Mechanisms behind the polarized distribution of lipids in epithelial cells

Epithelial cells are polarized cells and typically display distinct plasma membrane domains: basal plasma membrane domains face the underlying tissue, lateral domains contact adjacent cells and apical domains face the exterior lumen. Each membrane domain is endowed with a specific macromolecular composition that constitutes the functional identity of that domain. Defects in apical-basal plasma membrane polarity altogether or more subtle defects in the composition of either apical or basal plasma membrane domain can give rise to severe diseases. Lipids are the main component of cellular membranes and mechanisms that control their polarized distribution in epithelial cells are emerging. In particular sphingolipids and phosphatidylinositol lipids have taken center stage in the organization of the apical and basolateral plasma membrane domain. This short review article discusses mechanisms that contribute to the polarized distribution of lipids in epithelial cells

Why NERICA is a successful innovation for African farmers

This paper responds to ‘Funding international agricultural research and the need to be noticed: a case study of NERICA rice’ by Stuart Orr, James Sumberg, Olaf Erenstein and Andreas Oswald, published in this issue of Outlook on Agriculture. In summary, the article by Orr et al, based on an internal WARDA document written in November 2003 and augmented with results from Internet searches, is outdated and does not seem to be fair, objective or useful. We invite the authors to visit WARDA or any of its partners in Sub-Saharan Africa for evidence of the impact of NERICA varieties or the other improved varieties and technologies that have been developed and disseminated by WARDA in recent years

Electrochemical properties and electrochemical impedance spectroscopy of polypyrrole-coated platinum electrodes

Polypyrrole (PPy) films of different thickness were characterized by electrochemical impedance spectroscopy (EIS) measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8 V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the dopant). They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis (i.e. film thickness) for ClO4--doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO4--doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (Rct) obtained with SDS is nearly 200-fold higher than that obtained with ClO4- in the same solvent (H2O). With the same dopant (ClO4-), Rct is about five times higher in acetonitrile relative to water. All these EIS results of the different types of PPy suggest a relation with the wettability of the polymer.KEY WORDS: Conducting polymers, Polypyrrole, Electrochemical impedance spectroscopy, Equivalent-electrical circuit, Micellar mediaBull. Chem. Soc. Ethiop. 2006, 20(2), 279-293

Cancer du testicule: particularités cliniques et limites thérapeutiques en milieu hospitalier urologique au Sénégal

RésuméButEtudier les particularités cliniques et les limites thérapeutiques de la prise en charge du cancer du testicule au Sénégal.Patients et méthodesCette étude, rétrospective, était menée sur une période de 15 ans de Janvier 1997 à Janvier 2012. Vingt-deux dossiers étaient colligés mais 17 étaient exploitables.Résultatsl’incidence annuelle moyenne était de 1,13 cas par an. L’âge moyen des patients était de 27 ans ± 9,5. La tranche d’âge la plus concernée était celle de 21 à 40 ans. Les circonstances de découverte étaient dominées par la grosse bourse (10 cas) et en cas de vacuité scrotale, la masse abdominale ou pelvienne (7 cas). L’orchidectomie a été le principal geste thérapeutique. Elle a été réalisée par voie inguinale haute (8 patients) et par voie trans-péritonéale (7 patients). Sur le plan histologique, nous avions noté une prédominance des tumeurs germinales non séminomateuses avec 10 cas de carcinome embryonnaire dont un cas de type infantile. En post opératoire, 7 cas de progression avaient été notés dans le suivi: 3 cas de carcinose péritonéale, 3 cas d’envahissement locorégionale avec des adénopathies rétropéritonéale et 1 cas de métastase pulmonaire. Avec un recul moyen de 6 mois, 9 patients étaient décédés, 4 étaient perdus de vue et les 4 autres étaient vivants.ConclusionLe cancer du testicule reste rare au Sénégal et concerne des sujets jeunes. Le diagnostic est encore posé à des stades très évolués avec une lourde mortalité.AbstractObjectiveTo investigate the clinical features and limitations of therapeutic management of testicular cancer in Senegal.Patients and methodsThis is a retrospective study over 15 years period between January 1997 and January 2012. Twenty-two cases were collected but only 17 had complete data for analysis.ResultsThe average annual incidence was 1.13 cases per year, with a mean age of 27±9.5 years. The most affected age group was between 21 and 40 years.Clinical diagnosis was suspected by the presence of a scrotal swelling in10 cases and by empty scrotum associated with abdominal or pelvic mass in the remaining 7 cases. Orchiectomy was the main treatment option, done either by high inguinal approach in 8 patients or by trans- peritoneal route in other 7 patients. Histologically, a predominance of embryonic non seminomatous germ cell carcinoma was noted in 10 cases including infantile type in one case. Seven cases developed disease progression:3 cases of peritoneal carcinmatosis, 3 other cases of locoregional invasion with retroperitoneal lymphadenopathy and one case of pulmonary metastasis. At a mean follow up of six months, nine patients died, four were lost to follow up while the remaining four cases were still alive.ConclusionTesticular cancer is a rare tumor in Senegal and usually involves young people. Clinical diagnosis is always done at very advanced stage with a very high mortality rate

Efficacy of silica nanoparticles on groundnut bruchid, Caryedon serratus (Olivier) (Coleoptera, Bruchidae)

In Senegal, post-harvest losses caused by groundnut bruchid, Caryedon serratus, are detrimental to farmers and affect national economy. The objectivie of this study was to investigate the effectiveness of silica nanoparticles against C. serratus. Silica nanoparticles were synthesized by reverse microemulsion and different concentrations (0.17, 0.33, 0.67 and 1.7 mg kg-1) were tested on mortality and fecundity of C. serratus. Result showed that silica nanoparticles had high toxicity on C. serratus adults. Adults\u2019 mortality increased with concentrations and time of exposure to each concentration. Up to 100% mortality was observed with high concentrations (0.67 and 1.7 mg kg-1) after 6 and 7 days post exposure, respectively. Additionally, fecundity potential of C. serratus was significantly (P<0.05) reduced by silica nanoparticles. Results of this study clearly demonstrated that silica nanoparticles can be used as a valuable tool for the control of C. serratus in stored groundnut ( Arachis hypogaea L.) .Au S\ue9n\ue9gal, les pertes post-r\ue9colte caus\ue9es par la bruche de l\u2019arachide, Caryedon serratus , sont pr\ue9judiciables aux agriculteurs et affectent l\u2019\ue9conomie nationale. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9tudier l\u2019efficacit\ue9 des nanoparticules de silice contre C. serratus. Des nanoparticules de silice ont \ue9t\ue9 synth\ue9tis\ue9es par micro\ue9mulsion inverse et diff\ue9rentes concentrations (0,17\ua0; 0,33\ua0; 0,67 et 1,7 mg kg-1) ont \ue9t\ue9 test\ue9es sur la mortalit\ue9 et la f\ue9condit\ue9 de C. serratus. Les r\ue9sultats ont montr\ue9 que les nanoparticules de silice pr\ue9sentaient une toxicit\ue9 \ue9lev\ue9e chez les adultes de C. serratus. La mortalit\ue9 des adultes augmentait avec les concentrations et le temps d\u2019exposition \ue0 chaque concentration. Une mortalit\ue9 allant jusqu\u2019 \ue0 100% a \ue9t\ue9 observ\ue9e avec les plus grandes concentrations (0,67 et 1,7 mg kg-1) respectivement apr\ue8s 6 et 7 jours d\u2019exposition. De plus, le potentiel de f\ue9condit\ue9 de C. serratus \ue9tait significativement (P <0,05) r\ue9duit par les nanoparticules de silice. Les r\ue9sultats de cette \ue9tude ont clairement d\ue9montr\ue9 que les nanoparticules de silice peuvent \ueatre utilis\ue9es comme un outil pr\ue9cieux pour lutter contre C. serratus dans les arachides stock\ue9es ( Arachis hypogaea L.)

A Study of Machine Learning Techniques for Daily Solar Energy Forecasting using Numerical Weather Models

Proceedings of: 8th International Symposium on Intelligent Distributed Computing (IDC'2014). Madrid, September 3-5, 2014Forecasting solar energy is becoming an important issue in the context of renewable energy sources and Machine Learning Algorithms play an important rule in this field. The prediction of solar energy can be addressed as a time series prediction problem using historical data. Also, solar energy forecasting can be derived from numerical weather prediction models (NWP). Our interest is focused on the latter approach.We focus on the problem of predicting solar energy from NWP computed from GEFS, the Global Ensemble Forecast System, which predicts meteorological variables for points in a grid. In this context, it can be useful to know how prediction accuracy improves depending on the number of grid nodes used as input for the machine learning techniques. However, using the variables from a large number of grid nodes can result in many attributes which might degrade the generalization performance of the learning algorithms. In this paper both issues are studied using data supplied by Kaggle for the State of Oklahoma comparing Support Vector Machines and Gradient Boosted Regression. Also, three different feature selection methods have been tested: Linear Correlation, the ReliefF algorithm and, a new method based on local information analysis.Publicad

Larval ecology of mosquitoes in sylvatic arbovirus foci in southeastern Senegal

BACKGROUND: Although adult mosquito vectors of sylvatic arbovirus [yellow fever (YFV), dengue-2 (DENV-2) and chikungunya (CHIKV)] have been studied for the past 40 years in southeastern Senegal, data are still lacking on the ecology of larval mosquitoes in this area. In this study, we investigated the larval habitats of mosquitoes and characterized their seasonal and spatial dynamics in arbovirus foci. METHODS: We searched for wet microhabitats, classified in 9 categories, in five land cover classes (agriculture, forest, savannah, barren and village) from June, 2010 to January, 2011. Mosquito immatures were sampled monthly in up to 30 microhabitats of each category per land cover and bred until adult stage for determination. RESULTS: No wet microhabitats were found in the agricultural sites; in the remaining land covers immature stages of 35 mosquito species in 7 genera were sampled from 9 microhabitats (tree holes, fresh fruit husks, decaying fruit husks, puddles, bamboo holes, discarded containers, tires, rock holes and storage containers). The most abundant species was Aedes aegypti formosus, representing 30.2% of the collections, followed by 12 species, representing each more than 1% of the total, among them the arbovirus vectors Ae. vittatus (7.9%), Ae. luteocephalus (5.7%), Ae. taylori (5.0%), and Ae. furcifer (1.3%). Aedes aegypti, Cx. nebulosus, Cx. perfuscus, Cx. tritaeniorhynchus, Er. chrysogster and Ae. vittatus were the only common species collected from all land covers. Aedes furcifer and Ae. taylori were collected in fresh fruit husks and tree holes. Species richness and dominance varied significantly in land covers and microhabitats. Positive associations were found mainly between Ae. furcifer, Ae. taylori and Ae. luteocephalus. A high proportion of potential enzootic vectors that are not anthropophilic were found in the larval mosquito fauna. CONCLUSIONS: In southeastern Senegal, Ae. furcifer and Ae. taylori larvae showed a more limited distribution among both land cover and microhabitat types than the other common species. Uniquely among vector species, Ae. aegypti formosus larvae occurred at the highest frequency in villages. Finally, a high proportion of the potential non-anthropophilic vectors were represented in the larval mosquito fauna, suggesting the existence of unidentified sylvatic arbovirus cycles in southeastern Senegal

Exploring the main threats to the threatened African spurred tortoise Centrochelys sulcata in the West African Sahel

AbstractThe African spurred tortoiseCentrochelys sulcatais the second largest terrestrial turtle, with a scattered distribution across the West African Sahel. This species is threatened and declining consistently throughout its range, but little is known about the causes of its decline. It has been hypothesized that the decline is attributable to (1) competition with domestic cattle, (2) wildfire, and (3) the international pet trade. We conducted a series of analyses to investigate these three causes. Hypotheses 1 and 2 were analysed using a spatially explicit approach, using a database of the Food and Agriculture Organization of the United Nations and logistic regression modelling; hypothesis 3 was tested by analysing the CITES trade database for 1990–2010. We found a significant negative correlation between intensity of grazing (expressed as density of cattle, km−2) and the presence of spurred tortoises, and this negative effect increased when coupled with high fire intensity, whereas wildfires alone did not have a significant influence on the species' distribution at the global scale. There was a decrease in the annual export of wild individuals for the pet trade after the introduction of export quotas by country and by year, but trade data must be considered with caution