Bactericidal power of neutrophils in protein calorie malnutrition

A metabolic perspective of the neutrophil life cycle: new avenues in immunometabolism

Neutrophils are the most abundant innate immune cells. Multiple mechanisms allow them to engage a wide range of metabolic pathways for biosynthesis and bioenergetics for mediating biological processes such as development in the bone marrow and antimicrobial activity such as ROS production and NET formation, inflammation and tissue repair. We first discuss recent work on neutrophil development and functions and the metabolic processes to regulate granulopoiesis, neutrophil migration and trafficking as well as effector functions. We then discuss metabolic syndromes with impaired neutrophil functions that are influenced by genetic and environmental factors of nutrient availability and usage. Here, we particularly focus on the role of specific macronutrients, such as glucose, fatty acids, and protein, as well as micronutrients such as vitamin B3, in regulating neutrophil biology and how this regulation impacts host health. A special section of this review primarily discusses that the ways nutrient deficiencies could impact neutrophil biology and increase infection susceptibility. We emphasize biochemical approaches to explore neutrophil metabolism in relation to development and functions. Lastly, we discuss opportunities and challenges to neutrophil-centered therapeutic approaches in immune-driven diseases and highlight unanswered questions to guide future discoveries.

Mechanisms of Kwashiorkor-Associated Immune Suppression: Insights From Human, Mouse, and Pig Studies

Malnutrition refers to inadequate energy and/or nutrient intake. Malnutrition exhibits a bidirectional relationship with infections whereby malnutrition increases risk of infections that further aggravates malnutrition. Severe malnutrition (SM) is the main cause of secondary immune deficiency and mortality among children in developing countries. SM can manifest as marasmus (non-edematous), observed most often (68.6% of all malnutrition cases), kwashiorkor (edematous), detected in 23.8% of cases, and marasmic kwashiorkor, identified in ~7.6% of SM cases. Marasmus and kwashiorkor occur due to calorie-energy and protein-calorie deficiency (PCD), respectively. Kwashiorkor and marasmic kwashiorkor present with reduced protein levels, protein catabolism rates, and altered levels of micronutrients leading to uncontrolled oxidative stress, exhaustion of anaerobic commensals, and proliferation of pathobionts. Due to these alterations, kwashiorkor children present with profoundly impaired immune function, compromised intestinal barrier, and secondary micronutrient deficiencies. Kwashiorkor-induced alterations contribute to growth stunting and reduced efficacy of oral vaccines. SM is treated with antibiotics and ready-to-use therapeutic foods with variable efficacy. Kwashiorkor has been extensively investigated in gnotobiotic (Gn) mice and piglet models to understand its multiple immediate and long-term effects on children health. Due to numerous physiological and immunological similarities between pigs and humans, pig represents a highly relevant model to study kwashiorkor pathophysiology and immunology. Here we summarize the impact of kwashiorkor on children's health, immunity, and gut functions and review the relevant findings from human and animal studies. We also discuss the reciprocal interactions between PCD and rotavirus-a highly prevalent enteric childhood pathogen due to which pathogenesis and immunity are affected by childhood SM.

Infection in the Developing Brain: The Role of Unique Systemic Immune Vulnerabilities

Central nervous system (CNS) infections remain a major burden of pediatric disease associated with significant long-term morbidity due to injury to the developing brain. Children are susceptible to various etiologies of CNS infection partly because of vulnerabilities in their peripheral immune system. Young children are known to have reduced numbers and functionality of innate and adaptive immune cells, poorer production of immune mediators, impaired responses to inflammatory stimuli and depressed antibody activity in comparison to adults. This has implications not only for their response to pathogen invasion, but also for the development of appropriate vaccines and vaccination strategies. Further, pediatric immune characteristics evolve across the span of childhood into adolescence as their broader physiological and hormonal landscape develop. In addition to intrinsic vulnerabilities, children are subject to external factors that impact their susceptibility to infections, including maternal immunity and exposure, and nutrition. In this review we summarize the current evidence for immune characteristics across childhood that render children at risk for CNS infection and introduce the link with the CNS through the modulatory role that the brain has on the immune response. This manuscript lays the foundation from which we explore the specifics of infection and inflammation within the CNS and the consequences to the maturing brain in part two of this review series.

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants is still a matter of debate. Protein intake must be sufficient to achieve normal growth without leading to negative effects such as acidosis, uremia, and elevated levels of circulating amino acids.

OBJECTIVES

To determine whether higher (≥ 3.0 g/kg/d) versus lower (< 3.0 g/kg/d) protein intake during the initial hospital stay of formula-fed preterm infants or low birth weight infants (< 2.5 kilograms) results in improved growth and neurodevelopmental outcomes without evidence of short- or long-term morbidity. Specific objectives were to examine the following comparisons of interventions and to conduct subgroup analyses if possible. 1. Low protein intake if the amount was less than 3.0 g/kg/d. 2. High protein intake if the amount was equal to or greater than 3.0 g/kg/d but less than 4.0 g/kg/d. 3. Very high protein intake if the amount was equal to or greater than 4.0 g/kg/d.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 8), in the Cochrane Library (August 2, 2019); OVID MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Ovid MEDLINE(R) Daily, and Ovid MEDLINE(R) (to August 2, 2019); MEDLINE via PubMed (to August 2, 2019) for the previous year; and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (to August 2, 2019). We also searched clinical trials databases and the reference lists of retrieved articles for randomized controlled trials (RCTs) and quasi-randomized trials.

SELECTION CRITERIA

We included RCTs contrasting levels of formula protein intake as low (< 3.0 g/kg/d), high (≥ 3.0 g/kg/d but < 4.0 g/kg/d), or very high (≥ 4.0 g/kg/d) in formula-fed hospitalized neonates weighing less than 2.5 kilograms. We excluded studies if infants received partial parenteral nutrition during the study period, or if infants were fed formula as a supplement to human milk.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane and the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We identified six eligible trials that enrolled 218 infants through searches updated to August 2, 2019. Five studies compared low (< 3 g/kg/d) versus high (3.0 to 4.0 g/kg/d) protein intake using formulas that kept other nutrients constant. The trials were small (n = 139), and almost all had methodological limitations; the most frequent uncertainty was about attrition. Low-certainty evidence suggests improved weight gain (mean difference [MD] 2.36 g/kg/d, 95% confidence interval [CI] 1.31 to 3.40) and higher nitrogen accretion in infants receiving formula with higher protein content (3.0 to 4.0 g/kg/d) versus lower protein content (< 3 g/kg/d), while other nutrients were kept constant. No significant differences were seen in rates of necrotizing enterocolitis, sepsis, or diarrhea. We are uncertain whether high versus low protein intake affects head growth (MD 0.37 cm/week, 95% CI 0.16 to 0.58; n = 18) and length gain (MD 0.16 cm/week, 95% CI -0.02 to 0.34; n = 48), but sample sizes were small for these comparisons. One study compared high (3.0 to 4.0 g/kg/d) versus very high (≥ 4 g/kg/d) protein intake (average intakes were 3.6 and 4.1 g/kg/d) during and after an initial hospital stay (n = 77). Moderate-certainty evidence shows no significant differences in weight gain or length gain to discharge, term, and 12 weeks corrected age from very high protein intake (4.1 versus 3.6 g/kg/d). Three of the 24 infants receiving very high protein intake developed uremia.

AUTHORS' CONCLUSIONS

Higher protein intake (≥ 3.0 g/kg/d but < 4.0 g/kg/d) from formula accelerates weight gain. However, limited information is available regarding the impact of higher formula protein intake on long-term outcomes such as neurodevelopment. Research is needed to investigate the safety and effectiveness of protein intake ≥ 4.0 g/kg/d.

Current Understanding of Innate Immune Cell Dysfunction in Childhood Undernutrition

Undernutrition affects millions of children in low- and middle-income countries (LMIC) and underlies almost half of all deaths among children under 5 years old. The growth deficits that characterize childhood undernutrition (stunting and wasting) result from simultaneous underlying defects in multiple physiological processes, and current treatment regimens do not completely normalize these pathways. Most deaths among undernourished children are due to infections, indicating that their anti-pathogen immune responses are impaired. Defects in the body's first-line-of-defense against pathogens, the innate immune system, is a plausible yet understudied pathway that could contribute to this increased infection risk. In this review, we discuss the evidence for innate immune cell dysfunction from cohort studies of childhood undernutrition in LMIC, highlighting knowledge gaps in almost all innate immune cell types. We supplement these gaps with insights from relevant experimental models and make recommendations for how human and animal studies could be improved. A better understanding of innate immune function could inform future tractable immune-targeted interventions for childhood undernutrition to reduce mortality and improve long-term health, growth and development.

Higher versus lower amino acid intake in parenteral nutrition for newborn infants

BACKGROUND

Sick newborn and preterm infants frequently are not able to be fed enterally, necessitating parenteral fluid and nutrition. Potential benefits of higher parenteral amino acid (AA) intake for improved nitrogen balance, growth, and infant health may be outweighed by the infant's ability to utilise high intake of parenteral AA, especially in the days after birth.

OBJECTIVES

The primary objective is to determine whether higher versus lower intake of parenteral AA is associated with improved growth and disability-free survival in newborn infants receiving parenteral nutrition.Secondary objectives include determining whether:• higher versus lower starting or initial intake of amino acids is associated with improved growth and disability-free survival without side effects;• higher versus lower intake of amino acids at maximal intake is associated with improved growth and disability-free survival without side effects; and• increased amino acid intake should replace non-protein energy intake (glucose and lipid), should be added to non-protein energy intake, or should be provided simultaneously with non-protein energy intake.We conducted subgroup analyses to look for any differences in the effects of higher versus lower intake of amino acids according to gestational age, birth weight, age at commencement, and condition of the infant, or concomitant increases in fluid intake.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (2 June 2017), MEDLINE (1966 to 2 June 2017), Embase (1980 to 2 June 2017), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 2 June 2017). We also searched clinical trials databases, conference proceedings, and citations of articles.

SELECTION CRITERIA

Randomised controlled trials of higher versus lower intake of AAs as parenteral nutrition in newborn infants. Comparisons of higher intake at commencement, at maximal intake, and at both commencement and maximal intake were performed.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality, and extracted data from included studies. We performed fixed-effect analyses and expressed treatment effects as mean difference (MD), risk ratio (RR), and risk difference (RD) with 95% confidence intervals (CIs) and assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

Thirty-two studies were eligible for inclusion. Six were short-term biochemical tolerance studies, one was in infants at > 35 weeks' gestation, one in term surgical newborns, and three yielding no usable data. The 21 remaining studies reported clinical outcomes in very preterm or low birth weight infants for inclusion in meta-analysis for this review.Higher AA intake had no effect on mortality before hospital discharge (typical RR 0.90, 95% CI 0.69 to 1.17; participants = 1407; studies = 14; I² = 0%; quality of evidence: low). Evidence was insufficient to show an effect on neurodevelopment and suggest no reported benefit (quality of evidence: very low). Higher AA intake was associated with a reduction in postnatal growth failure (< 10th centile) at discharge (typical RR 0.74, 95% CI 0.56 to 0.97; participants = 203; studies = 3; I² = 22%; typical RD -0.15, 95% CI -0.27 to -0.02; number needed to treat for an additional beneficial outcome (NNTB) 7, 95% CI 4 to 50; quality of evidence: very low). Subgroup analyses found reduced postnatal growth failure in infants that commenced on high amino acid intake (> 2 to ≤ 3 g/kg/day); that occurred with increased amino acid and non-protein caloric intake; that commenced on intake at < 24 hours' age; and that occurred with early lipid infusion.Higher AA intake was associated with a reduction in days needed to regain birth weight (MD -1.14, 95% CI -1.73 to -0.56; participants = 950; studies = 13; I² = 77%). Data show varying effects on growth parameters and no consistent effects on anthropometric z-scores at any time point, as well as increased growth in head circumference at discharge (MD 0.09 cm/week, 95% CI 0.06 to 0.13; participants = 315; studies = 4; I² = 90%; quality of evidence: very low).Higher AA intake was not associated with effects on days to full enteral feeds, late-onset sepsis, necrotising enterocolitis, chronic lung disease, any or severe intraventricular haemorrhage, or periventricular leukomalacia. Data show a reduction in retinopathy of prematurity (typical RR 0.44, 95% CI 0.21 to 0.93; participants = 269; studies = 4; I² = 31%; quality of evidence: very low) but no difference in severe retinopathy of prematurity.Higher AA intake was associated with an increase in positive protein balance and nitrogen balance. Potential biochemical intolerances were reported, including risk of abnormal blood urea nitrogen (typical RR 2.77, 95% CI 2.13 to 3.61; participants = 688; studies = 7; I² = 6%; typical RD 0.26, 95% CI 0.20 to 0.32; number needed to treat for an additional harmful outcome (NNTH) 4; 95% CI 3 to 5; quality of evidence: high). Higher amino acid intake in parenteral nutrition was associated with a reduction in hyperglycaemia (> 8.3 mmol/L) (typical RR 0.69, 95% CI 0.49 to 0.96; participants = 505; studies = 5; I² = 68%), although the incidence of hyperglycaemia treated with insulin was not different.

AUTHORS' CONCLUSIONS

Low-quality evidence suggests that higher AA intake in parenteral nutrition does not affect mortality. Very low-quality evidence suggests that higher AA intake reduces the incidence of postnatal growth failure. Evidence was insufficient to show an effect on neurodevelopment. Very low-quality evidence suggests that higher AA intake reduces retinopathy of prematurity but not severe retinopathy of prematurity. Higher AA intake was associated with potentially adverse biochemical effects resulting from excess amino acid load, including azotaemia. Adequately powered trials in very preterm infants are required to determine the optimal intake of AA and effects of caloric balance in parenteral nutrition on the brain and on neurodevelopment.

Impact of Childhood Malnutrition on Host Defense and Infection

The global impact of childhood malnutrition is staggering. The synergism between malnutrition and infection contributes substantially to childhood morbidity and mortality. Anthropometric indicators of malnutrition are associated with the increased risk and severity of infections caused by many pathogens, including viruses, bacteria, protozoa, and helminths. Since childhood malnutrition commonly involves the inadequate intake of protein and calories, with superimposed micronutrient deficiencies, the causal factors involved in impaired host defense are usually not defined. This review focuses on literature related to impaired host defense and the risk of infection in primary childhood malnutrition. Particular attention is given to longitudinal and prospective cohort human studies and studies of experimental animal models that address causal, mechanistic relationships between malnutrition and host defense. Protein and micronutrient deficiencies impact the hematopoietic and lymphoid organs and compromise both innate and adaptive immune functions. Malnutrition-related changes in intestinal microbiota contribute to growth faltering and dysregulated inflammation and immune function. Although substantial progress has been made in understanding the malnutrition-infection synergism, critical gaps in our understanding remain. We highlight the need for mechanistic studies that can lead to targeted interventions to improve host defense and reduce the morbidity and mortality of infectious diseases in this vulnerable population.

Does Amount of Protein in Formula Matter for Low-Birthweight Infants? A Cochrane Systematic Review

BACKGROUND

High protein intake may be associated with negative consequences such as acidosis, uremia, and elevated levels of circulating amino acids (eg, phenylalanine levels). We performed a systematic review of randomized controlled trials to determine whether formula-fed low-birthweight infants could tolerate protein intakes>or=3.0 g/kg/d in their initial hospital stay, without adverse consequences.

METHODS

Randomized controlled trials contrasting levels of protein intakes as low (<3.0 g/kg/d), high (>or=3.0 g/kg/d but <4.0 g/kg/d), or very high protein intake (>or=4.0 g/kg/d) while other nutrients were held constant, were identified through a systematic search of the literature. Standard methods of the Cochrane Collaboration were used by 2 independent reviewers, with the third reviewer facilitating consensus decision making.

RESULTS

A meta-analysis of 5 randomized trials indicated improved weight gain (weighted mean difference [WMD] 2.36 g/kg/d; 95% confidence interval [CI] 1.31-3.40) and higher nitrogen accretion (WMD 143.7 mg/kg/d; 95% CI 128.7-158.8) with high (>or=3.0 g/kg/d but <4.0 g/kg/d) compared with low (<3.0 g/kg/d) protein intakes while other nutrients were kept constant. No data were available for IQ or Bayley scores at 18 months or later or for very high protein intakes (>or=4.0 g/kg/d). No significant differences were seen in rates of necrotizing enterocolitis, sepsis, or diarrhea.

CONCLUSIONS

Accelerated weight and nitrogen accretion were noted with higher protein intakes in "healthy" formula-fed low-birthweight infants. This benefit could not be weighed against the adverse consequences of elevated blood urea nitrogen levels and increased metabolic acidosis and neurodevelopmental abnormalities.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants is still a matter of debate. Protein intake must be sufficient to achieve normal growth without negative effects such as acidosis, uremia, and elevated levels of circulating amino acids.

OBJECTIVES

To determine whether higher (≥ 3.0 g/kg/d) versus lower (< 3.0 g/kg/d) protein intake during the initial hospital stay of formula-fed preterm infants or low birth weight infants (< 2.5 kilograms) results in improved growth and neurodevelopmental outcomes without evidence of short- and long-term morbidity.To examine the following distinctions in protein intake. 1. Low protein intake if the amount was less than 3.0 g/kg/d. 2. High protein intake if the amount was equal to or greater than 3.0 g/kg/d but less than 4.0 g/kg/d. 3. Very high protein intake if the amount was equal to or greater than 4.0 g/kg/d.If the reviewed studies combined alterations of protein and energy, subgroup analyses were to be carried out for the planned categories of protein intake according to the following predefined energy intake categories. 1. Low energy intake: less than 105 kcal/kg/d. 2. Medium energy intake: greater than or equal to 105 kcal/kg/d and less than or equal to 135 kcal/kg/d. 3. High energy intake: greater than 135 kcal/kg/d.As the Ziegler-Fomon reference fetus estimates different protein requirements for infants based on birth weight, subgroup analyses were to be undertaken for the following birth weight categories. 1. < 800 grams. 2. 800 to 1199 grams. 3. 1200 to 1799 grams. 4. 1800 to 2499 grams.

SEARCH METHODS

The standard search methods of the Cochrane Neonatal Review Group were used. MEDLINE, CINAHL, PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library) were searched.

SELECTION CRITERIA

Randomized controlled trials contrasting levels of formula protein intake as low (< 3.0 g/kg/d), high (≥ 3.0 g/kg/d but < 4.0 g/kg/d), or very high (≥ 4.0 g/kg/d) in formula-fed hospitalized neonates weighing less than 2.5 kilograms were included. Studies were excluded if infants received partial parenteral nutrition during the study period or were fed formula as a supplement to human milk. Studies in which nutrients other than protein also varied were added in a post-facto analysis.

DATA COLLECTION AND ANALYSIS

The standard methods of the Cochrane Neonatal Review Group were used.

MAIN RESULTS

Five studies compared low versus high protein intake. Improved weight gain and higher nitrogen accretion were demonstrated in infants receiving formula with higher protein content while other nutrients were kept constant. No significant differences were seen in rates of necrotizing enterocolitis, sepsis, or diarrhea.One study compared high versus very high protein intake during and after an initial hospital stay. Very high protein intake promoted improved gain in length at term, but differences did not remain significant at 12 weeks corrected age. Three of the 24 infants receiving very high protein intake developed uremia.A post-facto analysis revealed further improvement in all growth parameters in infants receiving formula with higher protein content. No significant difference in the concentration of plasma phenylalanine was noted between high and low protein intake groups. However, one study (Goldman 1969) documented a significantly increased incidence of low intelligence quotient (IQ) scores among infants of birth weight less than 1300 grams who received a very high protein intake (6 to 7.2 g/kg).

AUTHORS' CONCLUSIONS

Higher protein intake (≥ 3.0 g/kg/d but < 4.0 g/kg/d) from formula accelerates weight gain. However, limited information is available regarding the impact of higher formula protein intake on long-term outcomes such as neurodevelopmental abnormalities. Available evidence is not adequate to permit specific recommendations regarding the provision of very high protein intake (> 4.0 g/kg/d) from formula during the initial hospital stay or after discharge.

Early versus late administration of amino acids in preterm infants receiving parenteral nutrition

BACKGROUND

Observational studies in preterm newborns suggest that delay in administering amino acids could result in a protein catabolic state and could impact on growth and development.

OBJECTIVES

To determine the effect of early administration of amino acids in premature newborns on growth, neurodevelopmental outcome, mortality and clinically important side effects.

SEARCH METHODS

The standard search strategy of the Neonatal Review Group as outlined in The Cochrane Library was used. Relevant randomised controlled trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2012 I ssue 9 ), MEDLINE, EMBASE and CINAHL from their earliest dates to September 2012. The trial registry portal of the World Health Organization's International Cilinical Trial Registry Platform and ClinicalTrials.gov (US National Institute of Health) was searched to identify ongoing and completed but unpublished studies.

SELECTION CRITERIA

Randomised controlled trials comparing early administration of amino acids with late administration in premature newborn infants were included. Early administration of amino acid solution was defined as the administration of amino acids in isolation or with total parenteral nutrition within the first 24 hours of birth; late initiation was defined as the administration of amino acids in isolation or with total parenteral nutrition after the first 24 hours of birth. The primary outcome measures were growth, neurodevelopmental outcome and mortality at 28 days. The secondary outcomes were biochemical abnormalities, sepsis and mortality.

DATA COLLECTION AND ANALYSIS

Both review authors independently selected trials, assessed trial quality and extracted data from the included studies. We contacted authors for further information. Fixed-effect analyses were performed. The treatment effect was expressed as mean difference for continuous variables and as risk difference and risk ratio for dichotomous variables. All results included 95% confidence intervals (CIs).

MAIN RESULTS

Seven randomised controlled trials were included in this review. One randomised controlled trial reported no difference in crown-heel length and occipitofrontal head circumference by day 10. Four trials that enrolled 93 premature infants showed positive nitrogen balance (The mean difference with 95% CI was 250.42 (224.91 to 275.93 P value < 0.00001). Four trials showed a significant difference in the level of blood urea nitrogen (BUN) in the first 48 hours (P value < 0.00001). Early administration of amino acids did not result in metabolic acidosis in the first 24 hours.

AUTHORS' CONCLUSIONS

There is no available evidence of the benefits of early administration of amino acids on mortality, early and late growth and neurodevelopment. There is evidence from four randomised controlled trials included in this review that early administration of amino acids is associated with a positive nitrogen balance. The clinical relevance of this finding is not known. Acid-base status and ammonia levels were normal in the infants who received amino acids early. Given the small number of infants in the randomised controlled trials included in this review, the clinical heterogeneity among them, and the lack of data on important clinical outcomes, there is insufficient evidence to guide practice regarding the early versus late administration of amino acids to infants less than 37 weeks gestation.

Effects of malnutrition on oxidative burst functions and infection episodes in children with acute lymphoblastic leukemia

INTRODUCTION

The aim of this study was to determine the effect of malnutrition on oxidative burst functions (OBF) of neutrophils in children with acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

Twenty-eight patients with ALL and thirty healthy controls were enrolled to the study. Thirteen patients with ALL were found to have malnutrition. While neutrophil OBF of ALL patients without malnutrition were studied both before induction chemotherapy and 3 months after, the same functions in ALL patients with malnutrition were studied both before induction chemotherapy and when the nutritional status improved. Control group were studied at admission and 3 months later.

RESULTS

The OBF of ALL patients with and without malnutrition before induction chemotherapy were found to be significantly lower than the control group (P = 0.009), whereas the OBF were found to be similar in both patient groups with ALL (P = 0.27). The median infection episode rate and the duration of antibiotics therapy during the study period were similar in both patient groups with ALL. The repeated OBF of both patient groups with ALL were shown to increase to similar values with the control group in the third month of chemotherapy (P = 0.002). The median infection episode rate during the first month of chemotherapy was shown to decrease significantly during the third month of chemotherapy in both patient with ALL groups (P < 0.001).

CONCLUSIONS

We have not been able to demonstrate an overt effect of malnutrition on OBF. However, our results still need to be verified via further larger scaled studies of OBF in leukemic children with and without malnutrition.

Interactions of malnutrition and immune impairment, with specific reference to immunity against parasites

1. Clinical malnutrition is a heterogenous group of disorders including macronutrient deficiencies leading to body cell mass depletion and micronutrient deficiencies, and these often coexist with infectious and inflammatory processes and environmental problems. 2. There is good evidence that specific micronutrients influence immunity, particularly zinc and vitamin A. Iron may have both beneficial and deleterious effects depending on circumstances. 3. There is surprisingly slender good evidence that immunity to parasites is dependent on macronutrient intake or body composition.

Higher versus lower protein intake in formula-fed low birth weight infants

BACKGROUND

The ideal quantity of dietary protein for formula-fed low birth weight infants < 2.5 kilograms is still a matter of controversy and debate. In premature infants, the protein intake must be sufficient to achieve normal growth without negative effects such as acidosis, uremia, and elevated levels of circulating amino acids (e.g. phenylalanine levels). This systematic review evaluates the benefits and risks of higher (>= 3.0 g/kg/day) versus lower (< 3.0 g/kg/day) protein intakes during the initial hospital stay of formula-fed preterm infants < 2.5 kilograms.

OBJECTIVES

To determine whether higher (>= 3.0 g/kg/day) versus lower (< 3.0 g/kg/day) protein intakes during the initial hospital stay of formula-fed preterm infants < 2.5 kilograms result in improved growth and neurodevelopmental outcomes without evidence of short and long-term morbidity.

SEARCH STRATEGY

Two review authors searched MEDLINE (1966 - May 2005), CINAHL (1982 - May 2005), PubMed (1966 - May 2005), EMBASE (1980 - May 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2005), abstracts, conferences and symposia proceedings from Society of Pediatric Research, and American Academy of Pediatrics. Cross references were reviewed independently for additional relevant titles and abstracts for articles up to fifty years old.

SELECTION CRITERIA

Randomized controlled trials contrasting levels of formula protein intakes as low (< 3.0 g/kg/day), high (=> 3.0 g/kg/day but < 4.0 g/kg/day), or very high protein intake (=> 4.0 g/kg/day) during hospitalization of neonates less than 2.5 kilograms at birth who were formula-fed. Studies were not included if infants received partial parenteral nutrition during the study period or were fed formula as a supplement to human milk. Given the small number of studies that met all inclusion criteria, studies in which nutrients other than protein also varied (> 10% relative difference) were added in a post-facto analysis.

DATA COLLECTION AND ANALYSIS

Two review authors used standard methods of the Cochrane Collaboration and of the Cochrane Neonatal Review Group to independently assess trial eligibility and quality, and extracted data. In a 3-arm trial where two groups fell within the same predesignated protein intake group, weighted means and pooled standard deviations were calculated.

MAIN RESULTS

The literature search identified 37 studies, of which five met all the inclusion criteria. All five studies compared low (< 3.0 g/kg/day) to high protein intakes (=> 3.0 g/kg/day but < 4.0 g/kg/day). The overall analysis revealed an improved weight gain (WMD 2.36 g/kg/day, 95% CI 1.31, 3.40) and higher nitrogen accretion (WMD 143.7 mg/kg/day, 95% CI 128.7, 158.8) in infants receiving formula with higher protein content while other nutrients were kept constant. None of the studies reported IQ or Bayley scores at 18 months or later. No significant differences were seen in rates of necrotizing enterocolitis, sepsis or diarrhea. Of three studies included in the post-facto analysis, only one could be included in the meta-analysis. The post-facto analysis revealed further improvement in all growth parameters in infants receiving formula with higher protein content (weight gain: WMD 2.53 g/kg/day, 95% CI 1.62, 3.45, linear growth: WMD 0.16 cm/week, 95% CI 0.03, 0.30, and head growth: WMD 0.23, 95% CI 0.12, 0.35). There was no significant difference (WMD 0.25, 95% CI -0.20, 0.70) in the concentration of plasma phenylalanine between the high and low protein intake groups. One study (Goldman 1969) in the post-facto analysis documented a significantly increased incidence of low IQ scores, below 90, in infants of birth weight less than 1300 grams who received a very high protein intake (6 to 7.2 g/kg/day).

AUTHORS' CONCLUSIONS

This systematic review suggests that higher protein intake (=> 3.0 g/kg/day but < 4.0 g/kg/day) from formula accelerates weight gain. Based on increased nitrogen accretion rates, this most likely indicates an increase in lean body mass. Although accelerated weight gain is considered to be a positive effect, increase in other outcome measures examined may represent a negative or ambivalent effect. These include elevated blood urea nitrogen levels and increased metabolic acidosis. Limited information was available regarding the impact of higher formula protein intakes on long term outcomes such as neurodevelopmental abnormalities. As determined in this review, existing research literature on this topic is not adequate to make specific recommendations regarding the provision of very high protein intake (> 4.0 g/kg/day) from formula.

Serum IgE level in malnutrition

Infections and malnutrition remain the main causes of infant mortality in developing countries. In protein-calorie malnutrition, immunologic responses are affected, which often facilitates infections. However, the presence of asthma and allergic rhinitis are not commonly recognized in malnourished individuals. The aim of this study was to evaluate serum IgE values in children with primary moderate protein-calorie malnutrition.

METHODS

The level of IgE in peripheral blood of 18 children between 2 and 4 old with moderate protein-calorie malnutrition and without associated parasitic infestation was compared with that of 15 well nourished children of similar age. IgE serum levels were measured by an immunoenzymatic method.

RESULTS

The median level of serum IgE in malnourished children was 69.30 ng/ml while the control group showed a mean level of 95.97 ng/ml. This difference was significant (p < 0.01).

CONCLUSION

Malnourished children show decreased serum IgE levels. This might be one of the adaptive mechanisms of malnutrition employed in an attempt to use energy and protein reserves for growth and other functions. Our results are coherent with the decrease in IgE mediated reactions in malnourished patients.