Key Points• Hb-conformation-dependent interaction with band 3 protein regulates glycolysis in RBCs.• In hypoxia, HbS disrupts this system, disabling RBC antioxidant defense. Energy metabolism in RBCs is characterized by O 2 -responsive variations in flux through the Embden Meyerhof pathway (EMP) or the hexose monophosphate pathway (HMP). Therefore, the generation of ATP, NADH, and 2,3-DPG (EMP) or NADPH (HMP) shift with RBC O 2 content because of competition between deoxyhemoglobin and key EMP enzymes for binding to the cytoplasmic domain of the Band 3 membrane protein (cdB3). Enzyme inactivation by cdB3 sequestration in oxygenated RBCs favors HMP flux and NADPH generation (maximizing glutathione-based antioxidant systems). We tested the hypothesis that sickle hemoglobin disrupts cdB3-based regulatory protein complex assembly, creating vulnerability to oxidative stress. In RBCs from patients with sickle cell anemia, we demonstrate in the present study constrained HMP flux, NADPH, and glutathione recycling and reduced resilience to oxidative stress manifested by membrane protein oxidation and membrane fragility. Using a novel, inverted membrane-on-bead model, we illustrate abnormal (O 2 -dependent) association of sickle hemoglobin to RBC membrane that interferes with sequestration/inactivation of the EMP enzyme GAPDH. This finding was confirmed by immunofluorescent imaging during RBC O IntroductionSickle cell anemia (SCA) arises from a single amino acid substitution (Glu6Val) in the ␤-globin chain. Although the change to hemoglobin (Hb) is simple and uniform, SCA is characterized by broad differences in clinical manifestation. Phenotype variation in SCA is thought to arise from both environmental and genetic factors (eg, ␤-gene cluster haplotype, degree of HbF expression, or effects of other epistatic genes). The environmental factor that most clearly influences SCA phenotype is hypoxia, which drives sickle Hb (HbS) polymerization and the resulting well-characterized alterations in RBC physiology and the microcirculation. However, the influence of hypoxia on the SCA phenotype appears to be insufficiently explained by HbS polymerization alone. 1 Moreover, we lack a clear mechanistic understanding of the significant oxidative stress complicating SCA, a key feature of phenotype variation, both at rest and in association with hypoxia. 2 Nonpolymerized, solution-phase HbS may promote oxidative stress, even in RBCs under normal physiologic O 2 gradients. 3 Specifically, the low redox potential for heme in HbS 4 and avid binding affinity of HbS for the cytoplasmic regulatory domain of the Band 3 membrane protein (cdB3) 5,6 strongly affect RBC energetics and antioxidant systems [7][8][9] and, notably, do so as a function of RBC O 2 content. Therefore, both the genesis and the disposal of reactive oxygen species are abnormal in SCA, creating a baseline state of oxidative stress, which worsens in hypoxia.In particular, consideration of metabolic control in RBCs suggests O 2 -dependent HbS-cdB3 interaction as a relatively ...

ImportanceIncreasing evidence indicates that acute kidney injury (AKI) occurs frequently in children and young adults and is associated with poor short-term and long-term outcomes. Guidance is required to focus efforts related to expansion of pediatric AKI knowledge.ObjectiveTo develop expert-driven pediatric specific recommendations on needed AKI research, education, practice, and advocacy.Evidence ReviewAt the 26th Acute Disease Quality Initiative meeting conducted in November 2021 by 47 multiprofessional international experts in general pediatrics, nephrology, and critical care, the panel focused on 6 areas: (1) epidemiology; (2) diagnostics; (3) fluid overload; (4) kidney support therapies; (5) biology, pharmacology, and nutrition; and (6) education and advocacy. An objective scientific review and distillation of literature through September 2021 was performed of (1) epidemiology, (2) risk assessment and diagnosis, (3) fluid assessment, (4) kidney support and extracorporeal therapies, (5) pathobiology, nutrition, and pharmacology, and (6) education and advocacy. Using an established modified Delphi process based on existing data, workgroups derived consensus statements with recommendations.FindingsThe meeting developed 12 consensus statements and 29 research recommendations. Principal suggestions were to address gaps of knowledge by including data from varying socioeconomic groups, broadening definition of AKI phenotypes, adjudicating fluid balance by disease severity, integrating biopathology of child growth and development, and partnering with families and communities in AKI advocacy.Conclusions and RelevanceExisting evidence across observational study supports further efforts to increase knowledge related to AKI in childhood. Significant gaps of knowledge may be addressed by focused efforts.

Continuous renal replacement therapy is the most common modality of renal replacement in the critical care setting. Regional anticoagulation is an ideal option in a critically ill child after recent surgery or with coagulopathy. Therefore, regional citrate anticoagulation in the pediatric critical care population requiring renal replacement therapy is commonly employed. Complications of citrate anticoagulation can be avoided with a greater understanding of the properties and clearance of citrate. Continued reporting of observational data and the development of prospective multicenter trials using citrate anticoagulation are needed to ensure safe and standardized care in the pediatric population.

Background: The use of peritoneal catheters for prophylactic dialysis or drainage to prevent fluid overload after neonatal cardiac surgery is common in some centres; however, the multi-centre variability and details of peritoneal catheter use are not well described. Methods: Twenty-two-centre NEonatal and Pediatric Heart Renal Outcomes Network (NEPHRON) study to describe multi-centre peritoneal catheter use after STAT category 3–5 neonatal cardiac surgery using cardiopulmonary bypass. Patient characteristics and acute kidney injury/fluid outcomes for six post-operative days are described among three cohorts: peritoneal catheter with dialysis, peritoneal catheter with passive drainage, and no peritoneal catheter. Results: Of 1490 neonates, 471 (32%) had an intraoperative peritoneal catheter placed; 177 (12%) received prophylactic dialysis and 294 (20%) received passive drainage. Sixteen (73%) centres used peritoneal catheter at some frequency, including six centres in >50% of neonates. Four centres utilised prophylactic peritoneal dialysis. Time to post-operative dialysis initiation was 3 hours [1, 5] with the duration of 56 hours [37, 90]; passive drainage cohort drained for 92 hours [64, 163]. Peritoneal catheter were more common among patients receiving pre-operative mechanical ventilation, single ventricle physiology, and higher complexity surgery. There was no association with adverse events. Serum creatinine and daily fluid balance were not clinically different on any post-operative day. Mortality was similar. Conclusions: In neonates undergoing complex cardiac surgery, peritoneal catheter use is not rare, with substantial variability among centres. Peritoneal catheters are used more commonly with higher surgical complexity. Adverse event rates, including mortality, are not different with peritoneal catheter use. Fluid overload and creatinine-based acute kidney injury rates are not different in peritoneal catheter cohorts.

Pulmonary hemorrhage is a rare but potentially fatal condition in children. Previously described therapeutic approaches include high-frequency oscillation ventilation and extracorporeal membrane oxygenation. Infants with pulmonary hemorrhage and respiratory distress may benefit from a trial of surfactant before escalating care.