Lipid Oxidation Induced by RF Waves and Mediated by Ferritin Iron Causes Activation of Ferritin-Tagged Ion Channels

1. Download : Download high-res image (169KB)
2. Download : Download full-size image

     

AH jump duration is associated with elimination of slow pathway during ablation of atrioventricular nodal reentrant tachycardia

IntroductionAblating the slow pathway (SP) is the superior treatment for atrioventricular nodal reentrant tachycardia (AVNRT) with a low complication rate. However, the ablation of the SP could result in either complete elimination or modification of the SP. We aimed to investigate whether the duration of AH jump pre-ablation associated with the outcome of elimination of SP.MethodsWe included 56 patients with typical AVNRT (slow-fast), 20 males and 36 females, aged 44.2 ± 15.1 years. Slow pathway ablation was performed using classical approach. Univariate and multivariate analysis was performed for potential predictors of SP elimination.ResultsTypical AVNRT was inducible in all patients. Post-ablation, non-inducibility of AVNRT was obtained in all 56 (100%) patients, with SP elimination in 33 (61%) patients and SP modification in 23 (39%) patients. Patients with SP elimination had significantly longer AH jump than patients with SP modification. Cox regression analysis showed that AH jump duration was the independent predictor of SP elimination, in which every 20 ms increase in AH jump duration was associated with 1.30 higher rate of SP elimination. Furthermore, ROC curve analysis indicated that the AH jump duration of ≥100 ms had 6.14 times higher probability for complete elimination of the SP with a sensitivity of 79%, specificity of 70%, PPV of 79% and NPV of 70%.ConclusionsAH jump duration pre-ablation is associated with complete elimination of slow pathway during AVNRT ablation.     

Analysis of global DNA methylation changes in human keratinocytes immediately following exposure to a 900 MHz radiofrequency field

The increasing use of nonionizing radiofrequency electromagnetic fields (RF-EMFs) in a wide range of technologies necessitates studies to further understanding of biological effects from exposures to such forms of electromagnetic fields. While previous studies have described mechanisms for cellular changes occurring following exposure to low-intensity RF-EMFs, the role of molecular epigenetics has not been thoroughly investigated. Specifically unresolved is the effect of RF-EMFs on deoxyribonucleic acid (DNA) methylation, which is a powerful epigenetic process, used by cells to regulate gene expression. DNA methylation is dynamic and can be rapidly triggered in response to external stimuli such as exposure to RF-EMFs. In the present study, we performed a global analysis of DNA methylation patterns in human keratinocytes exposed to 900 MHz RF-EMFs for 1 h at a low dose rate (estimated mean specific absorption rate (SAR) < 10 mW/kg). We used a custom system to allow stable exposure of cell cultures to RF-EMFs under biologically relevant conditions (37 °C, 5% CO₂, 95% humidity). We performed whole genome bisulfite sequencing directly following RF-EMF exposure to examine the immediate changes in DNA methylation patterns and identify early differentially methylated genes in RF-EMF-exposed keratinocytes. By correlating global gene expression to whole genome bisulfite sequencing, we identified six common targets that were both differentially methylated and differentially expressed in response to RF-EMF exposure. The results highlight a potential epigenetic role in the cellular response to RF-EMFs. Particularly, the six identified targets may potentially be developed as epigenetic biomarkers for immediate responses to RF-EMF exposure. Bioelectromagnetics. 1–13, © 2023 Bioelectromagnetics Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.     

Eliciting Low-Risk Thyroid Cancer Treatment Preferences Using Clinical Vignettes: A Pilot Study

ObjectiveWhile surgical resection has been the traditional standard treatment for small (≤1 cm), differentiated thyroid cancers, active surveillance (AS) and radiofrequency ablation (RFA) are increasingly considered. The aim of this study was to explore patient preferences in thyroid cancer treatment using a series of clinical vignettes.MethodsThyroid cancer survivors and general population volunteers were recruited to rank experience-driven clinical vignettes in order of preference. Rankings were compared using Wilcoxon signed rank. Formative qualitative methods were used to develop and refine clinical vignettes that captured 4 treatments—thyroid lobectomy (TL), total thyroidectomy (TT), AS, and RFA—along with 6 treatment complications. Content was validated via interviews with 5 academic subspecialists.ResultsNineteen volunteers participated (10 survivors, 9 general population). Treatment complications were ranked lower than uncomplicated counterparts in 99.0% of cases, indicating excellent comprehension. Counter to our hypothesis, among uncomplicated vignettes, median rankings were 1 for AS, 2 for RFA, 3.5 for TL, and 5 for TT. Trends were consistent between thyroid cancer survivors and the general population. AS was significantly preferred over RFA (P = .02) and TT (P < .01). Among surgical options, TL was significantly preferred over TT (P < .01).ConclusionWhen treatments for low-risk thyroid cancer are described clearly and accurately through clinical vignettes, patients may be more likely to choose less invasive treatment options over traditional surgical resection.     

Atrial Tachycardia Originating from the Cavo-Tricuspid Isthmus May Exhibit Narrow P Waves

An 83-year-old man underwent electrophysiological testing for focal atrial tachycardia (AT) exhibiting narrow P waves with negative deflections in the inferior leads. Catheter ablation at the cavo-tricuspid isthmus (CTI) successfully eliminated the AT. The propagation map during AT and pacing study from the successful ablation site demonstrated that the atrial activation throughout the CTI did not produce significant P wave deflections. Consequently, during AT, the left atrial activation time determined the P wave duration. This case demonstrates that AT originating from the CTI may exhibit narrow P waves which can be misinterpreted as AT originating from the inter-atrial septum.     

Designed β-sheet-forming peptide 33mers with potent human bactericidal/permeability increasing protein-like bactericidal and endotoxin neutralizing activities

Novel peptide 33mers have been designed by incorporating β-conformation stabilizing residues from the β-sheet domains of α-chemokines and functionally important residues from the β-sheet domain of human neutrophil bactericidal protein (B/PI). B/PI is known for its ability to kill bacteria and to neutralize the action of bacterial endotoxin (lipopolysaccharide, LPS) which can induce septic shock leading to eventual death. Here, the goal was to make short linear peptides which demonstrate good β-sheet folding and maintain bioactivity as in native B/PI. A library of 24 peptide 33mers (βpep-1 to βpep-24) were synthesized with various amino acid substitutions. CD and NMR data acquired in aqueous solution indicate that βpep peptides form β-sheet structure to varying degrees and self-associate as dimers and tetramers like the α-chemokines. Bactericidal activity toward Gram-negative Pseudomonas aeruginosa was tested, and βpep-19 was found to be only about 5-fold less potent (62% kill at 1.2×10^?7 M) than native B/PI (80% kill at 2.9×10^?8 M). At LPS neutralization, βpep-2 and -23 were found to be most active (66–78% effective at 1.2×10^?6 M), being only about 50–100-fold less active than B/PI (50% at 1.5×10^?8 M). In terms of structure–activity relations, β-sheet structural stability correlates with the capacity to neutralize LPS, but not with bactericidal activity. Although a net positive charge is necessary for activity, it is not sufficient for optimal activity. Hydrophobic residues tend to influence activities indirectly by affecting structural stability. Furthermore, results show that sequentially and spatially related residues from the β-sheet domain of native B/PI can be designed into short linear peptides which show good β-sheet folding and retain much of the native activity. This research contributes to the development of solutions to the problem of multiple drug-resistant, opportunistic microorganisms like P. aeruginosa and of agents effective at neutralizing bacterial endotoxin.