The investigators, therefore, initiated a second translational study in which it was hypothesized that a higher dose of naloxone (2 mg/kg) would reinstate secondary hyperalgesia in human patients following resolution of a mild burn injury and thus show latent sensitization in humans. The investigators demonstrated in 4 out of 12 patients that naloxone administered 7 days after a mild burn injury was associated with the reinstatement of secondary hyperalgesia.