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.
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Question: 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?

Answer: 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.

Question: Context: Proliferation of smooth muscle cells (SMCs) plays an important role in vascular pathobiology, being involved in the development of coronary restenosis and atherosclerosis. The activation of nuclear proto-oncogenes appears to be a final common pathway onto which various mitogenic signals coverage. Accordingly, we attempted to determine whether the activation of the c-myc nuclear proto-oncogene is essential for human SMC proliferation and explored the possibility of inhibiting their growth using antisense oligonucleotides directed against c-myc messenger RNA (mRNA).', 'Proliferation of human SMCs was associated with an increase in c-myc mRNA expression after growth stimulation. Using 15-mer phosphorothioate oligonucleotides (oligomers), we tested their growth-inhibitory effect in SMCs in vitro. Antisense oligomers directed against the translation initiation region of the human c-myc gene exhibited a significant antiproliferative effect, whereas sense and mismatched oligomers did not inhibit the growth. The growth-inhibitory effect of c-myc antisense oligomers was dose dependent and preventable by an excess of sense oligomers. Furthermore, growth inhibition of SMCs treated with c-myc antisense oligomers was associated with a marked decrease in the c-myc mRNA level. Phosphorothioate oligomers remained stable in medium containing 20% serum and were detectable in SMCs as early as 1 hour after cell exposure. Intact oligomers rapidly accumulated intracellularly and persisted within human SMCs for at least 16 hours.\Question: Does downregulation of c-myc expression by antisense oligonucleotides inhibit proliferation of human smooth muscle cells?

Answer: c-myc antisense oligomers reduced c-myc expression and produced a significant growth inhibition of human SMCs, indicating an important role of c-myc gene activation in the process of SMC proliferation. Furthermore, extracellular stability and rapid cellular uptake provide the basis for future studies assessing the therapeutic role of the c-myc antisense approach in reducing SMC proliferation in the process of vascular restenosis.

Question: Context: During the first trimester of pregnancy, HIV-1 mother-to-child transmission is relatively rare despite the permissivity of placental cells to cell-to-cell HIV-1 infection. The placenta interacts directly with maternal uterine cells (decidual cells) but the physiological role of the decidua in the control of HIV-1 transmission and whether decidua could be a source of infected cells is unknown.', 'To answer to this question, decidual mononuclear cells were exposed to HIV-1 in vitro. Decidual cells were shown to be more susceptible to infection by an R5 HIV-1, as compared to an X4 HIV-1. Infected cells were identified by flow cytometry analysis. The results showed that CD14(+) cells were the main targets of HIV-1 infection in the decidua. These infected CD14(+) cells expressed DC-SIGN, CD11b, CD11c, the Fc gamma receptor CD16, CD32 and CD64, classical MHC class-I and class-II and maturation and activation molecules CD83, CD80 and CD86. The permissivity of decidual tissue was also evaluated by histoculture. Decidual tissue was not infected by X4 HIV-1 but was permissive to R5 HIV-1. Different profiles of infection were observed depending on tissue localization.\Question: Do antigen-presenting cells represent targets for R5 HIV-1 infection in the first trimester pregnancy uterine mucosa?

Answer:
The presence of HIV-1 target cells in the decidua in vitro and the low rate of in utero mother-to-child transmission during the first trimester of pregnancy suggest that a natural control occurs in vivo limiting cell-to-cell infection of the placenta and consequently infection of the fetus.