Late presentation of arrhythmogenic right ventricular cardiomyopathy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Arrhythmogenic right ventricular cardiomyopathy is an inherited myocardial disease affecting predominantly young people and manifests as sustained ventricular tachycardia with left bundle branch block morphology, sudden death or isolated right or biventricular heart failure. However, its first manifestation as sustained ventricular tachycardia in older patients without preceding symptoms of heart failure is infrequent. To our knowledge, our patient is among the oldest reported in the literature presenting with ventricular tachycardia because of arrhythmogenic right ventricular cardiomyopathy without preceding symptoms of heart failure.</p> <p>Case presentation</p> <p>We present an unusual case of a very late presentation of a right ventricular cardiomyopathy in a 72-year-old white Caucasian man. The patient was admitted with symptoms of weakness, dizziness and chest discomfort for several hours. His electrocardiogram showed a wide-complex tachycardia with left bundle branch block morphology and left axis deviation. Because of continuing hemodynamic instability, the patient was cardioverted to sinus rhythm with a single 300 J shock. His post-cardioversion electrocardiogram, cardiac echocardiogram, coronary angiogram, magnetic resonance imaging and electrophysiological study confirmed the diagnosis of arrhythmogenic right ventricular cardiomyopathy. The patient was treated with an implantable cardioverter defibrillator and discharged on sotalol.</p> <p>Conclusion</p> <p>This case report demonstrates that arrhythmogenic right ventricular cardiomyopathy may have a very late presentation and this diagnosis should be considered as a potential cause of sustained ventricular tachycardia of right ventricular origin among the elderly and should be treated accordingly.</p

PTEN protein phosphatase activity correlates with control of gene expression and invasion, a tumor-suppressing phenotype, but not with AKT activity

The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has a well-characterized lipid phosphatase activity and a poorly characterized protein phosphatase activity. We show that both activities are required for PTEN to inhibit cellular invasion and to mediate most of its largest effects on gene expression. PTEN appears to dephosphorylate itself at threonine 366, and mutation of this site makes lipid phosphatase activity sufficient for PTEN to inhibit invasion. We propose that the dominant role for PTEN’s protein phosphatase activity is autodephosphorylation-mediated regulation of its lipid phosphatase activity. Because PTEN’s regulation of invasion and these changes in gene expression required lipid phosphatase activity, but did not correlate with the total cellular abundance of its phosphatidylinositol 3,4,5-trisphosphate (PIP3) lipid substrate or AKT activity, we propose that localized PIP3 signaling may play a role in those PTEN-mediated processes that depend on both its protein and lipid phosphatase activities. Finally, we identified a tumor-derived PTEN mutant selectively lacking protein phosphatase activity, indicating that in some circumstances the regulation of invasion and not that of AKT can correlate with PTEN-mediated tumor suppression.Deposited by bulk impor