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.

To describe the novel use of a chorioretinal biopsy technique to confirm the microbiological diagnosis of endogenous Escherichia coli (E. coli) endophthalmitis, when other investigations have been proven nondiagnostic.', 'Case report of an 82-year-old white man with endogenous endophthalmitis without a clearly identifiable source of infection.', 'After systemic cultures and multiple aqueous and vitreous samples were unable to identify a causative organism, chorioretinal biopsy of a subretinal abscess was used to confirm the microbiological diagnosis. This ensured appropriate ophthalmic and systemic treatment of infection.
Do cHORIORETINAL BIOPSY FOR THE DIAGNOSIS OF ENDOGENOUS ENDOPHTHALMITIS DUE TO ESCHERICHIA COLI?

Endoscopic snare papillectomy (ESP) is a viable alternative to surgical treatment of ampullary adenomas and T1N0 stage ampullary carcinomas. The main drawback of this technique is the high risk of acute pancreatitis post procedure.The aim of this study was to assess the efficacy, safety, and long-term results of this procedure, and to determine whether routine pancreatic intubation facilitated by intraductal methylene blue (MB) injection reduces the risk for pancreatitis.', 'Between 2004 and 2011, 56 consecutive patients underwent ESP. Before resection, the pancreatic duct was cannulated, and MB was injected intraductally to facilitate stent placement after ampullectomy.', 'ESP was performed en bloc in 45 patients with histological findings of low-grade dysplasia (39%), high-grade dysplasia (25%), carcinoma (32.5%), and others (3.5%). The morbidity rate was 19.5%: acute pancreatitis (n=6), bleeding (n=4), perforation (n=1), and sepsis (n=1). Pancreatic intubation was performed in 89% of the patients. Postprocedure pancreatitis occurred significantly less in the patients with a pancreatic stent than in those without: 3/49 versus 3/6, P=0.013. ESP was considered as curative in 39 patients (75%). Of the 12 recurrences (25%), 10 were managed endoscopically, but with higher morbidity (acute pancreatitis=40%).
Does pancreatic intubation facilitated by methylene blue injection decrease the risk for postpapillectomy acute pancreatitis?

Human plasma factor XI is a homodimer, with each monomer comprising a catalytic domain and four homologous 'apple' domains. The monomers bind to each other through non-covalent bonds and through a disulfide bond between Cys321 residues in apple 4 domains.", 'To identify residues essential for dimerization in the FXI monomer interface.', 'Specificity-determining residues in apple 4 domains were sought by sequence alignment of FXI and prekallikrein apple domains in different species. Specific residues identified in apple 4 domains were mutagenized and expressed in baby hamster kidney (BHK) cells for evaluation of their effect on FXI dimerization, analyzed by non-reduced sodium dodecylsulfate polyacrylamide gel electrophoresis and size-exclusion chromatography.', 'Among the 19 residues of the FXI monomer interface, Leu284, Ile290 and Tyr329 were defined as specificity-determining residues. Substitutions of these residues or pairs of residues did not affect FXI synthesis and secretion from transfected BHK cells, but did impair dimerization, despite the presence of cysteine at position 321. The double mutant 284A/290A yielded predominantly a monomer, whereas all other single or double mutants yielded monomers as well as disulfide-bonded dimers.
Do three residues at the interface of factor XI ( FXI ) monomers augment covalent dimerization of FXI?