Optimization of culture conditions for porcine corneal endothelial cells

Purpose : To optimize the growth condition of porcine corneal endothelial cells (PCEC), we evaluated the effect of coculturing with a feeder layer (irradiated 3T3 fibroblasts) with the addition of various exogenous factors, such as epidermal growth factor (EGF), nerve growth factor (NGF), bovine pituitary extract (BPE), ascorbic acid, and chondroitin sulfate, on cell proliferation, size, and morphology. Methods : PCEC cultures were seeded at an initial cell density of 400 cells/cm2 in the presence or absence of 20,000 murine-irradiated 3T3 fibroblast/cm2 in the classic media Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 20% fetal bovine serum (FBS). Mean cell size and bromodeoxyuridine incorporation was assessed at various passages. Growth-promoting factors were studies by seeding PCEC at 8,000 cells/cm2 in DMEM with 20% FBS or Opti-MEM I supplemented with 4% FBS and one of the following additives: EGF (0.5, 5, 25 ng/ml), NGF (5, 20, 50 ng/ml), BPE (25, 50, 100, 200 μg/ml), ascorbic acid (10, 20, 40 μg/ml) and chondroitin sulfate (0.03, 0.08, 1.6%), alone or in combination. Cell number, size and morphology of PCEC were assessed on different cell populations. Each experiment was repeated at least twice in three sets. In some cases, cell cultures were maintained after confluence to observe post-confluence changes in cell morphology. Results : Co-cultures of PCEC grown in DMEM 20% FBS with a 3T3 feeder layer improved the preservation of small polygonal cell shape. EGF, NGF, and chondroitin sulfate did not induce proliferation above basal level nor did these additives help maintain a small size. However, chondroitin sulfate did help preserve a good morphology. BPE and ascorbic acid had dose-dependent effects on proliferation. The combination of BPE, chondroitin sulfate, and ascorbic acid significantly increased cell numbers above those achieved with serum alone. No noticeable changes were observed when PCEC were cocultured with a 3T3 feeder layer in the final selected medium. Conclusions : Improvements have been made for the culture of PCEC. The final selected medium consistently allowed the growth of a contact-inhibited cell monolayer of small, polygonal-shaped cells

Learning Mechanics and Game Mechanics Under the Perspective of Self-Determination Theory to Foster Motivation in Digital Game Based Learning

Background: Using digital games for educational purposes has been associated with higher levels of motivation among learners of different educational levels. However, the underlying psychological factors involved in digital game based learning (DGBL) have been rarely analyzed considering self-determination theory (SDT, Ryan \& Deci, 2000b); the relation of SDT with the flow experience (Csikszentmihalyi, 1990) has neither been evaluated in the context of DGBL

Habitat filtering and niche differentiation jointly explain species relative abundance within grassland communities along fertility and disturbance gradients

1.Deterministic niche-based processes have been proposed to explain species relative abundance within communities but lead to different predictions: habitat-filtering (HF) predicts dominant species to exhibit similar traits while niche differentiation (ND) requires that species have dissimilar traits to coexist. 2.Using a multiple trait-based approach, we evaluated the relative roles of HF and ND in determining species abundances in productive grasslands. Four dimensions of the functional niche of 12 co-occurring grass species were identified using 28 plant functional traits. Using this description of the species niche, we investigated patterns of functional similarity and dissimilarity and linked them to abundance in randomly-assembled six-species communities submitted to fertilization/disturbance treatments. 3.Our results suggest that HF and ND jointly determined species abundance by acting on contrasting niche dimensions. The effect of HF decreased relatively to ND with increasing disturbance and decreasing fertilization. Dominant species exhibited similar traits in communities whereas dissimilarity favored the coexistence of rare species with dominants by decreasing inter-specific competition. This stabilizing effect on diversity was suggested by a negative relationship between species overyielding and relative abundance. 4.We discuss the importance of considering independent dimensions of functional niche to better understand species abundance and coexistence within communities

Sociétés de la connaissance

Le terme « sociétés de la connaissance » est apparu dans les années 1990. Il caractérise une période où chaque pays, à son rythme, voit le savoir, l'information et la communication prendre une place centrale. Parler des fractures et des évolutions et non de révolution, c'est souligner la force des changements sociaux en cours, des rapports de force et des inégalités qui en découlent. Ce livre envisage le rôle des interactions entre technologies de la communication et mondialisation du savoir. À ce titre, il met en garde contre toute vision trop idéaliste d'une société de la connaissance et propose au lecteur un panorama de la richesse et des enjeux de ce mouvement en marche

Renouveler l’aménagement et l’urbanisme

En Amérique du Nord et en Europe, le renouvellement des pratiques d’aménagement du territoire et d’urbanisme s’impose comme une question centrale des études urbaines et régionales depuis plus d’une décennie. Ce questionnement s’articule autour de trois axes : la planification territoriale, le débat public et le développement durable. À partir de recherches inédites portant sur des expériences c­oncrètes menées au Québec et en France, cet ouvrage propose un regard nouveau sur les retombées et les effets du débat public sur la planification territoriale, l’aménagement du territoire et l’urbanisme. Il fait ainsi le bilan des implications du double impératif de la participation des citoyens et de la prise en compte du concept de développement durable, et offre des réponses à des questions cruciales pour l’avenir des pratiques d’aménagement du territoire et d’urbanisme en contexte urbain et métropolitain

HCV NS5B polymerase-bound conformation of a soluble sulfonamide inhibitor by 2D tranferred NOESY

HCV NS5B RNA-dependent RNA polymerase (NS5B) is essential for viral replication and is therefore considered a target for antiviral drug development. From our ongoing screening e\ufb00ort in the search for new anti-HCV agents, a novel inhibitor 1 with low lM activity against the HCV NS5B polymerase was identi\ufb01ed. SAR analysis indicated the optimal substitution pattern required for activity, for example, carboxylic acid group at 2-position of thiophene ring. We describe the steps taken to identify and solve the bioactive conformation of derivative 6 through the use of the transferred NOE method (trNOE).NRC publication: Ye