492 research outputs found

    Expansions for the Bollobas-Riordan polynomial of separable ribbon graphs

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    We define 2-decompositions of ribbon graphs, which generalise 2-sums and tensor products of graphs. We give formulae for the Bollobas-Riordan polynomial of such a 2-decomposition, and derive the classical Brylawski formula for the Tutte polynomial of a tensor product as a (very) special case. This study was initially motivated from knot theory, and we include an application of our formulae to mutation in knot diagrams.Comment: Version 2 has minor changes. To appear in Annals of Combinatoric

    Unsigned state models for the Jones polynomial

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    It is well a known and fundamental result that the Jones polynomial can be expressed as Potts and vertex partition functions of signed plane graphs. Here we consider constructions of the Jones polynomial as state models of unsigned graphs and show that the Jones polynomial of any link can be expressed as a vertex model of an unsigned embedded graph. In the process of deriving this result, we show that for every diagram of a link in the 3-sphere there exists a diagram of an alternating link in a thickened surface (and an alternating virtual link) with the same Kauffman bracket. We also recover two recent results in the literature relating the Jones and Bollobas-Riordan polynomials and show they arise from two different interpretations of the same embedded graph.Comment: Minor corrections. To appear in Annals of Combinatoric

    Osteoporosis management in Australian general practice: an analysis of current osteoporosis treatment patterns and gaps in practice.

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    BACKGROUND:Among Australians aged 50 and over, an estimated 1 in 4 men and 2 in 5 women will experience a minimal trauma fracture during their remaining lifetime. Effective fracture prevention is hindered by substantial undertreatment, even of patients who clearly warrant pharmacological therapy. Poor adherence to osteoporosis treatment is also a leading cause of repeat fractures and hospitalisation. The aim of this study was to identify current osteoporosis treatment patterns and gaps in practice in Australia, using general practice data, and to explore general practitioners' (GPs') attitudes to osteoporosis treatment and their views on patient factors affecting osteoporosis management. METHODS:The study was conducted in two phases. Phase 1 was a longitudinal retrospective cohort study which utilised data from MedicineInsight - a national general practice data program that extracts longitudinal, de-identified patient data from clinical information systems (CISs) of participating general practices. Phase 2 included semi-structured, in-depth telephone interviews with a sample of MedicineInsight practice GPs. Data were analysed using an inductive thematic analysis method informed by the theory of planned behaviour. RESULTS:A diagnosis of osteoporosis was recorded in 12.4% of patients over the age of 50 years seen in general practice. Of those diagnosed with osteoporosis, almost a quarter were not prescribed osteoporosis medicines. From 2012 to 17, there was a progressive increase in the number of denosumab prescriptions, while prescriptions for bisphosphonates and other osteoporosis medicines decreased. More than 80% of patients who ceased denosumab treatment had no subsequent bisphosphonate prescription recorded. Interviews with GPs revealed beliefs and attitudes that may have influenced their intentions towards prescribing and osteoporosis management. CONCLUSIONS:This study suggests that within the Australian general practice setting, osteoporosis is underdiagnosed and undertreated. In addition, it appears that most patients who ceased denosumab treatment had no record of subsequent antiresorptive therapy, which would place them at risk of further fractures. The study supports the need for the development of clinical education programs addressing GP knowledge gaps and attitudes, and the implementation of specific interventions such as good reminder/recall systems to avoid delays in reviewing and treating patients with osteoporosis

    Heart-Type Fatty Acid-Binding Protein Predicts Long-Term Mortality and Re-Infarction in Consecutive Patients With Suspected Acute Coronary Syndrome Who Are Troponin-Negative

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    ObjectivesThe purpose of this study was to establish the prognostic value of measuring heart fatty acid-binding protein (H-FABP) in patients with suspected acute coronary syndrome (ACS) (in particular, low- to intermediate-risk patients), in addition to troponin measured with the latest third-generation troponin assay.BackgroundWe have previously shown that H-FABP is a useful prognostic marker in patients with proven ACS.MethodsPatients (n = 1,080) consecutively admitted to the hospital with suspected ACS were recruited over 46 weeks. Siemens Advia Ultra-TnI (Siemens Healthcare Diagnostics, Newbury, United Kingdom) and Randox Evidence H-FABP (Randox Laboratories, Ltd., Co., Antrim, United Kingdom) were analyzed on samples collected 12 to 24 h from symptom onset. After exclusion of patients with ST-segment elevation and new left bundle branch block, 955 patients were included in the analysis.ResultsThe primary outcome measure of death or readmission with myocardial infarction after a minimum follow-up period of 12 months (median 18 months) occurred in 96 of 955 patients (10.1%). The H-FABP concentration was an independent predictor of death or myocardial infarction, after multivariate adjustment. Patients with H-FABP concentrations >6.48 μg/l had significantly increased risk of adverse events (adjusted hazard ratio: 2.62, 95% confidence interval: 1.30 to 5.28, p = 0.007). Among troponin-negative patients (which constituted 79.2% of the cohort), the aforementioned cutoff of 6.48 μg/l identified patients at very high risk for adverse outcomes independent of patient age and serum creatinine.ConclusionsWe have demonstrated that the prognostic value of elevated H-FABP is additive to troponin in low- and intermediate-risk patients with suspected ACS. Other studies suggest that our observations reflect the value of H-FABP as a marker of myocardial ischemia, even in the absence of frank necrosis

    Chronic Thromboembolic Pulmonary Hypertension

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    The pulmonary hypertension (PH) and right heart dysfunction that results from chronic thromboembolic involvement of the pulmonary vascular bed is potentially curable with surgical endarterectomy. Over the past several decades, growing clinical experience has brought about increased recognition of this treatable form of PH. Moreover, advances in cardiothoracic surgical techniques have given an increasing number of patients with chronic thromboembolic PH (CTEPH) a surgical remedy with decreasing perioperative morbidity and mortality risks. The availability of pulmonary hypertensive—specific medical therapy for CTEPH patients with surgically inaccessible disease also has been a positive therapeutic advance over the past several years. However, despite this progress, chronic thromboembolic disease as a sequela of acute pulmonary emboli continues to be underappreciated. Furthermore, even if CTEPH has been appropriately diagnosed, misinterpretation of diagnostic information may lead to the inappropriate exclusion of patients from surgical consideration. This may result in the prescription of pulmonary hypertensive medical therapy in CTEPH patients with potentially surgically correctable disease. This difficulty arises from a lack of objective criteria as to what constitutes surgical chronic thromboembolic disease, which primarily is a result of the variability in surgical experience in specialty centers in the United States. Consequently, clinicians must be wary about using pulmonary hypertensive medications in CTEPH patients. Before prescription, it is important to exclude patients from surgical consideration by consulting a specialized center with expertise in this discipline

    Interprofessional training for final year healthcare students: a mixed methods evaluation of the impact on ward staff and students of a two-week placement and of factors affecting sustainability

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    BACKGROUND: Multiple care failings in hospitals have led to calls for increased interprofessional training in medical education to improve multi-disciplinary teamwork. Providing practical interprofessional training has many challenges and remains uncommon in medical schools in the UK. Unlike most previous research, this evaluation of an interprofessional training placement takes a multi-faceted approach focusing not only on the impact on students, but also on clinical staff delivering the training and on outcomes for patients. METHODS: We used mixed methods to examine the impact of a two-week interprofessional training placement undertaken on a medical rehabilitation ward by three cohorts of final year medical, nursing and therapy students. We determined the effects on staff, ward functioning and participating students. Impact on staff was evaluated using the Questionnaire for Psychological and Social factors at work (QPSNordic) and focus groups. Ward functioning was inferred from standard measures of care including length of stay, complaints, and adverse events. Impact on students was evaluated using the Readiness for Interprofessional Learning Survey (RIPLS) among all students plus a placement survey among medical students. RESULTS: Between 2007 and 2010, 362 medical students and 26 nursing and therapy students completed placements working alongside the ward staff to deliver patient care. Staff identified benefits including skills recognition and expertise sharing. Ward functioning was stable. Students showed significant improvements in the RIPLS measures of Teamwork, Professional Identity and Patient-Centred Care. Despite small numbers of students from other professions, medical students’ rated the placement highly. Increasing student numbers and budgetary constraints led to the cessation of the placement after three years. CONCLUSIONS: Interprofessional training placements can be delivered in a clinical setting without detriment to care and with benefits for all participants. While financial support is a necessity, it appears that having students from multiple professions is not critical for a valuable training experience; staff from different professions and students from a single profession can work successfully together. Difficulty in aligning the schedules of different student professions is commonly cited as a barrier to interprofessional training. Our experience challenges this and should encourage provision of authentic interprofessional training experience

    UK informative inventory report (1990 to 2013)

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    This is the 10th Informative Inventory Report (IIR) from the UK National Atmospheric Emissions Inventory (NAEI) Programme. The report is compiled to accompany the UK’s 2015 data submission under the United Nations Economic Commission for Europe (UNECE) Convention on Long-Range Transboundary Air Pollution (CLRTAP) and contains detailed information on annual emission estimates of air quality pollutants by source in the UK from 1990 onwards

    The clinical efficacy of first-generation carcinoembryonic antigen (CEACAM5)-specific CAR T cells is limited by poor persistence and transient pre-conditioning-dependent respiratory toxicity

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    The primary aim of this clinical trial was to determine the feasibility of delivering first-generation CAR T cell therapy to patients with advanced, CEACAM5(+) malignancy. Secondary aims were to assess clinical efficacy, immune effector function and optimal dose of CAR T cells. Three cohorts of patients received increasing doses of CEACAM5(+)-specific CAR T cells after fludarabine pre-conditioning plus systemic IL2 support post T cell infusion. Patients in cohort 4 received increased intensity pre-conditioning (cyclophosphamide and fludarabine), systemic IL2 support and CAR T cells. No objective clinical responses were observed. CAR T cell engraftment in patients within cohort 4 was significantly higher. However, engraftment was short-lived with a rapid decline of systemic CAR T cells within 14 days. Patients in cohort 4 had transient, acute respiratory toxicity which, in combination with lack of prolonged CAR T cell persistence, resulted in the premature closure of the trial. Elevated levels of systemic IFNγ and IL-6 implied that the CEACAM5-specific T cells had undergone immune activation in vivo but only in patients receiving high-intensity pre-conditioning. Expression of CEACAM5 on lung epithelium may have resulted in this transient toxicity. Raised levels of serum cytokines including IL-6 in these patients implicate cytokine release as one of several potential factors exacerbating the observed respiratory toxicity. Whilst improved CAR designs and T cell production methods could improve the systemic persistence and activity, methods to control CAR T 'on-target, off-tissue' toxicity are required to enable a clinical impact of this approach in solid malignancies
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