1,720,958 research outputs found
Paracrine up-regulation of monocyte cyclooxygenase-2 by platelets : role of TGF-beta1
No full textIntroduction. Cellular interactions between platelets and leukocytes provide
a crucial mechanism for intercellular communication in thrombosis
and inflammation. We have examined the role of platelets and
platelet-derived products on cyclooxygenase-2 (Cox-2) induction in
adherent monocytes and addressed the signaling pathways involved.
Methods. Human monocytes were co-cultured with autologous platelets
or platelet releasates or exposed to mediators contained in platelet alphagranules
for 4-24 h. Cox-2 protein and mRNA were determined by Western
and RT-PCR. Thromboxane B2 and prostaglandin E2 synthesis as
index of Cox-2 activity, and levels of TGF-b1 in platelet releasates were
measured by EIA. Results. Activated platelets induce rapid and transient
Cox-2 de novo synthesis in adherent monocytes. The effect is dependent
upon platelet number but not upon cell-cell contact. Platelet-induced
Cox-2 was not affected by prevention of platelet TxA2 synthesis or
microparticle formation but was blunted by inhibition of platelet alphagranule
secretion. TGF-b1 induced Cox-2 expression and activity at concentrations
within the range of those detected in releasates from activated
platelets. The time course of monocyte Cox-2 induction by TGF-b1
was identical to that observed with platelet releasates. Moreover, TGF-
b1 receptor blockade completely abolished platelet-induced Cox-2
expression. p38 MAPK activation represents a common transduction
pathway through which activated platelets and rTGF-b1 induce Cox-2
in monocytes. Conclusions. Data suggest that TGF-b1 released by activated
platelets is pivotal in Cox-2 induction in monocytes and further supports
the key role of platelets in inflammatory and reparative response
Reactive oxygen species signal for cyclooxygenase-2 induction in human endothelial cells : role in the repair of wound
No full text
Cyclooxygenase-2 mediates hydrogen peroxide-induced wound repair in human endothelial cells
No full textCyclooxygenase-2 (Cox-2) metabolites produced by endothelial cells, particularly prostacyclin and prostaglandin E2, profoundly affect vascular tone, regional blood flow, and angiogenesis. We have previously shown that reactive oxygen species induce Cox-2 expression in human endothelial cells (HUVEC), either on their own or as components of the signaling pathway triggered by TNFα, the prototypical inflammatory cytokine. Here we investigated the role of Cox-2 induced by hydrogen peroxide (H2O2), either exogenous or endogenously generated by TNFα, in the repair of a mechanically wounded HUVEC monolayer and probed the sources of H2O2 that are involved in TNFα signaling and the pathways through which H2O2 modulates Cox-2 expression. Results indicate that H2O2-induced Cox-2 activity participates in the repair of wounded monolayers. Both NADPH oxidase and the mitochondrial electron transport chain are involved in H2O2 generation. Signaling triggered by H2O2 for Cox-2 induction acts by increasing the protein tyrosine kinase phosphorylation that follows inhibition of protein phosphatase activity. The activation of p38 MAPK and its interaction in the inhibition of serine/threonine phosphatase activity are both critical steps in this event. We conclude that Cox-2 induced by H2O2 plays an important role in promoting endothelial wound repair after injury, so that the cardioprotective effect of Cox-2 is due at least in part to its power of healing damaged endotheliu
Cyclooxygenase-2 is critical for hydrogen peroxide-mediated wound repair in human endothelial cells
No full textParacrine up-regulation of monocyte cyclooxygenase-2 by platelets: Role of transforming growth factor-beta1
No full textTo examine the role of platelets and platelet-derived products on cyclooxygenase-2 (Cox-2) induction in adherent monocytes and to address the signaling pathways involved. METHODS: Platelets and monocytes were obtained from peripheral blood of healthy donors. Adherent monocytes were co-cultured with autologous platelets or platelet releasates or exposed to mediators contained in platelet alpha-granules (either from platelet source or recombinant) for 4-24 h. Cox-2 protein and mRNA were determined by Western and RT-PCR analysis, respectively. Thromboxane B(2) (TxB(2)) and prostaglandin E(2) (PGE(2)) synthesis as index of Cox-2 activity, and levels of transforming growth factor-beta1 (TGF-beta1) in platelet releasates were measured by enzyme immunoassay (EIA). RESULTS: Activated platelets induce rapid and transient Cox-2 de novo synthesis in adherent monocytes. The effect is dependent upon the platelet number but not upon cell-cell contact. Platelet-induced Cox-2 was not affected by prevention of platelet TxA(2) synthesis or microparticle formation but was blunted by inhibition of platelet alpha-granule secretion. TGF-beta1, either platelet-derived or recombinant (rTGF-beta1), induced Cox-2 expression and activity in adherent monocytes at concentrations within the range of those detected in releasates from activated platelets; this effect was not shared by recombinant platelet-derived growth factor (rPDGF(BB)). The time course of Cox-2 induction by TGF-beta1 in monocytes was identical to that observed with platelet releasates. Moreover, TGF-beta1 receptor blockade completely abolished platelet-induced Cox-2 expression. p38 MAPK activation represents a common transduction pathway through which activated platelets and rTGF-beta1 induce Cox-2 in monocytes. CONCLUSION: These findings suggest that TGF-beta1 released by activated platelets has a pivotal role in Cox-2 induction in monocytes and further supports the key role of platelets in the inflammatory and reparative response
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
- …
