20 NEW THERAPEUTIC STRATEGIES AND AGENTS WITH STRUCTURE MODIFYING POTENTIAL IN OSTEOARTHRITIS

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Boucle de ceinture en bronze doré (fin XIIIe - début XIVe siècle)

International audienceDécouverte fortuite de deux boucles de ceintures médiévales en Provence à Eyguières et Aix-en-Provence

Les composantes de l’entraînement à l’improvisation actives dans la gestion des imprévus en salle de classe du niveau secondaire

La gestion de classe est l’une des principales difficultés éprouvées par les enseignantes et enseignants novices. Cependant, avec le temps, ils développent une certaine assurance devant les imprévus, notamment en raison de leur capacité à improviser. La présente étude vise à identifier certaines composantes de l’entraînement à l’improvisation actives dans la gestion des imprévus en classe du secondaire. Les résultats montrent qu’un tel entraînement peut développer la vigilance et la rapidité d’exécution devant une situation non planifiée.Class management is one of the major difficulties that face inexperienced teachers. However, with time, they develop confidence towards unexpected events, in part because of their capacity to improvise. The study presented aims at identifying some components of an improvisation training active in the management of unexpected events in high-school level classroom. Results show that this kind of training can develop watchfulness and swiftness of action in the face of unplanned situations

The increased synthesis of inducible nitric oxide inhibits IL-1ra synthesis by human articular chondrocytes: possible role in osteoarthritic cartilage degradation

SummaryThe degradation of osteoarthritic (OA) cartilage is likely related to the synthesis and the release of catabolic factors by chondrocytes. Nitric oxide (NO) has recently been suggested as playing a role in cartilage degradation. Since NO production is largely dependent on stimulation by IL-1, its effects on factors regulating the IL-1 biological activity, such as IL-1ra, are of the utmost importance. This study examined and compared the level of NO production by normal and OA cartilage and chondrocytes, as well as studied the effect of IL-1-induced NO production on the synthesis and steady-state mRNA of interleukin-1 receptor antagonist (IL-1ra).The NO baseline production by normal cartilage explants was undetectable but inducible by rhIL-1β. OA cartilage spontaneously produced NO. About a two-fold increase in NO production was found in OA rhIL-1β-stimulated (0.5–100 units/ml) cartilage as compared with the similarly stimulated normal cartilage. On chondrocytes rhIL-1β-stimulation (0.5–100 units/ml) produced a dose-dependent enhancement of both NO production and IL-1ra synthesis. Treatment with 200 μm Ng-monomethyl-L-arginine (L-NMA), a well known NO synthase inhibitor, induced over 70% inhibition of the NO production and a marked increased IL-1ra synthesis (average of 84%) and expression (mRNA level). Inhibition of prostaglandin synthesis by indomethacin had no effect on both the NO production or the IL-1ra level.In the present study, we demonstrated the capacity of OA cartilage to produce a larger amount of NO than the normal controls, both in spontaneous and IL-1-stimulated conditions. These data support the notion that, in vivo, OA chondrocytes are stimulated by factors, possibly IL-1, which in turn may induce the expression of NO synthase, thus the synthesis of NO itself. Importantly, our results showed that the elevation of NO production may be an important factor in the pathophysiology of OA since it can reduce IL-1ra synthesis by chondrocytes. As such, an increased level of IL-1, associated with a decreased IL-1ra level, may be responsible for the stimulation of OA chondrocytes by this cytokine, leading to an enhancement of cartilage matrix degradation

L’érosion différentielle dans les reliefs de l’Estrie et de la Nouvelle-Angleterre, entre Montréal et le piedmont sud-est des White Mountains

Entre Montréal et Granby, dans une véritable plaine à inselbergs, ces derniers correspondent à des intrusions tantôt syénitiques, tantôt basiques : ils sont plus résistants que les calcaro-schistes cambro-ordoviciens. L'intrusion la plus orientale est celle du mont Mégantic, qui comporte un croissant syénitique enveloppant une bosse de granite. Les intrusions de granite dévonien de l'Estrie et du nord du Vermont sont souvent en creux, ce qui peut s'expliquer soit par leur composition granodioritique (alvéole d'Island Pond), soit par une intense microfissuration (alvéole de Scotstown). La position culminante des White Mountains paraît due (en grande partie) à l'érosion différentielle. Les séries de Littleton, où les unités schisteuses sont aussi résistantes que les éléments quartzitiques et gneissiques. dominent, au nord, les gneiss olivériens, dont la position déprimée est attribuable à leur fracturation, non suivie de recristallisation, et ailleurs, les granites de Bickford, pourtant relativement acides. En position culminante se placent également les syenites et les granites à hastingsite mésozoïques. Quant aux granites dits de Conway, tantôt ils sont troués par d'amples cuvettes, tantôt ils constituent des fiers monolithes limités par des diaclases espacées. C'est que ces roches sont très hétérogènes, tantôt blanches et acides, tantôt grises et riches en biotite et en hornblende, ainsi qu'en plagioclases. Au total, les roches occupant le sommet de l'échelle de dureté sont celles où les perthites et les microperthites constituent une trame continue. Pour les autres variétés de roches, le degré de microfissuration et la composition minéralogique jouent alternativement le rôle principal.Between Montréal and Granby, the studied profile cuts across a true erosion plain where inselbergs coincide with syenitic and basic intrusions more resistant than the Cambro-Ordovician calcareous shales and schists. Mount Mégantic, the most eastern intrusion consists of a syenitic crescent and a granitic boss. In the Eastern Townships and northern Vermont, Devonian granitic intrusions are often hollowed out into basins. This derives either from their granodioritic composition (Island Pond) or from severe microfissuration (Scotstown). The prominent position of the White Mountains seems to be due to selective erosion. The Littleton Series, where schistous units are as resistant as the quartzitic and gneissic elements, rise on their northern boundary above the oliverian gneisses. These were easily eroded since no recrystallization occurred after fracturing. Elsewhere, the Littleton Series rise above Bickford granites despite the rather acid composition of the latter. Mesozoic hastingsite syenites and granites also have a prominent position. As for the granites classified as Conway granites, they range from white and acid varieties to grey varieties with a high content of plagioclases, biotites and hornblende. This heterogeneity may explain the topographic contrast between huge basins and monoliths, the latter being limited by spaced joints. The rocks at the top of the hardness scale are those where the main components, perthites and microperthites, form the structural grain. As for the other types of rocks, the degree of microfissuration (determined after microscopic examination and measurement of the filtration rate of coloured water) and the mineralogical composition oalternately intervene as the main element.Zwischen Montréal und Granby uberquert das erforschte Profil eine echte Erosionsebene, wo lnselberge mit syenetischen und basischen lntrusionen zusammenfallen, die widerstandsfâhiger als die Cambro-Ordovician Kalkâr Schalen und Schiefer sind. In der Estrie und im nôrd-lichen Vermont, sind devoniasniche Graniti intrusionen oft zu Becken ausgehôlt. Das kommt entweder von ihrer granodioritischen Zusammensetzung (Island Pond) Oder von hâftiger Mikrospaltung (Scotstown) her. Die hervorstehende Stellung der White Mountains scheint hauptsâchlich, aber nicht ausschliesslich, von selektiver Erosion zu stammen. Die Littleton Series, wo schieferhaltige Einheiten aus noch unbekannten Grunden, ebenso widerstandsfàhig wie die Quartzund Gneisselemente sind, erheben sich an ihrer nôrdlichen Grenze uber die oliveranischen Gneisse. Die wurden leicht erodiert weil es nach der Frakturation keine Rekristalisation gab. Anderswo erheben sich die Littleton Series uber Bickford Granite, trotz deren ziemlich saurer Beschaffenheit. Diese Mannigfaltigkeit kann vielleich den topographischen Kontrast zwischen grossen Becken und Monolithen erklâren, letztere findet man hauptsâchlich in durch Fugen begrenzten Randstellungen. Das Gestein am Gipfel der Hârteskala, hat als Hauptkomponenten Bethite und Mikroperthite, die, die strukturelle Kôrnung bilden. Fur die anderen Gesteinstypen kommen der Grad der Mikrospaltung (bestimmt durch mikroskopische Prufung und Messung der Filtrationsgeschwindigkeit von gefarbtem Wasser) und die mineralogische Zusammensetzung abwechselnd las Hauptelement vor

The ephrin-B2/EphB4 system is required in musculoskeletal development and protects the articulation during osteoarthritis: a research highlight

Ephrin ligands and their Eph receptors have been implicated in the control of extracellular matrix of some tissues. Although ephrin-B2 and its specific receptor EphB4 were found to be involved in postembryonic control of bone homeostasis, their roles were unclear in musculoskeletal growth and development as well as in osteoarthritis pathology. The role of this ephrin system in musculoskeletal growth and development was delineated in vivo using a cartilage-specific ephrin-B2 knockout mouse model. Its role in osteoarthritis in vivo was explored in mice using a bone-specific overexpression of EphB4 in which osteoarthritis was induced, and in vitro in human osteoarthritic subchondral bone osteoblasts and chondrocytes. In vivo, ephrin-B2 demonstrated to be essential for normal long bone growth and development and its absence in cartilage led to knee and hip osteoarthritis features in aged mice. In vitro data showed that the ephrin-B2-induced EphB4 receptor positively impacted the abnormal metabolism of both osteoarthritic subchondral bone osteoblasts and chondrocytes. The bone?specific EphB4 overexpression in mice validated the in vitro data in that it had beneficial effects not only on the osteoarthritic subchondral bone but also on the cartilage and synovial membrane, and further substantiated the hypothesis that by prophylactically protecting the subchondral bone, the genesis of osteoarthritis could be, at least in part, inhibited. In the context of identifying new candidates targeting osteoarthritis progression, this ephrin system is extremely attractive as a potential novel therapeutic avenue, as therapies having a more global articular approach may prove to be the most successful to arrest or slow the progression of this disease