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Background There is a clear need for assays that can predict the risk of metastatic prostate cancer following curative procedures. Importantly these assays must be analytically robust in order to provide quality data for important clinical decisions. DNA microarray based gene expression assays measure several analytes simultaneously and can present specific challenges to analytical validation. This study describes the analytical validation of one such assay designed to predict metastatic recurrence in prostate cancer using primary formalin fixed paraffin embedded tumour material. Methods Accuracy was evaluated with a method comparison study between the assay development platform (Prostate Disease Specific Array) and an alternative platform (Xcel™ microarray) using 50 formalin-fixed, paraffin-embedded prostate cancer patient samples. An additional 70 samples were used to establish the assay reportable range. Determination of assay precision and sensitivity was performed on multiple technical replicates of three prostate cancer samples across multiple variables (operators, days, runs, reagent lots, and equipment) and RNA/cDNA inputs respectively using the appropriate linear mixed model. Results The overall agreement between the development and alternative platform was 94.7% (95% confidence interval, 86.9–98.5%). The reportable range was determined to be 0.150 to 1.107 for core needle biopsy samples and − 0.214 to 0.844 for radical prostatectomy samples. From the precision study, the standard deviations for assay repeatability and reproducibility were 0.032 and 0.040 respectively. The sensitivity study demonstrated that a total RNA input and cDNA input of 50 ng and 3.5 μg respectively was conservative. Conclusion The Metastatic Assay was found to be highly reproducible and precise. In conclusion the studies demonstrated an acceptable analytical performance for the assay and support its potential use in the clinic. Electronic supplementary material The online version of this article (10.1186/s12920-018-0442-y) contains supplementary material, which is available to authorized users.

The music that chronicles the African American experience is marked in profound but subtle and contradictory ways by the law, perhaps the most pervasive presence in black life since enslaved Africans arrived in the New World. From the mournful but veiled complaints of the sorrow songs to Jay Z’s boastful narration of a pretextual traffic stop, at the heart of so much of the music of black culture lies a wary appraisal, and often an outright rejection, of the “justice” of American law. This Commentary reviews the fraught relationship between the law and the tradition of African American music.

This essay explores the recurring figure of the traitor in African-American letters, arguing that literary portrayals of the crime of treason reveal the fundamental tension between black loyalty to the nation and the nation’s betrayal of the race, and indeed demand that we reconsider the terms of treason itself. In three nineteenth-century texts by African American writers—Victor Sejour’s 1837 “The Mulatto,” Frederick Douglass’s 1853 “The Heroic Slave,” and Sutton Griggs’s 1899 Imperium in Imperio—faithful black subjects are inevitably betrayed by racialized law and custom and the refusal to acknowledge the possibility of a black subject fully incorporated into the nation. Asking whether and how blacks writers can navigate the chasm between loyalty to race and loyalty to nation, this essay interrogates the twinned metaphors of patriotism and treason as literary responses to the seeming incommensurability of racial and national citizenship.