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MAP Changes (map + change)
Selected AbstractsAtrial Fibrillation in the Goat Induces Changes in Monophasic Action Potential and mRNA Expression of Ion Channels Involved in RepolarizationJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2000HUUB M.W. VAN DER VELDEN PH.D. MAP Changes and Ion Channel Expression in Goat AF. Introduction: Sustained atrial fibrillation (AF) is characterized by a marked shortening of the atrial effective refractory period (AKRP) and a decrease or reversal of its physiolonic adaptation to heart rate. The aim of the present study was to investigate whether the AF-induced changes in AKKP in the goat are associated with changes in the atrial monophasic action potential (MAP) and whether an abnormal expression of specific ion channels underlies such changes. Methods and Results: Following thoracotomy, MAPs were recorded from the free wall of the right atrium hoth before induction of AF (control) and after cardioversion of sustained AF (>2 months) in chronically instrumented goats. In control goats. MAP duration at 80% repolarization (MAPD80) shortened (P < 0.01) from 132 ± 4 msec during slow pacing (400-msec interval) to 86 ± 10 msec during fast pacing (180 msec). After cardioversion of sustained AF, the MAPD80, during slow pacing was as short as 67 ± 5 msec (electrical remodeling). Increasing the pacing rate resulted in prolongation (P = 0.02) of the MAPD80 to 91 ± 6 msec. Also. MAPD20 (20% repolarization) shortened (P = 0.05) from 32 ± 4 msec (400 msec) to 14 ± 7 msec (180 msec) in the control goats, whereas it prolonged (P = 0.03) from 20 ± 3 msec (400 msec) to 33 ± 5 msec (180 msec) in sustained AF, mRNA expression of the L-type Ca2+ channel ,1c gene and Kv1.5 potassium channel gene, which underlie Ica, and Ikur respectively, was reduced in sustained.AF compared with sinus rhythm hy 32% (P = 0.01) and 45% (P < 0.01). respectively. No significant changes were found in the mRNA levels of the rapid Na+ channel, the Na+/Ca2+ exchanger, or the Kv4.2/4.3 channels responsible for I10. Conclusion: AF-induced electrical remodeling in the goat comprises shortening of MAPD and reversal of its physiologic rate adaptation. Changes in the time course of reploarization of the action potential are associated with changes in mRNA expression of the , subunit genes of the L.-type Ca2+ channel and the Kvl.5 potassium channel. [source] Pulse oximeter perfusion index as an early indicator of sympathectomy after epidural anesthesiaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2009Y. GINOSAR Background: The pulse oximeter perfusion index (PI) has been used to indicate sympathectomy-induced vasodilatation. We hypothesized that pulse oximeter PI provides an earlier and clearer indication of sympathectomy following epidural anesthesia than skin temperature and arterial pressure. Methods: Forty patients received lumbar epidural catheters. Patients were randomized to receive either 10 ml 0.5% bupivacaine or 10 ml 0.25% bupivacaine. PI in the toe, mean arterial pressure (MAP) and toe temperature were all assessed at baseline and at 5, 10 and 20 min following epidural anesthesia. The effect of epidural anesthesia over time was assessed by repeated measures analysis of variance. Additionally, we defined clinically evident sympathectomy criteria (a 100% increase in the PI, a 15% decrease in MAP and a 1 °C increase in toe temperature). The numbers of patients demonstrating these changes for each test were compared using the McNemar test for each time point. Results: Twenty-nine subjects had photoplethysmography signals that met a priori signal quality criteria for analysis. By 20 min, PI increased by 326%, compared with a 10% decrease and a 3% increase in MAP and toe temperature, respectively. For PI 15/29, 26/29 and 29/29 of the subjects met the sympathectomy criteria at 5, 10 and 20 min, respectively, compared with 4/29, 6/29 and 18/29 for MAP changes and 3/29, 8/29 and 14/29 for toe temperature changes. Conclusions: PI was an earlier, clearer and more sensitive indicator of the development of epidural-induced sympathectomy than either skin temperature or MAP. [source] Frequency Map Variations in Squirrel Monkey Primary Auditory Cortex,THE LARYNGOSCOPE, Issue 7 2005Steven W. Cheung MD Abstract Objective: The goal of this work is to understand the neural basis for cortical representation of hearing in highly vocal primates to gain insights into the substrates for communication. Variation patterns in frequency representation among animals are incorporated into an explanatory model to reconcile heterogeneous observations. Study Design: Prospective. Methods: Thirty-four squirrel monkeys underwent microelectrode mapping experiments in primary auditory cortex (AI) using tone pip stimuli. Characteristic frequency (CF) was extracted from the excitatory frequency receptive field. Frequency maps were reconstructed using Voronoi-Dirichlet tessellation. The spatial locations (rostral vs. caudal) of highest CF isofrequency contours (minimum length 1 mm) and highest CF neuronal clusters on the temporal gyral surface were analyzed. Results: Isofrequency contours at least 1 mm long with CFs greater than 2.9 kHz (75% cases) are accessible on the temporal gyrus. Variability of the highest CF isofrequency contours accessible on the temporal gyrus has an interquartile range from 2.9 to 5.1 (mean 4.3) kHz. The highest CF isofrequency contours are located mainly in rostral AI, whereas the highest CF neuronal clusters flanking fully expressed isofrequency contours are equally distributed in rostral and caudal locations. Conclusions: Squirrel monkey AI frequency map variations are sizeable across animals and small within single animals (interhemispheric comparison). AI frequency map variations, modeled as translations and rotations relative to the lateral sulcus, are independent transfers. Caution must be exercised when interpreting nominal frequency map changes that are attributed to hearing loss and auditory learning effects. [source] Scene-Graph-As-Bus: Collaboration between Heterogeneous Stand-alone 3-D Graphical ApplicationsCOMPUTER GRAPHICS FORUM, Issue 3 2000Bob Zeleznik We describe the Scene-Graph-As-Bus technique (SGAB), the first step in a staircase of solutions for sharing software components for virtual environments. The goals of SGAB are to allow, with minimal effort, independently-designed applications to share component functionality; and for multiple users to share applications designed for single users. This paper reports on the SGAB design for transparently conjoining different applications by unifying the state information contained in their scene graphs. SGAB monitors and maps changes in the local scene graph of one application to a neutral scene graph representation (NSG), distributes the NSG changes over the network to remote peer applications, and then maps the NSG changes to the local scene graph of the remote application. The fundamental contribution of SGAB is that both the local and remote applications can be completely unaware of each other; that is, both applications can interoperate without code or binary modification despite each having no knowledge of networking or interoperability. [source] | ||||||||||