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Open Access Software

BMDExpress: a software tool for the benchmark dose analyses of genomic data

Longlong Yang1, Bruce C Allen2 and Russell S Thomas1*

Author Affiliations

1 The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709-2137, USA

2 Bruce Allen Consulting, 101 Corbin Hill Circle, Chapel Hill, NC 27514, USA

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BMC Genomics 2007, 8:387  doi:10.1186/1471-2164-8-387

Published: 25 October 2007

Abstract

Background

Dose-dependent processes are common within biological systems and include phenotypic changes following exposures to both endogenous and xenobiotic molecules. The use of microarray technology to explore the molecular signals that underlie these dose-dependent processes has become increasingly common; however, the number of software tools for quantitatively analyzing and interpreting dose-response microarray data has been limited.

Results

We have developed BMDExpress, a Java application that combines traditional benchmark dose methods with gene ontology classification in the analysis of dose-response data from microarray experiments. The software application is designed to perform a stepwise analysis beginning with a one-way analysis of variance to identify the subset of genes that demonstrate significant dose-response behavior. The second step of the analysis involves fitting the gene expression data to a selection of standard statistical models (linear, 2° polynomial, 3° polynomial, and power models) and selecting the model that best describes the data with the least amount of complexity. The model is then used to estimate the benchmark dose at which the expression of the gene significantly deviates from that observed in control animals. Finally, the software application summarizes the statistical modeling results by matching each gene to its corresponding gene ontology categories and calculating summary values that characterize the dose-dependent behavior for each biological process and molecular function. As a result, the summary values represent the dose levels at which genes in the corresponding cellular process show transcriptional changes.

Conclusion

The application of microarray technology together with the BMDExpress software tool represents a useful combination in characterizing dose-dependent transcriptional changes in biological systems. The software allows users to efficiently analyze large dose-response microarray studies and identify reference doses at which particular cellular processes are altered. The software is freely available at http://sourceforge.net/projects/bmdexpress/ webcite and is distributed under the MIT Public License.