Kinetics of antigen cross-presentation assessed experimentally and by a model of the complete endomembrane system.

Dendritic cells (DCs) have a specialized endomembrane system capable of presenting exogenous antigens in the context of MHC class I (MHC-I) molecules. This process, named cross-presentation, is crucial to activate CD8+ T lymphocytes and initiate cytotoxic immune responses. In this report, we present an Agent-Based Model in combination with Ordinary Differential Equations with enough complexity to reproduce cross-presentation. The model embraces the secretory and endocytic pathways, in connection with the plasma membrane, the endoplasmic reticulum, and the cytosol. Key molecules required for cross-presentation were included as cargoes. In the simulations, the kinetics of MHC-I uptake and recycling, and cross-presentation accurately reproduced experimental values. The model proved to be a suitable tool to elaborate hypotheses and design experiments. In particular, the model predictions and the experimental results obtained indicate that the rate-limiting step in cross-presentation of soluble ovalbumin is MHC-I loading after proteasomal processing of the antigenic protein.

From cartoons to quantitative models in Golgi transport.

BACKGROUND: Cell biology is evolving to become a more formal and quantitative science. In particular, several mathematical models have been proposed to address Golgi self-organisation and protein and lipid transport. However, most scientific articles about the Golgi apparatus are still using static cartoons that miss the dynamism of this organelle. RESULTS: In this report, we show that schematic drawings of Golgi trafficking can be easily translated into an agent-based model using the Repast platform. The simulations generate an active interplay among cisternae and vesicles rendering quantitative predictions about Golgi stability and transport of soluble and membrane-associated cargoes. The models can incorporate complex networks of molecular interactions and chemical reactions by association with COPASI, a software that handles ordinary differential equations. CONCLUSIONS: The strategy described provides a simple, flexible and multiscale support to analyse Golgi transport. The simulations can be used to address issues directly linked to the mechanism of transport or as a way to incorporate the complexity of trafficking to other cellular processes that occur in dynamic organelles. SIGNIFICANCE: We show that the rules implicitly present in most schematic representations of intracellular trafficking can be used to build dynamic models with quantitative outputs that can be compared with experimental results.

Design and Implementation of a Robotic Software for the Assessment of Pain in Children.

Pain in child population is presented as a vital process which produces a variation in capacities and needs of care. That pain has an impact on the child's develpoment and therefore on his self-care agency acquisition. That is why the care provided to people with these characteristics are presented as a priority for the nursing professional. From a disciplinary framework, the nursing professional appears as a figue with knowledge for the development of new technological tools (such as robotics) to treat pain in children. In this way, a robotic system that incorporates a program for the assessment of pain in children has been designed using deductive methodology and guided by Software Requirements Specification ANSI/IEEE 830. Finally, this robotic system was implemented according to the construction phases of an Expert System.