An enzyme that selectively S-nitrosylates proteins to regulate insulin signaling.

Acyl-coenzyme A (acyl-CoA) species are cofactors for numerous enzymes that acylate thousands of proteins. Here, we describe an enzyme that uses S-nitroso-CoA (SNO-CoA) as its cofactor to S-nitrosylate multiple proteins (SNO-CoA-assisted nitrosylase, SCAN). Separate domains in SCAN mediate SNO-CoA and substrate binding, allowing SCAN to selectively catalyze SNO transfer from SNO-CoA to SCAN to multiple protein targets, including the insulin receptor (INSR) and insulin receptor substrate 1 (IRS1). Insulin-stimulated S-nitrosylation of INSR/IRS1 by SCAN reduces insulin signaling physiologically, whereas increased SCAN activity in obesity causes INSR/IRS1 hypernitrosylation and insulin resistance. SCAN-deficient mice are thus protected from diabetes. In human skeletal muscle and adipose tissue, SCAN expression increases with body mass index and correlates with INSR S-nitrosylation. S-nitrosylation by SCAN/SNO-CoA thus defines a new enzyme class, a unique mode of receptor tyrosine kinase regulation, and a revised paradigm for NO function in physiology and disease.

Reducing acetylated tau is neuroprotective in brain injury.

Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau. Subsequent tau mislocalization causes neurodegeneration and neurobehavioral impairment, and ac-tau accumulates in the blood. Blocking GAPDH S-nitrosylation, inhibiting p300/CBP, or stimulating Sirtuin1 all protect mice from neurodegeneration, neurobehavioral impairment, and blood and brain accumulation of ac-tau after TBI. Ac-tau is thus a therapeutic target and potential blood biomarker of TBI that may represent pathologic convergence between TBI and AD. Increased ac-tau in human AD brain is further augmented in AD patients with history of TBI, and patients receiving the p300/CBP inhibitors salsalate or diflunisal exhibit decreased incidence of AD and clinically diagnosed TBI.

S-nitrosylation is required for ß2AR desensitization and experimental asthma.

The ß2-adrenergic receptor (ß2AR), a prototypic G-protein-coupled receptor (GPCR), is a powerful driver of bronchorelaxation, but the effectiveness of ß-agonist drugs in asthma is limited by desensitization and tachyphylaxis. We find that during activation, the ß2AR is modified by S-nitrosylation, which is essential for both classic desensitization by PKA as well as desensitization of NO-based signaling that mediates bronchorelaxation. Strikingly, S-nitrosylation alone can drive ß2AR internalization in the absence of traditional agonist. Mutant ß2AR refractory to S-nitrosylation (Cys265Ser) exhibits reduced desensitization and internalization, thereby amplifying NO-based signaling, and mice with Cys265Ser mutation are resistant to bronchoconstriction, inflammation, and the development of asthma. S-nitrosylation is thus a central mechanism in ß2AR signaling that may be operative widely among GPCRs and targeted for therapeutic gain.

Control of tissue oxygenation by S-nitrosohemoglobin in human subjects.

S-Nitrosohemoglobin (SNO-Hb) is unique among vasodilators in coupling blood flow to tissue oxygen requirements, thus fulfilling an essential function of the microcirculation. However, this essential physiology has not been tested clinically. Reactive hyperemia following limb ischemia/occlusion is a standard clinical test of microcirculatory function, which has been ascribed to endothelial nitric oxide (NO). However, endothelial NO does not control blood flow governing tissue oxygenation, presenting a major quandary. Here we show in mice and humans that reactive hyperemic responses (i.e., reoxygenation rates following brief ischemia/occlusion) are in fact dependent on SNO-Hb. First, mice deficient in SNO-Hb (i.e., carrying C93A mutant Hb refractory to S-nitrosylation) showed blunted muscle reoxygenation rates and persistent limb ischemia during reactive hyperemia testing. Second, in a diverse group of humans-including healthy subjects and patients with various microcirculatory disorders-strong correlations were found between limb reoxygenation rates following occlusion and both arterial SNO-Hb levels (n = 25; P = 0.042) and SNO-Hb/total HbNO ratios (n = 25; P = 0.009). Secondary analyses showed that patients with peripheral artery disease had significantly reduced SNO-Hb levels and blunted limb reoxygenation rates compared with healthy controls (n = 8 to 11/group; P < 0.05). Low SNO-Hb levels were also observed in sickle cell disease, where occlusive hyperemic testing was deemed contraindicated. Altogether, our findings provide both genetic and clinical support for the role of red blood cells in a standard test of microvascular function. Our results also suggest that SNO-Hb is a biomarker and mediator of blood flow governing tissue oxygenation. Thus, increases in SNO-Hb may improve tissue oxygenation in patients with microcirculatory disorders.

P7C3-A20 treatment one year after TBI in mice repairs the blood-brain barrier, arrests chronic neurodegeneration, and restores cognition.

Chronic neurodegeneration in survivors of traumatic brain injury (TBI) is a major cause of morbidity, with no effective therapies to mitigate this progressive and debilitating form of nerve cell death. Here, we report that pharmacologic restoration of the blood-brain barrier (BBB), 12 mo after murine TBI, is associated with arrested axonal neurodegeneration and cognitive recovery, benefits that persisted for months after treatment cessation. Recovery was achieved by 30 d of once-daily administration of P7C3-A20, a compound that stabilizes cellular energy levels. Four months after P7C3-A20, electron microscopy revealed full repair of TBI-induced breaks in cortical and hippocampal BBB endothelium. Immunohistochemical staining identified additional benefits of P7C3-A20, including restoration of normal BBB endothelium length, increased brain capillary pericyte density, increased expression of BBB tight junction proteins, reduced brain infiltration of immunoglobulin, and attenuated neuroinflammation. These changes were accompanied by cessation of TBI-induced chronic axonal degeneration. Specificity for P7C3-A20 action on the endothelium was confirmed by protection of cultured human brain microvascular endothelial cells from hydrogen peroxide-induced cell death, as well as preservation of BBB integrity in mice after exposure to toxic levels of lipopolysaccharide. P7C3-A20 also protected mice from BBB degradation after acute TBI. Collectively, our results provide insights into the pathophysiologic mechanisms behind chronic neurodegeneration after TBI, along with a putative treatment strategy. Because TBI increases the risks of other forms of neurodegeneration involving BBB deterioration (e.g., Alzheimer's disease, Parkinson's disease, vascular dementia, chronic traumatic encephalopathy), P7C3-A20 may have widespread clinical utility in the setting of neurodegenerative conditions.

Role of Nitric Oxide Carried by Hemoglobin in Cardiovascular Physiology: Developments on a Three-Gas Respiratory Cycle.

A continuous supply of oxygen is essential for the survival of multicellular organisms. The understanding of how this supply is regulated in the microvasculature has evolved from viewing erythrocytes (red blood cells [RBCs]) as passive carriers of oxygen to recognizing the complex interplay between Hb (hemoglobin) and oxygen, carbon dioxide, and nitric oxide-the three-gas respiratory cycle-that insures adequate oxygen and nutrient delivery to meet local metabolic demand. In this context, it is blood flow and not blood oxygen content that is the main driver of tissue oxygenation by RBCs. Herein, we review the lines of experimentation that led to this understanding of RBC function; from the foundational understanding of allosteric regulation of oxygen binding in Hb in the stereochemical model of Perutz, to blood flow autoregulation (hypoxic vasodilation governing oxygen delivery) observed by Guyton, to current understanding that centers on S-nitrosylation of Hb (ie, S-nitrosohemoglobin; SNO-Hb) as a purveyor of oxygen-dependent vasodilatory activity. Notably, hypoxic vasodilation is recapitulated by native S-nitrosothiol (SNO)-replete RBCs and by SNO-Hb itself, whereby SNO is released from Hb and RBCs during deoxygenation, in proportion to the degree of Hb deoxygenation, to regulate vessels directly. In addition, we discuss how dysregulation of this system through genetic mutation in Hb or through disease is a common factor in oxygenation pathologies resulting from microcirculatory impairment, including sickle cell disease, ischemic heart disease, and heart failure. We then conclude by identifying potential therapeutic interventions to correct deficits in RBC-mediated vasodilation to improve oxygen delivery-steps toward effective microvasculature-targeted therapies. To the extent that diseases of the heart, lungs, and blood are associated with impaired tissue oxygenation, the development of new therapies based on the three-gas respiratory system have the potential to improve the well-being of millions of patients.

A Novel Method to Improve Perfusion of Ex Vivo Pumped Human Kidneys.

OBJECTIVE: To determine if addition of the S-nitrosylating agent ethyl nitrite (ENO) to the preservation solution can improve perfusion parameters in pumped human kidneys. BACKGROUND: A significant percentage of actively stored kidneys experience elevations in resistance and decreases in flow rate during the ex vivo storage period. Preclinical work indicates that renal status after brain death is negatively impacted by inflammation and reduced perfusion-processes regulated by protein S-nitrosylation. To translate these findings, we added ENO to the preservation solution in an attempt to reverse the perfusion deficits observed in nontransplanted pumped human kidneys. METHODS: After obtaining positive proof-of-concept results with swine kidneys, we studied donated human kidneys undergoing hypothermic pulsatile perfusion deemed unsuitable for transplantation. Control kidneys continued to be pumped a 4°C (ie, standard of care). In the experimental group, the preservation solution was aerated with 50 ppm ENO in nitrogen. Flow rate and perfusion were recorded for 10 hours followed by biochemical analysis of the kidney tissue. RESULTS: In controls, perfusion was constant during the monitoring period (ie, flow rate remained low and resistance stayed high). In contrast, the addition of ENO produced significant and sustained reductions in resistance and increases in flow rate. ENO-treated kidneys had higher levels of cyclic guanosine monophosphate, potentially explaining the perfusion benefits, and increased levels of interleukin-10, suggestive of an anti-inflammatory effect. CONCLUSIONS: S-Nitrosylation therapy restored the microcirculation and thus improved overall organ perfusion. Inclusion of ENO in the renal preservation solution holds promise to increase the number and quality of kidneys available for transplant.

International Classification of Retinopathy of Prematurity, Third Edition.

PURPOSE: The International Classification of Retinopathy of Prematurity is a consensus statement that creates a standard nomenclature for classification of retinopathy of prematurity (ROP). It was initially published in 1984, expanded in 1987, and revisited in 2005. This article presents a third revision, the International Classification of Retinopathy of Prematurity, Third Edition (ICROP3), which is now required because of challenges such as: (1) concerns about subjectivity in critical elements of disease classification; (2) innovations in ophthalmic imaging; (3) novel pharmacologic therapies (e.g., anti-vascular endothelial growth factor agents) with unique regression and reactivation features after treatment compared with ablative therapies; and (4) recognition that patterns of ROP in some regions of the world do not fit neatly into the current classification system. DESIGN: Review of evidence-based literature, along with expert consensus opinion. PARTICIPANTS: International ROP expert committee assembled in March 2019 representing 17 countries and comprising 14 pediatric ophthalmologists and 20 retinal specialists, as well as 12 women and 22 men. METHODS: The committee was initially divided into 3 subcommittees-acute phase, regression or reactivation, and imaging-each of which used iterative videoconferences and an online message board to identify key challenges and approaches. Subsequently, the entire committee used iterative videoconferences, 2 in-person multiday meetings, and an online message board to develop consensus on classification. MAIN OUTCOME MEASURES: Consensus statement. RESULTS: The ICROP3 retains current definitions such as zone (location of disease), stage (appearance of disease at the avascular-vascular junction), and circumferential extent of disease. Major updates in the ICROP3 include refined classification metrics (e.g., posterior zone II, notch, subcategorization of stage 5, and recognition that a continuous spectrum of vascular abnormality exists from normal to plus disease). Updates also include the definition of aggressive ROP to replace aggressive-posterior ROP because of increasing recognition that aggressive disease may occur in larger preterm infants and beyond the posterior retina, particularly in regions of the world with limited resources. ROP regression and reactivation are described in detail, with additional description of long-term sequelae. CONCLUSIONS: These principles may improve the quality and standardization of ROP care worldwide and may provide a foundation to improve research and clinical care.

Ranibizumab versus laser therapy for the treatment of very low birthweight infants with retinopathy of prematurity (RAINBOW): an open-label randomised controlled trial.

BACKGROUND: Despite increasing worldwide use of anti-vascular endothelial growth factor agents for treatment of retinopathy of prematurity (ROP), there are few data on their ocular efficacy, the appropriate drug and dose, the need for retreatment, and the possibility of long-term systemic effects. We evaluated the efficacy and safety of intravitreal ranibizumab compared with laser therapy in treatment of ROP. METHODS: This randomised, open-label, superiority multicentre, three-arm, parallel group trial was done in 87 neonatal and ophthalmic centres in 26 countries. We screened infants with birthweight less than 1500 g who met criteria for treatment for retinopathy, and randomised patients equally (1:1:1) to receive a single bilateral intravitreal dose of ranibizumab 0·2 mg or ranibizumab 0·1 mg, or laser therapy. Individuals were stratified by disease zone and geographical region using computer interactive response technology. The primary outcome was survival with no active retinopathy, no unfavourable structural outcomes, or need for a different treatment modality at or before 24 weeks (two-sided α=0·05 for superiority of ranibizumab 0·2 mg against laser therapy). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, NCT02375971. INTERPRETATION: Between Dec 31, 2015, and June 29, 2017, 225 participants (ranibizumab 0·2 mg n=74, ranibizumab 0·1 mg n=77, laser therapy n=74) were randomly assigned. Seven were withdrawn before treatment (n=1, n=1, n=5, respectively) and 17 did not complete follow-up to 24 weeks, including four deaths in each group. 214 infants were assessed for the primary outcome (n=70, n=76, n=68, respectively). Treatment success occurred in 56 (80%) of 70 infants receiving ranibizumab 0·2 mg compared with 57 (75%) of 76 infants receiving ranibizumab 0·1 mg and 45 (66%) of 68 infants after laser therapy. Using a hierarchical testing strategy, compared with laser therapy the odds ratio (OR) of treatment success following ranibizumab 0·2 mg was 2·19 (95% Cl 0·99-4·82, p=0·051), and following ranibizumab 0·1 mg was 1·57 (95% Cl 0·76-3·26); for ranibizumab 0·2 mg compared with 0·1 mg the OR was 1·35 (95% Cl 0·61-2·98). One infant had an unfavourable structural outcome following ranibizumab 0·2 mg, compared with five following ranibizumab 0·1 mg and seven after laser therapy. Death, serious and non-serious systemic adverse events, and ocular adverse events were evenly distributed between the three groups. FINDINGS: In the treatment of ROP, ranibizumab 0·2 mg might be superior to laser therapy, with fewer unfavourable ocular outcomes than laser therapy and with an acceptable 24-week safety profile. FUNDING: Novartis.

Hemoglobin ßCys93 is essential for cardiovascular function and integrated response to hypoxia.

Oxygen delivery by Hb is essential for vertebrate life. Three amino acids in Hb are strictly conserved in all mammals and birds, but only two of those, a His and a Phe that stabilize the heme moiety, are needed to carry O2. The third conserved residue is a Cys within the ß-chain (ßCys93) that has been assigned a role in S-nitrosothiol (SNO)-based hypoxic vasodilation by RBCs. Under this model, the delivery of SNO-based NO bioactivity by Hb redefines the respiratory cycle as a triune system (NO/O2/CO2). However, the physiological ramifications of RBC-mediated vasodilation are unknown, and the apparently essential nature of ßCys93 remains unclear. Here we report that mice with a ßCys93Ala mutation are deficient in hypoxic vasodilation that governs blood flow autoregulation, the classic physiological mechanism that controls tissue oxygenation but whose molecular basis has been a longstanding mystery. Peripheral blood flow and tissue oxygenation are decreased at baseline in mutant animals and decline excessively during hypoxia. In addition, ßCys93Ala mutation results in myocardial ischemia under basal normoxic conditions and in acute cardiac decompensation and enhanced mortality during transient hypoxia. Fetal viability is diminished also. Thus, ßCys93-derived SNO bioactivity is essential for tissue oxygenation by RBCs within the respiratory cycle that is required for both normal cardiovascular function and circulatory adaptation to hypoxia.

Plus Disease in Retinopathy of Prematurity: A Continuous Spectrum of Vascular Abnormality as a Basis of Diagnostic Variability.

PURPOSE: To identify patterns of interexpert discrepancy in plus disease diagnosis in retinopathy of prematurity (ROP). DESIGN: We developed 2 datasets of clinical images as part of the Imaging and Informatics in ROP study and determined a consensus reference standard diagnosis (RSD) for each image based on 3 independent image graders and the clinical examination results. We recruited 8 expert ROP clinicians to classify these images and compared the distribution of classifications between experts and the RSD. PARTICIPANTS: Eight participating experts with more than 10 years of clinical ROP experience and more than 5 peer-reviewed ROP publications who analyzed images obtained during routine ROP screening in neonatal intensive care units. METHODS: Expert classification of images of plus disease in ROP. MAIN OUTCOME MEASURES: Interexpert agreement (weighted κ statistic) and agreement and bias on ordinal classification between experts (analysis of variance [ANOVA]) and the RSD (percent agreement). RESULTS: There was variable interexpert agreement on diagnostic classifications between the 8 experts and the RSD (weighted κ, 0-0.75; mean, 0.30). The RSD agreement ranged from 80% to 94% for the dataset of 100 images and from 29% to 79% for the dataset of 34 images. However, when images were ranked in order of disease severity (by average expert classification), the pattern of expert classification revealed a consistent systematic bias for each expert consistent with unique cut points for the diagnosis of plus disease and preplus disease. The 2-way ANOVA model suggested a highly significant effect of both image and user on the average score (dataset A: P < 0.05 and adjusted R2 = 0.82; and dataset B: P < 0.05 and adjusted R2 = 0.6615). CONCLUSIONS: There is wide variability in the classification of plus disease by ROP experts, which occurs because experts have different cut points for the amounts of vascular abnormality required for presence of plus and preplus disease. This has important implications for research, teaching, and patient care for ROP and suggests that a continuous ROP plus disease severity score may reflect more accurately the behavior of expert ROP clinicians and may better standardize classification in the future.

Plus Disease in Retinopathy of Prematurity: Improving Diagnosis by Ranking Disease Severity and Using Quantitative Image Analysis.

PURPOSE: To determine expert agreement on relative retinopathy of prematurity (ROP) disease severity and whether computer-based image analysis can model relative disease severity, and to propose consideration of a more continuous severity score for ROP. DESIGN: We developed 2 databases of clinical images of varying disease severity (100 images and 34 images) as part of the Imaging and Informatics in ROP (i-ROP) cohort study and recruited expert physician, nonexpert physician, and nonphysician graders to classify and perform pairwise comparisons on both databases. PARTICIPANTS: Six participating expert ROP clinician-scientists, each with a minimum of 10 years of clinical ROP experience and 5 ROP publications, and 5 image graders (3 physicians and 2 nonphysician graders) who analyzed images that were obtained during routine ROP screening in neonatal intensive care units. METHODS: Images in both databases were ranked by average disease classification (classification ranking), by pairwise comparison using the Elo rating method (comparison ranking), and by correlation with the i-ROP computer-based image analysis system. MAIN OUTCOME MEASURES: Interexpert agreement (weighted κ statistic) compared with the correlation coefficient (CC) between experts on pairwise comparisons and correlation between expert rankings and computer-based image analysis modeling. RESULTS: There was variable interexpert agreement on diagnostic classification of disease (plus, preplus, or normal) among the 6 experts (mean weighted κ, 0.27; range, 0.06-0.63), but good correlation between experts on comparison ranking of disease severity (mean CC, 0.84; range, 0.74-0.93) on the set of 34 images. Comparison ranking provided a severity ranking that was in good agreement with ranking obtained by classification ranking (CC, 0.92). Comparison ranking on the larger dataset by both expert and nonexpert graders demonstrated good correlation (mean CC, 0.97; range, 0.95-0.98). The i-ROP system was able to model this continuous severity with good correlation (CC, 0.86). CONCLUSIONS: Experts diagnose plus disease on a continuum, with poor absolute agreement on classification but good relative agreement on disease severity. These results suggest that the use of pairwise rankings and a continuous severity score, such as that provided by the i-ROP system, may improve agreement on disease severity in the future.

S-nitrosylation therapy to improve oxygen delivery of banked blood.

From the perspectives of disease transmission and sterility maintenance, the world's blood supplies are generally safe. However, in multiple clinical settings, red blood cell (RBC) transfusions are associated with adverse cardiovascular events and multiorgan injury. Because ∼85 million units of blood are administered worldwide each year, transfusion-related morbidity and mortality is a major public health concern. Blood undergoes multiple biochemical changes during storage, but the relevance of these changes to unfavorable outcomes is unclear. Banked blood shows reduced levels of S-nitrosohemoglobin (SNO-Hb), which in turn impairs the ability of stored RBCs to effect hypoxic vasodilation. We therefore reasoned that transfusion of SNO-Hb-deficient blood may exacerbate, rather than correct, impairments in tissue oxygenation, and that restoration of SNO-Hb levels would improve transfusion efficacy. Notably in mice, administration of banked RBCs decreased skeletal muscle pO2, but infusion of renitrosylated cells maintained tissue oxygenation. In rats, hemorrhage-induced reductions in muscle pO2 were corrected by SNO-Hb-repleted RBCs, but not by control, stored RBCs. In anemic awake sheep, stored renitrosylated, but not control RBCs, produced sustained improvements in O2 delivery; in anesthetized sheep, decrements in hemodynamic status, renal blood flow, and kidney function incurred following transfusion of banked blood were also prevented by renitrosylation. Collectively, our findings lend support to the idea that transfusions may be causally linked to ischemic events and suggest a simple approach to prevention (i.e., SNO-Hb repletion). If these data are replicated in clinical trials, renitrosylation therapy could have significant therapeutic impact on the care of millions of patients.

Ranibizumab versus laser therapy for the treatment of very low birthweight infants with retinopathy of prematurity (RAINBOW): five-year outcomes of a randomised trial.

Background: Concerns remain over the long-term safety of vascular endothelial growth factor (VEGF) inhibitors to treat retinopathy of prematurity (ROP). RAINBOW is an open label randomised trial comparing intravitreal ranibizumab (in 0.2 mg and 0.1 mg doses) with laser therapy in very low birthweight infants (<1500 g) with ROP. Methods: Of 201 infants completing RAINBOW, 180 were enrolled in the RAINBOW Extension Study. At 5 years, children underwent ophthalmic, development and health assessments. The primary outcome was visual acuity in the better-seeing eye. The study is registered with ClinicalTrial.gov, NCT02640664. Findings: Between 16-6-2016 and 21-4-2022, 156 children (87%) were evaluated at 5 years. Of 32 children with no acuity test result, 25 had a preferential looking test, for 4 children investigators reported low vision for each eye, and in 3 further children no vision measurement was obtained. 124 children completed the acuity assessment, the least square mean (95% CI) letter score in the better seeing eye was similar in the three trial arms-66.8 (62.9-70.7) following ranibizumab 0.2 mg, 64.6 (60.6-68.5) following ranibizumab 0.1 mg and 62.1 (57.8-66.4) following laser therapy; differences in means: ranibizumab 0.2 mg v laser: 4.7 (95% CI: -1.1, 10.5); 0.1 mg v laser: 2.5 (-3.4, 8.3); 0.2 mg v 0.1 mg: 2.2 (-3.3, 7.8). High myopia (worse than -5 dioptres) in at least one eye occurred in 4/52 (8%) children following ranibizumab 0.2 mg, 8/55 (15%) following ranibizumab 0.1 mg and 11/45 (24%) following laser therapy (0.2 mg versus laser: odds ratio: 3.99 (1.16-13.72)). Ocular and systemic secondary outcomes and adverse events were distributed similarly in each trial arm. Interpretation: 5-year outcomes confirm the findings of the original RAINBOW trial and a planned interim analysis at 2 years, including a reduced frequency of high myopia following ranibizumab treatment. No effects of treatment on non-ocular outcomes were detected. Funding: Novartis Pharma AG.

Renal dysfunction in adults following cardiopulmonary bypass is linked to declines in S-nitroso hemoglobin: a case series.

Background: Impaired kidney function is frequently observed in patients following cardiopulmonary bypass (CPB). Our group has previously linked blood transfusion to acute declines in S-nitroso haemoglobin (SNO-Hb; the main regulator of tissue oxygen delivery), reductions in intraoperative renal blood flow, and postoperative kidney dysfunction. While not all CPB patients receive blood, kidney injury is still common. We hypothesized that the CPB procedure itself may negatively impact SNO-Hb levels leading to renal dysfunction. Materials and methods: After obtaining written informed consent, blood samples were procured immediately before and after CPB, and on postoperative day (POD) 1. SNO-Hb levels, renal function (estimated glomerular filtration rate; eGFR), and plasma erythropoietin (EPO) concentrations were quantified. Additional outcome data were extracted from the patients' medical records. Results: Twenty-seven patients were enroled, three withdrew consent, and one was excluded after developing bacteremia. SNO-Hb levels declined after surgery and were directly correlated with declines in eGFR (R=0.48). Conversely, plasma EPO concentrations were elevated and inversely correlated with SNO-Hb (R=-0.53) and eGFR (R=-0.55). Finally, ICU stay negatively correlated with SNO-Hb concentration (R=-0.32). Conclusion: SNO-Hb levels are reduced following CPB in the absence of allogenic blood transfusion and are predictive of decreased renal function and prolonged ICU stay. Thus, therapies directed at maintaining or increasing SNO-Hb levels may improve outcomes in adult patients undergoing cardiac surgery.

Repletion of S-nitrosohemoglobin improves organ function and physiological status in swine after brain death.

OBJECTIVE: To determine if reduction in nitric oxide bioactivity contributes to the physiological instability that occurs after brain death and, if so, to also determine in this setting whether administration of a renitrosylating agent could improve systemic physiological status. BACKGROUND: Organ function after brain death is negatively impacted by reduced perfusion and increased inflammation; the magnitude of these responses can impact post-graft function. Perfusion and inflammation are normally regulated by protein S-nitrosylation but systemic assessments of nitric oxide bioactivity after brain death have not been performed. METHODS: Brain death was induced in instrumented swine by inflation of a balloon catheter placed under the cranium. The subjects were then serially assigned to receive either standard supportive care or care augmented by 20 ppm of the nitrosylating agent, ethyl nitrite, blended into the ventilation circuit. RESULTS: Circulating nitric oxide bioactivity (in the form of S-nitrosohemoglobin) was markedly diminished 10 hours after induction of brain death-a decline that was obviated by administration of ethyl nitrite. Maintenance of S-nitrosohemoglobin was associated with improvements in tissue blood flow and oxygenation, reductions in markers of immune activation and cellular injury, and preservation of organ function. CONCLUSIONS: In humans, the parameters monitored in this study are predictive of post-graft function. As such, maintenance of endocrine nitric oxide bioactivity after brain death may provide a novel means to improve the quality of organs available for donation.

Determination of Unnecessary Blood Transfusion by Comprehensive 15-Hospital Record Review.

BACKGROUND: Although unnecessary blood component transfusions are costly and pose substantial patient risks, the extent of unnecessary blood use in a community hospital setting has not been systematically measured. METHODS: A 15-hospital observational analysis was performed using comprehensive retrospective review. Approximately 100 encounters (x¯â€¯= 103.9, standard deviation [SD] ± 7.6) per hospital (6,696 total component transfusion events) were reviewed between 2012 and 2018. Review was performed by two medical directors. Findings were supported by blind intra- and inter-reviewer double review and blind external review by 10 independent reviewers. RESULTS: Patients received an average of 4.3 (± 1.3) units. Only 8.2% (± 6.7) of patient encounters did not receive unnecessary units. Fifty-five percent (54.6% ± 13.5) could have been managed without at least one component type, while 44.6% (± 14.9) could have been managed completely without transfusion. Forty-five percent (45.4% ± 17.0) of red blood cell, 54.9% (± 19.3) of plasma-cryoprecipitate, and 38.0% (± 15.6) of plateletpheresis encounters could likely have been managed without transfusion. Between 2,713 units (40.5%) and 3,306 units (49.4%) were likely unnecessary. In patients who could have been managed without transfusion of at least one component type, unnecessary blood use was associated with a 0.38 (± 0.11)-day increase in length of hospital stay for each additional unnecessary unit received (p < 0.001). CONCLUSION: Substantial unnecessary blood use was identified, all of which was unrecognized by hospitals prior to review. Unnecessary blood use was attributed to overreliance on laboratory transfusion criteria and failure to follow common blood management principles, which resulted in potential harm to patients and avoidable cost.