Assesment of potential swelling of Pressurized Water Reactor internals The GONDOLE experiment in Osiris reactor

International audienc

Amyotrophic lateral sclerosis transcriptomics reveals immunological effects of low-dose interleukin-2

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease causing upper and lower motor neuron loss and currently no effective disease-modifying treatment is available. A pathological feature of this disease is neuroinflammation, a mechanism which involves both CNS-resident and peripheral immune system cells. Regulatory T-cells are immune-suppressive agents known to be dramatically and progressively decreased in patients with amyotrophic lateral sclerosis. Low-dose interleukin-2 promotes regulatory T-cell expansion and was proposed as an immune-modulatory strategy for this disease. A randomized placebo-controlled pilot phase-II clinical trial called Immuno-Modulation in Amyotrophic Lateral Sclerosis was carried out to test safety and activity of low-dose interleukin-2 in 36 amyotrophic lateral sclerosis patients (NCT02059759). Participants were randomized to 1MIU, 2MIU-low-dose interleukin-2 or placebo and underwent one injection daily for 5 days every 28 days for three cycles. In this report, we describe the results of microarray gene expression profiling of trial participants' leukocyte population. We identified a dose-dependent increase in regulatory T-cell markers at the end of the treatment period. Longitudinal analysis revealed an alteration and inhibition of inflammatory pathways occurring promptly at the end of the first treatment cycle. These responses are less pronounced following the end of the third treatment cycle, although an activation of immune-regulatory pathways, involving regulatory T-cells and T helper 2 cells, was evident only after the last cycle. This indicates a cumulative effect of repeated low-dose interleukin-2 administration on regulatory T-cells. Our analysis suggested the existence of inter-individual variation amongst trial participants and we therefore classified patients into low, moderate and high-regulatory T-cell-responders. NanoString profiling revealed substantial baseline differences between participant immunological transcript expression profiles with the least responsive patients showing a more inflammatory-prone phenotype at the beginning of the trial. Finally, we identified two genes in which pre-treatment expression levels correlated with the magnitude of drug responsiveness. Therefore, we proposed a two-biomarker based regression model able to predict patient regulatory T-cell-response to low-dose interleukin-2. These findings and the application of this methodology could be particularly relevant for future precision medicine approaches to treat amyotrophic lateral sclerosis

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

Amyotrophic lateral sclerosis transcriptomics reveals immunological effects of low-dose interleukin-2

Amyotrophic lateral sclerosis is a fatal neurodegenerative disease causing upper and lower motor neuron loss and currently no effective disease-modifying treatment is available. A pathological feature of this disease is neuroinflammation, a mechanism which involves both CNS-resident and peripheral immune system cells. Regulatory T-cells are immune-suppressive agents known to be dramatically and progressively decreased in patients with ALS. Low-dose interleukin-2 promotes regulatory T-cell expansion and was proposed as an immune-modulatory strategy for this disease. A randomized placebo-controlled pilot phase-II clinical trial called Immuno-Modulation in Amyotrophic Lateral Sclerosis (IMODALS) was carried out to test safety and activity of low-dose interleukin-2 in 36 amyotrophic lateral sclerosis patients (NCT02059759). Participants were randomized to 1MIU, 2MIU-low-dose interleukin-2 or placebo and underwent one injection daily for five days every twenty-eight days for three cycles. In this report, we describe the results of microarray gene expression profiling of trial participants' leukocyte population. We identified a dose-dependent increase in regulatory T-cell markers at the end of the treatment period. Longitudinal analysis revealed an alteration and inhibition of inflammatory pathways occurring promptly at the end of the first treatment cycle. These responses are less pronounced following the end of the third treatment cycle, although an activation of immune-regulatory pathways, involving regulatory T-cells and T helper 2 cells, was evident only after the last cycle. This indicates a cumulative effect of repeated low-dose interleukin-2 administration on regulatory T-cells. Our analysis suggested the existence of inter-individual variation amongst trial participants and we therefore classified patients into low, moderate and high-Treg-responders. NanoString profiling revealed substantial baseline differences between participant immunological transcript expression profiles with the least responsive patients showing a more inflammatory-prone phenotype at the beginning of the trial. Finally, we identified two genes in which pre-treatment expression levels correlated with the magnitude of drug responsiveness. Therefore, we proposed a two-biomarker based regression model able to predict patient Treg-response to low-dose interleukin-2. These findings and the application of this methodology could be particularly relevant for future precision medicine approaches to treat amyotrophic lateral sclerosis

A new MRI rating scale for progressive supranuclear palsy and multiple system atrophy: validity and reliability

AIM To evaluate a standardised MRI acquisition protocol and a new image rating scale for disease severity in patients with progressive supranuclear palsy (PSP) and multiple systems atrophy (MSA) in a large multicentre study. METHODS The MRI protocol consisted of two-dimensional sagittal and axial T1, axial PD, and axial and coronal T2 weighted acquisitions. The 32 item ordinal scale evaluated abnormalities within the basal ganglia and posterior fossa, blind to diagnosis. Among 760 patients in the study population (PSP = 362, MSA = 398), 627 had per protocol images (PSP = 297, MSA = 330). Intra-rater (n = 60) and inter-rater (n = 555) reliability were assessed through Cohen's statistic, and scale structure through principal component analysis (PCA) (n = 441). Internal consistency and reliability were checked. Discriminant and predictive validity of extracted factors and total scores were tested for disease severity as per clinical diagnosis. RESULTS Intra-rater and inter-rater reliability were acceptable for 25 (78%) of the items scored (≥ 0.41). PCA revealed four meaningful clusters of covarying parameters (factor (F) F1: brainstem and cerebellum; F2: midbrain; F3: putamen; F4: other basal ganglia) with good to excellent internal consistency (Cronbach α 0.75-0.93) and moderate to excellent reliability (intraclass coefficient: F1: 0.92; F2: 0.79; F3: 0.71; F4: 0.49). The total score significantly discriminated for disease severity or diagnosis; factorial scores differentially discriminated for disease severity according to diagnosis (PSP: F1-F2; MSA: F2-F3). The total score was significantly related to survival in PSP (p<0.0007) or MSA (p<0.0005), indicating good predictive validity. CONCLUSIONS The scale is suitable for use in the context of multicentre studies and can reliably and consistently measure MRI abnormalities in PSP and MSA. Clinical Trial Registration Number The study protocol was filed in the open clinical trial registry (http://www.clinicaltrials.gov) with ID No NCT00211224

Irradiation damage in nuclear graphite at the atomic scale

International audienc

Microstructural evolution of graphite under irradiation large scale molecular dynamics simulations

International audienceGraphite response to irradiations has been widely studied in the past because of its importance for nuclear engineering. Despite this fact, the very details of the underlying mechanisms that drive its response to irradiation are still under debate and several scenarios are available [1,2,3]. With molecular dynamics simulations using empirical potentials, we investigate in this paper the microstructural evolution under irradiation of bulk graphite (or HOPG) and polycrystalline graphite with a microstructure similar to nuclear graphite. Both primary damages and dose effects are considered and analyzed. Primary damage was investigated by displacement cascades. While mainly point defects only survive in graphite single crystal, the nanoporosity of polycristalline graphite modifies the nature of the irradiation damage.Dose effect was subsequently explored with the Frenkel pair accumulations method in graphite single crystal. Before amorphisation, we show that graphite single crystal follows a three stages evolution characterized by (1) an increase of point defects (2) a wrinkling and pinning of the graphene planes at small amorphous pockets and (3) an amorphisation by percolation of the small amorphous pockets. Although each of these three stages have already been proposed [2,3], their chronology is evidenced in the present simulations [4]. The relevancy of results and interpretation is largely supported by the similarity between calculated TEM images from simulation configurations and real TEM images obtained experimentally. References1. K. Niwase, Phil. Mag. Lett. 82 (2002) 401.2. M.I. Heggie, I. Suarez-Martinez, C. Davidson, and G. Haffenden, J. Nucl. Mater. 413 (2011) 150.3. B.J. Marsden, and G.N. Hall, in Comprehensive Nuclear Materials, chap. 4.11 (2012) 325.4. A. Chartier, L. Van Brutzel, B. Pannier, and P. Baranek, Carbon 91 (2015) 395

Irradiation neutronique du graphite a basse temperature cas du reacteur G1

National audienceDans le cœur des réacteurs de type Uranium Naturel Graphite Gaz (UNGG), du graphite était utilisé en tant que modérateur et réflecteur de neutrons. Ce matériau irradié durant le fonctionnement de ces réacteurs constituera une part importante des déchets nucléaires après les opérations de démantèlement. Ils contiennent notamment plusieurs radionucléides « dimensionnants » pour la gestion à long terme de ces déchets dont le 3H, le 14C et le 36Cl. Les objectifs des études de caractérisation des graphites nucléaires irradiés sont principalement de comprendre et de quantifier les évolutions du graphite après le passage en réacteur en fonction des paramètres de fonctionnement. Ces données sont particulièrement utiles à des études de modélisation de l'irradiation neutronique du graphite. Par ailleurs, ces études peuvent également aider à la compréhension des phénomènes de migration en condition de stockage des radionucléides actuellement présents dans les déchets de graphite. Le réacteur G1 du Commissariat à l'Energie Atomique (CEA) de Marcoule fût le premier réacteur de la filière UNGG. Construit en 1955, ce dernier a été exploité entre janvier 1956 et septembre 1968. Une particularité de ce réacteur était que le caloporteur utilisé était de l'air à température ambiante. Celui-ci était injecté à partir d'une fente médiane à l'empilement graphite du réacteur. La température de fonctionnement y était donc moins élevée (20 - 230°C) que dans les autres réacteurs UNGG. Par ailleurs, dix-huit opérations de recuit ont été réalisées pour dissiper l'énergie Wigner accumulée dans le graphite au cours de la vie du réacteur. De par ses conditions particulières de fonctionnement (basse température, recuits hors irradiation), il est intéressant d'étudier l'impact de l'irradiation neutronique sur le graphite nucléaire dans ce réacteur. Ainsi, les évolutions de structure et de nanostructure ont été étudiées par microspectrométrie Raman et Microscopie Electronique à Transmission (MET). En termes de résultat, (1) les échantillons prélevés dans le réacteur G1 sont relativement très impactés aux échelles étudiées par l’irradiation neutronique notamment en raison de la basse température de fonctionnement du réacteur et (2) la distribution des défauts d’irradiation n'est pas identique à ce qui a été observé sur les échantillons des réacteurs précédemment étudiés [1]. La température d’irradiation étant le principal changement, quelques interprétations seront proposées quant à la contribution de ce paramètre sur les évolutions de l'organisation multi-échelle du graphite lors du passage en réacteur. [1]J. Pageot et al., Carbon 105 2016, 77-89

Lithospheric imaging from teleseismic data by frequency-domain elastic full-waveform tomography

International audienc