In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

Q: Context: The caudal-type homeodomain transcriptional factor CDX2, a member of the caudal-related homeobox gene family, plays a crucial role in the regulation of cell proliferation and differentiation in the gut. Recent studies have reported that expression of CDX2 was an independent marker of outcome in patients with resected adenocarcinoma of ampulla of Vater, gastric cancer, and colon cancer. The clinicopathological significance of CDX2 expression has hitherto remained unclear in biliary tract carcinoma (BTC). The aim of this study was to determine whether CDX2 expression in BTC indicates clinical outcome.', 'The expression of CDX2 was investigated immunohistochemically in surgically resected specimens from 164 patients with BTC, including 74 intrahepatic cholangiocarcinomas, 49 extrahepatic cholangiocarcinomas, and 41 gallbladder carcinomas. The correlation between expression of CDX2 and clinicopathological factors, including overall survival, tumor location, tumor stage, and degree of tumor differentiation, was examined in patients with BTC.', 'In total, 27 of the 164 (16.46%) patients with BTC expressed CDX2. The frequency of CDX2 expression was much higher in the extrahepatic cholangiocarcinomas (22.45%) and gallbladder carcinomas (29.27%) than in the intrahepatic cholangiocarcinomas (5.41%), the difference being statistically significant (P = 0.002). Factors influencing survival on univariate analysis were tumor stage (P < 0.00001), degree of tumor differentiation (P = 0.0002), and CDX2 expression (P = 0.01). On multivariate analysis using the Cox proportional hazard model, CDX2 expression and tumor stage were independent prognostic factors in patients with BTC.\Question: Is expression of the caudal-type homeodomain transcription factor CDX2 related to clinical outcome in biliary tract carcinoma?

A: Expression of CDX2 was an independent indicator of outcome in patients with BTC in addition to tumor stage and tumor differentiation. The mechanism by which CDX2 expression influences behavior of biliary tract carcinoma needs further investigation.
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Q: Context: Serum ferritin concentration >100\xa0ng/mL was associated with a higher risk of death in hemodialysis patients in Japan, whereas such an association was less clear in hemodialysis patients in Western countries. Since Japanese dialysis patients are generally less inflamed than those in Western countries, inflammation may modify the association between serum ferritin and the adverse outcomes.', 'We performed an observational cohort study using data from 2606 Japanese hemodialysis patients who participated in the Dialysis Outcomes and Practice Patterns Study (DOPPS) III (2005-2008) or DOPPS IV (2009-2012). The predictor was serum ferritin category (<50, 50-99.9, 100-199.9, and ≥200\xa0ng/mL), and the primary and secondary outcomes were all-cause mortality and cardiovascular hospitalization, respectively. C-reactive protein (CRP, cut-off by 0.3\xa0mg/dL) and serum albumin (cut-off by 3.8\xa0g/dL) were stratification factors related to systemic inflammation.', 'After adjustment for relevant confounding factors, a U-shaped association was observed between serum ferritin and all-cause mortality in the group with low CRP levels, whereas such relationship was not significant in the high CRP counterparts. In contrast, we found a linear association between serum ferritin and cardiovascular hospitalization in the low CRP and high CRP groups commonly. Similar results were obtained when the total cohort was stratified by serum albumin.\Question: Do both low and high serum ferritin levels predict mortality risk in hemodialysis patients without inflammation?

A: Serum ferritin showed different patterns of association with all-cause mortality in hemodialysis patients with versus without inflammation, whereas its association with cardiovascular hospitalization was similar regardless of inflammatory conditions.
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Q: Context: Tetrodotoxin (TTX) is used to distinguish between two classes of voltage-gated sodium channel (VGSC)--TTX sensitive (TTXS) and TTX resistant (TTXR). The resistance of TTXR VGSCs is thought to result from a low binding affinity of TTX, although at high TTX concentrations channel block does occur. Here, we show that, at concentrations below those which produce block, TTX can bind to TTXR VGSCs.', 'Whole-cell voltage clamp recordings were made from dissociated rat dorsal root ganglion neurones that expressed both TTXS and TTXR sodium currents. Voltage-gated calcium currents were blocked by 10 microM extracellular lanthanum chloride. TTXS, but not TTXR, current was suppressed by using a holding potential of -50 mV, and the effect of TTX on the isolated TTXR current was explored.', 'Extracellular application of 0.5 microM TTX produced a 40% increase in TTXR current amplitude, a negative shift in the voltage-dependence of current activation (approximately -8 mV) and inactivation (approximately -10 mV) and increased rates of current activation and inactivation. The effect of TTX on current amplitude was dose-dependent (EC50 = 364 nM). Removal of lanthanum prevented the effect of TTX on TTXR current amplitude, whereas reducing extracellular calcium did not.\Question: Do low concentrations of tetrodotoxin interact with tetrodotoxin-resistant voltage-gated sodium channels?

A:
The findings are consistent with an interpretation that TTX relieves a tonic block of the TTXR VGSC by lanthanum. We conclude that TTX binds to the TTXR VGSC at low concentrations, without blocking it. This appears to be the first demonstration of a clear distinction between binding affinity and blocking potency of a channel-blocking agent.
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