Cerebral white matter damage in the preterm infant: pathophysiology and risk factors

Two risk assessment models for predicting white matter injury in extremely preterm infants

BACKGROUND

Extremely preterm infants (EPIs) are at high-risk of white matter injury (WMI), leading to long-term neurodevelopmental impairments. We aimed to develop nomograms for WMI.

METHODS

The study included patients from 31 provinces, spanning ten years. 6074 patients before 2018 were randomly divided into a training and internal validation group (7:3). The external validation group comprised 1492 patients from 2019. Predictors were identified using the least absolute shrinkage and selection operator (LASSO) and multivariable logistic regression and nomograms were constructed. Models' performance was evaluated using receiver operating characteristic (ROC), decision curve analysis (DCA) and calibration curves.

RESULTS

The prenatal nomogram included multiple gestation, premature rupture of membranes (PROM), chorioamnionitis, prenatal glucocorticoids, hypertensive disorder complicating pregnancy (HDCP) and Apgar 1 min, with area under the curve (AUC) of 0.805, 0.816 and 0.799 in the training, internal validation and external validation group, respectively. Days of mechanical ventilation (MV), shock, patent ductus arteriosus (PDA) ligation, intraventricular hemorrhage (IVH) grade III-IV, septicemia, hypothermia and necrotizing enterocolitis (NEC) stage II-III were identified as postpartum predictors. The AUCs were 0.791, 0.813 and 0.823 in the three groups, respectively. DCA and calibration curves showed good clinical utility and consistency.

CONCLUSION

The two nomograms provide clinicians with precise and efficient tools for prediction of WMI.

IMPACT

This study is a large-sample multicenter study, spanning 10 years. The two nomograms are convenient for identifying high-risk infants early, allowing for reducing poor prognosis.

Inosine pretreatment of pregnant rats ameliorates maternal inflammation-mediated hypomyelination in pups via microglia polarization switch

Periventricular leukomalacia (PVL) is a neurological condition observed in premature infants, characterized by hypomyelination and activation of microglia. Maternal inflammation-induced brain injury in offspring significantly contributes to the development of PVL. Currently, there are no clinical pharmaceutical interventions available for pregnant women to prevent maternal inflammation-mediated brain injury in their offspring. Inosine has been shown to modulate the immune response in diverse stressful circumstances, such as injury, ischemia, and inflammation. The aim of this investigation was to examine the potential prophylactic impact of inosine on offspring PVL induced by maternal inflammation. This was accomplished by administering a 1 mg/ml inosine solution (40 ml daily) to pregnant Sprague-Dawley (SD) rats for 16 consecutive days prior to their intraperitoneal injection of lipopolysaccharide (350 µg/kg, once a day, for two days). The results showed that maternal inosine pretreatment significantly reversed the reduction in MBP and CNPase (myelin-related markers), CC-1 and Olig2 (oligodendrocyte-related markers) in their PVL pups (P7), suggesting that inosine administration during pregnancy could improve hypomyelination and enhance the differentiation of oligodendrocyte precursor cells (OPCs) in their PVL pups. Furthermore, the protective mechanism of inosine against PVL is closely associated with the activation and polarization of microglia. This is evidenced by a notable reduction in the quantity of IBA 1-positive microglia, a decrease in the level of CD86 (a marker for M1 microglia), an increase in the level of Arg 1 (a marker for M2 microglia), as well as a decrease in the level of pro-inflammatory factors TNF-α, IL-1β, and IL-6, and an increase in the level of anti-inflammatory factors IL-4 and IL-10 in the brain of PVL pups following maternal inosine pretreatment. Taken together, inosine pretreatment of pregnant rats can improve hypomyelination in their PVL offspring by triggering the M1/M2 switch of microglia.

Oligodendrocyte Progenitor Cell Transplantation Ameliorates Preterm Infant Cerebral White Matter Injury in Rats Model

Background

Cerebral white matter injury (WMI) is the most common brain injury in preterm infants, leading to motor and developmental deficits often accompanied by cognitive impairment. However, there is no effective treatment. One promising approach for treating preterm WMI is cell replacement therapy, in which lost cells can be replaced by exogenous oligodendrocyte progenitor cells (OPCs).

Methods

This study developed a method to differentiate human neural stem cells (hNSCs) into human OPCs (hOPCs). The preterm WMI animal model was established in rats on postnatal day 3, and OLIG2+/NG2+/PDGFRα+/O4+ hOPCs were enriched and transplanted into the corpus callosum on postnatal day 10. Then, histological analysis and electron microscopy were used to detect lesion structure; behavioral assays were performed to detect cognitive function.

Results

Transplanted hOPCs survived and migrated throughout the major white matter tracts. Morphological differentiation of transplanted hOPCs was observed. Histological analysis revealed structural repair of lesioned areas. Re-myelination of the axons in the corpus callosum was confirmed by electron microscopy. The Morris water maze test revealed cognitive function recovery.

Conclusion

Our study showed that exogenous hOPCs could differentiate into CC1+ OLS in the brain of WMI rats, improving their cognitive functions.

Profiling analysis reveals the potential contribution of long non-coding RNAs to preterm white matter injury

AIMS

The aim of this study was to investigate the molecular mechanism underlying preterm white matter injury (WMI) via the identification and functional analysis of differentially expressed long non-coding RNAs (lncRNAs) and mRNAs.

MAIN METHODS

A neonatal rat model of preterm WMI was established by ligating the common carotid artery and hypoxia induction. RNA sequencing was performed to analyze gene expression profiles of brain samples. Gene Ontology (GO) and Kyoto Encyclopedia of Genes (KEGG) analyses were performed to evaluate functions of target mRNAs. A co-expression network was generated to explore regulatory mechanisms.

KEY FINDINGS

In total, 210 lncRNAs and 619 mRNAs were differentially expressed between the preterm WMI group and the sham group. Based on GO and KEGG analyses, enriched pathways included the apoptotic signaling pathway, vascular endothelial growth factor (VEGF) signaling pathway, natural killer cell-mediated cytotoxicity pathway, and the autophagy pathway.

SIGNIFICANCE

Differentially expressed lncRNAs and mRNAs in the brain tissues of preterm WMI model were identified, and the biological processes were closely associated with the development of preterm WMI, thus being considered potential targets for future studies.

The prognostic value of NIRS in preterm infants with (suspected) late-onset sepsis in relation to long term outcome: A pilot study

Late-onset sepsis is frequently seen in preterm infants and is associated with poor neurodevelopmental outcome. White matter damage is proposed as substrate of poor outcome, with contributing factors as regional hypoxia and effects of cytokines on oligodendrocytes. We investigated the relation between cerebral oxygenation during (suspected) late-onset sepsis and neurodevelopmental outcome. Prospective cohort study, including preterm infants (gestational age <32 weeks and/or birthweight <1500 grams) with (suspected) late-onset sepsis underwent NIRS registration during the first 72 hours of suspected late-onset sepsis. At two years corrected age neurodevelopment was scored using the Bayley Scales of Infant Development-II. Thirty-two infants were included. Twenty-seven infants were identified with proven late-onset sepsis and five infants had clinical sepsis without positive blood culture. In this study, late-onset sepsis was predominantly caused by coagulase negative staphylococci (CoNS) (72%). All NIRS values were within normal limits. No association was found between NIRS and impaired neurodevelopmental outcome (n = 4) at corrected age two years: composite cognitive score 105 (80-115), composite motor score 103 (82-118) (median and range). In this pilot study, late-onset sepsis (predominantly caused by CoNS with a relatively mild clinical course), was not associated with aberrant NIRS values, nor with impaired neurodevelopmental outcome. Further research might establish our findings and elucidate effects of other micro-organisms on cerebral perfusion.

Inhibitory Effect of LPS on the Proliferation of Oligodendrocyte Precursor Cells through the Notch Signaling Pathway in Intrauterine Infection-induced Rats

Periventricular white matter injury (PWMI) is very common in survivors of premature birth, and the final outcomes are a reduction in myelinated neurons leading to white matter hypomyelination. How and (or) why the oligodendrocyte lineage develops abnormally and myelination is reduced is a hot topic in the field. This study focuses on the effect of intrauterine inflammation on the proliferation of oligodendrocyte lineage cells and the underlying mechanisms. Lipopolysaccharide (LPS) (300 μg/kg) was intraperitoneally injected into pregnant Sprague-Dawley rats at embryonic days 19 and 20 to establish a rat model of intrauterine infection-induced white matter injury. Corpus callosum tissues were collected at postnatal day 14 (P14) to quantify the number of oligodendrocytes, the number and proliferation of oligodendrocyte precursor cells (OPCs), and the expression of myelin proteins (MBP and PLP). Furthermore, the expression of Wnt and Notch signaling-related proteins was analyzed. The results showed that the number of oligodendrocytes in the corpus callosum tissues of LPS-treated rats was reduced, and the expression levels of myelinating proteins were down-regulated. Further analysis showed that the Notch signaling pathway was down-regulated in the LPStreated group. These results indicate that intrauterine LPS may inhibit the proliferation of OPCs by down-regulating the Notch rather than the Wnt signaling pathway, leading to hypomyelination of white matter.

Magnesium Sulfate Prevents Neurochemical and Long-Term Behavioral Consequences of Neonatal Excitotoxic Lesions: Comparison Between Male and Female Mice

Magnesium sulfate (MgSO4) administration to mothers at risk of preterm delivery is proposed as a neuroprotective strategy against neurological alterations such as cerebral palsy in newborns. However, long-term beneficial or adverse effects of MgSO4 and sex-specific sensitivity remain to be investigated. We conducted behavioral and neurochemical studies of MgSO4 effects in males and females, from the perinatal period to adolescence in a mouse model of cerebral neonatal lesion. The lesion was produced in 5-day-old (P5) pups by ibotenate intracortical injection. MgSO4 (600 mg/kg, i.p.) prior to ibotenate prevented lesion-induced sensorimotor alterations in both sexes at P6 and P7. The lesion increased glutamate level at P10 in the prefrontal cortex, which was prevented by MgSO4 in males. In neonatally lesioned adolescent mice, males exhibited more sequelae than females in motor and cognitive functions. In the perirhinal cortex of adolescent mice, the neonatal lesion induced an increase in vesicular glutamate transporter 1 density in males only, which was negatively correlated with cognitive scores. Long-term sequelae were prevented by neonatal MgSO4 administration. MgSO4 never induced short- or long-term deleterious effect on its own. These results also strongly suggest that sex-specific neuroprotection should be foreseen in preterm infants.

Antenatal and intrapartum interventions for preventing cerebral palsy: an overview of Cochrane systematic reviews

BACKGROUND

Cerebral palsy is an umbrella term encompassing disorders of movement and posture, attributed to non-progressive disturbances occurring in the developing fetal or infant brain. As there are diverse risk factors and causes, no one strategy will prevent all cerebral palsy. Therefore, there is a need to systematically consider all potentially relevant interventions for their contribution to prevention.

OBJECTIVES

To summarise the evidence from Cochrane reviews regarding the effects of antenatal and intrapartum interventions for preventing cerebral palsy.

METHODS

We searched the Cochrane Database of Systematic Reviews on 7 August 2016, for reviews of antenatal or intrapartum interventions reporting on cerebral palsy. Two authors assessed reviews for inclusion, extracted data, assessed review quality, using AMSTAR and ROBIS, and quality of the evidence, using the GRADE approach. We organised reviews by topic, and summarised findings in text and tables. We categorised interventions as effective (high-quality evidence of effectiveness); possibly effective (moderate-quality evidence of effectiveness); ineffective (high-quality evidence of harm or of lack of effectiveness); probably ineffective (moderate-quality evidence of harm or of lack of effectiveness); and no conclusions possible (low- to very low-quality evidence).

MAIN RESULTS

We included 15 Cochrane reviews. A further 62 reviews pre-specified the outcome cerebral palsy in their methods, but none of the included randomised controlled trials (RCTs) reported this outcome. The included reviews were high quality and at low risk of bias. They included 279 RCTs; data for cerebral palsy were available from 27 (10%) RCTs, involving 32,490 children. They considered interventions for: treating mild to moderate hypertension (two) and pre-eclampsia (two); diagnosing and preventing fetal compromise in labour (one); preventing preterm birth (four); preterm fetal maturation or neuroprotection (five); and managing preterm fetal compromise (one). Quality of evidence ranged from very low to high. Effective interventions: high-quality evidence of effectiveness There was a reduction in cerebral palsy in children born to women at risk of preterm birth who received magnesium sulphate for neuroprotection of the fetus compared with placebo (risk ratio (RR) 0.68, 95% confidence interval (CI) 0.54 to 0.87; five RCTs; 6145 children). Probably ineffective interventions: moderate-quality evidence of harm There was an increase in cerebral palsy in children born to mothers in preterm labour with intact membranes who received any prophylactic antibiotics versus no antibiotics (RR 1.82, 95% CI 0.99 to 3.34; one RCT; 3173 children). There was an increase in cerebral palsy in children, who as preterm babies with suspected fetal compromise, were born immediately compared with those for whom birth was deferred (RR 5.88, 95% CI 1.33 to 26.02; one RCT; 507 children). Probably ineffective interventions: moderate-quality evidence of lack of effectiveness There was no clear difference in the presence of cerebral palsy in children born to women at risk of preterm birth who received repeat doses of corticosteroids compared with a single course (RR 1.03, 95% CI 0.71 to 1.50; four RCTs; 3800 children). No conclusions possible: low- to very low-quality evidence Low-quality evidence found there was a possible reduction in cerebral palsy for children born to women at risk of preterm birth who received antenatal corticosteroids for accelerating fetal lung maturation compared with placebo (RR 0.60, 95% CI 0.34 to 1.03; five RCTs; 904 children). There was no clear difference in the presence of cerebral palsy with interventionist care for severe pre-eclampsia versus expectant care (RR 6.01, 95% CI 0.75 to 48.14; one RCT; 262 children); magnesium sulphate for pre-eclampsia versus placebo (RR 0.34, 95% CI 0.09 to 1.26; one RCT; 2895 children); continuous cardiotocography for fetal assessment during labour versus intermittent auscultation (average RR 1.75, 95% CI 0.84 to 3.63; two RCTs; 13,252 children); prenatal progesterone for prevention of preterm birth versus placebo (RR 0.14, 95% CI 0.01 to 3.48; one RCT; 274 children); and betamimetics for inhibiting preterm labour versus placebo (RR 0.19, 95% CI 0.02 to 1.63; one RCT; 246 children).Very low-quality found no clear difference for the presence of cerebral palsy with any antihypertensive drug (oral beta-blockers) for treatment of mild to moderate hypertension versus placebo (RR 0.33, 95% CI 0.01 to 8.01; one RCT; 110 children); magnesium sulphate for prevention of preterm birth versus other tocolytic agents (RR 0.13, 95% CI 0.01 to 2.51; one RCT; 106 children); and vitamin K and phenobarbital prior to preterm birth for prevention of neonatal periventricular haemorrhage versus placebo (RR 0.77, 95% CI 0.33 to 1.76; one RCT; 299 children).

AUTHORS' CONCLUSIONS

This overview summarises evidence from Cochrane reviews on the effects of antenatal and intrapartum interventions on cerebral palsy, and can be used by researchers, funding bodies, policy makers, clinicians and consumers to aid decision-making and evidence translation. We recommend that readers consult the included Cochrane reviews to formally assess other benefits or harms of included interventions, including impacts on risk factors for cerebral palsy (such as the reduction in intraventricular haemorrhage for preterm babies following exposure to antenatal corticosteroids).Magnesium sulphate for women at risk of preterm birth for fetal neuroprotection can prevent cerebral palsy. Prophylactic antibiotics for women in preterm labour with intact membranes, and immediate rather than deferred birth of preterm babies with suspected fetal compromise, may increase the risk of cerebral palsy. Repeat doses compared with a single course of antenatal corticosteroids for women at risk of preterm birth do not clearly impact the risk of cerebral palsy.Cerebral palsy is rarely diagnosed at birth, has diverse risk factors and causes, and is diagnosed in approximately one in 500 children. To date, only a small proportion of Cochrane reviews assessing antenatal and intrapartum interventions have been able to report on this outcome. There is an urgent need for long-term follow-up of RCTs of interventions addressing risk factors for cerebral palsy, and consideration of the use of relatively new interim assessments (including the General Movements Assessment). Such RCTs must be rigorous in their design, and aim for consistency in cerebral palsy outcome measurement and reporting to facilitate pooling of data, to focus research efforts on prevention.

Microglia-derived IL-1β contributes to axon development disorders and synaptic deficit through p38-MAPK signal pathway in septic neonatal rats

BACKGROUND

Axon development plays a pivotal role in the formation of synapse, nodes of Ranvier, and myelin sheath. Interleukin-1β (IL-1β) produced by microglia may cause myelination disturbances through suppression of oligodendrocyte progenitor cell maturation in the septic neonatal rats. Here, we explored if a microglia-derived IL-1β would disturb axon development in the corpus callosum (CC) following lipopolysaccharide (LPS) administration, and if so, whether it is associated with disorder of synapse formation in the cerebral cortex and node of Ranvier.

METHODS

Sprague-Dawley rats (1-day old) in the septic model group were intraperitoneally administrated with lipopolysaccharide (1 mg/kg) and then sacrificed for detection of IL-1β, interleukin-1 receptor (IL-1R₁), neurofilament-68, neurofilament-160, and neurofilament-200, proteolipid, synaptophysin, and postsynaptic density 95 (PSD95) expression by western blotting and immunofluorescence. Electron microscopy was conducted to observe alterations of axonal myelin sheath and synapses in the cortex, and proteolipid expression was assessed using in situ hybridization. The effect of IL-1β on neurofilament and synaptophysin expression in primary neuron cultures was determined by western blotting and immunofluorescence. P38-MAPK signaling pathway was investigated to determine whether it was involved in the inhibition of IL-1β on neurofilament and synaptophysin expression.

RESULTS

In 1-day old septic rats, IL-1β expression was increased in microglia coupled with upregulated expression of IL-1R₁ on the axons. The expression of neurofilament-68, neurofilament-160, and neurofilament-200 (NFL, NFM, NFH) and proteolipid (PLP) was markedly reduced in the CC at 7, 14, and 28 days after LPS administration. Simultaneously, cortical synapses and mature oligodendrocytes were significantly reduced. By electron microscopy, some axons showed smaller diameter and thinner myelin sheath with damaged ultrastructure of node of Ranvier compared with the control rats. In the cerebral cortex of LPS-injected rats, some axo-dendritic synapses appeared abnormal looking as manifested by the presence of swollen and clumping of synaptic vesicles near the presynaptic membrane. In primary cultured neurons incubated with IL-1β, expression of NFL, NFM, and synaptophysin was significantly downregulated. Furthermore, p38-MAPK signaling pathway was implicated in disorder of axon development and synaptic deficit caused by IL-1β treatment.

CONCLUSIONS

The present results suggest that microglia-derived IL-1β might suppress axon development through activation of p38-MAPK signaling pathway that would contribute to formation disorder of cortical synapses and node of Ranvier following LPS exposure.

Melatonin for women in pregnancy for neuroprotection of the fetus

BACKGROUND

Melatonin is an antioxidant with anti-inflammatory and anti-apoptotic effects. Animal studies have supported a fetal neuroprotective role for melatonin when administered maternally. It is important to assess whether melatonin, given to the mother, can reduce the risk of neurosensory disabilities (including cerebral palsy) and death, associated with fetal brain injury, for the preterm or term compromised fetus.

OBJECTIVES

To assess the effects of melatonin when used for neuroprotection of the fetus.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2016).

SELECTION CRITERIA

We planned to include randomised controlled trials and quasi-randomised controlled trials comparing melatonin given to women in pregnancy (regardless of the route, timing, dose and duration of administration) for fetal neuroprotection with placebo, no treatment, or with an alternative agent aimed at providing fetal neuroprotection. We also planned to include comparisons of different regimens for administration of melatonin.

DATA COLLECTION AND ANALYSIS

Two review authors planned to independently assess trial eligibility, trial quality and extract the data.

MAIN RESULTS

We found no randomised trials for inclusion in this review. One study is ongoing.

AUTHORS' CONCLUSIONS

As we did not identify any randomised trials for inclusion in this review, we are unable to comment on implications for practice at this stage.Although evidence from animals studies has supported a fetal neuroprotective role for melatonin when administered to the mother during pregnancy, no trials assessing melatonin for fetal neuroprotection in pregnant women have been completed to date. However, there is currently one ongoing randomised controlled trial (with an estimated enrolment target of 60 pregnant women) which examines the dose of melatonin, administered to women at risk of imminent very preterm birth (less than 28 weeks' gestation) required to reduce brain damage in the white matter of the babies that were born very preterm.Further high-quality research is needed and research efforts should directed towards trials comparing melatonin with either no intervention (no treatment or placebo), or with alternative agents aimed at providing fetal neuroprotection (such as magnesium sulphate for the very preterm infant). Such trials should evaluate maternal and infant short- and longer-term outcomes (including neurosensory disabilities such as cerebral palsy), and consider the costs of care.

Prognosis of psychomotor and mental development in premature infants by early cranial ultrasound

Background

It is of high incidence of brain injuries in premature infants, so it is necessary to diagnose and treat the brain injury early for neonatal clinical practice. We are aimed to investigate the relationship between early postnatal cranial ultrasonography and psychomotor and mental development in prematrue infants at the age of 12 months.

Methods

Two-hundred and eight premature infants were selected and underwent follow-up from January, 2007 to November, 2012. Cranial ultrasonography was performed on them. The developmental outcomes of these premature infants at the age of 12 months were assessed by the psychomotor developmental index (PDI) scale and mental development index (MDI). The relationship between ultrasonic gray-scale value and PDI and MDI was analyzed.

Results

The worse prognosis for psychomotor and mental development was associated with the gestational age, Apgar score(1 min), gender, chorioamnionitis, duration of mechanical ventilation and duration of mechanic ventilation. The differences between the prognosis of psychomotor and mental development, and peri-intraventricular hemorrhage (PIVH) and periventricular white matter damage (PWMD), were statistically significant (P < 0.05). There were also significant differences between the early postnatal ultrasonic gray-scale value and prognoses of both psychomotor development and mental development (P < 0.05). There were negative correlations between ultrasonic gray-scale and both PDI and MDI (r = −0.753, P < 0.05; r = −0.764, P < 0.05).

Conclusions

The early postnatal cranial ultrasonography can assist to predict the prognosis of psychomotor and mental development for premature infants. The higher grade of PIVH and PWMD was associated with the worse prognosis of psychomotor and mental development.

Current research suggests that the future looks brighter for cerebral oxygenation monitoring in preterm infants

Brain injuries remain a significant problem for preterm infants, despite extensive physiological monitoring. Near infrared spectroscopy (NIRS) monitoring in the neonatal intensive care unit has to date remained limited to research activities.

CONCLUSION

This review highlights the increasing clinical application of NIRS in delivery suites and neonatal units. Four randomised controlled trials incorporating NIRS monitoring suggest that the future may indeed be brighter for this technology in the care of very preterm infants.

Could cord blood cell therapy reduce preterm brain injury?

Major advances in neonatal care have led to significant improvements in survival rates for preterm infants, but this occurs at a cost, with a strong causal link between preterm birth and neurological deficits, including cerebral palsy (CP). Indeed, in high-income countries, up to 50% of children with CP were born preterm. The pathways that link preterm birth and brain injury are complex and multifactorial, but it is clear that preterm birth is strongly associated with damage to the white matter of the developing brain. Nearly 90% of preterm infants who later develop spastic CP have evidence of periventricular white matter injury. There are currently no treatments targeted at protecting the immature preterm brain. Umbilical cord blood (UCB) contains a diverse mix of stem and progenitor cells, and is a particularly promising source of cells for clinical applications, due to ethical and practical advantages over other potential therapeutic cell types. Recent studies have documented the potential benefits of UCB cells in reducing brain injury, particularly in rodent models of term neonatal hypoxia–ischemia. These studies indicate that UCB cells act via anti-inflammatory and immuno-modulatory effects, and release neurotrophic growth factors to support the damaged and surrounding brain tissue. The etiology of brain injury in preterm-born infants is less well understood than in term infants, but likely results from episodes of hypoperfusion, hypoxia–ischemia, and/or inflammation over a developmental period of white matter vulnerability. This review will explore current knowledge about the neuroprotective actions of UCB cells and their potential to ameliorate preterm brain injury through neonatal cell administration. We will also discuss the characteristics of UCB-derived from preterm and term infants for use in clinical applications.

Serious periventricular white matter injury has a significant effect on the voiding pattern of preterm infants

AIM

To evaluate the effect of serious periventricular white matter injury (PWMI) on the voiding patterns of preterm infants.

METHODS

Free voiding was continuously observed for eight hours in 19 preterm infants with serious PWMI and 16 infants without PWMI. The infants had a gestational age of 32-35 weeks and a postnatal age of 9-15 days. Voiding frequency, voided volume, postvoid residual volume, empty voiding, awake voiding and interrupted voiding were recorded and compared between the two groups of infants.

RESULTS

The voiding frequency ((5.1 ± 1.0) vs. (7.0 ± 1.1)), awake voiding percentage ((23 ± 11)% vs. (42 ± 7)%) and empty voiding percentage (lower quartile = 16% vs. 28%, median = 20% vs. 33%, upper quartile = 28% vs. 40%) were significantly lower, while the voided volume ((19.9 ± 6.6) mL vs.(15.9 ± 5.3) mL)and postvoid residual volume (lower quartile = 1 mL. vs. 0 mL., median = 3 mL. vs. 2 mL., upper quartile = 3 mL. vs. 2 mL.) were significantly higher in the injured preterm infants, compared with the healthy infants (p < 0.05).

CONCLUSION

Serious PWMI has a significant effect on the voiding pattern of preterm infants, and the senior nerve centre plays a role in the voiding reflex of preterm infants.

Maternal exposure to lipopolysaccharide leads to transient motor dysfunction in neonatal rats

Epidemiological and experimental data implicate maternal infection and inflammation in the etiology of brain white matter injury, which may lead to cerebral palsy in preterm newborns. Our aim was to investigate motor development of the offspring after maternal administration of lipopolysaccharide (LPS). Wistar rats were intraperitoneally injected with Escherichia coli LPS or saline on gestational days 19 and 20. From birth to 3 weeks, pups were tested for neurobehavioral development, neurological signs and reflexes. From 3 to 6 weeks, motor coordination was investigated. At 4 months, animals were tested for locomotion. Brain myelination was assessed by myelin basic protein immunohistochemistry. Days of appearance of several neurological reflexes were significantly delayed, and neonate LPS pups displayed retarded performance in righting, gait and negative geotaxis. At the juvenile stage, LPS animals showed important impairment in coordination. However, although the LPS group performed worse in most tests, they reached vehicle levels by 5 weeks. At 4 months, LPS animals did not show variations in locomotion performances compared to vehicle. No myelination differences have been observed in the brains at adulthood. Maternal LPS administration results in delayed motor development even though these alterations fade to reach control level by 5 weeks. Motor impairments observed at the early stage in this study could be linked to previously reported hypomyelination of the white matter induced by maternal LPS challenge in the neonates. Finally, the normal myelination shown here at adulthood may explain the functional recovery of the animals and suggest either a potential remyelination of the brain or a delayed myelination in LPS pups.

Perinatal immunoproteins predict the risk of cerebral palsy in preterm children

OBJECTIVE

To investigate whether blood cytokines during the perinatal period predict the risk of cerebral palsy (CP) in preterm infants.

METHODS

This prospective cohort study comprised 169 children born before 32 weeks of gestation. Cord blood was drawn at birth, and 109 cytokines were analyzed using microarrays. Eleven cytokines were further measured from both cord and peripheral blood on days 1 and 7. Cerebral palsy was confirmed at 5 years of age.

RESULTS

Cerebral palsy was diagnosed in 19 children. Five clusters of cord blood cytokines were scored using factor analysis. According to logistic regression analysis, the scores of factors 1 and 2 independently predicted the risk of CP. These cytokines included several growth factors and chemokines, and they all tended to be higher in children with CP than in children without CP. Inflammatory cytokine levels were associated with CP risk on days 1 and 7 after birth.

CONCLUSION

The high blood concentrations of various cytokines during the perinatal period may relate to CP, and these cytokines may influence the pathways leading to early insult in the central nervous system. The risk profile of inflammatory cytokines is different at birth than during the first week after birth.

Mesenchymal stem cells prevent hydrocephalus after severe intraventricular hemorrhage

BACKGROUND AND PURPOSE

Severe intraventricular hemorrhage (IVH) in premature infants and the ensuing posthemorrhagic hydrocephalus cause significant mortality and neurological disabilities, and there are currently no effective therapies. This study determined whether intraventricular transplantation of human umbilical cord blood-derived mesenchymal stem cells prevents posthemorrhagic hydrocephalus development and attenuates brain damage after severe IVH in newborn rats.

METHODS

To induce severe IVH, 100 μL of blood was injected into each lateral ventricle of postnatal day 4 (P4) Sprague-Dawley rats. Human umbilical cord blood-derived mesenchymal stem cells or fibroblasts (1 × 10(5)) were transplanted intraventricularly under stereotaxic guidance at P6. Serial brain MRI and behavioral function tests, such as the negative geotaxis test and rotarod test, were performed. At P32, brain tissue and cerebrospinal fluid were obtained for histological and biochemical analyses.

RESULTS

Intraventricular transplantation of umbilical cord blood-derived mesenchymal stem cells, but not fibroblasts, prevented posthemorrhagic hydrocephalus development and significantly attenuated impairment on behavioral tests; the increased terminal deoxynycleotidyltransferase-mediated deoxyuridine triphosphate nick end labeling-positive cells; increased expression of inflammatory cytokines, such as interleukin-1α, interleukin-1β, interleukin-6, and tumor necrosis factor-α; increased astrogliosis; and reduced corpus callosal thickness and myelin basic protein expression after inducing severe IVH.

CONCLUSIONS

Intraventricular transplantation of umbilical cord blood-derived mesenchymal stem cells significantly attenuated the posthemorrhagic hydrocephalus and brain injury after IVH. This neuroprotective mechanism appears to be mediated by the anti-inflammatory effects of these cells.

Can anomalies of fetal brain circulation be useful in the management of growth restricted fetuses?

Assessment of the fetal cerebral circulation provides important information on the hemodynamic changes associated with chronic hypoxia and intrauterine growth restriction. Despite the incorporation of new US parameters, the landmark for the fetal brain hemodynamic evaluation is still the middle cerebral artery. However, new vascular territories, such as the anterior and posterior cerebral arteries, might provide additional information on the onset of the brain sparing effect. The fractional moving blood volume estimation and three-dimensional power Doppler ultrasound indices are new techniques that seem to be promising in identifying cases at earlier stages of vascular deterioration; still, they are not available for clinical application and more information is needed on the reproducibility and advantages of three-dimensional power Doppler ultrasound blood flow indices. In the past, the brain sparing effect was considered as a protective mechanism; however, recent information challenges this concept. There is growing evidence of an association between brain sparing effect and increased risk of abnormal neurodevelopment after birth. Even in mild late-onset intrauterine growth restriction affected fetuses with normal umbilical artery blood flow, increased cerebral blood perfusion can be associated with a substantial risk of abnormal neuroadaptation and neurodevelopment during childhood.

Different magnesium sulphate regimens for neuroprotection of the fetus for women at risk of preterm birth

BACKGROUND

The effectiveness of antenatal magnesium sulphate for neuroprotection of the fetus, infant, and child prior to very preterm birth, when given to women considered at risk of preterm birth, has been established. There is currently no consensus as to the regimen to use in terms of the dose, duration, the use of repeat dosing and timing.

OBJECTIVES

To assess the comparative effectiveness and adverse effects of different magnesium sulphate regimens for neuroprotection of the fetus in women considered at risk of preterm birth.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 December 2011).

SELECTION CRITERIA

Randomised trials comparing different magnesium sulphate regimens when used for neuroprotection of the fetus in women considered at risk of preterm birth. We planned to include cluster trials. We planned to exclude quasi-randomised trials and those with a crossover design. We planned to include trials published as full-text papers, along with those published in abstract form only.

DATA COLLECTION AND ANALYSIS

We planned that at least two review authors would assess trial eligibility.

MAIN RESULTS

No eligible completed trials were identified.

AUTHORS' CONCLUSIONS

Although strong evidence supports the use of antenatal magnesium sulphate for neuroprotection of the fetus prior to very preterm birth, no trials comparing different treatment regimens have been completed. Research should be directed towards comparisons of different dosages and other variations in regimens, evaluating both maternal and infant outcomes.

Prophylactic administration of melatonin to the mother throughout pregnancy can protect against oxidative cerebral damage in neonatal rats

OBJECTIVE

The purpose of this study was to investigate whether prophylactic administration of melatonin to the mother throughout pregnancy could protect against ischemia/reperfusion (I/R)-induced oxidative brain damage in neonatal rats.

METHODS

The utero-ovarian arteries were occluded bilaterally for 30 min in female Wistar rats on day 16 of pregnancy to induce fetal ischemia. Reperfusion was achieved by releasing the occlusion and restoring circulation. A sham operation was performed in control rats. Melatonin solution or vehicle alone was administrated orally throughout pregnancy. We collected brain mitochondria from neonatal rats, evaluated mitochondrial structure by electron microscopy, and measured the respiratory control index (RCI) as an indicator of mitochondrial respiratory activity as well as the concentration of thiobarbituric acid-reactive substances (TBARS), a marker of oxidative stress. Histological analysis was performed at the Cornu Ammonis 1 (CA1) and Cornu Ammonis 3 (CA3) regions of the hippocampus.

RESULTS

I/R significantly reduced the RCI and significantly elevated the concentration of TBARS. Melatonin treatment reversed these effects, resulting in values similar to that in untreated, sham-ischemic animals. Electron microscopic evaluation showed that the number of intact mitochondria decreased in the I/R group, while melatonin treatment preserved them. Histological analysis revealed a decrease in the ratio of normal to whole pyramidal cell number in the CA1 and CA3 regions in the I/R group. While melatonin administration protected against degeneration.

CONCLUSIONS

These results indicate that prophylactic administration of melatonin to the mother throughout pregnancy may prevent I/R-induced oxidative brain damage in neonatal rats.

Changes of expression of glucose transporters in the fetal lamb brain after MCI-186 administration to the maternal circulation with 10-min persistent umbilical cord occlusion

OBJECTIVE

To evaluate the effect of MCI-186 (3-methyl-1-phenyl-2-pyrazoline-5-one), a potent hydroxyl radical scavenger, administered to the maternal circulation following umbilical cord occlusion in regard to glucose transporter (GLUT) expression.

MATERIALS AND METHODS

Fourteen instrumented lambs were prepared. In three cases, a 10-min persistent umbilical cord occlusion was performed; 30 min after the insult, fetal brains were extirpated (Group A). Four cases had a 10-min occlusion(Group B) and four cases had 10-min occlusion and were administered MCI-186 to the maternal circulation (Group C).Three days following the insult, the fetal brains were extirpated. The remaining three cases had a sham operation (Group D).Brain tissue sections were stained at the locations of GLUT-1, -3 and -5 and were evaluated by two pathologists.

RESULTS

The expression of GLUT-1 and -3 significantly increased in the basal ganglia, hippocampi and periventricular region of Group B when compared with that of Group A. The expression of GLUT-1 and -3 in three regions of Group B were significantly higher than that of Group C and D. GLUT-5 was recognised only in Group B.

CONCLUSION

On the basis of expression of GLUT, the protective effect of MCI-186 on brain injury resulting from hypoxia/ ischemia-reperfusion is documented.

Prenatal low-dose aspirin and neurobehavioral outcomes of children born very preterm

OBJECTIVE

Low-dose aspirin (LDA) given during pregnancy may alter brain development in very preterm infants. We report the short- and long-term outcomes of very preterm infants according to LDA treatment.

PATIENTS AND METHODS

Data were from the Etude Epidemiologique des Petites Ages Gestationnels (EPIPAGE) cohort study, which included all infants born before 33 weeks of gestation in 9 French regions in 1997. This study was restricted to 656 children who were born to 584 women with an obstetric history of placental vascular disease or with chronic hypertension or renal or autoimmune diseases. The main outcome measures were mortality, cerebral lesions, and outcome at 5 years of age, which were measured by a diagnosis of cerebral palsy; behavioral difficulties, which were assessed with the Strength and Difficulties Questionnaire; and cognitive impairment, which was measured by the mental processing composite scale of the Kaufman Assessment Battery for Children (an IQ-equivalent measure of cognitive ability in 2 dimensions: sequential and simultaneous processing scores).

RESULTS

LDA treatment was administered to 125 of 584 (21%) mothers and was not significantly associated with mortality, cerebral lesions, cerebral palsy, or global cognitive impairment of the children at 5 years of age. The proportion of low simultaneous processing scores (<70) was lower in the group with LDA (7% vs 19% without LDA; P = .04). This association was not significant after adjustment for propensity score, prognostic factors, and social class (adjusted odds ratio [aOR]: 0.59 [95% confidence interval (CI): 0.17-2.06]). LDA treatment was associated with a reduction, at the limit of significance, in total behavioral difficulties (aOR: 0.44 [95% CI: 0.19-1.02]) and hyperactivity (aOR: 0.43 [95% CI: 0.17-1.05]).

CONCLUSIONS

LDA was not associated with adverse neonatal or long-term outcomes. Moreover, the results suggest that LDA may be associated with a reduction in neurobehavioral difficulties. More research is needed to assess the effects of aspirin alone or combined with other neuroprotective agents.

MCI-186 administered to the maternal circulation inhibits fetal brain injury resulting from total umbilical cord occlusion in the chronically instrumented fetal lamb

OBJECTIVE

To evaluate the transplacental effects of MCI-186 (edaravone), a potent hydroxyl radical scavenger, administered to the maternal circulation to inhibit fetal brain injury caused by umbilical cord occlusion.

METHODS

Nine chronically instrumented lambs were prepared. In three cases, 10-min persistent total umbilical cord occlusion (group A) was performed. Another three cases underwent occlusion and were administered 60 mg of MCI-186 through the maternal femoral vein prior to the end of occlusion (group B). The remaining three cases underwent sham operation (group C). On day 3 after insult, fetal brains were extirpated. Paraffin-embedded brain tissue sections were stained with hematoxylin and eosin, Bodian, Kluver-Barrera, and TUNEL. Neuronal cellular damage was evaluated by two pathologists blinded to the experimental conditions.

RESULTS

Group A displayed numerous cells with eosinophilic condensation of nuclear chromatin and proliferation of microglia in the hippocampus and basal ganglia. TUNEL-positive cells were observed in the periventricular area. Group B showed microglial proliferations, but no marked changes. No pathological changes were apparent in group C.

CONCLUSIONS

MCI-186 administered to the maternal circulation could inhibit fetal brain injury resulting from hypoxia-reperfusion induced by umbilical cord occlusion.

[Is it possible to protect the preterm infant brain and to decrease later neurodevelopmental disabilities?]

With improving neonatal survival for very premature babies, the challenge for neonatalogists is to ameliorate outcome of surviving babies. Several pharmacological molecules have been shown to have protective effects in different types of in vitro or in vivo animal models of acquired cerebral brain damages. However translational research and conduction of therapeutic trials in human remain difficult due to failure to recognize start of deleterious cascade leading to cerebral damage and additional toxic effect of potential protective molecules. This review concentrates on best evidence emerging in recent years on prevention on brain damage by early drug administration. It has been shown in two randomised trials that prenatal low-dose of magnesium sulphate does not increase paediatric mortality in very-preterm infants and has non significant neuroprotective effects on occurrence of motor dysfunction (with a 0.62 odds ratio in the French trial Premag and 0.71 relative risk in the Australian trial ACTOMgSO4), justifying that magnesium sulphate should be discussed as a stand-alone treatment or as part of a combination treatment, at least in the context of clinical trials. Antenatal corticosteroid therapy increases the survival of very-preterm infants, including the most immature. Moreover in an observational recent study of the Epipage cohort, it has been observed a significant decrease in white matter injury in the 28-32 weeks' gestation group but no effect on long term outcome and behaviour. Conversely in the most immature of the 24-27 weeks' gestation group, no effect has been detected either in white matter injury incidence or in long term outcome rates. Caffeine has a protective effect since a decrease in cerebral palsy has been noted in the caffeine group in a randomised trial studying caffeine versus placebo. For what concern other widely used potential protective molecules during the perinatal period, there is no evidence of cerebral protection with indometacine, nitric oxide, eythropoietin, phenobarbital, and etamsylate. Due to their specific properties, a careful evaluation of aspirin, anaesthetic drugs and tocolytics should be done in the next months.

Cord immunoproteins as predictors of respiratory outcome in preterm infants

OBJECTIVE

The purpose of this study was to evaluate the role of cord blood proteins and antenatal factors in the prediction of respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD).

STUDY DESIGN

The prospectively collected cohort included 163 infants. All infants were born between 1998-2002 in a single regional hospital before 32 weeks of gestation and survived the first hospitalization. Altogether, 107 cord blood proteins were analyzed. Twenty-two antenatal clinical factors were included in the data mining and logistic regression analyses.

RESULTS

The incidence of RDS was 64% and of BPD was 25%. Histologic chorioamnionitis protected from RDS (odds ratio [OR], 0.24; 95% confidence interval [CI], 0.11-0.53; P < .001). Besides the length of gestation, other clinical factors poorly predicted the outcomes. Matrix metalloproteinase-9 independently predicted RDS (OR, 8.3; 95% CI, 3.0-23.1; P < .001). Soluble glycoprotein 130 independently predicted BPD (OR, 6.07; 95%CI, 2.20-16.7; P < .001).

CONCLUSION

Specific antenatal immunologic activation predicts either acute or chronic respiratory disease in very preterm infants.

Amoeboid microglia in the periventricular white matter induce oligodendrocyte damage through expression of proinflammatory cytokines via MAP kinase signaling pathway in hypoxic neonatal rats

Hypoxic injury in the perinatal period results in periventricular white matter (PWM) lesions with axonal damage and oligodendroglial loss. It also alters macrophage function by perpetuating expression of inflammatory mediators. Relevant to this is the preponderance of amoeboid microglial cells (AMC) characterized as active macrophages in the developing PWM. This study aimed to determine if AMC produce proinflammatory cytokines that may be linked to the oligodendroglial loss observed in hypoxic PWM damage (PWMD). Wistar rats (1 day old) were subjected to hypoxia, following which upregulated expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), TNF receptor 1 (TNF-R(1)) and IL-1 receptor 1 (IL-1R(1)) was observed. This was coupled with apoptosis and expression of TNF-R(1) and IL-1R(1) in oligodendrocytes. Primary cultured microglial cells subjected to hypoxia (3% oxygen, 5% CO(2) and 92% nitrogen) showed enhanced expression of TNF-alpha and IL-1beta. Furthermore, mitogen-activated protein (MAP) kinase signaling pathway was involved in the expression of TNF-alpha and IL-1beta in microglia subjected to hypoxia. Our results suggest that following a hypoxic insult, microglial cells in the neonatal rats produce inflammatory cytokines such as TNF-alpha and IL-1beta via MAP kinase signaling pathway. These cytokines are detrimental to oligodendrocytes resulting in PWM lesion.

Maternal infection and white matter toxicity

Studies examining maternal infection as a risk factor for neurological disorders in the offspring have suggested that altered maternal immune status during pregnancy can be considered as an adverse event in prenatal development. Infection occurring in the mother during the gestational period has been implicated in multiple neurological effects. The current manuscript will consider the issue of immune/inflammatory conditions during prenatal development where adverse outcomes have been linked to maternal systemic infection. The discussions will focus primary on white matter and oligodendrocytes as they have been identified as target processes. This white matter damage occurs in very early preterm infants and in various other human diseases currently being examined for a linkage to maternal or early developmental immune status. The intent is to draw attention to the impact of altered immune status during pregnancy on the offspring for the consideration of such contributing factors to the general assessment of developmental neurotoxicology.

Origins of tactile vulnerability in high-risk infants

PURPOSE

This study examined the degree to which birthweight, gestational age, fetal drug exposure, hazardous postnatal medical events, and a mother's predisposition toward touch predicted the likelihood of an infant's tactile vulnerability during nursing care.

SUBJECTS

The convenience sample included 99 hospitalized infants in their second week of life and their mothers.

DESIGN

The design was correlational.

METHODS

A standardized observational assessment was used to code the infant's physiological and behavioral responses to touch during 4 different episodes of nursing care. Chart review was performed to collect information regarding fetal drug exposure, birthweight, gestational age, and postnatal medical events. Mothers completed a questionnaire regarding their own comfort with using touch and being touched.

MEASURES

The Tactile Vulnerability Assessment measured infant reactivity to and tolerance for touch during nursing care. The Postnatal Complications Scale identified hazardous medical conditions and treatments experienced by the infant during the first 2 weeks of life, and the Physical Contact Assessment evaluated a mother's predisposition toward touch.

RESULTS

The number of hazardous postnatal medical events experienced by an infant was the primary predictor of tactile vulnerability, accounting for 28% of the variance in the infant's likelihood of developing hyperarousal and distress from touch during care. Illicit fetal drug exposure and maternal predisposition toward touch were also significant predictors.

CONCLUSIONS

The significant relationship of postnatal medical events to tactile vulnerability suggests that it may be associated with the presence of infant pain or injury to the infant's central nervous system. Symptoms of drug withdrawal and the impact of teratogens on arousal regulation may also be implicated in greater distress from touch by infants. In addition, findings suggest the potential for inherited transmission of a vulnerability to touch. Assessment of infant vulnerability, including discussion with parents about their views of the infant's needs regarding touch, may enhance problem identification and early intervention to reduce infant distress and further medical problems.

The production of hydroxyl radicals in the fetal lamb brain resulting from occlusion of the umbilical circulation and the transplacental effect of MCI-186 to inhibit hydroxyl radical production

The present study evaluated hydroxyl radical production in fetal lamb brain during and after umbilical cord occlusion and examined the effects of injecting MCI-186 (3-metyl-1-phenyl-2-pyrazolin-5-one; Edaravone), a hydroxyl radical scavenger, into the maternal circulation. In 11 chronically instrumented lambs, intermittent total umbilical cord occlusions 1 min out of every 3 min for 1 h and 10-min persistent total umbilical cord occlusion were performed with brain microdialysis using 5 mM of sodium salicylate. In the remaining four lambs, 60 mg of MCI-186 was administered into the maternal circulation from shortly before the end of 10-min persistent total umbilical cord occlusion. Concentrations of 2,3-dihydroxy-benzoic acid (2,3-DHBA), produced by hydroxyl radical reactions with sodium salicylate, were measured in perfusate by HPLC. Concentration of 2,3-DHBA in perfusate was 23.05 +/- 10.95 nM before umbilical cord occlusion. Levels of 2,3-DHBA tended to increase slightly during and after intermittent umbilical cord occlusion, and were significantly increased by the end of 10-min occlusion (40.06 +/- 21.36 nM) and after occlusion (93.74 +/- 29.17 nM). Infusion of MCI-186 suppressed 2,3-DHBA concentration to 29.35 +/- 14.95 nM after occlusion. Administration of MCI-186 into the maternal circulation reduces hydroxyl radical production induced by umbilical cord occlusion in the fetal lamb brain.

Transplacental effects of allopurinol on suppression of oxygen free radical production in chronically instrumented fetal lamb brains during intermittent umbilical cord occlusion

OBJECTIVE

To evaluate the transplacental effect of allopurinol, which acts as a xanthine oxidase inhibitor and free radical scavenger, on inhibiting the production of superoxides during intermittent partial umbilical cord occlusion.

METHODS

Using four chronically instrumented fetal lambs, ewes received 400 mg allopurinol over a period of two hours. Concentrations of allopurinol and oxypurinol in blood samples from mothers and fetuses and fetal brain microdialysis perfusate were measured by HPLC. In another three cases the production of superoxide during intermittent umbilical cord occlusion was studied by measurement of chemiluminescence in perfusate before and after administration of Allopurinol.

RESULTS

(i) Allopurinol concentration in mothers had reached equilibrium by 30 min after starting administration and maintained a concentration about 6 mug/ml. Allopurinol concentration in fetuses increased gradually and reached 2.25 +/- 0.54 microg/ml at 120 min; (ii) Oxypurinol concentration in both mothers and fetuses increased during administration of allopurinol; (iii) Concentrations of allopurinol and oxypurinol in the perfusates reached 0.32 +/- 0.12 microg/ml, 0.53 +/- 0.22 microg/ml at 120 min respectively; and (iv) Administration of allopurinol significantly suppressed superoxide production during intermittent partial umbilical cord occlusion.

CONCLUSION

These results demonstrated a good transfer of allopurinol from mother to fetus and suggested the possibility of intrauterine treatment to inhibit fetal brain damage resulting from increased oxygen free radicals.

Endotoxin-induced hypoxic-ischemic tolerance is mediated by up-regulation of corticosterone in neonatal rat

Previous studies suggest that the endotoxin lipopolysaccharide (LPS) may have dual effects on brain damage induced by hypoxia-ischemia (HI) in 7-d-old rats, depending on the exposure paradigm. Although a 4-h interval between LPS administration and HI results in sensitization to HI brain injury, tolerance is observed when LPS is administered 24 h before HI. Our hypothesis is that endogenous corticosteroids are important in acquiring tolerance to HI. Neonatal rats received a single injection of LPS (1.0 mg/kg) either 4 h or 24 h before HI, or two LPS injections (4 h and 24 h) before HI. Increased brain injury was seen in animals subjected to a single LPS injection made 4 h before HI. In contrast, both the single 24-h exposure and the double injections of LPS resulted in tolerance to HI brain damage. To study the effects of corticosteroids on HI tolerance, RU486, a glucocorticoid receptor blocker, was subcutaneously injected at the same time as LPS (1.0 mg/kg), 24 h before HI stress. RU486-LPS treatment counteracted the LPS-induced tolerance effect, and aggravated the HI-induced brain injury compared with the vehicle-LPS-treated group. RU486 did not aggravate the HI-induced brain injury produced 24 h later in saline-injected animals. LPS (1.0 mg/kg) injected into 6-d-old rats transiently up-regulated serum corticosterone levels (119.6, 57.9, 56.8, and 28.3 ng/mL at 6, 12, 24, and 48 h after the LPS injection, respectively). We conclude that endotoxin-induced up-regulation of endogenous corticosterone appears to be critical for acquiring endotoxin-induced HI tolerance.

Ontogenic study of the influence of tissue plasminogen activator (t-PA) in neonatal excitotoxic brain insult and the subsequent microglia/macrophage activation

Intracerebral injections of ibotenic acid in neonatal mice produced white and gray matter lesions that mimic some aspects of the acquired cerebral injuries observed in human newborns (i.e. periventricular leukomalacias in preterm newborns and post-ischemic cortical necrosis in at term infants). We have evaluated the effects of tissue plasminogen activator inactivation (t-PA-/-) on the effects of ibotenic acid (0.01-20 microg), and on F4/80 labeling of microglia/macrophages at different stages. Three ontogenic periods have been identified. In mice injected the day of birth, postnatal (P) day 0, ibotenic acid induced neuronal migration disorders together with low local microglial activation in wild-type and t-PA-/- mice. In P2 and P5 mice, ibotenic acid induced diffuse microglial activation in the whole cortex and subcortical areas; e.g. caudate nucleus and septum. In wild-type mice, cystic lesions of the white matter were consistently observed, surrounded by macrophages. In t-PA-/- mice, noncystic lesions filled of macrophages were more frequent than cysts. Macrophages were virtually absent in the gray matter. White and gray matter lesions were reduced in t-PA-/- mice. The plasmin inhibitor aprotinin reduced white and gray matter lesions only in wild-type mice injected with high ibotenic acid doses (2.5-5 microg). During this period, a transient F4/80 immunoreactive cell population was detected in the cingulum. At P10, the salient lesion characteristic was a large gray matter lesion containing macrophage accumulation. Microglial activation was confined to the injection site in the white matter. t-PA-/- mice showed reduced lesion size under high doses (>5 microg) of ibotenic acid. Similarly, aprotinin diminished the lesion in wild-type animals exposed to 10 microg ibotenic acid. These data demonstrate that t-PA and microglia do not actively participate in the migration disorders induced in P0 mice. Conversely, t-PA was implicated in cyst formation in older (P2-P10) mice, and in their subsequent growth. t-PA was also involved in GM lesions, probably through an inflammatory process involving macrophages.

Corticothérapie post-natale chez le prématuré : bénéfices et risques

This review examines the risk/benefit ratio of postnatal steroid treatment in preterm infants and correlates epidemiological data with special emphasis on experimental evidence concening the impact of steroid on brain development. With all regimens, steroid treatment consistently reduced the need for assisted ventilation at 28 days of postnatal age or at term. However, neither oxygen at term nor neonatal mortality has been decreased by this treatment. Conversely, respiratory benefits should be weighed against several adverse effects: hyperglycemia, hypertension, gastrointestinal bleeding or perforation, increased risk of cerebral palsy. The impact of dexamethasone on brain development and risk factors of white matter damage could be involved in the association between postnatal steroid treatment and neurological impairment in treated infants. Injectable preparations of dexamethasone contain sulphiting preservatives which could account for the alterations in neuronal maturation observed in animal models. Early use of dexamethasone should especially be avoided for postnatal steroid treatment in premature infants. Other glucocorticoids as alternatives to dexamethasone need to be evaluated in appropriate and large controlled trials with long term follow up.

Combination treatment of neonatal rats with hypoxia-ischemia and endotoxin induces long-lasting memory and learning impairment that is associated with extended cerebral damage

OBJECTIVE

We assessed the long-term effects of perinatal hypoxia-ischemia and endotoxin on attention and short- and long-term memory in neonatal rats with the use of behavioral tasks and brain histologic results.

STUDY DESIGN

Four hours after injections of lipopolysaccharide (1 mg/kg, intraperitoneally) or saline solution, 7-day-old Wistar rat pups were subjected to unilateral hypoxia-ischemia for 1 hour. We studied 4 groups: controls (n = 43 rats), lipopolysaccharide alone (n = 12 rats), hypoxia-ischemia alone (n = 29 rats), and combined lipopolysaccharide + hypoxia-ischemia treatment (n = 34 rats). Seven to 16 weeks after the treatment, we measured attention with a choice reaction time task, short-term memory with an 8-arm radial maze task, and long-term memory with a water maze task. At 19 weeks of age, the brain was removed, fixed, and sectioned coronally; and the volume of each part was measured.

RESULTS

A loss of volume in the hippocampus was observed in the lipopolysaccharide, hypoxia-ischemia, and lipopolysaccharide + hypoxia-ischemia groups; a loss of striatum was observed in the hypoxia-ischemia and lipopolysaccharide + hypoxia-ischemia groups, but loss of cortex was observed only in the lipopolysaccharide + hypoxia-ischemia group. The lipopolysaccharide, hypoxia-ischemia, and lipopolysaccharide + hypoxia-ischemia groups showed significantly poorer performance (attention deficit) than controls in the choice reaction time task. Correct choices decreased, and error increased in the lipopolysaccharide + hypoxia-ischemia group compared with the other groups in the radial maze task, which shows short-term memory impairment. Swimming distance was significantly greater in the hypoxia-ischemia and lipopolysaccharide + hypoxia-ischemia groups than in the other 2 groups in the water maze test, which shows long-term memory impairment.

CONCLUSION

Combined lipopolysaccharide and hypoxia-ischemia treatment synergistically induced short-term memory impairment that is associated with loss of cortical volume.

Maternally administered melatonin protects against ischemia and reperfusion-induced oxidative mitochondrial damage in premature fetal rat brain

We investigated the oxidative susceptibility of the brain and the effect of maternally administered melatonin on ischemia/reperfusion-induced cerebral damage in premature fetal rat. Fetal brain mitochondria was separated on the 16th and 19th days of pregnant rats and the respiratory control index (RCI) was measured as an indicator of mitochondrial respiratory activity in the presence or absence of xanthine and xanthine oxidase. The utero-ovarian arteries were occluded bilaterally for 20 min in female rats on day 16 of pregnancy to induce fetal ischemia. Reperfusion was achieved by releasing the occlusion and restoring circulation for 30 min. A sham operation was performed in control rats. Melatonin (10 mg/kg) or vehicle was injected intraperitoneally into the dams 60 min prior to occlusion. The RCI and concentration of thiobarbituric acid-reactive substances (TBARS) in fetal brain mitochondria were measured. The addition of xanthine and xanthine oxidase significantly decreased mitochondrial RCI at both the 16- and 19-day-old fetal brain. Xanthine and xanthine oxidase-induced reduction in RCI was significantly greater in the 16-day-old fetal brain than that in the fetal brain from the 19th day of pregnancy. Ischemia/reperfusion significantly reduced RCI and elevated TBARS concentrations in the 16-day-old fetal brain mitochondria. Melatonin treatment reversed ischemia/reperfusion-induced reduction in RCI (2.22 +/- 0.10 to 2.53 +/- 0.08, P < 0.01) and elevation in TBARS concentrations (13.50 +/- 1.82 nmol/mg protein to 8.80 +/- 0.78 nmol/mg protein, P < 0.01), resulting in values similar to those in untreated, sham-treated animals. Results indicate that brain mitochondria in the premature fetal rats appear to be more susceptible to oxidative damage. Melatonin administration to pregnant rats may prevent ischemia/reperfusion-induced oxidative mitochondrial damage in premature fetal brain.

Neuroimaging in cerebral palsy

Parents and clinicians concerned about high-risk infants and children with motor delay or cerebral palsy seek information on cause, treatment, prognosis, and recurrence risk. Used in combination with history and examination, neuroimaging studies can improve diagnosis and management. In premature infants, cranial ultrasound is a reliable, noninvasive diagnostic modality. Nuclear magnetic resonance techniques including magnetic resonance imaging and diffusion weighted imaging can be used effectively in neonatal encephalopathies. In children with motor delay and cerebral palsy syndromes including spastic diplegia, quadriplegia, hemiplegia, and extrapyramidal movement disorders, conventional magnetic resonance imaging has become an important determinant of diagnosis and management. The aim of this article is to help clinicians select and interpret imaging studies of benefit in clinical care.

Bias in reported neurodevelopmental outcomes among extremely low birth weight survivors

OBJECTIVES

The purpose of this study was to investigate possible bias in the evaluation of neurodevelopment and somatic growth at 18 to 22 months' postmenstrual age among extremely low birth weight (ELBW) survivors (401-1000 g at birth).

METHODS

Data from a cohort of 1483 ELBW infant survivors who were born January 1993 through December 1994 and cared for at centers in the Neonatal Research Network of the National Institute of Child Health and Human Development were examined retrospectively. Children who were compliant with an 18- to 22-month follow-up visit, who visited but were not measured, or who made no visit were compared regarding 4 outcomes: 1) Bayley Scales of Infant Development, 2nd edition, Mental Developmental Index (MDI) <70 and 2) Psychomotor Developmental Index (PDI) <70, 3) presence or absence of cerebral palsy, and 4) weight <10th percentile for age. Logistic regression models were used to predict likelihood of these outcomes for children with no follow-up evaluation, and predicted probability distributions were compared across the groups.

RESULTS

Compared with children who were lost to follow-up, those who were compliant with follow-up were more likely to have been 1 of a multiple birth, to have received postnatal glucocorticoids, and to have had chronic lung disease. These factors were significantly associated with MDI and PDI <70 in the compliant group. Chronic lung disease was associated with increased risk of cerebral palsy (CP). MDI and PDI scores <70 were found in 37% and 29% of children who were evaluated at follow-up, respectively. Prediction models revealed that 34% and 26% of infants in the no-visit group would have had MDI and PDI scores <70. Compliant children tended to have greater incidence of MDI <70 compared with those predicted in the no-visit group but not PDI <70. CP was identified in 17% of the compliant group and predicted for 18% of the no-visit group. Predicted probabilities of having CP were marginally higher among the no-visit infants compared with those who were compliant with follow-up. There were no statistically significant somatic growth differences among the compliant, visit but not measured, and no-visit groups.

CONCLUSION

ELBW infant survivors who weighed 401 to 1000 g at birth and who are compliant with follow-up evaluations may have worse Bayley Scales of Infant Development, 2nd edition, MDI scores than infants with no visit. Thus, follow-up studies based on infants who are compliant with follow-up care may lead to an overestimation of adverse outcomes in ELBW survivors.

Lipopolysaccharide administration enhances hypoxic-ischemic brain damage in newborn rats

AIM

To determine whether inflammation and hypoxic-ischemic insult (HI) act additively to cause brain damage in perinatal animals by examining the dose-response effect of lipopolysaccharide (LPS) administration on HI insult in neonatal rat pups.

METHODS

Seven-day-old Wistar rats (n = 119) were divided into three groups: (i) a group that received a pre-injection of LPS and HI (LPS/HI, 1 mg/kg, n = 31; 0.5 mg/kg, n = 20; 0.1 mg/kg, n = 17); (ii) a group that received a pre-injection of saline and HI (saline/HI, n = 35); and (iii) those that received LPS alone (1 mg/kg, n = 16). At 4 h after the injection, rat pups from groups (i) and (11) were exposed to unilateral carotid artery ligation, followed by 1 h of hypoxia (8% oxygen in 92% nitrogen) at 33 degrees C. Seven days after the insult, they were sacrificed and their brains removed for histological study. Neuronal damage was categorized as mild, < or =25%; moderate, 25-50%; and severe, > or =50% of surface area on a single section.

RESULTS

Mortality rate during the experiment was significantly increased in the 1 mg/kg of LPS/HI group (12 of 31, 39%) compared with the saline/HI group (0%). No neuronal damage was observed in the LPS only group. However, when LPS was added to HI, neuronal loss in the cerebral cortex and hippocampus was significantly increased in a dose-response manner.

CONCLUSION

LPS potentiates hypoxic-ischemic insult in a dose-dependent fashion to cause brain damage in neonatal rats.

Role of tissue-derived plasminogen activator (t-PA) in an excitotoxic mouse model of neonatal white matter lesions

White matter (WM) lesions in preterm newborns may lead to cerebral palsy. To study WM lesions in a mouse model, we used intrapallial stereotactic injections of ibotenic acid, an N-methyl-D-aspartate receptor agonist. Previous studies support a contribution of tissue-type plasminogen activator (t-PA) to the brain lesions seen in various adult excitotoxic models. Therefore, we studied both 5-day-old (P5) wild-type mice and t-PA knock-out (t-PA-/-) mice. The ibotenic acid doses required to induce WM cysts were lower in the wild-type mice (EC50 < 0.01 microg/animal) than in the t-PA-/- mice (EC50 = 2.5 microg/animal) (p < 0.01), indicating the existence of t-PA-dependent and t-PA-independent mechanisms. Dose-dependent prolonged cyst growth occurred in the wild-type mice only. Early microglial activation and astrogliosis were similar in the wild-type and t-PA-/- mice. In adult mice (P45), demyelination occurred at the injection site in both groups but the astroglial scar was denser in the wild-type than in the t-PA-/- mice. These data support involvement of t-PA at several stages of WM lesion formation. Inactivation of t-PA might confer protection by prolonged hemostasis. The role of t-PA in cyst expansion suggests a new approach to the development of neuroprotective strategies in infants with developing WM lesions.

Postnatal steroid treatment and brain development

This review examines the risk/benefit ratio of postnatal steroid treatment in preterm infants and correlates epidemiological data with experimental evidence on the effect of glucocorticosteroids on brain development.

Follow-up data their use in evidence-based decision-making

Experience with certain perinatal interventions, such as supplemental oxygen and dexamethasone, leads to the conclusion that follow-up data are needed to be well informed about the safety of certain perinatal interventions. Experience with indomethacin suggests that follow-up data also are regarded by some clinicians as a necessary aspect of evidence about effectiveness. Ideally, clinical trials of perinatal interventions might involve collection of data about neonatal predictors of outcome (such as a neuroimaging study and a standardized neurologic assessment); several developmental and neurologic assessments before school entry; a comprehensive evaluation of the child's cognitive function, behavioral competencies, and academic performance at 7 to 8 years of age; serial detailed assessments of the family psychosocial functioning; and an inventory of resources available for the child. Many clinical trials have not included follow-up after the neonatal period, and in such cases information about the effect of the intervention on participants' HRQL is incomplete. The approach taken in several recent trials, in which the outcome of interest is neurodevelopmental outcome at 18 months, attempts to strike a balance between a theoretical ideal (a comprehensive, longitudinal follow-up through school age) and a follow-up regimen that is not prohibitively expensive. Such trials include follow-up during the first 1 to 3 years of life, when major disabilities can be identified reliably, thereby providing moderately informative data about participants' eventual quality of life, related to the presence or absence of major disability. If, however, there is reason to suspect that the intervention has effects on the developing brain, follow-up after school entry may provide additional evidence pertinent to the risks and benefits of the intervention.

Fetal subependymal cysts with normal neonatal outcome. A case report

The authors report the prenatal sonographic diagnosis of subependymal cysts, confirmed by in utero MRI, in an apparently uneventful pregnancy. The sonographic appearance of the lesions, the obstetric management and the postnatal follow-up to one year are described. Special attention is paid to prenatal factors of neurological morbidity, rather than intrapartum and postnatal, thus emphasizing the importance of early and sequential evaluation of the developing fetal brain. Diagnosis, clinical significance and outcome of prenatal subependymal cysts are necessary for parental counselling and obstetric management. Furthermore, the detection of a prenatal brain injury may have remarkable medico-legal implications.