Vitamin C supplementation in very preterm infants: a randomised controlled trial

Oxygen in the neonatal ICU: a complicated history and where are we now?

Despite major advances in neonatal care, oxygen remains the most commonly used medication in the neonatal intensive care unit (NICU). Supplemental oxygen can be life-saving for term and preterm neonates in the resuscitation period and beyond, however use of oxygen in the neonatal period must be judicious as there can be toxic effects. Newborns experience substantial hemodynamic changes at birth, rapid energy consumption, and decreased antioxidant capacity, which requires a delicate balance of sufficient oxygen while mitigating reactive oxygen species causing oxidative stress. In this review, we will discuss the physiology of neonates in relation to hypoxia and hyperoxic injury, the history of supplemental oxygen in the delivery room and beyond, supporting clinical research guiding trends for oxygen therapy in neonatal care, current practices, and future directions.

Retinopathy of Prematurity-Targeting Hypoxic and Redox Signaling Pathways

Retinopathy of prematurity (ROP) is a proliferative vascular ailment affecting the retina. It is the main risk factor for visual impairment and blindness in infants and young children worldwide. If left undiagnosed and untreated, it can progress to retinal detachment and severe visual impairment. Geographical variations in ROP epidemiology have emerged over recent decades, attributable to differing levels of care provided to preterm infants across countries and regions. Our understanding of the causes of ROP, screening, diagnosis, treatment, and associated risk factors continues to advance. This review article aims to present the pathophysiological mechanisms of ROP, including its treatment. Specifically, it delves into the latest cutting-edge treatment approaches targeting hypoxia and redox signaling pathways for this condition.

Oxidative stress in the eye and its role in the pathophysiology of ocular diseases

Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.

Identifying novel candidate compounds for therapeutic strategies in retinopathy of prematurity via computational drug-gene association analysis

Purpose

Retinopathy of prematurity (ROP) is the leading cause of preventable childhood blindness worldwide. Although interventions such as anti-VEGF and laser have high success rates in treating severe ROP, current treatment and preventative strategies still have their limitations. Thus, we aim to identify drugs and chemicals for ROP with comprehensive safety profiles and tolerability using a computational bioinformatics approach.

Methods

We generated a list of genes associated with ROP to date by querying PubMed Gene which draws from animal models, human studies, and genomic studies in the NCBI database. Gene enrichment analysis was performed on the ROP gene list with the ToppGene program which draws from multiple drug-gene interaction databases to predict compounds with significant associations to the ROP gene list. Compounds with significant toxicities or without known clinical indications were filtered out from the final drug list.

Results

The NCBI query identified 47 ROP genes with pharmacologic annotations present in ToppGene. Enrichment analysis revealed multiple drugs and chemical compounds related to the ROP gene list. The top ten most significant compounds associated with ROP include ascorbic acid, simvastatin, acetylcysteine, niacin, castor oil, penicillamine, curcumin, losartan, capsaicin, and metformin. Antioxidants, NSAIDs, antihypertensives, and anti-diabetics are the most common top drug classes derived from this analysis, and many of these compounds have potential to be readily repurposed for ROP as new prevention and treatment strategies.

Conclusion

This bioinformatics analysis creates an unbiased approach for drug discovery by identifying compounds associated to the known genes and pathways of ROP. While predictions from bioinformatic studies require preclinical/clinical studies to validate their results, this technique could certainly guide future investigations for pathologies like ROP.

Nutritional Supplements to Improve Outcomes in Preterm Neonates

Preterm infants are at higher risk of mortality and morbidity compared with those born at term. Nutrition-related morbidities include poor growth, immune deficiency, nutritional deficiencies, and adverse long-term neurodevelopment. In addition to macronutrients, many nutritional supplements have been used to enhance growth and development, and decrease infections. Nutrients can enhance preterm infants' immune status, optimize the microbiome, improve growth and development, and influence the risk of necrotizing enterocolitis, sepsis, and other outcomes.

Ascorbic Acid and the Premature Infant

Little information exists about the plasma target nutritional needs of the >15 million premature infants <37 weeks gestation. Investigating ascorbic acid’s (AscA) role in infant health, our study details the relationship of infant characteristics and maternal health on infant plasma AscA level (pAscA) during postnatal development. Furthermore, we determined pAscA influence during the first week of life (EpAscA) with later infant morbidities. We hypothesize that pAscA is influenced by gestational organ immaturity, as well as maternal factors, with EpAscA associated with greater morbidity risk. We conducted a prospective longitudinal observational study of pAscA, demographics and hospital course detailed in infants ≤34 weeks. Sixty-three subjects were included, with >200 urine and plasma data points analyzed. Maternal smoking, exposure to magnesium sulfate (MgSO4) and advancing gestational and postnatal age were associated with lower pAscA. Non-white infants and those ≤30 weeks that developed bronchopulmonary dysplasia or retinopathy of prematurity had lower pAscA. Prenatal smoking, MgSO4, birth gestational age and race negatively influence pAscA. These results show prenatal and postnatal developmental factors influencing initial pAscA and metabolism, potentially setting the stage for organ health and risk for disease. Assessment of dietary targets may need adjustment in this population.

Supplemental Oxygen in the Newborn: Historical Perspective and Current Trends

Oxygen is the final electron acceptor in aerobic respiration, and a lack of oxygen can result in bioenergetic failure and cell death. Thus, administration of supplemental concentrations of oxygen to overcome barriers to tissue oxygen delivery (e.g., heart failure, lung disease, ischemia), can rescue dying cells where cellular oxygen content is low. However, the balance of oxygen delivery and oxygen consumption relies on tightly controlled oxygen gradients and compartmentalized redox potential. While therapeutic oxygen delivery can be life-saving, it can disrupt growth and development, impair bioenergetic function, and induce inflammation. Newborns, and premature newborns especially, have features that confer particular susceptibility to hyperoxic injury due to oxidative stress. In this review, we will describe the unique features of newborn redox physiology and antioxidant defenses, the history of therapeutic oxygen use in this population and its role in disease, and clinical trends in the use of therapeutic oxygen and mitigation of neonatal oxidative injury.

Identification of candidate genes and pathways in retinopathy of prematurity by whole exome sequencing of preterm infants enriched in phenotypic extremes

Retinopathy of prematurity (ROP) is a vasoproliferative retinal disease affecting premature infants. In addition to prematurity itself and oxygen treatment, genetic factors have been suggested to predispose to ROP. We aimed to identify potentially pathogenic genes and biological pathways associated with ROP by analyzing variants from whole exome sequencing (WES) data of premature infants. As part of a multicenter ROP cohort study, 100 non-Hispanic Caucasian preterm infants enriched in phenotypic extremes were subjected to WES. Gene-based testing was done on coding nonsynonymous variants. Genes showing enrichment of qualifying variants in severe ROP compared to mild or no ROP from gene-based tests with adjustment for gestational age and birth weight were selected for gene set enrichment analysis (GSEA). Mean BW of included infants with pre-plus, type-1 or type 2 ROP including aggressive posterior ROP (n = 58) and mild or no ROP (n = 42) were 744 g and 995 g, respectively. No single genes reached genome-wide significance that could account for a severe phenotype. GSEA identified two significantly associated pathways (smooth endoplasmic reticulum and vitamin C metabolism) after correction for multiple tests. WES of premature infants revealed potential pathways that may be important in the pathogenesis of ROP and in further genetic studies.

Oxidative stress in the retina: implications for Retinopathy of Prematurity

Oxygen supplementation has been used as a part of respiratory care for preterm and term newborns since the beginning of 19^th century. Although oxygen administration can be life-saving, reactive oxygen species (ROS) and reactive nitrogen species (RNS) due to hyperoxia can have detrimental effects in the developing organs of the preterm infants, with both short and long term consequences. Oxygen toxicity on the immature tissues of preterm infants can contribute to the development of several diseases like retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD). The vascular development of human retina is completed at term, whereas the neural retina develops up to 5 years of age. Disruption of the normal retinal neurovascular growth is the pathognomonic feature of ROP, and can lead to vision threatening disease or even blindness. It is estimated that at least 100,000 infants all over the world will be blind every year due to ROP, which is the leading cause of blindness in children. In this review we will discuss the role of ROS and RNS in the development of ROP, and how through historical, epidemiological, and developmental aspects of this devastating disease, we can design future research for its prevention and treatment.

Ischemic Retinopathies: Oxidative Stress and Inflammation

Ischemic retinopathies (IRs), such as retinopathy of prematurity (ROP), diabetic retinopathy (DR), and (in many cases) age-related macular degeneration (AMD), are ocular disorders characterized by an initial phase of microvascular changes that results in ischemia, followed by a second phase of abnormal neovascularization that may culminate into retinal detachment and blindness. IRs are complex retinal conditions in which several factors play a key role during the development of the different pathological stages of the disease. Increasing evidence reveals that oxidative stress and inflammatory processes are important contributors to the pathogenesis of IRs. Despite the beneficial effects of the photocoagulation and anti-VEGF therapy during neovascularization phase, the need to identify novel targets to prevent initial phases of these ocular pathologies is still needed. In this review, we provide an update on the involvement of oxidative stress and inflammation in the progression of IRs and address some therapeutic interventions by using antioxidants and anti-inflammatory agents.

Maternal vitamin C deficiency during pregnancy results in transient fetal and placental growth retardation in guinea pigs

PURPOSE

Recently, we reported that preferential maternal-fetal vitamin C (vitC) transport across the placenta is likely to be impaired by prolonged maternal vitC deficiency. Maintenance of a basal maternal vitC supply at the expense of the fetus may impair fetal development; however, the knowledge of vitC's impact on intrauterine development is sparse. The aim of this study was to explore the effect of maternal vitC status on fetal and placental development in guinea pigs.

METHODS

Twenty pregnant Dunkin Hartley guinea pigs were randomized into four groups to receive diets either sufficient (918 mg/kg CTRL) or deficient (100 mg/kg DEF) in vitC. Cesarean sections at gestational day (GD) 45 or 56 allowed for fetal and placental measurements.

RESULTS

At GD45, body, brain and placental weights were significantly reduced in DEF pups compared with CTRL (p < 0.05, p < 0.001 and p < 0.05, respectively). DEF plasma vitC levels were ~6% of those of CTRL (p < 0.0001), and the fetal/maternal plasma vitC ratio was significantly reduced at GD56 in the DEF animals compared with controls (p = 0.035). Placental vitC levels were reduced in DEF animals (p < 0.0001) and the ascorbate oxidation ratio and glutathione elevated compared with controls (p < 0.0001).

CONCLUSIONS

Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Low maternal vitC intake during pregnancy may compromise maternal weight gain, placental function and intrauterine development.

Standardised neonatal parenteral nutrition formulations - an Australasian group consensus 2012

Standardised parenteral nutrition formulations are routinely used in the neonatal intensive care units in Australia and New Zealand. In 2010, a multidisciplinary group was formed to achieve a consensus on the formulations acceptable to majority of the neonatal intensive care units. Literature review was undertaken for each nutrient and recommendations were developed in a series of meetings held between November 2010 and April 2011. Three standard and 2 optional amino acid/dextrose formulations and one lipid emulsion were agreed by majority participants in the consensus. This has a potential to standardise neonatal parenteral nutrition guidelines, reduce costs and prescription errors.

Excess vitamin intake: An unrecognized risk factor for obesity

Over the past few decades, food fortification and infant formula supplementation with high levels of vitamins have led to a sharp increase in vitamin intake among infants, children and adults. This is followed by a sharp increase in the prevalence of obesity and related diseases, with significant disparities among countries and different groups within a country. It has long been known that B vitamins at doses below their toxicity threshold strongly promote body fat gain. Studies have demonstrated that formulas, which have very high levels of vitamins, significantly promote infant weight gain, especially fat mass gain, a known risk factor for children developing obesity. Furthermore, ecological studies have shown that increased B vitamin consumption is strongly correlated with the prevalence of obesity and diabetes. We therefore hypothesize that excess vitamins may play a causal role in the increased prevalence of obesity. This review will discuss: (1) the causes of increased vitamin intake; (2) the non-monotonic effect of excess vitamin intake on weight and fat gain; and (3) the role of vitamin fortification in obesity disparities among countries and different groups within a country.

Early infant exposure to excess multivitamin: a risk factor for autism?

Autism, a neurodevelopmental disorder that affects boys more than girls, is often associated with altered levels of monoamines (serotonin and catecholamines), especially elevated serotonin levels. The monoamines act as both neurotransmitters and signaling molecules in the gastrointestinal and immune systems. The evidence related to monoamine metabolism may be summarized as follows: (i) monoamine neurotransmitters are enzymatically degraded/inactivated by three mechanisms: oxidative deamination, methylation, and sulfation. The latter two are limited by the supply of methyl groups and sulfate, respectively. (ii) A decrease in methylation- and sulfation-mediated monoamine inactivation can be compensated by an increase in the oxidative deamination catalyzed by monoamine oxidase, an X-linked enzyme exhibiting higher activity in females than in males. (iii) Vitamins can, on one hand, facilitate the synthesis of monoamine neurotransmitters and, on the other hand, inhibit their inactivation by competing for methylation and sulfation. Therefore, we postulate that excess multivitamin feeding in early infancy, which has become very popular over the past few decades, may be a potential risk factor for disturbed monoamine metabolism. In this paper, we will focus on the relationship between excess multivitamin exposure and the inactivation/degradation of monoamine neurotransmitters and its possible role in the development of autism.

Association between Total Antioxidant Capacity in Breast Milk and Postnatal Age in Days in Premature Infants

This study aimed to consider the significance of breast milk in preventing oxidative stress by comparing total antioxidant capacity (TAC) in breast milk and formula milk for premature infants, demonstrating the relationship between TAC in breast milk and postnatal age in days. We used the biological anti-oxidant potential test, a new method to measure TAC in breast milk. Breast milk for premature infants were stored at -20 degrees C and thawed within 48 h of collection. We measured TAC in two types of formula milk in the same way. TAC was clearly higher in breast milk than formula milk. Although a negative correlation was observed between TAC in breast milk and age when collected, TAC was always higher than the average TAC in formula milk. TAC in breast milk is higher than TAC in formula milk. We suggest the importance of breast milk for preventing oxidative stress and starting breastfeeding early.

Neuronal death and oxidative stress in the developing brain

The developing brain is particularly vulnerable to reactive oxygen and reactive nitrogen species-mediated damage because of its high concentrations of unsaturated fatty acids, high rate of oxygen consumption, low concentrations of antioxidants, high content of metals catalyzing free radical formation, and large proportion of sensitive immature cells. In this review, we outline the dynamic changes of energy resources, metabolic requirements, and endogenous free radical scavenging systems during physiologic brain development. We further discuss the involvement of oxidative stress in the pathogenesis of neuronal death after exposure of the infant brain to hyperoxia, hypoxia/ischemia, sedative drugs, ethanol, and mechanical trauma. Several approaches have been developed to combat oxidative stress, but neuroprotective treatment strategies are limited in the clinical setting.

Recombinant human erythropoietin reduces plasminogen activator inhibitor and ameliorates pro-inflammatory responses following trauma

BACKGROUND AND THE PURPOSE OF THE STUDY

sBesides its hematopoietic effects, erythropoietin (EPO) by mobilization of iron and modulation of some inflammatory cytokines has antioxidant and anti-inflammatory properties. The purpose of this study was to evaluate these effects of erythropoietin and its impact on organ function in traumatized patients.

METHODS

Twenty-six ICU-admitted traumatized patients within 24 hrs after trauma were randomly assigned to the EPO (received EPO, 300 units/Kg/day) and Control (not received EPO) groups. The inflammatory biomarkers including Tumor Necrosis Factor alpha (TNF-α), Interleukin 1 (IL-1), Plasminogen Activator Inhibitor 1 (PAI-1) and Nitrotyrosine were recorded at the admission, 3, 6 and 9 days thereafter. Acute Physiology and Chronic Health Evaluation (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores were also recorded.

RESULTS

Among 12 patients (EPO group) TNF-α level at the day of 9 (P=0.046), and within EPO group at the days of 3 (P=0.026 ameliorate), 6 (P=0.016), and 9 (P=0.052) were significantly lowered. Level of IL-1 and PAI-1 decreased significantly at days of 3, 6 and 9 post intervention. Also there were significant differences between two groups in the SOFA score during three measured time intervals (the first, third and seventh days).

CONCLUSION

From the results of this study it seems that injection of erythrocyte stimulating agent is well tolerated and inhibits the inflammatory response and oxidative stress following trauma.

Micronutrientes com ação antioxidante em neonatos

OBJETIVO: Apresentar uma revisão atualizada e crítica sobre o estresse oxidativo em neonatos, bem como o efeito de micronutrientes com ação antioxidante direcionado ao grupo em questão. FONTES DE DADOS: Pesquisa bibliográfica nos bancos de dados Medline e LILACS (1997-2009), selecionando os artigos escritos em inglês, português ou espanhol, a partir dos descritores "neonato" e "micronutrientes", em combinação com "antioxidantes" e "estresse oxidativo". Foram examinados 90 artigos e 34 deles selecionados. SÍNTESE DOS DADOS: O nascimento, por si só, representa um estresse oxidativo para o recém-nascido, o que se agrava nos casos de prematuridade e quando existem doenças associadas. A agressão oxidativa sofrida pelo neonato a termo é contrabalançada pela maturação eficaz dos mecanismos antioxidantes; porém, no caso dos prematuros, isto não é evidente, uma vez que altas concentrações de antioxidantes só ocorrem no final da gestação. Diversos estudos foram realizados no intuito de avaliar as concentrações de antioxidantes em neonatos a termo e pré-termo, assim como propor doses de suplementação que possam ser eficazes em combater o estresse oxidativo. CONCLUSÕES: O estresse oxidativo está presente em neonatos, em especial nos prematuros, aumentando a demanda de nutrientes antioxidantes. É consenso que estes devem ser administrados de forma combinada, de modo a prevenir danos celulares. São necessários estudos longitudinais e com maiores casuísticas que avaliem as concentrações desses micronutrientes antioxidantes, com o intuito de traçar recomendações apropriadas para neonatos a termo e pré-termo.

Cholinergic and oxidative stress mechanisms in sudden infant death syndrome

Aim:

To determine whether biochemical parameters of cholinergic and oxidative stress function including red cell acetylcholinesterase (AChE), serum/plasma thyroglobulin, selenium, iron, ferritin, vitamins C, E, and A affect risk in apparent life-threatening event (ALTE), sudden infant death syndrome (SIDS), and sudden unexpected death in infancy (SUDI). To assess these biochemical parameters as a function of age; and for influence of pharmacology and epidemiology, including infant health, care, and feeding practices.

Methods:

A multicentre, case–control study with blood samples from 34 ALTE and 67 non-ALTE (control) infants matched for age, and 30 SIDS/SUDI and four non-SIDS/non-SUDI (post-mortem control) infants.

Results:

Levels/activity of the biochemical parameters were not significantly different in ALTE vs. control infants, with the exception of higher vitamin C levels in the ALTE group (p = 0.009). In ALTE and control groups, AChE and thyroglobulin levels increased and decreased respectively from birth to attain normal adult levels from 6 months. Levels of iron and ferritin were higher in the first 6 month period for all infant groups studied, intersecting with vitamin C levels peaking around 4 months of age.

Conclusion:

Lower AChE levels and higher combined levels of iron and vitamin C in the first 6 months of life may augment cholinergic and oxidative stress effect, particularly at the age when SIDS is most prevalent. This may contribute to risk of ALTE and SIDS/SUDI events during infancy.

Vitamin C deficiency in early postnatal life impairs spatial memory and reduces the number of hippocampal neurons in guinea pigs

BACKGROUND

The neonatal brain is particularly vulnerable to imbalances in redox homeostasis because of rapid growth and immature antioxidant systems. Vitamin C has been shown to have a key function in the brain, and during states of deficiency it is able to retain higher concentrations of vitamin C than other organs. However, because neurons maintain one of the highest intracellular concentrations of vitamin C in the organism, the brain may still be more sensitive to deficiency despite these preventive measures.

OBJECTIVE

The objective was to study the potential link between chronic vitamin C deficiency and neuronal damage in newborn guinea pigs.

DESIGN

Thirty 6- to 7-d-old guinea pigs were randomly assigned to 2 groups to receive either a vitamin C-sufficient diet or the same diet containing a low concentration of vitamin C (but adequate to prevent scurvy) for 2 mo. Spatial memory was assessed by the Morris Water Maze, and hippocampal neuron numbers were quantified by stereologic techniques.

RESULTS

The results showed a reduction in spatial memory (P < 0.05) and an increased time to first platform hit (P < 0.05) in deficient animals compared with controls. The deficient animals had a lower total number of neurons in hippocampal subdivisions (dentate gyrus, cornu ammonis 1, and cornu ammonis 2-3) than did the normal controls (P < 0.05).

CONCLUSIONS

Our data show that vitamin C deficiency in early postnatal life results in impaired neuronal development and a functional decrease in spatial memory in guinea pigs. We speculate that this unrecognized effect of vitamin C deficiency may have clinical implications for high-risk individuals, such as in children born from vitamin C-deficient mothers.

Comparative analysis of ascorbic acid in human milk and infant formula using varied milk delivery systems

Background

The expression of human milk for later use is on the rise. Bottle systems are used to deliver the expressed milk. Research has shown that storage of both human milk and artificial baby milk, or infant formula, leads to a loss of ascorbic acid (commonly called Vitamin C). As milk is removed from the bottle during feeding and replaced by ambient air, it is unknown if loss of ascorbic acid occurs during the course of a feeding. The purpose of this study is to investigate the effect of the milk delivery system on levels of ascorbic acid in human milk and infant formula. The objectives are to 1) determine changes in ascorbic acid concentration during a 20 minute "feed," 2) determine if there is a difference in ascorbic acid concentration between delivery systems, and 3) evaluate if any differences are of clinical importance.

Methods

Commonly available bottles were used for comparison of bottle delivery systems. Mature human milk was standardized to 42 mg/L of ascorbic acid. Infant formula with iron and infant formula with docosahexanoic acid were used for the formula samples. Each sample was analyzed for ascorbic acid concentration at baseline (0), 5, 10, 15, and 20 minutes. Each collection of samples was completed in triplicate. Samples were analyzed for ascorbic acid using normal-phase high performance liquid chromatography.

Results

Ascorbic acid concentration declined in all bottle systems during testing, Differences between the bottle systems were noted. Ascorbic acid concentrations declined to less than 40% of recommended daily intake for infants in 4 of the bottles systems at the 20 minute sampling.

Conclusion

The bottle systems used in this study had measurable decreases in the mean concentration of ascorbic acid. More research is needed to determine if the observed decreases are related to lower plasma ascorbic acid concentration in infants exclusively bottle fed. The decrease of ascorbic acid concentration observed in both human milk and infant formula using varied milk delivery systems may be of clinical importance. For infants who rely solely on bottle feeds there may be increased risk of deficiency. Bottle shape, size, and venting should be considered.

Oxidative stress and nutrition in the preterm newborn

Oxidative stress occurs when the production of free radicals exceeds the cells' ability to eliminate them. Many events leading to overproduction of free radicals may easily induce oxidative stress in the earliest phases of human life. Given the growing role of oxidative stress in newborn preterm morbidity, one of the goals of modern neonatology is to minimize free radical production and promote the development of adequate antioxidant systems through an adequate nutritional strategy. Appropriate administration of total parenteral solutions and lipid emulsions with light protection can minimize the risk of peroxidation. Providing the baby with amino acid substrates for cellular glutathione synthesis immediately after birth promotes antioxidant defenses at the early stages of life. Breast milk has been found to have many advantages over formula, including the potential to provide antioxidant protection to infants. It is conceivable that these antioxidants in breast milk help to eliminate free radicals in infants. The role of vitamin administration in preterm nutrition has not yet been established. Clinical trials carried out to test the efficacy of antioxidant drugs or vitamins were inconclusive. At present, there are no evidence-based recommendations about the use of nutritional strategies or antioxidant drugs to minimize oxidative stress in the management of preterm infants.

Anti-oxidant strategies

Oxidative stress plays an important role in causing organ injury in the compromised fetus and neonate. Recent experimental research and clinical studies have clarified important pathways in the production of reactive oxygen and nitrogen species. Free radicals are involved in causing cerebral damage after perinatal hypoxia-ischemia affecting membrane lipids, proteins, and DNA. Anti-oxidant strategies can be used as add-on neuroprotective therapy after perinatal oxidative stress. Selective inhibitors of neuronal and inducible nitric oxide synthase, allopurinol, melatonin, and erythropoietin are among the first compounds that are ready for clinical trials.

Impact of iron and vitamin C-containing supplements on preterm human milk: in vitro

Stress due to reactive oxygen species (ROS) may lead to neonatal diseases, such as necrotizing enterocolitis and respiratory distress. Enteral supplements for premature infants (PREM) added to human milk (HM) to increase nutrient content may induce lipid oxidation due to free radical formation via Fenton chemistry. We hypothesized that ferrous iron and vitamin C-containing supplements added to HM in vitro cause oxidation of milk fats, affect intracellular redox balance, and induce DNA damage. Lipid peroxidation in HM was measured by FOX-2 and TBARS assays; fatty acid composition of supplemented HM was measured by gas chromatography. Two cell culture bioassays were used for assessing either intracellular oxidative stress or DNA damage: the former involved Caco-2BBe cells, a secondary differentiated cell line, and the latter utilized FHS-74 Int cells, a primary fetal small intestinal culture. Lipid oxidation products of HM increased after the addition of iron alone, iron and vitamin C, or iron and a vitamin C-containing supplement (Trivisol, TVS). A reduced content of mono and polyunsaturated fatty acids in HM was also observed. Iron, not iron+vitamin C, but iron+TVS induced significant intracellular oxidative stress in FHS-74 Int cells. In contrast, iron, either alone or in combination with TVS or vitamin C, increased DNA damage in Caco-2BBE cells. Iron supplementation may increase oxidative stress in PREM infants and should be given separately from vitamin C-containing supplements.

Immunomodulatory effect of vitamin C on intracytoplasmic cytokine production in neonatal cord blood cells

BACKGROUND

Vitamin C (ascorbic acid) is an essential water-soluble antioxidant in cells and plasma. Besides metabolic functions, vitamin C is also known to contribute to immune homeostasis. Recently, it has been demonstrated that vitamin C has an inhibitory effect on the expression of pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor alpha (TNF-alpha) in adult whole blood cells in vitro. It has been postulated that vitamin C might be an interesting compound for modulation of an over-exuberant immune response, e.g., in patient cohorts susceptible for the development of systemic inflammatory response syndrome such as neonates. It was the aim of this study to investigate the modulatory effects of vitamin C on the production of inflammatory mediators in neonatal cord blood cells.

METHODS

The intracytoplasmic production of pro-inflammatory cytokines in neonatal cord blood cells stimulated with lipopolysaccharide or phorbol 12-myristate 13-acetate/ionomycin was assessed by flow-cytometry.

RESULTS

In contrast to our previous observations from adult whole blood cells, 20 mM vitamin C mildly stimulated the percentage of neonatal monocytes producing IL-6 after lipopolysaccharide stimulation (e.g., 11.3% increase compared to control, p = 0.005). In the presence of 20 mM vitamin C, even a stronger stimulatory effect was noted for the percentage of IL-8 (e.g., 46.7% increase, p < 0.001) and TNF-alpha producing neonatal monocytes (e.g., 69.2% increase, p = 0.004; n = 20). In accordance with adult data, the percentage of neonatal lymphocytes producing IL-2 after phorbol 12-myristate 13-acetate/ionomycin stimulation was dose-dependently reduced (e.g., 41.3% inhibition, p = 0.001, 20 mM vitamin C), while the percentage of TNF-alpha producing lymphocytes was mildly stimulated (e.g., 20.8% increase, p = 0.003, 20 mM vitamin C).

CONCLUSIONS

Interestingly, vitamin C was demonstrated to enhance pro-inflammatory responses in CD14(+) cord blood cells while only intracellular IL-2 production in CD3(+) cells was diminished. These data suggest that vitamin C differentially influences intracytoplasmic cytokine production in adults and neonates, and further studies are needed to elucidate the underlying mechanisms of this selective immunomodulation.

Oxygen and retinopathy of prematurity

Retinopathy of prematurity is on the rise and a third epidemic has been identified. In spite of extensive research and progress in the understanding of this disease in recent years, 50 000 children worldwide are blinded by this condition each year. The relation between hyperoxia, low-gestational age, growth retardation, oxygen dependent growth factors, and oxidative stress are now being understood more clearly. We know that in the first phase of retinopathy of prematurity, hyperoxia inhibits vascular endothelial growth factor. In the second phase, vascular endothelial growth factor rises, and when insulin-like growth factor-1 reaches a threshold around 32 to 34 weeks postconceptional age, uncontrolled neovascularization may occur. It is not known whether this new knowledge will have implications for future therapy. However, by strictly avoiding hyperoxia, that is, SaO2>92-93% and avoiding fluctuations in SaO2, it is possible to control and prevent severe retinopathy of prematurity in most cases.