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.

[Q]: Context: Postoperative neurologic deficits after thoracic aortic reconstruction vary widely. Our previous study showed that delayed ischemic preconditioning could prevent spinal cord injury caused by occlusion of the descending thoracic aorta in pigs. We investigated early ischemic preconditioning in the same model.', 'Twenty-eight pigs were divided into 4 groups: group 1 (n = 6) underwent a sham operation, group 2 (n = 6) underwent aortic occlusion for 20 minutes, group 3 (n = 8) underwent aortic occlusion for 35 minutes, and group 4 (n = 8) underwent aortic occlusion for 20 minutes and underwent aortic occlusion 80 minutes later without hypotension for 35 minutes. Aortic occlusion was accomplished by using 2 balloon occlusion catheters placed fluoroscopically at T6 to T8 above the diaphragm and at the aortic bifurcation. Neurologic evaluation was performed by an independent observer according to the Tarlov scale (0-4). The lower thoracic and lumbar spinal cords were harvested at 120 hours and examined histologically with hematoxylin-and-eosin stain. Histologic results (number of neurons and grade of inflammation) were scored (0-4) and were similarly analyzed. Statistical analysis was by means of the Kruskal-Wallis test.', 'Group 4 had a better neurologic outcome at 24, 48, and 120 hours in comparison with group 3 (P <.001). The histologic changes were proportional to the neurologic test scores, with the more severe and extensive gray matter damage in animals of group 3 (number of neurons, P <.001; grade of inflammation, P <.001).
Answer: Early ischemic preconditioning without hypotension protects against spinal cord injury after aortic occlusion, as confirmed by using the Tarlov score and histopathology.
[A]: Does early ischemic preconditioning without hypotension prevent spinal cord injury caused by descending thoracic aortic occlusion?


[Q]: Context: Ischemic mitral regurgitation (MR) often persists after restrictive mitral valve annuloplasty, in which case it is associated with worse clinical outcomes. The goal of the present study was to determine whether persistence of MR and/or clinical outcome could be predicted from preoperative analysis of mitral valve configuration.', 'In 51 consecutive patients undergoing restrictive annuloplasty for ischemic MR, posterior leaflet (PL) angle, anterior leaflet angle, coaptation distance, and tenting area were quantified by echocardiography before surgery (6+/-3 days), and MR severity was assessed before and early after surgery (9+/-4 days). Postoperatively, persistence of mild to moderate MR (vena contracta > 3 mm) was observed in 11 (22%) of the patients. The best predictor of postoperative persistence of MR was a PL angle > or = 45 degrees (sensitivity 100%, specificity 97%, positive predictive value 92%, negative predictive value 100%). Patients with persistent MR had markedly lower 3-year event-free survival (26+/-20%) compared with those with nonpersistent MR (75+/-12%, P=0.01). Preoperative presence of a PL angle > or = 45 degrees also was associated with a markedly lower 3-year event-free survival (22+/-17% versus 76+/-12%; P<0.001).
Answer: In patients undergoing restrictive annuloplasty for ischemic MR, persistence of MR and 3-year event-free survival can accurately be predicted by preoperative analysis of mitral valve configuration. Patients with a PL angle > or = 45 degrees (ie, with high PL restriction) should thus be considered poor candidates for this procedure, and concomitant or alternative procedures should be contemplated.
[A]: Does preoperative posterior leaflet angle accurately predict outcome after restrictive mitral valve annuloplasty for ischemic mitral regurgitation?


[Q]: Context: High fibroblast growth factor-23 (FGF-23) levels are associated with mortality and cardiovascular events in patients with chronic kidney disease. The aim of this cross-sectional study was to investigate the relationship between plasma FGF-23 levels and coronary artery calcification and carotid artery intima-media thickness (CA-IMT) in hemodialysis (HD) patients.', 'In this cross-sectional study, plasma intact FGF-23 levels were measured in 229 patients who underwent coronary artery calcification scores (CACs) determined by multi-slice computerized tomography and CA-IMT assessed by using high-resolution color Doppler ultrasonography.', 'Median FGF-23 was 53.5 pg/ml (IQR 30.8-249.5). Median CACs was 98 (IQR 0-531), and the frequency of patients with severe calcification (CACs > 400) was 28.8%; 27.5% of cases had no calcification. Mean CA-IMT was 0.78 ± 0.20 mm, and the presence of carotid plaques was 51% with a mean length 2.1 mm. FGF-23 level was positively correlated with serum calcium (r = 0.337, p < 0.001), phosphate (r = 0.397, p < 0.001) and CACs (r = 0.218, p = 0.001). Neither CA-IMT nor the presence of carotid artery plaques correlated with FGF-23 levels. In adjusted ordinal regression analysis, FGF-23 level was an independent predictor for severe CACs together with age, gender, presence of diabetes, time on dialysis and CA-IMT (model r(2) = 0.44, p < 0.001). As a novel finding, the mean CACs was markedly higher in patients with FGF-23 level above median regardless of phosphate levels (p = 0.03).
Answer: In HD patients, plasma FGF-23 level is superior to phosphate in the prediction of coronary artery calcification. However, FGF-23 is not associated with carotid artery atherosclerosis in HD patients.
[A]:
Are fGF-23 levels associated with vascular calcification , but not with atherosclerosis , in hemodialysis patients?