potential-dependent Michaelis constant. Mutations of aspartate 574 (also salt-bridged to R509) to asparagine and proline 508 to alanine have much smaller effects on kinetic properties. None of the mutations significantly increase sensitivity to CO, but neutralizing the expected negative charges from D118 and D574 decreases O_2 tolerance by stabilizing the oxidized resting Ni^(III)–OH state (“Ni-B”). An extensive model of the catalytic importance of residues close to the active site now emerges, whereby a conserved gas channel culminates in the arginine headgroup suspended above the Ni and Fe

Perceptions and Reactions with Regard to Pneumonic Plague

We assessed perceptions and likely reactions of 1,005 UK adults to a hypothetical terrorist attack involving pneumonic plague. Likely compliance with official recommendations ranged from good (98% would take antimicrobial drugs) to poor (76% would visit a treatment center). Perceptions about plague were associated with these intentions

Antiandrogens Act as Selective Androgen Receptor Modulators at the Proteome Level in Prostate Cancer Cells*

Current therapies for prostate cancer include antiandrogens, inhibitory ligands of the androgen receptor, which repress androgen-stimulated growth. These include the selective androgen receptor modulators cyproterone acetate and hydroxyflutamide and the complete antagonist bicalutamide. Their activity is partly dictated by the presence of androgen receptor mutations, which are commonly detected in patients who relapse while receiving antiandrogens, i.e. in castrate-resistant prostate cancer. To characterize the early proteomic response to these antiandrogens we used the LNCaP prostate cancer cell line, which harbors the androgen receptor mutation most commonly detected in castrate-resistant tumors (T877A), analyzing alterations in the proteome, and comparing these to the effect of these therapeutics upon androgen receptor activity and cell proliferation. The majority are regulated post-transcriptionally, possibly via nongenomic androgen receptor signaling. Differences detected between the exposure groups demonstrate subtle changes in the biological response to each specific ligand, suggesting a spectrum of agonistic and antagonistic effects dependent on the ligand used. Analysis of the crystal structures of the AR in the presence of cyproterone acetate, hydroxyflutamide, and DHT identified important differences in the orientation of key residues located in the AF-2 and BF-3 protein interaction surfaces. This further implies that although there is commonality in the growth responses between androgens and those antiandrogens that stimulate growth in the presence of a mutation, there may also be influential differences in the growth pathways stimulated by the different ligands. This therefore has implications for prostate cancer treatment because tumors may respond differently dependent upon which mutation is present and which ligand is activating growth, also for the design of selective androgen receptor modulators, which aim to elicit differential proteomic responses dependent upon cellular context

AKARI observations of ice absorption bands towards edge-on young stellar objects

To investigate the composition and evolution of circumstellar ice around low-mass young stellar objects (YSOs), we observed ice absorption bands in the near infrared (NIR) towards eight YSOs ranging from class 0 to class II, among which seven are associated with edge-on disks. We performed slit-less spectroscopic observations using the grism mode of the InfraRed Camera (IRC) on board AKARI, which enables us to obtain full NIR spectra from 2.5 mu m to 5 mu m, including the CO2 band and the blue wing of the H2O band, which are inaccessible from the ground. We developed procedures to carefully process the spectra of targets with nebulosity. The spectra were fitted with polynomial baselines to derive the absorption spectra. The molecular absorption bands were then fitted with the laboratory database of ice absorption bands, considering the instrumental line profile and the spectral resolution of the grism dispersion element. Towards the class 0-I sources (L1527, IRC-L1041-2, and IRAS 04302), absorption bands of H2O, CO2, CO, and XCN are clearly detected. Column density ratios of CO2 ice and CO ice relative to H2O ice are 21-28% and 13-46%, respectively. If XCN is OCN-, its column density is as high as 2-6% relative to H2O ice. The HDO ice feature at 4.1 mu m is tentatively detected towards the class 0-I sources and HV Tau. Non-detections of the CH-stretching mode features around 3.5 mu m provide upper limits to the CH3OH abundance of 26% (L1527) and 42% (IRAS 04302) relative to H2O. We tentatively detect OCS ice absorption towards IRC-L1041-2. Towards class 0-I sources, the detected features should mostly originate in the cold envelope, while CO gas and OCN-could originate in the region close to the protostar, where there are warm temperatures and UV radiation. We detect H2O ice band towards ASR41 and 2MASSJ 1628137-243139, which are edge-on class II disks. We also detect H2O ice and CO2 ice towards HV Tau, HK Tau, and UY Aur, and tentatively detect CO gas features towards HK Tau and UY Aur

Relationship Difficulties Among U.K. Military Personnel: Impact of Sociodemographic, Military, and Deployment-Related Factors

© 2015, Taylor & Francis Group, LLC. Military work, especially operational deployments, may impact the romantic relationships of military personnel. Using a subsample of 7,581 participants from a cohort study of U.K. military personnel (data collected between 2007 and 2009), the prevalence of relationship difficulties and associations with sociodemographic, military-, and deployment-related characteristics was examined. Most participants did not report experiencing relationship difficulties. Adjusted regression analyses indicate that childhood adversity, limited support for and from partners, being in unmarried relationships, financial problems, deploying for more than 13 months in 3 years, and work being above trade, ability, and experience were key factors associated with relationship difficulties. The likelihood of U.K. military personnel experiencing relationship difficulties is increased because of personal vulnerabilities that may be exacerbated in the military context

Communication aid requirements of intensive care unit patients with transient speech loss

Alert and transiently nonvocal intensive care unit (ICU) patients are dependent on augmentative and alternative communication (AAC). Unfortunately, the literature demonstrates that existent AAC devices have not been widely adopted, and unaided methods are often the primary modalities used despite being insufficient, and frustrating. We present the results of a qualitative semi-structured interview study with 8 ex-ICU patients, 4 ICU patient relatives, and 6 ICU staff, exploring their AAC needs and requirements. Participants identified important AAC hardware, software, and content requirements. Salient factors impacting on AAC adoption in the ICU setting were also highlighted and included the need for staff training and bedside patient assessment. Based on the study results, we propose a series of recommendations regarding the design and implementation of future AAC tools specifically targeted at this group