In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
--------
Question: Context: Vitamin A plays a major role in lipid metabolism. Previously, we reported that chronic vitamin A feeding (129 mg/kg) for two months normalized the abnormally high plasma HDL-cholesterol (HDL-C) levels in hypercholesterolemic obese rats by upregulating the hepatic scavenger receptor class B type 1 (SR-BI) expression. In this report, we hypothesize that the administration of a dose less than 129 mg of vitamin A/kg would also be effective in lowering the plasma HDL-C levels in these rats.', 'Changes in the activity and expression of proteins related to RCT were analyzed together with blood parameters in five-month-old male lean and obese rats supplemented with 2.6 (control group), 26, 52 and 129 mg of vitamin A/kg as retinyl palmitate for 20 weeks.', 'Vitamin A supplementation in the obese rats decreased the plasma HDL-C levels with a concomitant increase in the hepatic SR-BI expression and lipase activity compared to that observed in the control diet-fed obese rats treated with 2.6 mg of vitamin A/kg diet. Furthermore, vitamin A supplementation at doses of 52 and 129 mg/kg diet reduced the plasma lecithin cholesterol acyltransferase activity and increased the hepatic ATP-binding cassette transporter protein A1 expression in the obese rats. Interestingly, most of these changes were not observed in the lean rats fed a vitamin A-enriched diet.\Question: Does vitamin A-enriched diet modulate reverse cholesterol transport in hypercholesterolemic obese rats of the WNIN/Ob strain?

Answer: Chronic feeding of a vitamin A-enriched diet in hypercholesterolemic obese rats normalizes the plasma HDL-C level and presumably improves RCT, with an effective dose of 52 mg/kg diet. Further studies should focus on the pharmacological potential of vitamin A supplementation to correct an abnormal human obesity-associated lipoprotein metabolism.


Question: Context: To investigate the incidence of acute kidney injury after cardiac surgery and its association with mortality in a patient population receiving ibuprofen and gentamicin perioperatively.', 'Retrospective study with Cox regression analysis to control for possible preoperative, intraoperative and postoperative confounders.', 'University hospital-based single-center study.', 'All patients who underwent coronary artery bypass grafting ± valve surgery during 2012.', 'None.', 'Acute surgery within 24 hours of coronary angiography, previous nephrectomy, preoperative sCr >2.26 mg/dL and selective cerebral perfusion during cardiopulmonary bypass were used as exclusion criteria. Acute kidney injury was defined, using the Acute Kidney Injury Network (AKIN) criteria. Six hundred eight patients were included in the study. Mean age was 68.2 ± 9.7 years, and 81% were males. Acute kidney injury was seen in 28.1% of the patients. Overall mortality at one year was 7% and 3% in the no-AKI group. At one year, mortality was 15% in patients with AKIN stage 1 and AKIN stage 2 compared to 70% in AKIN stage 3. A hazard ratio of 2.34 (95% CI: 1.21-4.51, p = 0.011) and 5.62 (95% CI: 2.42-13.06), p<0.0001) were found for AKIN stage 1 and 2/3 combined, respectively.\Question: Is acute kidney injury independently associated with higher mortality after cardiac surgery?

Answer: More than 28% of the patients undergoing elective or subacute cardiac surgery developed AKI in this contemporary cohort. Furthermore, acute kidney injury was an independent predictor of increased mortality irrespective of the perioperative risk factors.


Question: Context: To characterize metabolic features of women with polycystic ovary syndrome (PCOS) by exercise behavior and determine relative health benefits of different exercise intensities.', 'Cross-sectional study.', 'Tertiary academic institution.', 'Three hundred and twenty-six women aged 14-52 years-old with PCOS by Rotterdam criteria examined between 2006 and\xa02013.', 'International Physical Activity Questionnaire (IPAQ) administered to classify patients into three groups based on Department of Health and Human Services (DHHS) Guidelines of vigorous, moderate, and inactive, along with physical examination and serum testing.', 'Blood pressure, body mass index (BMI), waist circumference, fasting lipids, fasting glucose and insulin, 2-hour 75-gram oral glucose tolerance, homeostatic model assessment of insulin resistance (HOMA-IR).', "The DHHS guidelines for adequate physical activity were met by 182 (56%) women. Compared with moderate exercisers and inactive women, the vigorous exercisers had lower BMI and lower HOMA-IR; higher levels of high-density lipoprotein cholesterol and sex hormone-binding globulin; and a reduced prevalence of the metabolic syndrome. In a multivariate logistic regression analysis controlling for age, BMI, and total energy expenditure, every hour of vigorous exercise reduced a patient's odds of metabolic syndrome by 22% (odds ratio 0.78; 95% confidence interval, 0.62, 0.99).\Question: Is vigorous exercise associated with superior metabolic profiles in polycystic ovary syndrome independent of total exercise expenditure?

Answer:
Women with PCOS who met DHHS guidelines for exercise demonstrated superior metabolic health parameters. Vigorous but not moderate activity is associated with reduced odds of the metabolic syndrome, independent of age, BMI, and total energy expenditure. PCOS patients should be encouraged to meet activity guidelines via vigorous physical activity.