The association of early blood oxygenation with child development in preterm infants with acute respiratory disorders.

The potential negative impact of early blood oxygenation on development of specific cognitive and motor outcomes in children born at very low birth weight (VLBW; 1000-1500g) has not been examined even though these infants are exposed to varying durations and amounts of oxygen as part of their neonatal care. While this is the largest group of preterm infants, they receive much less research attention than extremely low birth weight infants (ELBW<1000g). Although neonatologists are questioning the routine use of oxygen therapy for all neonates, research has focused primarily on the more medically fragile ELBW infants. To date there are no systematic studies available to guide decision making for oxygen supplementation for a large segment of the preterm infant population. The aim of the present study was to determine if there is an association between blood oxygenation in the first 4h of life and specific cognitive and motor skills in preterm infants with acute respiratory disorders but no severe intracranial insult using a selected cohort from a longitudinal study children recruited in 1991 and 1992 designed to examine the role of biological immaturity as defined by gestational age and parenting in development. From this cohort, 55 children had acute respiratory disorders without severe intracranial insult. Of these, 35 children had at least one partial pressure of oxygen obtained from arterial blood (PaO2) during the first 4h of life as part of their clinical care. Higher early PaO2 values were associated with lower impulse control and attention skills in the elementary school age period. Models that were examined for relations between PaO2 values that also included birth weight and parenting quality across the first year of life revealed that higher PaO2 remained associated with impulse control but not attention skills. Birth weight was not associated with any outcomes. These results suggest that hyperoxia may be a risk factor for developmental problems that are not expressed until school age.

Benefits and risks of breastfeeding.

In the absence of significant, unpreventable risks, breastfeeding should be the norm for the nourishment of human infants and should, therefore, be encouraged for populations in all countries. Continued efforts of international and national agencies and healthcare professionals to aid and abet breastfeeding, reduce the risks that occur in some women during breastfeeding, provide the safest substitutes for human milk when that is necessary, and encourage further research into the posed questions should considerably improve the health of many children.

Activation of nuclear factor-kappaB signaling pathway by interleukin-1 after hypoxia/ischemia in neonatal rat hippocampus and cortex.

Perinatal hypoxia/ischemia (HI) is a common cause of neurological deficits in children. Interleukin-1 (IL-1) activity has been implicated in HI-induced brain damage. However, the mechanisms underlying its action in HI have not been characterized. We used a 7-day-old rat model to elucidate the role of nuclear factor-kappaB (NF-kappaB) activation in HI stimulation of IL-1 signaling. HI was induced by permanent ligation of the left carotid artery followed by 90 min of hypoxia (7.8% O(2)). Using ELISA assays, we observed increased cell death and caspase 3 activity in hippocampus and cortex 3, 6, 12, 24 and 48 h post-HI. IL-1beta protein expression increased, beginning at 3 h after HI and lasting until 24 h post-HI in hippocampus and 12 h post-HI in cortex. Intracerebroventricular injection of 2 microg IL-1 receptor antagonist (IL-1Ra) 2 h after HI significantly reduced cell death and caspase 3 activity. Electrophoretic mobility shift assay analyses of hippocampus and cortex after HI for NF-kappaB activity showed increased p65/p50 DNA-binding activity at 24 h post-HI. Western blot analyses showed significant nuclear translocation of p65. Protein expression levels of two known inflammatory agents, inducible nitric oxide synthase and cycloxygenase 2, known to be transcriptionally regulated by NF-kappaB, also increased at 24 h after HI. All these HI-induced changes were reversed by IL-1Ra blockade of IL-1 signaling, consistent with IL-1 triggering of inflammatory apoptotic outcomes via NF-kappaB transcriptional activation. The observed increase in cytoplasmic phosphorylated inhibitor kappaBalpha (IkappaBalpha) and nuclear translocation of Bcl-3 24 h after HI was also significantly attenuated by IL-1Ra blockade, suggesting that HI-induced IL-1 activation of NF-kappaB is via both the degradation of IkappaBalpha and the nuclear translocation of Bcl-3.

Effects of NF-kappaB oligonucleotide "decoys" on gene expression in P7 rat hippocampus after hypoxia/ischemia.

"Decoy" oligonucleotides can be used as gene-specific nuclear factor (NF-kappaB) inhibitors to regulate gene expression. We applied two different decoy oligonucleotides that contained the NF-kappaB binding consensus sequences present in the immunoglobulin G (IgG)-kappaB and Bcl-x promoter into 7-day-old (P7) rat lateral ventricles before hypoxia/ischemia (HI) and compared their effects on gene expression in hippocampi to saline-treated, scrambled decoy-treated, or untreated hippocampi exposed to HI. Left hippocampi were collected at 12 hr after HI. Electrophoretic mobility shift assays (EMSAs) showed that the two decoy treatments had different effects on NF-kappaB binding to the IgG-kappaB and Bcl-x promoter-specific consensus sequences, respectively. We assessed the decoys' effects on gene expression 12 hr after HI using ribonuclease protection assays (RPAs) and Affymetrix DNA microarrays. RPAs showed that both decoys significantly decreased interleukin (IL)-1alpha mRNA levels but had no impact on IL-1beta, IL-6, and IL-10 mRNA levels. IgG-kappaB decoys significantly decreased tumor necrosis factor (TNF)-alpha and TNF-beta mRNA levels compared to minimal changes after treatment with Bcl-x decoys. DNA microarray analyses showed that Bcl-x decoy treatment significantly decreased Bcl-x(L) mRNA levels. The decreased Bcl-x(L) mRNA levels after Bcl-x decoy treatment was confirmed by RPA analysis. DNA microarray data also indicated that several other genes were affected by both decoys. Our results suggest that different NF-kappaB decoy treatments could differentially regulate transcriptional responses to central nervous system trauma. Careful design of decoy sequences, however, is essential to acquire selective effects on cell death outcome.

Bcl-2 family members make different contributions to cell death in hypoxia and/or hyperoxia in rat cerebral cortex.

Hypoxic brain injury during fetal or neonatal development leads to damaged immature neurons and can result in cognitive or behavioral dysfunction. Hyperoxia therapy (treatment with oxygen) is commonly applied to infants with signs of perinatal hypoxia-anoxia. Both hypoxia and hyperoxia have been shown to result in apoptosis in the brains of rats in several animal models. One determinant of cellular commitment to cell death is the differential expression of the Bcl-2 family of proteins in response to trauma. Here, we characterize cell death and the expression of Bcl-2 homologous proteins in 7-day-old neonatal rat cerebral cortex after hypoxia (5% O(2) for 40 min) and/or hyperoxia (>95% O(2) for 2 h after hypoxia). The expression of Bcl-2 and Bcl-X(L), two anti-apoptotic proteins, decreased at 24 h after hypoxia. Bcl-X(L) increased after either hyperoxia or hypoxia+hyperoxia. We did not detect significant changes in the cytoplasmic levels of pro-apoptotic protein Bax after any of these three treatments. Using cell death ELISA and DNA FragEL assays, we observed increased cell death at 24h after hypoxia, hyperoxia or hypoxia+hyperoxia treatments. At 24 h after either hypoxia, hyperoxia or hypoxia+hyperoxia, caspase 3 activity also increased significantly. Our results suggest that both hypoxia and hyperoxia alone can induce cell death. The Bcl-2 --> cytochrome c --> caspase 3 pathway played a role in hypoxia-induced cell death, while other pathways may be involved in hyperoxia-induced cell death.

Expression of glutamate transporter, GABRA6, serine proteinase inhibitor 2 and low levels of glutamate and GABA in the brain of knock-out mouse for Canavan disease.

Canavan disease (CD) is an autosomal recessive leukodystrophy characterized by spongy degeneration of the brain. The clinical features of CD are hypotonia, megalencephaly, and mental retardation leading to early death. While aspartoacylase (ASPA) activity increases with age in the wild type mouse brain, there is no ASPA activity in the CD mouse brain. So far ASPA deficiency and elevated NAA have been ascribed with the CD. Other factors affecting the brain that result from ASPA deficiency may lead pathophysiology of CD. The NMR spectra and amino acid analysis showed lower levels of glutamate and gamma-aminobutyric acid in the CD mouse brain compared to the wild type. Microarray gene expression on CD mouse brain showed glutamate transporter-EAAT4 and gamma-aminobutyric acid-A receptor, subunit alpha6 (GABRA6) were lower 9.7- and 119.1-fold, respectively. Serine proteinase inhibitor 2 (Spi2) was 29.9-fold higher in the CD mouse brain compared to the wild type. The decrease of GABRA6 and high expression of Spi2 in CD mouse brain were also confirmed by real-time RT-PCR. This first report showing abnormal expression of EAAT4, GABRA6, Spi2 combined with lower levels of glutamate and GABA are likely to be associated with the pathophysiology of CD.

Attenuated transcriptional responses to oxidative stress in the aged rat brain.

The aged nervous system displays impaired cognitive functions, and these impairments are exacerbated in several neurodegenerative diseases. A role for oxidative stress has been suggested for several of these age-associated dysfunctions. In addition, recovery from more acute traumatic insults that also generate oxidative stress is impaired in the aged. Here we examine the response of aged rat hippocampi to normobaric hyperoxia treatments and demonstrate an attenuation in the DNA binding activity of the AP-1 and nuclear factor-kappa B transcription factors, which are important components of stress response signal transduction pathways and can determine shifts in cellular commitments to necrosis, apoptosis, or functional recovery in the central nervous system.