1,721,746 research outputs found
The amplification of TCR signaling by dynamic membrane microdomains
No full textModulation of T-cell receptor (TCR) signaling is essential for the regulation of T-cell responses to infectious agents. Recently, many laboratories have suggested that TCR triggering might be compartmentalized in plasma membrane microdomains called rafts. Results on the role of lipid rafts as signaling units in TCR triggering suggest that rafts might be used by T cells to fine-tune their immune responsiveness
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
[Clinical and cytological findings in chromium rhinopathy]
No full textGli Autori hanno studiato le alterazioni della mucosa nasale in un campione di soggetti esposti all'azione del cromo. E' stato eseguito un esame obbiettivo O.R.L. e un esame citodiagnostico condotto con la tecnica di Papanicolau. E' stata trovata una buona correlazione tra l'esame obbiettivo O.R.L. e l'esame del secreto. Gli Autori sottolineano l'importanza del raffronto tra l'esame obbiettivo e citologico ai fini della medicina preventiva e dell'igiene industriale per rilevare la presenza di alterazioni citologiche (metaplasie, metacromasia, segni di sofferenza cellulare) quando ancora la sintomatologia soggettiva sia scarsa o addirittura muta
Lipid-based membrane microdomains in T cell activation
No full textThe immune system is able to mount an immune response against antigens present in the body at very low concentrations and, at the same time, to discriminate precisely between an infectious stimulus and a non-infectious one. During T cell activation, this sensitivity and specificity are achieved by mechanisms of sustained interactions with antigen-presenting cells (APC) as well as by tunable activation thresholds and signal modulation. Thus, in addition to the interaction between the T cell receptor (TCR) and its ligand, T cell activation depends on the combination of many other events involving costimulatory and inhibitory receptors, actin cytoskeleton and lipid membrane microdomains. Lipid rafts, shingolipid- and cholesterol-rich membrane microdomains, seem to be primarily involved in initiation and propagation of the signal transduction cascade associated to lymphocyte activation and might be used by T cells to fine-tune their immune responsiveness. In this article, we discuss recent results indicating that rafts are responsible for the spatial and temporal organization of the T cell signal transduction
Effects of cadmium on lymphocyte proliferation and macrophage activation in catfish, Ictalurus melas
No full textThe effects of cadmium (Cd) (in vitroandin vivo) on phytohaemoagglutinin(PHA)- or lipopolysaccharide(LPS)-induced lymphocyte proliferation were investigated in the catfish,Ictalurus melas. The effects of Cd on macrophage activation by Concanavallina A orSaccharomyces cerevisiae, as measured by superoxide (O2-) production, were investigated. Dose-independent (except at 2 μmCd) inhibition of T cell stimulation and dose-dependent inhibition of B cell stimulation, by lymphocytes exposedin vitroto 2-40 μmCd, was found.In vivo, 20 μg l-1Cd inhibited both PHA- and LPS-induced lymphocyte proliferation, at 4 days of exposure and throughout the duration of the experiment. During the first week of exposure, Cd significantly decreased spontaneous3H-methyl-thymidine uptake from unstimulated lymphocytes; however, 15 days after exposure unstimulated cells recovered their basal level of spontaneous thymidine uptake.In vitro2-40 μmCd enhanced O2-production by activated macrophages, while the addition of 50-100 μmCd had no significant effects
Lipid rafts in lymphocyte activation and migration
No full textFunctional polarization of leukocytes is a requisite to accomplish immune function. Immune synapse formation or chemotaxis requires asymmetric redistribution of membrane receptors, signaling molecules and the actin cytoskeleton. There is increasing evidence that compartmentalization of the plasma membrane into distinct lipid microdomains is pivotal in establishing and maintaining leukocyte polarity. Specific rafts assemble into large-scale domains to create plasma membrane asymmetries at specific cell locations, thus coordinating temporally and spatially cell signaling in these processes. In this review we discuss the roles of lipid rafts as organizers of T lymphocyte polarity during cell activation and migration
Lymphocyte lipid rafts: structure and function
No full textEvidence has accumulated over the past few years to suggest that specialized plasma membrane regions enriched in cholesterol and glycolipids, called 'lipid rafts', are primarily involved in the initiation and propagation of the signal transduction cascade associated with lymphocyte activation. Considering the multitude of recent and often contradictory data, however, it appears that a critical reconsideration of the role of lipid rafts in lymphocyte activation is necessary and timely, particularly in light of a series of new experimental results that challenge the traditional view of the role of lipid rafts in lymphocyte activation
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
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