Rupture interlaminaire en mode I dans les composites unidirectionnels polypropylène/fibres de verre

Revue bibliographique : rupture interlaminaire dans les composites à matrice polymère -- Influences sur la ténacité des composites -- Méthodologie expérimentale -- Caractérisation microstructurale -- Observation microscopique -- Essais mécaniques -- Essai de rupture interlaminaire en quasi-statique -- Essai de rupture interlaminaire en fatigue -- Morphologie -- Performance mécanique : traction, flexion et cisaillement -- Rupture interlaminaire en quasi-statique -- Fractographie -- Rupture interlaminaire en fatigue

C57BL/6 and Swiss Webster Mice Display Differences in Mobility, Gliosis, Microcavity Formation and Lesion Volume After Severe Spinal Cord Injury

Spinal cord injuries (SCI) are neuropathologies causing enormous physical and emotional anguish as well as irreversibly disabilities with great socio/economic burdens to our society. The availability of multiple mouse strains is important for studying the underlying pathophysiological response after SCI. Although strain differences have been shown to directly affect spontaneous functional recovery following incomplete SCI, its influence after complete lesion of the spinal cord is unclear. To study the influence of mouse strain on recovery after severe SCI, we first carried out behavioral analyses up to 6 weeks following complete transection of the spinal cord in mice with two different genetic backgrounds namely, C57BL/6 and Swiss Webster. Using immunohistochemistry, we then analyzed glial cell reactivity not only at different time-points after injury but also at different distances from the lesion epicenter. Behavioral assessments using CatWalk™ and open field analyses revealed increased mobility (measured using average speed) and differential forelimb gross sensory response in Swiss Webster compared to C57BL/6 mice after complete transection of the spinal cord. Comprehensive histological assessment revealed elevated microglia/macrophage reactivity and a moderate increase in astrogliosis in Swiss Webster that was associated with reduced microcavity formation and reduced lesion volume after spinal cord transection compared to C57BL/6 mice. Our results thus suggest that increased mobility correlates with enhanced gliosis and better tissue protection after complete transection of the spinal cord

No widespread induction of cell death genes occurs in pure motoneurons in an amyotrophic lateral sclerosis mouse model

To identify candidate genes that may be involved in motoneuron degeneration, we combined laser capture microdissection with microarray technology. Gene expression in motoneurons was analyzed during the progression of the disease in transgenic SOD1G93A mice that develop motoneuron loss. Three major observations were made: first, there was only a small number of genes that were differentially expressed in motoneurons at a pre-symptomatic age (27 out of 34 000 transcripts). Secondly, there is an early specific up-regulation of the gene coding for the intermediate filament vimentin that is increased even further during disease progression. Using in situ hybridization and immunohistochemical analysis, we show that vimentin expression was not only elevated in motoneurons but that the protein formed inclusions in the motoneuron cytoplasm. Thirdly, a time-course analysis of the motoneurons at a symptomatic age (90 and 120 days) showed a modest de-regulation of only a few genes associated with cell death pathways; however, a massive up-regulation of genes involved in cell growth and/or maintenance was observed. This is the first description of the gene profile of SOD1G93A motoneurons during disease progression and unexpectedly, no widespread induction of cell death-associated genes was detected in motoneurons of SOD1G93A mic

Microglia Responses in Acute and Chronic Neurological Diseases: What Microglia-Specific Transcriptomic Studies Taught (and did Not Teach) Us

Over the last decade, microglia have been acknowledged to be key players in central nervous system (CNS) under both physiological and pathological conditions. They constantly survey the CNS environment and as immune cells, in pathological contexts, they provide the first host defense and orchestrate the immune response. It is well recognized that under pathological conditions microglia have both sequential and simultaneous, beneficial and detrimental effects. Cell-specific transcriptomics recently became popular in Neuroscience field allowing concurrent monitoring of the expression of numerous genes in a given cell population. Moreover, by comparing two or more conditions, these approaches permit to unbiasedly identify deregulated genes and pathways. A growing number of studies have thus investigated microglial transcriptome remodeling over the course of neuropathological conditions and highlighted the molecular diversity of microglial response to different diseases. In the present work, we restrict our review to microglia obtained directly from in vivo samples and not cell culture, and to studies using whole-genome strategies. We first critically review the different methods developed to decipher microglia transcriptome. In particular, we compare advantages and drawbacks of flow cytometry and laser microdissection to isolate pure microglia population as well as identification of deregulated microglial genes obtained via RNA sequencing (RNA-Seq) vs. microarrays approaches. Second, we summarize insights obtained from microglia transcriptomes in traumatic brain and spinal cord injuries, pain and more chronic neurological conditions including Amyotrophic lateral sclerosis (ALS), Alzheimer disease (AD) and Multiple sclerosis (MS). Transcriptomic responses of microglia in other non-neurodegenerative CNS disorders such as gliomas and sepsis are also addressed. Third, we present a comparison of the most activated pathways in each neuropathological condition using Gene ontology (GO) classification and highlight the diversity of microglia response to insults focusing on their pro- and anti-inflammatory signatures. Finally, we discuss the potential of the latest technological advances, in particular, single cell RNA-Seq to unravel the individual microglial response diversity in neuropathological contexts

Isolation of mineralizing Nestin+ Nkx6.1+ vascular muscular cells from the adult human spinal cord

<p>Abstract</p> <p>Background</p> <p>The adult central nervous system (CNS) contains different populations of immature cells that could possibly be used to repair brain and spinal cord lesions. The diversity and the properties of these cells in the human adult CNS remain to be fully explored. We previously isolated Nestin⁺Sox2⁺neural multipotential cells from the adult human spinal cord using the neurosphere method (i.e. non adherent conditions and defined medium).</p> <p>Results</p> <p>Here we report the isolation and long term propagation of another population of Nestin⁺cells from this tissue using adherent culture conditions and serum. QPCR and immunofluorescence indicated that these cells had mesenchymal features as evidenced by the expression of Snai2 and Twist1 and lack of expression of neural markers such as Sox2, Olig2 or GFAP. Indeed, these cells expressed markers typical of smooth muscle vascular cells such as Calponin, Caldesmone and Acta2 (Smooth muscle actin). These cells could not differentiate into chondrocytes, adipocytes, neuronal and glial cells, however they readily mineralized when placed in osteogenic conditions. Further characterization allowed us to identify the Nkx6.1 transcription factor as a marker for these cells. Nkx6.1 was expressed in vivo by CNS vascular muscular cells located in the parenchyma and the meninges.</p> <p>Conclusion</p> <p>Smooth muscle cells expressing Nestin and Nkx6.1 is the main cell population derived from culturing human spinal cord cells in adherent conditions with serum. Mineralization of these cells in vitro could represent a valuable model for studying calcifications of CNS vessels which are observed in pathological situations or as part of the normal aging. In addition, long term propagation of these cells will allow the study of their interaction with other CNS cells and their implication in scar formation during spinal cord injury.</p

Monitoring programme of antimicrobial resistance in sentinel bacteria isolated from intestinalflora of pigs and poultry 1999-2001

Un programme de surveillance des taux de résistance aux antibiotiques chez des bactéries indicatrices ( Escherichia coli et Enterococcus faecium) isolées de la flore intestinale du poulet de chair et du porc a été mis en place, en France, pour déterminer leurs évolutions en fonction du temps. Plusieurs antibiotiques représentatifs des classes d’antibiotiques utilisées comme médicaments vétérinaires ou comme facteurs de croissance ont été étudiés. Une évolution statistiquement significative du niveau de résistance à trois antibiotiques a été mis en évidence chez les souches d’ Enterococcus faecium isolées chez le poulet de chair. L’hypothèse d’égalité des niveaux de résistance entre les différentes années d’études n’a pas pu être rejetée pour les souches d' Enterococcus faecium isolées chez le porc. Une réduction statistiquement significative de la résistance chez les souches d' Escherichia coli est observée pour la streptomycine et le triméthoprime pour celles isolées du poulet de chair et pour la streptomycine et l’apramycine pour celles isolées du porc.A monitoring programme of antimicrobial resistance of sentinel bacteria (Escherichia coli and Enterococcus faecium) isolated from intestinal flora of poultry and pigs has been implemented to follow trends in France. Several antimicrobials representative of different antimicrobial families used as veterinary drugs and feed additives has been tested. A statistically significant variation between the different years has been observed for Enterococcus faecium strains isolated from poultry for resistance against three antimicrobials while the hypothesis of equality could not be rejected for pig strains. A statistically significant decrease of Escherichia coli resistance was observed in each animal species for two antimicrobials tested (streptomycin and trimethoprim in poultry, streptomycin and apramycin in pig)

Digital Technology To Support Organic Growers ? Mesclun: A Web App To Help Designing Complex Organic Vegetable Production

For organic vegetable growers, combining long rotations involving a high level of plant diversity with intercropping can bring economic and ecological benefits but often increase management complexity and workload. To support the decision making of farmers facing such challenges, the research-action objective of the MESCLUN programme is to develop a web application based on the innovative computer technologies of knowledge graphs and semantic web. In this French transdisciplinary project, we articulate methods and frameworks from different fields (agronomy, economy, design, knowledge and computer engineering) with expertise of agricultural practitioners (organic growers, advisors, teachers, organic farming students). Through an iterative and participatory approach based on co-innovation workshops in 4 contrasted regions of France, we design, develop and test web app prototypes to help farmers to appropriate systemic thinking, explore and assess their “own” solutions in the organisation of complex organic vegetables systems. We will present functionalities/interface of the first web app prototype. We will for example show how the web app can help growers to plan their crops in space and time considering contrasted fertility and plants health strategies as well as marketing requirements. We will also illustrate how different simulations can be assessed from a socio-economic perspective (workload and income). Based on those first results, we will examine the specificities, added value and blind spots of our web app compared to other decision making tools in the organic agricultural sector. To feed a more general debate, we will provide critical discussion points on the potentialities and limitations of innovative digital solutions to support decision making in complex organic farming systems

Bostonia. Volume 10

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

An Autoreactive Antibody from an SLE/HIV-1 Individual Broadly Neutralizes HIV-1

Broadly HIV-1–neutralizing antibodies (BnAbs) display one or more unusual traits, including a long heavy chain complementarity-determining region 3 (HCDR3), polyreactivity, and high levels of somatic mutations. These shared characteristics suggest that BnAb development might be limited by immune tolerance controls. It has been postulated that HIV-1–infected individuals with autoimmune disease and defective immune tolerance mechanisms may produce BnAbs more readily than those without autoimmune diseases. In this study, we identified an HIV-1–infected individual with SLE who exhibited controlled viral load (\u3c5,000 copies/ml) in the absence of controlling HLA phenotypes and developed plasma HIV-1 neutralization breadth. We collected memory B cells from this individual and isolated a BnAb, CH98, that targets the CD4 binding site (CD4bs) of HIV-1 envelope glycoprotein 120 (gp120). CH98 bound to human antigens including dsDNA, which is specifically associated with SLE. Anti-dsDNA reactivity was also present in the patient’s plasma. CH98 had a mutation frequency of 25% and 15% nt somatic mutations in the heavy and light chain variable domains, respectively, a long HCDR3, and a deletion in the light chain CDR1. The occurrence of anti-dsDNA reactivity by a HIV-1 CD4bs BnAb in an individual with SLE raises the possibility that some BnAbs and SLE-associated autoantibodies arise from similar pools of B cells