1,720,997 research outputs found
The pulmonary immunopathology of sudden infant death syndrome
No full textThe work in this thesis tests the hypothesis that SIDS infants suffer an abnormal immunological reaction prior to death which results in respiratory obstruction and fatal hypoxia. The triggering factor for this reaction is likely to be a common bacterial or viral antigen. The inflammatory cell population within the pulmonary parenchyma of cases of SIDS, non-pulmonary death controls and pneumonia deaths, has been characterised by immunocytochemistry on paraffin wax embedded tissue sections and snap-frozen tissue. Examination of paraffin wax embedded tissue revealed a significant increase in the pulmonary parenchyma of eosinophils, CD3+ T cells, CD20+ B cells and mast cells compared to deaths from non-pulmonary causes. Neutrophil numbers were significantly reduced in SIDS cases. Analysis of frozen tissue revealed similar results with an increase also in the numbers of CD4+ and CD8+ T cells. There was no significant expansion of any of the variable ( chains and only a small increase in the levels of expression of the ( T cell receptor. Immunocytochemical analysis of the cytokine profile in the pulmonary parenchyma revealed a higher number of cells storing the cytokines Interleukin-4 (IL-4), IL-5, IL-8, IL-10, IL-13 and tumour necrosis factor-( in SIDS cases, but similar numbers of cells storing IL-1(, IL-2, IL-12 as controls. Serum analysis demonstrated a significant increase in the concentration of mast cell tryptase and eosinophil cationic protein, but only a small increase in the concentration of cotinine, whilst mast cell ultrastructural analysis revealed no evidence for anaphylactic-type degranulation. The increased levels of eosinophils, mast cells, B cells and T cells show that there is an inflammatory infiltrate in the lungs of SIDS victims at death. This is probably controlled by the CD4 helper T cell and the release of cytokines which fit the Th2 cytokine profile.</p
TGF-? isoform release and activation during in vitro bronchial epithelial wound repair
No full textRestitution of an epithelial layer after environmental or biological damage is important to maintain the normal function of the respiratory tract. We have investigated the role of transforming growth factor (TGF)-beta isoforms in the repair of layers of 16HBE 14o- bronchial epithelial-derived cells after damage by multiple scoring. ELISA showed that both latent TGF-beta 1 and TGF-beta 2 were converted to their active forms 2 h after wounding. Time-lapse microscopy showed that the addition of TGF-beta 1, but not TGF-beta 2, progressively increased the rate of migration of damaged monolayers at concentrations down to 250 pg/ml. This increase was blocked by addition of a neutralizing TGF-beta 1 antibody. Phase-contrast microscopy and inhibition of proliferation with mitomycin C showed that proliferation was not required for migration. These results demonstrate that conversion of latent to active TGF-beta 1 and TGF-beta 2 during in vitro epithelial wound repair occurs quickly and that TGF-beta 1 speeds epithelial repair. A faster repair may be advantageous in preventing access of environmental agents to the internal milieu of the lung although the production of active TGF-beta molecules may augment subepithelial fibrosis
Basement membrane pores in human bronchial epithelium: a conduit for infiltrating cells?
No full textThis study reports the presence of oval-shaped pores in the basement membrane of the human bronchial airway that may be used as conduits for immune cells to traffic between the epithelial and mesenchymal compartments. Human bronchial mucosa collected after surgery was stripped of epithelial cells without damaging the basement membrane. Both scanning and transmission electron microscopy showed oval-shaped pores 0.75 to 3.85 µm in diameter in the bronchial basement membrane at a density of 863 pores/mm2. Transmission electron microscopy showed that the pores spanned the full depth of the basement membrane, with a concentration of collagen-like fibers at the lateral edges of the pore. Infiltrating cells apparently moved through the pores, both in the presence and absence of the epithelium. Taken together, these results suggest that immune cells use basement membrane pores as predefined routes to move between the epithelial and mesenchymal compartments without disruption of the basement membrane. As a persistent feature of the basement membrane, pores could facilitate inflammatory cell access to the epithelium and greatly increase the frequency of intercellular contact between trafficking cells
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
Interactions between endothelial cells and epithelial cells in a combined cell model of airway mucosa: effects on tight junction permeability
No full textEnvironmental particulates impact first on airway epithelium, whereas circulating infiltrating cells are recruited through the underlying endothelium. An effective cellular immune response requires coordination between endothelium and epithelium. The authors have developed a bilayer culture model consisting of human bronchial epithelial derived cells (16HBE 14o-) and human umbilical vein endothelial cells (HUVECs) cultured as confluent layers on either side of a porous membrane. Confocal microscopy with epithelial and endothelial-specific antibodies showed segregated cell layers. By scanning and transmission electron microscopy, both cell types are polarized and tight junctions formed at the apical interface between cells. Epithelial cells grown in a bilayer showed significantly increased transepithelial resistance (TER) of 2260 +/- 64 Omega.cm(2) compared to epithelial or endothelial monolayers alone (1400 +/- 70 or 80 +/- 12 Omega.cm(2), respectively). This reflected decreased permeability and was unrelated to cell density or height. Increased TER coincided with increased occludin mRNA and protein in the epithelial cell layer as determined by polymerase chain reaction (PCR) and immunoblotting. Conditioned medium showed that decreased permeability was mediated by soluble endothelial-derived factor(s). This model reflects the in vivo relationship of human airway endothelial cells and epithelial cells. Altered tight junction permeability in cocultures indicates that these cells can work together as an active part of the mucosal barrier
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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