MT-CYB and injury: We measured mtDNA content in plasma from young (n = 9, average age 36.8) and old (n = 6, average age 82.7) trauma patients and corresponding young (n = 11, average age ~25) and old (n = 7, average age 72.1) volunteers by quantitative RT-PCR using primers specific to the mitochondrial gene, cytochrome B. Assigning young volunteers’ mtDNA levels as a control value of 100%, elderly volunteers, young trauma patients and elderly trauma patients had values of 385 ± 8, 364 ± 9, and 2156 ± 72 respectively (Fig. 4A).