Publications by authors named "Jonathan Hassel"

Apamin-sensitive small-conductance Ca-activated K (SK) current ( I) is encoded by Ca-activated K channel subfamily N ( KCNN) genes. I importantly contributes to cardiac repolarization in conditions associated with reduced repolarization reserve. To test the hypothesis that I inhibition contributes to drug-induced long QT syndrome (diLQTS), we screened for KCNN variants among patients with diLQTS, determined the properties of heterologously expressed wild-type (WT) and variant KCNN channels, and determined if the 5-HT receptor antagonist ondansetron blocks I.

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Background: We recently reported that skin sympathetic nerve activity (SKNA) can be used to estimate sympathetic tone in humans. In animal models, vagal nerve stimulation (VNS) can damage the stellate ganglion, reduce stellate ganglion nerve activity, and suppress cardiac arrhythmia. Whether VNS can suppress sympathetic tone in humans remains unclear.

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Background: Sympathetic nerve activity is important to cardiac arrhythmogenesis.

Objective: The purpose of this study was to develop a method for simultaneous noninvasive recording of skin sympathetic nerve activity (SKNA) and electrocardiogram (ECG) using conventional ECG electrodes. This method (neuECG) can be used to adequately estimate sympathetic tone.

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Objectives: To reevaluate risk factors for high defibrillation threshold (DFT) and propose a risk assessment tool.

Background: Controversy exists over routine DFT testing during implantable cardioverter defibrillator (ICD) placement.

Methods: We retrospectively analyzed 1,642 consecutive patients who received an ICD and underwent DFT testing.

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Administration of the glucagon-like peptide-1 (GLP-1) receptor agonists GLP-1 and exendin-4 (Ex-4) directly into the central nervous system decreases food intake. But although Ex-4 potently suppresses food intake after peripheral administration, the effects of parenteral GLP-1 are variable and not as strong. A plausible explanation for these effects is the rapid inactivation of circulating GLP-1 by dipeptidyl peptidase-4 (DPP-4), an enzyme that does not alter Ex-4 activity.

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Two-partner secretion (TPS) systems are a family of proteins being rapidly identified and characterized in a growing number of gram-negative bacteria. TPS systems mediate the secretion of proteins, many involved in virulence traits such as hemolysis, adherence to epithelial cells, inhibition of bacterial growth, and immunomodulation of the host. A TPS system typically consists of a transporter located in the bacterial outer membrane (OM) which is responsible for the recognition and secretion of at least one large exoprotein.

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