Etude de la répartition des mollusques hôtes intermédiaires des schistosomes en Afrique de l'Ouest : premiers résultats

Au cours de 18 enquêtes réalisées dans 29 régions de 6 pays d'Afrique de l'Ouest (Bénin, Haute-Volta, Mali, Niger et Togo), une espèce de #Biomphalaria (#Biomphalaria pfeifferi) et six espèces de #Bulinus (#Bulinus truncatus rohlfsi, #Bulinus globosus, #Bulinus jousseaumei, #Bulinus umbilicatus, #Bulinus senegalensis et #Bulinus forskalii) ont été récoltées. L'ébauche de la carte de répartition de ces espèces permet de remarquer : la présence de trois espèces principales (#Biomphalaria pfeifferi, #Bulinus globosus et #Bulinus truncatus rohlfsi) ; l'absence de #Biomphalaria pfeifferi au dessus de 14° de latitude Nord ; l'existence d'une zone à #Bulinus truncatus rohlfsi au nord, d'une zone à #Bulinus globosus au Sud et d'une zone intermédiaire où ces deux espèces sont en sympatrie ; la présence possible de deux souches de #Schistosoma haematobium, chacune transmise par l'un des deux hôtes intermédiaires précédents. Les auteurs font remarquer la tendance à l'extension des parasitoses et de leur hôte intermédiaire, résultat des divers travaux d'aménagement hydraulique et la nécessité de sensibiliser les autorités aux problèmes de santé attachés à tout projet d'aménagement

Clinical Value of Prognostic Instruments to Identify Patients with an Increased Risk for Osteoporotic Fractures: Systematic Review

There is a plethora of evidence available studying the association of risk profiles and the development of osteoporotic fractures. The small number of out-of-sample validations, the large variety of study characteristics, outcomes and follow-up periods impedes from deriving robust summaries and from conclusions regarding the clinical performance of many tools. First and foremost, future activity in this field should aim at reaching a consensus among clinical experts in respect to the existing instruments. Then we call for careful validations and expedient adaptations for local circumstances of the most promising candidates

clag9 Is Not Essential for PfEMP1 Surface Expression in Non-Cytoadherent Plasmodium falciparum Parasites with a Chromosome 9 Deletion

BACKGROUND: The expression of the clonally variant virulence factor PfEMP1 mediates the sequestration of Plasmodium falciparum infected erythrocytes in the host vasculature and contributes to chronic infection. Non-cytoadherent parasites with a chromosome 9 deletion lack clag9, a gene linked to cytoadhesion in previous studies. Here we present new clag9 data that challenge this view and show that surface the non-cytoadherence phenotype is linked to the expression of a non-functional PfEMP1. METHODOLOGY/PRINCIPAL FINDINGS: Loss of adhesion in P. falciparum D10, a parasite line with a large chromosome 9 deletion, was investigated. Surface iodination analysis of non-cytoadherent D10 parasites and COS-7 surface expression of the CD36-binding PfEMP1 CIDR1α domain were performed and showed that these parasites express an unusual trypsin-resistant, non-functional PfEMP1 at the erythrocyte surface. However, the CIDR1α domain of this var gene expressed in COS-7 cells showed strong binding to CD36. Atomic Force Microscopy showed a slightly modified D10 knob morphology compared to adherent parasites. Trafficking of PfEMP1 and KAHRP remained functional in D10. We link the non-cytoadherence phenotype to a chromosome 9 breakage and healing event resulting in the loss of 25 subtelomeric genes including clag9. In contrast to previous studies, knockout of the clag9 gene from 3D7 did not interfere with parasite adhesion to CD36. CONCLUSIONS/SIGNIFICANCE: Our data show the surface expression of non-functional PfEMP1 in D10 strongly indicating that genes other than clag9 deleted from chromosome 9 are involved in this virulence process possibly via post-translational modifications

FRAX™ and the assessment of fracture probability in men and women from the UK

SUMMARY: A fracture risk assessment tool (FRAX) is developed based on the use of clinical risk factors with or without bone mineral density tests applied to the UK. INTRODUCTION: The aim of this study was to apply an assessment tool for the prediction of fracture in men and women with the use of clinical risk factors (CRFs) for fracture with and without the use of femoral neck bone mineral density (BMD). The clinical risk factors, identified from previous meta-analyses, comprised body mass index (BMI, as a continuous variable), a prior history of fracture, a parental history of hip fracture, use of oral glucocorticoids, rheumatoid arthritis and other secondary causes of osteoporosis, current smoking, and alcohol intake 3 or more units daily. METHODS: Four models were constructed to compute fracture probabilities based on the epidemiology of fracture in the UK. The models comprised the ten-year probability of hip fracture, with and without femoral neck BMD, and the ten-year probability of a major osteoporotic fracture, with and without BMD. For each model fracture and death hazards were computed as continuous functions. RESULTS: Each clinical risk factor contributed to fracture probability. In the absence of BMD, hip fracture probability in women with a fixed BMI (25 kg/m(2)) ranged from 0.2% at the age of 50 years for women without CRF's to 22% at the age of 80 years with a parental history of hip fracture (approximately 100-fold range). In men, the probabilities were lower, as was the range (0.1 to 11% in the examples above). For a major osteoporotic fracture the probabilities ranged from 3.5% to 31% in women, and from 2.8% to 15% in men in the example above. The presence of one or more risk factors increased probabilities in an incremental manner. The differences in probabilities between men and women were comparable at any given T-score and age, except in the elderly where probabilities were higher in women than in men due to the higher mortality of the latter. CONCLUSION: The models provide a framework which enhances the assessment of fracture risk in both men and women by the integration of clinical risk factors alone and/or in combination with BMD

Etude de la répartition des mollusques hôtes intermédiaires des schistosomes en Afrique de l'Ouest : premiers résultats

Au cours de 18 enquêtes réalisées dans 29 régions de 6 pays d'Afrique de l'Ouest (Bénin, Haute-Volta, Mali, Niger et Togo), une espèce de #Biomphalaria (#Biomphalaria pfeifferi) et six espèces de #Bulinus (#Bulinus truncatus rohlfsi, #Bulinus globosus, #Bulinus jousseaumei, #Bulinus umbilicatus, #Bulinus senegalensis et #Bulinus forskalii) ont été récoltées. L'ébauche de la carte de répartition de ces espèces permet de remarquer : la présence de trois espèces principales (#Biomphalaria pfeifferi, #Bulinus globosus et #Bulinus truncatus rohlfsi) ; l'absence de #Biomphalaria pfeifferi au dessus de 14° de latitude Nord ; l'existence d'une zone à #Bulinus truncatus rohlfsi au nord, d'une zone à #Bulinus globosus au Sud et d'une zone intermédiaire où ces deux espèces sont en sympatrie ; la présence possible de deux souches de #Schistosoma haematobium, chacune transmise par l'un des deux hôtes intermédiaires précédents. Les auteurs font remarquer la tendance à l'extension des parasitoses et de leur hôte intermédiaire, résultat des divers travaux d'aménagement hydraulique et la nécessité de sensibiliser les autorités aux problèmes de santé attachés à tout projet d'aménagement

Leishmania DNA is rapidly degraded following parasite death: an analysis by microscopy and real-time PCR.

Control of human leishmaniases relies on appropriate diagnosis and reliable methods for monitoring chemotherapy. The current method used for estimation of parasite burden during chemotherapy patient follow-up as well as in pharmacological studies performed in experimental models involves PCR-based assays. Compared to time-consuming conventional methods, this type of Leishmania DNA detection-based method is extremely sensitive, but could fail in distinguishing viable Leishmania from slowly degenerating ones. We have used an in vitro model to monitor the duration of Leishmania DNA persistence in mouse macrophages following exposure to l-leucine ester, a molecule otherwise known to rapidly kill intracellular Leishmania amazonensis amastigotes. At 1h of post l-leucine ester exposure, more than 98% of amastigote-loaded macrophages harbored killed parasites and parasite remnants, as assessed by microscopy. This dramatic decrease in parasite load and the microscopic parasite follow-up over the 120h time period studied were correlated with Leishmania DNA as quantified by real-time PCR. Our results indicate that kinetoplast and nuclear parasite DNA degradation occurs very rapidly after amastigote death. These data add further weight to the argument that PCR assays represent not only a robust method for diagnosis but can also be reliable for monitoring parasite size reduction rate post any intervention (Leishmania-targeting molecules, immunomodulators...)

Improved high-resolution EBSD analyses by correcting radial distortion of electron diffraction patterns

International audienceRegistering experimental and simulated electron diffraction patterns is increasingly used for advanced electron backscatter diffraction indexation (EBSD) analysis, yet the accuracy of registration is limited by several effects not accounted for in pattern simulation, such as the Kikuchi band (K-band) asymmetry, gray level reversal and (mainly radial) optical distortion. Radial distortion parameters have previously been measured with chessboardtype standard samples. Simulated patterns have been adopted to demonstrate the necessity of optical distortion removal in EBSD analyses. However there still lacks an efficient and precise radial distortion assessment and correction method. Here a simple radial distortion model, including barrel and pincushion distortions, is proposed to rectify the diffraction patterns during EBSD analyses. The correlation between experimental pattern and the simulated master pattern permits to index the diffraction pattern and assess the radial distortion simultaneously. The method is applied to three high-definition experimental electron diffraction datasets acquired with different cameras. The radial distortion parameter is identified with a relative uncertainty below 4%. The consideration of radial distortion improves the correlation between experimental and simulated patterns. Gray level profiles of the K-bands are analyzed to verify the correctness of image registration. The current method provides a fast, economic yet precise correction of the radial distortion for advanced EBSD analyses

Iron Oxide Monocrystalline Nanoflowers for Highly Efficient Magnetic Hyperthermia

International audienceMagnetic nanoparticles exhibit a high potential to selectively treat cancer by hyperthermia provided that high heating capacity can be reached. In this work, we report an efficient synthesis of novel structures of magnetic iron oxide. The particles, obtained by applying a modified “polyol” protocol, present a particular shape: they look constituted of smaller grains of approximately 11 nm, assembled in a flower-shaped structure. These nanoflowers, dispersed in water at physiological pH, present particularly interesting magnetic properties and a great capacity of heating. The value of the specific loss power (SLP) of these nanoflowers is 1 order of magnitude higher than the SLP reported for conventional 11 nm single-domain maghemite nanoparticles in the same condition of field exposure