1,721,179 research outputs found
Lactobacillus crispatus M247: azioni immuno - modulanti e interazioni molecolari con l' epitelio intestinale
No full textCon il primo lavoro è stato identificato un tratto fenotipico di un ceppo di L.crispatus associato alla capacità di persistere e colonizzare il colon dell’ospite e di modificarene la composizione microbica, tale L.crispatus M247 è in grado di modificare, nell’epitelio del colon, il livello di espressione dei TLR2 dei TLR4 sia in vitro che in vivo. Con il secondo studio si identifica un meccanismo antinfiammatorio, prima sconosciuto, indotto da un ceppo probiotico che coinvolge l’attivazione di PPAR-γ e fornisce una nuova visuale sui meccanismi molecolari coinvolti nel dialogo tra epitelio intestinale e microbiota simbionte.The colonic microbiota is a major modulator of the mucosal immune system; therefore, its manipulation through
supplementation with probiotics may significantly affect the host’s immune responses. Since different probiotics
seem to exert various effects in vivo, we tested the relevance of the autoaggregation phenotype on the intestinal
persistence of lactobacilli and their ability to modulate the host’s innate immune responses. After 14 days of diet
supplementation, the aggregating strain Lactobacillus crispatus M247 but not aggregation-deficient isogenic mutant
MU5 was recovered from the feces and colonic mucosa of mice. This observation was confirmed by strain-specific
PCR amplification and by Lactobacillus-specific denaturing gradient gel electrophoresis analysis. Indeed, L. crispatus
M247 increased Toll-like receptor 2 (TLR2) mRNA levels, while it reduced TLR4 mRNA and protein levels in
the colonic mucosa, whereas MU5 was ineffective. In colonic epithelial cells (CMT-93 cells) L. crispatus M247 but
not MU5 induced time-dependent extracellular signal-regulated kinase-1 (ERK1) tyrosine phosphorylation and
TLR modulation, which were abolished in the presence of PD98059 (an ERK1 inhibitor). To assess the functional
relevance of probiotic-induced TLR modulation, we determined the consequences of L. crispatus preexposure on
TLR4 (lipopolysaccharide [LPS]) and TLR2 [Pam3Cys-Ser-(Lys)4] ligand-mediated effects in intestinal epithelial
cells. Preexposure to L. crispatus M247 blunted LPS-induced interleukin-6 (IL-6) release and inhibition of CMT-93
migration over a wound edge, whereas it enhanced TLR2-mediated IL-10 up-regulation. In summary, the aggregation
phenotype is required for L. crispatus persistence in the colon and for modulation of TLR2/TLR4 expression
through an ERK-dependent pathway. We speculate that the aggregation phenotype in L. crispatus M247 is required
to temper epithelial cell responsiveness to bacterial endotoxins, which thus affects the evolution of intestinal
inflammatory processes. Accumulating evidence indicates
that the peroxisome proliferator activated receptor
(PPAR)- is a major player in maintaining intestinal
mucosa homeostasis, but whether PPAR- is
directly involved in probiotic-mediated effects and
the molecular events involved in its activation are not
known. Methods: We investigated the role of PPAR-
in the immunomodulatory effects of Lactobacillus
crispatus M247 on intestinal epithelial cells (IEC) and
the role of probiotic-derived H2O2 on PPAR- activity.
Results: L crispatus M247 supplementation in
mice significantly increased PPAR- levels and transcriptional
activity in the colonic mucosa. L crispatus
M247 induced PPAR- nuclear translocation and enhanced
transcriptional activity in epithelial (CMT-93)
cells, as demonstrated by the increased luciferase activity
of a PPAR- –responsive element, PPAR- –
responsive gene up-regulation, and reduced activity
of an nuclear factor- B–responsive element. Pharmacologic
PPAR- inhibition or silencing by small interfering
RNA cancelled the L crispatus M247–mediated
effects in CMT-93 cells. Because Lactobacillus
strains producing little H2O2 failed to activate
PPAR- , we investigated the role of L crispatus M247–
derived H2O2 in PPAR- activation. L crispatus M247
induced a transient rise in intracellular H2O2 and
PPAR- transcriptional activity was cancelled by
antioxidant or H2O2 scavenger. Toll-like receptor
(TLR)-2 was not required for PPAR- up-regulation
mediated by L crispatus M247 in mice, although the
protective effects of L crispatus M247 on dextran sodium
sulfate-induced colitis were less pronounced in
TLR-2 / mice. Conclusions: L crispatus M247 uses
H2O2 as a signal transducing molecule to induce
PPAR- activation in IEC, directly modulating epithelial
cell responsiveness to inflammatory stimuli
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
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
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