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AP-2 proteins are a family of developmentally-regulated transcription factors. They are encoded by five different genes (α, β, γ, δ, and ε) but they share a common structure. AP-2 plays relevant roles in growth, differentiation, and adhesion by controlling the transcription of specific genes. Evidence shows that the AP-2 genes are involved in tumorigenesis and for instance, they act as tumor suppressors in melanomas and mammary carcinomas. Here we investigated the function of the AP-2α protein in cancer formation and progression focusing on apoptosis and migration.We introduced AP-2α-specific siRNA (as oligos or in retroviruses) in HeLa or MCF-7 human tumor cells and obtained a pronounced down-modulation of AP-2α mRNA and protein levels. In these cells, we observed a significant reduction of chemotherapy-induced apoptosis, migration, and motility and an increase in adhesion suggesting a major role of AP-2α during cancer treatment and progression (migration and invasion). We have data suggesting that migration is, at least in part, regulated by secreted factors. By performing a whole genome microarray analysis of the tumor cells expressing AP-2α siRNA, we identified several AP-2α -regulated genes involved in apoptosis and migration such as FAST kinase, osteopontin, caspase 9, members of the TNF family, laminin alpha 1, collagen type XII, alpha 1, and adam. [ABSTRACT FROM AUTHOR]

DNA microarrays are small solid supports on the surface of which DNA probes for thousands of genes have been orderly arrayed. Hybridization of labeled RNA from tissues or tumors allows evaluation of the relative amount of any specific mRNA present in the samples, depicting its gene expression profile. During development and progression of breast cancers, specific genetic programs are activated, which can be assayed on DNA microarrays. Studies performed so far show that the gene expression profile of a tumor defines its biology, its invasive and metastatic potential, and its responsiveness to treatments. Classification of breast cancer by expression profiling appears a very powerful approach, outperforming all commonly used methods of classification. However, much work has to be done before microarray will give robust information for clinical decisions and become routine practice. [ABSTRACT FROM AUTHOR]

In many situations of engineering and applied mathematics interest we are confronted with heat and mass transfer problems in granular medium, as in the grains drying processes and in small load nuclear reactors safety, where the spheres are fuel elements. In the literature we have found several models that try to describe these two processes. Most of the models found in the literature are empiric or semi-empiric and valid, therefore, for a quite limited range of the involved parameters. In this work we present a mathematical model based on the Navier-Stokes equations in three dimensions that describe the hot air flow going through the granular middle. We consider the grains in the form of small spheres inside a chamber. During the air passage in the grains middle occurs heat and water mass transfer between the spheres and the air. The heat transfer in the air occurs by convection and conduction processes, while the water mass (as vapor) in the air, is transferred by the convection and the diffusion processes. The heat and mass transfer between the air and the grains is considered in the sources terms of the energy and mass conservation equations for the grains and the air. Those terms are modeled obeying the Fourier's and Fick's laws, respectively. Our objective is to evaluate the dimensionless parameters influence in the heat and mass transfer processes, as well as to establish the values of that parameters for which the model is valid. Among the dimensionless parameters analyzed, we have the Reynolds, the Schmidt, the Prandtl and the Eckert numbers. Numerical tests, using the Gauss-Seidel central finite difference scheme, are carried out for non dimensional parameters ranging from Re = 200 - 2000, Sc = 0.7 - 0.9, Pr = 0.7 - 0.9, Ec = 10−5 -10−4. The results will contribute to obtain a better understanding of the parameters influence during the drying process of a granular medium. [ABSTRACT FROM AUTHOR]

The improvement of combustor devices is very important especially for aeronautical applications; combustors or burners are mechanical equipments where the combustion takes place. New technologies, including mixture and reaction, instability, low cost and emission are helping the development of numerical codes employed in combustion problems. But, when the burners are improved, unexpected problems can appear. The field of combustion can be divided into non-premixed and premixed combustion. The majority applications of technical interest are classified as non premixed and turbulent. To model non premixed flames it is necessary a good understanding of the combustion process and of turbulent mixing because the reaction take place when the fuel and the oxidizer mix in a molecular level. In combustion problems there is a strong coupling among transport (heat transfer, molecular diffusion, convection, turbulent transport....) chemistry and fluid dynamics: it is a multidisciplinary topic of research. Moreover, combustion models may turn very complex: the complete mechanism of methane combustion has been identified as having more than 300 elementary reactions and over 30 species. The complete reaction mechanism of iso-octane oxidation includes 3600 elementary reactions among 860 chemical species. Due to computational resource limitations to perform Direct Numerical Simulation (DNS), for moderate to high Reynolds values, Large-Eddy Simulation (LES) seems to be a good alternative. LES turns attractive since only the sub-grid scales and chemical reactions need to be modeled; the large scales are fully resolved. The LES equations are closed by modeling the stress tensor with an eddy viscosity. Therefore, the application of LES requires appropriate sub-grid scale models, fast computers and accurate and robust methods. The aim of this work is the numerical solution of mixing and reacting flows inside a combustor. The model considers the overall, single step, irreversible reaction between two species, being the reaction rate governed by the Arrhenius law. Numerical tests, based on the finite difference explicit Runge-Kutta five-stage scheme, for third order time and fourth order space approximations, are carried out for Reynolds 10000, Damköhler 300, Zel'dovich 10, Heat Release 10 and Schmidt and Prandtl both equal to 0.9 and the results contribute to obtain a better understanding of the mixture-reaction behavior for the reacting flow inside a combustor. [ABSTRACT FROM AUTHOR]