Conduction Defects Research Articles

Boosting photocatalytic CO2 reduction by tuning photogenerated carrier kinetics in two-dimensional WOx/BiOCl S-scheme heterojunction with oxygen vacancies

Photocatalytic CO2 reduction driven by sustainable solar energy is a highly desirable route to achieve carbon recycling, to which charge separation in photocatalysts holds the key. In this work, two-dimensional (2D) WO3·H2O nanosheets with rich oxygen vacancies (Vo-WOx) were combined with 2D BiOCl nanosheets to form a 2D/2D Vo-WOx/BiOCl S-scheme heterojunction by a self-assembly process. The 2D/2D stacked structure combined with the introduction of oxygen vacancies in Vo-WOx could improve the light harvesting of the designed photocatalytic system. The dual transfer pathways in the S-scheme junction were induced by the fact that the photogenerated electrons on the conduction band and defect energy level of the Vo-WOx transfer across the interface to combine with the BiOCl, leading to an improved kinetic process of photogenerated carriers. Moreover, the S-scheme configuration can retain a strong redox potential for satisfying the thermodynamic requirement of CO2 reduction. As a result, the optimized 30Vo-WOx/BiOCl composite can achieve the highest CO yield rate of 8.82 μmol h−1 from CO2 reduction without any sacrifice reagents, which was 4.69 and 3.08 times higher than that of pure BiOCl and WO3/BiOCl without oxygen vacancy. This work provides a new view of defect engineering in S-scheme heterojunction for pursuing a highly efficient photocatalytic CO2 reduction system.

E-cigarettes and their lone constituents induce cardiac arrhythmia and conduction defects in mice

E-cigarette use has surged, but the long-term health effects remain unknown. E-cigarette aerosols containing nicotine and acrolein, a combustion and e-cigarette byproduct, may impair cardiac electrophysiology through autonomic imbalance. Here we show in mouse electrocardiograms that acute inhalation of e-cigarette aerosols disturbs cardiac conduction, in part through parasympathetic modulation. We demonstrate that, similar to acrolein or combustible cigarette smoke, aerosols from e-cigarette solvents (vegetable glycerin and propylene glycol) induce bradycardia, bradyarrhythmias, and elevations in heart rate variability during inhalation exposure, with inverse post-exposure effects. These effects are slighter with tobacco- or menthol-flavored aerosols containing nicotine, and in female mice. Yet, menthol-flavored and PG aerosols also increase ventricular arrhythmias and augment early ventricular repolarization (J amplitude), while menthol uniquely alters atrial and atrioventricular conduction. Exposure to e-cigarette aerosols from vegetable glycerin and its byproduct, acrolein, diminish heart rate and early repolarization. The pro-arrhythmic effects of solvent aerosols on ventricular repolarization and heart rate variability depend partly on parasympathetic modulation, whereas ventricular arrhythmias positively associate with early repolarization dependent on the presence of nicotine. Our study indicates that chemical constituents of e-cigarettes could contribute to cardiac risk by provoking pro-arrhythmic changes and stimulating autonomic reflexes.

Extended Near‐Infrared Photovoltaic Responses of Perovskite Solar Cells by p‐Type Phthalocyanine Derivative

AbstractThe absent photo‐response in near‐infrared (NIR) light (>800 nm) of lead‐based perovskite solar cells (PSCs) limits the further improvement of their power conversion efficiency (PCE). Here, a narrow bandgap p‐type phthalocyanine derivative (Copper(II) 2,3,9,10,16,17,23,24‐octakis((4‐(bis(4‐methoxyphenyl)amino)phenyl)ethynyl)phthalocyanine –8TPAEPC) with NIR absorption is synthesized to extend the photovoltaic response of perovskite to 850 nm. After doping the 8TPAEPC into the perovskite photoactive layer, the perovskite crystal quality is improved, resulting in its good electrical conductivity and less surface defects. Furthermore, the molecules stacking on the grain boundaries construct the charge transportation paths, as well as the p–n bulk heterojunction with enhanced built‐in potential. The target PSCs are optimized with notably enhanced PCE from 20% up to 22.10%, and excellent stability that is over 80% of the initial level at 70–80% relative humidity can be maintained for more than 500 h, benefiting from the improved hydrophobicity of 8TPAEPC. In addition, 8TPAEPC also serves as a dopant‐free, highly carrier‐mobile, and moreover, NIR‐responsive hole transport layer (HTL) with boosted PCE of 20.42% that reaches state of the art level among the dopant‐free metal phthalocyanines HTL‐based PSCs.

Atrial depolarization abnormalities in pulmonary sarcoidosis

BackgroundCardiac sarcoidosis, often manifested as sudden death, can be the first manifestation of sarcoidosis. Since 12-lead electrocardiogram (ECG) is recommended as an initial screening tool for cardiac sarcoidosis, the recognition of subtle abnormalities assumes utmost significance. The objective of this study was to identify the electrocardiographic abnormalities in patients with pulmonary sarcoidosis.ResultsA detailed analysis of 12-lead ECGs obtained from sixty patients with histopathologically proven pulmonary sarcoidosis and no overt cardiac involvement was done. The findings were compared with those of an age-matched control group. Varying degrees of intraventricular conduction defects were common in the study group [67%], as well as the control group [57%] [P = 0.23]. There was a higher prevalence of biphasic P wave [P = 0.003] and bifid P wave [P = 0.029] in lead III and rsr’ in lead aVF [P = 0.03] in the study group as compared to the control group.ConclusionsOur study demonstrates a greater prevalence of subtle ECG abnormalities in patients with pulmonary sarcoidosis as compared to patients with other forms of pulmonary disease. Atrial depolarization abnormalities were commoner in patients with pulmonary sarcoidosis.

Effects of UV-ozone treatment on the performance of deep-ultraviolet photodetectors based on ZnGa2O4 epilayers

ZnGa2O4 epilayers have been grown on sapphire using the metalorganic chemical vapor deposition system. However, there is a trade-off between high conductivity and large defect density (oxygen vacancies) with the growth time of the growth of ZnGa2O4 epilayers. The ultraviolet (UV)-ozone treatment on the ZnGa2O4 epilayer at 100 ° C was proposed to reduce the number of oxygen vacancies in ZnGa2O4. The effect of UV-ozone treatment on the performance of ZnGa2O4 metal-semiconductor-metal (MSM) photodetector (PD) was evaluated. X-ray photoelectron spectroscopy analysis showed a decrease in the number of oxygen vacancies after UV-ozone treatment of ZnGa2O4. The measured lattice parameter near the surface around 10 nm of untreated ZnGa2O4 was 8.3434 ± 0.0120 A˙ and increased slightly to 8.3775 ± 0.0083 A˙ after UV-ozone treatment due to the decrease in oxygen vacancies. The dark current (at 5 V) of ZnGa2O4 PD was significantly reduced from 251 to 20.2 pA before and after UV-ozone treatment; it resulted in a substantial one-order enhancement in the on/off ratio of the PDs from 2.7 × 105 and 2.15 × 106 after the UV-ozone treatment. Furthermore, the rejection ratio also improved between 240 and 470 nm from 35 to 84 after UV-ozone treatment. The relationship between photocurrent and light intensity and the improvement in raising and falling time also showed the reduced density of trap states by UV-ozone treatment. This indicates that UV-ozone treatment can enhance the characteristics of ZnGa2O4 PDs for UV sensing applications.

Detection of arrhythmias in patients with cardiac amyloidosis using implantable ECG recorders

Abstract Introduction Cardiac Amyloidosis frequently results in congestive cardiac failure and arrhythmias, from a disruption in cardiac substrate with subsequent electro-mechanical remodeling. Arrhythmias are vary based on the amyloidosis type. Conduction defects and atrial arrhythmias are more prevalent in transthyretin amyloidosis compared with light chain amyloidosis, and this difference might be a reflection of the longer survival time in the former. Methods 112 transthyretin amyloidosis (TTR) patients with completed underlying diagnosis including 99mTc-DPD scan, genetic testing and endomyocardioal biopsy (27%) without documented arrhythmias were randomized to standard clinical follow-up including arrhythmias or implantation of an ECG loop recorder (ILR). The classic FU took place in a heart failure clinic, and the group of patients with ILR was monitored by remote control with automatic daily report of the occurrence of arrhythmias by an independent organization. If an arrhythmia was detected, the patient was contacted immediately. The mean follow-up time for both groups was 17±7 months. Results The results are summarized in Table 1. Conclusions Currently, there is no consensus on the absolute benefit that ICDs in patients with cardiac amyloidosis. When non-sustained VT and syncope are captured and documented, ICD implantation for prevention of SCD in CA is most likely a reasonable approach. However, intensive monitoring of arrhythmias in patients with CA using ILR can lead to accurate and early detection of ventricular arrhythmias in particular and early initiation of ICD treatment as a prevention of SCD. Documentation of ventricular arrhythmias in CA patients was significantly higher by ILR (p<0.005) and was a clear predictor of patient survival (HR 2.51). Funding Acknowledgement Type of funding sources: None.

Is it worthwhile to perform surgical aortic valve replacement in elderly patients with symptomatic aortic valve disease and malignancy: a short and long-term study in 2,500 patients

Abstract Introduction Malignancy (all types) can be considered as limiting factor for the outcome of surgical aortic valve replacement (SAVR). Purpose How does the referral pattern evolve over time for patients with previously malignancy, referred for SAVR What is their early and long-term outcome after SAVR? Patients and methods This is a retrospective file study of 2,500 patients referred for SAVR with a biological prosthesis between 1987 and 2017. Mechanical valves and valve prosthesis in another position were excluded. A chi-square analysis was used to compare patients with and without cancer with respect to age, gender, era of referral (2008, the year of introduction of transcatheter aortic valve implantation, TAVI), preoperative cardiovascular (parameters for ventricular function, severity of valve disease, coronary disease, arrhythmias and conduction defects) and non-cardiac (pulmonary, renal, diabetes, cerebral) comorbid conditions, operative variables (bypass time, associated CABG and mitral valve repair), need for resources (blood products, stay on ICU) and early postoperative mortality, cardiac and non-cardiac events. A Kaplan-Meier (log-rank) analysis was used to evaluate the effect of malignancy on long-term outcome. Results Of the 2,500 patients, 388 (15.5%) patients had a documented prior malignancy There was a total of 18.917 patient-years for follow-up. For cancer patients, this was 2,489 patient-years. The referral of patients increased after 2008 (from 9.1% to 17.7%, p=0.006). Cancer patients had more chronic pulmonary (14.6% vs. 17.9%, p=0.044) and kidney (15.5% vs. 21.5%, p=0.009) disease, more prior CVA (14.8% vs. 19.8%, p=0.038) and permanent pacemaker implant (14.9% vs. 24/19%, p=0.044). Obesity was less present (18.4% vs. 14.2%). Cardiovascular and operative parameters were comparable for both groups. Postoperative cardiac and non-cardiac adverse events, need for resources and especially mortality (5.0% vs. 6.9%, p=0.105) were comparable. Long-term survival was significantly reduced in patients with malignancy (p<0.001), but this was acceptable: a mean survival time of 105 (98–113) months vs. 121 (118–125) months. Five-year survival was 70.0±2.4% vs. 76.6±0.9% Ten-year survival was 38.6%±1.3% vs. 48.9±2.9% Fifteen-year survival was 14.1±2.7% vs. 20±1.3% In a Cox' proportional hazard analysis, malignancy ranks 8th of 10 independent predictors for mortality (odds ratio 1.26). Conclusion Even after the introduction of TAVI, the number of valve patients with prior malignancy referred for SAVR increased significantly. Nevertheless, only non-cardiac preoperative factors differed significantly. Operative variables, use of resources and early outcome did not differ significantly. Malignancy reduces long-term survival in a significant but acceptable degree. Funding Acknowledgement Type of funding sources: None.

Cardiac Outcomes in Adults With Mitochondrial Diseases

BackgroundPatients with mitochondrial diseases are at risk of heart failure (HF) and arrhythmic major adverse cardiac events (MACE). ObjectivesWe developed prediction models to estimate the risk of HF and arrhythmic MACE in this population. MethodsWe determined the incidence and searched for predictors of HF and arrhythmic MACE using Cox regression in 600 adult patients from a multicenter registry with genetically confirmed mitochondrial diseases. ResultsOver a median follow-up time of 6.67 years, 29 patients (4.9%) reached the HF endpoint, including 19 hospitalizations for nonterminal HF, 2 cardiac transplantations, and 8 deaths from HF. Thirty others (5.1%) reached the arrhythmic MACE, including 21 with third-degree or type II second-degree atrioventricular blocks, 4 with sinus node dysfunction, and 5 sudden cardiac deaths. Predictors of HF were the m.3243A>G variant (HR: 4.3; 95% CI: 1.8-10.1), conduction defects (HR: 3.0; 95% CI: 1.3-6.9), left ventricular (LV) hypertrophy (HR: 2.6; 95% CI: 1.1-5.8), LV ejection fraction <50% (HR: 10.2; 95% CI: 4.6-22.3), and premature ventricular beats (HR: 4.1; 95% CI: 1.7-9.9). Independent predictors for arrhythmia were single, large-scale mtDNA deletions (HR: 4.3; 95% CI: 1.7-10.4), conduction defects (HR: 6.8; 95% CI: 3.0-15.4), and LV ejection fraction <50% (HR: 2.7; 95% CI: 1.1-7.1). C-indexes of the Cox regression models were 0.91 (95% CI: 0.88-0.95) and 0.80 (95% CI: 0.70-0.90) for the HF and arrhythmic MACE, respectively. ConclusionsWe developed the first prediction models for HF and arrhythmic MACE in patients with mitochondrial diseases using genetic variant type and simple cardiac assessments.

A Pilot Study of Electrocardiographic Features in Patients with Obesity from a Tertiary Care Centre in Southern India (Electron).

Background: Obesity is associated with increased all-cause mortality and cardiovascular disease (CVD). An electrocardiogram (ECG) may be used to screen for subtle signs of CVD or altered cardiac morphology in the obese. Methodology: This observational cross-sectional analysed ECG changes in patients with obesity at a tertiary care centre in southern India. Results: One hundred and fifty adult patients with a mean (SD) BMI of 39.9 (6.7) kg/m2 were recruited in the study after excluding those with comorbidities (diabetes mellitus, systemic hypertension) or on chronic medications (ACE inhibitors). The cohort showed a female predominance (69.3%), with a mean (SD) age of 45.4 (11.2) years. Most patients exhibited a sinus rhythm (78%), with one patient showing features of first-degree conduction block. Sinus tachycardia was seen in 32 (21.3%) patients. We observed left and right ventricular hypertrophy in five (3.3%) and three (2%) patients, respectively. Observed ECG patterns included a prolonged QTc in 16 (10.7%) patients, inverted T-waves (mostly in the inferior leads) in 39 (26%) patients and ST-segment depression (predominantly in the lateral leads) in 14 (9.3%) patients. A greater prevalence was noted for morbid obesity. No deaths were reported in our cohort. Conclusions: The predominant ECG variations in this cohort included tachycardia, atrial enlargement, ventricular hypertrophy, conduction defects, LAD, features of ischemia or old infarction and repolarization abnormalities, with a greater prevalence in morbid obesity. Further studies are needed to assess the impact of weight reducing measures on reversibility of these changes and determine the association with outcomes in obese patients.

OA15 A case of cardiac manifestation of systemic sclerosis

Introduction/BackgroundA 45-year-old lady, originally from Peru, with a background of diffuse cutaneous systemic sclerosis presented with shortness of breath on exertion, frequent palpitations, non-exertional chest tightness, and fatigue.Description/MethodIn 2011, she presented with inflammatory arthritis as well as Raynaud’s phenomenon. Her anti-nuclear antibody screen showed a positive anti-SCL-70 and anti-U3RNP. Over the years she developed pulmonary hypertension, renal involvement (proteinuria), dysphagia, cutaneous involvement (sclerodactyly, digital ulcers, telangiectasia) and interstitial lung disease. She was commenced on methotrexate and prednisolone. Her pulmonary hypertension was controlled on macitentan and sildenafil. Her pulse was 112 beats per minute, regular with a blood pressure of 168/85 mmHg. She had a loud P2 and a parasternal heave. She had sparse basal crepitations. She had mild pitting oedema to her knees. Her JVP was not raised. Her weight was 38kg.Her right heart catheterisation in April 2021 reported a mean pulmonary artery pressure of 24mmHg and pulmonary vascular resistance of 255 ARU. A computerized tomography (CT) scan of her chest showed known interstitial lung disease and no pulmonary embolism. Her lung function tests were stable. A cardiovascular magnetic resonance imaging (CMR) guided cardiac catheter in April 2021 showed scleroderma involvement of the heart, with mild pericardial effusion and elevated native myocardial T1 and T2. Left ventricular ejection fraction was normal. The impression was that of scleroderma with myocardia involvement. Her immunosuppression was escalated to cyclophosphamide. A cardiac MRI in September 2021 showed improvements in T1 and T2 mapping parameters. She completed 4 cycles of cyclophosphamide (15mg/kg). However, due to gastrointestinal side effects (nausea and vomiting) and a diagnosis of latent tuberculosis in February 2022, cyclophosphamide was stopped. In March 2022, her repeat CMR showed that the T1 and T2 mapping had slightly increased and presented again with chest pain and palpitations. Following a multi-disciplinary team discussion, the patient was treated with rituximab 500mg two weeks apart with 100mg of methylprednisolone as premedication prior to the infusions.Discussion/ResultsAlthough subclinical cardiac involvement in scleroderma is common, only 10 to 30% of patients are symptomatic. Our patients complained of non-exertional chest pain. Macrovascular coronary disease had been excluded; the cause of her chest pain was likely secondary to microvascular dysfunction. In patients with cardiac scleroderma, the mechanism of coronary disease is secondary to myocardial inflammation and repeated microvascular ischaemia. This results in reperfusion defects secondary to necrosis, in turn driving myocardial fibrosis. In the late stages, fibrosis results in left ventricular diastolic dysfunction, a complication related to increased mortality.Supraventricular tachycardia is one of the manifestations in conduction abnormalities in cardiac scleroderma: others include conduction defects and bradyarrhythmias. As with our patient, tachyarrhythmias can be associated with symptoms such as generalised fatigue, shortness of breath, and exercise intolerance.Another complication found on imaging was a small pericardial effusion. This is the most common pericardial disease in scleroderma. For most, pericardial effusions are asymptomatic; however, it can be associated with complications such as tamponade.Whilst cyclophosphamide is a common treatment choice for scleroderma with cardiac involvement, evidence for this is limited to case series due to its rarity. Additionally, it carries significant toxicity: Our case developed significant nausea and vomiting following her third and fourth cyclophosphamide infusions and this was discontinued also in light of her diagnosis of latent TB. Rituximab, the agent to which the patient was subsequently switched, similarly has a growing body of evidence in cardiac scleroderma. Since her rituximab infusions, our case has remained stable and she has noticed an improvement of her clinical symptoms.Key learning points/ConclusionCardiac scleroderma is associated with significant reduction in quality of life, morbidity, and mortality. It is often difficult to treat due to sparsity of high-quality evidence (as in other rare conditions) as well as the multiple organ systems and co-morbidities involved. This case illustrates the clinical manifestation of cardiac scleroderma and the difficulty in selecting appropriate immunosuppression medication.

Clipping electron transport and polarization relaxation of Ti3C2Tx based nanocomposites towards multifunction

High-performance multifunctional electromagnetic (EM) materials exhibit great potential for development, and have attracted extensive attention from the scientific field. Generally, the dielectric "genes", including conductive networks, interfaces, and defects, are the pivotal factors that determine their performance. Herein, multifunctional Ti3C2Tx@polyaniline decorated MWCNT (TPMC) nanocomposites, containing generous dielectric "genes", were synthesized via the electrostatic self-assembly method. Thanks to the regulation of internal dielectric "genes", TPMC exhibited a tunable EM wave absorption (EMA) and EM interference (EMI) shielding performance. TPMC achieved a maximum reflection loss (RL) of −54.7 dB and an effective absorption bandwidth (EAB) of nearly 6 GHz at 1.5 mm. Moreover, the complete conductive networks endowed TPMC with a reliable EMI shielding capability. It exhibited a maximum EMI shielding effectiveness (SE) of 34 dB, and meanwhile, displayed an absorption-dominated green shielding performance. Furthermore, owing to the integration of the "genes", TPMC showed a high coulomb efficiency (∼98%) and excellent cycling stability (exceeded 95% retation after 8000 cycles), indicating a great potential as outstanding supercapacitor electrode material. This work provides a promising strategy for controlling the EM pollution and alleviating the energy issues.

Microwave-Reduced Graphene Oxide for Aluminum Batteries

Recently, rechargeable graphene-based aluminum-ion batteries (AIBs) as an attractive energy storage system has been studied. Owing to the requirements such as high conductivity and low defects, the graphene cathode used in AIBs is typically fabricated using chemical vapor deposition (CVD). Here, we utilize solution-processable microwave-reduced graphene oxide (MWrGO) that has been shown to be of very high quality with low defect density as a cathode in AIBs. Our results show that it is possible to increase the AlCl4– ion storage with MWrGO, relative to thermally reduced graphene oxide (TrGO). The MWrGO film cathode for AIBs shows a stable discharge capacity of 87.7 mA h g–1 at 0.2 A g–1 with a coulombic efficiency of >93% and favorable rate capability that can withstand more than 4500 cycles without capacity decay at a high current density of 2 A g–1. The relationship between AlCl4– ion storage capability and microwave time has been examined to elucidate the fundamental relationship between AlCl4– intercalation and defects in graphene. We found that improved quality and lowered defects lead to higher diffusion-controlled contribution arising from the faradaic redox reaction, also leading to increased AlCl4– ion storage capability, whereas higher defects of graphene result in increased electrical double-layer capacity contribution but reduced AlCl4– ion storage capability.

Towards vertical Schottky diodes on bulk cubic silicon carbide (3C-SiC)

In this paper, we demonstrate the feasibility of fabricating vertical Schottky diodes on bulk cubic silicon carbide (3C-SiC) material obtained by combining sublimation epitaxy and chemical vapor deposition, starting from 4°-off axis 4H-SiC. First, the good quality of the epilayers grown with this method was demonstrated by morphological and structural analyses. Then, fabricated vertical Pt/3C-SiC Schottky diodes exhibited an ideality factor of 1.21 and a barrier height of 0.6 eV, as determined by thermionic emission model. The temperature dependent forward current analysis indicated the formation of an inhomogeneous barrier, which has been related with the presence of conductive surface defects, detected by nanoscale local current measurements. On the other hand, the reverse leakage current could be described by thermionic field emission model, including image force lowering. These findings demonstrate the viability of the proposed approach for bulk 3C-SiC growth for device fabrication. The material quality and the feasibility of fabricating vertical diodes based on 3C-SiC with a low barrier pave the way for the application of this polytype for medium-voltage power devices.

Impact of balloon predilatation in patients with reduced versus preserved ejection fraction during transcatheter aortic valve implantation

Although there is a trend toward direct transcatheter aortic valve implantation (TAVI), still balloon predilatation is necessary in some cases, especially in patients with severe calcification. However, predilatation including rapid ventricular pacing may have adverse outcomes, especially in patients with reduced ejection factor (EF). To evaluate the impact of predilatation on in-hospital outcomes in patients with reduced versus preserved EF underwent TAVI. This was a prospective observational study including 110 patients (72 patients with preserved EF (≥50%) and 38 patients with reduced EF (<50%)) who underwent TAVI. The two groups were compared regarding in-hospital outcomes. Predilatation was done routinely in all 110 patients. The mean age was significantly higher in patients with preserved EF (82.76 ± 5.74 vs. 80.13 ± 6.51 years; p = 0.03). The majority (51.4%) of patients with preserved EF were females but the majority (73.7%) of those with reduced EF were males (P < 0.001). Predilatation showed no statistical difference regarding in-hospital mortality (2.6% vs. 1.4%; p = 0.29), hemodynamic instability (5.3% vs. 0.0%; p = 0.11), stroke (0% vs. 1.4%; p = 0.67), conduction defects (13.2% vs. 19.4%; p = 0.29), permanent pacemaker implantation (7.9% vs. 5.5%; p = 0.45), paravalvular leakage (5.3% vs. 2.8%; p = 0.42), vascular complications (7.9% vs. 11.1%; p = 0.43), and acute kidney injury (7.9% vs. 7%; p = 0.4) in patients with reduced versus preserved EF, respectively. When balloon predilatation is inevitable during TAVI it is safe in patients with reduced as well as preserved EF with no added risk of hemodynamic instability or other outcomes.

Mitochondrial Genome Variants as a Cause of Mitochondrial Cardiomyopathy.

Mitochondria are small double-membraned organelles responsible for the generation of energy used in the body in the form of ATP. Mitochondria are unique in that they contain their own circular mitochondrial genome termed mtDNA. mtDNA codes for 37 genes, and together with the nuclear genome (nDNA), dictate mitochondrial structure and function. Not surprisingly, pathogenic variants in the mtDNA or nDNA can result in mitochondrial disease. Mitochondrial disease primarily impacts tissues with high energy demands, including the heart. Mitochondrial cardiomyopathy is characterized by the abnormal structure or function of the myocardium secondary to genetic defects in either the nDNA or mtDNA. Mitochondrial cardiomyopathy can be isolated or part of a syndromic mitochondrial disease. Common manifestations of mitochondrial cardiomyopathy are a phenocopy of hypertrophic cardiomyopathy, dilated cardiomyopathy, and cardiac conduction defects. The underlying pathophysiology of mitochondrial cardiomyopathy is complex and likely involves multiple abnormal processes in the cell, stemming from deficient oxidative phosphorylation and ATP depletion. Possible pathophysiology includes the activation of alternative metabolic pathways, the accumulation of reactive oxygen species, dysfunctional mitochondrial dynamics, abnormal calcium homeostasis, and mitochondrial iron overload. Here, we highlight the clinical assessment of mtDNA-related mitochondrial cardiomyopathy and offer a novel hypothesis of a possible integrated, multivariable pathophysiology of disease.

A Patient of Limb-girdle Muscular Dystrophy Type 1B Presenting with Heart Failure and Cardiac Conduction Defects: A Case Report

Background: Limb-girdle muscular dystrophy type 1B (LGMD1B) are characterised by cardiac dysrhythmias, late-onset cardiomyopathy, slowly progressive skeletal myopathy and contractures of the neck, elbows and ankles. The causative mutation is in lamin A/C gene (autosomal dominant LGMD1B). Objective: To assess the clinical outcome of a patient of limb-girdle muscular dystrophy type 1B with heart failure and cardiac conduction defects. The case: We report a case of 47-yr-old male with proximal muscle weakness who presented with repeated exertional dyspnea and repeated presyncope. ECG revealed junctional bradycardia. Echocardiography revealed global wall motion abnormality with EF 48%. EMG showed myopathic pattern. Next genome sequencing showed that the patient has a missense mutation in exon 4 region of LMNA gene (c.G662A/p.Arg221His). Cardiac involvement is very common in this disease which includes AV block, bradycardia, atrial tachycardia, atrial fibrillation and ventricular dysrhythmia causing sudden death. Our patient presented with symptomatic junctional bradycardia which necessitates implantation of permanent pacemaker. Conclusion: Cardiologists should be aware of these unusual genetic diseases with conduction defects, especially in young adults. Bangladesh Med Res Counc Bull 2022; 48(1): 76-80

NADPH Oxidase Mediates Oxidative Stress and Ventricular Remodeling through SIRT3/FOXO3a Pathway in Diabetic Mice.

Oxidative stress and mitochondrial dysfunction are important mechanisms of ventricular remodeling, predisposed to the development of diabetic cardiomyopathy (DCM) in type 2 diabetes mellitus. In this study, we have successfully established a model of type 2 diabetes using a high-fat diet (HFD) in combination with streptozotocin (STZ). The mice were divided into three groups of six at random: control, diabetes, and diabetes with apocynin and the H9c2 cell line was used as an in vitro model for investigation. We examined the molecular mechanisms of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation on mitochondrial dysfunction and ventricular remodeling in the diabetic mouse model. Hyperglycemia-induced oxidative stress led to a reduced expression of sirtuin 3 (SIRT3), thereby promoting forkhead box class O 3a (FOXO3a) acetylation in ventricular tissue and H9c2 cells. Reactive oxygen species (ROS) overproduction promoted ventricular structural modeling and conduction defects. These alterations were mitigated by inhibiting NADPH oxidase with the pharmaceutical drug apocynin (APO). Apocynin improved SIRT3 and Mn-SOD expression in H9c2 cells transfected with SIRT3 siRNA. In our diabetic mouse model, apocynin improved myocardial mitochondrial function and ROS overproduction through the recovery of the SIRT3/FOXO3a pathway, thereby reducing ventricular remodeling and the incidence of DCM.

Facile Synthesis of Conductive Metal-Organic Frameworks Nanotubes for Ultrahigh-Performance Flexible NO Sensors.

Cu-benzenehexathiol (Cu-BHT) has attracted significant attention due to its record high electrical conductivity and crystal defects Cu2c . However, the nonporous structure and small specific surface area of Cu-BHT with two-dimensional kagome lattice invariably limit its practical application in sensing and catalysis. In this work, Cu-BHT nanotubes (Cu-BHT-NTs) are designed and prepared via a facile homogeneous reaction to solve these problems. Compared with the traditional nanorod-like structure, the Cu-BHT-NTs not only have a higher specific surface area but also possess a higher proportion of crystal defects (66.6%). The successfully configured DPPTT/Cu-BHT-NTs heterostructure organic field-effect transistor (OFET)-based sensor exhibits excellent sensitivity as high as 13610%, a minimum detection limits down to 5ppb, and exceptional selectivity to nitric oxide (NO) toxic gases. Theoretical analysis systematically shows that Cu2c sites in the Cu-BHT-NTs increase the number of electrons transferred from the heterostructure to NO molecules, confirming that the high sensitivity and selectivity result from the high binding between Cu-BHT-NTs and NO molecules. Furthermore, a fully flexible device based on the heterojunction OFET sensor is prepared to ensure the convenience of wearing and carrying gas sensors, opening up a new avenue for the next generation of wearable intelligent electronics.

The effect of coronavirus infection on QT and QTc intervals of hospitalized patients in Qazvin, Iran

Electrocardiographic (ECG) changes have been investigated in the condition of coronavirus disease (COVID-19) indicating that COVID-19 infection exacerbates arrhythmias and triggers conduction abnormalities. However, the specific type of ECG abnormalities in COVID-19 and their impact on mortality fail to have been fully elucidated. The present retrospective, tertiary care hospital-based cross-sectional study was conducted by reviewing the medical records of all patients diagnosed with COVID-19 infection who were admitted to Booali Sina Hospital in Qazvin, Iran from March to July 2020. Demographic information, length of hospital stay, treatment outcome, and electrocardiographic information (heart rate, QTc interval, arrhythmias, and blocks) were extracted from the medical records of the patients. Finally, a total of 231 patients were enrolled in the study. Atrial fibrillation was a common arrhythmia, and the left anterior fascicular block was a common cardiac conduction defect other than sinus arrhythmia. The deceased patients were significantly older than the recovered ones (71 ± 14 vs. 57 ± 16 years, p < 0.001). Longer hospital stay (p = 0.036), non-sinus rhythm (p < 0.001), bundle and node blocks (p = 0.002), ST-T waves changes (p = 0.003), and Tachycardia (p = 0.024) were significantly prevalent in the deceased group. In baseline ECGs, no significant difference was observed in terms of the absolute size of QT; however, a prolonged QTc in the deceased was about twice of the recovered patients (using Bazett, Sagie, and Fridericia’s formula). Serial ECGs are recommended to be taken from all hospitalized patients with COVID-19 due to increased in-hospital mortality in patients with prolonged QTc interval, non-sinus rhythms, ST-T changes, tachycardia, and bundle, and node blocks.

Novel design of Sulfur-doped nickel cobalt layered double hydroxide and polypyrrole nanotube composites from zeolitic imidazolate Framework-67 as efficient active material of battery supercapacitor hybrids

Nickel and cobalt layered double hydroxide (NiCo-LDH) has large specific surface area and interlayer spacing, multiple redox states and high ion-exchange capability, but poor electrical conductivity, severe agglomerations and structural defect restrict energy storage ability of NiCo-LDH as active materiel of battery supercapacitor hybrids (BSH). In this study, it is the first time to design sulfur-doped NiCo-LDH and polypyrrole nanotubes composites (NiCo-LDH-S/PNTs) from zeolitic imidazolate framework-67 (ZIF-67) as the efficient active material of BSH using electrospinning and hydrothermal processes. Effects of sulfur doping amounts are investigated. The one-dimensional hollow polypyrrole decorated with NiCo-LDH-S sheets with high aspect ratio provides straight charge-transfer routes and abundant contacts with electrolyte. The highest specific capacitance (CF) of 1936.3 F/g (specific capacity of 322.8 mAh/g) is achieved for the NiCo-LDH-S/PNTs with sulfur doping amount of 7% at 10 mV/s. The BSH comprising graphene LDH negative electrode and NiCo-LDH-S/PNTs positive electrode shows the maximum energy density of 16.28 Wh/kg at 650 W/kg. The CF retention of 74% and Coulombic efficiency of 90% are also achieved after 8000 charge/discharge cycles.