| 1. |
- Magalhães, Ana, et al.
(author)
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Fut2-null mice display an altered glycosylation profile and impaired BabA-mediated Helicobacter pylori adhesion to gastric mucosa
- 2009
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In: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 19:12, s. 1525-1536
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Journal article (peer-reviewed)abstract
- Glycoconjugates expressed on gastric mucosa play a crucial role in host-pathogen interactions. The FUT2 enzyme catalyzes the addition of terminal alpha(1,2)fucose residues, producing the H type 1 structure expressed on the surface of epithelial cells and in mucosal secretions of secretor individuals. Inactivating mutations in the human FUT2 gene are associated with reduced susceptibility to Helicobacter pylori infection. H. pylori infects over half the world's population and causes diverse gastric lesions, from gastritis to gastric cancer. H. pylori adhesion constitutes a crucial step in the establishment of a successful infection. The BabA adhesin binds the Le(b) and H type 1 structures expressed on gastric mucins, while SabA binds to sialylated carbohydrates mediating the adherence to inflamed gastric mucosa. In this study, we have used an animal model of nonsecretors, Fut2-null mice, to characterize the glycosylation profile and evaluate the effect of the observed glycan expression modifications in the process of H. pylori adhesion. We have demonstrated expression of terminal difucosylated glycan structures in C57Bl/6 mice gastric mucosa and that Fut2-null mice showed marked alteration in gastric mucosa glycosylation, characterized by diminished expression of alpha(1,2)fucosylated structures as indicated by lectin and antibody staining and further confirmed by mass spectrometry analysis. This altered glycosylation profile was further confirmed by the absence of Fucalpha(1,2)-dependent binding of calicivirus virus-like particles. Finally, using a panel of H. pylori strains, with different adhesin expression profiles, we have demonstated an impairment of BabA-dependent adhesion of H. pylori to Fut2-null mice gastric mucosa, whereas SabA-mediated binding was not affected.
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| 2. |
- Otero, Nuno, 1969-, et al.
(author)
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BeLife : a simulation tool to support learning about photosynthesis
- 2005
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In: Proceedings of the 2005 conference on Towards Sustainable and Scalable Educational Innovations Informed by the Learning Sciences. - : IOS Press. - 1586035738 ; , s. 857-860
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Conference paper (peer-reviewed)abstract
- This paper describes the design and implementation of a multi-agent based interactive learning environment called BeLife. BeLife intends to support learning scientific concepts related to photosynthesis, plant growth and greenhouse management. One of the main objectives of the development of BeLife is to create an interactive learning environment that combines modelling and simulation learning tasks in one tool. We present the initial findings from a case study conducted in a classroom setting with high school students. The study evaluated the usability of a high fidelity prototype of the system. We elaborate on these results and discuss the adequacy of BeLife envisioned functionalities and its applicability.
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| 3. |
- Prada, Rui, et al.
(author)
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The User in the Group : Evaluating the Effects of Autonomous Group Dynamics
- 2007
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In: Proceedings of the international conference on Advances in computer entertainment technology. - New York, NY, USA : ACM Digital Library. - 9781595936400 ; , s. 25-32
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Conference paper (peer-reviewed)abstract
- Autonomous characters in virtual environments have the potential to improve the interaction experience of users, specially, their social experience. This effect is driven by the interactions occurring between users and the autonomous characters, that in certain scenarios can be in the context of a group. However, for these group interactions to be successful, it is not enough to assure that the autonomous characters behave in a coherent manner from an individual perspective, but it is also necessary that they exhibit behaviours that are coherent with the group composition, context and structure. Therefore, we have developed a model to support believable group dynamics of autonomous characters, inspired in theories developed in human social psychological sciences. This model defines the knowledge that each individual should build about the others and about the group it belongs, and how this knowledge drives their interactions in the group. The model was integrated in the mind of the autonomous characters that perform a collaborative task, in a computer game, with a human player. The game was used in a study that showed that players’ interaction experience was better when interaction with groups that followed our model, namely, regarding trust and social identification with the group. In addition, we found some evidence that players prefer playing in groups that have higher level of conflict.
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