Vigorous Exercise in Patients With Hypertrophic Cardiomyopathy.

Importance: Whether vigorous intensity exercise is associated with an increase in risk of ventricular arrhythmias in individuals with hypertrophic cardiomyopathy (HCM) is unknown. Objective: To determine whether engagement in vigorous exercise is associated with increased risk for ventricular arrhythmias and/or mortality in individuals with HCM. The a priori hypothesis was that participants engaging in vigorous activity were not more likely to have an arrhythmic event or die than those who reported nonvigorous activity. Design, Setting, and Participants: This was an investigator-initiated, prospective cohort study. Participants were enrolled from May 18, 2015, to April 25, 2019, with completion in February 28, 2022. Participants were categorized according to self-reported levels of physical activity: sedentary, moderate, or vigorous-intensity exercise. This was a multicenter, observational registry with recruitment at 42 high-volume HCM centers in the US and internationally; patients could also self-enroll through the central site. Individuals aged 8 to 60 years diagnosed with HCM or genotype positive without left ventricular hypertrophy (phenotype negative) without conditions precluding exercise were enrolled. Exposures: Amount and intensity of physical activity. Main Outcomes and Measures: The primary prespecified composite end point included death, resuscitated sudden cardiac arrest, arrhythmic syncope, and appropriate shock from an implantable cardioverter defibrillator. All outcome events were adjudicated by an events committee blinded to the patient's exercise category. Results: Among the 1660 total participants (mean [SD] age, 39 [15] years; 996 male [60%]), 252 (15%) were classified as sedentary, and 709 (43%) participated in moderate exercise. Among the 699 individuals (42%) who participated in vigorous-intensity exercise, 259 (37%) participated competitively. A total of 77 individuals (4.6%) reached the composite end point. These individuals included 44 (4.6%) of those classified as nonvigorous and 33 (4.7%) of those classified as vigorous, with corresponding rates of 15.3 and 15.9 per 1000 person-years, respectively. In multivariate Cox regression analysis of the primary composite end point, individuals engaging in vigorous exercise did not experience a higher rate of events compared with the nonvigorous group with an adjusted hazard ratio of 1.01. The upper 95% 1-sided confidence level was 1.48, which was below the prespecified boundary of 1.5 for noninferiority. Conclusions and Relevance: Results of this cohort study suggest that among individuals with HCM or those who are genotype positive/phenotype negative and are treated in experienced centers, those exercising vigorously did not experience a higher rate of death or life-threatening arrhythmias than those exercising moderately or those who were sedentary. These data may inform discussion between the patient and their expert clinician around exercise participation.

Impact and effectiveness of a mandatory competency-based simulation program for pediatric emergency medicine faculty.

Introduction: Pediatric emergency medicine physicians struggle to maintain their critical procedural and resuscitation skills. Continuing professional development programs incorporating simulation and competency-based standards may help ensure skill maintenance. Using a logic model framework, we sought to evaluate the effectiveness of a mandatory annual competency-based medical education (CBME) simulation program. Methods: The CBME program, evaluated from 2016 to 2018, targeted procedural, point-of-care ultrasound (POCUS) and resuscitation skills. Delivery of educational content included a flipped-classroom website, deliberate practice, mastery-based learning, and stop-pause debriefing. Participants' competence was assessed using a 5-point global rating scale (GRS; 3 = competent, 5 = mastery). Statistical process control charts were used to measure the effect of the CBME program on team performance during in situ simulations (ISS), measured using the Team Emergency Assessment Measure (TEAM) scale. Faculty completed an online program evaluation survey. Results: Forty physicians and 48 registered nurses completed at least one course over 3 years (physician mean ± SD 2.2 ± 0.92). Physicians achieved competence on 430 of 442 stations (97.3%). Mean ± SD GRS scores for procedural, POCUS, and resuscitation stations were 4.34 ± 0.43, 3.96 ± 0.35, and 4.17 ± 0.27, respectively. ISS TEAM scores for "followed standards and guidelines" improved significantly. No signals of special cause variation emerged for the other 11 TEAM items, indicating skills maintenance. Physicians rated CBME training as highly valuable (mean question scores 4.15-4.85/5). Time commitment and scheduling were identified as barriers to participation. Conclusions: Our mandatory simulation-based CBME program had high completion rates and very low station failures. The program was highly rated and faculty improved or maintained their ISS performance across TEAM scale domains.

Contingency Management and Pre-Exposure Prophylaxis Adherence Support Services (CoMPASS): A hybrid type 1 effectiveness-implementation study to promote HIV risk reduction among people who inject drugs.

BACKGROUND: HIV disproportionally affects persons who inject drugs (PWID), but engagement with HIV pre-exposure prophylaxis (PrEP) is low. We describe the rationale and study design for a new study, "Contingency Management and Pre-Exposure Prophylaxis (PrEP) Adherence Support Services (CoMPASS)," a hybrid type 1 effectiveness-implementation trial to promote HIV risk reduction among PWID. METHODS: In four community-based programs in the northeastern United States, PrEP-eligible PWID (target n = 526) are randomized to treatment as usual or Contingency Management (CM) and, as indicated, stepped up to PrEP Adherence Support Services (CoMPASS) over 24 weeks. During CM sessions, participants receive timely tangible rewards for verifiable activities demonstrating 1) PrEP initiation and adherence, and 2) engagement with medications for opioid use disorder (MOUD) and other OUD-related care. Participants who do not have high levels of biomarker-confirmed PrEP adherence at week 12 will be stepped up to receive PrEP Adherence Support Services (PASS) consisting of strengths-based case management over 12 weeks. Interventions are delivered by trained PrEP navigators, staff embedded within the respective sites. The primary outcome is sustained PrEP adherence by dried blood spot testing at 24 weeks. To inform future implementation, we are conducting implementation-focused process evaluations throughout the clinical trial. CONCLUSIONS: Results from this protocol are anticipated to yield novel findings regarding the impact and scalability of CoMPASS to promote HIV prevention among PWID in partnership with community-based organizations. http://ClinicalTrials.gov identifier: NCT04738825.

Aligning payer and provider strategies with the latest evidence to optimize clinical outcomes for patients with neuromyelitis optica spectrum disorder.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder affecting the central nervous system that is associated with significant morbidity and mortality. Early diagnosis and treatment are essential to minimize long-term disability. Recent advances in the understanding of the pathophysiology of NMOSD have led to multiple new therapies, but significant care and knowledge gaps persist. OBJECTIVES: To summarize current knowledge about the burden of disease and diagnosis and treatment of NMOSD in order to support managed care professionals and health care providers in making collaborative, evidence-based decisions to optimize outcomes among patients with NMOSD. In addition, this review also presents findings of a patient survey that provides insight into real-world experiences of those living with NMOSD. SUMMARY: Diagnosis of NMOSD is based on detection of immunoglobulin G antibodies to the water channel protein aquaporin-4 (AQP4-IgG) in the context of compatible clinical and magnetic resonance imaging features. Patients who are AQP4-IgG seronegative and/or who are positive for myelin oligodendrocyte glycoprotein antibodies may also satisfy criteria for NMOSD. The rarity of the condition combined with the significant overlap in clinical features with other autoimmune diseases affecting the central nervous system, most notably multiple sclerosis, can delay accurate diagnosis, which in turn can delay appropriate treatment, leading to the accumulation of long-term disability. Accumulating disability associated with NMOSD has a substantial negative impact on quality of life. The disease typically evolves as relapsing (ie, repeated) acute attacks. Treatment consists of management of acute attacks, prevention of subsequent attacks, and management of acute and chronic symptoms. The armamentarium of therapies to prevent attacks consists of several monoclonal antibodies (mAbs) approved to treat AQP4-IgG-seropositive disease and several off-label therapies used for patients with either seropositive or seronegative disease. There is limited evidence to guide treatment decision-making, including which therapies to use first line, when to switch, and when to use monotherapy vs combination therapy. In addition, therapies with the greatest demonstrated safety and efficacy in NMOSD are costly and may not be accessible to all patients. Moreover, the results of the patient survey revealed significant clinical and financial burdens to patients with NMOSD including frequent attacks, delays in therapy initiation, need for urgent care and repeat hospitalizations, new and worsening symptoms, accumulating disability, and difficulties affording care. As such, key stakeholders must weigh them against the substantial economic costs of untreated or suboptimal treatment of disease. DISCLOSURES: Dr Wingerchuk has served on the advisory board or panel for Alexion, Biogen, Genentech, Horizon, Mitsubishi Tanabe, Novartis, Roche, UCB, and Viela Bio and has received grants of research support from Alexion. Dr Weinshenker has served as a consultant or on the advisory board or panel for Alexion, Genentech, Horizon, Mitsubishi Tanabe, Roche, UCB, and Viela Bio, served on the speakers bureau or other promotional education for Genentech and Roche, and has received royalties from RSR Ltd.

AQP4-dependent glioma cell features affect the phenotype of surrounding cells via extracellular vesicles.

BACKGROUND: Extracellular vesicles (EVs) are membrane-enclosed particles released systemically by all cells, including tumours. Tumour EVs have been shown to manipulate their local environments as well as distal targets to sustain the tumour in a variety of tumours, including glioblastoma (GBM). We have previously demonstrated the dual role of the glial water channel aquaporin-4 (AQP4) protein in glioma progression or suppression depending on its aggregation state. However, its possible role in communication mechanisms in the microenvironment of malignant gliomas remains to be unveiled. RESULTS: Here we show that in GBM cells AQP4 is released via EVs that are able to affect the GBM microenvironment. To explore this role, EVs derived from invasive GBM cells expressing AQP4-tetramers or apoptotic GBM cells expressing orthogonal arrays of particles (AQP4-OAPs) were isolated, using a differential ultracentrifugation method, and were added to pre-seeded GBM cells. Confocal microscopy analysis was used to visualize the interaction and uptake of AQP4-containing EVs by recipient cells. Chemoinvasion and Caspase3/7 activation assay, performed on recipient cells after EVs uptake, revealed that EVs produced by AQP4-tetramers expressing cells were able to drive surrounding tumour cells toward the migratory phenotype, whereas EVs produced by AQP4-OAPs expressing cells drive them toward the apoptosis pathway. CONCLUSION: This study demonstrates that the different GBM cell phenotypes can be transferred by AQP4-containing EVs able to influence tumour cell fate toward invasiveness or apoptosis. This study opens a new perspective on the role of AQP4 in the brain tumour microenvironment associated with the EV-dependent communication mechanism.

Role of pericytes in blood-brain barrier preservation during ischemia through tunneling nanotubes.

Crosstalk mechanisms between pericytes, endothelial cells, and astrocytes preserve integrity and function of the blood-brain-barrier (BBB) under physiological conditions. Long intercellular channels allowing the transfer of small molecules and organelles between distant cells called tunneling nanotubes (TNT) represent a potential substrate for energy and matter exchanges between the tripartite cellular compartments of the BBB. However, the role of TNT across BBB cells under physiological conditions and in the course of BBB dysfunction is unknown. In this work, we analyzed the TNT's role in the functional dialog between human brain endothelial cells, and brain pericytes co-cultured with human astrocytes under normal conditions or after exposure to ischemia/reperfusion, a condition in which BBB breakdown occurs, and pericytes participate in the BBB repair. Using live time-lapse fluorescence microscopy and laser-scanning confocal microscopy, we found that astrocytes form long TNT with pericytes and endothelial cells and receive functional mitochondria from both cell types through this mechanism. The mitochondrial transfer also occurred in multicellular assembloids of human BBB that reproduce the three-dimensional architecture of the BBB. Under conditions of ischemia/reperfusion, TNT formation is upregulated, and astrocytes exposed to oxygen-glucose deprivation were rescued from apoptosis by healthy pericytes through TNT-mediated transfer of functional mitochondria, an effect that was virtually abolished in the presence of TNT-destroying drugs. The results establish a functional role of TNT in the crosstalk between BBB cells and demonstrate that TNT-mediated mitochondrial transfer from pericytes rescues astrocytes from ischemia/reperfusion-induced apoptosis. Our data confirm that the pericytes might play a pivotal role in preserving the structural and functional integrity of BBB under physiological conditions and participate in BBB repair in brain diseases.

A Quality Improvement Initiative Is Associated With Reduced Time to Administer Biologics and Small Molecules and Emergency Room Visits in Inflammatory Bowel Disease.

BACKGROUND: Delays in biologic or small molecule medication administration are associated with increased adverse events, hospitalization, and surgery in inflammatory bowel disease (IBD). We evaluated the impact of a quality improvement (QI) intervention on the time to administration of biologics or small molecules (TABS) in IBD. METHODS: Data were retrospectively extracted for IBD patients prescribed biologics or small molecules from a convenience sample of providers participating in an accredited QI educational intervention (baseline cohort). Subsequent to the intervention, data were prospectively collected from patients prescribed these medications (postintervention cohort). Dates related to steps between a treatment decision to medication administration were collected. The primary outcome compared TABS in baseline and postintervention cohorts. RESULTS: Eighteen physicians provided survey and patient data for 200 patients in each cohort (n=400). The median time to medication administration (TABS) decreased from baseline to postintervention cohorts (30 vs. 26 d, P=0.04). Emergency room visits before medication administration also decreased (25.5% vs. 12.5%, P=0.001). Similar numerical TABS reductions were observed in subgroups limited to physicians providing patients to both cohorts and for individual medications prescribed. Primary contributors to delays included filling prescriptions subsequent to insurance approval and dispensation subsequent to this. CONCLUSIONS: A QI intervention successfully reduced medication administration times (TABS) by accelerating provider-dependent steps. This intervention was associated with reduced emergency room visits. We propose TABS as a quality metric to assess the effective delivery of therapies in IBD. Further evaluation of QI interventions, patient education on prescription drug insurance, and quality metrics are warranted.

Overcoming barriers to biosimilar adoption: real-world perspectives from a national payer and provider initiative.

In response to a published national payer survey indicating striking needs for multistakeholder initiatives to increase biosimilar adoption, a focus workgroup meeting joining payers and providers was conducted in December 2019 in Boston, MA. Before the focus group meeting, a survey was sent to health care providers to collect perceptions about barriers to biosimilar adoption and gather input on best potential strategies for addressing these barriers. The focus group panel consisted of 5 managed care pharmacists and 3 physician experts in rheumatology, dermatology, and gastroenterology, representing large managed care organizations and health care systems in the Boston area. A clinical moderator facilitated discussions between the payers and providers regarding challenges to biosimilar adoption and potential collaborative strategies to overcome these barriers. The focus group participants identified hurdles to biosimilar adoption in 3 major areas: (1) the lack of confidence in biosimilar interchangeability and a need for education about biosimilars, (2) the lack of financial incentives to switch to biosimilars from the reference biologic product, and (3) administrative burdens that impair the prescription of biologics. Learning from their mutual experiences, the focus group participants formulated action plans to address these barriers. The top strategies recommended by the participants included advancing biosimilar education, facilitating administrative processes related to biosimilar prescriptions, and increasing provider reimbursement while reducing cost sharing to patients receiving biosimilars. DISCLOSURES: The study reported on in this article was part of a continuing education program funded by an independent educational grant that was awarded by Sandoz Inc., a Novartis Division, to PRIME Education, LLC. The grantor had no role in the study design, execution, analysis, or reporting. The Academy of Managed Care Pharmacy (AMCP) received grant funding from PRIME to assist with participant recruitment and content review for the continuing education program. Bandekar, Cheifetz, Edgar, Helfgott, Hoye-Simek, Liu, and Smith received an honorarium from PRIME for serving as faculty for the continuing education program. Cheifetz has received research grants from Inform Diagnostics and consulting fees from AbbVie, Bacainn, BMS, Grifols, Janssen, Pfizer, Prometheus, Samsung, and Takeda unrelated to this work. Smith has received consulting fees from Boehringer-Ingelheim, has served as an investigator on industry-initiated trials for AbbVie and Pfizer, and has served as an investigator on investigator-initiated trials for Novartis and Regeneron. Carter, Fajardo, and Simone have nothing to disclose.

Development and implementation of a novel, mandatory competency-based medical education simulation program for pediatric emergency medicine faculty.

BACKGROUND: Maintaining acute care physician competence is critically important. Current maintenance of certification (MOC) programs has started to incorporate simulation-based education (SBE). However, competency expectations have not been defined. This article describes the development of a mandatory annual SBE, competency-based simulation program for technical and resuscitation skills for pediatric emergency medicine (PEM) physicians. METHODS: The competency-based medical education (CBME) program was introduced in 2016. Procedural skill requirements were based on a needs assessment derived from Royal College PEM training guidelines. Resuscitation scenarios were modified versions of pre-existing in-situ mock codes or critical incident cases. All full-time faculty were required to participate annually in both sessions. Delivery of educational content included a flipped classroom website, deliberate practice, and stop-pause debriefing. All stations required competency checklists and global rating scales. RESULTS: Between 2016 and 2018, 40 physicians and 48 registered nurses attended these courses. Overall course evaluations in 2018 were 4.92/5 and 4.93/5. Barriers to implementation include the need for many simulation education experts, time commitment, and clinical scheduling during course events. CONCLUSION: We have developed a mandatory simulation-based, technical, and resuscitation CBME program for PEM faculty. This simulation-based CBME program could be adapted to other acute care disciplines. Further research is required to determine if these skills are enhanced both in a simulated and real environment and if there is an impact on patient outcomes.

Regulation of aquaporin-4 expression in the central nervous system investigated using M23-AQP4 null mouse.

In astrocytes, unknown mechanisms regulate the expression of M1 and M23 isoforms of water channel aquaporin-4 (M1-AQP4 and M23-AQP4). The ratio between these two isoforms controls the AQP4 assembly state in the plasma membrane known as orthogonal arrays of particles (OAPs). To give new insights into these mechanisms, here, we explore the regulation of AQP4 expression in the spinal cord of a CRISPR/Cas9 M23-null mouse model (M23-null). In the M23-null spinal cord OAP assembly, the perivascular localization of AQP4 and M1-AQP4 protein were drastically reduced. In heterozygous, M1-AQP4 was proportionally reduced with M23-AQP4, maintaining the isoform ratio unaffected. We hypothesize a role of the M23-AQP4 in the regulation of M1-AQP4 expression. M1-AQP4 transcription, splicing and M1-AQP4 protein degradation were found to be unaffected in M23-null spinal cord and in M23-null astrocyte primary culture. The translational control was investigated by mRNA-protein pull down and quantitative mass spectrometry, to isolate and quantify AQP4 mRNA binding proteins (AQP4-RBPs). Compared to WT, in M23-null spinal cord, the interaction between AQP4 mRNA and polypyrimidine tract binding protein 1, a positive regulator of AQP4 translation, was higher, while interaction with the RNA helicase DDX17 was lower. In astrocyte primary cultures, DDX17 knockdown upregulated AQP4 protein expression and increased cell swelling, leaving AQP4 mRNA levels unchanged. Here, we identify AQP4-RBPs and provide evidence that in mouse spinal cord M23-AQP4 deletion changes the interaction between AQP4 mRNA and some RBPs involved in AQP4 translation. We describe for the first time the RNA helicase DDX17 as a regulator of AQP4 expression in astrocytes.

Does Evaluation and Management of COPD Follow Therapeutic Strategy Recommendations?

INTRODUCTION: Recommendations for chronic obstructive pulmonary disease (COPD) diagnosis and management requires symptom and exacerbation risk assessment. Adherence to these recommendations appears to be limited. We examined the impact of a COPD quality improvement (QI) program in the Southeastern United States. METHODS: From 2017 to 2018, nine pulmonary and 15 primary care physicians were included in our study and asked to identify 6 to 7 of their COPD patients using maintenance COPD medications with at least 2 office visits in the past year. A separate group of COPD patients (n=135 pulmonary and 165 primary care) from the same practices were evaluated. Physicians underwent focused, educational, peer-to-peer small group webinars. Data were collected from physicians and their patients using a systematic survey. Chart audits occurred at baseline and 6 months after the webinars. RESULTS: The majority of physicians (67%) saw ≥ 20 COPD patients/week. There were important discrepancies between the care clinicians thought they provided, and the care recalled by their patients. Clinicians felt that 33% of their patients experienced at least 2 exacerbations in the past year; 56% of their patients reported this frequency. There was discrepancy in the clinicians' interpretations and the patients' reasons for discontinuing their medications and in the use of referrals. Self-reported changes were noted by clinicians after educational webinars and improvements in patient care were noted in the year following intervention. CONCLUSION: We identified notable discrepancies between the clinicians' impression of care provided and the components actually recalled by their patients. We also identified improvements in processes of care and outcomes following an educational intervention based on the principles of audit and feedback.

AQP4 Aggregation State Is a Determinant for Glioma Cell Fate.

The glial water channel protein aquaporin-4 (AQP4) forms heterotetramers in the plasma membrane made of the M23-AQP4 and M1-AQP4 isoforms. The isoform ratio controls AQP4 aggregation into supramolecular structures called orthogonal arrays of particles (AQP4-OAP). The role of AQP4 aggregation into OAP in malignant gliomas is still unclear. In this study, we demonstrate that AQP4 aggregation/disaggregation into OAP influences the biology of glioma cells. Selective expression of the OAP-forming isoform M23-AQP4 (AQP4-OAP) triggered cell shape changes in glioma cells associated with alterations to the F-actin cytoskeleton that affected apoptosis. By contrast, expression of M1-AQP4 (AQP4-tetramers), which is unable to aggregate into OAP, ameliorated glioma cell invasiveness, improved cell migration, and increased methalloproteinase-9 activity. Two prolines (254 and 296) at the C-terminus tail were shown to be important in mediating the relationship between the actin cytoskeleton and AQP4-OAP and AQP4-tetramers. In conclusion, this study demonstrates that AQP4 aggregation state might be an important determinant in orienting glioma cells to persist or perish. AQP4 disaggregation may potentiate invasiveness potential, whereas AQP4 aggregation may activate the apoptotic path. This study shows a new perspective on the role of AQP4 in brain tumors not necessarily associated with edema formation but with AQP4 aggregation/disaggregation dynamics and their link with the actin cytoskeleton. SIGNIFICANCE: This study demonstrates how AQP4 aggregation influences plasma membrane dynamics to alter cell proliferation, invasiveness, migration, and apoptotic potential in glioma cells.

Canadian and UK/Ireland practice patterns in lumbar puncture performance in febrile neonates with bronchiolitis.

BACKGROUND: Serious bacterial infections in young infants with bronchiolitis are rare. Febrile infants <1 month old with bronchiolitis often receive a lumbar puncture (LP), despite limited data for this practice and lack of clinical practice guidelines for this population. The primary objective was to investigate practice patterns in performance of LPs in the ED management of febrile infants aged ≤30 days with bronchiolitis. METHODS: A cross-sectional survey of two national paediatric emergency research networks (PediatricEmergency Research Canada (PERC) and the PediatricEmergency Research UK/Ireland (PERUKI)) was conducted January to November 2017 using a modified Dillman technique. The survey was preceded by a clinical vignette describing a well appearing, 21-day-old infant with low-grade fever, respiratory findings typical of bronchiolitis and no perinatal serious bacterial infection (SBI) risk features. RESULTS: The response rate from PERC was 169/250 (68%) and 172/201 (86%) from PERUKI. Nine physicians in training were excluded, leaving 332 eligible participants. Although most physicians believe that neonates with bronchiolitis rarely have meningitis (PERC 141/161 (87.6%); PERUKI 154/171 (90%)) and feel comfortable diagnosing bronchiolitis in this group (PERC 136/161 (84.5%); PERUKI 143/171 (83.6%)), there was significant variation in the proportion who would be likely/very likely to perform an LP (PERC 100/161 (62.1%); PERUKI 15/171 (8.8%)) (p<0.0001). Practice in Canada, <10 years in practice and lack of comfort with diagnosing bronchiolitis represent multivariable predictors of LP; OR 23.7 (95% CI 11.7 to 47.9), 2.3 (95% CI 1.2 to 4.2) and 2.5 (95% CI 1.1 to 5.0), respectively. Rapid knowledge of respiratory syncytial virus positivity would decrease LP probability from 35.4% to 20.2%. CONCLUSION: Estimated probability of performing LPs and other interventions in otherwise healthy febrile neonates with bronchiolitis is highly variable between emergency physicians in Canada and the UK/Ireland. Network, <10 years in ED practice and comfort level with diagnosing bronchiolitis in newborns constitute independent predictors of the likelihood of LP performance.

Host-Cell Type Dependent Features of Recombinant Human Aquaporin-4 Orthogonal Arrays of Particles-New Insights for Structural and Functional Studies.

The CNS plasma-membrane water channel aquaporin-4 (AQP4) is expressed as two major isoforms able to aggregate into supramolecular assemblies known as 'orthogonal arrays of particles' (OAPs). OAP subnanometric features are largely unknown mainly because a method for the expression, isolation, and crystallization of integral human OAPs has not been developed. Here, the human OAP-forming isoform M23-AQP4 was expressed in insect and mammalian cell lines and AQP4 and OAP features evaluated. Native size exclusion chromatography was employed to isolate and analyze authentically folded OAPs, and neuromyelitis optica (NMO)-specific sandwich ELISA was developed to test OAP-integrity. The results demonstrate that in insect cells most AQP4 remains intracellular and unfolded and that OAPs are largely disassembled after the detergent extraction step. In mammalian cells, AQP4 showed regular plasma membrane targeting and OAPs exhibited strong post-extraction stability. Starting from the mammalian cell expression system, we isolated authentically folded OAPs. Together these data suggest a new strategy for expressing and isolating integral recombinant human OAPs and providing new insights into the cell-type dependent OAP-assembly and post-extraction stability, potentially useful to design new approaches for structural and functional studies of OAP and for other plasma membrane proteins organized into supramolecular structures.

Competitive athletes with implantable cardioverter-defibrillators-How to program? Data from the Implantable Cardioverter-Defibrillator Sports Registry.

BACKGROUND: Athletes with an implantable cardioverter-defibrillator (ICD) may require unique optimal device-based tachycardia programming. OBJECTIVE: The purpose of this study was to assess the association of tachycardia programming characteristics of ICDs with occurrence of shocks, transient loss-of-consciousness, and death among athletes. METHODS: A subanalysis of a prospective, observational, international registry of 440 athletes with ICDs followed for a median of 44 months was performed. Programming characteristics were divided into groups for rate cutoff (very high, high, or low) and detection (long-detection interval [>nominal] or nominal). Endpoints included total, appropriate, and inappropriate shocks, transient loss-of-consciousness, and mortality. RESULTS: In this cohort, 62% were programmed with high-rate cutoff and 30% with long detection. No athlete died of an arrhythmia (related or unrelated) to ICD shocks. Three patients had sustained ventricular tachycardia below programmed detection rate, presenting as palpations and/or dizziness. ICD shocks were received by 98 athletes (64 appropriate, 32 inappropriate); 2 patients received both. Programming a high-rate cutoff was associated with decreased risk of total (P = .01) and inappropriate (P = .04) shocks overall and during competition or practice. Programming long-detection intervals was associated with fewer total shocks. Single- vs dual-chamber devices and the number of zones were unrelated to risk of shock. Transient loss-of-consciousness, associated with 27 appropriate shocks, was not related to programming characteristics. CONCLUSION: High-rate cutoff and long-detection duration programming of ICDs in athletes at risk for sudden death can reduce total and inappropriate ICD shocks without affecting survival or the incidence of transient loss-of-consciousness.

Safety of Sports for Young Patients With Implantable Cardioverter-Defibrillators: Long-Term Results of the Multinational ICD Sports Registry.

BACKGROUND: Despite safety concerns, many young patients with implantable cardioverter-defibrillators (ICDs) participate in sports. We undertook a prospective, multinational registry to determine the incidence of serious adverse events because of sports participation. The primary end points were death or resuscitated arrest during sports or injury during sports because of arrhythmia or shock. Secondary end points included system malfunction and incidence of ventricular arrhythmias requiring multiple shocks for termination. METHODS: Athletes with ICDs aged ≤21 years were included in this post hoc subanalysis of the ICD Sports Registry. Data on sports and clinical outcomes were obtained by phone interview and medical records review. ICD shocks and clinical details of lead malfunction were classified by 2 electrophysiologists. RESULTS: A total of 129 young athletes participating in competitive (n=117) or dangerous (n=12) sports were enrolled. The mean age was 16 years (range, 10-21; 40% female; 92% white). The most common diagnoses were long QT syndrome (n=49), hypertrophic cardiomyopathy (n=30), and congenital heart disease (n=16). The most common sports were basketball and soccer, including 79 varsity/junior varsity high school and college athletes. During a median follow-up of 42 months, 35 athletes (27%) received 38 shocks. There were no occurrences of death, arrest, or injury related to arrhythmia, during sports. There was 1 ventricular tachycardia/ventricular fibrillation storm during competition. Freedom from lead malfunction was 92.3% at 5 years and 79.6% at 10 years. CONCLUSIONS: Although shocks related to competition/practice are not uncommon, there were no serious adverse sequelae. Lead malfunction rates were similar to previously reported in unselected pediatric ICD populations. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00637754.

Aquaporin-1 inhibition reduces metastatic formation in a mouse model of melanoma.

Aquaporin-1 (AQP1) is a proangiogenic water channel protein promoting endothelial cell migration. We previously reported that AQP1 silencing by RNA interference reduces angiogenesis-dependent primary tumour growth in a mouse model of melanoma. In this study, we tested the hypothesis that AQP1 inhibition also affects animal survival and lung nodule formation. Melanoma was induced by injecting B16F10 cells into the back of C57BL6J mice. Intratumoural injection of AQP1 siRNA and CTRL siRNA was performed 10 days after tumour cell implantation. Lung nodule formation was analysed after the death of the mice. Western blot was used to quantify HIF-1α, caspase-3 (CASP3) and metalloproteinase-2 (MMP2) protein levels. We found that AQP1 knock-down (KD) strongly inhibited metastatic lung nodule formation. Moreover, AQP1 siRNA-treated mice showed a twofold survival advantage compared to mice receiving CTRL siRNAs. The reduced AQP1-dependent tumour angiogenesis caused a hypoxic condition, evaluated by HIF-1α significant increase, in turn causing an increased level of apoptosis in AQP1 KD tumours, assessed by CASP3 quantification and DNA fragmentation. Importantly, a decreased level of MMP2 after AQP1 KD indicated a decreased activity against extracellular matrix associated with reduced vascularization and metastatic formation. In conclusion, these findings highlight an additional role for AQP1 as an important determinant of tumour dissemination by facilitating tumour cell extravasation and metastatic formation. This study adds knowledge on the role played by AQP1 in tumour biology and supports the view of AQP1 as a potential drug target for cancer therapy.