Pacing Features That Mimic Malfunction: A Review of Current Programmable and Automated Device Functions That Cause Confusion in the Clinical Setting

Modern implantable devices capable of pacing are armed with a multitude of programmable and automated features. While some features represent important advances in device safety and performance, many can also mimic device malfunction. This article discusses these features in terms of the confusion they may cause and highlights important clinical clues that aid in their recognition.     

Endothelium‐dependent Vasodilation in Myogenically Active Mouse Skeletal Muscle Arterioles: Role of EDH and K+ Channels

As smooth muscle cell (SMC) membrane potential (E_m) is critical for vascular responsiveness, and arteriolar SMCs are depolarized at physiological intraluminal pressures, we hypothesized that myogenic tone impacts on dilation mediated by endothelium‐derived hyperpolarization (EDH). Studies were performed on cannulated mouse cremaster arterioles [diameter, 33±2 μm (n=23) at 60 mmHg; SMC Em ‐34.6±1.2 mV (n=7)]. Myogenic activity was assessed as tone developed in response to intraluminal pressure. Functional observations were related to mRNA, protein expression, and anatomy. Acetylcholine concentration‐response curves showed a modest shift following indomethacin (10 μM) and L‐NAME (100 μM), although maximal vasodilation was achieved. Residual dilation was removed by apamin (1 μM) in combination with TRAM‐34 (1 μM) or charybotoxin (0.1 μM), indicating the requirement of small (S) and intermediate (I) calcium‐activated potassium channels (K_Ca). Charybdotoxin, but not TRAM‐34, caused vasoconstriction, presumably through the inhibition of SMC BK_Ca. Expression of SK3 and IK1 was confirmed by immunohistochemistry and polymerase chain reaction, while myoendothelial junctions were common, suggesting a high degree of cell coupling. Also consistent with a role for endothelial K_Ca channels, acetylcholine increased endothelium [Ca²⁺]_i. Apamin and TRAM‐34 similarly blocked EDH‐mediated dilation at intraluminal pressures of 30 and 90 mmHg, suggesting that in mouse arterioles, SK_{Ca ‐} and IK_{Ca ‐} mediated mechanisms predominate and operate independently of physiological levels of myogenic activation.     

Primary Cutaneous Aspergillosis in an Immunocompetent Patient: Successful Treatment with Oral Voriconazole

Abstract:   We report a case of primary cutaneous aspergillosis in an immunocompetent child that responded rapidly to oral voriconazole therapy. Voriconazole may be considered as a treatment option for pediatric patients with primary cutaneous aspergillosis.     

The effect of 40 h constant wakefulness on task-switching efficiency

This study investigated efficiency of switching between different tasks in 12 male participants (19–30 years) during 40 h of constant wakefulness. As index of task-switching efficiency, switch costs in reaction time were assessed every 3 h under controlled behavioural and environmental conditions. Overall reaction times and switch costs showed a temporal pattern consistent with the assumption of a combined influence of a sleep homeostatic and a circadian process. An additional analysis indicated that the variation in switch costs could not be attributed to interference of the current task with persisting activation from preceding tasks. We therefore conclude that sleep loss and the circadian system affect the ability to prepare the current task rather than automatic processing of irrelevant stimulus information.