1,720,968 research outputs found
Human cytomegalovirus inhibits the migration of immature dendritic cells by down-regulating cell-surface CCR1 and CCR5.
No full textDendritic cells (DC) play a key role in the host immune response to infections. Human cytomegalovirus (HCMV) infection can inhibit the maturation of DC and impair their ability to stimulate T cell proliferation and cytotoxicity. In this study, we assessed the effects of HCMV infection on the migratory behavior of human DC. The HCMV strain TB40/E inhibited the migration of immature monocyte-derived DC in response to inflammatory chemokines by 95% 1 day after infection. This inhibition was mediated by early viral replicative events, which significantly reduced the cell-surface expression of CC chemokine receptor 1 (CCR1) and CCR5 by receptor internalization. HCMV infection also induced secretion of the inflammatory chemokines CC chemokine ligand 3 (CCL3)/macrophage inflammatory protein-1alpha (MIP-1alpha), CCL4/MIP-1beta, and CCL5/regulated on activation, normal T expressed and secreted (RANTES). Neutralizing antibodies for these chemokines reduced the effects of HCMV on chemokine receptor expression and on DC migration by approximately 60%. Interestingly, the surface expression of the lymphoid chemokine receptor CCR7 was not up-regulated after HCMV infection on immature DC, and immature-infected DC did not migrate in response to CCL19/MIP-3beta. These findings suggest that blocking the migratory ability of DC may be a potent mechanism used by HCMV to paralyze the early immune response of the host
Thioredoxin specifically cross-desensitizes monocytes to MCP-1
No full text: Thioredoxin (Trx) is a protein disulfide oxidoreductase which can be secreted and acts as a cytokine. As we recently reported that Trx is chemotactic, we investigated whether it desensitizes monocytes or PMN to other chemokines. Preincubation for 15 min with Trx inhibited the chemotactic response of monocytes to MCP-1, but not to fMLP. This effect was independent of whether Trx was present during the chemotaxis assay or only during the preincubation. Preincubation (5 min) with Trx also inhibited the increase in intracellular Ca(2+) induced by MCP-1 in monocytes, but not that induced by fMLP. Preincubation with Trx did not affect the chemotactic response induced in PMN by IL-8. The inhibition of chemotactic and Ca(2+) responses to MCP-1 in monocytes was not due to a down-regulation of the MCP-1 receptor, as shown by receptor binding studies. The Ca(2+) response to MCP-1 was also inhibited by Trx in a CCR2-transfected cell line. It is suggested that Trx inhibits monocyte responses to chemokines by acting downstream of the chemokine receptors. Since there are high concentrations of circulating Trx in infection and inflammatory diseases, this might act as an inhibitor of monocyte migration in vivo
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
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
Human Macrophages Escape Inhibition of Major Histocompatibility Complex-Dependent Antigen Presentation by Cytomegalovirus and Drive Proliferation and Activation of Memory CD4+ and CD8+ T Cells
Full text linkHuman cytomegalovirus (HCMV) persistently infects 40–90% of the human population but in the face of a normal immune system, viral spread and dissemination are efficiently controlled thus preventing clinically signs and disease. HCMV-infected hosts produce a remarkably large amount of HCMV-specific CD4+ and CD8+ T cells that can even reach 20–50% of total T memory cells in the elderly. How HCMV may elicit such large and long-lasting T-cell responses in the absence of detectable viremia has not been elucidated yet. Additionally, HCMV is known to encode several gene products that potently inhibit T-cell recognition of infected cells. The best characterized are the four immune evasive US2, US3, US6, and US11 genes that by different mechanisms account for major histocompatibility complex (MHC) class I and class II degradation and intracellular retention in infected cells. By infecting M1 and M2 human macrophages (Mφ) with the wild-type HCMV strain TB40E or a mutant virus deleted of the four immune evasive genes US2, US3, US6, and US11, we demonstrated that human Mφ counteract the inhibitory potential of the US2-11 genes and remain capable to present peptides via MHC class I and class II molecules. Moreover, by sorting the infected and bystander cells, we provide evidence that both infected and bystander Mφ contribute to antigen presentation to CD4+ and CD8+ T cells. The T cells responding to TB40E-infected Mφ show markers of the T effector memory compartment, produce interferon-γ, and express the lytic granule marker CD107a on the cell surface, thus mirroring the HCMV-specific T cells present in healthy seropositive individuals. All together, our findings reveal that human Mφ escape inhibition of MHC-dependent antigen presentation by HCMV and continue to support T cell proliferation and activation after HCMV infection. Taking into account that Mφ are natural targets of HCMV infection and a site of viral reactivation from latency, our findings support the hypothesis that Mφ play crucial roles for the lifelong maintenance and expansion of HCMV-committed T cells in the human host
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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