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Immobilisation of torus fractures of the wrist in children (FORCE): a randomised controlled equivalence trial in the UK.
BACKGROUND: The most common fractures in children are torus (buckle) fractures of the wrist. Controversy exists over treatment, which ranges from splint immobilisation and discharge to cast immobilisation, follow-up, and repeat imaging. This study compared pain and function in affected children offered a soft bandage and immediate discharge with those receiving rigid immobilisation and follow-up as per treating centre protocol. METHODS: In this randomised controlled equivalence trial we included 965 children (aged 4-15 years) with a distal radius torus fracture from 23 hospitals in the UK. Children were randomly allocated in a 1:1 ratio to the offer of bandage group or rigid immobilisation group using bespoke web-based randomisation software. Treating clinicians, participants, and their families could not be masked to treatment allocation. Exclusion criteria included multiple injuries, diagnosis at more than 36 h after injury, and inability to complete follow-up. The primary outcome was pain at 3-days post-randomisation measured using Wong-Baker FACES Pain Rating Scale. We performed a modified intention-to-treat and per protocol analysis. The trial was registered with ISRCTN registry, ISRCTN13955395. FINDINGS: Between Jan 16, 2019, and July 13, 2020, 965 children were randomly allocated to a group, 489 to the offer of a bandage group and 476 to the rigid immobilisation group, 379 (39%) were girls and 586 (61%) were boys. Primary outcome data was collected for 908 (94%) of participants, all of whom were included in the modified intention-to-treat analysis. Pain was equivalent at 3 days with 3·21 points (SD 2·08) in the offer of bandage group versus 3·14 points (2·11) in the rigid immobilisation group. With reference to a prespecified equivalence margin of 1·0, the adjusted difference in the intention-to-treat population was -0·10 (95% CI -0·37 to 0·17) and-0·06 (95% CI -0·34 to 0·21) in the per-protocol population. INTERPRETATION: This trial found equivalence in pain at 3 days in children with a torus fracture of the distal radius assigned to the offer of a bandage group or the rigid immobilisation group, with no between-group differences in pain or function during the 6 weeks of follow-up. FUNDING: UK National Institute for Health and Care Research.
Formation and closure of macropinocytic cups in Dictyostelium.
Macropinocytosis is a conserved endocytic process by which cells engulf droplets of medium into micron-sized vesicles. We use light-sheet microscopy to define an underlying set of principles by which macropinocytic cups are shaped and closed in Dictyostelium amoebae. Cups form around domains of PIP3 stretching almost to their lip and are supported by a specialized F-actin scaffold from lip to base. They are shaped by a ring of actin polymerization created by recruiting Scar/WAVE and Arp2/3 around PIP3 domains, but how cups evolve over time to close and form a vesicle is unknown. Custom 3D analysis shows that PIP3 domains expand from small origins, capturing new membrane into the cup, and crucially, that cups close when domain expansion stalls. We show that cups can close in two ways: either at the lip, by inwardly directed actin polymerization, or the base, by stretching and delamination of the membrane. This provides the basis for a conceptual mechanism whereby closure is brought about by a combination of stalled cup expansion, continued actin polymerization at the lip, and membrane tension. We test this through the use of a biophysical model, which can recapitulate both forms of cup closure and explain how 3D cup structures evolve over time to mediate engulfment.
Tools to Image Germplasm Dynamics During Early Zebrafish Development
During the first day of zebrafish development, ribonucleoprotein (RNP) complexes called germplasm form large aggregates that initially segregate asymmetrically during cleavage stages. After zygotic genome activation, the granules break into smaller fragments that associate with the nuclear membrane as perinuclear (germ) granules toward the end of gastrulation. The mechanisms underlying the highly dynamic behavior of germ granules are not well studied but thought to be facilitated by the cytoskeleton. Here, we present efficient mounting strategies using 3d-printed tools that generate wells on agarose-coated sample holders to allow high-resolution imaging of multiplexed embryos that are less than one day post-fertilization (dpf) on inverted (spinning disk confocal) as well as upright (lattice light-sheet and diSPIM) microscopes. In particular, our tools and methodology allow water dipping lenses to have direct access to mounted embryos, with no obstructions to the light path (e.g., through low melting agarose or methyl cellulose). Moreover, the multiplexed tight arrays of wells generated by our tools facilitate efficient mounting of early embryos (including cleavage stages) for live imaging. These methods and tools, together with new transgenic reporter lines, can facilitate the study of germ granule dynamics throughout their lifetime in detail, at high resolution and throughput, using live imaging technologies.
CENP-F stabilizes kinetochore-microtubule attachments and limits dynein stripping of corona cargoes
Accurate chromosome segregation demands efficient capture of microtubules by kinetochores and their conversion to stable bioriented attachments that can congress and then segregate chromosomes. An early event is the shedding of the outermost fibrous corona layer of the kinetochore following microtubule attachment. Centromere protein F (CENP-F) is part of the corona, contains two microtubule-binding domains, and physically associates with dynein motor regulators. Here, we have combined CRISPR gene editing and engineered separation-of-function mutants to define how CENP-F contributes to kinetochore function. We show that the two microtubule-binding domains make distinct contributions to attachment stability and force transduction but are dispensable for chromosome congression. We further identify a specialized domain that functions to limit the dynein-mediated stripping of corona cargoes through a direct interaction with Nde1. This antagonistic activity is crucial for maintaining the required corona composition and ensuring efficient kinetochore biorientation.
Controlling Anomalous Diffusion in Lipid Membranes.
Diffusion in cell membranes is not just simple two-dimensional Brownian motion but typically depends on the timescale of the observation. The physical origins of this anomalous subdiffusion are unresolved, and model systems capable of quantitative and reproducible control of membrane diffusion have been recognized as a key experimental bottleneck. Here, we control anomalous diffusion using supported lipid bilayers containing lipids derivatized with polyethylene glycol (PEG) headgroups. Bilayers with specific excluded area fractions are formed by control of PEG lipid mole fraction. These bilayers exhibit a switch in diffusive behavior, becoming anomalous as bilayer continuity is disrupted. Using a combination of single-molecule fluorescence and interferometric imaging, we measure the anomalous behavior in this model over four orders of magnitude in time. Diffusion in these bilayers is well described by a power-law dependence of the mean-square displacement with observation time. Anomaleity in this system can be tailored by simply controlling the mole fraction of PEG lipid, producing bilayers with diffusion parameters similar to those observed for anomalous diffusion in biological membranes.
Urea-mediated anomalous diffusion in supported lipid bilayers.
Diffusion in biological membranes is seldom simply Brownian motion; instead, the rate of diffusion is dependent on the time scale of observation and so is often described as anomalous. In order to help better understand this phenomenon, model systems are needed where the anomalous diffusion of the lipid bilayer can be tuned and quantified. We recently demonstrated one such model by controlling the excluded area fraction in supported lipid bilayers (SLBs) through the incorporation of lipids derivatized with polyethylene glycol. Here, we extend this work, using urea to induce anomalous diffusion in SLBs. By tuning incubation time and urea concentration, we produce bilayers that exhibit anomalous behaviour on the same scale as that observed in biological membranes.
Psoriatic arthritis flare incidence, definition and risk factors: a systematic review.
OBJECTIVES: We systematically reviewed the literature to identify the incidence of psoriatic arthritis (PsA) flare, criteria used to define it, and associated risk factors. METHODS: Databases of Embase, Medline ALL, Web of Science Core Collection and Cochrane Central Register of Controlled Trials were searched until September 2023, for original articles studying PsA flare. The Newcastle Ottawa scale was used to assess the quality of included studies. RESULTS: Fifty-four studies of cohort, cross-sectional, and clinical trial designs were included. Twelve studies assessed PsA flare rates, 28 assessed risk factors, and 44 defined flare. The prevalence of current flare ranged between 7%-50% (n = 8), while the incidence ranged between 10%-27% over 6 months (n = 3), and 22%-23% over 12 months (n = 2). Based on high-quality scoring, the current patient-reported flare was 10% (n = 1), while current physician-reported flare was 7% with 22%-23% incidence rate over 12 months (n = 2). Criteria used in flare definition could be grouped into seven categories, with disease activity scores (36%), patient-reported (39%) and physician-reported (30%) flare, and change in therapy (25%) being frequently used. Risk factors could be grouped into four categories: arthritis therapies, SARS-CoV, PsA features, and other. The factors showed limited or unclear evidence. CONCLUSION: The current prevalence of flare ranged between 7%-10%, and the annual incidence was 22%-23%, based on high-quality scoring. Forty-four studies defined flare, revealing no consensus on a single flare definition, and highlighting the need for a standardized definition. No conclusions could be drawn on risk factors, highlighting the need for further research. PROSPERO REGISTRATION: CRD42024482657.
Attribution of causality in Stevens-Johnson syndrome/toxic epidermal necrolysis.
Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is an acute, severe immunobullous disorder of skin and mucous membranes that is most commonly induced by exposure to drugs. Causation of SJS/TEN is most often determined by the "algorithm of drug causality for epidermal necrolysis" (ALDEN) tool. However, concerns remain regarding the precision of ALDEN and causality assessment tools, potentially impacting ongoing studies attempting to link specific genotypes with specific drug classes as causes. To determine whether a standard of care exists in attribution of causation in SJS/TEN, we performed a narrative review of current concepts on causation in SJS/TEN, and available clinical and laboratory assessment tools for attributing causation. We found that current SJS/TEN causality attribution tools, including ALDEN, are somewhat limited by underlying assumptions. The utility of ex vivo tests proposed for determining causation in SJS/TEN, specifically the lymphocyte transformation test and cytokine stimulation assays, remain under investigation and are either not tractable for acute SJS/TEN or are not yet validated. In summary, a critical unmet need exists in the care of SJS/TEN patients, namely the difficulty in determining a precise cause in any specific individual. This shortfall limits the clinician's ability to discontinue only the causal agent in the acute phase, confounds studies of pathogenesis, and leaves affected patients in the chronic phase without knowing which drug or drug class is safe to use in the future. Further studies are needed to close this critical gap in the care of this devastating disease.
Harmonization of Diagnostic Criteria in Mastocytosis for Use in Clinical Practice: WHO vs ICC vs AIM/ECNM.
Mastocytosis is a clonal myeloid disorder defined by an increase and accumulation of mast cells (MCs) in one or multiple organ systems. The complex pathology of mastocytosis results in variable clinical presentations, courses, and outcomes. The World Health Organization (WHO) divides the disease into cutaneous mastocytosis (CM), several forms of systemic mastocytosis (SM), and MC sarcoma. In most patients with SM, a somatic KIT mutation, usually D816V, is identified. Patients diagnosed with CM or nonadvanced SM, including indolent SM, have a near-normal life expectancy, whereas those with advanced SM, including aggressive SM and MC leukemia, have limited life expectancy. Since 2001, a multidisciplinary consensus group consisting of experts from the European Competence Network on Mastocytosis and the American Initiative in Mast Cell Diseases has supported the field by developing diagnostic criteria for mastocytosis. These criteria served as the basis for the WHO classification of mastocytosis over 2 decades. More recently, an International Consensus Classification group proposed slightly modified diagnostic criteria and a slightly revised classification. In this article, these changes are discussed. Furthermore, we propose harmonization among the proposals of the American Initiative in Mast Cell Diseases/European Competence Network on Mastocytosis consensus group, WHO, and the International Consensus Classification Group. Such harmonization will facilitate comparisons of retrospective study results and the conduct of prospective trials.
Restricted plant diversity limits carbon recapture after wildfire in warming boreal forests
Incomplete wildfire combustion in boreal forests leaves behind legacy plant-soil feedbacks known to restrict plant biodiversity. These restrictions can inhibit carbon recapture after fire by limiting ecosystem transition to vegetation growth patterns that are capable of offsetting warmth-enhanced soil decomposition under climate change. Here, we field-surveyed plant regrowth conditions 2 years after 49 separate, naturally-occurring wildfires spanning the near-entire climatic range of boreal Fennoscandia in order to determine the local to regional scale drivers of early vegetation recovery. Minimal conifer reestablishment was found across a broad range of fire severities, though residual organic soil and plant structure was associated with restricted growth of a variety of more warmth-adapted vegetation, such as broadleaf trees. This dual regeneration limitation coincided with greater concentrations of bacterial decomposers in the soil under increased mean annual temperature, potentially enhancing soil carbon release. These results suggest that large portions of the boreal region are currently at risk of extending postfire periods of net emissions of carbon to the atmosphere under limitations in plant biodiversity generated by wildfire and a changing climate.
Evaluating the impact of artificial intelligence-assisted image analysis on the diagnostic accuracy of front-line clinicians in detecting fractures on plain X-rays (FRACT-AI): protocol for a prospective observational study.
INTRODUCTION: Missed fractures are the most frequent diagnostic error attributed to clinicians in UK emergency departments and a significant cause of patient morbidity. Recently, advances in computer vision have led to artificial intelligence (AI)-enhanced model developments, which can support clinicians in the detection of fractures. Previous research has shown these models to have promising effects on diagnostic performance, but their impact on the diagnostic accuracy of clinicians in the National Health Service (NHS) setting has not yet been fully evaluated. METHODS AND ANALYSIS: A dataset of 500 plain radiographs derived from Oxford University Hospitals (OUH) NHS Foundation Trust will be collated to include all bones except the skull, facial bones and cervical spine. The dataset will be split evenly between radiographs showing one or more fractures and those without. The reference ground truth for each image will be established through independent review by two senior musculoskeletal radiologists. A third senior radiologist will resolve disagreements between two primary radiologists. The dataset will be analysed by a commercially available AI tool, BoneView (Gleamer, Paris, France), and its accuracy for detecting fractures will be determined with reference to the ground truth diagnosis. We will undertake a multiple case multiple reader study in which clinicians interpret all images without AI support, then repeat the process with access to AI algorithm output following a 4-week washout. 18 clinicians will be recruited as readers from four hospitals in England, from six distinct clinical groups, each with three levels of seniority (early-stage, mid-stage and later-stage career). Changes in the accuracy, confidence and speed of reporting will be compared with and without AI support. Readers will use a secure web-based DICOM (Digital Imaging and Communications in Medicine) viewer (www.raiqc.com), allowing radiograph viewing and abnormality identification. Pooled analyses will be reported for overall reader performance as well as for subgroups including clinical role, level of seniority, pathological finding and difficulty of image. ETHICS AND DISSEMINATION: The study has been approved by the UK Healthcare Research Authority (IRAS 310995, approved on 13 December 2022). The use of anonymised retrospective radiographs has been authorised by OUH NHS Foundation Trust. The results will be presented at relevant conferences and published in a peer-reviewed journal. TRIAL REGISTRATION NUMBERS: This study is registered with ISRCTN (ISRCTN19562541) and ClinicalTrials.gov (NCT06130397). The paper reports the results of a substudy of STEDI2 (Simulation Training for Emergency Department Imaging Phase 2).