No abstract

Background-In patients with paroxysmal atrial fibrillation (AF), catheter ablation maintains sinus rhythm more effectively than antiarrhythmic drugs (AADs), but its effect on symptoms and quality of life (QOL) has not been fully characterized. Methods and Results-We evaluated symptoms and QOL in a multicenter, randomized trial comparing catheter ablation with AADs as second-line treatment for patients with paroxysmal AF. The Short Form (SF)-36 health survey and the AF Symptom Checklist were administered at baseline and 3, 6, and 9 months after a blanking or dose-titration period.The primary between-group comparisons were conducted at 3 months because of permitted crossover from AAD to ablation beyond this time. Additional analyses based on subsequent follow-up were performed, including the construction of mixed linear regression models to assess the impact of multiple factors on follow-up QOL scores. At baseline in both the ablation (nϭ103) and the AAD (nϭ56) groups, 7 of 8 SF-36 scales were well below population norms, as were the physical (PCS) and mental (MCS) summary scores. At 3 months, the same 7 SF-36 scales were significantly (PϽ0.01) higher in the ablation than in the AAD group, as were the PCS (52.0Ϯ7.

B-cell lymphoma 2 (Bcl-2) family proteins are established regulators of cell survival, but their involvement in the normal function of primary cells has only recently begun to receive attention. In this study, we demonstrate that chemical and genetic loss-of-function of antiapoptotic Bcl-2 and Bcl-xL significantly augments glucose-dependent metabolic and Ca2+ signals in primary pancreatic β-cells. Antagonism of Bcl-2/Bcl-xL by two distinct small-molecule compounds rapidly hyperpolarized β-cell mitochondria, increased cytosolic Ca2+, and stimulated insulin release via the ATP-dependent pathway in β-cell under substimulatory glucose conditions. Experiments with single and double Bax–Bak knockout β-cells established that this occurred independently of these proapoptotic binding partners. Pancreatic β-cells from Bcl-2−/− mice responded to glucose with significantly increased NAD(P)H levels and cytosolic Ca2+ signals, as well as significantly augmented insulin secretion. Inducible deletion of Bcl-xL in adult mouse β-cells also increased glucose-stimulated NAD(P)H and Ca2+ responses and resulted in an improvement of in vivo glucose tolerance in the conditional Bcl-xL knockout animals. Our work suggests that prosurvival Bcl proteins normally dampen the β-cell response to glucose and thus reveals these core apoptosis proteins as integrators of cell death and physiology in pancreatic β-cells.