Epidemiology of bronchopulmonary dysplasia

Calcium absorption in very low birth weight infants with and without bronchopulmonary dysplasia

OBJECTIVE

To evaluate the effects of early bronchopulmonary dysplasia (BPD) on calcium (Ca) metabolism and growth in very low birth weight (VLBW) infants.

STUDY DESIGN

A dual-tracer, stable isotope method was used to assess Ca absorption in VLBW infants. Infants with early BPD received energy-dense feedings and mild fluid restriction.

RESULTS

Sixteen of 41 preterm infants were classified as having early BPD. Fractional Ca absorption (early BPD, 58.4 ± 4.6% versus no early BPD, 50.3 ± 4.0%, P = .2), total Ca absorption (early BPD, 127 ± 14 mg/kg/d versus no early BPD, 104 ± 9 mg/kg/d, P = .9), and Ca retention (early BPD, 99.6 ± 10.0 mg/kg/d versus no early BPD, 91.0 ± 9.8 mg/kg/d, P = .2) were similar among groups. There was no significant difference in weight gain, linear growth, or head circumference growth between groups.

CONCLUSIONS

The ability of VLBW infants with early BPD and fluid restriction to grow and accrete calcium is similar to those without early BPD. The use of high caloric density feedings in VLBW infants with early BPD can help achieve bone and overall growth outcomes close to those achievable in utero.

Etiology of Bronchopulmonary Dysplasia: Before Birth

Bronchopulmonary dysplasia affects thousands of infants annually with high attendant morbidity, mortality, and healthcare costs. Respiratory outcomes for preterm infants may be widely disparate even within the same medical center for infants of similar gestational ages. Given the high estimates for the heritability for bronchopulmonary dysplasia as measured at 36 weeks of postmenstrual age, the course of disease for a particular infant is likely heavily influenced by factors that operate prenatally or in the early postnatal period. In this review we discuss the etiologies of lung disease in the premature infant, including in utero, genetic, and epigenetic factors that may influence pulmonary outcomes.

Update in pediatrics: focus on fat-soluble vitamins

This article provides an update on fat-soluble vitamins (A, D, E, and K) in the healthy pediatric population and in children with chronic disease states that commonly cause deficiencies, specifically cystic fibrosis and cholestatic liver disease. For each fat-soluble vitamin, the biological function, nutrition availability, absorption, deficiency, toxic states, and monitoring parameters are defined.

The clustering of disorders in infants born before the 28th week of gestation

AIM

To see whether disorders prevalent in infants born extremely preterm cluster.

DESIGN

Observational cohort study.

SETTING

  University-affiliated newborn intensive care nurseries.

SUBJECTS

  One thousand two hundred and twenty-three infants born before the 28th week of gestation who survived until 36 weeks postmenstrual age when the diagnosis of bronchopulmonary dysplasia (BPD) could be made.

INTERVENTIONS

  None.

MAIN OUTCOME MEASURES

  Cerebral white matter damage (an echolucent lesion, or moderate or severe ventriculomegaly on a protocol cranial ultrasound scan), BPD, retinopathy of prematurity (ROP), necrotizing enterocolitis (NEC) and early and late bacteremia.

RESULTS

After adjustment for gestational age, children who had severe NEC (Bell stage IIIb) were at increased risk of cerebral white matter damage, severe ROP (stage 3+), and severe BPD (defined as both oxygen and ventilator dependent). Children who had early bacteremia were at increased risk of late bacteremia and severe ROP. Those who had severe ROP were at increased risk of severe BPD and both early and late bacteremia.

CONCLUSIONS

  Necrotizing enterocolitis is the disorder common to most of the clusters, but we do not know if its onset occurred before the others. Organ-damage-promoting substances, however, have been found in the circulation of newborn animals with bowel inflammation, supporting the view that NEC contributes to the damage of other organs.

Thioredoxin-interacting protein inhibits hypoxia-inducible factor transcriptional activity

Vascular endothelial growth factor (VEGF) is required for proper lung development and is transcriptionally regulated in alveolar epithelial cells by hypoxia-inducible factor (HIF). Previous findings in a newborn mouse model of bronchopulmonary dysplasia (BPD) suggest that thioredoxin-interacting protein (Txnip) is a novel regulator of VEGF expression. The present studies were designed to test the hypothesis that Txnip negatively regulates VEGF through effects on HIF-mediated gene expression. To test this hypothesis, we first examined the levels of VEGF and Txnip protein in the lungs of 1-day-old newborn mice and E19 embryos and detected a significant inverse correlation. To elucidate the mechanisms underlying this relationship, we studied the effects of Txnip overexpression on HIF-mediated transcription using murine lung epithelial (MLE-12) cells. Overexpression of Txnip inhibited HIF-mediated reporter activity in both hypoxia and room air. Suppression of HIF activity by Txnip seemed to be independent of the ability of Txnip to bind to thioredoxin. Thus, our studies support a model in which Txnip is a potentially critical regulator of HIF-mediated gene transcription in the murine lung. Alterations in Txnip expression could alter lung VEGF expression in prematurely born human infants and contribute to the development of BPD.

Oxygen and oxidative stress in bronchopulmonary dysplasia

AIMS

to summarize present knowledge regarding the relation between oxidative stress and development of bronchopulmonary dysplasia (BPD).

METHODS

relevant literature searched at Pubmed and other sources.

RESULTS

Oxidative stress is generated in a number of conditions and by a number of causes such as inflammation and hyperoxia. Ontogenic aspects are discussed. Oxidative stress as physiological regulators, its relation to transcription factors and inflammation is summarized. The role of oxygen and antioxidant therapy and newborn resuscitation for development and prevention of BPD as well as new therapeutic modes especially the use of growth factors, gene therapy and stem cells, are briefly discussed.

CONCLUSION

oxidative stress and BPD are associated. A better understanding of this association is necessary in order to reduce the severity and the incidence of the condition.

Deficits in lung alveolarization and function after systemic maternal inflammation and neonatal hyperoxia exposure

Systemic maternal inflammation contributes to preterm birth and is associated with development of bronchopulmonary dysplasia (BPD). Infants with BPD exhibit decreased alveolarization, diffuse interstitial fibrosis with thickened alveolar septa, and impaired pulmonary function. We tested the hypothesis that systemic prenatal LPS administration to pregnant mice followed by postnatal hyperoxia exposure is associated with prolonged alterations in pulmonary structure and function after return to room air (RA) that are more severe than hyperoxia exposure alone. Timed-pregnant C3H/HeN mice were dosed with LPS (80 microg/kg) or saline on gestation day 16. Newborn pups were exposed to RA or 85% O2 for 14 days and then to RA for an additional 14 days. Data were collected and analyzed on postnatal days 14 and 28. The combination of prenatal LPS and postnatal hyperoxia exposure generated a phenotype with more inflammation (measured as no. of macrophages per high-power field) than either insult alone at day 28. The combined exposures were associated with a diffuse fibrotic response [measured as hydroxyproline content (microg)] but did not induce a more severe developmental arrest than hyperoxia alone. Pulmonary function tests indicated that hyperoxia, independent of maternal exposure, induced compliance decreases on day 14 that did not persist after RA recovery. Either treatment alone or combined induced an increase in resistance on day 14, but the increase persisted on day 28 only in pups receiving the combined treatment. In conclusion, the combination of systemic maternal inflammation and neonatal hyperoxia induced a prolonged phenotype of arrested alveolarization, diffuse fibrosis, and impaired lung mechanics that mimics human BPD. This new model should be useful in designing studies of specific mechanisms and interventions that could ultimately be utilized to define therapies to prevent BPD in premature infants.