Low Rate of Spontaneous Closure in Premature Infants Discharged with a Patent Ductus Arteriosus: A Multicenter Prospective Study.

OBJECTIVES: To assess the rate of spontaneous closure and the incidence of adverse events in infants discharged home with a patent ductus arteriosus. STUDY DESIGN: In a prospective multicenter study, we enrolled 201 premature infants (gestational age of 23-32 weeks at birth) discharged home with a persistently patent ductus arteriosus (PDA) and followed their PDA status at 6-month intervals through 18 months of age. The primary study outcome was the rate and timing of spontaneous ductal closure. Secondary outcomes included rate of assisted closure and the incidence of serious adverse events. RESULTS: Spontaneous ductal closure occurred in 95 infants (47%) at 12 months and 117 infants (58%) by 18 months. Seventeen infants (8.4%) received assisted closure with surgical ligation or device assisted occlusion. Three infants died (1.5%). Although infants with spontaneous closure had a higher mean birth weight and gestational age compared with infants with a persistent PDA or assisted closure, we did not identify other factors predictive of spontaneous closure. CONCLUSIONS: Spontaneous closure of the PDA occurred in slightly less than one-half of premature infants discharged with a patent ductus by 1 year, lower than prior published reports. The high rate of assisted closure and/or adverse events in this population warrants close surveillance following discharge. TRIAL REGISTRATION: ClinicalTrials.gov: NCT02750228.

A comparison of the sexually dimorphic dexamethasone transcriptome in mouse cerebral cortical and hypothalamic embryonic neural stem cells.

Fetal exposure to synthetic glucocorticoids reprograms distinct neural circuits in the developing brain, often in a sex-specific manner, via mechanisms that remain poorly understood. To reveal whether such reprogramming is associated with select molecular signatures, we characterized the transcriptome of primary, embryonic mouse cerebral cortical and hypothalamic neural progenitor/stem cells derived from individual male and female embryos exposed to the synthetic glucocorticoid, dexamethasone. Gene expression profiling by RNA-Seq identified differential expression of common and unique genes based upon brain region, sex, and/or dexamethasone exposure. These gene expression datasets provide a unique resource that will inform future studies examining the molecular mechanisms responsible for region- and sex-specific reprogramming of the fetal brain brought about by in utero exposure to excess glucocorticoids.

Statins impact primary embryonic mouse neural stem cell survival, cell death, and fate through distinct mechanisms.

Statins inhibit HMG-CoA reductase, the rate-limiting enzyme in the cholesterol biosynthesis pathway (CBP), and are used for the prevention of cardiovascular disease. The anti-inflammatory effects of statins may also provide therapeutic benefits and have led to their use in clinical trials for preeclampsia, a pregnancy-associated inflammatory condition, despite their current classification as category X (i.e. contraindicated during pregnancy). In the developing neocortex, products of the CBP play essential roles in proliferation and differentiation of neural stem-progenitor cells (NSPCs). To understand how statins could impact the developing brain, we studied effects of pravastatin and simvastatin on primary embryonic NSPC survival, proliferation, global transcription, and cell fate in vitro. We found that statins dose dependently decrease NSPC expansion by promoting cell death and autophagy of NSPCs progressing through the G1 phase of the cell cycle. Genome-wide transcriptome analysis demonstrates an increase in expression of CBP genes following pravastatin treatment, through activation of the SREBP2 transcription factor. Co-treatment with farnesyl pyrophosphate (FPP), a CBP metabolite downstream of HMG-CoA reductase, reduces SREBP2 activation and pravastatin-induced PARP cleavage. Finally, pravastatin and simvastatin differentially alter NSPC cell fate and mRNA expression during differentiation, through a non-CBP dependent pathway.

Effects of antenatal glucocorticoids on the developing brain.

Glucocorticoids (GCs) regulate distinct physiological processes in the developing fetus, in particular accelerating organ maturation that enables the fetus to survive outside the womb. In preterm birth, the developing fetus does not receive sufficient exposure to endogenous GCs in utero for proper organ development predisposing the neonate to complications including intraventricular hemorrhage, respiratory distress syndrome (RDS) and necrotizing enterocolitis (NEC). Synthetic GCs (sGCs) have proven useful in the prevention of these complications since they are able to promote the rapid maturation of underdeveloped organs present in the fetus. While these drugs have proven to be clinically effective in the prevention of IVH, RDS and NEC, they may also trigger adverse developmental side effects. This review will examine the current clinical use of antenatal sGC therapy in preterm birth, their placental metabolism, and their effects on the developing brain.

Minireview: the impact of antenatal therapeutic synthetic glucocorticoids on the developing fetal brain.

The life-threatening, emotional, and economic burdens of premature birth have been greatly alleviated by antenatal glucocorticoid (GC) treatment. Antenatal GCs accelerate tissue development reducing respiratory distress syndrome and intraventricular hemorrhage in premature infants. However, they can also alter developmental processes in the brain and trigger adverse behavioral and metabolic outcomes later in life. This review summarizes animal model and clinical studies that examined the impact of antenatal GCs on the developing brain. In addition, we describe studies that assess glucocorticoid receptor (GR) action in neural stem/progenitor cells (NSPCs) in vivo and in vitro. We highlight recent work from our group on two GR pathways that impact NSPC proliferation, ie, a nongenomic GR pathway that regulates gap junction intercellular communication between coupled NSPCs through site-specific phosphorylation of connexin 43 and a genomic pathway driven by differential promoter recruitment of a specific GR phosphoisoform.