Analyse physico-chimique de l’eau de l’unité d’hémodialyse du chr de Saint- Louis (Sénégal)

L’insuffisance rénale chronique est un des problèmes majeurs de la santé publique dans le monde. Au Sénégal, une étude récente réalisée dans la population générale adulte avait retrouvé une prévalence de l’ordre de 6,1%. «L’eau pour dilution de concentrées d’hémodialyse» est produite en continue et utilisée en grande quantité chez l’hémodialysé chronique, donc il apparaît primordial de veiller à sa bonne qualité. Au Sénégal, aucune étude n’a été faite à ce jour pour évaluer l’efficacité du système de traitement de l’eau pour dilution des concentrés de dialyse dans les différents centres de dialyse du pays. L’objectif de ce travail est de contrôler l’efficacité du système de traitement de l’eau pour dilution de concentrées d’hémodialyse afin de s’assurer de son innocuité. Les prélèvements ont été effectués au niveau de trois points clés du circuit de traitement de l’eau pour hémodialyse. A l’entrée et à la sortie de l’osmoseur, à la sortie de la boucle de distribution. Les analyses ont été effectuées à l’aide d’électrodes spécifiques. Les valeurs de potentiels ont permis de tracer les courbes d’étalonnage. La détermination par régression des pentes et des ordonnées à l’origine de la relation de Nernst donne E(mV ) = B - A Log Cm avec des coefficients de corrélation variant entre 0,988 et 0,999 prouvant que 98% au moins des variations de tensions mesurées (E) sont attribuables à la concentration. L’analyse physico-chimique des teneurs en chlorures, nitrates et fluorures révèle des teneurs plus élevées à l’entrée de l’osmoseur qu’à la sortie. Ces basses valeurs découlent du rôle de l’osmoseur qui filtre une grande partie des électrolytes. Par contre, à la sortie de la boucle de distribution les teneurs en électrolytes des différents échantillons étaient plus importantes que celles à la sortie de l’osmoseur. Cette forte concentration en électrolytes atteste d’une pollution par la boucle de distribution de l’eau déjà filtrée par l’osmoseur. L’intérêt de cette étude réside dans le fait qu’elle met en lumière l’importance du contrôle de la qualité de l’eau pour l’hémodialyse et la nécessité d’un bon planning de maintenance préventive efficace de l’ensemble de la boucle de traitement d’eau au sein de chaque centre.© 2016 International Formulae Group. All rights reserved.Mots clés: Hémodialyse, eau, chlorures, fluorures, nitrates, électrodes spécifiquesEnglish Title: Physicochemical analysis of Saint–Louis regional hospital’s hemodialysis unit’s water (Senegal)English AbstractChronic kidney disease is a major public health problem worldwide. In Senegal, a recent study in the general adult population found a prevalence of about 6,1%. "Water for diluting concentrated hemodialysis" is produced and used continuously at high levels in hemodialysis chronic. It is therefore essential to ensure its quality. In Senegal, no study has been done to assess the effectiveness of water treatment system for dialysis concentrates dilution in different dialysis centers of the country. The objective of this work is to monitor the effectiveness of the water treatment system for hemodialysis concentrated dilution to ensure its safety. The samples were taken on key issues of hemodialysis water’s treatment circuit. Three levels of sampling were selected. At the entrance and at the outlet of the reverse osmosis unit at the outlet of the distribution loop. Analyses were performed using specific electrodes. Potential values allowed us to map the calibration curves. Determination by regression of slopes and intercepts of the Nernst relation gives with correlation coefficients ranging from 0.988 to 0.999 showing that at least 98% of the measured voltages fluctuations (E) are attributable to the concentration. Physicochemical analysis of the levels of chlorides, nitrates and fluorides reveals higher levels at the entrance of the reverse osmosis unit than at the outlet. These low values resulting of the role of reverse osmosis which filter much of the electrolytes. For against, at the outlet of the distribution loop the electrolyte content of the different samples were greater than those at the outlet of the reverse osmosis unit. This high electrolyte concentration attests to pollution of the water distribution loop already filtered by reverse osmosis. The interest of this study lies in the fact that it highlights the importance of monitoring the quality of water for hemodialysis and the need for good planning for effective preventive maintenance throughout the water treatment loop within each center.© 2016 International Formulae Group. All rights reserved.Keywords: Hemodialysis, water, nitrates, fluoride, chloride, specific electrode

Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity

Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear.; Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels.; There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss.; There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household

Méthode de Dandelin-Graeffe et méthode de Baker

L'objet général de ce travail est l'étude de la convergence des méthodes classiques de calcul approché des racines d'un polynôme à coefficients complexes. Les méthodes considérées sont celles de Bernoulli et de Graeffe-Dandelin. On montre que ces questions de convergence sont liées à des problèmes diophantiens et que les théorèmes d'approximation de Dirichlet et surtout la méthode de Baker fournissent des résultats de convergence nouveaux qui s'appliquent aux polynômes à coefficients entiers. De nombreux exemples calculés en MAPLE, y sont présentés et analysés.The main topic of this work is the study of the convergence of classical methods to compute approximate values for the roots of complex polynomials. Considered methods are those of Bernoulli and Graeffe-Dandelin. We show that these questions of convergence tie in with Diophantine problems and that the theorems of Dirichlet's approximation and especially Baker's method yield new results of convergence that hold for polynomials with integer coefficients. Many examples calculated in MAPLE, are presented and analyzed there.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Development of thermochemically induced fluorescence (TIF) method for the determination of insecticide deltamethrin in Senegalese natural waters

International audienceA simple and sensitive thermochemically induced fluorescence (TIF) method was developed to determine deltamethrin, an insecticide which has toxic effects on human beings and animals. After optimisation at different pH, temperature was increased from 25 to 50°C. TIF method is based on the thermolysis transformation of naturally non-fluorescent pesticides into a fluorescent thermoproduct. The thermolysis kinetics reaction investigated in water at optimal pH 12 and after 4 minutes heating at 40°C made it possible to obtain a low mean half-life time (t1/2 = 1.41 ± 0.06 min), which shows that deltamethrin degrades very rapidly due to heat. The obtained calibration curve gave correlation coefficients close to unity. The limit of detection (LOD = 4.4 ng mL−1) and quantification (LOQ = 15 ng mL−1) values were very low, showing the high sensitivity of the TIF method. TIF method was applied to determination of deltamethrin residues in tap and well waters by standard addition procedure, with satisfactory recovery values between 107.6 and 111.4%. The relative standard deviation (RSD) value of the measured concentrations in spiked water samples was less than 6%, which demonstrated good reproducibility of the TIF method

Rare predicted loss-of-function variants of type I IFN immunity genes are associated with life-threatening COVID-19

BackgroundWe previously reported that impaired type I IFN activity, due to inborn errors of TLR3- and TLR7-dependent type I interferon (IFN) immunity or to autoantibodies against type I IFN, account for 15-20% of cases of life-threatening COVID-19 in unvaccinated patients. Therefore, the determinants of life-threatening COVID-19 remain to be identified in similar to 80% of cases.MethodsWe report here a genome-wide rare variant burden association analysis in 3269 unvaccinated patients with life-threatening COVID-19, and 1373 unvaccinated SARS-CoV-2-infected individuals without pneumonia. Among the 928 patients tested for autoantibodies against type I IFN, a quarter (234) were positive and were excluded.ResultsNo gene reached genome-wide significance. Under a recessive model, the most significant gene with at-risk variants was TLR7, with an OR of 27.68 (95%CI 1.5-528.7, P=1.1x10(-4)) for biochemically loss-of-function (bLOF) variants. We replicated the enrichment in rare predicted LOF (pLOF) variants at 13 influenza susceptibility loci involved in TLR3-dependent type I IFN immunity (OR=3.70[95%CI 1.3-8.2], P=2.1x10(-4)). This enrichment was further strengthened by (1) adding the recently reported TYK2 and TLR7 COVID-19 loci, particularly under a recessive model (OR=19.65[95%CI 2.1-2635.4], P=3.4x10(-3)), and (2) considering as pLOF branchpoint variants with potentially strong impacts on splicing among the 15 loci (OR=4.40[9%CI 2.3-8.4], P=7.7x10(-8)). Finally, the patients with pLOF/bLOF variants at these 15 loci were significantly younger (mean age [SD]=43.3 [20.3] years) than the other patients (56.0 [17.3] years; P=1.68x10(-5)).ConclusionsRare variants of TLR3- and TLR7-dependent type I IFN immunity genes can underlie life-threatening COVID-19, particularly with recessive inheritance, in patients under 60 years old