1,720,988 research outputs found
Streptococcus pneumoniae modulates the respiratory burst response in human neutrophils
No full textThe gram-positive pathogen Streptococcus pneumoniae is the most common cause
of community-acquired pneumonia and is responsible for high morbidity and
mortality worldwide. A major feature of pneumococcal pneumonia is an abundant
neutrophil infiltration. In this work we observed that the R6 nonencapsulated
S. pneumoniae strain induced a higher oxidative burst in neutrophils compared
with its capsulated progenitor D39, by triggering neutrophil NADPH oxidase to
produce more reactive oxygen intermediates (ROI) and by interfering with the
neutrophil kinase signalling pathway. In addition, we evaluated the possibility that
the capsule, lacking in R6 but present in D39, could modulate the S. pneumoniaeinduced
neutrophil respiratory burst. In this respect, three knock-out isogenic
mutants (D39DCPS2E, D39DCPS-R6 and R6DCPS-R6) that were unable to
synthesize the capsule, were tested for their capability of inducing the release of
neutrophil-ROIs. The results indicate that the mutants behaved similarly to their
wild-type parental strains in enhancing respiratory burst activity, suggesting
that the capsule itself is not directly involved in modulating the neutrophil
oxidative burst induced by S. pneumoniae, but that other genetic differences
between D39 and R6 present elsewhere in the genome could be responsible for
these mechanisms
ChemInform Abstract: Titanocene-Catalyzed Pinacol Couplings: Reagent-Controlled Transition-Metal-Catalyzed Radical Reactions.
No full text
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
Streptococcus pneumoniae induces mast cell degranulation
No full textStreptococcus pneumoniae colonizes the nasopharynx of healthy human carriers, but occasionally can spread in the
body causing severe diseases. The mucosa of the respiratory tract is enriched in mast cells, key players of the innate
immune response. Here, we report on the interaction of various strains of S. pneumoniae with the mast cell line RBL-
2H3. Live, but not heat-killed. bacteria were found to induce mast cell degranulation in a dose- and time-dependent
manner, only partially controlled by cytosolic calcium, with no production of TNF-y and IL-6. Non-encapsulated
pncumococcal strains exhibited different potencies in triggering mast cells. We propose here that the induction of mast
cell dcgranulation by pneumococcal factors not accompanied by the production of pro-inflammatory cytokines may he
a specific strategy elaborated by this bacterium to promote its own spreading from the respiratory mucosa into the
environment
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
Streptococcus pneumoniae induces mast cell degranulation
No full textStreptococcus pneumoniae colonizes the nasopharynx of healthy human carriers, but occasionally can spread in the body causing severe diseases. The mucosa of the respiratory tract is enriched in mast cells, key players of the innate immune response. Here, we report on the interaction of various strains of S. pneumoniae with the mast cell line RBL-2H3. Live, but not heat-killed, bacteria were found to induce mast cell degranulation in a dose- and time-dependent manner, only partially controlled by cytosolic calcium, with no production of TNF-alpha and IL-6. Non-encapsulated pneumococcal strains exhibited different potencies in triggering mast cells. We propose here that the induction of mast cell degranulation by pneumococcal factors not accompanied by the production of pro-inflammatory cytokines may be a specific strategy elaborated by this bacterium to promote its own spreading from the respiratory mucosa into the environment
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