Antiarrhythmic and electrophysiologic effects of flecainide on acutely induced atrial fibrillation in healthy horses

BACKGROUND: Only few pharmacologic compounds have been validated for treatment of atrial fibrillation (AF) in horses. Studies investigating the utility and safety of flecainide to treat AF in horses have produced conflicting results, and the antiarrhythmic mechanisms of flecainide are not fully understood. OBJECTIVES: To study the potential of flecainide to terminate acutely induced AF of short duration (≥15 minutes), to examine flecainide‐induced changes in AF duration and AF vulnerability, and to investigate the in vivo effects of flecainide on right atrial effective refractory period, AF cycle length, and ventricular depolarization and repolarization. ANIMALS: Nine Standardbred horses. Eight received flecainide, 3 were used as time‐matched controls, 2 of which also received flecainide. METHODS: Prospective study. The antiarrhythmic and electrophysiologic effects of flecainide were based on 5 parameters: ability to terminate acute pacing‐induced AF (≥15 minutes), and drug‐induced changes in atrial effective refractory period, AF duration, AF vulnerability, and ventricular depolarization and repolarization times. Parameters were assessed at baseline and after flecainide by programmed electrical stimulation methods. RESULTS: Flecainide terminated all acutely induced AF episodes (n = 7); (AF duration, 21 ± 5 minutes) and significantly decreased the AF duration, but neither altered atrial effective refractory period nor AF vulnerability significantly. Ventricular repolarization time was prolonged between 8 and 20 minutes after initiation of flecainide infusion, but no ventricular arrhythmias were detected. CONCLUSIONS AND CLINICAL IMPORTANCE: Flecainide had clear antiarrhythmic properties in terminating acute pacing‐induced AF, but showed no protective properties against immediate reinduction of AF. Flecainide caused temporary prolongation in the ventricular repolarization, which may be a proarrhythmic effect

Splice-shifting oligonucleotide (SSO) mediated blocking of an exonic splicing enhancer (ESE) created by the prevalent c.903+469T>C MTRR mutation corrects splicing and restores enzyme activity in patient cells

The prevalent c.903+469T>C mutation in MTRR causes the cblE type of homocystinuria by strengthening an SRSF1 binding site in an ESE leading to activation of a pseudoexon. We hypothesized that other splicing regulatory elements (SREs) are also critical for MTRR pseudoexon inclusion. We demonstrate that the MTRR pseudoexon is on the verge of being recognized and is therefore vulnerable to several point mutations that disrupt a fine-tuned balance between the different SREs. Normally, pseudoexon inclusion is suppressed by a hnRNP A1 binding exonic splicing silencer (ESS). When the c.903+469T>C mutation is present two ESEs abrogate the activity of the ESS and promote pseudoexon inclusion. Blocking the 3′splice site or the ESEs by SSOs is effective in restoring normal splicing of minigenes and endogenous MTRR transcripts in patient cells. By employing an SSO complementary to both ESEs, we were able to rescue MTRR enzymatic activity in patient cells to approximately 50% of that in controls. We show that several point mutations, individually, can activate a pseudoexon, illustrating that this mechanism can occur more frequently than previously expected. Moreover, we demonstrate that SSO blocking of critical ESEs is a promising strategy to treat the increasing number of activated pseudoexon

The association between socioeconomic status and tumour stage at diagnosis of ovarian cancer: A pooled analysis of 18 case-control studies

PURPOSE: Socioeconomic status (SES) is a known predictor of survival for several cancers and it has been suggested that SES differences affecting tumour stage at diagnosis may be the most important explanatory factor for this. However, only a limited number of studies have investigated SES differences in tumour stage at diagnosis of ovarian cancer. In a pooled analysis, we investigated whether SES as represented by level of education is predictive for advanced tumour stage at diagnosis of ovarian cancer, overall and by histotype. The effect of cigarette smoking and body mass index (BMI) on the association was also evaluated. METHODS: From 18 case-control studies, we obtained information on 10,601 women diagnosed with epithelial ovarian cancer. Study specific odds ratios (ORs) with corresponding 95% confidence intervals (CI) were obtained from logistic regression models and combined into a pooled odds ratio (pOR) using a random effects model. RESULTS: Overall, women who completed ≤high school had an increased risk of advanced tumour stage at diagnosis compared with women who completed >high school (pOR 1.15; 95% CI 1.03-1.28). The risk estimates for the different histotypes of ovarian cancer resembled that observed for ovarian cancers combined but did not reach statistical significance. Our results were unchanged when we included BMI and cigarette smoking. CONCLUSION: Lower level of education was associated with an increased risk of advanced tumour stage at diagnosis of ovarian cancer. The observed socioeconomic difference in stage at diagnosis of ovarian cancer calls for further studies on how to reduce this diagnostic delay.Other Research Uni