Multi-modal adaptor-clathrin contacts drive coated vesicle assembly.

Clathrin-coated pits are formed by the recognition of membrane and cargo by the AP2 complex and the subsequent recruitment of clathrin triskelia. A role for AP2 in coated-pit assembly beyond initial clathrin recruitment has not been explored. Clathrin binds the ß2 subunit of AP2, and several binding sites have been identified, but our structural knowledge of these interactions is incomplete and their functional importance during endocytosis is unclear. Here, we analysed the cryo-EM structure of clathrin cages assembled in the presence of ß2 hinge-appendage (ß2HA). We find that the ß2-appendage binds in at least two positions in the cage, demonstrating that multi-modal binding is a fundamental property of clathrin-AP2 interactions. In one position, ß2-appendage cross-links two adjacent terminal domains from different triskelia. Functional analysis of ß2HA-clathrin interactions reveals that endocytosis requires two clathrin interaction sites: a clathrin-box motif on the hinge and the "sandwich site" on the appendage. We propose that ß2-appendage binding to more than one triskelion is a key feature of the system and likely explains why assembly is driven by AP2.

The chemotactic receptor EBI2 regulates the homeostasis, localization and immunological function of splenic dendritic cells.

Spleen-resident dendritic cell (DC) populations occupy sentinel positions for the capture and presentation of blood-borne antigens. Here we found a difference in expression of the chemotactic receptor EBI2 (GPR183) on splenic DC subsets and that EBI2 regulated the positioning and homeostasis of DCs in the spleen. EBI2 and its main ligand, 7α,25-OHC, were required for the generation of the splenic CD4(+) DC subset and the localization of DCs in bridging channels. Absence of EBI2 from DCs resulted in defects in both the activation of CD4(+) T cells and the induction of antibody responses. Regulated expression of EBI2 on DC populations is therefore critical for the generation and correct positioning of splenic DCs and the initiation of immune responses.

Reversible Inactivation of Ferret Auditory Cortex Impairs Spatial and Nonspatial Hearing.

A key question in auditory neuroscience is to what extent are brain regions functionally specialized for processing specific sound features, such as location and identity. In auditory cortex, correlations between neural activity and sounds support both the specialization of distinct cortical subfields, and encoding of multiple sound features within individual cortical areas. However, few studies have tested the contribution of auditory cortex to hearing in multiple contexts. Here we determined the role of ferret primary auditory cortex in both spatial and nonspatial hearing by reversibly inactivating the middle ectosylvian gyrus during behavior using cooling (n = 2 females) or optogenetics (n = 1 female). Optogenetic experiments used the mDLx promoter to express Channelrhodopsin-2 in GABAergic interneurons, and we confirmed both viral expression (n = 2 females) and light-driven suppression of spiking activity in auditory cortex, recorded using Neuropixels under anesthesia (n = 465 units from 2 additional untrained female ferrets). Cortical inactivation via cooling or optogenetics impaired vowel discrimination in colocated noise. Ferrets implanted with cooling loops were tested in additional conditions that revealed no deficit when identifying vowels in clean conditions, or when the temporally coincident vowel and noise were spatially separated by 180 degrees. These animals did, however, show impaired sound localization when inactivating the same auditory cortical region implicated in vowel discrimination in noise. Our results demonstrate that, as a brain region showing mixed selectivity for spatial and nonspatial features of sound, primary auditory cortex contributes to multiple forms of hearing.SIGNIFICANCE STATEMENT Neurons in primary auditory cortex are often sensitive to the location and identity of sounds. Here we inactivated auditory cortex during spatial and nonspatial listening tasks using cooling, or optogenetics. Auditory cortical inactivation impaired multiple behaviors, demonstrating a role in both the analysis of sound location and identity and confirming a functional contribution of mixed selectivity observed in neural activity. Parallel optogenetic experiments in two additional untrained ferrets linked behavior to physiology by demonstrating that expression of Channelrhodopsin-2 permitted rapid light-driven suppression of auditory cortical activity recorded under anesthesia.

SOD2 V16A amplifies vascular dysfunction in sickle cell patients by curtailing mitochondria complex IV activity.

Superoxide dismutase 2 (SOD2) catalyzes the dismutation of superoxide to hydrogen peroxide in mitochondria, limiting mitochondrial damage. The SOD2 amino acid valine-to-alanine substitution at position 16 (V16A) in the mitochondrial leader sequence is a common genetic variant among patients with sickle cell disease (SCD). However, little is known about the cardiovascular consequences of SOD2V16A in SCD patients or its impact on endothelial cell function. Here, we show SOD2V16A associates with increased tricuspid regurgitant velocity (TRV), systolic blood pressure, right ventricle area at systole, and declined 6-minute walk distance in 410 SCD patients. Plasma lactate dehydrogenase, a marker of oxidative stress and hemolysis, significantly associated with higher TRV. To define the impact of SOD2V16A in the endothelium, we introduced the SOD2V16A variant into endothelial cells. SOD2V16A increases hydrogen peroxide and mitochondrial reactive oxygen species (ROS) production compared with controls. Unexpectedly, the increased ROS was not due to SOD2V16A mislocalization but was associated with mitochondrial complex IV and a concomitant decrease in basal respiration and complex IV activity. In sum, SOD2V16A is a novel clinical biomarker of cardiovascular dysfunction in SCD patients through its ability to decrease mitochondrial complex IV activity and amplify ROS production in the endothelium.

Insurance-based Disparities in Outcomes and Extracorporeal Membrane Oxygenation Utilization for Hospitalized COVID-19 Patients.

BACKGROUND: The objective of this study was to examine insurance-based disparities in mortality, nonhome discharges, and extracorporeal membrane oxygenation utilization in patients hospitalized with COVID-19. METHODS: Using a national database of U.S. academic medical centers and their affiliated hospitals, the risk-adjusted association between mortality, nonhome discharge, and extracorporeal membrane oxygenation utilization and (1) the type of insurance coverage (private insurance, Medicare, dual enrollment in Medicare and Medicaid, and no insurance) and (2) the weekly hospital COVID-19 burden (0 to 5.0%; 5.1 to 10%, 10.1 to 20%, 20.1 to 30%, and 30.1% and greater) was evaluated. Modeling was expanded to include an interaction between payer status and the weekly hospital COVID-19 burden to examine whether the lack of private insurance was associated with increases in disparities as the COVID-19 burden increased. RESULTS: Among 760,846 patients hospitalized with COVID-19, 214,992 had private insurance, 318,624 had Medicare, 96,192 were dually enrolled in Medicare and Medicaid, 107,548 had Medicaid, and 23,560 had no insurance. Overall, 76,250 died, 211,702 had nonhome discharges, 75,703 were mechanically ventilated, and 2,642 underwent extracorporeal membrane oxygenation. The adjusted odds of death were higher in patients with Medicare (adjusted odds ratio, 1.28 [95% CI, 1.21 to 1.35]; P < 0.0005), dually enrolled (adjusted odds ratio, 1.39 [95% CI, 1.30 to 1.50]; P < 0.0005), Medicaid (adjusted odds ratio, 1.28 [95% CI, 1.20 to 1.36]; P < 0.0005), and no insurance (adjusted odds ratio, 1.43 [95% CI, 1.26 to 1.62]; P < 0.0005) compared to patients with private insurance. Patients with Medicare (adjusted odds ratio, 0.47; [95% CI, 0.39 to 0.58]; P < 0.0005), dually enrolled (adjusted odds ratio, 0.32 [95% CI, 0.24 to 0.43]; P < 0.0005), Medicaid (adjusted odds ratio, 0.70 [95% CI, 0.62 to 0.79]; P < 0.0005), and no insurance (adjusted odds ratio, 0.40 [95% CI, 0.29 to 0.56]; P < 0.001) were less likely to be placed on extracorporeal membrane oxygenation than patients with private insurance. Mortality, nonhome discharges, and extracorporeal membrane oxygenation utilization did not change significantly more in patients with private insurance compared to patients without private insurance as the COVID-19 burden increased. CONCLUSIONS: Among patients with COVID-19, insurance-based disparities in mortality, nonhome discharges, and extracorporeal membrane oxygenation utilization were substantial, but these disparities did not increase as the hospital COVID-19 burden increased.

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.

Correction: Stability of spontaneous, correlated activity in mouse auditory cortex.

[This corrects the article DOI: 10.1371/journal.pcbi.1007360.].

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.

Smooth muscle cell CYB5R3 preserves cardiac and vascular function under chronic hypoxic stress.

Chronic hypoxia is a major driver of cardiovascular complications, including heart failure. The nitric oxide (NO) - soluble guanylyl cyclase (sGC) - cyclic guanosine monophosphate (cGMP) pathway is integral to vascular tone maintenance. Specifically, NO binds its receptor sGC within vascular smooth muscle cells (SMC) in its reduced heme (Fe2+) form to increase intracellular cGMP production, activate protein kinase G (PKG) signaling, and induce vessel relaxation. Under chronic hypoxia, oxidative stress drives oxidation of sGC heme (Fe2+→Fe3+), rendering it NO-insensitive. We previously showed that cytochrome b5 reductase 3 (CYB5R3) in SMC is a sGC reductase important for maintaining NO-dependent vasodilation and conferring resilience to systemic hypertension and sickle cell disease-associated pulmonary hypertension. To test whether CYB5R3 may be protective in the context of chronic hypoxia, we subjected SMC-specific CYB5R3 knockout mice (SMC CYB5R3 KO) to 3 weeks hypoxia and assessed vascular and cardiac function using echocardiography, pressure volume loops and wire myography. Hypoxic stress caused 1) biventricular hypertrophy in both WT and SMC CYB5R3 KO, but to a larger degree in KO mice, 2) blunted vasodilation to NO-dependent activation of sGC in coronary and pulmonary arteries of KO mice, and 3) decreased, albeit still normal, cardiac function in KO mice. Overall, these data indicate that SMC CYB5R3 deficiency potentiates bilateral ventricular hypertrophy and blunts NO-dependent vasodilation under chronic hypoxia conditions. This implicates that SMC CYB5R3 KO mice post 3-week hypoxia have early stages of cardiac remodeling and functional changes that could foretell significantly impaired cardiac function with longer exposure to hypoxia.

Expanding the genotypic spectrum of TXNL4A variants in Burn-McKeown syndrome.

The developmental disorder Burn-McKeown Syndrome (BMKS) is characterised by choanal atresia and specific craniofacial features. BMKS is caused by biallelic variants in the pre-messenger RNA splicing factor TXNL4A. Most patients have a loss-of-function variant in trans with a 34-base pair (bp) deletion (type 1 Δ34) in the promoter region. Here, we identified two patients with BMKS. One individual has a TXNL4A c.93_94delCC, p.His32Argfs *21 variant combined with a type 1 Δ34 promoter deletion. The other has an intronic TXNL4A splice site variant (c.258-3C>G) and a type 1 Δ34 promoter deletion. We show the c.258-3C>G variant and a previously reported c.258-2A>G variant, cause skipping of the final exon of TXNL4A in a minigene splicing assay. Furthermore, we identify putative transcription factor binding sites within the 56 bp of the TXNL4A promoter affected by the type 1 and type 2 Δ34 and use dual luciferase assays to identify a 22 bp repeated motif essential for TXNL4A expression within this promoter region. We propose that additional variants affecting critical transcription factor binding nucleotides within the 22 bp repeated motif could be relevant to BMKS aetiology. Finally, our data emphasises the need to analyse the non-coding sequence in individuals where a single likely pathogenic coding variant is identified in an autosomal recessive disorder consistent with the clinical presentation.

Xanthine Oxidase Drives Hemolysis and Vascular Malfunction in Sickle Cell Disease.

OBJECTIVE: Chronic hemolysis is a hallmark of sickle cell disease (SCD) and a driver of vasculopathy; however, the mechanisms contributing to hemolysis remain incompletely understood. Although XO (xanthine oxidase) activity has been shown to be elevated in SCD, its role remains unknown. XO binds endothelium and generates oxidants as a byproduct of hypoxanthine and xanthine catabolism. We hypothesized that XO inhibition decreases oxidant production leading to less hemolysis. Approach and Results: Wild-type mice were bone marrow transplanted with control (AA) or sickle (SS) Townes bone marrow. After 12 weeks, mice were treated with 10 mg/kg per day of febuxostat (Uloric), Food and Drug Administration-approved XO inhibitor, for 10 weeks. Hematologic analysis demonstrated increased hematocrit, cellular hemoglobin, and red blood cells, with no change in reticulocyte percentage. Significant decreases in cell-free hemoglobin and increases in haptoglobin suggest XO inhibition decreased hemolysis. Myographic studies demonstrated improved pulmonary vascular dilation and blunted constriction, indicating improved pulmonary vasoreactivity, whereas pulmonary pressure and cardiac function were unaffected. The role of hepatic XO in SCD was evaluated by bone marrow transplanting hepatocyte-specific XO knockout mice with SS Townes bone marrow. However, hepatocyte-specific XO knockout, which results in >50% diminution in circulating XO, did not affect hemolysis levels or vascular function, suggesting hepatocyte-derived elevation of circulating XO is not the driver of hemolysis in SCD. CONCLUSIONS: Ten weeks of febuxostat treatment significantly decreased hemolysis and improved pulmonary vasoreactivity in a mouse model of SCD. Although hepatic XO accounts for >50% of circulating XO, it is not the source of XO driving hemolysis in SCD.

Clathrin: the molecular shape shifter.

Clathrin is best known for its contribution to clathrin-mediated endocytosis yet it also participates to a diverse range of cellular functions. Key to this is clathrin's ability to assemble into polyhedral lattices that include curved football or basket shapes, flat lattices or even tubular structures. In this review, we discuss clathrin structure and coated vesicle formation, how clathrin is utilised within different cellular processes including synaptic vesicle recycling, hormone desensitisation, spermiogenesis, cell migration and mitosis, and how clathrin's remarkable 'shapeshifting' ability to form diverse lattice structures might contribute to its multiple cellular functions.

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.

Normative Beliefs about Social Withdrawal in Adolescence.

The goal of this study is to explore normative beliefs about social withdrawal during adolescence. Participants were N = 419 adolescents (Mage = 16.13 years), who completed measures of normative beliefs about social withdrawal and their own social withdrawal (shyness, unsociability). Among the results, adolescents reported greater overall acceptance of unsociability compared to shyness, however, some gender differences also emerged. Specifically, adolescents were more accepting of unsociability when depicted by hypothetical females, and more accepting of shyness when depicted by hypothetical males. Participant social withdrawal was associated with greater acceptance of socially withdrawn behaviors in others. These findings provide a first look at normative beliefs about social withdrawal during a developmentally critical age period for this construct.

Disease modeling of core pre-mRNA splicing factor haploinsufficiency.

The craniofacial disorder mandibulofacial dysostosis Guion-Almeida type is caused by haploinsufficiency of the U5 snRNP gene EFTUD2/SNU114. However, it is unclear how reduced expression of this core pre-mRNA splicing factor leads to craniofacial defects. Here we use a CRISPR-Cas9 nickase strategy to generate a human EFTUD2-knockdown cell line and show that reduced expression of EFTUD2 leads to diminished proliferative ability of these cells, increased sensitivity to endoplasmic reticulum (ER) stress and the mis-expression of several genes involved in the ER stress response. RNA-Seq analysis of the EFTUD2-knockdown cell line revealed transcriptome-wide changes in gene expression, with an enrichment for genes associated with processes involved in craniofacial development. Additionally, our RNA-Seq data identified widespread mis-splicing in EFTUD2-knockdown cells. Analysis of the functional and physical characteristics of mis-spliced pre-mRNAs highlighted conserved properties, including length and splice site strengths, of retained introns and skipped exons in our disease model. We also identified enriched processes associated with the affected genes, including cell death, cell and organ morphology and embryonic development. Together, these data support a model in which EFTUD2 haploinsufficiency leads to the mis-splicing of a distinct subset of pre-mRNAs with a widespread effect on gene expression, including altering the expression of ER stress response genes and genes involved in the development of the craniofacial region. The increased burden of unfolded proteins in the ER resulting from mis-splicing would exceed the capacity of the defective ER stress response, inducing apoptosis in cranial neural crest cells that would result in craniofacial abnormalities during development.

Elimination of germinal-center-derived self-reactive B cells is governed by the location and concentration of self-antigen.

Secondary diversification of the B cell repertoire by immunoglobulin gene somatic hypermutation in the germinal center (GC) is essential for providing the high-affinity antibody specificities required for long-term humoral immunity. While the risk to self-tolerance posed by inadvertent generation of self-reactive GC B cells has long been recognized, it has not previously been possible to identify such cells and study their fate. In the current study, self-reactive B cells generated de novo in the GC failed to survive when their target self-antigen was either expressed ubiquitously or specifically in cells proximal to the GC microenvironment. By contrast, GC B cells that recognized rare or tissue-specific self-antigens were not eliminated, and could instead undergo positive selection by cross-reactive foreign antigen and produce plasma cells secreting high-affinity autoantibodies. These findings demonstrate the incomplete nature of GC self-tolerance and may explain the frequent association of cross-reactive, organ-specific autoantibodies with postinfectious autoimmune disease.

Long-term renal function after venoarterial extracorporeal membrane oxygenation.

BACKGROUND: The utilization of venoarterial extracorporeal membrane oxygenation (VA-ECMO) as a life-supporting therapy has increased exponentially over the last decade. As more patients receive and survive ECMO, there are a number of unanswered clinical questions about their long-term prognosis and organ function including the need for long-term dialysis. METHODS: We aimed to utilize over 208 patient-years of follow-up data from our large institutional cohort of VA-ECMO patients to determine the incidence of requiring VA-ECMO support on the need for renal replacement therapy after discharge (LT-dialysis). This retrospective review included all adult VA-ECMO patients at our institution from January 2014 to October 2018 (N = 283). RESULTS: Out of the 99 (35%) survivors, 88 (89%) did not require LT-dialysis of any duration after discharge from the index hospitalization. Patients who required VA-ECMO for decompensated cardiogenic shock were more likely to need LT-dialysis (p = .034), and those who required renal replacement therapy during VA-ECMO (N = 27) also had a higher incidence of LT-dialysis (33%). CONCLUSION: Overall, these data suggest there is a low incidence of long-term dialysis dependence among survivors of VA-ECMO support. Worries about the potential long-term detrimental effect of VA-ECMO should not preclude patients from receiving this life-saving support.

EFTUD2 missense variants disrupt protein function and splicing in mandibulofacial dysostosis Guion-Almeida type.

Pathogenic variants in the core spliceosome U5 small nuclear ribonucleoprotein gene EFTUD2/SNU114 cause the craniofacial disorder mandibulofacial dysostosis Guion-Almeida type (MFDGA). MFDGA-associated variants in EFTUD2 comprise large deletions encompassing EFTUD2, intragenic deletions and single nucleotide truncating or missense variants. These variants are predicted to result in haploinsufficiency by loss-of-function of the variant allele. While the contribution of deletions within EFTUD2 to allele loss-of-function are self-evident, the mechanisms by which missense variants are disease-causing have not been characterized functionally. Combining bioinformatics software prediction, yeast functional growth assays, and a minigene (MG) splicing assay, we have characterized how MFDGA missense variants result in EFTUD2 loss-of-function. Only four of 19 assessed missense variants cause EFTUD2 loss-of-function through altered protein function when modeled in yeast. Of the remaining 15 missense variants, five altered the normal splicing pattern of EFTUD2 pre-messenger RNA predominantly through exon skipping or cryptic splice site activation, leading to the introduction of a premature termination codon. Comparison of bioinformatic predictors for each missense variant revealed a disparity amongst different software packages and, in many cases, an inability to correctly predict changes in splicing subsequently determined by MG interrogation. This study highlights the need for laboratory-based validation of bioinformatic predictions for EFTUD2 missense variants.

Stability of spontaneous, correlated activity in mouse auditory cortex.

Neural systems can be modeled as complex networks in which neural elements are represented as nodes linked to one another through structural or functional connections. The resulting network can be analyzed using mathematical tools from network science and graph theory to quantify the system's topological organization and to better understand its function. Here, we used two-photon calcium imaging to record spontaneous activity from the same set of cells in mouse auditory cortex over the course of several weeks. We reconstruct functional networks in which cells are linked to one another by edges weighted according to the correlation of their fluorescence traces. We show that the networks exhibit modular structure across multiple topological scales and that these multi-scale modules unfold as part of a hierarchy. We also show that, on average, network architecture becomes increasingly dissimilar over time, with similarity decaying monotonically with the distance (in time) between sessions. Finally, we show that a small fraction of cells maintain strongly-correlated activity over multiple days, forming a stable temporal core surrounded by a fluctuating and variable periphery. Our work indicates a framework for studying spontaneous activity measured by two-photon calcium imaging using computational methods and graphical models from network science. The methods are flexible and easily extended to additional datasets, opening the possibility of studying cellular level network organization of neural systems and how that organization is modulated by stimuli or altered in models of disease.

MELD-XI is predictive of mortality in venoarterial extracorporeal membrane oxygenation.

BACKGROUND: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is a life-saving method of supporting critically ill patients. However, it is expensive and associated with high morbidity and mortality, making early predictive outcome modeling extremely valuable. The model for end-stage liver disease-excluding international normalized ratio (MELD-XI) scoring system has been shown to have prognostic value in other critically ill patient populations. MATERIALS AND METHODS: A single-center retrospective review was performed for all adult patients managed on VA-ECMO from May 2011 to January 2018 (n = 247). Patients were included in the study if MELD-XI scores could be calculated during the first 48 hours on ECMO (n = 187). Receiver operating characteristic curve analysis was performed for MELD-XI in regard to in-hospital mortality. RESULTS: Of the 187 patients, 74 (40%) patients had MELD-XI less than 14 (low-risk) and 113 (60%) had a MELD-XI of 14 or greater (high-risk). The cohorts did not differ significantly in terms of patient characteristics or indication for ECMO. The high-risk MELD-XI group had significantly greater mortality during index hospitalization compared to the low-risk group (74% vs 39%; P < .0001). Quartile stratification demonstrated progressively worse prognosis associated with higher MELD-XI scores; the fourth quartile showed a ninefold increased risk of mortality compared to the first quartile (P < .001). The AUC for predicting index hospitalization mortality was 0.69 (95% CI, 0.62-0.77) with a Youden index (J) of 0.36 and optimized cutoff of 12.98. CONCLUSIONS: These findings suggest that the MELD-XI scoring system can be applied to the VA-ECMO patient population early in their course of ECMO as a prognostic tool to aid in complex clinical decision making.