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International audience; BACKGROUND: The clinically appropriate duration of thromboprophylaxis in hospitalized patients with acute medical illnesses is unknown. In this multicenter, randomized, double-blind trial, we evaluated the efficacy and safety of oral rivaroxaban administered for an extended period, as compared with subcutaneous enoxaparin administered for a standard period, followed by placebo. METHODS: We randomly assigned patients 40 years of age or older who were hospitalized for an acute medical illness to receive subcutaneous enoxaparin, 40 mg once daily, for 10±4 days and oral placebo for 35±4 days or to receive subcutaneous placebo for 10±4 days and oral rivaroxaban, 10 mg once daily, for 35±4 days. The primary efficacy outcomes were the composite of asymptomatic proximal or symptomatic venous thromboembolism up to day 10 (noninferiority test) and up to day 35 (superiority test). The principal safety outcome was the composite of major or clinically relevant nonmajor bleeding. RESULTS: A total of 8101 patients underwent randomization. A primary efficacy outcome event occurred in 78 of 2938 patients (2.7%) receiving rivaroxaban and 82 of 2993 patients (2.7%) receiving enoxaparin at day 10 (relative risk with rivaroxaban, 0.97; 95% confidence interval [CI], 0.71 to 1.31; P=0.003 for noninferiority) and in 131 of 2967 patients (4.4%) who received rivaroxaban and 175 of 3057 patients (5.7%) who received enoxaparin followed by placebo at day 35 (relative risk, 0.77; 95% CI, 0.62 to 0.96; P=0.02). A principal safety outcome event occurred in 111 of 3997 patients (2.8%) in the rivaroxaban group and 49 of 4001 patients (1.2%) in the enoxaparin group at day 10 (P

International audience; OBJECTIVE: To summarise and compare the efficacy and safety of various oral anticoagulants (dabigatran, rivaroxaban, apixaban, and vitamin K antagonists) and antiplatelet agents (acetylsalicylic acid) for the secondary prevention of venous thromboembolism. DESIGN: Systematic review and network meta-analysis. DATA SOURCES: Literature search using Medline (1950 to present), Embase (1980 to present), and the Cochrane Register of Controlled Trials using the OVID interface. Publications from potentially relevant journals were also searched by hand. REVIEW METHODS: Randomised controlled trials of patients receiving anticoagulants, antiplatelet drugs, or placebo or observation for secondary prevention of venous thromboembolism. Selected outcomes were rates of recurrent venous thromboembolism and major bleeding. Two reviewers independently extracted data onto standardised forms. RESULTS: 12 articles met our inclusion criteria, with 11,999 patients evaluated for efficacy and 12,167 for safety. All treatments reduced the risk of recurrent venous thromboembolism. Compared with placebo or observation, vitamin K antagonists at a standard adjusted dose (target international normalised ratio 2.0-3.0) showed the highest risk difference (odds ratio 0.07; 95% credible interval 0.03 to 0.15) and acetylsalicylic acid showed the lowest risk difference (0.65; 0.39 to 1.03). Risk of major bleeding was higher with a standard adjusted dose of vitamin K antagonists (5.24; 1.78 to 18.25) than with placebo or observation. Fatal recurrent venous thromboembolism and fatal bleeding were rare. Detailed subgroup and individual patient level data were not available. CONCLUSIONS: All oral anticoagulants and antiplatelet agents investigated in this analysis were associated with a reduced recurrence of venous thromboembolism compared with placebo or observation, although acetylsalicylic acid was associated with the lowest risk reduction. Vitamin K antagonists given at a standard adjusted dose was associated with the greatest risk reduction in recurrent venous thromboembolism, but also the greatest risk of major bleeding.

International audience; BACKGROUND: The use of warfarin reduces the rate of ischemic stroke in patients with atrial fibrillation but requires frequent monitoring and dose adjustment. Rivaroxaban, an oral factor Xa inhibitor, may provide more consistent and predictable anticoagulation than warfarin. METHODS: In a double-blind trial, we randomly assigned 14,264 patients with nonvalvular atrial fibrillation who were at increased risk for stroke to receive either rivaroxaban (at a daily dose of 20 mg) or dose-adjusted warfarin. The per-protocol, as-treated primary analysis was designed to determine whether rivaroxaban was noninferior to warfarin for the primary end point of stroke or systemic embolism. RESULTS: In the primary analysis, the primary end point occurred in 188 patients in the rivaroxaban group (1.7% per year) and in 241 in the warfarin group (2.2% per year) (hazard ratio in the rivaroxaban group, 0.79; 95% confidence interval [CI], 0.66 to 0.96; P

International audience; The mammalian target of rapamycin (mTOR) inhibitors, such as rapalogues, are a promising new tool for the treatment of metastatic gastroenteropancreatic endocrine tumors. However, their mechanisms of action remain to be established. We used two murine intestinal endocrine tumoral cell lines, STC-1 and GLUTag, to evaluate the antitumor effects of rapamycin in vitro and in vivo in a preclinical model of liver endocrine metastases. In vitro, rapamycin inhibited the proliferation of cells in the basal state and after stimulation by insulin-like growth factor-1. Simultaneously, p70S6 kinase and 4EBP1 phosphorylation was inhibited. In vivo, rapamycin substantially inhibited the intrahepatic growth of STC-1 cells, irrespectively of the timing of its administration and even when the treatment was administered after cell intrahepatic engraftment. In addition, treated animals had significantly prolonged survival (mean survival time: 47.7 days in treated animals versus 31.8 days in controls) and better clinical status. Rapamycin treatment was associated with a significant decrease in mitotic index and in intratumoral vascular density within STC-1 tumors. Furthermore, the antitumoral effect obtained after treatment with a combination of rapamycin and phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 was more significant than with rapamycin alone in both cell lines. Our results suggest that the antitumor efficacy of rapamycin in neuroendocrine tumors results from a combination of antiproliferative and antiangiogenic effects. Interestingly, a more potent antitumor efficiency could be obtained by simultaneously targeting several levels of the PI3K/mTOR pathway.

International audience; INTRODUCTION: Lipiodol is used as a vector for chemoembolization or internal radiotherapy in unresectable hepatocellular carcinomas (HCCs). The aim of this study is to improve the tumoral uptake of Lipiodol by modulating membrane fluidizing agents to optimize the effectiveness of Lipiodol vectorized therapy. METHODS: The effect of dexamethasone and tamoxifen on membrane fluidity was studied in vitro by electron paramagnetic resonance applied to rat hepatocarcinoma cell line N1S1. The tumoral uptake of Lipiodol was studied in vivo on rats with HCC, which had been previously treated by dexamethasone and/or tamoxifen, after intra-arterial administration of (99m)Tc-SSS-Lipiodol. RESULTS: The two molecules studied here exhibit a fluidizing effect in vitro which appears dependent on time and dose, with a maximum fluidity obtained after 1 hr at concentrations of 20 μM for dexamethasone and 200 nM for tamoxifen. In vivo, while the use of dexamethasone or tamoxifen alone tends to lead to increased tumoral uptake of Lipiodol, this effect does not reach levels of significance. On the other hand, there is a significant increase in the tumoral uptake of (99m)Tc-SSS-Lipiodol in rats pretreated by both dexamethasone and tamoxifen, with a tumoral uptake (expressed in % of injected activity per g of tumor) of 13.57 ± 3.65% after treatment, as against 9.45 ± 4.44% without treatment (P

International audience; Numerous studies, focused on the hypothalamus, have recently implicated endocannabinoids (EC) as orexigenic factors in the central control of food intake. However, the EC system is also highly expressed in the hindbrain autonomic integrator of food intake regulation, i.e. the dorsal vagal complex (DVC). Previous studies have shown that exogenous cannabinoids, by acting on cannabinoid 1 receptor (CB1R), suppress GABAergic and glutamatergic neuronal transmission in adult rat dorsal motor nucleus of the vagus nerve (DMNV), the principal efferent compartment of the DVC. However, no endogenous release of EC has been demonstrated in DVC to date. Using patch-clamp techniques on mouse coronal brainstem slices, we confirmed that both inhibitory and excitatory neurotransmission were depressed by WIN 55,212-2, a CB1R agonist. We demonstrated that DMNV neurons exhibited a rapid and reversible depolarization-induced suppression of electrically evoked GABAergic IPSCs (eIPSCs), classically known as DSI (depolarization-induced suppression of inhibition), while spontaneous or miniature IPSCs activity remained unaltered. Further, no depolarization-induced suppression of glutamatergic eEPSCs (DSE) occurred. Our results indicate that DSI was blocked by SR141716A (Rimonabant), a selective CB1R antagonist, and was dependent on calcium elevation in DMNV neurons, suggesting a release of EC in the DVC. Moreover, the analysis of the paired-pulse ratio, of the coefficient of variation and of the failure rate of eIPSCs support the fact that EC-mediated suppression of GABAergic inhibition takes place at the presynaptic level. These results show for the first time that DMNV neurons release EC in an activity-dependent manner, which in turn differentially regulates their inhibitory and excitatory synaptic inputs.

International audience; Redirecting the splicing machinery through the hybridization of high affinity, RNase H- incompetent oligonucleotide analogs such as phosphoramidate morpholino oligonucleotides (PMO) might lead to important clinical applications. Chemical conjugation of PMO to arginine-rich cell penetrating peptides (CPP) such as (R-Ahx-R)(4) (with Ahx standing for 6-aminohexanoic acid) leads to sequence-specific splicing correction in the absence of endosomolytic agents in cell culture at variance with most conventional CPPs. Importantly, (R-Ahx-R)(4)-PMO conjugates are effective in mouse models of various viral infections and Duchenne muscular dystrophy. Unfortunately, active doses in some applications might be close to cytotoxic ones thus presenting challenge for systemic administration of the conjugates in those clinical settings. Structure-activity relationship studies have thus been undertaken to unravel CPP structural features important for the efficient nuclear delivery of the conjugated PMO and limiting steps in their internalization pathway. Affinity for heparin (taken as a model heparan sulfate), hydrophobicity, cellular uptake, intracellular distribution and splicing correction have been monitored. Spacing between the charges, hydrophobicity of the linker between the Arg-groups and Arg-stereochemistry influence splicing correction efficiency. A significant correlation between splicing correction efficiency, affinity for heparin and ability to destabilize model synthetic vesicles has been observed but no correlation with cellular uptake has been found. Efforts will have to focus on endosomal escape since it appears to remain the limiting factor for the delivery of these splice-redirecting ON analogs.

Human stem cells are powerful tools by which to investigate molecular mechanisms of cell growth and differentiation under normal and pathological conditions. Hedgehog signaling, the dysregulation of which causes several pathologies, such as congenital defects and cancer, is involved in several cell differentiation processes and interferes with adipocyte differentiation of rodent cells. The present study was aimed at investigating the effect of Hedgehog pathway modulation on adipocyte phenotype using different sources of human mesenchymal cells, such as bone marrow stromal cells and human multipotent adipose-derived stem cells. We bring evidence that Hedgehog signaling decreases during human adipocyte differentiation. Inhibition of this pathway is not sufficient to trigger adipogenesis, but activation of Hedgehog pathway alters adipocyte morphology as well as insulin sensitivity. Analysis of glycerol-3-phosphate dehydrogenase activity and expression of adipocyte marker genes indicate that activation of Hedgehog signaling by purmorphamine impairs adipogenesis. In sharp contrast to reports in rodent cells, the maturation process, but not the early steps of human mesenchymal stem cell differentiation, is affected by Hedgehog activation. Hedgehog interferes with adipocyte differentiation by targeting CCAAT enhancer-binding protein α and peroxisome proliferator-activated receptor (PPAR) γ2 expression, whereas PPARγ1 level remains unaffected. Although Hedgehog pathway stimulation does not modify the total number of adipocytes, adipogenesis appears dramatically impaired, with reduced lipid accumulation, a decrease in adipocyte-specific markers, and acquisition of an insulin-resistant phenotype. This study indicates that a decrease in Hedgehog signaling is necessary but not sufficient to trigger adipocyte differentiation and unveils a striking difference in the adipocyte differentiation process between rodent and human mesenchymal stem cells. Disclosure of potential conflicts of interest is found at the end of this article.

The type 1 cannabinoid receptor (CB1R) is one of the most abundant G-protein-coupled receptors (GPCRs) in the brain, predominantly localized to axons of GABAergic neurons. Like several other neuronal GPCRs, CB1R displays significantin vitroconstitutive activity (i.e., spontaneous activation in the absence of ligand). However, a clear biological role for constitutive GPCR activity is still lacking. This question was addressed by studying the consequences of constitutive activation on the intracellular trafficking of endogenous or transfected CB1Rs in cultured hippocampal neurons using optical and electron microscopy. We found that constitutive activity results in a permanent cycle of endocytosis and recycling, which is restricted to the somatodendritic compartment. Thus, CB1Rs are continuously removed by endocytosis from the plasma membrane in the somatodendritic compartment but not in axons, where CB1Rs accumulate on surface. Blocking constitutive activity by short-term incubation with inverse agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-4-morpholinyl-1H-pyrazole-3-carboxamide (AM281) results in sequestration of recycled CB1Rs on the somatodendritic plasma membrane. Long-term inhibition of endocytosis by cotransfection of dominant-negative proteins results in impaired axonal polarization of surface-bound CB1Rs. Kinetic analysis shows that the majority of newly synthesized CB1Rs arrive first to the somatodendritic plasma membrane, from where they are rapidly removed by AM281-sensitive constitutive endocytosis before being delivered to axons. Thus, constitutive-activity driven somatodendritic endocytosis is required for the proper axonal targeting of CB1R, representing a novel, conformation-dependent targeting mechanism for axonal GPCRs.

Summary: Morpholino (MO) based inhibition of translational initiation represents an attractive methodology to eliminate gene function during Xenopus development (Heasman et al., 2000). However, the degree to which a given target protein can be eliminated and the longevity of this effect during embryogenesis has not been documented. To examine the efficacy of MOs, we have used transgenic Xenopus lines that harbour known numbers of integrations of a GFP reporter under the control of the ubiquitous and highly expressed CMV promoter (Fig. 1a). In addition we have investigated the longevity of the inhibitory effect by using transgenic lines expressing GFP specifically in the lens of tadpoles. These transgenic lines represent the ideal control for the technique as the promoters are highly expressed and GFP can be easily detected by fluorescence and immunoblotting. Moreover, as GFP has no function in development, the levels of inhibition can be tested in an otherwise normal individual. Here we report that MOs are able to efficiently and specifically inhibit the translation of GFP in transgenic lines from Xenopus laevis and Xenopus tropicalis and the inhibitory effect is long-lived, lasting into the tadpole stages. genesis 30:110–113, 2001. © 2001 Wiley-Liss, Inc.

International audience; 1. CB-1 cannabinoid receptors are strongly expressed in the molecular layer of the cerebellar cortex. We have analysed, in patch-clamped Purkinje cells (PCs) in rat cerebellar slices, the effect of the selective CB-1 agonists WIN55,212-2 and CP55,940 and of the selective CB-1 antagonist SR141716-A on excitatory synaptic transmission and synaptic plasticity. 2. Bath application of both agonists markedly depressed parallel fibre (PF) EPSCs. This effect was reversed by SR141716-A. In contrast, responses of PCs to ionophoretic application of glutamate were not affected by WIN55, 212-2. 3. The coefficient of variation and the paired-pulse facilitation of these PF-mediated EPSCs increased in the presence of WIN55,212-2. 4. WIN55,212-2 decreased the frequency of miniature EPSCs and of asynchronous synaptic events evoked in the presence of strontium in the bath, but did not affect their amplitude. 5. WIN55, 212-2 did not change the excitability of PFs. 6. WIN55,212-2 impaired long-term depression induced by pairing protocols in PCs. This effect was antagonized by SR141716-A. The same impairment of LTD was produced by 2-chloroadenosine, a compound that decreases the probability of release of glutamate at PF-PC synapses. 7. The present study demonstrates that cannabinoids inhibit synaptic transmission at PF-PC synapses by decreasing the probability of release of glutamate, and thereby impair LTD. These two effects might represent a plausible cellular mechanism underlying cerebellar dysfunction caused by cannabinoids.

International audience; We have shown previously that ADP released upon platelet adhesion mediated by IIb 3 integrin triggers accumulation of phosphatidylinositol 3,4-bisphosphate (PtdIns-3,4-P 2) (Gironcel, D., Racaud-Sultan, C., Payras-tre, B., Haricot, M., Borchert, G., Kieffer, N., Breton, M., and Chap, H. (1996) FEBS Lett. 389, 253–256). ADP has also been involved in platelet spreading. Therefore, in order to study a possible role of phosphoinositide 3-ki-nase in platelet morphological changes following adhesion , human platelets were pretreated with specific phosphoinositide 3-kinase inhibitors LY294002 and wortmannin. Under conditions where PtdIns-3,4-P 2 synthesis was totally inhibited (25 M LY294002 or 100 nM wortmannin), platelets adhered to the fibrinogen matrix , extended pseudopodia, but did not spread. Moreover , addition of ADP to the medium did not reverse the inhibitory effects of phosphoinositide 3-kinase inhibi-tors on platelet spreading. Although synthetic dipalmi-toyl PtdIns-3,4-P 2 and dipalmitoyl phosphatidylinositol 3,4,5-trisphosphate restored only partially platelet spreading, phosphatidylinositol 4,5-bisphosphate (Pt-dIns-4,5-P 2) was able to trigger full spreading of wort-mannin-treated adherent platelets. Following 32 P labeling of intact platelets, the recovery of [ 32 P]PtdIns-4,5-P 2 in anti-talin immunoprecipitates from adherent plate-lets was found to be decreased upon treatment by wort-mannin. These results suggest that the lipid products of phosphoinositide 3-kinase are required but not sufficient for ADP-induced spreading of adherent platelets and that PtdIns-4,5-P 2 could be a downstream messenger of this signaling pathway.

We compared the anti-proliferative properties of 4-benzylphenoxy-N ethyl morpholine (morpho-BPE) and trifluopromazine (TFP) on both the human breast cancer cell lines, MCF7, and its tamoxifen-resistant variant RTx6. We found that the calmodulin antagonist trifluopromazine (TFP) which bound ABS weakly, inhibited MCF7 cell growth but did not follow the relationship observed for diphenylmethane derivatives between MCF7-inhibitory potencies and their Ki. Regarding the tamoxifen-resistant RTx6 cells, TFP but not morpho-BPE induced inhibition of the proliferation. Using a tritiated derivative of morpho-BPE, two distinct binding sites could be demonstrated. Indeed, a low affinity binding site was present in both cell lines whereas a high affinity binding site was mainly found in MCF7 cells although being in lower concentration (less than 10%) in RTx6 cells. Both tamoxifen and TFP displaced morpho-BPE from the two binding sites. The uptake and efflux of the tritiated drug were similar in the two cell lines. The drug did not appear to be metabolized. We concluded that TFP and morpho-BPE belong to distinct classes of molecules and that ABS mediates the anti-proliferative action of diphenylmethane derivatives but not the inhibitory effect of the calmodulin antagonist TFP.