3,858 research outputs found

    Bioluminescent Francisella tularensis SCHU S4 enables non-invasive tracking of bacterial dissemination and the evaluation of antibiotics in an inhalational mouse model of tularaemia

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    This document is the Accepted Manuscript version of the following article: Hall CA, Flick-Smith HC, Harding SV, Atkins HS, and Titball RW. 2016. "A bioluminescent Francisella tularensis SCHU S4 strain enables noninvasive tracking of bacterial dissemination and the evaluation of antibiotics in an inhalational mouse model of tularemia", Antimicrob Agents Chemother 60:7206–7215. The version of record is available online at doi:10.1128/AAC.01586-16. Copyright © 2016, American Society for Microbiology. All Rights Reserved.Bioluminescence imaging (BLI) enables real-time, noninvasive tracking of infection in vivo and longitudinal infection studies. In this study, a bioluminescent Francisella tularensis strain, SCHU S4-lux, was used to develop an inhalational infection model in BALB/c mice. Mice were infected intranasally, and the progression of infection was monitored in real time using BLI. A bioluminescent signal was detectable from 3 days postinfection (3 dpi), initially in the spleen and then in the liver and lymph nodes, before finally becoming systemic. The level of bioluminescent signal correlated with bacterial numbers in vivo, enabling noninvasive quantification of bacterial burdens in tissues. Treatment with levofloxacin (commencing at 4 dpi) significantly reduced the BLI signal. Furthermore, BLI was able to distinguish noninvasively between different levofloxacin treatment regimens and to identify sites of relapse following treatment cessation. These data demonstrate that BLI and SCHU S4-lux are suitable for the study of F. tularensis pathogenesis and the evaluation of therapeutics for tularemia.Peer reviewedFinal Accepted Versio

    The role of Plasmodium falciparum var genes in malaria in pregnancy

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    Sequestration of Plasmodium falciparum-infected erythrocytes in the placenta is responsible for many of the harmful effects of malaria during pregnancy. Sequestration occurs as a result of parasite adhesion molecules expressed on the surface of infected erythrocytes binding to host receptors in the placenta such as chondroitin sulphate A (CSA). Identification of the parasite ligand(s) responsible for placental adhesion could lead to the development of a vaccine to induce antibodies to prevent placental sequestration. Such a vaccine would reduce the maternal anaemia and infant deaths that are associated with malaria in pregnancy. Current research indicates that the parasite ligands mediating placental adhesion may be members of the P. falciparum variant surface antigen family PfEMP1, encoded by var genes. Two relatively well-conserved subfamilies of var genes have been implicated in placental adhesion, however, their role remains controversial. This review examines the evidence for and against the involvement of var genes in placental adhesion, and considers whether the most appropriate vaccine candidates have yet been identified

    Identification of Plasmodium falciparum var1CSA and var2CSA domains that bind IgM natural antibodies

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    Malaria in pregnancy is responsible for maternal anaemia, low-birth-weight babies and infant deaths. Plasmodium falciparum infected erythrocytes are thought to cause placental pathology by adhering to host receptors such as chondroitin sulphate A (CSA). CSA binding infected erythrocytes also bind IgM natural antibodies from normal human serum, a process that may facilitate placental adhesion or promote immune evasion. The parasite ligands that mediate placental adhesion are thought to be members of the variant erythrocyte surface antigen family P. falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by the var genes. Two var gene sub-families, var1CSA and var2CSA, have been identified as parasite CSA binding ligands and are leading candidates for a vaccine to prevent pregnancy-associated malaria. We investigated whether these two var gene subfamilies implicated in CSA binding are also the molecules responsible for IgM natural antibody binding. By heterologous expression of domains in COS-7 cells, we found that both var1CSA and var2CSA PfEMP1 variants bound IgM, and in both cases the binding region was a DBL epsilon domain occurring proximal to the membrane. None of the domains from a control non-IgM-binding parasite (R29) bound IgM when expressed in COS-7 cells. These results show that PfEMP1 is a parasite ligand for non-immune IgM and are the first demonstration of a specific adhesive function for PfEMP1 epsilon type domains

    Analyzing monthly extreme sea levels with a time-dependent GEV model

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    A statistical model to analyze different time scales of the variability of extreme high sea levels is presented. This model uses a time-dependent generalized extreme value (GEV) distribution to fit monthly maxima series and is applied to a large historical tidal gauge record (San Francisco, California). The model allows the identification and estimation of the effects of several time scales —such as seasonality, interdecadal variability, and secular trends— in the location, scale, and shape parameters of the probability distribution of extreme sea levels. The inclusion of seasonal effects explains a large amount of data variability, thereby allowing a more efficient estimation of the processes involved. Significant correlation with the Southern Oscillation index and the nodal cycle, as well as an increase of about 20% for the secular variability of the scale parameter have been detected for the particular dataset analyzed. Results show that the model is adequate for a complete analysis of seasonal-to-interannual sea level extremes providing time-dependent quantiles and confidence intervals

    The shifting nature of women’s experiences and perceptions of ductal carcinoma in situ

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    Aim: This paper is a report of a descriptive qualitative study of the evolution of women’s perceptions and experiences of ductal carcinoma in situ from the period near to diagnosis to one year later. Background: Ductal carcinoma in situ is a non-invasive breast condition where cancer cells are detected but confined to the ducts of the breast. With treatment, the condition has a positive prognosis but ironically patients undergo treatment similar to that for invasive breast cancer. There is a lack of longitudinal qualitative research studying women’s experiences of ductal carcinoma in situ, especially amongst newly diagnosed patients and how experiences change over time. Methods: Forty-five women took part in an initial interview following a diagnosis of ductal carcinoma in situ and twenty-seven took part in a follow-up interview 9-13 months later. Data were collected between January 2007 and October 2008. Transcripts were analysed using a hybrid approach to thematic analysis. Findings: Women’s early perceptions of ductal carcinoma in situ merged and sometimes conflicted with their lay beliefs of breast cancer. Perceptions and experiences of the condition shifted over time. These overriding aspects were evident within four themes identified across the interviews: 1) perceptions of DCIS versus breast cancer, 2) from paradox to acceptance, 3) personal impact, and 4) support and interactions with others. Conclusion: This study represents one of the few longitudinal qualitative studies with newly diagnosed patients, capturing women’s initial and shifting experiences and perceptions of the condition. The issues identified need to be recognised in clinical practice and supported appropriately

    Exploring attitudes to edgy urban destinations: the case of Deptford, London

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    The role of tourists and tourism in urban development is not fully understood. Research has focused on tourism districts within city centres, but less is known about tourism in peripheral, less affluent urban districts. These areas can appeal to visitors as edgy alternatives to mainstream destinations. This study establishes who is interested in visiting and why, and it explores the underlying rationale for negative attitudes. The aims are addressed by an in-depth analysis of Deptford in South East London. This area is a relatively deprived part of a world city, albeit one that has long been earmarked as London's next cool district. The study uses a mix of different sources to analyse the case. Responses to a New York Times article on Deptford are analysed and the attitudes of actual visitors and key stakeholders are explored. The discussion includes an examination of different interpretations and attitudes towards the notion of edginess. Edginess is deemed attractive by certain audiences; something linked to a reverence for working-class life in the arts. The study concludes that, whilst edginess is a noted characteristic, what people appreciate about Deptford is its ‘distinctive ordinariness’ – its contrast with more polished and contrived urban districts

    Proteolytic and nonproteolytic activation mechanisms result in conformationally and functionally different forms of coagulation factor XIII A

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    Factor XIIIA (FXIIIA) is a transglutaminase that cross‐links intra‐ and extracellular protein substrates. FXIIIA is expressed as an inactive zymogen, and during blood coagulation, it is activated by removal of an activation peptide by the protease thrombin. No such proteolytic FXIIIA activation is known to occur in other tissues or the intracellular form of FXIIIA. For those locations, FXIIIA is assumed instead to undergo activation by Ca2+ ions. Previously, we demonstrated a monomeric state for active FXIIIA. Current analytical ultracentrifugation and kinetic experiments revealed that thrombin‐activated FXIIIA has a higher conformational flexibility and a stronger affinity toward glutamine substrate than does nonproteolytically activated FXIIIA. The proteolytic activation of FXIIIA was further investigated in a context of fibrin clotting. In a series of fibrin cross‐linking assays and scanning electron microscopy studies of plasma clots, the activation rates of FXIIIA V34X variants were correlated with the extent of fibrin cross‐linking and incorporation of nonfibrous protein into the clot. Overall, the results suggest conformational and functional differences between active FXIIIA forms, thus expanding the understanding of FXIIIA function. Those differences may serve as a basis for developing therapeutic strategies to target FXIIIA in different physiological environments

    Nurses' and surgeons' views and experiences of surgical wounds healing by secondary intention : a qualitative study

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    AIMS AND OBJECTIVES: To explore surgeons' and nurses' perspectives of managing surgical wounds healing by secondary intention. BACKGROUND: Every year, more than 10 million surgical operations are performed in the NHS in the UK. Most surgical wounds heal by primary intention, where the edges of the wound are brought together with staples, sutures, adhesive glue or clips. Sometimes wounds are deliberately left open to heal, from the base up, known as 'healing by secondary intention'. These wounds are often slow to heal, prone to infection, and complex to manage. DESIGN: A qualitative, descriptive approach, using semi-structured interviews. METHODS: Interviews with five (general, vascular and plastic) surgeons and 7 nurses (3 tissue viability nurses, 2 district and 1 community nurse, and 1 hospital nurse) working in hospital and community care settings in two locations in the north of England. Data analysis followed the recommended sequential steps of 'Framework' approach. Consolidated criteria for reporting qualitative research guided the study report. RESULTS: Participants reported that the main types of wounds healing by secondary intention that they manage are extensive abdominal cavity wounds; open wounds relating to treatment for pilonidal sinus; large open wounds on the feet of patients with diabetes; and axilla and groin wounds, associated with removal of lymph nodes for cancer. Infection and prolonged time to healing were the main challenges. Negative pressure wound therapy was the most favoured treatment option. CONCLUSIONS: Negative pressure wound therapy was advocated by professionals despite a lack of research evidence indicating clinical or cost-effectiveness. Our findings underscore the need for rigorous evaluation of negative pressure wound therapy, and other wound care treatments, through studies that include economic evaluation. RELEVANCE FOR CLINICAL PRACTICE: Clinical decision making in wound care could be optimised through further robust studies to inform practitioners about the cost-effectiveness of available treatments

    ‘Get yourself some nice, neat, matching box files’: research administrators and occupational identity work

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    To date, qualitative research into occupational groups and cultures within academia has been relatively scarce, with an almost exclusive concentration upon teaching staff within universities and colleges. This article seeks to address this lacuna and applies the interactionist concept of ‘identity work’ in order to examine one specific group to date under-researched: graduate research administrators. This occupational group is of sociological interest as many of its members appear to span the putative divide between ‘academic’ and ‘administrative’ occupational worlds within higher education. An exploratory, qualitative research project was undertaken, based upon interviews with 27 research administrators. The study analyses how research administrators utilise various forms of identity work to sustain credible occupational identities, often in the face of considerable challenge from their academic colleagues
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