Instructions: Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Input: Oxidative stress in reflux esophagitis was investigated before and after antireflux surgery.', "Oxidative stress was studied in the distal and proximal esophagus of control patients (without esophagitis, but with other gastrointestinal disorders), of patients with various grades of esophagitis (including Barrett's esophagus), and in patients who had a Nissen fundoplication. Oxidative stress was assessed by chemiluminescence, lipid peroxidation (LP), and by measuring superoxide dismutase (SOD).", "Chemiluminescence and LP increased with the degree of esophagitis and was highest in patients with Barrett's esophagus; SOD decreased with damage, except in cases of Barrett's esophagus associated with mild esophagitis. Chemiluminescence and LP in reflux patients were higher in the distal than in the proximal esophagus, and SOD was lower, whereas no such difference was found in controls. Findings after Nissen fundoplication were similar to those of controls.
Output:
Is reflux esophagitis in humans mediated by oxygen-derived free radicals?