Aspiration of biological viscoelastic drops

Spherical cellular aggregates are in vitro systems to study the physical and biophysical properties of tissues. We present a novel approach to characterize the mechanical properties of cellular aggregates using micropipette aspiration technique. We observe an aspiration in two distinct regimes, a fast elastic deformation followed by a viscous flow. We develop a model based on this viscoelastic behavior to deduce the surface tension, viscosity, and elastic modulus. A major result is the increase of the surface tension with the applied force, interpreted as an effect of cellular mechanosensing.Comment: 4 pages, 4 figures

Functional Annotation of the Ophiostoma novo-ulmi Genome: Insights into the Phytopathogenicity of the Fungal Agent of Dutch Elm Disease

International audienceThe ascomycete fungus Ophiostoma novo-ulmi is responsible for the pandemic of Dutch elm disease that has been ravaging Europe and North America for 50 years. We proceeded to annotate the genome of the O. novo-ulmi strain H327 that was sequenced in 2012. The 31.784-Mb nuclear genome (50.1% GC) is organized into 8 chromosomes containing a total of 8,640 protein-coding genes that we validated with RNA sequencing analysis. Approximately 53% of these genes have their closest match to Grosmannia clavigera kw1407, followed by 36% in other close Sordariomycetes, 5% in other Pezizomycotina, and surprisingly few (5%) orphans. A relatively small portion (~3.4%) of the genome is occupied by repeat sequences; however, the mechanism of repeat-induced point mutation appears active in this genome. Approximately 76% of the proteins could be assigned functions using Gene Ontology analysis; we identified 311 carbohydrate-active enzymes, 48 cytochrome P450s, and 1,731 proteins potentially involved in pathogen– host interaction, along with 7 clusters of fungal secondary metabolites. Complementary mating-type locus sequencing, mating tests, and culturing in the presence of elm terpenes were conducted. Our analysis identified a specific genetic arsenal impacting the sexual and vegetative growth, phytopathogenicity, and signaling/plant–defense–degradation relationship between O. novo-ulmi and its elm host and insect vectors. Introduction During the last centuries, increased movements of people and goods across countries and continents have favored the emergence and global spread of plant pathogens, insect pests, and invasive weeds which have substantially altered the landscape of several parts of the world. One well-documented example is Dutch elm disease (DED), the most destructive disease of elms. It has been estimated that over 1 billion mature elms were killed by two successive pandemics since the early 1900s (Paoletti et al. 2005). The first pandemic, which prompted initial investigations by Dutch scientists shortly after the First World War (Holmes and Heybroek 1990), was caused by the ascomycete fungus Ophiostoma ulmi (Buisman) Nannf. As it spread relentlessly over Western Europe and, a few decade

Integrin/Fak/Src-mediated regulation of cell survival and anoikis in human intestinal epithelial crypt cells: selective engagement and roles of PI3-K isoform complexes

In human intestinal epithelial crypt (HIEC) cells, the PI3-K/Akt-1 pathway is crucial for the promotion of cell survival and suppression of anoikis. Class I PI3-K consists of a complex formed by a catalytic (C) and regulatory (R) subunit. Three R (p85α, β, and p55γ) and four C (p110α, β, γ and δ) isoforms are known. Herein, we analyzed the expression of PI3-K isoforms in HIEC cells and determined their roles in cell survival, as well as in the β1 integrin/Fak/Src-mediated suppression of anoikis. We report that: (1) the predominant PI3-K complexes expressed by HIEC cells are p110α/p85β and p110α/p55γ; (2) the inhibition and/or siRNA-mediated expression silencing of p110α, but not that of p110β, γ or δ, results in Akt-1 down-activation and consequent apoptosis; (3) the expression silencing of p85β or p55γ, but not that of p85α, likewise induces Akt-1 down-activation and apoptosis; however, the impact of a loss of p55γ on both Akt-1 activation and cell survival is significantly greater than that from the loss of p85β; and (4) both the p110α/p85β and p110α/p55γ complexes are engaged by β1 integrin/Fak/Src signaling; however, the engagement of p110α/p85β is primarily Src-dependent, whereas that of p110α/p55γ is primarily Fak-dependent (but Src-independent). Hence, HIEC cells selectively express PI3-K isoform complexes, translating into distinct roles in Akt-1 activation and cell survival, as well as in a selective engagement by Fak and/or Src within the context of β1 integrin/Fak/Src-mediated suppression of anoikis

Improved image contrast with mangafodipir trisodium (MnDPDP) during MR-guided percutaneous cryosurgery of the liver

The present study was undertaken to measure the gain observed in the liver-to-tumor contrast of perioperative images when using mangafodipir trisodium, a liver-specific contrast agent, during percutaneous cryosurgery of the liver performed under the guidance of magnetic resonance images. Retrospective quantitative analyses of MR images were performed on eleven patients having a total of 30 liver tumors treated by MR-guided percutaneous cryosurgery. An initial group of four patients were treated with no contrast agent, and was compared with a second group of 7 patients who received an intravenous injection of 5 mumol/kg of mangafodipir for their cryosurgery. The percutaneous cryosurgery was monitored under the near-real-time-imaging mode of a 0.5T open-configuration MRI system using a T-1-weighted Gradient-recalled echo pulse sequence. A significant improvement in the liver-to-tumor contrast-to-noise ratio was observed with mangafodipir (p < 0.05, paired t test) in 0.5T preoperative images. Along with the stability of the mangafodipir contrast enhancement during the entire cryosurgical procedure, the resulting gain in contrast allowed for better visualizing the presence of residual untreated tumor margins at the periphery of the cryosurgery iceball directly from perioperative images acquired with patients under narcosis. Consequently, it not only became easier for the interventionalist to determine the need for an additional cryoprobe to increase the size of the iceball during the procedure, but also to decide on the appropriate end point of the cryosurgery

Safety and immunogenicity of double-dose versus standard-dose hepatitis B revaccination in non-responding adults with HIV-1 (ANRS HB04 B-BOOST): a multicentre, open-label, randomised controlled trial

Equipe CHU UB (EA) Pôle MERS CT3 Hors Enjeu ANRS HB04 B-BOOST study group : Hugues Aumaitre (Centre Hospitalier Marechal Joff re, Perpignan, France); Jean-Luc Berger (Centre Hospitalier Universitaire de Reims– Hopital Robert Debre, Reims, France); Alain Devidas (Hopital Gilles de Corbeil–Centre Hospitalier Sud Francilien, Corbeil Essonne, France); Sophie Abgrall (Centre Hospitalier Universitaire Avicenne, Avicenne, France); Olivier Patey (Centre Hospitalier Intercommunal de Villeneuve St Georges, Villeneuve Saint Georges, France); Marie-Christine Drobacheff Thiebaut (Centre Hospitalier Universitaire de Besancon–Hopital Saint Jacques, Besancon, France); Frederic Lucht (Centre Hospitalier Universitaire de St Etienne–Hopital Nord, Saint Etienne, France); Bruno Hoen (Centre Hospitalier Universitaire de Besancon–Hopital Saint Jacques, Besancon, France); Caroline Lascoux-Combe (Hopital Saint Louis, Paris, France); Olivier Lortholary (Hopital Necker, Paris, France); Veronique Delcey (Hopital Lariboisiere, Paris, France); Pierre De Truchis (Hopital Raymond–Poincare, Garches, France); Vincent Jeantils (Hopital Jean Verdier, Bondy, France); Daniel Vittecoq (Le Kremlin Bicetre, France); Laurence Slama (Hopital Tenon, Paris, France); David Zucman (Hopital Foch, Suresnes, France); Yves Levy (Hopital Henri Mondor, Creteil, France); Christine Katlama (Hopital Pitie Salpetriere, Paris, France); Anne Simon (Hopital Pitie Salpetriere, Paris, France); Pierre-Marie Girard (Hopital Saint Antoine, Paris, France); Jean-Michel Molina (CISIH, Hopital Saint Louis, Paris, France); Sandrine Pierre-Francois (Centre Hospitalier Universitaire de Fort de France–Hopital Pierre Zobda Quitman, Fort de France, France); Jean-Marie Chennebault (Centre Hospitalier Universitaire d’Angers–Hopital de l’Hotel Dieu, Angers, France); Rozenn Le Berre (Centre Hospitalier Universitaire de Brest– Hopital de La Cavale Blanche, Brest, France); Didier Neau (Hopital Pellegrin, Bordeaux, France); Jean Michel Livrozet (Hopital Edouard Herriot, Lyon, France); Isabelle Poizot-Martin (Hopital Sainte Marguerite, Marseille, France); Sophie Matheron (Hopital Bichat, Paris, France); Jacques Reynes (Hopital Gui De Chauliac, Montpellier, France); Eric Billaud (Centre Hospitalier Universitaire de Nantes–Hotel Dieu, Nantes, France); Philippe Perre (Centre Hospitalier Departemental de Vendee–Les Oudairies, La Roche sur Yon, France); Jacques Durand (Centre Hospitalier Universitaire de Nice–Hopital de l’Archet, Nice, France); Eric Rosenthal (Centre Hospitalier Universitaire de Nice–Hopital de l’Archet, Nice, France); Cedric Arvieux (Centre Hospitalier Universitaire de Rennes–Hopital Pontchaillou, Rennes, France); Lize Cuzin (Centre Hospitalier Universitaire de Toulouse–Hopital Purpan, Toulouse, France); Renaud Verdon (Centre Hospitalier Universitaire Cote de Nacre, Caen, France); Pascale Leclercq (Centre Hospitalier Universitaire de Grenoble–Hopital Albert Michallon, Grenoble, France); Faiza Ajana (Hopital Gustave Dron, Tourcoing, France); Thierry May (Centre Hospitalier Universitaire Nancy–Hopital Brabois, Nancy, France); Yasmine Debab (Centre Hospitalier Universitaire de Rouen–Hopital Charles Nicolle, Rouen, France); Agnes Lefort (Hopital Beaujon, Clichy, France); Isabelle Delacroix (Centre Hospitalier Intercommunal de Creteil, Creteil, France); Genevieve Beck-Wirth (Hopital du Moenchberg, Mulhouse, France); Yves Poinsignon (Centre Hospitalier Bretagne-Atlantique Vannes, Vannes, France); Thierry Prazuck (Centre Hospitalier Regional–Hopital de La Source, Orleans, France); Patrick Philibert (Hopital Europeen Marseille, Marseille, France); Jean-Paul Viard (Hopital Hotel Dieu, Paris, France).International audienceBACKGROUND:Revaccination with double-dose hepatitis B vaccine has been recommended in HIV-infected patients who do not respond to standard vaccination, but has not yet been assessed. We aimed to compare the safety and immunogenicity of a reinforced hepatitis B revaccination protocol with the standard revaccination schedule in HIV-infected patients not responding to primary vaccination.METHODS:We did this multicentre, open-label, randomised controlled trial, at 53 centres in France. HIV-infected adults (aged ≥18 years), with CD4 counts of 200 cells per μL or more and no response to a previous hepatitis B vaccination or a 20 μg booster dose, were randomly assigned (1:1), according to a computer-generated randomisation list with permuted blocks (block sizes of two to six), to receive either standard-dose (20 μg) or double-dose (40 μg) recombinant hepatitis B vaccine at weeks 0, 4, and 24. Randomisation was stratified by baseline CD4 count (200-349 vs ≥350 cells per μL). Patients and treating physicians were not masked to treatment allocation, but the randomisation list was concealed from the investigators who assigned participants to the vaccination groups. The primary endpoint was the proportion of responders, defined as patients with hepatitis B surface antibody (anti-HBs) titres of 10 mIU/mL or more, at week 28. We did analysis by modified intention to treat. This study is registered with ClinicalTrials.gov, number NCT00670839.FINDINGS:Between May 19, 2008, and May 8, 2011, 178 participants were randomly assigned to the standard-dose group (n=90) or the double-dose group (n=88), of whom 176 (98%) participants were included in the primary efficacy analysis. At week 28, we recorded a response in 60 patients (67%, 95% CI 57-77) in the standard-dose group versus 64 patients (74%, 63-82) in the double-dose group (p=0·334). Except for more frequent local reactions in the double-dose group than the standard-dose group (13 [15%] vs four [4%] patients; p=0·020), there was no difference in safety between groups.INTERPRETATION:In adults with HIV-1 who have not responded to previous hepatitis B vaccination, double-dose revaccination did not achieve a higher response rate than did revaccination with standard single-dose regimen. However, the safety profile was similar between treatment groups. Our results should be assessed in future studies before double-dose vaccine can be considered for the standard of care of vaccine non-responders.FUNDING:French National Institute for Medical Research-French National Agency for Research on AIDS and Viral Hepatitis

Littératie numérique et didactique des langues et des cultures

Parmi les différentes déclinaisons de la littératie, les recherches sur la littératie numérique ont contribué à faire évoluer les conceptions de la lecture, de l’écriture et, plus largement, de la communication. Ces travaux enrichissent l’appareil conceptuel des didacticiens des langues et commencent à trouver des retombées concrètes dans le domaine de l’enseignement-apprentissage. L’objet de ce numéro est de proposer des éclairages sur le lien entre littératie numérique et didactique des langues (quel que soit le statut de celles‑ci : L1, L2, etc.). Les études qui y sont regroupées portent sur des pratiques de littératie numérique en dehors et dans le contexte des classes et interrogent le lien entre développement de compétences en langues et littératie numérique. Le numéro, en plus d’aborder l’histoire des chassés-croisés entre littératie et didactique des langues, questionne la notion de littératie numérique, évoque les liens entre cette notion et celle de citoyenneté numérique, et propose des éléments de réflexions pour penser l’articulation entre pratiques de littératie numérique et pratiques de classe. L’ensemble permet d’ouvrir des perspectives d’avenir autant pour la recherche que pour la pratique en didactique des langues. REMERCIEMENTS Ont été sollicités pour évaluer les articles de ce numéro (dossier thématique + rubrique Varia) : Brahim Azaoui, Jean-Paul Bronckart, Cristelle Cavalla, Maud Ciekanski, Stéphane Colognesi, Charlotte Dejean, Isabelle Delcambre, Marie-Pierre Dufour, Cédric Fluckiger, Anne-Laure Foucher, Marie Cécile Guernier, Thérèse Jeanneret, François Mangenot, Agnès Millet, Chiara Ramero, Christian Surcouf, Denyse Toffoli, Marcello Vitali-Rosati, Ciara Wigham