Given a passage, 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: Few studies investigated the best method for removing stains from different types of resin-based composite restorations and compared them to the more recently introduced nanocomposites. This study compared the effect of four methods for stain removal from composite resins; finishing with Sof-lex disks, using pumice and brush, bleaching with 10% carbamide peroxide and 38% hydrogen peroxide.', 'Twenty disk specimens were prepared. Specimens were immersed in a staining solution for 3\xa0weeks. The stained surfaces of five specimens from each RBC material were treated with one of the treatment procedures. Colorimetric measurements were taken using spectrophotometer prior to and after staining, and then repeated after surface treatments. Color difference values were calculated.', "One-way ANOVA indicated significant differences in color change of the three composite resin materials following staining. Filtek Z250 showed the least susceptibility to discoloration followed by Renamel, Filtek Supreme was the material most prone to discoloration. Two-way ANOVA and Tukey's Post Hoc showed that all stain removing procedures except polishing with pumice, were able to return Filtek Z250 to clinically acceptable color difference. While bleaching with 38% carbamide peroxide was not effective with Renamel. Only pumice and 10% carbamide peroxide were able to return Renamel to clinically acceptable color difference.

A: Do the effectiveness of four methods for stain removal from direct resin-based composite restorative materials?
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Q: The local anesthetic properties of tetrodotoxin, a potent naturally occurring sodium channel blocker, have been recently reexamined. It was found that sciatic nerve block duration could be greatly increased and systemic toxicity greatly decreased if epinephrine was injected with tetrodotoxin. The mechanism that underlies epinephrine-mediated prolongation of tetrodotoxin nerve blocks is not known, but indirect evidence suggests that epinephrine may slow the clearance of tetrodotoxin from the site of injection. The authors hypothesized that tetrodotoxin causes vasodilatation at its injection site, which accelerates its systemic uptake, and that this vasodilatation is attenuated by coinjected epinephrine.', 'The radiolabeled microsphere technique was used to measure tissue blood flow in anesthetized rats before and after perisciatic injection of tetrodotoxin alone and in combination with epinephrine.', 'Tetrodotoxin, in a dose of 0.1 ml of a 60 microM solution, significantly increased blood flow in perisciatic muscle at the injected side compared with simultaneous contralateral control and ipsilateral preinjection baseline. Tetrodotoxin did not increase blood flow in the sciatic nerve. Coinjection of epinephrine with tetrodotoxin prevented tetrodotoxin-induced increases in perisciatic muscle blood flow over time and did not alter sciatic nerve blood flow. Arterial blood pressure was maintained with this dose of tetrodotoxin, although brain blood flow decreased. Coinjection of epinephrine with tetrodotoxin prevented decreases in brain blood flow. Higher doses of tetrodotoxin produced hypotension.

A: Does epinephrine prevent muscle blood flow increases after perineural injection of tetrodotoxin?
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Q: To determine the effect of suppression of vascular endothelial growth factor (VEGF) by monthly injection of ranibizumab on posterior retinal nonperfusion (RNP) in patients with diabetic macular edema (DME).', 'Unplanned retrospective analysis of prospectively collected data from 2 randomized, sham injection-controlled, double-masked, multicenter clinical trials.', 'Six hundred sixty-six patients with DME.', 'An independent reading center measured the area of RNP on fluorescein angiograms obtained in the phase 3 RISE and RIDE trials.', 'The percentage of patients with no posterior RNP.', 'The percentage of patients with no posterior RNP decreased in the sham group between baseline and month 24, but remained relatively stable in the 2 ranibizumab groups. After month 24, the sham group crossed over to receive monthly injections of ranibizumab 0.5 mg, and the differences between the sham and ranibizumab groups were reduced. The percentage of patients who showed an increase in posterior RNP from baseline increased over time in all 3 groups, but at a faster rate in the sham group, resulting in statistically significant differences at every time point between months 3 (9.6% vs. 18.5%; P = 0.016) and 24 (16.1% vs. 37.6%; P<0.0001) for ranibizumab 0.5 mg versus sham and from months 6 (12.3% vs. 23.0%; P = 0.013) through 24 (15.0% vs. 37.6%; P<0.0001) for ranibizumab 0.3 mg. Initiation of ranibizumab in the sham group at month 24 was followed by reduction in the percentage of patients with an increase in posterior RNP from baseline at months 30 and 36, whereas the 2 ranibizumab groups continued their gradual rise.

A:
Does neutralization of vascular endothelial growth factor slow progression of retinal nonperfusion in patients with diabetic macular edema?
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