A 26-year-old woman with recurrent loss of consciousness.

The case of a 26-year-old woman with congenital long QT syndrome and recurrent arrhythmic syncope which had been misdiagnosed as a seizure disorder is presented. Useful criteria for discriminating between loss of consciousness due to congenital long QT syndrome and loss of consciousness caused by seizure activity are discussed. The multiple potential causes and clinical implications of a prolonged QT interval, as well as the clinical features and management of congenital long QT syndrome are reviewed.

Calcineurin initiates smooth muscle differentiation in neural crest stem cells.

The process of vascular smooth muscle cell (vSMC) differentiation is critical to embryonic angiogenesis. However, despite its importance, the vSMC differentiation program remains largely undefined. Murine gene disruption studies have identified several gene products that are necessary for vSMC differentiation, but these methodologies cannot establish whether or not a factor is sufficient to initiate the differentiation program.