bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification with a photoaffinity reagent of a tonoplast protein involved in vacuolar malate transport of Catharanthus roseus
Authors: Lahjouji Karim , Carrasco Antoine , Bouyssou Huguette , Cazaux Louis , Marigo Gérard , Canut Hervé 
Published: August 2003

SummaryThe effect of N‐(4‐azido‐salicylyl) aspartic acid (AzSA), a photolysable analogue of malate, was tested on the malate transport activity of tonoplast vesicles isolated from Catharanthus roseus cell suspension cultures. AzSA inhibited malate uptake in a competitive manner with a Kti of 1.7 millimolar. When iodinated, the malate analogue was found to be still photolysable and a competitive inhibitor of malate uptake. Photolysis of 125I‐labelled AzSA in the presence of purified tonoplast vesicles led to label incorporation into several polypeptides after analysis by gel electrophoresis. Only one polypeptide, with an apparent molecular mass of 37 kDa, was totally protected by the inclusion of 50 millimolar malate, the original substrate, in the photolysis medium. The labelled polypeptide is therefore apparently a specific malate‐binding protein. Diethylpyrocarbonate (DEPC), a very potent inhibitor of malate transport acting at the active site of the transporter, also protected the 37 kDa polypeptide from labelling. Citrate and, to a lesser extent, quinate afforded protection from labelling whilst other organic acids or aspartic acid (100 millimolar) did not. These photoprotection results are in good agreement with the data concerning the specificity of malate transport across the tonoplast. Polyclonal antibodies against the 37 kDa polypeptide strongly inhibited malate uptake both in tonoplast vesicles and in isolated vacuoles. These results suggest the involvement of the 37 kDa polypeptide in vacuolar malate transport.
A second form of adenine phosphoribosyltransferase in Arabidopsis thaliana with relative specificity towards cytokinins
Authors: Schnorr Kirk Matthew , Gaillard Catherine , Biget Elisabeth , Nygaard Per , Laloue Michel 
Published: August 2003

SummaryAdenine phosphoribosyltransferase (APRTase) is an important enzyme for its ability to convert adenine, a by‐product of many biochemical reactions, into AMP. By functional complementation of an Escherichia coli mutant, cDNAs encoding two APRTases have been cloned from Arabidopsis thaliana. One of the cDNAs (ATapt1)has been previously identified while the second (ATapt2) is of a previously unknown type. Kinetic analysis of the two enzymes purified from E. coli expressing the two cDNAs indicates that ATapt2 has a higher affinity for cytokinin than the ATapt1. RNase protection studies indicate that the ATapt2, is not expressed in leaves. Analysis of the gene structure indicates that ATapt2 has identical intron positions to ATapt1, but neither the intron sequence nor intron size are conserved between the two genes. The implications of a second, differentially expressed APRTase with affinity for both adenine and cytokinin are discussed.
A role for arabinogalactan‐proteins in plant cell expansion: evidence from studies on the interaction of β‐glucosyl Yariv reagent with seedlings of Arabidopsis thaliana
Authors: Willats William G.T. , Knox J. Paul 
Published: August 2003

SummarySeedlings of Arabidopsis thaliana were germinated and grown in medium containing β‐glucosyl Yariv reagent (βGlcY), a synthetic phenyl glycoside that interacts specifically with arabinogalactan‐proteins (AGPs), a class of plant cell surface proteoglycans. The effect of βGlcY on the seedlings was to reduce the overall growth of both the root and the shoot. βGlcY only accumulated in the root tissues and the reduced growth of the shoot appeared to be an indirect effect of impaired root growth. Reduced root growth was a consequence of a reduction in cell elongation during the postproliferation phase of elongation at the root apex and this was associated with extensive radial expansion of root epidermal cells. βGlcY penetrated roots as far as the endodermis and it is suggested that the interaction of βGlcY with AGPs in the load‐bearing cell layers inhibited root elongation. When βGlcY was added to carrot suspension‐cultured cells that had been induced to elongate rather than proliferate, cell elongation was inhibited. The AGP‐unreactive α‐galactosyl Yariv reagent (αGalY) had no biological activity in either of these systems.
Lc as a non‐destructive visual reporter and transposition excision marker gone for tomato
Authors: Goldsbrough Andrew P. , Tong Yusen , Yoder John I. 
Published: August 2003

SummaryThe maize anthocyanin regulatory gone Lc gives rise to greatly enhanced anthocyanin accumulation when introduced into tomato. Under the control of the cauliflower mosaic virus promoter Lc was seen to mediate enhanced pigmentation in all vegetative tissues, including roots, under high light (or sunlight) conditions. This paper demonstrates that the gone can be used as a powerful non‐destructive cell autonomous visual excision marker which will provide a valuable tool for transposon mutagenesis, the study of transposon biology and for studying cell lineages at the whole‐plant level.
Mind the Model: Effect of Instrumentation on Inducibility of Atrial Fibrillation in a Sheep Model
Authors: WILLEMS RIK , HOLEMANS PATRICIA , ECTOR HUGO , SIPIDO KARIN R. , VAN DE WERF FRANS , HEIDBÜCHEL HEIN 
Published: August 2003

Effect of Instrumentation on AF in a Sheep Model.
Introduction: Atrial electrical remodeling, shortening of the atrial effective refractory period (AERP) underlying atrial fibrillation (AF) has been described in different animal models. However, there remains some controversy regarding the time course of this electrical remodeling and the need for secondary factors in the development of AF. We investigated the effect of instrumentation on the inducibility of AF. We hypothesized that epicardial instrumentation could be a confounding factor that accelerates the development of AF. Methods and Results: Thirty sheep were rapidly atrially paced at 600 beats/min for 15 weeks: 15 were endocardially instrumented and paced (endo), and 15 were both endocardially and epicardially instrumented. Six of these animals were endocardially paced (sham) and 9 were epicardially paced (epi). The underlying rhythm was determined at regular intervals, and electrophysiologic study was performed. AF developed significantly faster in the epi group. After 3 weeks of pacing, the cumulative incidence of sustained AF (> 1 hour) already was 70% in this group versus only 14% and 20% in the endo and sham groups, respectively. After 15 weeks of pacing, this difference was no longer evident. Baseline AERP and minimal AERP, reached before the development of AF, were not significantly different in the three groups. Epicardial instrumentation (epi and sham) increased baseline left and right atrial pressures, but only epicardial stimulation (epi) led to early development of AF. Conclusion: In this sheep model of AF, the experimental setup is a major determinant of the inducibility of AF. Not epicardial instrumentation per se but epicardial stimulation accelerated the development of AF. Different animal models of AF may represent different clinical entities of AF.
Differentiation of Atrial and Pulmonary Vein Potentials Recorded Circumferentially Within Pulmonary Veins
Authors: TADA HIROSHI , ORAL HAKAN , GREENSTEIN RADMIRA , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED 
Published: August 2003

Pulmonary Vein Electrograms.
Introduction: Accurate discrimination of atrial and pulmonary vein potentials recorded circumferentially within the pulmonary veins is important when performing segmental isolation of the pulmonary veins in patients with atrial fibrillation. Methods and Results: Twenty patients with paroxysmal atrial fibrillation underwent pulmonary vein mapping with a decapolar Lasso catheter during sinus rhythm and during pacing in the distal coronary sinus and left atrial appendage. Bipolar and unipolar electrograms were recorded within the left superior, right superior, and left inferior pulmonary veins. The atrial potentials were larger in the left pulmonary veins than in the right superior pulmonary vein, whereas the pulmonary vein potentials in the superior pulmonary veins were larger than in the left inferior pulmonary vein. The atrial and pulmonary vein potentials usually were readily distinguished during sinus rhythm in the right superior pulmonary vein. Characteristic distribution and morphologies of the atrial potentials as well as the response to distal coronary sinus and left atrial appendage pacing were useful for differentiating the atrial and pulmonary vein potentials in the left pulmonary veins. Conclusion: Atrial and pulmonary vein potentials recorded circumferentially within the pulmonary veins have characteristic features that are useful in distinguishing them from each other.In the left pulmonary veins, discrimination of the atrial and pulmonary vein potentials is aided by coronary sinus or left atrial appendage pacing.
Mechanisms for Atrial Fibrillation in Patients with Wolff‐Parkinson‐White Syndrome
Authors: HAMADA TAKASHI , HIRAKI TATSURO , IKEDA HISAO , KUBARA ICHIRO , YOSHIDA TERUHISA , OHGA MASANOBU , IMAIZUMI TSUTOMU 
Published: August 2003

Atrial Fibrillation and WPW Syndrome.
Introduction: Paroxysmal atrial fibrillation (PAF) frequently occurs in patients with Wolff‐Parkinson‐White (WPW) syndrome. To elucidate the mechanisms for PAF, we performed electrophysiologic studies (EPS) before and after ablation of accessory pathways (APs). Methods and Results: We investigated 24 patients with WPW syndrome who had AV reciprocating tachycardia and prior PAF and had undergone successful ablation of APs. Patients in whom atrial fibrillation (AF) was induced by EPS at day 7 after ablation were considered the inducible AF group (n = 14), and patients in whom AF was not induced by EPS at day 7 after ablation were considered the noninducible AF group (n = 10). Fifteen patients with AV nodal reentrant tachycardia (AVNRT) but without PAF who underwent ablation of the slow AV nodal pathways served as the control group (AVNRT group). Maximal atrial conduction delay and conduction delay zone, which are indices of atrial vulnerability, were measured before and after ablation. Before ablation, maximal atrial conduction delay and conduction delay zone were significantly greater (P < 0.0001 and P < 0.0001, respectively) in the two WPW syndrome groups than in the AVNRT group, indicating increased atrial vulnerability in WPW syndrome with PAF. After ablation, these parameters did not change in the inducible AF group, whereas they were significantly (P < 0.0001) decreased in the noninducible AF group and were not different from those in the AVNRT group, indicating normalized atrial vulnerability in the noninducible AF group after ablation. The prospective study demonstrated that PAF recurred only in the inducible AF group during long‐term follow‐up (17 ± 7 months). Conclusion: The findings of this study suggest that there are two mechanisms of PAF in patients with WPW syndrome: one mechanism is reversible and AP‐dependent atrial vulnerability, and the other is intrinsic and AP‐independent atrial vulnerability.
Changes in Repolarization Properties with Long‐Term Cardiac Memory Modify Dispersion of Repolarization in Patients with Wolff‐Parkinson‐White Syndrome
Authors: TAKADA YASUNOBU , INDEN YASUYA , AKAHOSHI MAKOTO , SHIBATA YOSHIHISA , SHIMIZU ATSUYA , YOSHIDA YUKIHIKO , YAMADA TAKUMI , TSUBOI NAOYA , HIRAYAMA HARUO , ITO TERUO , KONDO TAKAHISA , SAITO HIDEHIKO , HIRAI MAKOTO 
Published: August 2003

Cardiac Memory Modifies Repolarization Dispersion.
Introduction: Transient T wave changes after cessation of preexcitation have been attributed to cardiac memory. However, there have been no reports on the effects of long‐term cardiac memory on repolarization dispersion before and after catheter ablation in patients with Wolff‐Parkinson‐White (WPW) syndrome. Methods and Results: We investigated 47 patients with an accessory pathway (AP; 24 manifest left‐sided, 14 manifest right‐sided, and 9 concealed left‐sided). Repolarization dispersion was analyzed by two methods, recovery time (RT) dispersion and newly proposed T wave width (WT), from 87‐lead body surface maps before, 1 day after, and 7 days after catheter ablation. RT dispersion and WT were significantly correlated before, 1 day after, and 7 days after catheter ablation (r = 0.78). In patients with preexcitation, RT dispersion and WT increased significantly (P < 0.05) 1 day after catheter ablation (178 ± 32 msec and 172 ± 30 msec) compared with those before (154 ± 24 msec and 156 ± 18 msec) and 7 days after catheter ablation (147 ± 19 msec and 156 ± 16 msec), respectively. However, there were no significant changes in RT dispersion and WT before and after catheter ablation in concealed WPW syndrome. Conclusion: The findings suggest that the abrupt changes in activation sequence increase repolarization dispersion in the presence of previous cardiac memory, and that the dispersion decreases days or weeks after alteration of activation sequence by catheter ablation, with development of new cardiac memory in patients with manifest WPW syndrome.
Adrenergic‐Cholinergic Interaction that Modulates Repolarization in the Atrium is Altered with Aging
Authors: SOSUNOV EUGENE A. , ANYUKHOVSKY EVGENY P. , ROSEN MICHAEL R. 
Published: August 2003

Autonomic Modulation of Atrial Repolarization.
Introduction: Aging is associated with involution of both limbs of the autonomic nervous system, and the prejunctional and postjunctional effects of adrenergic and cholinergic stimulation are altered with senescence. Hence, postjunctional age‐related changes in adrenergic‐cholinergic interaction are a likely occurrence and may contribute to an altered substrate for arrhythmias. Methods and Results: Microelectrode techniques were used to record action potentials from epicardial slices of Bachmann's bundles of dogs aged 3 to 5 years (adult) and 8 to 12 years (old) in the absence or presence of acetylcholine and isoproterenol (separately and in combination). In control, action potential duration to 90% repolarization (APD) was longer in old atria. Acetylcholine (10−8 to 10−5 mol/L) in a concentration‐dependent manner hyperpolarized and shortened APD in both tissues, with more prominent effects in the old. The effects of isoproterenol (10−9 to 10−6 mol/L) to elevate the plateau and shorten APD were about the same in both adult and old tissues. In adults, low concentrations of isoproterenol (10−9 and 10−8 mol/L) significantly prolonged APD, which had been first shortened by acetylcholine. This effect of isoproterenol was decreased in old atrial tissue, resulting in shorter APD in old than adult atria in the combined presence of beta‐adrenergic and muscarinic agonists. Conclusion: In adult Bachmann's bundle, beta‐adrenergic stimulation effectively operates as a “brake” to decrease the extent of cholinergic‐induced APD shortening. The action of beta‐adrenergic stimulation to antagonize acetylcholine‐induced acceleration of repolarization declines with age, which may contribute to an altered arrhythmogenic substrate.
Atrial Signal Analysis and Defibrillation Threshold Assessment in Chronic Persistent and Reinduced Atrial Fibrillation
Authors: BORIANI GIUSEPPE , BARTOLINI PIETRO , BIFFI MAURO , CALCAGNINI GIOVANNI , CAMANINI CLAUDIA , CORAZZA IVAN , ZANNOLI ROMANO , BARBARO VINCENZO , BRANZI ANGELO 
Published: August 2003

De. brillation Threshold in Chronic and Reinduced AF.
Introduction: Induced versus spontaneous atrial fibrillation (AF) is of interest for assessing atrial defibrillation threshold reproducibility. Methods and Results: Twenty‐one patients with chronic AF underwent internal cardioversion with assessment of atrial defibrillation threshold at baseline and at reinduced AF. High right atrial (HRA) and coronary sinus (CS) bipolar recordings were analyzed to measure the mean local atrial period, its coefficient of variation, the 5th (P5) and 95th (P95) percentiles of atrial intervals, and the percentage of points lying at the baseline (number of occurrences), and to quantify AF organization. Atrial defibrillation threshold was comparable in baseline and reinduced AF in terms of leading‐edge voltage and delivered energy. Baseline and reinduced AF were comparable with regard to overall signal parameters (both in HRA and CS) and the presence of an organized arrhythmia pattern. As for individual variables, P5 increased while P95 and coefficient of variation decreased in reinduced AF compared with spontaneous AF (statistical significance was achieved for all these parameters in HRA, but only for coefficient of variation and P95 in CS). Conclusion: Sustained AF reinduced after cardioversion of chronic AF is comparable with baseline AF in terms of atrial defibrillation threshold, atrial cycle length, and pattern of organization. Therefore, a clinical model based on reinduction of sustained AF after cardioversion is suitable for studying the effects of a series of interventions on atrial defibrillation threshold. However, because this model does not yield a form of AF with comparable indices of local refractoriness (e.g., P5), it is not recommended when analyzing local electrophysiologic properties.
Mechanistic Significance of Intermittent Pulmonary Vein Tachycardia in Patients with Atrial Fibrillation
Authors: ORAL HAKAN , ÖZAYDIN MEHMET , TADA HIROSHI , CHUGH AMAN , SCHARF CHRISTOPH , HASSAN SOHAIL , LAI STEVE , GREENSTEIN RADMIRA , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED 
Published: August 2003

Pulmonary Vein Tachycardia.
Introduction: The significance of intermittent tachycardia within a pulmonary vein (PV) during an episode of atrial fibrillation (AF) is unclear. The aim of this study was to determine the role that intermittent PV tachycardias play in AF. Methods and Results: In 56 patients with AF, segmental ostial ablation guided by PV potentials was performed to isolate the PVs. The characteristics of intermittent PV tachycardias and the inducibility of AF before and after PV isolation were analyzed prospectively. During AF, a PV tachycardia (mean cycle length 130 ± 30 msec) with exit block to the left atrium was present in 93% of left superior, 80% of left inferior, 73% of right superior, and 7% of right inferior PVs. The site of shortest cycle length during AF alternated between the PVs and left atrium 1 to 13 times per minute. Complete isolation was achieved in 168 (94%) of 178 targeted PVs. In 99% of PVs, tachycardia resolved upon isolation. AF was persistent before and after PV isolation in 100% and 27% of patients, respectively (P < 0.001). Conclusion: Intermittent bursts of tachycardia are observed within multiple PVs during persistent AF in a majority of patients. After PV isolation, PV tachycardias almost always resolve, and AF is less likely to be inducible or persistent. These observations suggest a dynamic interplay between the atria and PVs, with intermittent bursts of PV tachycardia being dependent on left atrial input and with the probability of persistent AF diminishing when PV tachycardias are eliminated by PV isolation.
Body Surface Area of ST Elevation and the Presence of Late Potentials Correlate to the Inducibility of Ventricular Tachyarrhythmias in Brugada Syndrome
Authors: ECKARDT LARS , BRUNS HANS‐JÜRGEN , PAUL MATTHIAS , KIRCHHOF PAULUS , SCHULZE‐BAHR ERIC , WICHTER THOMAS , BREITHARDT GÜNTER , BORGGREFE MARTIN , HAVERKAMP WILHELM 
Published: August 2003

BSPM and Late Potentials in Brugada Syndrome.
Introduction: The value of noninvasive markers reflecting repolarization and/or conduction abnormalities in identifying patients with abnormal ECG showing a pattern of atypical right bundle branch block and ST elevation syndrome (Brugada syndrome) at risk for life‐threatening arrhythmias is controversial. Because right precordial ST elevation reflects inhomogeneous repolarization, we hypothesized that a correlation between the area of ST elevation, that is, the area of inhomogeneous repolarization, and the inducibility of ventricular tachyarrhythmias (VT) exists. Therefore, the body surface area of ST elevation and the presence of late potentials were compared to the inducibility of VT in patients with the characteristic ECG of Brugada syndrome. Methods and Results: A 120‐channel body surface potential map was recorded at rest and after administration of a Class I agent (ajmaline, 1 mg/kg) to measure the body surface area of ST elevation (≥0.2 mV) in 23 individuals (16 patients had been resuscitated from near sudden cardiac death or had suffered syncope) with an ECG compatible with the diagnosis of Brugada syndrome as well as in 15 healthy controls and in 15 patients with arrhythmogenic right ventricular cardiomyopathy. Late potentials were assessed in 20 of the Brugada patients using signal‐averaged ECG. Programmed ventricular stimulation was performed at two ventricular sites with up to three extrastimuli. Mean body surface area of ST elevation (≥0.2 mV) of all Brugada syndrome patients was 154 ± 139 cm2 (control 9 ± 9 cm2; P < 0.001). In the group of patients with arrhythmogenic right ventricular cardiomyopathy, only one patient was found to have an area of ST elevation (165 cm2). In the presence of ajmaline, area size increased to 330 ± 223 cm2 in Brugada syndrome patients (P < 0.05). In patients with inducible sustained (n = 15) and nonsustained VT (n = 3), a mean area of 183 ± 139 cm2 was found, whereas the area was only 52 ± 58 cm2 in those with no VT induction (P < 0.05). For an area ≥ 50 cm2, there were positive and negative predictive values of 92% and 60%, respectively. Positive late potentials were found in 60% of patients and correlated to the inducibility during programmed ventricular stimulation (positive predictive value 100%, negative predictive value 75%; P < 0.001). Conclusion: In patients with Brugada syndrome, the body surface area of ST elevation and the presence of late potentials correlate to the inducibility of VT during programmed ventricular stimulation and may be of value as a new noninvasive marker for risk stratification in these patients.
Cerebrovascular Complication Associated with Pulmonary Vein Ablation
Authors: KOK LAI CHOW , MANGRUM J. MICHAEL , HAINES DAVID E. , MOUNSEY J. PAUL 
Published: August 2003

Stroke and PV Ablation.
Introduction: Radiofrequency (RF) ablation has become an established treatment modality for patients with paroxysmal atrial fibrillation (AF). A principal limitation of RF catheter ablation is the risk of thromboembolism. Stroke as a complication after ablation of triggers of AF has not been previously reported. Methods and Results: Fifty‐six patients underwent RF ablation for a focal source of AF. Forty‐nine patients (86%) had AF triggers in ≥1 pulmonary vein. Mean procedure time was 227 ± 74 minutes. Cerebrovascular event occurred in 3 (5%) patients, all >60 years old. Two of the three patients had a prior history of transient ischemic attacks. Conclusion: The risk of stroke from RF ablation may be higher in paroxysmal AF patients with prior transient ischemic attack.