1,721,241 research outputs found
AIDS in Africa
No full textWe would like to add a layer of complexity to, and maybe shed some light on, interactions between AIDS and other infectious diseases recently summarised by Corbett and colleagues (June 22, p 2177).1
Immunological results collected over time in the Gulu district of north Uganda, where prevalence of HIV infection ranges between 14% and 25%, show that lymphocytes from African HIV-infected individuals are abnormally activated. Thus, production of interferon γ and interleukin 10 by HIV-antigen-stimulated peripheral blood mononuclear cells of African HIV-infected individuals is higher than in European patients. Immune activation in the African setting is not limited to HIV-infected individuals: production of interferon γ and interleukin 10 is greatly augmented in HIV-uninfected individuals as well. This abnormal activation is associated with environmental conditions, including parasitic infections, poor hygienic conditions, and dietary limitations, since the immune response resumes a Th1-dominant pattern in Africans who move to Western countries.2
Susceptibility to HIV infection is thought to be higher, and disease progression faster, in African individuals than in European individuals. How could the peculiar cytokine profile seen in the African setting affect susceptibility to infection and the rate of progression to AIDS? In vitro, interferon γ and interleukin 10 increase expression of chemokine receptor 5 (CCR5)—one of the main coreceptors for HIV on the surface of immune cells. Data show that CCR5 is indeed upregulated in vivo in African individuals.2 The potential importance of this observation is underlined by results indicating that HIV infection in Africa is mostly supported by R5 viruses—ie the viral strain that uses CCR5 as its coreceptor.3 Thus, immune activation would provoke upregulation of CCR5 on target cells, and this would result in an evolutionary pressure on the viral quasispecies, leading to the preferential selection of R5 HIV strains. The net result is prevalence of R5 virus within a biological scenario (upregulation of CCR5) that facilitates infection of target cells. Because CCR5-expressing cells are concentrated in the female genital tract,4 and HIV infection in Africa is mainly heterosexually transmitted, the immune scenario detected in Africa could also be at least partly responsible for a facilitated heterosexual transmission of HIV infection.
This hypothesis is strengthened by preliminary data gathered in the Marashtra-mumbai region of India. In fact, despite the observation that R5 viruses are prevalent in this region,5 cells of HIV-infected and HIV-uninfected Marashtra-mumbai individuals mostly express the chemokine receptor CXCR4 (unpublished data). CXCR4 upregulation is seen in the presence of an immune profile that overlaps the one seen in African individuals, but that is also distinguished by abnormally increased secretion of interleukin 4, the cytokine that induces CXCR4. In this scenario, characterised by the discordance between the predominant HIV strain and the prevalent viral coreceptor, progression of HIV infection is slower and similar to the one seen in Western countries
African enigma: key player in human immunodeficiency virus pathogenesis in developing countries?
No full text
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
Dolutegravir and metformin : a clinically relevant or just a pharmacokinetic interaction?
No full text- …
