2,129 research outputs found

    Non-adiabatic radiative collapse of a relativistic star under different initial conditions

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    We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star with interior comprising of a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the configurations are spherically symmetric, however, in the latter case, the physical space t=constantt= constant of the configurations is assumed to be inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is observed that as long as the collapse is shear-free, its evolution depends only on the mass and size of the star at the onset of collapse.Comment: To appear in Pramana- j. of physic

    Defining the molecular role of gp91phox in the immune manifestation of acute allergic asthma using a preclinical murine model

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    <p>Abstract</p> <p>Objective</p> <p>The phenomena manifested during inflammation require interplay between circulating effector cells, local resident cells, soluble mediators and genetic host factors to establish, develop and maintain itself. Of the molecues involed in the initiation and perpetuation of acute allergic inflammation in asthma, the involvement of effector cells in redox reactions for producing O<sub>2</sub><sup>- </sup>(superoxide anion) through the mediation of NADPH oxidase is a critical step. Prior data suggest that reactive oxygen species (ROS) produced by NADPH oxidase homologues in non-phagocytic cells play an important role in the regulation of signal transduction, while macrophages use a membrane-associated NADPH oxidase to generate an array of oxidizing intermediates which inactivate MMPs on or near them.</p> <p>Materials and Methods and Treatment</p> <p>To clarify the role of gp91phox subunit of NADPH oxidase in the development and progression of an acute allergic asthma phenotype, we induced allergen dependent inflammation in a gp91<it><sup>phox</sup></it>-/- single knockout and a gp91phox-/-MMP-12-/- double knockout mouse models.</p> <p>Results</p> <p>In the knockout mice, both inflammation and airway hyperreactivity were more extensive than in wildtype mice post-OVA. Although OVA-specific IgE in plasma were comparable in wildtype and knockout mice, enhanced inflammatory cell recruitment from circulation and cytokine release in lung and BALf, accompanied by higher airway resistance as well as Penh in response to methacholine, indicate a regulatory role for NADPH oxidase in development of allergic asthma. While T cell mediated functions like Th2 cytokine secretion, and proliferation to OVA were upregulated synchronous with the overall robustness of the asthma phenotype, macrophage upregulation in functions such as proliferation, and mixed lymphocyte reaction indicate a regulatory role for gp91phox and an overall non-involvement or synergistic involvement of MMP12 in the response pathway (comparing data from gp91phox-/- and gp91phox-/-MMP-12-/- mice).</p

    Regularity of Edge Ideals and Their Powers

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    We survey recent studies on the Castelnuovo-Mumford regularity of edge ideals of graphs and their powers. Our focus is on bounds and exact values of  reg I(G)\text{ reg } I(G) and the asymptotic linear function  reg I(G)q\text{ reg } I(G)^q, for q1,q \geq 1, in terms of combinatorial data of the given graph G.G.Comment: 31 pages, 15 figure

    A population-based study of 92 clinically recognised risk factors for heart failure: co-occurrence, prognosis and preventive potential

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    BACKGROUND: Primary prevention strategies for heart failure(HF) have had limited success, possibly due to a wide range of underlying risk factors(RFs). Systematic evaluations of the prognostic burden and preventive potential across this wide range of risk factors are lacking. OBJECTIVE: To estimate evidence, prevalence and co-occurrence for primary prevention and impact on prognosis of RFs for incident HF. METHODS: We systematically reviewed trials and observational evidence of primary HF prevention across 92 putative aetiologic RFs for HF identified from US and European clinical practice guidelines. We identified 170 885 individuals aged ≥30 years with incident HF from 1997-2017, using linked primary and secondary care UK electronic health records(EHR) and rule-based phenotypes(ICD-10, Read Version 2, OPCS-4 procedure and medication codes) for each of 92 RFs. RESULTS: Only 10/92 factors had high quality observational evidence for association with incident HF; 7 had effective RCT-based interventions for HF prevention(RCT-HF), and 6 for CVD prevention, but not HF(RCT-CVD), and the remainder had no RCT-based preventive interventions(RCT-0). We were able to map 91/92 risk factors to EHR using 5961 terms, and 88/91 factors were represented by at least one patient. In the 5 years prior to HF diagnosis, 44.3% had ≥4 RFs. By RCT evidence, the most common RCT-HF RFs were hypertension(48.5%), stable angina(34.9%), unstable angina(16.8%), myocardial infarction(15.8%), and diabetes(15.1%); RCT-CVD RFs were smoking(46.4%) and obesity(29.9%); and RCT-0 RFs were atrial arrhythmias(17.2%), cancer(16.5%),), heavy alcohol intake(14.9%). Mortality at 1 year varied across all 91 factors(lowest: pregnancy-related hormonal disorder 4.2%; highest: phaeochromocytoma 73.7%). Among new HF cases, 28.5% had no RCT-HF RFs and 38.6% had no RCT-CVD RFs. 15.6% had either no RF or only RCT-0 RFs. CONCLUSION: 1 in 6 individuals with HF have no recorded RFs or RFs without trials. We provide a systematic map of primary preventive opportunities across a wide range of RFs for HF, demonstrating a high burden of co-occurrence and the need for trials tackling multiple RFs

    Conservative management versus open reduction and internal fixation for mid-shaft clavicle fractures in adults - The Clavicle Trial: Study protocol for a multicentre randomized controlled trial

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    Background: Clavicle fractures account for around 4% of all fractures and up to 44% of fractures of the shoulder girdle. Fractures of the middle third (or mid-shaft) account for approximately 80% of all clavicle fractures. Management of this group of fractures is often challenging and the outcome can be unsatisfactory. In particular it is not clear whether surgery produces better outcomes than non-surgical management. Currently there is much variation in the use of surgery and a lack of good quality evidence to inform our decision.Methods/Design: We aim to undertake a multicentre randomised controlled trial evaluating the effectiveness and safety of conservative management versus open reduction and internal fixation for displaced mid-shaft clavicle fractures in adults. Surgical treatment will be performed using the Acumed clavicle fixation system. Conservative management will consist of immobilisation in a sling at the side in internal rotation for 6 weeks or until clinical or radiological union. We aim to recruit 300 patients. These patients will be followed-up for at least 9 months. The primary endpoint will be the rate of non-union at 3 months following treatment. Secondary endpoints will be limb function measured using the Constant-Murley Score and the Disabilities of the Arm, Shoulder and Hand (DASH) Score at 3 and 9 months post-operatively.Discussion: This article presents the protocol for a multicentre randomised controlled trial. It gives extensive details of, and the basis for, the chosen methods, and describes the key measures taken to avoid bias and to ensure validity.Trial Registration: United Kingdom Clinical Research Network ID: 8665. The date of registration of the trial is 07/09/2006. The date the first patient was recruited is 18/12/2007. © 2011 Longo et al; licensee BioMed Central Ltd

    The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections

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    Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013 The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate cocaine-induced changes in the concentrations of different redox forms of cysteine (Cys) and homocysteine (Hcy), and products of anaerobic Cys metabolism, i.e., labile, reduced sulfur (LS) in the rat plasma. The above-mentioned parameters were determined after i.p. acute and subchronic cocaine treatment as well as following i.v. cocaine self-administration using the yoked procedure. Additionally, Cys, Hcy, and LS levels were measured during the 10-day extinction training in rats that underwent i.v. cocaine administration. Acute i.p. cocaine treatment increased the total and protein-bound Hcy contents, decreased LS, and did not change the concentrations of Cys fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered the total and protein-bound Cys concentrations while LS level was unchanged. Cocaine self-administration enhanced the total and protein-bound Hcy levels, decreased LS content, and did not affect the Cys fractions. On the other hand, yoked cocaine infusions did not alter the concentration of Hcy fractions while decreased the total and protein-bound Cys and LS content. This extinction training resulted in the lack of changes in the examined parameters in rats with a history of cocaine self-administration while in the yoked cocaine group an increase in the plasma free Cys fraction and LS was seen. Our results demonstrate for the first time that cocaine does evoke significant changes in homeostasis of thiol amino acids Cys and Hcy, and in some products of anaerobic Cys metabolism, which are dependent on the way of cocaine administration

    The Ly6 Protein Coiled Is Required for Septate Junction and Blood Brain Barrier Organisation in Drosophila

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    Background: Genetic analysis of the Drosophila septate junctions has greatly contributed to our understanding of the mechanisms controlling the assembly of these adhesion structures, which bear strong similarities with the vertebrate tight junctions and the paranodal septate junctions. These adhesion complexes share conserved molecular components and have a common function: the formation of paracellular barriers restraining the diffusion of solutes through epithelial and glial envelopes. Methodology/Principal Findings: In this work we characterise the function of the Drosophila cold gene, that codes for a protein belonging to the Ly6 superfamily of extracellular ligands. Analysis of cold mutants shows that this gene is specifically required for the organisation of the septate junctions in epithelial tissues and in the nervous system, where its contribution is essential for the maintenance of the blood-brain barrier. We show that cold acts in a cell autonomous way, and we present evidence indicating that this protein could act as a septate junction component. Conclusion/Significance: We discuss the specific roles of cold and three other Drosophila members of the Ly6 superfamily that have been shown to participate in a non-redundant way in the process of septate junction assembly. We propose tha

    Process evaluation of a randomised pilot trial of home-based rehabilitation compared to usual care in patients with heart failure with preserved ejection fraction and their caregiver’s

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    Background: Whilst heart failure (HF) with preserved ejection fraction (HFpEF) affects almost 50 percent of the HF population, evidence-based treatment options remain limited. However, there is growing evidence of the potential value of exercise-based cardiac rehabilitation. This study reports the process evaluation of the Rehabilitation Enablement in Chronic Heart Failure (REACH-HF) intervention for HFpEF patients and their caregivers conducted as part of the REACH-HFpEF pilot trial. Methods: Process evaluation sub-study parallel to a single centre (Tayside, Scotland) randomised controlled pilot trial with qualitative assessment of both intervention fidelity delivery and HFpEF patients’ and caregivers’ experiences. The REACH-HF intervention consisted of self-help manual for patients and caregivers, facilitated over 12 weeks by trained healthcare professionals. Interviews were conducted following completion of intervention in a purposeful sample of 15 HFpEF patients and 7 caregivers. Results: Qualitative information from the facilitator interactions and interviews identified three key themes for patients and caregivers: (1) understanding their condition, (2) emotional consequences of HF, and (3) patients’ and caregivers’ responses to the REACH-HF intervention. The differing professional backgrounds demonstrate the possibility of delivering REACH-HF by either existing HF or cardiac rehabilitation services of a combination of the two. Conclusions: The REACH-HF home-based facilitated intervention for HFpEF appears feasible and well accepted model for delivery of a cardiac rehabilitation intervention, with the potential to address key unmet needs of patients and their caregivers who are often excluded from service provision and current CR programmes. Results of this study will inform a recently funded full multicentre randomised clinical trial

    Regulation of mammary gland branching morphogenesis by the extracellular matrix and its remodeling enzymes.

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    A considerable body of research indicates that mammary gland branching morphogenesis is dependent, in part, on the extracellular matrix (ECM), ECM-receptors, such as integrins and other ECM receptors, and ECM-degrading enzymes, including matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs). There is some evidence that these ECM cues affect one or more of the following processes: cell survival, polarity, proliferation, differentiation, adhesion, and migration. Both three-dimensional culture models and genetic manipulations of the mouse mammary gland have been used to study the signaling pathways that affect these processes. However, the precise mechanisms of ECM-directed mammary morphogenesis are not well understood. Mammary morphogenesis involves epithelial 'invasion' of adipose tissue, a process akin to invasion by breast cancer cells, although the former is a highly regulated developmental process. How these morphogenic pathways are integrated in the normal gland and how they become dysregulated and subverted in the progression of breast cancer also remain largely unanswered questions
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