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  • 1
    Electronic Resource
    Electronic Resource
    Phospholipase C isozymes selectively couple to specific neurotransmitter receptors (1997)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 389 (1997), S. 290-293 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A variety of extracellular signals are transduced across the cell membrane by the enzyme phosphoinositide-specific phospholipase C-β (PLC-β) coupled with guanine-nucleotide-binding G proteins. There are four isoenzymes of PLC-β, β1–β4, but their functions in vivo ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/38508
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Wavefront Dynamics on Transmembrane Potential Characteristics During Atrial Fibrillation (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 11 (2000), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Transmembrane Potential Characteristics. Introduction: Although computerized mapping studies have demonstrated the presence of multiple wavelets during atrial fibrillation (AF) and that action potential amplitude and duration in AF vary significantly from beat to heat, no study has correlated the single cell action potential changes with the patterns of activation during AF. Methods and Results: We studied wavefront dynamics and single cell transmembrane potential (TMP) characteristics in 12 isolated perfused canine right atria. The endocardial surface was mapped using 477 bipolar electrodes while TMP was recorded with a standard glass microelectrode from an epicardial cell. AF was induced in the presence of acetylcholine. Successful simultaneous TMP recordings and activation maps were made during six episodes of AF and for a total of 141 activations. Large variations of TMP amplitude and duration were observed frequently; 34% of them have a low amplitude (〈50% of the amplitude recorded during pacing). Low-amplitude potentials were recorded when the impaled cell was (1) in an area of random reentry (67%, n = 36); (2) within 3.2 mm of the core of organized functional reentry (22%, n = 12); (3) in the middle of two merging wavefronts (9%, n = 5); and (4) at the point of spontaneous wavebreak (2%, n = 1). Conclusion: Large variations of TMP are observed frequently during in vitro AF. Low-amplitude TMPs are associated with specific patterns of AF activation wavefronts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.2000.tb00072.x
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  • 3
    Electronic Resource
    Electronic Resource
    Relation Between Cellular Repolarization Characteristics and Critical Mass for Human Ventricular Fibrillation (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cardiovascular electrophysiology 10 (1999), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Critical Mass for Human Ventricular Fibrillation. Introduction: The critical mass for human ventricular fibrillation (VF) and its electrical determinants are unclear. The goal of this study was to evaluate the relationship between repolarization characteristics and critical mass for VF in diseased human cardiac tissues. Methods and Results: Fight native hearts from transplant recipients were studied. The right ventricle was immediately excised, then perfused (n = 6) or superfused (n = 2) with Tyrode's solution at 36° C. The action potential duration (APD) restitution curve was determined by an S1-S2 method. Programmed stimulation and burst pacing were used to induce VF. In 3 of 8 tissues, 10 μM cromakalim, au ATP-sensitive potassium channel opener, was added to the perfusate and the stimulation protocol repeated. Results show that, at baseline, VF did not occur either spontaneously or during rewarming, and it could not he induced by aggressive electrical stimulation in any tissue. The mean APD at 90% depolarization (APD90) at a cycle length of 600 msec was 227 ± 49 msec, and the mean slope of the APD restitution curve was 0.22 ± 0.08. Among the six tissues perfused, five were not treated with any antiarrhythmic agent. The weight of these five heart samples averaged 111 ± 23 g (range 85 to 138). However, after cromakalim infusion, sustained VF (〉 30 min in duration) was consistently induced. As compared with baseline in the same tissues, cromakalim shortened the APD90 from 243 ± 32 msec to 55 ± 18 msec (P 〈 0.001) and increased the maximum slope of the APD restitution curve from 0.24 ± 0.11 to 1.43 ± 0.10 (P 〈 0.01). Conclusion: At baseline, the critical mass for VF in diseased human hearts in vitro is 〉 111 g. However, the critical mass for VF can vary, as it can he reduced by shortening APD and increasing the slope of the APD restitution curve.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8167.1999.tb00280.x
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  • 4
    Electronic Resource
    Electronic Resource
    Hydride Vapor Phase Epitaxy of GaN Thick Films by the Consecutive Deposition Process Using GaCl3 (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: GaN buffer and main layers were grown by the conventional hydride vapor phase epitaxy technique using GaCl3 consecutively. The deposited buffer layers were investigated by atomic force microscopy and X-ray analysis. To examine the behavior of the buffer layers at main layer growth temperature, heat treatment was conducted at 900°C. Based on the results of the buffer layer study, GaN thick films were grown at 1050°C. Optimum deposition conditions of buffer layer from the buffer and main layer studies generally coincided. On the φ scanning pattern, the GaN films grown on (0001) Al2O3 were single-crystalline. Band-edge emission dominated photoluminescence was observed at room temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00035.x
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  • 5
    Electronic Resource
    Electronic Resource
    Spatial Dispersion of Action Potential Duration Restitution Kinetics Is Associated with Induction of Ventricular Tachycardia/Fibrillation in Humans (2004)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 15 (2004), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Action potential duration restitution (APDR) plays a role in initiation and maintenance of ventricular tachycardia (VT)/ventricular fibrillation (VF). We hypothesized that the steeply sloped APDR and its spatial heterogeneity contribute to VT/VF inducibility in patients with ventricular arrhythmia. Method and Results: After programmed ventricular stimulation (PVS) for evaluation of clinically documented VT, patients (n = 20, 15 male, age 52.5 ± 9.5 years) were divided into two groups: inducible sustained VT/VF (IVT, n = 10) and noninducible VT/VF (NVT, n = 10). Data were compared with the corresponding results obtained from normal controls (C, n = 10). Right ventricular (RV) monophasic action potential duration at 90% repolarization (APD90) and ventricular effective refractory period (VERP) in the right ventricular apex (RVA) and right ventricular outflow tract (RVOT) were determined. APDR was acquired by scanning diastole with premature ventricular beats during a pacing cycle length of 600 msec (S1-S2) in all patients and by rapid pacing at the cycle lengths that induced APD alternans in three patients. Maximal slopes (Smax) of the APDR curves and ΔAPD90 (APD90 at S2 400 ms – APD90 at the shortest S2) were measured. VERP and APD90 at each RV site did not differ among the three groups. Smax obtained by S1-S2 (1.6 ± 0.6) did not differ from Smax obtained by rapid pacing (1.2 ± 0.7), with a significant correlation noted between these values (r = 0.92, P 〈 0.01). The IVT group had a higher spatial dispersion of Smax (Smax at RVOT – Smax at RVA) compared to the C group (P 〈 0.05), with no difference between the NVT group and the IVT or C groups. The IVT group had a higher spatial dispersion of ΔAPD90 compared to the NVT and C groups (P 〈 0.01, respectively). Smax at the RVOT (2.7 ± 1.9) was steeper than that at the RVA (1.9 ± 1.2, P 〈 0.05). Inducibility of sustained VT/VF was greater at the RVOT (83.3%) than at the RVA (50.0%, P 〈 0.05). Conclusion: In patients with ventricular arrhythmia, VT/VF is highly inducible under conditions of greater spatial dispersion of ventricular refractoriness and APDR.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2004.03569.x
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  • 6
    Electronic Resource
    Electronic Resource
    Patterns of spiral tip motion in cardiac tissues (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 8 (1998), S. 137-148 
    Details
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In support of the spiral wave theory of reentry, simulation studies and animal models have been utilized to show various patterns of spiral wave tip motion such as meandering and drifting. However, the demonstration of these or any other patterns in cardiac tissues have been limited. Whether such patterns of spiral tip motion are commonly observed in fibrillating cardiac tissues is unknown, and whether such patterns form the basis of ventricular tachycardia or fibrillation remain debatable. Using a computerized dynamic activation display, 108 episodes of atrial and ventricular tachycardia and fibrillation in isolated and intact canine cardiac tissues, as well as in vitro swine and myopathic human cardiac tissues, were analyzed for patterns of nonstationary, spiral wave tip motion. Among them, 46 episodes were from normal animal myocardium without pharmacological perturbations, 50 samples were from normal animal myocardium, either treated with drugs or had chemical ablation of the subendocardium, and 12 samples were from diseased human hearts. Among the total episodes, 11 of them had obvious nonstationary spiral tip motion with a life span of 〉2 cycles and with consecutive reentrant paths distinct from each other. Four patterns were observed: (1) meandering with an inward petal flower in 2; (2) meandering with outward petals in 5; (3) irregularly concentric in 3 (core moving about a common center); and (4) drift in 1 (linear core movement). The life span of a single nonstationary spiral wave lasted no more than 7 complete cycles with a mean of 4.6±4.3, and a median of 4.5 cycles in our samples. Conclusion: (1) Patently evident nonstationary spiral waves with long life spans were uncommon in our sample of mostly normal cardiac tissues, thus making a single meandering spiral wave an unlikely major mechanism of fibrillation in normal ventricular myocardium. (2) A tendency toward four patterns of nonstationary spiral tip motion was observed. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.166294
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  • 7
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    [ASAP] Reactivity of Morita–Baylis–Hillman Adducts in C–H Functionalization of (Hetero)aryl Nitrones: Access to Bridged Cycles and Carbazoles (2018)
    American Chemical Society (ACS)
    Details
    Publication Date: 2018-07-27
    Description: Organic Letters DOI: 10.1021/acs.orglett.8b01910
    Print ISSN: 1523-7060
    Electronic ISSN: 1523-7052
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society (ACS)
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  • 8
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    Hearing preservation in patients with unilateral vestibular schwannoma who undergo stereotactic radiosurgery (2012)
    Wiley-Blackwell
    In: Cancer
    Details
    Publication Date: 2012-05-10
    Description: BACKGROUND: The objective of this study was to identify the prognostic factors for hearing preservation that would allow the more accurate stratification of patients who undergo stereotactic radiosurgery (SRS) for unilateral, sporadic vestibular schwannoma (VS). METHODS: In total, 119 patients with VS who had serviceable hearing underwent SRS as primary treatment. The mean (±standard deviation) patient age was 48 ± 11 years, and the mean (±standard deviation) follow-up duration was 55.2 ± 35.7 months. The median marginal radiotherapy dose was 12.0 grays (Gy), and the mean (±standard deviation) tumor volume was 1.95 ± 2.24 cm 3 . The mean (±standard deviation) pure tone average (PTA) score was 26 ± 12 decibels (dB) (range, 4-50 dB), and the mean (±standard deviation) maximum speech discrimination score was 91 ± 12% (range, 52-100%). The mean (±standard deviation) baseline values for the interlatency (IL) of waves I and III (IL I-III) and the IL of waves I through V (IL I-V) on auditory brainstem response were 2.58 ± 0.60 milliseconds (mS) (range, 1.92-4.30 mS) and 4.80 ± 0.61 mS (range, 3.80-6.40 mS), respectively. RESULTS: In multivariate analysis, the PTA score and IL I-V were significant and independent prognostic factors (hazard ratio, 1.072; 95% confidence interval, 1.046-1.098; P 〈 .001; and hazard ratio, 1.534; 95% confidence interval, 1.008-2.336; P = .046, respectively). By using the PTA score and IL I-V, the patients were classified into 4 groups. The ratios of patients with serviceable hearing after SRS were 89.6%, 64.0%, 25.8%, and 6.7%, respectively, in Groups A through D ( P 〈 .001). CONCLUSIONS: The current results indicated that the classification system based on using the PTA score and the IL I-V of the auditory brainstem response may be useful and specific for predicting the rate of hearing preservation in each individual. Cancer 2012. © 2012 American Cancer Society.
    Print ISSN: 0008-543X
    Electronic ISSN: 1097-0142
    Topics: Biology , Medicine
    Published by Wiley-Blackwell on behalf of The American Cancer Society.
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  • 9
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    Inhibition of CO poisoning on Pt catalyst coupled with the reduction of toxic hexavalent chromium in a dual-functional fuel cell (2014)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2014-12-13
    Description: We propose a method to enhance the fuel cell efficiency with the simultaneous removal of toxic heavy metal ions. Carbon monoxide (CO), an intermediate of methanol oxidation that is primarily responsible for Pt catalyst deactivation, can be used as an in-situ reducing agent for hexavalent chromium (Cr (VI)) with reactivating the CO-poisoned Pt catalyst. Using electro-oxidation measurements, the oxidation of adsorbed CO molecules coupled with the concurrent conversion of Cr (VI) to Cr (III) was confirmed. This concept was also successfully applied to a methanol fuel cell to enhance its performance efficiency and to remove toxic Cr (VI) at the same time. Scientific Reports 4 doi: 10.1038/srep07450
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Nature Publishing Group (NPG)
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  • 10
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    Rhodium-Catalyzed [3 + 2] Annulation of Cyclic N-Acyl Ketimines with Activated Olefins: Anticancer Activity of Spiroisoindolinones (2016)
    American Chemical Society (ACS)
    Details
    Publication Date: 2016-12-08
    Description: The Journal of Organic Chemistry DOI: 10.1021/acs.joc.6b02708
    Print ISSN: 0022-3263
    Electronic ISSN: 1520-6904
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society (ACS)
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