A three-dimensional multi-agent-based model for the evolution of Chagas' disease.

A better understanding of Chagas' disease is important because the knowledge about the progression and the participation of the different types of cells in this disease are still lacking. To clarify this system, the kinetics of inflammatory cells and parasite nests was shown in an experiment. Using this experimental data, we have developed a three-dimensional multi-agent-based computational model for the evolution of Chagas' disease. Our model includes five different types of agents: inflammatory cell, fibrosis, cardiomyocyte, fibroblast, and Trypanosoma cruzi. Fibrosis is fixed and the other types of agents can move through the empty space. They move randomly by using the Moore neighborhood. This model reproduces the acute and chronic phases of Chagas' disease and the volume occupied by all different types of cells in the cardiac tissue.

Modularity map of the network of human cell differentiation.

Cell differentiation in multicellular organisms is a complex process whose mechanism can be understood by a reductionist approach, in which the individual processes that control the generation of different cell types are identified. Alternatively, a large-scale approach in search of different organizational features of the growth stages promises to reveal its modular global structure with the goal of discovering previously unknown relations between cell types. Here, we sort and analyze a large set of scattered data to construct the network of human cell differentiation (NHCD) based on cell types (nodes) and differentiation steps (links) from the fertilized egg to a developed human. We discover a dynamical law of critical branching that reveals a self-similar regularity in the modular organization of the network, and allows us to observe the network at different scales. The emerging picture clearly identifies clusters of cell types following a hierarchical organization, ranging from sub-modules to super-modules of specialized tissues and organs on varying scales. This discovery will allow one to treat the development of a particular cell function in the context of the complex network of human development as a whole. Our results point to an integrated large-scale view of the network of cell types systematically revealing ties between previously unrelated domains in organ functions.

Development of a two-dimensional agent-based model for chronic chagasic cardiomyopathy after stem cell transplantation.

MOTIVATION: A significant issue in stem cell therapy is to understand the role of this type of cell in the tissue regeneration. To explain this mechanism, an experimental study has quantified that the bone marrow cell transplantation decreases the number of inflammatory cells and reduces the fibrosis area in chagasic mice. Using this experimental data, we have developed an agent-based computational model to investigate the regeneration of the chronic chagasic cardiomyopathy after bone marrow stem cell transplantation. RESULTS: Our model includes six different types of agents: inflammatory cell, fibrosis area, cardiomyocyte, proinflammatory cytokine tumor necrosis factor-alpha, Trypanosoma cruzi parasite and bone marrow stem cell. This latter promotes apoptosis in inflammatory cells, reduction in the fibrosis area and can differentiate into cardiomyocyte. Proinflammatory cytokine tumor necrosis factor-alpha can increase the fibrosis area and T.cruzi can increase the number of inflammatory cells. Our results for both apoptosis of inflammatory cells and reduction in the fibrosis area were compared with experimental data. They suggest that the concentration pattern is the most important factor to characterize the kinetics of cardiac tissue regeneration after bone marrow stem cell transplantation. AVAILABILITY: The source code of our software is available online at www.vivas.ufba.br/bone/bone.zip .br Supplementaty information: Supplementary data are available at Bioinformatics online.

Associação entre condiloma acuminado e fístula anorretal em doentes HIV-positivos / Anorretal association between condilomata acuminata and fistula in sick people HIV-positives

A pandemia provocada pelo vírus da imunodeficiência humana (HIV) é um dos problemas de saúde pública mais discutidos na atualidade. Acredita-se que 30por cento dos doentes terão afecções anorretais durante a evolução dessa infecção. Os condilomas acuminados, as úlceras e as fístulas anais são as mais freqüentes, em especial naqueles que praticam sexo anal receptivo. Temos observado a concomitância entre condilomas acuminados e fístulas anais, o que nos induziu a avaliar a existência dessa associação e sua freqüência. Por isso, revisamos 218 prontuários de doentes de condilomas acuminados e/ou fístula anal operados entre junho de 1999 e fevereiro de 2003. Houve predominância do sexo masculino 197(90,3por cento) com média de idade de 31,5 anos. Realizamos ressecção de condilomas em 144 doentes, tratamento de fístula anal em 36 e os dois procedimentos em 38 outros. Durante a operação, encontramos condilomas no trajeto fistuloso de seis doentes. Como resultados, observamos a incidência de fístulas anais em 20,8por cento dos portadores de condilomas acuminados e 51,3por cento de condilomas naqueles com fístulas perianais. Sugerimos que as lesões provocadas pelo HPV devam ser pesquisadas nas fístulas anorretais, como essas necessitam diagnóstico na presença de condilomas nesse grupo de doentes.