Accuracy of PE rule-out strategies in pregnancy : secondary analysis of the DiPEP study prospective cohort

ObjectiveRecent studies suggest that combinations of clinical probability assessment (the YEARS algorithm or Geneva score) and D-dimer can safely rule out suspected pulmonary embolism (PE) in pregnant women. We performed a secondary analysis of the DiPEP (Diagnosis of Pulmonary Embolism in Pregnancy) study data to determine the diagnostic accuracy of these strategies.MethodsThe DiPEP study prospectively recruited and collected data and blood samples from pregnant/postpartum women with suspected PE across 11 hospitals and retrospectively collected data from pregnant/postpartum women with diagnosed PE across all UK hospitals (15 February 2015 to 31 August 2016). We selected prospectively recruited pregnant women who had definitive diagnostic imaging for this analysis. We used clinical data and D-dimer results to determine whether the rule out strategies would recommend further investigation. Two independent adjudicators used data from imaging reports, treatments and adverse events up to 30 days to determine the reference standard.ResultsPEs were diagnosed in 12/219 (5.5%) women. The YEARS/D-dimer strategy would have ruled out PE in 96/219 (43.8%) but this would have included 5 of the 12 with PEs. Sensitivity for PE was 58.3% (95% CI 28.6% to 83.5%) and specificity 44.0% (37.1% to 51.0%). The Geneva/D-dimer strategy would have ruled out PE in 46/219 (21.0%) but this would have included three of the 12 with PE. Sensitivity was 75.0% (95% CI 42.8% to 93.3%) and specificity 20.8% (95% CI 15.6% to 27.1%). Administration of anticoagulants prior to blood sampling may have reduced D-dimer sensitivity for small PE.ConclusionStrategies using clinical probability and D-dimer have limited diagnostic accuracy and do not accurately rule out all PE in pregnancy. It is uncertain whether PE missed by these strategies lead to clinically important consequences.</jats:sec

Classical, novel and atypical isoforms of PKC stimulate ANF- and TRE/AP-1-regulated-promoter activity in ventricular cardiomyocytes

Cultured neonatal rat ventricular myocytes were co-transfected with expression plasmids encoding protein kinase C (PKC) isoforms from each of the PKC subfamilies (classical PKC-α, novel PKC-ε or atypical PKC-ξ) together with an atrial natriuretic factor (ANF) reporter plasmid. Each PKC had been rendered constitutively active by a single Ala→Glu mutation or a small deletion in the inhibitory pseudosubstrate site. cPKC-α, nPKC-ε or aPKC-ξ expression plasmids each stimulated ANF-promoter activity and expression of a reporter gene under the control of a 12-O-tetradecanoylphorbol 13-acetate-response element (TRE). Upregulation of the ANF promoter is characteristic of the hypertrophic response in the heart ventricle and a TRE is present in the ANF promoter. Thus all subfamilies of PKC may have the potential to contribute to hypertrophic response in cardiomyocytes

Predicting the response of plates subjected to near-field explosions using an energy equivalent impulse

Recent experimental work by the current authors has provided highly spatially and temporally resolved measurements of the loading imparted to, and the subsequent dynamic response of, structures subjected to near-field explosive loading [1]. In this article we validate finite element models of plates subjected to near-field blast loads and perform a parametric study into the relationship between imparted load and peak and residual plate deformation. The energy equivalent impulse is derived, based on the theory of upper bound kinetic energy uptake introduced herein, which accounts for the additional energy imparted to a structure from a spatially non-uniform blast load. Whilst plate deflection is weakly correlated to total impulse, there is shown to be a strong positive correlation between deflection and energy equivalent impulse. The strength of this correlation is insensitive to loading distribution and mode of response. The method developed in this article has clear applications for the generation of fast-running engineering tools for the prediction of structural response to near-field explosions

Using X-ray Crystallography, Biophysics, and Functional Assays to Determine the Mechanisms Governing T-cell Receptor Recognition of Cancer Antigens.

Human CD8+ cytotoxic T lymphocytes (CTLs) are known to play an important role in tumor control. In order to carry out this function, the cell surface-expressed T-cell receptor (TCR) must functionally recognize human leukocyte antigen (HLA)-restricted tumor-derived peptides (pHLA). However, we and others have shown that most TCRs bind sub-optimally to tumor antigens. Uncovering the molecular mechanisms that define this poor recognition could aid in the development of new targeted therapies that circumnavigate these shortcomings. Indeed, present therapies that lack this molecular understanding have not been universally effective. Here, we describe methods that we commonly employ in the laboratory to determine how the nature of the interaction between TCRs and pHLA governs T-cell functionality. These methods include the generation of soluble TCRs and pHLA and the use of these reagents for X-ray crystallography, biophysical analysis, and antigen-specific T-cell staining with pHLA multimers. Using these approaches and guided by structural analysis, it is possible to modify the interaction between TCRs and pHLA and to then test how these modifications impact T-cell antigen recognition. These findings have already helped to clarify the mechanism of T-cell recognition of a number of cancer antigens and could direct the development of altered peptides and modified TCRs for new cancer therapies

Shear-banding in a lyotropic lamellar phase, Part 1: Time-averaged velocity profiles

Using velocity profile measurements based on dynamic light scattering and coupled to structural and rheological measurements in a Couette cell, we present evidences for a shear-banding scenario in the shear flow of the onion texture of a lyotropic lamellar phase. Time-averaged measurements clearly show the presence of structural shear-banding in the vicinity of a shear-induced transition, associated to the nucleation and growth of a highly sheared band in the flow. Our experiments also reveal the presence of slip at the walls of the Couette cell. Using a simple mechanical approach, we demonstrate that our data confirms the classical assumption of the shear-banding picture, in which the interface between bands lies at a given stress $\sigma^\star$. We also outline the presence of large temporal fluctuations of the flow field, which are the subject of the second part of this paper [Salmon {\it et al.}, submitted to Phys. Rev. E]

Blast Quantification Using Hopkinson Pressure Bars

Near-field blast load measurement presents an issue to many sensor types as they must endure very aggressive environments and be able to measure pressures up to many hundreds of megapascals. In this respect the simplicity of the Hopkinson pressure bar has a major advantage in that while the measurement end of the Hopkinson bar can endure and be exposed to harsh conditions, the strain gauge mounted to the bar can be affixed some distance away. This allows protective housings to be utilized which protect the strain gauge but do not interfere with the measurement acquisition. The use of an array of pressure bars allows the pressure-time histories at discrete known points to be measured. This article also describes the interpolation routine used to derive pressure-time histories at un-instrumented locations on the plane of interest. Currently the technique has been used to measure loading from high explosives in free air and buried shallowly in various soils

Selecting pregnant or postpartum women with suspected pulmonary embolism for diagnostic imaging: the DiPEP diagnostic study with decision-analysis modelling

BACKGROUND: Pulmonary embolism (PE) is a leading cause of death in pregnancy and post partum, but the symptoms of PE are common in normal pregnancy. Simple diagnostic tests are needed to select women for diagnostic imaging. OBJECTIVE: To estimate the accuracy, effectiveness and cost-effectiveness of clinical features, decision rules and biomarkers for selecting pregnant or postpartum women with a suspected PE for imaging. DESIGN: An expert consensus study to develop new clinical decision rules, a case-control study of women with a diagnosed PE or a suspected PE, a biomarker study of women with a suspected PE or diagnosed deep-vein thrombosis (DVT) and decision-analysis modelling. SETTING: Emergency departments and consultant-led maternity units. PARTICIPANTS: Pregnant/postpartum women with a diagnosed PE from any hospital reporting to the UK Obstetric Surveillance System research platform and pregnant/postpartum women with a suspected PE or diagnosed DVT at 11 prospectively recruiting sites. INTERVENTIONS: Clinical features, decision rules and biomarkers. MAIN OUTCOME MEASURES: Sensitivity, specificity, area under receiver operating characteristic (AUROC) curve, quality-adjusted life-years (QALYs) and health-care costs. RESULTS: The primary analysis involved 181 women with PE and 259 women without PE in the case-control study and 18 women with DVT, 18 with PE and 247 women without either in the biomarker study. Most clinical features showed no association with PE. The AUROC curves for the clinical decision rules were as follows: primary consensus, 0.626; sensitive consensus, 0.620; specific consensus, 0.589; PE rule-out criteria, 0.621; simplified Geneva score, 0.579; Wells's PE criteria (permissive), 0.577; and Wells's PE criteria (strict), 0.732. The sensitivities and specificities of the D-dimer measurement were 88.4% and 8.8%, respectively, using a standard threshold, and 69.8% and 32.8%, respectively, using a pregnancy-specific threshold. Previous venous thromboembolism, long-haul travel, multiple pregnancy, oxygen saturation, recent surgery, temperature and PE-related chest radiograph abnormality were predictors of PE on multivariable analysis. We were unable to derive a rule through multivariable analysis or recursive partitioning with adequate accuracy. The AUROC curves for the biomarkers were as follows: activated partial thromboplastin time - 0.669, B-type natriuretic peptide - 0.549, C-reactive protein - 0.542, Clauss fibrinogen - 0.589, enzyme-linked immunosorbent assay D-dimer - 0.668, Innovance D-dimer (Siemens Healthcare Diagnostics Products GmbH, distributed by Sysmex UK Ltd, Milton Keynes, UK) - 0.651, mid-regional pro-atrial natriuretic peptide (MRproANP) - 0.524, prothrombin fragment 1 + 2 - 0.562, plasmin-antiplasmin - 0.639, Prothombin time - 0.613, thrombin generation lag time - 0.702, thrombin generation endogenous potential - 0.559, thrombin generation peak - 0.596, thrombin generation time to peak - 0.655, tissue factor - 0.531 and troponin - 0.597. The repeat analysis excluding women who had received anticoagulation was limited by the small number of women with PE (n = 4). The health economic analysis showed that a strategy of scanning all women with a suspected PE accrued more QALYs and incurred fewer costs than any selective strategy based on a clinical decision rule and was therefore the dominant strategy. LIMITATIONS: The findings apply specifically to the diagnostic assessment of women with a suspected PE in secondary care. CONCLUSIONS: Clinical features, decision rules and biomarkers do not accurately, effectively or cost-effectively select pregnant or postpartum women with a suspected PE for diagnostic imaging. FUTURE WORK: New diagnostic technologies need to be developed to detect PE in pregnancy. TRIAL REGISTRATION: Current Controlled Trials ISRCTN21245595. FUNDING DETAILS: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 47. See the NIHR Journals Library website for further project information

In Silico and Structural Analyses Demonstrate That Intrinsic Protein Motions Guide T Cell Receptor Complementarity Determining Region Loop Flexibility.

T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions