A novel approach to study oxidative stress in neonatal respiratory distress syndrome

Oxidation products of proteins in plasma of newborns reflect damage inflicted by O2 supplementation and correlate with gestational age

Treatment of neonates, and especially preterm newborns, with supplementary O2, can result in oxidative stress and both short- and long-term health complications. Oxidation products formed on proteins, which are the principal targets of reactive species in plasma, can be used to assess damage arising from O2 therapy. We hypothesized that this may be particularly relevant for preterm neonates. Oxidation products formed on proteins in the plasma of term and preterm newborns were quantified to assess their possible use as biomarkers. Plasma samples from 114 term and preterm neonates with and without O2 supplementation (fraction of inspired oxygen, FiO2 > 21 % and 21 %, respectively) were analyzed. Total protein content and protein carbonyls were determined spectrophotometrically, whilst specific oxidation products from Tyr, Trp and Met were quantified using liquid chromatography coupled to mass detection (LC-MS). Kynurenine (Kyn), N-formylkynurenine (NFKyn), dihydroxydiphenylalanine (DOPA), 3-nitrotyrosine (3-NTyr), methionine sulfoxide (MetSO) and di-tyrosine (di-Tyr) were assessed in their protein-bound form. Alcohols, hydroperoxides and dimers of Trp were also investigated. Carbonyl groups, as well as 3-NTyr and MetSO, showed statistical differences between term and preterm neonates. However, only MetSO was sensitive to O2 supplementation in both term and preterm subjects. The plasma levels of these products showed an inverse association with gestational age. The advantages and limitations of these products as biomarkers of protein oxidation, and the experimental procedures needed to quantify these accurately, should be considered when designing future clinical investigations.

Oxidative Stress in Pregnancy

Recent years have seen an increased interest in the role of oxidative stress (OS) in pregnancy. Pregnancy inherently heightens susceptibility to OS, a condition fueled by a systemic inflammatory response that culminates in an elevated presence of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the circulatory system. The amplified OS in pregnancy can trigger a series of detrimental outcomes such as underdevelopment, abnormal placental function, and a host of pregnancy complications, including pre-eclampsia, embryonic resorption, recurrent pregnancy loss, fetal developmental anomalies, intrauterine growth restriction, and, in extreme instances, fetal death. The body's response to mitigate the uncontrolled increase in RNS/ROS levels requires trace elements that take part in non-enzymatic and enzymatic defense processes, namely, copper (Cu), zinc (Zn), manganese (Mn), and selenium (Se). Determination of ROS concentrations poses a challenge due to their short half-lives, prompting the use of marker proteins, including malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), and glutathione (GSH). These markers, indicative of oxidative stress intensity, can offer indirect assessments of pregnancy complications. Given the limitations of conducting experimental studies on pregnant women, animal models serve as valuable substitutes for in-depth research. This review of such models delves into the mechanism of OS in pregnancy and underscores the pivotal role of OS markers in their evaluation.

Lipid Peroxidation and Antioxidative Capacity Are Unaltered in Transitional Breast Milk Exposed to Light from Women Giving Birth to Preterm Infants before 32 Weeks of Gestation

Breast milk (BM) is the primary nutrition for infants and has a high content of lipids. Preterm infants receive expressed BM via tube feeding, and they are frequently treated with phototherapy. When parenteral nutrition (PN) is exposed to light and/or phototherapy, lipid peroxidation (LPO) increases. By light-protecting PN, morbidity and mortality are reduced in preterm infants through the reduction of oxidative stress. We aimed to investigate whether light-protecting breast milk could reduce LPO. Twelve mothers giving birth to a preterm infants of less than 32 weeks of gestational age were included. Transitional BM was collected and divided into three study groups; light-protected, ward light and phototherapy light. Baseline samples were collected after expression and the exposures started within one hour. Feeding syringe samples were exposed to light for 30 up to 360 min. Nasogastric tube samples were run through a tube under the same light conditions. Samples were stored in -80 °C until analyses of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) and total antioxidant capacity (TAC). There were no significant differences in MDA, 4-HNE or TAC levels observed between the different study groups. This study indicates that the light exposure of expressed transitional BM does not affect LPO and the levels of MDA, 4-HNE or TAC.

Biomarkers of Oxidative Stress in Healthy Infants within the First Three Days after Birth

The clinical relevance of stress biomarkers in newborns is well established. Currently, oxidative stress (OS) parameters are seen to play an important role in neonatal resuscitation guidelines, and a link has been observed between the amount of oxygen delivered and the level of OS and the development of various pathologies. The aim of the current study was to investigate changes in neonatal plasma and urine OS status during the first hours after birth. A lower antioxidant capacity (TAC) and higher levels of malondialdehyde in blood were observed in newborns at the time of birth compared with results 48 h postnatally. The urine revealed a significant and progressive increase in TAC and creatinine during the first 36 h of life, with a progressive decline thereafter. Meanwhile, malondialdehyde in urine samples showed no significant differences over time. Overall, the correlation between blood and urine parameters was poor, except for the relationship between umbilical vein glutathione reduced/oxidized ratio and urine malondialdehyde (r = 0.7; p = 0.004) and between TAC in the umbilical artery and urine (r = -0.547; p = 0.013). The biomarkers evaluated in this study could be established as reference values for neonatal OS.

Women with preeclampsia exposed to air pollution during pregnancy: Relationship between oxidative stress and neonatal disease - Pilot study

Oxidative imbalance as a pathophysiological mechanism has been reported as an adverse outcome in pregnant women who develop preeclampsia and in their newborns. Furthermore, emerging evidence suggests the same mechanism by which air pollutants may exert their toxic effects. Therefore, the objective of the study was to evaluate the biomarkers of oxidative stress and their relationship with neonatal disease in premature newborns from mothers with preeclampsia exposed to air pollution during pregnancy. The data of air pollutants (PM2.5, PM10 and ozone) were collected at fixed monitoring stations. Oxidative and antioxidant status markers were obtained through special techniques in women with preeclampsia and in umbilical cord blood of their premature newborns. The oxidative stress markers were significantly higher in women with preeclampsia and their newborns who were exposed to higher levels of ambient air pollutants in the first and second trimester of pregnancy. Neonatal diseases are associated with preeclampsia in pregnancies, specifically intrauterine growth restriction (IUGR) and necrotizing enterocolitis (NEC). A significant correlation was identified in the levels of prooxidant agents and antioxidant enzyme activity in the presence of neonatal diseases associated with preeclampsia. There is increased oxidative damage in both the maternal and fetal circulation in women who develop preeclampsia exposed to air pollution during pregnancy. Therefore, these pregnancies complicated by preeclampsia have a greater adverse outcome as neonatal disease in the preterm infant.

Association between thiol-disulfide hemostasis and transient tachypnea of the newborn in late-preterm and term infants

BACKGROUND

Transient tachypnea of the newborn (TTN), which is the most common respiratory disease in the neonatal period, increases respiratory workload in newborns. We purposed to evaluate the oxidative stress (OS) status and thiol disulfide hemostasis in late preterm and term newborns with TTN in this study.

METHODS

The study was carried out in a single-centre neonatal intensive care unit to investigate the effect of continuous airway positive pressure (CPAP) on the oxidative system in newborns with TTN. Thiol (native and total) and disulfide levels, total antioxidant and oxidant status (TAS/TOS) and Oxidative stress index (OSI) levels were measured.

RESULTS

Total thiol levels measured before treatment was 429.5 (369.5-487) µmol/L in the late preterm group and 425 (370-475) µmol/L in the term group (p = 0.741). We found significant changes in TOS, OSI and TAS levels after CPAP treatment in the late preterm group (p < 0.001, p < 0.001, p = 0.012 respectively). It was also found that the disulfide level, which was 26.2 (19.2-31.7) before the treatment, decreased to 19.5 (15.5-28.75) after the treatment (p = 0.001) in late preterms.

CONCLUSION

CPAP treatment reduced the OS status burden associated with TTN in neonates. The late preterm newborns with TTN are more affected by OS and increased OS levels decrease with CPAP treatment.

Antenatal and Postnatal Sequelae of Oxidative Stress in Preterm Infants: A Narrative Review Targeting Pathophysiological Mechanisms

The detrimental effects of oxidative stress (OS) can start as early as after conception. A growing body of evidence has shown the pivotal role of OS in the development of several pathological conditions during the neonatal period, which have been therefore defined as OS-related neonatal diseases. Due to the physiological immaturity of their antioxidant defenses and to the enhanced antenatal and postnatal exposure to free radicals, preterm infants are particularly susceptible to oxidative damage, and several pathophysiological cascades involved in the development of prematurity-related complications are tightly related to OS. This narrative review aims to provide a detailed overview of the OS-related pathophysiological mechanisms that contribute to the main OS-related diseases during pregnancy and in the early postnatal period in the preterm population. Particularly, focus has been placed on pregnancy disorders typically associated with iatrogenic or spontaneous preterm birth, such as intrauterine growth restriction, pre-eclampsia, gestational diabetes, chorioamnionitis, and on specific postnatal complications for which the role of OS has been largely ascertained (e.g., respiratory distress, bronchopulmonary dysplasia, retinopathy of prematurity, periventricular leukomalacia, necrotizing enterocolitis, neonatal sepsis). Knowledge of the underlying pathophysiological mechanisms may increase awareness on potential strategies aimed at preventing the development of these conditions or at reducing the ensuing clinical burden.

Human Milk Feeding for Septic Newborn Infants Might Minimize Their Exposure to Ventilation Therapy

Background. It has been well established that human milk feeding contributes to limiting lung diseases in vulnerable neonates. The primary aim of this study was to compare the need for mechanical ventilation between human milk-fed neonates with sepsis and formula-fed neonates with sepsis. Methods. All late preterm and full-term infants from a single center with sepsis findings from 2002 to 2017 were identified. Data on infant feeding during hospital admission were also recorded. Multivariate logistic regression analyses were performed to assess the impact of feeding type on ventilation support and main neonatal morbidities. Results. The total number of participants was 322 (human milk group = 260; exclusive formula group = 62). In the bivariate analysis, 72% of human milk-fed neonates did not require oxygen therapy or respiratory support versus 55% of their formula-fed counterparts (p < 0.0001). Accordingly, invasive mechanical ventilation was required in 9.2% of any human milk-fed infants versus 32% of their exclusively formula-fed counterparts (p = 0.0085). These results held true in multivariate analysis; indeed, any human milk-fed neonates were more likely to require less respiratory support (OR = 0.44; 95% CI:0.22, 0.89) than those who were exclusively formula-fed. Conclusion. Human milk feeding may minimize exposure to mechanical ventilation.

Evaluation of Genetic Polymorphisms of the Antioxidant Enzymes and Biomarkers of Oxidative Stress in Preterm Neonates With Respiratory Distress Syndrome Receiving External Surfactant

Background:

Preterm neonates, particularly extremely preterm, are susceptible to respiratory distress syndrome (RDS) due to surfactant deficiency. Single nucleotide polymorphisms (SNPs) in the antioxidant enzymes influence the balance between antioxidant and oxidative stress molecules.

Objectives:

To ascertain the role of SNPs of antioxidant enzymes and oxidative stress biomarkers in preterm neonates with RDS.

Design:

Observational, cross-sectional study.

Methods:

Preterm neonates diagnosed with RDS receiving external surfactant within 24 hours were considered as the cases and those without RDS were the control group. Umbilical cord blood and peripheral blood samples before administering surfactant (day 1), and on days 2 and 3 were collected. Plasma malondialdehyde, 8-hydroxy-2-deoxy guanosine (8-OH-dG), advanced oxidation protein products (AOPP), total antioxidant capacity (TAC), visfatin, reduced glutathione, and chaperonin 60 were evaluated using enzyme-linked immunosorbent assay. SNPs in manganese superoxide dismutase (MnSOD), copper/zinc superoxide dismutase (Cu/Zn SOD), glutathione peroxidase (GPX1 and GPX3), catalase (CAT), glutathione S-transferase (GSTP1) were evaluated using real-time polymerase-chain-reaction. The receiver-operating characteristics curve was used for predicting the accuracy of biomarkers using the area under the curve (AUC) and 95% confidence intervals (95% CI).

Results:

GSTP1, MnSOD, and eNOS (rs1799983) SNPs were observed to significantly influence the oxidative biomarker concentrations in the entire study population. SNPs in GSTP1, MnSOD, and eNOS (rs1799983) were significantly associated with differences in oxidative stress biomarkers. MnSOD (rs4880) significantly increased the risk of pulmonary complications in neonates with RDS. DNA damage product (8-OH-dG) concentrations before surfactant administration has the best predictive accuracy (AUC: 0.8; 95% CI: 0.7-1; P = .001) for pulmonary complications with a cut-off value of 5008.8 pg/mL. TAC concentrations are significantly greater on day 2 and day 3 amongst neonates receiving surfactant compared to the control group. AOPP in the umbilical cord blood was observed to significantly predict the severity of RDS (AUC: 0.8; 95% CI: 0.6-1; P = .01) with an optimal cut-off value of 88.78 µmol/L.

Conclusion:

We observed that SNPs in eNOS and MnSOD significantly influence the production of oxidative stress biomarkers in preterm neonates. Baseline 8-OH-dG concentrations best predict the risk of pulmonary complications and AOPP concentrations in the umbilical cord blood predict the risk of RDS severity.

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.

Oxidative Stress in Preterm Newborns

Preterm babies are highly susceptible to oxidative stress (OS) due to an imbalance between the oxidant and antioxidant systems. The generation of free radicals (FR) induces oxidative damage to multiple body organs and systems. OS is the main factor responsible for the development of typical premature infant diseases, such as bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, kidney damage, eryptosis, and also respiratory distress syndrome and patent ductus arteriosus. Many biomarkers have been detected to early identify newborns at risk of developing a free radical-mediated disease and to investigate new antioxidant strategies. This review reports the current knowledge on OS in the preterm newborns and the newest findings concerning the use of OS biomarkers as diagnostic tools, as well as in implementing antioxidant therapeutic strategies for the prevention and treatment of these diseases and their sequelae.

Efficacy comparison of high-frequency oscillatory ventilation with continuous nasal positive airway pressure in neonatal respiratory distress syndrome treatment

OBJECTIVES

To compare the treatment efficacy of high-frequency oscillatory ventilation (HFOV) with nasal continuous positive airway pressure (NCPAP) in the treatment of neonatal respiratory distress syndrome (NRDS) and its effect on the expression of high-mobility group protein B1 (HMGB1).

METHODS

A total of 180 infants with NRDS admitted to our hospital were included and randomly assigned into the HFOV group (receiving conventional therapy and HFOV), the NCPAP group (receiving conventional therapy and NCPAP), and the conventional group (receiving conventional therapy). Qi and blood indicators, heart rate, respiratory frequency, PCO₂, and PaO₂ were observed and recorded before and after treatment, together with complications after treatment. ELISA was performed for HMGB1 Results: A distinctly lower partial pressure of carbon dioxide (PCO₂) but higher arterial partial pressure of oxygen (PaO₂) was observed in the HFOV and NCPAP groups than in the conventional group (P < 0.05), whereas infants in the HFOV group exhibited slight differences in these two indicators from their counterparts in the NCPAP group (P > 0.05). The serum HMGB1 levels in both groups were significantly higher than those in the conventional group (P < 0.05).

DISCUSSION

Both HFOV and NCPAP are feasible in the treatment of NRDS and may play a role in the inhibition of HMGB1.

Oxidative Stress at Birth Is Associated with the Concentration of Iron and Copper in Maternal Serum

Oxidative stress (OS) in the foetal and neonatal periods leads to many disorders in newborns and in later life. The nutritional status of pregnant women is considered to be one of the key factors that triggers OS. We investigated the relationship between the concentration of selected mineral elements in the blood of pregnant women and the concentration of 3′nitrotyrosine (3′NT) as a marker of OS in the umbilical cord blood of newborns. The study group consisted of 57 pregnant women and their newborn children. The concentrations of magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn) and copper (Cu) in maternal serum (MS) were measured by the flame atomic absorption/emission spectrometry (FAAS/FAES) method. The concentration of 3′NT in umbilical cord serum (UCS) of newborns was determined by the ELISA method. A positive correlation between MS Fe and UCS 3′NT in male newborns was shown (rho = 0.392, p = 0.053). Significantly higher UCS 3′NT was demonstrated in newborns, especially males, whose mothers were characterized by MS Fe higher than 400 μg/dL compared to those of mothers with MS Fe up to 300 μg/dL (p < 0.01). Moreover, a negative correlation between the MS Cu and UCS 3′NT in male newborns was observed (rho = −0.509, p = 0.008). Results of the study showed the need to develop strategies to optimize the nutritional status of pregnant women. Implementation of these strategies could contribute to reducing the risk of pre- and neonatal OS and its adverse health effects in the offspring.

Novel predictor markers for early differentiation between transient tachypnea of newborn and respiratory distress syndrome in neonates

Neonatal Respiratory Distress Syndrome (RDS) and Transient Tachypnea of newborn (TTN) are common similar neonatal respiratory diseases. Study the early predictor markers in differentiation between TTN and RDS in neonates. A prospective case control study which was done in Neonatal Intensive Care Unit (NICU) of Tanta University Hospital (TUH) from September 2016 to March 2018. Three groups of neonates were included in the study: RDS group (45 neonates), TTN group (45 neonates), and control group (45 healthy neonates). There were statistically significant difference (SSD) between our studied three groups as regard serum Malondialdehyde (MDA), Superoxide dismutase SOD, Lactate dehydrogenase (LDH), and blood PH and P-values were 0.001* for these comparative parameters. The ROC curve of RDS cases revealed that the serum MDA Cut off, sensitivity and specificity were 1.87 mmol/L, 98%, 96%, respectively which had the highest sensitivity and specificity followed by the serum SOD then the serum LDH and lastly the blood PH while in TTN cases, the serum MDA Cut off, sensitivity and specificity were 0.74 mmol/L, 96%, 93%, respectively then the serum SOD then the serum LDH and lastly the blood PH. Serum MDA, SOD, LDH, and PH had a beneficial role as early predictors in differentiation between TTN and RDS in neonates.

Biomarkers of Oxidative Stress for Neonatal Lung Disease

The transition from prenatal to postnatal life causes a significant increase in arterial oxygen tension and the activation of metabolic pathways enabling the newborn's adaptation to the extra-uterine environment. The balance between pro-oxidant and anti-oxidant systems is critical to preserve cellular functions. Indeed, oxidative stress (OS) occurs when the production of free radicals is not balanced by the activity of intracellular antioxidant systems, contributing to cellular and tissue damage. Perinatal OS may have serious health consequences during the postnatal period and later in life. Namely, OS has been recognized as the major cause of lung injury in newborns, especially those preterm born, due to their immature lung and antioxidant systems. The development of OS biomarkers has gained increasing research interest since they may provide useful insights about pathophysiological pathways underlying OS-mediated pulmonary diseases in newborns. Moreover, their implementation in clinical settings may help to early identify high risk-newborns and to provide targeted treatment. Ideally, a biomarker should demonstrate ease of use, biological validity and reproducibility, high sensitivity and specificity. However, none of the clinically validated biomarkers so far have been qualified for neonatal lung disease. Additionally, the complex technical procedures and the high cost of such determinations have hampered the use of OS biomarkers in clinical practice. This review aims to evaluate the current evidence on the application of biomarkers of oxidative stress for neonatal lung disease and exploring the most relevant issues affecting their implementation in practice, as well as the associated evidence gaps and research limitations.

Oxidative stress biomarkers in the perinatal period: Diagnostic and prognostic value

Perinatal oxidative stress (OS) is involved in the physiopathology of many pregnancy-related disorders and is largely responsible for cellular, tissue and organ damage that occur in the perinatal period especially in preterm infants, leading to the so-called "free-radicals related diseases of the newborn". Reliable biomarkers of lipid, protein, DNA oxidation and antioxidant power in the perinatal period have been demonstrated to show specificity for the disease, to have prognostic power or to correlate with disease activity. Yet potential clinical applications of oxidative stress biomarkers in neonatology are still under study. Overcoming the technical and economic difficulties that preclude the use of OS biomarkers in the clinical practice is a challenge that needs to be overcome to identify high-risk subjects and to predict their short- and long-term outcome. Cord blood, urine and saliva represent valid and ethically acceptable biological samples for investigations in the perinatal period.

Relationship Between Oxidative Stress Markers and Endothelin-1 Levels in Newborns of Different Gestational Ages

Oxidative stress results from excessive reactive oxygen species formation and/or inadequate antioxidant defense. Premature and critically ill infants are especially susceptible due to an immature intrinsic antioxidant system that cannot fully compensate for a free radical load. Oxidative stress is also associated with endothelial dysfunction and alterations in Endothelin-1 (ET-1) signaling pathways. However, the effects of the complex interaction between oxidative stress and ET-1 in newborns are not well-understood. The objective of this pilot study was to determine the relationship between levels of common oxidative stress biomarkers [glutathione (GSH), malondialdehyde (MDA)] and ET-1 in newborns of different gestational ages. In a level IV NICU, 63 neonates were prospectively enrolled and divided into groups based on gestational age at birth: Early Preterm (24 0/7-30 6/7 weeks), Late Preterm (31 0/7-36 6/7 weeks), and Term (37 0/7-42 weeks). Umbilical cord (1.5 mL) and 24(±4) h of life (24 h) (1 mL) blood samples were collected for GSH, MDA, and ET-1 analyses. GSH, MDA, and ET-1 were determined using established methodology. Mean cord MDA levels for all age groups, Early Preterm (2.93 ± 0.08 pg/ml), Late Preterm (2.73 ± 0.15 pg/ml), and Term (2.92 ± 0.13 pg/ml), were significantly higher than those at 24 h of life (p < 0.001). Mean cord ET-1 levels were significantly higher than 24 h samples in both Early and Late Preterm groups (p < 0.05). Cord and 24 h ET-1 levels did not correlate with MDA and GSH levels at birth (r² = 0.03, p > 0.05 and r² = 0.001, p > 0.05, respectively) or 24 h of life (r² = 0.001, p > 0.05 and r² = 0.03, p > 0.05, respectively). Preterm neonates exposed to prenatal corticosteroids (1.87 ± 0.31 pg/ml) had lower cord MDA levels than non-exposed neonates (2.85 ± 0.12 pg/ml) (p < 0.05). Both cord and 24 h OS markers were significantly higher in neonates treated with oxygen therapy (p < 0.005 and p < 0.05, respectively) than those who did not receive supplemental oxygen. Oxidative stress markers (MDA and GSH) and ET-1 levels act independently. MDA is higher in cord blood than at 24 h of life regardless of gestational age. In preterm neonates, ET-1 levels are higher in umbilical cord blood compared to 24 h of life.

Oxidative stress markers in neonatal respiratory distress syndrome: advanced oxidation protein products and 8-hydroxy-2-deoxyguanosine in relation to disease severity

OBJECTIVE

We assessed oxidant-antioxidant status and evaluated the role of lipid peroxidation, oxidative DNA damage, and protein oxidation in the development and severity of neonatal respiratory distress syndrome (RDS).

METHODS

Forty preterm neonates with RDS were compared with another 40 preterm neonates without RDS enrolled as controls. Total antioxidant capacity (TAC), malondialdehyde (MDA), advanced oxidation protein products (AOPPs), 8-hydroxy-2-deoxyguanosine (8-OHdG), and trace elements (copper and zinc) were measured in cord blood (day 0) for all neonates and repeated on day 3 for the RDS group.

RESULTS

Day 0 serum levels of MDA, AOPPs, and 8-OHdG were significantly higher in neonates with RDS than controls with a further increase on day 3. Days 0 and 3 levels of TAC, copper, and zinc were significantly lower in the RDS group compared with controls. Elevated serum levels of 8-OHdG and AOPPs were associated with severe RDS, invasive mechanical ventilation, and high mortality rate. 8-OHdG and AOPPs were positively correlated with MDA, oxygenation index, duration of ventilation, and duration of hospitalization.

CONCLUSIONS

Increased lipid, protein, and DNA oxidation is accompanied by alterations in the antioxidant defense status, which may play a role in the pathogenesis and severity of RDS.

Antioxidant Capacity of Preterm Neonates Assessed by Hydrogen Donor Value

Background and objectives: Premature newborns have a number of oxidative stress-inducing disorders. Antioxidant defense is deficient in premature newborns. Hydrogen donors can be used to evaluate the non-enzymatic antioxidant defense. By measuring hydrogen donors, a group of antioxidants can be assessed: tocopherol, ascorbic acid, and glutathione. These represent the most relevant group of non-enzymatic antioxidants. The main aim of this study was to evaluate the non-enzymatic antioxidant defense capacity of premature newborns by measuring hydrogen donors. Materials and Methods: We evaluated the non-enzymatic antioxidant capacity by hydrogen donor measurement in 24 premature newborns with various oxidative stress-inducing disorders and in 14 premature newborns without oxidative stress-inducing conditions. Statistical analysis was performed using the Statistica program (v. 8, StatSoft, Round Rock, TX, USA). Differences between groups were tested with Wilcoxon matched test for quantitative paired data or Mann-Whitney test for quantitative independent data. The Z test for proportions was used to compare qualitative data among subgroups. Results: Hydrogen donors in the study group had a significantly lower value on the first day of life compared to the value of the control group. Also, the hydrogen donor value in the study group was significantly lower on the first day compared to the third day of life (p < 0.05). Neonates with mild respiratory distress (14 cases) had increased hydrogen donor values on their third day of life compared to the first day of life. Conclusions: The antioxidant capacity is influenced by oxidative stress-inducing disorders. Respiratory distress influenced the hydrogen donor value and antioxidant defense. Antioxidant defense gradually improves after birth according to gestational age.

Biomarkers of oxidative stress in the fetus and in the newborn

The dynamic field of perinatology entails ever-increasing search for molecular mechanisms of neonatal diseases, especially in the domain of fetal growth and neurodevelopmental outcome. There is an urgent need for new molecular biomarkers, to early identify newborn at high risk for developing diseases and to provide new treatment targets. The interest in biomarkers of oxidative stress in perinatal period have begun to grow in the last century, when it was evidenced the importance of the free radicals generation underlying the various disease conditions. To date, interesting researches have been carried out, representing milestones for implementation of oxidative stress biomarkers in perinatal medicine. Use of a panel of "oxidative stress biomarkers", particularly non protein bound iron, advanced oxidative protein products and isoprostanes, may provide valuable information regarding functional pathways underlying free radical mediated diseases of newborns and their early identification and prevention. Here, we will review recent advances and the current knowledge on the application of biomarkers of oxidative stress in neonatal/perinatal medicine including novel biomarker discovery, defining yet unrecognized biologic therapeutic targets, and linking of oxidative stress biomarkers to relevant standard indices and long-term outcomes.

Autism Spectrum Disorders and Perinatal Complications-Is Oxidative Stress the Connection?

Background: Autism spectrum disorders (ASD) are complex psychiatric disorders, with gene environment interaction being in the basis of their etiology. The association of perinatal complications and ASD is well established. Recent findings suggested that oxidative stress and polymorphism in genes encoding antioxidant enzymes might be involved in the development of ASD. Glutathione transferases (GSTs) have an important role in the antioxidant defense system. We aimed to establish whether the predictive effects of prenatal and perinatal complications (as possible oxidative stress inducers) on ASD risk are dependent on GST polymorphisms. Methods: The study included 113 ASD cases and 114 age- and sex group-matched healthy controls. All participants were genotyped for GSTA1, GSTM1, GSTT1, and GSTP1 polymorphisms. The questionnaire regarding prenatal and perinatal risk factors and complications was administered for all the subjects in the study. Results: The evaluated perinatal complications as a group significantly increased the risk of ASD [odds ratio (OR) = 9.415; p = 0.000], as well as individual perinatal complications, such as prematurity (OR = 11.42; p = 0.001), neonatal jaundice (OR = 8.774; p = 0.000), respiratory distress syndrome (OR = 4.835; p = 0.047), and the use of any medication during pregnancy (OR = 2.413; p = 0.03). In logistic regression model, adding GST genotypes did not modify the significant effects found for prematurity and neonatal jaundice as risk factors in ASD. However, there was a significant interaction of GST genotype with medication use during pregnancy and the use of tocolytics during pregnancy, which was predictive of ASD risk only in carriers of GSTM1-null, as opposed to carriers of GSTM1-active genotype. Conclusion: Specific perinatal complications may be significant risk factors for ASD. GSTM1 genotype may serve as a moderator of the effect of some prenatal factors on the risk of ASD such as using medication during pregnancy. It may be speculated that different oxidative stress-related genetic and environmental factors could lead to development of ASD. Apart from etiological mechanisms, possible therapeutic implications in ASD are also discussed.

Oxidative Stress and Anti-Oxidant Markers in Premature Infants with Respiratory Distress Syndrome

BACKGROUND

Neonatal respiratory distress syndrome (RDS) caused by decreased surfactant and structural lung immaturity. The imbalance between oxidative status and antioxidant defence system was suggested to be an important trigger for lung affection with RDS.

AIM

The goal of the current research was to elucidate the significance of the oxidant/ antioxidant status in the pathogenesis of RDS in preterm infants.

PATIENTS AND METHODS

This controlled study included 31 preterm neonates with RDS and 36 healthy preterm neonates. Quantification level of oxidative stress biomarkers; malondialdehyde (MDA) & hydrogen peroxide (H₂O₂) along with antioxidant enzymes activity; catalase (CAT) & superoxide dismutase (SOD) in plasma of healthy premature neonates compared with those with RDS.

RESULTS

status of oxidative stress markers (MDA & H₂O₂) showed a significant increase with decreased levels of antioxidant enzymes activity (CAT & SOD) in neonates with RDS when compared to healthy prematures.

CONCLUSION

The results obtained in this study indicate that the increased oxidative stress accompanied by reduced antioxidant defences may play a significant role in the pathogenesis of respiratory distress in preterm newborns.

The influence factors of neonatal respiratory distress syndrome in Southern China: a case-control study

Objective: To explore the relevant influencing factors of neonatal respiratory distress syndrome (NRDS) in southern China and provide scientific basis for improving the quality of life for neonates.Methods: A retrospective analysis of 320 cases with NRDS neonates admitted from January 2015 to December 2017 in a neonatal department of a Maternal and Child Health Hospital in South China was conducted. Three hundred twenty non-NRDS patients admitted to the same hospital during the same period were also included as control. The basic characteristics were compared and the risk and protective factors for NRDS were evaluated by logistic regression analysis.Results: Univariate analysis showed that the difference in age, gestational age, fetal sex, mode of delivery, asphyxia, intrauterine distress, and gestational diabetes in the case group and the control group were significantly different (p < .05). The multivariate logistic regression analysis revealed that the age of pregnant women (OR ± 1.539, 95% CI ± 1.427-1.660), intrauterine distress (OR ± 2.427, 95% CI ± 1.079-5.458), and gestational diabetes (OR ± 2.881, 95% CI ± 1.271-6.532) were independent risk factors for NRDS. Meanwhile, gestational age (OR ± 0.588, 95% CI ± 0.508-0.681) was an independent protective factor for NRDS.Conclusions: The age of pregnant women, intrauterine distress, and gestational diabetes can increase the risk of NRDS, while long gestational age can reduce the risk of NRDS. Early detection, early diagnosis and early treatment of children with NRDS have achieved the purpose of improving the quality of life of children.

Serum glutathione S-transferase Pi as predictor of the outcome and acute kidney injury in premature newborns

BACKGROUND

The incidence of acute kidney injury (AKI) among the neonates treated at the Neonatal Intensive Care Unit is high with high mortality rates. Glutathione S-transferase (GST) class Pi plays an important role in the protection of cells from cytotoxic and oncogenic agents. The aim of the study was to examine whether the levels of serum glutathione S-transferase Pi (GST Pi) determined after birth have any predictive value for the outcome and development of AKI in premature neonates.

METHODS

The prospective study included 36 premature neonates. The data about morbidity was gathered for all the neonates included in the study. The blood samples were taken in the first 6 h of life and GST Pi levels were measured.

RESULTS

The mean values and standard deviations of GST Pi among the neonates who died and who survived were 1.904 ± 0.4535 vs 1.434 ± 0.444 ng/ml (p = 0.0128). Logistic regression revealed a statistically significant, positive correlation between GST Pi levels and death (p = 0.0180, OR7.5954; CI 1.4148-40.7748).The mean value of GST Pi levels in the neonates with AKI was higher than in neonates without AKI (p = 0.011).

CONCLUSIONS

The conclusion of our study is that high levels of serum GST Pi in the first 6 h after birth are associated with an increased mortality and development of AKI in prematurely born neonates.

Evaluation of dynamic thiol-disulfide homeostasis in very low-birth-weighted preterms

BACKGROUND

Thiols are organic compounds containing sulfhydryl groups which exert antioxidant effects via dynamic thiol-disulfide homeostasis. The shift towards disulfides indicates the presence of oxidative environment. Thiol-disulfide homeostasis has not been evaluated in neonates. We aimed to evaluate dynamic thiol-disulfide homeostasis in preterm infants.

METHODS

Preterm infants with birth weight less than 1500 g (25-32 weeks of gestation) were included. Infants with major congenital anomaly, perinatal asphyxia, twin to twin transfusion and infants who were mechanically ventilated and nil by mouth for more than 3 days or fed with formula, had intraventricular hemorrhage ≥ grade 2 or sepsis, received blood/blood product transfusion or inotrope treatment and developed bronchopulmonary dysplasia or retinopathy of prematurity (≥ stage 3), and died were excluded thereafter. Serum thiol-disulfide homeostasis was evaluated for three times: (Baseline, first week, third week). Serum native thiol, total thiol and disulfide were measured (µmol/Lt), disulfide:native thiol, disulfide:total thiol, and native thiol:total thiol ratios were calculated. Wilcoxon's test was used to analyze the significance of change in measurements. Baseline results were analyzed for gender and mode of delivery.

RESULTS

Eighty preterm infants [1255 (1080-1415) grams] were included. Baseline values were native thiol: 209.54 ± 41.83 µmol/L; total thiol: 251.70 ± 45.82 µmol/L; disulfide: 21.08 ± 7.43 µmol/Lt; disulfide:native thiol: 10.49 ± 4.62; disulfide:total thiol: 8.45 ± 2.93; native thiol:total thiol: 83.10 ± 5.87. Thiol levels increased in each measurement, disulfide and disulfide/thiol ratios increased in the first week, decreased in the third week, ratio of native/total thiol decreased in the first week, increased in the third week. No effect of gender or mode of delivery on baseline thiol-disulfide homeostasis was detected.

CONCLUSIONS

The shift in the thiol-disulfide equilibrium towards disulfides in the first week can be attributed to subjection of infants to many oxidative insults. Furthermore, the thiol predominance in the third week could be explained by the decrease in oxidative events and increase in feeding as a supply of antioxidants. This study, displaying the levels of the dynamic thiol-disulfide homeostasis in preterm infants without obvious risks for increased oxidative stress, may provide acceptable range for thiol-disulfide homeostasis in recovering preterm infants.

Circulating Protein Carbonyls, Antioxidant Enzymes and Related Trace Minerals among Preterms with Respiratory Distress Syndrome

INTRODUCTION

Information about oxidative stress in preterms with Respiratory Distress Syndrome (RDS) is defective, so various researches in this area are required, which may open new roads in understanding the pathogenesis of the disease, hence provide additional helpful therapeutic approaches.

AIM

To assess and compare the plasma level of protein carbonyls as a marker for oxidant status and the antioxidant enzymes; Superoxide Dismutase (SOD) and Glutathione Peroxidase (GPx) and the related trace minerals in the form of Copper (Cu), Zinc (Zn) and Selenium (Se) as markers for antioxidant status, in preterms with and without RDS.

MATERIALS AND METHODS

A hospital-based case-control study was conducted on fifty-seven preterm neonates (37 preterms with RDS and 20 preterms without RDS) admitted to neonatal intensive care unit of Qena University Hospitals after approval of the University Hospital Ethical Committee. Plasma protein carbonyls assay was done using commercially available ELISA assay kit. Plasma Cu, Zn, Se, erythrocyte SOD and GPx activities assays were done using commercially available colorimetric assay kits.

RESULTS

Significant higher plasma levels of protein carbonyls and oxidant/antioxidants ratio (protein carbonyls/{SOD+GPx}) with significant lower plasma levels of Zn, Cu, Se, erythrocyte SOD and GPx activities were found in the preterms with RDS when compared with the preterms without RDS (p<0.001 for all measured markers for both groups). In terms of birth weights and gestational ages, they were negatively correlated with both plasma protein carbonyls and oxidant/antioxidants ratio and positively correlated with plasma copper, zinc, selenium, erythrocyte SOD and GPx activities in a statistically significant manner. Non-significant correlations were found between the measured oxidative stress markers and the severity of RDS.

CONCLUSION

Oxidative stress may have a contributory role in the development of RDS among preterms. Lower birth weight and prematurity may increase the susceptibity to oxidative stress among such patients.

A study of oxidative stress in neonates delivered through meconium-stained amniotic fluid

To estimate the levels of malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OH-dG) in cord blood plasma of newborns born through meconium-stained amniotic fluid (MSAF) and also to find out the correlation between their levels with birth weight and gestation, we measured the cord blood plasma levels of MDA and 8-OH-dG in 59 newborns born through MSAF and 50 newborns born through clear liquor. The levels of cord blood plasma MDA and 8-OH-dG were significantly higher in full-term and late-preterm newborns born through MSAF. On further comparison, it was found that both full-term and late-preterm intrauterine growth restricted (IUGR) neonates had higher levels of these markers as compared to babies born as appropriate for gestational age (AGA) through MSAF. Plasma levels of MDA and 8-OH-dG were significantly correlated with birth weight even after controlling the relationship with gestational age for all cases as well as all full-term cases. These markers are also significantly correlated to each other.

CONCLUSIONS

The present study suggest that the neonates born through MSAF experience higher degrees of oxidative stress, as evidenced by increased levels of cord blood plasma MDA and 8-OH-dG. What is known: • Aspirated meconium has been found to induce free radical generation and cellular damage in animal studies. • Its role in free radical generation and oxidative damage in human neonates is scarce. What is new: • Neonates born through meconium-stained amniotic fluid experience significant oxidative stress.

Biomarkers in Pediatric ARDS: Future Directions

Acute respiratory distress syndrome (ARDS) is common among mechanically ventilated children and accompanies up to 30% of all pediatric intensive care unit deaths. Though ARDS diagnosis is based on clinical criteria, biological markers of acute lung damage have been extensively studied in adults and children. Biomarkers of inflammation, alveolar epithelial and capillary endothelial disruption, disordered coagulation, and associated derangements measured in the circulation and other body fluids, such as bronchoalveolar lavage, have improved our understanding of pathobiology of ARDS. The biochemical signature of ARDS has been increasingly well described in adult populations, and this has led to the identification of molecular phenotypes to augment clinical classifications. However, there is a paucity of data from pediatric ARDS (pARDS) patients. Biomarkers and molecular phenotypes have the potential to identify patients at high risk of poor outcomes, and perhaps inform the development of targeted therapies for specific groups of patients. Additionally, because of the lower incidence of and mortality from ARDS in pediatric patients relative to adults and lack of robust clinical predictors of outcome, there is an ongoing interest in biological markers as surrogate outcome measures. The recent definition of pARDS provides additional impetus for the measurement of established and novel biomarkers in future pediatric studies in order to further characterize this disease process. This chapter will review the currently available literature and discuss potential future directions for investigation into biomarkers in ARDS among children.