Synaptic target selection is critical for establishing functional neuronal circuits. The mechanisms regulating target selection remain incompletely understood. We describe a role for the EGF receptor and its ligand Gurken in target selection of octopaminergic Type II neurons in the Drosophila neuromuscular system. Mutants in happyhour, a regulator of EGFR signaling, form ectopic Type II neuromu...

The effect of electrically induced auricular and ventricular tachycardia of various rates was studied in the anesthetized dog. When, the control heart ranging between 140 and 190 per minute, atrial tachycardia of a rate only slightly higher than the control rate was induced, a very temporary initial decrease in arterial blood pressure, cardiac output and coronary blood flow occurred, then all t...

The mechanism of cycle length oscillation and its role in spontaneous termination of reentry was studied in an in vitro preparation of canine atrial tissue surrounding the tricuspid orifice. Reentry occurred around a fixed path with incomplete recovery of excitability. Among 18 experiments, there was complete concordance between the occurrence of spontaneous cycle length oscillation and spontan...

Atrioventricular (A-V) conduction, ventriculo-atrial conduction and mechanism of tachycardia were studied by programmed electrical stimulation before and after the administration of ouabain in 15 patients suffering from paroxysmal supraventricular re-entrant tachycardia. In 13 patients the tachycardia circuit was confined to the A-V node. In two patients the stimulation study showed that an acc...

These studies were designed to examine the electrophysiological effects of diphenylhydantoin (Dilantin) on the heart of awake dogs. Recording electrodes were implanted over the sinoatrial node, bundle of His, and right bundle branch, and studies were performed 2 to 6 weeks following recovery. Diphenylhydantoin (10 mg/kg) increased heart rate, shortened A-V conduction time and had little or no e...

BACKGROUND In recent years, digoxin use has been on the decline, with decreased incidence of digoxin toxicity. Hence, digoxin toxicity, when it occurs, remains an elusive diagnosis to emergency physicians. OBJECTIVE To present a case of digoxin toxicity with normal levels of digoxin and serum potassium, but with severe hypomagnesemia. CASE REPORT A 66-year-old woman presented with junctiona...

Ryanodine receptor type 2 (RyR2) mutations are implicated in catecholaminergic polymorphic ventricular tachycardia (CPVT) thought to result from altered myocyte Ca(2+) homeostasis reflecting inappropriate "leakiness" of RyR2-Ca(2+) release channels arising from increases in their basal activity, alterations in their phosphorylation, or defective interactions with other molecules or ions. The la...

In animals a discrete class of small RNAs, the piwi-interacting RNAs (piRNAs), guard germ cell genomes against the activity of mobile genetic elements. piRNAs are generated, via an unknown mechanism, from apparently single-stranded precursors that arise from discrete genomic loci, termed piRNA clusters. Presently, little is known about the signals that distinguish a locus as a source of piRNAs....

Barring vague retrosternal discomfort and transient arrhythmias, no other serious complication was encountered. The arrhythmias observed were ventricular premature contractions and supraventricular ectopic beats. Atrial fibrillation occurred in a single case and brief ventricular tachycardia in 4 cases. It is important to stress that all these cardiac arrhythmias occurred only during the proced...