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Abstract The greatest burden of sickle cell anemia (SCA) globally occurs in sub‐Saharan Africa, where significant morbidity and mortality occur secondary to SCA‐induced vasculopathy and stroke. Transcranial Doppler ultrasound (TCD) can grade the severity of vasculopathy, with disease modifying therapy resulting in stroke reduction in high‐risk children. However, TCD utilization for vasculopathy detection in African children with SCA remains understudied. The objective was to perform a prospective, observational study of TCD findings in a cohort of children with SCA from the Democratic Republic of the Congo, Zambia, and Malawi. A total of 770 children aged 2–17 years without prior stroke underwent screening TCD. A study was scored as low risk when the time‐averaged maximum of the mean (TAMMX) in the middle cerebral artery or terminal internal carotid artery was 50 cm/s, conditional risk when 170–200 cm/s, and high risk when >200 cm/s. Low‐risk studies were identified in 604 children (78%), conditional risk in 129 children (17%), and high risk in three children (0.4%). Additionally, 34 (4%) were scored as having an unknown risk study (TAMMX

The use of plant extracts as a bio-reducer for the synthesis of silver nanoparticles has attracted attention due to its rapid, ecological, non-toxic and economical protocol. The aim of this study was to investigate the possibility of synthesizing silver nanoparticles using Cymbopogon citratus leaf extract, and characterizing them by Ultraviolet-visible spectroscopy, X-ray Diffraction and X-ray Fluorescence in order to determine their size and composition, as well as to evaluate them in-vitro bioactivity on selected models. The results of this study show that silver nanoparticles were successfully synthesized, with a size of 29.49 nm. The silver nanoparticles showed bactericidal activity against all three types of bacteria (E. coli ATCC 25922, S. aureus ATCC 25923, and P. aerugunosa ATCC 27853) at the minimum inhibitory concentration (MIC=31.25 μg/mL), larvicidal activity against Anopheles larvae and reasonable antioxidant properties. All these results demonstrate the biopharmaceutical potential of these new products. These nanoparticles, synthesized from plant extracts, could be a promising solution for the treatment of a number of diseases, including malaria, bacterial infections and diseases caused by oxidative stress.

La coopération internationale constitue chaque jour davantage une importance capitale dans les vies des Etats, des organisations internationales et des sociétés multinationales, c’est un cadre par excellence où les Etats entretiennent des bonnes relations entre eux, une plateforme où les Etats avancés apportent aux pays en développement leur aide. Nul n’ignore aujourd’hui qu’un Etat ne peut vivre en autarcie, en vase clos où toutes ses activités sont fermées sans toutefois avoir l’aide extérieure par le biais de la coopération. L’aide extérieure se présente comme un moyen par lequel un Etat fait recours afin de soutenir ses activités et de renforcer son capital, pour échapper à l’inflation ou à une crise économique dont aucun Etat ne peut s’en passer.

Each year more than 150, 000 tons of dyes are released in effluents by industries. These chemicals entities non-biodegradable and toxic can be removed from effluent by metallic nanomaterials. The aqueous extract of Manotes expansa leaves is used as reducing and stabilizing agent in the biogenic synthesis of Mn-CuO nanocomposites. The nanoparticles obtained were characterized using UV-visible spectroscopy, X-ray Diffraction (XRD), X-ray Fluorescence, Dynamic Light Scattering (DSL), and Scanning Electron Microscopy (SEM). The hemotoxicity of biosynthesized nanomaterials was assessed by evaluating their hemolytic activity using erythrocytes as a model system. The photocatalytic activity of Mn-CuO was carried out by photocatalytic degradation of Methylene Blue dye as a model. The results obtained by UV-vis spectroscopy showed a Plasmonic Surface Resonance band at 408 nm. XRD and X-ray fluorescence made it possible to identify the presence of particles of formula Mn0.53Cu0.21O having crystallized in a Hexagonal system (a = 3.1080 Å and c = 5.2020 Å). Spherical morphology and average height 49.34 ± 6.71 nm were determined by SEM and DSL, respectively. The hemolytic activity of biosynthesized nanomaterials revealed that they are not hemotoxic in vitro (% hemolysis 3.2%) and 98.3% of Methylene Blue dye was removed after 120 min under irradiation with solar light in the presence of Mn-CuO nanocomposites.

One of the most important processes for mass movement in coastal areas is sediment transport; it plays a significant role in coastal morphology changes. This manuscript focuses on the distribution and variation in surface-suspended sediments in the North Passage of the Yangtze Estuary. Field data on surface-suspended sediment concentration (SSSC) and suspended particle size (SPS) were collected at fifteen hydrological sites over a period of three years, from 2016 to 2018. The main objective was to analyze the spatial and temporal patterns of sediment and particle size and their potential impact on the estuary. Results indicate that extreme weather events have an influence on the hydrological conditions and sediment dynamics of the area. The intensity and range of SSSC variation in the North Passage seem to be determined by the magnitude of the current velocity, while the sediment load significantly impacted the sediment distribution pattern. This study demonstrates that surface sediment dynamics can be used as a basis for understanding the spatiotemporal variation in estuarine turbidity maximum (ETM) in the North Passage of the Yangtze Estuary.

One of the most appealing aspects of machine learning for material design is its high throughput exploration of chemical spaces, but to reach the ceiling of machine learning-aided exploration, more than current model architectures and processing algorithms are required. New architectures such as graph neural networks have seen significant research investments recently. For heterogeneous catalysis, defining substrate intramolecular bonds and adsorbate/substrate intermolecular bonds is a time-consuming and challenging process. Before applying a model, dataset pre-processing, node/bond descriptor design, and specific model constraints have to be considered. In this work, a framework designed to solve these issues is presented in the form of an automatic graph representation algorithm (AGRA) tool to extract the local chemical environment of metallic surface adsorption sites. This tool is able to gather multiple adsorption geometry datasets composed of different systems and combine them into a single model. To show AGRA’s excellent transferability and reduced computational cost compared to other graph representation methods, it was applied to five different catalytic reaction datasets and benchmarked against the Open Catalyst Projects graph representation method. The two oxygen reduction reaction (ORR) datasets with O/OH adsorbates obtained 0.053 eV root-mean-square deviation (RMSD) when combined together, whereas the three carbon dioxide reduction reaction datasets with CHO/CO/COOH obtained an average performance of 0.088 eV RMSD. To further display the algorithm’s versatility and extrapolation ability, a model was trained on a subset combination of all five datasets with an RMSD of 0.105 eV. This universal model was then used to predict a wide range of adsorption energies and an entirely new ORR catalyst system, which was then verified through density functional theory calculations.

This study consists of biogenic synthesis of Ag-MnO nanocomposite whose aqueous extract from Cyttaranthus congolensis was used as a reducer and stabilizer. The characterization of these particles by visible UV spectroscopy made it possible to identify the band linked to the surface plasmon resonance located around 380 nm. X-ray Diffraction and Fluorescence made it possible to determine the presence of particles of formula Ag 0.21 Mn 0.28 O having crystallized in a Monoclinic system (a= 5.8517 , b = 3.4674 , c = 5.4838 and β = 107.663°). A spherical morphology was determined by Scanning Electron Microscopy (SEM). The haemolytic activity carried out on human blood made it possible to conclude that Ag-MnO nanocomposites are not toxic to human blood. Moreover, these particles showed good antibacterial activity against gram-positive and gram-negative strains of bacteria. Promising results on anthelminthic activity of Ag-MnO nanocomposites against several pathogenic helmints were reported in this study. Besides antibacterial and antihelmintic activities, Ag-MnO nanocomposites also exhibited good anti-inflammatory and antioxidant activity.

Background: Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, an obligate intracellular protozoan responsible for one of the most common congenital infections in the world. This study aimed to determine the seroprevalence and risk factors associated with toxoplasmosis in pregnant women consulted in three health centers in the city of Dschang. Methods: This study was a cross-sectional study that was conducted, with a total of 242 participants. A questionnaire was administered after obtaining the free and informed consent of the participants. Blood sample was collected to assay IgG and IgM antibodies specific to Toxoplasma gondii using the enzyme-linked immunosorbent assay (ELISA) kit, and potential risk factors were evaluated with the administration questionnaire using a binary logistic regression model. Statistical significance was measured at P

Background and purpose: Transcranial doppler ultrasound (TCD) is a tool that diagnoses and monitors pathophysiological changes to the cerebrovasculature. As cerebral blood flow velocities (CBFVs) increase throughout childhood, interpretation of TCD examinations in pediatrics requires comparison to age matched normative data. Large cohorts of healthy children have not been examined to develop these reference values in any population. There is a complete absence of normative values in African children where, due to lack of alternate neuroimaging techniques, utilization of TCD is rapidly emerging. Materials and methods: A prospective study of 710 healthy African children 3 months-15 years was performed. Demographics, vital signs, and hemoglobin values were recorded. Participants underwent a complete, non-imaging TCD examination. Systolic (Vs), diastolic (Vd), and mean (Vm) flow velocities and pulsatility index (PI) were calculated by the instrument for each measurement. Results: Vs, Vd, and Vm increased through early childhood in all vessels, with the highest CBFVs identified in children 5–5.9 years. There were few significant gender differences in CBFVs in any vessels in any age group. No correlations between blood pressure or hemoglobin and CBFVs were identified. Children in the youngest age groups had CBFVs similar to those previously published, whereas nearly every vessel in children ≥3 years had significantly lower Vs, Vd, and Vm. Conclusions: For the first time, reference TCD values for African children are established. Utilization of these CBFVs in the interpretation of TCD examinations in this population will improve the overall accuracy of TCD as a clinical tool on the continent.

Résumé La réalité actuelle des Nations en Afrique et dans le monde fait l’objet de plusieurs controverses autour de la mission principale de l’Organisation des Nations Unies. Cette réalité mal gérée depuis des décennies par l’ONU a occasionné des crises politiques, des conflits armés, des guerres et des inégalités des peuples du monde. L’idée de la Conférence de la Haye après la faillite de la Société des Nations avait comme but de mettre en place des outils permettant de résoudre pacifiquement les crises, d’éviter les guerres et d’établir des règlements pacifiques des conflits, mais surtout de consolider la paix et la sécurité dans le monde. Cette ultime mission semble être loin des préoccupations majeures de l’ONU dans la mesure où le Conseil de Sécurité avec ses cinq membres permanents ne permet pas aux nouveaux Etats et aux pays sous-développés de jouir pleinement de leur souveraineté face à ces problèmes. Il est donc nécessaire et urgent que les reformes du système onusien aient lieu afin d’assurer l’équilibre mondial. Abstract The actual reality of Nations in Africa and in the world is marked by many controversies about the main mission of the United Nations Organization. This reality has produced political crises, armed conflicts, wars and inequality among people around the word due to the bad administration of the UN since some decades. The idea of the Haye conference after the failure of the League of Nations aimed at establishing tools in order to resolve crises peaceably, to avoid wars and promote peaceful conflicts regulation but also to solidify world’s peace and security. This final mission seems to be far from the major preoccupations of the UN due to the fact that the Security Council with its five permanent members do not permit to the new States and poor counties to enjoy fully their sovereignty face to issues. So, it is very important and imperative that the reform of the United Nations System be carried out in order to insure global balance.

Nowadays, research on environmentally friendly materials has become a significant challenge in the field of civil engineering. In this study, stabilized compressed earth bricks (CEBs) incorporating recycled expanded polystyrene (EPS) beads were studied with the aim of enhancing the development of green constructions. The mass contents of recycled EPS in CEB formulated at a compaction pressure of 5 MPa are 0%, 0.25%, 0.5%, 0.75%, and 1% relative to the mass of the soil, while cement type CEM I 32.5, as a stabilizer, constituted 8% by mass. Characterization was carried out by determining densities, dry and wet compressive strength, flexural strength, total water absorption, and capillarity. Sample properties were found to be strongly influenced by the percentage of recycled EPS. Increasing the EPS aggregate content led to a reduction in compressive strength in both wet and dry conditions. Samples with 0.5% EPS and 8% cement offered better physical and mechanical performance. Samples containing EPS had relatively low water absorption, which would contribute to good durability. These CEBs comply with the wall construction requirements for two-story dwellings. This study also demonstrates the potential use of this recycled material in the construction industry.

Clay mineral authigenesis at continental margins plays an important role in global marine element cycles. However, despite being increasingly used as tracers for both modern and past oceanographic conditions, the behavior of the rare earth elements (REEs) and their isotopes during marine clay authigenesis still remains poorly known. In this study, we report on a detailed geochemical investigation of glauconite from the West African continental shelf, near the mouth of the Congo River. Elemental, neodymium, and hafnium isotope analyses were conducted on both acid leachate and separated clay-size fractions of glauconite pellets, in order to investigate the behavior of REE during the formation of authigenic clays. Our data indicate that kaolinite dissolution and subsequent Fe-bearing clay authigenesis act as a net source of REEs to seawater. We show that enhanced glauconitization, as inferred from increasing Fe and K contents, is accompanied by significant decoupling of the REE toward markedly LREE-enriched shale-normalized patterns in neoformed clay separates. Using both Nd and Hf isotopes and SEM observations, we rule out any seawater influence and argue that this shift primarily reflects the progressively overwhelming presence of insoluble nanocrystals of detrital LREE-rich phosphates, which are known to occur in close association with kaolinite in tropical soils. Due to their marked insolubility in surface environments, such nanocrystals can be preserved during kaolinite dissolution and subsequently incorporated into the aggregates of authigenic green clays forming the peloids. Most strikingly, we show that the combined influence of net REE loss (due to kaolinite dissolution) and decoupling (due to subsequent entrapment of inherited LREE-bearing accessory phases into neoformed clay minerals) is accompanied by preferential release of a dissolved REE fraction characterized by seawater-like distribution patterns. These findings reinforce the emerging view that clay mineral dissolution and authigenesis at continental margins possibly play a major role in marine REE cycling.

Abstract Novel tuberculosis (TB)-vaccines preferably should (i) boost host immune responses induced by previous BCG vaccination and (ii) be directed against Mycobacterium tuberculosis (Mtb) proteins expressed throughout the Mtb infection-cycle. Human Mtb antigen-discovery screens identified antigens encoded by Mtb-genes highly expressed during in vivo murine infection (IVE-TB antigens). To translate these findings towards animal models, we determined which IVE-TB-antigens are recognised by T-cells following Mtb challenge or BCG vaccination in three different mouse strains. Eleven Mtb-antigens were recognised across TB-resistant and susceptible mice. Confirming previous human data, several Mtb-antigens induced cytokines other than IFN-γ. Pulmonary cells from susceptible C3HeB/FeJ mice produced less TNF-α, agreeing with the TB-susceptibility phenotype. In addition, responses to several antigens were induced by BCG in C3HeB/FeJ mice, offering potential for boosting. Thus, recognition of promising Mtb-antigens identified in humans validates across multiple mouse TB-infection models with widely differing TB-susceptibilities. This offers translational tools to evaluate IVE-TB-antigens as diagnostic and vaccine antigens.

Thirty-eight samples were taken from the banks of the Sanaga River and its main tributaries draining different plant ecosystems, but also from rivers in the coastal basins of Cameroon. This study aims to characterize the origins of pollen and the dominant mode of transport of pollen inputs to the continental shelf. The classical method of pollen spectra analysis and multivariate statistical analysis revealed three groups of samples corresponding to the three main ecosystems in which the samples were taken. Pollens typical of the northern savannas are found in the spectra of samples taken further downstream from the Sanaga River in forest areas and not in samples from rivers draining mainly the forested coastal basins. The level of similarity between groups and the spatial evolution of spectra from upstream to downstream are related to the fluvial transport of pollen.

Eumelanin is an important pigment, for example, in skin, hair, eyes, and the inner ear. It is a highly heterogeneous polymer with 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and 5,6-dihydroxyindole (DHI) building blocks, of which DHICA is reported as the more abundant in natural eumelanin. The DHICA-eumelanin protomolecule consists of three building blocks, indole-2-carboxylic acid-5,6-quinone (ICAQ), DHICA and pyrrole-2,3,5-tricarboxylic acid (PTCA). Here, we focus on the self-assembly of DHICA-eumelanin using multi-microsecond molecular dynamics (MD) simulations at various concentrations in aqueous solutions. The molecule was first parameterized using density functional theory (DFT) calculations. Three types of systems were studied: (1) uncharged DHICA-eumelanin, (2) charged DHICA-eumelanin corresponding to physiological pH, and (3) a binary mixture of both of the above protomolecules. In the case of uncharged DHICA-eumelanin, spontaneous aggregation occurred and water molecules were present inside the aggregates. In the systems corresponding to physiological pH, all the carboxyl groups are negatively charged and the DHICA-eumelanin model has a net charge of −4. The effect of K+ ions as counterions was investigated. The results show high probability of binding to the deprotonated oxygens of the carboxylate anions in the PTCA moiety. Furthermore, the K+ counterions increased the solubility of DHICA-eumelanin in its charged form. A possible explanation is that the charged protomolecules favor binding to the K+ ions rather than aggregating and binding to other protomolecules. The binary mixtures show aggregation of uncharged DHICA-eumelanins; unlike the charged systems with no aggregation, a few charged DHICA-eumelanins are present on the surface of the uncharged aggregation, binding to the K+ ions.

For a long time, particular attention was paid to glauconitization in the surficial sediments lying on the outer continental shelves of present oceans. Subsequently, the processes observed and analyzed may have served as models for studies of glauconite in Cenozoic or even Mesozoic shelf deposits. Access to the sedimentary domains of deep oceans, particularly those of contouritic accumulation fields, has made it possible to discover unexpected processes of glauconitization. Thus, the long-term prevalence of control using fairly high-temperature water has become obsolete, and the prerequisite influence of continental flows has come to be considered on a new scale. Frequently, sediments from contouritic accumulation provide a condensed and undisturbed sedimentary record without periods of sediment erosion. Glauconitic grains could possibly integrate the signatures of bottom-water masses over prolonged periods of time, which, while preventing their use in high-resolution studies, would provide an effective means of yielding reliable average estimates on past εNd signatures of bottom-water masses. In this regard, glauconitic grains are probably better-suited to paleoceanographic reconstructions than foraminifera and leached Fe-oxyhydroxide fractions, which appear to be influenced by sediment redistribution and the presence of terrestrial continental Fe-oxides, respectively. Direct methodological access to the compositions of the semi-confined microenvironments of neoformation has largely renewed the information, chemical or crystallographic, that was previously, and for a long time, restricted to macromeasurements. The various granular supports (mudclasts, fecal pellets, and foraminifera infillings) include inherited 1:1 clays (or Te-Oc; i.e., clay minerals consisting of one tetrahedral sheet and one octahedral sheet, such as kaolinite) that are gradually replaced by 2:1 clays (Te-Oc-Te) dominated first by smectite, and then by glauconite. In small pores, the water’s activity is diminished; as a consequence, the precipitation of a great number of mineral species is thereby made easier, and their stability domains are changed. A specific methodological approach allows the study of the mineralogy and chemistry of the fine-scale mineral phases and to avoid the global aspect of the analytical methods previously used in the initial studies. Wide-field micrographs taken at a mean direct magnification of 100.000 show the intimate and characteristic organization of the main phases that occur in a single grain. One or several “fine” (about 10 nanometers in scale) microchemical analyses can be recorded, and directly coupled with each interesting and well-identified structure image observed in HRTEM.

Contourite sediment accumulations at continental margins are related to strong bottom water circulation, where intense winnowing can result in neoformation of authigenic grains of glauconite at the seafloor. In this study, we investigated whether such glauconite grains could faithfully record ambient bottom-water neodymium (Nd) isotopic compositions, and hence be used as paleoceanographic archives. To this purpose, we measured Nd isotopic compositions (εNd) in a series of glauconitic grains, foraminiferal assemblages, leached Fe-Mn oxyhydroxide phases, and detrital clays separated from a contourite sediment record at the Demerara slope off French Guiana (IG-KSF-11; 2370 m water depth), at a location where the present-day εNd distribution along the water column is well characterised. We show that the εNd composition of core-top glauconite grains (−12.0 ± 0.5) agrees with the expected NADW-like seawater signature at the same location and water depth (−11.6 ± 0.3), while departing from measured εNd values for corresponding detrital clays (−11.3 ± 0.2), foraminiferal (−10.9 ± 0.2), and Fe-Mn oxyhydroxide fractions (−9.2 ± 0.2). This finding indicates that glauconitic grains at this particular location are probably best suited for paleoceanographic reconstructions than foraminifera and leached Fe-oxyhydroxide fractions, which appear to be influenced by sediment redistribution and the presence of terrestrial continental Fe-oxides, respectively. Using rare earth elements (REE), we tentatively propose that the acquisition of seawater Nd isotopic signatures by glauconite is controlled by the presence of authigenic REE-bearing phosphate-rich phases intertwined within clay mineral sheets, while confirming previous findings that the process of glauconitisation results in the progressive loss of REE within glauconitic grains. Preliminary paleoceanographic implications suggest strengthened bottom-water circulation of the glacial analogue of NADW at this particular location and water depth, with a εNd signature (between −10.8 and −11.5) similar to that of modern NADW.

Electric power distribution systems have been heavily engaged in evolutionary changes toward effective usage of distribution networks for dependability, quality, and improvement of services delivered to customers throughout the years. This was accomplished via a procedure known as reconfiguration. Several strategies have been offered by various authors for successful distribution feeder reconfiguration with a novel optimization method. As a result, this work developed a Discrete Particle Swarm Optimization (DPSO) method to address the issue of distribution system feeder reconfiguration during both steady-state and dynamic power system operations. In a dynamic state, the power demand and generation required are continually changing over time, and the DPSO algorithm finds a new set of solutions to fulfill the power demand. Many network topologies are investigated for the dynamic operation. The feeder reconfiguration single-objective optimization problem was transformed into a multi-objective optimization problem by taking into account both real power loss reduction and distribution system load balancing. The suggested technique was verified using various IEEE 16, 33, and 69 bus standard test distribution systems to determine the efficiency of the developed DPSO algorithm. The simulation findings reveal that DPSO outperforms other optimization algorithms in terms of actual power loss reduction and load balancing, while solving multi-objective distribution system feeder reconfiguration.

Several seed and seedling traits are measured to evaluate germination and emergence potential in relation with environmental conditions. More generally, these traits are also measured in the field of ecology as simple traits that can be correlated to other adaptative traits more difficult to measure on adult plants, as for example traits of the rooting system. Methods were developed for deep high throughput phenotyping of hundreds of genotypes from dry seed to the end of heterotrophic growth. The present dataset comes from a project on genotyping and phenotyping of populations of genotypes, with different geographic and genetic origins so as to increase genotypic diversity of sugar beet in terms of germination and early growth traits, evaluated at low temperatures. Data were collected in relation to the creation of the first sugar beet crop ontology. This dataset corresponds to the first automated phenotyping of a population of 198 genotypes and 4 commercial control varieties and is hosted on INRAE public depository under the reference number doi.org/10.15,454/AKNF4Q. The equipment and methods presented here are available on a phenotyping platform opened to collaborative research and adaptable for specific services for characterizing thousands of genotypes on different crops or other species. The phenotyping values can also be linked to genomic information to study the genetic determinism of the trait values. Keywords: Seed, Seedling, Germination, Heterotrophic growth, Automated phenotyping, Sugar beet, Genotypes

INTRODUCTION : le faible poids de naissance (FPN) est un important prédicteur de survie de l’enfant et de son développement ultérieur. De par sa physiopathologie, le paludisme est présumé en être un des facteurs de risques. La présente étude avait pour but de déterminer l’association entre l’accès palustre chez la femme enceinte (FE) et la survenue du FPN (poids 2500 g).Méthodes: il s’est agi d’une enquête analytique de type cas-témoins, basée sur l’administration d’un questionnaire et d’une grille d’observation. Nous avons calculé l’Odds ratio (OR) brut et l’OR ajusté pour déterminer l’association. La régression logistique a été appliquée pour reconnaître les variables qui sont effectivement les déterminants du problème étudié.Résultats: cent cinquante-six (156) femmes dont 78 cas et 78 témoins ont participé à la présente étude. La prévalence de FPN était de 12,32% (105/852); 41,02% (64/156) des femmes ont eu un accès palustre durant leurs grossesses et 42,14% de parturientes ont pris leurs trois doses de TPI (traitement préventif intermittent). Nous avons ressorti une association significative entre le paludisme et le FPN avec un OR brute = 3,75 [P = 0,0001 (p = 0,05)] et l’OR ajusté = 2,82 [P = 0,01 (p = 0,05)] a été obtenu en tenant compte des différents facteurs de confusions.Conclusion: la survenue du paludisme durant la grossesse est un facteur qui augmente le risque de FPN. Les efforts devraient être faits pour améliorer la couverture en TPI et en utilisation de moustiquaire imprégnée d’insecticide à longue durée d’action afin de prévenir le paludisme durant la grossesse.

Cobalt porphyrin phospholipid (CoPoP) can incorporate within bilayers to enable non-covalent surface-display of antigens on liposomes by mixing with proteins bearing a polyhistidine tag (his-tag); however, the mechanisms for how this occurs are poorly understood. These were investigated using the his-tagged model antigen Pfs25, a protein antigen candidate for malaria transmission-blocking vaccines. Pfs25 was found to associate with the small molecule aquocobalamin, a form of vitamin B12 and a cobalt-containing corrin macrocycle, but without particle formation, enabling comparative assessment. Relative to CoPoP liposomes, binding and serum stability studies indicated a weaker association of Pfs25 to aquocobalamin or cobalt nitrilotriacetic acid (Co-NTA) liposomes, which have cobalt displayed in the aqueous phase on lipid headgroups. Antigen internalization by macrophages was enhanced with Pfs25 bound to CoPoP liposomes. Immunization in mice with Pfs25 bound to CoPoP liposomes elicited antibodies that recognized ookinetes and showed transmission-reducing activity. To explore the physical mechanisms involved, we employed molecular dynamics (MD) simulations of bilayers containing phospholipid, cholesterol, as well as either CoPoP or NTA-functionalized lipids. The results show that the CoPoP-containing bilayer creates nanodomains that allow access for a limited but sufficient amount of water molecules that could be replaced by his-tags due to their favorable free energy properties allowing for stabilization. The position of the metal center within the NTA liposomes was much more exposed to the aqueous environment, which could explain its limited capacity for stabilizing Pfs25. This study illustrates the impact of CoPoP-induced antigen particleization in enhancing vaccine efficacy, and provides molecular insights into the CoPoP bilayer properties that enable this.

ABSTRACT Leucoderma syphiliticum (LS), originally described as syphilide pigmentaire, encompasses a spectrum of dyschromic lesions that emerge during the course of secondary syphilis. Very few case reports are available in modern biomedical databases. We present the case of a 57-year-old HIV-infected male patient who presented with several round to oval, non-scaling, slightly raised and well-demarcated hypochromic lesions scattered over the trunk, abdomen, dorsum, and arms. Prior non-treponemal tests were negative for syphilis, but novel studies yielded positive results at high titers. Skin lesions slowly regressed and the hypochromic areas repigmented a few weeks after benzathine penicillin G treatment. This is the first report of LS in an HIV-infected patient. A review of modern and ancient literature was performed. The present case report emphasizes the need for clinicians to have a heightened awareness of the varied and unusual clinical phenotypes of syphilis.

This study develops an original co-infection model in mice using Brucella melitensis, the most frequent cause of human brucellosis, and Trypanosoma brucei, the agent of African trypanosomiasis. Although the immunosuppressive effects of T. brucei in natural hosts and mice models are well established, we observed that the injection of T. brucei in mice chronically infected with B. melitensis induces a drastic reduction in the number of B. melitensis in the spleen, the main reservoir of the infection. Similar results are obtained with Brucella abortus- and Brucella suis-infected mice and B. melitensis-infected mice co-infected with Trypanosoma cruzi, demonstrating that this phenomenon is not due to antigenic cross-reactivity. Comparison of co-infected wild-type and genetically deficient mice showed that Brucella elimination required functional IL-12p35/IFNγ signaling pathways and the presence of CD4+ T cells. However, the impact of wild type and an attenuated mutant of T. brucei on B. melitensis were similar, suggesting that a chronic intense inflammatory reaction is not required to eliminate B. melitensis. Finally, we also tested the impact of T. brucei infection on the course of Mycobacterium tuberculosis infection. Although T. brucei strongly increases the frequency of IFNγ+CD4+ T cells, it does not ameliorate the control of M. tuberculosis infection, suggesting that it is not controlled by the same effector mechanisms as Brucella. Thus, whereas T. brucei infections are commonly viewed as immunosuppressive and pathogenic, our data suggest that these parasites can specifically affect the immune control of Brucella infection, with benefits for the host.

Past limnological conditions of Lake Mbalang (7°19′ N, 13°44′ E, altitude: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (δ13C) since 7200 cal yr BP. The data showed that before 3600 cal yr BP, the water column was dominantly stable except around 5000–5300 cal yr BP where diatoms evidenced a mixed upper water layer and δ13C data suggest more forested vegetation in the landscape. These stable conditions can be explained by a strong monsoon flux and relatively northern position of the ITCZ that entailed high or low rainfall well distributed over the year, allowing the development of mountainous forest taxa. The decreasing trend of the monsoon flux towards the mid-Holocene was affected by several abrupt centennial to millennial-scale weakening at 6700, 5800–6000, 5000–5300, 4500 and 3600 cal yr BP. However, their impact on the vegetation is not visible, probably because rainfall distribution was favourable to forest maintenance or extension. After 3600 cal yr BP, the water column became very mixed as a result of more intense NE trade winds (Harmattan) that led at ~3000 cal yr BP to the establishment of savannah in the vegetation landscape. At that time, rainfall was probably reduced following the southward shift of the ITCZ, and the distribution of yearly rainfall was not favourable anymore to forest development. A strong seasonality with a marked dry season was established, conditions that maintained the savannah vegetation until today. Diatom data suggest the lake did not dry up during the last 7200cal yr BP; however, a low lake level observed at 2400–2100 cal yr BP is contemporaneous to a climatic event evidenced in several areas of tropical Africa and could correspond to the southernmost position of the ITCZ. Other low lake levels are observed at 1800 and 1400 cal yr BP, after which the lake rose to its present level.