1,720,957 research outputs found
Cell-biological mechanisms regulating antigen presentation : Signaling towards adaptive immunity
No full textWe, humans, are exposed daily to millions of potential pathogens, through contact, inhalation, or ingestion. Our ability to avoid infection depends on our immune system, which consists of two distinct, yet interrelated and interacting subsystems: the innate and adaptive immune system. The adaptive immune system remembers previous encounters with specific pathogens and destroys them when they attack again. Elicitation of an adaptive response depends on special white blood cells from the innate immune system.
This thesis focuses on the central role that the intracelllular endosomal transport network in these specialized white blood cells, e.g. B-cells and Dendritic cells (DCs), plays in elicitating an adaptive immune response.
Using live cell fluorescent microscopy on human monocyte-derived DCs, we show that TLR-triggering induced tubulation of late endosomes. However, TLR triggering was insufficient to stimulate tubulation of endosomal recycling compartments (ERCs) in human monocyte-derived DCs. Tubulation of ERCs within human DCs required additional antigen-specific CD8+ T-cell interaction. This tubular remodeling occurs within 30 min of T-cell contact and involved ligation of HLA-A2 and ICAM-1 by T-cell-expressed T-cell receptor and LFA-1, respectively. In addition, wedemonstrated that MICAL-L1 is necessary for tubulation of ERCs in human DCs. Disintegration of microtubules or inhibition of endosomal recycling abolished tubular ERCs, which coincided with reduced antigen-dependent CD8+ T-cell activation.
Another mechanism that is involved in endosomal trafficking and underlies antigen presentation, is receptor-mediated uptake of antigens. We targeted exogenous antigen to Fc gamma receptors (FcγRs), which increased CD8+ T-cell activation following antigen cross-presentation by human monocyte-derived and BDCA-3+ DCs. Using several pharmaceutical inhibitors, we show that FcγR-targeted antigens enter both cytosolic and vacuolar pathways of cross-presentation in human DCs.
Additionally, we report on two related Common Variable Immunodeficiency (CVID) patients carrying a Leucine to Proline replacement at position 3 in the Src kinase B-lymphoid tyrosine kinase (BLK). Unlike in mice, where functional redundancy exists between Src kinases, we show that L3P-BLK abrogates early B-cell Receptor (BCR) signalling, e.g. Syk phosphorylation, required for B-cell proliferation. Moreover, expression of L3P-BLK accelerates late endosomal/lysosomal BCR-antigen complex delivery, causing destruction of the antigen. Together these events reduce antigen presentation as shown by decreased BCR-mediated HLA-DR-restricted antigen-specific activation of CD4+ T-cells. Thus, defective early BCR signalling may affect endosomal trafficking and diminish interdependent antigen presentation. Whether more CVID patients harbour defective endosomal trafficking and antigen presentation is unknown to date, but we showed disturbed early BCR signaling in a significant proportion of pediatric CVID(-like) patients. In these young CVID-patients, BCR or CD20 crosslinking induces less BCR internalization and antibody-mediated CD20 triggering elicited decreased BCR downstream signaling as measured by secondary Ca2+ fluxes.
In conclusion, the work described in this thesis describes the pivotal role of the endosomal network in initiation of adaptive immune responses. Regulating key endosomal processes by interfering a.o. with endosomal tubulation, antigen (Fcγ) receptor-targeting, or Src kinase (BLK) function may contribute to an improvement in future therapeutic intervention strategies contributing to patient survival
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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