Oxygen radical disease in the newborn, revisited: Oxidative stress and disease in the newborn period

Paeoniflorin protects 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease mice by inhibiting oxidative stress and neuronal apoptosis through activating the Nrf2/HO-1 signaling pathway

OBJECTIVES

This study aimed to explore the neuroprotective effects of paeoniflorin on oxidative stress and apoptosis in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mice.

METHODS

The effects of paeoniflorin on motor function in mice were evaluated by behavioral test. Then substantia nigra of mice were collected and neuronal damage was assessed using Nissl staining. Positive expression of tyrosine hydroxylase (TH) was detected by immunohistochemistry. Levels of malondialdehyde, superoxide dismutase (SOD) and glutathione were measured by biochemical method. terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay was used to detect apoptosis of dopaminergic neurons. Western blotting and real-time fluorescence quantitative PCR were used to detect the protein and mRNA expressions of Nrf2, heme oxygenase-1 (HO-1), B-cell lymphoma-2(Bcl-2), Bax and cleaved caspase-3.

RESULTS

Paeoniflorin treatment significantly ameliorated the motor performance impairment in MPTP-induced PD mice. Moreover, it notably increased the positive expression rate of TH and reduced the damage and apoptosis of dopaminergic neurons in the substantia nigra. Furthermore, paeoniflorin increased the levels of SOD and glutathione and decreased the malondialdehyde content. It also promoted Nrf2 nuclear translocation, increased the protein and mRNA expressions of HO-1 and Bcl-2 and reduced the protein and mRNA expressions of BCL2-Associated X2 (Bax) and cleaved caspase-3. Treatment with the Nrf2 inhibitor, ML385, notably reduced the effects of paeoniflorin in MPTP-induced PD mice.

CONCLUSIONS

Neuroprotective effects of paeoniflorin in MPTP-induced PD mice may be mediated via inhibition of oxidative stress and apoptosis of dopaminergic neurons in substantia nigra through activation of the Nrf2/HO-1 signaling pathway.

Influence of Defatting and Pasteurization on Nutrients and Oxidative Stress Markers in Human Milk

BACKGROUND

It is well known that the best nutritional option for infants is human milk, and that when breastfeeding is not possible, human milk banks are a possible alternative. However, in the case of infants with fat transport disorder like chylothorax, defatting of human milk is mandatory.

RESEARCH AIM

The aim of the study was to reduce milk fat content without reducing other nutrients, increasing oxidative stress, or introducing harmful microorganisms.

METHODS

In this prospective, cross-sectional, observational study, we examined the influence of defatting and pasteurization of 50 donor samples on fat, macro- and micronutrients, as well as on oxidative stress markers.

RESULTS

Low-temperature centrifugation proved to be very efficient in defatting, reducing the concentration of triglycerides by 85% and cholesterol by 50%. The macronutrients (proteins, albumin, and Immunoglobulin A) did not undergo significant changes due to defatting and pasteurization procedures, while iron decreased by 36%. However, as the majority of iron is retained, this result does not remarkably change the milk composition. Furthermore, oxidative stress markers and antioxidant levels were unchanged, and the milk result was microbiologically safe.

CONCLUSIONS

Cold milk centrifugation proved to be an effective technique that allows the reduction of human milk lipids. The determination of triglycerides and cholesterol can be used as an indicator of skimming. This procedure is not accompanied by substantial modifications of other components present in the milk.

Randomized Trial of 21% versus 100% Oxygen during Chest Compressions Followed by Gradual versus Abrupt Oxygen Titration after Return of Spontaneous Circulation in Neonatal Lambs

The combination of perinatal acidemia with postnatal hyperoxia is associated with a higher incidence of hypoxic-ischemic encephalopathy (HIE) in newborn infants. In neonatal cardiac arrest, current International Liaison Committee on Resuscitation (ILCOR) and Neonatal Resuscitation Program (NRP) guidelines recommend increasing inspired O2 to 100% during chest compressions (CC). Following the return of spontaneous circulation (ROSC), gradual weaning from 100% O2 based on pulse oximetry (SpO2) can be associated with hyperoxia and risk for cerebral tissue injury owing to oxidative stress. We hypothesize that compared to gradual weaning from 100% O2 with titration based on preductal SpO2, abrupt or rapid weaning of inspired O2 to 21% after ROSC or use of 21% O2 during CC followed by upward titration of inspired O2 to achieve target SpO2 after ROSC will limit hyperoxia after ROSC. Nineteen lambs were randomized before delivery and asphyxial arrest was induced by umbilical cord occlusion. There was no difference in oxygenation during chest compressions between the three groups. Gradual weaning of inspired O2 from 100% O2 after ROSC resulted in supraphysiological PaO2 and higher cerebral oxygen delivery compared to 21% O2 during CC or 100% O2 during CC followed by abrupt weaning to 21% O2 after ROSC. The use of 21% O2 during CC was associated with very low PaO2 after ROSC and higher brain tissue lactic acid compared to other groups. Our findings support the current recommendations to use 100% O2 during CC and additionally suggest the benefit of abrupt decrease in inspired oxygen to 21% O2 after ROSC. Clinical studies are warranted to investigate optimal oxygen titration after chest compressions and ROSC during neonatal resuscitation.

Relationship between large and small for gestational age and hospital readmission after postpartum discharge: a population-based, data-linkage study

This study aims to determine the association of small for gestational age (SGA) and large for gestational age (LGA) at birth with hospital readmission after postpartum discharge for up to 28 days of delivery. This is a population-based, data-linkage study using the French National Uniform Hospital Discharge Database. "Healthy" singleton term infants born between January 1st, 2017, and November 30th, 2018, in the French South region were included. SGA and LGA were defined as birth weight < 10th and > 90th percentiles, respectively, according to sex and gestational age. A multivariable regression analysis was performed. Among 67,359 included infants, 2441 (3.6%) were readmitted, and 61% of them were hospitalized within 14 days postpartum. Hospitalized infants were more likely to be LGA at birth (10.3% vs. 8.6% in non-hospitalized infants, p < 0.01); the proportion of SGA infants did not differ between both groups. Compared to appropriate birth weight for GA (AGA) infants, LGA infants were more often hospitalized for infectious diseases (57.7% vs. 51.3%, p = 0.05). After regression analysis, LGA infants had a 20% higher odds of being hospitalized than those born AGA (aOR (95%CI) = 1.21 (1.06-1.39)), while aOR (95%CI) for SGA was 1.11 (0.96-1.28).

CONCLUSION

 In contrast to SGA, LGA was associated with hospital readmission during the first month of life. Follow-up protocols that include LGA should be evaluated.

WHAT IS KNOWN

• Newborns are at high risk of hospital readmission during the postpartum period. • However, the influence of appropriateness for gestational age at birth, i.e. being born small for gestational age (SGA) or large for gestational age (LGA), has been little evaluated.

WHAT IS NEW

• In contrast to SGA born infants, we found that infants born LGA were at high risk of hospital admission and the main cause was infectious diseases. • This population should be considered at risk of early adverse outcomes and should require attentive medical follow-up after postpartum discharge.

Association of Funisitis with Short-Term Outcomes of Prematurity: A Frequentist and Bayesian Meta-Analysis

The fetal systemic inflammatory response associated with intra-amniotic inflammation may play a key role in the pathogenesis of complications of preterm birth. Funisitis is the histologic equivalent of the fetal inflammatory response, whereas chorioamnionitis represents a maternal inflammatory response. We conducted a frequentist and Bayesian model average (BMA) meta-analysis of studies investigating the effects of funisitis on short-term outcomes of prematurity. Thirty-three studies (12,237 infants with gestational age ≤ 34 weeks) were included. Frequentist meta-analysis showed that funisitis was associated with an increased risk of any bronchopulmonary dysplasia (BPD), moderate/severe BPD, retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), any sepsis, early-onset sepsis (EOS), and mortality. However, Bayesian meta-analysis showed that the evidence in favor of the alternative hypothesis (i.e., funisitis is associated with an increased risk of developing the outcome) was strong for any IVH, moderate for severe IVH and EOS, and weak for the other outcomes. When the control group was restricted to infants having chorioamnionitis without funisitis, the only outcome associated with funisitis was any IVH. In conclusion, our data suggest that the presence of funisitis does not add an additional risk to preterm birth when compared to chorioamnionitis in the absence of fetal inflammatory response.

Neonatal intensive care admission for term neonates and subsequent childhood mortality: a retrospective linkage study

BACKGROUND

Neonatal intensive care unit (NICU) admission among term neonates is a rare event. The aim of this study was to study the association of the NICU admission of term neonates on the risk of long-term childhood mortality.

METHODS

A single-center case-control retrospective study between 2005 and 2019, including all in-hospital ≥ 37 weeks' gestation singleton live-born neonates. The center perinatal database was linked with the birth and death certificate registries of the Israeli Ministry of Internal Affairs. The primary aim of the study was to study the association between NICU admission and childhood mortality throughout a 15-year follow-up period.

RESULTS

During the study period, 206,509 births were registered; 192,527 (93.22%) term neonates were included in the study; 5292 (2.75%) were admitted to NICU. Throughout the follow-up period, the mortality risk for term neonates admitted to the NICU remained elevated; hazard ratio (HR), 19.72 [14.66, 26.53], (p < 0.001). For all term neonates, the mortality rate was 0.16% (n = 311); 47.9% (n = 149) of those had records of a NICU admission. The mortality rate by time points (ratio_1:10,0000 births) related to the age at death during the follow-up period was as follows: 29, up to 7 days; 20, 7-28 days; 37, 28 days to 6 months; 21, 6 months to 1 year; 19, 1-2 years; 9, 2-3 years; 10, 3-4 years; and 27, 4 years and more. Following the exclusion of congenital malformations and chromosomal abnormalities, NICU admission remained the most significant risk factor associated with mortality of the study population, HRs, 364.4 [145.3; 913.3] for mortality in the first 7 days of life; 19.6 [12.1; 32.0] for mortality from 28 days through 6 months of life and remained markedly elevated after age 4 years; HR, 7.1 [3.0; 17.0]. The mortality risk related to the NICU admission event, adjusted for admission diagnoses remained significant; HR = 8.21 [5.43; 12.4].

CONCLUSIONS

NICU admission for term neonates is a pondering event for the risk of long-term childhood mortality. This group of term neonates may benefit from focused health care.

Molecular mechanisms of cell death in bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) in neonates is the most common pulmonary disease that causes neonatal mortality, has complex pathogenesis, and lacks effective treatment. It is associated with chronic obstructive pulmonary disease, pulmonary hypertension, and right ventricular hypertrophy. The occurrence and development of BPD involve various factors, of which premature birth is the most crucial reason for BPD. Under the premise of abnormal lung structure and functional product, newborns are susceptible to damage to oxides, free radicals, hypoxia, infections and so on. The most influential is oxidative stress, which induces cell death in different ways when the oxidative stress balance in the body is disrupted. Increasing evidence has shown that programmed cell death (PCD), including apoptosis, necrosis, autophagy, and ferroptosis, plays a significant role in the molecular and biological mechanisms of BPD and the further development of the disease. Understanding the mode of PCD and its signaling pathways can provide new therapeutic approaches and targets for the clinical treatment of BPD. This review elucidates the mechanism of BPD, focusing on the multiple types of PCD in BPD and their molecular mechanisms, which are mainly based on experimental results obtained in rodents.

Protective Effects of Early Caffeine Administration in Hyperoxia-Induced Neurotoxicity in the Juvenile Rat

High-risk preterm infants are affected by a higher incidence of cognitive developmental deficits due to the unavoidable risk factor of oxygen toxicity. Caffeine is known to have a protective effect in preventing bronchopulmonary dysplasia associated with improved neurologic outcomes, although very early initiation of therapy is controversial. In this study, we used newborn rats in an oxygen injury model to test the hypothesis that near-birth caffeine administration modulates neuronal maturation and differentiation in the hippocampus of the developing brain. For this purpose, newborn Wistar rats were exposed to 21% or 80% oxygen on the day of birth for 3 or 5 days and treated with vehicle or caffeine (10 mg/kg/48 h). Postnatal exposure to 80% oxygen resulted in a drastic reduction of associated neuronal mediators for radial glia, mitotic/postmitotic neurons, and impaired cell-cycle regulation, predominantly persistent even after recovery to room air until postnatal day 15. Systemic caffeine administration significantly counteracted the effects of oxygen insult on neuronal maturation in the hippocampus. Interestingly, under normoxia, caffeine inhibited the transcription of neuronal mediators of maturing and mature neurons. The early administration of caffeine modulated hyperoxia-induced decreased neurogenesis in the hippocampus and showed neuroprotective properties in the neonatal rat oxygen toxicity model.

Oxygenation of the newborn. The impact of one molecule on newborn lives

Hypoxanthine is a purine metabolite which increases during hypoxia and therefore is an indicator of this condition. Further, when hypoxanthine is oxidized to uric acid in the presence of xanthine oxidase, oxygen radicals are generated. This was the theoretical basis for suggesting and studying, beginning in the 1990s, resuscitation of newborn infants with air instead of the traditional 100% O2. These studies demonstrated a 30% reduction in mortality when resuscitation of term and near term infants was carried out with air compared to pure oxygen. The mechanism for this is not fully understood, however the hypoxanthine -xanthine oxidase system increases oxidative stress and plays a role in regulation of the perinatal circulation. Further, hyperoxic resuscitation inhibits mitochondrial function, and one reason may be that genes involved in ATP production are down-regulated. Thus, the study of one single molecule, hypoxanthine, has contributed to the global prevention of an estimated 2-500,000 annual infant deaths.

Perinatal Oxidative Stress and Kidney Health: Bridging the Gap between Animal Models and Clinical Reality

Oxidative stress arises when the generation of reactive oxygen species or reactive nitrogen species overwhelms antioxidant systems. Developing kidneys are vulnerable to oxidative stress, resulting in adult kidney disease. Oxidative stress in fetuses and neonates can be evaluated by assessing various biomarkers. Using animal models, our knowledge of oxidative-stress-related renal programming, the molecular mechanisms underlying renal programming, and preventive interventions to avert kidney disease has grown enormously. This comprehensive review provides an overview of the impact of perinatal oxidative stress on renal programming, the implications of antioxidant strategies on the prevention of kidney disease, and the gap between animal models and clinical reality.

BORN study: a multicenter randomized trial investigating cord blood red blood cell transfusions to reduce the severity of retinopathy of prematurity in extremely low gestational age neonates

BACKGROUND

Extremely low gestational age neonates (ELGANs, i.e., neonates born before 28 weeks of gestation) are at high risk of developing retinopathy of prematurity (ROP), with potential long-life visual impairment. Due to concomitant anemia, ELGANs need repeated red blood cell (RBC) transfusions. These produce a progressive replacement of fetal hemoglobin (HbF) by adult hemoglobin (HbA). Furthermore, a close association exists between low levels of HbF and severe ROP, suggesting that a perturbation of the HbF-mediated oxygen release may derange retinal angiogenesis and promote ROP.

METHODS/DESIGN

BORN (umBilical blOod to tRansfuse preterm Neonates) is a multicenter double-blinded randomized controlled trial in ELGANs, to assess the effect of allogeneic cord blood RBC transfusions (CB-RBCs) on severe ROP development. Recruitment, consent, and randomization take place at 10 neonatology intensive care units (NICUs) of 8 Italian tertiary hospitals. ELGANs with gestational age at birth comprised between 24+0 and 27+6 weeks are randomly allocated into two groups: (1) standard RBC transfusions (adult-RBCs) (control arm) and (2) CB-RBCs (intervention arm). In case of transfusion need, enrolled patients receive transfusions according to the allocation arm, unless an ABO/RhD CB-RBC is unavailable. Nine Italian public CB banks cooperate to make available a suitable amount of CB-RBC units for all participating NICUs. The primary outcome is the incidence of severe ROP (stage 3 or higher) at discharge or 40 weeks of postmenstrual age, which occurs first.

DISCUSSION

BORN is a groundbreaking trial, pioneering a new transfusion approach dedicated to ELGANs at high risk for severe ROP. In previous non-randomized trials, this transfusion approach was proven feasible and able to prevent the HbF decrease in patients requiring multiple transfusions. Should the BORN trial confirm the efficacy of CB-RBCs in reducing ROP severity, this transfusion strategy would become the preferential blood product to be used in severely preterm neonates.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05100212. Registered on October 29, 2021.

Analysis of cellular and cell free mitochondrial DNA content and reactive oxygen species levels in maternal blood during normal pregnancy: a pilot study

BACKGROUND

Alterations in mitochondrial signatures such as mitochondrial DNA (mtDNA) content in maternal blood have been linked to pregnancy-related complications. However, changes in maternal mtDNA content, their distribution and associated signaling during normal pregnancies are not clear; which could suggest their physiological role in maternal adaptation to pregnancy related changes and a reference threshold.

THE AIM OF THIS STUDY

to assess the distribution of mtDNA in peripheral blood and their association with circulatory ROS levels across different trimesters of healthy pregnancy.

METHODS

In this pilot cross sectional study, blood samples of normal pregnant women from each trimester (total = 60) and age-matched non-pregnant (NP) women as control group (n = 20) were analyzed for a) the relative distribution of mtDNA content in cellular and cell free (plasma) fractions using relative quantitative polymerase chain reaction (qPCR) and b) the levels of circulating reactive oxygen species (ROS) by measurement of plasma H2O2. The results were compared between pregnant and NP groups and within trimesters for significant differences, and were also analyzed for their correlation between groups using statistical methods.

RESULTS

While, we observed a significant decline in cellular mtDNA; plasma mtDNA was significant increased across all trimesters compared to NP. However, from comparisons within trimesters; only cellular mtDNA content in 3rd trimester was significantly reduced compared to 1st trimester, and plasma mtDNA did not differ significantly among different trimesters. A significantly higher level of plasma H2O2 was also observed during 3rd trimester compared to NP and to 1st trimester. Correlation analysis showed that, while cellular mtDNA content was negatively correlated to plasma mtDNA and to plasma H2O2 levels; plasma mtDNA was positively correlated with plasma H2O2 content.

CONCLUSIONS

This study suggested that normal pregnancy is associated with an opposing trend of reduced cellular mtDNA with increased circulatory mtDNA and H2O2 levels, which may contribute to maternal adaptation, required during different stages of pregnancy. Estimation of mtDNA distribution and ROS level in maternal blood could show mitochondrial functionality during normal pregnancy, and could be exploited to identify their prognostic/ diagnostic potential in pregnancy complications.

Randomized controlled trial of low vs high oxygen during neonatal anesthesia: Oxygenation, feasibility, and oxidative stress

BACKGROUND

To reduce risk for intermittent hypoxia a high fraction of inspired oxygen is routinely used during anesthesia induction. This differs from the cautious dosing of oxygen during neonatal resuscitation and intensive care and may result in significant hyperoxia.

AIM

In a randomized controlled trial, we evaluated oxygenation during general anesthesia with a low (23%) vs a high (80% during induction and recovery, and 40% during maintenance) fraction of inspired oxygen, in newborn infants undergoing surgery.

METHOD

Thirty-five newborn infants with postconceptional age of 35-44 weeks were included (17 infants in low and 18 in high oxygen group). Oxygenation was monitored by transcutaneous partial pressure of oxygen, pulse oximetry, and cerebral oxygenation. Predefined SpO2 safety targets dictated when to increase inspired oxygen.

RESULTS

At start of anesthesia, oxygenation was similar in both groups. Throughout anesthesia, the high oxygen group displayed significant hyperoxia with higher (difference-20.3 kPa, 95% confidence interval (CI)-28.4 to 12.2, p < .001) transcutaneous partial pressure of oxygen values than the low oxygen group. While SpO2 in the low oxygen group was lower (difference - 5.8%, 95% CI -9.3 to -2.4, p < .001) during anesthesia, none of the infants spent enough time below SpO₂ safety targets to mandate supplemental oxygen, and cerebral oxygenation was within the normal range and not statistically different between the groups. Analysis of the oxidative stress biomarker urinary F₂ -Isoprostane revealed no differences between the low and high oxygen group.

CONCLUSION

We conclude that in healthy newborn infants, use of low oxygen during general anesthesia was feasible, while the prevailing practice of using high levels of inspired oxygen resulted in significant hyperoxia. The trade-off between careful dosing of oxygen and risks of hypo- and hyperoxia in neonatal anesthesia should be further examined.

Early versus late parenteral nutrition in term and late preterm infants: study protocol for a randomised controlled trial

BACKGROUND

Despite the wide use of parenteral nutrition (PN) in neonatal intensive care units (NICU), there is limited evidence regarding the optimal time to commence PN in term and late preterm infants. The recommendations from the recently published ESPGHAN/ESPEN/ESPR/CPEN and NICE guidelines are substantially different in this area, and surveys have reported variations in clinical practice. The aim of this randomised controlled trial (RCT) is to evaluate the benefits and risks of early versus late PN in term and late preterm infants.

METHODS/DESIGN

This study is a single-centre, non-blinded RCT in the NICU of Perth Children's Hospital, Western Australia.A total of 60 infants born ≥34 weeks of gestation who have a high likelihood of intolerance to enteral nutrition (EN) for at least 3-5 days will be randomised to early (day 1 or day 2 of admission) or late commencement (day 6 of admission) of PN after informed parental consent. In both groups, EN will be commenced as early as clinically feasible. Primary outcomes are plasma phenylalanine and plasma F2-isoprostane levels on Day 4 and Day 8 of admission. Secondary outcomes are total and individual plasma amino acid profiles, plasma and red blood cell fatty acid profiles, in-hospital all-cause mortality, hospital-acquired infections, length of hospital/NICU stay, z scores and changes in z scores at discharge for weight, height and head circumference, time to full EN, duration of respiratory (mechanical, non-invasive) support, duration of inotropic support, the incidence of hyper and hypoglycaemia, incidence of metabolic acidosis, liver function, blood urea nitrogen, and C-reactive protein (CRP).

DISCUSSION

This RCT will examine the effects of early versus late PN in term and late preterm infants by comparing key biochemical and clinical outcomes and has the potential to identify underlying pathways for beneficial or harmful effects related to the timing of commencement of PN in such infants.

TRIAL REGISTRATION

ANZCTR; ACTRN12620000324910 (3rd March 2020).

Hyperoxia by short-term promotes oxidative damage and mitochondrial dysfunction in rat brain

Oxygen (O₂) therapy is used as a therapeutic protocol to prevent or treat hypoxia. However, a high inspired fraction of O₂ (FIO₂) promotes hyperoxia, a harmful condition for the central nervous system (CNS). The present study evaluated parameters of oxidative stress and mitochondrial dysfunction in the brain of rats exposed to different FIO₂. Male Wistar rats were exposed to hyperoxia (FIO₂ 40 % and 60 %) compared to the control group (FIO₂ 21 %) for 2 h. Oxidative stress, neutrophilic infiltration, and mitochondrial respiratory chain enzymes were determined in the hippocampus, striatum, cerebellum, cortex, and prefrontal cortex after O₂ exposure. The animals exposed to hyperoxia showed increased lipid peroxidation, formation of carbonyl proteins, N/N concentration, and neutrophilic infiltration in some brain regions, like hippocampus, striatum, and cerebellum being the most affected. Furthermore, CAT activity and activity of mitochondrial enzyme complexes were also altered after exposure to hyperoxia. Rats exposed to hyperoxia showed increase in oxidative stress parameters and mitochondrial dysfunction in brain structures.

Packed red blood cell transfusion in preterm infants

Premature infants commonly receive adult packed red blood cells (pRBCs) during their hospital stay. As adult erythrocytes differ substantially from those of preterm infants, transfusion of adult pRBCs into preterm infants can be considered inappropriate for the physiology of a preterm infant. An absence of standardisation of transfusion protocols makes it difficult to compare and interpret pertinent clinical data, as reflected by unclear associations between pRBC transfusion and complications related to prematurity, such as bronchopulmonary dysplasia, neurodevelopmental impairment, retinopathy of prematurity, or necrotising enterocolitis. The difficulty in interpreting clinical data is further increased by differences in study designs that either overestimate pRBC-associated complications of prematurity or have not yet been designed to directly link pRBC transfusions to their respective complications. Thus, neonatal transfusion practice has become an ongoing difficulty, in which differences in transfusion guidelines hinder the ability to generate comparable clinical data, and heterogeneity in clinical data prevents the implementation of standardised transfusion protocols. To overcome these issues, novel approaches with biochemical-clinical translational designs could enable clinicians to gather causal evidence instead of circumstantial correlation.

Glucocorticoids in a Neonatal Hyperoxic Lung Injury Model: Pulmonary and Neurotoxic effects

BACKGROUND

We aimed to compare the effect of dexamethasone (Dex), hydrocortisone (Hc), and methylprednisolone (Mpz) at equivalent doses on somatic growth, lung healing, and neurotoxicity in a hyperoxic rat model. We hypothesized that Mpz and Hc would be superior to Dex with less neurotoxicity by exerting similar therapeutic efficacy on the injured lung.

METHODS

Neonatal rats were randomized to control, bronchopulmonary dysplasia (BPD), Dex, Hc, and Mpz groups. All drugs were administered daily following day 15 over 7 days. Histopathological and immunohistochemical analyses of the lung and brain were performed on day 22.

RESULTS

All types had much the same impact on lung repair. Oxidative markers in the lung were similar in the steroid groups. While nuclear factor erythroid 2-related factor and heat-shock protein 70 dropped following steroid treatment, no difference was noted in other biochemical markers in the brain between the study groups. Apoptotic activity and neuron loss in the parietal cortex and hippocampus were noted utmost in Dex, but alike in other BPD groups.

CONCLUSIONS

Mpz does not appear to be superior to Dex or Hc in terms of pulmonary outcomes and oxidative damage in the brain, but safer than Dex regarding apoptotic neuron loss.

IMPACT

This is the first study that compared the pulmonary efficacy and neurotoxic effects of Dex, Hc, and Mpz simultaneously in an established BPD model. This study adds to the literature on the importance of possible antioxidant and protective effects of glucocorticoid therapy in an oxidative stress-exposed brain. Mpz ended up with no more additional neuron loss or apoptosis risk by having interchangeable effects with others for the treatment of established BPD. Mpz and Hc seem safe as a rescue therapy in terms of adverse outcomes for established BPD in which lung and brain tissue is already impaired.

Pulmonary hypertension and oxidative stress: Where is the link?

Oxidative stress can be associated with hyperoxia and hypoxia and is characterized by an increase in reactive oxygen (ROS) and nitrogen (RNS) species generated by an underlying disease process or by supplemental oxygen that exceeds the neutralization capacity of the organ system. ROS and RNS acting as free radicals can inactive several enzymes and vasodilators in the nitric oxide pathway promoting pulmonary vasoconstriction resulting in persistent pulmonary hypertension of the newborn (PPHN). Studies in animal models of PPHN have shown high ROS/RNS that is further increased by hyperoxic ventilation. In addition, antioxidant therapy increased PaO2 in these models, but clinical trials are lacking. We recommend targeting preductal SpO2 between 90 and 97%, PaO2 between 55 and 80 mmHg and avoiding FiO2 > 0.6-0.8 if possible during PPHN management. This review highlights the role of oxidative and nitrosative stress markers on PPHN and potential therapeutic interventions that may alleviate the consequences of increased oxidant stress during ventilation with supplemental oxygen.

Respiratory distress syndrome management in resource limited settings-Current evidence and opportunities in 2022

The complications of prematurity are the leading cause of neonatal mortality worldwide, with the highest burden in the low- and middle-income countries of South Asia and Sub-Saharan Africa. A major driver of this prematurity-related neonatal mortality is respiratory distress syndrome due to immature lungs and surfactant deficiency. The World Health Organization's Every Newborn Action Plan target is for 80% of districts to have resources available to care for small and sick newborns, including premature infants with respiratory distress syndrome. Evidence-based interventions for respiratory distress syndrome management exist for the peripartum, delivery and neonatal intensive care period- however, cost, resources, and infrastructure limit their availability in low- and middle-income countries. Existing research and implementation gaps include the safe use of antenatal corticosteroid in non-tertiary settings, establishing emergency transportation services from low to high level care facilities, optimized delivery room resuscitation, provision of affordable caffeine and surfactant as well as implementing non-traditional methods of surfactant administration. There is also a need to optimize affordable continuous positive airway pressure devices able to blend oxygen, provide humidity and deliver reliable pressure. If the high prematurity-related neonatal mortality experienced in low- and middle-income countries is to be mitigated, a concerted effort by researchers, implementers and policy developers is required to address these key modalities.

Oxidative Stress and Antioxidative Therapy in Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is clinically characterized by a progressive increase in pulmonary artery pressure, followed by right ventricular hypertrophy and subsequently right heart failure. The underlying mechanism of PAH includes endothelial dysfunction and intimal smooth muscle proliferation. Numerous studies have shown that oxidative stress is critical in the pathophysiology of PAH and involves changes in reactive oxygen species (ROS), reactive nitrogen (RNS), and nitric oxide (NO) signaling pathways. Disrupted ROS and NO signaling pathways cause the proliferation of pulmonary arterial endothelial cells (PAECs) and pulmonary vascular smooth muscle cells (PASMCs), resulting in DNA damage, metabolic abnormalities, and vascular remodeling. Antioxidant treatment has become a main area of research for the treatment of PAH. This review mainly introduces oxidative stress in the pathogenesis of PAH and antioxidative therapies and explains why targeting oxidative stress is a valid strategy for PAH treatment.

Polyphenols and IUGR Pregnancies: Effects of the Antioxidant Hydroxytyrosol on the Hippocampus Proteome in a Porcine Model

Supplementation of a mother’s diet with antioxidants such as hydroxytyrosol (HTX) has been proposed to ameliorate the adverse phenotypes of foetuses affected by intrauterine growth restriction (IUGR). Our previous studies showed, in a porcine model of IUGR, an effect of maternal HTX supplementation on the neurotransmitter profile of several brain areas and the morphology of the hippocampus in 100 days old foetuses. The present study analyzed the impact of maternal HTX supplementation on the hippocampus proteome at this foetal age by TMT10plex labelling. Eleven differentially abundant proteins were identified by comparing both conditions, and eight of them downregulated and three upregulated in the HTX-treated group. The downregulated proteins were mainly involved in protein synthesis and RNA metabolism and may explain the differences in neuron differentiation in the HTX-treated group. The upregulated proteins were related to cell detoxification and could represent a potential mechanism to explain the neuroprotective effect of HTX.

Severity of neonatal influenza infection is driven by type I interferon and oxidative stress

Neonates exhibit increased susceptibility to respiratory viral infections, attributed to inflammation at the developing pulmonary air-blood interface. IFN I are antiviral cytokines critical to control viral replication, but also promote inflammation. Previously, we established a neonatal murine influenza virus (IV) model, which demonstrates increased mortality. Here, we sought to determine the role of IFN I in this increased mortality. We found that three-day-old IFNAR-deficient mice are highly protected from IV-induced mortality. In addition, exposure to IFNβ 24 h post IV infection accelerated death in WT neonatal animals but did not impact adult mortality. In contrast, IFN IIIs are protective to neonatal mice. IFNβ induced an oxidative stress imbalance specifically in primary neonatal IV-infected pulmonary type II epithelial cells (TIIEC), not in adult TIIECs. Moreover, neonates did not have an infection-induced increase in antioxidants, including a key antioxidant, superoxide dismutase 3, as compared to adults. Importantly, antioxidant treatment rescued IV-infected neonatal mice, but had no impact on adult morbidity. We propose that IFN I exacerbate an oxidative stress imbalance in the neonate because of IFN I-induced pulmonary TIIEC ROS production coupled with developmentally regulated, defective antioxidant production in response to IV infection. This age-specific imbalance contributes to mortality after respiratory infections in this vulnerable population.

Antioxidants: Role the in prevention and treatment of bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is one of the major causes of chronic respiratory diseases among infants. Both pharmacological and nonpharmacological approaches have been proposed for its management. Since oxidative stress is known to play a pivotal role in the pathogenesis of BPD, it is reasonable to consider the potential of antioxidant strategies in the prevention and treatment of this condition. Indeed, antioxidants can prevent or inhibit substrate oxidation. Some studies have evaluated the efficacy of the exogenous administration of vitamins and micronutrients in reducing the propagation of free radicals through their scavenging capacity. Nonetheless, encouraging preclinical results did not translate into effective preventive and/or therapeutic interventions. This narrative review evaluates the current evidence about the antioxidants that are potentially useful for preventing and treating BPD and explores the most relevant issues affecting their implementation in clinical practice, as well as their associated evidence gaps and research limitations.

In Vivo Assessment of Antioxidant Potential of Human Milk Treated by Holder Pasteurization or High Hydrostatic Pressure Processing: A Preliminary Study on Intestinal and Hepatic Markers in Adult Mice

Preterm infants are highly susceptible to oxidative stress due to an imbalance between endogenous oxidant and antioxidant systems. In addition, these newborns are frequently fed with donor milk (DM) treated by Holder pasteurization (HoP) at 62.5 °C for 30 min, which is known to alter numerous heat-sensitive factors, including some antioxidants. High hydrostatic pressure (HHP) processing was recently proposed as an innovative method for the treatment of DM. The present study aimed to measure the redox balance of HoP- and HHP-DM and to study, in vivo, the effects of HoP- and HHP-DM on the gut and liver. H₂O₂, vitamin A and vitamin E (α- and γ-tocopherols) concentrations, as well as the total antioxidant capacity (TAC), were measured in raw-, HoP- and HHP-DM. The gene expression level of antioxidant systems and inflammatory response were quantified in the ileum and liver of adult mice after 7 days of oral administration of HoP- or HHP-DM. HoP reduced the γ-tocopherol level, whereas HHP treatment preserved all vitamins close to the raw milk level. The milk H₂O₂ content was reduced by HHP but not by HoP. The total antioxidant capacity of DM was reduced after HHP processing measured by PAOT-Liquid^® technology but was unaffected after measurement by ORAC assay. In mice, HHP-DM administration induced a stimulation of antioxidant defenses and reduced some inflammatory markers in both the ileum and liver compared to HoP-DM treatment. Our preliminary study suggests that the HHP processing of DM may better protect preterm infants from gut and liver pathologies compared to HoP, which is currently used in most human milk banks.

Pulmonary Resilience: Moderating the Association between Oxygen Exposure and Pulmonary Outcomes in Extremely Preterm Newborns

Bronchopulmonary dysplasia (BPD) is a chronic lung disease of infancy associated with high morbidity and mortality. Although most prevalent following extremely preterm birth, BPD is diagnosed at 36 weeks post-menstrual age, when the disease trajectory is underway, and long-term physiological implications may be irreversible. There is an urgent and unmet need to identify how early exposures can be modified to decrease the risk of developing BPD before disease progression becomes irreversible. Extremely preterm newborns encounter a paradox at birth: oxygen is a life-sustaining component of ex utero life yet is undeniably toxic. Attempts at minimizing supplemental oxygen exposure by targeting lower oxygen saturations appear to decrease BPD but may increase mortality. Given the potential association between lower oxygen saturations and increased mortality, practice guidelines favor targeting higher saturations. This uniformly increases oxygen exposure, prompting a cascade of pathogenic mechanisms implicated in BPD development. In this review, we introduce the concept of pulmonary resilience: a homeostatic process driven by the autonomic nervous system (ANS) as a moderator of physiologic stress that when functional, could inform successful environmental adaptation following extremely preterm birth. We hypothesize that infants with early-life ANS dysfunction require a higher oxygen dose for survival; conversely, oxygen exposure could be safely limited in infants with more robust early-life ANS function, an indicator of pulmonary resilience. Characterizing the pulmonary resilience continuum to guide individualized supplemental oxygen dosing may reduce morbidity and mortality in this growing population of extremely preterm infants at risk for BPD.

Vitamin E and preterm infants

In evaluating vitamin E (VE) nutritional status of preterm infants, it is essential that any data should be compared with those of healthy term infants, and never with those of adults. Moreover, it should be evaluated in terms of gestational age (GA), not birth weight (BW), because placental transfer of most nutrients from mother to fetus is dependent on GA, not BW. Judging from the limited data during the last 75 years, there was no significant correlation between GA and VE concentrations in circulation or in the red blood cells (RBCs), leukocytes, and buccal mucosal cells. In addition, the oxidizability of polyunsaturated fatty acids (PUFAs) in plasma or RBCs, as targets for protection by VE chain-breaking ability, was lower in preterm infants. However, because of the minimal information available about hepatic VE levels, which is considered a key determinant of whole body VE status, the decision on whether VE status of preterm infants is comparable with that of term infants should be postponed. Clinical trials of VE supplementation in preterm infants were repeatedly undertaken to investigate whether VE reduces severity or inhibits development of several diseases specific to preterm infants, namely retinopathy of prematurity (ROP), bronchopulmonary dysplasia (BPD), and germinal matrix hemorrhage - intraventricular hemorrhage (GMH-IVH). Most of these trials resulted in a misfire, with a few exceptions for IVH prevention. However, almost all these studies were performed from 1980s to early 1990s, in the pre-surfactant era, and the study populations were composed of mid-preterm infants with GAs of approximately 30 weeks (wks). There is considerable difference in 'preterm infants' between the pre- and post-surfactant eras; modern neonatal medicine mainly treats preterm infants of 28 wks GA or less. Therefore, these results are difficult to apply in modern neonatal care. Before considering new trials of VE supplementation, we should fully understand modern neonatal medicine, especially the recent method of oxygen supplementation. Additionally, a deeper understanding of recent progress in pathophysiology and therapies for possible target diseases is necessary to decide whether VE administration is still worth re-challenging in modern neonatal intensive care units (NICUs). In this review, we present recent concepts and therapeutic trends in ROP, BPD, and GMH-IVH for those unfamiliar with neonatal medicine. Numerous studies have reported the possible involvement of reactive oxygen species (ROS)-induced damage in relation to supplemental oxygen use, inflammation, and immature antioxidant defense in the development of both BPD and ROP. Various antioxidants effectively prevented the exacerbation of BPD and ROP in animal models. In the future, VE should be re-attempted as a complementary factor in combination with various therapies for BPD, ROP, and GMH-IVH. Because VE is a natural and safe supplement, we are certain that it will attract attention again in preterm medicine.

Impaired Antioxidant Defence Status Is Associated With Metabolic-Inflammatory Risk Factors in Preterm Children With Extrauterine Growth Restriction: The BIORICA Cohort Study

Introduction: An impaired antioxidant status has been described during foetal growth restriction (FGR). Similarly, the antioxidant defence system can be compromised in preterm children with extrauterine growth restriction (EUGR). The aim of this prospective study was to evaluate the antioxidant status in prepubertal children with a history of prematurity without FGR, with and without EUGR, compared to a healthy group. Methods: In total, 211 children were recruited and classified into three groups: 38 with a history of prematurity and EUGR; 50 with a history of prematurity and adequate extrauterine growth (AEUG); and 123 control children born at term. Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities were assessed in lysed erythrocytes with spectrophotometric methods. Plasma levels of the antioxidants α-tocopherol, retinol and β-carotene were determined through solvent extraction and ultra-high-pressure liquid chromatography coupled to mass spectrometry. Results: Children with the antecedent of EUGR and prematurity had lower CAT activity than the other two groups and lower GPx activity than the control children. Lower SOD, GPx and GR activities were observed in the AEUG group compared to the controls. However, higher concentrations of α-tocopherol and β-carotene were found in the EUGR group compared to the other groups; retinol levels were also higher in EUGR than in AEUG children. In EUGR and AEUG children, enzymatic antioxidant activities and plasma antioxidants were associated with metabolic syndrome components and pro-inflammatory biomarkers. Conclusions: This study reveals, for the first time, that the EUGR condition and prematurity appear to be linked to an impairment of the antioxidant defence status, which might condition an increased risk of adverse metabolic outcomes later in life.

Transfusion-Free Survival Predicts Severe Retinopathy in Preterm Neonates

Repeated red blood cell (RBC) transfusions are thought to increase the risk for retinopathy of prematurity (ROP), likely due to a critical fetal hemoglobin (HbF) reduction. In this study, we investigated if the postmenstrual age (PMA) of neonates at transfusion influences the risk for ROP. We estimated the cumulative transfusion-free survival (TFS) in a series of 100 preterm neonates receiving one or more RBC units. TFS was calculated by censoring patients at first transfusion and expressing the time between birth and transfusion as either PMA or postnatal day. Then, we investigated if TFS predicted the occurrence of severe ROP, defined as ROP stage 3 or higher. We found that neonates with severe ROP displayed a significantly shorter TFS expressed according to their PMA (p = 0.001), with similar TFS according to postnatal days. At receiver operating characteristic (ROC) curve analysis, receiving an RBC unit before week 28 of PMA predicted severe ROP with a sensitivity of 64% and a specificity of 78%. In addition, receiving a second RBC unit before the PMA of 29 weeks predicted severe ROP with a sensitivity of 75% and a specificity of 69%. At multivariate analysis, PMA at the second transfusion was even more informative than at first transfusion and outperformed all other variables in predicting severe ROP, with an odds ratio of 4.554 (95% CI 1.332-15.573, p = 0.016). Since HbF decrease is greater after multiple RBC transfusions, it is conceivable that neonates receiving more than one unit before the PMA of 29 weeks may be exposed to a greater disturbance of retinal vascularization. Any strategy aimed at preventing the critical HbF decrease at this low age might potentially reduce the risk for severe ROP.

Antioxidant Effect of Melatonin in Preterm Newborns

Introduction

Preterm infants are at risk of free radical-mediated diseases from oxidative stress (OS) injury. Increased free radical generation has been demonstrated in preterm infants during the first seven days of life. Melatonin (MEL) is a powerful antioxidant and scavenger of free radicals. In preterm neonates, melatonin deficiency has been reported. Exogenous melatonin administration appears a promising strategy in the treatment of neonatal morbidities in which OS has a leading role.

Objective

The aim was to evaluate plasma MEL concentrations and OS biomarkers in preterm newborns after early administration of melatonin.

Methods

A prospective, randomized double-blind placebo-controlled pilot study was conducted from January 2019 to September 2020. Thirty-six preterm newborns were enrolled. Starting from the first day of life, 21 received a single dose of oral melatonin 0.5 mg/kg once a day, in the morning (MEL group); 15 newborns received an equivalent dose of placebo (placebo group). Samples of 0.2 mL of plasma were collected at 24 and 48 hours after MEL administration. Plasma concentrations of melatonin, non-protein-bound iron (NPBI), advanced oxidation protein products (AOPP), and F2-isoprostanes (F2-Isopr) were measured. Babies were clinically followed until discharge.

Results

At 24 and 48 hours after MEL administration, the MEL concentrations were significantly higher in the MEL group than in the placebo group (52759.30 ± 63529.09 vs. 28.57 ± 46.24 pg/mL and 279397.6 ± 516344.2 vs. 38.50 ± 44.01 pg/mL, respectively). NPBI and AOPP did not show any statistically significant differences between the groups both at 24 and 48 hours. At 48 hours, the mean blood concentrations of F2-Isopr were significantly lower in the MEL group than in the placebo group (36.48 ± 33.85 pg/mL vs.89.97 ± 52.01 pg/mL).

Conclusions

Early melatonin administration in preterm newborns reduces lipid peroxidation in the first days of life showing a potential role to protect high-risk newborns. Trial Registration. This trial is registered with NCT04785183, Early Supplementation of Melatonin in Preterm Newborns: the Effects on Oxidative Stress.

Influence of Oxidative Stress Generated by Smoking during Pregnancy on Glutathione Status in Mother-Newborn Pairs

Glutathione plays a key role in maintaining a physiological balance between prooxidants and antioxidants in the human body. Therefore, we examined the influence of maternal smoking as a source of oxidative stress measured by total oxidant capacity (TOC) on reduced glutathione (GSH), oxidized glutathione (GSSG), glutathione peroxidase (GPx-3), and reductase (GR) amount in maternal and umbilical cord blood in 110 (45 smoking and 65 non-smoking) mother-newborn pairs. Concentrations of glutathione status markers and TOC were evaluated by competitive inhibition enzyme immunoassay technique. Plasma TOC levels were significantly higher and the GSH/GSSG ratio, which is considered an index of the cell’s redox status, were significantly lower in smoking women and their offspring than in non-smoking pairs. Decreased GR levels were found in smoking mothers and their newborns compared with similar non-smoking groups. Although plasma GPx-3 concentrations were similar in both maternal groups, in the cord blood of newborns exposed to tobacco smoke in utero they were reduced compared with the levels observed in children of tobacco abstinent mothers. Oxidative stress generated by tobacco smoke impairs glutathione homeostasis in both the mother and the newborn. The severity of oxidative processes in the mother co-existing with the reduced potential of antioxidant systems may have a negative effect on the oxidative-antioxidant balance in the newborn.

Oxidative Stress and Respiratory Diseases in Preterm Newborns

Premature infants are exposed to increased generation of reactive oxygen species, and on the other hand, they have a deficient antioxidant defense system. Oxidative insult is a salient part of lung injury that begins as acute inflammatory injury in respiratory distress disease and then evolves into chronic and structural scarring leading to bronchopulmonary dysplasia. Oxidative stress is also involved in the pathogenesis of pulmonary hypertension in newborns through the modulation of the vascular tone and the response to pulmonary vasodilators, with consequent decrease in the density of the pulmonary vessels and thickening of the pulmonary arteriolar walls. Oxidative stress has been recognized as both a trigger and an endpoint for several events, including inflammation, hypoxia, hyperoxia, drugs, transfusions, and mechanical ventilation, with impairment of pulmonary function and prolonged lung damage. Redoxomics is the most fascinating new measure to address lung damage due to oxidative stress. The new challenge is to use omics data to discover a set of biomarkers useful in diagnosis, prognosis, and formulating optimal and individualized neonatal care. The aim of this review was to examine the most recent evidence on the relationship between oxidative stress and lung diseases in preterm newborns. What is currently known regarding oxidative stress-related lung injury pathogenesis and the available preventive and therapeutic strategies are also discussed.

Fetal hemoglobin levels in premature newborns. Should we reconsider transfusion of adult donor blood?

PURPOSE

The aim of this study was to assess the percent decrease in fetal hemoglobin (HbF) after transfusion of adult-derived donor packed red blood cell (pRBC) units in extremely low gestational age newborns (ELGANs).

METHODS

Control percent fetal hemoglobin (%HbF) levels were measured in newborn cord blood or peripheral blood samples in non-transfused patients prior to elective surgery. ELGANs were followed prospectively and %HbF was measured on residual post-test complete blood count (CBC) specimens. ELGAN %HbF values were compared to the control population and transfusions were recorded.

RESULTS

Initial mean %HbF in ELGANs (n=16) was 92.2±1.3% (range 90.2-95.1%), which is similar to the control group (n=25). Mean levels dropped to 61.1±11.1% (range 34.2-73.2%) after a single pRBC transfusion (n=9) and to a mean of 35.6±6.3% after an additional transfusion (n=5). %HbF levels trended upwards if no additional transfusions were given, but levels still remained lower than expected for gestational age through discharge (n=85 samples).

CONCLUSIONS

Percent fetal hemoglobin concentrations in ELGANs decrease precipitously after transfusion with adult donor pRBCs. Further studies are needed to evaluate the benefit of maintaining higher fetal hemoglobin concentrations in these patients and whether administration of HbF rather than adult donor pRBCs would improve patient outcomes.

Oxygen Toxicity to the Immature Lung-Part II: The Unmet Clinical Need for Causal Therapy

Oxygen toxicity continues to be one of the inevitable injuries to the immature lung. Reactive oxygen species (ROS) production is the initial step leading to lung injury and, subsequently, the development of bronchopulmonary dysplasia (BPD). Today, BPD remains the most important disease burden following preterm delivery and results in life-long restrictions in lung function and further important health sequelae. Despite the tremendous progress in the pathomechanistic understanding derived from preclinical models, the clinical needs for preventive or curative therapies remain unmet. This review summarizes the clinical progress on guiding oxygen delivery to the preterm infant and elaborates future directions of research that need to take into account both hyperoxia and hypoxia as ROS sources and BPD drivers. Many strategies have been tested within clinical trials based on the mechanistic understanding of ROS actions, but most have failed to prove efficacy. The majority of these studies were tested in an era before the latest modes of non-invasive respiratory support and surfactant application were introduced or were not appropriately powered. A comprehensive re-evaluation of enzymatic, antioxidant, and anti-inflammatory therapies to prevent ROS injury is therefore indispensable. Strategies will only succeed if they are applied in a timely and vigorous manner and with the appropriate outcome measures.

Impact of Arterial Carbon Dioxide and Oxygen Content on Cerebral Autoregulation Monitoring Among Children Supported by ECMO

BACKGROUND

Cerebral autoregulation (CA) impairment is associated with neurological complications among children supported by extracorporeal membrane oxygenation (ECMO). Severe variations of arterial CO₂ (PaCO₂) and O₂ (PaO₂) tension after ECMO onset are common and associate with mortality and poor neurological outcome. The impact of gas exchange on CA among critically ill patients is poorly studied.

METHODS

Retrospective analysis of data collected prospectively from 30 children treated with veno-arterial or veno-venous ECMO in the PICU of Nantes University Hospital, France. A correlation coefficient between the variations of regional cerebral oxygen saturation (rSO₂) and the variations of mean arterial blood pressure (MAP) was calculated as an index of CA (cerebral oxygenation reactivity index, COx). Cox-MAP plots were investigated allowing determining lower limit of autoregulation (LLA) and upper limit of autoregulation (ULA) limits of autoregulation. Age-based normal blood pressure was used to adjust the MAP, LLA, and ULA data from each patient and then reported as percentage (nMAP, nLLA, and nULA, respectively). RSO₂, COx, nMAP, nLLA, and nULA values were averaged over one hour before each arterial blood gas (ABG) sample during ECMO run.

RESULTS

Thirty children (median age 4.8 months [Interquartile range (IQR) 0.7-39.1], median weight 5 kg [IQR 4-15]) experiencing 31 ECMO runs were included in the study. Three hundred and ninety ABGs were analyzed. The highest values of COx were observed on day 1 (D1) of ECMO. The relationship between COx and PaCO₂ was nonlinear, but COx values tended to be lower in case of hypercapnia compared to normocapnia. During the whole ECMO run, a weak but significant correlation between PaCO₂ and nULA was observed (R = 0.432, p = 0.02). On D1 of ECMO, this correlation was stronger (R = 0.85, p = 0.03) and a positive correlation between nLLA and PaCO₂ was also found (R = 0.726, p < 0.001). A very weak negative correlation between PaO₂ and nULA was observed within the whole ECMO run and on D1 of ECMO (R =  -0.07 p = 0.04 and R =  -0.135 p =  <0.001, respectively). The difference between nULA and nLLA representing the span of the autoregulation plateau was positively correlated with PaCO₂ and negatively correlated with PaO₂ (R = 0.224, p = 0.01 and R =  -0.051, p = 0.004, respectively).

CONCLUSIONS

We observed a complex relationship between PaCO₂ and CA, influenced by the level of blood pressure. Hypercapnia seems to be globally protective in normotensive or hypertensive condition, while, in case of very low MAP, hypercapnia may disturb CA as it increases LLA. These data add additional arguments for very cautiously lower PaCO₂, especially after ECMO start.

Preparation, Structural Characterization, and Property Investigation of Gallic Acid-Grafted Fungal Chitosan Conjugate

Oxidative stress is the cause of numerous diseases in humans; therefore, there has been a continuous search for novel antioxidant molecules. Fungal chitosan is an attractive molecule that has several applications (antifungal, antibacterial, anticancer and antiparasitic action) owing to its unique characteristics; however, it exhibits low antioxidant activity. The aim of this study was to obtain fungal chitosan (Chit-F) from the fungus Rhizopus arrhizus and synthesize its derivative, fungal chitosan-gallic acid (Chit-FGal), as a novel antioxidant chitosan derivative for biomedical use. A low molecular weight Chi-F (~3.0 kDa) with a degree of deacetylation of 86% was obtained from this fungus. Chit-FGal (3.0 kDa) was synthesized by an efficient free radical-mediated method using hydrogen peroxide (H2O2) and ascorbic acid. Both Chit-F and Chit-FGal showed similar copper chelating activities; however, Chit-FGal was more efficient as an antioxidant, exhibiting twice the total antioxidant capacity than Chi-F (p < 0.05). Furthermore, H2O2 (0.06 M) promoted a 50% decrease in the viabilities of the 3T3 fibroblast cells. However, this effect was abolished in the presence of Chit-FGal (0.05-0.25 mg/mL), indicating that Chit-FGal protected the cells from oxidative damage. These results suggest that Chit-FGal may be a promising agent to combat oxidative stress.

Male Disadvantage in Oxidative Stress-Associated Complications of Prematurity: A Systematic Review, Meta-Analysis and Meta-Regression

A widely accepted concept is that boys are more susceptible than girls to oxidative stress-related complications of prematurity, including bronchopulmonary dysplasia (BPD), retinopathy of prematurity (ROP), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and periventricular leukomalacia (PVL). We aimed to quantify the effect size of this male disadvantage by performing a systematic review and meta-analysis of cohort studies exploring the association between sex and complications of prematurity. Risk ratios (RRs) and 95% CIs were calculated by a random-effects model. Of 1365 potentially relevant studies, 41 met the inclusion criteria (625,680 infants). Male sex was associated with decreased risk of hypertensive disorders of pregnancy, fetal distress, and C-section, but increased risk of low Apgar score, intubation at birth, respiratory distress, surfactant use, pneumothorax, postnatal steroids, late onset sepsis, any NEC, NEC > stage 1 (RR 1.12, CI 1.06–1.18), any IVH, severe IVH (RR 1.28, CI 1.22–1.34), severe IVH or PVL, any BPD, moderate/severe BPD (RR 1.23, CI 1.18–1.27), severe ROP (RR 1.14, CI 1.07–1.22), and mortality (RR 1.23, CI 1.16–1.30). In conclusion, preterm boys have higher clinical instability and greater need for invasive interventions than preterm girls. This leads to a male disadvantage in mortality and short-term complications of prematurity.

Association between blood carboxyhemoglobin level and bronchopulmonary dysplasia in extremely low birthweight infants

Carboxyhemoglobin (CO-Hb) can be endogenously formed in the presence of oxidative stress and may be elevated in inflammatory lung disease. There is lack of evidence of its relationship with the development of bronchopulmonary dysplasia (BPD) in extremely low birthweight (ELBW) infants. The objective of the study is to evaluate the relationship between blood CO-Hb levels in the first 14 days of life (DOL) in ELBW infants and the development of BPD at 36 weeks postmenstrual age (PMA). This is a retrospective cohort study of 58 ELBW infants born at LAC-USC Medical Center between June 2015 and and June 2019 who survived to 36 weeks PMA. CO-Hb values were collected daily from DOL 1 to DOL 14. BPD definition using the recent 2019 NICHD criteria was used. Multivariate logistic regression was performed to determine the association between blood CO-Hb levels and BPD. Receiver operator curve was used to evaluate the ability of the median fraction of inspired oxygen (FiO₂) level used at DOL 11-14 in discriminating absent to mild BPD versus moderate to severe BPD. 58 ELBW infants were included in the study. 24 (41%) were diagnosed with moderate to severe BPD, while 34 (59%) were diagnosed with no to mild BPD. Severity of BPD was fairly discriminated by FiO₂ at DOL 11-14, but not with CO-Hb levels at any point within the first 14 DOL. The role and mechanism of CO-Hb production in this population need to be further studied.

Role of the SENP1-SIRT1 pathway in hyperoxia-induced alveolar epithelial cell injury

Bronchopulmonary dysplasia (BPD) is a common complication in preterm infants, and its main pathogenesis partly involves oxidative stress. A large number of studies have shown that silent information regulator 1 (SIRT1) plays a protective role in oxidative stress. SUMO-specific protease 1 (SENP1) is vital in the nucleoplasmic distribution of SIRT1 under stress. However, whether the SENP1-SIRT1 pathway is involved in the hyperoxic lung injury is unknown. Therefore, this study aimed to explore the role and related mechanisms of the SENP1-SIRT1 pathway in hyperoxic lung injury. Peripheral blood mononuclear cells (PBMCs) from infants with BPD and SENP1-silenced alveolar epithelial cells were used as research models. PBMCs were isolated from the peripheral blood of premature infants. Next, the SENP1-silenced human alveolar epithelial cells were used to verify the role of the SENP1-SIRT1 pathway in vitro. The results indicated that the ROS level and the mRNA and protein expression of SENP1 increased in PBMCs of infants with BPD, but the expression of SIRT1 decreased in the nucleus and increased in the cytoplasm, and then the expression of acetyl-p53 (Ac-p53) increased. In the hyperoxic alveolar epithelial cell injury model, it seemed that hyperoxia could induce the same variation trend in the SENP1-SIRT1 pathway as in infants with BPD and then increased the expression of Ac-p53 and BAX, and cell apoptosis. Furthermore, silencing SENP1 could alleviate these hyperoxia-induced changes. These results suggested that SENP1 played an important role in hyperoxia-induced lung injury. It could regulate the expression and nucleoplasmic distribution of SIRT1 to inhibit its deacetylase activity, and then promoted cell apoptosis. Hence, SENP1 may become a potential intervention target of BPD in the future.

Randomized trial of oxygen weaning strategies following chest compressions during neonatal resuscitation

BACKGROUND

The Neonatal Resuscitation Program (NRP) recommends using 100% O2 during chest compressions and adjusting FiO2 based on SpO2 after return of spontaneous circulation (ROSC). The optimal strategy for adjusting FiO2 is not known.

METHODS

Twenty-five near-term lambs asphyxiated by umbilical cord occlusion to cardiac arrest were resuscitated per NRP. Following ROSC, lambs were randomized to gradual decrease versus abrupt wean to 21% O2 followed by FiO2 titration to achieve NRP SpO2 targets. Carotid blood flow and blood gases were monitored.

RESULTS

Three minutes after ROSC, PaO2 was 229 ± 32 mmHg in gradual wean group compared to 57 ± 13 following abrupt wean to 21% O2 (p < 0.001). PaO2 remained high in the gradual wean group at 10 min after ROSC (110 ± 10 vs. 67 ± 12, p < 0.01) despite similar FiO2 (~0.3) in both groups. Cerebral O2 delivery (C-DO2) was higher above physiological range following ROSC with gradual wean (p < 0.05). Lower blood oxidized/reduced glutathione ratio (suggesting less oxidative stress) was observed with abrupt wean.

CONCLUSION

Weaning FiO2 abruptly to 0.21 with adjustment based on SpO2 prevents surge in PaO2 and C-DO2 and minimizes oxidative stress compared to gradual weaning from 100% O2 following ROSC. Clinical trials with neurodevelopmental outcomes comparing post-ROSC FiO2 weaning strategies are warranted.

IMPACT

In a lamb model of perinatal asphyxial cardiac arrest, abrupt weaning of inspired oxygen to 21% prevents excessive oxygen delivery to the brain and oxidative stress compared to gradual weaning from 100% oxygen following return of spontaneous circulation. Clinical studies assessing neurodevelopmental outcomes comparing abrupt and gradual weaning of inspired oxygen after recovery from neonatal asphyxial arrest are warranted.

The newborn sheep translational model for pulmonary arterial hypertension of the neonate at high altitude

Chronic hypoxia during gestation induces greater occurrence of perinatal complications such as intrauterine growth restriction, fetal hypoxia, newborn asphyxia, and respiratory distress, among others. This condition may also cause a failure in the transition of the fetal to neonatal circulation, inducing pulmonary arterial hypertension of the neonate (PAHN), a syndrome that involves pulmonary vascular dysfunction, increased vasoconstrictor tone and pathological remodeling. As this syndrome has a relatively low prevalence in lowlands (~7 per 1000 live births) and very little is known about its prevalence and clinical evolution in highlands (above 2500 meters), our understanding is very limited. Therefore, studies on appropriate animal models have been crucial to comprehend the mechanisms underlying this pathology. Considering the strengths and weaknesses of any animal model of human disease is fundamental to achieve an effective and meaningful translation to clinical practice. The sheep model has been used to study the normal and abnormal cardiovascular development of the fetus and the neonate for almost a century. The aim of this review is to highlight the advances in our knowledge on the programming of cardiopulmonary function with the use of high-altitude newborn sheep as a translational model of PAHN.

Comparison of coenzyme Q10 or fish oil for prevention of intermittent hypoxia-induced oxidative injury in neonatal rat lungs

BACKGROUND

Neonatal intermittent hypoxia (IH) results in oxidative distress in preterm infants with immature antioxidant systems, contributing to lung injury. Coenzyme Q10 (CoQ10) and fish oil protect against oxidative injury. We tested the hypothesis that CoQ10 is more effective than fish oil for prevention of IH-induced lung injury in neonatal rats.

METHODS

Newborn rats were exposed to two clinically relevant IH paradigms at birth (P0): (1) 50% O₂ with brief hypoxia (12% O₂); or (2) room air (RA) with brief hypoxia (12% O₂), until P14 during which they were supplemented with daily oral CoQ10, fish oil, or olive oil from P0 to P14. Pups were studied at P14 or placed in RA until P21 with no further treatment. Lungs were assessed for histopathology and morphometry; biomarkers of oxidative stress and lipid peroxidation; and antioxidants.

RESULTS

Of the two neonatal IH paradigms 21%/12% O₂ IH resulted in the most severe outcomes, evidenced by histopathology and morphometry. CoQ10 was effective for preserving lung architecture and reduction of IH-induced oxidative stress biomarkers. In contrast, fish oil resulted in significant adverse outcomes including oversimplified alveoli, hemorrhage, reduced secondary crest formation and thickened septae. This was associated with elevated oxidants and antioxidants activities.

CONCLUSIONS

Data suggest that higher FiO₂ may be needed between IH episodes to curtail the damaging effects of IH, and to provide the lungs with necessary respite. The negative outcomes with fish oil supplementation suggest oxidative stress-induced lipid peroxidation.

Polyphenols and IUGR Pregnancies: Effects of the Antioxidant Hydroxytyrosol on Brain Neurochemistry and Development in a Porcine Model

Supplementation of a mother’s diet with antioxidants, such as hydroxytyrosol (HTX), has been proposed to ameliorate the adverse phenotypes of fetuses at risk of intrauterine growth restriction. In the present study, sows were treated daily with or without 1.5 mg of HTX per kilogram of feed from day 35 of pregnancy (at 30% of total gestational period), and individuals were sampled at three different ages: 100-day-old fetuses and 1-month- and 6-month-old piglets. After euthanasia, the brain was removed and the hippocampus, amygdala, and prefrontal cortex were dissected. The profile of the catecholaminergic and serotoninergic neurotransmitters (NTs) was characterized and an immunohistochemical study of the hippocampus was performed. The results indicated that maternal supplementation with HTX during pregnancy affected the NT profile in a brain-area-dependant mode and it modified the process of neuron differentiation in the hippocampal CA1 and GD areas, indicating that cell differentiation occurred more rapidly in the HTX group. These effects were specific to the fetal period, concomitantly with HTX maternal supplementation, since no major differences remained between the control and treated groups in 1-month- and 6-month-old pigs.

The relationship between intermittent hypoxemia events and neural outcomes in neonates

This brief review examines 1) patterns of intermittent hypoxemia in extremely preterm infants during early postnatal life, 2) the relationship between neonatal intermittent hypoxemia exposure and outcomes in both human and animal models, 3) potential mechanistic pathways, and 4) future alterations in clinical care that may reduce morbidity. Intermittent hypoxemia events are pervasive in extremely preterm infants (<28 weeks gestation at birth) during early postnatal life. An increased frequency of intermittent hypoxemia events has been associated with a range of poor neural outcomes including language and cognitive delays, motor impairment, retinopathy of prematurity, impaired control of breathing, and intraventricular hemorrhage. Neonatal rodent models have shown that exposure to short repetitive cycles of hypoxia induce a pathophysiological cascade. However, not all patterns of intermittent hypoxia are deleterious and some may even improve neurodevelopmental outcomes. Therapeutic interventions include supplemental oxygen, pressure support and pharmacologic drugs but prolonged hyperoxia and pressure exposure have been associated with cardiopulmonary morbidity. Therefore, it becomes imperative to distinguish high risk from neutral and/or even beneficial patterns of intermittent hypoxemia during early postnatal life. Identification of such patterns could improve clinical care with targeted interventions for high-risk patterns and minimal or no exposure to treatment modalities for low-risk patterns.

Microarray and qPCR Analysis of Mitochondrial Metabolism Activation during Prenatal and Early Postnatal Development in Rats and Humans with Emphasis on CoQ10 Biosynthesis

At the end of the mammalian intra-uterine foetal development, a rapid switch from glycolytic to oxidative metabolism must proceed. Using microarray techniques, qPCR, enzyme activities and coenzyme Q content measurements, we describe perinatal mitochondrial metabolism acceleration in rat liver and skeletal muscle during the perinatal period and correlate the results with those in humans. Out of 1546 mitochondrial genes, we found significant changes in expression in 1119 and 827 genes in rat liver and skeletal muscle, respectively. The most remarkable expression shift occurred in the rat liver at least two days before birth. Coenzyme Q-based evaluation in both the rat model and human tissues showed the same trend: the total CoQ content is low prenatally, significantly increasing after birth in both the liver and skeletal muscle. We propose that an important regulator of rat coenzyme Q biosynthesis might be COQ8A, an atypical kinase involved in the biosynthesis of coenzyme Q. Our microarray data, a total of 16,557 RefSeq (Entrez) genes, have been deposited in NCBI's Gene Expression Omnibus and are freely available to the broad scientific community. Our microarray data could serve as a suitable background for finding key factors regulating mitochondrial metabolism and the preparation of the foetus for the transition to extra-uterine conditions.

Red cell distribution width as a predictor for bronchopulmonary dysplasia in premature infants

Bronchopulmonary dysplasia (BPD) is the most common morbidity complicating preterm birth. Red blood cell distribution width (RDW), a measure of the variation of red blood cell size, could reflect oxidative stress and chronic inflammation in many diseases such as cardiovascular, pulmonary, and other diseases. The objectives of the present study were to evaluate perinatal factors affecting RDW and to validate whether RDW could be a potential biomarker for BPD. A total of 176 preterm infants born at < 30 weeks were included in this study. They were categorized into BPD (n = 85) and non-BPD (n = 91) infants. RDW at birth and 14 days and 28 days of life (DOL 14, DOL 28) were measured. Clinical data were obtained from all subjects at Fukushima Medical University (Fukushima, Japan). The mean RDW at birth, DOL 14 and DOL 28 were 16.1%, 18.6%, 20.1%, respectively. Small for gestational age (SGA), chorioamnionitis (CAM), hypertensive disorders of pregnancy (HDP), gestational age and birth weight were significantly associated with RDW at birth. SGA, BPD and red blood cell (RBC) transfusion before DOL 14 were associated with RDW at DOL 14. BPD and RBC transfusion before DOL 14 were associated with RDW at DOL 28. Compared with non-BPD infants, mean RDW at DOL 14 (21.1% vs. 17.6%, P < 0.001) and DOL 28 (22.2% vs. 18.2%, P < 0.001) were significantly higher in BPD infants. Multivariate analysis revealed that RDW at DOL 28 was significantly higher in BPD infants (P = 0.001, odds ratio 1.63; 95% CI 1.22–2.19). Receiver operating characteristic analysis for RDW at DOL 28 in infants with and without BPD yielded an area under the curve of 0.87 (95% CI 0.78–0.91, P < 0.001). RDW at DOL 28 with mild BPD (18.1% vs. 21.3%, P < 0.001), moderate BPD (18.1% vs. 21.2%, P < 0.001), and severe BPD (18.1% vs. 24.0%, P < 0.001) were significantly higher than those with non-BPD, respectively. Furthermore, there are significant differences of RDW at DOL 28 among mild, moderate, and severe BPD. In summary, we conclude that RDW at DOL 28 could serve as a biomarker for predicting BPD and its severity. The mechanism by which RDW at DOL 28 is associated with the pathogenesis of BPD needs further elucidation.

Pharmacodynamic Effects of Standard versus High Caffeine Doses in the Developing Brain of Neonatal Rats Exposed to Intermittent Hypoxia

(1) Background: Caffeine citrate, at standard doses, is effective for reducing the incidence of apnea of prematurity (AOP) and may confer neuroprotection and decrease neonatal morbidities in extremely low gestational age neonates (ELGANs) requiring oxygen therapy. We tested the hypothesis that high-dose caffeine (HiC) has no adverse effects on the neonatal brain. (2) Methods: Newborn rat pups were randomized to room air (RA), hyperoxia (Hx) or neonatal intermittent hypoxia (IH), from birth (P0) to P14 during which they received intraperitoneal injections of LoC (20 mg/kg on P0; 5 mg/kg/day on P1-P14), HiC (80 mg/kg; 20 mg/kg), or equivalent volume saline. Blood gases, histopathology, myelin and neuronal integrity, and adenosine receptor reactivity were assessed. (3) Results: Caffeine treatment in Hx influenced blood gases more than treatment in neonatal IH. Exposure to neonatal IH resulted in hemorrhage and higher brain width, particularly in layer 2 of the cerebral cortex. Both caffeine doses increased brain width in RA, but layer 2 was increased only with HiC. HiC decreased oxidative stress more effectively than LoC, and both doses reduced apoptosis biomarkers. In RA, both caffeine doses improved myelination, but the effect was abolished in Hx and neonatal IH. Similarly, both doses inhibited adenosine 1A receptor in all oxygen environments, but adenosine 2A receptor was inhibited only in RA and Hx. (4) Conclusions: Caffeine, even at high doses, when administered in normoxia, can confer neuroprotection, evidenced by reductions in oxidative stress, hypermyelination, and increased Golgi bodies. However, varying oxygen environments, such as Hx or neonatal IH, may alter and modify pharmacodynamic actions of caffeine and may even override the benefits caffeine.

Developmental programming of cardiovascular function: a translational perspective

The developmental origins of health and disease (DOHaD) is a concept linking pre- and early postnatal exposures to environmental influences with long-term health outcomes and susceptibility to disease. It has provided a new perspective on the etiology and evolution of chronic disease risk, and as such is a classic example of a paradigm shift. What first emerged as the 'fetal origins of disease', the evolution of the DOHaD conceptual framework is a storied one in which preclinical studies played an important role. With its potential clinical applications of DOHaD, there is increasing desire to leverage this growing body of preclinical work to improve health outcomes in populations all over the world. In this review, we provide a perspective on the values and limitations of preclinical research, and the challenges that impede its translation. The review focuses largely on the developmental programming of cardiovascular function and begins with a brief discussion on the emergence of the 'Barker hypothesis', and its subsequent evolution into the more-encompassing DOHaD framework. We then discuss some fundamental pathophysiological processes by which developmental programming may occur, and attempt to define these as 'instigator' and 'effector' mechanisms, according to their role in early adversity. We conclude with a brief discussion of some notable challenges that hinder the translation of this preclinical work.