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.

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

Context: Scutellaria barbata D.Don has been applied to treat cancers, inflammation and urinary disease. However, its antitumor mechanism still remains unclear.', 'With methylene chloride fraction of Herba Scutellariae barbatae (MCSB), apoptosis-related experiments were carried out on human U937 leukemia cells by (a) 2,3-bis[2-4-nitro-5-sulphophenyl]2H-tetrazolium-5-carboxanilide (XTT) assay for cytotoxicity; (b) terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling (TUNEL) assay for morphological changes; (c) cell cycle analysis; (d) Western blot analysis of poly(ADP-ribose) polymerase (PARP), caspase-8, caspase-9, caspase-3 and Bax, Bcl-2 and cytochrome c expressions for apoptosis signaling pathway.', 'MCSB inhibited the proliferation of human U937 leukemia cells in a dose-dependent manner (IC50 = approximately 10 microg/ml). MCSB dose-dependently increased the sub-G1 DNA contents by cell cycle analysis. DNA fragments indicating induction of apoptosis were observed in MCSB-treated U937 cells by TUNEL assay. Caspase-9 and caspase-3 were activated while caspase-8 was intact by MCSB. Similarly, MCSB effectively cleaved PARP, increased the ratio of Bax/Bcl-2 and released the cytochrome c from mitochondria during apoptosis in U937 cells.
Answer: Our results suggest that MCSB can induce apoptosis via the mitochondria-mediated signaling pathway.
Does methylene chloride fraction of Scutellaria barbata induce apoptosis in human U937 leukemia cells via the mitochondrial signaling pathway?

Context: Significant improvement in myocardial recovery has been shown previously with interventions to decrease reactive oxygen species after ischemia/hypoxia. We investigated whether co-administration of N-acetylcysteine (NAC, a scavenger for reactive oxygen species) and N (G)-monomethyl-L: -arginine (L-NMMA, a non-selective nitric oxide synthase inhibitor) results in better hemodynamic recovery.', 'Controlled, block-randomized study.', 'University research laboratory.', 'Mixed breed piglets (1-4d, 1.6-2.4 kg).', 'Acutely instrumented piglets received normocapnic alveolar hypoxia (10-15% oxygen) for 2 h followed by reoxygenation with 100% oxygen (1 h) then 21% oxygen (3 h). After reoxygenation, hypoxic-reoxygenated piglets were given either saline (controls), NAC [30 mg/kg bolus + 20 mg/(kg h) infusion], NMMA [0.1 mg/kg bolus + 0.1 mg/(kg h) infusion] or NAC + L-NMMA via intravenous infusion in a blinded, randomized fashion (n = 8/group). Sham-operated piglets had no hypoxia-reoxygenation (n = 5).', 'Both cardiac index and stroke volume of hypoxia-reoxygenation controls remained depressed during reoxygenation (vs. normoxic baseline, p < 0.05). Post-resuscitation treatment with L-NMMA alone did not improve systemic hemodynamic recovery, but caused pulmonary hypertension (vs. controls). In contrast, treating the piglets with either NAC or NAC + L-NMMA improved cardiac index and stroke volume, with no effect on heart rate and blood pressure (vs. controls). These treatments also decreased various oxidative stress markers in myocardial tissues (vs. controls). However, there was no significant difference between NAC- and NAC + L-NMMA groups in all examined parameters.
Answer: Post-resuscitation administration of NAC improved cardiac function and reduced oxidative stress in newborn pigs with hypoxia-reoxygenation insult. Low-dose, non-selective inhibitor of nitric oxide synthase activity did not provide any further beneficial effect.
Does post-resuscitation NOS inhibition improve hemodynamic recovery of hypoxic newborn pigs?