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.
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Question: Context: Although the presence of perineural invasion has been recognized as a poor prognostic factor in extrahepatic cholangiocarcinoma, the molecular mechanisms of perineural invasion in extrahepatic cholangiocarcinoma remain unclear. Nerve growth factor has been reported to be a candidate predictive biomarker of perineural invasion in some cancers.', 'To investigate the impact of intratumoral nerve growth factor expression in resected extrahepatic cholangiocarcinoma on survival.', 'Intratumoral nerve growth factor expression was investigated immunohistochemically in 112 patients with resected extrahepatic cholangiocarcinoma. Associations between nerve growth factor expression and clinicopathological factors were statistically evaluated, and risk factors for poor survival were analyzed using univariate and multivariate analyses.', 'High and low nerve growth factor expression was observed in 62 (55%) and 50 (45%) patients, respectively. For all 112 patients, no significant correlation was found between nerve growth factor expression and presence of perineural invasion (P = 0.942). Moreover, nerve growth factor expression was not associated with recurrence-free survival (P = 0.861) and overall survival (P = 0.973). In multivariate analysis, lymph node metastasis (P = 0.004) was identified as an independent risk factor for early recurrence and the presence of perineural invasion (P = 0.002) and lymph node metastasis (P < 0.001) was identified as independent risk factors for poor survival.
Answer: Intratumoral nerve growth factor expression is not associated with perineural invasion or recurrence-free and overall survival in patients with resected extrahepatic cholangiocarcinoma.

Answer: Is nerve Growth Factor Expression Associated with Perineural Invasion in Extrahepatic Cholangiocarcinoma?

Question: Context: The use of sedation allows medical procedures to be performed outside the operating room while ensuring patient comfort and a controlled environment to increase the yield of the procedure. There is concern about a higher risk of adverse events with use of sedation in patients with obstructive sleep apnea.', 'We aimed to determine if the presence of obstructive sleep apnea increased the risk of hospitalization and/or health care use after patients received moderate conscious sedation for an elective, ambulatory colonoscopy.', 'We conducted a retrospective case-control database and chart review study. We compared hospital admissions, intensive care unit (ICU) admissions, and emergency room visits at 24 hours, 7 days, and 30 days in patients with obstructive sleep apnea (n=3,860) and without obstructive sleep apnea (n=2,374) who had undergone an elective, ambulatory colonoscopy with sedation.', 'We found no significant differences in hospital admissions, ICU admissions, or emergency room visits between the two groups at any time point within the 30 days following the procedures. In a sensitivity analysis in which we compared 827 individuals with polysomnographically confirmed sleep apnea with control subjects, there was still no difference in hospital admissions, ICU admissions, or emergency room visits in the 30 days after receiving sedation for the procedure. Outcomes were not different in individuals with various severities of obstructive sleep apnea.
Answer: The presence of obstructive sleep apnea was not associated with increased early hospital admissions, ICU admissions, or emergency room visits after colonoscopy with sedation.

Answer: Is obstructive Sleep Apnea Associated with Higher Health Care Use after Colonoscopy under Conscious Sedation?

Question: Context: To determine whether frontal white matter diffusion abnormalities can help predict acute executive function impairment after mild traumatic brain injury (mTBI).', 'This study had institutional review board approval, included written informed consent, and complied with HIPAA. Diffusion-tensor imaging and standardized neuropsychologic assessments were performed in 20 patients with mTBI within 2 weeks of injury and 20 matched control subjects. Fractional anisotropy (FA) and mean diffusivity (MD) images (imaging parameters: 3.0 T, 25 directions, b = 1000 sec/mm(2)) were compared by using whole-brain voxelwise analysis. Spearman correlation analyses were performed to evaluate associations between diffusion measures and executive function.', 'Multiple clusters of lower frontal white matter FA, including the dorsolateral prefrontal cortex (DLPFC), were present in patients (P < .005), with several clusters also demonstrating higher MD (P < .005). Patients performed worse on tests of executive function. Lower DLPFC FA was significantly correlated with worse executive function performance in patients (P < .05).
Answer: Impaired executive function following mTBI is associated with axonal injury involving the DLPFC.

Answer:
Does diffusion-tensor imaging implicate prefrontal axonal injury in executive function impairment following very mild traumatic brain injury?