Early Initiation of Guideline-Directed Medical Therapy for Heart Failure After Cardiac Surgery.

There is an evolving role for guideline-directed medical therapy (GDMT) in managing heart failure with reduced ejection fraction after cardiac surgery. GDMT is based on the use of pharmacologic agents from each of 4 distinct drug classes, also known as the 4 pillars of heart failure therapy: ß-blockers, renin-angiotensin system inhibitors, often paired with neprilysin inhibitors, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter-2 inhibitors. Despite the demonstrated benefits of GDMT in reducing mortality and hospitalization rates in the nonsurgical literature, there is conspicuous underuse of GDMT after cardiac surgery. The lack of published literature and practical challenges surrounding the timing for initiation of GDMT in the immediate postoperative period has limited standardized implementation strategies. A multidisciplinary approach will be necessary to assist in initiating, titrating, and monitoring the response to these therapies in patients with heart failure with reduced ejection fraction after cardiac surgery.

Combining a prioritization strategy and functional studies nominates 5'UTR variants underlying inherited retinal disease.

BACKGROUND: 5' untranslated regions (5'UTRs) are essential modulators of protein translation. Predicting the impact of 5'UTR variants is challenging and rarely performed in routine diagnostics. Here, we present a combined approach of a comprehensive prioritization strategy and functional assays to evaluate 5'UTR variation in two large cohorts of patients with inherited retinal diseases (IRDs). METHODS: We performed an isoform-level re-analysis of retinal RNA-seq data to identify the protein-coding transcripts of 378 IRD genes with highest expression in retina. We evaluated the coverage of their 5'UTRs by different whole exome sequencing (WES) kits. The selected 5'UTRs were analyzed in whole genome sequencing (WGS) and WES data from IRD sub-cohorts from the 100,000 Genomes Project (n = 2397 WGS) and an in-house database (n = 1682 WES), respectively. Identified variants were annotated for 5'UTR-relevant features and classified into seven categories based on their predicted functional consequence. We developed a variant prioritization strategy by integrating population frequency, specific criteria for each category, and family and phenotypic data. A selection of candidate variants underwent functional validation using diverse approaches. RESULTS: Isoform-level re-quantification of retinal gene expression revealed 76 IRD genes with a non-canonical retina-enriched isoform, of which 20 display a fully distinct 5'UTR compared to that of their canonical isoform. Depending on the probe design, 3-20% of IRD genes have 5'UTRs fully captured by WES. After analyzing these regions in both cohorts, we prioritized 11 (likely) pathogenic variants in 10 genes (ARL3, MERTK, NDP, NMNAT1, NPHP4, PAX6, PRPF31, PRPF4, RDH12, RD3), of which 7 were novel. Functional analyses further supported the pathogenicity of three variants. Mis-splicing was demonstrated for the PRPF31:c.-9+1G>T variant. The MERTK:c.-125G>A variant, overlapping a transcriptional start site, was shown to significantly reduce both luciferase mRNA levels and activity. The RDH12:c.-123C>T variant was found in cis with the hypomorphic RDH12:c.701G>A (p.Arg234His) variant in 11 patients. This 5'UTR variant, predicted to introduce an upstream open reading frame, was shown to result in reduced RDH12 protein but unaltered mRNA levels. CONCLUSIONS: This study demonstrates the importance of 5'UTR variants implicated in IRDs and provides a systematic approach for 5'UTR annotation and validation that is applicable to other inherited diseases.

The Society of Thoracic Surgeons Intermacs 2023 Annual Report: Focus on Magnetically Levitated Devices.

The 14th Annual Report from The Society of Thoracic Surgeons (STS) Interagency Registry for Mechanically Assisted Circulatory Support (Intermacs) describes outcomes of 27,493 patients with a continuous-flow left ventricular assist device (LVAD) from the past decade (2013-2022). In 2022, 2517 primary LVADs were implanted, of which 2512 (99.8%) were fully magnetically levitated (Mag-Lev) devices. This shift to nearly exclusive use of a Mag-Lev device led us to examine its outcomes compared with contemporary (2018-2022) and historical (2013-2017) non-Mag-Lev cohorts. Patients supported by a Mag-Lev device (n = 10,920) had a higher 1- and 5-year survival of 86% (vs 79% and 81%, P < .0001) and 64% (vs 44% and 44%, P < .0001), respectively, than those receiving non-Mag-Lev devices during the contemporary and historical eras. Over 5 years, freedom from gastrointestinal bleeding (72% vs 60%, P < .0001), stroke (87% vs 67%, P < .0001), and device malfunction/pump thrombus (83% vs 54%, P < .0001), but not device-related infection (61% vs 64%, P = .93), was higher with Mag-Lev devices compared with non-Mag-Lev support during the contemporary era. In this large primacy cohort of real-world patients with advanced heart failure, this report underscores marked improvements in short- and intermediate-term survival and reduction of adverse events with a contemporary Mag-Lev LVAD.

Less Invasive Left Ventricular Assist Device Implantation Is Safe and Feasible in Patients With Smaller Body Surface Area.

OBJECTIVE: Smaller body surface area (BSA) frequently precludes patients from left ventricular assist device (LVAD) therapy. We sought to investigate the clinical outcomes in patients with small BSA undergoing less invasive LVAD implantation. METHODS: We conducted a retrospective review of 216 patients implanted with HeartMate 3 LVAD (Abbott, Chicago, IL) via less invasive surgery at our institution. Patients were dichotomized based on their preimplant BSA for comparison between small BSA (≤1.8 m2) and normal/large BSA (>1.8 m2). We analyzed patient perioperative characteristics and outcomes. RESULTS: In our study, small BSA was found in 32 patients (14.8%), while 184 patients (85.2%) had normal/large BSA. Women were more prevalent in the small BSA group (50.0% vs 13.0%, P < 0.001). Preoperative and intraoperative data showed comparable results. Major complications and hospital length of stay did not differ by BSA group. Patients with smaller BSA had significantly decreased pump parameters at discharge, including LVAD flow (4.11 ± 0.49 vs 4.60 ± 0.54 L/min, P < 0.001) and pump speed (5,200 vs 5,400 rpm, P < 0.001). Survival to discharge and within 6 months after implantation were similar between the groups. CONCLUSIONS: Our study results suggest that less invasive HeartMate 3 implantation can be safely performed and demonstrates equivalent outcomes in patients with smaller body habitus. Randomized trials are required to confirm our data.

Fatty acid nitroalkenes - Multi-target agents for the treatment of sickle cell disease.

Sickle cell disease (SCD) is a hereditary hematological disease with high morbidity and mortality rates worldwide. Despite being monogenic, SCD patients display a plethora of disease-associated complications including anemia, oxidative stress, sterile inflammation, vaso-occlusive crisis-related pain, and vasculopathy, all of which contribute to multiorgan dysfunction and failure. Over the past decade, numerous small molecule drugs, biologics, and gene-based interventions have been evaluated; however, only four disease-modifying drug therapies are presently FDA approved. Barriers regarding effectiveness, accessibility, affordability, tolerance, and compliance of the current polypharmacy-based disease-management approaches are challenging. As such, there is an unmet pharmacological need for safer, more efficacious, and logistically accessible treatment options for SCD patients. Herein, we evaluate the potential of small molecule nitroalkenes such as nitro-fatty acid (NO2-FA) as a therapy for SCD. These agents are electrophilic and exert anti-inflammatory and tissue repair effects through an ability to transiently post-translationally bind to and modify transcription factors, pro-inflammatory enzymes and cell signaling mediators. Preclinical and clinical studies affirm safety of the drug class and a murine model of SCD reveals protection against inflammation, fibrosis, and vascular dysfunction. Despite protective cardiac, renal, pulmonary, and central nervous system effects of nitroalkenes, they have not previously been considered as therapy for SCD. We highlight the pathways targeted by this drug class, which can potentially prevent the end-organ damage associated with SCD and contrast their prospective therapeutic benefits for SCD as opposed to current polypharmacy approaches.

Hemin and iron increase synthesis and trigger export of xanthine oxidoreductase from hepatocytes to the circulation.

We recently reported a previously unknown salutary role for xanthine oxidoreductase (XOR) in intravascular heme overload whereby hepatocellular export of XOR to the circulation was identified as a seminal step in affording protection. However, the cellular signaling and export mechanisms underpinning this process were not identified. Here, we present novel data showing hepatocytes upregulate XOR expression/protein abundance and actively release it to the extracellular compartment following exposure to hemopexin-bound hemin, hemin or free iron. For example, murine (AML-12 cells) hepatocytes treated with hemin (10 µM) exported XOR to the medium in the absence of cell death or loss of membrane integrity (2.0 ± 1.0 vs 16 ± 9 µU/mL p < 0.0001). The path of exocytosis was found to be noncanonical as pretreatment of the hepatocytes with Vaculin-1, a lysosomal trafficking inhibitor, and not Brefeldin A inhibited XOR release and promoted intracellular XOR accumulation (84 ± 17 vs 24 ± 8 hemin vs 5 ± 3 control µU/mg). Interestingly, free iron (Fe2+ and Fe3+) induced similar upregulation and release of XOR compared to hemin. Conversely, concomitant treatment with hemin and the classic transition metal chelator DTPA (20 µM) or uric acid completely blocked XOR release (p < 0.01). Our previously published time course showed XOR release from hepatocytes likely required transcriptional upregulation. As such, we determined that both Sp1 and NF-kB were acutely activated by hemin treatment (∼2-fold > controls for both, p < 0.05) and that silencing either or TLR4 with siRNA prevented hemin-induced XOR upregulation (p < 0.01). Finally, to confirm direct action of these transcription factors on the Xdh gene, chromatin immunoprecipitation was performed indicating that hemin significantly enriched (∼5-fold) both Sp1 and NF-kB near the transcription start site. In summary, our study identified a previously unknown pathway by which XOR is upregulated via SP1/NF-kB and subsequently exported to the extracellular environment. This is, to our knowledge, the very first study to demonstrate mechanistically that XOR can be specifically targeted for export as the seminal step in a compensatory response to heme/Fe overload.

Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

Nitro fatty acids (NO 2 -FAs) are endogenously generated lipid signaling mediators from metabolic and inflammatory reactions between conjugated diene fatty acids and nitric oxide or nitrite-derived reactive species. NO 2 -FAs undergo reversible Michael addition with hyperreactive protein cysteine thiolates to induce posttranslational protein modifications that can impact protein function. Herein, we report a novel mechanism of action of natural and non-natural nitroalkenes structurally similar to ( E ) 10-nitro-octadec-9-enoic acid (CP-6), recently de-risked by preclinical Investigational New Drug-enabling studies and Phase 1 and Phase 2 clinical trials and found to induce DNA damage in a TNBC xenograft by inhibiting homologous-recombination (HR)-mediated repair of DNA double-strand breaks (DSB). CP-6 specifically targets Cys319, essential in RAD51-controlled HR-mediated DNA DSB repair in cells. A nitroalkene library screen identified two structurally different nitroalkenes, a non-natural fatty acid [( E ) 8-nitro- nonadec-7-enoic acid (CP-8)] and a dicarboxylate ester [dimethyl ( E )nitro-oct-4-enedioate (CP- 23)] superior to CP-6 in TNBC cells killing, synergism with three different inhibitors of the poly ADP-ribose polymerase (PARP) and γ-IR. CP-8 and CP-23 effectively inhibited γ-IR-induced RAD51 foci formation and HR in a GFP-reported assay but did not affect benign human epithelial cells or cell cycle phases. In vivo, CP-8 and CP-23's efficacies diverged as only CP-8 showed promising anticancer activities alone and combined with the PARP inhibitor talazoparib in an HR-proficient TNBC mouse model. As preliminary preclinical toxicology analysis also suggests CP-8 as safe, our data endorse CP-8 as a novel anticancer molecule for treating cancers sensitive to homologous recombination-mediated DNA repair inhibitors.

Small molecule nitroalkenes inhibit RAD51-mediated homologous recombination and amplify triple-negative breast cancer cell killing by DNA-directed therapies.

Nitro fatty acids (NO2-FAs) are endogenously generated lipid signaling mediators from metabolic and inflammatory reactions between conjugated diene fatty acids and nitric oxide or nitrite-derived reactive species. NO2-FAs undergo reversible Michael addition with hyperreactive protein cysteine thiolates to induce posttranslational protein modifications that can impact protein function. Herein, we report a novel mechanism of action of natural and non-natural nitroalkenes structurally similar to (E) 10-nitro-octadec-9-enoic acid (CP-6), recently de-risked by preclinical Investigational New Drug-enabling studies and Phase 1 and Phase 2 clinical trials and found to induce DNA damage in a TNBC xenograft by inhibiting homologous-recombination (HR)-mediated repair of DNA double-strand breaks (DSB). CP-6 specifically targets Cys319, essential in RAD51-controlled HR-mediated DNA DSB repair in cells. A nitroalkene library screen identified two structurally different nitroalkenes, a non-natural fatty acid [(E) 8-nitro-nonadec-7-enoic acid (CP-8)] and a dicarboxylate ester [dimethyl (E)nitro-oct-4-enedioate (CP-23)] superior to CP-6 in TNBC cells killing, synergism with three different inhibitors of the poly ADP-ribose polymerase (PARP) and γ-IR. CP-8 and CP-23 effectively inhibited γ-IR-induced RAD51 foci formation and HR in a GFP-reported assay but did not affect benign human epithelial cells or cell cycle phases. In vivo, CP-8 and CP-23's efficacies diverged as only CP-8 showed promising anticancer activities alone and combined with the PARP inhibitor talazoparib in an HR-proficient TNBC mouse model. As preliminary preclinical toxicology analysis also suggests CP-8 as safe, our data endorse CP-8 as a novel anticancer molecule for treating cancers sensitive to homologous recombination-mediated DNA repair inhibitors.

Design and characteristics of the prophylactic intra-operative ventricular arrhythmia ablation in high-risk LVAD candidates (PIVATAL) trial.

BACKGROUND: The use of a Left Ventricular Assist Device (LVAD) in patients with advanced heart failure refractory to optimal medical management has progressed steadily over the past two decades. Data have demonstrated reduced LVAD efficacy, worse clinical outcome, and higher mortality for patients who experience significant ventricular tachyarrhythmia (VTA). We hypothesize that a novel prophylactic intra-operative VTA ablation protocol at the time of LVAD implantation may reduce the recurrent VTA and adverse events postimplant. METHODS: We designed a prospective, multicenter, open-label, randomized-controlled clinical trial enrolling 100 patients who are LVAD candidates with a history of VTA in the previous 5 years. Enrolled patients will be randomized in a 1:1 fashion to intra-operative VTA ablation (n = 50) versus conventional medical management (n = 50) with LVAD implant. Arrhythmia outcomes data will be captured by an implantable cardioverter defibrillator (ICD) to monitor VTA events, with a uniform ICD programming protocol. Patients will be followed prospectively over a mean of 18 months (with a minimum of 9 months) after LVAD implantation to evaluate recurrent VTA, adverse events, and procedural outcomes. Secondary endpoints include right heart function/hemodynamics, healthcare utilization, and quality of life. CONCLUSION: The primary aim of this first-ever randomized trial is to assess the efficacy of intra-operative ablation during LVAD surgery in reducing VTA recurrence and improving clinical outcomes for patients with a history of VTA.

Preoperative central corneal thickness in eyes with pediatric cataract versus normal fellow eyes.

PURPOSE: To compare the preoperative central corneal thickness (CCT) in eyes with unilateral cataract with their normal fellow eyes in the pediatric population. METHODS: A retrospective chart review was conducted using the STORM Kids cataract database. Eyes with traumatic cataract, previous surgery or therapeutic manipulation, or age >18 years were excluded. Only eyes with a normal fellow eye were included. The intraocular pressure, age at time of surgery, race, sex, and type of cataract were also extracted from the record. RESULTS: A total of 70 eyes with unilateral cataract and 70 fellow normal eyes met inclusion criteria. The mean age at the time of surgery was 3.35 years (range, 0.08-15.05). The mean preoperative CCT in the operated eyes was 577 ± 58 µm (range, 464-898 µm). The mean preoperative CCT in fellow eyes was 570 ± 35 µm (range, 485-643 µm). There was no statistically significant difference between the preoperative CCT in cataract eyes versus unaffected fellow eyes (P = 0.183). When stratified by age, the difference in the CCT between cataract and fellow eyes was greatest in the <1 year age group, but was not statistically significant (P = 0.236). The mean preoperative corneal diameter of operative eyes was 11.0 mm (range, 5.5-12.5 mm [n = 68]). The mean preoperative IOP was 15.1 mm Hg (n = 66). CONCLUSIONS: In our study cohort, there was no significant difference in mean preoperative CCT between unilateral pediatric cataract eyes and unaffected fellow eyes.

Release of hepatic xanthine oxidase (XO) to the circulation is protective in intravascular hemolytic crisis.

Xanthine oxidase (XO) catalyzes the catabolism of hypoxanthine to xanthine and xanthine to uric acid, generating oxidants as a byproduct. Importantly, XO activity is elevated in numerous hemolytic conditions including sickle cell disease (SCD); however, the role of XO in this context has not been elucidated. Whereas long-standing dogma suggests elevated levels of XO in the vascular compartment contribute to vascular pathology via increased oxidant production, herein, we demonstrate, for the first time, that XO has an unexpected protective role during hemolysis. Using an established hemolysis model, we found that intravascular hemin challenge (40 µmol/kg) resulted in a significant increase in hemolysis and an immense (20-fold) elevation in plasma XO activity in Townes sickle cell phenotype (SS) sickle mice compared to controls. Repeating the hemin challenge model in hepatocyte-specific XO knockout mice transplanted with SS bone marrow confirmed the liver as the source of enhanced circulating XO as these mice demonstrated 100% lethality compared to 40% survival in controls. In addition, studies in murine hepatocytes (AML12) revealed hemin mediates upregulation and release of XO to the medium in a toll like receptor 4 (TLR4)-dependent manner. Furthermore, we demonstrate that XO degrades oxyhemoglobin and releases free hemin and iron in a hydrogen peroxide-dependent manner. Additional biochemical studies revealed purified XO binds free hemin to diminish the potential for deleterious hemin-related redox reactions as well as prevents platelet aggregation. In the aggregate, data herein reveals that intravascular hemin challenge induces XO release by hepatocytes through hemin-TLR4 signaling, resulting in an immense elevation of circulating XO. This increased XO activity in the vascular compartment mediates protection from intravascular hemin crisis by binding and potentially degrading hemin at the apical surface of the endothelium where XO is known to be bound and sequestered by endothelial glycosaminoglycans (GAGs).

Left atrial appendage exclusion with less invasive left ventricular assist device implantation.

OBJECTIVES: The objective of this single-center, pilot, prospective, and historical control study is to evaluate safety and feasibility outcomes associated with left atrial appendage exclusion (LAAE) concomitant with left ventricular assist device (LVAD) implantation via less invasive surgery (LIS) as a stroke prevention strategy. METHODS: A predefined number of 30 eligible subjects scheduled for LIS LVAD with LAAE were enrolled in the prospective arm between January 2020 and February 2021. Eligible retrospective LIS LVAD patients without LAAE were propensity-matched in a 1:1 ratio with the prospective arm subjects. The primary study objectives were to evaluate the safety, feasibility, and efficacy of the LAAE concomitant with LIS LVAD. RESULTS: Preoperative characteristics of patients in the Non-LAAE and LAAE groups were similar. LAAE was successfully excluded in all prospective patients (100%). Primary safety endpoints of chest tube output within the first 24 postoperative hours, Reoperation for bleeding within 48 h, and index hospitalization mortality demonstrated comparable safety of LAAE versus Non-LAAE with LIS LVAD. Cox proportional hazard regression demonstrated that LAAE with LIS LVAD was associated with 37% and 49% reduction in the risk of stroke and disabling stroke, respectively (p > .05). CONCLUSION: Results from our pilot study demonstrated the safety and feasibility of LAAE concomitant with LIS LVAD as a stroke prevention strategy. This is the first prospective study describing LAAE performed concomitantly to less invasive LVAD implantation. The efficacy of LAAE in long-term stroke prevention needs to be confirmed in future prospective randomized clinical trials.

Cytochrome b5 reductases: Redox regulators of cell homeostasis.

The cytochrome-b5 reductase (CYB5R) family of flavoproteins is known to regulate reduction-oxidation (redox) balance in cells. The five enzyme members are highly compartmentalized at the subcellular level and function as "redox switches" enabling the reduction of several substrates, such as heme and coenzyme Q. Critical insight into the physiological and pathophysiological significance of CYB5R enzymes has been gleaned from several human genetic variants that cause congenital disease and a broad spectrum of chronic human diseases. Among the CYB5R genetic variants, CYB5R3 is well-characterized and deficiency in expression and activity is associated with type II methemoglobinemia, cancer, neurodegenerative disorders, diabetes, and cardiovascular disease. Importantly, pharmacological and genetic-based strategies are underway to target CYB5R3 to circumvent disease onset and mitigate severity. Despite our knowledge of CYB5R3 in human health and disease, the other reductases in the CYB5R family have been understudied, providing an opportunity to unravel critical function(s) for these enzymes in physiology and disease. In this review, we aim to provide the broad scientific community an up-to-date overview of the molecular, cellular, physiological, and pathophysiological roles of CYB5R proteins.

Loss of cardiomyocyte CYB5R3 impairs redox equilibrium and causes sudden cardiac death.

Sudden cardiac death (SCD) in patients with heart failure (HF) is allied with an imbalance in reduction and oxidation (redox) signaling in cardiomyocytes; however, the basic pathways and mechanisms governing redox homeostasis in cardiomyocytes are not fully understood. Here, we show that cytochrome b5 reductase 3 (CYB5R3), an enzyme known to regulate redox signaling in erythrocytes and vascular cells, is essential for cardiomyocyte function. Using a conditional cardiomyocyte-specific CYB5R3-knockout mouse, we discovered that deletion of CYB5R3 in male, but not female, adult cardiomyocytes causes cardiac hypertrophy, bradycardia, and SCD. The increase in SCD in CYB5R3-KO mice is associated with calcium mishandling, ventricular fibrillation, and cardiomyocyte hypertrophy. Molecular studies reveal that CYB5R3-KO hearts display decreased adenosine triphosphate (ATP), increased oxidative stress, suppressed coenzyme Q levels, and hemoprotein dysregulation. Finally, from a translational perspective, we reveal that the high-frequency missense genetic variant rs1800457, which translates into a CYB5R3 T117S partial loss-of-function protein, associates with decreased event-free survival (~20%) in Black persons with HF with reduced ejection fraction (HFrEF). Together, these studies reveal a crucial role for CYB5R3 in cardiomyocyte redox biology and identify a genetic biomarker for persons of African ancestry that may potentially increase the risk of death from HFrEF.

Patient-Reported Outcomes Measurement Information System (PROMIS) in Left Ventricular Assist Devices.

BACKGROUND: Appropriate collection of quality of life measurements for left ventricular assist device (LVAD) patients is challenging. Patient-Reported Outcomes Measurement Information System (PROMIS) is a popular tool that has been validated across multiple disciplines, but its applicability to the LVAD population remains unknown. METHODS: This single-center, retrospective review included LVAD patients who completed a PROMIS assessment and Kansas City Cardiomyopathy Questionnaire (KCCQ-12) survey at clinical encounters postoperatively. Patients completed computer adaptive PROMIS assessments for physical function, pain interference, and depression. All PROMIS domains are designed to follow a normal distribution (mean T-score 50, SD 10) in the general population. Assessments were aggregated over time and correlation between the KCCQ-12 summary score and each PROMIS domain was assessed individually. RESULTS: A total of 178 LVAD patients were included in the study. The median time between LVAD implantation and PRO collection was 16.5 [interquartile range, 7.9-37.8] months. Patients typically had worse physical function (T-score 38.8 [33.6-44.2]) but comparable pain (51.1 [38.7-59.2]) and depression (49.9 [41.7-57.5]) as the general population. The KCCQ-12 was more strongly correlated to PROMIS physical function (Spearman's ρ = 0.746) than pain (ρ = -0.539) or depression (ρ = -0.591). CONCLUSIONS: PROMIS provides a robust quality of life data collection system that can be implemented in a clinical setting without imposing a significant burden. Using this more holistic system may allow for better patient-centered care in order to address quality of life limitations imposed by LVAD support that are not directly related to heart failure symptoms.

Cooperation between CYB5R3 and NOX4 via coenzyme Q mitigates endothelial inflammation.

NADPH oxidase 4 (NOX4) regulates endothelial inflammation by producing hydrogen peroxide (H2O2) and to a lesser extent O2•-. The ratio of NOX4-derived H2O2 and O2•- can be altered by coenzyme Q (CoQ) mimics. Therefore, we hypothesize that cytochrome b5 reductase 3 (CYB5R3), a CoQ reductase abundant in vascular endothelial cells, regulates inflammatory activation. To examine endothelial CYB5R3 in vivo, we created tamoxifen-inducible endothelium-specific Cyb5r3 knockout mice (R3 KO). Radiotelemetry measurements of systolic blood pressure showed systemic hypotension in lipopolysaccharides (LPS) challenged mice, which was exacerbated in R3 KO mice. Meanwhile, LPS treatment caused greater endothelial dysfunction in R3 KO mice, evaluated by acetylcholine-induced vasodilation in the isolated aorta, accompanied by elevated mRNA expression of vascular adhesion molecule 1 (Vcam-1). Similarly, in cultured human aortic endothelial cells (HAEC), LPS and tumor necrosis factor α (TNF-α) induced VCAM-1 protein expression was enhanced by Cyb5r3 siRNA, which was ablated by silencing the Nox4 gene simultaneously. Moreover, super-resolution confocal microscopy indicated mitochondrial co-localization of CYB5R3 and NOX4 in HAECs. APEX2-based electron microscopy and proximity biotinylation also demonstrated CYB5R3's localization on the mitochondrial outer membrane and its interaction with NOX4, which was further confirmed by the proximity ligation assay. Notably, Cyb5r3 knockdown HAECs showed less total H2O2 but more mitochondrial O2•-. Using inactive or non-membrane bound active CYB5R3, we found that CYB5R3 activity and membrane translocation are needed for optimal generation of H2O2 by NOX4. Lastly, cells lacking the CoQ synthesizing enzyme COQ6 showed decreased NOX4-derived H2O2, indicating a requirement for endogenous CoQ in NOX4 activity. In conclusion, CYB5R3 mitigates endothelial inflammatory activation by assisting in NOX4-dependent H2O2 generation via CoQ.

Smoking and the Risk of Stroke in Patients with a Left Ventricular Assist device.

There are limited data on the association of smoking with the risk of stroke following left ventricular assist device (LVAD) implantation. We designed this study to analyze the impact of smoking status at the time of LVAD implantation on stroke. We hypothesized that current smokers are at increased risk of stroke when compared with patients who were former or never smokers. The study population comprised of 369 patients in the University of Rochester Medical Center LVAD database, implanted with an LVAD between 2008 and 2018. Patients were stratified as current smoker (smoking within 30 days before LVAD implantation), former smoker, and never smoker. Stroke was defined as a transient ischemic attack or cerebrovascular accident (hemorrhagic or ischemic). There were 45 current smokers, 198 former smokers, and 125 never smokers. Current smokers were younger (mean age 50 ± 11 years), as compared with former (58 ± 12 years) and never smokers (56 ± 13 years) p < 0.001. At 2 years following LVAD implantation, the cumulative incidence of stroke was significantly higher among current smokers (39%) as compared with former and never smokers (16% and 15%, respectively; p = 0.022 for the overall difference during follow-up). In a multivariate model adjusted for significant clinical variables, current smoking was associated with a significant 88% (p = 0.018) higher risk of stroke when compared with all noncurrent smokers. In conclusion, our data suggest that LVAD candidates who are current smokers experience a significantly higher risk of stroke following device implantation.

Viability and thresholds for treatment of extremely preterm infants: survey of UK neonatal professionals.

BACKGROUND: Decisions about treatments for extremely preterm infants (EPIs) born in the 'grey zone' of viability can be ethically complex. This 2020 survey aimed to determine views of UK neonatal staff about thresholds for treatment of EPIs given a recently revised national Framework for Practice from the British Association of Perinatal Medicine. METHODS: The online survey requested participants indicate the lowest gestation at which they would be willing to offer active treatment and the highest gestation at which they would withhold active treatment of an EPI at parental request (their lower and upper thresholds). Relative risks were used to compare respondents' views based on profession and neonatal unit designation. Further questions explored respondents' conceptual understanding of viability. RESULTS: 336 respondents included 167 consultants, 127 registrars/fellows and 42 advanced neonatal nurse practitioners (ANNPs). Respondents reported a median grey zone for neonatal resuscitation between 22+1 and 24+0 weeks' gestation. Registrars/fellows were more likely to select a lower threshold at 22+0 weeks compared with consultants (Relative Risk (RR)=1.37 (95% CI 1.07 to 1.74)) and ANNPs (RR=2.68 (95% CI 1.42 to 5.06)). Those working in neonatal intensive care units compared with other units were also more likely to offer active treatment at 22+0 weeks (RR=1.86 (95% CI 1.18 to 2.94)). Most participants understood a fetus/newborn to be 'viable' if it was possible to survive, regardless of disability, with medical interventions accessible to the treating team. CONCLUSION: Compared with previous studies, we found a shift in the reported lower threshold for resuscitation in the UK, with greater acceptance of active treatment for infants <23 weeks' gestation.

Complete sternal-sparing left ventricular assist device implantation is associated with improved postoperative mobility.

Left ventricular assist device (LVAD) implantation via a complete sternal-sparing (CSS) technique is gaining interest due to several potential benefits. We hypothesized that the CSS approach for HeartMate 3 (HM3) LVAD implantation improves postoperative mobility and physical independence compared to full sternotomy (FS). We retrospectively reviewed patients who were implanted with a commercial HM3 at our institution from September 2017 to August 2018. The Activity Measure for Post-Acute Care short forms and Functional Independence Measure scores were used to assess the patient's physical limitations postoperatively. A total of 43 patients were included in the study: 27 (63%) CSS patients and 16 (37%) FS patients. At postoperative day 3, the CSS cohort demonstrated improved mobility based on Activity Measure for Post-Acute Care scores compared to the FS group; 40% of the CSS cohort versus 67% of the FS cohort remained 100% impaired. The CSS cohort also demonstrated greater postoperative independence in the Functional Independence Measure sit-to-stand metric with 78% of the CSS cohort achieving modified or complete independence by postoperative day 15 compared to only 21% of the FS patients. These early data suggest that the CSS approach for HM3 LVAD implantation improves postoperative mobility and functional independence compared to FS.

The Role of the U5 snRNP in Genetic Disorders and Cancer.

Pre-mRNA splicing is performed by the spliceosome, a dynamic macromolecular complex consisting of five small uridine-rich ribonucleoprotein complexes (the U1, U2, U4, U5, and U6 snRNPs) and numerous auxiliary splicing factors. A plethora of human disorders are caused by genetic variants affecting the function and/or expression of splicing factors, including the core snRNP proteins. Variants in the genes encoding proteins of the U5 snRNP cause two distinct and tissue-specific human disease phenotypes - variants in PRPF6, PRPF8, and SNRP200 are associated with retinitis pigmentosa (RP), while variants in EFTUD2 and TXNL4A cause the craniofacial disorders mandibulofacial dysostosis Guion-Almeida type (MFDGA) and Burn-McKeown syndrome (BMKS), respectively. Furthermore, recurrent somatic mutations or changes in the expression levels of a number of U5 snRNP proteins (PRPF6, PRPF8, EFTUD2, DDX23, and SNRNP40) have been associated with human cancers. How and why variants in ubiquitously expressed spliceosome proteins required for pre-mRNA splicing in all human cells result in tissue-restricted disease phenotypes is not clear. Additionally, why variants in different, yet interacting, proteins making up the same core spliceosome snRNP result in completely distinct disease outcomes - RP, craniofacial defects or cancer - is unclear. In this review, we define the roles of different U5 snRNP proteins in RP, craniofacial disorders and cancer, including how disease-associated genetic variants affect pre-mRNA splicing and the proposed disease mechanisms. We then propose potential hypotheses for how U5 snRNP variants cause tissue specificity resulting in the restricted and distinct human disorders.