A novel alternating second-generation cryoballoon or contact-force guided radiofrequency catheter ablation strategy for redo-ablation in patients with recurrent atrial fibrillation: a single-center experience.

BACKGROUND: Pulmonary vein (PV) reconnection after radiofrequency (RFC) or cryoballoon (CB) pulmonary vein isolation (PVI) is common. METHOD: We report a single-center experience of 156 patients who underwent a redo procedure-ablation strategy for recurrent atrial fibrillation (AF) in a reverse sequence after a failed index RFC or CB PVI. RESULTS: A total of 60 patients after index CB PVI underwent RFC-redo ablation (CB-RFC redo), and 96 patients after index RFC PVI underwent CB-redo ablation (RFC-CB redo). During the redo procedure, the proportion of patients with PV reconnection was lower after index CB PVI procedure compared with the proportion of patients after index RFC PVI (88.3% versus 98.9%, p = 0.01). Additionally, a mean number of 1.50 ± 0.8 PVs/patient were reconnected after index CB PVI, compared with 3.36 ± 0.9 PVs/patient after index RFC PVI (p = 0.001). Patients after index RFC PVI frequently presented with ≥ 3 reconnected PVs, compared with index CB PVI (70.8% vs 10%, p < 0.001). At a 2-year follow-up, 43 patients (27.6%) developed recurrence after redo ablation, with a similar AF-free outcome (CB-RFC redo:73.3% vs RFC-CB redo: 71.9%, p = 0.873). In the multivariate analysis, persistent AF (HR = 2.107, 95% CI: 1.085-4.091, p = 0.028) and early AF recurrence after the initial ablation (HR = 2.431, 95% CI: 1.279-4.618, p = 0.007) were independent predictors of AF recurrence. CONCLUSIONS: The extent and distribution of PV reconnections were different after index RFC and CB PVI procedures. Alternating CB or RFC ablation technique strategy is effective with a similar long-term outcome, and it may be an appropriate option for repeated AF ablation.

The pre-ablation triglyceride-glucose index predicts late recurrence of atrial fibrillation after radiofrequency ablation in non-diabetic adults.

BACKGROUND: Current prognostic risk scoring systems and biomarkers are routinely used as non-invasive methods for assessing late recurrence of atrial fibrillation (AF) in patients who have undergone radiofrequency catheter ablation (RFCA). This study aimed to investigate the predictive value of the triglyceride-glucose (TyG) index for late AF recurrence after RFCA in non-diabetic patients. METHODS: In total, 275 patients with AF who underwent RFCA at the Fuwai hospital (Beijing, China) between January 2016 and December 2018 were enrolled in this study. During follow up, patients were divided into late and non-late AF recurrence groups, based on whether they had experienced late AF recurrence determined by electrocardiography (ECG) examine or 48 h Holter monitoring. The TyG index was calculated using the following equation: ln [fasting triglycerides [mg/dL] × fasting glucose [mg/dL]/2]. RESULTS: During a median follow-up of 26.1 months, late AF recurrence event rates significantly increased in the highest TyG index tertile group (tertile 3) compared to the lowest group (tertile 1) (54% versus 12%, respectively; p < 0.001). The mean TyG index was higher in the late AF recurrence group compared to the non- late AF recurrence group (9.42 ± 0.6 versus 8.68 ± 0.70, respectively; p < 0.001). On multivariate Cox regression analysis, the pre-ablation TyG index was an independent risk factor for late recurrence of AF after RFCA (hazard ratio [HR] 2.015 [95% confidence interval (CI): 1.408-4.117]; p = 0.009). Receiver operating characteristic (ROC) curve analysis revealed that TyG index was a significant predictor of late AF recurrence after RFCA, with an area under the ROC curve (AUC) of 0.737 (95% CI: 0.657-0.816; p < 0.001). In addition, the AUC of left atrial diameter (LAD) was 0.780 (95%CI: 0.703-0.857, p < 0.001). Finally, the TyG index positively correlated with LAD (r = 0.133, p = 0.027), high sensitivity C-reactive protein (r = 0.132, p = 0.028) and N-terminal pro B-type natriuretic peptide (r = 0.291, p < 0.001) levels. CONCLUSIONS: An elevated pre-ablation TyG index was associated with an increased risk of late AF recurrence after RFCA in non-diabetic patients. The TyG index may be potentially useful as a novel biomarker for the risk stratification of late AF recurrence in non-diabetic patients.

Sequential versus optimized pulmonary vein isolation for paroxysmal atrial fibrillation: a pilot study.

PURPOSE: We aimed to investigate whether the sequence of wide circumferential pulmonary vein isolation (PVI) ablation had an effect on the acute reconnection or long-term effectiveness in patients with paroxysmal atrial fibrillation (AF). METHODS: One hundred consecutive paroxysmal AF patients, who were scheduled to accept PVI, were enrolled and randomized into two groups: (1) optimized group. Lesions were first applied to the anterior/posterior carina and the ridge between the left atrial (LA) appendage and the left pulmonary vein (PV). Then both circles were closed with continuous lesions. (2) Sequential group-continuous circular lesions were created counter-clockwise and started from the site of 6 o'clock. The primary endpoint was the freedom from non-blanking period recurrence of any atrial tachyarrhythmias lasting for 30 s or longer during the 1-year follow-up period after a single procedure. The secondary endpoint included safety endpoints, LA dwelling time, and fluoroscopy time/dose. RESULTS: Forty-nine patients in the optimized group and 48 patients in the sequential group were available for analysis. There was no difference between the AF-free rate of the optimized group and the sequential group (75.5% vs. 72.9%, p = 0.7715). Cox regression analysis found that acute reconnection had the potential to predict long-term recurrence at 1 year (Risk ratio 2.175, p = 0.0818). Both groups had similar safety endpoints, LA dwelling time, and fluoroscopy time/dose. CONCLUSIONS: Adjusting the ablation sequence of PVI by ablating the anterior/posterior carina and the ridge between the left PV and the LA appendage first did not improve 1-year AF-free rate for paroxysmal AF.

Risk of New-Onset Atrial Fibrillation Post-cavotricuspid Isthmus Ablation in Typical Atrial Flutter Without History of Atrial Fibrillation.

Aims: The aim was to describe the incidence of atrial fibrillation (AF) after cavotricuspid isthmus (CTI) ablation in patients with typical atrial flutter (AFL) without history of AF and to identify risk factors for new-onset AF after the procedure. Methods: A total of 191 patients with typical AFL undergoing successful CTI ablation were enrolled. Patients who had history of AF, structural heart disease, cardiac surgery, or ablation or who received antiarrhythmic drug after procedure were excluded. Clinical and electrophysiological data were collected. Results: There were 47 patients (24.6%) developing new AF during a follow-up of 3.3 ± 1.9 years after CTI ablation. Receiver operating characteristic (ROC) curves indicated that the cut-off values of left atrial diameter (LAD) and CHA2DS2-VASc score were 42 mm and 2, with area under the curve of 0.781 and 0.550, respectively. The multivariable Cox regression analysis revealed that obstructive sleep apnea (OSA) [hazard ratio (HR) 3.734, 95% confidence interval (CI) 1.470-9.484, P = 0.006], advanced interatrial block (aIAB) (HR 2.034, 95% CI 1.017-4.067, P = 0.045), LAD > 42 mm (HR 2.710, 95% CI 1.478-4.969, P = 0.001), and CHA2DS2-VASc score > 2 (HR 2.123, 95% CI 1.118-4.034, P = 0.021) were independent risk factors of new-onset AF. Conclusion: A combination of OSA, aIAB, LAD > 42 mm, and CHA2DS2-VASc > 2 was a strongly high risk for new-onset AF after ablation for typical AFL, and it had significance in postablation management in clinical practice.

Machine learning prediction of pyrolytic gas yield and compositions with feature reduction methods: Effects of pyrolysis conditions and biomass characteristics.

This study aimed to utilize machine learning algorithems combined with feature reduction for predicting pyrolytic gas yield and compositions based on pyrolysis conditions and biomass characteristics. To this end, random forest (RF) and support vector machine (SVM) was introduced and compared. The results suggested that six features were adequate to accurately forecast (R2 > 0.85, RMSE < 5.7%) the yield while the compositions only required three. Moreover, the profound information behind the models was extracted. The relative contribution of pyrolysis conditions was higher than that of biomass characteristics for yield (55%), CO2 (73%), and H2 (81%), which was inverse for CO (12%) and CH4 (38%). Furthermore, partial dependence analysis quantified the effects of both reduced features and their interactions exerted on pyrolysis process. This study provided references for pyrolytic gas production and upgrading in a more convenient manner with fewer features and extended the knowledge into the biomass pyrolysis process.

Peroxydisulfate/oxygen system-based electrochemiluminescent immunosensing of Hg2+ using Pt/Pd nanodendrites-thiosemicarbazide/norfloxacin as a signal enhancer.

Herein, we describe a competitive-type electrochemiluminescence (ECL) strategy for Hg2+ determination based on the peroxydisulfate/oxygen (S2O82-/O2) system that uses Pt/Pd nanodendrites (Pt/Pd NDs)-thiosemicarbazide/norfloxacin (TN)-covered gold nanoparticles (Pt/Pd-TNG50) as a signal enhancer. The Pt/Pd NDs, a dense array of Pt branches on a Pd core, possessed excellent catalytic properties to enhance ECL intensity by accelerating electron transfer. In addition, the binary intramolecular synergy of TN, which had cooperative interactions of powerful π-π stacking with a larger conjugated surface, could extremely enhance the ECL signal of the S2O82-/O2 system. Furthermore, we designed a competitive immunoassay method using a structured sensor where a monoclonal antibody (mAb) against Hg2+ exhibited high specificity and recognition of Hg2+, which greatly improved the specificity and sensitivity of the immunosensor. As a result, the proposed immunosensor gave Hg2+ detection with a low detection limit (16 pg mL-1) and displayed high sensitivity and stability. Importantly, this work not only, for the first time to our knowledge, utilized Pt/Pd NDs as promising ECL emitters for bioprobe construction but also opened an efficient way for the detection of Hg2+ in environmental monitoring.

Overexpression of miR-22 attenuates oxidative stress injury in diabetic cardiomyopathy via Sirt 1.

BACKGROUND/AIMS: Oxidative stress injury is believed to be important in diabetic cardiomyopathy. Recent evidence indicates that miR-22 plays an important role in various cardiovascular diseases, but the protective role of miR-22 in diabetic cardiomyopathy remains undetermined. METHODS: Diabetes was induced in male C57BL/6 mice by intraperitoneal injection with streptozotocin combined with a high-fat diet, and miR-22 was overexpressed following transfection with adeno-associated virus. Cardiac function was assessed by echocardiography and a cardiac catheter system. In vitro study, H9c2 cells were treated with normal or high glucose (HG), and cell viability or apoptosis was detected using the Cell Counting Kit-8 (CCK-8) assay and flow cytometry, respectively. Reactive oxygen species, malondialdehyde, and superoxide dismutase were also detected in diabetic mice and H9c2 cells. The expression level of miR-22 was detected by real-time PCR. The protein expression of Sirt 1, oxidative stress injury-related proteins (GRP78, CHOP, ATF 3), and apoptosis-related proteins Bax/Bcl-2, cl-casp-9/casp-9, and cl-casp-3/casp-3 were determined by Western blotting analysis. RESULTS: HG-induced oxidative stress injury and apoptosis were observed in H9c2 cells, which were ameliorated by miR-22. Cardiac dysfunction and severely altered heart structure were also observed in diabetic mice and were dramatically reversed by overexpression of miR-22. The expression of Sirt 1 decreased significantly in diabetic mice and HG-treated H9c2 cells. Overexpression of miR-22 restored the level of Sirt 1. Bioinformatics analysis predicted that Sirt 1 was a potential target gene of miR-22. Luciferase reporter assay verified that miR-22 promoted Sirt 1 expression by direct binding to the Sirt 1 3'untranslated repeats. Upregulation of Sirt 1 could improve cell viability and attenuate oxidative stress injury and apoptosis in the HG-treated H9c2 cells, similar to the effect of miR-22. However, the protective effects of miR-22 against HG-induced oxidative stress injury and apoptosis were abrogated by knockdown of Sirt 1. CONCLUSIONS: Overexpression of miR-22 can attenuate oxidative stress injury in diabetic cardiomyopathy by upregulation of Sirt 1 in vivo and in vitro.

Highly sensitive determination of diclofenac based on resin beads and a novel polyclonal antibody by using flow injection chemiluminescence competitive immunoassay.

A novel flow injection chemiluminescence immunoassay for simple, sensitive and low-cost detection of diclofenac was established based on specific binding of antigen and antibody. Carboxylic resin beads used as solid phase carrier materials provided good biocompatibility and large surface-to-volume ratio for modifying more coating antigen. There was a competitive process between the diclofenac in solution and the immobilized coating antigen to react with the limited binding sites of the polyclonal antibody to form the immunocomplex. The second antibody labelled with horseradish peroxidase was introduced into the immunosensor and trapped by captured polyclonal antibody against diclofenac, which could effectively amplify chemiluminescence signals of luminol-PIP-H2O2. Under optimal conditions, the diclofenac could be detected quantitatively. The chemiluminescence intensity decreased linearly with the logarithm of the diclofenac concentration in the range of 0.1-100ngmL-1 with a detection limit of 0.05ngmL-1 at a signal-to-noise ratio of 3. The immunosensor exhibited high sensitivity, specificity and acceptable stability. This easy-operated and cost-effective analytical method could be valuable for the diclofenac determination in real water samples.

Involvement of activation of C-met signaling pathway in CD151-induced HUVECs angiogenesis.

CD151 is a member of the tetraspanin family that is implicated as a promoter of pathological or physiological angiogenesis. C-Met is expressed on a variety of cells including vascular endothelial cells (VECs) and up-regulated during angiogenesis. In this study, we investigated whether CD151 regulated migration, proliferation, tube formation and angiogenesis of human umbilical VECs (HUVECs) with activation of C-Met. Moreover, we studied whether CD151 could affect the angiogenic molecules such as nitric oxide (NO), vascular cell adhesion molecule-1 (VCAM-1) and vascular endothelial growth factor (VEGF). The expression of CD151 was determined by Western blotting. The cell proliferation assay was performed using the cell counting kit-8 (CCK-8) method and cell migration was assessed in microchemotaxis chambers by using fetal bovine serum (FBS) as the chemotactic stimulus. The angiogenic molecules were evaluated using ELISA. The NO level was detected using NO detection kit. The potential involvement of various signaling pathways was explored using relevant antibodies. We found that proliferation, migration and tube formation of HUVECs were promoted by CD151 with activation of C-Met, FAK and CDC42, while they were suppressed with CD151 knockdown by RNAi. Similarly, the levels of NO, VCAM-1 and VEGF in HUVECs were increased by CD151, but they were inhibited with CD151 knockdown by RNAi. These data suggested that CD151 could promote migration, proliferation, tube formation and angiogenesis of HUVECs, which was possibly related to the C-Met signaling pathways.

A quantum dot based electrochemiluminescent immunosensor for the detection of pg level phenylethanolamine A using gold nanoparticles as substrates and electron transfer accelerators.

This study reports the development of an electrochemiluminescent (ECL) immunosensor for ultrasensitive detection of phenylethanolamine A (PA) based on CdSe quantum dots (QDs) and gold nanoparticles (GNPs). The GNPs/ovalbumin-PA/anti-PA-QD immunosensor was fabricated layer by layer using GNPs as substrates and electron transport accelerators. The use of GNPs greatly enhanced the sensitivity for detecting PA due to the excellent electron transportation ability and the large surface area of GNP carriers allowing several binding events of ovalbumin-PA on each nanosphere. Transmission electron microscopy images (TEM), photoluminescence spectra, ultraviolet-visible absorption spectra and dynamic light scattering (DLS) were used to characterize the QDs and GNPs. The sensor was characterized with electrochemical impedance spectra (EIS), and a strong ECL emission of the modified electrode could be observed during the cathodic process of S2O8(2-) and QDs in air-saturated PBS buffer containing 0.1 M K2S2O8 and 0.1 M KCl (pH 7.4). With a competitive immunoassay format, the ECL signal depended linearly on the logarithm of the phenylethanolamine A concentration within a range of 0.02 ng mL(-1) to 50 ng mL(-1), and the detection limit was 0.0047 ng mL(-1), much lower than those reported in the literature. This ECL immunosensor is rapid, simple and sensitive with acceptable precision, and it will extend the application of QD ECL in immunoassays of ß-agonists and open new avenues for the detection of food additive residues in the future.

Quantum dots based electrochemiluminescent immunosensor by coupling enzymatic amplification for ultrasensitive detection of clenbuterol.

An ultrasensitive electrochemiluminescence (ECL) immunosensor based on CdSe quantum dots (QDs) has been designed for the detection of clenbuterol. The immunosensor was fabricated by layer by layer and characterized with atomic force microscopic images (AFM) and electrochemical impedance spectra (EIS). In oxygen-saturated pH=9.0 Tris-HCl buffer, a strong ECL emission of QDs could be observed during the cathodic process due to the H2O2 product from electrochemical reduction of dissolved oxygen. Upon the formation of immunocomplex, the second antibody labeled with horseradish peroxidase was simply immobilized on the electrode surface. The ECL emission decreased since steric hindrance of the immunocomplex slowed down the electron-transfer speed of dissolved oxygen, and also could be greatly amplified by an enzymatic cycle to consume the self-produced coreactant. Using clenbuterol as model analyte, the ECL intensity was determined by the concentration of competitive immunoassay of clenbuterol with a wide calibration in the range of 0.05 ng mL(-1) to 1000 ng mL(-1), and a low detection limit was 0.02 ng mL(-1). The immunosensor shows good stability and fabrication reproducibility. It was applied to detecting practical samples with the satisfactory results. This immunosensing strategy opens a new avenue for detection of residue and application of QDs in ECL biosensing.

Communication scheduling to minimize thermal effects of implanted biosensor networks in homogeneous tissue.

A network of biosensors can be implanted in a human body for health monitoring, diagnostics, or as a prosthetic device. Biosensors can be organized into clusters where most of the communication takes place within the clusters, and long range transmissions to the base station are performed by the cluster leader to reduce the energy cost. In some applications, the tissues are sensitive to temperature increase and may be damaged by the heat resulting from normal operations and the recharging of sensor nodes. Our work is the first to consider rotating the cluster leadership to minimize the heating effects on human tissues. We explore the factors that lead to temperature increase, and the process for calculating the specific absorption rate (SAR) and temperature increase of implanted biosensors by using the finite-difference time-domain (FDTD) method. We improve performance by rotating the cluster leader based on the leadership history and the sensor locations. We propose a simplified scheme, temperature increase potential, to efficiently predict the temperature increase in tissues surrounding implanted sensors. Finally, a genetic algorithm is proposed to exploit the search for an optimal temperature increase sequence.