HPLC analysis of azadirachtin and formulation of neem seed extracts.

Une méthode de dosage de l'azadirachtine a été développée. Après élimination de l'huile par l'hexane, l'azadirachtine est extraite des amandes broyées à l'aide de méthanol. Les extraits sont purifiés d'abord par partage liquide/liquide, ensuite par chromatographie sur colonne de Florisil. L'analyse HPLC est réalisée notamnent sur colonne CI8 ODS. Le taux moyen de récupération est de 97%. Des extraits des amandes du neem (Azadirachta indica) ont été formulés en solution émulsionnable EC

Toxic effects of neem products (Azadirachta indica A. Juss) on Aedes aegypti Linnaeus 1762 larvae

Treatment and comparative analysis of the properties of aqueous extracts of seed kernel of Azadirachta indica A. Juss (neem) was carried out on Aedes aegypti larvae. The aim of this work was to evaluate lethal effects of neem products (1% Suneem, formulated neem oil and neem powder) on A. aegypti larvae. Assays showed that A. indica was toxic to larvae of A. aegypti. For 1% Suneem, 1% formulatedneem oil and neem powder, the lethal concentrations and lethal time at 50% (LC50 and LT50) for A. aegypti were 2 and 8 mg/l after 24 h and 3 mg/l after 120 h, respectively. Assays showed that Suneemand Formulated neem oil were more toxic to A. aegypti than Neem powder. Both products of the neem (A. indica, A. juss) have a remarkable influence on the development of A. aegypti larvae, causing an inhibition of nymphs and adults emergency. The Histopathological results revealed a serious damage on the epithelial columnar cells, a perturbation of alimentary flow, slightly hypertrophied cells, abeginning of vacuolisation on apical level, and a bursting of some cells in posterior part of the gut. However, nuclei, adipose tissue and muscles seem to keep normal appearance

Historical and simulated ecosystem carbon dynamics in Ghana: land use, management, and climate

International audienceWe used the General Ensemble biogeochemical Modeling System (GEMS) to simulate responses of natural and managed ecosystems to changes in land use, management, and climate for a forest/savanna transitional zone in central Ghana. Model results show that deforestation for crop production during the last century resulted in a substantial reduction in ecosystem carbon (C) stock from 135.4 Mg C ha?1 in 1900 to 77.0 Mg C ha?1 in 2000, and in soil organic C stock within the top 20 cm of soil from 26.6 Mg C ha?1 to 21.2 Mg C ha?1. If no land use change takes place from 2000 through 2100, low and high climate change scenarios (increase in temperature and decrease in precipitation over time) will result in losses of soil organic C stock by 19% and 25%, respectively. A low nitrogen (N) fertilization rate is the principal constraint on current crop production. An increase in N fertilization under the low climate change scenario would increase crop yield by 14% with 30 kg N ha?1 and by 38% with 60 kg N ha?1, leading to an increase in the average soil C stock by 12% and 29%, respectively, in all cropland by 2100. The results suggest that the climate changes in the future from current climate conditions will not necessarily become a determinant control on ecosystem C fluxes and crop production, while a reasonable N fertilization rate is critical to achieve food security and agricultural sustainability in the study area through the 21st century, and current cropping systems could be optimized to make full use of the rainfall resource

Efficacite agronomique du compost a base de la biomasse du « neem » et de l’anacarde sur des cultures maraicheres dans la zone des Niayes au Senegal

Dans la zone des Niayes au Sénégal, les sols sont pauvres en matières organiques et en éléments nutritifs nécessaires aux plantes. Les engrais chimiques utilisés pour améliorer les rendements ont engendré une forte pollution des sols et de la  nappe phréatique. L’objectif de cette étude est d’évaluer la valeur agronomique du compost fabriqué à base des feuilles de neem et d’anacarde, de fiente de volaille et de la cendre de bois. Le compost obtenu présente un rapport C/N de 15,49 et des teneurs en N - P - K de 9,1, 14,8 et 7,3 mg/kg, respectivement. Les différentes doses du compost testées  sur  des  cultures  maraichères  ont  révélé  des  performances  agronomiques  meilleures par rapport aux témoins. La dose T3 (30 t/ha) a induit les meilleurs rendements pour la tomate (27,213 t/ha) et l’oignon (105,263 t/ha). Pour le chou et la pomme de terre, la dose T1 (10 t/ha) a permis d’obtenir les meilleurs rendements (144,533 t/ha et 55,163 t/ha, respectivement). Par contre pour le poivron, la dose T2 (20 t/ha) a favorisé les meilleurs rendements (32,534 t/ha) avec un poids moyen (81,748g) et un nombre de fruits/récolte considérablement plus élevé. Ce compost pourrait constituer une alternative réelle à l’utilisation abusive de l’engrais minéral dans la zone agricole des Niayes.Mots clés : Compost, Neem, Feuilles d’anacarde, Maraichage, Sénéga

Do drugs interact together in cardiovascular prevention? A meta-analysis of powerful or factorial randomized controlled trials.

To explore whether preventive cardiovascular drugs (antihypertensive, antiplatelet, lipid lowering and hypoglycemic agents) interact together in cardiovascular prevention. We searched PubMed®, Web of science™, Embase and Cochrane library for powerful randomized placebo-controlled trials (>1000 patients). We explored whether drug effect on major vascular events changed according to cross-exposure to other drug classes or to cardiovascular risk factors (hypertension or type 2 diabetes), through a meta-analysis of relative odds ratio computed by trial subgroups. A significant interaction was suggested from confidence intervals of the ratio of odds ratios, when they excluded neutral value of 1. In total, 14 trials with 178,398 patients were included. No significant interaction was observed between co-prescribed drugs or between these medications and type 2 diabetes/hypertension status. Our meta-analysis is the first one to evaluate drug-drug and drug-hypertension/type 2 diabetes status interactions in terms of cardiovascular risks: we did not observe any significant interaction. This indirectly reinforces the rationale of using several contrasted mechanisms to address cardiovascular prevention; and allows the combination effect prediction by a simple multiplication of their odds ratios. The limited availability of data reported or obtained from authors is a strong argument in favor of data sharing

Energetic crisis and space reconstruction in Senegal: traditional crops vs biofuels?

La crise énergétique mondiale est fortement ressentie par les pays pauvres importateurs de pétrole. Les stratégies élaborées par les gouvernements de ces États sont certes diversifiées, mais les résultats semblent encore peu efficaces. Parmi ces stratégies, un important programme de biocarburant est mis en oeuvre au Sénégal, à travers un dispositif de culture de pourghère ( Jatropha curcas L). Ce programme du Gouvernement du Sénégal constitue une nouvelle politique énergétique conçue pour atténuer la dépendance vis-à-vis de l’extérieur. Le programme est bâti sur une base de production utilisant les réserves foncières dans les différentes Communautés rurales du Sénégal. Une projection de 1000 hectares de Jatropha par Communauté rurale est envisagée. Cette disposition a plusieurs implications, dont l’utilisation de la terre, source de revenus, mais aussi de conflits sociaux. Dans cette posture, les incertitudes concernant l’alimentation sont-elles écartées ? L’analyse diachronique de l’occupation des sols et des superficies utilisées pour la culture du Jatropha montre que le mode d’utilisation de la terre peut être facteur de risque pour la sécurité alimentaire. En effet, les systèmes de culture de Jatropha Curcas reposent sur une association des cultures avec les céréales, les légumineuses, les cultures oléagineuses ; ou sur une culture en plein champs (souvent prise en charge par des opérateurs privés ayant obtenu des collectivités locales le droit d’usage par voie de délibération du Conseil rural). Les modalités de contractualisation constituent des facteurs déterminants dans l’utilisation des espaces cultivés et l’allocation de superficies pour la culture bioénergétique. Cependant, l’implication des acteurs (les producteurs, particulièrement) dans une stratégie d’extension/substitution des superficies destinées aux cultures traditionnelles vivrières et de rente aux cultures énergétiques dépendra des débouchés offerts par les biocarburants mais également des performances économiques de cette filière

Sensitivity Analysis of the GEMS Soil Organic Carbon Model to Land Cover Land Use Classification Uncertainties Under Different Climate Scenarios in Senegal

Spatially explicit land cover land use (LCLU) change information is needed to drive biogeochemical models that simulate soil organic carbon (SOC) dynamics. Such information is increasingly being mapped using remotely sensed satellite data with classification schemes and uncertainties constrained by the sensing system, classification algorithms and land cover schemes. In this study, automated LCLU classification of multi-temporal Landsat satellite data were used to assess the sensitivity of SOC modeled by the Global Ensemble Biogeochemical Modeling System (GEMS). The GEMS was run for an area of 1560km2 in Senegal under three climate change scenarios with LCLU maps generated using different Landsat classification approaches. This research provides a method to estimate the variability of SOC, specifically the SOC uncertainty due to satellite classification errors, which we show is dependent not only on the LCLU classification errors but also on where the LCLU classes occur relative to the other GEMS model inputs

Evaluation of the Prognostic Value of IFN-γ Release Assay and Tuberculin Skin Test in Household Contacts of Infectious Tuberculosis Cases in Senegal

BACKGROUND: Chemoprophylaxis of contacts of infectious tuberculosis (TB) cases is recommended for TB control, particularly in endemic countries, but is hampered by the difficulty to diagnose latent TB infection (LTBI), classically assessed through response to the Tuberculin Skin Test (TST). Interferon-gamma release assays (IGRA) are proposed new tools to diagnose LTBI, but there are limited data on their ability to predict the development of active TB disease. To address this, we investigated the response to TST and IGRA in household contacts of infectious TB cases in a TB high-burden country and the potential correlation with development of TB. METHODOLOGY/PRINCIPAL FINDINGS: Prospective household contacts study conducted in two health centres in Dakar, Senegal. A total of 2679 household contacts of 206 newly detected smear and/or culture positive index TB cases aged 18 years or greater were identified A TST was performed in each contact and an ESAT6/CFP10 ELISPOT assay performed in a random sample of those. Contacts were followed-up for 24 months. TB was diagnosed in 52 contacts, an incidence rate of 9.27/1000 person-years. In univariable analysis, the presence of positive TST (> or = 10 mm) and ELISPOT (>32 SFC/million PBMC) responses at baseline were associated with active TB during follow-up: Rate Ratio [RR] = 2.32 (95%CI:1.12-4.84) and RR = 2.09 (95%CI:0.83-5.31), respectively. After adjustment for age, sex and proximity to index case, adjusted RRs were 1.51 (95%CI:0.71-3.19) and 1.98 (95%CI:0.77-5.09), respectively. Restricting analysis to the 40 microbiologically confirmed cases, the adjusted RR for positive ELISPOT was 3.61 (95%CI:1.03-12.65). The median ELISPOT response in contacts who developed TB was 5-fold greater than in those who did not develop TB (p = 0.02). CONCLUSIONS/SIGNIFICANCE: TST and IGRAs are markers of a contact of the immune system with tubercle bacilli. In a TB endemic area, a high ELISPOT response may reflect increased bacterial replication that may subsequently be associated with development of TB disease and may have a prognostic value. Further longitudinal data are needed to assess whether IGRAs are reliable markers to be used for targeting chemoprophylaxis

Strengthening human genetics research in Africa: report of the 9th meeting of the African Society of Human Genetics in Dakar in May 2016.

The 9th meeting of the African Society of Human Genetics, in partnership with the Senegalese Cancer Research and Study Group and the Human Heredity and Health in Africa (H3Africa) Consortium, was held in Dakar, Senegal. The theme was Strengthening Human Genetics Research in Africa. The 210 delegates came from 21 African countries and from France, Switzerland, UK, UAE, Canada and the USA. The goal was to highlight genetic and genomic science across the African continent with the ultimate goal of improving the health of Africans and those across the globe, and to promote the careers of young African scientists in the field. A session on the sustainability of genomic research in Africa brought to light innovative and practical approaches to supporting research in resource-limited settings and the importance of promoting genetics in academic, research funding, governmental and private sectors. This meeting led to the formation of the Senegalese Society for Human Genetics