758 research outputs found
Compte rendu du colloque hispano-français de géomorphologie
No full textHoyos Gómez M., Vergnolle Christine. Compte rendu du colloque hispano-français de géomorphologie. In: Mélanges de la Casa de Velázquez, tome 21, 1985. pp. 469-471
Stability/Instability of Conductivity and Work Function Changes of ITO Thin Films, UV-Irradiated in Air or Vacuum. Measurements by the Four-Probe Method and by Kelvin Force Microscopy
No full textThis study shows that, after UV-irradiation in air or vacuum, conductivity and work function of ITO and In2O3 come back to their initial values in a few hours or minutes. In addition to this instability, one of the reported drawbacks of ITO is the indium diffusion into the organic layers of operating LED, leading to performance degradation. So, we have reconsidered ITO as transparent anode and explored alternatives such as NiO
Fault interaction and stress triggering of 20th century earthquakes in Mongolia
No full textJournal of Geophysical Research, v. 108, n. B10, p. 2503, 2003. http://dx.doi.org/10.1029/2002JB002375International audienceMogod earthquake (sequence). Each of the larger (M ! 8) earthquakes involved strike-slip faulting averaging more than 5 m and rupture lengths of several hundred kilometers. Available geologic data indicate that recurrence intervals on the major source faults are several thousands of years and distances of about 400 km separate the respective rupture areas. We propose that the occurrences of these and many smaller earthquakes are related and controlled to a large extent by stress changes generated by the compounded static deformation of the preceding earthquakes and subsequent viscoelastic relaxation of the lower crust and upper mantle beneath Mongolia. We employ a spherically layered viscoelastic model constrained by the 1994-2002 GPS velocity field in western Mongolia [Vergnolle et al., 2003]. Using the succession of twentieth century earthquakes as sources of deformation, we then analyze the time-dependent change in Coulomb failure stress (Ás f). At remote interaction distances, static Ás f values are small. However, modeled postseismic stress changes typically accumulate to several tenths of a bar over time intervals of decades. Almost all significant twentieth century regional earthquakes (M ! 6) with well-constrained fault geometry lie in positive Ás f lobes of magnitude about +0.5 bar. Our results suggest that significant stress transfer is possible among continental faults separated by hundreds of kilometers and on timescales of decades
Polyunsaturated fatty acid metabolism signature in ischemia differs from reperfusion in mouse intestine.
No full textPolyunsaturated fatty acid (PUFA) metabolites are bioactive autoacoids that play an important role in the pathogenesis of a vast number of pathologies, including gut diseases. The induction and the resolution of inflammation depend on PUFA metabolic pathways that are favored. Therefore, understanding the profile of n-6 (eicosanoids)/n-3 (docosanoids) PUFA-derived metabolites appear to be as important as gene or protein array approaches, to uncover the molecules potentially implicated in inflammatory diseases. Using high sensitivity liquid chromatography tandem mass spectrometry, we characterized the tissue profile of PUFA metabolites in an experimental model of murine intestinal ischemia reperfusion. We identified temporal and quantitative differences in PUFA metabolite production, which correlated with inflammatory damage. Analysis revealed that early ischemia induces both pro-inflammatory and anti-inflammatory eicosanoid production. Primarily, LOX- (5/15/12/8-HETE, LTB4, LxA4) and CYP- (5, 6-EET) metabolites were produced upon ischemia, but also PGE3, and PDx. This suggests that different lipids simultaneously play a role in the induction and counterbalance of ischemic inflammatory response from its onset. COX-derived metabolites were more present from 2 to 5 hours after reperfusion, fitting with the concomitant inflammatory peaks. All metabolites were decreased 48 hours post-reperfusion except for to the pro-resolving RvE precursor 18-HEPE and the PPAR-γαμμα agonist, 15d-PGJ2. Data obtained through the pharmacological blockade of transient receptor potential vanilloid-4, which can be activated by 5, 6-EET, revealed that the endogenous activation of this receptor modulates post-ischemic intestinal inflammation. Altogether, these results demonstrate that different lipid pathways are involved in intestinal ischemia-reperfusion processes. Some metabolites, which expression is severely changed upon intestinal ischemia-reperfusion could provide novel targets and may facilitate the development of new pharmacological treatments
A vasculo-protective circuit centered on lipoxin A4 and aspirin-triggered 15-epi-lipoxin A4 operative in murine microcirculation
No full textEndogenous protective pathways mitigate the overshooting of inflammation after sterile
or infectious injury. Here we report that formyl peptide receptor 2 (Fpr2/3) null mice display
a major phenotype with exacerbated vascular inflammation observed postischemia reperfusion
(IR) injury of the mesenteric artery, characterized by marked neutrophil adhesion
and extravasation as visualized by intravitalmicroscopy. Analysis of endogenous agonists
for Fpr2/3 revealed that lipoxin A4 (LXA4) was generated by platelet/neutrophil aggregates
during ischemia: this cellular response was attenuated in Fpr2/32/2 mice; hence, LXA4
levels were lower after 30 minutes’ ischemia, and associated with augmented vascular
inflammation in the reperfusion (45-180 minutes) phase. Exogenous delivery of LXA4
attenuated IR-mediated inflammation in Fpr2/31/1 but not Fpr2/32/2 mice; conversely, an
Fpr2/3 antagonist skewed the vascular phenotype of Fpr2/31/1 mice to that of Fpr2/32/2
animals. Such LXA4-based circuit could be activated by aspirin (30-100 mg/kg), which
triggered formation of 15-epi-LXA4 in wild-typemice, yet it was effective in Fpr2/32/2 mice. In summary,we propose that during ischemia,
neutrophil Fpr2/3 controls platelet/neutrophil aggregates with the rapid generation of circulating LXA4, which in turn modulates
downstream vascular inflammatory responses evident during the reperfusion phase
Serine Protease Inhibition Reduces Post-Ischemic Granulocyte Recruitment in Mouse Intestine.
No full textProteinase-activated receptor 2 is an anti-inflammatory signal for colonic lamina propria lymphocytes in a mouse model of colitis
No full textThe proteinase-activated receptor 2 (PAR-2) is a member of a family of G protein-coupled receptors for proteases. Proteases cleave PARs within the extracellular N-terminal domains to expose tethered ligands that bind to and activate the cleaved receptors. PAR-2 is highly expressed in colon in epithelial and neuronal elements. In this study we show that PAR-2 activation prevents the development and induces healing of T helper cell type 1-mediated experimental colitis induced by intrarectal administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS) in mice. A role for PAR-2 in the protection against colon inflammation was explored by the use of SLIGRL-NH2, a synthetic peptide that corresponds to the mouse tethered ligand exposed after PAR-2 cleavage. TNBS-induced colitis was dose-dependently reduced by the administration of SLIGRL-NH2, whereas the scramble control peptide, LSIGRL-NH2, was un-effective. This beneficial effect was reflected by increased survival rates, improvement of macroscopic and histologic scores, decrease in mucosal content of T helper cell type 1 cytokines, protein, and mRNA, and a diminished myeloperoxidase activity. SLIGRL-NH2, but not the scramble peptide, directly inhibited IFN-gamma secretion and CD44 expression on lamina propria T lymphocytes. Protection exerted by PAR-2 in TNBS-treated mice was reverted by injecting mice with a truncated form of calcitonin gene-related peptide and by sensory neurons ablation with the neurotoxin capsaicin. Collectively, these studies show that PAR-2 is an anti-inflammatory receptor in the colon and suggest that PAR-2 ligands might be effective in the treatment of inflammatory bowel diseases
Targeting fatty acid amide hydrolase and transient receptor potential vanilloid-1 simultaneously to modulate colonic motility and visceral sensation in the mouse: A pharmacological intervention with N-arachidonoyl-serotonin (AA-5-HT)
No full textBackground: Endocannabinoid anandamide (AEA) inhibits intestinal motility and visceral pain, but it may also be proalgesic through transient receptor potential vanilloid-1 (TRPV1). AEA is degraded by fatty acid amide hydrolase (FAAH). This study explored whether dual inhibition of FAAH and TRPV1 reduces diarrhea and abdominal pain.
Methods: Immunostaining was performed on myenteric plexus of the mouse colon. The effects of the dual FAAH/TRPV1 inhibitor AA-5-HT on electrically induced contractility, excitatory junction potential (EJP) and fast (f) and slow (s) inhibitory junction potentials (IJP) in the mouse colon, colonic propulsion and visceromotor response (VMR) to rectal distension were studied. The colonic levels of endocannabinoids and fatty acid amides were measured.
Key results: CB1-positive neurons exhibited TRPV1; only some TRPV1 positive neurons did not express CB1. CB1 and FAAH did not colocalize. AA-5-HT (100 nM-10 μM) decreased colonic contractility by ~60%; this effect was abolished by TRPV1 antagonist 5'-IRTX, but not by CB1 antagonist, SR141716. AA-5-HT (1 μM-10 μM) inhibited EJP by ~30% and IJPs by ~50%. The effects of AA-5-HT on junction potentials were reversed by SR141716 and 5`-IRTX. AA-5-HT (20 mg/kg; i.p.) inhibited colonic propulsion by ~30%; SR141716 but not 5`-IRTX reversed this effect. AA-5-HT decreased VMR by ~50%-60%; these effects were not blocked by SR141716 or 5`-IRTX. AA-5-HT increased AEA in the colon.
Conclusions and inferences: The effects of AA-5-HT on visceral sensation and colonic motility are differentially mediated by CB1, TRPV1 and non-CB1/TRPV1 mechanisms, possibly reflecting the distinct neuromodulatory roles of endocannabinoid and endovanilloid FAAH substrates in the mouse intestine
Completeness of quasi-filiform Lie algebras
No full textIt is proved that for any quasi-filiform of non-zero rank the solvable Lie algebra obtained by adjoining a maximal torus of outer derivations is complete. Further, for any positive integer m, it is shown that there exist solvable complete Lie algebras with the second ChevalleyEilenberg cohomology group of arbitrary dimension.Depto. de Álgebra, Geometría y TopologíaFac. de Ciencias MatemáticasInstituto de Matemática Interdisciplinar (IMI)TRUEpu
Putting collective intelligence to the enforcement of the Digital Services Act: Report on possible collaborations between the European Commission and civil society organisations
No full textWhile underlying the many ways to build strong cooperation settings between regulators and CSOs, this report focuses on making concrete recommendations for the design of an efficient and influential expert group with the European Commission. The creation of an expert group finds its roots in article 64 and recital 137 of the DSA which require the Commission to develop Union expertise and capabilities. Once established, the experts of this group will be able to bring evidence-based information directly to the Commission and specific expertise on the protection of fundamental rights and the safety of users online. By instituting an expert group, the Commission will not only benefit from valuable expert knowledge but will also demonstrate its willingness to put in place an efficient enforcement system based on collective intelligence. Aside from the establishment of an expert group, other cumulative mechanisms will also help the DSA’s enforcement to thrive. Civil society organisations should, for instance, consider organising regular crowdsourcing events to deep-dive and analyse the data published by entities covered by the transparency obligations. As it has done in the past, the Commission can sponsor these events and be a direct beneficiary of their results. Another way for civil society organisations to bring information to the Regulator is by legal action, including by making complaints to the regulators
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