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: HBV covalently closed circular DNA (cccDNA), the replicative intermediate responsible for persistent HBV infection of hepatocytes, is the template for transcription of all viral mRNAs. Nuclear cccDNA accumulates as a stable episome organized into minichromosomes by histone and nonhistone proteins. In this study we investigated, by a newly developed sensitive and specific assay, the relationship between viral replication and HBV chromatin assembly, transcription, and interaction with viral and cellular regulatory proteins.', 'To achieve this aim we coupled a quantitative chromatin immunoprecipitation (ChIP) technique to an established method that allows the amplification of virion-encapsidated HBV genomes after transfection of linear HBV DNA into human hepatoma HuH7 cells. The cccDNA-ChIP technique was also applied to study HBV minichromosome transcriptional regulation in liver tissue from HBV-infected patients.', 'The use of anti-acetyl-H4/-H3 specific antibodies to immunoprecipitate transcriptionally active chromatin revealed that HBV replication is regulated by the acetylation status of the cccDNA-bound H3/H4 histones. Class I histone deacetylases inhibitors induced an evident increase of both cccDNA-bound acetylated H4 and HBV replication. Finally, histones hypoacetylation and histone deacetylase 1 recruitment onto the cccDNA in liver tissue correlated with low HBV viremia in hepatitis B patients.\Question: Is hepatitis B virus replication regulated by the acetylation status of hepatitis B virus cccDNA-bound H3 and H4 histones?

A: We developed a ChIP-based assay to analyze, in vitro and ex vivo, the transcriptional regulation of HBV cccDNA minichromosome. Our results provide new insights on the regulation of HBV replication and identify the enzymatic activities that modulate the acetylation of cccDNA-bound histones as new therapeutic targets for anti-HBV drugs.
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Q: Context: Optimistic people report a higher quality of life, engage in more active coping and adopt more health-promoting behaviors than people low in optimism, ie, pessimism. We evaluated whether pessimists are more likely to show progression in carotid disease than optimists.', 'A total of 209 middle-aged healthy premenopausal women enrolled in an epidemiological study of cardiovascular risk factors and had carotid scans 10.4 years and 13.5 years later when they were at least 5 years postmenopausal. Women completed the Life Orientation Test (LOT), a measure of pessimistic and optimistic attitudes, at study entry and at the time of the first carotid scan. Analyses evaluated the association of LOT scores and change in carotid intima medial thickness (IMT) across 3 years.', 'Multiple linear regression analyses showed that the higher the pessimism scores at study entry, the greater the increase in mean IMT (beta = 0.17, p <.007). A comparison of those in the lowest quartile of LOT scores (most optimistic) with those in the other three quartiles showed that the most optimistic group had less progression than the remaining more pessimistic women (mean percent increase = 1.3 and 6.0 for mean IMT, F = 15.4, p <.001). Women who were chronically optimistic at study entry and at the first carotid scan (bottom quartiles at both times) had less progression in mean IMT than did those who were chronically pessimistic (top quartiles at both times).\Question: Do optimistic attitudes protect against progression of carotid atherosclerosis in healthy middle-aged women?

A: Optimistic women are less likely to show progression of carotid disease in mid-life than are pessimists.
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Q: Context: We evaluated the prognostic value of mid-regional proadrenomedullin (MR-proADM) in atrial fibrillation (AF) patients undergoing radiofrequency ablation.', 'Plasma concentrations of MR-proADM were measured at baseline and after 12months in 87 AF patients in whom radiofrequency ablation was performed. The association between MR-proADM and AF recurrence was tested by univariable and multivariable Cox models.', 'In all 87 patients radiofrequency ablation was successfully performed. Of the total population 54% had paroxysmal AF. The mean left ventricular ejection fraction was 54% (minimum 25%). After 12months of follow-up, 71% of the patients were free of AF recurrence. At baseline, mean MR-proADM in the total population was 0.72nmol/l±0.22. Patients with AF recurrence had significantly higher baseline MR-proADM (0.89nmol/l±0.29) as compared with patients without AF recurrence (0.65nmol/l±0.14; p<0.001). After 12months, mean MR-proADM plasma concentration remained higher in patients with AF recurrence (0.81nmol/l±0.22 as compared with patients free of AF 0.54nmol/l±0.20; p<0.001). Receiver operating characteristic (ROC) curve analysis for MR-proADM yields a specificity of 98% and a sensitivity of 64% with an optimal cut-off value of 0.82nmol/l to predict recurrence of AF after catheter ablation. In the logistic regression analysis only MR-proADM remained independently predictive for AF recurrence.\Question: Do mid-regional proadrenomedullin levels predict recurrence of atrial fibrillation after catheter ablation?

A:
This is the first study revealing the association between MR-proADM elevation before ablation and poor outcomes after ablation of AF. Larger studies are needed to validate these results.
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