Bayesian Modeling of MPSS Data: Gene Expression Analysis of Bovine Salmonella Infection

Massively Parallel Signature Sequencing (MPSS) is a high-throughput counting-based technology available for gene expression profiling. It produces output that is similar to Serial Analysis of Gene Expression (SAGE) and is ideal for building complex relational databases for gene expression. Our goal is to compare the in vivo global gene expression profiles of tissues infected with different strains of Salmonella obtained using the MPSS technology. In this article, we develop an exact ANOVA type model for this count data using a zero-inflated Poisson (ZIP) distribution, different from existing methods that assume continuous densities. We adopt two Bayesian hierarchical models-one parametric and the other semiparametric with a Dirichlet process prior that has the ability to "borrow strength" across related signatures, where a signature is a specific arrangement of the nucleotides, usually 16-21 base-pairs long. We utilize the discreteness of Dirichlet process prior to cluster signatures that exhibit similar differential expression profiles. Tests for differential expression are carried out using non-parametric approaches, while controlling the false discovery rate. We identify several differentially expressed genes that have important biological significance and conclude with a summary of the biological discoveries.     

Age-related neurodegenerative changes and how they affect the gut

The enteric nervous system (ENS) is the division of the autonomic nervous system that regulates gastrointestinal (GI) function. Although large numbers of enteric neurons may be lost with age, the GI tract remains surprisingly functional. Exceptions to this generality include swallowing disorders and reduced colonic motility in the elderly. Evidence of age-related neurodegenerative changes in structure and function of the ENS is briefly reviewed in this Perspective.     

Gambling decisions: an early intervention program for problem gamblers

An implementation and one-year follow-up of the Gambling Decisions program attempted to answer several important questions. First, is controlled gambling a viable treatment option for some gamblers? Can earlier stage problem gamblers be separated for treatment from those with more severe problems? Finally, would problem gamblers utilize a community health agency for treatment of their excessive gambling? A pretest/posttest design was chosen where the efficacy of the program was assessed using repeated measures ANOVA analysis. Results showed that an average loss of $608 over a 4-week period was reduced to $113 immediately after the 6-week program and to a loss of $73 at 12 months. The average number of hours spent gambling per 4 weeks was significantly reduced from 23.5 at pretest to 6.5 at the 12 month posttest. Significant decreases were also observed in the number of days per week that clients gambled, and clients reported significant reductions in everyday life problems related to gambling after completing the program.     

Nonemployment of Black Men in Major Metropolitan Areas*

The author examines the extent of nonemployment among black males across 64 MSAs in 1980, testing Szymanski's (1976) thesis of functional substitutability of women and black workers in the post-World War II period. Evidence is presented to show that black male nonemployment is partially the result of increased white female employment. The paper concludes with the suggestion that in the United States labor displacement in the post-World War II economy has worked cross-genderly when race is taken into account.