Metastable Atrial State Underlies the Primary Genetic Substrate for MYL4 Mutation-Associated Atrial Fibrillation.

BACKGROUND: Atrial fibrillation (AF) is the most common clinical arrhythmia and is associated with heart failure, stroke, and increased mortality. The myocardial substrate for AF is poorly understood because of limited access to primary human tissue and mechanistic questions around existing in vitro or in vivo models. METHODS: Using an MYH6:mCherry knock-in reporter line, we developed a protocol to generate and highly purify human pluripotent stem cell-derived cardiomyocytes displaying physiological and molecular characteristics of atrial cells. We modeled human MYL4 mutants, one of the few definitive genetic causes of AF. To explore non-cell-autonomous components of AF substrate, we also created a zebrafish Myl4 knockout model, which exhibited molecular, cellular, and physiologic abnormalities that parallel those in humans bearing the cognate mutations. RESULTS: There was evidence of increased retinoic acid signaling in both human embryonic stem cells and zebrafish mutant models, as well as abnormal expression and localization of cytoskeletal proteins, and loss of intracellular nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide + hydrogen. To identify potentially druggable proximate mechanisms, we performed a chemical suppressor screen integrating multiple human cellular and zebrafish in vivo endpoints. This screen identified Cx43 (connexin 43) hemichannel blockade as a robust suppressor of the abnormal phenotypes in both models of MYL4 (myosin light chain 4)-related atrial cardiomyopathy. Immunofluorescence and coimmunoprecipitation studies revealed an interaction between MYL4 and Cx43 with altered localization of Cx43 hemichannels to the lateral membrane in MYL4 mutants, as well as in atrial biopsies from unselected forms of human AF. The membrane fraction from MYL4-/- human embryonic stem cell derived atrial cells demonstrated increased phospho-Cx43, which was further accentuated by retinoic acid treatment and by the presence of risk alleles at the Pitx2 locus. PKC (protein kinase C) was induced by retinoic acid, and PKC inhibition also rescued the abnormal phenotypes in the atrial cardiomyopathy models. CONCLUSIONS: These data establish a mechanistic link between the transcriptional, metabolic and electrical pathways previously implicated in AF substrate and suggest novel avenues for the prevention or therapy of this common arrhythmia.

Cost communication in cosmetic and reconstructive breast surgery: Public perceptions in the United States.

BACKGROUND: There is a need to better understand the financial toxicity of surgery on patients. Recent data demonstrated that plastic surgeons seldom discuss out-of-pocket costs with patients. Not much is known regarding the public perceptions of out-of-pocket cost communication in reconstructive and cosmetic breast surgery. METHODS: A cross-sectional survey was administered to adult women in the United States from November 2021 to December 2021 using Amazon Mechanical Turk. Perceptions regarding cost communication in plastic surgery were gathered. Incomplete responses were excluded. Multivariable models were used to identify predictors of responses. RESULTS: There were 512 complete responses. Respondents had a mean age of 37.4 years. The majority strongly agreed or agreed that plastic surgeons should discuss out-of-pocket costs with patients undergoing implant-based breast reconstruction (85%), plastic surgeons should know the impact of surgery on patients' financial well-being (78%), and discussing costs was the most important aspect of the appointment (70%). Respondents who were unsure of their insurance status had lower odds of strongly agreeing or agreeing that surgeons should discuss out-of-pocket costs for autologous reconstruction (OR 0.12, CI 0.02-0.58, p = 0.01) and cosmetic breast augmentation (OR 0.14, CI 0.03-0.65, p = 0.01). Privately insured respondents had greater odds of strongly agreeing or agreeing to both, respectively (OR 2.21, CI 1.32-3.82, p < 0.01; OR 1.94, CI 1.17-3.31, p = 0.01) CONCLUSION: Many laywomen support the cost communication in plastic surgery and believe that plastic surgeons should know the impact of surgery on the patients' financial well-being, with variability among the sociodemographic groups. Plastic surgeons should strongly consider discussing costs with patients undergoing breast surgery.

Optimizing Breast Reconstruction through Integration of Plastic Surgery and Radiation Oncology.

Post-mastectomy radiation therapy (PMRT) is an important adjunct to improve oncologic outcomes and survival in select breast cancer patients at increased risk for local recurrence. As recommendations for PMRT broaden, an increasing number of patients will have it included as part of their breast cancer treatment plan. METHODS: This overview of the literature strives to broaden the exposure of the plastic surgeon to PMRT and describe the indications, guidelines, and considerations relevant to reconstructive surgery. The primary targets and dosing considerations will also be reviewed. Finally, the short- and long-term toxicities are outlined with the goal of providing the plastic surgeon insights with which to recognize certain toxicities in the clinic during follow up and to develop the fluency to be able to talk to patients about the potential for certain toxicities. RESULTS: Generally, PMRT is safe and well tolerated. Considerations in breast reconstruction should be made on a patient-by-patient basis. Plastic surgeon familiarity with PMRT, its indications, and complications will amplify the surgeon's ability to optimize outcomes. CONCLUSIONS: As more women undergo breast reconstruction, an increasing number of patients will have PMRT as part of their breast cancer treatment plan. By understanding the basic principles of PMRT, plastic surgeons can engage patients in conversations of shared decision-making and maximize outcomes.

The Octopus Procedure Combined with Targeted Muscle Reinnervation for Elective Transhumeral Amputation.

Optimizing prosthetic function and tolerance are key principles of performing an elective upper extremity amputation. It is common for upper extremity amputees to experience issues related to nonoptimal prosthetic control and pain. Targeted muscle reinnervation and regenerative peripheral nerve interfaces in elective transhumeral amputations have been introduced as techniques to address the paucity of signals that may exist for myoelectric control postamputation. These techniques require the denervation of muscle and rely on delayed muscle reinnervation to provide eventual signal amplification for prosthetic function. In addition, the fascicles cannot be separated enough to provide signals to each individual muscle. Use of native innervated forearm musculature can provide more immediate and specific signals for prosthetic use. These native muscles are often not available for use due to trauma, denervation, or dysvascularization. In elective amputations, they can be used as spare parts to provide more signals for the sensors on a myoelectric prosthetic. The concept has been used in partial hand amputations and allowed for individual digital control at the terminal prosthetic device. In this study, we describe a novel technique used for an elective transhumeral amputation utilizing native innervated, vascularized musculature to provide intuitive control of a myoelectric prosthetic.

Fast and sensitive HPLC-MS/MS method for direct quantification of intracellular deoxyribonucleoside triphosphates from tissue and cells.

Deoxyribonucleoside triphosphates (dNTPs) are used in DNA synthesis and repair. Even slight imbalances can have adverse biological effects. This study validates a fast and sensitive HPLC-MS/MS method for direct quantification of intracellular dNTPs from tissue. Equal volumes of methanol and water were used for nucleotide extraction from mouse heart and gastrocnemius muscle and isolated cardiomyocytes followed by centrifugation to remove particulates. The resulting supernatant was analyzed on a porous graphitic carbon chromatography column using an elution gradient of ammonium acetate in water and ammonium hydroxide in acetonitrile with a run time of just 10min. Calibration curves of all dNTPs ranged from 62.5 to 2500fmol injections and demonstrated excellent linearity (r2>0.99). The within day and between day precision, as measured by the coefficient of variation (CV (%)), was <25% for all points, including the lower limit of quantification (LLOQ). The inter-day accuracy was within 12% of expected concentration for the LLOQ and within 7% for all other points on the calibration curve. The intra-day accuracy was within 22% for the LLOQ and within 11% for all points on the curve. Compared to existing methods, this study presents a faster and more sensitive method for dNTP quantification.