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Background: Patients with likely pathogenic/pathogenic desmoplakin ( DSP ) variants are poorly characterized. Some of them meet diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC), but it is unclear how risk stratification strategies for ARVC perform in this setting., Objectives: The purpose of this study was to characterize arrhythmic outcomes and to test the performance of the recently validated ARVC risk calculator in patients with DSP likely pathogenic/pathogenic variants fulfilling definite 2010 ARVC Task Force Criteria ( DSP -TFC+)., Methods: DSP -TFC+ patients were enrolled from 20 institutions across 3 continents. Ventricular arrhythmias (VA), defined as a composite of sustained ventricular tachycardia (VT), appropriate implantable cardioverter defibrillator therapies, and ventricular fibrillation/sudden cardiac death events in follow-up, were reported as the primary outcome. We tested the performance of the ARVC risk calculator for VA prediction, reporting c-statistics., Results: Among 252 DSP -TFC+ patients (age 39.6 ± 16.9 years, 35.3% male), 94 (37.3%) experienced VA over 44.5 [IQR: 19.6-78.3] months. Patients with left ventricle involvement (n = 194) were at higher VA risk (log-rank P  = 0.0239). History of nonsustained VT (aHR 2.097; P  = 0.004) showed the strongest association with VA occurrence during the first 5-year follow-up. Neither age ( P  = 0.723) nor male sex ( P  = 0.200) was associated with VAs at follow-up. In 204 patients without VA at diagnosis, incident VA rate was high (32.8%; 7.37%/y). The ARVC risk calculator performed poorly overall (c-statistic 0.604 [0.594-0.614]) and very poorly in patients with left ventricular disease (c-statistic 0.558 [0.556-0.560])., Conclusions: DSP -TFC+ patients are at substantial risk for VAs. The ARVC risk calculator performs poorly in DSP -TFC+ patients suggesting need for a gene-specific risk algorithm. Meanwhile, DSP -TFC+ patients with nonsustained VT should be considered as high-risk., Competing Interests: The Johns Hopkins ARVC program (Dr James, Gasperetti, Calkins, Carrick, Murray, and Tondo) is supported by the Leonie-Wild Foundation, the Leyla Erkan Family Fund for ARVD Research, the Hugh Calkins, Marvin H. Weiner, and Jacqueline J. Bernstein Cardiac Arrhythmia Center, the Dr Francis P. Chiramonte Private Foundation, the Dr Satish, Rupal, and Robin Shah ARVD Fund at 10.13039/100007880Johns Hopkins, the Bogle Foundation, the Campanella family, the Patrick J. Harrison family, the 10.13039/501100019817Peter French Memorial Foundation, and the Wilmerding Endowments and 10.13039/100000002NIH/10.13039/100006108NCATS UL1 TR003098. ASJMtR and PVT acknowledge support from the Netherlands Cardiovascular Research Initiative, an initiative with support of the Netherlands Heart Foundation, grant nos. CVON2018-30 PREDICT2, CVON2015-12 eDETECT, 2020B005 Double Dose. ASJMtR is supported by the 10.13039/501100001826ZonMW Off-Road Grant 2021. The Zurich ARVC Program is supported by the 10.13039/501100011561Georg und Bertha Schwyzer-Winiker Foundation, 10.13039/501100007252Baugarten Foundation, Wild Foundation, 10.13039/501100001711Swiss National Science Foundation (SNF), and the 10.13039/501100004362Swiss Heart Foundation. The Bologna Cardiomyopathy Registry has received funding support from the 10.13039/501100003196Italian Ministry of Health, RC-2022-2773270 project AAMW received funding from CVON Predict-2. Dr Mestroni is supported by 10.13039/100000002NIH R01HL69071, R01HL116906, R01HL147064, 10.13039/100000002NIH/10.13039/100006108NCATS UL1 TR002535 and UL1 TR001082. Dr Yazdani is supported by 10.13039/501100000274British Heart Foundation FS/CRTF/23/24448 and Alexander Jansons Myocarditis UK. Dr Prasad has received funding from Alexander Jansons Myocarditis UK, 10.13039/501100000833Rosetrees Trust, and 10.13039/501100000274British Heart Foundation. Dr Medo is supported by the 10.13039/100001825Rose Foundation. This work was supported by the 10.13039/501100000265Medical Research Council (UK), 10.13039/501100000274British Heart Foundation [RE/18/4/34215], the 10.13039/501100013342NIHR Imperial College Biomedical Research Centre, the 10.13039/501100000272NIHR Royal Brompton Biomedical Research Centre, and the 10.13039/501100000282Sir Jules Thorn Charitable Trust [21JTA]. Dr Saguner has received educational grants through his institution from Abbott, Bayer Healthcare, Biosense Webster, Biotronik, Boston Scientific, BMS/Pfizer, and Medtronic; and speaker/advisory board/consulting fees from Abbott, Bayer Healthcare, Daiichi-Sankyo, Medtronic, Novartis, and Pfizer. Dr Lakdawala has received unrestricted research support from Pfizer and the O’Hare and Steggall Family Foundations and consulting fees from BMS, Pfizer, Cytokinetics, Sarepta, and Tenaya. Dr Mestroni received educational grant from Greenstone; and advisory board/consulting fees from Tenaya, StrideBio, and Unicure. Dr Gasperetti received advisory board/consulting fees from Lexeo, and has served as an unpaid consultant for StrideBio. Dr James has received research grants from StrideBio Inc and Lexeo Inc; has received advisory board/consulting fees from Pfizer and Lexeo; and has served as an unpaid consultant for StrideBio and Tenaya. Dr Ware has received research support from Bristol-Myers Squibb; and advisory board/consultancy fees from Bristol-Myers Squibb, Foresite Labs, and Pfizer. Dr Calkins is a consultant for Medtronic Inc, Biosense Webster, Pfizer, StrideBio, Rocket, and Abbott. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (© 2024 The Authors.)

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiac disease that leads to ventricular tachycardia (VT), a life-threatening heart rhythm disorder. Treating ARVC remains challenging due to the complex underlying arrhythmogenic mechanisms, which involve structural and electrophysiological (EP) remodeling. Here, we developed a novel genotype-specific heart digital twin (Geno-DT) approach to investigate the role of pathophysiological remodeling in sustaining VT reentrant circuits and to predict the VT circuits in ARVC patients of different genotypes. This approach integrates the patient's disease-induced structural remodeling reconstructed from contrast-enhanced magnetic-resonance imaging and genotype-specific cellular EP properties. In our retrospective study of 16 ARVC patients with two genotypes: plakophilin-2 ( PKP2 , n = 8) and gene-elusive (GE, n = 8), we found that Geno-DT accurately and non-invasively predicted the VT circuit locations for both genotypes (with 100%, 94%, 96% sensitivity, specificity, and accuracy for GE patient group, and 86%, 90%, 89% sensitivity, specificity, and accuracy for PKP2 patient group), when compared to VT circuit locations identified during clinical EP studies. Moreover, our results revealed that the underlying VT mechanisms differ among ARVC genotypes. We determined that in GE patients, fibrotic remodeling is the primary contributor to VT circuits, while in PKP2 patients, slowed conduction velocity and altered restitution properties of cardiac tissue, in addition to the structural substrate, are directly responsible for the formation of VT circuits. Our novel Geno-DT approach has the potential to augment therapeutic precision in the clinical setting and lead to more personalized treatment strategies in ARVC., Competing Interests: YZ, KZ, AP, CJ, SZ, RC, ES, AG, CT, BM, HC, NT No competing interests declared, (© 2023, Zhang et al.)

Background: We sought to determine regional myofiber stress after Coapsys device (Myocor, Inc, Maple Grove, MN) implantation using a finite element model of the left ventricle (LV). Chronic ischemic mitral regurgitation is caused by LV remodeling after posterolateral myocardial infarction. The Coapsys device consists of a single trans-LV chord placed below the mitral valve such that when tensioned it alters LV shape and decreases chronic ischemic mitral regurgitation., Methods: Finite element models of the LV were based on magnetic resonance images obtained before (preoperatively) and after (postoperatively) coronary artery bypass grafting with Coapsys implantation in a single patient. To determine the effect of Coapsys and LV before stress, virtual Coapsys was performed on the preoperative model. Diastolic and systolic material variables in the preoperative, postoperative, and virtual Coapsys models were adjusted so that model LV volume agreed with magnetic resonance imaging data. Chronic ischemic mitral regurgitation was abolished in the postoperative models. In each case, myofiber stress and pump function were calculated., Results: Both postoperative and virtual Coapsys models shifted end-systolic and end-diastolic pressure-volume relationships to the left. As a consequence and because chronic ischemic mitral regurgitation was reduced after Coapsys, pump function was unchanged. Coapsys decreased myofiber stress at end-diastole and end-systole in both the remote and infarct regions of the myocardium. However, knowledge of Coapsys and LV prestress was necessary for accurate calculation of LV myofiber stress, especially in the remote zone., Conclusions: Coapsys decreases myofiber stress at end-diastole and end-systole. The improvement in myofiber stress may contribute to the long-term effect of Coapsys on LV remodeling., (Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Context: A precise role for the innate immune system in psoriasis remains to be determined. Surface receptors, including Toll-like receptors (TLRs) that recognize bacterial ligands and CD91, which recognizes heat shock proteins (HSPs), are implicated in both innate and adaptive immunity., Objective: Since skin is exposed to various exogenous stimuli, which can provoke or exacerbate psoriasis, we characterized expression and function of TLRs, CD91, and HSPs in normal and psoriatic skin., Design: A variety of skin-derived cells and blood-derived cells were analyzed both in vivo and in vitro; samples were obtained from 24 different individuals for innate immune-related receptor expression and function. By comparing and contrasting individuals with healthy skin and psoriatic patients, several specific differences were identified., Results: Immunohistochemistry-based expression profiling revealed TLR1 expression in epidermal dendritic cells (DCs) and dermal dendritic cells (DDCs) in normal skin, as well as in pre-psoriatic skin and psoriatic plaques, with enhanced basal layer keratinocyte (KC) expression in pre-psoriatic and psoriatic plaques compared with normal skin; TLR2 expression primarily by DDCs; and TLR4 expression by epidermal DCs and DDCs, with mid-epidermal-layer KCs displaying cell surface staining. No TLR9 or CD14 was detected on DCs or KCs, although psoriatic plaques contained CD14-positive macrophages. Analysis of psoriatic epidermis revealed HSPs 27, 60, and 70. Keratinocytes were CD91 negative, but CD91 was expressed by fibroblasts and DDCs in normal and pre-psoriatic skin, with prominent accumulation of CD91-positive DDCs in psoriatic plaques. Cultured KCs revealed no surface expression of TLR2, TLR4, TLR9, or CD91. Exposure of fibroblasts, but not KCs, to lipopolysaccharide or HSPs triggered nuclear factor (NF)-kappaB activation. Heat shock proteins did induce maturation of blood-derived DCs accompanied by increased interleukin-12 production and enhanced antigen-presenting function., Conclusions: These data demonstrate distinctive patterns of innate immune-related receptors by specific subsets of cells in normal and psoriatic skin, suggesting functional roles for HSPs and DCs in psoriasis.

A cDNA encoding a human ortholog of mouse DNA helicase B, which may play a role in DNA replication, has been cloned and expressed as a recombinant protein. The predicted human DNA helicase B (HDHB) protein contains conserved helicase motifs (superfamily 1) that are strikingly similar to those of bacterial recD and T4 dda proteins. The HDHB gene is expressed at low levels in liver, spleen, kidney, and brain and at higher levels in testis and thymus. Purified recombinant HDHB hydrolyzed ATP and dATP in the presence of single-stranded DNA, displayed robust 5'-3' DNA helicase activity, and interacted physically and functionally with DNA polymerase alpha-primase. HDHB proteins with mutations in the Walker A or B motif lacked ATPase and helicase activity but retained the ability to interact with DNA polymerase alpha-primase, suggesting that the mutants might be dominant over endogenous HDHB in human cells. When purified HDHB protein was microinjected into the nucleus of cells in early G(1), the mutant proteins inhibited DNA synthesis, whereas the wild type protein had no effect. Injection of wild type or mutant protein into cells at G(1)/S did not prevent DNA synthesis. The results suggest that HDHB function is required for S phase entry.

With the recent introduction of neuraminidase (NA) inhibitors into clinical practice for the treatment of influenza virus infections, considerable attention has been focused on the potential for resistance development and cross-resistance between different agents from this class. A-315675 is a novel influenza virus NA inhibitor that has potent enzyme activity and is highly active in cell culture against a variety of strains of influenza A and B viruses. To further assess the therapeutic potential of this compound, in vitro resistance studies have been conducted and a comparative assessment has been made relative to oseltamivir carboxylate. The development of viral resistance to A-315675 was studied by in vitro serial passage of influenza A/N9 virus strains grown in MDCK cells in the presence of increasing concentrations of A-315675. Parallel passaging experiments were conducted with oseltamivir carboxylate, the active form of a currently marketed oral agent for the treatment of influenza virus infections. Passage experiments with A-315675 identified a variant at passage 8 that was 60-fold less susceptible to the compound. Sequencing of the viral population identified an E119D mutation in the NA gene, but no mutations were observed in the hemagglutinin (HA) gene. However, by passage 10 (2.56 microM A-315675), two mutations (R233K, S339P) in the HA gene appeared in addition to the E119D mutation in the NA gene, resulting in a 310-fold-lower susceptibility to A-315675. Further passaging at higher drug concentrations had no effect on the generation of further NA or HA mutations (20.5 microM A-315675). This P15 virus displayed 355-fold-lower susceptibility to A-315675 and >175-fold-lower susceptibility to zanamivir than did wild-type virus, but it retained a high degree of susceptibility to oseltamivir carboxylate. By comparison, virus variants recovered from passaging against oseltamivir carboxylate (passage 14) harbored an E119V mutation and displayed a 6,000-fold-lower susceptibility to oseltamivir carboxylate and a 175-fold-lower susceptibility to zanamivir than did wild-type virus. Interestingly, this mutant still retained susceptibility to A-315675 (42-fold loss). This suggests that cross-resistance between A-315675- and oseltamivir carboxylate-selected variants in vitro is minimal.

A-315675 is a novel, pyrrolidine-based compound that was evaluated in this study for its ability to inhibit A and B strain influenza virus neuraminidases in enzyme assays and influenza virus replication in cell culture. A-315675 effectively inhibited influenza A N1, N2, and N9 and B strain neuraminidases with inhibitor constant (K(i)) values between 0.024 and 0.31 nM. These values were comparable to or lower than the K(i) values measured for oseltamivir carboxylate (GS4071), zanamivir, and BCX-1812, except for the N1 enzymes that were found to be the most sensitive to BCX-1812. The time-dependent inhibition of neuraminidase catalytic activity observed with A-315675 is likely due to its very low rate of dissociation from the active site of neuraminidase. The half times for dissociation of A-315675 from B/Memphis/3/89 and A/Tokyo/3/67 (H3N2) influenza virus neuraminidases of 10 to 12 h are significantly slower than the half times measured for oseltamivir carboxylate (33 to 60 min). A-315675 inhibited the replication of several laboratory strains of influenza virus in cell culture with potencies that were comparable or superior to those for oseltamivir carboxylate and BCX-1812, except for the A/H1N1 viruses that were found to be two- to fourfold more susceptible to BCX-1812. A-315675 and oseltamivir carboxylate exhibited comparable potencies against a panel of A/H1N1 and A/H3N2 influenza virus clinical isolates, but A-315675 was found to be significantly more potent than oseltamivir carboxylate against the B strain isolates. The favorable in vitro results relative to other clinically effective agents provide strong support for the further investigation of A-315675 as a potential therapy for influenza virus infections.

A 336-amino-acid segment of the GB virus C second envelope protein (E2) has been produced in BHK-21 cells using the Semliki Forest virus vector system. Secretion of this protein was facilitated by deletion of a hydrophobic region at the C-terminus that may represent the membrane anchoring domain. The E2 protein recovered from the culture supernatant exhibited a molecular mass of approximately 52 kDa, with the increase in size relative to the polyprotein backbone being contributed by N-linked glycosylation. A radioimmunoprecipitation assay using GBV-C E2 was developed to test for the presence of antibodies against this protein in human sera. The prevalence of antibodies to E2 was high among injection drug users and other individuals at risk for acquiring parenterally transmitted agents. There was a much higher percentage of anti-E2 seropositivity in GBV-C RT-PCR negative compared to GBV-C RT-PCR positive samples from these populations. In addition, serial samples from patients transfused with blood containing GBV-C showed seroconversion to anti-E2 positivity and loss of GBV-C viremia as measured by RT-PCR within 11 months of transfusion in five of seven individuals. Thus, this system provided a rapid means to identify GBV-C E2 as a useful antigen for the study of GBV-C exposure.