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.

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.

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.

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.

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.

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.

S-Nitrosylated hemoglobin predicts organ yield in neurologically-deceased human donors.

Current human donor care protocols following death by neurologic criteria (DNC) can stabilize macro-hemodynamic parameters but have minimal ability to preserve systemic blood flow and microvascular oxygen delivery. S-nitrosylated hemoglobin (SNO-Hb) within red blood cells (RBCs) is the main regulator of tissue oxygenation (StO2). Based on various pre-clinical studies, we hypothesized that brain death (BD) would decrease post-mortem SNO-Hb levels to negatively-impact StO2 and reduce organ yields. We tracked SNO-Hb and tissue oxygen in 61 DNC donors. After BD, SNO-Hb levels were determined to be significantly decreased compared to healthy humans (p = 0·003) and remained reduced for the duration of the monitoring period. There was a positive correlation between SNO-Hb and StO2 (p < 0.001). Furthermore, SNO-Hb levels correlated with and were prognostic for the number of organs transplanted (p < 0.001). These clinical findings provide additional support for the concept that BD induces a systemic impairment of S-nitrosylation that negatively impacts StO2 and reduces organ yield from DNC human donors. Exogenous S-nitrosylating agents are in various stages of clinical development. The results presented here suggest including one or more of these agents in donor support regimens could increase the number and quality of organs available for transplant.

Time Course of Retinopathy of Prematurity Regression and Reactivation After Treatment with Ranibizumab or Laser in the RAINBOW Trial.

PURPOSE: To study the time course of retinopathy of prematurity (ROP) regression and reactivation after treatment with intravitreal ranibizumab or laser in the ranibizumab compared with laser therapy for the treatment of infants born prematurely with ROP trial. DESIGN: Post hoc analysis of a randomized, clinical trial. SUBJECTS: A total of 225 infants (448 eyes) were randomized to ranibizumab 0.2 mg (n = 74, 148 eyes), ranibizumab 0.1 mg (n = 77, 152 eyes), and laser (n = 74, 148 eyes). METHODS: Features of disease regression were measured using time-to-event analysis per eye, corrected for within-subject association. Analyses of disease reactivation and additional treatments were descriptive. MAIN OUTCOME MEASURES: Median time to regression of plus disease, stage 3 ROP, aggressive posterior (AP)-ROP to 24-week follow-up and disease reactivation and first additional treatment to 2-year follow-up. RESULTS: The median times to regression after ranibizumab 0.2 mg vs. laser were as follows: plus disease, 4 vs. 16 days (P < 0.001); stage 3 ROP, 8 vs. 16 days (P = 0.004); and AP-ROP, 7.3 vs. 22 days (P = 0.03). Results for ranibizumab 0.1 mg were similar to those for 0.2 mg, with a median of 4, 9, and 8 days, respectively. Additional treatments were given in 34 (25%) of 138 eyes after laser and 40 (27%) of 146 and 42 (28%) of 152 eyes after 0.2 mg and 0.1 mg ranibizumab, respectively. Incomplete disease regression requiring additional treatment occurred in 30 (22%) of 138 eyes after laser after a median interval of 15 days compared with 11 (8%) of 146 and 9 (6%) of 152 after 0.2 mg and 0.1 mg ranibizumab after a median interval of 21 and 13 days, respectively. Retinopathy of prematurity reactivation requiring additional treatment occurred in 3 (2%) of 138 eyes after laser after a median interval of 43 days compared with 22 (15%) of 146 and 26 (17%) of 152 after 0.2 and 0.1 mg ranibizumab after a median interval of 53.5 (maximum, 105) and 54.5 days (maximum, 128), respectively. CONCLUSIONS: Intravitreal 0.2 or 0.1 mg ranibizumab induced a faster regression of plus disease, stage 3 ROP, and AP-ROP than laser did. Ranibizumab was associated with fewer additional treatments for incomplete disease regression but more for disease reactivation.

Airway Thiol-NO Adducts as Determinants of Exhaled NO.

Thiol-NO adducts such as S-nitrosoglutathione (GSNO) are endogenous bronchodilators in human airways. Decreased airway S-nitrosothiol concentrations are associated with asthma. Nitric oxide (NO), a breakdown product of GSNO, is measured in exhaled breath as a biomarker in asthma; an elevated fraction of expired NO (FENO) is associated with asthmatic airway inflammation. We hypothesized that FENO could reflect airway S-nitrosothiol concentrations. To test this hypothesis, we first studied the relationship between mixed expired NO and airway S-nitrosothiols in patients endotracheally intubated for respiratory failure. The inverse (Lineweaver-Burke type) relationship suggested that expired NO could reflect the rate of pulmonary S-nitrosothiol breakdown. We thus studied NO evolution from the lungs of mice (GSNO reductase -/-) unable reductively to catabolize GSNO. More NO was produced from GSNO in the -/- compared to wild type lungs. Finally, we formally tested the hypothesis that airway GSNO increases FENO using an inhalational challenge model in normal human subjects. FENO increased in all subjects tested, with a median t1/2 of 32.0 min. Taken together, these data demonstrate that FENO reports, at least in part, GSNO breakdown in the lungs. Unlike GSNO, NO is not present in the lungs in physiologically relevant concentrations. However, FENO following a GSNO challenge could be a non-invasive test for airway GSNO catabolism.

2-year outcomes of ranibizumab versus laser therapy for the treatment of very low birthweight infants with retinopathy of prematurity (RAINBOW extension study): prospective follow-up of an open label, randomised controlled trial.

BACKGROUND: Intravitreal injection of vascular endothelial growth factor (VEGF) inhibitors is increasingly used to treat retinopathy of prematurity (ROP) in the absence of evidence about long-term efficacy or safety. In this prespecified interim analysis of the RAINBOW extension study, we aimed to prospectively assess outcomes at age 2 years. METHODS: RAINBOW was an open-label, randomised trial that compared intravitreal ranibizumab (at 0·1 mg and 0·2 mg doses) with laser therapy for the treatment of ROP in very low birthweight infants (<1500 g). Families of the 201 infants that completed the RAINBOW core study were approached for consent to enter the extension study, which evaluates treatment outcomes prospectively through to 5 years of age. At age 20-28 months corrected for prematurity, participants had ophthalmic, development, and health assessments. The primary outcome was the absence of structural ocular abnormalities; secondary outcomes included vision-related quality of life (reported by parents using the Children's Visual Function Questionnaire), development (assessed with the Mullen Scales of Early Learning), motor function, and health status. Investigator-determined ocular and non-ocular serious and other adverse events were recorded. This study is registered with ClinicalTrials.gov, NCT02640664. FINDINGS: Between June 16, 2016, and Jan 22, 2018, 180 infants were enrolled in the RAINBOW extension study, and 153 (85%) were evaluated at 20-28 months of age. No child developed new ocular structural abnormalities. Structural abnormalities were present in one (2%) of 56 infants in the ranibizumab 0·2 mg group, one (2%) of 51 infants in the 0·1 mg group, and four (9%) of 44 infants in the laser therapy group. The odds ratio of no structural abnormality was 5·68 (95% CI 0·60-54·0; p=0·10) for ranibizumab 0·2 mg versus laser therapy, 4·82 (0·52-45·0; p=0·14) for ranibizumab 0·1 mg versus laser therapy, and 1·21 (0·07-20; p=0·90) for ranibizumab 0·2 mg vs 0·1 mg. High myopia (-5 dioptres or worse) was less frequent after 0·2 mg ranibizumab (five [5%] of 110 eyes) than with laser therapy (16 [20%] of 82; odds ratio 0·19, 95% CI 0·05-0·69; p=0·012). Composite vision-related quality of life scores seemed higher among the ranibizumab 0·2 mg group (mean 84, 95% CI 80-88) compared with laser therapy (77, 72-83; p=0·063). Mullen Scales T-scores for visual reception, receptive and expressive language were distributed similarly between the three trial groups and there were similar proportions of infants with motor and hearing problems among treatment groups. The proportion of infants with respiratory symptoms and Z scores of standing height, weight, and head circumference were similarly distributed in the treatment groups. There were no adverse events considered by the investigator to be related to the study intervention. INTERPRETATION: 2-year outcomes following ranibizumab 0·2 mg for the treatment of ROP confirm the ocular outcomes of the original RAINBOW trial and show reduced high myopia, with possibly better vision-related quality of life. This treatment did not appear to affect non-ocular infant development. FUNDING: Novartis Pharma AG.

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.

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.

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.

Red Blood Cell-Mediated S-Nitrosohemoglobin-Dependent Vasodilation: Lessons Learned from a ß-Globin Cys93 Knock-In Mouse.

Significance: Red blood cell (RBC)-mediated vasodilation plays an important role in oxygen delivery. This occurs through hemoglobin actions, at least in significant part, to convert heme-bound nitric oxide (NO) (in tense [T]/deoxygenated-state hemoglobin) into vasodilator S-nitrosothiol (SNO) (in relaxed [R]/oxygenated-state hemoglobin), convey SNO through the bloodstream, and release it into tissues to increase blood flow. The coupling of hemoglobin R/T state allostery, both to NO conversion into SNO and to SNO release (along with oxygen), under hypoxia supports the model of a three-gas respiratory cycle (O2/NO/CO2). Recent Advances: Oxygenation of tissues is dependent on a single, strictly conserved Cys residue in hemoglobin (ßCys93). Hemoglobin couples SNO formation/release at ßCys93 to O2 binding/release at hemes ("thermodynamic linkage"). Mice bearing ßCys93Ala hemoglobin that is unable to generate SNO-ßCys93 establish that SNO-hemoglobin is important for R/T allostery-regulated vasodilation by RBCs that couple blood flow to tissue oxygenation. Critical Issues: The model for RBC-mediated vasodilation originally proposed by Stamler et al. in 1996 has been largely validated: SNO-ßCys93 forms in vivo, dilates blood vessels, and is hypoxia-regulated, and RBCs actuate vasodilation proportionate to hypoxia. Numerous compensations in ßCys93Ala animals to alleviate tissue hypoxia (discussed herein) are predicted to preserve vasodilatory responses of RBCs but impair linkage to R/T transition in hemoglobin. This is borne out by loss of responsivity of mutant RBCs to oxygen, impaired blood flow responses to hypoxia, and tissue ischemia in ßCys93-mutant animals. Future Directions: SNO-hemoglobin mediates hypoxic vasodilation in the respiratory cycle. This fundamental physiology promises new insights in vascular diseases and blood 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.

Ranibizumab Population Pharmacokinetics and Free VEGF Pharmacodynamics in Preterm Infants With Retinopathy of Prematurity in the RAINBOW Trial.

Purpose: To develop a population pharmacokinetic (PK) model for intravitreal ranibizumab in infants with retinopathy of prematurity (ROP) and assess plasma free vascular endothelial growth factor (VEGF) pharmacodynamics (PD). Methods: The RAnibizumab compared with laser therapy for the treatment of INfants BOrn prematurely With retinopathy of prematurity (RAINBOW) trial enrolled 225 infants to receive a bilateral intravitreal injection of ranibizumab 0.1 mg, ranibizumab 0.2 mg, or laser in a 1:1:1 ratio and included sparse sampling of blood for population PK and PD analysis. An adult PK model using infant body weight as a fixed allometric covariate was re-estimated using the ranibizumab concentrations in the preterm population. Different variability, assumptions, and covariate relationships were explored. Model-based individual predicted concentrations of ranibizumab were plotted against observed free VEGF concentrations. Results: Elimination of ranibizumab had a median half-life of 5.6 days from the eye and 0.3 days from serum, resulting in an apparent serum half-life of 5.6 days. Time to reach maximum concentration was rapid (median: 1.3 days). Maximum concentration (median 24.3 ng/mL with ranibizumab 0.2 mg) was higher than that reported in adults. No differences in plasma free VEGF concentrations were apparent between the groups or over time. Plotted individual predicted concentrations of ranibizumab against observed free VEGF concentrations showed no relationship. Conclusions: In preterm infants with ROP, elimination of ranibizumab from the eye was the rate-limiting step and was faster compared with adults. No reduction in plasma free VEGF was observed. The five-year clinical safety follow-up from RAINBOW is ongoing. Translational Relevance: Our population PK and VEGF PD findings suggest a favorable ocular efficacy: systemic safety profile for ranibizumab in preterm infants.

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.

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.