Publications by authors named "David Shim"

Article Synopsis
  • Paroxysmal atrial fibrillation (pAF) can develop into persistent atrial fibrillation (psAF), but some patients experience psAF without previous pAF, which might influence their response to direct current cardioversion (DCCV).
  • This study aimed to analyze how a history of pAF impacts recurrence rates post-DCCV in patients with their first psAF episode.
  • Findings showed that patients with primary psAF had longer AF survival times and less recurrence after DCCV compared to those with a history of pAF, suggesting that pAF patients may require more proactive rhythm control strategies.
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Radiofrequency (RF) ablation can be a source of electromagnetic interference (EMI) for cardiovascular implantable electronic devices (CIEDs). The response of CIEDs to this type of EMI can be variable and unpredictable. We report a case with an uncommon response where there was a failure to deliver pacing pulses to both atrial and ventricular pacing leads during RF ablation close to the atrial lead even when the pacemaker was set to pace asynchronously.

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Sensor data from missile flights are highly valuable, as a test requires considerable resources, but some sensors may be detached or fail to collect data. Remotely acquired missile sensor data are incomplete, and the correlations between the missile data are complex, which results in the prediction of sensor data being difficult. This article proposes a deep learning-based prediction network combined with the wavelet analysis method.

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Background: While initial studies suggest that same-day discharge or shortened bedrest may be feasible for some patients following atrial fibrillation (AF) ablation, the risks and benefits of this approach remain unclear for patients undergoing hemostasis with figure-of-eight (FO8) suture technique.

Methods: We prospectively evaluated access site bleeding, length of hospitalization, urinary catheterization, and other clinical outcomes in patients undergoing AF ablation with 3 hours of bedrest between April and May 2021, and compared them to a control group that had undergone AF ablation with 6 hours of bedrest from April to July 2019. FO8 sutures were used for hemostasis in all patients.

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Superior vena cava (SVC) syndrome is a rare complication associated with transvenous cardiac implantable electronic devices that may present with a variety of manifestations. Various strategies such as transvenous lead extraction, anticoagulation, venoplasty, and stenting have been used to treat this condition, but the optimal management protocols have yet to be defined. Subcutaneous implantable cardioverter-defibrillator (ICD) (S-ICD) therapy can be an alternative option to a transvenous system for those who require future ICD surveillance.

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Objectives: This study sought to investigate the sensitivity of electroanatomical mapping (EAM) to detect scar as identified by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR).

Background: Previous studies have shown correlation between low voltage electrogram amplitude and myocardial scar. However, voltage amplitude is influenced by the distance between the scar and the mapping surface and its extent.

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Importance: Administration of hydroxychloroquine with or without azithromycin for the treatment of coronavirus disease 2019 (COVID-19)-associated pneumonia carries increased risk of corrected QT (QTc) prolongation and cardiac arrhythmias.

Objective: To characterize the risk and degree of QT prolongation in patients with COVID-19 in association with their use of hydroxychloroquine with or without concomitant azithromycin.

Design, Setting, And Participants: This was a cohort study performed at an academic tertiary care center in Boston, Massachusetts, of patients hospitalized with at least 1 positive COVID-19 nasopharyngeal polymerase chain reaction test result and clinical findings consistent with pneumonia who received at least 1 day of hydroxychloroquine from March 1, 2020, through April 7, 2020.

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In recent years, research concerning autonomous driving has gained momentum to enhance road safety and traffic efficiency. Relevant concepts are being applied to the fields of perception, planning, and control of automated vehicles to leverage the advantages offered by the vehicle-to-everything (V2X) communication technology. This paper presents a V2X communication-aided autonomous driving system for vehicles.

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Background: Pulsed field ablation (PFA) is a nonthermal energy that may provide safety advantages over radiofrequency ablation (RFA). One-shot PFA catheters have been developed for pulmonary vein isolation, but they do not permit flexible lesion sets. This study investigated a novel lattice-tip catheter designed for focal RFA or PFA ablation.

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Abnormal NFκB activation has been implicated in Alzheimer's disease (AD). However, the signaling pathways governing NFκB regulation and function in the brain are poorly understood. We identify complement protein C3 as an astroglial target of NFκB and show that C3 release acts through neuronal C3aR to disrupt dendritic morphology and network function.

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Background: The transcription factor NFκB is an important mediator of cell survival and inflammation in the immune system. In the central nervous system (CNS), NFκB signaling has been implicated in regulating neuronal survival following acute pathologic damage such as traumatic brain injury (TBI) and stroke. NFκB is normally bound by the principal inhibitory protein, IκBα, and sequestered in the cytoplasm.

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Background: Though originally discovered in the immune system as an important mediator of inflammation, NF-κB has recently been shown to play key roles in the central nervous system, such as synaptogenesis, synaptic plasticity, and cognition. NF-κB activity is normally tightly regulated by its primary inhibitor, IκBα, through a unique autoinhibitory loop. In this study, we tested the hypothesis that the IκBα autoinhibitory loop ensures optimal levels of NF-κB activity to promote proper brain development and function.

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Feedback regulation of transcription factor NF-kappaB by its inhibitor IkappaBalpha plays an essential role in control of NF-kappaB activity. To understand the biological significance of IkappaBalpha-mediated feedback regulation of NF-kappaB, we generated mice harboring mutated kappaB enhancers in the promoter of the IkappaBalpha gene (IkappaBalpha(M/M)) to inhibit NF-kappaB-regulated IkappaBalpha expression. Here, we report that these mutant mice are defective in NF-kappaB-induced expression of IkappaBalpha.

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Ubiquitination regulates the degradation, membrane trafficking, and transcription of proteins. At mammalian synapses, the ubiquitin-proteasome system (UPS) influences synaptic transmission and plasticity. Nicotine also has the ability to affect synaptic function via mechanisms that remain partially unknown.

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To assess the efficacy of self versus heterologous ErbB-2 vaccines, the reactivity to human and rat ErbB-2 (Her-2 and neu, respectively) DNA vaccines were tested in normal, Her-2 or neu transgenic mice. When immunized with either Her-2 or neu DNA, normal BALB/c and C57BL/6 mice produced cross-reactive T cells, but only antigen specific antibodies. In Her-2 Tg mice, weak to no anti-Her-2 response was induced by either self Her-2 or heterologous neu DNA, demonstrating profound tolerance to Her-2 and the inability to induce anti-Her-2 immunity with either vaccine.

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When CD4+ CD25+ regulatory T cells are depleted or inactivated for the purpose of enhancing antitumor immunity, the risk of autoimmune disease may be significantly elevated because these regulatory T cells control both antitumor immunity and autoimmunity. To evaluate the relative benefit and risk of modulating CD4+ CD25+ regulatory T cells, we established a new test system to measure simultaneously the immune reactivity to a tumor-associated antigen, neu, and an unrelated self-antigen, thyroglobulin. BALB/c mice were inoculated with TUBO cells expressing an activated rat neu and treated with anti-CD25 monoclonal antibody to deplete CD25+ cells.

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Tyrosine phenol-lyase (TPL) from Citrobacter freundii is dependent on monovalent cations, K(+) or NH(4)(+), for high activity. We have shown previously that Glu-69, which is a ligand to the bound cation, is important in monovalent cation binding and activation [Sundararaju, B., Chen, H.

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Purpose: In circulations with pulsatile pulmonary artery flow the pulmonary venous wedge pressure (PVWp) has been validated as a good estimate of pulmonary artery pressure (PAp), when PAp is low. The purpose of this study was to validate PVWp estimates of PAp in the less-pulsatile pulmonary circulation of children after bidirectional Glenn shunts.

Methods: A retrospective study was performed of 22 simultaneous measurements of PVWp and PAp made during 20 catheterizations in 19 children who had undergone bidirectional Glenn procedures.

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Purpose: Dry eye syndrome is prevalent in post-menopausal women, and post-menopausal women secrete less mucus in their reproductive tracts. Using a mouse model, the purpose of this study was to determine if estrogen and/or progesterone regulates Muc4 and Muc5AC gene expression in the ocular surface epithelia, as the hormones do in reproductive tract epithelia.

Methods: Adult C57BL/6 mice were ovariectomized, and 19 days later, pellets containing estrogen, progesterone, or a combination were inserted subcutaneously.

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Kawasaki disease is an acute systemic vasculitis of unknown etiology that has become the most common form of acquired heart disease in young children in developing countries. The most serious threat from Kawasaki disease is the development of coronary vasculitis, with subsequent development of aneurysms, thrombosis, and coronary compromise. Standard treatment during the acute phase of Kawasaki disease now consists of intravenous gamma globulin, 2 g/kg, given as a single dose, and high-dose aspirin therapy, 80 to 100 mg/kg daily.

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Objective: To determine the incidence of catheter-related surgical emergencies during pediatric interventional catheterization procedures.

Study Design: We reviewed all interventional catheter procedures (n = 578) over a 4-year period (April 1996 to April 2000) to determine any complication during interventional catheterization that required surgery within 24 hours after catheterization.

Results: The overall incidence of surgical emergencies was 1.

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