The Role of Endoscopy for Primary and Secondary Prophylaxis of Variceal Bleeding.

Cirrhosis is associated with a high morbidity and mortality. One of the most serious and unpredictable complication of cirrhosis, with a high mortality rate, is bleeding from esophagogastric varices. Endoscopic screening of varices followed by primary prophylactic treatment with beta blockers or band ligation in the presence of large esophageal varices will reduce the variceal bleeding rates and thereby reduce mortality risks in those with advanced cirrhosis. There is a paucity of data on primary prophylaxis of gastric varices but secondary prophylaxis includes glue injection, balloon-occluded retrograde transvenous obliteration, or transjugular intrahepatic portosystemic shunting with coil embolization.

Evaluating the global CpG methylation status of native DNA utilizing a bipartite split-luciferase sensor.

Epigenetic modifications play an essential role in the regulation of gene expression and ultimately cell fate. Methylation of cytosine at CpG dinucleotides (mCpG) is an important epigenetic mark that has been correlated with cancer when present at promoter sites of tumor suppressor genes. To develop a rapid methodology for the direct assessment of global levels of DNA methylation, we first interrogated the methyl-CpG binding domains (MBDs), the Kaiso family of Cys(2)-His(2) zinc fingers, and an SET- and RING-associated domain using a split-luciferase reassembly methodology. We identified MBD1 as the most selective domain for the discrimination between mCpG and CpG sites with over 90-fold selectivity. Utilizing a bipartite strategy, we constructed a purely methylation-dependent bipartite sensor for the direct detection of global levels of DNA methylation by attaching MBD1 domains to each of the split-luciferase halves. This new sensor was validated for the direct determination of genomic DNA methylation levels in in vitro studies without any intervening chemical or enzymatic processing of DNA. Finally, we demonstrated that this bipartite sensor can be utilized for monitoring dose-dependent changes in global levels of methylation in DNA from HeLa cells challenged with 5-aza-2'-deoxycytidine, a DNA methyltransferase inhibitor.