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: Chromatin epigenetics participate in control of gene expression during metazoan development. DNA methylation and post-translational modifications (PTMs) of histones have been extensively characterised in cell types present in, or derived from, mouse embryos. In embryonic stem cells (ESCs) derived from blastocysts, factors involved in deposition of epigenetic marks regulate properties related to self-renewal and pluripotency. In the germ lineage, changes in histone PTMs and DNA demethylation occur during formation of the primordial germ cells (PGCs) to reset the epigenome of the future gametes. Trimethylation of histone H3 on lysine 27 (H3K27me3) by Polycomb group proteins is involved in several epigenome-remodelling steps, but it remains unclear whether these epigenetic features are conserved in non-mammalian vertebrates. To investigate this question, we compared the abundance and nuclear distribution of the main histone PTMs, 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) in chicken ESCs, PGCs and blastodermal cells (BCs) with differentiated chicken ESCs and embryonic fibroblasts. In addition, we analysed the expression of chromatin modifier genes to better understand the establishment and dynamics of chromatin epigenetic profiles.', 'The nuclear distributions of most PTMs and 5hmC in chicken stem cells were similar to what has been described for mammalian cells. However, unlike mouse pericentric heterochromatin (PCH), chicken ESC PCH contained high levels of trimethylated histone H3 on lysine 27 (H3K27me3). In differentiated chicken cells, PCH was less enriched in H3K27me3 relative to chromatin overall. In PGCs, the H3K27me3 global level was greatly reduced, whereas the H3K9me3 level was elevated. Most chromatin modifier genes known in mammals were expressed in chicken ESCs, PGCs and BCs. Genes presumably involved in de novo DNA methylation were very highly expressed. DNMT3B and HELLS/SMARCA6 were highly expressed in chicken ESCs, PGCs and BCs compared to differentiated chicken ESCs and embryonic fibroblasts, and DNMT3A was strongly expressed in ESCs, differentiated ESCs and BCs.\Question: Do chicken embryonic stem cells and primordial germ cells display different heterochromatic histone marks than their mammalian counterparts?

Answer: Chicken ESCs and PGCs differ from their mammalian counterparts with respect to H3K27 methylation. High enrichment of H3K27me3 at PCH is specific to pluripotent cells in chicken. Our results demonstrate that the dynamics in chromatin constitution described during mouse development is not universal to all vertebrate species.


Question: Context: The aim of this study was to assess the effect of the implementation of evidence-based guidelines and subsequent feedback to surgeons in the management of acute pancreatitis.', 'An evidence-based Pancreatitis Proforma was developed. Data were prospectively recorded (01/06/2005-30/09/2007). Audit feedback (AFB) was performed at 9 months. A final analysis was performed comparing outcomes pre- and post-audit feedback.', '372 patients were included. Median age (range) was 57 (12-96) years. 168 (45.2%) patients were admitted pre-AFB. Post-AFB, there was a significant increase in the number of patients whose diagnosis was made within 48 hours (135/168 (80.4%) vs 189/204 (92.6%), p<0.001) and who underwent definitive treatment for mild biliary pancreatitis (33/61 (54.1%) vs 56/70 (80.0%), p=0.002). Post-AFB there was also a significant reduction in the number of computed tomography (CT) scans performed for patients with mild acute pancreatitis (23/85 (27.1%) vs 13/99 (13.1%), p=0.018). Mortality (9/168 (5.4%) vs 3/204 (1.4%), p=0.040) also decreased. On multivariate analysis, AFB was an independent factor for change in the use of CT scans (p=0.015) and management of patients with mild biliary pancreatitis (p=0.039).\Question: Is closing the audit loop necessary to achieve compliance with evidence-based guidelines in the management of acute pancreatitis?

Answer: For evidence-based guidelines to be effective, feedback to surgeons is necessary.


Question: Context: Neosquamous epithelium (NSE) can arise within Barrett's esophagus as a consequence of medical or surgical acid reduction therapy, as well as after endoscopic ablation. Morphologic studies have suggested that NSE can develop from adjacent squamous epithelium, submucosal gland ducts, or multipotent progenitor cell(s) that can give rise to either squamous or Barrett's epithelium, depending on the luminal environment. The cells responsible for Barrett's epithelium self-renewal are frequently mutated during neoplastic progression. If NSE arises from the same cells that self-renew the Barrett's epithelium, the two tissues should be clonally related and share genetic alterations; if NSE does not originate in the self-renewing Barrett's, NSE and Barrett's esophagus should be genetically independent.", "We isolated islands of NSE and the surrounding Barrett's epithelium from 20 patients by microdissection and evaluated each tissue for genetic alterations in exon 2 of CDKN2A or exons 5 to 9 of the TP53 gene. Nine patients had p16 mutations and 11 had TP53 mutations within the Barrett's epithelium.", "In 1 of 20 patients, a focus of NSE had a 146 bp deletion in p16 identical to that found in surrounding Barrett's epithelium. The NSE in the remaining 19 patients was wild-type for p16 or TP53.\Question: Does neosquamous epithelium typically arise from Barrett 's epithelium?

Answer:
Our mutational data support the hypothesis that, in most circumstances, NSE originates in cells different from those responsible for self-renewal of Barrett's epithelium. However, in one case, NSE and Barrett's epithelium seem to have arisen from a progenitor cell that was capable of differentiating into either intestinal metaplasia or NSE.