Publications by authors named "Paul M Kerr"

Several workflow changes were implemented in a large academic interventional radiology practice, including separation of inpatient and outpatient services, early start times, and using an adaptive learning system to predict case length tailored to individual physicians. Metrics including procedural volume, on-time start, accuracy at predicting case length, and room shutdown time were assessed before and after the intervention. Considerable improvements were seen in accuracy of first case start times, predicting block times, and last case encounter ending times.

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Nitric oxide (NO), an important endogenous signaling molecule released from vascular endothelial cells and nerves, activates the enzyme soluble guanylate cyclase to catalyze the production of cyclic guanosine monophosphate (cGMP) from guanosine triphosphate. cGMP, in turn, activates protein kinase G to phosphorylate a range of effector proteins in smooth muscle cells that reduce intracellular Ca levels to inhibit both contractility and proliferation. The enzyme phosphodiesterase type 5 (PDE5) curtails the actions of cGMP by hydrolyzing it into inactive 5'-GMP.

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Agonist-induced vasoconstriction triggers a negative feedback response whereby movement of charged ions through gap junctions and/or release of endothelium-derived (NO) limit further reductions in diameter, a mechanism termed myoendothelial feedback. Recent studies indicate that electrical myoendothelial feedback can be accounted for by flux of inositol trisphosphate (IP3) through myoendothelial gap junctions resulting in localized increases in endothelial Ca(2+) to activate intermediate conductance calcium-activated potassium (IKCa) channels, the resultant hyperpolarization then conducting back to the smooth muscle to attenuate agonist-induced depolarization and tone. In the present study we tested the hypothesis that activation of IKCa channels underlies NO-mediated myoendothelial feedback.

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Maternal carbohydrate intake is one important determinant of fetal body composition, but whether increased exposure to individual sugars has long-term adverse effects on the offspring is not well established. Therefore, we examined the effect of fructose feeding on the mother, placenta, fetus and her offspring up to 6 months of life when they had been weaned onto a standard rodent diet and not exposed to additional fructose. Dams fed fructose were fatter, had raised plasma insulin and triglycerides from mid-gestation and higher glucose near term.

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The trace amine β-phenylethylamine (PEA) is normally present in the body at low nanomolar concentrations but can reach micromolar levels after ingestion of drugs that inhibit monoamine oxidase and primary amine oxidase. In vivo, PEA elicits a robust pressor response, but there is no consensus regarding the underlying mechanism, with both vasodilation and constriction reported in isolated blood vessels. Using functional and biochemical approaches, we found that at low micromolar concentrations PEA (1-30 μM) enhanced nerve-evoked vasoconstriction in the perfused rat mesenteric bed but at a higher concentration (100 μM) significantly inhibited these responses.

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Triton X-100 (TX-100) is a nonionic detergent frequently used at millimolar concentrations to disrupt cell membranes and solubilize proteins. At low micromolar concentrations, TX-100 has been reported to inhibit the function of potassium channels. Here, we have used electrophysiological and functional techniques to examine the effects of TX-100 on another class of ion channels, L-type voltage-operated calcium channels (VOCCs).

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The vascular endothelium plays a critical role in vascular health by controlling arterial diameter, regulating local cell growth, and protecting blood vessels from the deleterious consequences of platelet aggregation and activation of inflammatory responses. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as nitric oxide (NO), and to elicit hyperpolarization of the endothelial cell membrane potential, which can spread to the surrounding smooth muscle cells via gap junctions. Endothelial hyperpolarization, mediated by activation of calcium-activated potassium (K(Ca)) channels, has generally been regarded as a distinct pathway for smooth muscle relaxation.

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The endothelium plays a critical role in controlling resistance artery diameter, and thus blood flow and blood pressure. Circulating chemical mediators and physical forces act directly on the endothelium to release diffusible relaxing factors, such as NO, and elicit hyperpolarization of the endothelial cell membrane potential, which spreads to the underlying smooth muscle cells via gap junctions (EDH). It has long been known that arterial vasoconstriction in response to agonists is limited by the endothelium, but the question of how contraction of smooth muscle cells leads to activation of the endothelium (myoendothelial feedback) has, until recently, received little attention.

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1. Modulation of vascular cell calcium is critical for the control of vascular tone, blood flow and pressure. 2.

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