1,721,028 research outputs found
The impact of HIV infection on the burden and severity of influenza illness in Malawian adults
Full text linkBackground. Influenza infection and its complications cause substantial morbidity and mortality worldwide. However, the epidemiology of influenza in sub-Saharan Africa (SSA) is not well known. Furthermore, the effects of HIV infection on influenza burden and severity in adults in a region with high HIV prevalence are also poorly characterised. Although seasonal influenza vaccination is recommended for HIV-infected persons in developed settings, it is not part of routine HIV care in Africa. The primary aim of this thesis was to examine the impact of HIV on the incidence and severity of influenza infection among adults in urban Malawi, to determine whether HIV-infected adults should be prioritised for influenza preventative measures.
Methods. At the Queen Elizabeth Central Hospital in Blantyre, Malawi, we characterised the epidemiology, seasonality and risk factors for influenza infection in Malawian adults enrolled in a sentinel surveillance study. Secondly, we established a prospective cohort to compare the incidence of laboratory-confirmed influenza illness between HIV-infected and HIV-uninfected adults over two years. Thirdly, we conducted a case control study of adults with mild (influenza-like illness (ILI)) and severe (hospitalised lower respiratory tract infection (LRTI)) influenza illness to explore risk factors for severe influenza presentation, with HIV as the primary exposure of interest. Lastly, as a potential mechanism through which influenza and other respiratory viral infections predispose to secondary bacterial pneumonia, we investigated the association between respiratory viral infections and nasopharyngeal carriage density of Streptococcus pneumoniae in a cross-sectional and case control analysis nested within the prospective cohort.
Results. Influenza was a common cause of mild and severe acute respiratory infections in Malawian adults in the hospital-based sentinel surveillance. Pregnant women were found to have nearly double the risk of hospital-attended influenza infection compared to non-gravid women of childbearing age. In the prospective cohort of 608 adults (59% HIV-reactive), 24/229 (10.5%) ILI episodes in HIV-infected and 5/119 (4.2%) in HIV-uninfected adults were influenza PCR-positive (incidence rates 46.0 vs. 14.5 per 1000 person years). After accounting for potential confounders, HIV-infected adults had an approximately three times higher incidence of influenza infection compared to HIV-uninfected adults. In the case control study, HIV was the single most important risk factor for severe influenza-related presentation; HIV-infected adults experienced a five-fold greater risk of severe influenza disease compared to HIV-uninfected adults, and over 50% of influenza-related hospitalised LRTI were attributable to HIV. Influenza infection was associated with pneumococcal carriage, but respiratory viral infection was not associated with pneumococcal acquisition or an increase in pneumococcal colonisation density.
Conclusion. We have clearly demonstrated a high burden of influenza disease among Malawian adults. Moreover, HIV-infected adults have increased susceptibility and severity of influenza presentations, thus should be considered a priority group for targeted vaccination in the region. Influenza vaccine policies that maximise health benefit through efficient use of limited resources are urgently needed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Platelet and soluble CD40L in meningococcal sepsis
No full textOBJECTIVE: To determine the influence of meningococcal sepsis on levels of platelet derived CD40L and on endothelial CD40 expression. DESIGN AND SETTING: Prospective observational study in two tertiary paediatric intensive care units. PATIENTS AND PARTICIPANTS: 63 children with meningococcal sepsis and 10 age-matched controls. MEASUREMENTS AND RESULTS: (a) sCD40L ELISA of plasma from patients with meningococcal sepsis (n = 49) and age matched controls (n = 10). This demonstrated higher sCD40L levels in patients (median 0.29 ng/ml, IQR 0.2-0.41) than controls (0.09 ng/ml, 0.08-0.12). However, there was no relationship between plasma sCD40L level and platelet count or disease severity. (b) Flow cytometry of fresh blood from patients with meningococcal sepsis (n = 11) and age-matched controls (n = 10) for membrane bound CD40L and CD62P on circulating platelets. This demonstrated low levels of CD40L and CD62P in patients and controls. CD40L+ platelets were 3.5% (3.0-4.8) in patients and 4.9% (3.5-4.3) in controls. CD62P+ platelets were 10.7% (6.4-12.8) in patients and 7.9% (5.9-13.0) in controls. (c) Immunohistochemistry of skin biopsy specimens from six patients, staining for endothelial CD40 expression at sites of microthrombus formation, which demonstrated preserved CD40 expression in vascular endothelium at sites of microthrombus formation. CONCLUSIONS: The elevated sCD40L level in meningococcal sepsis implies release of sCD40L from platelets. However, there was no relationship between plasma sCD40L level and the degree of thrombocytopenia or disease severity. Furthermore, platelet surface bound CD40L was similar in controls and patients. Thus, further investigation is needed to determine whether platelet CD40L contributes to inflammation and thrombosis in MCS
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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