Decoding Corticotropin-Releasing Factor Receptor Type 1 Crystal Structures.

The structural analysis of class B G protein-coupled receptors (GPCR), cell surface proteins responding to peptide hormones, has until recently been restricted to the extracellular domain (ECD). Corticotropin-releasing factor receptor type 1 (CRF1R) is a class B receptor mediating stress response and also considered a drug target for depression and anxiety. Here we report the crystal structure of the transmembrane domain of human CRF1R in complex with the small-molecule antagonist CP-376395 in a hexagonal setting with translational non-crystallographic symmetry. Molecular dynamics and metadynamics simulations on this novel structure and the existing TMD structure for CRF1R provides insight as to how the small molecule ligand gains access to the induced-fit allosteric binding site with implications for the observed selectivity against CRF2R. Furthermore, molecular dynamics simulations performed using a full-length receptor model point to key interactions between the ECD and extracellular loop 3 of the TMD providing insight into the full inactive state of multidomain class B GPCRs.This is the accepted manuscript. It is currently embargoed pending publication

Comparing the effects of sun exposure and vitamin D supplementation on vitamin D insufficiency, and immune and cardio-metabolic function: the Sun Exposure and Vitamin D Supplementation (SEDS) Study

BACKGROUND Adults living in the sunny Australian climate are at high risk of skin cancer, but vitamin D deficiency (defined here as a serum 25-hydroxyvitamin D (25(OH)D) concentration of less than 50 nmol/L) is also common. Vitamin D deficiency may be a risk factor for a range of diseases. However, the optimal strategies to achieve and maintain vitamin D adequacy (sun exposure, vitamin D supplementation or both), and whether sun exposure itself has benefits over and above initiating synthesis of vitamin D, remain unclear. The Sun Exposure and Vitamin D Supplementation (SEDS) Study aims to compare the effectiveness of sun exposure and vitamin D supplementation for the management of vitamin D insufficiency, and to test whether these management strategies differentially affect markers of immune and cardio-metabolic function. METHODS/DESIGN The SEDS Study is a multi-centre, randomised controlled trial of two different daily doses of vitamin D supplementation, and placebo, in conjunction with guidance on two different patterns of sun exposure. Participants recruited from across Australia are aged 18-64 years and have a recent vitamin D test result showing a serum 25(OH)D level of 40-60 nmol/L. DISCUSSION This paper discusses the rationale behind the study design, and considers the challenges but necessity of data collection within a non-institutionalised adult population, in order to address the study aims. We also discuss the challenges of participant recruitment and retention, ongoing engagement of referring medical practitioners and address issues of compliance and participant retention. TRIAL REGISTRATION Australia New Zealand Clinical Trials Registry: ACTRN12613000290796 Registered 14 March 2013

The ethics of future trials: qualitative analysis of physicians' decision making

Background: The decision to conduct a randomized controlled trial (RCT) in a field raises ethical as well as scientific issues. From the clinical equipoise literature, future trials are justifiable if there is ”honest, professional disagreement in the community of expert practitioners as to the preferred treatment”. Empirical data are sparse about how clinicians apply the principles of equipoise to the justification of future RCTs. For example, selective decontamination of the digestive tract (SDD) is not widely used in critical care practice despite the strength of the evidence base and therefore provides a unique opportunity to learn how clinicians think about the ethics of further RCTs in critical care. Methods: In an international interview study of views of healthcare professionals about SDD, we undertook a secondary analysis of qualitative data collected using a Theoretical Domains Framework of clinical behaviour. We adopted a general descriptive approach to explore how physicians determined whether another RCT of SDD is ethical. Following a constant comparison approach, three investigators reviewed 54 purposively chosen transcripts from three international regions. We interpreted the data using thematic analysis. Results: We grouped participants’ responses into four inter-related themes: 1) cultural norms about evidence and practice within healthcare; 2) personal views about what evidence is current or applicable; 3) the interpersonal and relational nature of professional decision making locally; and 4) an a priori commitment to future trials. The analysis also identified several unresolved tensions regarding when a future RCT should be pursued. These tensions focused on a clash between potential benefits to current individual patients and potential future harms to patients more broadly. Conclusions: Our study suggests that ethical decision making about future RCTs in the field of SDD does not rely strongly on appeals to evidence, even when the quality of the evidence is reasonably high. Rather, “extra-evidential” reasons, including social, professional, and relational factors, seem to influence opinions regarding the ethics of future trials. Further work is required to see if these conclusions are applicable to other clinical topics and settings

Legacies of domestication, trade and herder mobility shape extant male zebu cattle diversity in South Asia and Africa

All tropically adapted humped cattle (Bos indicus or 'zebu'), descend from a domestication process that took place >8,000 years ago in South Asia. Here we present an intercontinental survey of Y-chromosome diversity and a comprehensive reconstruction of male-lineage zebu cattle history and diversity patterns. Phylogenetic analysis revealed that all the zebu Y-chromosome haplotypes in our dataset group within three different lineages: Y3A, the most predominant and cosmopolitan lineage; Y3B, only observed in West Africa; and Y3C, predominant in South and Northeast India. The divergence times estimated for these three Zebu-specific lineages predate domestication. Coalescent demographic models support either de novo domestication of genetically divergent paternal lineages or more complex process including gene flow between wild and domestic animals. Our data suggest export of varied zebu lineages from domestication centres through time. The almost exclusive presence of Y3A haplotypes in East Africa is consistent with recent cattle restocking in this area. The cryptic presence of Y3B haplotypes in West Africa, found nowhere else, suggests that these haplotypes might represent the oldest zebu lineage introduced to Africa ca. 3,000 B.P. and subsequently replaced in most of the world. The informative ability of Interspersed Multilocus Microsatellites and Y-specific microsatellites to identify genetic structuring in cattle populations is confirmed

Monoclonal anti-β1-adrenergic receptor antibodies activate G protein signaling in the absence of β-arrestin recruitment

Thermostabilized G protein-coupled receptors used as antigens for in vivo immunization have resulted in the generation of functional agonistic anti-β1-adrenergic (β1AR) receptor monoclonal antibodies (mAbs). The focus of this study was to examine the pharmacology of these antibodies to evaluate their mechanistic activity at β1AR. Immunization with the β1AR stabilized receptor yielded five stable hybridoma clones, four of which expressed functional IgG, as determined in cell-based assays used to evaluate cAMP stimulation. The antibodies bind diverse epitopes associated with low nanomolar agonist activity at β1AR, and they appeared to show some degree of biased signaling as they were inactive in an assay measuring signaling through β-arrestin. In vitro characterization also verified different antibody-receptor interactions reflecting the different epitopes on the extracellular surface of β1AR to which the mAbs bind. The anti-β1AR mAbs only demonstrated agonist activity when in dimeric antibody format, but not as the monomeric Fab format, suggesting that agonist activation may be mediated through promoting receptor dimerization. Finally, we have also shown that at least one of these antibodies exhibits in vivo functional activity at a therapeutically-relevant dose producing an increase in heart rate consistent with β1AR agonism

The views of health care professionals about selective decontamination of the digestive tract: An international, theoretically informed interview study

Purpose: Selective Decontamination of the Digestive tract (SDD) as a prophylactic intervention improves hospital-acquired infection and survival rates. Uptake of SDD is low and remains controversial. This study applied the Theoretical Domains Framework (TDF) to assess ICU clinicians’ views about SDD in regions with limited or no adoption of SDD. Materials and Methods: Participants were health professionals with ‘decisional authority’ for the adoption of SDD. Semistructured interviews were conducted as the first round of a Delphi study. Views about SDDadoption, delivery and further SDD research were explored. Directed content analysis of interview data identified sub-themes which informed item development for subsequent Delphi rounds. Linguistic features of interview data were also explored. Results: 141 participants provided interview data. Fifty-six sub-themes were identified; 46 were common across regions. Beliefs about consequences was the most widely elaborated theme. Linguistic features of how participants discussed SDD included caution expressed when discussing the risks and benefits and words such as worry, anxiety and fear when discussing potential antibiotic resistance associated with SDD. Conclusions: We identified salient beliefs, barriers and facilitators to SDD adoption and delivery. What participants said about SDD and the way in which they said it demonstrated the degree of clinical caution, uncertainty and concern that SDD evokes

The mechanisms and processes of connection: developing a causal chain model capturing impacts of receiving recorded mental health recovery narratives.

BACKGROUND: Mental health recovery narratives are a core component of recovery-oriented interventions such as peer support and anti-stigma campaigns. A substantial number of recorded recovery narratives are now publicly available online in different modalities and in published books. Whilst the benefits of telling one's story have been investigated, much less is known about how recorded narratives of differing modalities impact on recipients. A previous qualitative study identified connection to the narrator and/or to events in the narrative to be a core mechanism of change. The factors that influence how individuals connect with a recorded narrative are unknown. The aim of the current study was to characterise the immediate effects of receiving recovery narratives presented in a range of modalities (text, video and audio), by establishing the mechanisms of connection and the processes by which connection leads to outcomes. METHOD: A study involving 40 mental health service users in England was conducted. Participants were presented with up to 10 randomly-selected recovery narratives and were interviewed on the immediate impact of each narrative. Thematic analysis was used to identify the mechanisms of connection and how connection leads to outcome. RESULTS: Receiving a recovery narrative led participants to reflect upon their own experiences or those of others, which then led to connection through three mechanisms: comparing oneself with the narrative and narrator; learning about other's experiences; and experiencing empathy. These mechanisms led to outcomes through three processes: the identification of change (through attending to narrative structure); the interpretation of change (through attending to narrative content); and the internalisation of interpretations. CONCLUSIONS: This is the first study to identify mechanisms and processes of connection with recorded recovery narratives. The empirically-based causal chain model developed in this study describes the immediate effects on recipients. This model can inform selection of narratives for use in interventions, and be used to support peer support workers in recounting their own recovery narratives in ways which are maximally beneficial to others

The Orphan G Protein-coupled Receptors GPR41 and GPR43 Are Activated by Propionate and Other Short Chain Carboxylic Acids

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