bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catheter Tip Cooling During Radiofrequency Ablation of Intra‐Atrial Reentry: Effects on Power, Temperature, and Impedance
Authors: BLAUFOX ANDREW D. , NUMAN MOHAMED T. , LAOHAKUNAKORN PREECHA , KNICK BARBARA , PAUL THOMAS , SAUL J. PHILIP 
Published: August 2003

Catheter Tip Cooling.
Introduction: Cooling the catheter tip either passively with increased tip size or actively during radiofrequency catheter ablation (RFCA) has been shown in canine thigh preparations to create larger lesions than standard catheter tips, yielding a theoretical advantage for improving the outcome of RFCA for intra‐atrial reentrant tachycardia (IART). Methods and Results: The pediatric RFCA database at the Medical University of South Carolina was reviewed for RFCA of IART in patients with structural heart disease. From a total of 31 patients who underwent procedures during the study period, 8 patients in whom ablation with conventional ablation techniques failed and who went on to passive cooling with an 8‐mm tip catheter or active cooling with an internally cooled‐tip catheter were studied. Power delivery was greater but temperature and impedance were lower during cooled ablation than during conventional ablation. Passive cooling was associated with higher power than active cooling. These changes in RF biophysical characteristics were associated with successful elimination of 11 of 13 IART circuits in 7 of 8 patients. Conclusion: Cooling during RF ablation of atrial tachycardia clearly yielded greater power delivery in vivo and was associated with success.
Increased Intermittency and Decreased Nonstationarity of Heart Rates During the Daytime in Patients with Neurocardiogenic Syncope
Authors: YUM MYUNG‐KUL , KIM JUNE SOO 
Published: August 2003

Intermittency and Nonstationarity in Syncope.
Introduction: During head‐up tilt (HUT) test, patients with neurocardiogenic syncope show a sudden severe decrease in heart rate at the beginning of their induced syncopal attacks (termed intermittency). They also exhibit slow and progressive increases in their mean heart rates long before the induced syncopal attacks (termed nonstationarity). The aim of this study was to test our hypothesis that during daily activity, although not as prominently as during HUT test, patients show different degrees of intermittency and nonstationarity compared to healthy persons. Method and Results: Thirty patients with a positive HUT test and 30 healthy controls without a history of syncope were studied. The RR intervals of their 24‐hour ambulatory ECGs were analyzed. To quantify the intermittency (C1) and nonstationarity (H1) behavior, multifractal analysis was performed using Mexican hat and Haar wavelet function, respectively. In the syncope group, C1 and H1 were significantly higher at 6 A.M.–6 P.M. and lower at 6 A.M.–midnight, respectively. However, the values were not different at midnight–6 A.M. The significant night‐day circadian change shown in the control group was lost in C1 and diminished in H1. Conclusion: Patients with neurocardiogenic syncope show increased intermittency and decreased nonstationarity of heart rates in the daytime during daily activity, and abnormal night‐day circadian changes of the intermittency and nonstationarity. These findings may be useful in the early identification of patients with neurocardiogenic syncope and in the investigation of abnormalities in heart rate regulating mechanisms.
Unidirectional Conduction Block at Cavotricuspid Isthmus Created by Radiofrequency Catheter Ablation in Patients With Typical Atrial Flutter
Authors: MATSUSHITA TAKEHIKO , CHUN SUNG , LIEM L. BING , FRIDAY KAREN J. , SUNG RUEY J. 
Published: August 2003

Unidirectional Block at Cavotricuspid Isthmus.
Introduction: Although unidirectional conduction block at the cavotricuspid isthmus can be created by radiofrequency ablation for atrial flutter, its underlying mechanism has not been elucidated. Methods and Results: Twenty‐seven patients (22 men and 5 women; mean age 59 ± 11 years) who met the following criteria were studied: (1) bidirectional isthmus conduction demonstrable at baseline; (2) at least one linear lesion attempted on the cavotricuspid isthmus with radiofrequency catheter ablation; and (3) conduction times at anterolateral and posteromedial portions of the isthmus measured for both clockwise and counterclockwise directions before the ablation procedure. Unidirectional conduction block was observed before achieving bidirectional block in 9 patients (group I); the remaining 18 patients did not exhibit unidirectional conduction block (group II). All unidirectional conduction blocks were demonstrated in the counterclockwise direction. Anterolateral isthmus conduction time in group I was significantly longer than that in group II in both directions. However, there were no significant differences in posteromedial isthmus conduction time between groups I and II in either direction. Anterolateral isthmus conduction time was significantly longer than posteromedial conduction time in group I but not in group II. Conclusion: There were significant differences in conduction properties at the cavotricuspid isthmus between patients who developed unidirectional conduction block and those who did not. Our results support the notion that anisotropy contributes to the genesis of unidirectional conduction block at the cavotricuspid isthmus during the radiofrequency ablation procedure.
Effect of Shock‐Induced Changes in Transmembrane Potential on Reentrant Waves and Outcome During Cardioversion of Isolated Rabbit Hearts
Authors: EVANS FREDERICK G. , IDEKER RAYMOND E. , GRAY RICHARD A. 
Published: August 2003

Shock Effects on Reentry.
Introduction: Although numerous theories exist for the mechanisms of defibrillation, experimental data directly relating these mechanisms to the termination of reentry in whole hearts are lacking. Methods and Results: Using video imaging technology, we recorded ~5,000 optical action potentials simultaneously from the anterior and posterior ventricular epicardium of rabbit hearts during cardioversion of stable reentrant arrhythmias. Monophasic shocks at three strengths for each polarity were delivered between electrodes inside the right ventricle (RV) and above the left atrium. Cardioversion efficacy at the three strengths was 21%, 42%, and 92% for RV+ shocks, which primarily depolarized the epicardium, and 10%, 15%, and 33% for RV– shocks, which primarily hyperpolarized the epicardium. The mechanism of cardioversion for RV+ shocks was elimination of excitable gaps and reentry via excitation ahead of wavefronts and action potential prolongation at wavetails, both of which increased with shock strength. Partial elimination of these gaps resulted in resetting of preshock reentry and/or induction of new reentry. RV– shocks cardioverted primarily via deexcitation, which terminated reentry by creating new postshock wavefronts via break excitation that rapidly activated excitable gaps. Outcome was dependent on the preshock state for both polarities at strengths near the 50% success level. Before successful shocks, more epicardium was recovered, resulting in more excitation and longer postshock depolarization (RV+ shocks) and faster postshock elimination of excitable gaps (RV– shocks). Conclusion: These findings provide a direct mechanistic link between shock‐induced changes in Vm and the effect of polarity, strength, and timing on cardioversion efficacy.
Mathematical Model of the Rapidly Activating Delayed Rectifier Potassium Current IKr in Rabbit Sinoatrial Node
Authors: OEHMEN CHRISTOPHER S. , GILES WAYNE R. , DEMIR SEMAHAT S. 
Published: August 2003

Role of IKr in Rabbit Sinoatrial Node.
Introduction: A rapidly activating delayed rectifier potassium current (IKr) is known to have an important role in determining the properties of spontaneous pacing in enzymatically isolated rabbit sinoatrial node (SAN) cells. The functional characteristics of IKr are conferred by its dependence on time, voltage, and external potassium. The aim of this study was to develop a rigorous mathematical representation for IKr based on experimental findings and to investigate the role of IKr in the automaticity and intercellular communication of SAN cells. Methods and Results: A Markov model was developed using available experimental data for IKr in rabbit SAN. The dependence of IKr on external potassium, [K+]o, was incorporated using data from both in vitro preparations and results from heterologous expression experiments for this ether‐a‐go‐go related gene product. Our simulation results show the following. (1) IKr is the dominant repolarizing current in rabbit SAN cells. (2) Deactivation of IKr contributes to the net current change during the early diastolic depolarization phase. (3) Inward rectification of IKr results in a decrease in membrane resistance during repolarization relative to plateau. (4) The complex [K+]o dependence of IKr confers [K+]o insensitivity on isolated cells, which may account for the sensitivity of pacing rate to elevated [K+]o at the tissue level. Conclusion: Model results show that IKr mediates diastolic depolarization by the kinetics of its decay and by lowering resistance during late repolarization. In elevated [K+]o, increased chord conductance is balanced by the changes in kinetics and voltage dependence of IKr so that the pacing rate of single cells may be more [K+]o insensitive than expected. In addition, elevated [K+]o increases IKr magnitude during repolarization but lowers resistance, so current flow through gap junctions is less able to hyperpolarize pacing cells.
Linearly Scaled, Rate‐Invariant Normal Limits for QT Interval: Eight Decades of Incorrect Application of Power Functions
Authors: RAUTAHARJU PENTTI M. , ZHANG ZHU‐MING 
Published: August 2003

Rate‐Invariant Normal Limits for QT Interval.
Introduction: Normal limits for QT traditionally are derived as mean ± 2*SD, with rate adjustment done by dividing QT values by power functions such as RR1/2 (proportional scaling). Methods and Results: We evaluated procedures for deriving normal limits by comparing adjusted QT distributions versus heart rate using ECG data of 11,739 normal men and women aged ≥ 40 years. QT decreased as predicted by many power functions with heart rate but its SD remained relatively unchanged. Consequently, proportional scaling induced rate‐dependent distortion of normal limits. Furthermore, QT distributions by heart rate were variably skewed and non‐normal. Therefore, normal limits expressed as mean ± 2*SD were misleading. Omission of regression intercept was an additional reason for failure of Bazett's and Fridericia's formulas. Regularized normal limits for adjusted QT (Qta) were obtained with linear instead of proportional scaling of type QTa = QT + k1*(1 – RRk2), for instance, with k2 = 0.5, k1 = 0.360 for males and 0.353 for females, or with k2 = 0.42, k1 = 0.414 for males and 0.420 for females. With linear scaling, QTa = 460 msec was established as the upper 2% normal limit, with 32 msec as the limit for a significant QTa increase from reference ECG in serial comparison. Conclusion: Traditional procedures for establishment of normal limits failed because of proportional scaling, assumption of normal QT distribution, or omission of regression intercept. Percentile distributions of linearly scaled adjusted QT produced regularized rate invariant normal limits within normal sinus rates.
Bundle Branch Reentrant Tachycardia in Patients with Apparent Normal His‐Purkinje Conduction: The Role of Functional Conduction Impairment
Authors: LI YI‐GANG , GRÖNEFELD GERIAN , ISRAEL CARSTEN , BOGUN FRANK , HOHNLOSER STEFAN H. 
Published: August 2003

Bundle Branch Reentry Due to Functional His‐Purkinje Block.
Introduction: His‐Purkinje conduction delay, manifested by bundle branch block QRS complex configuration or by HV interval prolongation, is considered an essential condition for maintenance of bundle branch reentrant tachycardia (BBRT). Methods and Results: Of 178 patients with different types of ventricular tachycardia (VT), 13 were found to have BBRT as the underlying electrophysiologic mechanism. Of these 13 patients (9 men and 4 women; mean age 64 ± 13 years), 6 had an HV interval ≤55 msec (group A), and 7 had a prolonged HV interval (>55 msec; group B) during sinus rhythm (SR). PR interval (169 ± 32 vs 339 ± 138 msec, P = 0.01) and QRS duration (116 ± 17 vs 167 ± 29 msec, P = 0.003) during SR were significantly shorter in group A than in group B. In group A, the HV interval was significantly longer during VT than during SR (73 ± 18 vs 47 ± 7 msec, P = 0.007). There were more patients with functional His‐Purkinje block (split His potentials, a jump of HV interval induced by programmed atrial stimulation or burst pacing) or phase 3 block in group A than group B (6/6 patients vs 0/7 patients, P < 0.001). Successful ablation of the right bundle branch was performed in all 13 patients without deteriorating AV block. Two patients died in each group, and VTs (other than BBRT) or ventricular fibrillation were documented by ICD electrogram storages in 4 patients during follow‐up of 27 ± 17 months. Conclusion: A prolonged HV interval during SR is not a prerequisite for BBRT. Functional His‐Purkinje system abnormalities appear to be the electrophysiologic substrate for this specific type of BBRT.
Global P Wave Duration on the 65‐Lead ECG: Single‐Site and Dual‐Site Pacing in the Structurally Normal Human Atrium
Authors: GOZOLITS STEFAN , FISCHER GERALD , BERGER THOMAS , HANSER FRITZ , ABOU‐HARB MARIA , TILG BERNHARD , PACHINGER OTMAR , HINTRINGER FLORIAN , ROITHINGER FRANZ X. 
Published: August 2003

Global P Wave Duration on the 65‐Lead ECG.
Introduction: Pacing is believed to prevent atrial fibrillation by reducing atrial activation time. Exact correlation between P wave duration (PWD) on surface ECG and endocardial atrial activation time is still unexplored. Methods and Results: In 15 patients without structural heart disease (9 women, age 45 ± 14 years), single site [high right atrium (HRA), coronary sinus ostium (CSos), distal CS (CSd), high RA septum (Bachmann's bundle, BB)] and dual‐site pacing (various combinations) was performed after ablation of supraventricular tachycardia. A 65‐lead surface ECG was recorded simultaneously. Endocardial atrial activation time was measured off‐line (stimulus – last bipolar recording), and the respective PWD was assessed using the root mean square and 65‐channel summary plots. PWD during pacing from BB was significantly shorter (96 ± 12 msec) than during HRA (121 ± 15 msec), CSos (108 ± 9 msec), and CSd pacing (126 ± 14 msec; P < 0,01, respectively). PWD during dual‐site pacing (HRA + BB, 91 ± 14 msec; HRA + CSos, 96 ± 7 msec; HRA + CSd, 90 ± 7 msec; BB + CSd, 96 ± 12 msec) was not significantly shorter than during pacing from BB. Correlation between endocardial atrial activation time and PWD was 0.83. Conclusion: PWD during single‐site and dual‐site atrial pacing represents endocardial atrial activation time and can be measured precisely using the 65‐lead surface ECG. The fact that high septal pacing results in the shortest PWD may have implications for preventive pacing in patients with atrial fibrillation.
Salt Stress Activation of Wound-Related Genes in Tomato Plants
Authors: Dombrowski James E. 
Published: August 2003

Abstract
Plants respond to various stresses by expressing distinct sets of genes. The effects of multiple stresses on plants and their interactions are not well understood. We have discovered that salt stress causes the accumulation of proteinase inhibitors and the activation of other wound-related genes in tomato (Lycopersicon esculentum) plants. Salt stress was also found to enhance the plant's response to wounding locally and systemically. The tomato mutant (def-1), which has an impairment in the octadecanoid pathway, displayed a severe reduction in the accumulation of proteinase inhibitors under salt stress, indicating that salt stress-induced accumulation of proteinase inhibitors was jasmonic acid dependent. The analysis of salt stress in another tomato mutant, spr-1, which carries a mutation in a systemin-specific signaling component, and transgenic tomato plants that express an antisense-prosystemin cDNA, showed that prosystemin activity was not required for the salt-induced accumulation of proteinase inhibitors, but was necessary to achieve maximal levels. These results suggest that a prosystemin independent- but jasmonic acid-dependent pathway is utilized for proteinase inhibitor accumulation in response to salt stress.
Convergence of Signaling Pathways Induced by Systemin, Oligosaccharide Elicitors, and Ultraviolet-B Radiation at the Level of Mitogen-Activated Protein Kinases in Lycopersicon peruvianum Suspension-Cultured Cells
Authors: Holley Susan R. , Yalamanchili Roopa D. , Moura Daniel S. , Ryan Clarence A. , Stratmann Johannes W. 
Published: August 2003

Abstract
We tested whether signaling pathways induced by systemin, oligosaccharide elicitors (OEs), and ultraviolet (UV)-B radiation share common components in Lycopersicon peruvianum suspension-cultured cells. These stress signals all induce mitogen-activated protein kinase (MAPK) activity. In desensitization assays, we found that pretreatment with systemin and OEs transiently reduced the MAPK response to a subsequent treatment with the same or a different elicitor. In contrast, MAPK activity in response to UV-B increased after pretreatment with systemin and OEs. These experiments demonstrate the presence of signaling components that are shared by systemin, OEs, and UV-B. Based on desensitization assays, it is not clear if the same or different MAPKs are activated by different stress signals. To identify specific stress-responsive MAPKs, we cloned three MAPKs from a tomato (Lycopersicon esculentum) leaf cDNA library, generated member-specific antibodies, and performed immunocomplex kinase assays with extracts from elicited L. peruvianum cells. Two highly homologous MAPKs, LeMPK1 and LeMPK2, were activated in response to systemin, four different OEs, and UV-B radiation. An additional MAPK, LeMPK3, was only activated by UV-B radiation. The common activation of LeMPK1 and LeMPK2 by many stress signals is consistent with the desensitization assays and may account for substantial overlaps among stress responses. On the other hand, MAPK activation kinetics in response to elicitors and UV-B differed substantially, and UV-B activated a different set of LeMPKs than the elicitors. These differences may account for UV-B-specific responses.
Induction of Hypersensitive Cell Death by Hydrogen Peroxide Produced through Polyamine Degradation in Tobacco Plants
Authors: Yoda Hiroshi , Yamaguchi Yube , Sano Hiroshi 
Published: August 2003

Abstract
Screening immediate-early responding genes during the hypersensitive response (HR) against tobacco mosaic virus infection in tobacco (Nicotiana tabacum) plants, we identified a gene encoding ornithine decarboxylase. Subsequent analyses showed that other genes involved in polyamine biosynthesis were also up-regulated, resulting in the accumulation of polyamines in apoplasts of tobacco mosaic virus-infected leaves. Inhibitors of polyamine biosynthesis, α-difluoromethyl-ornithine, however, suppressed accumulation of polyamines, and the rate of HR was reduced. In contrast, polyamine infiltration into a healthy leaf induced the generation of hydrogen peroxide and simultaneously caused HR-like cell death. Polyamine oxidase activity in the apoplast increased up to 3-fold that of the basal level during the HR, and its suppression with a specific inhibitor, guazatine, resulted in reduced HR. Because it is established that hydrogen peroxide is one of the degradation products of polyamines, these results indicate that one of the biochemical events in the HR is production of polyamines, whose degradation induces hydrogen peroxide, eventually resulting in hypersensitive cell death.
Dithiol Oxidant and Disulfide Reductant Dynamically Regulate the Phosphorylation of Light-Harvesting Complex II Proteins in Thylakoid Membranes
Authors: Martinsuo Päivi , Pursiheimo Saijaliisa , Aro Eva-Mari , Rintamäki Eevi 
Published: September 2003

Abstract
Light-induced phosphorylation of light-harvesting chlorophyll a/b complex II (LHCII) proteins in plant thylakoid membranes requires an activation of the LHCII kinase via binding of plastoquinol to cytochrome b 6 f complex. However, a gradual down-regulation of LHCII protein phosphorylation occurs in higher plant leaves in vivo with increasing light intensity. This inhibition is likely to be mediated by increasing concentration of thiol reductants in the chloroplast. Here, we have determined the components involved in thiol redox regulation of the LHCII kinase by studying the restoration of LHCII protein phosphorylation in thylakoid membranes isolated from high-light-illuminated leaves of pumpkin (Cucurbita pepo), spinach (Spinacia oleracea), and Arabidopsis. We demonstrate an experimental separation of two dynamic activities associated with isolated thylakoid membranes and involved in thiol regulation of the LHCII kinase. First, a thioredoxin-like compound, responsible for inhibition of the LHCII kinase, became tightly associated and/or activated within thylakoid membranes upon illumination of leaves at high light intensities. This reducing activity was completely missing from membranes isolated from leaves with active LHCII protein phosphorylation, such as dark-treated and low-light-illuminated leaves. Second, hydrogen peroxide was shown to serve as an oxidant that restored the catalytic activity of the LHCII kinase in thylakoids isolated from leaves with inhibited LHCII kinase. We propose a dynamic mechanism by which counteracting oxidizing and reducing activities exert a stimulatory and inhibitory effect, respectively, on the phosphorylation of LHCII proteins in vivo via a novel membrane-bound thiol component, which itself is controlled by the thiol redox potential in chloroplast stroma.
The analytic nursery: Ferenczi's ‘wise baby’ meets Jung's ‘divine child’
Authors: Fortune Christopher 
Published: August 2003

Abstract:In 1923, Sandor Ferenczi wrote a paper entitled ‘The dream of the clever baby’, in which he identified a phenomenon he discovered through his clinical work: the notion that young children who had been traumatized often had accelerated developmental characteristics that led them to acquire highly acute sensitivities and intuitions – in short, wisdom beyond their years. He characterized them as ‘wise’ babies. Similarly, C. G. Jung, with Karl Kerenyi, (1949) elaborated a myth known as the ‘divine child’– identifying an archetype which activates healing and intuitive understanding in children and adults. In their work, Jung (and Kerenyi) explored the ‘divine child’ archetype from a mythological and a psychological perspective. The following paper elaborates aspects of Ferenczi's ‘wise child’ and Jung's ‘divine child’, comparing and contrasting them, and suggesting new perspectives on the connections between Ferenczi's and Jung's theoretical and clinical perspectives, and the two men themselves. As well, and specifically, the paper explores a comparative understanding of the development of two different modalities of early psychodynamic concepts with regard to children and their response to trauma, aspects that continue through theoretical and clinical practice today.
Statewide Trial‐Heat Polls and the 2000 Presidential Election: A Forecast Model*
Authors: DeSart Jay A. , Holbrook Thomas M. 
Published: August 2003

Objective. We provide an examination and update of a presidential election forecasting model that we have previously developed to predict state‐level presidential election outcomes.Method. Our model consists of September statewide trial‐heat polls in 1992, 1996, and 2000 along with a prior vote variable. We use this model to generate predictions for both state‐level and national‐level outcomes.Results. Although our model generated reasonably accurate point estimates of state‐level outcomes in 2000, it still incorrectly predicted a Gore victory in 2000.Conclusions. We discuss possible explanations for the 2000 misprediction and present updated coefficients to be used to generate a forecast for the 2004 election.