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Heart failure ( HF) can increase atrial fibrillation and induce cardiac hypermethylation. The homeobox gene Pitx2c plays important roles in the genesis of atrial fibrillation and the promoter region of Pitx2c contains cytosine-phosphate-guanine islands. Therefore, epigenetic modification by hypermethylation may reduce Pitx2c expression in atrial myocytes. The aim of the present study were to evaluate whether HF can modulate DNA methylation of Pitx2c and the potential mechanisms involved., We used real-time polymerase chain reaction, immunoblotting and pyrosequencing to investigate RNA and protein expression, as well as the methylation of Pitx2c, in isoproterenol-induced HF, healthy rat left atria and in HL-1 cells with and without (control) exposure to angiotensin (Ang) II (0.1 and 1 μmol/L) or isoproterenol (1 or 10 μmol/L) for 24 h., The HF atrium exhibited increased Pitx2c promoter methylation with increased DNA methyltransferase ( DNMT) 1 and decreased Pitx2c protein levels compared with the normal atrium. Angiotensin II (0.1 and 1 μmol/L), increased Pitx2c promoter methylation in HL-1 cells with increased DNMT1 and decreased Pitx2c and Kir2.1 protein levels compared with control cells. These effects were attenuated by the methylation inhibitor 5-aza-2′-deoxycytidine (0.1 μmol/L) and by the Ang II receptor blocker losartan (10 μmol/L). However, isoproterenol (1 and 10 μmol/L) did not change the expression of the Pitx2c, DNMT1 and Kir2.1 proteins., In conclusion, HF induces Pitx2c promoter hypermethylation and Ang II may contribute to the hypermethylation in HF. [ABSTRACT FROM AUTHOR]

Abstract Background and Aims: The existence of gastric metaplasia (GM) of the duodenal mucosa has been considered to be highly related to the recurrence of duodenal ulcers (DU). The aims of this study are to evaluate the usefulness of methylene blue staining in the detection of GM, and to clarify the relationship between GM and the deformity of the duodenal bulb. Methods: Fifteen patients with healed DU and four patients with symptoms of dyspepsia without evidence of ulcers were enrolled into this endoscopic study. During each endoscopy, methylene blue was sprayed evenly on the duodenal bulb, and biopsies were taken from blue-stained and unstained areas. The existence and extent of GM were assessed histologically and grossly. The correlation between duodenal bulb deformity and the extent of GM was also studied. Results: The mean score of methylene blue non-staining (MBNS) was 0, 1.30 ± 0.15, and 3.00 ± 0.00 in group A (non-ulcer patients), group B (patients with healed DU and with normal-shaped bulb) and C (patients with healed DU and with deformed duodenal bulb), respectively; showing significant differences among the groups (P < 0.05 in each). Both the existence and the grading of GM were higher in unstained specimens than in blue-stained specimens (100 vs 16.6%, P < 0.0001 and 3.62 ± 0.09 vs 0.19 ± 0.06, P < 0.001, respectively). Conclusions: Methylene blue non-staining can be applied to investigate the existence and extent of GM in the duodenal bulb accurately. The incidence of GM in the duodenal bulb was higher in patients with healed ulcers than in non-ulcer patients. Patients with deformed duodenal bulbs have a higher extent of GM than those without deformed duodenal bulbs. [ABSTRACT FROM AUTHOR]