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.
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Question: It has already been demonstrated that the rat esophagus produces retinoic acid from retinol. In this study, this process is further characterized and the effect of acetaldehyde examined to elucidate the possible mechanisms behind the epidemiological evidence that the incidence of esophageal cancer is higher in alcoholics.', 'Rat esophageal samples were incubated with all-trans retinal and newly formed all-trans retinoic acid (ATRA) was quantified using high-performance liquid chromatography (HPLC). Furthermore, beta-nicotinamide adenine dinucleotide (NAD)-dependent acetaldehyde oxidation by the rat esophagus was examined by tracing NAD reduction using a spectrophotometer.', 'Rat esophageal samples produced ATRA from all-trans retinal in a NAD-dependent manner and the potential was significantly attenuated by phenetyl isothiocynate, an ALDH inhibitor, or acetaldehyde depending on the concentration used. Rat esophageal samples also oxidized acetaldehyde of various concentrations NAD dependently. The ATRA formation potential that was temporarily inhibited by acetaldehyde was recovered to the control level by dialysis when the specimen was incubated with up to 50 microM of acetaldehyde.

Answer: Does acetaldehyde inhibit the formation of retinoic acid from retinal in the rat esophagus?


Question: To investigate the effect of kappa-Opioid receptors in the cardioprotection elicited by ischemic postconditioning and the underlying mechanism.', 'The isolated perfused hearts of male Sprague-Dawley rats were subjected to 30 min of global ischemia followed by 120 min of reperfusion. formazan content of myocardium was measured spectrophotometrically, and the level of lactate dehydrogenase (LDH) in the coronary effluent was also measured. In isolated ventricular myocytes hypoxia postconditioning was achieved by 3 cycles of 5 min reoxygenation/5 min hypoxia starting at the beginning of reoxygenation, and cell viability was measured.', 'In the Langendorff perfused rat heart model, ischemic postconditioning (6 cycles of 10 s reperfusion/10 s global ischemia starting at the beginning of reperfusion) increased formazan content, reduced LDH release, improved the recovery of the left ventricular developed pressure, maximal rise/fall rate of left ventricular pressure, left ventricular end-diastolic pressure and rate pressure product (left ventricular developed pressure multiplied by heart rate), attenuated the decrease of coronary flow during reperfusion and increased the isolated cell viability. Pretreatment with nor-BNI, an antagonist of kappa-Opioid receptors and mitoK(ATP) blocker 5-HD attenuated the effect of ischemic/hypoxic postconditioning.

Answer: Does [ Kappa-opioid receptor mediate the cardioprotective effect of ischemic postconditioning ]?


Question: To investigate by immunohistochemical observation the effects of amniotic membrane (AM) patching on myofibroblastic differentiation and matrix metalloproteinase (MMP) expression in the corneal stroma after an alkali burn in vivo.', 'A corneal alkali burn was made by placing a circular piece of filter paper containing 1 N NaOH on the central cornea of rabbits. Burning was done unilaterally in each rabbit. Immediately after the wounding, in the AM group, AM was sutured onto the cornea and removed on day 1. Rabbits with no AM patching were controls. On day 14, corneas were excised and immunohistochemical observation was carried out using antibodies against alpha-smooth muscle actin (alpha-SMA), vimentin, MMP-1, MMP-2, MMP-9, and membrane-type1 (MT1)-MMP. Observation after Masson trichrome staining was also performed.', 'In the AM group, alpha-SMA positive cells were noticeably fewer, and MMP-2, MMP-9, and MT1-MMP expression was clearly inhibited. Also, collagen fibers were more regularly arranged than in control eyes. The more proximate the cells were to the epithelial side, the fewer alpha-SMA-positive cells were observed in the AM group.

Answer:
Do immunohistochemical observation of amniotic membrane patching on a corneal alkali burn in vivo?