instruction:
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.
question:
Context: Anemia is an established adverse risk factor in cardiovascular disease. However, the effect of preoperative anemia is not well defined in heart surgery. This study evaluates the effect of preoperative anemia on early clinical outcomes in patients undergoing cardiac surgery.', 'A retrospective, observational, cohort study of prospectively collected data was undertaken on 7,738 consecutive patients undergoing heart surgery between April 2003 and February 2009. Of these, 1,856 patients with preoperative anemia were compared to 5,882 patients without anemia (control group). According to the World Health Organization, anemia was defined as hemoglobin level<13 g/dl for men and <12 g/dl for women. Selection bias not controlled by multivariable methods was assessed with propensity-adjustment method.', 'Overall mortality was 2.1%. Preoperative anemia was associated with tripling in the risk of death (4.6% vs 1.5%, p<0.0001) and postoperative renal dysfunction (18.5% vs 6.5%, p<0.0001). There was also a significant difference between the anemic and non-anemic group in the risk of postoperative stroke (1.9% vs 1.1%, p=0.008), atrial fibrillation (36.7% vs 33%, p=0.003) and length of hospital stay>7 days (54% vs 36.7%, p<0.0001). In propensity-adjusted, multivariable logistic regression, preoperative anemia was an independent predictor of mortality (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.02 to 2.03), postoperative renal dysfunction (OR 1.73, 95% CI 1.43 to 2.1) and length of hospital stay>7 days (OR 1.3, 95% CI 1.15 to 1.47).
Answer: In patients undergoing heart surgery, preoperative anemia is associated with an increased risk of mortality and postoperative morbidity.
answer:
Does preoperative anemia increase mortality and postoperative morbidity after cardiac surgery?

question:
Context: Hyperoxia increases oxidative stress through the generation of reactive oxygen species and may therefore enhance inflammation in the lungs. The aim of this study was to investigate whether short term supplementary oxygen (28%) increases oxidative stress and inflammation in the airways by measuring 8-isoprostane and interleukin 6 (IL-6) concentrations in exhaled breath condensate.', 'Twenty three healthy subjects (12 men, mean (SD) age 48 (7) years) and 23 patients with chronic obstructive pulmonary disease (COPD; 15 men, mean (SD) age 56 (5) years) were studied. 8-isoprostane and IL-6 concentrations were measured by immunoassay.', 'Increased concentrations of 8-isoprostane and IL-6 were found in all subjects after breathing 28% oxygen for 1 hour. In healthy subjects the concentrations of 8-isoprostane and IL-6 were 10.9 (2.9) pg/ml and 4.9 (0.8) pg/ml, respectively, compared with baseline concentrations of 6.1 (1.3) pg/ml and 2.9 (0.6) pg/ml, and in patients with COPD the concentrations were 27.9 (3.1) pg/ml and 8.3 (1.2) pg/ml), respectively, compared with baseline concentrations of 18.9 (3.6) pg/ml and 6.3 (0.6) pg/ml. By contrast, breathing air through the same face mask for 1 hour had no significant effects on 8-isoprostane or IL-6 concentrations in normal subjects or those with COPD.
Answer: These findings suggest that short term supplementary oxygen may enhance oxidative stress and inflammation in the airways. Whether this happens with long term oxygen therapy needs to be determined.
answer:
Does supplementary oxygen in healthy subjects and those with COPD increase oxidative stress and airway inflammation?

question:
Context: Hirschsprung disease (HSCR) is a rare multigenic congenital disorder characterized by the absence of the enteric ganglia. To date, single nucleotide polymorphisms (SNPs) in pre-miRNAs have been confirmed related with some diseases. Thus, we hypothesized that pre-miRNA polymorphisms might contribute to HSCR susceptibility. We investigated whether rs2910164 and rs11614913 of pre-miR-146a and pre-miR-196a2, are associated with HSCR.', 'Polymorphisms were genotyped using the Taqman method. Real-time PCR was used for detecting the expression level of miR-146a and its target gene ROBO1 in CC and GG genotypes.', 'Significant differences were found in the genotype distribution of rs2910164 and rs11614913 polymorphism between HSCR cases and controls (p = 0.023 and 0.041, respectively). Furthermore, G allele of rs2910164 might increase the risk of HSCR (OR, 1.54; 95% CI, 1.06-2.23). Moreover, the expression level of miR-146a for homozygote GG was also higher than homozygote CC (p = 0.0193). In contrast, the expression level of its target gene ROBO1 predicted in bioinformatics for homozygote GG was much lower than homozygote CC (p = 0.0096).
Answer: Our results showed that the polymorphism rs2910164 in pre-miR-146a might alter the production of mature miR-146a and then down-regulate the target gene ROBO1, which plays an important role in pathogenesis of HSCR.
answer:
Does a common polymorphism in pre-miR-146a underlie Hirschsprung disease risk in Han Chinese?