Structural basis for CCR6 modulation by allosteric antagonists.

The CC chemokine receptor 6 (CCR6) is a potential target for chronic inflammatory diseases. Previously, we reported an active CCR6 structure in complex with its cognate chemokine CCL20, revealing the molecular basis of CCR6 activation. Here, we present two inactive CCR6 structures in ternary complexes with different allosteric antagonists, CCR6/SQA1/OXM1 and CCR6/SQA1/OXM2. The oxomorpholine analogues, OXM1 and OXM2 are highly selective CCR6 antagonists which bind to an extracellular pocket and disrupt the receptor activation network. An energetically favoured U-shaped conformation in solution that resembles the bound form is observed for the active analogues. SQA1 is a squaramide derivative with close-in analogues reported as antagonists of chemokine receptors including CCR6. SQA1 binds to an intracellular pocket which overlaps with the G protein site, stabilizing a closed pocket that is a hallmark of inactive GPCRs. Minimal communication between the two allosteric pockets is observed, in contrast to the prevalent allosteric cooperativity model of GPCRs. This work highlights the versatility of GPCR antagonism by small molecules, complementing previous knowledge of CCR6 activation, and sheds light on drug discovery targeting CCR6.

An operational workflow for producing periodic estimates of species occupancy at national scales.

Policy makers require high-level summaries of biodiversity change. However, deriving such summaries from raw biodiversity data is a complex process involving several intermediary stages. In this paper, we describe an operational workflow for generating annual estimates of species occupancy at national scales from raw species occurrence data, which can be used to construct a range of policy-relevant biodiversity indicators. We describe the workflow in detail: from data acquisition, data assessment and data manipulation, through modelling, model evaluation, application and dissemination. At each stage, we draw on our experience developing and applying the workflow for almost a decade to outline the challenges that analysts might face. These challenges span many areas of ecology, taxonomy, data science, computing and statistics. In our case, the principal output of the workflow is annual estimates of occupancy, with measures of uncertainty, for over 5000 species in each of several defined 'regions' (e.g. countries, protected areas, etc.) of the UK from 1970 to 2019. This data product corresponds closely to the notion of a species distribution Essential Biodiversity Variable (EBV). Throughout the paper, we highlight methodologies that might not be applicable outside of the UK and suggest alternatives. We also highlight areas where the workflow can be improved; in particular, methods are needed to mitigate and communicate the risk of bias arising from the lack of representativeness that is typical of biodiversity data. Finally, we revisit the 'ideal' and 'minimal' criteria for species distribution EBVs laid out in previous contributions and pose some outstanding questions that should be addressed as a matter of priority. Going forward, we hope that this paper acts as a template for research groups around the world seeking to develop similar data products.

The epidemiology of head injuries at 2019 Rugby Union World Cup.

INTRODUCTION: The sequelae of concussion are of growing concern within Rugby. World Rugby has introduced rule changes to improve player welfare and reduce head injury frequency. We aimed to report the incidence of head injuries and head injury assessment (HIA) at the 2019 Rugby World Cup (RWC). METHODS: We reviewed all 45 tournament matches and recorded the number of head injuries, the injured player's position, and the mechanism of injury; whether the player had an HIA; and if they returned to play following injury. We compared these findings with previous RWCs. RESULTS: We recorded 68 head injuries (1.33/game). Thirty-six players (52.9%) were removed from the field of play for an HIA. Of these, 23 (63.9%) failed and therefore considered to have concussion. The head injury rate in 2019 was 37.8 per 1000 player hours, which increased from previous tournaments (22.0 in 2015, 14.6 in 2011, and 4.7 in 2007). The concussion rate was 23 per 1000 player hours in 2019, which was lower than 29 in 2015. In 2019, 63.9% of HIAs were failed compared to 48.7% in 2015. We identified 17 cases where medical staff did not attend to a player suffering a head injury on-field. Of these, four players underwent an HIA after the match doctor reviewed the incident. CONCLUSION: We recorded a higher rate of head injuries, and a player was more likely to fail their HIA than in previous tournaments. These findings may represent a greater awareness from medical staff and the benefits of education. However, 25% of head injuries not receiving an initial on-field assessment provide room for improvement.

Madagascar's extraordinary biodiversity: Evolution, distribution, and use.

Madagascar's biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar's past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique "living laboratory" for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth's biodiversity.

Madagascar's extraordinary biodiversity: Threats and opportunities.

Madagascar's unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar's terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as the most prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar.

Open access journals are as likely to be referenced by the Orthopaedic literature, despite having a lower impact factor than subscription-based journals.

BACKGROUND: The internet has changed the way we access and publish Orthopaedic literature. Traditional subscription journals have been challenged by the open access method of publication which permits the author to make their article available to all readers for free, often at a cost to the author. This has also been adopted in part by traditional subscription journals forming hybrid journals. One of the criticisms of open access publications is that it provides the author with a "pay to publish" opportunity. We aimed to determine if access to the journals impacts their influence. METHODS: We selected the top 40 Trauma and Orthopaedic Journals as ranked by the SCImago Rank. Each journal was reviewed and assessed for the journal quality, defined by reviewing the journal impact factor and SCImago rank; influence, defined by reviewing the top 10 articles provided by the journal for the number of citations; and cost of open access publication. RESULTS: Of the top 40 journals, 10 were subscription, 10 were open access, and 20 were hybrid journals. Subscription journals had the highest mean impact factor, and SCImago rank with a significant difference in the impact factor (p = 0.001) and SCImago rank (p = 0.021) observed between subscription and open access journals. No significant difference was seen between citation numbers of articles published in subscription and open access journals (p = 0.168). There was a positive correlation between the cost of publishing in an open access journal and the impact factor (r = 0.404) but a negative correlation between cost and the number of citations (r = 0.319). CONCLUSION: Open access journals have significantly lower quality measures in comparison to subscription journals. Despite this, we found no difference between the number of citations, suggestive of there being no difference in the influence of these journals in spite of the observed difference in quality.

From structure to clinic: Design of a muscarinic M1 receptor agonist with potential to treatment of Alzheimer's disease.

Current therapies for Alzheimer's disease seek to correct for defective cholinergic transmission by preventing the breakdown of acetylcholine through inhibition of acetylcholinesterase, these however have limited clinical efficacy. An alternative approach is to directly activate cholinergic receptors responsible for learning and memory. The M1-muscarinic acetylcholine (M1) receptor is the target of choice but has been hampered by adverse effects. Here we aimed to design the drug properties needed for a well-tolerated M1-agonist with the potential to alleviate cognitive loss by taking a stepwise translational approach from atomic structure, cell/tissue-based assays, evaluation in preclinical species, clinical safety testing, and finally establishing activity in memory centers in humans. Through this approach, we rationally designed the optimal properties, including selectivity and partial agonism, into HTL9936-a potential candidate for the treatment of memory loss in Alzheimer's disease. More broadly, this demonstrates a strategy for targeting difficult GPCR targets from structure to clinic.

Loss of functional diversity through anthropogenic extinctions of island birds is not offset by biotic invasions.

Human impacts reshape ecological communities through the extinction and introduction of species. The combined impact of these factors depends on whether non-native species fill the functional roles of extinct species, thus buffering the loss of functional diversity. This question has been difficult to address, because comprehensive information about past extinctions and their traits is generally lacking. We combine detailed information about extinct, extant, and established alien birds to quantify historical changes in functional diversity across nine oceanic archipelagos. We found that alien species often equal or exceed the number of anthropogenic extinctions yet apparently perform a narrower set of functional roles as current island assemblages have undergone a substantial and ubiquitous net loss in functional diversity and increased functional similarity among assemblages. Our results reveal that the introduction of alien species has not prevented anthropogenic extinctions from reducing and homogenizing the functional diversity of native bird assemblages on oceanic archipelagos.

Metatarsalgia: anatomy, pathology and management.

Metatarsalgia is a common presentation, particularly in middle-aged women. This review discusses the anatomical basis and classifies the different pathologies into primary, secondary and iatrogenic. The key elements to differentiate the pathologies within each classification which could cause a patient to suffer with metatarsalgia are outlined. Further investigations are briefly covered, but a linked article discusses the investigations of metatarsalgia in more detail. The article gives an overview of metatarsalgia to help clinicians to investigate and manage these symptoms.

Imaging in metatarsalgia.

Metatarsalgia is a common clinical conundrum that requires careful assessment. There are a variety of causes and understanding these can help manage the pain. These causes have different imaging characteristics and require specific imaging. By understanding core imaging principles and how they apply to causes of metatarsalgia, pathology can be more efficiently investigated. This article covers primary, secondary and iatrogenic causes of metatarsalgia with the most appropriate imaging modalities for each and the salient imaging findings. This article reviews the common forefoot pathologies and how they may be optimally radiologically investigated, with an emphasis on the key imaging findings.

Crystal Structure and Subsequent Ligand Design of a Nonriboside Partial Agonist Bound to the Adenosine A2A Receptor.

In this study, we determined the crystal structure of an engineered human adenosine A2A receptor bound to a partial agonist and compared it to structures cocrystallized with either a full agonist or an antagonist/inverse agonist. The interaction between the partial agonist, belonging to a class of dicyanopyridines, and amino acids in the ligand binding pocket inspired us to develop a small library of derivatives and assess their affinity in radioligand binding studies and potency and intrinsic activity in a functional, label-free, intact cell assay. It appeared that some of the derivatives retained the partial agonist profile, whereas other ligands turned into inverse agonists. We rationalized this remarkable behavior with additional computational docking studies.

Advances in long-wavelength native phasing at X-ray free-electron lasers.

Long-wavelength pulses from the Swiss X-ray free-electron laser (XFEL) have been used for de novo protein structure determination by native single-wavelength anomalous diffraction (native-SAD) phasing of serial femtosecond crystallography (SFX) data. In this work, sensitive anomalous data-quality indicators and model proteins were used to quantify improvements in native-SAD at XFELs such as utilization of longer wavelengths, careful experimental geometry optimization, and better post-refinement and partiality correction. Compared with studies using shorter wavelengths at other XFELs and older software versions, up to one order of magnitude reduction in the required number of indexed images for native-SAD was achieved, hence lowering sample consumption and beam-time requirements significantly. Improved data quality and higher anomalous signal facilitate so-far underutilized de novo structure determination of challenging proteins at XFELs. Improvements presented in this work can be used in other types of SFX experiments that require accurate measurements of weak signals, for example time-resolved studies.

Clinical Outcome of Transtendon Repair of Partial Articular Supraspinatus Tendon Avulsion Tear.

Partial articular supraspinatus tendon avulsion (PASTA) tears are common. However, there is no consensus on the optimal surgical technique for the management of grade 3 tears (>50%). The authors report a retrospective consecutive case series of 64 patients with grade 3 PASTA lesions. The patients were treated by 2 surgeons from 2 centers with the same transtendon repair technique and implant system. The preoperative Oxford Shoulder Score (OSS) was compared with the postoperative OSS at final follow-up (mean, 28 months). Significant improvement in mean OSS occurred from 19.2 (SD, 7.5) preoperatively to 39.8 (SD, 7.8) postoperatively (P=.0001), and patient satisfaction rates were high (88%). The authors believe that transtendon repair of PASTA lesions of 50% or more is beneficial. High-quality randomized controlled trials are required to compare the benefit of repair vs debridement alone. [Orthopedics. 2020;43(6):e533-e537.].

X-Ray Crystallography and Free Energy Calculations Reveal the Binding Mechanism of A2A Adenosine Receptor Antagonists.

We present a robust protocol based on iterations of free energy perturbation (FEP) calculations, chemical synthesis, biophysical mapping and X-ray crystallography to reveal the binding mode of an antagonist series to the A2A adenosine receptor (AR). Eight A2A AR binding site mutations from biophysical mapping experiments were initially analyzed with sidechain FEP simulations, performed on alternate binding modes. The results distinctively supported one binding mode, which was subsequently used to design new chromone derivatives. Their affinities for the A2A AR were experimentally determined and investigated through a cycle of ligand-FEP calculations, validating the binding orientation of the different chemical substituents proposed. Subsequent X-ray crystallography of the A2A AR with a low and a high affinity chromone derivative confirmed the predicted binding orientation. The new molecules and structures here reported were driven by free energy calculations, and provide new insights on antagonist binding to the A2A AR, an emerging target in immuno-oncology.

Comparison of Orexin 1 and Orexin 2 Ligand Binding Modes Using X-ray Crystallography and Computational Analysis.

The orexin system, which consists of the two G protein-coupled receptors OX1 and OX2, activated by the neuropeptides OX-A and OX-B, is firmly established as a key regulator of behavioral arousal, sleep, and wakefulness and has been an area of intense research effort over the past two decades. X-ray structures of the receptors in complex with 10 new antagonist ligands from diverse chemotypes are presented, which complement the existing structural information for the system and highlight the critical importance of lipophilic hotspots and water molecules for these peptidergic GPCR targets. Learnings from the structural information regarding the utility of pharmacophore models and how selectivity between OX1 and OX2 can be achieved are discussed.

Identification of a novel allosteric GLP-1R antagonist HTL26119 using structure- based drug design.

A series of novel allosteric antagonists of the GLP-1 receptor (GLP-1R), exemplified by HTL26119, are described. SBDD approaches were employed to identify HTL26119, exploiting structural understanding of the allosteric binding site of the closely related Glucagon receptor (GCGR) (Jazayeri et al., 2016) and the homology relationships between GCGR and GLP-1R. The region around residue C3476.36b of the GLP-1R receptor represents a key difference from GCGR and was targeted for selectivity for GLP-1R.

Projected losses of global mammal and bird ecological strategies.

Species, and their ecological strategies, are disappearing. Here we use species traits to quantify the current and projected future ecological strategy diversity for 15,484 land mammals and birds. We reveal an ecological strategy surface, structured by life-history (fast-slow) and body mass (small-large) as one major axis, and diet (invertivore-herbivore) and habitat breadth (generalist-specialist) as the other. We also find that of all possible trait combinations, only 9% are currently realized. Based on species' extinction probabilities, we predict this limited set of viable strategies will shrink further over the next 100 years, shifting the mammal and bird species pool towards small, fast-lived, highly fecund, insect-eating, generalists. In fact, our results show that this projected decline in ecological strategy diversity is much greater than if species were simply lost at random. Thus, halting the disproportionate loss of ecological strategies associated with highly threatened animals represents a key challenge for conservation.

Towards high throughput GPCR crystallography: In Meso soaking of Adenosine A2A Receptor crystals.

Here we report an efficient method to generate multiple co-structures of the A2A G protein-coupled receptor (GPCR) with small-molecules from a single preparation of a thermostabilised receptor crystallised in Lipidic Cubic Phase (LCP). Receptor crystallisation is achieved following purification using a low affinity "carrier" ligand (theophylline) and crystals are then soaked in solutions containing the desired (higher affinity) compounds. Complete datasets to high resolution can then be collected from single crystals and seven structures are reported here of which three are novel. The method significantly improves structural throughput for ligand screening using stabilised GPCRs, thereby actively driving Structure-Based Drug Discovery (SBDD).

Agonists and Antagonists of Protease-Activated Receptor 2 Discovered within a DNA-Encoded Chemical Library Using Mutational Stabilization of the Target.

The discovery of ligands via affinity-mediated selection of DNA-encoded chemical libraries is driven by the quality and concentration of the protein target. G-protein-coupled receptors (GPCRs) and other membrane-bound targets can be difficult to isolate in their functional state and at high concentrations, and therefore have been challenging for affinity-mediated selection. Here, we report a successful selection campaign against protease-activated receptor 2 (PAR2). Using a thermo-stabilized mutant of PAR2, we conducted affinity selection using our >100-billion-compound DNA-encoded library. We observed a number of putative ligands enriched upon selection, and subsequent cellular profiling revealed these ligands to comprise both agonists and antagonists. The agonist series shared structural similarity with known agonists. The antagonists were shown to bind in a novel allosteric binding site on the PAR2 protein. This report serves to demonstrate that cell-free affinity selection against GPCRs can be achieved with mutant stabilized protein targets.