Rôle et place du riz pluvial dans les exploitations du Vakinankaratra (Hauts Plateaux et Moyen Ouest)

International audienceDans la région des Hautes Terres, zone montagneuse dont les plaines et les bas fond irrigués sont dominés par de forts reliefs, l'accroissement de la pression démographique s'est traduit par la saturation des terres irriguées, destinées à la riziculture, et par une emprise agricole de plus en plus forte sur les terres de versant. La conduite des cultures de versant (Tanety), ou cultures pluviales, selon les techniques traditionnelles de travail du sol, combiné à l'abondance des pluies, accentue les phénomènes d'érosion et conduit donc à une forte perte de fertilité. De plus, la dégradation des sols en amont se traduit très souvent par l'ensablement et des dégâts sur les infrastructures et parcelles irriguées situées en aval. Ainsi, ces systèmes ne permettent pas, du fait de la fragilité de l'écosystème, de concilier les objectifs de production et de durabilité. Pour faire évoluer ces systèmes vers plus de durabilité, il convient d'améliorer les connaissances sur les pratiques des exploitants. Cette communication présente les résultats de deux diagnostics agraires réalisé en 2007 dans la commune d'Andranomanelatra, à la périphérie d'Antsirabe, sur les hauts plateaux de Madagascar et en 2008/2009 dans le reste du Vakinankaratra, hauts plateaux et moyen-ouest, ainsi que des résultats obtenus et sortis de la base de données parcelle (BDD) du projet BVPI SE/HP. Des typologies d'exploitations sont présentées pour mieux identifier les contraintes et opportunités de chaque type et la place du riz pluvial dans la formation du revenu ou la satisfaction des besoins alimentaires. On examinera l'opportunité que représente le riz pluvial pour les agriculteurs de la région sans oublier les autres opportunités ou alternatives présentes dans la zone qui semblent plus adaptées à des contextes très différenciés des hauts plateaux. La discussion portera sur les enjeux agricoles à venir et la place que peut y jouer le riz pluvial

Expression of Protease-Activated Receptor 1 and 2 and Anti-Tubulogenic Activity of Protease-Activated Receptor 1 in Human Endothelial Colony-Forming Cells

Endothelial colony-forming cells (ECFCs) are obtained from the culture of human peripheral blood mononuclear cell (hPBMNC) fractions and are characterised by high proliferative and pro-vasculogenic potential, which makes them of great interest for cell therapy. Here, we describe the detection of protease-activated receptor (PAR) 1 and 2 amongst the surface proteins expressed in ECFCs. Both receptors are functionally coupled to extracellular signal-regulated kinase (ERK) 1 and 2, which become activated and phosphorylated in response to selective PAR1- or PAR2-activating peptides. Specific stimulation of PAR1, but not PAR2, significantly inhibits capillary-like tube formation by ECFCs in vitro, suggesting that tubulogenesis is negatively regulated by proteases able to stimulate PAR1 (e.g. thrombin). The activation of ERKs is not involved in the regulation of tubulogenesis in vitro, as suggested by use of the MEK inhibitor PD98059 and by the fact that PAR2 stimulation activates ERKs without affecting capillary tube formation. Both qPCR and immunoblotting showed a significant downregulation of vascular endothelial growth factor 2 (VEGFR2) in response to PAR1 stimulation. Moreover, the addition of VEGF (50–100 ng/ml) but not basic Fibroblast Growth Factor (FGF) (25–100 ng/ml) rescued tube formation by ECFCs treated with PAR1-activating peptide. Therefore, we propose that reduction of VEGF responsiveness resulting from down-regulation of VEGFR2 is underlying the anti-tubulogenic effect of PAR1 activation. Although the role of PAR2 remains elusive, this study sheds new light on the regulation of the vasculogenic activity of ECFCs and suggests a potential link between adult vasculogenesis and the coagulation cascade

Severe Dengue Is Associated with Consumption of von Willebrand Factor and Its Cleaving Enzyme ADAMTS-13

Severe dengue infections are characterized by thrombocytopenia, clinical bleeding and plasma leakage. Activation of the endothelium, the inner lining of blood vessels, leads to the secretion of storage granules called Weibel Palade bodies (WPBs). We demonstrated that severe dengue in Indonesian children is associated with a strong increase in plasma levels of the WPB constituents von Willebrand factor (VWF), VWF propeptide and osteoprotegerin (OPG). An increased amount of the hemostatic protein VWF was in a hyperreactive, platelet binding conformation, and this was most pronounced in the children who died. VWF levels at enrollment were lower than expected from concurrent VWF propeptide and OPG levels and VWF levels did not correlate well with markers of disease severity. Together, this suggests that VWF is being consumed during severe dengue. Circulating levels of the VWF-cleaving enzyme ADAMTS-13 were reduced. VWF is a multimeric protein and a subset of children had a decrease in large and intermediate VWF multimers at discharge. In conclusion, severe dengue is associated with exocytosis of WPBs with consumption of VWF and low ADAMTS-13 activity levels. This may contribute to the thrombocytopenia and complications of dengue

A qualitative study exploring perceptions and attitudes of community pharmacists about extended pharmacy services in Lahore, Pakistan

Background In recent decades, community pharmacies reported a change of business model, whereby a shift from traditional services to the provision of extended roles was observed. However, such delivery of extended pharmacy services (EPS) is reported from the developed world, and there is scarcity of information from the developing nations. Within this context, the present study was aimed to explore knowledge, perception and attitude of community pharmacists (CPs) about EPS and their readiness and acceptance for practice change in the city of Lahore, Pakistan. Methods A qualitative approach was used to gain an in-depth knowledge of the issues. By using a semi-structured interview guide, 12 CPs practicing in the city of Lahore, Pakistan were conveniently selected. All interviews were audio-taped, transcribed verbatim, and were then analyzed for thematic contents by the standard content analysis framework. Results Thematic content analysis yielded five major themes. (1) Familiarity with EPS, (2) current practice of EPS, (3) training needed to provide EPS, (4) acceptance of EPS and (5) barriers toward EPS. Majority of the CPs were unaware of EPS and only a handful had the concept of extended services. Although majority of our study respondents were unaware of pharmaceutical care, they were ready to accept practice change if provided with the required skills and training. Lack of personal knowledge, poor public awareness, inadequate physician-pharmacist collaboration and deprived salary structures were reported as barriers towards the provision of EPS at the practice settings. Conclusion Although the study reported poor awareness towards EPS, the findings indicated a number of key themes that can be used in establishing the concept of EPS in Pakistan. Over all, CPs reported a positive attitude toward practice change provided to the support and facilitation of health and community based agencies in Pakistan

Osteoprotegerin induces CD34 + differentiation in Endothelial Progenitor Cells

International audienceEndothelial progenitor cells (EPCs) are the main hypothetical cells that could give rise to vessels and in particular one subtype isolated from peripheral or cord bloods: endothelial colony forming cells (ECFCs). These ECFCs are clonogenic precursors committed to endothelial lineage and have robust vasculogenic properties. However, their low number and poor expansion properties when isolated from human adult bloods, currently limit their use as an autologous cell therapy product. We previously reported that osteoprotegerin (OPG), a well-characterized regulator of bone metabolism, contributes to ischemic tissue revascularization, tumor growth in vivo, and potentiates ECFCs proangiogenic properties through the secretion of SDF-1. The current study investigated the role of OPG in ECFCs differentiation and expansion from cord blood CD34+ cells. OPG increased the number of ECFCs after endothelial differentiation of CD34+ cells, enhancing the time of EPCs colonies initial appearance and the growth kinetic of endothelial cell progeny. OPG-exposed ECFCs expressed higher levels of CD34+ compared to control ECFCs. In conclusion, our findings provide novel insights into OPG in regulation of CD34+ progenitor cells. These results give new opportunities for ex vivo expansion of human ECFCs using OPG as a cell culture component for future ECFC product manufacture according to GMP

Mechanistic study of the proangiogenic effect of osteoprotegerin

Osteoprotegerin (OPG), a soluble tumour necrosis factor receptor superfamily member, inhibits RANKL-mediated osteoclastogenesis. We have previously reported that OPG enhances the proangiogenic properties of endothelial colony-forming cells (ECFCs) in vitro, and promotes vasculogenesis in vivo. Here we investigated how OPG promotes neovascularisation. Proteomic experiments showed that OPG pretreatment affected ECFCs protein expression in two ways, 23 spots being down-regulated and 6 upregulated. These spots corresponded to proteins involved in cell motility, adhesion, signal transduction and apoptosis. In keeping with these proteomic results, we found that OPG induced ECFCs adhesion to activated endothelium in shear stress conditions, promoting intermediate but not focal adhesion to fibronectin and collagen. Treatment with OPG induced a reorganization of the ECFCs cytoskeleton, with the emergence of cell protrusions characteristic of a migratory phenotype. These effects correlated with decreased FAK phosphorylation and enhanced integrin αVβ3 expression. OPG drastically reduced caspase-3/7 activities and maintained ECFCs viability after 48 h of treatment. All these effects were significantly attenuated by ECFCs incubation with the CXCR4 antagonist AMD-3100, and by prior heparan sulphate proteoglycan disruption. The proangiogenic properties of OPG appeared to be mediated by the proteoglycan syndecan-1, although OPG 1-194 lacking its heparin-binding domain still had pro-vasculogenic effects in vitro and in vivo. These results suggest that OPG may interact with ECFCs by binding to HSPGs/syndecan-1, thereby induce an anti-adhesive effect and promoting ECFCs migration through a SDF-1/CXCR4 dependent pathway