[Importance de la nature, des opportunités d'activités, de leur accessibilité et de leur publicisation pour favoriser la santé positive, la participation sociale et l'équité en santé d'Estriens âgés].

Cette étude visait à explorer comment les composantes clés de l'environnement des communautés favorisent les résultantes de santé d'Estriens âgés, plus précisément leur santé positive, leur participation sociale et leur équité en santé. Une étude de cas multiples a été réalisée auprès de cinq communautés estriennes (cas) à l'aide de groupes de discussion focalisée (1/communauté) regroupant un total de 49 participants connaissant bien les communautés respectives, soit 47 aînés, 1 conseillère municipale et 1 technicienne en loisir. En rendant accessible et équitable la réalisation d'activités importantes pour les aînés, la nature, une offre d'activités variée, des moyens de communication efficace et les mesures favorisant l'équité avaient une influence positive sur les résultantes de santé. Des facteurs individuels tels qu'un niveau élevé de scolarité et un statut socioéconomique favorable avaient aussi une influence positive. Ces résultats permettent d'outiller les décideurs souhaitant favoriser un vieillissement actif et en santé.

Insulin allergy: a diagnostic and therapeutic strategy based on a retrospective cohort and a case-control study.

AIMS/HYPOTHESIS: Insulin allergy is a rare but significant clinical challenge. We aimed to develop a management workflow by (1) validating clinical criteria to guide diagnosis, based on a retrospective cohort, and (2) assessing the diagnostic performance of confirmatory tests, based on a case-control study. METHODS: In the retrospective cohort, patients with suspected insulin allergy were classified into three likelihood categories according to the presence of all (likely insulin allergy; 26/52, 50%), some (possible insulin allergy; 9/52, 17%) or none (unlikely insulin allergy; 17/52, 33%) of four clinical criteria: (1) recurrent local or systemic immediate or delayed hypersensitivity reactions; (2) reactions elicited by each injection; (3) reactions centred on the injection sites; and (4) reactions observed by the investigator (i.e. in response to an insulin challenge test). All underwent intradermal reaction (IDR) tests. A subsequent case-control study assessed the diagnostic performance of IDR, skin prick and serum anti-insulin IgE tests in ten clinically diagnosed insulin allergy patients, 24 insulin-treated non-allergic patients and 21 insulin-naive patients. RESULTS: In the retrospective cohort, an IDR test validated the clinical diagnosis in 24/26 (92%), 3/9 (33%) and 0/14 (0%) likely, possible and unlikely insulin allergy patients, respectively. In the case-control study, an IDR test was 80% sensitive and 100% specific and identified the index insulin(s). The skin prick and IgE tests had a marginal diagnostic value. Patients with IDR-confirmed insulin allergy were treated using a stepwise strategy. CONCLUSIONS/INTERPRETATION: Subject to validation, clinical likelihood criteria can effectively guide diabetologists towards an insulin allergy diagnosis before undertaking allergology tests. An IDR test shows the best diagnostic performance. A progressive management strategy can subsequently be implemented. Continuous subcutaneous insulin infusion is ultimately required in most patients. CLINICALTRIALS: gov: NCT01407640.

Characterization of potential TRPP2 regulating proteins in early Xenopus embryos.

Transient receptor potential cation channel-2 (TRPP2) is a nonspecific Ca2+ -dependent cation channel with versatile functions including control of extracellular calcium entry at the plasma membrane, release of intracellular calcium ([Ca2+ ]i) from internal stores of endoplasmic reticulum, and calcium-dependent mechanosensation in the primary cilium. In early Xenopus embryos, TRPP2 is expressed in cilia of the gastrocoel roof plate (GRP) involved in the establishment of left-right asymmetry, and in nonciliated kidney field (KF) cells, where it plays a central role in early specification of nephron tubule cells dependent on [Ca2+ ]i signaling. Identification of proteins binding to TRPP2 in embryo cells can provide interesting clues about the mechanisms involved in its regulation during these various processes. Using mass spectrometry, we have therefore characterized proteins from late gastrula/early neurula stage embryos coimmunoprecipitating with TRPP2. Binding of three of these proteins, golgin A2, protein kinase-D1, and disheveled-2 has been confirmed by immunoblotting analysis of TRPP2-coprecipitated proteins. Expression analysis of the genes, respectively, encoding these proteins, golga2, prkd1, and dvl2 indicates that they are likely to play a role in these two regions. Golga2 and prkd1 are expressed at later stage in the developing pronephric tubule where golgin A2 and protein kinase-D1 might also interact with TRPP2. Colocalization experiments using exogenously expressed fluorescent versions of TRPP2 and dvl2 in GRP and KF reveal that these two proteins are generally not coexpressed, and only colocalized in discrete region of cells. This was observed in KF cells, but does not appear to occur in the apical ciliated region of GRP cells.

Pou3f transcription factor expression during embryonic development highlights distinct pou3f3 and pou3f4 localization in the Xenopus laevis kidney.

The POU (Pit-Oct-Unc) genes encode a large transcription factor family comprising 6 classes (pou1f to pou6f ) involved in many developmental processes, such as cell commitment and differentiation. The pou3f class contains four members (pou3f1, pou3f2, pou3f3, pou3f4) characterized by expression in ectodermal tissue derivatives, such as nervous system and otic vesicle, during mammalian development. In order to obtain insights into the potential conservation of this class of transcription factors in vertebrates, we carried out a phylogenetic analysis and a comprehensive comparative study of pou3f expression in the frog Xenopus laevis. All vertebrates examined possessed members of the four pou3f subfamilies, excepting the zebrafish, which lacked a pou3f4 gene. Whole mount in situ hybridization and real-time quantitative polymerase chain reaction (RT-qPCR) analyses revealed that Xenopus pou3f genes were expressed in the forming neural tube and their expression was maintained in the brain, mostly in the dorsal part, at tailbud stages. The pou3f2, pou3f3, and pou3f4 genes were also expressed in the developing otic vesicle, and pou3f1 in some cells of the epidermis. Besides ectodermal derivatives, pou3f3 and pou3f4 were expressed in the developing kidney. Their expression started at the early tailbud stage in the pronephric anlage and partly overlapped. In the mature pronephric tubule, pou3f3 was restricted to the intermediate tubule, while pou3f4 was also expressed in the distal and connecting tubule. Together, our results highlight a significant conservation of pou3f gene expression in vertebrates and indicate that they may have distinct but also redundant functions during neural and renal development.

TRPP2-dependent Ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment in Xenopus.

In Xenopus laevis embryos, kidney field specification is dependent on retinoic acid (RA) and coincides with a dramatic increase of Ca(2+) transients, but the role of Ca(2+) signaling in the kidney field is unknown. Here, we identify TRPP2, a member of the transient receptor potential (TRP) superfamily of channel proteins encoded by the pkd2 gene, as a central component of Ca(2+) signaling in the kidney field. TRPP2 is strongly expressed at the plasma membrane where it might regulate extracellular Ca(2+) entry. Knockdown of pkd2 in the kidney field results in the downregulation of pax8, but not of other kidney field genes (lhx1, osr1 and osr2). We further show that inhibition of Ca(2+) signaling with an inducible Ca(2+) chelator also causes downregulation of pax8, and that pkd2 knockdown results in a severe inhibition of Ca(2+) transients in kidney field explants. Finally, we show that disruption of RA results both in an inhibition of intracellular Ca(2+) signaling and of TRPP2 incorporation into the plasma membrane of kidney field cells. We propose that TRPP2-dependent Ca(2+) signaling is a key component of pax8 regulation in the kidney field downstream of RA-mediated non-transcriptional control of TRPP2.

Pax8 and Pax2 are specifically required at different steps of Xenopus pronephros development.

The respective role of Pax2 and Pax8 in early kidney development in vertebrates is poorly understood. In this report, we have studied the roles of Pax8 and Pax2 in Xenopus pronephros development using a loss-of-function approach. Our results highlight a differential requirement of these two transcription factors for proper pronephros formation. Pax8 is necessary for the earliest steps of pronephric development and its depletion leads to a complete absence of pronephric tubule. Pax2 is required after the establishment of the tubule pronephric anlage, for the expression of several terminal differentiation markers of the pronephric tubule. Neither Pax2 nor Pax8 is essential to glomus development. We further show that Pax8 controls hnf1b, but not lhx1 and Osr2, expression in the kidney field as soon as the mid-neurula stage. Pax8 is also required for cell proliferation of pronephric precursors in the kidney field. It may exert its action through the wnt/beta-catenin pathway since activation of this pathway can rescue MoPax8 induced proliferation defect and Pax8 regulates expression of the wnt pathway components, dvl1 and sfrp3. Finally, we observed that loss of pronephros in Pax8 morphants correlates with an expanded vascular/blood gene expression domain indicating that Pax8 function is important to delimit the blood/endothelial genes expression domain in the anterior part of the dorso-lateral plate.

Differential expression of arid5b isoforms in Xenopus laevis pronephros.

Arid5b belongs to the ARID family of transcription factors characterised by a helix-turn-helix motif- based DNA-binding domain called ARID (A-T Rich Interaction Domain). In human, alternative splicing leads to long and short isoforms (isoform1 and 2, respectively) which differ in their N-terminal part. In this study, we report the cloning and expression pattern of Xenopus laevis arid5b. We have isolated a full length cDNA that shows homology with the human arid5b isoform1. Furthermore, 5'RACE experiments revealed the presence of a shorter isoform equivalent to the human isoform2. Temporal expression analysis by RT-qPCR indicated that X. laevis arid5b isoform1 and isoform2 are differentially expressed during development. Isoform1 is strongly expressed maternally, while isoform2 expression is essentially restricted to tailbud stages. Spatial expression analysis by whole mount in situ showed that arid5b is predominantly expressed in the developing pronephros. Arid5b mRNAs are detected in the antero-dorsal part of the pronephros anlage at the early tailbud stage and later on, in the proximal part of the pronephric tubule. RT-qPCR analyses with primers that allow to discriminate isoform1 from isoform2 showed that the latter is enriched in the pronephros anlage. In agreement with a specific pronephric signature of the isoform2, we also observed that isoform2 but not isoform1 is upregulated in animal caps induced to form pronephric tissue in response to activin A and retinoic acid. These results indicate that the two arid5b isoforms are differentially expressed and likely play different roles during early Xenopus development.

HNF1B controls proximal-intermediate nephron segment identity in vertebrates by regulating Notch signalling components and Irx1/2.

The nephron is a highly specialised segmented structure that provides essential filtration and resorption renal functions. It arises by formation of a polarised renal vesicle that differentiates into a comma-shaped body and then a regionalised S-shaped body (SSB), with the main prospective segments mapped to discrete domains. The regulatory circuits involved in initial nephron patterning are poorly understood. We report here that HNF1B, a transcription factor known to be involved in ureteric bud branching and initiation of nephrogenesis, has an additional role in segment fate acquisition. Hnf1b conditional inactivation in murine nephron progenitors results in rudimentary nephrons comprising a glomerulus connected to the collecting system by a short tubule displaying distal fates. Renal vesicles develop and polarise normally but fail to progress to correctly patterned SSBs. Major defects are evident at late SSBs, with altered morphology, reduction of a proximo-medial subdomain and increased apoptosis. This is preceded by strong downregulation of the Notch pathway components Lfng, Dll1 and Jag1 and the Irx1/2 factors, which are potential regulators of proximal and Henle's loop segment fates. Moreover, HNF1B is recruited to the regulatory sequences of most of these genes. Overexpression of a HNF1B dominant-negative construct in Xenopus embryos causes downregulation specifically of proximal and intermediate pronephric segment markers. These results show that HNF1B is required for the acquisition of a proximo-intermediate segment fate in vertebrates, thus uncovering a previously unappreciated function of a novel SSB subcompartment in global nephron segmentation and further differentiation.

Retinoic acid-dependent control of MAP kinase phosphatase-3 is necessary for early kidney development in Xenopus.

BACKGROUND INFORMATION: In Xenopus, the functional kidney of the tadpole, the pronephros, forms from the kidney field, which is specified at completion of gastrulation. Specification of the kidney field requires retinoic acid (RA) signalling during gastrulation, while fibroblast growth factor (FGF) signals inhibit should be inhibit this process. RESULTS: We have analysed the functional interactions taking place during gastrulation between RA and FGF signals in the lateral marginal zone (LMZ), that is in the environment of unspecified pronephric mesoderm precursors. Inhibition of FGF receptor (FGFR) signalling with SU5402 does not significantly affect expression of genes encoding RA metabolism enzymes and RA receptor-α in LMZ explants. Furthermore, SU5402 has no effect on the expression of hoxa1, a major RA target in the LMZ, showing that FGF is not antagonising RA in the LMZ. Disruption of RA signalling affects FGF ligand production to some extent, especially FGF8b, but the strongest effect is the down-regulation of the mitogen-activated protein kinase phosphatase-3 (MKP3)-encoding gene, mkp3. A strong up-regulation of mkp3 occurs in response to exogenous RA. This effect is reduced in a context of FGFR inhibition, suggesting that RA and FGF signals are co-operating upstream of mkp3. Mkp3 knockdown results in an inhibition of the kidney field markers pax8 and lhx1 and in a defective development of the pronephros. CONCLUSIONS: FGF is not negatively influencing pronephric specification by antagonising RA signalling. Functional interactions between RA and FGF rather take place at the level of the transcriptional regulation of mkp3, indicating that RA may antagonise FGF signalling at the level of the extracellular signal-regulated kinase (Erk) pathway. A fine tuning of Erk signalling by MKP3 is important for the proper establishment of the kidney field.

Mix.1/2-dependent control of FGF availability during gastrulation is essential for pronephros development in Xenopus.

Although FGFs are known to affect mesoderm patterning, their influence on intermediate mesoderm specification during gastrulation is ignored. Here, we show that pronephros precursors are exposed to FGF, but a strict control of FGF signals is necessary to allow pronephros development. We provide evidence that this control is mediated by the paired-like homeobox genes Mix.1 and Mix.2. Morpholino-based Mix.1/2 knockdown, or repression of Mix.1 target genes with an enRMix.1 construct, causes an expansion of FGF4 and FGF8 expression in the lateral marginal zone at gastrula stage, together with an inhibition of pronephros development at neurula and tailbud stages. Expression of the nephrogenic mesoderm markers Xlim-1 and XPax-8 can be rescued in Mix.1/2 morphants by intrablastocoelic injections of the FGFR inhibitor SU5402 at mid-gastrula stage, showing that inhibition of pronephros development results from an increase of FGF signalling. We further show that Mix.1 overexpression results in the down-regulation of FGF3, 4, 8 and XmyoD, in addition to Xbra. However, cells overexpressing Mix.1 can normally populate somites, indicating that Mix.1 does not affect their fate cell autonomously. These data support the idea that Mix.1/2 regulates levels and/or duration of FGF signals to which pronephros precursors are exposed during gastrulation.

The CB1 receptor antagonist rimonabant reverses the diet-induced obesity phenotype through the regulation of lipolysis and energy balance.

We investigated the molecular events involved in the long-lasting reduction of adipose mass by the selective CB1 antagonist, SR141716. Its effects were assessed at the transcriptional level both in white (WAT) and brown (BAT) adipose tissues in a diet-induced obesity model in mice. Our data clearly indicated that SR141716 reversed the phenotype of obese adipocytes at both macroscopic and genomic levels. First, oral treatment with SR141716 at 10 mg/kg/d for 40 days induced a robust reduction of obesity, as shown by the 50% decrease in adipose mass together with a major restoration of white adipocyte morphology similar to lean animals. Second, we found that the major alterations in gene expression levels induced by obesity in WAT and BAT were mostly reversed in SR141716-treated obese mice. Importantly, the transcriptional patterns of treated obese mice were similar to those obtained in the CB1 receptor knockout mice fed a high-fat regimen and which are resistant to obesity, supporting a CB1 receptor-mediated process. Functional analysis of these modulations indicated that the reduction of adipose mass by the molecule resulted from an enhanced lipolysis through the induction of enzymes of the beta-oxidation and TCA cycle, increased energy expenditure, mainly through futile cycling (calcium and substrate), and a tight regulation of glucose homeostasis. These changes accompanied a significant cellular remodeling and contributed to a reduction of the obesity-related inflammatory status. In addition to a transient reduction of food consumption, increases of both fatty acid oxidation and energy expenditure induced by the molecule summate leading to a sustained weight loss. Altogether, these data strongly indicate that the endocannabinoid system has a major role in the regulation of energy metabolism.