Estimate of the Coulomb correlation energy in CeAg2Ge2 from inverse photoemission and high resolution photoemission spectroscopy

The occupied and the unoccupied electronic structure of CeAg2Ge2 single crystal has been studied using high resolution photoemission and inverse photoemission spectroscopy, respectively. High resolution photoemission reveals the clear signature of Ce 4f states in the occupied electronic structure which was not observed clearly in our earlier studies. The Coulomb correlation energy in this system has been determined experimentally from the position of the 4f states above and below the Fermi level. Theoretically, the correlation energy has been determined by using the first principles density functional calculations within the generalized gradient approximations taking into account the strong intra-atomic (on-site) interaction Hubbard Ueff term. The calculated valence band shows minor changes in the spectral shape with increasing Ueff due to the fact that the density of Ce 4f state is narrow in the occupied part and is hybridized with the Ce 5d, Ag 4d and Ge 4p states. On the other hand, substantial changes are observed in the spectral shape of the calculated conduction band with increasing Ueff since the density of Ce 4f state is very large in the unoccupied part, compared to other states. The estimated value of correlation energy for CeAg2Ge2 from the experiment and the theory is ≈ 4.2 eV. The resonant photoemission data are analyzed in the framework of the single-impurity Anderson model which further confirms the presence of the Coulomb correlation energy and small hybridization in this system.

The predictive value of echocardiographic parameters associated with left ventricular diastolic dysfunction on short- and long-term outcomes of catheter ablation of atrial fibrillation

AIMS

Recurrence of atrial fibrillation (AF) is frequently observed after AF catheter ablation. However, the predictive value of echocardiographic parameters associated with left ventricular diastolic dysfunction (LVDD) has not been well studied.

METHODS AND RESULTS

In 124 consecutive patients (mean age 61 ± 10 years, 60% male) with paroxysmal (n = 70) or persistent AF (n = 54) undergoing AF catheter ablation, mitral early diastolic peak (E-wave) and late peak (A-wave) velocities, E/A ratio, deceleration time (DT) of mitral early velocity, early diastolic mitral annulus peak velocity (e'), and E/e' ratio were determined by transthoracic echocardiography. Early (ERAF) and late AF recurrence (LRAF) were monitored with 7-day Holter electrocardiograms directly after catheter ablation and after 6 and 12 months. Early AF recurrence occurred in 34% of the patients, while LRAF was observed in 27% of the patients. Patients with ERAF had higher E-wave (0.9 ± 0.2 vs. 0.8 ± 0.2 m/s, P = 0.035) and lower A-wave velocity (0.5 ± 0.2 vs. 0.6 ± 0.2 m/s, P = 0.038), higher E/A ratio (1.8 ± 0.9 vs. 1.5 ± 0.9, P = 0.089), and slower DT (214 ± 67 vs. 243 ± 68 ms, P = 0.073), while E/e', left atrial diameter, and left ventricular ejection fraction were similar. In multivariable regression analysis, the E/A ratio was the only independent predictor of ERAF (odds ratio 2.905, 95% confidence interval 1.072-7.870, P = 0.036). None of the echocardiographic parameters influenced the late therapy outcome.

CONCLUSION

Early results of the catheter ablation, but not the late rhythm outcome, are influenced by an impaired mitral inflow pattern, which is associated with LVDD.

Impact of Metabolic Syndrome on Left Atrial Electroanatomical Remodeling and Outcomes After Radiofrequency Ablation of Nonvalvular Atrial Fibrillation

Background—

Recent studies reported worse outcomes after atrial fibrillation (AF) ablation in patients with metabolic syndrome (MetS). However, mechanisms of AF recurrence in MetS remain unclear.

Method and Results—

We performed pulmonary vein isolation and voltage mapping in 236 patients with AF (age 61±9.6 years; persistent AF 64%; MetS 54%). Left atrial (LA) low voltage areas were semiquantitatively estimated and presented as low voltage index. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel III. Follow-up for AF recurrence ≤12 months was performed. LA low voltage areas were observed in 46% of patients with MetS versus 8.2% patients without MetS ; P <0.0001. MetS was an independent predictor of LA low voltage areas: odds ratio, 11.64; 95% confidence interval, 4.381–30.903; P <0.0001. Observed AF recurrence at 12 months was 42.7% in MetS versus 36.1% in the non-MetS group ( P =0.303). The presence of LA low voltage areas was a predictor of 12-month AF recurrence: odds ratio, 2.99; 95% confidence interval, 1.36–6.56; P =0.006. Probability of 12-month AF recurrence increased with 84.5% for every unit of low voltage Index.

Conclusions—

MetS was not associated with worse outcomes after radiofrequency catheter ablation of AF, but LA low voltage areas were more frequently observed in patients with MetS. The presence and extent of LA low voltage areas may influence the long-term outcomes after catheter ablation.

Cerium oxide nanoparticles prevent apoptosis in primary cortical culture by stabilizing mitochondrial membrane potential

Cerium oxide nanoparticles (CNPs) of spherical shape have unique antioxidant capacity primarily due to alternating + 3 and + 4 oxidation states and crystal defects. Several studies revealed the protective efficacies of CNPs in cells and tissues against the oxidative damage. However, its effect on mitochondrial functioning, downstream effectors of radical burst and apoptosis remains unknown. In this study, we investigated whether CNPs treatment could protect the primary cortical cells from loss of mitochondrial membrane potential (Δψm) and Δψm-dependent cell death. CNPs with spherical morphology and size range 7-10 nm were synthesized and utilized at a concentration of 25 nM on primary neuronal culture challenged with 50 μM of hydrogen peroxide (H2O2). We showed that optimal dose of CNPs minimized ROS content of the cells and also curbed related surge in cellular calcium flux. Importantly, CNPs treatment prevented apoptotic loss of cell viability. Reduction in the apoptosis could be successfully attributed to the maintenance of Δψm and restoration of major redox equivalents NADH/NAD(+) ratio and cellular ATP. These findings, therefore, suggest possible route of CNPs protective efficacies in primary cortical culture.

Comparison of CHADS2, R2CHADS2, and CHA2DS2-VASc scores for the prediction of rhythm outcomes after catheter ablation of atrial fibrillation: the Leipzig Heart Center AF Ablation Registry

BACKGROUND

Recurrences of atrial fibrillation (AF) occur in up to 30% within 1 year after catheter ablation. This study evaluated the value of CHADS2, R2CHADS2, and CHA2DS2-VASc scores for the prediction of rhythm outcomes after AF catheter ablation.

METHODS AND RESULTS

Using the Leipzig Heart Center AF Ablation Registry, we documented rhythm outcomes within the first 12 months in 2069 patients (67% men; 60±10 years; 35% persistent AF) undergoing AF catheter ablation. AF recurrences were defined as any atrial arrhythmia occurring within the first week (early recurrences, ERAF) and between 3 and 12 months (late recurrences, LRAF) after ablation. ERAF and LRAF occurred in 36% and 33%, respectively. On multivariable analysis, R2CHADS2 (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.02-1.21; P=0.016) and CHA2DS2-VASc (OR, 1.09; 95% CI, 1.017-1.17; P=0.015) scores as well as persistent AF and left atrial diameter were significant predictors for ERAF. Similarly, the same clinical variables remained significant predictors for LRAF even after adjustment for ERAF, which was the strongest predictor for LRAF (HR, 3.12; 95% CI, 2.62-3.71; P<0.001). However, using receiver operating characteristic curve analyses, both scores demonstrated relatively low predictive value for ERAF (area under the curve [AUC], 0.536 [0.510-0.563]; P=0.007; and AUC, 0.547 [0.521-0.573]; P<0.001 for R2CHADS2 and CHA2DS2-VASc, respectively) and LRAF (AUC, 0.548 [0.518-0.578]; P=0.002; and AUC, 0.550 [0.520-0.580]; P=0.001).

CONCLUSIONS

R2CHADS2 and CHA2DS2-VASc were associated with rhythm outcomes after catheter ablation. However, AF type, left atrial diameter, and especially ERAF are also significant predictors for LRAF that should be included into new clinical scores for the prediction of rhythm outcomes after catheter ablation.

Outcomes in Catheter Ablation of Ventricular Tachycardia in Dilated Nonischemic Cardiomyopathy Compared With Ischemic Cardiomyopathy

Background—

Data on the outcomes of ventricular tachycardia (VT) ablation in nonischemic dilated cardiomyopathy (NIDCM) are insufficient. The Heart Center of Leipzig VT (HELP-VT) study was conducted prospectively to compare outcomes after radiofrequency catheter ablation of VT in patients with NIDCM compared with ischemic cardiomyopathy (ICM).

Methods and Results—

Two hundred twenty-seven patients, 63 with NIDCM and 164 with ICM, presenting with sustained VT were ablated with radiofrequency catheter ablation. Noninducibility of any clinical and nonclinical VT was achieved in 66.7% of NIDCM and in 77.4% of ICM patients. Ablation of the clinical VT only was achieved in 18.3% of ICM and in 22.2% of NIDCM patients. There was no statistically significant difference in short-term outcomes between the 2 groups. At the 1-year follow-up, VT-free survival in NIDCM was 40.5% compared with 57% in ICM. In univariate analysis, the hazard ratio for VT recurrence was significantly higher for NIDCM (1.62; 95% confidence interval, 1.12– 2.34; P =0.01). In both the ICM and NIDCM subgroups, procedure failure and incomplete procedural success were independent predictors of VT recurrence.

Conclusions—

Although the short-term success rates after VT ablation in NIDCM and ICM patients were similar, the long-term outcomes in NIDCM patients were significantly worse. Complete VT noninducibility at the end of the ablation is associated with beneficial long-term outcome in NIDCM. Pursuing compete elimination of all inducible VTs is desirable and may improve the long-term success in NIDCM.

Understanding the local environment of Sm3+ in doped SrZrO3 and energy transfer mechanism using time-resolved luminescence: a combined theoretical and experimental approach

A combined experimental and theoretical study on the photoluminescence (PL) properties of strontium zirconate (SZ) and Sm³⁺ doped SZ nanostructures is presented in this work.

Origin of blue emission in ThO2 nanorods: exploring it as a host for photoluminescence of Eu3+, Tb3+ and Dy3+

Nanorods of ThO₂ were synthesized in a reverse micelle technique using cetyl trimethyl ammonium bromide as a surfactant and characterized by X-ray diffraction and transmission electron microscopy.

Long-term follow-up after atrial fibrillation ablation in patients with impaired left ventricular systolic function: the importance of rhythm and rate control

BACKGROUND

Atrial fibrillation (AF) ablation is increasingly used in patients with reduced left ventricular ejection fraction (LVEF), but long-term outcomes are still unknown.

OBJECTIVE

To assess the long-term effects of AF ablation in patients with systolic heart failure according to rhythm outcome.

METHODS

We included 69 patients with LVEF ≤40%, referred for circumferential pulmonary vein isolation with or without additional substrate modification to our institution in 2006-2010. Follow-up included 7-day Holter electrocardiography and echocardiography at baseline and at 6, 12, and 24 months after ablation. A matched control group (n = 69) after AF ablation without heart failure was used for comparison.

RESULTS

After 28 ± 11 months and 1.6 ± 0.7 ablation procedures, 45 (65%) patients were still in the stable sinus rhythm (SSR) group. LVEF increased from 33 ± 6% to 53 ± 11% (P < .001) in the SSR group and from 33 ± 5% to 38 ± 12% (P = .03) in patients with recurrences (atrial tachycardia/fibrillation group). While LVEF increase was similar in the 2 groups at 6 months (15 ± 12% vs 8 ± 11%; P = .2), further LVEF improvements were observed in the SSR group only. Adjustments for baseline characteristics revealed that the increase in LVEF at 6 months was associated with higher baseline heart rate and not with rhythm outcome. Heart rate did not change in either group after 6 months of follow-up. Complications and procedural data of the study group were similar to the control group.

CONCLUSION

In patients with heart failure undergoing AF ablation, there is an initial short-term LVEF improvement related to baseline heart rate. However, long-term LVEF improvement is associated with rhythm outcome.

Sociodemographic and clinical profile of homeless mentally ill inpatients in a north Indian medical university

Homeless mentally ill (HMI) persons are a highly vulnerable and socially disadvantaged population, deprived of even the basic minimal human rights. Data on HMI in India is scarce. This retrospective chart review aimed to evaluate socio-demographic, socio-cultural and clinical profile of HMI patients, and to study reasons of homelessness and outcome related variables in these patients. One hundred and forty homeless persons were admitted to the department of psychiatry of a north Indian medical university from February 2005 to July 2011. Of these, one hundred and twenty-seven (90.7%) had psychiatric illness and six had only intellectual disabilities. The majority of HMI persons were illiterate/minimally literate, adult, male, and from low socioeconomic and rural backgrounds. Most of the patients (55.7%) had more than one psychiatric diagnosis. HMI had considerably high rates of co-morbid substance abuse (44.3%), intellectual disabilities (38.6%) and physical problems (75.4%). Most (84.3%) were mentally ill before leaving home and 54.3% left home themselves due to the illness. Most HMI responded to the treatment. After treatment of mental illness, it was possible to reintegrate about 70% of the patients into their families. Families were willing to accept and support them. Untreated/inadequately treated mental illness was the most common reason for homelessness. Easily accessible treatment and rehabilitation facilities at low cost can improve the plight of such patients. Further research in this area is required.

Renal Dysfunction, Stroke Risk Scores (CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 ), and the Risk of Thromboembolic Events After Catheter Ablation of Atrial Fibrillation

Background—

There are limited data on the predictive value of stroke risk scores for thromboembolic events (TEs) after catheter ablation of atrial fibrillation (AF). Our objectives were to report the incidence of TEs after AF ablation in a large contemporary AF ablation cohort and to investigate the impact of renal dysfunction and the value of stroke risk stratification scores (CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 ) for predicting TE after AF ablation.

Methods and Results—

Using the Leipzig Heart Center AF Ablation Registry, we documented TEs in patients undergoing radiofrequency AF catheter ablation. TE was defined as stroke, transient ischemic attack, or systemic embolism. Study population (N=2069; 66% men; 60±10 years; 62% paroxysmal AF; mean CHADS 2 , 1.2±0.9; CHA 2 DS 2 -VASc, 2.1±1.4; and R 2 CHADS 2 , 1.3±1.1) were followed up for a median 18 (Q1–Q3, 12–29) months (ie, 3078 patient-years). Overall, 31 TEs occurred, with 16 events within 30 days of ablation and 15 TEs (0.72%) during the follow-up period. On multivariate analysis, CHADS 2 ( P <0.001), R 2 CHADS 2 ( P <0.001), and CHA 2 DS 2 -VASc ( P =0.003) scores were independent predictors of TEs during follow-up, and AF recurrence conferred a nonsignificant trend for increased TE risk ( P =0.071–0.094). The CHA 2 DS 2 -VASc score further differentiated TE risk in patients with CHADS 2 and R 2 CHADS 2 0 to 1 (0.13% if CHA 2 DS 2 -VASc was 0–1 and 0.71% if CHA 2 DS 2 -VASc was >2) and had the best predictive value in patients with AF recurrences (c-index 0.894, P =0.022 versus CHADS 2 , P =0.031 versus R 2 CHADS 2 ).

Conclusions—

CHADS 2 , CHA 2 DS 2 -VASc, and R 2 CHADS 2 scores were associated with TE risk. The CHA 2 DS 2 -VASc score differentiated TE risk in the low-risk strata based on CHADS 2 and R 2 CHADS 2 scores and may be superior in the subgroup with AF recurrences.