Temporal changes in plasma miRNA content after traumatic brain injury. Purified RNA from plasma collected at various time points after injury were assayed using miRNA-specific TaqMan probes directed against (A) miR-16, (B) miR-26a, (C) miR-92a, (D) miR-638, or (E) miR-765. Changes in threshold cycle are relative to the mean of the healthy volunteer (HV) values. Data are presented as the mean ± standard error of the mean of each group (*p < 0.05 by one-way ANOVA, or ANOVA on ranks; ANOVA, analysis of variance; miRNA, microRNA; TBI, traumatic brain injury).