Prions in Milk from Ewes Incubating Natural Scrapie

Since prion infectivity had never been reported in milk, dairy products originating from transmissible spongiform encephalopathy (TSE)-affected ruminant flocks currently enter unrestricted into the animal and human food chain. However, a recently published study brought the first evidence of the presence of prions in mammary secretions from scrapie-affected ewes. Here we report the detection of consistent levels of infectivity in colostrum and milk from sheep incubating natural scrapie, several months prior to clinical onset. Additionally, abnormal PrP was detected, by immunohistochemistry and PET blot, in lacteal ducts and mammary acini. This PrPSc accumulation was detected only in ewes harbouring mammary ectopic lymphoid follicles that developed consequent to Maedi lentivirus infection. However, bioassay revealed that prion infectivity was present in milk and colostrum, not only from ewes with such lympho-proliferative chronic mastitis, but also from those displaying lesion-free mammary glands. In milk and colostrum, infectivity could be recovered in the cellular, cream, and casein-whey fractions. In our samples, using a Tg 338 mouse model, the highest per ml infectious titre measured was found to be equivalent to that contained in 6 µg of a posterior brain stem from a terminally scrapie-affected ewe. These findings indicate that both colostrum and milk from small ruminants incubating TSE could contribute to the animal TSE transmission process, either directly or through the presence of milk-derived material in animal feedstuffs. It also raises some concern with regard to the risk to humans of TSE exposure associated with milk products from ovine and other TSE-susceptible dairy species

A HIV-1 Tat mutant protein disrupts HIV-1 Rev function by targeting the DEAD-box RNA helicase DDX1

BACKGROUND: Previously we described a transdominant negative mutant of the HIV-1 Tat protein, termed Nullbasic, that downregulated the steady state levels of unspliced and singly spliced viral mRNA, an activity caused by inhibition of HIV-1 Rev activity. Nullbasic also altered the subcellular localizations of Rev and other cellular proteins, including CRM1, B23 and C23 in a Rev-dependent manner, suggesting that Nullbasic may disrupt Rev function and trafficking by intervening with an unidentified component of the Rev nucleocytoplasmic transport complex. RESULTS: To seek a possible mechanism that could explain how Nullbasic inhibits Rev activity, we used a proteomics approach to identify host cellular proteins that interact with Nullbasic. Forty-six Nullbasic-binding proteins were identified by mass spectrometry including the DEAD-box RNA helicase, DDX1. To determine the effect of DDX1 on Nullbasic-mediated Rev activity, we performed cell-based immunoprecipitation assays, Rev reporter assays and bio-layer interferometry (BLI) assays. Interaction between DDX1 and Nullbasic was observed by co-immunoprecipitation of Nullbasic with endogenous DDX1 from cell lysates. BLI assays showed a direct interaction between Nullbasic and DDX1. Nullbasic affected DDX1 subcellular distribution in a Rev-independent manner. Interestingly overexpression of DDX1 in cells not only restored Rev-dependent mRNA export and gene expression in a Rev reporter assay but also partly reversed Nullbasic-induced Rev subcellular mislocalization. Moreover, HIV-1 wild type Tat co-immunoprecipitated with DDX1 and overexpression of Tat could rescue the unspliced viral mRNA levels inhibited by Nullbasic in HIV-1 expressing cells. CONCLUSIONS: Nullbasic was used to further define the complex mechanisms involved in the Rev-dependent nuclear export of the 9 kb and 4 kb viral RNAs. All together, these data indicate that DDX1 can be sequestered by Nullbasic leading to destabilization of the Rev nucleocytoplasmic transport complex and decreased levels of Rev-dependent viral transcripts. The outcomes support a role for DDX1 in maintenance of a Rev nuclear complex that transports viral RRE-containing mRNA to the cytoplasm. To our knowledge Nullbasic is the first anti-HIV protein that specifically targets the cellular protein DDX1 to block Rev’s activity. Furthermore, our research raises the possibility that wild type Tat may play a previously unrecognized but very important role in Rev function. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12977-014-0121-9) contains supplementary material, which is available to authorized users

Simulations aérodynamiques avancées de profils givrés

International audienceThe paper presents a numerical investigation of the flow around a NACA23012 airfoil with two ice shapes, a spanwise ridge and leading edge roughness. RANS and URANS simulations are completed with various 1 st and 2 nd order turbulence models (Spalart-Allmaras, Menter SST, EARSM, DRSM) for a selected number of points of the airfoil polar. To assess the ability of advanced unsteady hybrid RANS/LES models, one selected flow condition of the spanwise ridge case is also computed with a ZDES hybrid method. The results are compared with experimental data (integrated loads, pressure distribution, velocity field) obtained in the ONERA F1 wind tunnel. The Spalart-Allmaras model is the only RANS model among those assessed in this study converging efficiently towards steady-state whatever the flow condition considered. Together with DRSM, it also provides a reasonable predictive effect on the performance degradation due to ice shape. DRSM is much more expensive as it contains more physics, providing natural unsteady solutions which have to be time-averaged. DRSM first and second-order statistic fields compare well with ZDES ones, both of them indicating that geometrical three-dimensionality of the ice shapes should be taken into account. Furthermore, the unsteady content of the DRSM URANS solution is compared with that of ZDES, showing that the vortex shedding phenomenon can also be captured by DRSM.Le document présente une étude numérique de l'écoulement autour d'un profil NACA23012 avec deux formes de givre, une crête dans le sens de l'envergure et une rugosité de bord d'attaque. Les simulations RANS et URANS sont réalisées avec divers modèles de turbulence des premier et deuxième ordres (Spalart-Allmaras, Menter SST, EARSM, DRSM) pour un certain nombre de points de la polaire. Pour évaluer la capacité des modèles hybrides RANS/LES avancés, une condition d'écoulement du cas de la crête transversale est également calculée à l'aide d'une méthode hybride ZDES. Les résultats sont comparés aux données expérimentales (charges intégrées, distribution de la pression, champ de vitesse) obtenues dans la soufflerie F1 de l'ONERA. Le modèle de Spalart-Allmaras est le seul modèle RANS parmi ceux évalués dans cette étude qui converge efficacement vers un état stationnaire, quelle que soit la condition d'écoulement considérée. Avec le DRSM, il fournit également un outil de précision raisonnable pour la prévision de la dégradation des performances due à la forme de la givre. Le DRSM est beaucoup plus coûteux, car il contient plus de physique, fournissant des solutions naturellement instationnaires qui doivent être moyennées en temps. Les champs statistiques de premier et deuxième ordre du DRSM se comparent bien avec ceux de la ZDES, les deux indiquant que la tridimensionnalité géométrique des formes de givre devrait être prise en compte. De plus, le contenu instationnaire de la solution URANS DRSM est comparé à celui de la ZDES, montrant que le phénomène d'émission tourbillonnaire en aval de la recirculation peut également être capturé par le DRSM

Validity and reliability of the 3D motion analyzer in comparison with the Vicon device for biomechanical pedalling analysis

International audienceThe present work aimed to assess the validity and reliability of the 3D motion analyzer (Shimano Dynamics Lab, Sittard, Netherland) during laboratory cycling tests in comparison with the Vicon device (Vicon Motion Systems Ltd. Oxford, UK). Three cyclists were required to complete one laboratory cycling test at three different pedalling cadence and at a constant power output. Kinematic measurements were collected simultaneously from 3D motion analyzer and Vicon devices and performed five times for each pedalling cadence. The two systems showed a high reliability with excellent intraclass correlation coefficients for most kinematic variables. Moreover, this system was considered as valid by considering the error due to the initial markers placement. Experts and scientists should use the Vicon system for the purpose of research whereas the 3D motion analyzer could be used for bike fitting

The blind-test activity of the GOAHEAD project

This paper describes the blind-test CFD activity of the EU 6th Framework project GOAHEAD. This blind-test activity has been used to evaluate and assess the helicopter CFD codes which are today in use in Europe and to scrutinize the wind-tunnel test conditions with respect to the expected flow phenomena prior to the wind-tunnel test campaign. Results are presented for an isolated fuselage test case, a low-speed (pitch-up) test case, a cruise test case, a high-speed tail-shake test case and a highly-load rotor (dynamic-stall) test case

Exophthalmos, Diplopia, and Bilateral Eyelid Edema: Symptoms of Ocular Mastocytosis.

International audiencePURPOSE:Mastocytosis is characterized by clonal mast cell proliferation with accumulation within various organs and uncontrolled activation with excessive mast cell mediator release. Ocular manifestations have rarely been published. We describe a 63-year-old man with bilateral exophthalmos that led to the diagnosis of systemic mastocytosis.CASE REPORT:A patient presented with bilateral eyelid edema with exophthalmos associated with binocular diplopia. Ophthalmologic examination showed bilateral axial, symmetrical, and painless exophthalmos with eyelid edema, and limitation in elevation of the right eye. Visual acuity was normal. Orbital magnetic resonance imaging showed increased volume of both the superior and medial recti muscles and right inferior oblique muscle, and histopathological examination of orbital fat and muscle biopsies revealed an infiltration by mast cells. Serum tryptase was elevated. The patient also complained of a long history of pruritis and diffuse skin erythema that could be elicited with just mild pressure (Darier's sign). A bone marrow biopsy confirmed the infiltration of abnormal mast cells with a D816V mutation in the KIT gene. Treatment with cladribine was initiated and resulted in resolution of both ocular and systemic signs and symptoms that persisted without relapse 18 months after discontinuation. Ocular mastocytosis is a rare condition, which was previously reported to involve the conjunctiva, cornea, uvea, eyelid, orbit, and choroid. Cases of ocular mastocytosis can be classified into two main groups: mast cells tumors (mastocytomas) and ocular manifestations associated with systemic mastocytosis. Histological examination of ocular samples is rarely performed, and there are no standard criteria for the diagnosis of ocular mastocytosis. Our case emphasizes cladribine could represent an alternative treatment.CONCLUSIONS:Our case is the first published case of exophthalmos and eyelid edema associated with systemic mastocytosis confirmed by pathologic examination of periocular biopsies that was treated effectively with cladribine

Delayed hemolytic transfusion reaction in sickle cell disease patients: evidence of an emerging syndrome with suicidal red blood cell death

International audienceBackground: Delayed hemolytic transfusion reaction (DHTR) is a life-threatening complication in sickle cell disease (SCD) characterized by recurrence of disease complications, recipient red blood cell (RBC) destruction, and frequently no detectable antibody. Phosphatidylserine (PS) exposure signs suicidal RBC death or eryptosis and is involved in vasoocclusive crisis (VOC).Study design and methods: Transfusion was monitored in 48 SCD patients for up to 20 days. PS exposure was evaluated in vivo on patient RBCs (PS-RBCs) at five time points and in vitro after incubation of donor RBCs with pretransfusion plasma.Results: Three VOC patients displayed DHTR with recurrent SCD features and no detectable antibody in two cases. In vitro, PS-RBC percentage was significantly increased by incubating donor RBCs with pretransfusion plasma samples from DHTR patients with no detectable antibody. No such increase was observed with samples from other patients. This result indicates that donor RBCs may be damaged by the environment of SCD patients, increasing the physiologic clearance of apoptotic RBCs. In vivo, PS-RBC percentage increased in all three cases after destruction of transfused RBCs, indicating that DHTR induces PS-RBCs and, possibly, subsequent VOC and autologous RBC destruction.Conclusion: This study clearly demonstrates that DHTR can occur in the absence of detectable antibody. In these cases, a mechanism of excessive eryptosis is proposed