Submitted for Publication: January 26, 2012; final revision received April 5, 2012; accepted May 3, 2012.
Author Contributions: Drs Perkins, Spencer, Haughey, Nussenbaum, Adkins, Kuperman, and Thorstad had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Perkins and Thorstad. Acquisition of data: Perkins, Spencer, Chernock, Haughey, and Thorstad. Analysis and interpretation of data: Perkins, Spencer, Chernock, Haughey, Nussenbaum, Adkins, and Kuperman. Drafting of the manuscript: Perkins and Adkins. Critical revision of the manuscript for important intellectual content: Perkins, Spencer, Chernock, Haughey, Nussenbaum, Adkins, Kuperman, and Thorstad. Statistical analysis: Perkins and Spencer. Administrative, technical, and material support: Spencer, Haughey, Adkins, and Thorstad. Study supervision: Nussenbaum and Thorstad.
Financial Disclosure: None reported.
Additional Contributions: Jianping Li, BS, provided expert technical assistance with the immunohistochemical experiments.