Plasma F2-isoprostanes are elevated in newborns and inversely correlated to gestational age

Serum Biomarkers in Patent Ductus Arteriosus in Preterm Infants: A Narrative Review

Background: Patent ductus arteriosus (PDA) in preterm infants presents a significant challenge in neonatal care, marked by ongoing debates about its definition, diagnosis, treatment options, and effects on patient outcomes. Plasma biomarkers assess mediators involved in PDA closure and hemodynamic responses, assisting in identifying newborns at higher risk of developing potentially serious neonatal conditions. The purpose of this review was to investigate the relationship between PDA and various plasma biomarkers used to evaluate and diagnose ductal patency during perinatal life, as outlined in the relevant literature. Methods: We conducted an electronic search of the National Library of Medicine (MEDLINE)/PubMed and Web of Science for relevant studies published up to December 2024, including prospective, retrospective, cohort, and cross-sectional studies, as well as reviews and meta-analyses. The keywords used in the search included "preterm infant", "persistent ductus arteriosus", "patent ductus arteriosus", "PDA", "neonatal biomarkers", "cardiac biomarkers", and "vasoactive biomarkers". Results: Out of the 813 identified articles, 85 were included in our review of cardiac biomarkers: Natriuretic peptides (NPs), Cardiac troponin T (cTnT), vasoactive biomarkers (Mid-regional pro-adrenomedullin (MR-proADM), Endothelin-1 (ET-1), Copeptin, and Isoprostanes (IPs)), and inflammatory biomarkers (Interleukin-6 (IL-6), IL-8, IL-10, Growth Differentiation Factor 15 (GDF-15), Monocyte Chemoattractant Protein-1 (MCP-1/CCL2), Macrophage Inflammatory Protein-1α (MIP-1α/CCL3)) in relation to PDA. Conclusions: Even if research shows a strong correlation between specific biomarkers and echocardiographic parameters in patients with PDA, clinical judgment must take these evaluations into account, particularly when determining whether to treat a PDA. Future research should focus on investigating new biomarkers associated with the underlying mechanisms of perinatal ductus arteriosus dynamics in preterm infants.

Exploratory study evaluating the relationships between perinatal adversity, oxidative stress, and infant neurodevelopment across the first year of life

Early childhood adversity increases risk for negative lifelong impacts on health and wellbeing. Identifying the risk factors and the associated biological adaptations early in life is critical to develop scalable early screening tools and interventions. Currently, there are limited, reliable early childhood adversity measures that can be deployed prospectively, at scale, to assess risk in pediatric settings. The goal of this two-site longitudinal study was to determine if the gold standard measure of oxidative stress, F2-Isoprostanes, is potentially a reliable measure of a physiological response to adversity of the infant and mother. The study evaluated the independent relationships between F2-Isoprostanes, perinatal adversity and infant neurocognitive development. The study included mother-infant dyads born >36 weeks' gestation. Maternal demographic information and mental health assessments were utilized to generate a perinatal cumulative risk score. Infants' development was assessed at 6 and 12 months and both mothers and infants were assayed for F2-isoprostane levels in blood and urine, respectively. Statistical analysis revealed that cumulative risk scores correlated with higher maternal (p = 0.01) and infant (p = 0.05) F2-isoprostane levels at 6 months. Infant F2-isoprostane measures at 2 months were negatively associated with Mullen Scales of Early Learning Composite scores at 12 months (p = 0.04). Lastly, higher cumulative risk scores predicted higher average maternal F2-isoprostane levels across the 1-year study time period (p = 0.04). The relationship between perinatal cumulative risk scores and higher maternal and infant F2-isoprostanes at 6 months may reflect an oxidative stress status that informs a sensitive period in which a biomarker can be utilized prospectively to reveal the physiological impact of early adversity.

Exposure to bisphenol A associated with multiple health-related outcomes in humans: An umbrella review of systematic reviews with meta-analyses

Bisphenol A (BPA), a toxic endocrine disruptor, is widely distributed in the environment, and the effects of BPA exposure on human health outcomes are a critical issue. The objective of this study was to perform an umbrella review of published meta-analyses investigating the associations between BPA exposure and human-related health outcomes. The relevant reports were searched from three electronic databases from inception to July 12, 2023 including PubMed, ScienceDirect, and Embase. The reports that were systematic reviews with meta-analyses investigating the associations between BPA exposure and human health outcomes were included in our review. A total of 14 reports were included in our review. Several human health outcomes related to exposure BPA were investigated including maternal prenatal health, infant health, allergic diseases, kidney disease, metabolic syndromes, polycystic ovary syndrome, earlier puberty, inflammation and immune responses, and thyroid function in neonates. Among these health outcomes, BPA exposure was associated with multiple human health outcomes including preterm birth, allergic diseases, kidney disease, polycystic ovarian syndrome, obesity, type 2 diabetes, cardiovascular disease, hypertension, and inflammation and immune responses (C-reactive protein and interleukin-6). These results showed that BPA exposure has seriously affected human health. To protect human health, World Health Organization should develop meaningful regulations on BPA to decrease the environmental contamination.

Serum pro-oxidant/antioxidant balance in term versus preterm neonates

The oxidant/antioxidant status balance is a process that begins before birth and premature infants are particularly susceptible to oxidative stress. According to the mechanisms of oxidative stress and lack of study in this field, in this prospective study, we aimed to compare the levels of serum pro-oxidant/antioxidant balance (PAB) in preterm versus term babies. This was a prospective cross-sectional study that was performed in Ghaem hospital, a university tertiary hospital, in Mashhad, Iran. The study population included all term and preterm neonates who were admitted to the hospital within birth time. In our study, 324 neonates were included. One hundred ninety-eight neonates were preterm (61.1%) and others were term (38.9%). There was a significant difference between PAB levels in term and preterm neonates. Serum PAB level was significantly lower in preterm neonates rather than in term neonates (21.86 ± 21.01 vs 50.33 ± 31.69; P = .001). There was also a significant negative correlation between PAB levels and gestational age. According to previous investigations, we showed for the first time in our study that PAB is lower in preterm newborns rather than in term ones.

Oxidative Stress Biomarkers and Early Brain Activity in Extremely Preterm Infants: A Prospective Cohort Study

Early brain activity, measured using amplitude-integrated EEG (aEEG), is correlated with neurodevelopmental outcome in preterm newborns. F2-isoprostanes (IPs) are early biomarkers predictive for brain damage. We aimed to investigate the relationship between perinatal IPs concentrations and quantitative aEEG measures in preterm newborns. Thirty-nine infants (gestational age (GA) 24–27 ± 6 weeks) who underwent neuromonitoring using aEEG during the first two days after birth were enrolled. The rate of spontaneous activity transients per minute (SAT rate) and inter-SAT interval (ISI) in seconds were computed. Two postnatal time-points were examined: within 12 h (day 1) and between 24 and 48 h (day 2). IPs were measured in plasma from cord blood (cb-IPs) and between 24 and 48 h (pl-IPs). Multivariable regression analyses were performed to assess the correlation between IPs and brain activity. Cb-IPs were not associated with SAT rate and ISI at day 1. Higher pl-IPs were followed by longer ISI (R = 0.68; p = 0.034) and decreased SAT rate (R = 0.58; p = 0.007) at day 2 after adjusting for GA, FiO2 and IVH. Higher pl-IPs levels are associated with decreased functional brain activity. Thus, pl-IPs may represent a useful biomarker of brain vulnerability in high-risk infants.

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).

Redox Imbalance and Its Metabolic Consequences in Tick-Borne Diseases

One of the growing global health problems are vector-borne diseases, including tick-borne diseases. The most common tick-borne diseases include Lyme disease, tick-borne encephalitis, human granulocytic anaplasmosis, and babesiosis. Taking into account the metabolic effects in the patient's body, tick-borne diseases are a significant problem from an epidemiological and clinical point of view. Inflammation and oxidative stress are key elements in the pathogenesis of infectious diseases, including tick-borne diseases. In consequence, this leads to oxidative modifications of the structure and function of phospholipids and proteins and results in qualitative and quantitative changes at the level of lipid mediators arising in both reactive oxygen species (ROS) and ROS enzyme-dependent reactions. These types of metabolic modifications affect the functioning of the cells and the host organism. Therefore, links between the severity of the disease state and redox imbalance and the level of phospholipid metabolites are being searched, hoping to find unambiguous diagnostic biomarkers. Assessment of molecular effects of oxidative stress may also enable the monitoring of the disease process and treatment efficacy.

Increased Impact of Air Pollution on Lung Function in Preterm versus Term Infants: The BILD Study

Rationale: Infants born prematurely have impaired capacity to deal with oxidative stress shortly after birth. Objectives: We hypothesize that the relative impact of exposure to air pollution on lung function is higher in preterm than in term infants. Methods: In the prospective BILD (Basel-Bern Infant Lung Development) birth cohort of 254 preterm and 517 term infants, we investigated associations of particulate matter ⩽10 μm in aerodynamic diameter (PM₁₀) and nitrogen dioxide with lung function at 44 weeks' postconceptional age and exhaled markers of inflammation and oxidative stress response (fractional exhaled nitric oxide [Fe_NO]) in an explorative hypothesis-driven study design. Multilevel mixed-effects models were used and adjusted for known confounders. Measurements and Main Results: Significant associations of PM₁₀ during the second trimester of pregnancy with lung function and Fe_NO were found in term and preterm infants. Importantly, we observed stronger positive associations in preterm infants (born 32-36 wk), with an increase of 184.9 (95% confidence interval [CI], 79.1-290.7) ml/min [Formula: see text]e per 10-μg/m³ increase in PM₁₀, than in term infants (75.3; 95% CI, 19.7-130.8 ml/min) (p_{prematurity × PM10 interaction} = 0.04, after multiple comparison adjustment p_adj = 0.09). Associations of PM₁₀ and Fe_NO differed between moderate to late preterm (3.4; 95% CI, -0.1 to 6.8 ppb) and term (-0.3; 95% CI, -1.5 to 0.9 ppb) infants, and the interaction with prematurity was significant (p_{prematurity × PM10 interaction} = 0.006, p_adj = 0.036). Conclusions: Preterm infants showed significantly higher susceptibility even to low to moderate prenatal air pollution exposure than term infants, leading to increased impairment of postnatal lung function. Fe_NO results further elucidate differences in inflammatory/oxidative stress response when comparing preterm infants with term infants.

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.

Isoprostanes as Biomarker for White Matter Injury in Extremely Preterm Infants

Background and Aim: Preterm white matter is vulnerable to lipid peroxidation-mediated injury. F2-isoprostanes (IPs), are a useful biomarker for lipid peroxidation. Aim was to assess the association between early peri-postnatal IPs, white matter injury (WMI) at term equivalent age (TEA), and neurodevelopmental outcome in preterm infants. Methods: Infants with a gestational age (GA) below 28 weeks who had an MRI at TEA were included. IPs were measured in cord blood (cb) at birth and on plasma (pl) between 24 and 48 h after birth. WMI was assessed using Woodward MRI scoring system. Multiple regression analyses were performed to assess the association between IPs with WMI and then with BSITD-III scores at 24 months corrected age (CA). Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive value of pl-IPs for the development of WMI. Results: Forty-four patients were included. cb-IPs were not correlated with WMI score at TEA, whereas higher pl-IPs and lower GA predicted higher WMI score (p = 0.037 and 0.006, respectively) after controlling for GA, FiO2 at sampling and severity of IVH. The area under the curve was 0.72 (CI 95% = 0.51-0.92). The pl-IPs levels plotted curve indicated that 31.8 pg/ml had the best predictive threshold with a sensitivity of 86% and a specificity of 60%, to discriminate newborns with any WMI from newborns without WMI. IPs were not associated with outcome at 24 months. Conclusion: Early measurement of pl-IPs may help discriminate patients showing abnormal WMI score at TEA, thus representing an early biomarker to identify newborns at risk for brain injury.

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.

Early predictors of perinatal brain damage: the role of neurobiomarkers

The early detection of perinatal brain damage in preterm and term newborns (i.e. intraventricular hemorrhage, periventricular leukomalacia and perinatal asphyxia) still constitute an unsolved issue. To date, despite technological improvement in standard perinatal monitoring procedures, decreasing the incidence of perinatal mortality, the perinatal morbidity pattern has a flat trend. Against this background, the measurement of brain constituents could be particularly useful in the early detection of cases at risk for short-/long-term brain injury. On this scenario, the main European and US international health-care institutions promoted perinatal clinical and experimental neuroprotection research projects aimed at validating and including a panel of biomarkers in the clinical guidelines. Although this is a promising attempt, there are several limitations that do not allow biomarkers to be included in standard monitoring procedures. The main limitations are: (i) the heterogeneity of neurological complications in the perinatal period, (ii) the small cohort sizes, (iii) the lack of multicenter investigations, (iv) the different techniques for neurobiomarkers assessment, (iv) the lack of consensus for the validation of assays in biological fluids such as urine and saliva, and (v), the lack of reference curves according to measurement technique and biological fluid. In the present review we offer an up-to-date overview of the most promising developments in the use of biomarkers in the perinatal period such as calcium binding proteins (S100B protein), vasoactive agents (adrenomedullin), brain biomarkers (activin A, neuron specific enolase, glial fibrillary acidic protein, ubiquitin carboxyl-terminal hydrolase-L1) and oxidative stress markers.

Isoprostanes as Biomarker for Patent Ductus Arteriosus in Preterm Infants

Context: It has been reported that isoprostanes (IPs) have a role in the pathophysiology of ductus arteriosus during the fetal and neonatal period. Our aim in this study was to assess if urinary IPs (uIPs) levels correlate with the risk of developing a hemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants. Materials and methods: Infants with 23 + 0 - 33 + 6 weeks of gestational age and respiratory distress syndrome (RDS) were consecutively enrolled. Urine samples were collected on the 2nd and 10th day of life (DOL) for uIPs measurement. Echocardiography for hsPDA diagnosis was performed between 24 and 48 h of life. Regression analysis was performed to assess the correlation between uIPs and hsPDA. Receiver operating characteristic (ROC) curve analysis was used to evaluate the accuracy of the uIPs in predicting the occurrence of hsPDA. Results: Sixty patients were studied: 33 (55%) developed a hsPDA, 27 (45%) had ibuprofen hsPDA closure, and six (10%) required surgical closure. uIPs levels decreased from the 2nd to the 10th DOL. Adjusted regression analysis demonstrated that uIPs on the 2nd DOL were associated (p = 0.02) with the risk of developing a hsPDA. A cut-off level of 1627 ng/mg of creatinine of uIPs predicted the development of a hsPDA with a sensitivity of 82% and a specificity of 73%. Conclusion: Early measurement of uIPs on the 2nd DOL is a reliable biomarker of hsPDA development and, alone or combined with other markers, might represent a non-invasive tool useful for planning the management of PDA in preterm infants.

Thiol-Redox Regulation in Lung Development and Vascular Remodeling

Significance: Redox homeostasis is finely tuned and governed by distinct intracellular mechanisms. The dysregulation of this either by external or internal events is a fundamental pathophysiologic base for many pulmonary diseases. Recent Advances: Based on recent discoveries, it is increasingly clear that cellular redox state and oxidation of signaling molecules are critical modulators of lung disease and represent a final common pathway that leads to poor respiratory outcomes. Critical Issues: Based on the wide variety of stimuli that alter specific redox signaling pathways, improved understanding of the disease and patient-specific alterations are needed for the development of therapeutic targets. Further Directions: For the full comprehension of redox signaling in pulmonary disease, it is essential to recognize the role of reactive oxygen intermediates in modulating biological responses. This review summarizes current knowledge of redox signaling in pulmonary development and pulmonary vascular disease.

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.

Reactive oxygen species as mediators of oxygen signaling during fetal-to-neonatal circulatory transition

Reactive oxygen species (ROS) are frequently seen as pathological agents of oxidative stress. However, ROS are not always deleterious and can also act as cell signaling molecules. Vascular oxygen sensing and signaling during fetal-to-neonatal circulatory transition is a remarkable example of the physiological regulatory actions of ROS. The fetal relative hypoxic environment induces hypoxic pulmonary vasoconstriction (HPV) and ductus arteriosus (DA) relaxation favoring the presence of high pulmonary vascular resistance and right-to-left ductal shunt. At birth, the increase in oxygen tension causes relaxation of pulmonary arteries (PAs) and normoxic DA vasoconstriction (NDAV), thus diverting blood flow to the lungs. Although the response to changes in oxygen tension is diametrically opposite, the mechanisms responsible for HPV and NDAV appear to be the result of a similar interaction between triggering and modulating factors that lead to an increase in cytosolic Ca²⁺ concentration and Ca²⁺ sensitization of the contractile apparatus. Growing evidence points to an increase in ROS (mitochondria- and/or NADPH-derived superoxide and/or H₂O₂), leading to inhibition of voltage-gated K⁺ channels, membrane depolarization, and activation of voltage-gated L-type Ca²⁺ channels as critical events in the signaling pathway of both HPV and NDAV. Several groups of investigators have completed this pathway adding other elements such as neutral sphingomyelinase-derived ceramide, the sarcoplasmic/endoplasmic reticulum (through ryanodine and inositol 1,4,5-trisphosphate receptors), Rho kinase-mediated Ca²⁺ sensitization, or transient receptor potential channels. The present review focus on the role of ROS as mediators of the homeostatic oxygen sensing system during fetal and neonatal life not only in the PAs and DA but also in systemic arteries.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Endothelial Colony-Forming Cells in Young Adults Born Preterm: A Novel Link Between Neonatal Complications and Adult Risks for Cardiovascular Disease

BACKGROUND

Preterm birth is linked to cardiovascular risks and diseases. Endothelial progenitor cells play a critical role in vascular development and repair. Cord blood endothelial progenitor cells of preterm-born infants, especially endothelial colony-forming cells (ECFC), show enhanced susceptibility to prematurity-related pro-oxidant stress. Whether ECFC dysfunction is present in adulthood following preterm birth is unknown.

METHODS AND RESULTS

This cross-sectional observational study includes 55 preterm-born (≤29 gestational weeks) young adults (18-29 years old, 38% male) and 55 sex- and age-matched full-term controls. ECFC were isolated from peripheral blood; cell proliferative and vascular cord formation capacities were assessed in vitro. Daytime systolic blood pressure was higher, whereas glucose tolerance and body mass index were lower in preterm-born subjects. ECFC colonies grew in culture for 62% of full-term- and 58% of preterm-born participants. Preterm-born participants have formed ECFC colonies later in culture and have reduced proliferation compared with controls. Only in preterm-born individuals, we observed that the later the ECFC colony grows in culture, the worse was overall ECFC function. In addition, in preterms, elevated systolic blood pressure significantly correlated with reduced ECFC proliferation (r_S=-0.463; P=0.030) and numbers of branches formed on matrigel (r_S=-0.443; P=0.039). In preterm-born subjects, bronchopulmonary dysplasia was associated with impaired ECFC function, whereas exposure to antenatal steroids related to better ECFC function.

CONCLUSIONS

This study is the first to examine ECFC in preterm-born adults and to demonstrate ECFC dysfunction compared with full-term controls. In the preterm-born group, ECFC dysfunction was associated with bronchopulmonary dysplasia, the major prematurity-related neonatal morbidity, and with increased systolic blood pressure into adulthood.

Comparative physiology of the ductus arteriosus among vertebrates

The ductus arteriosus is typically viewed as a mammalian fetal blood vessel providing a right-to-left shunt of right ventricular outflow away from the lungs and to the systemic circuit, that must close at birth. This review provides a wider comparative examination of the ductus arteriosus in lungfish, reptiles, birds, and mammals. The ductus arteriosus evolved with the lung in the ancestors of the lungfish as a connection between the pulmonary arteries and dorsal aorta. During embryonic development, reptiles, birds, and mammals all possess either one or two paired ductus arteriosi that provide a fetal shunt of blood away from the lungs. Differences in the fetal circulatory arrangement are seen between these groups and this influences the importance of the ductus arteriosus as an embryonic shunt. The ductus arteriosus from lungfish and tetrapod vertebrates is an oxygen sensitive blood vessel, with shared conserved pathways involved in oxygen sensing. By expanding studies into more comparative models such as lungfish or developing birds a better understanding of the physiology of the ductus arteriosus can be developed.

Preterm birth and oxidative stress: Effects of acute physical exercise and hypoxia physiological responses

Preterm birth is a global health issue that can induce lifelong medical sequela. Presently, at least one in ten newborns are born prematurely. At birth, preterm newborns exhibit higher levels of oxidative stress (OS) due to the inability to face the oxygen rich environment in which they are born into. Moreover, their immature respiratory, digestive, immune and antioxidant defense systems, as well as the potential numerous medical interventions following a preterm birth, such as oxygen resuscitation, nutrition, phototherapy and blood transfusion further contribute to high levels of OS. Although the acute effects seem well established, little is known regarding the long-term effects of preterm birth on OS. This matter is especially important given that chronically elevated OS levels may persist into adulthood and consequently contribute to the development of numerous non-communicable diseases observed in people born preterm such as diabetes, hypertension or lung disorders. The purpose of this review is to summarize the current knowledge regarding the consequences of preterm birth on OS levels from newborn to adulthood. In addition, the effects of physical activity and hypoxia, both known to disrupt redox balance, on OS modulation in preterm individuals are also explored.

Neonatal exposure to high oxygen levels leads to impaired ischemia-induced neovascularization in adulthood

Adverse perinatal conditions can lead to developmental programming of cardiovascular diseases. Prematurely born infants are often exposed to high oxygen levels, which in animal models has been associated with endothelial dysfunction, hypertension, and cardiac remodeling during adulthood. Here we found that adult mice that have been transiently exposed to O₂ after birth show defective neovasculariation after hindlimb ischemia, as demonstrated by impaired blood flow recovery, reduced vascular density in ischemic muscles and increased tissue damages. Ischemic muscles isolated from mice exposed to O₂ after birth exhibit increased oxidative stress levels and reduced expression of superoxide dismutase 1 (SOD1) and vascular endothelial growth factor (VEGF). Pro-angiogenic cells (PACs) have been shown to have an important role for postnatal neovascularisation. We found that neonatal exposure to O₂ is associated with reduced number of PACs in adults. Moreover, the angiogenic activities of both PACs and mature mouse aortic endothelial cells (MAECs) are significantly impaired in mice exposed to hyperoxia after birth. Our results indicate that neonatal exposure to high oxygen levels leads to impaired ischemia-induced neovascularization during adulthood. The mechanism involves deleterious effects on oxidative stress levels and angiogenic signals in ischemic muscles, together with dysfunctional activities of PACs and mature endothelial cells.

Predictive Role of F2-Isoprostanes as Biomarkers for Brain Damage after Neonatal Surgery

Objective

Neonates have a high risk of oxidative stress during anesthetic procedures. The predictive role of oxidative stress biomarkers on the occurrence of brain injury in the perioperative period has not been reported before.

Methods

A prospective cohort study of patients requiring major surgery in the neonatal period was conducted. Biomarker levels of nonprotein-bound iron (NPBI) in plasma and F₂-isoprostane in plasma and urine before and after surgical intervention were determined. Brain injury was assessed using postoperative MRI.

Results

In total, 61 neonates were included, median gestational age at 39 weeks (range 31–42) and weight at 3000 grams (1400–4400). Mild to moderate brain lesions were found in 66%. Logistic regression analysis showed a significant difference between plasma NPBI in patients with nonparenchymal injury versus no brain injury: 1.34 umol/L was identified as correlation threshold for nonparenchymal injury (sensitivity 67%, specificity 91%). In the multivariable analysis, correcting for GA, no other significant relation was found with the oxidative stress biomarkers and risk factors.

Conclusion

Oxidative stress seems to occur during anaesthesia in this cohort of neonates. Plasma nonprotein-bound iron showed to be associated with nonparenchymal injury after surgery, with values of 1.34 umol/L or higher. Risk factors should be elucidated in a more homogeneous patient group.

Prediction of cardiovascular risk in preterm neonates through urinary proteomics: An exploratory study

Highlights

Urine proteomics allows the identification of the pathways modulated in neonates.Up-regulated pathways in preterm include immunity, metabolism and oxidative stress.Some of these pathways seem to be modulated by the nutritional support.AGT and RBP4 might be related to the development of cardiovascular diseases.

Abstract

Preterm birth has been associated with an increased risk of cardiovascular diseases (CVD) in adulthood. The goal of our study was to give new molecular insights on the relationship between prematurity and CVD risk and to identify putative biomarkers that would facilitate the development of effective screening and therapeutic strategies. In this sense, mass spectrometry (MS)-based proteomics was applied to the characterization of urine protein profile.GeLC-MS/MS analysis of urine (desalted and concentrated with a 10-kDa filter) followed by bioinformatics was applied for the characterization of preterm and full-term neonates. Urine proteome profiling retrieved 434 unique proteins, from which 126 were common to both groups, 37 were unique to preterm and 58 to full-term neonates. Protein-protein interaction analysis for unique proteins and common ones present in significant distinct levels retrieved immune system, metabolism, defense systems and tissue remodeling as the most representative clusters in preterm neonates.Metabolic adaptation along with the up-regulation of heart growth (identified by angiotensinogen and retinol-binding protein 4) may account for an increased CVD risk in preterm neonates. These proteins may have predictive value of CVD in adulthood of this specific group of neonates. The follow-up of urinary proteome dynamics of preterm and full-term neonates will be crucial for the validation of this hypothesis.

Physiological role of reactive oxygen species as promoters of natural defenses

It has been 60 yr since the discovery of reactive oxygen species (ROS) in biology and the beginning of the scientific community's attempt to understand the impact of the unpaired electron of ROS molecules in biological pathways, which was eventually noted to be toxic. Several studies have shown that the presence of ROS is essential in triggering or acting as a secondary factor for numerous pathologies, including metabolic and genetic diseases; however, it was demonstrated that chronic treatment with antioxidants failed to show efficacy and positive effects in the prevention of diseases or health complications that result from oxidative stress. On the contrary, such treatment has been shown to sometimes even worsen the disease. Because of the permanent presence of ROS in organisms, elaborate mechanisms to adapt with these reactive molecules and to use them without necessarily blocking or preventing their actions have been studied. There is now a large body of evidence that shows that living organisms have conformed to the presence of ROS and, in retrospect, have adapted to the bioactive molecules that are generated by ROS on proteins, lipids, and DNA. In addition, ROS have undergone a shift from being molecules that invoked oxidative damage in regulating signaling pathways that impinged on normal physiological and redox responses. Working in this direction, this review unlocks a new conception about the involvement of cellular oxidants in the maintenance of redox homeostasis in redox regulation of normal physiological functions, and an explanation for its essential role in numerous pathophysiological states is noted.-Roy, J., Galano, J.-M., Durand, T., Le Guennec, J.-Y., Lee, J. C.-Y. Physiological role of reactive oxygen species as promoters of natural defenses.

Classifying oxidative stress by F2-isoprostane levels across human diseases: A meta-analysis

The notion that oxidative stress plays a role in virtually every human disease and environmental exposure has become ingrained in everyday knowledge. However, mounting evidence regarding the lack of specificity of biomarkers traditionally used as indicators of oxidative stress in human disease and exposures now necessitates re-evaluation. To prioritize these re-evaluations, published literature was comprehensively analyzed in a meta-analysis to quantitatively classify the levels of systemic oxidative damage across human disease and in response to environmental exposures.

In this meta-analysis, the F₂-isoprostane, 8-iso-PGF_2α, was specifically chosen as the representative marker of oxidative damage. To combine published values across measurement methods and specimens, the standardized mean differences (Hedges’ g) in 8-iso-PGF_2α levels between affected and control populations were calculated.

The meta-analysis resulted in a classification of oxidative damage levels as measured by 8-iso-PGF_2α across 50 human health outcomes and exposures from 242 distinct publications. Relatively small increases in 8-iso-PGF_2α levels (g<0.8) were found in the following conditions: hypertension (g=0.4), metabolic syndrome (g=0.5), asthma (g=0.4), and tobacco smoking (g=0.7). In contrast, large increases in 8-iso-PGF_2α levels were observed in pathologies of the kidney, e.g., chronic renal insufficiency (g=1.9), obstructive sleep apnoea (g=1.1), and pre-eclampsia (g=1.1), as well as respiratory tract disorders, e.g., cystic fibrosis (g=2.3).

In conclusion, we have established a quantitative classification for the level of 8-iso-PGF_2α generation in different human pathologies and exposures based on a comprehensive meta-analysis of published data. This analysis provides knowledge on the true involvement of oxidative damage across human health outcomes as well as utilizes past research to prioritize those conditions requiring further scrutiny on the mechanisms of biomarker generation.

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Oxidative damage is highly variable in human conditions as measured by F₂-isoprostanes.

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Respiratory tract and urogenital diseases have the highest F₂-isoprostanes.

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Cancer and cardiovascular diseases have surprisingly low F₂-isoprostanes.

Prenatal phthalate exposure and 8-isoprostane among Mexican-American children with high prevalence of obesity

Oxidative stress has been linked to many obesity-related conditions among children including cardiovascular disease, diabetes mellitus and hypertension. Exposure to environmental chemicals such as phthalates, ubiquitously found in humans, may also generate reactive oxygen species and subsequent oxidative stress. We examined longitudinal changes of 8-isoprostane urinary concentrations, a validated biomarker of oxidative stress, and associations with maternal prenatal urinary concentrations of phthalate metabolites for 258 children at 5, 9 and 14 years of age participating in a birth cohort residing in an agricultural area in California. Phthalates are endocrine disruptors, and in utero exposure has been also linked to altered lipid metabolism, as well as adverse birth and neurodevelopmental outcomes. We found that median creatinine-corrected 8-isoprostane concentrations remained constant across all age groups and did not differ by sex. Total cholesterol, systolic and diastolic blood pressure were positively associated with 8-isoprostane in 14-year-old children. No associations were observed between 8-isoprostane and body mass index (BMI), BMI Z-score or waist circumference at any age. Concentrations of three metabolites of high molecular weight phthalates measured at 13 weeks of gestation (monobenzyl, monocarboxyoctyl and monocarboxynonyl phthalates) were negatively associated with 8-isoprostane concentrations among 9-year olds. However, at 14 years of age, isoprostane concentrations were positively associated with two other metabolites (mono(2-ethylhexyl) and mono(2-ethyl-5-carboxypentyl) phthalates) measured in early pregnancy. Longitudinal data on 8-isoprostane in this pediatric population with a high prevalence of obesity provides new insight on certain potential cardiometabolic risks of prenatal exposure to phthalates.

The response to oxidative stress and metallomics analysis in a twin study: The role of the environment

Inefficient response to oxidative stress has been associated with ageing and health risk. Metals are known to inhibit DNA repair and may modify the antioxidant response. How genetic variability and lifestyle factors modulate the response to oxidative stress is poorly explored. Our study aims to disentangle the contribution of genetics and environmental exposures to oxidative stress response using data from twin pairs. The non-enzymatic antioxidant capacity (NEAC), the repair capacity of 8-oxo-7,8-dihydroguanine (OGG activity) and the levels of 12 metals were measured in blood of 64 monozygotic and 31 dizygotic twin pairs. The contributions of genetic and environmental effects were assessed using standard univariate twin modelling. NEAC and OGG activity significantly decreased with age. Gender-, age- and body mass index-associated differences were identified for some metals. Principal Component Analysis identified two groups of metals whose levels in blood were highly correlated: As, Hg, Pb, Se, Zn and Al, Co, Cr, Mn, Ni. The environmental influence was predominant on OGG activity and NEAC variance whereas for most metals the best-fitting model incorporated additive genetic and unique environmental sources of variance. NEAC and OGG activity were both inversely correlated with blood levels of various metals. The inhibition of OGG activity by Cd was largely explained by smoking. Our data show a substantial role of environmental factors in NEAC and OGG activity variance that is not explained by twins' age. Exogenous environmental factors such as metals contribute to oxidative stress by decreasing NEAC and inhibiting repair of oxidatively-induced DNA damage.

Oxygen Use in Neonatal Care: A Two-edged Sword

In the neonatal period, the clinical use of oxygen should be taken into consideration for its beneficial and toxicity effects. Oxygen toxicity is due to the development of reactive oxygen species (ROS) such as OH^• that is one of the strongest oxidants in nature. Of note, generation of ROS is a normal occurrence in human and it is involved in a myriad of physiological reactions. Anyway an imbalance between production of oxidant species and antioxidant defenses, called oxidative stress, could affect various aspect of organisms' physiology and it could determine pathological consequences to living beings. Neonatal oxidative stress is essentially due to decreased antioxidants, increased ROS, or both. Studies have demonstrated that antioxidant capacity is lower in preterm newborns than term babies. This well-known deficiency of antioxidant factors is only a piece of a cohort of factors, which can be involved in the neonatal oxidative stress and the increased production of ROS may be a main factor. Mechanisms of ROS generation are: mitochondrial respiratory chain, free iron and Fenton reaction, inflammation, hypoxia and/or ischemia, reperfusion, and hyperoxia. Oxidative stress following hyperoxia has been recognized to be responsible for lung, central nervous system, retina, red blood cell injuries, and possibly generalized tissue damage. When supplemental oxygen is needed for care, it would be prudent to avoid changes and fluctuations in SpO₂. The definition of the safest level of oxygen saturations in the neonate remains an area of active research. Currently, on the basis of the published evidences, the most suitable approach would be to set alarm limits between 90 and 95%. It should allow to avoid SpO₂ values associated with potential hypoxia and/or hyperoxia. Although the usefulness of antioxidant protection in the neonatal period is still under investigation, the risk of tissue damage due to oxidative stress in perinatal period should not be underestimated.

[Oxidative stress after preterm birth: origins, biomarkers, and possible therapeutic approaches]

The survival of preterm babies has increased over the last few decades. However, disorders associated with preterm birth, known as oxygen radical diseases of neonatology, such as retinopathy, bronchopulmonary dysplasia, periventricular leukomalacia, and necrotizing enterocolitis are severe complications related to oxidative stress, which can be defined by an imbalance between oxidative reactive species production and antioxidant defenses. Oxidative stress causes lipid, protein, and DNA damage. Preterm infants have decreased antioxidant defenses in response to oxidative challenges, because the physiologic increase of antioxidant capacity occurs at the end of gestation in preparation for the transition to extrauterine life. Therefore, preterm infants are more sensitive to neonatal oxidative stress, notably when supplemental oxygen is being delivered. Furthermore, despite recent advances in the management of neonatal respiratory distress syndrome, controversies persist concerning the oxygenation saturation targets that should be used in caring for preterm babies. Identification of adequate biomarkers of oxidative stress in preterm infants such as 8-iso-prostaglandin F2α, and adduction of malondialdehyde to hemoglobin is important to promote specific therapeutic approaches. At present, no therapeutic strategy has been validated as prevention or treatment against oxidative stress. Breastfeeding should be considered as the main measure to improve the antioxidant status of preterm infants. In the last few years, melatonin has emerged as a protective molecule against oxidative stress, with antioxidant and free-radical scavenger roles, in experimental and preliminary human studies, giving hope that it can be used in preterm infants in the near future.

Disruption of cytochrome P4501A2 in mice leads to increased susceptibility to hyperoxic lung injury

Hyperoxia contributes to acute lung injury in diseases such as acute respiratory distress syndrome. Cytochrome P450 (CYP) 1A enzymes have been implicated in hyperoxic lung injury, but the mechanistic role of CYP1A2 in pulmonary injury is not known. We hypothesized that mice lacking the gene Cyp1a2 (which is predominantly expressed in the liver) will be more sensitive to lung injury and inflammation mediated by hyperoxia and that CYP1A2 will play a protective role by attenuating lipid peroxidation and oxidative stress in the lung. Eight- to ten-week-old WT (C57BL/6) or Cyp1a2(-/-) mice were exposed to hyperoxia (>95% O2) or maintained in room air for 24-72 h. Lung injury was assessed by determining the ratio of lung weight/body weight (LW/BW) and by histology. Extent of inflammation was determined by measuring the number of neutrophils in the lung as well as cytokine expression. The Cyp1a2(-/-) mice under hyperoxic conditions showed increased LW/BW ratios, lung injury, neutrophil infiltration, and IL-6 and TNF-α levels and augmented lipid peroxidation, as evidenced by increased formation of malondialdehyde- and 4-hydroxynonenal-protein adducts and pulmonary isofurans compared to WT mice. In vitro experiments showed that the F2-isoprostane PGF2-α is metabolized by CYP1A2 to a dinor metabolite, providing evidence for a catalytic role for CYP1A2 in the metabolism of F2-isoprostanes. In summary, our results support the hypothesis that hepatic CYP1A2 plays a critical role in the attenuation of hyperoxic lung injury by decreasing lipid peroxidation and oxidative stress in vivo.

The isoprostanes--25 years later

Isoprostanes (IsoPs) are prostaglandin-like molecules generated independent of the cyclooxygenase (COX) by the free radical-induced peroxidation of arachidonic acid. The first isoprostane species discovered were isomeric to prostaglandin F2α and were thus termed F2-IsoPs. Since the initial discovery of the F2-IsoPs, IsoPs with differing ring structures have been identified as well as IsoPs from different polyunsaturated fatty acids, including eicosapentaenoic acid and docosahexanenoic acid. The discovery of these molecules in vivo in humans has been a major contribution to the field of lipid oxidation and free radical research over the course of the past 25 years. These molecules have been determined to be both biomarkers and mediators of oxidative stress in numerous disease settings. This review focuses on recent developments in the field with an emphasis on clinical research. Special focus is given to the use of IsoPs as biomarkers in obesity, ischemia-reperfusion injury, the central nervous system, cancer, and genetic disorders. Additionally, attention is paid to diet and lifestyle factors that can affect endogenous levels of IsoPs. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance."

Developmental regulation of antioxidant enzymes and their impact on neonatal lung disease

SIGNIFICANCE

Deficient antioxidant defenses and compromised ability to respond to oxidative stress burden the immature lung. Routine neonatal therapies can cause increased oxidative stress with subsequent injury to the premature lung. Novel therapeutic approaches to protect the premature lung are greatly needed.

RECENT ADVANCES

Live cell imaging with targeted redox probes allows for the measurement of subcellular oxidative stress and for comparisons of oxidative stress across development. Comprehension of subcellular and cell-type-specific responses to oxidative stress may influence the targeting of future antioxidant therapies.

CRITICAL ISSUES

Challenges remain in identifying the optimal cellular targets, degree of enzyme activity, and appropriate antioxidant therapy. Further, the efficacy of delivering exogenous antioxidants to specific cell types or subcellular compartments remains under investigation. Treatment with a nonselective antioxidant could unintentionally compromise cellular function or impact cellular defense mechanisms and homeostasis.

FUTURE DIRECTIONS

Genetic and/or biomarker screening may identify infants at the greatest risk for oxidative lung injury and guide the use of more selective antioxidant therapies. Novel approaches to the delivery of antioxidant enzymes may allow cell type- or cellular organelle-specific therapy. Improved comprehension of the antioxidant enzyme regulation across cell type, cell compartment, gender, and developmental stage is critical to the design and optimization of therapy.

Mice deficient in the gene for cytochrome P450 (CYP)1A1 are more susceptible than wild-type to hyperoxic lung injury: evidence for protective role of CYP1A1 against oxidative stress

Hyperoxia contributes to acute lung injury in diseases such as acute respiratory distress syndrome in adults and bronchopulmonary dysplasia in premature infants. Cytochrome P450 (CYP)1A1 has been shown to modulate hyperoxic lung injury. The mechanistic role(s) of CYP1A1 in hyperoxic lung injury in vivo is not known. In this investigation, we hypothesized that Cyp1a1(-/-) mice would be more susceptible to hyperoxic lung injury than wild-type (WT) mice, and that the protective role of CYP1A1 is in part due to CYP1A1-mediated decrease in the levels of reactive oxygen species-mediated lipid hydroperoxides, e.g., F2-isoprostanes/isofurans, leading to attenuation of oxidative damage. Eight- to ten-week-old male WT (C57BL/6J) or Cyp1a1(-/-) mice were exposed to hyperoxia (>95% O2) or room air for 24-72 h. The Cyp1a1(-/-) mice were more susceptible to oxygen-mediated lung damage and inflammation than WT mice, as evidenced by increased lung weight/body weight ratio, lung injury, neutrophil infiltration, and augmented expression of IL-6. Hyperoxia for 24-48 h induced CYP1A expression at the mRNA, protein, and enzyme levels in liver and lung of WT mice. Pulmonary F2-isoprostane and isofuran levels were elevated in WT mice after hyperoxia for 24 h. On the other hand, Cyp1a1(-/-) mice showed higher levels after 48-72 h of hyperoxia exposure compared to WT mice. Our results support the hypothesis that CYP1A1 protects against hyperoxic lung injury by decreasing oxidative stress. Future research could lead to the development of novel strategies for prevention and/or treatment of acute lung injury.

The common antitussive agent dextromethorphan protects against hyperoxia-induced cell death in established in vivo and in vitro models of neonatal brain injury

Preterm infants are prematurely subjected to relatively high oxygen concentrations, even when supplemental oxygen is not administered. There is increasing evidence to show that an excess of oxygen is toxic to the developing brain. Dextromethorphan (DM), a frequently used antitussive agent with pleiotropic mechanisms of action, has been shown to be neuroprotective in various models of central nervous system pathology. Due to its numerous beneficial properties, it might also be able to counteract detrimental effects of a neonatal oxygen insult. The aim of the current study was to evaluate its therapeutic potential in established cell culture and rodent models of hyperoxia-induced neonatal brain injury. For in vitro studies pre- and immature oligodendroglial (OLN-93) cells were subjected to hyperoxic conditions for 48 h after pre-treatment with increasing doses of DM. For in vivo studies 6-day-old Wistar rat pups received a single intraperitoneal injection of DM in two different dosages prior to being exposed to hyperoxia for 24h. Cell viability and caspase-3 activation were assessed as outcome parameters at the end of exposure. DM significantly increased cell viability in immature oligodendroglial cells subjected to hyperoxia. In pre-oligodendroglial cells cell viability was not significantly affected by DM treatment. In vivo caspase-3 activation induced by hyperoxic exposure was significantly lower after administration of DM in gray and white matter areas. In control animals kept under normoxic conditions DM did not significantly influence caspase-3-dependent apoptosis. The present results indicate that DM is a promising and safe treatment strategy for neonatal hyperoxia-induced brain injury that merits further investigation.

Transient neonatal high oxygen exposure leads to early adult cardiac dysfunction, remodeling, and activation of the renin-angiotensin system

Perinatal conditions (such as preterm birth) can affect adult health and disease, particularly the cardiovascular system. Transient neonatal high O(2) exposure in rat in adulthood (a model of preterm birth-related complications) leads to elevated blood pressure, vascular rigidity, and dysfunction with renin-angiotensin system activation. We postulate that neonatal hyperoxic stress also affects myocardial structure, function, and expression of renin-angiotensin system components. Sprague-Dawley pups were kept with their mother in 80% O(2) or in room air (control) from days 3 to 10 of life. Left ventricular function was assessed in 4-, 7-, 12-week-old (echocardiography) and in 16-week-old (intraventricular catheterization) male O(2)-exposed versus control rats. At 16 weeks, hearts from O(2)-exposed rats showed cardiomyocyte hypertrophy, enhanced fibrosis, and increased expression of transforming growth factor-β1, senescence-associated proteins p53 and Rb, upregulation of angiotensin II type 1 (AT1) receptor expression (protein and AT1a/b mRNA), and downregulation of AT2 receptors. At 4 weeks (before blood pressure increase), the expression of cardiomyocyte surface area, fibrosis, p53, and AT1b was significantly increased and AT2 decreased in O(2)-exposed animals. After 4 weeks of continuous angiotensin II infusion (starting at 12 weeks), O(2)-exposed rats developed severe heart failure, with impaired myocardial mechanical properties compared with saline-infused rats. Transient neonatal O(2) exposure in rats leads to left ventricular hypertrophy, fibrosis and dysfunction, and increased susceptibility to heart failure under pressure overload. These results are relevant to the growing population of individuals born preterm who may be at higher risk of cardiac dysfunction when faced with increased peripheral resistance associated with hypertension, vascular diseases, and aging.

Developmental programming of eNOS uncoupling and enhanced vascular oxidative stress in adult rats after transient neonatal oxygen exposure

The authors have previously shown that neonatal hyperoxic stress leads to high blood pressure, impaired endothelium-mediated vasodilatation, and increased vascular production of superoxide anion by NAD(P)H oxidase in adulthood. However, it is unknown whether changes in nitric oxide (NO) production and/or bioinactivation prevail and whether NO synthase (NOS) is also a source of superoxide. The purpose of this study was to evaluate whether adult animals exposed to neonatal hyperoxic stress have impaired vascular NO production associated with NOS uncoupling participating to vascular superoxide production and vascular dysfunction. In adult male rats exposed to 80% oxygen from day 3 to 10 of life (H, n = 6) versus room air controls (CTRL, n = 6), vascular (aorta) NO production is decreased at baseline (CTRL: 21 ± 1 vs. H: 16 ± 2 4,5-diaminofluorescein diacetate fluorescence intensity arbitrary units; P < 0.05) and after carbachol stimulation (acetylcholine analog; CTRL: 26 ± 2 vs. H: 18±2; P < 0.05). Pretreatment with L-arginine (CTRL: 32 ± 4 vs. H: 31 ± 5) and L-sepiapterine [analog of key NOS cofactor tetrahydro-L-biopterin (BH4)] (CTRL: 30 ± 3 vs. H: 29 ± 3) normalizes NO production after carbachol. L-Sepiapterine also normalizes impaired vasodilatation to carbachol. Vascular endothelial NO synthase (eNOS) immunostaining is reduced, whereas total eNOS protein expression is increased in H (CTRL: 0.76 ± 0.08 vs. H: 1.76± 0.21; P < 0.01). The significantly higher superoxide generation (CTRL: 20 ± 2 vs. H: 28 ± 3 hydroethidine fluorescence intensity arbitrary units; P < 0.05) is prevented by pretreatment with the eNOS inhibitor N-nitro-L-arginine methyl ester (CTRL: 21 ± 4 vs. H: 22 ± 4). Taken together, the current data indicate a role for eNOS uncoupling in enhanced vascular superoxide, impaired endothelium-mediated vasodilatation, and decreased NO production in adult animals with programmed elevated blood pressure after a brief neonatal oxygen exposure.

Sex-dependent changes in the pulmonary vasoconstriction potential of newborn rats following short-term oxygen exposure

BACKGROUND

Chronic exposure to supplemental oxygen (O(2)) induces lung damage and mortality in a sex-dependent manner. The effect of short-term hyperoxia on the newborn pulmonary vasculature is unknown but is, however, of clinical significance in the neonatal resuscitation context. We hypothesize that short-term hyperoxia has a sex-dependent effect on the pulmonary vasculature.

METHODS

Following 1-h 100% O(2) exposure, the pulmonary arteries and lung tissues of newborn rats were evaluated.

RESULTS

Superoxide dismutase 3 (SOD3) expression in female pups' lungs was increased as compared with that in the lungs of male pups. As compared with air-treated pups, the response of male pups to thromboxane was increased by O(2), whereas the opposite effect was documented in the vessels of female pups. The enhanced force of hyperoxia-exposed arteries of the male pups was suppressed with superoxide or peroxynitrite scavengers, and increased lung SOD activity and hydrogen peroxide content were seen in female, but not in male, rats. Hyperoxia induced an increase in lung tissue oxidative products and Rho-kinase (ROCK) activity in male, but not in female, pups.

CONCLUSION

A lower lung SOD content and failure to upregulate SOD activity facilitates peroxynitrite generation and ROCK activation in hyperoxia-exposed males, predisposing them to pulmonary vasoconstriction. These observations, if relevant to humans, may explain the increased mortality and higher incidence of pulmonary hypertension in male neonates.

Biomarkers of oxidative stress in fetal and neonatal diseases

Oxidative stress (OS) is strongly involved in the pathogenesis of many fetal and newborn diseases. A low efficient antioxidant systems in preterm babies are not able to counteract the harmful effects of free radicals (FRs), leading to "FRs-related disease" of newborns promoting cellular, tissue and organ damages. The dangerous effects of FRs are linked to their property of being very unstable molecules and their ability to react with lipids, proteins, polysaccharides, nucleic acids, causing functional alterations within the cell, until cell death. OS is difficult to be measured in vivo, because FRs have a very short half-life. Actually, measurements of lipid peroxidation reach high specificity and sensitivity with the discovery of stable compounds, isoprostanes. Recent studies evaluating the damaging effects of FRs in the perinatal period, have observed a direct relation between the degree of OS and the severity of oxidative damage in the course of pregnancy and in perinatal period, with an interesting predictive role of OS biomarkers for diseases resulting from oxidative injury. The validation of a biomarker profile for early identification of newborns at high risk of OS, will pave the way to new clinical preventative or therapeutic approaches to reduce the prevalence of neonatal disability.

Isoprostanes as physiological mediators of transition to newborn life: novel mechanisms regulating patency of the term and preterm ductus arteriosus

BACKGROUND

Increased oxygen tension at birth regulates physiologic events that are essential to postnatal survival, but the accompanying oxidative stress may also generate isoprostanes. We hypothesized that isoprostanes regulate ductus arteriosus (DA) function during postnatal vascular transition.

METHODS

Isoprostanes were measured by gas chromatography-mass spectrometry. DA tone was assessed by pressure myography. Gene expression was measured by quantitative PCR.

RESULTS

Oxygen exposure was associated with increased 8-iso-prostaglandin (PG)F2α in newborn mouse lungs. Both 8-iso-PGE2 and 8-iso-PGF2α induced concentration-dependent constriction of the isolated term DA, which was reversed by the thromboxane A2 (TxA2) receptor antagonist SQ29548. SQ29548 pretreatment unmasked an isoprostane-induced DA dilation mediated by the EP4 PG receptor. Exposure of the preterm DA to 8-iso-PGE2 caused unexpected DA relaxation that was reversed by EP4 antagonism. In contrast, exposure to 8-iso-PGF2α caused preterm DA constriction via TxA2 receptor activation. Further investigation revealed the predominance of the TxA2 receptor at term, whereas the EP4 receptor was expressed and functionally active from mid-gestation onward.

CONCLUSION

This study identifies a novel physiological role for isoprostanes during postnatal vascular transition and provide evidence that oxidative stress may act on membrane lipids to produce vasoactive mediators that stimulate physiological DA closure at birth or induce pathological patency of the preterm DA.

Significant Differences in Markers of Oxidant Injury between Idiopathic and Bronchopulmonary-Dysplasia-Associated Pulmonary Hypertension in Children

While oxidant stress is elevated in adult forms of pulmonary hypertension (PH), levels of oxidant stress in pediatric PH are unknown. The objective of this study is to measure F(2)-isoprostanes, a marker of oxidant stress, in children with idiopathic pulmonary hypertension (IPH) and PH due to bronchopulmonary dysplasia (BPD). We hypothesized that F(2)-isoprostanes in pediatric IPH and PH associated with BPD will be higher than in controls. Plasma F(2)-isoprostanes were measured in pediatric PH patients during clinically indicated cardiac catheterization and compared with controls. F(2)-Isoprostane levels were compared between IPH, PH due to BD, and controls. Five patients with IPH, 12 with PH due to BPD, and 20 control subjects were studied. Patients with IPH had statistically higher isoprostanes than controls 62 pg/mL (37-210) versus 20 pg/mL (16-27), P < 0.01). The patients with PH and BPD had significantly lower isoprostanes than controls 15 pg/mL (8-17) versus 20 pg/ml (16-27), P < 0.02. F(2)-isoprostanes are elevated in children with IPH compared to both controls and patients with PH secondary to BPD. Furthermore, F(2)-isoprostanes in PH secondary to BPD are lower than control levels. These findings suggest that IPH and PH secondary to BPD have distinct mechanisms of disease pathogenesis.

Impact of fetal programming, birth weight, and infant feeding on later hypertension

The concept of developmental origins of adult disease derives from both epidemiologic and basic sciences. This brief review considers the impact of the intrauterine milieu, intrauterine growth retardation, premature birth, and infant feeding on later hypertension and kidney disease.

Influence of sex and glucocorticoid exposure on preterm placental pro-oxidant-antioxidant balance

Glucocorticoids (GC) are known to influence fetal ROS production and anti-oxidant defences yet little attention has focused on the potential for effects in the placenta. We hypothesised that antenatal GC exposure alters placental pro-oxidant-anti-oxidant balance sex-specifically, based upon the known relationship between male sex and poor pregnancy outcome. Placentae were collected from 60 women who delivered between 24 and 31 completed weeks gestation and placental oxidative and nitrative stress (protein carbonyl, lipid hydroperoxide, and nitrotyrosine concentration) and anti-oxidant enzyme activity (glutathione peroxidase, thioredoxin reductase, and superoxide dismutase) measured. A pro-oxidant state was observed in placentae of male compared to female infants born within 72 h of antenatal GC exposure, with higher levels of protein carbonyl content (p = 0.04), lipid hydroperoxide (p < 0.01) and nitrotyrosine content (p = 0.02), and lower levels of glutathione peroxidase activity (p = 0.01). A pro-oxidant state continued to be observed in placentae of males compared to females born outside of 72 h, with higher protein carbonyl content (p = 0.04) and lower glutathione peroxidase activity (p = 0.01) than females, however no differences in placental lipid hydroperoxide and nitrotyrosine content were observed. These sex-specific alterations in products of placental oxidative stress could not purely be explained by differences in clinical illness severity (CRIB2 score). Therefore, these sex-specific alterations in placental pro-oxidant-antioxidant balance in response to antenatal betamethasone exposure, independent of illness severity, could contribute to the patho-physiologic processes underlying oxygen radical diseases of the newborn, conditions known to exhibit a male excess.

Contractile effects of 15-E2t-isoprostane and 15-F2t-isoprostane on chicken embryo ductus arteriosus

Isoprostanes (IsoPs) are prostaglandin (PG)-like compounds produced nonenzymatically by free radical-catalyzed peroxidation of arachidonate. Cyclooxygenase-derived PGs play a major role in ductus arteriosus (DA) homeostasis but the putative role of IsoPs has not been studied so far. We investigated, using wire myography, the vasoactive effects of 15-E(2t)-IsoP and 15-F(2t)-IsoP in the chicken embryo DA, pulmonary artery (PA) and femoral artery (FA). 15-E(2t)-IsoP and 15-F(2t)-IsoP contracted DA, PA, and FA rings in a concentration-dependent manner. 15-E(2t)-IsoP was equally efficacious (mean±SE E(max)=1.25±0.06 mN/mm) as and more potent (-log of molar concentration producing 50% of E(max)=pEC(50)=7.00±0.04) than the thromboxane-prostanoid (TP) receptor agonist U46619 (E(max)=1.49±0.11 mN/mm; pEC(50)=6.48±0.05) in contracting chicken DA (pulmonary side). 15-F(2t)-IsoP was less potent (pEC(50)=5.74±0.11) and less efficacious (E(max)=0.96±0.11) than U46619. Concentration-dependent contractions to 15-E(2t)-IsoP and U46619 in DA rings were competitively inhibited by the TP receptor antagonist SQ29548 (0.1 μM to 10 μM) with no decrease in the E(max) values. SQ29548 also inhibited concentration-dependent contraction to 15-F(2t)-IsoP but this inhibition was associated with a decrease in E(max). Pre-incubation of DA rings with 15-F(2t)-IsoP inhibited responses to U46619 and, in vessels contracted with U46619 (1 μM), 15-F(2t)-IsoP (>1 μM) evoked a relaxant response. Enzyme immunoassay did not show a measurable release of 15-F(2t)-IsoP by DA rings. In conclusion, 15-E(2t)-IsoP is a potent and efficacious constrictor of chicken DA, acting through TP receptors. In contrast, 15-F(2t)-IsoP is probably acting as a partial agonist at TP receptors. We speculate that IsoPs play a role in the control of chicken DA tone and could participate in its closure.

Isoprostane levels in urine of preterm newborns treated with ibuprofen for patent ductus arteriosus closure

Patent ductus arteriosus (PDA) is the most common cardiovascular abnormality of the preterm infant usually treated with ibuprofen (IBU). PDA is strictly related to oxidative stress (OS) in neonates. This study tests the hypothesis that OS occurs in neonates with PDA and that IBU treatment reduces OS. Forty-three preterm babies with gestational age (GA) <33 weeks were studied prospectively. Three urine samples were collected: at time 0 (before starting treatment), time 1 (after pharmacological PDA closure), and time 2 (7 days after the end of treatment) in all patients. OS was studied by measuring urinary isoprostane (IPs) levels. The results showed significant changes in urinary IP levels from time 0 to time 2 (Kruskal-Wallis, p=0.047). Time trend showed a significant decrease in IPs from time 0 to time 1 after IBU therapy (p=0.0067). This decrease was followed by an increase in IPs levels 7 days after treatment. IBU therapy for PDA closure reduced the risk of OS related to free-radical (FR) generation. This antioxidant effect of IBU may be beneficial in preterm babies with PDA who are at high risk for OS.