Vitamin A supplementation in very low birth weight neonates: rationale and evidence

The role of nutritional interventions in the prevention and treatment of chronic lung disease of prematurity

Chronic lung disease of prematurity or bronchopulmonary dysplasia (BPD) is a common complication of preterm birth. Nutrition may affect incidence and severity of BPD. In this context, the Section on Nutrition, Gastroenterology and Metabolism, the Pulmonary Section of the European Society for Paediatric Research (ESPR) and SPR have joined forces to review the current knowledge on nutritional issues related to BPD. The aim of this narrative review is to discuss the clinical implications for nutritional practice. Nutrient deficiencies may influence pathogenesis of BPD. Adequate nutrition and growth can play a crucial role in the prevention of and recovery from BPD. Optimal nutrition strategy is an important principle, especially in the early postnatal period. As optimal energy intake in infants at risk of BPD or with evolving BPD is not yet defined, further research with well-designed studies on nutritional strategies for preterm infants with BPD is urgently needed. IMPACT: Based on current evidence it seems reasonable to recommend that BPD diagnosed infants should receive an energy supply ranging from 120 to 150 Kcal/kg/d. Exclusive MOM feed with adequate fortification should be encouraged as this is associated with a significant reduction in the risk of BPD. Suboptimal nutritional delivery is often seen in preterm infants with BPD compared to controls.

Vitamin A Status in Preterm Infants Is Associated with Inflammation and Dexamethasone Exposure

Vitamin A has a key role in lung development and its deficiency is associated with an increased risk of bronchopulmonary dysplasia. This secondary cohort analysis of the ImNuT trial (Immature, Nutrition Therapy NCT03555019) aimed to (1) explore vitamin A status in preterm infants <29 weeks gestation and (2) assess the influence of inflammation and postnatal dexamethasone exposure on vitamin A concentrations in blood. We report detailed information on vitamin A biochemistry, vitamin A intake, markers of inflammation and dexamethasone exposure. After four weeks of age, infants exposed to dexamethasone (n = 39) showed higher vitamin A concentrations compared to unexposed infants (n = 41); median (IQR) retinol was 1.0 (0.74, 1.5) vs. 0.56 (0.41, 0.74) µmol/L, p < 0.001. Pretreatment retinol concentrations were lower in the dexamethasone group compared to non-exposed infants (p < 0.001); 88% vs. 60% of the infants were considered deficient in vitamin A (retinol < 0.7 µmol/L) at one week of age. Small size for gestational age, mechanical ventilation and elevated levels of interleukin-6 were factors negatively associated with first-week retinol concentrations. In conclusion, preterm infants <29 weeks gestation are at risk of vitamin A deficiency despite intakes that accommodate current recommendations. The presence of inflammation and dexamethasone exposure should be considered when interpreting vitamin A status.

Dilemmas in human milk fortification

Fortification of human milk is the standard of care for very low birth weight (VLBW) infants and is required to support adequate postnatal growth and development. Achieving adequate growth velocity and preventing growth faltering is critical for the developing neonatal brain and optimizing long-term neurodevelopmental outcomes. Mother's milk is the gold standard nutrition to feed preterm infants, however, it does not provide the nutrients needed to support the growth of VLBW infants. After the decision is made to use mother's milk (if available) or alternatively, donor human milk, many dilemmas exist with regards to additional treatment decisions surrounding the type of fortification to use, when to fortify, and the duration of fortification. In this article, we will review the differences in mother's milk compared to donor milk, the different types of human milk fortifiers, the optimal timing of fortification, and discuss when to discontinue human milk fortification.

Epigenome-wide association study of bronchopulmonary dysplasia in preterm infants: results from the discovery-BPD program

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a lung disease in premature infants caused by therapeutic oxygen supplemental and characterized by impaired pulmonary development which persists into later life. While advances in neonatal care have improved survival rates of premature infants, cases of BPD have been increasing with limited therapeutic options for prevention and treatment. This study was designed to explore the relationship between gestational age (GA), birth weight, and estimated blood cell-type composition in premature infants and to elucidate early epigenetic biomarkers associated with BPD.

METHODS

Cord blood DNA from preterm neonates that went on to develop BPD (n = 14) or not (non-BPD, n = 93) was applied to Illumina 450 K methylation arrays. Blood cell-type compositions were estimated using DNA methylation profiles. Multivariable robust regression analysis elucidated CpGs associated with BPD risk. cDNA microarray analysis of cord blood RNA identified differentially expressed genes in neonates who later developed BPD.

RESULTS

The development of BPD and the need for oxygen supplementation were strongly associated with GA (BPD, p < 1.0E-04; O2 supplementation, p < 1.0E-09) and birth weight (BPD, p < 1.0E-02; O2 supplementation, p < 1.0E-07). The estimated nucleated red blood cell (NRBC) percent was negatively associated with birth weight and GA, positively associated with hypomethylation of the tobacco smoke exposure biomarker cg05575921, and high-NRBC blood samples displayed a hypomethylation profile. Epigenome-wide association study (EWAS) identified 38 (Bonferroni) and 275 (false discovery rate 1%) differentially methylated CpGs associated with BPD. BPD-associated CpGs in cord blood were enriched for lung maturation and hematopoiesis pathways. Stochastic epigenetic mutation burden at birth was significantly elevated among those who developed BPD (adjusted p = 0.02). Transcriptome changes in cord blood cells reflected cell cycle, development, and pulmonary disorder events in BPD.

CONCLUSIONS

While results must be interpreted with caution because of the small size of this study, NRBC content strongly impacted DNA methylation profiles in preterm cord blood and EWAS analysis revealed potential insights into biological pathways involved in BPD pathogenesis.

Early Vitamin A Supplementation for Prevention of Short-Term Morbidity and Mortality in Very-Low-Birth-Weight Infants: A Systematic Review and Meta-Analysis

Background

Vitamin A plays an important role in the development and maintenance of the normal function of organs and systems. Premature infants have low levels of vitamin A, which may be associated with an increased risk of developing disease. This study aimed to evaluate the effects of vitamin A supplementation on short-term morbidity and mortality in very-low-birth-weight (VLBW) infants.

Methods

We used PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, and Web of Science to conduct a literature search of studies published before January 1, 2022, to be included in our meta-analysis. The analysis included randomized controlled trials that compared the effects of vitamin A supplementation on VLBW infants (birth weight <1,500 g) and controls given a placebo or no treatment. The certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) guidelines.

Results

Twelve randomized controlled trials were included in the meta-analysis, and 2,111 infants were pooled and analyzed. The overall risk of bias was not serious in the included studies. Vitamin A supplementation for reducing the incidence of bronchopulmonary dysplasia (BPD) at 36 weeks' postmenstrual age seems to be limited [risk ratio (RR):0.85; 95% confidence intervals (CI): 0.70-1.04; 8 studies, 1,595 infants, very-low-certainty evidence], which is different from the previous systematic review. Length of hospital stay (mean difference: -12.67, 95% CI: -23.55 to -1.79; 6 studies, 739 infants, low-certainty evidence), and the incidence of vitamin A deficiency at 28 days postnatal age (RR: 0.08; 95% CI: 0.02-0.38; 3 studies, 358 infants, low-certainty evidence) were reduced in the vitamin A group. Besides, vitamin A supplementation seems to reduce the incidence of periventricular leukomalacia (RR: 0.68; 95% CI: 0.47-0.97; 4 studies, 1,224 infants, low-certainty evidence) and retinopathy of prematurity of any grade (RR: 0.61; 95% CI: 0.48-0.76; 4 studies, 463 infants, moderate-certainty evidence).

Conclusions

There is no sufficient evidence regarding vitamin A supplementation preventing BPD in VLBW infants. Vitamin A supplementation can reduce the incidence of vitamin A deficiency and retinopathy of prematurity of any grade, and may exert an effect of preventing periventricular leukomalacia.

Systematic Review Registration

http://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42020211070.

Vitamin A supplementation in very-preterm or very-low-birth-weight infants to prevent morbidity and mortality: a systematic review and meta-analysis of randomized trials

BACKGROUND

A previous systematic review showed that intramuscular vitamin A supplementation reduced the risk of bronchopulmonary dysplasia (BPD) in very-low-birth-weight (VLBW) infants. However, more recent studies have questioned this finding.

OBJECTIVES

Our objective was to synthesize current evidence on vitamin A supplementation in very-preterm (<32 wk gestational age) or VLBW infants and investigate the factors that may modify its efficacy.

METHODS

A systematic review was conducted using the Cochrane systematic review methodology. We included randomized controlled trials investigating vitamin A supplementation for reducing morbidity and mortality in very-preterm or VLBW infants. Certainty of evidence was assessed using Grading of Recommendations, Assessment, Development and Evaluation (GRADE) recommendations. Prespecified subgroup analyses assessed factors that may modify the effects of vitamin A supplementation.

RESULTS

We included 17 studies (n = 2471) in the qualitative and 15 studies (n = 2248) in the quantitative synthesis. Moderate-certainty evidence suggested a beneficial effect of vitamin A for decreasing the risk of BPD at 36 wk postmenstrual age (RR: 0.83; 95% CI: 0.74, 0.93; numbers needed to treat for an additional beneficial outcome: 16; 95% CI: 9, 53; 9 studies, n = 1752; P = 0.002). Subgroup analysis suggested that the beneficial effect was limited to infants with baseline vitamin A intake <1500 IU · kg-1 · d-1. Both enteral and parenteral routes were effective. Vitamin A supplementation did not have adverse effects and did not alter mortality before discharge (12 studies, n = 1917) or neurodevelopmental outcomes at 18-22 mo (1 study, n = 538).

CONCLUSIONS

The benefit of vitamin A supplementation for reducing BPD is likely to be limited to infants with baseline vitamin A intake <1500 IU · kg-1 · d-1 and is not affected by the route of administration.

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

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

Nutritional Composition and Bioactive Compounds in Three Different Parts of Mango Fruit

Mango (Mangifera indica L.), known as the king of fruits, has an attractive taste and fragrance and high nutritional value. Mango is commercially important in India, where ~55% of the global crop is produced. The fruit has three main parts: pulp, peel, and kernel. The pulp is the most-consumed part, while the peel and kernel are usually discarded. Mango pulp is a source of a variety of reducing sugars, amino acids, aromatic compounds, and functional compounds, such as pectin, vitamins, anthocyanins, and polyphenols. Mango processing generates peels and kernels as bio-wastes, though they also have nutraceutical significance. Functional compounds in the peel, including protocatechuic acids, mangiferin and β-carotene are known for their antimicrobial, anti-diabetic, anti-inflammatory, and anti-carcinogenic properties. The mango kernel has higher antioxidant and polyphenolic contents than the pulp and peel and is used for oil extraction; it's possible usage in combination with corn and wheat flour in preparing nutraceuticals is being increasingly emphasized. This review aims to provide nutraceutical and pharmacological information on all three parts of mango to help understand the defense mechanisms of its functional constituents, and the appropriate use of mangoes to enhance our nutrition and health.

Saliva for Assessing Vitamin A Status in Extremely Preterm Infants: A Diagnostic Study

BACKGROUND

Salivary measurement of hormones and vitamins is gaining prominence as a minimally invasive procedure with the negligible potential for harm. We aimed to assess the utility of saliva for assessing vitamin A status in extremely preterm infants.

METHODS

Paired saliva and blood samples were collected at 4 weeks of age from infants born <28 weeks of gestation using a proprietary polymer swab. Plasma retinol was measured using high-performance liquid chromatography, and salivary retinol was measured using enzyme-linked immunosorbent assay.

RESULTS

Thirty infants were recruited with a median (IQR) gestation and birth weight of 26.2 weeks (24.8-27.2) and 865 g (718-1,002), respectively. An adequate volume of saliva (>50 µL) was obtained in 68%. There was no significant correlation (Spearman's correlation coefficient = 0.16, p = 0.3) between individual plasma and salivary retinol levels. Bland-Altman analysis showed wide limits of agreement (-113 to +119%) between individual plasma and salivary retinol levels.

CONCLUSION

Individual vitamin A status cannot be determined reliably from saliva in extremely preterm infants using current collection materials and analysis techniques.

Pharmacotherapy for the Prevention of Bronchopulmonary Dysplasia: Can Anything Compete with Caffeine and Corticosteroids?

Bronchopulmonary dysplasia (BPD) is a morbidity of prematurity with implications for respiratory and neurologic health into adulthood. Multiple risk factors contribute to the development of BPD leading to examination of various prevention strategies. The roles of systemic corticosteroids and caffeine have been addressed by the American Academy of Pediatrics. The place in therapy of other agents commonly utilized in clinical practice remains unclear. Inhaled nitric oxide has been the subject of numerous large, randomized controlled trials in preterm infants. Despite sound rationale, these trials have largely failed to document benefit, suggesting a limited role for inhaled nitric oxide therapy in the preterm population. In contrast, intramuscular vitamin A has been documented to reduce the incidence of BPD in randomized trials. However, the invasiveness and the sporadic availability of this therapy have led to decreased utilization. All macrolide antibiotics do not appear to have a similar impact on the incidence of BPD; however, azithromycin administered to infants colonized with Ureaplasma may have impact. Questions remain about the optimal dosing approach and long-term safety of this intervention. Finally, diuretic therapy is widely used in clinical practice despite significant toxicities and limited data supporting a role in BPD prevention. Taken together, available data suggest that caffeine and selective use of corticosteroids remain the mainstays of pharmacologic BPD prevention.

Intramuscular Followed by Oral Vitamin A Supplementation in Neonates with Birth Weight from 750 to 1250 g: A Randomized Controlled Trial

Multiple intramuscular (IM) injections of vitamin A have been shown to decrease bronchopulmonary dysplasia in very low birth weight (VLBW) neonates. However, this regime is neither practical nor popular. Oral vitamin A has failed to achieve adequate plasma levels. We aimed to investigate if a schedule of initial IM followed by oral supplementation can reduce vitamin A deficiency. This was a blinded, randomized controlled trial, conducted in a level III neonatal unit. Neonates with birth weight from 750 to 1250 g, were enrolled at the age of 24-96 h of life. They were randomly allocated to vitamin A supplementation (VAS) (n = 61) or placebo group (n = 59). VAS group received vitamin A 5000 IU IM on alternate days till establishment of adequate enteral feeds, followed by oral 10,000 IU daily for 28 days. The primary outcome was incidence of vitamin A deficiency (plasma retinol < 200 μg/L) on day 28. A total of 120 neonates with mean (SD) gestation age and birth weight of 31 (2.4) weeks and 1065 (141) g, respectively were enrolled. More than 90% of cases were vitamin A deficient at the baseline. The proportion of vitamin A deficient infants on day 28 of study was significantly lower in VAS group compared to placebo group (4% vs. 61%, p < 0.001). The median (1st-3rd quartile) plasma retinol levels (μg/L) were significantly higher in VAS group compared to placebo [489 (295,627) vs. 184 (156,240), p < 0.001]. We conclude that the IM followed by oral VAS significantly reduced the incidence of vitamin A deficiency in VLBW infants.

Enteral vitamin A for reducing severity of bronchopulmonary dysplasia in extremely preterm infants: a randomised controlled trial

Background

Intramuscular vitamin A supplementation decreases the risk of bronchopulmonary dysplasia (BPD) in very-low-birth-weight preterm infants without significant adverse effects. However, intramuscular vitamin A supplementation is not widely accepted because of the discomfort and risk of trauma associated with repeated injections. Enteral vitamin A supplementation has not been studied adequately in the clinical trials. Enterally administered water-soluble vitamin A is absorbed better than the fat-soluble form. We hypothesised that enteral administration of a water-soluble vitamin A preparation will decrease severity of BPD compared with a control group receiving placebo.

Methods

We plan a double-blind randomised placebo-controlled trial at a tertiary neonatal-perinatal intensive care unit. Eligibility criteria include infants born at less than 28 weeks’ gestational age and less than 72 h of life. Infants with major congenital gastrointestinal or respiratory tract abnormalities will be excluded. After parental consent, infants will be randomized to receive either enteral water-soluble vitamin A (5000 IU once a day) or placebo. The intervention will be started within 24 h of introduction of feeds and continued until 34 weeks’ post-menstrual age (PMA).

The primary outcome is severity of BPD at 36 weeks’ PMA. Severity of BPD will be assessed objectively from the right-shift of the peripheral oxyhaemoglobin saturation versus partial pressure of inspired oxygen (SpO₂-PiO₂) curve. We require 188 infants for 80% power and 5% significance level based on an expected 20% decrease in the right shift of the SpO₂-PiO₂ curve in the vitamin A group (primary outcome) compared with control group at 36 weeks’ PMA, and a 20% attrition rate.

Secondary outcomes will be plasma and salivary concentrations of vitamin A on day 28 of the trial (first 30 infants), lung and diaphragm function, clinical outcomes at 36 week’ PMA or before discharge/death, and safety of vitamin A.

Discussion

BPD poses a significant economic burden on the health-care system. If our study shows that enteral supplementation of water-soluble vitamin A is safe and effective for decreasing the severity of BPD, it will provide the opportunity to further evaluate a simple, globally acceptable preventive therapy for BPD.

Trial registration

ANZCTR; ACTRN12616000408482 (30th March 2016).

Electronic supplementary material

The online version of this article (10.1186/s12887-017-0958-x) contains supplementary material, which is available to authorized users.

Vitamin A Supplementation for Prevention of Bronchopulmonary Dysplasia: Cornerstone of Care or Futile Therapy?

OBJECTIVE

To review the evidence on vitamin A supplementation (VAS) and bronchopulmonary dysplasia (BPD) in extremely-low-birth-weight infants. We also discuss the impact of a vitamin A shortage on BPD rates.

DATA SOURCES

A PubMed search inclusive of dates 1946 to March 2016 was performed using the search terms bronchopulmonary dysplasia, chronic lung disease (CLD), and vitamin A STUDY SELECTION AND DATA EXTRACTION: All English-language studies were evaluated. Only those investigating VAS by intramuscular administration were included.

DATA SYNTHESIS

A total of 6 studies were evaluated. Additionally, a report on the incidence of BPD during a national shortage was reviewed. Investigators found mixed results with VAS and incidence of CLD or death in a varying number of neonates. In the largest evaluation, investigators found a statistically significant decrease in the rate of death or BPD: 55% in the VAS group versus 62% in the placebo group. The number needed to treat to prevent 1 case of BPD was 15 infants. Few studies found an increased incidence of adverse events following VAS. A report over a 2-year shortage period found that whereas the rate of VAS declined dramatically, BPD rates remained stable. This large observational evaluation calls into question the place of vitamin A in BPD prevention.

CONCLUSIONS

VAS has been identified as a strategy to decrease the incidence of BPD. Initial large-scale prospective evaluations have shown clear benefit of VAS in reducing the incidence of CLD or death. However, changing definitions of BPD and implementation of noninvasive ventilation strategies limit the application of early studies. During a drug shortage, VAS declined dramatically, but BPD rates remained stable. With concerns of sepsis and necrotizing enterocolitis in small-scale studies, and in light of the recent shortage evidence, further evaluations are necessary before VAS can be recommended as a cornerstone of BPD prevention.

Anti-oxidant profiles and markers of oxidative stress in preterm neonates

BACKGROUND

Preterm birth is associated with an increased oxidant burden which places these infants at a higher risk of injury.

AIMS

This prospective study aimed to assess levels of antioxidants and a marker of oxidative stress in preterm neonates.

OBJECTIVES

(i) To compare levels of anti-oxidants [vitamin A, vitamin E, catalase, total anti-oxidant status (TAS)] as well as malondialdehyde level (MDA) (a marker of lipid peroxidation) between preterm and full-term neonates; (ii) to determine changes in the values of measured vitamins at birth and at discharge among preterm neonates; and (iii) to compare levels of anti-oxidants with MDA levels in relation to complications of prematurity and outcome.

METHODS

The study was undertaken in 100 preterm neonates and 100 full-term neonates as a control group. MDA was estimated by a thiobarbituric acid-reactive technique; TAS was determined using a Randox assay kit; catalase activity was measured spectrophotometrically and vitamin A and E levels were estimated by high performance liquid chromatography.

RESULTS

The plasma levels of vitamin A, vitamin E, TAS and catalase were significantly lower in the preterm than in the full-term group (P < 0.01), and the plasma level of MDA was significantly higher in preterm than full-term neonates (P < 0.01). Vitamin A and E levels in preterm neonates were significantly higher at discharge than at birth (P < 0.01). Vitamin A, vitamin E and catalase levels at birth were significantly lower in patients who developed necrotizing enterocolitis or bronchopulmonary dysplasia than in those who did not.

CONCLUSION

Preterm neonates are exposed to increased oxidant stress at birth and are susceptible to anti-oxidant deficiencies. A higher dose of enteral vitamin A supplementation in preterm neonates might reduce morbidity and improve outcome. Further studies are warranted to evaluate the appropriate dose of oral vitamin E supplementation for preterm neonates.

Effect of Hyperoxia on Retinoid Metabolism and Retinoid Receptor Expression in the Lungs of Newborn Mice

BACKGROUND

Preterm newborns that receive oxygen therapy often develop bronchopulmonary dysplasia (BPD), which is abnormal lung development characterized by impaired alveologenesis. Oxygen-mediated injury is thought to disrupt normal lung growth and development. However, the mechanism of hyperoxia-induced BPD has not been extensively investigated. We established a neonatal mouse model to investigate the effects of normobaric hyperoxia on retinoid metabolism and retinoid receptor expression.

METHODS

Newborn mice were exposed to hyperoxic or normoxic conditions for 15 days. The concentration of retinol and retinyl palmitate in the lung was measured by HPLC to gauge retinoid metabolism. Retinoid receptor mRNA levels were assessed by real-time PCR. Proliferation and retinoid receptor expression in A549 cells were assessed in the presence and absence of exogenous vitamin A.

RESULTS

Hyperoxia significantly reduced the body and lung weight of neonatal mice. Hyperoxia also downregulated expression of RARα, RARγ, and RXRγ in the lungs of neonatal mice. In vitro, hyperoxia inhibited proliferation and expression of retinoid receptors in A549 cells.

CONCLUSION

Hyperoxia disrupted retinoid receptor expression in neonatal mice.

Effects of early inhaled nitric oxide therapy and vitamin A supplementation on the risk for bronchopulmonary dysplasia in premature newborns with respiratory failure

OBJECTIVE

To assess whether the combination of early inhaled nitric oxide (iNO) therapy and vitamin A supplementation lowers the incidence of bronchopulmonary dysplasia (BPD) in premature newborns with respiratory failure.

STUDY DESIGN

A total of 793 mechanically ventilated infants (birth weight 500-1250 g) were randomized (after stratification by birth weight) to receive placebo or iNO (5 ppm) for 21 days or until extubation (500-749, 750-999, or 1000-1250 g). A total of 398 newborns received iNO, and of these, 118 (30%) received vitamin A according to their enrollment center. We compared patients who received iNO + vitamin A with those who received iNO alone. The primary outcome was a composite of death or BPD at 36 weeks postconceptual age.

RESULTS

BPD was reduced in infants who received iNO + vitamin A for the 750-999 g birth weight group compared with iNO alone (P = .01). This group also showed a reduction in the combined outcome of BPD + death compared with iNO alone (P = .01). The use of vitamin A did not change the risk for BPD in the placebo group. Overall, the use of vitamin A was low (229 of 793 patients, or 29%). Combined therapy improved Bayley Scales of Infant Development II Mental and Psychomotor Developmental Index scores at 1 year compared with infants treated solely with iNO for the 500-749 g birth weight group.

CONCLUSIONS

In this retrospective analysis of the nonrandomized use of vitamin A, combined iNO + vitamin A therapy in preterm infants with birth weight 750-999 g reduced the incidence of BPD and BPD + death and improved neurocognitive outcomes at 1 year in the 500-749 g birth weight group.

Vitamin A for preterm infants; where are we now?

In the 35 years since low plasma vitamin A levels were first described in premature infants, much effort has gone into attempting to describe the functional consequences of vitamin A deficiency in this population. Supplementation of extremely low birth weight infants with intramuscular (i.m.) vitamin A has a significant but modest beneficial effect upon the development of chronic lung disease (NNT 13), most likely due to reduced production of pro-inflammatory cytokines. Early high dose i.m. vitamin A also improves retinal development and there are limited clinical and laboratory data suggesting a role for vitamin A in prevention of retinopathy of prematurity. Despite evidence of benefit, there is reluctance to give routine i.m. vitamin A in the neonatal intensive care unit, but current intravenous supplementation is almost certainly inadequate. Further work is required to identify the optimal dose and most appropriate route of administration of vitamin A for preterm infants.

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.

Vitamin A is systemically bioavailable after intratracheal administration with surfactant in an animal model of newborn respiratory distress

Chronic lung disease (CLD) is a major cause of long-term morbidity in extremely LBW infants with respiratory distress syndrome. Parenteral vitamin A administration decreases the risk of CLD. We tested the hypothesis that intratracheal vitamin A administration with surfactant is systemically bioavailable without interfering with the functional properties of exogenous surfactant. Newborn piglets were ventilated with 100% FiO2 and sequential saline lavage induced respiratory distress syndrome. During lung injury induction, ventilator changes were allowed, but none were made following treatment allocation. Animals were assigned by chance in a blinded control trial to three groups: I=control; II=surfactant; III=surfactant+vitamin A. Hemodynamics, lung mechanics, and blood gases were measured following instrumentation, pre- and posttreatment for 4 h, at which time the liver was sampled for retinol determination. All parameters improved in animals receiving surfactant. A significant interaction existed between time and group for PaO2 and alveolar-arterial oxygen difference (A-aDO2). Hepatic levels of retinol were higher (p<0.001) in animals receiving retinyl acetate. Intratracheal administration of surfactant+vitamin A did not alter the beneficial effects of surfactant on lung compliance and gas exchange. Intratracheal Vitamin A was associated with rapid hepatic uptake. Further studies are warranted.

Oxygen toxicity and reactive oxygen species: the devil is in the details

Reactive oxygen species (ROS) serve as cell signaling molecules for normal biologic processes. However, the generation of ROS can also provoke damage to multiple cellular organelles and processes, which can ultimately disrupt normal physiology. An imbalance between the production of ROS and the antioxidant defenses that protect cells has been implicated in the pathogenesis of a variety of diseases, such as cancer, asthma, pulmonary hypertension, and retinopathy. The nature of the injury will ultimately depend on specific molecular interactions, cellular locations, and timing of the insult. This review will outline the origins of endogenous and exogenously generated ROS. The molecular, cellular, pathologic, and physiologic targets will then be discussed with a particular emphasis on aspects relevant to child development. Finally, antioxidant defenses that scavenge ROS and mitigate associated toxicities will be presented, with a discussion of potential therapeutic approaches for the prevention and/or treatment of human diseases using enzymatic and nonenzymatic antioxidants.

Newborn vitamin A supplementation reduced infant mortality in rural Bangladesh

OBJECTIVES

We assessed the effect of supplementing newborns with 50000 IU of vitamin A on all-cause infant mortality through 24 weeks of age.

PATIENTS AND METHODS

This was a community-based, double-masked, cluster-randomized, placebo-controlled trial conducted in 19 unions in rural northwest Bangladesh. The study was nested into and balanced across treatment arms of an ongoing placebo-controlled, weekly maternal vitamin A or beta-carotene supplementation trial. Study-defined sectors (N = 596) were evenly randomized for newborns of participating mothers to receive a single, oral supplement of vitamin A (50000 IU) or placebo as droplets of oil squeezed from a gelatinous capsule. Mothers provided informed consent for newborn participation at approximately 28 weeks' gestation. After birth, typically at home (where >90% of births occurred), infants were supplemented and their vital status was followed through 24 weeks of age. The main outcome measure was mortality through 24 weeks of age.

RESULTS

We obtained maternal consent to dose 17116 live-born infants (99.8% of all eligible) among whom 15937 (93.1%) were visited to be supplemented <30 days after birth and for whom vital status at 24 weeks of age was known. Dosed infants (n = 15902 [99.8%]) received their study supplement at a median age of 7 hours. Relative to control subjects, the risk of death in vitamin A-supplemented infants was 0.85, reflecting a 15% reduction in all-cause mortality. Protective relative risks were indistinguishable by infant gender, gestational age, birth weight, age at dosing, maternal age, parity, or across the 3 treatment arms of the maternal supplementation trial.

CONCLUSIONS

Newborn vitamin A dosing improved infant survival through the first 6 months of life in Bangladesh. These results corroborate previous findings from studies in Indonesia and India and provide additional evidence that vitamin A supplementation shortly after birth can reduce infant mortality in South Asia.

Improved vitamin A supplementation regimen for breastfed very low birth weight infants

OBJECTIVE

Preterm infants usually have low retinol status at birth and at discharge from hospital. We have evaluated a new protocol designed to improve plasma retinol in very low birth weight infants (VLBW, birth weight < 1500 g).

DESIGN

An open intervention trial was conducted in which vitamin A was given in a human milk fortifier. The daily dose of vitamin A varied according to bodyweight and was given mixed with human milk instead of as a bolus. Blood samples were collected at inclusion and at discharge from hospital. Plasma was analyzed for retinol using high-performance liquid chromatography. The daily intake of vitamin A and plasma retinol concentration was compared with the vitamin protocol normally used in Norwegian hospitals.

RESULTS

Sixty VLBW infants were included and 53 completed the study. At discharge from hospital, the reference group had lower median plasma retinol concentrations compared to the modified group (0.30 microM vs. 0.49 microM, p = 0.008). Fewer infants in the modified group had plasma retinol levels below 0.35 microM (indicating reduced hepatic stores) compared to infants in the reference group (44% vs. 69%, p = 0.04).

CONCLUSION

The modified protocol improved plasma retinol levels at discharge compared to the reference protocol.

Shielding parenteral multivitamins from light increases vitamin A and E concentration in lung of newborn guinea pigs

BACKGROUND & AIMS

Exposure of parenteral multivitamin preparation (MVP) to light generates peroxides. Light-exposed MVP induces an oxidant stress in lung but not in liver. This discrepancy suggests differences in handling of infused antioxidant vitamins between the two organs.

HYPOTHESIS

antioxidant capacity of lung depends on the MVP concentration and light protection of infused solutions.

METHODS

Protocol 1: four groups of three-day old guinea pigs received the base solution (5% dextrose + 0.45% NaCl) enriched with 0%, 1%, 2% and 3% MVP. Protocol 2: three further groups received the base solution + 2% MVP either light-exposed or light-protected or light-protected + 300 microM H2O2. After 4 days, lung and liver were sampled for vitamin determinations. Data were analyzed by ANOVA.

RESULTS

In lung, vitamins A-C-E reached a plateau with 1% MVP. In liver, vitamin A and E increased according to their concentration in solutions. Light exposure and added-H2O2 were associated with lower vitamin E in lung and liver. Retinol was higher in lung and lower in liver of animals receiving light-protected compared to light-exposed solutions.

CONCLUSIONS

Light protection of 1% MVP is a better way to improve the pulmonary oxidant-antioxidant balance than to increase MVP (>1%) in parenteral nutrition.

Antenatal vitamin A decreases ventilation-induced lung injury in the lamb model of congenital diaphragmatic hernia

OBJECTIVE

Infants with congenital diaphragmatic hernia (CDH) are susceptible to ventilation-induced lung injury. Vitamin A may protect the lung from injury during ventilation. The authors investigated the effects of antenatal vitamin A on ventilation-induced lung injury in CDH lambs using lung myeloperoxidase (MPO) activity as an indicator of lung injury.

METHODS

Left-sided diaphragmatic defects were created in 10 lambs at 79-81 days' gestation. Six CDH lambs had right jugular venous catheters inserted at 120 days' gestation and were given vitamin A until 135 days' gestation. Four CDH lambs were not treated. Twin littermates (n = 3) served as controls. All lambs were delivered at 136-139 days of gestation and ventilated for 2 hours. Lambs were sacrificed following ventilation and samples of left lung were snap frozen. MPO was extracted from lung tissue and MPO activity was assayed.

RESULTS

CDH lambs treated with antenatal vitamin A demonstrated significantly lower MPO activity than untreated CDH lambs (0.0477 +/- 0.0150 vs. 0.1106 +/- 0.0230 units/mg protein, p < 0.05).

CONCLUSION

This is the first study to look at the effect of vitamin A on lung injury in CDH. In the lamb model of CDH, antenatal vitamin A decreases ventilation-induced lung injury.

Retinoic acid delineates the topography of neuronal plasticity in postnatal cerebral cortex

Retinoic acid is well recognized to promote neuronal differentiation in the embryonic nervous system, but how it influences the postnatal cerebral cortex remains largely unknown. The domain of highest retinoic acid actions in the cortex of the mouse constricts postnatally to a narrow band that includes the dorsal visual stream and the attentional and executive networks. This band of cortex, which is distinguished by the retinoic acid-synthesizing enzyme RALDH3, exhibits signs of delayed maturation and enhanced plasticity compared to the surrounding cortex, as indicated by suppression of parvalbumin, neurofilament, cytochrome oxidase and perineuronal net maturation, and persistence of the embryonic, polysialated form of the neural cell-adhesion molecule PSA-NCAM. During the first postnatal week, the RALDH3-expressing territory translocates in the caudal cortex from the medial limbic lobe to the adjacent neocortex. This topographical shift requires the neurotrophin NT-3 because in mice lacking neuronal NT-3 the RALDH3 enzyme maintains its early postnatal pattern up to adulthood. In the NT-3-null mutants, expression of the markers, whose topography colocalizes with RALDH3 in the normal cortex, matches the abnormal RALDH3 pattern. This indicates that the uneven retinoic acid distribution serves a role in patterning the maturation and to some extent function of the normal postnatal cerebral cortex.

Fat-soluble vitamins in breast-fed preterm and term infants

OBJECTIVE

To examine the supply and status of fat-soluble vitamins in very low birth weight (VLBW) infants compared to a reference group of normal birth weight (NBW) infants.

DESIGN

A longitudinal study of VLBW infants in the early neonatal period. Blood samples were drawn at 1 week of age and at discharge from hospital. Plasma was analyzed for the fat-soluble vitamins: retinol, 25-OH-vitamin D, alpha-tocopherol and phylloquinone (vitamin K(1)) using high-performance liquid chromatography.

SUBJECTS

A total of 40 VLBW infants were included in the study. A reference group of 33 NBW infants was randomly selected from one of our previous studies.

RESULTS

The VLBW infants received fortified human milk, and daily oral vitamin supplement (Multibionta). In VLBW infants, plasma retinol concentrations decreased and plasma 25-OH-vitamin D increased during the study period. VLBW infants had significantly lower plasma retinol (0.3 vs 0.7 mu M) and higher plasma 25-OH-vitamin D (166 vs 25 nM) at discharge compared to NBW infants. Plasma phylloquinone concentration in VLBW infants was very high (53 ng/ml) at one week of age, especially in the youngest infants (192 ng/ml), but decreased rapidly during the study period resulting in low/normal plasma concentrations (0.9 ng/ml) at discharge.

CONCLUSIONS

We observed alterations in plasma concentration of retinol and 25-OH-vitamin D in VLBW infants in the early neonatal period, resulting in marked differences between VLBW at discharge and NBW. Further trials are needed to evaluate whether changes in vitamin supplementation may improve clinical outcome in VLBW infants.

Papel da vitamina A na prevenção do estresse oxidativo em recém-nascidos

A vitamina A é um micronutriente essencial ao ser humano, sobretudo nos momentos de intenso crescimento e desenvolvimento, como a gestação e a infância. Além da atuação dessa vitamina em diversos processos metabólicos, atualmente têm-se destacado o efeito antioxidante desempenhado principalmente pelas formas pró-vitamínicas (carotenóides). Essa função antioxidante da vitamina A é de grande importância no nascimento, período no qual o recém-nascido produz grande quantidade de radicais livres em resposta à exposição a elevadas concentrações de oxigênio. Devido às baixas reservas dessa vitamina, cuja transferência trans-placentária ocorre principalmente no terceiro trimestre de gestação e devido à imaturidade dos demais sistemas antioxidantes, os recém-nascidos prematuros são os mais vulneráveis aos efeitos do estresse decorrente do nascimento. No entanto, ainda existem controvérsias quanto aos benefícios da suplementação da vitamina A no período gestacional, com o objetivo de prevenir a deficiência de vitamina A e suas conseqüências. O presente trabalho tem por objetivo reunir artigos referentes ao tema e publicados em periódicos indexados nas bases de dados MEDLINE e LILACS, no período de 1990 e 2003.

Vitamin A and preterm infants: what we know, what we don't know, and what we need to know

Vitamin A is essential for optimal growth and development. In the developing world, vitamin A supplementation of the newborn infant reduces mortality. In the developed world, extremely preterm infants are born with low body stores of vitamin A and are at high risk of vitamin A deficiency. Optimal vitamin A supplementation for this population is not clearly defined, however, and, despite evidence of benefit, early vitamin A supplementation of extremely preterm infants is not uniformly practised in the United Kingdom. There is an urgent need for studies in preterm infants that include quantification of hepatic stores and functional assessment of vitamin A status as well as long term outcome.

Management of infants with bronchopulmonary dysplasia in North America

The in-hospital management of infants with BPD includes minimizing the duration of mechanical ventilation and avoiding the use of high inspired oxygen concentrations while maintaining adequate oxygenation. Fluid restriction, bronchodilators, and diuretic therapy can improve lung function and reduce the need for supplemental oxygen and high ventilator settings, but do not change the ultimate course of these infants. Corticosteroids also improve lung function and accelerate weaning from oxygen and mechanical ventilation, but their use during the first weeks of life is associated with worse neurological outcome. Adequate nutrition plays an important role in lung injury protection and recovery. Infants with severe BPD frequently develop pulmonary hypertension and may benefit from the use of pulmonary vasodilators. Outpatient management must be carefully planned and carried out by experienced multidisciplinary teams. Social and financial issues must be addressed with the family and caregivers. Home oxygen and mechanical ventilation therapy are used frequently after discharge and require specialized staff and equipment. Maintenance of oxygenation and proper nutritional support are critical aspects in the post-discharge management of these infants. Immunizations and RSV prevention are also important to prevent infections in these vulnerable immunocompromised patients.

Low plasma retinol concentrations increase the risk of developing bronchopulmonary dysplasia and long-term respiratory disability in very-low-birth-weight infants

BACKGROUND

The effect of inadequate vitamin A during the neonatal period on lung status is still unknown.

OBJECTIVE

We tested the hypothesis that low plasma retinol concentrations during the first month of life are independently associated with bronchopulmonary dysplasia (BPD) and long-term respiratory morbidity at 6 mo gestationally corrected age (ie, the age the infant would be had the pregnancy gone to term).

DESIGN

Respiratory outcome information was obtained to 6 mo corrected age for a historical cohort of very-low-birth-weight neonates (<1250 g) who were admitted to intensive care over a 7-y period. Neonates with one or more plasma measurements of retinol concentrations < 0.35 micromol/L (<100 microg/L) on days 1-28 were classified as having low vitamin A. BPD was defined at day 28 by clinical and radiologic criteria and by use of supplemental oxygen at 36 wk postmenstrual age (PMA). Dependence on supplemental oxygen was used to identify long-term respiratory disability at 6 mo corrected age. Multivariate logistic regression analyses were conducted.

RESULTS

Of the 350 study infants, 192 (55%) had low vitamin A status. BPD occurred in 52% of survivors at day 28 (173/331) and at 36 wk PMA (147/285). Fourteen percent (33/244) required oxygen support at 6 mo corrected age. Adjusted odds ratios of BPD with low vitamin A were 3.5 (95% CI: 1.7, 7.2) at day 28 and 1.7 (1.0, 2.7) at 36 wk PMA. At 6 mo corrected age, the adjusted odds ratio was 2.6 (1.1, 6.4) for respiratory disability with low vitamin A.

CONCLUSION

Poor vitamin A status during the first month of life significantly increased the risk of developing BPD and long-term respiratory disability.

Current perspectives on the prevention and management of chronic lung disease in preterm infants

Chronic lung disease (CLD) or bronchopulmonary dysplasia is a recognized sequel of preterm birth. With improving survival of infants at lower gestational ages, the incidence is on the rise. Pathological features of CLD include alveolar maldevelopment, with or without areas of pulmonary fibrosis. Assisted ventilation, infection/inflammation, oxygen administration, and fluid overload are the major risk factors in the evolution of CLD.Interventions, including the treatment of maternal infection, administration of prenatal glucocorticoids, and postnatal surfactant replacement therapy, improve the survival of preterm infants; however, their effect on CLD is difficult to determine. Strategies that have been effective in reducing CLD are the administration of retinol (vitamin A), high frequency oscillatory ventilation, and administration of glucocorticoids. Previous concerns regarding neurological problems associated with high frequency ventilation have not been substantiated in recent studies. Current recommendations do not advise the routine use of glucocorticoids due to concerns regarding long-term neurodevelopment. Therapies that were found to be ineffective in reducing the incidence of CLD include prenatal thyrotropin, cromolyn sodium (sodium cromoglycate), alpha-1 antitrypsin, superoxide dismutase, tocopherol (vitamin E), ascorbic acid (vitamin C), allopurinol, ambroxol, inositol, inhaled bronchodilators, and fluid restriction. Strategies that may be effective in reducing lung injury and subsequent CLD include avoiding assisted ventilation, lung protective ventilatory maneuvers, permissive hypercapnia, prevention of infection, early aggressive nutrition, and the treatment of a patent ductus arteriosus. The use of inhaled glucocorticoids improves pulmonary dynamics but long-term effects are unknown. The management of infants with established CLD has not been studied adequately, and the role of various ventilatory strategies for infants with established CLD is not clear. Adequate oxygenation should be maintained to prevent hypoxic episodes. Diuretics are helpful during acute decompensation; however, their long-term impact has not been well studied. Provision of adequate nutrition, immunization (routine and against respiratory syncytial virus), follow-up, and monitoring are the key elements in the long-term management of infants with CLD. Future research priorities should be to identify strategies to prevent/treat inflammation and promote the healing processes in the injured lung. The long-term effects of lung-protective ventilation strategies need to be studied.

A trial of vitamin A therapy to facilitate ductal closure in premature infants

OBJECTIVE

To determine whether postnatal vitamin A therapy increased ductal closure rate in premature infants.

STUDY DESIGN

This was a prospective, double-blind, placebo-controlled trial. Subjects (n=40) were recruited on day of life 1. Inclusion criteria were premature neonates weighing 500 to 1500 g with an indwelling umbilical line. Vitamin A was administered intramuscularly on days 1, 3, and 7. Blood vitamin A and retinol binding protein levels were obtained on days 1 and 3. Echocardiography was performed on days 1, 3, 7, and 14. Failure of ductal closure was defined as the presence of a moderate to large patent ductus arteriosus on day 14, indomethacin therapy, or surgical ligation.

RESULTS

Comparison between the treatment and placebo groups revealed no differences in gestational age, weight, or oxygenation index. Vitamin A and retinol binding protein levels did not differ between the groups at entry but increased significantly after vitamin A treatment. Failure of ductal closure occurred in 22 of 40 babies without any difference between the groups (12/22 vs 10/18, P=NS). Four infants required surgical ligation, all in the treatment group (P=.04). Clinical outcome did not vary between groups.

CONCLUSION

Postnatal vitamin A therapy did not improve ductal closure rates in premature infants.

Vitamin A and infancy. Biochemical, functional, and clinical aspects

Vitamin A is a very intriguing natural compound. The molecule not only has a complex array of physiological functions, but also represents the precursor of promising and powerful new pharmacological agents. Although several aspects of human retinol metabolism, including absorption and tissue delivery, have been clarified, the type and amounts of vitamin A derivatives that are intracellularly produced remain quite elusive. In addition, their precise function and targets still need to be identified. Retinoic acids, undoubtedly, play a major role in explaining activities of retinol, but, recently, a large number of physiological functions have been attributed to different retinoids and to vitamin A itself. One of the primary roles this vitamin plays is in embryogenesis. Almost all steps in organogenesis are controlled by retinoic acids, thus suggesting that retinol is necessary for proper development of embryonic tissues. These considerations point to the dramatic importance of a sufficient intake of vitamin A and explain the consequences if intake of retinol is deficient. However, hypervitaminosis A also has a number of remarkable negative consequences, which, in same cases, could be fatal. Thus, the use of large doses of retinol in the treatment of some human diseases and the use of megavitamin therapy for certain chronic disorders as well as the growing tendency toward vitamin faddism should alert physicians to the possibility of vitamin overdose.

A comparison of three vitamin A dosing regimens in extremely-low-birth-weight infants

OBJECTIVE

Vitamin A supplementation reduces bronchopulmonary dysplasia (BPD)/death in extremely low birth weight neonates. It was hypothesized that compared with the standard regimen of 5000 IU 3 times per week for 4 weeks, (1) a higher dose (10,000 IU 3 x per week) would increase serum retinol and retinol binding protein (RBP) and lower relative dose responses (RDR), and (2) once-per-week dosing (15,000 IU once per week) would lead to equivalent levels, RBP, and RDR.

STUDY DESIGN

Extremely low birth weight neonates (n = 120) receiving O(2)/mechanical ventilation at 24 hours were randomly assigned to (1) standard, (2) higher dose, or (3) once-per-week regimens. Measures of vitamin A deficiency were serum retinol <20 microg/dL, RBP <2.5 mg/dL, and/or RDR >10% on day 28. BPD was defined as O(2)/mechanical ventilation at 36 weeks' postmenstrual age.

RESULTS

Groups were similar at enrollment (median gestational age, 25 weeks; birth weight, 689 g). Possible toxicity was seen in <5%. The higher dose regimen did not increase retinol or RBP, decrease RDR, or improve outcomes. Infants in the once-per-week regimen had lower retinol levels and higher RDR without an effect on outcomes.

CONCLUSIONS

Compared with the standard regimen, once-per-week dosing worsened, and higher doses did not reduce, vitamin A deficiency. Therefore, the standard regimen is recommended.

Retinoic acid attenuates O2-induced inhibition of lung septation

Exposure of the newborn lung to hyperoxia is associated with impaired alveolar development. In newborn rats exposed to hyperoxia and studied at day 14 of life, retinoic acid (RA) treatment improved survival and increased lung collagen but did not improve alveolar development. To determine whether RA treatment during exposure to hyperoxia results in late improvement in alveolarization, we treated newborn rats with RA and hyperoxia from day 3 to day 14 and then weaned O2 to room air by day 20, and studied the animals on day 42. O2-exposed animals had larger mean lung volumes, larger alveoli, and decreased gas-exchange tissue relative to air-exposed animals, whereas RA-treated O2-exposed animals were not statistically different from air-exposed controls. Relative to control animals, elastin staining at day 14 was decreased in hyperoxia-exposed lung independent of RA treatment, and, at day 42, elastin staining was similar in all treatment groups. At day 14, elastin gene expression was similar in all treatment groups, whereas at day 42 lung previously exposed to hyperoxia showed increased elastin signal independent of RA treatment. These results indicate that RA treatment during hyperoxia exposure promotes septal formation without evidence of effects on elastin gene expression after 4 wk of recovery.

Lecithin:retinol acyltransferase expression is regulated by dietary vitamin A and exogenous retinoic acid in the lung of adult rats

Lecithin:retinol acyltransferase (LRAT), a retinol esterifying enzyme, plays a major role in the metabolism and storage of vitamin A in several animal tissues. Groups of vitamin A (VA)-adequate (control) and VA-deficient rats were treated with vehicle or 5 mg of all-trans-retinoic acid (RA); an additional group of VA-deficient rats were fed 100 microg of RA. In control rats, lung LRAT mRNA and LRAT specific activity were approximately 50% of the levels expressed in the liver. In the lung of VA-deficient rats, LRAT mRNA and specific activity levels were <10% of those in the control group. Treatment of VA-deficient rats with 100 microg RA increased lung LRAT mRNA (P < 0.005) and specific activity (P < 0.0001), and treatment with 5 mg of RA increased LRAT mRNA level and specific activity more than approximately 15- and 6-fold above those in control lung, respectively (both P < or = 0.001). The lung tissue of VA-adequate rats contained retinyl ester (approximately 3 nmol/g tissue), whereas none was detected in the lung tissue of VA-deficient rats. These results show that LRAT expression and vitamin A storage are regulated by vitamin A status and by treatment with all-trans-RA in the adult lung. These results suggest that the regulated storage of vitamin A may be important for maintaining the integrity and physiologic functions of the lung.

Safety and efficacy of nitric oxide in chronic lung disease

BACKGROUND

Therapies for neonatal chronic lung disease (CLD) of prematurity have had limited success.

AIMS

To determine whether inhaled nitric oxide (INO) administered to very low birthweight infants with developing CLD might improve oxygenation without adverse effects.

METHODS

Subjects were 10-30 days of age, birth weight < 1250 g, with developing or established CLD, and requiring mechanical ventilation with mean airway pressure > or = 7 cm H2O and FIO2 . or = 0.40. We monitored changes in oxygenation and FIO2 requirement during treatment with INO (initial dose 20 ppm). Tracheal aspirate samples obtained before, during, and after treatment were analysed for interleukin 1beta (IL-1beta), IL-8, 8-epi-prostaglandin F2alpha (8-epi-PGF2alpha), laminin, and endothelin 1 (ET-1) to assess any potential effects of INO on markers of inflammation peroxidation, basement membrane injury, or vasoactivity.

RESULTS

Thirty three patients met entry criteria. Mean gestational age was 25 (SD 2) weeks; birth weight was 736 (190 g); age of study infants was 19 (6) days (range 9-29). Mean FIO2 decreased from baseline (0.75) to 0.58 at 72 hours. Duration of therapy was seven days. Tracheal aspirate concentrations of IL-1beta, IL-8, 8-epi-PGF2alpha, ET-1, and laminin were unchanged between baseline and 48 hours of INO, and 48 hours after discontinuation of INO. No new cases of, nor extension of, intraventricular haemorrhage occurred. Four infants died.

CONCLUSION

INO (< or = 20 ppm) improved oxygenation in most infants with early CLD, without inducing changes in markers of inflammatory or oxidative injury.

Updates in pediatric nutrition

Ongoing research in several areas of pediatric nutrition has new practical applications for community-based pediatricians. For example, a fresh understanding of risk factors for rickets persuades pediatricians to recognize and treat this disease, which was thought to be nearly extinct in the modern industrialized world. Similarly, an expanded awareness of the antibacterial components of breast milk encourages a more complete dialogue between pediatricians and new mothers about the potential benefits of breast-feeding. For those infants with feeding intolerance, new data help to refine the indications for hypoallergenic formulas, which are increasingly recommended for children with a variety of symptoms. The past year also has seen breakthroughs in our understanding of supplemental nutrition for children. Vitamin A may provide direct benefits for the most vulnerable of children, namely premature infants at high risk for lung disease. At the other end of the pediatric spectrum, adolescent athletes seeking to enhance their performance are consuming poorly studied sports supplements that may not be beneficial and may even be toxic. Finally, a greater appreciation for the epidemic of obesity that is sweeping the United States and other countries suggests that children at high risk may represent a far more diverse population than had been recognized previously.

Special nutritional needs of infants for prevention of and recovery from bronchopulmonary dysplasia

Extremely low birth weight infants who develop severe respiratory disease may have special nutrient requirements imposed by a combination of enhanced utilization of nutrients or the need for epithelial cell repair resulting from the disease process, as well as to support catch-up growth. Inositol, free fatty acids, vitamin E and vitamin A are proposed as nutrients for which infants at risk of chronic pulmonary insufficiency may have special requirements. Of these nutrients, only for vitamin A does suggestive evidence exist that high doses when given intramuscularly may reduce the incidence of death or chronic lung disease. Exogenous steroid therapy (dexamethasone), which is often used to improve pulmonary compliance in ventilated premature infants, may compromise vitamin A status and induce restricted somatic and bone mineral growth. Supplemental nutrition by means of enriched infant formulas has provided benefits in growth and bone mass accretion to infants recovering from bronchopulmonary dysplasia up to 3-mo corrected age. This growth advantage was not sustained over the subsequent 9 mo, suggesting that prolonged nutritional support is required until catch-up growth is complete. Further studies are required to delineate the needs for specific nutrients such as antioxidant vitamins and minerals or vitamin A that may play a role in preventing severe chronic lung disease in premature infants. As well, the role of supplemental nutrition (beyond the requirements of term infants) to support catch-up growth and maintenance during the critical stages of early development requires further investigation before evidence-based nutrient recommendations can be developed for this special population of infants.

Randomised controlled trial of oral vitamin A supplementation in preterm infants to prevent chronic lung disease

BACKGROUND

Intramuscular supplementation with vitamin A in large doses may reduce the incidence of chronic lung disease.

AIM

To investigate whether oral supplementation with vitamin A would reduce the incidence of chronic lung disease in a group of extremely low birthweight infants.

METHODS

Infants with birth weight < 1000 g were randomised at birth to receive oral vitamin A supplementation (5000 IU/day) or placebo for 28 days. The primary outcome was oxygen dependency at 28 days of age or death.

RESULTS

A total of 154 infants were randomised; 77 received vitamin A (median birth weight (interquartile range) 806 (710-890) g), and 77 received placebo (median birth weight (interquartile range) 782 (662-880) g). Plasma vitamin A concentrations in the supplemented group were significantly higher at 24 hours of age but did not differ significantly at birth, 12 hours of age, 7 days, or 28 days of life. There were no significant differences in the proportion of infants who survived, required oxygen at 28 days, required oxygen at 36 weeks postmenstrual age, survived without chronic lung disease at 36 weeks, survived without significant retinopathy, or who survived without significant intraventricular haemorrhage.

CONCLUSIONS

Oral supplementation with 5000 IU vitamin A in extremely low birthweight infants does not significantly alter the incidence of chronic lung disease. However, this dose may have been inadequate to achieve optimal serum retinol concentrations.

Strategies for prevention of neonatal chronic lung disease

Chronic lung disease (CLD) of prematurity remains a substantial problem despite modern perinatal and neonatal care. CLD remains related to gestational age and lung immaturity, although it has become clear that severe initial lung disease is not a prerequisite for CLD to develop. Attempts to prevent CLD to date have not adequately addressed the multifactorial nature of the complex pathophysiology that leads to CLD. Thus, results have been modest at best. Prevention of CLD will require a multifaceted approach with specific interventions and care practices focused on different aspects of the pathway that leads to CLD. This review considers new information related to causation of CLD and the magnitude of the effect of prevention strategies tested to date. This article also advances the hypothesis that CLD is preventable with a global strategy of minimizing inciting events, optimizing management, and specific therapies aimed at intrinsic vulnerabilities.

Vitamin A and E supplementation in breast-fed newborns

BACKGROUND

Vitamins A and E are two potent antioxidant nutrients that play a significant role in immune function. In contrast to the numerous studies of vitamin A and E status in children, adolescents, and adults, information on term infants, particularly breast-fed infants, is scarce. The goals of the present investigation were to examine the vitamins A and E nutritional status of term breast-fed infants at birth and to assess retinol and tocopherol plasma levels during a 3-month supplementation trial.

METHODS

The study was a prospective, blinded comparison of a supplementation protocol with a placebo in a group of consecutively recruited term newborns. The supplemented group received 3000 IU vitamin A and 5 IU vitamin E orally. The placebo group received a solution of similar viscosity and organoleptic characteristics. Vitamin A and E were separated by reverse-phase high-performance liquid chromatography on a C18 Spectrasyl column and quantified by ultraviolet spectrophotometry.

RESULTS

Vitamin A and E levels steadily increased with age in both groups of infants. However, levels at 3 months were higher in the supplemented than in the control group.

CONCLUSION

The data show that supplementation with 3000 IU vitamin A and 5 IU vitamin E for 3 months increases circulating vitamin levels in newborn term babies compared with those in nonsupplemented infants.