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.

Example Input: Context: A fundamental prerequisite for using degradable synthetic biopolymers as composite skin substitutes is the ability to establish vascular tissue. PEGT/PBT block-copolymer matrices have previously been shown as a favorable dermal substitute. In this study, quantitative data on neovascularization of PEGT/PBT block-copolymer matrices are presented.', 'PEGT/PBT-block-copolymer discs of three different pore diameters (1: < 75 microm, 2: 75-212 microm, 3: 250-300 microm) were implanted into dorsal skinfold chambers of balb/c mice. Histological sections were evaluated 7, 14, and 21 days post implantation by light and scanning electron microscopy. Blood vessel analysis was performed by means of digital image analysis (n = 288) of hematoxylin/eosin stained sections within apical (AOF) and basal (BOF) observation fields of the matrices.', 'Twenty-one days after implantation the density of blood vessels within the BOF of the scaffolds with a pore size of 75-212 and 250-300 microm were 4.6 +/- 0.45 and 5.8 +/- 0.62 (mean +/- S.E.M.; blood vessel profiles (BVF)), respectively. In <75 microm scaffolds, smaller numbers of BVF were found (4.2 +/- 0.39). In contrast, the evaluation within the AOF revealed significantly higher numbers of BVF in 75-212 microm group (3.5 +/- 0.49) and 250-300 microm group (4.5 +/- 0.66) as compared to the < 75 microm group (2.3 +/- 0.48).
Answer: There is evidence that the three-dimensional structure of PEGT/PBT-block-copolymer (pore size structure) influences neovascularization. The porous structures of copolymer matrices with adequate interconnection of pores (pore sizes of 75-212 and 250-300 microm) are characterized by faster ingrowth of vascular tissue.
Example Output: Does analysis of neovascularization of PEGT/PBT-copolymer dermis substitute in balb/c-mice?

Example Input: 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.
Example Output: Does preoperative posterior leaflet angle accurately predict outcome after restrictive mitral valve annuloplasty for ischemic mitral regurgitation?

Example Input: Context: The aim of this clinical study were to compare the clinical efficacy of ankaferd blood stopper (ABS) when used in combination with autogenous cortical bone graft (ACB) in the treatment of intrabony periodontal defects.', 'The study was planned as a split-mouth design. Fifteen patients with chronic periodontitis at 30 sites (six men, nine women; 42 ± 7 years) were included. Treatment sites had probing pocket depths (PPD) of ≥ 6 mm and osseous defect depths of ≥ 4 mm as radiographically assessed. Following the initial periodontal therapy, patients were randomly assigned to two treatments in contralateral areas of the dentition: ACB + ABS or ACB alone. At baseline and 6 mo after surgery, clinical parameters of plaque index, gingival index, PPD, clinical attachment level and gingival recession (GR) were recorded. The primary outcome variable was the change in clinical attachment level between baseline and 24 wk after surgery. Gingival crevicular fluid samples were collected immediately before surgery and at 2, 4, 6, 12 and 24 wk after the surgery. Gingival crevicular fluid volume was calculated and vascular endothelial growth factor levels in gingival crevicular fluid were measured.', 'PPD decreased, clinical attachment level improved and gingival index decreased significantly in response to both modes of treatment (p < 0.05). Both treatment modalities resulted in a significant gain in radiographic bone levels compared to baseline (p < 0.05). Intergroup comparisons showed that there was a significantly higher gain in clinical attachment level in the ABS/ACB group compared to ACB group (p < 0.05) with significantly less GR (p < 0.05). Similarly, vascular endothelial growth factor concentration in gingival crevicular fluid was significantly higher in the ABS/ACB group at postoperative weeks 2 and 4 compared to the ACB group (p < 0.01).
Answer: The findings suggest that ABS enhances the soft tissue healing during the periodontal defect fill by the ACB by stimulating angiogenesis and vascular endothelial cell function, prevents GR and thereby increases the clinical attachment gain.
Example Output:
Does ankaferd blood stopper enhance healing after osseous grafting in patients with intrabony periodontal defects?