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Amyloid plaques composed of extracellular focal deposition of Aβ fibrils are a hallmark of Alzheimer’s disease (AD). Cryo-EM structures of Aβ fibrils purified from human AD brain tissue post mortem have recently been determined. However, the molecular architecture of amyloid plaques in the context of fresh, unfixed mammalian brain tissue is unknown. Here, using cryogenic correlated light and electron tomography we report the native,in situmolecular architecture of Aβ fibrils in the brain of a mouse model containing the Arctic familial AD mutation (AppNL-G-F) and an atomic model of Arctic Aβ fibril purified from the brains of these animals. We show that in-tissue Aβ fibrils are arranged in a lattice or in parallel bundles within a plaque, and are interdigitated by subcellular compartments, exosomes, extracellular droplets and extracellular multilamellar bodies. At the atomic level, the Arctic Aβ fibril differs significantly from earlier structures of Aβ amyloid extracted fromAppNL-Fmice models and human AD brain tissue, showing a striking effect of the Arctic mutation (E22G) on fibril structure. Cryo-electron tomography ofex vivopurified and in-tissue amyloid revealed an ensemble of additional fibrillar species, including thin protofilament-like rods and branched fibrils. Together, these results provide a structural model for the dense network architecture that characterises β-amyloid plaque pathology.

Different tauopathies are characterized by specific amyloid filament folds that are conserved between patients. Disease-specific tau filament folds probably reflect the specific pathological contexts leading to their formation including isoforms or post-translational modifications. Little is known, however, as to whether and how intrinsic conformational tendencies of the tau sequence itself contribute to its polymorphism. Using cryo-EM structure determination we find that a short amyloidogenic C-terminal peptide consisting of residues 350-362 of the tau repeat domain adopts the same polymorphic conformations in isolation as it does in the context of major disease-associated protofilament folds. Biophysical characterisation and molecular modelling show that the amyloid conformations adopted by this peptide constitute core structural motifs stabilizing distinct disease-associated tau filament folds. In accordance this segment also contributes to the efficient propagation of human AD tau seeds in tau reporter cells while it is irrelevant to heparin-induced recombinant seeds. Our findings suggest that tau 350-362 is key to the propagation of disease-associated tau polymorphs and that the conformational preferences of this segment predispose to the topological diversity observed in tau filament folds.

Zusammenfassung Im illegalen Nierenhandel werden Verkaufer oft uber den Tisch gezogen, sie werden genotigt, es wird ihnen angemessene medizinische Betreuung vorenthalten und sie werden uber die Gefahren und die Illegalitat der Nierenentnahme in die Irre gefuhrt. Die Empfanger bezahlen oft fur qualitativ schlechte Operationen sowie ungesunde oder unpassende Nieren. Einige Autoren argumentieren, es sei die Illegalitat, die dieses Leid und dieses Unrecht verursachen, nicht der Handel an sich. Sie argumentieren, die Legalisierung von Nierenverkaufen wurde das Leid verringern. Dieses Leidensverringerungsargument ist es, das in diesem Aufsatz entwickelt und untersucht wird. Es werden zunachst die ethischen und empirischen Bestandteile einer utilitaristischen Version von Leidensverringerung dargelegt. Und es wird erklart, wie eine Legalisierung das Leiden auf Schwarzmarkten vermutlich verringern wurde, aber auch, warum wir nicht wissen, wie die Legalisierung das Angebot an Organen oder die Anzahl leidvoller Transaktionen auf ‘weisen Markten’ beeinflussen wurde. Kurz gesagt, wir konnen nicht sicher sein, dass seine Legalisierung das Leiden insgesamt verringern wurde. Dennoch versucht dieser Aufsatz zu zeigen, dass die Argumentation zugunsten von einer Legalisierung gestarkt werden kann, wenn man dem utilitaristischen Hauptanliegen des aggregierten Wohlergehens etwas hinzufugt. Den besonderen Anliegen der am schlechtesten Gestellten und dem Unrecht des Verkaufsakts kann man durch Legalisierung besser gerecht werden als durch Kriminalisierung. Das Leidensverringerungsargument entscheidet diese Debatte uber die Legalisierung des Organhandels zwar nicht, aber es ist entscheidender als Kritiker bislang zugestehen wollten.

Access to DNA within nucleosomes is required for a variety of processes in cells including transcription, replication and repair. Consequently, cells encode multiple systems that remodel nucleosomes. These complexes can be simple, involving one or a few protein subunits, or more complicated multi-subunit machines 1 . Biochemical studies2–4 have placed the motor domains of several chromatin remodellers in the superhelical location 2 region of the nucleosome. Structural studies of yeast Chd1 and Snf2—a subunit in the complex with the capacity to remodel the structure of chromatin (RSC)—in complex with nucleosomes5–7 have provided insights into the basic mechanism of nucleosome sliding performed by these complexes. However, how larger, multi-subunit remodelling complexes such as INO80 interact with nucleosomes and how remodellers carry out functions such as nucleosome sliding 8 , histone exchange 9 and nucleosome spacing10–12 remain poorly understood. Although some remodellers work as monomers 13 , others work as highly cooperative dimers11, 14, 15. Here we present the structure of the human INO80 chromatin remodeller with a bound nucleosome, which reveals that INO80 interacts with nucleosomes in a previously undescribed manner: the motor domains are located on the DNA at the entry point to the nucleosome, rather than at superhelical location 2. The ARP5–IES6 module of INO80 makes additional contacts on the opposite side of the nucleosome. This arrangement enables the histone H3 tails of the nucleosome to have a role in the regulation of the activities of the INO80 motor domain—unlike in other characterized remodellers, for which H4 tails have been shown to regulate the motor domains.

This paper evaluates a primary care triumvirate leadership programme from the perspectives of key stakeholders (General Practitioners, General Practice Nurses, Practice Managers, programme and practice colleagues); and to provide evidencedinformed recommendations for future primary care triumvirate healthcare leadership development. Kirkpatrick's Four/Five Levels of Evaluation Model was used as the evaluation approach. Data was collected by the use of face to face and telephone focus group interviews. Thematic analysis was used to generate themes relating to the four levels of Kirkpatrick's model. Findings show how adopting a primary care triumvirate leadership approach offers a promising platform for operationalising the contemporary collective and distributed approaches to leadership development. Future programmes could benefit further by adopting a multi-dimensional leadership development model. This would expose the primary care triumvirate leader to the evidence based Six 'E's' approach to leadership development (evaluate, examine, exposure, education, environment, experience).

The RecBCD complex plays key roles in phage DNA degradation, CRISPR array acquisition (adaptation) and host DNA repair. The switch between these roles is regulated by a DNA sequence called Chi. We report cryo-EM structures of the Escherichia coli RecBCD complex bound to several different DNA forks containing a Chi sequence, including one in which Chi is recognised and others in which it is not. The Chi-recognised structure shows conformational changes in regions of the protein that contact Chi and reveals a tortuous path taken by the DNA. Sequence specificity arises from interactions with both the RecC subunit and the sequence itself. These structures provide molecular details for how Chi is recognised and insights into the changes that occur in response to Chi binding that switch RecBCD from bacteriophage destruction and CRISPR spacer acquisition, to constructive host DNA repair.

Summary CRISPR and associated Cas proteins function as an adaptive immune system in prokaryotes to combat bacteriophage infection. During the immunization step, new spacers are acquired by the CRISPR machinery, but the molecular mechanism of spacer capture remains enigmatic. We show that the Cas9, Cas1, Cas2, and Csn2 proteins of a Streptococcus thermophilus type II-A CRISPR-Cas system form a complex and provide cryoelectron microscopy (cryo-EM) structures of three different assemblies. The predominant form, with the stoichiometry Cas18-Cas24-Csn28, referred to as monomer, contains ∼30 bp duplex DNA bound along a central channel. A minor species, termed a dimer, comprises two monomers that sandwich a further eight Cas1 and four Cas2 subunits and contains two DNA ∼30-bp duplexes within the channel. A filamentous form also comprises Cas18-Cas24-Csn28 units (typically 2–6) but with a different Cas1-Cas2 interface between them and a continuous DNA duplex running along a central channel., Graphical Abstract, Highlights • Cryo-EM structures of three different assemblies of the Cas1, Cas2, and Csn2 proteins • One form, with the stoichiometry Cas18-Cas24-Csn28, contains ∼30 bp duplex DNA • Another comprises two of these units with an additional Cas18-Cas24 interface • Filaments comprise Cas18-Cas24-Csn28 units around a continuous DNA duplex, The mechanism of spacer capture by type II CRISPR-Cas systems remains enigmatic. Wilkinson et al. report cryo-EM structures of three macromolecular assemblies of the Cas1, Cas2, and Csn2 proteins. All three complexes contain duplex DNA running along a central channel. A filamentous form contains a continuous duplex and smaller units contain shorter sections of ∼30 bp.

INTRODUCTION Canonical nucleosomes contain two copies of each of four histone proteins: H2A, H2B, H3, and H4. However, variants of these histones can be inserted by adenosine triphosphate (ATP)–dependent chromatin-remodeling machines. The yeast SWR1 chromatin-remodeling complex, a member of the INO80 remodeler family, catalyzes the exchange of H2A-H2B dimers for dimers containing Htz1 (H2A.Z in human) in an ATP-dependent manner. However, the mechanism by which SWR1 exchanges histones is poorly understood. Despite having a DNA translocase subunit similar to that in the INO80 complex that slides nucleosomes, no net translocation of nucleosomes has been reported for SWR1. Consequently, the function of the ATPase activity, which is required for histone exchange in SWR1, has remained enigmatic. RATIONALE To obtain sufficient quantities for structural analysis, we generated the complete 14-subunit yeast SWR1 complex in insect cells. Binding of nucleosomes to SWR1 is stabilized in the presence of an ATP analog (ADP•BeF 3 ), which we used to prepare a complex with a canonical yeast H2A-containing nucleosome. Structural analysis was undertaken by cryo–electron microscopy (cryo-EM). We also used single-molecule FRET (smFRET) techniques to probe the dynamics of nucleosomes bound to SWR1. Fluorescent probes were positioned on the H2A histones and the end of the DNA to monitor changes in nucleosome dynamics upon binding of SWR1 and ATP (or ATP analogs). RESULTS We determined the cryo-EM structure of the SWR1-nucleosome complex at 3.6-A resolution. The architecture of the complex shows how the SWR1 complex is assembled around a heterohexameric core of the RuvBL1 and RuvBL2 subunits. The Swr1 motor subunit binds at superhelical location 2 (SHL2), a position it shares in common with other remodelers but not with its most closely related complex, INO80, which binds at SHL6-SHL7. Binding of ATP or ADP•BeF 3 to the SWR1-nucleosome complex induces substantial unwrapping of the DNA wrap. Conformational changes in the motor domains of the Swr1 subunit drive a single–base pair translocation of the DNA wrap from the DNA entry site. The single–base pair DNA translocation accompanies conformational changes in the histone core that begin to destabilize the histone dimer interface. Using smFRET methods, we further probed these conformational changes to show how an increase in the dynamics of the SWR1-bound nucleosomes is dependent on binding of ATP but not hydrolysis. CONCLUSION The cryo-EM structure of the SWR1 complex bound to a nucleosome reveals details of the intricate interactions between components of the SWR1 complex and its nucleosome substrate. Interactions between the Swr1 motor domains and the DNA wrap at SHL2 distort the DNA, causing a bulge with concomitant translocation of the DNA by one base pair, coupled to conformational changes of the histone core that likely destabilize the dimer interface. Furthermore, partial unwrapping of the DNA from the histone core takes place upon binding of nucleosomes to the SWR1 complex. Single-molecule data monitor this unwrapping and show how the dynamics are altered by ATP binding prior to hydrolysis.

The SALT Building Management System (BMS) was designed to control sub-system cooling and environmental control in the telescope chamber as part of ensuring optimal science data quality. With over 400 inputs and output points for monitoring and control, this required an effective system when performing maintenance in the event of any failure or degradation of the system. The BMS lacked this effectiveness due to an unstructured design and a lack of documentation, causing time-consuming root cause analysis and excessive downtime. In this paper, we describe the research and development of an effective Building Management System.

AddAB and RecBCD-type helicase-nuclease complexes control the first stage of bacterial homologous recombination (HR) – the resection of double strand DNA breaks. A switch in the activities of the complexes to initiate repair by HR is regulated by a short, species-specific DNA sequence known as a Crossover Hotspot Instigator (Chi) site. It has been shown that, upon encountering Chi, AddAB and RecBCD pause translocation before resuming at a reduced rate. Recently, the structure of B.subtilis AddAB in complex with its regulatory Chi sequence revealed the nature of Chi binding and the paused translocation state. Here the structural features associated with Chi binding are described in greater detail and discussed in relation to the related E.coli RecBCD system.

Our previous paper (Wilkinson et al, 2016) used high-resolution cryo-electron microscopy to solve the structure of the Escherichia coli RecBCD complex, which acts in both the repair of double-stranded DNA breaks and the degradation of bacteriophage DNA. To counteract the latter activity, bacteriophage λ encodes a small protein inhibitor called Gam that binds to RecBCD and inactivates the complex. Here, we show that Gam inhibits RecBCD by competing at the DNA-binding site. The interaction surface is extensive and involves molecular mimicry of the DNA substrate. We also show that expression of Gam in E. coli or Klebsiella pneumoniae increases sensitivity to fluoroquinolones; antibacterials that kill cells by inhibiting topoisomerases and inducing double-stranded DNA breaks. Furthermore, fluoroquinolone-resistance in K. pneumoniae clinical isolates is reversed by expression of Gam. Together, our data explain the synthetic lethality observed between topoisomerase-induced DNA breaks and the RecBCD gene products, suggesting a new co-antibacterial strategy.

Although the terms 'health' and 'healthy' are often applied to marine ecosystems and communicate information about holistic condition (e.g. as required by the Ecosystem Approach), their meaning is unclear. Ecosystems have been understood in various ways, from non-interacting populations of species to complex integrated systems. Health has been seen as a metaphor, an indicator that aggregates over system components, or a non-localized emergent system property. After a review, we define good ecosystem health as: 'the condition of a system that is self-maintaining, vigorous, resilient to externally imposed pressures, and able to sustain services to humans. It contains healthy organisms and populations, and adequate functional diversity and functional response diversity. All expected trophic levels are present and well interconnected, and there is good spatial connectivity amongst subsystems.' We equate this condition with good ecological or environmental status, e.g. as referred to by recent EU Directives. Resilience is central to health, but difficult to measure directly. Ecosystems under anthropogenic pressure are at risk of losing resilience, and thus of suffering regime shifts and loss of services. For monitoring whole ecosystems, we propose an approach based on 'trajectories in ecosystem state space', illustrated with time-series from the northwestern North Sea. Change is visualized as Euclidian distance from an arbitrary reference state. Variability about a trend in distance is used as a proxy for inverse resilience. We identify the need for institutional support for long time-series to underpin this approach, and for research to establish state space co-ordinates for systems in good health. Changes in the northern North Sea, 1958-2008, plotted in a state space defined by the breeding success of kittiwakes, abundance of copepods Calanus spp., and simulated annual primary production.© Inter-Research 2013. www.int-res.com.

ResumoEste estudo centra-se em caracteristicas de comunidades de macroalgas do intertidal rochoso para avaliacao da qualidade ecologica das massasde aguas co...

The SALT Tracker was originally designed to carry a payload of approximately 1000 kg. The current loading exceeds 1300 kg and more instrumentation, for example, the Near-Infrared (NIR) arm of the Robert Stobie Spectrograph (RSS), is being designed for the telescope. In general, provision also had to be made to expand the envelope of the tracker payload carrying capacity for future growth as some of the systems on SALT are currently running with small safety margins. It was therefore decided to upgrade the SALT Tracker to be able to carry a payload of 1875 kg. Before the project "Kick-Off" it became evident that neither SALT nor SAAO had the required standard of formal processes and procedures to execute a project of this nature. The Project Management, Mechanical Design and Review processes and procedures were adopted from the Aerospace Industry and tailored for our application. After training the project team in the application of these processes/procedures and gaining their commitment, the Tracker Upgrade Project was "Kicked-Off" in early May 2013. The application of these aerospace-derived processes and procedures, as used during the Tracker Upgrade Project, were very successful as is shown in this paper where the authors also highlight some of the details of the implemented processes and procedures as well as specific challenges that needed to be met while executing a project of this nature and technical complexity.

Following successful commissioning of the SALT Fiber Instrument Feed guidance system, the concept was developed further to re-design the guidance probe currently supporting observations with the Robert Stobie Spectrograph. Major advances of the new system include a compact, modular and line-replaceable design, high optical efficiency, a doubleprobe positioning system allowing both translation and rotation guidance corrections as well as closed-loop focus feedback. The mechanical and optical designs, the control system architecture and performance aspects of the system are presented. The probe‘s integration with the greater telescope software control system is also discussed.

Liquid lens coupling provides excellent transmission efficiency when compared to multilayer coatings especially for applications where broadband transmission is required. However, long term reliability of liquid coupling is difficult to achieve. This is typically due to chemical compatibility issues affecting both the optical transmission and the integrity of the opto-mechanical support. As part of a recent service of the Robert Stobie Spectrograph on SALT we had the opportunity to study these problems further and in this paper we provide analysis of problems identified and some solutions to prevent them. We also present general guidelines which could aid future opto-mechanical designs for liquid coupling of lenses.

The volcanic origin of the Azores archipelago (Portugal) gives rise to active deep sea and shallow water hydrothermal activity that affects benthic communities. Intertidal seaweed surveys were conducted at two shores affected by intense shallow water hydrothermal vents. Water temperature, acidity and salinity were monitored. Seaweed communities were found to be species poor and have a disproportionally larger number of filamentous early successional species on shores that are subject to the effect of hot and acidic freshwater of volcanic origin. There is an ecological resemblance between hydrothermally affected seaweed communities in the Azores and those affected by acid mine drainage in the UK, thus indicating that hydrothermalism can be a useful scenario for pollution studies under conditions of ocean warming and acidification.

Objectives: This study aimed to evaluate the validity and utility of and candidate reactions towards cognitive ability tests, and current selection methods, including a clinical problem-solving test (CPST) and a situational judgement test (SJT), for postgraduate selection. Methods: This was an exploratory, longitudinal study to evaluate the validities of two cognitive ability tests (measuring general intelligence) compared with current selection tests, including a CPST and an SJT, in predicting performance at a subsequent selection centre (SC). Candidate reactions were evaluated immediately after test administration to examine face validity. Data were collected from candidates applying for entry into training in UK general practice (GP) during the 2009 recruitment process. Participants were junior doctors (n = 260). The mean age of participants was 30.9 years and 53.1% were female. Outcome measures were participants’ scores on three job simulation exercises at the SC. Results: Findings indicate that all tests measure overlapping constructs. Both the CPST and SJT independently predicted more variance than the cognitive ability test measuring non-verbal mental ability. The other cognitive ability test (measuring verbal, numerical and diagrammatic reasoning) had a predictive value similar to that of the CPST and added significant incremental validity in predicting performance on job simulations in an SC. The best single predictor of performance at the SC was the SJT. Candidate reactions were more positive towards the CPST and SJT than the cognitive ability tests. Conclusions: In terms of operational validity and candidate acceptance, the combination of the current CPST and SJT proved to be the most effective administration of tests in predicting selection outcomes. In terms of construct validity, the SJT measures procedural knowledge in addition to aspects of declarative knowledge and fluid abilities and is the best single predictor of performance in the SC. Further research should consider the validity of the tests in this study in predicting subsequent performance in training.

In bacteria, the repair of double-stranded DNA breaks is modulated by Chi sequences. These are recognised by helicase-nuclease complexes that process DNA ends for homologous recombination. Chi activates recombination by changing the biochemical properties of the helicase-nuclease, transforming it from a destructive exonuclease into a recombination-promoting repair enzyme. This transition is thought to be controlled by the Chi-dependent opening of a molecular latch, which enables part of the DNA substrate to evade degradation beyond Chi. Here, we show that disruption of the latch improves Chi recognition efficiency and stabilizes the interaction of AddAB with Chi, even in mutants that are impaired for Chi binding. Chi recognition elicits a structural change in AddAB that maps to a region of AddB which resembles a helicase domain, and which harbours both the Chi recognition locus and the latch. Mutation of the latch potentiates the change and moderately reduces the duration of a translocation pause at Chi. However, this mutant displays properties of Chi-modified AddAB even in the complete absence of bona fide hotspot sequences. The results are used to develop a model for AddAB regulation in which allosteric communication between Chi binding and latch opening ensures quality control during recombination hotspot recognition.

Let’s face it, being a GP is not good for your health. Many hours are spent sitting staring at a computer screen with only the occasional unhealthy snack for sustenance. The popularity of fitness apps has led me to rethink the wisdom of prolonged sitting at work and to increase my daily steps. I decided to stop using the intercom to call patients and, instead, walk to the waiting room and call them in person. No longer: ‘Jane Smith, room 4!’ but rather: ‘Hello Jane, nice to see you, you look like you caught the rain today …’ Thirty plus steps a day for 30 patients increases my count, and with additional activity plus minor detours this equates to an additional 2000 daily steps. Patients often enquire whether the intercom is broken. I respond with a self-satisfied glow, ‘I’m trying to do more exercise and keep active.’ They appear impressed with my simple example of modifying one’s behaviour to improve health. Thirty seconds extra …

Shallow water hydrothermal vents can be compared to polluted places due to high concentrations of heavy metals, and are thus good models for bioaccumulation studies. The present study intended to estimate the time of exposure required for the accumulation of certain elements to stabilize in specimens of Cystoseira abies-marina, to be used as a reference in future work. Cystoseira abies-marina intertidal specimens were transplanted from Mosteiros (a non-hydrothermal and pristine site) to Ferraria (with hydrothermal activity) and left there. Transplanted samples were collected after 1, 2, 4 and 8 weeks and the concentrations of Cd, Mg, Mn and Zn were measured through flame atomic absorption spectrophotometry. Although further studies with increased periods of exposure are needed because the concentration of these elements never stabilized in the collected samples, there is strong evidence that increased time of exposure led to increased concentrations of Cd, Mg, Mn, but not Zn. These results are consistent with the assumption that C. abies-marina is bioaccumulating some of the heavy metals and can thus be a good indicator for polluted waters.

This is the first account of the effects of drainage water from an abandoned coal mine on the seaweed community of the intertidal rocky shore in the British Isles. At St Monans, Scotland, along a 250 m transect, the brown climax species Fucus spiralis showed a low abundance in sampling quadrats (17.5%) and small plant size (3.5 cm), close to the outfall, compared to stations at increasing distance from the drainage source. Immediately below the outfall the fucoid community was replaced by a mixture of 12 species of freshwater, brackish and marine Chlorophyta, which did not occur, or only scarcely occurred, at any other transect station. At high tide, ferrous iron concentrations in the water were highest near the source (15.5 mg/l), while salinity was at its lowest (1.1 psu). Accordingly, iron tissue concentrations of apical segments of F. spiralis were also at their highest (12 mg Fe/g dry weight). Reproductive development of F. spiralis may have been inhibited close to the source.

The EC Water Framework Directive requires that ecological quality be assessed in transitional waters using the abundance and species composition of macroalgae. In estuaries, which form the majority of transitional waters, species composition is not a suitable measure. This arises from two features: (i) there is a continuous, natural change in species composition along the gradient of estuarine conditions which makes it difficult to know where within an estuary the species composition should be assessed, (ii) the inner estuarine macroalgal community of mat-forming species is very tolerant to both natural and anthropogenic stress and species poor which makes it insensitive to environmental variations in terms of species composition. An alternative feature is proposed based on the extent of upstream penetration of perennial fucoid algae. This proposal is founded on a series of case studies of the changes in fucoid limits, within a number of estuaries in the British Isles, consequent upon changes in pollution status over the last three decades. This also has to take into account variations of fucoid penetration owing to natural factors such as range of salinity variation and turbidity. The abundance criterion is taken to mean the absence of macroalgal blooms or "green tides", because general abundance of species is hard to quantify meaningfully in the upper estuarine mat-forming species and in the lower estuary is subject to great variation owing to the physical variability of estuary types.

Acute pancreatitis (AP) is a common and devastating inflammatory condition of the pancreas that is considered to be a paradigm of sterile inflammation leading to systemic multiple organ dysfunction syndrome (MODS) and death1,2. Acute mortality from AP-MODS exceeds 20% (ref. 3), and the lifespans of those who survive the initial episode are typically shorter than those of the general population4. There are no specific therapies available to protect individuals from AP-MODS. Here we show that kynurenine-3-monooxygenase (KMO), a key enzyme of tryptophan metabolism5, is central to the pathogenesis of AP-MODS. We created a mouse strain that is deficient for Kmo (encoding KMO) and that has a robust biochemical phenotype that protects against extrapancreatic tissue injury to the lung, kidney and liver in experimental AP-MODS. A medicinal chemistry strategy based on modifications of the kynurenine substrate led to the discovery of the oxazolidinone GSK180 as a potent and specific inhibitor of KMO. The binding mode of the inhibitor in the active site was confirmed by X-ray co-crystallography at 3.2 Å resolution. Treatment with GSK180 resulted in rapid changes in the levels of kynurenine pathway metabolites in vivo, and it afforded therapeutic protection against MODS in a rat model of AP. Our findings establish KMO inhibition as a novel therapeutic strategy in the treatment of AP-MODS, and they open up a new area for drug discovery in critical illness.

Background. Early virological response to antiretroviral therapy is predictive of long-term treatment outcome in therapy-naive patients. In treatment-experienced patients, such correlations are less well defined, because initial responses may be less pronounced and transient because of accumulated cross-resistance to prior therapies. Our objectives were to explore how the virological and immunological status of treatment-experienced patients at an early time point (week 12) during enfuvirtide-based therapy predicted their responses at weeks 24, 48, and 96 in the T-20 versus Optimized Regimen Only (TORO) trials. Methods. Post hoc, modified, on-treatment and intent-to-treat analyses were performed to determine whether the relationship between virological and immunological outcomes at weeks 24, 48, and 96 were predicted by the patients' week-12 responses to therapy. Results. Using a modified on-treatment analysis for patients who, by week 12, achieved a decrease in their HIV-1 RNA load of ≥1 log 10 copies/mL, 39.2% (95% CI, 33.6%-44.8%) and 59.5% (95% CI, 53.8%-65.1%) achieved a viral load of

(2012). Mentoring for doctors in difficulty. Education for Primary Care: Vol. 23, No. 2, pp. 87-89.

The Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS) is a fibre-fed R4 echelle spectrograph employing a white pupil design with red and blue channels for wavelength coverage from 370–890nm. The instrument has four modes, each with object and sky fibres: Low (R~15000), Medium (R~40000) and High Resolution (R~65000), as well as a High Stability mode for enhanced radial velocity precision at R~65000. The High Stability mode contains a fibre double-scrambler and offers optional simultaneous Th-Ar arc injection, or the inclusion of an iodine cell in the beam. The LR mode has unsliced 500μm fibres and makes provision for nod-and-shuffle for improved background subtraction. The MR mode also uses 500μm fibres, while the HR and HS fibres are 350μm. The latter three modes employ modified Bowen-Walraven image-slicers to subdivide each fibre into three slices. All but the High Stability bench is sealed within a vacuum tank, which itself is enclosed in an interlocking Styrostone enclosure, to insulate the spectrograph against temperature and atmospheric pressure variations. The Fibre Instrument Feed (FIF) couples the four pairs of fibres to the telescope focal plane and allows the selection of the appropriate fibre pair for a given mode, and adjustment of the fibre separation to optimally position the sky fibre. The HRS employs a photomultiplier tube for an exposure meter and has a dedicated auto-guider attached to the FIF. We report here on the commissioning results and overall instrument performance since achieving first light on 28 September 2013.

In bacterial cells, processing of double-stranded DNA breaks for repair by homologous recombination is dependent upon the recombination hotspot sequence χ (Chi)1, 2 and is catalysed by either an AddAB- or RecBCD-type helicase–nuclease (reviewed in refs 3, 4). These enzyme complexes unwind and digest the DNA duplex from the broken end until they encounter a χ sequence5, whereupon they produce a 3′ single-stranded DNA tail onto which they initiate loading of the RecA protein6. Consequently, regulation of the AddAB/RecBCD complex by χ is a key control point in DNA repair and other processes involving genetic recombination. Here we report crystal structures of Bacillus subtilis AddAB in complex with different χ-containing DNA substrates either with or without a non-hydrolysable ATP analogue. Comparison of these structures suggests a mechanism for DNA translocation and unwinding, suggests how the enzyme binds specifically to χ sequences, and explains how χ recognition leads to the arrest of AddAB (and RecBCD) translocation that is observed in single-molecule experiments7, 8, 9.

Opposition to inducement payments for research subjects is an international orthodoxy amongst writers of ethics committee guidelines. We offer an argument in favour of these payments. We also critically evaluate the best arguments we can find or devise against such payments, and except in one very limited range of circumstances, we find these unconvincing.