Serum ferritin values in neonates <29 weeks' gestation are highly variable and do not correlate with reticulocyte hemoglobin content

OBJECTIVES

To compare serum ferritin and RET-He values among extremely low gestational age neonates ELGANs with other markers of iron-deficient erythropoiesis.

STUDY DESIGN

This is a secondary analysis of the NICHD Darbepoetin Trial. Study data from placebo recipients who had a serum ferritin, a RET-He, and a mean corpuscular volume (MCV) measurement within a 24-hour period were analyzed for correlation.

RESULTS

Mixed linear regression models showed no association between ferritin and RET-He at both early (β = 0.0016, p = 0.40) and late (β = -0.0001, p = 0.96) time points. Positive associations were observed between RET-He and MCV at baseline, early, and late time points (p < 0.01, =0.01, <0.001, respectively), while ferritin was not associated with MCV at any time point.

CONCLUSIONS

Our study shows that RET-He is better correlated with MCV as a marker of iron-limited erythropoiesis than ferritin. The results suggest that ferritin is limited as a marker of iron sufficiency in premature infants.

STUDY IDENTIFICATION

FDA IND Number 100138; ClinicalTrials.gov number NCT03169881; NRN ID number NICHD-NRN-0058 (Darbe).

The Impact of Maternal Antibiotics on Neonatal Disease

OBJECTIVES

We examined the impact of prenatal exposure to maternal antibiotics on risk of necrotizing enterocolitis (NEC), late onset sepsis (LOS), and death in infants born preterm.

STUDY DESIGN

Secondary data analysis was conducted via an extant cohort of 580 infants born <32 weeks of gestation and enrolled in 3 level III neonatal intensive care units. Prenatal antibiotic exposure was defined as antibiotics received by the mother within 72 hours before delivery. Postnatal empiric antibiotic exposure was defined as antibiotic initiated within the first day of life without documented infection, categorized as low (<5 days) or high (>5 days) duration.

RESULTS

Two-thirds of mothers received antibiotics within 72 hours before delivery, of whom 59.8% received >1 antibiotic. Ampicillin (37.6%) and azithromycin (26.4%) were the most common antibiotics given. NEC occurred in 7.5%, LOS in 11.1%, death in 9.6%, and the combined outcome of NEC, LOS, or death in 21.3% of study infants. In multiple logistic regression models adjusted for gestational age, postnatal empiric antibiotic exposure, and other factors, prenatal antibiotic exposure was associated with reduced risk of NEC (OR 0.28; 95% CI 0.14-0.56; P < .001), death (OR 0.29; 95% CI 0.14-0.60; P = .001), but not LOS (OR 1.59; 95% CI 0.84-2.99; P = .15), although protection was significant for the combined outcome (OR 0.52, P < .001). High postnatal empiric antibiotic exposure was associated with greater risk of death but not other outcomes in multiple regression models (OR 3.18, P = .002).

CONCLUSIONS

Prenatal antibiotic exposure was associated with lower rates of NEC or death of infants born preterm, and its impact on infant outcomes warrants further study.

Association of Chorioamnionitis with Aberrant Neonatal Gut Colonization and Adverse Clinical Outcomes

Objective

Chorioamnionitis (inflammation of the placenta and fetal membranes) and abnormal gastrointestinal colonization have been associated with an increased risk of sepsis and death in preterm infants, but whether chorioamnionitis causes abnormal pioneering gastrointestinal colonization in infants is not known. We determined the relationship between chorioamnionitis, altered infant fecal microbiome indicating abnormal gastrointestinal colonization, and adverse outcomes.

Study Design

Preterm infants ≤ 28 weeks at birth were enrolled from 3 level III NICUs in Cincinnati, Ohio and Birmingham, Alabama. Sequencing for 16S microbial gene was performed on stool samples in the first 3 weeks of life. Chorioamnionitis was diagnosed by placental histology. Late onset sepsis and death outcomes were analyzed in relation to fecal microbiota and chorioamnionitis with or without funisitis (inflammation of the umbilical cord).

Results

Of the 106 enrolled infants, 48 infants had no chorioamnionitis, 32 infants had chorioamnionitis but no funisitis (AC), and 26 infants had chorioamnionitis with funisitis (ACF). The fecal samples from ACF infants collected by day of life 7 had higher relative abundance of family Mycoplasmataceae (phylum Tenericutes), genus Prevotella (phylum Bacteroidetes) and genus Sneathia (phylum Fusobacteria). Further, AC and ACF infants had higher incidence of late-onset sepsis/death as a combined outcome. Presence of specific clades in fecal samples, specifically, order Fusobacteria, genus Sneathia or family Mycoplasmataceae, were significantly associated with higher risk of sepsis or death.

Conclusion

The results support the hypothesis that specific alterations in the pioneering infant gastrointestinal microbiota induced by chorioamnionitis predispose to neonatal sepsis or death.

Metagenomic Sequencing with Strain-Level Resolution Implicates Uropathogenic E. coli in Necrotizing Enterocolitis and Mortality in Preterm Infants

Necrotizing enterocolitis (NEC) afflicts approximately 10% of extremely preterm infants with high fatality. Inappropriate bacterial colonization with Enterobacteriaceae is implicated, but no specific pathogen has been identified. We identify uropathogenic E. coli (UPEC) colonization as a significant risk factor for the development of NEC and subsequent mortality. We describe a large-scale deep shotgun metagenomic sequence analysis of the early intestinal microbiome of 144 preterm and 22 term infants. Using a pan-genomic approach to functionally subtype the E. coli, we identify genes associated with NEC and mortality that indicate colonization by UPEC. Metagenomic multilocus sequence typing analysis further defined NEC-associated strains as sequence types often associated with urinary tract infections, including ST69, ST73, ST95, ST127, ST131, and ST144. Although other factors associated with prematurity may also contribute, this report suggests a link between UPEC and NEC and indicates that further attention to these sequence types as potential causal agents is needed.

Center Variation in Intestinal Microbiota Prior to Late-Onset Sepsis in Preterm Infants

OBJECTIVE

Late onset sepsis (LOS) contributes to mortality and morbidity in preterm infants. We tested the hypotheses that microbes causing LOS originate from the gut, and that distortions in the gut microbial community increases subsequent risk of LOS.

STUDY DESIGN

We examined the gut microbial community in prospectively collected stool samples from preterm infants with LOS and an equal number of age-matched controls at two sites (Cincinnati, OH and Birmingham, AL), by sequencing the bacterial 16S rDNA. We confirmed our findings in a subset of infants by whole genome shotgun sequencing, and analyzed the data using R and LEfSe.

RESULTS

Infants with LOS in Cincinnati, as compared to controls, had less abundant Actinobacteria in the first samples after birth (median 18 days before sepsis onset), and less abundant Pseudomonadales in the last samples collected prior to LOS (median 8 days before sepsis onset). Infants with LOS in Birmingham, as compared to controls, had no differences identified in the first sample microbial communities, but Lactobacillales was less abundant in the last samples prior to LOS (median 4 days before sepsis onset). Sequencing identified detectable levels of the sepsis-causative organism in stool samples prior to disease onset for 82% of LOS cases.

CONCLUSIONS

Translocation of gut microbes may account for the majority of LOS cases. Distortions in the fecal microbiota occur prior to LOS, but the form of distortion depends on timing and site. The microbial composition of fecal samples does not predict LOS onset in a generalizable fashion.

Early empiric antibiotic use in preterm infants is associated with lower bacterial diversity and higher relative abundance of Enterobacter

OBJECTIVES

To determine the impact of empiric ampicillin and gentamicin use in the first week of life on microbial colonization and diversity in preterm infants.

STUDY DESIGN

The 16s ribosomal DNA community profiling was used to compare the microbiota of 74 infants born ≤32 weeks gestational age by degree of antibiotic use in the first week of life. The degree of antibiotic use was classified as 0 days, 1-4 days, and 5-7 days of antibiotic administration. All of the antibiotic use was empiric, defined as treatment based solely on clinical suspicion of infection without a positive culture result.

RESULTS

Infants who received 5-7 days of empiric antimicrobial agents in the first week had increased relative abundance of Enterobacter (P = .016) and lower bacterial diversity in the second and third weeks of life. Infants receiving early antibiotics also experienced more cases of necrotizing enterocolitis, sepsis, or death than those not exposed to antibiotics.

CONCLUSIONS

Early empiric antibiotics have sustained effects on the intestinal microbiota of preterm infants. Intestinal dysbiosis in this population has been found to be associated with elevated risk of necrotizing enterocolitis, sepsis, or death.

Intestinal microbiota of preterm infants differ over time and between hospitals

BACKGROUND

Intestinal microbiota are implicated in risk of necrotizing enterocolitis (NEC) and sepsis, major diseases of preterm infants in neonatal intensive care units (NICUs). Rates of these diseases vary over time and between NICUs, but time and NICU comparisons of the intestinal microbiota of preterm infants are lacking.

METHODS

We included 66 singleton infants <29 weeks gestational age with stool samples collected between postnatal days 3 to 21 of life who survived free of NEC and sepsis. Infants were enrolled during 2010 and 2011. Twenty-six infants were enrolled at hospital 1 in Cincinnati, OH, and 40 infants were enrolled at hospital 2 in Birmingham, AL. Samples collected from days 3-9 ("week 1") and days 10-16 ("week 2") were compared between years and hospitals. Microbial succession was compared between hospitals in 28 infants with samples from the first 3 weeks of life. DNA extracted from stool was used to sequence the 16S rRNA gene by Illumina MiSeq using universal primers. Resulting operational taxonomic unit tables were analyzed for differences between years and hospitals using linear discriminant analysis effect size algorithm (LEfSe; significance, p < 0.05).

RESULTS

Significant variation was observed in infant microbiota by year and hospital. Among hospital 1 infants, week 1 samples had more phylum Firmicutes (class Bacilli, families Clostridiaceae and Enterococcaceae) in 2010 and more phylum Proteobacteria (family Enterobacteriaceae) in 2011; week 2 samples did not significantly vary over time. However, among hospital 2 infants, the week 1 shift was nearly opposite, with more Proteobacteria (Enterobacteriaceae) in 2010 and more Firmicutes (Bacilli) in 2011; week 2 samples exhibited the same pattern. Regression analysis of clinical covariates found that antibiotic use had an important influence but did not explain these observed shifts in microbiota over time and between hospitals. Microbial succession also differed by hospital, with greater change in microbiota in hospital 1 than hospital 2 infants (p < 0.01, Jaccard distance).

CONCLUSION

Colonizing microbiota differ over time and between NICUs in ways that could be relevant to disease. Multi-site, longitudinal studies are needed to reliably define the impact of intestinal microbiota on adverse outcomes of preterm infants.

Early microbial and metabolomic signatures predict later onset of necrotizing enterocolitis in preterm infants

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating intestinal disease that afflicts 10% of extremely preterm infants. The contribution of early intestinal colonization to NEC onset is not understood, and predictive biomarkers to guide prevention are lacking. We analyzed banked stool and urine samples collected prior to disease onset from infants <29 weeks gestational age, including 11 infants who developed NEC and 21 matched controls who survived free of NEC. Stool bacterial communities were profiled by 16S rRNA gene sequencing. Urinary metabolomic profiles were assessed by NMR.

RESULTS

During postnatal days 4 to 9, samples from infants who later developed NEC tended towards lower alpha diversity (Chao1 index, P = 0.086) and lacked Propionibacterium (P = 0.009) compared to controls. Furthermore, NEC was preceded by distinct forms of dysbiosis. During days 4 to 9, samples from four NEC cases were dominated by members of the Firmicutes (median relative abundance >99% versus <17% in the remaining NEC and controls, P < 0.001). During postnatal days 10 to 16, samples from the remaining NEC cases were dominated by Proteobacteria, specifically Enterobacteriaceae (median relative abundance >99% versus 38% in the other NEC cases and 84% in controls, P = 0.01). NEC preceded by Firmicutes dysbiosis occurred earlier (onset, days 7 to 21) than NEC preceded by Proteobacteria dysbiosis (onset, days 19 to 39). All NEC cases lacked Propionibacterium and were preceded by either Firmicutes (≥98% relative abundance, days 4 to 9) or Proteobacteria (≥90% relative abundance, days 10 to 16) dysbiosis, while only 25% of controls had this phenotype (predictive value 88%, P = 0.001). Analysis of days 4 to 9 urine samples found no metabolites associated with all NEC cases, but alanine was positively associated with NEC cases that were preceded by Firmicutes dysbiosis (P < 0.001) and histidine was inversely associated with NEC cases preceded by Proteobacteria dysbiosis (P = 0.013). A high urinary alanine:histidine ratio was associated with microbial characteristics (P < 0.001) and provided good prediction of overall NEC (predictive value 78%, P = 0.007).

CONCLUSIONS

Early dysbiosis is strongly involved in the pathobiology of NEC. These striking findings require validation in larger studies but indicate that early microbial and metabolomic signatures may provide highly predictive biomarkers of NEC.

Fetal and postnatal brain MRI in premature infants with twin-twin transfusion syndrome

OBJECTIVE

To describe the findings on fetal and postnatal magnetic resonance imaging (MRI) in premature infants with twin-twin transfusion syndrome (TTTS) and to determine whether currently used staging systems and other fetal and postnatal factors correlate with brain injury in this population.

STUDY DESIGN

We performed a prospective study of 22 premature infants with TTTS whose mothers had fetal MRIs. Postnatal brain MRI was performed at term equivalent age (38 to 44 weeks) and medical records were reviewed. Brain injury was scored on fetal and postnatal MRIs using an injury scale incorporating hemorrhagic and nonhemorrhagic injury.

RESULT

The median (range) gestational age (GA) was 31 weeks (26 to 35) and birth weight (BW) was 1296 g (762 to 2330). In all, 5/22 patients (23%) had brain injury seen on fetal MRI and 15/22 patients (68%) had brain injury seen on postnatal MRI. Quintero stage was the only predictor variable that was significantly correlated with the total brain injury score (P=0.05).

CONCLUSION

Postnatal brain injury in premature infants with TTTS is correlated with Quintero stage. GA and BW are not predictive of brain injury in this cohort of infants.

Hospital and neurodevelopmental outcomes of extremely low-birth-weight infants with necrotizing enterocolitis and spontaneous intestinal perforation

OBJECTIVE

We sought to determine the incidence of necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) in surviving extremely low-birth-weight (ELBW, <1000 g birth weight) infants and to establish the impact of NEC on outcomes by hospital discharge and at 18 to 22 months adjusted age in a large, contemporary, population-based practice.

STUDY DESIGN

Hospital outcome data for all ELBW infants born in the greater Cincinnati region from 1998 to 2009 were extracted from the National Institute of Child Health Neonatal Research Network Database. Neurodevelopmental outcome at 18 to 22 months was assessed using Bayley Scales of Infant Development-II scores for Mental Developmental Index and Psychomotor Developmental Index. Multivariable logistic regression was used and adjusted odds ratios reported to control for confounders.

RESULT

From 1998 to 2009, ELBW infants accounted for 0.5% of the 352 176 live-born infants in greater Cincinnati. The incidence of NEC was 12%, with a 50% case-fatality rate. Death before discharge, morbid complications of prematurity and neurodevelopmental impairment were all increased among infants diagnosed with NEC. Infants with surgical NEC and SIP had a higher incidence of death, but long-term neurodevelopmental outcomes were not different comparing surviving ELBW infants with medical NEC, surgical NEC and SIP.

CONCLUSION

Although ELBW infants comprise a very small proportion of live-born infants, those who develop NEC and SIP are at an increased risk for death, morbid complications of prematurity and neurodevelopmental impairment. No significant differences in neurodevelopmental outcomes were observed between the medical and surgical NEC and SIP groups.

Grade and laterality of intraventricular haemorrhage to predict 18-22 month neurodevelopmental outcomes in extremely low birthweight infants

AIM

To determine whether extremely low-birthweight (ELBW) infants with bilateral compared to unilateral intraventricular haemorrhage (IVH) have worse neurodevelopmental outcomes at 18-22 months.

METHODS

A total of 166 ELBW infants (<1000 g) admitted to a Cincinnati NICU from 1998 to 2005 with a head ultrasound showing Grade I-IV IVH and neurodevelopmental assessment at 18-22 months corrected age were included. Multivariable linear and logistic regression models were developed to determine the impact of laterality and grade of IVH and other clinical variables to predict scores on the Bayley Scales of Infant Development, Second Edition, Mental Development Index and Psychomotor Development Index and the combined outcome of neurodevelopmental impairment (NDI).

RESULTS

Infants with bilateral grade IV IVH had lower adjusted mean Bayley scores compared with infants with unilateral grade IV IVH. For grades I, II and III IVH, bilaterality of IVH was not associated with lower mean Bayley scores. Infants with grade IV IVH had the highest odds of NDI. The probability of NDI increased with sepsis and postnatal steroid use.

CONCLUSION

ELBW infants with bilateral compared to those with unilateral grade IV IVH had worse neurodevelopmental outcomes. Infants with grades I-III IVH had similar outcomes whether they had unilateral or bilateral IVH.

A Potential Biomarker for Acute Kidney Injury in Preterm Infants from Metabolic Profiling

BACKGROUND

Currently used biomarkers for acute kidney injury (AKI), namely Ngal, SCr, and BUN, are inadequate for timely detection of AKI in preterm infants.

METHODS

Nuclear magnetic resonance (NMR) spectroscopy-based metabolic profiling was conducted on urines from 20 preterm infants to determine if novel metabolic biomarkers could be identified for early detection of AKI. Urines were collected from every patient each day for the first 14 days of life. NMR spectra were measured for all urines and metabolic profiling analysis conducted.

RESULTS

One metabolite, carnitine, increased significantly in urines of three extremely low birth weight (ELBW) infants starting on day five of life. The three affected infants either received prolonged antibiotic treatment, extended treatment with indomethacin, or both. One ELBW patient who received both treatments and reached the highest urinary carnitine level died on day 10 of life due to localized gut perforation complicated by suspected AKI.

CONCLUSIONS

It was concluded that carnitine increased in the three neonates in part due to antibiotic- and/or indomethacin-induced AKI. It is hypothesized that combined antibiotic and indomethacin treatment promoted AKI resulting in reduced proximal renal tubule reabsorption of carnitine and that β-lactam antibiotics blocked renal carnitine uptake by human organic cation transporter, hOCTN2.

Prolonged initial empirical antibiotic treatment is associated with adverse outcomes in premature infants

OBJECTIVE

To investigate the outcomes after prolonged empirical antibiotic administration to premature infants in the first week of life, and concluding subsequent late onset sepsis (LOS), necrotizing enterocolitis (NEC), and death.

STUDY DESIGN

Study infants were ≤ 32 weeks gestational age and ≤ 1500 g birth weight who survived free of sepsis and NEC for 7 days. Multivariable logistic regression was conducted to determine independent relationships between prolonged initial empirical antibiotic therapy (≥ 5 days) and study outcomes that control for birth weight, gestational age, race, prolonged premature rupture of membranes, days on high-frequency ventilation in 7 days, and the amount of breast milk received in the first 14 days of life.

RESULTS

Of the 365 premature infants who survived 7 days free of sepsis or NEC, 36% received prolonged initial empirical antibiotics, which was independently associated with subsequent outcomes: LOS (OR, 2.45 [95% CI, 1.28-4.67]) and the combination of LOS, NEC, or death (OR, 2.66 [95% CI, 1.12-6.3]).

CONCLUSIONS

Prolonged administration of empirical antibiotics to premature infants with sterile cultures in the first week of life is associated with subsequent severe outcomes. Judicious restriction of antibiotic use should be investigated as a strategy to reduce severe outcomes for premature infants.

Pharmacokinetics of levetiracetam in neonates with seizures

The pharmacokinetics of levetiracetam were determined prospectively in 18 neonates with seizures. Neonates were found to have lower clearance, higher volume of distribution, and a longer half-life as compared with older children and adults. Mild somnolence was the only adverse effect.

Fucosyltransferase 2 non-secretor and low secretor status predicts severe outcomes in premature infants

OBJECTIVE

To investigate secretor gene fucosyltransferase 2 (FUT2) polymorphism and secretor phenotype in relation to outcomes of prematurity.

STUDY DESIGN

Study infants were ≤32 weeks gestational age. Secretor genotype was determined from salivary DNA. Secretor phenotype was measured with H antigen, the carbohydrate produced by secretor gene enzymes, in saliva samples collected on day 9 ± 5. The optimal predictive cutoff point in salivary H values was identified with Classification and Regression Tree analysis. Study outcomes were death, necrotizing enterocolitis (NEC, Bell's stage II/III), and confirmed sepsis.

RESULTS

There were 410 study infants, 26 deaths, 30 cases of NEC, and 96 cases of sepsis. Analyzed by genotype, 13% of 95 infants who were non-secretors, 5% of 203 infants who were heterozygotes, and 2% of 96 infants who were secretor dominant died (P = .01). Analyzed by phenotype, 15% of 135 infants with low secretor phenotype died, compared with 2% of 248 infants with high secretor phenotype (predictive value = 76%, P < .001). Low secretor phenotype was associated (P < .05) with NEC, and non-secretor genotype was associated (P = .05) with gram negative sepsis. Secretor status remained significant after controlling for multiple clinical factors.

CONCLUSIONS

Secretor genotype and phenotype may provide strong predictive biomarkers of adverse outcomes in premature infants.

Prediction of bronchopulmonary dysplasia by postnatal age in extremely premature infants

RATIONALE

Benefits of identifying risk factors for bronchopulmonary dysplasia in extremely premature infants include providing prognostic information, identifying infants likely to benefit from preventive strategies, and stratifying infants for clinical trial enrollment.

OBJECTIVES

To identify risk factors for bronchopulmonary dysplasia, and the competing outcome of death, by postnatal day; to identify which risk factors improve prediction; and to develop a Web-based estimator using readily available clinical information to predict risk of bronchopulmonary dysplasia or death.

METHODS

We assessed infants of 23-30 weeks' gestation born in 17 centers of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network and enrolled in the Neonatal Research Network Benchmarking Trial from 2000-2004.

MEASUREMENTS AND MAIN RESULTS

Bronchopulmonary dysplasia was defined as a categorical variable (none, mild, moderate, or severe). We developed and validated models for bronchopulmonary dysplasia risk at six postnatal ages using gestational age, birth weight, race and ethnicity, sex, respiratory support, and Fi(O(2)), and examined the models using a C statistic (area under the curve). A total of 3,636 infants were eligible for this study. Prediction improved with advancing postnatal age, increasing from a C statistic of 0.793 on Day 1 to a maximum of 0.854 on Day 28. On Postnatal Days 1 and 3, gestational age best improved outcome prediction; on Postnatal Days 7, 14, 21, and 28, type of respiratory support did so. A Web-based model providing predicted estimates for bronchopulmonary dysplasia by postnatal day is available at https://neonatal.rti.org.

CONCLUSIONS

The probability of bronchopulmonary dysplasia in extremely premature infants can be determined accurately using a limited amount of readily available clinical information.

Use of a body proportionality index for growth assessment of preterm infants

OBJECTIVE

To evaluate the utility of weight-for-length (defined as gm/cm(3), known as the "ponderal index") as a complementary measure of growth in infants in neonatal intensive care units (NICUs).

STUDY DESIGN

This was a secondary analysis of infants (n=1214) of gestational age 26 to 29 weeks at birth, included in a registry database (1991-2003), who had growth data at birth and discharge. Weight-for-age and weight-for-length were categorized as small (<10th percentile), appropriate, or large (>90th percentile).

RESULTS

Statistical agreement between the weight-for-age and weight-for-length measures was poor (kappa=0.02 at birth, 0.10 at discharge; Bowker test for symmetry, P< .0001). From birth to discharge, the percentage of small-for-age infants increased from 12% to 21%, the percentage of small-for-length infants decreased from 10% to 4%, the percentage of large-for-age infants remained similar (<1%), and the percentage of large-for-length infants increased from 5% to 17%. At discharge, 92% of the small-for-age infants were appropriate or large-for-length, and 19% of the appropriate-for-age infants were large-for-length.

CONCLUSIONS

Weight-for-age and weight-for-length are complementary measures. Weight-for-length or other measures of body proportionality should be considered for inclusion in routine growth monitoring of infants in the NICU.

Urinary NGAL in premature infants

Premature infants are at unique risk for developing acute kidney injury (AKI) due to incomplete nephrogenesis, early exposure to nephrotoxic medications, and coexisting conditions such as patent ductus arteriosus (PDA) and respiratory distress syndrome (RDS). Unfortunately, laboratory testing for the diagnosis of AKI in this population is problematic because of the physiology of both the placenta and the extra-uterine premature kidney. Recent research has led to the development of promising biomarkers for the early detection of AKI in children but there are no published reports in neonates. Our goal was to determine whether urine neutrophil gelatinase-associated lipocalin (NGAL) was detectable in premature infants and to correlate levels with gestational age, birth weight (BW), or indomethacin exposure. We enrolled 20 infants in four BW groups: 500-750, 751-1000, 1001-1250, and 1251-1500 g. Urine was collected every day for the first 14 d of life. Neonates born at earlier gestational ages and lower BWs had higher urine NGAL levels (p < 0.01). We conclude that urine NGAL is easily obtained in premature infants and that it correlates significantly with both BW and gestational age. The use of urinary NGAL as a biomarker of AKI in premature infants warrants further investigation.

Congenital bone marrow failure syndromes associated with protean developmental defects and leukemia

Congenital bone marrow failure syndromes are associated with a number of congenital abnormalities affecting a wide range of organ systems. The underlying molecular abnormalities that cause these disorders affect normal embryonic development during the critical organogenesis phase (weeks 4 to 8). These syndromes predispose patients to leukemia and other malignancies, and these genetic disorders may represent the first hit of at least two hits necessary for malignant transformation. The molecular defects underlying these diseases are just beginning to be understood; mechanisms suggested by recent research include DNA repair (FA-A, FA-G); abnormalities of the ribosomes (DBA, DC); to disorders of electron transport (FA-C, Pearson's syndrome, Barth's syndrome). Understanding these molecular mechanisms provides the knowledge necessary to develop better therapy, possibly including gene therapy, offering for the first time the potential for curing the hematologic manifestations of these illnesses.

A randomized, placebo-controlled trial of granulocyte colony-stimulating factor administration to newborn infants with neutropenia and clinical signs of early-onset sepsis

OBJECTIVE

To determine whether recombinant human granulocyte colony-stimulating factor (G-CSF) administration: 1) accelerates production of neutrophils; 2) increases bone marrow stored and precursor neutrophils; and 3) is safe in newborn infants with neutropenia and clinical signs of early-onset sepsis.

STUDY DESIGN

We randomized 20 infants with neutropenia and clinical signs of early-onset sepsis in the first 3 days of life to receive G-CSF (10 microg/kg/d) or placebo for 3 days. Entry criteria included neutropenia as defined by Manroe criteria, an elevated immature to total neutrophil ratio [(I/T) >/=0.25], and a requirement for ventilatory support. Cultures were obtained and antibiotics initiated on all study infants. Circulating absolute neutrophil count (ANC), I/T ratio, bone marrow neutrophil storage pool (NSP) and neutrophil proliferative pool (NPP), and plasma G-CSF concentrations were evaluated. Also, severity of illness as determined using the Score for Neonatal Acute Physiology (SNAP), morbidity, and mortality were recorded.

RESULTS

Circulating ANC increased in both G-CSF and placebo recipients by day 1. Also, the I/T neutrophil ratio decreased in both G-CSF and placebo recipients. There were no significant differences in the ANC or I/T ratio between the two groups during the study period. Similarly, bone marrow NSP and NPP did not differ between G-CSF and placebo recipients at study entry or day 2. No differences were observed in the secondary outcome measures including severity of illness, morbidity, and mortality.

CONCLUSIONS

Administration of recombinant G-CSF to infants with neutropenia and clinical signs of early-onset sepsis did not increase circulating ANC, or bone marrow NSP and NPP compared with placebo. No differences were observed between G-CSF and placebo recipients in severity of illness, morbidity, or mortality. No adverse effects of G-CSF administrations were noted.

The effect of erythropoietin on the transfusion requirements of preterm infants weighing 750 grams or less: a randomized, double-blind, placebo-controlled study

BACKGROUND

Clinical trials of erythropoietin (EPO) administration to preterm infants have not focused on infants weighing 750 gm or less, the population most likely to receive multiple transfusions because of large phlebotomy losses. It is unknown whether preterm infants weighing 750 gm or less will respond to EPO by accelerating erythropoiesis, or whether EPO administered to this population will decrease blood transfusions.

METHODS

We randomly assigned 28 extremely low birth weight preterm infants (mean +/- SEM: 24.7 +/- 0.3 weeks' gestation, 662 +/- 14 gm birth weight), in the first 72 hours of life, to receive either EPO (200 U/kg/day) or placebo for 14 days and administered transfusions only according to protocol over a 21-day study period. All infants received 1 mg/kg/day iron dextran in their total parenteral nutrition solution during the 14-day treatment period.

RESULTS

During the 21-day study period, a lower number and volume of transfusions were received by the EPO recipients (4.7 +/- 0.7 transfusions per patient and 70 +/- 11 ml/kg per patient) than by the placebo recipients (7.5 +/- 1.1 transfusions per patient and 112 +/- 17 ml/kg per patient; p < 0.05, EPO vs placebo), whereas hematocrits remained similar in the two groups. Reticulocyte counts were similar in both groups on day 1 but were greater in the EPO recipients on day 14 (EPO day 1, 351 +/- 53; EPO day 14, 359 +/- 40 x 10(3)/microl; placebo day 1, 334 +/- 64; placebo day 14, 120 +/- 10 x 10(3)/microl; p < 0.01, EPO vs placebo). Serum ferritin concentrations were similar in both groups at the beginning of the study but were greater in the placebo recipients by day 14 (EPO, 262 +/- 44 microg/L; placebo, 593 +/- 92 microg/L; p < 0.01). No adverse effects of EPO or iron were noted.

CONCLUSION

The combination of EPO and parenteral iron stimulates erythropoiesis in preterm infants weighing 750 gm or less and results in fewer transfusions during their first 3 weeks of life.

Regulation of interleukin-10 gene expression: possible mechanisms accounting for its upregulation and for maturational differences in its expression by blood mononuclear cells

Interleukin-10 (IL-10) downmodulates phagocytic immune responses and accentuates humoral responses. Human neonates exhibit broad immune deficits that parallel actions of IL-10. We postulated that IL-10 production would be diminished in neonatal blood cells. We found that IL-10 production by lipopolysaccharide-stimulated peripheral blood mononuclear cells (PBMNCs) in vitro was greater by adult cells than by term cells and preterm cells. Additional studies were undertaken to identify mechanisms responsible for the developmental differences in IL-10 gene expression. IL-10 transcription was present in freshly isolated adult and neonatal cells in the absence of detectable levels of transcript. Transcription rates were not different between adult and neonatal cells. IL-10 transcripts were approximately 40% more abundant in adult cells than in term cells and were consistent with differences in secreted protein; however, no differences were noted in mRNA stability. IL-10 half-life was 60 minutes for both adult and term PBMNCs. We conclude that up-regulation of IL-10 gene expression in PBMNCs is modulated at the post-transcriptional level, that IL-10 protein production and mRNA content are greater in activated cells from adults compared with those from neonates, and that maturational differences in IL-10 expression are not due to differences in transcription rate or mRNA stability. Maturational differences in IL-10 expression might be due to differences in subpopulations of cytokine-producing cells or differences in nucleo-cytoplasmic transport.

Possible mechanisms accounting for the growth factor independence of hematopoietic progenitors from umbilical cord blood

Hematopoietic progenitors obtained from the bone marrow of healthy adults fail to undergo clonogenic maturation in vitro if a source of hematopoietic growth factors is not included in the culture dishes. In contrast, a fraction of similarly purified progenitors obtained from umbilical cord blood undergo clonogenic maturation even in the absence of added growth factors. We postulated that production of hematopoietic growth factors within the culture dishes containing the progenitors of umbilical cord blood origin might be responsible. We postulated further, that this production might be by non-progenitor cells co-plated along with the progenitors, or alternatively by CD34+ cells themselves, or by cells clonally derived from CD34+ cells. To test these possibilities we first assessed the effect of including in the cultures neutralizing antibody directed against various growth factors. Inclusion of anti-granulocyte macrophage colony-stimulating factor (GM-CSF) and anti-interleukin-3 (IL-3) (but not anti-IL-2) significantly reduced the growth factor independence of cord blood progenitors (P < .005 and P < .01). Inclusion of both anti-GM-CSF and anti-IL-3 almost completely ablated the spontaneous colony growth (P < .001). Inclusion of IL-10 also reduced, in a concentration-dependent fashion, the spontaneous generation of umbilical cord blood-derived colonies. Transcripts for GM-CSF and IL-3 were detected, by reverse transcriptase-polymerase chain reaction (RT-PCR), in the CD34+ cells from cord blood and from adult marrow. When plated without added growth factors, however, the CD34+ cells of adult marrow origin failed to produce colonies, whereas 6% of cord blood CD34+ cells similarly cultured did so. When these growth factor independent colonies were plucked from culture, transcripts for GM-CSF and IL-3 were identified in all. We conclude that production of GM-CSF and IL-3 occurs within culture dishes containing hematopoietic progenitors of umbilical cord origin, and that this explains some of their apparently unique features of in vitro growth.

Effect of recombinant stem cell factor on clonogenic maturation and cycle status of human fetal hematopoietic progenitors

Studies were undertaken to delineate the actions of stem cell factor (SCF) on human fetal hematopoietic progenitors in vitro. Mononuclear cells from umbilical cord blood of term fetuses were "panned" immunologically, and the resulting hematopoietic progenitors were grown in methylcellulose culture containing various concentrations of SCF alone or in combination with other recombinant hematopoietic growth factors. Neutralizing antibodies to IL-3 and granulocyte-macrophage colony-stimulating factor were added to all plates to which recombinant IL-3 or granulocyte-macrophage colony-stimulating factor were not included to decrease any confounding effect resulting from production of small quantities of these factors within the culture plates. SCF, as a single agent, supported clonogenic maturation of fetal granulocyte-macrophage progenitors (granulocyte-macrophage colony-forming unit, p < 0.05), multipotent progenitors (CFU-MIX, p < 0.05), and erythroid progenitors (erythroid burst-forming unit, p < 0.05). When combined with subplateau concentrations (0.1 microgram/L) of IL-3 or granulocyte-macrophage colony-stimulating factor, SCF had an additive or synergistic effect on clonogenic maturation of granulocyte-macrophage colony-forming unit and CFU-MIX. When combined with higher concentrations (5.0 micrograms/L) of IL-3 or granulocyte-macrophage colony-stimulating factor, SCF generally did not enhance colony formation but did increase the number of cells per colony. Like other pleiotropic cytokines such as IL-6, IL-9, and IL-11, SCF had a broad spectrum of action of fetal hematopoietic progenitors.

Production of granulocyte colony-stimulating factor in vitro by monocytes from preterm and term neonates

We postulated that defective generation of granulocyte colony-stimulating factor (G-CSF) by cells of newborn infants might underlie their deficiencies in upregulating neutrophil production and function during bacterial infection. To test this, we isolated monocytes from the blood of preterm neonates, term neonates, and adults and, after stimulation with various concentrations of interleukin-1 alpha (IL-1 alpha) or lipopolysaccharide (LPS), quantified G-CSF concentrations in cell supernatants and G-CSF mRNA in cell lysates. When stimulated with plateau concentrations of IL-1 alpha for 24 hours, G-CSF concentrations were higher in supernatants of adult cells (8,699 +/- 5,529 pg/10(6) monocytes) than in those from term infants (2,557 +/- 442 pg, P < .05) or from preterm infants (879 +/- 348 pg, P < .05 v adults). When stimulated with plateau concentrations of LPS, supernatants of monocytes from preterm neonates had less G-CSF than did those from term neonates or adults. G-CSF mRNA content was low in cells from preterm infants, higher in those from term infants, and highest in those from adults. On the basis of the in vitro studies, we speculated that serum G-CSF concentrations might be less elevated in neutropenic neonates than in neutropenic adults. Indeed, serum concentrations were relatively low in all nonneutropenic subjects; 92 +/- 34 pg/mL (mean +/- SEM) in 10 preterm neonates, 114 +/- 21 pg/mL in 16 term neonates, and 45 +/- 13 pg/mL in 11 healthy adults. Serum concentrations were not elevated in 7 neutropenic neonates (39 +/- 17 pg/mL) but were in 8 neutropenic adults (2101 +/- 942 pg/mL, P < .05 v healthy adults). Other studies suggested that the lower G-CSF production in neonates is not counterbalanced by a heightened sensitivity of G-CSF--responsive progenitors to G-CSF. Therefore, we speculate that newborn infants, particularly those delivered prematurely, generate comparatively low quantities of G-CSF after inflammatory stimulation, and that this might constitute part of the explanation for their defective upregulation of neutrophil production and function during infection.

Diminished transcription of interleukin-8 by monocytes from preterm neonates

Developmental delays, which impair antibacterial host defense, are present in the neutrophil system of human preterm neonates. We hypothesized that diminished production of interleukin-8 (IL-8), a neutrophil chemotactic peptide, might in part be responsible for these defects. To test this, monocytes from the blood of preterm neonates, term neonates, and adults were isolated immunologically by "negative panning" and subsequently stimulated with interleukin-1 alpha (IL-1 alpha), tumor necrosis factor alpha (TNF-alpha), or lipopolysaccharide (LPS), after which IL-8 levels in the supernatants were measured by ELISA. Total cellular RNA was extracted and IL-8 mRNA was assessed by Northern blotting and by competitive polymerase chain reaction (PCR) analyses. After stimulation with IL-1 alpha, IL-8 accumulation was lowest in supernatants of monocytes from preterm neonates, intermediate in supernatants of monocytes from term neonates and greatest from monocytes of adults. Similarly, when stimulated with TNF-alpha or LPS, monocytes from preterm neonates produced less IL-8 than cells from term neonates and adults. These differences in IL-8 concentrations paralleled differences in IL-8 mRNA expression.

The failure of newborn mice infected with Escherichia coli to accelerate neutrophil production correlates with their failure to increase transcripts for granulocyte colony-stimulating factor and interleukin-6

We quantified circulating and storage neutrophils, their precursors and progenitors, and mRNA for some of the cytokines involved in granulocytopoiesis, in newborn and adult mice following intrapulmonary inoculation of Escherichia coli. Four hours following inoculation of adult and newborn mice with a quantity of organisms 2 logs below the LD100, all animals were neutropenic. After 24 h, adults had recovered from the neutropenia but neonates had not (p < 0.001). Accelerated neutrophil production was evident in the infected adults, and correlated with the appearance of granulocyte colony-stimulating factor (G-CSF) transcripts in the liver, spleen, and lung, and interleukin-6 (IL-6) transcripts in the spleen and lung. An increase in neutrophil production was not observed in the neonates, and none of their organs tested had transcripts for either G-CSF or IL-6, but they did have transcripts for cytokines not involved in granulocytopoiesis; macrophage colony-stimulating factor and its receptor (c-fms). We speculate that the failure to increase neutrophil production in infected neonatal mice is the result of failure to increase production of relevant cytokines.

Effect of interleukin-11 on cycling status and clonogenic maturation of fetal and adult hematopoietic progenitors

A recently cloned human cytokine, interleukin-11 (IL-11), has functional similarities to IL-6. We tested the hypothesis that the hematopoietic actions of IL-11 in vitro also resemble those of IL-6. The effect of IL-11 on the cell cycle status of fetal and adult hematopoietic progenitors was assessed using serum-free incubations followed by tritiated thymidine suicide studies. Its effect on clonogenic maturation was assessed by including IL-11, either as a single agent or with subplateau or plateau concentrations of other recombinant cytokines, in cultures that contained neutralizing monoclonal antibodies directed against relevant growth factors. Similar to IL-6, IL-11 resulted in accelerated cycling of fetal colony-forming units-mixed (CFU-MIX), CFU-granulocyte macrophage (CFU-GM), and erythroid burst-forming units (BFU-E). This effect was additive to that of submaximal, but not to plateau, concentrations of IL-6. However, no effect of IL-11 was observed on cycling status of adult progenitors. As a single agent, IL-11 failed to support clonal maturation of either fetal or adult progenitors. IL-11 was additive to GM-CSF in supporting clonal maturation of CFU-GM from adult marrow but not from fetal blood. We conclude that the in vitro hematopoietic actions of IL-11 on cell cycle status of hematopoietic progenitors resemble those of IL-6. However, unlike IL-6, IL-11 as a single agent failed to support clonal maturation of fetal CFU-GM, BFU-E, and CFU-MIX.

Defective production of interleukin-6 by monocytes: a possible mechanism underlying several host defense deficiencies of neonates

Several deficiencies in antibacterial defense have been described in neonates. Among those best characterized are delayed maturation of B cells into antibody producing cells, deficient T-cell maturation, and delayed cycling of hematopoietic progenitor cells after an infectious challenge. No unifying theory has been forwarded, however, to explain the concomitance of these three developmental deficiencies. IL-6, a cytokine produced primarily by monocytes and macrophages in response to stimulation by IL-1, is involved in the regulation of these three processes. Thus, we postulated that defective production of IL-6 could be a mechanism underlying these immune deficiencies of neonates. Indeed, we observed that a peak production, cells of five term neonates produced only one half as much IL-6 (14 120 +/- 2590 pg IL-6/10(6) monocytes) as those of five adults (28 940 +/- 1680 pg, p less than 0.001). Peak production was lower still by monocytes of six preterm neonates (7190 +/- 1400 pg, p less than 0.001 versus term). Production of IL-6 protein was inhibited by actinomycin D and the IL-6 mRNA content of monocytes from neonates, as assessed by competitive polymerase chain reaction, was less than that of adult monocytes. We speculate that defective IL-6 transcription might underlie some of the defects in immune regulation observed in neonates.

Administration of erythropoietin to newborn rats results in diminished neutrophil production

Very high concentrations of erythropoietin (epo), in clonogenic cultures, result in reduced production of neutrophils, and fetal progenitors are more sensitive to this effect of epo than are those of adults. However, the significance of this observation is unclear because no evidence of reduced neutrophil production has been presented following administration of recombinant epo to human or animal subjects. In the present study we injected newborn rats, beginning on the first day of life, with 20, 200, or 2,000 U epo/kg body weight, and measured serum epo concentrations after 2, 8, 24, or 48 hours. After selecting a dose that resulted in serum concentrations greater than 1,000 mU/mL (a concentration that resulted in down-modulation of neutrophil production from neonatal rat progenitors in vitro) other newborn rats were treated for 3 days with that dose (1,000 U epo/kg) or a vehicle control. Administration of epo resulted in increased hematocrits (P less than .001), reticulocyte counts (P less than .001), normoblasts/femur (P less than .05), and normoblasts/spleen (P less than .001). Recipients of epo also had more erythroid colony-forming units (CFU-E) (P less than .001) and higher CFU-E tritiated thymidine suicide rates (P less than .01) than did controls. However, femurs and spleens of epo recipients contained fewer postmitotic neutrophils (femur, P less than .01; spleen, P less than .01), proliferative neutrophils (femur, P less than .01; spleen, P less than .02), granulocyte-macrophage colony-forming units (CFU-GM) (P less than .005), and lower CFU-GM tritiated thymidine suicide rates (P less than .01). Seven and nine days after twice-daily administration of 2,000 U epo/kg, blood neutrophil concentrations had diminished (P less than .05). Thus, administration of high doses of recombinant epo to newborn rats resulted in diminished neutrophil production accompanying accelerated erythropoiesis.

Effect of interleukin-9 on clonogenic maturation and cell-cycle status of fetal and adult hematopoietic progenitors

We assessed the effect of interleukin-9 (IL-9) on clonogenic maturation and cell-cycle status of hematopoietic progenitors of fetal (umbilical cord blood) and adult (bone marrow) origin. As a single agent IL-9 supported, in a concentration-dependent fashion, maturation of burst-forming units-erythroid (BFU-E) of adult and fetal origin. However, only 1/3 the number of adult BFU-E colonies developed, as did in response to granulocyte-macrophage colony-stimulating factor (GM-CSF), and only 1/6 the number developed as did in response to IL-3. In contrast, the effect of IL-9 on fetal BFU-E colonies was equal to that of GM-CSF and IL-3. Synergistic effects of IL-9 with low concentrations (0.1 ng/mL) of GM-CSF and IL-3 were seen on adult BFU-E colony formation, but no effect was apparent at higher concentrations (1.0 ng/mL). In contrast, using fetal cells, synergistic effects of IL-9 with low and high concentrations of GM-CSF and IL-3 were apparent. Addition of IL-9 to plates containing fetal cells plus GM-CSF and IL-3 not only resulted in more BFU-E colonies, but also in more multicentered (greater than or equal to 10 individual centers) colonies, and more cells per colony. IL-9 had a wider spectrum of action on progenitors of fetal origin than on progenitors of adult origin, supporting the generation of fetal multipotent colony-forming unit (CFU)-Mix and CFU-GM colonies. Incubation with IL-9 did not accelerate cycling of adult or fetal BFU-E, CFU-Mix, or CFU-GM to the extent observed after incubation with IL-6. Thus, IL-9 primarily supported maturation of erythroid progenitors of adult origin, and its addition to plates containing GM-CSF and IL-3 (1.0 ng/mL) did not result in maturation of additional clones. In contrast, IL-9 had a wider spectrum of action on fetal progenitors and, when combined with IL-3 and GM-CSF, resulted in clonogenic maturation of progenitors that did not undergo maturation after stimulation with IL-3 and GM-CSF.