Transferência de Aprendizado para Redes Bayesianas com Aplicação em Predição de Falha de Discos Rígidos

Predizer falhas em Discos Rígidos é muito importante para evitar perda de dados e custos adicionais. Logo, um esforço pode ser observado para encontrar métodos adequados de predição de falhas. Apesar dos resultados encorajantes alcançados por vários métodos, um aspecto notado é a falta de dados disponíveis para construir modelos confiáveis. Transferência de Aprendizado oferece uma alternativa válida, uma vez que pode ser usada para transferir conhecimento de modelos de Disco com muitos dados para Discos com menos dados. Neste trabalho, avaliamos estratégias de Transferência de Aprendizado para esta tarefa. Além disso propomos uma estratégia para construir fontes de informação baseadas no agrupamento de modelos de disco parecidos. Resultados mostraram que todos os cenários testados de transferência melhoram a performance dos métodos de predição, principalmente para Discos com muito poucos dados

Effect of oxygen on multidrug resistance in the first trimester human placenta

Introduction: The multidrug resistance proteins, P-glycoprotein (P-gp, encoded by the ABCB1 gene) and breast cancer resistance protein (BCRP, encoded by ABCG2) are highly expressed in the first trimester placenta. These transporters protect the fetus from exposure to maternally derived toxins and xenobiotics. Since oxygen is a regulator of multidrug resistance in various tissues, we hypothesized that changes in oxygen tension alter placental ABCB1/P-gp and ABCG2/BCRP expression in the first trimester. Methods: Placental specimens were collected from first (n=7), second (n=5) and term pregnancies (n=5). First trimester placental villous explants were incubated (24 or 48h) in different oxygen tension (3-20%). ABCB1, ABCG2 and VEGFA mRNA expression levels were assessed by RT-PCR and protein was localized by IHC. Results: ABCB1 is expressed most highly in the first trimester placenta (p<0.05), whereas ABCG2 expression does not change significantly over pregnancy. P-gp and BCRP staining is present in the syncytiotrophoblast and in cytotrophoblasts. ABCG2 mRNA is increased in hyperoxic (20%) conditions after 48h (p<0.05). In contrast, hypoxia (3%) did not change ABCB1 mRNA expression but significantly increased VEGFA mRNA (p<0.05). Hypoxia resulted in increased BCRP staining in cytotrophoblasts and in the microvillous membrane of the syncytium. Whereas, hypoxia resulted in increased P-gp staining in proliferating cytotrophoblasts. Conclusion: We conclude that placental multidrug resistance expression, specifically ABCG2, is regulated by oxygen tension in the first trimester. It is possible that changes in placental oxygen supply are capable of altering fetal drug exposure especially during early pregnancy.This study was funded by the Canadian Institutes for Health Research (grant: FRN-57746; to S.G.M. and W.G.)

MAPSkew: Metaheuristic Approaches for Partitioning Skew in MapReduce

MapReduce is a parallel computing model in which a large dataset is split into smaller parts and executed on multiple machines. Due to its simplicity, MapReduce has been widely used in various applications domains. MapReduce can significantly reduce the processing time of a large amount of data by dividing the dataset into smaller parts and processing them in parallel in multiple machines. However, when data are not uniformly distributed, we have the so called partitioning skew, where the allocation of tasks to machines becomes unbalanced, either by the distribution function splitting the dataset unevenly or because a part of the data is more complex and requires greater computational effort. To solve this problem, we propose an approach based on metaheuristics. For evaluating purposes, three metaheuristics were implemented: Simulated Annealing, Local Beam Search and Stochastic Beam Search. Our experimental evaluation, using a MapReduce implementation of the Bron-Kerbosch Clique Algorithm, shows that the proposed method can find good partitionings while better balancing data among machines

R.M.C.: FramePersist: An object persistence framework for mobile device applications

Traditional requirements for persistence layers do not consider limitations of the development platforms available for mobile devices. In order to facilitate the development of applications, which need to store data, for mobile devices, these traditional requirements are reevaluated in this paper and a framework for object persistence is proposed. This framework, called FramePersist, is constructed based on the concept of object serialization and allows to persist and to search objects efficiently. Mapping rules of objects for persistence are presented together with a case study using the Symbian OS native file systems. 1

Transferência de Aprendizado para Redes Bayesianas com Aplicação em Predição de Falha de Discos Rígidos

Predizer falhas em Discos Rígidos é muito importante para evitar perda de dados e custos adicionais. Logo, um esforço pode ser observado para encontrar métodos adequados de predição de falhas. Apesar dos resultados encorajantes alcançados por vários métodos, um aspecto notado é a falta de dados disponíveis para construir modelos confiáveis. Transferência de Aprendizado oferece uma alternativa válida, uma vez que pode ser usada para transferir conhecimento de modelos de Disco com muitos dados para Discos com menos dados. Neste trabalho, avaliamos estratégias de Transferência de Aprendizado para esta tarefa. Além disso propomos uma estratégia para construir fontes de informação baseadas no agrupamento de modelos de disco parecidos. Resultados mostraram que todos os cenários testados de transferência melhoram a performance dos métodos de predição, principalmente para Discos com muito poucos dados

Chorioamnionitis Induces a Specific Signature of Placental ABC Transporters Associated with an Increase of miR-331-5p in the Human Preterm Placenta

Background/Aims: The ATP-binding cassette (ABC) transporters mediate drug biodisposition and immunological responses in the placental barrier. In vitro infective challenges alter expression of specific placental ABC transporters. We hypothesized that chorioamnionitis induces a distinct pattern of ABC transporter expression. Methods: Gene expression of 50 ABC transporters was assessed using TaqMan® Human ABC Transporter Array, in preterm human placentas without (PTD; n=6) or with histological chorioamnionitis (PTDC; n=6). Validation was performed using qPCR, immunohistochemistry and Western blot. MicroRNAs known to regulate P-glycoprotein (P-gp) were examined by qPCR. Results: Up-regulation of ABCB9, ABCC2 and ABCF2 mRNA was detected in chorioamnionitis (p&#x3c;0.05), whereas placental ABCB1 (P-gp; p=0.051) and ABCG2 (breast cancer resistance protein-BCRP) mRNA levels (p=0.055) approached near significant up-regulation. In most cases, the magnitude of the effect significantly correlated to the severity of inflammation. Upon validation, increased placental ABCB1 and ABCG2 mRNA levels (p&#x3c;0.05) were observed. At the level of immunohistochemistry, while BCRP was increased (p&#x3c;0.05), P-gp staining intensity was significantly decreased (p&#x3c;0.05) in PTDC. miR-331-5p, involved in P-gp suppression, was upregulated in PTDC (p&#x3c;0.01) and correlated to the grade of chorioamnionitis (p&#x3c;0.01). Conclusions: Alterations in the expression of ABC transporters will likely lead to modified transport of clinically relevant compounds at the inflamed placenta. A better understanding of the potential role of these transporters in the events surrounding PTD may also enable new strategies to be developed for prevention and treatment of PTD

Down-regulation of the placental BCRP/ABCG2 transporter in response to hypoxia signaling

INTRODUCTION: The BCRP/ABCG2 efflux transporter protects the developing fetus by limiting the transplacental transfer of drugs and chemicals and prevents the apoptosis of trophoblasts. The purpose of this study was to determine whether hypoxia-related signaling alters placental BCRP expression and function in vitro and in human pregnancies. METHODS: Human BeWo choriocarcinoma cells were treated with the hypoxia mimetic, cobalt chloride (CoCl(2)), or 3% oxygen for 24-48 h. Activation of HIF-1α signaling and regulation of BCRP was assessed using qPCR, ELISA, western blotting and a fluorescent substrate transport assay. In addition, healthy term placentas from high altitude pregnancies with chronic hypoxia were assessed for BCRP expression. RESULTS: CoCl(2) and 3% oxygen increased HIF-1α protein signaling and decreased the mRNA and protein expression of BCRP by 30-75% in BeWo cells. Reduced BCRP expression corresponded with impaired efflux activity during hypoxia as evidenced by accumulation of the substrate Hoechst 33342. A number of transcription factors known to regulate BCRP, including AHR, NRF2 and PPARγ, were also coordinately down-regulated by 3% oxygen in BeWo cells. Moreover, women who gave birth at a high altitude (3100 m) exhibited signs of chronic placental hypoxia, including enhanced protein expression of the HIF-1α target GLUT1, and had reduced BCRP levels in microvillous membranes compared to women at a moderate altitude (1600 m). DISCUSSION: This study provides novel insight into the regulation of the placental BCRP transporter by hypoxia, which may be important for exposure of the fetus to chemicals during early development and in hypoxia-related pregnancy disorders