Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.

Input: Consider Input: Abstract: In a double-blind, placebo-controlled study the analgesic efficacy of the combination of a tricyclic antidepressant and morphine was investigated. One of two tricyclic antidepressants (either amitriptyline, a relatively selective serotonin uptake inhibitor or desipramine, a relatively selective noradrenaline uptake inhibitor) or a placebo, was given for 1 week prior to surgery, followed by a single postoperative dose of morphine. Desipramine, but not amitriptyline, both increased and prolonged morphine analgesia. Neither tricyclic antidepressant reduced dental postoperative pain in the absence of morphine. We propose that desipramine enhances opiate analgesia by enhancing a noradrenergic component that contributes to endogenous opioid-mediated analgesia systems.

Output: Amitriptyline

Input: Consider Input: Abstract: Twenty-two patients with evidence of systemic vasculitis and peripheral neuropathy were clinically and electrophysiologically investigated in a retrospective study. Ten had a polyarteritis nodosa, 6 a probable polyarteritis nodosa, and 6 a Churg-Strauss syndrome. Nine patients presented clinically with mononeuropathy or mononeuropathy multiplex considered typical of ischemic involvement of peripheral nerve; nine had more diffuse neuropathy, two of them a symmetric polyneuropathy. EMG examination revealed more diffuse neuropathy than clinically predicted. Findings were of acute or subacute axonal neuropathy.

Output: Adult

Input: Consider Input: Abstract: To determine the end point of histopathologic damage in avulsed arteries, the forearm arteries of five monkeys being sacrificed were avulsed longitudinally and samples of proximal and distal arteries prepared for light microscopy and transmission and scanning electron microscopy. A severe and consistent circumferential skip lesion was found on the luminal surface involving the intima and media. In 30 percent of vessels, histopathologic damage extended more than 3.0 cm from the rupture point. Similar circumferential tears occurred on the luminal surface of resected human avulsed arteries collected at the time of replantation surgery. No consistent lesions were noted in resected veins from human avulsed amputations. It is possible that in the human artery (as in the monkey) circumferential lesions frequently extend many centimeters from the rupture point and therefore beyond resection distances. Lesions present in the vessel after resection and microsurgical repair might be the site of thrombosis and subsequent occlusion.
Output: Animal