Given a passage with a context and an answer, 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.

[EX Q]: Context: To study the effect of Cleistocalyx nervosum extract (CE) on diethylnitrosamine (DEN) and phenobarbital (PB) induced oxidative stress in early stages of rat hepatocarcinogenesis.', 'Male Wistar rats were divided into 4 groups, with Group 1 as a negative control and Group 2 was a positive control receiving DEN injections once a week and PB in drinking water for 6 weeks. Two weeks before DEN initiation and PB treatment, Groups 3 and 4, were fed with 500 and 1000 mg/kg of CEs, respectively, for 8 weeks.', 'A number of GST-P-positive foci, preneoplastic lesions, in the liver were markedly increased in carcinogen administered rats, but was comparatively decreased in rats treated with 1000 mg/kg of CE. The CE reduced malondialdehyde in serum and in the livers of rats treated with DEN and PB. Moreover, CE significantly increased the activities of glutathione peroxidase and catalase in rat liver.
Answer: CE appeared to exert its chemopreventive effects by modulating antioxidant status during DEN and PB induced early stages of hepatocarcinogenesis in rats.
[EX A]: Does cleistocalyx nervosum extract ameliorate chemical-induced oxidative stress in early stages of rat hepatocarcinogenesis?

[EX Q]: Context: Growth-differentiation factor-15 (GDF-15) is emerging as an independent prognostic biomarker in patients with cardiovascular (CV) disease. Little is known about the pathophysiological basis for the close association of GDF-15 to future CV events. We hypothesized that GDF-15 is related to underlying CV pathologies.', 'To relate the levels of GDF-15 to indices of CV dysfunction and disease in elderly individuals, serum levels of GDF-15 were measured in 1004 subjects aged 70 years from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. Carotid intima-media thickness and plaque burden, and left ventricular (LV) geometry and function were assessed by ultrasound. Endothelial function was evaluated in forearm resistance vessels and in the brachial artery by venous occlusion plethysmography and ultrasound imaging, respectively. Elevated levels of GDF-15 were related to several CV risk factors (male gender, current smoking, body mass index, waist circumference, diabetes, fasting glucose, triglycerides, and low HDL cholesterol). After adjustment for CV risk factors, increased levels of GDF-15 were associated with reduced endothelium-dependent vasodilation in resistance vessels, plaque burden, LV mass and concentric LV hypertrophy, reduced LV ejection fraction, and clinical manifestations of coronary artery disease and heart failure.
Answer: GDF-15 carries information on CV dysfunction and disease that is not captured by traditional CV risk factors in elderly individuals.
[EX A]: Is growth-differentiation factor-15 an independent marker of cardiovascular dysfunction and disease in the elderly : results from the Prospective Investigation of the Vasculature in Uppsala Seniors ( PIVUS ) Study?

[EX Q]: Context: Are submaximal and maximal exercise tests reliable, valid and acceptable in people with chronic pain, fibromyalgia and fatigue disorders?', 'Systematic review of studies of the psychometric properties of exercise tests.', 'People older than 18 years with chronic pain, fibromyalgia and chronic fatigue disorders.', 'Studies of the measurement properties of tests of physical capacity in people with chronic pain, fibromyalgia or chronic fatigue disorders were included.', "Studies were required to report: reliability coefficients (intraclass correlation coefficient, alpha reliability coefficient, limits of agreements and Bland-Altman plots); validity coefficients (intraclass correlation coefficient, Spearman's correlation, Kendal T coefficient, Pearson's correlation); or dropout rates.", 'Fourteen studies were eligible: none had low risk of bias, 10 had unclear risk of bias and four had high risk of bias. The included studies evaluated: Astrand test; modified Astrand test; Lean body mass-based Astrand test; submaximal bicycle ergometer test following another protocol other than Astrand test; 2-km walk test; 5-minute, 6-minute and 10-minute walk tests; shuttle walk test; and modified symptom-limited Bruce treadmill test. None of the studies assessed maximal exercise tests. Where they had been tested, reliability and validity were generally high. Dropout rates were generally acceptable. The 2-km walk test was not recommended in fibromyalgia.
Answer: Moderate evidence was found for reliability, validity and acceptability of submaximal exercise tests in patients with chronic pain, fibromyalgia or chronic fatigue. There is no evidence about maximal exercise tests in patients with chronic pain, fibromyalgia and chronic fatigue.
[EX A]:
Are several submaximal exercise tests reliable , valid and acceptable in people with chronic pain , fibromyalgia or chronic fatigue : a systematic review?