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Pabalan N.A.,University of Saint Louis
Asian Pacific Journal of Cancer Prevention | Year: 2010

Genetic association studies report potentially conflicting findings which meta-analysis seeks to quantify and objectively summarize. Attributing cancer to a single gene variant requires large sample sizes, which may strain resources in a primary study. Properly used, meta-analysis is a powerful tool for resolving discrepancies in genetic association studies given the exponential increase in sample sizes when data are combined. The several steps involved in this methodology require careful attention to critical issues in meta-analysis, heterogeneity and publication bias, evaluation of which can be graphical or statistical. Overall summary effects of a meta-analysis may or may not reflect similar associations when the component studies are sub grouped. Overall associations and that of the subgroups are evaluated for tenability using sensitivity analysis. The low association between a polymorphism and cancer is offset by detectable changes in cancer incidence in the general population making them an important issue from a public health point of view. Asian meta-analytic publications in cancer genetics come from six countries with an output that number from one to two. The exception is China, whose publication output has increased exponentially since 2008. Source


Pabalan N.,University of Saint Louis | Jarjanazi H.,Environment Canada | Ozcelik H.,Samuel Lunenfeld Research Institute
Breast Cancer Research and Treatment | Year: 2013

Inconsistency of reported associations between the Pro919Ser polymorphism in the BRCA1 interacting protein 1 (BRIP1) gene and breast cancer prompted us to undertake a meta-analysis. Although investigated by fewer studies, we have also studied the risk associated with the two additional BRIP1 polymorphisms, C47G and G64A, and breast cancer riskWe conducted searches of the published literature in MEDLINE through PubMed up to October 2012. Individual data on 5,122 cases and 5,735 controls from eight published case-control studies were evaluated for the Pro919Ser polymorphism. Accordingly, C47G and G64A polymorphisms were studied in 1,539 cases and 1,183 controls, and 667 and 782, respectively.In the overall analysis, association was lacking between the Pro919Ser polymorphism and breast cancer risk (odds ratio [OR] 0.98-1.02), materially unchanged when confined to subjects of European ancestry (OR 0.96-1.03) or even in the high-powered studies (OR 0.97-1.03). In the menopausal subgroups, premenopausal women followed the null pattern (OR 0.94-0.98) for the Pro and Ser allele contrasts, but not for the Pro-Ser genotype comparison where significant increased risk was observed (OR 1.39, P = 0.002). The postmenopausal women (>50 years) exhibited a range of pooled effects from protection (OR 0.83, P = 0.11) in the Pro-Ser genotype to slightly increased risk (OR 1.12-1.16, P = 0.28-0.42) in the Pro and Ser allele comparisons. The G64A polymorphism effects were essentially null (OR 0.90-0.98), but C47G was found to confer non-significantly increased risk under all genetic models (OR 1.27-1.40).Upon conclusion, overall summary estimates imply no associations but suggest susceptibility among carriers of the C47G polymorphism and Pro-Ser genotype in premenopausal women. The premenopausal findings and variable outcomes in postmenopausal women require more studies for confirmation. © 2012 Springer Science+Business Media New York. Source


Pabalan N.,University of Saint Louis | Jarjanazi H.,Environment Canada | Sung L.,Hospital for Sick Children | Li H.,Samuel Lunenfeld Research Institute | Ozcelik H.,Samuel Lunenfeld Research Institute
PLoS ONE | Year: 2012

Background: Breast cancer susceptibility may be modulated partly through polymorphisms in oxidative enzymes, one of which is myeloperoxidase (MPO). Association of the low transcription activity variant allele A in the G463A polymorphism has been investigated for its association with breast cancer risk, considering the modifying effects of menopausal status and antioxidant intake levels of cases and controls. Methodology/Principal Findings: To obtain a more precise estimate of association using the odds ratio (OR), we performed a meta-analysis of 2,975 cases and 3,427 controls from three published articles of Caucasian populations living in the United States. Heterogeneity among studies was tested and sensitivity analysis was applied. The lower transcriptional activity AA genotype of MPO in the pre-menopausal population showed significantly reduced risk (OR 0.56-0.57, p = 0.03) in contrast to their post-menopausal counterparts which showed non-significant increased risk (OR 1.14; p = 0.34-0.36). High intake of antioxidants (OR 0.67-0.86, p = 0.04-0.05) and carotenoids (OR 0.68-0.86, p = 0.03-0.05) conferred significant protection in the women. Stratified by menopausal status, this effect was observed in pre-menopausal women especially those whose antioxidant intake was high (OR 0.42-0.69, p = 0.04). In post-menopausal women, effect of low intake elicited susceptibility (OR 1.19-1.67, p = 0.07-0.17) to breast cancer. Conclusions/Significance: Based on a homogeneous Caucasian population, the MPO G463A polymorphism places post-menopausal women at risk for breast cancer, where this effect is modified by diet. © 2012 Pabalan et al. Source


Pangilinan J.M.,University of Saint Louis | Janssens G.K.,Hasselt University
Journal of Global Optimization | Year: 2011

This paper investigates the performance of evolutionary algorithms in the optimization aspects of oblique decision tree construction and describes their performance with respect to classification accuracy, tree size, and Pareto-optimality of their solution sets. The performance of the evolutionary algorithms is analyzed and compared to the performance of exhaustive (traditional) decision tree classifiers on several benchmark datasets. The results show that the classification accuracy and tree sizes generated by the evolutionary algorithms are comparable with the results generated by traditional methods in all the sample datasets and in the large datasets, the multiobjective evolutionary algorithms generate better Pareto-optimal sets than the sets generated by the exhaustive methods. The results also show that a classifier, whether exhaustive or evolutionary, that generates the most accurate trees does not necessarily generate the shortest trees or the best Pareto-optimal sets. © 2010 Springer Science+Business Media, LLC. Source


Bonzi B.,University of Ouagadougou | Fall A.A.,French Institute for Research in Computer Science and Automation | Fall A.A.,University of Saint Louis | Iggidr A.,French Institute for Research in Computer Science and Automation | Sallet G.,French Institute for Research in Computer Science and Automation
Journal of Mathematical Biology | Year: 2011

We introduce classes of differential susceptibility and infectivity epidemic models. These models address the problem of flows between the different susceptible, infectious and infected compartments and differential death rates as well. We prove the global stability of the disease free equilibrium when the basic reproduction ratio R0 ≤ 1 and the existence and uniqueness of an endemic equilibrium when R0 > 1. We also prove the global asymptotic stability of the endemic equilibrium for a differential susceptibility and staged progression infectivity model, when R0 > 1. Our results encompass and generalize those of Hyman and Li (J Math Biol 50:626-644, 2005; Math Biosci Eng 3:89-100, 2006). © 2010 Springer-Verlag. Source

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