Enteral glutamine supplementation and morbidity in low birth weight infants

Amino acids for the prevention of mortality and morbidity in preterm infants: a systematic review and network meta-analysis

To determine the effectiveness and safety of amino acids in preventing the mortality and morbidity among preterm infants. We conducted a systematic review and network meta-analysis. We searched MEDLINE, EMBASE, Web of Science, CINAHL, Scopus, Cochrane, and Google Scholar, and grey literature, from databases inception to January 2021. We included randomized trials that evaluated any amino acids on preterm or low-birth weight infants. We performed frequentist pairwise and network meta-analyses and used the GRADE methodology to assess the certainty of the evidence and provide a summary of the results.We included 18 trials (3702 infants). Low certainty evidence showed that there seems to be no benefit for arginine, glutamine, or N-acetylcysteine in reducing all-cause mortality. Oral arginine likely results in reduction of necrotizin enterocolitis (NEC) stage ≥ II (OR 0.48; 95% CI 0.26-0.90; moderate certainty). Oral glutamine may reduce the likelihood of developing late-onset sepsis (LOS) compared to placebo (OR 0.62; 95% CI 0.47-0.82; low certainty); and likely reduces time to reach full enteral feeding (MD = - 2.63 days; 95% CI - 4.99 to - 0.27; moderate certainty). Amino acids may have no effect on mortality. Oral arginine may reduce severe NEC, and oral glutamine may reduce LOS and the time to reach full feeding.Systematic review registration: PROSPERO registration number: CRD4201603873.

NutriBrain: protocol for a randomised, double-blind, controlled trial to evaluate the effects of a nutritional product on brain integrity in preterm infants

Background

The gut microbiota and the brain are connected through different mechanisms. Bacterial colonisation of the gut plays a substantial role in normal brain development, providing opportunities for nutritional neuroprotective interventions that target the gut microbiome. Preterm infants are at risk for brain injury, especially white matter injury, mediated by inflammation and infection. Probiotics, prebiotics and L-glutamine are nutritional components that have individually already demonstrated beneficial effects in preterm infants, mostly by reducing infections or modulating the inflammatory response. The NutriBrain study aims to evaluate the benefits of a combination of probiotics, prebiotics and L-glutamine on white matter microstructure integrity (i.e., development of white matter tracts) at term equivalent age in very and extremely preterm born infants.

Methods

This study is a double-blind, randomised, controlled, parallel-group, single-center study. Eighty-eight infants born between 24 + 0 and < 30 + 0 weeks gestational age and less than 72 h old will be randomised after parental informed consent to receive either active study product or placebo. Active study product consists of a combination of Bifidobacterium breve M-16V, short-chain galacto-oligosaccharides, long-chain fructo-oligosaccharides and L-glutamine and will be given enterally in addition to regular infant feeding from 48 to 72 h after birth until 36 weeks postmenstrual age. The primary study outcome of white matter microstructure integrity will be measured as fractional anisotropy, assessed using magnetic resonance diffusion tensor imaging at term equivalent age and analysed using Tract-Based Spatial Statistics. Secondary outcomes are white matter injury, brain tissue volumes and cortical morphology, serious neonatal infections, serum inflammatory markers and neurodevelopmental outcome.

Discussion

This study will be the first to evaluate the effect of a combination of probiotics, prebiotics and L-glutamine on brain development in preterm infants. It may give new insights in the development and function of the gut microbiota and immune system in relation to brain development and provide a new, safe treatment possibility to improve brain development in the care for preterm infants.

Trial registration

ISRCTN, ISRCTN96620855. Date assigned: 10/10/2017.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02570-x.

Differences in the Gut Microbiota Establishment and Metabolome Characteristics Between Low- and Normal-Birth-Weight Piglets During Early-Life

Low-birth-weight (LBW) piglets are at a high-risk for postnatal growth failure, mortality, and metabolic disorders later in life. Early-life microbial exposure is a potentially effective intervention strategy for modulating the health and metabolism of the host. Yet, it has not been well elucidated whether the gut microbiota development in LBW piglets is different from their normal littermates and its possible association with metabolite profiles. In the current study, 16S rRNA gene sequencing and metabolomics was used to investigate differences in the fecal microbiota and metabolites between LBW and normal piglets during early-life, including day 3 (D3), 7 (D7), 14 (D14), 21 (D21, before weaning), and 35 (D35, after birth). Compared to their normal littermates, LBW piglets harbored low proportions of Faecalibacterium on D3, Flavonifractor on D7, Lactobacillus, Streptococcus, and Prevotella on D21, as well as Howardella on D21 and D35. However, the abundance of Campylobacter on D7 and D21, Prevotella on D14 and D35, Oscillibacter and Moryella on D14 and D21, and Bacteroides on D21 was significantly higher in LBW piglets when compared with normal piglets. The results of the metabolomics analysis suggested that LBW significantly affected fecal metabolites involved in fatty acid metabolism (e.g., linoleic acid, α-linolenic acid, and arachidonic acid), amino acid metabolism (e.g., valine, phenylalanine, and glutamic acid), as well as bile acid biosynthesis (e.g., glycocholic acid, 25-hydroxycholesterol, and chenodeoxycholic acid). Spearman correlation analysis revealed a significant negative association between Campylobacter and N1-acetylspermine on D7, Moryella and linoleic acid on D14, Prevotella and chenodeoxycholic acid on D21, and Howardella and phenylalanine on D35, respectively. Collectively, LBW piglets have a different gut bacterial community structure when compared with normal-birth-weight (NBW) piglets during early-life, especially from 7 to 21 days of age. Also, a distinctive metabolic status in LBW piglets might be partly associated with the altered intestinal microbiota. These findings may further elucidate the factors potentially associated with the impaired growth and development of LBW piglets and facilitate the development of nutritional interventions.

Enteral Arg-Gln Dipeptide Administration Increases Retinal Docosahexaenoic Acid and Neuroprotectin D1 in a Murine Model of Retinopathy of Prematurity

Purpose

Low levels of the long chain polyunsaturated fatty acid (LCPUFA) docosahexaenoic acid (DHA) have been implicated in retinopathy of prematurity (ROP). However, oral DHA suffers from poor palatability and is associated with increased bleeding in premature infants. We asked whether oral administration of the neutraceutical arginine-glutamine (Arg-Glu) could increase retinal DHA and improve outcomes in a mouse model of oxygen-induced retinopathy (OIR).

Methods

Postnatal day 7 (P7) pups were maintained at 75% oxygen for 5 days and then returned to room air on P12. Pups were gavaged twice daily with Arg-Gln or vehicle from P12 to P17 and eyes were harvested for analysis on P17. Vaso-obliteration and vascular density were assessed on retinal flat mounts and preretinal neovascularization was assessed on retinal cross sections. Retinas were used for measurement of DHA and 10,17S-docosatriene (neuroprotectin D1, NPD1), a key DHA-derived lipid, and for analysis by reverse-phase protein array (RPPA).

Results

With Arg-Gln treatment, retinal DHA and NPD1 levels were increased in OIR pups. Arg-Gln reduced preretinal neovascularization by 39 ± 6% (P < 0.05) relative to vehicle control. This was accompanied by a restoration of vascular density of the retina in the pups treated with Arg-Gln (73.0 ± 3.0%) compared to vehicle (53.1 ± 3.4%; P < 0.05). Arg-Gln dipeptide restored OIR-induced signaling changes toward normoxia and was associated with normalization of insulin-like growth factor receptor 1 signaling and reduction of apoptosis and an increase in anti-apoptosis proteins.

Conclusions

Arg-Gln may serve as a safer and easily tolerated nutraceutical agent for prevention or treatment of ROP.

Nutritional support for low birth weight infants: insights from animal studies

Infants born with low birth weights (<2500 g, LBW), accounting for about 15 % of newborns, have a high risk for postnatal growth failure and developing the metabolic syndromes such as type 2 diabetes, CVD and obesity later in life. Improper nutrition provision during critical stages, such as undernutrition during the fetal period or overnutrition during the neonatal period, has been an important mediator of these metabolic diseases. Considering the specific physiological status of LBW infants, nutritional intervention and optimisation during early life merit further attention. In this review, the physiological and metabolic defects of LBW infants were summarised from a nutritional perspective. Available strategies for nutritional interventions and optimisation of LBW infants, including patterns of nutrition supply, macronutrient proportion, supplementation of amino acids and their derivatives, fatty acids, nucleotides, vitamins, minerals as well as hormone and microbiota manipulators, were reviewed with an aim to provide new insights into the advancements of formulas and human-milk fortifiers.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2015, Issue 12), MEDLINE, EMBASE and Maternity and Infant Care (to December 2015), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 12 randomised controlled trials in which a total of 2877 preterm infants participated. Six trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not find an effect of glutamine supplementation on mortality (typical relative risk 0.97, 95% confidence interval 0.80 to 1.17; risk difference 0.00, 95% confidence interval -0.03 to 0.02) or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Three trials that assessed neurodevelopmental outcomes in children aged 18 to 24 months and beyond did not find any effects.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2015, Issue 12), MEDLINE, EMBASE and Maternity and Infant Care (to December 2015), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 12 randomised controlled trials in which a total of 2877 preterm infants participated. Six trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not find an effect of glutamine supplementation on mortality (typical relative risk 0.97, 95% confidence interval 0.80 to 1.17; risk difference 0.00, 95% confidence interval -0.03 to 0.02) or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Three trials that assessed neurodevelopmental outcomes in children aged 18 to 24 months and beyond did not find any effects.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Enteral L-Arginine and Glutamine Supplementation for Prevention of NEC in Preterm Neonates

Objective. Evaluating the efficacy and safety of arginine and glutamine supplementation in decreasing the incidence of NEC among preterm neonates. Methods. Prospective case-control study done on 75 preterm neonates ≤34 weeks, divided equally into L-arginine group receiving enteral L-arginine, glutamine group receiving enteral glutamine, and control group. Serum L-arginine and glutamine levels were measured at time of enrollment (sample 1), after 14 days of enrollment (sample 2), and at time of diagnosis of NEC (sample 3). Results. The incidence of NEC was 9.3%. There was no difference in the frequency of NEC between L-arginine and control groups (P > 0.05). NEC was not detected in glutamine group; L-arginine concentrations were significantly lower in arginine group than control group in both samples while glutamine concentrations were comparable in glutamine and control groups in both samples. No significant difference was found between groups as regards number of septic episodes, duration to reach full oral intake, or duration of hospital stay. Conclusion. Enteral L-arginine supplementation did not seem to reduce the incidence of NEC. Enteral glutamine may have a preventive role against NEC if supplied early to preterm neonates. However, larger studies are needed to confirm these findings. This work is registered in ClinicalTrials.gov (ClinicalTrials.gov Identifier: NCT01263041).

Plasma glutamine deficiency is associated with multiple organ failure in critically ill children

A low plasma glutamine concentration (<420 µmol/L) is an independent risk factor for mortality in critically ill adult patients. Glutamine metabolism in children is less well characterized. However, pediatric ICU (PICU) mortality is low and, therefore, mortality is difficult to use as an endpoint. Here we evaluated if plasma glutamine concentration at admission to the PICU, relates to the development of multiple organ failure, using pediatric logistic organ dysfunction score (PELOD)-score. In this observational study, consecutive critically ill children (n = 149) admitted to the PICU of a tertiary university hospital as well as a reference group of healthy children (n = 60) were included. Plasma glutamine concentration and the PELOD were determined at admission for all patients and at day 5 for those patients still in the PICU. Plasma glutamine concentration at admission was low in the PICU patients as compared to controls (p = 0.00002) and patients with a low plasma glutamine concentration had more organ failure as compared to patients with higher plasma glutamine concentration (p = 0.0001). Plasma glutamine concentration normalized in patients staying >5 days in the PICU. Plasma glutamine depletion was present in 40 % of patients at PICU admission and it was associated with the development of multiple organ failure. Furthermore, the majority of the critically ill children normalized their plasma glutamine concentration within 5 days, which is different from adult ICU patients. The study suggests that an initial plasma glutamine deficiency is associated with multiple organ failure in critically ill children.

Infants at risk of cerebral palsy: a systematic review of outcomes used in Cochrane studies of pregnancy, childbirth and neonatology

OBJECTIVE

To systematically review meta-analyses (MAs) and randomised controlled trials (RCTs) of interventions for infants at risk of cerebral palsy (CP), to determine if consensus exists in study end-points.

METHODS

MAs within the "Neonatal" and "Pregnancy and Childbirth" Review Groups in Cochrane Database of Systematic Reviews (to June 2011) were included if they contained risk factors for CP as a study end-point, and were either published in 2010 or 2011 or cited >20 times in Sciverse Scopus. Up to 20 RCTs from each MA were included. Outcome measures, definitions and cut-points for ordinal groupings were extracted from MAs and RCTs and frequencies calculated.

RESULTS

Twenty-two MAs and 165 RCTs were appraised. High consistency existed in types of outcome domains listed as important in MAs. For 10/16 most frequently cited outcome domains, <50% of RCTs contributed data for meta-analyses. Low consistency in outcome definitions, measures, cut-points in RCTs and long-term follow-up prohibited data aggregation.

CONCLUSIONS

Variation in outcome measurement and long-term follow up has hampered the ability of RCTs to contribute data on important outcomes for CP, resulting in lost opportunities to measure the impact of maternal and neonatal interventions. There is an urgent need for and long-term follow up of these interventions and an agreed set of standardised and clinically relevant common data elements for study end-points.

Effect of High-Dose Cysteine Supplementation on Erythrocyte Glutathione: A Double-Blinded, Randomized Placebo-Controlled Pilot Study in Critically Ill Neonates

BACKGROUND

This study's objective was to determine if parenteral cysteine when compared with isonitrogenous noncysteine supplementation increases erythrocyte reduced glutathione (GSH) in neonates at high risk for inflammatory injury.

MATERIAL AND METHODS

Neonates with a score for neonatal acute physiology >10 requiring mechanical ventilation and parenteral nutrition (PN) were randomized in a double-blinded, placebo-controlled study to receive parenteral cysteine-HCl (CYS group) or additional PN amino acids (ISO group) at 121 mg/kg/d for ≥7 days. A 6-hour [(13)C2] glycine IV infusion was administered at study week 1 to determine the fractional synthetic rate of GSH (FSR-GSH).

RESULTS

Baseline characteristics were similar between the CYS (n = 17) and ISO groups (n = 21). Erythrocyte GSH and total glutathione concentrations, GSH:oxidized GSH (GSSG), and FSR-GSH after treatment were not different between groups. However, the CYS group had a larger individual positive change in GSH and total glutathione (infusion day - baseline) compared with the ISO group (P = .02 for each). After adjusting for treatment, a lower enrollment weight and rate of red blood cell transfusion were associated with a decreased change in total glutathione and GSH (P < .05 for each).

CONCLUSION

When compared with isonitrogenous noncysteine supplementation, high-dose cysteine supplementation for at least 1 week in critically ill neonates resulted in a larger and more positive individual change in GSH. Smaller infants and those who received transfused blood demonstrated less effective change in GSH with cysteine supplementation. The benefit of cysteine remains promising and deserves further investigation.

Intestinal mucosal defense system, Part 1. Consensus recommendations for immunonutrients

When microbial communities colonize in the developing intestinal tract after birth, microorganisms interact with specific apical surface receptors on the enterocytes. This interaction triggers a response that prevents overexpression of inflammatory cytokines, thus providing protection from pathogen-induced mucosal damage. Multiple immune modulatory factors in human milk and innate humoral factors also control inflammatory responses, providing additional protective effects. Our understanding of the role of the luminal microbial communities or microbiota is growing rapidly as novel technologies provide new insights into their taxonomy, function during early development, and impact on life-long health. Multiple studies have evaluated the effects of the specific nutrients, glutamine, arginine, nucleotides, polyunsaturated fatty acids, and lactoferrin, on disease outcomes in premature infants. These studies support a role for nutrients to modulate host defense mechanisms in premature infants, to develop normal digestive function, to protect from bacterial translocation, and to preserve mucosal barrier integrity. These effects are clearly important. However, not enough is yet known to design specific clinical care practices that support a healthy microbiota.

Glutamine randomized studies in early life: the unsolved riddle of experimental and clinical studies

Glutamine may have benefits during immaturity or critical illness in early life but its effects on outcome end hardpoints are controversial. Our aim was to review randomized studies on glutamine supplementation in pups, infants, and children examining whether glutamine affects outcome. Experimental work has proposed various mechanisms of glutamine action but none of the randomized studies in early life showed any effect on mortality and only a few showed some effect on inflammatory response, organ function, and a trend for infection control. Although apparently safe in animal models (pups), premature infants, and critically ill children, glutamine supplementation does not reduce mortality or late onset sepsis, and its routine use cannot be recommended in these sensitive populations. Large prospectively stratified trials are needed to better define the crucial interrelations of “glutamine-heat shock proteins-stress response” in critical illness and to identify the specific subgroups of premature neonates and critically ill infants or children who may have a greater need for glutamine and who may eventually benefit from its supplementation. The methodological problems noted in the reviewed randomized experimental and clinical trials should be seriously considered in any future well-designed large blinded randomized controlled trial involving glutamine supplementation in critical illness.

Randomized clinical trial of glutamine-supplemented versus standard parenteral nutrition in infants with surgical gastrointestinal disease

BACKGROUND

Addition of glutamine to parenteral nutrition in surgical infants remains controversial. The aim of this trial was to determine whether glutamine supplementation of parenteral nutrition in infants requiring surgery would reduce the time to full enteral feeding and/or decrease the incidence of sepsis and septicaemia.

METHODS

A prospective double-blind multicentre randomized clinical trial was performed in surgical infants less than 3 months old who required parenteral nutrition. Patients were allocated to treatment or control groups by means of minimization. Infants received either 0·6 g per kg per day alanyl-glutamine (treatment group) or isonitrogenous isocaloric parenteral nutrition (control group) until full enteral feeding was achieved. Primary outcomes were time to full enteral feeding and incidence of sepsis. Cox regression analysis was used to compare time to full enteral feeding, and to calculate risk of sepsis/septicaemia.

RESULTS

A total of 174 patients were randomized, of whom 164 completed the trial and were analysed (82 in each group). There was no difference in time to full enteral feeding or time to first enteral feeding between groups, and supplementation with glutamine had no effect on the overall incidence of sepsis or septicaemia. However, during total parenteral nutrition (before the first enteral feed), glutamine administration was associated with a significantly decreased risk of developing sepsis (hazard ratio 0·33, 95 per cent confidence interval 0·15 to 0·72; P = 0·005).

CONCLUSION

Glutamine supplementation during parenteral nutrition did not reduce the incidence of sepsis in surgical infants with gastrointestinal disease.

REGISTRATION NUMBER

ISRCTN83168963 (http://www.controlled-trials.com).

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine is a conditionally essential amino acid. Endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Evidence exists that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may also benefit preterm infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2011, Issue 4), MEDLINE, EMBASE and CINAHL (to November 2011), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors. We synthesised data using a fixed-effect model and reported typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

We identified 11 randomised controlled trials in which a total of 2771 preterm infants participated. Five trials assessed enteral glutamine supplementation and six trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality. Meta-analysis did not detect a statistically significant effect of glutamine supplementation on mortality [typical relative risk 0.98 (95% confidence interval 0.80 to 1.18); risk difference 0.00 (95% confidence interval -0.03 to 0.02)] or major neonatal morbidities including the incidence of invasive infection or necrotising enterocolitis. Two trials that assessed neurodevelopmental outcomes at 18 to 24 months did not find any statistically significant differences in various assessments.

AUTHORS' CONCLUSIONS

The available trial data do not provide evidence that glutamine supplementation confers important benefits for preterm infants.

Effects of neonatal enteral glutamine supplementation on cognitive, motor and behavioural outcomes in very preterm and/or very low birth weight children at school age

In very preterm ( < 32 weeks of gestation) and/or very low birth weight (VLBW, < 1500 g birth weight) children, serious neonatal infections are among the main causes of poor developmental outcomes later in childhood. The amino acid glutamine has been shown to reduce the incidence of serious neonatal infections in very preterm and/or VLBW children, while developmental effects beyond 24 months are unknown. We determined the cognitive, motor and behavioural outcomes at school age of a cohort of sixty-four very preterm and/or VLBW children (aged 7·5 (sd 0·4) years) who participated in a randomised placebo-controlled trial using enteral glutamine between day 3 and day 30 of life. Cognitive and motor outcomes were studied using the Wechsler Intelligence Scale for Children-III, the Movement Assessment Battery for Children (MABC), the Attention Network Test and a visual working memory task. Behavioural outcomes were evaluated using parent- and teacher-rated questionnaires. Intelligence quotient, processing speed, attentional functioning, working memory and parent- and teacher-rated behavioural outcomes were not different between children treated with glutamine or placebo; only visuomotor abilities as measured by the Ball Skills scale of the MABC (P = 0·002; d = 0·67) were poorer in the glutamine group. This effect persisted after taking into account the beneficial effects of lower serious neonatal infections rates in children treated with glutamine (P = 0·005). In conclusion, glutamine supplementation between day 3 and day 30 of life had neither beneficial nor detrimental effects on long-term cognitive, motor and behavioural outcomes of very preterm and/or VLBW children at school age, although visuomotor abilities were poorer in children that received glutamine.

Glutamine supplementation in sick children: is it beneficial?

The purpose of this review is to provide a critical appraisal of the literature on Glutamine (Gln) supplementation in various conditions or illnesses that affect children, from neonates to adolescents. First, a general overview of the proposed mechanisms for the beneficial effects of Gln is provided, and subsequently clinical studies are discussed. Despite safety, studies are conflicting, partly due to different effects of enteral and parenteral Gln supplementation. Further insufficient evidence is available on the benefits of Gln supplementation in pediatric patients. This includes premature infants, infants with gastrointestinal disease, children with Crohn's disease, short bowel syndrome, malnutrition/diarrhea, cancer, severe burns/trauma, Duchenne muscular dystrophy, sickle cell anemia, cystic fibrosis, and type 1 diabetes. Moreover, methodological issues have been noted in some studies. Further mechanistic data is needed along with large randomized controlled trials in select populations of sick children, who may eventually benefit from supplemental Gln.

The impact of oral glutamine supplementation on the intestinal permeability and incidence of necrotizing enterocolitis/septicemia in premature neonates

OBJECTIVE

To examine the impact of oral glutamine (Gln) supplementation on gut integrity and on the incidence of necrotizing enterocolitis (NEC)/septicemia of premature neonates.

METHODS

Preterm neonates (n = 101, gestational age <34 weeks, birth weight <2000 g) were randomly allocated to receive from day 3 to day 30 postpartum, either oral Gln (0.3 g/kg/day, n = 51-Gln group) or placebo (caloreen-isocaloric, n = 50-control group). Intestinal permeability was determined from the urinary lactulose/mannitol recovery (L/M ratio) following their oral administration and assessed at three time points: day 2 (before first administration), day 7 and day 30 of life. The incidence of NEC and septicemia over the study period was also recorded.

RESULTS

A decrease of lactulose recovery at days 7 (p = 0.001) and 30 (p < 0.001) and a decrease of L/M ratio at day 7 (p = 0.002) were observed only in the Gln group. Lactulose recovery and L/M ratio at day 7 (p = 0.022 and p = 0.004, respectively), as well as lactulose recovery (p = 0.001), mannitol recovery (p = 0.042), and L/M ratio (p = 0.001) at day 30, were decreased in the Gln group as compared to controls. NEC and septicemia were lower in the Gln group at the end of the first week (p = 0.009 and p = 0.041, respectively) and up to the end of the study (p < 0.001 and p = 0.048, respectively).

CONCLUSION

Oral Gln administration may have beneficial effects on intestinal integrity and the overall incidence of NEC/septicemia in preterm infants.

Glutamine-enriched enteral nutrition in very low birthweight infants and allergic and infectious diseases at 6 years of age

In a previous randomised controlled trial, we found that glutamine-enriched enteral nutrition in 102 very low birthweight (VLBW) infants decreased both the incidence of serious infections in the neonatal period and the risk of atopic dermatitis during the first year of life. We hypothesised that glutamine-enriched enteral nutrition in VLBW infants in the neonatal period influences the risk of allergic and infectious disease at 6 years of age. Eighty-eight of the 102 infants were eligible for the follow-up study (13 died, 1 chromosomal abnormality). Doctor-diagnosed allergic and infectious diseases were assessed by means of validated questionnaires. The association between glutamine-enriched enteral nutrition in the neonatal period and allergic and infectious diseases at 6 years of age was based on univariable and multivariable logistic regression analyses. Seventy-six of the 89 (85%) infants participated, 38 in the original glutamine-supplemented group and 38 in the control group. After adjustment, we found a decreased risk of atopic dermatitis in the glutamine-supplemented group: adjusted odds ratio (aOR) 0.23 [95% CI 0.06, 0.95]. No association between glutamine supplementation and hay fever, recurrent wheeze and asthma was found. A decreased risk of gastrointestinal tract infections was found in the glutamine-supplemented group (aOR) 0.10 [95% CI 0.01, 0.93], but there was no association with upper respiratory, lower respiratory or urinary tract infections. We concluded that glutamine-enriched enteral nutrition in the neonatal period in VLBW infants decreased the risk of atopic dermatitis and gastrointestinal tract infections at 6 years of age.

Necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains a major cause of neonatal morbidity and death. The pathophysiology is poorly understood. Prevailing evidence suggests that NEC is due to an inappropriate inflammatory response of the immature gut to some undefined insult. The mortality rate (15%-25%) for affected infants has not changed appreciably in 30 years. Many infants with NEC recover uneventfully with medical therapy and have long-term outcomes similar to unaffected infants of matched gestational age. Infants with progressive disease requiring surgical intervention suffer almost all of the mortality and morbidity. Of these, approximately 30%-40% will die of their disease and most of the remainder will develop long-term neurodevelopmental and gastrointestinal morbidity. Recent randomized trials suggest that the choice of operation does not influence patient outcome. Current work is focusing on developing a better understanding of the pathogenesis and improving means to identify which infants are at greatest risk of disease progression.

Cytokine profiles in 1-yr-old very low-birth-weight infants after enteral glutamine supplementation in the neonatal period

In a previous study, we found that glutamine-enriched enteral nutrition in 102 very low-birth-weight (VLBW) infants decreased both the incidence of serious neonatal infections and atopic dermatitis during the first year of life. The aims of this follow-up study were to determine whether these beneficial effects are attended by changes in Th(1) and Th(2) cytokine profiles at age 1 yr. Furthermore, we studied changes in cytokine profiles during the first year of life in these VLBW infants. In total, 89 infants were eligible for the follow-up study (12 died, 1 exclusion due to a chromosomal abnormality). Th(1) (IFN-gamma, TNF- alpha and IL-2) and Th(2) cytokine (IL-10, IL-5, and IL-4) profiles following in vitro whole blood stimulation were measured at 1 yr. Cytokine profiles were measured in 59/89 (66%) infants. Glutamine-enriched enteral nutrition in neonatal period did not influence cytokine profiles at 1 yr. Cytokine profiles were not different in infants with and without allergic or infectious diseases. The beneficial effect of glutamine-enriched enteral nutrition on the incidence of serious neonatal infections and atopic dermatitis during the first year of life is not related to changes in the Th(1) and Th(2) cytokine profiles. Both Th(1) and Th(2) cytokine profiles increased during the first year of life in this cohort of VLBW infants.

Prevention of necrotising enterocolitis: Year 2004 and beyond

The incidence of necrotising enterocolitis (NEC) has not changed significantly despite the dramatic advances in perinatal-neonatal care. The absolute number of survivors of NEC is expected to rise, as prevention of prematurity, the single most important risk factor for the illness, continues to be difficult. Prevention of NEC has thus become an area of research priority. Given the role of inflammatory mediators in its pathogenesis newer immune modulators are being studied as potential agents for prevention/treatment of NEC. Caution, however, is warranted because the failure of sepsis trials in adults has clearly indicated that the concept of down-regulating the inflammatory response is deceptively simple. Clinical trials of any such promising preventative agent(s) need to be designed carefully and must include long-term neurodevelopmental outcomes as almost an entire population of high-risk preterm neonates will be exposed to their adverse effects. As new frontiers continue to be explored, the proven benefits of simple and safe interventions like antenatal glucocorticoid therapy and the preferential use of breast milk for feeding high-risk neonates must not be forgotten. Given that a single effective agent is unlikely in the near future, utilizing a package of "potentially better practices" seems to be the most appropriate strategy to prevent and minimize NEC.

Potential of immunomodulatory agents for prevention and treatment of neonatal sepsis

Prevention of neonatal infection-related mortality represents a significant global challenge particularly in the vulnerable premature population. The increased risk of death from sepsis is likely due to the specific immune deficits found in the neonate as compared to the adult. Stimulation of the neonatal immune system to prevent and/or treat infection has been attempted in the past largely without success. In this review, we identify some of the known deficits in the neonatal immune system and their clinical impact, summarize previous attempts at immunomodulation and the outcomes of these interventions, and discuss the potential of novel immunomodulatory therapies to improve neonatal sepsis outcome.

Cytokine responses in very low birth weight infants receiving glutamine-enriched enteral nutrition

OBJECTIVE

Very low birth weight (VLBW) infants receiving glutamine-enriched enteral nutrition may present with a lower infection rate, which may result from enhanced antimicrobial innate or Th1 cytokine responses. We investigated whether glutamine-enriched enteral nutrition in VLBW infants increased these cytokine responses following in vitro stimulation of whole blood cells.

METHODS

In a double-blind, placebo-controlled, randomized controlled trial, VLBW infants (gestational age <32 weeks and/or birth weight <1500 g) received enteral glutamine supplementation (0.3 g x kg(-1) x day(-1)) or isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Cytokine responses following in vitro whole blood cell stimulation with anti-(alpha)CD3/alphaCD28 or lipopolysaccharide were analyzed by cytometric bead array at 3 time points: before the start of the study, at day 7 of life, and at day 14 of life.

RESULTS

Baseline patient and nutritional characteristics were not different between groups. At least 2 blood samples were analyzed in 25 of 52 (48%) and 38 of 50 (76%) infants in the glutamine-supplemented and control groups, respectively. Glutamine-enriched enteral nutrition was not associated with significant alterations in cytokine responses (interferon-gamma, tumor necrosis factor-alpha, interleukin [IL]-2, IL-4, IL-5, and IL-10) of peripheral blood cells upon stimulation with either anti-alphaCD3/alphaCD28 or lipopolysaccharide.

CONCLUSIONS

We hypothesize that glutamine-enriched enteral nutrition decreases the infection rate in VLBW infants by influencing the mucosal and not the systemic immune system.

Metabolism and nutrition in the surgical neonate

Considerable improvements have been achieved in pediatric surgery during the last two decades: the mortality rate of neonates undergoing major operations has declined to less than 10%, and the morbidity of major operations has become negligible. This considerable improvement can be partly ascribed to a better understanding of the physiological changes that occur after an operation and to more appropriate management and nutrition of the critically ill and "stressed" neonates and children. The metabolic response to an operation is different in neonates from adults: there is a small increase in oxygen consumption and resting energy expenditure immediately after surgery with return to normal by 12-24 hours. The increase in resting energy expenditure is significantly greater in infants having a major operation than in those having a minor procedure. The limited increase in energy expenditure may be due to diversion of energy from growth to tissue repair. During parenteral nutrition, it is not advisable to administer more than 18 g/kg/day of carbohydrate because this intake will be associated with lipogenesis, increased CO(2) production, and increased free radical-mediated lipid peroxide formation. Glutamine intake is potentially beneficial during total parenteral nutrition, although a large, randomized, controlled trial in surgical neonates requiring parenteral nutrition is needed to provide evidence for its benefit.

Protein and amino acid metabolism in the human newborn

Birth and adaptation to extrauterine life involve major shifts in the protein and energy metabolism of the human newborn. These include a shift from a state of continuous supply of nutrients including amino acids from the mother to cyclic periodic oral intake, a change in the redox state of organs, thermogenesis, and a significant change in the mobilization and use of oxidative substrates. The development of safe, stable isotopic tracer methods has allowed the study of protein and amino acid metabolism not only in the healthy newborn but also in those born prematurely and of low birth weight. These studies have identified the unique and quantitative aspects of amino acid/protein metabolism in the neonate, thus contributing to rational nutritional care of these babies. The present review summarizes the contemporary data on some of the significant developments in essential and dispensable amino acids and their relationship to overall protein metabolism. Specifically, the recent data of kinetics of leucine, phenylalanine, glutamine, sulfur amino acid, and threonine and their relation to whole-body protein turnover are presented. Finally, the physiological rationale and the impact of nutrient (amino acids) interventions on the dynamics of protein metabolism are discussed.

Neurodevelopmental outcomes of very low-birth-weight infants after enteral glutamine supplementation in the neonatal period

AIM

To determine the effect of neonatal glutamine-enriched enteral nutrition in very low birth weight (VLBW) infants on neurodevelopmental outcome at 2 years of age.

METHODS

Eighty-eight out of one hundred two infants participating in the initial study were eligible for the follow-up study (13 died, one exclusion due to a chromosomal abnormality). Neurodevelopmental outcome (neurologic status, vision, hearing and Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) of the Bayley Scales of Infant Development II) was evaluated at the corrected age of 2 years. To adjust for potential confounders, data were analyzed by multiple linear or logistic regression (for continuous and dichotomous variables, respectively)

RESULTS

Seventy-two out of eighty-eight (82%) infants participated in the follow-up study: 40 and 32 infants in glutamine-supplemented and control groups, respectively. The incidence of neither an MDI nor a PDI <or= 85 was different in glutamine-supplemented and control groups (MDI <or= 85: 27 and 19%, p = 0.17; PDI <or= 85: 28 and 16% p = 0.16, respectively). The incidence of neurodevelopmental impairment was not different between both groups (OR: 2.16, 95% CI: 0.64-7.28).

CONCLUSIONS

A positive effect of neonatal glutamine-enriched enteral nutrition in VLBW infants on neurodevelopmental outcome at 2 years of age was not found in this study.

Necrotizing enterocolitis: recent scientific advances in pathophysiology and prevention

Necrotizing enterocolitis (NEC) is a leading cause of morbidity and mortality among infants in the neonatal intensive care unit. Here we review the epidemiology and pathophysiology of NEC, with an emphasis on the latest research findings and potential areas for future research. NEC continues to be one of the most devastating and unpredictable diseases affecting premature infants. Despite decades of research, the pathogenesis of this disease remains unclear, and prevention and treatment strategies are limited. Hopefully, future studies aimed at understanding premature intestinal defenses, commensal or probiotic bacterial influences, and possible genetic predisposition will lead to the improvement of prevention and treatment strategies.

Glutamine supplementation to prevent morbidity and mortality in preterm infants

BACKGROUND

Glutamine endogenous biosynthesis may be insufficient for tissue needs in states of metabolic stress. Trials in adults have suggested that glutamine supplementation improves clinical outcomes in critically ill adults. It has been suggested that glutamine supplementation may benefit preterm infants, particularly very low birth weight infants.

OBJECTIVES

To determine the effects of glutamine supplementation on mortality and morbidity in preterm infants.

SEARCH STRATEGY

The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2007), MEDLINE (1966 - July 2007), EMBASE (1980 - July 2007), conference proceedings, and previous reviews.

SELECTION CRITERIA

Randomised or quasi-randomised controlled trials that compared glutamine supplementation versus no glutamine supplementation in preterm infants at any time from birth to discharge from hospital.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group were used, with separate evaluation of trial quality and data extraction by two authors. Data were synthesised using a fixed effects model and reported using typical relative risk, typical risk difference and weighted mean difference.

MAIN RESULTS

2365 preterm infants have participated in seven randomised controlled trials. All of the participating infants were of very low birth weight. Three trials assessed enteral glutamine supplementation and four trials assessed parenteral glutamine supplementation. The trials were generally of good methodological quality with adequate allocation concealment, blinding of caregivers and assessors to the intervention, and complete or near-complete follow-up of recruited infants. Glutamine supplementation does not have a statistically significant effect on mortality: typical relative risk 0.98 (95% confidence interval 0.80 to 1.20); typical risk difference 0.00 (95% confidence interval -0.03 to 0.02). The only trial that assessed long-term outcomes did not find any statistically significant differences in various assessments of neurodevelopment at 18 months corrected age. Glutamine supplementation does not have a statistically significant effect on other neonatal morbidities including invasive infection, necrotising enterocolitis, time to achieve full enteral nutrition, or duration of hospital stay.

AUTHORS' CONCLUSIONS

The available data from good quality randomised controlled trials indicate that glutamine supplementation does not confer benefits for preterm infants. The narrow confidence intervals for the effect size estimates suggest that a further trial of this intervention is not a research priority.

Gastrointestinal maturation and implications for infant feeding

The level of gastrointestinal (GI) maturity of an individual infant is a major determinant of whether the infant will be able to meet nutritional needs by sole use of the GI tract or if parenteral means will be necessary. The GI tract is not only an organ for digestion and absorption of nutrients; it also performs major endocrine, neural and immunologic functions. In this review, anatomic, functional and biochemical development will be described and related to means by which enteral nutrition can be used in the prematurely born infant to optimize health and prevent disease.

The effect of glutamine-enriched enteral nutrition on intestinal microflora in very low birth weight infants: A randomized controlled trial

BACKGROUND & AIMS

In a previous study, we have found that glutamine supplementation decreased the infection rate in very low birth weight (VLBW) infants. In this study, we investigated whether this beneficial effect originated from increased number of bifidobacteria and lactobacilli in the intestinal microflora of these infants.

METHODS

In a randomized controlled trial, VLBW infants (gestational age <32 weeks and/or birth weight <1500g) received enteral glutamine supplementation (0.3g/kg/day) or isonitrogenous placebo supplementation between d3 and d30 of life. Faecal microflora was determined by fluorescent in situ hybridization <48h, at d7, d14 and d30 of life.

RESULTS

In 43/52 (glutamine group) and 43/50 (control group) infants, > or = 2 samples were analyzed. Baseline characteristics were not different between groups. The prevalence of bifidobacteria, lactobacilli, Escheria coIi, streptococci and clostridia was not different between groups (p>0.05). In both groups, colonization with bifidobacteria was delayed, whereas potentially pathogenic bacteria such as E. coli, appeared rapidly after birth. Antibiotic treatment decreased the prevalence of all faecal bacteria (p<0.05).

CONCLUSIONS

Decreased infectious morbidity in VLBW infants that received glutamine supplementation was not associated with alterations in the prevalence of bifidobacteria, lactobacilli, E. coIi, streptococci and clostridia. In general, colonization with health-promoting bacteria was delayed, whereas potentially pathogenic bacteria appeared rapidly after birth. Antibiotic treatment delayed the bacterial colonization.

Glutamine supplementation in the newborn infant

Glutamine is a non-essential amino acid that can be synthesized de novo from glutamate. This synthesis can be increased by intravenous infusion of carbon precursors (alpha-ketoglutarate or amino acids) in adults and in infants. The metabolism of glutamine is highly compartmentalized between the splanchnic tissues and the periphery, so that orally administered glutamine is completely metabolized in the splanchnic compartment. Data from studies in adults and children show that plasma levels of glutamine decline during acute stress and illness. Because of its importance in several physiological functions (the demonstrated benefits of supplemental glutamine in adult burns and trauma patients and the inhibitory effect on proteolysis in the skeletal muscle in vitro), it has been suggested that during 'acute stress' the demands of glutamine outweigh its de novo synthesis, resulting in a fall in plasma glutamine levels. As a consequence, glutamine has been considered a 'conditionally essential' amino acid. Because of its instability in solution, glutamine is not routinely added to the parenteral amino acid mixtures. A number of clinical trials of parenteral and enteral supplementation of glutamine have been performed. The outcome measures examined have varied between acute effects and long-term complex clinical events such as mortality and risk of infections. Although acute studies in LBW babies have shown some beneficial effects such as changes in protein metabolism and activation of immune system, these have not been translated into prolonged advantages such as reduction in mortality or in nosocomial infection. The reasons for these differences are discussed.

Necrotizing enterocolitis: a practical guide to its prevention and management

Neonatal necrotizing enterocolitis is the second most common cause of morbidity in premature infants and requires intensive care over an extended period. Despite advances in medical and surgical techniques, the mortality and long-term morbidity due to necrotizing enterocolitis remain very high. Recent advances have shifted the attention of researchers from the classic triad (ischemia, bacteria, and the introduction of a metabolic substrate into the intestine) of necrotizing enterocolitis, to gut maturation, feeding practices, and inflammation. The focus on inflammation includes proinflammatory cytokines such as tumor necrosis factor-alpha, interleukin (IL)-6, IL-18, and platelet-activating factor. Research related to the etiology of necrotizing enterocolitis has moved quickly from clostridial toxin to bacterial and other infectious agents. More recently, the pattern of bacterial colonization has been given emphasis rather than the particular species or strain of bacteria or their virulence. Gram-negative bacteria that form part of the normal flora are now speculated as important factors in triggering the injury process in a setting where there is a severe paucity of bacterial species and possible lack of protective Gram-positive organisms. Although the incidence of necrotizing enterocolitis has increased because of the survival of low birthweight infants, clinicians are more vigilant in their detection of the early gastrointestinal symptoms of necrotizing enterocolitis; however, radiographic demonstration of pneumatosis intestinalis remains the hallmark of necrotizing enterocolitis. With prompt diagnosis, a large proportion of infants with necrotizing enterocolitis are now able to be managed medically with intravenous fluid and nutrition, nasogastric suction, antibacterials, and close monitoring of physiologic parameters. In the advanced cases that require surgery, clinicians tend to opt for either simple peritoneal drainage (for very small and sick infants) or laparotomy and resection of the affected part. Intestinal transplantation later in life is available as a viable option for those who undergo resection of large segments of the intestine. It is becoming more evident that treatment of this devastating disease is expensive and comes with the toll of significant long-term sequelae. This has resulted in renewed interest in designing alternative strategies to prevent this serious gastrointestinal disease. Simple trophic feeding and the use of L-glutamine and arginine are novel avenues that have been examined. The use of probiotics ('friendly' bacterial flora) has been introduced as a promising tool for establishing healthy bacterial flora in the newborn gut to block the injury process that may ultimately lead to necrotizing enterocolitis.

Pathophysiology of glutamine and glutamate metabolism in premature infants

PURPOSE OF REVIEW

The potential efficacy of glutamine and glutamate as nutritional supplements for premature infants was originally met with enthusiasm. Despite no evidence of toxicity in the clinical trials, the use of glutamine has not become routine. In certain studies, the benefits seem clear, whereas in others, benefits have not been demonstrated. Specific designs for studies have been difficult, targets based on mechanistic frameworks have been poorly defined, study populations are heterogeneous and putative mechanisms of glutamine action are multifold. Our purpose is to review recent findings pertaining to (1) the action and mechanisms of glutamine and glutamate in the gastrointestinal tract, and (2) the future directions for glutamine and glutamate research with a focus on the premature neonate.

RECENT FINDINGS

Studies elucidating mechanisms of glutamine action include tissue protection, immune modulation, preservation of glutathione and antioxidant capacity, preservation of metabolism, decreased intestinal apoptosis, and enhancement of heat shock proteins. The ability to decrease gastrointestinal-derived systemic inflammation appears to have especially significant implications for premature infants.

SUMMARY

We review recent studies of mechanisms of glutamine and glutamate action, pertinent clinical trials, and suggest areas for future research based on these mechanisms.

Immunomodulation. Part IV: Glutamine

Glutamine, a nonessential amino acid that appears to be conditionally essential during periods of physiologic stress, plays important physiologic roles in the immune system. However, neither enteral nor parenteral glutamine supplementation makes a difference in the rate of systemic infection or of NEC in very low birth weight infants. Thus, the search for agents to enhance the neonate's immune system and to serve as safe and effective adjuvants to antibiotics continues. Part V, the final article in this immunomodulation series, will explore the use of probiotics to support the neonatal immune system.

The effect of glutamine-enriched enteral nutrition on intestinal permeability in very-low-birth-weight infants: a randomized controlled trial

BACKGROUND

Very-low-birth-weight (VLBW) infants are susceptible to glutamine depletion. Glutamine depletion has negative effects on intestinal integrity. The lower infection rate in VLBW infants receiving glutamine-enriched enteral nutrition may originate from improved intestinal integrity, as reflected by decreased intestinal permeability. The aim of our study was to investigate whether glutamine-enriched enteral nutrition in VLBW infants enhances the normal decrease in intestinal permeability, as measured by the sugar absorption test (SAT).

METHODS

In a double-blind, randomized, placebo-controlled trial, VLBW infants (gestational age <32 weeks or birth weight <1,500 g) received enteral glutamine supplementation (0.3 g/kg/d) or an isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Intestinal permeability, determined from the urinary lactulose/mannitol (L/M) ratio after an oral dose of lactulose and mannitol, was assessed at 4 time points: before the start of the study, and at days 7, 14, and 30 of life.

RESULTS

At least 2 SATs were performed in 45/52 (86%) and 45/50 (90%) infants in the glutamine-supplemented and control groups, respectively. Baseline patient and nutrition characteristics were not different between the groups. There was no effect of glutamine-enriched enteral nutrition on the decrease of the L/M ratio between the start and end of the study (p = .78). In both treatment groups, median urinary lactulose concentrations decreased (p < .001), whereas median urinary mannitol concentrations increased (p = .003).

CONCLUSIONS

Glutamine-enriched enteral nutrition does not enhance the postnatal decrease in intestinal permeability in VLBW infants. Any beneficial effect of glutamine may involve other aspects of intestinal integrity; for example, modulation of the intestinal inflammatory response.

The effect of glutamine-supplemented total parenteral nutrition on nutrition and intestinal absorptive function in a rat model

The aim of the present study was to evaluate the effect of short-term (7 days) glycyl-glutamine-supplemented total parenteral nutrition (TPN) on nutrition and intestinal absorptive function in a rat model. Thirty Wistar rats, weighting 140-180 g, were divided into three groups (n=10) randomly. The animals received isonitrogenous and isocaloric TPN solutions for 7 days. The nitrogen was supplied by glycyl-glutamine dipeptide-supplemented amino acid solution (group G), and two standard amino acid solutions (group V, group N), respectively. Body weight, plasma glutamine level, nitrogen balance, total tissue water and intestinal absorptive function, assessed by (15-N)-glycine absorption, were investigated. Body weight decreased in three groups at the end of TPN; there was no significant difference in relative body-weight changes. There was a significant improvement of cumulative nitrogen balance and nitrogen retention in group G compared to other groups (P<0.05). There was no significant difference in intestinal glycine absorption (P>0.05) among the three groups. Total tissue water of left thigh muscle was significantly higher in group V and group N than that in group G (P<0.05). The results indicated that short-term (7 days) TPN supplemented with glycyl-glutamine improved plasma glutamine level and nitrogen balance, decreased water content of muscle, but had no beneficial effect on absorptive function in a rat model.

Effect of intravenous amino acids on glutamine and protein kinetics in low-birth-weight preterm infants during the immediate neonatal period

Glutamine may be a conditionally essential amino acid in low-birth-weight (LBW) preterm neonates. Exogenously administered amino acids, by providing anaplerotic carbon into the tricarboxylic acid cycle, could result in greater cataplerotic efflux and glutamine de novo synthesis. The effect of dose and duration of amino acid infusion on glutamine and nitrogen (N) kinetics was examined in LBW infants in the period immediately after birth. Preterm neonates (<32 weeks gestation, birth weights 809-1,755 g) were randomized to initially receive either 480 or 960 micromol x kg(-1) x h(-1) of an intravenous amino acid solution for 19-24 hours, followed by a higher or lower amino acid load for either 5 h or 24 h. Glutamine de novo synthesis, leucine N, phenylalanine, and urea kinetics were determined using stable isotopic tracers. An increase in amino acid infusion from 480 to 960 micromol x kg(-1) x h(-1) for 5 h resulted in decreased glutamine de novo synthesis in every neonate (384.4 +/- 38.0 to 368.9 +/- 38.2 micromol x kg(-1) x h(-1), P < 0.01) and a lower whole body rate of proteolysis (P < 0.001) and urea synthesis (P < 0.001). However, when the increased amino acid infusion was extended for 24 h, glutamine de novo synthesis increased (369.7 +/- 92.6 to 483.4 +/- 97.5 micromol x kg(-1) x h(-1), P < 0.001), whole body rate of proteolysis did not change, and urea production increased. Decreasing the amino acid load resulted in a decrease in glutamine rate of appearance (R(a)) and leucine N R(a), but had no effect on phenylalanine R(a). Acutely stressed LBW infants responded to an increase in amino acid load by transiently suppressing whole body rate of glutamine synthesis, proteolysis, and oxidation of protein. The mechanisms of this transient effect on whole body protein/nitrogen metabolism remain unknown.

Surgical injury and metabolic stress enhance the virulence of the human opportunistic pathogen Pseudomonas aeruginosa

BACKGROUND

We have shown previously that the PA-I lectin of Pseudomonas aeruginosa plays a key role in gut-derived sepsis during surgical stress. The aims of this study were to determine if the intestinal tract lumen of a stressed host contained soluble factors that could induce the expression of PA-I.

METHODS

Mice were subjected to either 30% surgical hepatectomy or sham-laparotomy, and P. aeruginosa was introduced into the cecum. Twenty-four hours later, feces were recovered, and PA-I and exotoxin A were determined by real-time polymerase chain reaction (PCR). In reiterative experiments, fecal filtrates from both hepatectomy and sham-operated mice were tested for their ability to induce PA-I expression in cultures of P. aeruginosa. Finally, the media from cultured human intestinal epithelial (Caco-2) cells stressed with excess glutamine was tested for its ability to induce the expression of PA-I in cultures of P. aeruginosa.

RESULTS

Both PA-I and exotoxin A mRNA were increased in vivo in the intestinal tract of mice subjected to 30% hepatectomy. Soluble fecal filtrates from hepatectomy mice induced PA-I in vitro. Media from epithelial cells exposed to excess glutamine alone induced PA-I expression.

CONCLUSIONS

The intestinal environment of a stressed host contains soluble factors capable of inducing lethal virulence traits in human opportunistic pathogen P. aeruginosa.

Glutamine-enriched enteral nutrition in very-low-birth-weight infants and effects on feeding tolerance and infectious morbidity: a randomized controlled trial

BACKGROUND

Glutamine depletion has negative effects on the functional integrity of the gut and leads to immunosuppression. Very-low-birth-weight (VLBW) infants are susceptible to glutamine depletion because nutrition is limited in the first weeks of life.

OBJECTIVE

The objective was to determine the effect of glutamine-enriched enteral nutrition on feeding tolerance, infectious morbidity, and short-term outcome in VLBW infants.

DESIGN

In a double-blind randomized controlled trial, VLBW infants (gestational age <32 wk or birth weight <1500 g) were allocated to receive enteral glutamine supplementation (0.3 g . kg(-1) . d(-1)) or isonitrogenous control supplementation (alanine) between days 3 and 30 of life. The supplementations were added to breast milk or to preterm formula. The primary endpoint for the study was time to full enteral feeding. Secondary endpoints were other variables of feeding tolerance, infectious morbidity, and short-term outcome.

RESULTS

Baseline patient and nutritional characteristics were not significantly different in the glutamine-supplemented (n = 52) and the control (n = 50) groups. The median time to full enteral feeding was 13 d (range: 7-31 d) in the glutamine-supplemented group and 13 d (range: 6-35 d) in the control group (hazard ratio: 1.19; 95% CI: 0.79, 1.79; P = 0.40). In the glutamine-supplemented group, 26 of 52 infants (50%) had >/=1 serious infection compared with 38 of 50 (76%) in the control group (odds ratio: 0.32; 95% CI: 0.14, 0.74; P = 0.008). Other variables of feeding tolerance and short-term outcome were not significantly different between groups.

CONCLUSIONS

Glutamine-enriched enteral nutrition did not improve feeding tolerance or short-term outcome in VLBW infants. However, infectious morbidity was significantly lowered in infants who received glutamine-enriched enteral nutrition.

Reducing the global burden of sepsis in infants and children: a clinical practice research agenda

OBJECTIVE

Sepsis remains a predominant cause of mortality and morbidity in children in the developing and industrialized world. This review discusses a clinical practice research agenda to reduce this global burden.

DESIGN

Summary of the literature with analysis by experts.

RESULTS

Many interventions have been proven effective in decreasing sepsis. Heterologous immunization with attenuated Bacillus Camille Guerin vaccine reduces all-cause mortality, and specific immunizations further reduce morbidity and mortality from many specific microbes. Antepartum antibiotics reduce the prevalence of cerebral palsy and mortality in infants. Administration of antibiotics to neonates with signs of sepsis reduces all-cause mortality five-fold and can also reduce mortality in the big four killers of children: severe pneumonia, diarrhea, malaria, or measles. Immunonutrition with zinc and vitamin A can further reduce morbidity in diarrhea and pneumonia and reduce mortality in measles. First-hour rapid intravenous fluid resuscitation achieves 100% survival in dengue shock, and time-sensitive fluid resuscitation and inotropic support reduces mortality ten-fold in meningococcal septic shock. Multiple organ failure occurs when late or inadequate resuscitation results in systemic thrombosis or when infection is not eradicated because of immunosuppression or inadequate source control.

CONCLUSIONS

The global burden of sepsis can be reduced by 1) prevention with improved heterologous or specific vaccines and vitamin or mineral supplement programs; 2) early recognition and treatment with appropriate antibiotics, intravenous fluid resuscitation, and inotropic support in organized healthcare-delivery systems; and 3) development of new diagnostics and therapeutics that reduce systemic thrombosis, improve immune function, and kill resistant organisms.

Feeding strategies and necrotizing enterocolitis

PURPOSE OF REVIEW

To update clinical trials concerning feeding strategies or feeding interventions to prevent necrotizing enterocolitis (NEC).

RECENT FINDINGS

The overall incidence of NEC remains unchanged. Several studies have shown that it is safe to use small feeding volumes early in life even in selected circumstances, such as feeding during the use of indomethacin to treat symptomatic patent ductus arteriosus. Although descriptive case reports have linked some feeding interventions such as thickened feedings to NEC, there is no evidence to establish a causal relation. Interestingly, one report showed that neither the presence of-nor characteristics of-gastric residuals was helpful to identify those infants who subsequently develop NEC. Numerous studies in animals show that vascular and host defense responses are not adequate in the immature gut. A few small clinical trials showed that various feeding strategies may alter these responses in preterm infants. However, larger clinical trials around these issues await further characterization of the mechanisms that regulate these two aspects of gastrointestinal function with respect to feeding.

SUMMARY

Studies continue to demonstrate how fragile the immature gut is, but further work directed to understanding the mechanisms that regulate gastrointestinal responses to feeding is needed to design meaningful interventions for large prospective trials.

Glutamine supplementation of parenteral nutrition does not improve intestinal permeability, nitrogen balance, or outcome in newborns and infants undergoing digestive-tract surgery: results from a double-blind, randomized, controlled trial

OBJECTIVE

To assess the effect of isocaloric isonitrogenous parenteral glutamine supplementation on intestinal permeability and nitrogen loss in newborns and infants after major digestive-tract surgery.

SUMMARY BACKGROUND DATA

Glutamine supplementation in critically ill and surgical adults may normalize intestinal permeability, attenuate nitrogen loss, improve survival, and lower the incidence of nosocomial infections. Previous studies in critically ill children were limited to very-low-birthweight infants and had equivocal results.

METHODS

Eighty newborns and infants were included in a double-blind, randomized trial comparing standard parenteral nutrition (sPN; n = 39) to glutamine-supplemented parenteral nutrition (GlnPN; glutamine target intake, 0.4 g kg day; n = 41), starting on day 2 after major digestive-tract surgery. Primary endpoints were intestinal permeability, as assessed by the urinary excretion ratio of lactulose and rhamnose (weeks 1 through 4); nitrogen balance (days 4 through 6), and urinary 3-methylhistidine excretion (day 5). Secondary endpoints were mortality, length of stay in the ICU and the hospital, number of septic episodes, and usage of antibiotics and ICU resources.

RESULTS

Glutamine intake plateaued at 90% of the target on day 4. No differences were found between patients assigned sPN and patients assigned GlnPN regarding any of the endpoints. Glutamine supplementation was not associated with adverse effects.

CONCLUSIONS

In newborns and infants after major digestive-tract surgery, we did not identify beneficial effects of isonitrogenous, isocaloric glutamine supplementation of parenteral nutrition. Glutamine supplementation in these patients therefore is not warranted until further research proves otherwise.

A suplementação de glutamina é benéfica em crianças com doenças graves?

Embora haja vários estudos clínicos randômicos avaliando os benefícios da suplementação de glutamina em pacientes adultos, há pouca informação em pacientes pediátricos, particularmente naqueles com doenças graves. O objetivo deste estudo foi avaliar criticamente os estudos sobre suplementação de glutamina, para verificar os possíveis benefícios clínicos desta suplementação em crianças gravemente doentes. Levou-se a cabo uma pesquisa dos estudos publicados entre 1992 e 2003, do tipo prospectivo, randômico e controlado, conduzidos em pacientes pediátricos gravemente doentes, divididos em dois grupos: o dos que receberam suplementos de glutamina por via enteral ou parenteral, e o dos que receberam placebo. As variáveis de desfecho foram: tempo para atingir oferta plena de dieta enteral, tempo de hospitalização, complicações e mortalidade. Foram utilizadas as bases de dados Medline, LILACS e Cochrane, com as palavras-chave: glutamine, critically ill, trauma, sepsis, burned, injured, bone marrow transplantation, intensive care, mechanical ventilation. Dos 33 estudos inicialmente identificados, 7 preencheram os critérios de inclusão. A análise dos resultados mostrou que nos pacientes suplementados com glutamina, houve melhor aceitação por via enteral e redução do tempo de nutrição parenteral em recém-nascidos, não havendo efeito sobre o tempo de internação, custos hospitalares e mortalidade. Os estudos controlados na faixa etária pediátrica, não permitem que se adote o uso rotineiro da glutamina em crianças gravemente enfermas. O número reduzido de pacientes e a heterogeneidade quanto ao grupo etário, doenças e via de administração são fatores que limitam a interpretação dos resultados.

Glutamine modulates LPS-induced IL-8 production through IkappaB/NF-kappaB in human fetal and adult intestinal epithelium

The intestinal epithelium may serve as a nidus for inflammation that can cause local and systemic organ dysfunction. Relative to the adult, the immature intestine is exquisitely sensitive to inflammatory agents. Glutamine (Gln), an amino acid that is rapidly depleted during critical illness, modulates intestinal inflammation in vitro and in vivo. Here we relate Gln status to activation of the inhibitor of kappaB (IkappaB)/nuclear factor (NF)-kappaB signaling pathway in fetal-derived (H4) and adult (Caco-2) enterocytes. In the absence of Gln with or without LPS, H4 cells expressed more interleukin (IL)-8) than Caco-2 cells. Gln supplementation partially prevented the LPS-induced elevation of IL-8 in both cell types. IkappaBalpha was significantly decreased in both H4 and Caco-2 cells with Gln deprivation, and this was followed by an increase in NF-kappaB p65 in the nucleus. DNA binding of NF-kappaB was increased in both H4 and Caco-2 cells with Gln deprivation. IkappaBalpha phosphorylation was not altered by Gln status in either H4 or Caco-2 cells. Proteasomal inhibition after Gln depletion in Caco-2 cells was associated with an increase in the IkappaB-ubiquitin complex, but a decrease in complex formation in H4 cells, indicating that Gln deprivation alters IkappaBalpha through a pathway that differs from Caco-2 cells. We speculate that a reduced capacity of the immature enterocyte (H4) to respond to Gln deprivation with increased synthesis of IkappaBalpha rather than increased proteolysis as seen in the Caco-2 cells is the underlying mechanism.