bluuebunny/crossref_metadata_2025 huggingface dataset:
Spontaneous and evoked high‐frequency oscillations in the tetanus toxin model of epilepsy
Authors: Rolston John D. , Laxpati Nealen G. , Gutekunst Claire‐Anne , Potter Steve M. , Gross Robert E.
Published: October 2010

Purpose:  High‐frequency oscillations (HFOs) are an emerging biomarker for epileptic tissue. Yet the mechanism by which HFOs are produced is unknown, and their rarity makes them difficult to study. Our objective was to examine the occurrence of HFOs in relation to action potentials (APs) and the effect of microstimulation in the tetanus toxin (TT) model of epilepsy, a nonlesional model with a short latency to spontaneous seizures.

Methods:  Rats were injected with TT into dorsal hippocampus and implanted with a 16‐channel (8 × 2) multielectrode array, one row each in CA3 and CA1. After onset of spontaneous seizures (3–9 days), recordings were begun of APs and local field potentials, analyzed for the occurrence of interictal spikes and HFOs. Recordings were made during microstimulation of each electrode using customized, open‐source software.

Results:  Population bursts of APs during interictal spikes were phase‐locked with HFOs, which were observable almost exclusively with high‐amplitude interictal spikes. Furthermore, HFOs could reliably be produced by microstimulation of the hippocampus, providing evidence that these oscillations can be controlled temporally by external means.

Discussion:  We show for the first time the occurrence of HFOs in the TT epilepsy model, an attractive preparation for their experimental investigation and, importantly, one with a different etiology than that of status models, providing further evidence of the generality of HFOs. The ability to provoke HFOs with microstimulation may prove useful for better understanding of HFOs by directly evoking them in the lab, and designing high‐throughput techniques for presurgical localization of the epileptic focus.
Pubertal Development, Sleep Problems, and Alcohol Use: A Commentary
Authors: Wong Maria M.
Published: October 2010

Background:  This commentary discussed the study conducted by Pieters et al. (2010 Alcohol Clin Exp Res in press) on the relationships among puberty dependent, sleep regulation, and alcohol use in adolescents. The goal of this commentary is to underscore the significance of the study and discuss some of the unaddressed questions in the area.

Methods:  The significance of the study and unaddressed questions are discussed.

Results:  Pieters et al. (2010 Alcohol Clin Exp Res in press) provided valuable data to understanding the relationships among puberty, sleep problems, and alcohol use. Questions regarding the relationship between puberty and sleep problems, the possible reciprocal relationships among circadian phase preference, sleep problems and alcohol use, mediators and moderators of such relationships, as well as potential gender differences on these relationships were discussed.

Conclusions:  To understand the relationships among pubertal development, sleep problems, and alcohol use, researchers need to be aware of the physiological changes that take place in puberty, as well as the psychosocial factors that are associated with such changes. Important mediators and moderators of the relationships among these constructs also need to be identified. Longitudinal design may be useful in this regard.
Pregnenolone and Ganaxolone Reduce Operant Ethanol Self‐Administration in Alcohol‐Preferring P Rats
Authors: Besheer Joyce , Lindsay Tessa G. , O’Buckley Todd K. , Hodge Clyde W. , Morrow A. Leslie
Published: October 2010

Background: Neuroactive steroids modulate ethanol intake in several self‐administration models with variable effects. The purpose of this work was to examine the effects of the long‐acting synthetic GABAergic neurosteroid ganaxolone and the endogenous neurosteroid pregnenolone, a precursor of all GABAergic neuroactive steroids, on the maintenance of ethanol self‐administration in an animal model of elevated drinking—the alcohol‐preferring (P) rats.

Methods: P rats were trained to self‐administer ethanol (15% v/v) versus water on a concurrent schedule of reinforcement, and the effects of ganaxolone (0 to 30 mg/kg, subcutaneous [SC]) and pregnenolone (0 to 75 mg/kg, intraperitoneal [IP]) were evaluated on the maintenance of ethanol self‐administration. After completion of self‐administration testing, doses of the neuroactive steroids that altered ethanol self‐administration were assessed on spontaneous locomotor activity. Finally, the effect of pregnenolone administration on cerebral cortical levels of the GABAergic neuroactive steroid (3α,5α)‐3‐hydroxypregnan‐20‐one (allopregnanolone, 3α,5α‐THP) was determined in both ethanol‐experienced and ethanol‐inexperienced P rats because pregnenolone is a precursor of these steroids.

Results: Ganaxolone produced a dose‐dependent biphasic effect on ethanol reinforcement, as the lowest dose (1 mg/kg) increased and the highest dose (30 mg/kg) decreased ethanol‐reinforced responding. However, the highest ganaxolone dose also produced a nonspecific reduction in locomotor activity. Pregnenolone treatment significantly reduced ethanol self‐administration (50 and 75 mg/kg), without altering locomotor activity. Pregnenolone (50 mg/kg) produced a significant increase in cerebral cortical allopregnanolone levels. This increase was observed in the self‐administration trained animals, but not in ethanol‐naïve P rats.

Conclusions: These results indicate that pregnenolone dose‐dependently reduces operant ethanol self‐administration in P rats without locomotor impairment, suggesting that it may have potential as a novel therapeutic for reducing chronic alcohol drinking in individuals that abuse alcohol.
The Nicotinic Acetylcholine Receptor Partial Agonist Varenicline Increases the Ataxic and Sedative‐Hypnotic Effects of Acute Ethanol Administration in C57BL/6J Mice
Authors: Kamens Helen M. , Andersen Jimena , Picciotto Marina R.
Published: October 2010

Background: The costs associated with alcohol abuse are staggering, therefore much effort has been put into developing new pharmacologic strategies to decrease alcohol abuse. Recently, the nicotinic acetylcholine receptor (nAChR) partial agonist varenicline has been shown to decrease ethanol consumption in both humans and animal models.

Methods: We examined the effects of varenicline on the ataxic and sedative‐hypnotic effects of ethanol. First, varenicline was administered prior to placement in a locomotor activity chamber to determine whether varenicline influenced baseline locomotor activity. To determine the effect of nicotinic modulation on ethanol‐induced motor incoordination, varenicline was administered 30 minutes prior to an acute ethanol injection and then mice were tested on the balance beam, dowel test, or fixed‐speed rotarod. To examine ethanol’s sedative‐hypnotic effects, varenicline was administered 30 minutes prior to 4 g/kg ethanol and the duration of loss of righting reflex (LORR) was measured.

Results: Varenicline markedly reduced baseline locomotor activity in C57BL/6J mice. Varenicline increased ethanol‐induced ataxia when measured on the balance beam and dowel test but had no effect when measured on the fixed‐speed rotarod. Pretreatment with varenicline increased the duration of LORR.

Conclusions: These data provide evidence that nAChRs may be involved in the ataxic and sedative effects of ethanol. It is possible that one mechanism that could contribute to the ability of varenicline to decrease ethanol consumption may be through increasing negative behavioral effects of alcohol.
Emotional Distress in Partners of Patients with an Implantable Cardioverter Defibrillator: A Systematic Review and Recommendations for Future Research
Authors: VAN DEN BROEK KRISTA C. , HABIBOVIĆ MIRELA , PEDERSEN SUSANNE S.
Published: October 2010

Both patients with an implantable cardioverter defibrillator (ICD) and their partners face challenges when adapting to the ICD. Distress is a burden on its own for partners but may also affect well being and health of patients. This review provides a systematic overview of the literature on psychological distress in partners of ICD patients and recommendations for future research.

PubMed and PsycInfo were searched in March 2010 using a priori defined search terms. This search and the additional hand search resulted in 22 studies, of which 13 were quantitative and eight qualitative.

Sample sizes in quantitative studies varied considerably from 10 to 196 partners, with only six of 13 studies including >50 partners. Partner levels of distress were at least on par with patient levels. The majority of large‐scale studies suggested that partner distress levels decrease in the first year postimplantation. Most studies reported no impact of ICD shocks on distress levels or quality of life in partners. ICD indication as well as comorbid conditions, age, and the psychological profile of the partner were related to distress and quality of life. Domains of concern emerging from qualitative studies were related to care of the ICD patient, helplessness and uncertainties related to shocks, role changes, sexual activities, overprotectiveness, and driving.

Partner levels of distress may be as high as that of ICD patients. Research with large samples is needed to further investigate the course and determinants of partner distress and the influence that partner distress may have on patient health outcomes. (PACE 2010; 33:1442–1450)
Spironolactone Therapy is Associated with Reduced Ventricular Tachycardia Rate in Patients with Cardiomyopathy
Authors: DIMAS VASSILIS , AYERS COLBY , DANIELS JAMES , JOGLAR JOSE A. , HILL JOSEPH A. , NASEEM R. HARIS
Published: October 2010

Introduction: Multiple pharmacological therapies currently in prevalent clinical use for cardiac diseases have antifibrotic properties. Spironolactone, a potent antifibrotic agent, is currently used for advanced heart failure. Therapies such as HMG‐CoA reductase inhibitors (statins) and angiotensin‐converting enzyme inhibitors (ACEi) also have antifibrotic properties. However, the effect of these medications on the ventricular arrhythmia phenotype is currently unknown. Therefore, we set out to define the ventricular arrhythmia rates in patients actively treated with such therapies.

Methods and Results: We retrospectively evaluated the ventricular tachycardia (VT) rates in patients with structural heart disease actively treated with therapies with antifibrotic properties. VT rates were significantly diminished in patients treated with spironolactone (158 ± 26 beats per minute [bpm], n = 21) compared to patients on no medications (205 ± 22 bpm, n = 13) or those who were on similar heart‐failure therapies but not on spironolactone (186 ± 32 bpm, n = 82). In addition, we observed that VT rates showed a significant trend toward lower rates in patients receiving either statins or ACEi, compared to patients on no medical therapy. In multivariate analysis, spironolactone therapy was identified as the single most significant variable for reduced VT rate.

Conclusion: Use of spironolactone in patients with heart failure is associated with reduced VT rate. Similar but less‐significant reductions in VT rates were observed with use of other pharmacological agents with antifibrotic properties, such as statins and ACEi. Our findings, at least in part, could account for reduction in sudden cardiac death rates documented with use of these therapies. (PACE 2011; 34:309–314))
Increased Heterogenity of Ventricular Repolarization in Obese Nonhypertensive Children
Authors: NIGRO GERARDO , RUSSO VINCENZO , DI SALVO GIOVANNI , DE CRESCENZO ILARIA , RAGO ANNA , PERRONE LAURA , GOLINO PAOLO , RUSSO MARIA GIOVANNA , CALABRÒ RAFFAELE
Published: October 2010

Objective: Obese children, without arterial hypertension, may be a unique clinical opportunity to evaluate the effect of obesity, per se, on ventricular repolarization, excluding the influence of possible comorbidities. The QTc dispersion (QTc‐d), JTc dispersion (JTc‐d), and transmural dispersion of repolarization (TDR) have been suggested to be electrocardiographic indexes reflecting the physiological variability of regional ventricular repolarization. The aim of our study is to define the effects of obesity on the ventricular repolarization in obese children who have no other clinically appreciable cause of heart disease.

Methods: The study involved 70 subjects (48 male, 22 female), with a mean age (± standard deviation) of 13 ± 2 years. A total of 35 individuals were obese (Group A: 24 male, 11 female, mean body mass index [BMI] of 38.2 ± 5.8 kg/m2), and 35 participants were healthy lean children (Group C: 24 male, 11 female, mean BMI of 22.3 ± 0.3 kg/m2). Heart rate; QRS duration; maximum and minimum QT interval; and QTc‐d, JTc‐d, and TDR measurement were performed.

Results: Compared with the healthy control group, obese children presented increased values of the QTc‐d, JTc‐d, and TDR (31.1 ± 10.6 vs 46.2 ± 15.3 ms, P < 0.003; 29.8 ± 8.5 vs 40.1 ± 10.3 ms, P < 0.04; 83.2 ± 13.5 vs 100.7 ± 16.3 ms, P < 0.05). A statistically significant correlation was found between the values of QTc‐d, insulin serum concentration (r = 0.46, P = 0.04), and homeostasis model assessment of insulin resistance (r = 0.34, P = 0.03).

Conclusions: Our data suggest that obese nonhypertensive children have an increased ventricular repolarization heterogeneity in relation to controls. (PACE 2010; 33:1533–1539)
Trends of Temporary Pacemaker Implant and Underlying Disease Substrate
Authors: JOU YU‐LAN , HSU HONG‐PIN , TUAN TA‐CHUAN , WANG KANG‐LING , LIN YENN‐JIANG , LO LI‐WEI , HU YU‐FENG , KONG CHI‐WOON , CHANG SHIH‐LIN , CHEN SHIH‐ANN
Published: October 2010

Background: To evaluate contemporary trends of clinical characteristics, etiologies, and underlying diseases, and their relationship between different bradyarrhythmias in patients undergoing temporary pacemakers (TPMs).

Methods: This study included 509 patients (77 ± 11 year, 74% males) with symptomatic bradyarrhythmias requiring TPMs between 2002 and 2008. Demographics, electrocardiographic indications, etiologies, underlying diseases, and the outcome of permanent pacemaker (PPM) implants within 30 days were analyzed.

Results: Atrioventricular conduction dysfunction (AVCD) (64.0%) dominated in all bradyarrhythmias, with idiopathic degeneration (61%) as its major etiology. Antiarrhythmic drug (38%) was the leading cause in sinoatrial node dysfunction (SAND). There was an increasing trend in AVCD, while a decreasing trend in SAND. Regarding etiologies for TPM, an increasing trend was found in idiopathic degeneration, whereas a decreasing trend in acute coronary syndrome (ACS). Idiopathic degeneration had an odds ratio (OR) of 1.9 for AVCD (P = 0.001), whereas electrolyte/acid‐base disturbances (OR = 3.7, P = 0.001), β‐blockers (OR = 2.4, P = 0.002), and chronic renal disease (OR = 1.9, P = 0.01) were associated with SAND. Patients with intrinsic etiologies for TPM had a high incidence of PPM implantation within 30 days than those with extrinsic causes (67.5% vs 3.8%, P < 0.0001)

Conclusion: Increasing trends in patients requiring TPMs were observed in the elderly patients and those with AVCD and idiopathic degeneration, while decreasing trends were observed in those with SAND and ACS. Idiopathic degeneration was associated with AVCD, whereas extrinsic etiologies were related to SAND. Patients with intrinsic etiologies had a higher incidence of PPM implantation than those with extrinsic factors for TPM. (PACE 2010; 33:1475–1484)
Predictors of Mortality in Patients with Chagas’ Cardiomyopathy and Ventricular Tachycardia Not Treated with Implantable Cardioverter‐Defibrillators
Authors: SARABANDA ALVARO VALENTIM LIMA , MARIN‐NETO JOSÉ ANTÔNIO
Published: October 2010

Background: The natural history of the arrhythmogenic form of Chagas’ heart disease is not fully understood.

Methods: We assessed the outcome of 56 patients with Chagas’ cardiomyopathy ([31 men]; mean age of 55 years; mean left ventricular ejection fraction [LVEF] 42%) presenting with either sustained ventricular tachycardia (VT) or nonsustained VT (NSVT), before therapy with implantable cardioverter‐defibrillator was available at our center.

Results: Over a mean follow‐up of 38 ± 16 months (range, 1–61 months), 16 patients (29%) died, 11 due to sudden cardiac death (SCD), and five from progressive heart failure. Survivors and nonsurvivors had comparable baseline characteristics, except for a lower LVEF (46 ± 7% vs 31 ± 9%, P < 0.001) and a higher New York Heart Association class (P = 0.003) in those who died during follow‐up. Receiver‐operator characteristic curve analysis showed that an LVEF cutoff value of 38% had the best accuracy for predicting all‐cause mortality and an LVEF cutoff value of 40% had the best accuracy for prediction of SCD. Using the multivariate Cox regression analysis, LVEF < 40% was the only predictor of all‐cause mortality (hazard ratio [HR] 12.22, 95% confidence interval [CI] 3.46–43.17, P = 0.0001) and SCD (HR 6.58, 95% CI 1.74–24.88, P = 0.005).

Conclusions: Patients with Chagas’ cardiomyopathy presenting with either sustained VT or NSVT run a major risk for mortality when had concomitant severe or even moderate LV systolic dysfunction. (PACE 2011; 54–62)
Radiofrequency Ablation of a Left Accessory Pathway Unmasks Classic Chagas’ disease ECG Pattern
Authors: FEMENÍA FRANCISCO , ARCE MAURICIO , BARANCHUK ADRIAN
Published: October 2010

In patients with chronic Chagas’ cardiomyopathy, there are forms of the disease that affect the electrical conduction system almost exclusively. The most common disorders include right bundle branch block alone or in association with left anterior fascicular block. We present an unusual case of a patient with Chagas’ cardiomyopathy in association with a preexcitation syndrome. (PACE 2012; 35:e38–e39)
Clinical Predictors of Conduction Disease Progression in Type I Myotonic Muscular Dystrophy
Authors: NAZARIAN SAMAN , WAGNER KATHRYN R. , CAFFO BRIAN S. , TOMASELLI GORDON F.
Published: October 2010

Background: Patients with type I myotonic muscular dystrophy (DM1) are at risk for sudden death due to atrioventricular conduction block. We sought to characterize the trends and predictors of time‐dependent electrocardiographic (ECG) variations in patients with DM1.

Methods: Seventy patients with DM1 underwent standard electrocardiography at first evaluation and routine and symptom prompted follow‐up. Individual variations in ECG conduction intervals were assessed using spaghetti plots. Clinical predictors of conduction disease progression were assessed using multivariate random effects regression models of panel data clustered by patient and adjusted for heart rate.

Results: Substantial individual variability was noted in time‐dependent changes in PR, QRS, and QTc intervals of patients with DM1
. Changes in the QTc interval were closely associated with prolongation of the QRS interval. Age, the presence of paroxysmal atrial flutter or fibrillation, and the number of cytosine‐thymine‐guanine (CTG) repeats were independent positive predictors of time‐dependent PR and QRS prolongation during long‐term follow‐up. Female sex was negatively associated with PR prolongation but positively associated with QTc prolongation. Lower left ventricular ejection fraction was associated with greater QRS interval progression during long‐term follow‐up but was not predictive of PR interval progression.

Conclusions: Patients with DM1 can develop rapid changes in cardiac conduction intervals. Paroxysmal atrial flutter or fibrillation, older age, and larger CTG expansions predict greater time‐dependent PR and QRS interval prolongation and warrant particular attention in the arrhythmic evaluation of this high risk patient subset. (PACE 2011; 34:171–176)
Effect of Substance Abuse on Defibrillation Threshold in Patients with Implantable Cardioverter‐Defibrillator
Authors: PERRINE SHANE A. , NAYAK RAGHAVENDRA , BHARADWAJ ADITYA S. , MCKELVEY GEORGE , MOHAMAD TAMAM , JACOB SONY
Published: October 2010

Background:
 The use of recreational drugs has been observed to have deleterious effects on the heart. The aim of our study was to evaluate the effect of substance abuse on the defibrillation threshold (DFT) in patients with implantable cardioverter‐defibrillators (ICDs).

Methods:
 A retrospective analysis was conducted on patients who had undergone ICD placement at a tertiary university medical center in Detroit, Michigan. Subjects were identified based on self‐reported drug use and placed into one of the three groups: controls, cocaine, and other illicit drugs. Due to a disparity in race among groups, the main analysis on DFT value was conducted on African‐American patients only. Furthermore, exploratory analyses were conducted to investigate the effects of marijuana use and race on DFT values.

Results:
 A history of cocaine use (n = 17) significantly increases DFT among African Americans (17.3 ± 8 Joule [J] vs 12.5 ± 5 J in cases vs controls, P < 0.05), while previous use of marijuana does not significantly influence DFT. African‐American patients with a history of illicit drug use had indications for ICD implantation at an earlier age and that within the control (nondrug using) group; African Americans (n = 73) had higher DFT compared to Caucasians (n = 32), (14.5 ± 0.5 J vs 9.7 ± 0.6 J, P < 0.05).

Conclusions:
 A history of cocaine use in African Americans with ICD is a risk factor for high DFT and race itself (being African American) may be a risk for high DFT. Use of high‐energy ICDs and other DFT lowering techniques may be considered for patients who have used or continue to use cocaine or in whom DFT testing cannot be performed at the time of implantation. (PACE 2011; 34:193–199)
Altered Left Ventricular Contraction Pattern during Right Ventricular Pacing: Assessment Using Real‐Time Three‐Dimensional Echocardiography
Authors: WOLBER THOMAS , HAEGELI LAURENT , HUERLIMANN DAVID , BRUNCKHORST CORINNA , LÜSCHER THOMAS F. , DURU FIRAT
Published: October 2010

Background:
 Chronic right ventricular apical (RVA) pacing has been associated with increased risk of heart failure and adverse outcome. The acute effects of RVA pacing on three‐dimensional (3D) ventricular function and mechanical dyssynchrony are not well known. We performed a real‐time 3D echocardiographic (RT3DE) study to assess global and regional left ventricular function during RVA pacing.

Methods:
 Twenty‐six patients with implanted cardiac devices and normal intrinsic atrioventricular conduction were included in the study. RT3DE was performed during intrinsic sinus rhythm and during RVA pacing. Quantification of global and regional left ventricular function was performed offline by time‐volume analysis of 16 myocardial segments. Time to reach minimum regional volume was calculated for each segment as a percentage of the cardiac cycle. The systolic dyssynchrony index (SDI) was defined as the standard deviation of these time periods. Longitudinal function was assessed by time‐volume analysis of apical, midventricular, and basal segments.

Results:
 During RVA pacing, a reversed apical‐to‐basal longitudinal contraction sequence was observed in 58% of all patients. RVA pacing was associated with increased left ventricular (LV) dyssynchrony (SDI increase from 4.4 ± 2.2% to 6.3 ± 2.4%, P = 0.001) and reduced LV ejection fraction (decrease from 53 ± 13% to 47 ± 14%, P = 0.05).

Conclusion:
 RT3DE assessment of LV function provides evidence that pacing from the RVA results in acute alterations in LV contraction sequence and increased LV dyssynchrony. Further studies are warranted to assess the potential of RT3DE to identify patients who might be at increased risk of pacing‐induced heart failure or who might benefit from alternate‐site or multisite pacing. (PACE 2011; 76–81)
Low‐Level Vagosympathetic Nerve Stimulation Inhibits Atrial Fibrillation Inducibility: Direct Evidence by Neural Recordings from Intrinsic Cardiac Ganglia
Authors: YU LILEI , SCHERLAG BENJAMIN J. , LI SHUYAN , SHENG XIA , LU ZHIBING , NAKAGAWA HIROSHI , ZHANG YING , JACKMAN WARREN M. , LAZZARA RALPH , JIANG HONG , PO SUNNY S.
Published: October 2010

Intrinsic Cardiac Ganglia Activity Inhibited by Low‐Level Vagal Stimulation. Introduction: We hypothesized that low‐level vagosympathetic stimulation (LL‐VNS) can suppress atrial fibrillation (AF) by inhibiting the activity of the intrinsic cardiac autonomic nervous system (ICANS).

Methods and Results:
Wire electrodes inserted into both vagosympathetic trunks allowed LL‐VNS at 10% or 50% below the voltage required to slow the sinus rate or atrioventricular conduction. Multielectrode catheters were attached to atria, atrial appendages and all pulmonary veins. Electrical stimulation at the anterior right and superior left ganglionated plexi (ARGP, SLGP) was used to simulate a hyperactive state of the ICANS. Effective refractory period (ERP) and window of vulnerability (WOV) for AF were determined at baseline and during ARGP+SLGP stimulation in the presence or absence of LL‐VNS. Neural activity was recorded from the ARGP or SLGP. ARGP+SLGP stimulation induced shortening of ERP, increase of ERP dispersion and increase of AF inducibility (WOV), all of which were suppressed by LL‐VNS (10% or 50% below threshold) at all tested sites. Sham LL‐VNS failed to induce these changes. The effects of LL‐VNS were mediated by inhibition of the ICANS, as evidenced by (1) LL‐VNS suppression of the ability of the ARGP stimulation to slow the sinus rate, (2) the frequency and amplitude of the neural activity recorded from the ARGP or SLGP was markedly suppressed by LL‐VNS, and (3) the spatial gradient of the ERP and WOV from the PV‐atrial junction toward the atrial appendage was eliminated by LL‐VNS.

Conclusions:
LL‐VNS suppressed AF inducibility by inhibiting the neural activity of major GP within the ICANS. (J Cardiovasc Electrophysiol, Vol. 22, pp. 455‐463)
Different Patterns of Atrial Remodeling After Catheter Ablation of Chronic Atrial Fibrillation
Authors: LO LI‐WEI , TSAO HSUAN‐MING , LIN YENN‐JIANG , CHANG SHIH‐LIN , HU YU‐FENG , TSAI WEN‐CHIN , TUAN TA‐CHUN , SUENARI KAZUYOSHI , HUANG SHIH‐YU , TUNG NGUYEN‐HUU , HIGA SATOSHI , TAI CHING‐TAI , UENG KWO‐CHANG , LI CHENG‐HUNG , CHAO TZE‐FAN , WU TSU‐JUEY , CHEN SHIH‐ANN
Published: October 2010

Atrial Substrate Remodeling After Chronic AF Ablation. Background: Multiple remodeling patterns have been observed after catheter ablation of atrial fibrillation (AF). Objective: We aimed to clarify the electrical/structural properties associated with recurrences after ablation of chronic AF.

Methods:
After a stepwise ablation procedure in 120 consecutive patients with persistent/long‐lasting persistent AF, 36 had a recurrence of AF (Group 1/Group 2: recurrence with paroxysmal/persistent AF, n = 16/20).

Results:
During the first procedure, the left atrial (LA) bipolar voltage did not differ between the 2 groups, and the LA volume was smaller in Group 1 than in Group 2 and it was the only factor predicting the recurrent types (P = 0.009, OR = 1.04). In the second procedure, the bipolar voltage of the global left atrium increased (1.33 ± 0.11 mV vs 1.76 ± 0.16 mV, P = 0.001) in Group 1 and decreased (1.31 ± 0.14 mV vs 0.90 ± 0.12 mV, P = 0.01) in Group 2, when compared with that of the first procedure. The LA low‐voltage area (<0.5 mV) decreased in Group 1, and increased in Group 2. The LA volume (90 ± 8 cm3 vs 72 ± 8 cm3, P = 0.002) decreased in the second procedure in Group 1. It remained the same in Group 2. The right atrial substrates did not change between the procedures. After a follow‐up of 27 ± 3 months, all patients in Group 1 and 14 patients in Group 2 remained in sinus rhythm (P = 0.02).

Conclusion:
A better outcome with reverse electrical and structural remodeling occurred after the ablation of chronic AF when the recurrence was paroxysmal AF. Progressive electrical remodeling without any structural remodeling developed in those with a recurrence involving persistent AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 385‐393)
Influence of Strontium Substitution on Ferroelectric–Relaxor Transition in PLZT (7/60/40)
Authors: Priyadarsini Vattappilly , Salija Padinjare Veettil , Divya Anickattu Somasekharan , Kumar Viswanathan
Published: October 2010

In the typical ferroelectric, (Pb1−xLax)(ZryTi1−y)O3 [PLZT (7/60/40)] crossover to the relaxor phase has been achieved by isovalent A‐site substitution. Dielectric, ferroelectric, electric field‐induced strain, and structural studies reveal that the influence of the chemical substituent strontium on this crossover is qualitatively similar to pressure‐induced effects in compositionally disordered perovskites.
Acicular Mullite–Cordierite Composites with Controllable CTE Values
Authors: Grohol Daniel , Han Chan , Pyzik Aleksander J. , Goss Janet M. , Todd Clifford S.
Published: October 2010

A new, two‐step method for the synthesis of porous mullite–cordierite composites with controllable coefficients of thermal expansion (CTE) values is reported. In the first step, a porous structure of interconnected acicular mullite grains with high aspect ratios is formed by using SiF4 gas at elevated temperatures. This intermediate contains particles of MgF2 and cristobalite that are attached to the mullite grains. In the second step, MgF2 and cristobalite react with parts of the acicular mullite structure, and they form cordierite, while maintaining the acicular nature of the resulting mullite–cordierite composite. CTE of mullite–cordierite composites synthesized using this method decrease about linearly with increasing cordierite content, and porosities range from 49% in cordierite‐rich composite to 54% in a mullite‐rich composite. The CTE value of a desired porous composite can be easily controlled by choosing the appropriate ratios of reactants Al2O3, SiO2, and MgO, which result in the desired mullite‐to‐cordierite ratio with its characteristic CTE value.
Enhancement of Red Emission in Aluminum Garnet Yellow Phosphors by Sb3+ Substitution for the Octahedral Site
Authors: Jung Hong Chae , Park Jin Young , Raju G. Seeta Rama , Choi Byung Chun , Jeong Jung Hyun , Moon Byung Kee
Published: October 2010

The synthetic compounds of Sb3+ ion‐substituted lanthanide aluminum garnet doped with cerium powders have been prepared by solvothermal method at 230°C and then calcined at 1500°C. These particles have spherical morphology with an average size of about 2 μm, which indicates the good luminescent characteristics. Tb3(SbAl)Al3O12:Ce3+, and Gd3(SbGa)Al3O12:Ce3+ showed not only the red shift but also increased broadness with increased red to green ratio as compared with YAG:Ce3+ phosphor. The color coordination of Ce3+‐doped Y3Al2Al3O12, Tb3(SbAl)Al3O12, and Gd3(SbGa)Al3O12 are (0.315, 0.341), (0.332, 0.331), and (0.337, 0.330), respectively. These results demonstrate that the possibility for the use of Tb3(SbAl)Al3O12 and Gd3(SbGa)Al3O12 phosphors to enhance the white light generation in the field of white light‐emitting diodes.
Effects of Ultrasonic Irradiation on the Structural and Electrical Properties of Lead‐Free 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 Ceramics
Authors: Tan Chee Kiang Ivan , Yao Kui , Ma Jan
Published: October 2010

Lead‐free piezoelectric ceramics of 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 (0.94KNN–0.06LN) were prepared by an ultrasonic irradiation method. X‐ray diffraction, thermal analyses, and X‐ray photoelectron spectroscopy were used to evaluate the effects of different ultrasonic powers on the structural and electrical properties of the 0.94KNN–0.06LN ceramics. The results revealed that the ultrasonic irradiation facilitated the decomposition of starting carbonates, promoted the perovskite phase formation and the transformation from orthorhombic to tetragonal phase, and resulted in improved ceramic density. 0.94KNN–0.06LN ceramic samples with a relative density of 94% were obtained after the ultrasonic irradiation processing under air sintering, which exhibited a piezoelectric constant of 184 pC/N. This study showed that ultrasonic irradiation was an effective method for producing high‐quality KNN‐based lead‐free ceramics with significantly reduced processing time.
Dielectric, Ferromagnetic Characteristics, and Room‐Temperature Magnetodielectric Effects in Double Perovskite La2CoMnO6 Ceramics
Authors: Lin Yi Qi , Chen Xiang Ming
Published: October 2010

The magnetic, dielectric, and magnetodielectric properties of La2CoMnO6 ceramics were evaluated together with the polarization‐electric field hysteresis loops. The phase segregation consisting of ordered and disordered regions was determined in the present ceramics. The ordering of Co2+ and Mn4+ gave rise to ferromagnetic transition temperature as high as 210 K, while the disordering of Co3+ and Mn3+ resulted in low ferromagnetic transition temperature of 80 and 150 K. The relaxor‐like behavior combined with a giant dielectric constant (∼105) was determined in La2CoMnO6 ceramics, which was attributed to the charge ordering of Co2+ and Mn4+. Owing to the mutual origin of magnetism and dielectric relaxation, La2CoMnO6 ceramics showed considerable magnetodielectric effects (∼0.8% at 10 kOe) at room temperature.
Microwave Dielectric Properties of Low‐Firing Li2MO3 (M=Ti, Zr, Sn) Ceramics with B2O3–CuO Addition
Authors: Pang Li‐Xia , Zhou Di
Published: October 2010

In this work, the sintering behaviors, microwave dielectric properties, and chemical compatibility with silver of pure and B2O3–CuO addition Li2MO3 (M=Ti, Zr, Sn) ceramics were studied. The 1 wt% B2O3–CuO addition does not affect the phase composition of Li2MO3 (M=Ti, Zr, Sn) and no secondary phase could be observed from XRD analysis. The sintering temperatures can be lowered from above 1200°C to around 900°C by 1 wt% B2O3–CuO addition. XRD analysis of cofired ceramics indicates that the Li2MO3 (M=Ti, Zr, Sn) ceramics are chemically compatible with silver. With 1 wt% B2O3–CuO addition, both Li2TiO3 and Li2SnO3 ceramics can be sintered well and possess good microwave dielectric properties with a permittivity of ∼19.67, a Q×f value of ∼46 300 GHz, a temperature coefficient of resonant frequency (TCF) of ∼+31.3 ppm/°C, and a permittivity of 13.73, a Q×f value of 36 400 GHz and a TCF about +27.4 ppm/°C, respectively.
OSCEs in Japanese postgraduate clinical training Hiroshima experience 2000—2009
Authors: Taguchi N. , Ogawa T.
Published: October 2010

Background:  Hiroshima University Hospital used the Objective Structured Clinical Examination (OSCE) as a formative and summative assessment tool to evaluate trainees’ competence.

Aim:  To reflect on Hiroshima University Hospital experience of OSCEs in postgraduate training in terms of OSCE structure and trainees’ perception of the OSCE they attended.

Methods:  A total 27 OSCEs implemented in Hiroshima University Hospital from 2000 to 2009 were examined. The OSCE in postgraduate training, Hiroshima University Hospital, was influenced by many factors from organisational and pedagogical perspectives, and changed to meet social and curriculum needs. At each OSCE, all examinees were required to answer an anonymous questionnaire, which consisted of ten checklists, just after their experience of OSCE.

Results:  Five hundred and forty trainees who attended each OSCE were required to answer a questionnaire and 510 were returned (94.4%). In the comparison between formative and summative OSCEs, the number of trainees who answered “the OSCE is meaningful” in formative OSCE was significantly higher than that in summative OSCE (P < 0.001). In the comparison between before and after the 2006/2007 academic year, trainees who indicated that OSCEs were meaningful increased after 2006/2007 (P < 0.05), and trainees who felt they were evaluated appropriately by these OSCEs increased after 2006/2007 (P < 0.01).

Conclusion:  Trainees viewed OSCEs positively and appreciated their effectiveness from a pedagogical perspective, and OSCE positively affected the trainees’ approach to learning. A ten‐year process of OSCE change has helped with educational reforms because of its adaptability. Flexible attitudes to change are necessary for stakeholders to achieve the desired reforms.
A generic consensus assessment of undergraduate competence in forceps exodontia in the United Kingdom
Authors: Durham J. , Balmer C. , Bell A. , Cowan G. , Cowpe J. , Crean St J. , Dawson L. , Evans A. , Freeman C. , Jones J. , Macluskey M. , McDonagh A. , McHanwell S. , Millsopp L. , Myrddin L. , Oliver R. , Renton T. , Sivarajasingam V. , Still D. , Taylor K. , Thomson P.
Published: October 2010

The assessment of competence in clinical skills has become more frequent in published healthcare curricula and syllabuses recently. There are agreed mechanisms for the assessment of competence in the post‐graduate environment, but no consensus within the undergraduate curriculum. This paper seeks to develop an agreed generic checklist for the assessment of competence in forceps exodontia.

Materials and methods:  A modified Delphi process was undertaken with representatives from all UK dental schools (n = 13) to develop a generic checklist for the assessment of competence in forceps exodontia. A content analysis of the assessments employed by each school was used to help discussion and inform the Delphi process.

Results:  Seven schools currently employ a summative assessment of competence in forceps exodontia, with the majority employing a structured clinical objective test (n = 6). From the seven assessments, there were a total of 29 putative items and 10 putative domains identified for a generic checklist. These were reduced to five domains and 19 items through the content analysis and Delphi process, and a generic overarching checklist was created.

Conclusion:  Using this generic checklist, it may now be possible to pool data inter‐institution to perform more powerful analyses on how our students obtain, or fail to obtain competence in forceps exodontia.
Admission systems to dental school in Europe: a closer look at Flanders
Authors: Buyse T. , Lievens F. , Martens L.
Published: October 2010

Dental education in Europe faces enormous challenges. One deals with the admission to dental school. Although admission procedures vary considerably across Europe, a characteristic of some systems is that the same procedure is used across students who will ultimately pursue different majors (medical or dental). This is based on the assumptions that there is no significant difference in these students’ scores and that the requirements for medicine and dentistry are equal. This study examines these assumptions in the admission exam ‘Medical and Dental Studies’ in Flanders. Students who pass may choose whether they start medical or dental education. Over an 8‐year period (2000–2007), admission exam scores of students starting medicine (n = 4492) were compared to those of students starting dentistry (n = 547). Second, the validity of this exam is examined for both medical and dental education. It was found that students starting dentistry had a significantly lower total score on the admission exam than students starting medicine. Differences were especially striking for the cognitive part of the admission exam. For both medical and dental students, the admission exam score was a valid predictor of academic grades in the first 3 years, although correlations were lower for dental education. These results have implications for admission procedures in countries where the same system is used for both majors. The findings that students who have a lower score choose dental education and that the validity of the exam is slightly lower for dentistry, raise questions about using the same admission exam for two obviously different majors.
Description and evaluation of a new approach on pre‐clinical implant dentistry education based on an innovative simulation model
Authors: Güth J. F. , Ponn A. , Mast G. , Gernet W. , Edelhoff D.
Published: October 2010

Introduction:  Predominantly theoretical courses are employed to teach German dental students in implant dentistry at pre‐clinical stage. As implant dentistry is an important part of the clinical treatment spectra, practical implementation of this field at an early stage of education seems to be appropriate. By a newly developed interdisciplinary implant dentistry course, students should assess an improved competence level as well as first practical experiences in the field of implant dentistry at the pre‐clinical stage of their education.

Materials and methods:  Interdisciplinary implant dentistry education was integrated in the final pre‐clinical course Phantom II at the Department of Prosthodontics, LMU, Munich. In total 120 pre‐clinical students participated at the implant dentistry education course. After theoretical introduction into implant surgery and implant prosthetics, 30 simulation units were employed for the practical training of the participants. All important treatment steps were carried out by the students under instruction by the supervisors, including interdisciplinary planning, the use of the drilling template, the template guided insertion of two implants, as well as the integration of two ball attachments into a pre‐existing full denture. After the course participants were asked by questionnaire about the quality of the course and their personal opinion.

Results:  The course received an extraordinary positive feedback. In total 108 students evaluated the course with the overall grade of 1.68 according to the German school‐mark system (1 = excellent, 6 = unsatisfactory). Also the single parts of the course were voted constantly positively.

Conclusion:  The aim of this first interdisciplinary course for pre‐clinical students was to enhance competence level and practical implementation of implant dentistry at an early stage of education. Participants’ comments and suggestions on the questionnaires demonstrated the positive response and the general interest in this form of dental education, as well as the demand for further development of training in this field.
Participation in continuing professional development by dental practitioners in Victoria, Australia in 2007
Authors: Hopcraft M. S. , Manton D. J. , Chong P. L. , Ko G. , Ong P. Y. S. , Sribalachandran S. , Wang C.‐J. , Yong P. Y. , Jian L. F.
Published: October 2010

Background:  Mandatory continuing professional development (CPD) was introduced in 2005 in Victoria, Australia to ensure that dental practitioners maintained their skills, knowledge and kept up‐to‐date with current topics in dentistry. The aim of this study was to investigate the participation, impact on practice and attitudes of Victorian dentists and dental specialists to CPD activities since the commencement of mandatory CPD.

Methods:  A cross‐sectional survey of a random sample of registered dentists and dental specialists (n = 895) was conducted from May to August 2008 using an anonymous, postal, self‐administered questionnaire.

Results:  The response rate was 66%. More than three quarters of practitioners believed mandatory CPD is a reasonable requirement for continued registration. Dentists reported attending an average of 30.9 h of certifiable clinical CPD whilst specialists attended an average of 33.2 h of certifiable clinical CPD over a 12‐month period. Nearly three quarters of respondents reported changing their practice as a result of CPD activities, whilst one quarter attended CPD mainly to meet the mandatory requirements.

Conclusions:  Overall there was a positive attitude towards mandatory CPD and a high level of participation in CPD activities by Victorian dentists and specialists in 2007, although nearly half of the respondents attended <20 h of certified clinical CPD during 2007. A number of barriers exist, particularly for rural and female practitioners in accessing CPD, and further research is required to examine the benefits derived from mandatory CPD.
Dental nurses as trainers and assessors: vocational dental trainer attitudes
Authors: McKie A. E. , Crowe A. , McCombes W. , Freeman R.
Published: October 2010

Aim:  To explore the attitudes of vocational dental trainers (VDTs) working in general dental practice to the role of dental nurses as trainers and assessors of trainee dental nurses (tDNs), vocational dental practitioners (VDPs) and vocational dental hygienist/therapists (VDHTs).

Method:  This research was conducted within the context of the development of a training and assessment qualification for dental nurses. A survey was sent to all 148 VDTs in Scotland. The survey assessed VDT attitudes as to the appropriateness of dental nurses to train and assess tDNs, VDPs, VDHTs with regard to their clinical, communication‐based and administrative duties. The three sets of attitudes for tDNS, VDPS and VDHTs were assessed on a five‐point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree). The data were subjected to one way and repeated measures of ANOVA.

Results:  A total of 126 VDTs responded giving an 85% response rate. For clinical, communication‐based and administrative activities, VDTs had significantly greater mean scores for the appropriateness of DNs to train [F(1,57) = 45.69, P < 0.001] and assess [F(1,57) = 76.94, P < 0.001] tDNs compared with VDPs and VDHTs.

Conclusion:  Vocational dental trainers felt it was more appropriate for DNs to train and assess tDNs’ clinical, communication‐based and administrative activities compared with VDPs and VDHTs. Over 80% of dental trainers, however, indicated there would be benefit to their practice in having a dental nurse educated in the principles and application of training and assessment.
Latent variable approach to correct errors in radiographic measurements
Authors: Tu Yu‐Kang , Donos Nikos , Pometti Daniela , Nibali Luigi
Published: October 2010

Tu Y‐K, Donos N, Pometti D, Nibali L. Latent variable approach to correct errors in radiographic measurements. Eur J Oral Sci 2010; 118: 642–648. © 2010 Eur J Oral Sci

Radiographic outcomes are important for the diagnosis and treatment of periodontal diseases. However, the assessment of radiographic measurements is affected by many factors, and it is therefore difficult to ascertain changes in radiographic outcomes. In this study, we proposed a latent variable approach to correct for the distortion in the radiographic measurements in pairs of periapical radiographs taken before and after periodontal treatment. Clinical data from 123 patients treated with non‐surgical periodontal therapy was used to illustrate the latent variable approach in assessing radiographic changes in infrabony defect depth. Results were compared with a correction factor method. Computer simulations were also undertaken to evaluate the performance of these two methods compared with uncorrected, raw measurements by calculating their intraclass correlation coefficients (ICCs). The example data set showed that the latent variable method (LVM) and the correction factor method (CFM) were comparable. Simulations showed that both methods achieved very high ICCs in different scenarios, whilst uncorrected raw measurements had relatively low ICCs. This study suggests that correction for errors in radiographic measurements is required for routine radiographs. Whilst both LVM and CFM achieve excellent results, LVM is more flexible in handling missing values, and may provide better results when treatment effects are large.