La construction de l’expérience

Les pionniers de la formation des adultes ont fait de l’expérience la spécificité de la formation de ce public (Knowles, 1973). Depuis, cette orientation s’est confirmée et généralisée aux formations à visée professionnelle telles que les formations par alternance. La prise en compte de l’expérience déborde aujourd’hui le cadre de la formation des adultes. Elle est en effet de plus en plus valorisée au sein de l’enseignement scolaire comme le montre la promotion des pratiques pédagogiques prô..

Plan d'expériences numérique pour l'analyse des conditions de contact en microformage

Les effets d'échelle en microformage peuvent être observés aussi bien sur l'écrouissage du matériau que dans les conditions de frottement à l'interface outil/matière. Ici nous proposons un plan d'expériences numérique basé sur des essais de compression de cylindre afin de mettre en évidence l'influence des propriétés géométriques de surface sur l'effort de compression. Les surfaces de l'outil et du cylindre ont été modélisées par un profil sinusoïdal. Ainsi, les cinq paramètres d'entrée pour le plan d'expériences numérique sont l'amplitude et la période du profil sinusoïdal pour l'outil et le cylindre ainsi que le déphasage entre les deux profils en contact. L'évolution de l'effort de compression est utilisée comme paramètre de sortie du plan d'expériences numérique. L'analyse des résultats du plan permet de mettre en évidence la sensibilité des paramètres tribologiques des surfaces vis-à-vis de l'effort de compression. Sur la base de ce plan d'expériences numérique, une modélisation plus réaliste des conditions de contact et frottement en microformage tenant compte des critères de rugosité peut être envisagée

Comportement des roches en température

International audienc

NG2-expressing glial precursor cells are a new potential oligodendroglioma cell initiating population in N-ethyl-N-nitrosourea-induced gliomagenesis.: Brain precursor cells and gliomas

International audienceGliomas are the most common primary brain tumor affecting human adults and remain a therapeutic challenge because cells of origin are still unknown. Here, we investigated the cellular origin of low-grade gliomas in a rat model based on transplacental exposure to N-ethyl-N-nitrosourea (ENU). Longitudinal magnetic resonance imaging coupled to immunohistological and immunocytochemical analyses were used to further characterize low-grade rat gliomas at different stages of evolution. We showed that early low-grade gliomas have characteristics of oligodendroglioma-like tumors and exclusively contain NG2-expressing slow dividing precursor cells, which express early markers of oligodendroglial lineage. These tumor-derived precursors failed to fully differentiate into oligodendrocytes and exhibited multipotential abilities in vitro. Moreover, a few glioma NG2+ cells are resistant to radiotherapy and may be responsible for tumor recurrence, frequently observed in humans. Overall, these findings suggest that transformed multipotent NG2 glial precursor cell may be a potential cell of origin in the genesis of rat ENU-induced oligodendroglioma-like tumors. This work may open up new perspectives for understanding biology of human gliomas

Le site du Carreau du Temple (Paris) entre “ marais ” et “ marécages ” : indices géoarchéologiques et paléo-environnementaux

Les fouilles du “ Carreau du Temple ”, effectuées en 2011, ont permis d’étudier une séquence pédo-sédimentaire préservée sous les vestiges d’une occupation qui débute au xiie s. avec le développement de l’Enclos du Temple. L’emplacement du site correspond à un domaine de transition géomorphologique entre une montille à faible relief (le quartier du Marais) et un paléochenal de la Seine qui ceinture la rive droite. La séquence de sol, qui correspond à un horizon organique homogène à l’échelle du site, a fait l’objet d’une étude paléo-environnementale (sédimentologie, micromorphologie, paléobotanique) afin de déterminer son origine et son mode de mise en place. Les principaux résultats indiquent que le site est dépourvu de marqueurs de milieu palustre, tandis que la séquence présente tous les indices d’une anthropisation intense liée à une activité agricole du Moyen Âge, d’abord céréalière puis essentiellement maraîchère. Ce résultat s’accorde avec les vestiges identifiés sur le site et confirme les observations pédo-sédimentaires faites en plusieurs endroits de la rive droite et en particulier dans le quartier du Marais. L’absence de marqueurs palustres relativise fortement l’image d’une rive droite insalubre et marécageuse, associée à une toponymie qui semble essentiellement hériter d’une occupation céréalière et maraîchère de ses sols.The excavations of the Carreau du Temple, Paris, France, undertaken in 2011, provided the opportunity to study a pedo-sedimentary sequence preserved in the ruins of an occupation that began in the twelfth century with the development of the “Enclos du Temple”. The site is located in an area of geomorphological transition between a relief characterised by shallow ancient dunes (the “Marais”, “swamp” in French) and a paleochannel of the right bank of the river Seine. The sediment sequence, which corresponds to a homogeneous organic horizon extending across the site, was the subject of a paleo-environmental study (sedimentology, micromorphology, paleobotany) aimed at determining both its origin and evolution. The principal results found no markers indicating a wetland environment; however, extensive evidence of intensive human activity related to agricultural practices from the Middle Ages was identified, including evidence for both cereal and more specifically, vegetable production. This result agrees with the archaeological remains identified at the site and confirms the pedo-sedimentary observations made in several places along the paleo-channel, and in particular in the Marais. The absence of wetland markers that would normally indicate a marshy right river bank calls into question the toponymy of the place - the Marais - which is a name usually associated with unsanitary, swampy conditions; the evidence found, in fact indicates that this was a zone of varied agricultural production

Usefulness of PKH fluorescent labelling to study leukemic cell proliferation with various cytostatic drugs or acetyl tetrapeptide – AcSDKP

BACKGROUND: PKH67 labelling was compared for classical proliferation assessment (using S phase evaluation) to analyse the cell proliferation of 29 AML patients treated or not with various drugs. Among these drugs, the effect of tetrapeptide AcSDKP or AcSDKP-NH2 on AML cells, stimulated or not by cytokines, was also evaluated in order to determine (i) if AcSDKP was able to inhibit blast cell proliferation as it inhibits haematopoietic progenitors (ii) if AcSDKP-NH2 was more stable than AcSDKP with FBS. METHODS: For PKH labeling, cells were suspended in Diluent C, and rapidly admixed with PKH67 solution at 20 μM PKH67. Staining was stopped by addition of FBS. RESULTS: A good correlation between PKH67 labelling and bromodeoxyuridine incorporation was obtained first with 6/9 patients for control cells, then for 11/17 AML patients treated with classical antileukemic drugs (among whom 4 were also treated with AcSDKP). The effect of AcSDKP was also studied on 7 patients. The discrepancy between both methods was essentially due to an accumulation of cells into different cycle phases measured by BrdUrd incorporation secondary to drug action and PKH67 labelling which measured the dynamic proliferation. This last method allows identifying resistant cells which still proliferate. AcSDKP or AcSDKP-NH2 induced a decrease of leukemic cell proliferation in 5/7 patients when cytokines were added (in order to stimulate proliferation) one day after tetrapeptide AcSDKP or AcSDKP-NH2. No effect on proliferation was noted when cytokines were added to AcSDKP-NH2. CONCLUSION: PKH67 labelling method is a powerful tool for cell proliferation assessment in patients with AML, even in cells treated by various drugs

Combined Liver-Kidney Transplantation With Preformed Anti-human Leukocyte Antigen Donor-Specific Antibodies

Introduction: the impact of preformed donor-specific anti-human leukocyte antigen (HLA) antibodies (pDSAs) after combined liver-kidney transplantation (CLKT) is still uncertain. Methods: we conducted a retrospective study in 8 European high-volume transplant centers and investigated the outcome of 166 consecutive CLKTs, including 46 patients with pDSAs. Results: patient survival was lower in those with pDSAs (5-year patient survival rate of 63% and 78% with or without pDSA, respectively; P = 0.04). The presence of pDSAs with a mean fluorescence intensity (MFI) ≥ 5000 (hazard ratio 4.96; 95% confidence interval: 2.3-10.9; P < 0.001) and the presence of 3 or more pDSAs (hazard ratio 6.5; 95% confidence interval: 2.5-18.8; P = 0.05) were independently associated with death. The death-censored liver graft survival was similar in patients with or without pDSAs. Kidney graft survival was comparable in both groups. (The 1- and 5-year death-censored graft survival rates were 91.6% and 79.5%, respectively, in patients with pDSAs and 93% and 88%, respectively, in the donor-specific antibody [DSA]-negative group, P = not significant). Despite a higher rate of kidney graft rejection in patients with pDSAs (5-year kidney graft survival rate without rejection of 87% and 97% with or without pDSAs, respectively; P = 0.04), kidney function did not statistically differ between both groups at 5 years post-transplantation (estimated glomerular filtration rate 45 ± 17 vs. 57 ± 29 ml/min per 1.73 m2, respectively, in patients with and without pDSAs). Five recipients with pDSAs (11.0%) experienced an antibody-mediated kidney rejection that led to graft loss in 1 patient. Conclusion: our results suggest that CLKT with pDSAs is associated with a lower patients' survival despite good recipients', liver and kidney grafts' outcome

Study of the economic impact of cryptosporidiosis in calves after implementing good practices to manage the disease on dairy farms in Belgium, France, and the Netherlands

Cryptosporidium spp. are widespread parasitic protozoans causing enteric infections in humans and animals. The parasites cause neonatal diarrhoea in calves, leading to a high mortality rate in the first 3 weeks. Losses are significant for farmers, but the cost of cryptosporidiosis remains poorly documented. In the absence of a vaccine, only preventive measures are available to farmers to combat the infection. This study, conducted between 2018 and 2021, aimed to evaluate the economic impact of Cryptosporidium spp. on European dairy farms and monitor changes in costs after implementing disease management measures. First, a field survey was carried out and questionnaires administered to 57 farmers in Belgium, France, and the Netherlands. The aim of the survey was to assess the losses associated with the occurrence of diarrhoea in calves aged between 3 days and 3 weeks. The economic impact of diarrhoea was calculated based on mortality losses, health expenditures, and additional labour costs. To refine the cost estimation specifically for Cryptosporidium spp., stool samples were collected from 10 calves per farm. The prevalence of Cryptosporidium spp. was determined, and the economic impact of diarrhoea was adjusted accordingly. The assumption was made that a certain percentage of costs was attributed to cryptosporidiosis based on the prevalence. These protocols were repeated at the end of the study to observe changes in costs. In the three years, the cost of diarrhoea for the 28 farms that stayed in the panel all along the study improved from €140 in 2018 to €106 on average per diarrhoeic calf in 2021. With a stable prevalence at 40%, the cost of cryptosporidiosis per infected calf decreased from €60.62 to €45.91 in Belgium, from €43.83 to €32.14 in France, and from €58.24 to €39.48 in the Netherlands. This represented an average of €15 saved per infected calf. The methodology employed in this study did not allow us to conclude that the improvement is strictly due to the implementation of preventive measures. However, with 11 million calves raised in the Interreg 2 Seas area covered by the study, it provided valuable insights into the economic burden of Cryptosporidium spp

Abdominal Surgery in Patients With Idiopathic Noncirrhotic Portal Hypertension: A Multicenter Retrospective Study

In patients with idiopathic noncirrhotic portal hypertension (INCPH), data on morbidity and mortality of abdominal surgery are scarce. We retrospectively analyzed the charts of patients with INCPH undergoing abdominal surgery within the Vascular Liver Disease Interest Group network. Forty‐four patients with biopsy‐proven INCPH were included. Twenty‐five (57%) patients had one or more extrahepatic conditions related to INCPH, and 16 (36%) had a history of ascites. Forty‐five procedures were performed, including 30 that were minor and 15 major. Nine (20%) patients had one or more Dindo‐Clavien grade ≥ 3 complication within 1 month after surgery. Sixteen (33%) patients had one or more portal hypertension–related complication within 3 months after surgery. Extrahepatic conditions related to INCPH (P = 0.03) and history of ascites (P = 0.02) were associated with portal hypertension–related complications within 3 months after surgery. Splenectomy was associated with development of portal vein thrombosis after surgery (P = 0.01). Four (9%) patients died within 6 months after surgery. Six‐month cumulative risk of death was higher in patients with serum creatinine ≥ 100 μmol/L at surgery (33% versus 0%, P < 0.001). An unfavorable outcome (i.e., either liver or surgical complication or death) occurred in 22 (50%) patients and was associated with the presence of extrahepatic conditions related to INCPH, history of ascites, and serum creatinine ≥ 100 μmol/L: 5% of the patients with none of these features had an unfavorable outcome versus 32% and 64% when one or two or more features were present, respectively. Portal decompression procedures prior to surgery (n = 10) were not associated with postoperative outcome. Conclusion: Patients with INCPH are at high risk of major surgical and portal hypertension–related complications when they harbor extrahepatic conditions related to INCPH, history of ascites, or increased serum creatinine