Prise en charge des fièvres sans foyer infectieux clinique chez l'enfant de trois mois à trois ans aux urgences pédiatriques de Bordeaux

FORT-DE-FRANCE-CHRU-BU (972332102) / SudocBORDEAUX2-BU Santé (330632101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Retinoic acid regulates the developmental expression of dopamine D2 receptor in rat striatal primary cultures.

International audienceThe time course of D2 receptor expression assessed by the levels of the corresponding binding sites and mRNA was studied in rat striatum during ontogenesis and in primary cultures of cells taken at embryonic day (E) 17 and postnatal day (P) 4. In the two experimental situations, the amount of D2 receptor mRNA and number of binding sites increased regularly from E16 to P15, indicating that expression of D2 receptors in striatal neurons occurs independently from a dopaminergic input. Incubation of striatal primary cultures with 10(-5) M retinoic acid significantly increased the level of D2 receptor mRNA, whereas thyroid hormone, vitamin D3, and steroid hormones (estradiol, testosterone, and corticosterone) had no effect. The transcriptional activity of the rat D2 receptor gene promoter region, which bears a retinoic acid-responsive element, was increased by retinoic acid in transfected C6 glioma cells but not in transfected MMQ prolactin cells. Thyroid hormone and vitamin D3 were not effective in either cell line. Finally, mutations of the putative retinoic acid-responsive element inhibited the transcriptional effect of retinoic acid. These results suggest that retinoic acid is a key factor in regulation of the embryonic onset of the dopaminergic D2 receptor

Heterodimerization of Endothelin-converting Enzyme-1 Isoforms Regulates the Subcellular Distribution of This Metalloprotease

International audienceEndothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced from a single gene through the use of alternate promoters. These isoforms share the same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated the distribution of ECE-1 isoforms in transfected AtT-20 neuroendocrine cells. Whereas ECE-1a and 1c were present at the plasma membrane, ECE-1b and ECE-1d were retained inside the cells. We found that both intracellular isoforms were concentrated in the endosomal system: ECE-1d in recycling endosomes, and ECE-1b in late endosomes/multivesicular bodies. Leucine-based motifs were involved in the intracellular retention of these isoforms, and the targeting of ECE-1b to the degradation pathway required an additional signal in the N terminus. The concentration of ECE-1 isoforms in the endosomal system suggested new functions for these enzymes. Potential novel functions include redistribution of other isoforms through direct interaction. We have showed that ECE-1 isoforms could heterodimerize, and that in such heterodimers the ECE-1b targeting signal was dominant. Interaction of a plasma membrane isoform with ECE-1b resulted in its intracellular localization and decreased its extracellular activity. These data demonstrated that the targeting signals specific for ECE-1b constitute a regulatory domain per se that could modulate the localization and the activity of other isoforms

A simple way to use X-ray micro-tomography to infer elastic properties of heterogeneous materials: application to sedimentary rocks

Abstract Macroscopic mechanical properties of materials depend directly on their microstructure. Microscopy, and more specifically tomography, is a key method for studying microstructures. Here, we propose a simple way to use an X-ray tomogram to infer local elastic properties. We distinguish between two scenarios of microstructure images. In the first scenario, the material is composed by very apparent phases so the image can be easily segmented into a set of subspaces with homogenous properties. In the second scenario, the image, as that of sedimentary rocks, contains poorly contrasted phases, including strong intra-phase heterogeneities. For this case, we propose an alternative to segmentation techniques in order to factor in material heterogeneities. To do this, we use the local X-ray attenuation to define elastic moduli. Then, we compute up-scaled elastic moduli by solving the mechanical equilibrium. Finally, we confirm our method by comparing the up-scaled elastic moduli to indentation experiments performed at the same scale

A new family of orphan G protein-coupled receptors predominantly expressed in the brain1The nucleotide sequence of the receptor cDNA reported in this paper has been submitted to the GenBank/EMBL Data Libraries with the accession number Y16280.1

AbstractThe cloning of a cDNA encoding a G protein-coupled receptor homologous to the endothelin type B receptor, but unable to bind endothelin, was recently reported and termed ETBR-LP. We report here the isolation of a human cDNA encoding a receptor that is highly related to ETBR-LP and which was therefore termed ETBR-LP-2. Comparison of the two amino acid sequences revealed 68% overall homology and 48% identity. As is the case for ETBR-LP, the new receptor is strongly expressed in the human central nervous system (e.g. in cerebellar Bergmann glia, cerebral cortex, internal capsule fibers). Membranes of HEK-293 cells stably expressing ETBR-LP-2 did not bind endothelin-1, endothelin-2, endothelin-3, bombesin, cholecystokinin-8 or gastrin-releasing peptide