Cysteine, cystine or N-acetylcysteine supplementation in parenterally fed neonates

Preparation and Kokumi Properties of N-Acetyl-Val/Leu/Ile/Met/Phe in the Presence of Acetic Acid and Amino Acid: A Commercially Available Transglutaminase and Protease A 2SD

Kokumi is a beneficial feeling for the evaluation of food quality, and thus, preparing and understanding the taste properties of kokumi compounds are important for the flavor of food. N-acetyl-Val/Leu/Ile/Met/Phe/Trp/Tyr is a type of kokumi compound found in food and usually prepared by chemical reagents. In this study, we first prepared these six kokumi compounds using transglutaminase and protease A2SD in aqueous solution by using amino acids and acetic acid as substrates and evaluated their kokumi characteristics. HPLC and LC-MS were used to identify quantitative N-acetyl amino acids. Using Phe and acetic acid as substrates, transglutaminase and protease A2SD showed the highest yields for N-acetyl-Phe of 22.75 and 42.21%, respectively, under the optimal conditions. For N-acetyl-Val/Leu/Ile/Met/Trp/Tyr, these two enzymes showed the synthesis yield in the ranges of 2.22-20.12 and 0.75-12.91%, respectively. Six N-acetyl-amino acids were succesully enriched by ethyl acetate with a recovery over 50% and purity over 95%. Sensory evaluation found that N-acetyl-Val/Leu/Ile/Met/Phe are kokumi compounds that enhance sweet, umami, and salt tastes in 5% sucrose, 0.3% NaCl, and 0.5% sodium glutamate, especially N-acetyl-Val, with the salt- and umami-enhancing threshold values of 0.63 and 1.25 g/L, respectively. Therefore, transglutaminase and protease A2SD for the synthesis of partial N-acetyl amino acid might have the potential to be applied in food as a kokumi compound.

Oxygen and mechanical stretch in the developing lung: risk factors for neonatal and pediatric lung disease

Chronic airway diseases, such as wheezing and asthma, remain significant sources of morbidity and mortality in the pediatric population. This is especially true for preterm infants who are impacted both by immature pulmonary development as well as disproportionate exposure to perinatal insults that may increase the risk of developing airway disease. Chronic pediatric airway disease is characterized by alterations in airway structure (remodeling) and function (increased airway hyperresponsiveness), similar to adult asthma. One of the most common perinatal risk factors for development of airway disease is respiratory support in the form of supplemental oxygen, mechanical ventilation, and/or CPAP. While clinical practice currently seeks to minimize oxygen exposure to decrease the risk of bronchopulmonary dysplasia (BPD), there is mounting evidence that lower levels of oxygen may carry risk for development of chronic airway, rather than alveolar disease. In addition, stretch exposure due to mechanical ventilation or CPAP may also play a role in development of chronic airway disease. Here, we summarize the current knowledge of the impact of perinatal oxygen and mechanical respiratory support on the development of chronic pediatric lung disease, with particular focus on pediatric airway disease. We further highlight mechanisms that could be explored as potential targets for novel therapies in the pediatric population.

Calcium and Phosphate Solubility Curve Equation for Determining Precipitation Limits in Compounding Parenteral Nutrition

Clinicians have published research and reports on calcium and phosphate solubility within parenteral nutrition (PN) for over 40 years. Foundational empirical laboratory investigation in the 1980s motivated by the prevalence of neonatal rickets and osteomalacia in the Neonatal Intensive Care Unit (NICU) population led to precipitation curves that have guided PN prescribing and compounding. Over subsequent decades, numerous publications have expanded the knowledge of factors influencing calcium and phosphate solubility in formulating optimal and safe PN admixtures. Failure to adhere to known principles has led to serious injury and death. Known solubility curves are derived from empiric analysis of a finite number of conditions and concentrations, whereas custom PN orders vary widely and rarely match the admixture composition in the data set used to derive the published precipitation curves. Various commercial platforms have been developed to aid the pharmacist in assessing the potential for precipitation when evaluating a PN order. Some applications plot the calcium and phosphate concentrations of the prescribed PN against known published graphs most similar to the order, allowing the pharmacist to judge the risk of precipitation. Other approaches use intellectually protected trade secret algorithms to determine calcium and phosphate solubility across a continuum of conditions. This publication reports equations that have been used successfully for over 2 decades in our regional network of NICUs and shared with others to determine safe prescribing limits for calcium and phosphate concentrations using an electronic PN prescribing program.

Interventions to Prevent Bronchopulmonary Dysplasia in Preterm Neonates: An Umbrella Review of Systematic Reviews and Meta-analyses

IMPORTANCE

Bronchopulmonary dysplasia (BPD) has multifactorial etiology and long-term adverse consequences. An umbrella review enables the evaluation of multiple proposed interventions for the prevention of BPD.

OBJECTIVE

To summarize and assess the certainty of evidence of interventions proposed to decrease the risk of BPD from published systematic reviews.

DATA SOURCES

MEDLINE, Cochrane Central Register of Controlled Trials, EMBASE, and Web of Science were searched from inception until November 9, 2020.

STUDY SELECTION

Meta-analyses of randomized clinical trials comparing interventions in preterm neonates that included BPD as an outcome.

DATA EXTRACTION AND SYNTHESIS

Data extraction was performed in duplicate. Quality of systematic reviews was evaluated using Assessment of Multiple Systematic Reviews version 2, and certainty of evidence was assessed using Grading of Recommendation, Assessment, Development, and Evaluation.

MAIN OUTCOMES AND MEASURES

(1) BPD or mortality at 36 weeks' postmenstrual age (PMA) and (2) BPD at 36 weeks' PMA.

RESULTS

A total of 154 systematic reviews evaluating 251 comparisons were included, of which 110 (71.4%) were high-quality systematic reviews. High certainty of evidence from high-quality systematic reviews indicated that delivery room continuous positive airway pressure compared with intubation with or without routine surfactant (relative risk [RR], 0.80 [95% CI, 0.68-0.94]), early selective surfactant compared with delayed selective surfactant (RR, 0.83 [95% CI, 0.75-0.91]), early inhaled corticosteroids (RR, 0.86 [95% CI, 0.75-0.99]), early systemic hydrocortisone (RR, 0.90 [95% CI, 0.82-0.99]), avoiding endotracheal tube placement with delivery room continuous positive airway pressure and use of less invasive surfactant administration (RR, 0.90 [95% CI, 0.82-0.99]), and volume-targeted compared with pressure-limited ventilation (RR, 0.73 [95% CI, 0.59-0.89]) were associated with decreased risk of BPD or mortality at 36 weeks' PMA. Moderate to high certainty of evidence showed that inhaled nitric oxide, lower saturation targets (85%-89%), and vitamin A supplementation are associated with decreased risk of BPD at 36 weeks' PMA but not the competing outcome of BPD or mortality, indicating they may be associated with increased mortality.

CONCLUSIONS AND RELEVANCE

A multipronged approach of delivery room continuous positive airway pressure, early selective surfactant administration with less invasive surfactant administration, early hydrocortisone prophylaxis in high-risk neonates, inhaled corticosteroids, and volume-targeted ventilation for preterm neonates requiring invasive ventilation may decrease the combined risk of BPD or mortality at 36 weeks' PMA.

Thioredoxin-1 Ameliorates Oxygen-Induced Retinopathy in Newborn Mice Through Modulation of Proinflammatory and Angiogenic Factors

Oxygen-induced retinopathy (OIR) is an animal model for retinopathy of prematurity, which is a leading cause of blindness in children. Thioredoxin-1 (TRX) is a small redox protein that has cytoprotective and anti-inflammatory properties in response to oxidative stress. The purpose of this study was to determine the effect of TRX on OIR in newborn mice. From postnatal day 7, C57BL/6 wild type (WT) and TRX transgenic (TRX-Tg) mice were exposed to either 21% or 75% oxygen for 5 days. Avascular and neovascular regions of the retinas were investigated using fluorescence immunostaining. Fluorescein isothiocyanate-dextran and Hoechst staining were used to measure retinal vascular leakage. mRNA expression levels of proinflammatory and angiogenic factors were analyzed using quantitative polymerase chain reaction. Retinal histological changes were detected using immunohistochemistry. In room air, the WT mice developed well-organized retinas. In contrast, exposing WT newborn mice to hyperoxia hampered retinal development, increasing the retinal avascular and neovascular areas. After hyperoxia exposure, TRX-Tg mice had enhanced retinal avascularization compared with WT mice. TRX-Tg mice had lower retinal neovascularization and retinal permeability during recovery from hyperoxia compared with WT mice. In the early stages after hyperoxia exposure, VEGF-A and CXCL-2 expression levels decreased, while IL-6 expression levels increased in WT newborn mice. Conversely, no differences in gene expressions were observed in the TRX-Tg mouse retina. IGF-1 and Angpt1 levels did not decrease during recovery from hyperoxia in TRX-Tg newborn mice. As a result, overexpression of TRX improves OIR in newborn mice by modulating proinflammatory and angiogenic factors.

Current and emerging adjuvant therapies in biliary atresia

Following Kasai hepatic portoenterostomy (HPE), most patients with biliary atresia will eventually require liver transplantation due to progressive cirrhosis and liver failure. Preventing liver transplantation, or even delaying eventual liver transplantation, is the key to improving long-term outcomes. This review first examines the commonly used adjuvant therapies in post-HPE biliary atresia and the strength of the evidence supporting these therapies. Next, it examines the evolving frontiers of management through a comprehensive evaluation of both recently completed and ongoing clinical trials in biliary atresia. Promising therapies used in other cholestatic liver diseases with potential benefit in biliary atresia are discussed. Improving post-HPE management is critical to prevent complications, delay liver transplantation, and ultimately improve the long-term survival of patients with biliary atresia.

Free Radicals and Neonatal Brain Injury: From Underlying Pathophysiology to Antioxidant Treatment Perspectives

Free radicals play a role of paramount importance in the development of neonatal brain injury. Depending on the pathophysiological mechanisms underlying free radical overproduction and upon specific neonatal characteristics, such as the GA-dependent maturation of antioxidant defenses and of cerebrovascular autoregulation, different profiles of injury have been identified. The growing evidence on the detrimental effects of free radicals on the brain tissue has led to discover not only potential biomarkers for oxidative damage, but also possible neuroprotective therapeutic approaches targeting oxidative stress. While a more extensive validation of free radical biomarkers is required before considering their use in routine neonatal practice, two important treatments endowed with antioxidant properties, such as therapeutic hypothermia and magnesium sulfate, have become part of the standard of care to reduce the risk of neonatal brain injury, and other promising therapeutic strategies are being tested in clinical trials. The implementation of currently available evidence is crucial to optimize neonatal neuroprotection and to develop individualized diagnostic and therapeutic approaches addressing oxidative brain injury, with the final aim of improving the neurological outcome of this population.

Severe Presentation of Congenital Hemolytic Anemias in the Neonatal Age: Diagnostic and Therapeutic Issues

Congenital hemolytic anemias (CHAs) are a group of diseases characterized by premature destruction of erythrocytes as a consequence of intrinsic red blood cells abnormalities. Suggestive features of CHAs are anemia and hemolysis, with high reticulocyte count, unconjugated hyperbilirubinemia, increased lactate dehydrogenase (LDH), and reduced haptoglobin. The peripheral blood smear can help the differential diagnosis. In this review, we discuss the clinical management of severe CHAs presenting early on in the neonatal period. Appropriate knowledge and a high index of suspicion are crucial for a timely differential diagnosis and management. Here, we provide an overview of the most common conditions, such as glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency, and hereditary spherocytosis. Although rare, congenital dyserythropoietic anemias are included as they may be suspected in early life, while hemoglobinopathies will not be discussed, as they usually manifest at a later age, when fetal hemoglobin (HbF) is replaced by the adult form (HbA).

Parenteral Nutrition and Oxidant Load in Neonates

Neonates with preterm, gastrointestinal dysfunction and very low birth weights are often intolerant to oral feeding. In such infants, the provision of nutrients via parenteral nutrition (PN) becomes necessary for short-term survival, as well as long-term health. However, the elemental nutrients in PN can be a major source of oxidants due to interactions between nutrients, imbalances of anti- and pro-oxidants, and environmental conditions. Moreover, neonates fed PN are at greater risk of oxidative stress, not only from dietary sources, but also because of immature antioxidant defences. Various interventions can lower the oxidant load in PN, including the supplementation of PN with antioxidant vitamins, glutathione, additional arginine and additional cysteine; reduced levels of pro-oxidant nutrients such as iron; protection from light and oxygen; and proper storage temperature. This narrative review of published data provides insight to oxidant molecules generated in PN, nutrient sources of oxidants, and measures to minimize oxidant levels.

Translational Research in Retinopathy of Prematurity: From Bedside to Bench and Back Again

Retinopathy of prematurity (ROP), a vascular proliferative disease affecting preterm infants, is a leading cause of childhood blindness. Various studies have investigated the pathogenesis of ROP. Clinical experience indicates that oxygen levels are strongly correlated with ROP development, which led to the development of oxygen-induced retinopathy (OIR) as an animal model of ROP. OIR has been used extensively to investigate the molecular mechanisms underlying ROP and to evaluate the efficacy of new drug candidates. Large clinical trials have demonstrated the efficacy of anti-vascular endothelial growth factor (VEGF) agents to treat ROP, and anti-VEGF therapy is presently becoming the first-line treatment worldwide. Anti-VEGF therapy has advantages over conventional treatments, including being minimally invasive with a low risk of refractive error. However, long-term safety concerns and the risk of late recurrence limit this treatment. There is an unmet medical need for novel ROP therapies, which need to be addressed by safe and minimally invasive therapies. The recent progress in biotechnology has contributed greatly to translational research. In this review, we outline how basic ROP research has evolved with clinical experience and the subsequent emergence of new drugs. We discuss previous and ongoing trials and present the candidate molecules expected to become novel targets.

Stability of N-Acetylcysteine (NAC) in Standardized Pediatric Parenteral Nutrition and Evaluation of N,N-Diacetylcystine (DAC) Formation

The ESPGHAN/ESPEN/ESPR-Guidelines on pediatric parenteral nutrition (PPN) recommend the administration of the semiessential amino acid (AA) cysteine to preterm neonates due to their biochemical immaturity resulting in an inability to sufficiently synthetize endogenous cysteine. The soluble precursor N-acetylcysteine (NAC) is easily converted into bioavailable cysteine. Its dimer N,N-diacetylcystine (DAC) is almost unconvertable to cysteine when given intravenously resulting in a diminished bioavailability of cysteine. This study aims to understand the triggers and oxidation process of NAC to DAC to evaluate possibilities of reducing DAC formation in standardized PPN. Therefore, different air volumes (21% O₂) were injected into the AA compartment of a standardized dual-chamber PPN. O₂ concentrations were measured in the AA solution and the headspaces of the primary and secondary packaging. NAC and DAC concentrations were analyzed simultaneously. The analysis showed that O₂ is principally delivered from the primary headspace. NAC oxidation exclusively delivers DAC, depending on the O₂ amount in the solution and the headspaces. The reaction of NAC to DAC being containable by limiting the O₂ concentration, the primary headspace must be minimized during manufacturing, and oxygen absorbers must be added into the secondary packaging for a long-term storage of semipermeable containers.

An Overview of Systematic Reviews of Randomized-Controlled Trials for Preventing Necrotizing Enterocolitis in Preterm Infants

Necrotizing enterocolitis (NEC) remains a major cause for neonatal mortality and morbidity in preterm infants. The purpose of this review was to summarize evidence from systematic reviews of randomized-controlled trials (RCTs) regarding antenatal and postnatal interventions for preventing NEC. PubMed, EMBASE, the Cochrane Library Databases, Database of Abstracts of Reviews of Effects, and Campbell Library were searched for meta-analyses in which NEC was reported as an outcome after antenatal or postnatal strategies. The AMSTAR instrument was used to evaluate quality of included reviews. Grading of Recommendations, Assessment, Development and Evaluation assessment was used to evaluate certainty of evidence. We identified 98 meta-analyses of RCTs. The quality of included reviews was adequate, whereas the certainty of evidence was moderate to very low. Moderate certainty evidence showed a reduction in NEC following administration of a combination of species of probiotics, probiotics (any), antenatal corticosteroids in pregnant women at risk of preterm birth, and ibuprofen versus indomethacin for treatment of patent ductus arteriosus (PDA). For surgical NEC, moderate certainty evidence showed an increased risk with lower (85-89%) oxygen saturation target levels, compared with higher (91-95%) oxygen saturation target levels. In conclusion, decreased risk of NEC is observed with probiotics, antenatal corticosteroids for women at risk of preterm birth, and ibuprofen versus indomethacin for treatment of PDA. Targeting lower oxygen saturations may increase the risk of surgical NEC, compared to targeting higher saturations.

Intermittent hypoxia and bronchial hyperreactivity

The premature neonate is at high risk for childhood airway hyperreactivity and episodes of wheezing. Intermittent hypoxic events are frequently observed during the first weeks and months of life in these infants. Intermittent hypoxemia has been associated with adverse outcomes in extremely premature infants; including the diagnosis of bronchopulmonary dysplasia, reported wheezing, and use of prescription asthma medications. We review the incidence of intermittent hypoxia, their potential role in short and longer term respiratory morbidity, and the translational newborn models now being used to investigate common pathways by which intermittent hypoxia contributes to respiratory disease.

Protein intakes to optimize outcomes for preterm infants

Proteins are key structural components of all human cells and are also involved in key physiologic processes through their roles as enzymes, hormones and transport proteins. Protein requirements are substantially higher in preterm infants than those born at term, yet inadequate protein intakes are a common problem on many neonatal units. Very preterm infants (VPT, <32 weeks) commonly receive parenteral amino acid solutions which are typically commenced on admission, and increased over the next few days. Several recent studies have explored differing parenteral amino acid intakes in the first few days, and recommendations have recently been updated. Parenteral nutrition intakes are decreased as enteral feeds are tolerated, but human milk alone will not meet protein needs in most VPT and supplementation or fortification will be required. This review paper considers basic protein and amino acid physiology in the newborn period, and the evidence base for current recommendations.

Thiol-Redox Regulation in Lung Development and Vascular Remodeling

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

Glutathione Supplementation of Parenteral Nutrition Prevents Oxidative Stress and Sustains Protein Synthesis in Guinea Pig Model

Peroxides contaminating parenteral nutrition (PN) limit the use of methionine as a precursor of cysteine. Thus, PN causes a cysteine deficiency, characterized by low levels of glutathione, the main molecule used in peroxide detoxification, and limited growth in individuals receiving long-term PN compared to the average population. We hypothesize that glutathione supplementation in PN can be used as a pro-cysteine that improves glutathione levels and protein synthesis and reduces oxidative stress caused by PN. One-month-old guinea pigs (7–8 per group) were used to compare glutathione-enriched to a non-enriched PN, animals on enteral nutrition were used as a reference. PN: Dextrose, amino acids (Primene), lipid emulsion (Intralipid), multivitamins, electrolytes; five-day infusion. Glutathione (GSH, GSSG, redox potential) and the incorporation of radioactive leucine into the protein fraction (protein synthesis index) were measured in the blood, lungs, liver, and gastrocnemius muscle. Data were analysed by ANOVA; p < 0.05 was considered significant. The addition of glutathione to PN prevented the PN-induced oxidative stress in the lungs and muscles and supported protein synthesis in liver and muscles. The results potentially support the recommendation to add glutathione to the PN and demonstrate that glutathione could act as a biologically available cysteine precursor.

Oxygen Toxicity in the Neonate: Thinking Beyond the Balance

Fetal development occurs in a relatively hypoxemic environment, and birth represents significant oxidative stress. Premature infants are disadvantaged by a lack of maternal antioxidant transfer and impaired endogenous antioxidant responses. O₂ metabolism is essential for life and its biochemical reactions are dynamic, compartmentalized, and difficult to characterize in vivo. There is a growing appreciation for the role of reactive oxygen species in nonpathologic processes, including regulation of cell signaling and mitochondrial function. There are several gaps in the knowledge about the role of reactive oxygen species in normal development and how oxidative stress alters normal signaling and subsequent development.

A phase 2 trial of N-Acetylcysteine in Biliary atresia after Kasai portoenterostomy

BACKGROUND

Biliary atresia (BA) is a life-threatening liver disease of infancy, characterized by extrahepatic biliary obstruction, bile retention, and progressive liver injury. The Kasai portoenterostomy (KP) is BA's only nontransplant treatment. Its success is variable and depends on restoration of hepatic bile flow. Many adjunctive therapeutics have been studied to improve outcomes after the KP, but none demonstrate effectiveness. This study tests if N-acetylcysteine (NAC), a precursor to the choleretic glutathione, improves bile flow after KP.

METHODS

This report describes the design of an open-label, single center, Phase 2 study to determine the effect of NAC following KP on markers of bile flow and outcomes in BA. The intervention is intravenous NAC (150 mg/kg/day) administered continuously for seven days starting 0-24 h after KP. The primary outcome is normalization of total serum bile acid (TSBA) concentrations within 24 weeks of KP. The secondary objectives are to describe NAC therapy's effect on other clinical parameters followed in BA for 24 months and to report adverse events occurring with therapy. This study follows the "minimax" clinical trial design.

DISCUSSION

This is the first clinical trial to test NAC's effectiveness in improving bile flow after KP in BA. It introduces three important concepts for future BA therapeutic trials: (1) the "minimax" study design, a pertinent design for rare diseases because it detects potential effects quickly with small subject size; (2) the more sensitive bile flow marker, TSBAs, which may correlate with positive long-term outcomes better than traditional bile flow markers such as serum bilirubin; and (3) liver enzyme changes immediately after KP, which can be a guideline for potential drug-induced liver injury in other BA peri-operative adjunctive therapeutic trials.

Turkish Neonatal Society guideline on parenteral nutrition in preterm infants

Postnatal growth failure due to inappropriate and insufficient nutrition is a risk for preterm infants, especially for very-low-birth-weight or extremely-low-birth-weight infants. This extrauterine growth failure causes negative effects on long-term neurodevelopment. Early initiation of intensive parenteral nutrition with appropriate protein and energy supply is a nutritional emergency when enteral feeding cannot be achieved. This approach prevents protein catabolism and helps achievement of positive protein balance and postnatal growth. Protein, lipid, and glucose initiation with appropriate doses that reach timely goals constitute the major elements of parenteral nutrition. The transition to enteral nutrition with the mother's milk at the earliest convenience must be targeted in parenteral nutrition.

Pharmacotherapy and ROP: Going Back to the Basics

Retinopathy of prematurity (ROP) is a leading cause of blindness in preterm infants around the world. Through the development of animal models and clinical trials our understanding of the pathophysiology of this disease and approach to therapy has evolved significantly since ROP was first described in the 1940s in the United States. The mainstay of treatment in ROP remains ablative laser therapy to the avascular retina but pharmacologic agents are being more and more commonly used with new targets for pharmacotherapy emerging. This paper summarizes our current understanding of the pathophysiology of ROP based on the data gleaned from animal models and discusses current approaches to pharmacotherapy.

Sex-Specificity of Oxidative Stress in Newborns Leading to a Personalized Antioxidant Nutritive Strategy

Oxidative stress is a critical process that triggers several diseases observed in premature infants. Growing recognition of the detriment of oxidative stress in newborns warrants the use of an antioxidant strategy that is likely to be nutritional in order to restore redox homeostasis. It appears essential to have a personalized approach that will take into account the age of gestation at birth and the sex of the infant. However, the link between sex and oxidative stress remains unclear. The aim of this study was to find a common denominator explaining the discrepancy between studies related to sex-specific effects of oxidative stress. Results highlight a specificity of sex in the levels of oxidative stress markers linked to the metabolism of glutathione, as measured in the intracellular compartments. Levels of all sex-dependent oxidative stress markers are greater and markers associated to a better antioxidant defense are lower in boys compared to girls during the neonatal period. This sex-specific discrepancy is likely to be related to estrogen metabolism, which is more active in baby-girls and promotes the activation of glutathione metabolism. Conclusion: our observations suggest that nutritive antioxidant strategies need to target glutathione metabolism and, therefore, should be personalized considering, among others, the sex specificity.

Neonatal Parenteral Nutrition Containing Calcium Chloride and Sodium Phosphate

Objective. The authors’ objectives were to determine mineral as well as Al intakes for ≤1000 g birth weight (ELBW) infants supported with parenteral nutrition (PN) solutions containing calcium chloride (CaCl) and sodium phosphate (NaPhos). Study design. This study was a prospective cohort study of 32 ELBW infants. Nutrient and Al intakes were recorded based on actual fluid intakes and concentrations of nutrients and Al in PN solutions. Growth velocities and peak alkaline phosphatase (AP) levels during the hospital stay were recorded. Result. Mean (±standard deviation) weight, length, and head circumference gains and AP were 13.7 ± 1.8 g/kg/d, 1.0 ± 0.2 cm/wk, 0.7 ± 0.1 cm/wk, and 636 ± 227 U/L, respectively. Al intake was 0.27 ± 0.07 µmol/kg/d (7.2 ± 1.8 µg/kg/d) in infants receiving PN with low Al content. This study documented average parenteral Ca and P intakes of 1.15 to 1.20 and 1.19 to 1.29 mmol/kg/d, (46-48 and 37-40 mg/kg/d), respectively, with PN fluid intakes of 90 to 100 mL/kg/d. Conclusion. AP and growth in ELBW infants receiving PN solutions containing CaCl are comparable to those reported in the literature for ELBW infants. Ca and P intakes approaching those reported for preterm infants receiving PN containing calcium gluconate can be provided with PN solutions containing CaCl. Fluid restriction is a significant factor limiting mineral intakes. Al intake can be limited to near FDA recommended intakes in PN solutions containing CaCl.

Advances in understanding and management of retinopathy of prematurity

The understanding, diagnosis, and treatment of retinopathy of prematurity have changed in the 70 years since the original description of retrolental fibroplasia associated with high oxygenation. It is now recognized that retinopathy of prematurity differs in appearance worldwide and as ever smaller and younger premature infants survive. New methods are being evaluated to image the retina, diagnose severe retinopathy of prematurity, and determine windows of time for treatment to save eyes and improve visual and neural outcomes. New treatments to promote physiologic retinal vascular development, vascular repair, and inhibit vasoproliferation by regulating proteins involved in vascular endothelial growth factor, insulin-like growth factor, or erythropoietin signaling. Reducing excessive oxidative/nitrosative stress and understanding progenitor cells and neurovascular and glial vascular interactions are being studied.

Glucose-6-Phosphate Dehydrogenase Deficiency and the Need for a Novel Treatment to Prevent Kernicterus

Hyperbilirubinemia occurs frequently in newborns, and in severe cases can progress to kernicterus and permanent developmental disorders. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, one of the most common human enzymopathies, is a major risk factor for hyperbilirubinemia and greatly increases the risk of kernicterus even in the developed world. Therefore, a novel treatment for kernicterus is needed, especially for G6PD-deficient newborns. Oxidative stress is a hallmark of bilirubin toxicity in the brain. We propose that the activation of G6PD via a small molecule chaperone is a potential strategy to increase endogenous defense against bilirubin-induced oxidative stress and prevent kernicterus.

Working group reports: evaluation of the evidence to support practice guidelines for nutritional care of preterm infants-the Pre-B Project

The "Evaluation of the Evidence to Support Practice Guidelines for the Nutritional Care of Preterm Infants: The Pre-B Project" is the first phase in a process to present the current state of knowledge and to support the development of evidence-informed guidance for the nutritional care of preterm and high-risk newborn infants. The future systematic reviews that will ultimately provide the underpinning for guideline development will be conducted by the Academy of Nutrition and Dietetics' Evidence Analysis Library (EAL). To accomplish the objectives of this first phase, the Pre-B Project organizers established 4 working groups (WGs) to address the following themes: 1) nutrient specifications for preterm infants, 2) clinical and practical issues in enteral feeding of preterm infants, 3) gastrointestinal and surgical issues, and 4) current standards of infant feeding. Each WG was asked to 1) develop a series of topics relevant to their respective themes, 2) identify questions for which there is sufficient evidence to support a systematic review process conducted by the EAL, and 3) develop a research agenda to address priority gaps in our understanding of the role of nutrition in health and development of preterm/neonatal intensive care unit infants. This article is a summary of the reports from the 4 Pre-B WGs.

The Role of Immunonutrients in the Prevention of Necrotizing Enterocolitis in Preterm Very Low Birth Weight Infants

Necrotizing enterocolitis (NEC) is a critical intestinal emergency condition, which mainly occurs in preterm very low birth weight (PVLBW) infants. Despite remarkable advances in the care of PVLBW infants, with considerable improvement of the survival rate in recent decades, the incidence of NEC and NEC-related mortality have not declined accordingly. The fast progression from nonspecific signs to extensive necrosis also makes primary prevention the first priority. Recently, increasing evidence has indicated the important role of several nutrients in primary prevention of NEC. Therefore, the aim of this review is to summarize some potential immunomodulatory nutrients in the prevention of NEC, including bovine colostrum, probiotics, prebiotics (e.g., human milk oligosaccharides), long chain polyunsaturated fatty acids, and amino acids (glutamine, cysteine and N-acetylcysteine, l-arginine and l-citrulline). Based on current research evidence, probiotics are the most documented effective method to prevent NEC, while others still require further investigation in animal studies and clinical randomized controlled trials.

Calcium Chloride in Neonatal Parenteral Nutrition Solutions with and without Added Cysteine: Compatibility Studies Using Laser and Micro-Flow Imaging Methodology

BACKGROUND

Previous studies of compatibility of calcium chloride (CaCl2) and phosphates have not included particle counts in the range specified by the United States Pharmacopeia. Micro-flow imaging techniques have been shown to be comparable to light obscuration when determining particle count and size in pharmaceutical solutions.

OBJECTIVE

The purpose of this study was to do compatibility testing for parenteral nutrition (PN) solutions containing CaCl2 using dynamic light scattering and micro-flow imaging techniques.

METHODS

Solutions containing TrophAmine (Braun Medical Inc, Irvine, CA), CaCl2, and sodium phosphate (NaPhos) were compounded with and without cysteine. All solutions contained standard additives to neonatal PN solutions including dextrose, trace metals, and electrolytes. Control solutions contained no calcium or phosphate. Solutions were analyzed for particle size and particle count. Means of Z-average particle size and particle counts of controls were determined. Study solutions were compared to controls and United States Pharmacopeia (USP) Chapter 788 guidelines. The maximum amount of Phos that was compatible in solutions that contained at least 10 mmol/L of Ca in 2.5% amino acids (AA) was determined. Compatibility of these solutions was verified by performing analyses of 5 repeats of these solutions. Microscopic analyses of the repeats were also performed.

RESULTS

Amounts of CaCl2 and NaPhos that were compatible in solutions containing 1.5%, 2%, 2.5%, and 3% AA were determined. The maximum amount of NaPhos that could be added to TrophAmine solutions of > = 2.5% AA containing at least 10 mmol/L of CaCl2 was 7.5 mmol/L. Adding 50 mg/dL of cysteine increased the amount of NaPhos that could be added to solutions containing 10 mmol/L of CaCl2 to 10 mmol/L.

CONCLUSION

Calcium chloride can be added to neonatal PN solutions containing NaPhos in concentrations that can potentially provide an intravenous intake of adequate amounts of calcium and phosphorus.

Nutritional support in children and young people with cancer undergoing chemotherapy

BACKGROUND

It is well documented that malnutrition is a common complication of paediatric malignancy and its treatment. Malnutrition can often be a consequence of cancer itself or a result of chemotherapy. Nutritional support aims to reverse malnutrition seen at diagnosis, prevent malnutrition associated with treatment and promote weight gain and growth. The most effective and safe forms of nutritional support in children and young people with cancer are not known.

OBJECTIVES

To determine the effects of any form of parenteral (PN) or enteral (EN) nutritional support, excluding vitamin supplementation and micronutrient supplementation, in children and young people with cancer undergoing chemotherapy and to determine the effect of the nutritional content of PN and EN. This is an update of a previous Cochrane review.

SEARCH METHODS

We searched the following databases for the initial review: CENTRAL (The Cochrane Library, Issue 2, 2009), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), CINAHL (1982 to 2006), the National Research Register (2007) and Dissertations & Theses (2007). Experts in the field were also contacted for information on relevant trials. For this update, we searched the same electronic databases from 2006 to September 2013. We also scrutinised the reference lists of included articles to identify additional trials.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any form of nutritional support with another, or control, in children or young people with cancer undergoing chemotherapy.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials. At least two authors independently assessed quality and extracted data. We contacted trialists for missing information.

MAIN RESULTS

The current review included the eight trials from the initial review and six new trials which randomised 595 participants (< 21 years of age) with leukaemias or solid tumours undergoing chemotherapy. The trials were all of low quality with the exception of two of the trials looking at glutamine supplementation. One small trial found that compared to EN, PN significantly increased weight (mean difference (MD) 4.12, 95% CI 1.91 to 6.33), serum albumin levels (MD 0.70, 95% CI 0.14 to 1.26), calorie intake (MD 22.00, 95% CI 5.12 to 38.88) and protein intake (MD 0.80, 95% CI 0.45 to 1.15). One trial comparing peripheral PN and EN with central PN found that mean daily weight gain (MD -27.00, 95% CI -43.32 to -10.68) and energy intake (MD -15.00, 95% CI -26.81 to -3.19) were significantly less for the peripheral PN and EN group, whereas mean change in serum albumin was significantly greater for that group (MD 0.47, 95% CI 0.13 to 0.81, P = 0.008). Another trial with few participants found an increase in mean energy intake (% recommended daily amount) in children fed an energy dense feed compared to a standard calorie feed (MD +28%, 95% CI 17% to 39%). Three studies looked at glutamine supplementation. The evidence suggesting that glutamine reduces severity of mucositis was not statistically significant in two studies (RR 0.64, 95% CI 0.19 to 2.2 and RR 0.85, 95% CI 0.66 to 1.1) and differences in reduction of infection rates were also not significant in two studies (RR 1.0, 95% CI 0.72 to 1.4 and RR 0.98, 95% CI 0.63 to 1.51). Only one study compared olive oil based PN to standard lipid containing PN. Despite similar calorie contents in both feeds, the standard lipid formula lead to greater weight gain (MD -0.34 z-scores, 95% CI -0.68 to 0.00). A single study compared standard EN with fructooligosaccharide containing EN. There was no difference in weight gain between groups (mean difference -0.12, 95% CI -0.57 to 0.33), with adverse effects (nausea) occurring equally between the groups (RR 0.92, 95% CI 0.48 to 1.74).

AUTHORS' CONCLUSIONS

There is limited evidence from individual trials to suggest that PN is more effective than EN in well-nourished children and young people with cancer undergoing chemotherapy. The evidence for other methods of nutritional support remains unclear. Limited evidence suggests an energy dense feed increases mean daily energy intake and has a positive effect on weight gain. Evidence suggesting glutamine supplementation reduces incidence and severity of mucositis, infection rates and length of hospital stay is not statistically significant. Further research, incorporating larger sample sizes and rigorous methodology utilising valid and reliable outcome measures, is essential.

Bronchopulmonary dysplasia: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases

Bronchopulmonary dysplasia (BPD) is the most common complication of extreme preterm birth. Infants who develop BPD manifest aberrant or arrested pulmonary development and can experience lifelong alterations in cardiopulmonary function. Despite decades of promising research, primary prevention of BPD has proven elusive. This workshop report identifies current barriers to the conduct of primary prevention studies for BPD and causal pathways implicated in BPD pathogenesis. Throughout, we highlight promising areas for research to improve understanding of normal and aberrant lung development, distinguish BPD endotypes, and ascertain biomarkers for more targeted therapeutic approaches to prevention. We conclude with research recommendations and priorities to accelerate discovery and promote lung health in infants born preterm.

Membrane transporters in a human genome-scale metabolic knowledgebase and their implications for disease

Membrane transporters enable efficient cellular metabolism, aid in nutrient sensing, and have been associated with various diseases, such as obesity and cancer. Genome-scale metabolic network reconstructions capture genomic, physiological, and biochemical knowledge of a target organism, along with a detailed representation of the cellular metabolite transport mechanisms. Since the first reconstruction of human metabolism, Recon 1, published in 2007, progress has been made in the field of metabolite transport. Recently, we published an updated reconstruction, Recon 2, which significantly improved the metabolic coverage and functionality. Human metabolic reconstructions have been used to investigate the role of metabolism in disease and to predict biomarkers and drug targets. Given the importance of cellular transport systems in understanding human metabolism in health and disease, we analyzed the coverage of transport systems for various metabolite classes in Recon 2. We will review the current knowledge on transporters (i.e., their preferred substrates, transport mechanisms, metabolic relevance, and disease association for each metabolite class). We will assess missing coverage and propose modifications and additions through a transport module that is functional when combined with Recon 2. This information will be valuable for further refinements. These data will also provide starting points for further experiments by highlighting areas of incomplete knowledge. This review represents the first comprehensive overview of the transporters involved in central metabolism and their transport mechanisms, thus serving as a compendium of metabolite transporters specific for human metabolic reconstructions.

Transcriptional responses of neonatal mouse lung to hyperoxia by Nrf2 status

Hyperoxia exposure can inhibit alveolar growth in the neonatal lung through induction of p21/p53 pathways and is a risk factor for the development of bronchopulmonary dysplasia (BPD) in preterm infants. We previously found that activation of nuclear factor erythroid 2 p45-related factor (Nrf2) improved survival in neonatal mice exposed to hyperoxia likely due to increased expression of anti-oxidant response genes. It is not known however, whether hyperoxic induced Nrf2 activation attenuates the growth impairment caused by hyperoxia in neonatal lung. To determine if Nrf2 activation modulates cell cycle regulatory pathway genes associated with growth arrest we examined the gene expression in the lungs of Nrf2(-/-) and Nrf2(+/+) neonatal mice at one and 3days of hyperoxia exposure.

METHODS

Microarray analysis was performed in neonatal Nrf2(+/+) and Nrf2(-/-) lungs exposed to one and 3days of hyperoxia. Sulforaphane, an inducer of Nrf2 was given to timed pregnant mice to determine if in utero exposure attenuated p21 and IL-6 gene expression in wildtype neonatal mice exposed to hyperoxia.

RESULTS

Cell cycle regulatory genes were induced in Nrf2(-/-) lung at 1day of hyperoxia. At 3days of hyperoxia, induction of cell cycle regulatory genes was similar in Nrf2(+/+) and Nrf2(-/-) lungs, despite higher inflammatory gene expression in Nrf2(-/-) lung.

CONCLUSION

p21/p53 pathways gene expression was not attenuated by Nrf2 activation in neonatal lung. In utero SUL did not attenuate p21 expression in wildtype neonatal lung exposed to hyperoxia. These findings suggest that although Nrf2 activation induces expression of anti-oxidant genes, it does not attenuate alveolar growth arrest caused by exposure to hyperoxia.

Behavioral and biochemical evidence of the role of acetaldehyde in the motivational effects of ethanol

Since Chevens' report, in the early 50's that his patients under treatment with the aldehyde dehydrogenase inhibitor, antabuse, could experience beneficial effects when drinking small volumes of alcoholic beverages, the role of acetaldehyde (ACD) in the effects of ethanol has been thoroughly investigated on pre-clinical grounds. Thus, after more than 25 years of intense research, a large number of studies have been published on the motivational properties of ACD itself as well as on the role that ethanol-derived ACD plays in the effects of ethanol. Accordingly, in particular with respect to the motivational properties of ethanol, these studies were developed following two main strategies: on one hand, were aimed to challenge the suggestion that also ACD may exert motivational properties on its own, while, on the other, with the aid of enzymatic manipulations or ACD inactivation, were aimed to test the hypothesis that ethanol-derived ACD might have a role in ethanol motivational effects. Furthermore, recent evidence significantly contributed to highlight, as possible mechanisms of action of ACD, its ability to commit either dopaminergic and opioidergic transmission as well as to activate the Extracellular signal Regulated Kinase cascade transduction pathway in reward-related brain structures. In conclusion, and despite the observation that ACD seems also to have inherited the elusive nature of its parent compound, the behavioral and biochemical evidence reviewed points to ACD as a neuroactive molecule able, on its own and as ethanol metabolite, to exert motivational effects.

Parenteral nutrition additive shortages: the short-term, long-term and potential epigenetic implications in premature and hospitalized infants

Nutrition support practitioners are currently dealing with shortages of parenteral nutrition micronutrients, including multivitamins (MVI), selenium and zinc. A recent survey from the American Society of Enteral and Parenteral Nutrition (ASPEN) indicates that this shortage is having a profound effect on clinical practice. A majority of respondents reported taking some aggressive measures to ration existing supplies. Most premature infants and many infants with congenital anomalies are dependent on parenteral nutrition for the first weeks of life to meet nutritional needs. Because of fragile health and poor reserves, they are uniquely susceptible to this problem. It should be understood that shortages and rationing have been associated with adverse outcomes, such as lactic acidosis and Wernicke encephalopathy from thiamine deficiency or pulmonary and skeletal development concerns related to inadequate stores of Vitamin A and D. In this review, we will discuss the current parenteral shortages and the possible impact on a population of very low birth weight infants. This review will also present a case study of a neonate who was impacted by these current shortages.

Cord blood glutathione depletion in preterm infants: correlation with maternal cysteine depletion

BACKGROUND

Depletion of blood glutathione (GSH), a key antioxidant, is known to occur in preterm infants.

OBJECTIVE

Our aim was to determine: 1) whether GSH depletion is present at the time of birth; and 2) whether it is associated with insufficient availability of cysteine (cys), the limiting GSH precursor, or a decreased capacity to synthesize GSH.

METHODOLOGY

Sixteen mothers delivering very low birth weight infants (VLBW), and 16 mothers delivering healthy, full term neonates were enrolled. Immediately after birth, erythrocytes from umbilical vein, umbilical artery, and maternal blood were obtained to assess GSH [GSH] and cysteine [cys] concentrations, and the GSH synthesis rate was determined from the incorporation of labeled cysteine into GSH in isolated erythrocytes ex vivo, measured using gas chromatography mass spectrometry.

PRINCIPAL FINDINGS

Compared with mothers delivering at full term, mothers delivering prematurely had markedly lower erythrocyte [GSH] and [cys] and these were significantly depressed in VLBW infants, compared with term neonates. A strong correlation was found between maternal and fetal GSH and cysteine levels. The capacity to synthesize GSH was as high in VLBW as in term infants.

CONCLUSION

The current data demonstrate that: 1) GSH depletion is present at the time of birth in VLBW infants; 2) As VLBW neonates possess a fully active capacity to synthesize glutathione, the depletion may arise from inadequate cysteine availability, potentially due to maternal depletion. Further studies would be needed to determine whether maternal-fetal cysteine transfer is decreased in preterm infants, and, if so, whether cysteine supplementation of mothers at risk of delivering prematurely would strengthen antioxidant defense in preterm neonates.

Risk factors for necrotizing enterocolitis totalis: a case-control study

OBJECTIVE

The objective of this study was to compare demographic and clinical events in three groups of preterm neonates: those with necrotizing enterocolitis totalis (NEC-T), those with NEC non-totalis (NEC non-T) and in preterm patients without NEC.

STUDY DESIGN

This retrospective case-control study was conducted at Yale New Haven Children's Hospital using patient data from January 1991 to December 2007. Study patients were less than 36 weeks of gestational age (GA) at birth, without gastrointestinal (GI) malformations. Cases (NEC-T) were diagnosed at operation or at autopsy with observation of >80% necrosis of the GI tract. Two control groups were assigned: Group 1 or NEC non-T and Group II or Non-NEC. Two to four controls per case were matched to cases by GA at birth±2 weeks. Demographic and clinical data for the day of diagnosis and retrospectively up to 7 days preceding diagnosis were recorded for those with NEC-T and NEC. Group II controls were matched for date of birth and day of life, in addition to GA at birth.

RESULT

A total of 14 075 patients were admitted to the Newborn Special Care Unit during the study interval. Overall 328 patients (2.3%) developed NEC≥Bell's Stage II; 39 patients met inclusion criteria for NEC-T case status; 148 NEC non-T and 110 non-NEC controls were assigned. In the comparison of NEC T and NEC non-T neonates, use of breast milk was associated with decreased risk of NEC-T, adjusted odds ratio (OR)=0.26, 95% confidence interval (CI) of OR=0.08-0.085, P=0.03. When NEC T and non-NEC patients were compared, having reached full-enteral feeds before the date of diagnosis of the matched case (adjusted OR=28.5, 95% CI of OR=2.7-299, P=0.005) and use of breast milk (adjusted OR=0.09, 95% CI of OR=0.02-0.56, P=0.01) were significantly different between the two groups.

CONCLUSION

Breast milk usage was significantly associated with decreased occurrence of NEC-T in our comparison of NEC-T, NEC non-T and non-NEC patients. Although there were some differences, the majority of demographic and clinical variables assessed were not shown to be significantly different between cases and controls. This highlights the need for more biological data in assessing risk of developing NEC-T.

Amino acid composition in parenteral nutrition: what is the evidence?

PURPOSE OF REVIEW

Complete parenteral nutrition solutions contain mixed amino acid products providing all nine essential amino acids and a varying composition of nonessential amino acids. Relatively little rigorous comparative efficacy research on altered parenteral nutrition amino acid composition has been published in recent years.

RECENT FINDINGS

Limited data from randomized, double-blind, adequately powered clinical trials to define optimal doses of total or individual amino acids in parenteral nutrition are available. An exception is the growing number of studies on the efficacy of glutamine supplementation of parenteral nutrition or given as a single parenteral agent. Parenteral glutamine appears to confer benefit in selected patients; however, additional data to define optimal glutamine dosing and the patient subgroups who may most benefit from this amino acid are needed. Although some promising studies have been published, little data are available in the current era of nutrition support on the clinical efficacy of altered doses of arginine, branched chain amino acids, cysteine, or taurine supplementation of parenteral nutrition.

SUMMARY

Despite routine use of parenteral nutrition, surprisingly little clinical efficacy data are available to guide total or specific amino acid dosing in adult and pediatric patients requiring this therapy. This warrants increased attention by the research community and funding agencies to better define optimal amino acid administration strategies in patient subgroups requiring parenteral nutrition.

Nutritional support in children and young people with cancer undergoing chemotherapy

BACKGROUND

Malnutrition can often be a consequence of cancer itself or a result of chemotherapy. Nutritional support aims to reverse malnutrition seen at diagnosis, prevent malnutrition associated with treatment and promote weight gain and growth. The most effective and safe forms of nutritional support in children and young people with cancer are unclear.

OBJECTIVES

To determine the effects of any form of parenteral (PN) or enteral (EN) nutritional support in children and young people with cancer undergoing chemotherapy.

SEARCH STRATEGY

We searched the following databases: CENTRAL (The Cochrane Library 2009, Issue 2), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), CINAHL (1982 to 2006), the National Research Register (2007) and Dissertations & Theses (2007). We scrutinised reference lists of articles to identify additional trials. We also contacted experts in the field for information on relevant trials.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials comparing any form of nutritional support with another, or control, in children or young people with cancer undergoing chemotherapy.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials. Three authors independently assessed quality and extracted data. We contacted trialists for missing information.

MAIN RESULTS

We included eight trials which randomised 159 participants (< 21 years) with leukaemias or solid tumours undergoing chemotherapy. The trials were all of low quality. One small trial found that compared to EN, PN significantly increased weight (mean difference (MD) 4.12; 95% CI 1.91 to 6.33), serum albumin levels (MD 0.70; 95% CI 0.14 to 1.26), calorie intake (MD 22.00; 95% CI 5.12 to 38.88) and protein intake (MD 0.80; 95% CI 0.45 to 1.15). One trial comparing peripheral PN and EN with central PN found that mean daily weight gain (MD -27.00; 95% CI -43.32 to -10.68) and energy intakes (MD -15.00; 95% CI -26.81 to -3.19) were significantly less for the peripheral PN and EN group, whereas mean change in serum albumin was significantly greater for that group(MD 0.47; 95% CI 0.13 to 0.81, P = 0.008).

AUTHORS' CONCLUSIONS

There is limited evidence from individual trials to suggest that parenteral nutrition is more effective than enteral nutrition in well-nourished children and young people with cancer undergoing chemotherapy. The evidence for other methods of nutritional support remains unclear. No studies were identified comparing the nutritional content in the PN or EN groups of studies. Further research, incorporating larger sample sizes and rigorous methodology utilising valid and reliable outcome measures, is essential.

l-Cysteine reduces oral ethanol self-administration and reinstatement of ethanol-drinking behavior in rats

Our previous findings have shown that l-cysteine, a non essential amino acid, prevented ethanol (EtOH) induced conditioned place preference. The aim of the present study was to examine the effect of l-cysteine on the acquisition and maintenance of oral EtOH self-administration and on the reinstatement of EtOH-drinking behavior in Wistar rats. Rats were pretreated intraperitoneally with saline or l-cysteine (20 and 40 mg/kg) 30 min before each acquisition trial, in an operant nose-poking paradigm where they were given the opportunity to orally self-administer tap water or EtOH (5-10% v/v). Further, to evaluate if l-cysteine reduces the acquired oral EtOH self-administration, we carried out an independent experiment in which rats were trained to self-administer EtOH (10%); after all groups of rats developed similarly stable oral EtOH self-administration, the effect of l-cysteine (0, 40, 60, 80 and 100mg/kg) was tested. An additional group of rats was pretreated with saline or l-cysteine (80 mg/kg) and tested on reinstatement after EtOH extinction and, at the end of last reinstatement session, were utilized to measure blood and brain EtOH levels. The animals that had access to EtOH solution discriminated between the active and inactive nose-pokes and showed rates of active nose-pokes significantly higher than the tap water group. Furthermore, rats self-administering EtOH (10%) also demonstrated extinction behavior and gradually reinstated active nose-poke responding when EtOH was reintroduced. l-cysteine reduced both the acquisition and maintenance of oral EtOH self-administration. The reduced reinstatement of EtOH-drinking behavior was paralleled by a significant reduction of EtOH intake and correlated with blood and brain EtOH levels. The efficacy of l-cysteine on the various phases of alcohol drinking in rats, could represent an interesting pharmacological approach and could open a new line of research for the development of therapies to reduce EtOH intake in alcoholic patients.

Necrotizing enterocolitis in newborns: pathogenesis, prevention and management

Necrotizing enterocolitis (NEC) is primarily a disease process of the gastrointestinal (GI) tract of premature neonates that results in inflammation and bacterial invasion of the bowel wall. Despite advances in the care of premature infants, NEC remains one of the leading causes of morbidity and mortality in this population. It occurs in 1-5% of all neonatal intensive care admissions and 5-10% of all very low birthweight (<1500 g) infants. Although research has presented an interesting array of potential contributing factors, the precise aetiology of this multifactorial disease process remains elusive. Historically, it was believed that NEC arose predominantly from ischaemic injury to the immature GI tract, yet alternate plausible hypotheses indicate that many factors are likely to be involved. These may include issues related to the introduction and advancement of enteric feeding, alterations in the normal bacterial colonization of the GI tract, bacterial translocation and activation of the cytokine cascade, decreased epidermal growth factor, increased platelet activating factor, and mucosal damage from free radical production. Clinical manifestations of NEC may be vague, including increased episodes of apnoea, desaturations, bradycardia, lethargy and temperature instability. There may also be GI-specific symptoms such as feeding intolerance, emesis, bloody stools, abdominal distention and tenderness, and abdominal wall discolouration. Laboratory values may be indicative of infection, coagulation abnormalities and fluid retention. Radiographic signs may include ileus, dilated or fixed intestinal loops, air in the intestinal wall or free air in the abdomen. Medical treatment typically consists of bowel rest and decompression, antibacterial therapy, and management of other haematological or electrolyte imbalances. Increased respiratory and cardiovascular support is sometimes needed. In neonates who do not respond adequately to medical management, or if pneumoperitoneum is present, surgical intervention may occur with either use of a peritoneal drain or laparotomy. Advances in antenatal and neonatal care have resulted in increased survival of extremely preterm neonates. As this at-risk population continues to increase, an effective preventative strategy for NEC is needed. One preventative strategy is the use of antenatal corticosteroids to enhance maturation of the fetus if preterm delivery is likely. Recommendation of use of breast milk, early initiation of trophic feeds and judicoius advancement of enteric feeds are current postnatal strategies. Other preventative strategies that have been investigated include the use of oral antibacterials, antioxidants, supplementation of arginine and epidermal growth factor, none of which have changed clinical practice. Recent promising data indicate that prophylactic use of probiotics may play a role in preventing the onset of NEC. However, more large-scale, definitive studies are needed.

Metabolism of methionine in the newborn infant: response to the parenteral and enteral administration of nutrients

The rates of transmethylation and transsulfuration of methionine were quantified using [1-(13)C]methionine and [C2H3]methionine tracers in newborn infants born at term gestation and in prematurely born low birth weight infants. Whole body rate of protein breakdown was also measured using [2H5]phenylalanine. The response to enteral formula feeding and parenteral nutrition was examined in full term and prematurely born babies, respectively. The relative rates of appearance of methionine and phenylalanine were comparable to the amino acid composition of mixed body proteins. Rates of transmethylation were high, both in full term infants (fast 32 +/- 14 micromol kg(-1) x h(-1); fed 21.7 +/- 3.2) and in preterm infants (57.2 +/- 14.8). Significant flux through the transsulfuration pathway was evident (full term: fast 6.0 +/- 4.4, fed 4.1 +/- 2.1; preterm: 24.9 +/- 9.9 micromol kg(-1) x h(-1)). Transsulfuration of methionine is evident in the human newborn in the immediate neonatal period, suggesting that cysteine may not be considered a "conditionally" essential amino acid for the neonate. The high rate of transmethylation may reflect the high methylation demand, whereas high rates of transsulfuration in premature babies may be related to high demands for glutathione and to the amounts of methionine in parenteral amino acid mixtures.

Optimal protein and energy intakes in preterm infants

There is compelling evidence that current nutritional practice fails to provide sufficient dietary protein for preterm infants, especially extremely and very low birth weight infants. Nutrient requirements can be estimated by a variety of techniques, but most suggest that these infants will require a protein intake of 3.5-4.0 g/kg/d. Even when these infants are able to tolerate full enteral feeds, most currently available artificial milk formula or breast milk fortifiers will not ensure these protein requirements are met except when fed at high volumes. Energy requirements on the other hand may be currently met, and evidence from controlled studies suggests that intakes higher than 110-135 kcal/kg/d might not be beneficial. The data from studies on neonatal adiposity outcomes, and from studies examining relationship between early growth and later cardiovascular outcome, also suggest that excess nutrient intake might be harmful. In the light of this data, optimal intakes and protein-energy ratios require re-appraisal.

Inhibition of NAD(P)H oxidase reduces apoptosis and avascular retina in an animal model of retinopathy of prematurity

PURPOSE

To study the mechanisms of action of the antioxidants, n-acetylcysteine (NAC), and the nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase oxidase inhibitor, apocynin, on intravitreous neovascularization (IVNV), and retinal avascularity in a rat model of retinopathy of prematurity (ROP).

METHODS

Newborn rats exposed to oxygen-induced retinopathy underwent intraperitoneal (IP) injections of NAC (150 mg/kg) at post-natal day (p)2, p6, p10 (early NAC-treated), or p12 through p17 (late NAC-treated), apocynin (10 mg/kg) from p12 through p17, or phosphate buffered saline (PBS; controls). Lipid hydroperoxide (LHP) was measured in early NAC-treated oxygen-induced retinopathy (OIR) at p7, p14 and p18. Pups were placed in room air at p14. At p18, retinal flat mounts were scored for IVNV and avascular/total retinal area, or retinas were assayed for cleaved caspase-3 and vascular endothelial growth factor (VEGF) protein. In non-injected OIR pups, retinas were assayed for gp91(phox). Cryosections were stained with isolectin B4, cleaved caspase-3, CD68, CD31, gp91(phox), neuron-glial antigen 2 (NG-2), or anti-glial fibrillary acidic protein (GFAP) and visualized with confocal microscopy.

RESULTS

LHP increased over time in retinas from OIR exposed pups in association with IVNV. Early NAC-treated retinas had significantly reduced LHP compared to PBS-control at p18 (p<0.012). However, neither early nor late treatment with NAC had an effect on IVNV or retinal avascularity. Although apocynin had no effect on IVNV, it reduced both avascular retina (p=0.017) and retinal cleaved caspase-3 determined by western blot (p=0.021). In cryosections from OIR eyes, cleaved caspase-3 positive cells co-labeled with some lectin-stained vessels, NG2 labeled cells, and with GFAP positive cells in the inner nuclear layer. We found that the intravascular expression of gp91(phox) co-localized mostly with CD31 and some CD68 positive cells.

CONCLUSIONS

Our results do not support the antioxidant properties of NAC as effective in reducing IVNV or avascular retina in the 50/10 OIR rat model. Apocynin reduced avascularity and apoptosis in the OIR model perhaps through pathways triggered by ROS generation but upstream from LHP production. Further study and consideration may be given to apocynin or NAD(P)H oxidase inhibitors as adjunctive therapy for ROP to reduce the avascular retina.

Cysteine, cystine or N-acetylcysteine supplementation in parenterally fed neonates

BACKGROUND

L-cysteine is thought to be a conditionally essential (i.e., essential under certain conditions) amino acid for neonates. It is a precursor of glutathione, an antioxidant that may reduce oxidation injury. The addition of cysteine to parenteral nutrition (PN) allows for the reduction of the amount of methionine in PN, thereby limiting hepatotoxicity, and acidifies the solution, thereby increasing calcium and phosphate solubility, and potentially improving bone mineralization.

OBJECTIVES

To determine the effects of supplementing parenteral nutrition with cysteine, cystine or its precursor N-acetylcysteine on neonatal growth and short and long-term outcomes.

SEARCH STRATEGY

The standard search method of the Cochrane Neonatal Review Group was used. MEDLINE (1966-December 2005), EMBASE (1974-December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2006) and recent abstracts (until December 2005) from the Society for Pediatric Research/American Pediatric Society, Eastern Society for Pediatric Research, and Society for Parenteral and Enteral Nutrition were searched.

SELECTION CRITERIA

All randomized (RCTs) and quasi-randomized trials that examined the effects of cysteine, cystine or N-acetylcysteine supplementation of neonatal PN were reviewed. Predetermined outcome variables included growth, nitrogen retention, mortality, morbidity secondary to oxidation injury, bone accretion, acidosis, liver disease, and cysteine levels.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Collaboration and its Neonatal Review Group were used. Statistical analysis included relative risk, risk difference, and weighted mean difference (WMD).

MAIN RESULTS

Six trials fulfilled entry criteria. The majority of patients in these trials were preterm. Five small trials evaluated short-term cysteine supplementation of cysteine-free PN. One large multicenter RCT evaluated short-term N-acetylcysteine supplementation of cysteine-containing PN in extremely low birth weight infants (< or = 1000 grams).

PRIMARY OUTCOMES

Growth was not significantly affected by cysteine supplementation (evaluated in one quasi-randomized trial) or by N-acetylcysteine supplementation (evaluated in one RCT). Nitrogen retention was significantly increased by cysteine supplementation (studied in four trials) (WMD 31.8 mg/kg/day, 95% confidence interval +8.2, +55.4, n = 95, including 73 preterm infants).

SECONDARY OUTCOMES

Plasma levels of cysteine were significantly increased by cysteine supplementation but not by N-acetylcysteine supplementation. N-acetylcysteine supplementation did not significantly affect the risks of death by 36 postmenstrual weeks, bronchopulmonary dysplasia (BPD), death or BPD, retinopathy of prematurity (ROP), severe ROP, necrotizing enterocolitis requiring surgery, periventricular leukomalacia, intraventricular hemorrhage (IVH), or severe IVH. No data were available on other outcomes.

AUTHORS' CONCLUSIONS

Available evidence from RCTs shows that routine short-term cysteine chloride supplementation of cysteine-free PN in preterm infants improves nitrogen balance.However, there is insufficient evidence to assess the risks of cysteine supplementation, especially regarding metabolic acidosis, which has been reported during the first two weeks of cysteine chloride administration. Available evidence from a large RCT trial does not support routine N-acetylcysteine supplementation of cysteine-containing PN in extremely low birth weight infants. A large RCT would be required to assess whether routine prolonged cysteine supplementation of cysteine-free PN affects growth and short and long-term neonatal outcomes in very low birth weight infants.