Sur la maîtrise de l’information

Porto Rico, territoire à double culture hispanique et américaine, la conférence a abordé cette année la question de la maîtrise de l’information pour les publics multiculturels des bibliothèques publiques et universitaires. Quelle importance représente la maîtrise de l’information pour les populations étrangères, immigrantes ou indigènes ? Quels sont leurs besoins et quel rôle peuvent tenir les bibliothèques

Les bibliothécaires et les outils du Web 2.0

Réfléchir à comment adapter, appréhender et intégrer les outils du Web 2.0 est un enjeu majeur pour les bibliothécaires. La profession doit développer de nouvelles pistes de travail pour mieux interagir avec les usagers du Web et maîtriser les contenus en ligne

The chondro-osseous continuum: is it possible to unlock the potential assigned within?

Endochondral ossification (EO), by which long bones of the axial skeleton form, is a tightly regulated process involving chondrocyte maturation with successive stages of proliferation, maturation, and hypertrophy, accompanied by cartilage matrix synthesis, calcification, and angiogenesis, followed by osteoblast-mediated ossification. This developmental sequence reappears during fracture repair and in osteoarthritic etiopathology. These similarities suggest that EO, and the cells involved, are of great clinical importance for bone regeneration as it could provide novel targeted approaches to increase specific signaling to promote fracture healing, and if regulated appropriately in the treatment of osteoarthritis. The long-held accepted dogma states that hypertrophic chondrocytes are terminally differentiated and will eventually undergo apoptosis. In this mini review, we will explore recent evidence from experiments that revisit the idea that hypertrophic chondrocytes have pluripotent capacity and may instead transdifferentiate into a specific sub-population of osteoblast cells. There are multiple lines of evidence, including our own, showing that local, selective alterations in cartilage extracellular matrix (ECM) remodeling also indelibly alter bone quality. This would be consistent with the hypothesis that osteoblast behavior in long bones is regulated by a combination of their lineage origins and the epigenetic effects of chondrocyte-derived ECM which they encounter during their recruitment. Further exploration of these processes could help to unlock potential novel targets for bone repair and regeneration and in the treatment of osteoarthritis

Critical illness-related bone loss is associated with osteoclastic and angiogenic abnormalities

Critically ill patients are at increased risk of fractures during rehabilitation, and can experience impaired healing of traumatic and surgical bone fractures. In addition, markers of bone resorption are markedly increased in critically ill patients, while markers of bone formation are decreased. In the current study, we have directly investigated the effect of critical illness on bone metabolism and repair. In a human in vitro model of critical illness, Fluorescence-activated cell sorting (FACS) analysis revealed an increase in circulating CD14+/CD11b+ osteoclast precursors in critically ill patient peripheral blood compared to healthy controls. In addition, the formation of osteoclasts was increased in patient peripheral blood mononuclear cell (PBMC) cultures compared to healthy controls, both in the presence and absence of osteoclastogenic factors receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Culturing PBMCs with 10% critically ill patient serum further increased osteoclast formation and activity in patient PBMCs only, and neutralization studies revealed that immunoglobulin G (IgG) antibody signaling through the immunoreceptor Fc receptor common γ chain III (FcRγIII) played an important role. When analyzing bone formation, no differences in osteogenic differentiation were observed using human periosteal-derived cells (hPDCs) treated with patient serum in vitro, but a decrease in the expression of vascular endothelial growth factor receptor 1 (VEGF-R1) suggested impaired vascularization. This was confirmed using serum-treated hPDCs implanted onto calcium phosphate scaffolds in a murine in vivo model of bone formation, where decreased vascularization and increased osteoclast activity led to a decrease in bone formation in scaffolds with patient serum-treated hPDCs. Together, these findings may help to define novel therapeutic targets to prevent bone loss and optimize fracture healing in critically ill patients

The Role of Galectin-1 and Galectin-3 in the Mucosal Immune Response to Citrobacter rodentium Infection

Despite their abundance at gastrointestinal sites, little is known about the role of galectins in gut immune responses. We have therefore investigated the Citrobacter rodentium model of colonic infection and inflammation in Galectin-1 or Galectin-3 null mice. Gal-3 null mice showed a slight delay in colonisation after inoculation with C. rodentium and a slight delay in resolution of infection, associated with delayed T cell, macrophage and dendritic cell infiltration into the gut mucosa. However, Gal-1 null mice also demonstrated reduced T cell and macrophage responses to infection. Despite the reduced T cell and macrophage response in Gal-1 null mice, there was no effect on C. rodentium infection kinetics and pathology. Overall, Gal-1 and Gal-3 play only a minor role in immunity to a gut bacterial pathogen

Site Specific Effects of Zoledronic Acid during Tibial and Mandibular Fracture Repair

Numerous factors can affect skeletal regeneration, including the extent of bone injury, mechanical loading, inflammation and exogenous molecules. Bisphosphonates are anticatabolic agents that have been widely used to treat a variety of metabolic bone diseases. Zoledronate (ZA), a nitrogen-containing bisphosphonate (N-BP), is the most potent bisphosphonate among the clinically approved bisphosphonates. Cases of bisphosphonate-induced osteonecrosis of the jaw have been reported in patients receiving long term N-BP treatment. Yet, osteonecrosis does not occur in long bones. The aim of this study was to compare the effects of zoledronate on long bone and cranial bone regeneration using a previously established model of non-stabilized tibial fractures and a new model of mandibular fracture repair. Contrary to tibial fractures, which heal mainly through endochondral ossification, mandibular fractures healed via endochondral and intramembranous ossification with a lesser degree of endochondral ossification compared to tibial fractures. In the tibia, ZA reduced callus and cartilage formation during the early stages of repair. In parallel, we found a delay in cartilage hypertrophy and a decrease in angiogenesis during the soft callus phase of repair. During later stages of repair, ZA delayed callus, cartilage and bone remodeling. In the mandible, ZA delayed callus, cartilage and bone remodeling in correlation with a decrease in osteoclast number during the soft and hard callus phases of repair. These results reveal a more profound impact of ZA on cartilage and bone remodeling in the mandible compared to the tibia. This may predispose mandible bone to adverse effects of ZA in disease conditions. These results also imply that therapeutic effects of ZA may need to be optimized using time and dose-specific treatments in cranial versus long bones

American Society for Bone and Mineral Research-Orthopaedic Research Society Joint Task Force Report on Cell-Based Therapies.

Cell-based therapies, defined here as the delivery of cells in vivo to treat disease, have recently gained increasing public attention as a potentially promising approach to restore structure and function to musculoskeletal tissues. Although cell-based therapy has the potential to improve the treatment of disorders of the musculoskeletal system, there is also the possibility of misuse and misrepresentation of the efficacy of such treatments. The medical literature contains anecdotal reports and research studies, along with web-based marketing and patient testimonials supporting cell-based therapy. Both the American Society for Bone and Mineral Research (ASBMR) and the Orthopaedic Research Society (ORS) are committed to ensuring that the potential of cell-based therapies is realized through rigorous, reproducible, and clinically meaningful scientific discovery. The two organizations convened a multidisciplinary and international Task Force composed of physicians, surgeons, and scientists who are recognized experts in the development and use of cell-based therapies. The Task Force was charged with defining the state-of-the art in cell-based therapies and identifying the gaps in knowledge and methodologies that should guide the research agenda. The efforts of this Task Force are designed to provide researchers and clinicians with a better understanding of the current state of the science and research needed to advance the study and use of cell-based therapies for skeletal tissues. The design and implementation of rigorous, thorough protocols will be critical to leveraging these innovative treatments and optimizing clinical and functional patient outcomes. In addition to providing specific recommendations and ethical considerations for preclinical and clinical investigations, this report concludes with an outline to address knowledge gaps in how to determine the cell autonomous and nonautonomous effects of a donor population used for bone regeneration. © 2019 American Society for Bone and Mineral Research