Fetal and neonatal origins of altered brain development

Ketamine decreases inflammatory and immune pathways after transient hypoxia in late gestation fetal cerebral cortex

Transient hypoxia in pregnancy stimulates a physiological reflex response that redistributes blood flow and defends oxygen delivery to the fetal brain. We designed the present experiment to test the hypotheses that transient hypoxia produces damage of the cerebral cortex and that ketamine, an antagonist of NMDA receptors and a known anti‐inflammatory agent, reduces the damage. Late gestation, chronically catheterized fetal sheep were subjected to a 30‐min period of ventilatory hypoxia that decreased fetal PaO₂ from 17 ± 1 to 10 ± 1 mmHg, or normoxia (PaO₂ 17 ± 1 mmHg), with or without pretreatment (10 min before hypoxia/normoxia) with ketamine (3 mg/kg, i.v.). One day (24 h) after hypoxia/normoxia, fetal cerebral cortex was removed and mRNA extracted for transcriptomics and systems biology analysis (n = 3–5 per group). Hypoxia stimulated a transcriptomic response consistent with a reduction in cellular metabolism and an increase in inflammation. Ketamine pretreatment reduced both of these responses. The inflammation response modeled with transcriptomic systems biology was validated by immunohistochemistry and showed increased abundance of microglia/macrophages after hypoxia in the cerebral cortical tissue that ketamine significantly reduced. We conclude that transient hypoxia produces inflammation of the fetal cerebral cortex and that ketamine, in a standard clinical dose, reduces the inflammation response.

Tumor necrosis factor-inducible gene 6 protein: A novel neuroprotective factor against inflammation-induced developmental brain injury

Inflammation is an important factor contributing to developmental brain injury in preterm infants. Although tumor necrosis factor-inducible gene 6 protein (TSG-6) has immunomodulatory effects in several inflammatory conditions of adult animals, nothing is currently known about the role of TSG-6 in the developing brain, its impact on perinatal inflammation and its therapeutic potential. The aim of the current work was 1) to characterize the developmental expression of TSG-6 in the newborn rat brain, 2) to evaluate the impact of LPS exposure on TSG-6 expression and 3) to assess the therapeutic potential of exogenous TSG-6 administration. Brain hemispheres of healthy Wistar rats (postnatal day 1-postnatal day 15 (P1-P15)) were evaluated with regard to the physiological expression of TSG-6. LPS-treated rats (0.25mg/kg LPS i.p. on P3) were analyzed for inflammation-induced changes in TSG-6 and cytokine expression. To evaluate whether exogenous recombinant human (rh)TSG-6 affects inflammation-induced brain injury, newborn Wistar rats, exposed to LPS on P3, were treated with rhTSG-6 i.p. (four repetitive doses of 2.25mg/kg every 12h, first dose 3h before LPS injection). PCR, Western blotting and multiplex ELISA were performed according to standard protocols. TSG-6 is physiologically expressed in the developing brain with a linear increase in expression from P1 to P15 at the mRNA level. At P6, regional differences in TSG-6 expression in the cortex, thalamus and striatum were detected at mRNA and protein level. Furthermore, TSG-6 gene expression was significantly increased by inflammation (induced by LPS treatment). Combined treatment with LPS and TSG-6 vs. LPS exposure alone, resulted in significant down-regulation of cleaved caspase-3, a marker of apoptosis and neuronal plasticity. In addition, several inflammatory serum markers were decreased after TSG-6 treatment. Finally, TSG-6 is physiologically expressed in the developing brain. Changes of TSG-6 expression associated with inflammation suggest a role of TSG-6 in neuroinflammation. Reduction of cleaved caspase-3 by TSG-6 treatment demonstrates the putative neuroprotective potential of exogenous TSG-6 administration in inflammation-induced developmental brain injury.

Cerebral Oxygen Saturation to Guide Oxygen Delivery in Preterm Neonates for the Immediate Transition after Birth: A 2-Center Randomized Controlled Pilot Feasibility Trial

OBJECTIVE

To assess if monitoring of cerebral regional tissue oxygen saturation (crSO2) using near-infrared spectroscopy (NIRS) to guide respiratory and supplemental oxygen support reduces burden of cerebral hypoxia and hyperoxia in preterm neonates during resuscitation after birth.

STUDY DESIGN

Preterm neonates <34(+0) weeks of gestation were included in a prospective randomized controlled pilot feasibility study at 2 tertiary level neonatal intensive care units. In a NIRS-visible group, crSO2 monitoring in addition to pulse oximetry was used to guide respiratory and supplemental oxygen support during the first 15 minutes after birth. In a NIRS-not-visible group, only pulse oximetry was used. The primary outcomes were burden of cerebral hypoxia (<10th percentile) or hyperoxia (>90th percentile) measured in %minutes crSO2 during the first 15 minutes after birth. Secondary outcomes were all cause of mortality and/or cerebral injury and neurologic outcome at term age. Allocation sequence was 1:1 with block-randomization of 30 preterm neonates at each site.

RESULTS

In the NIRS-visible group burden of cerebral hypoxia in %minutes, crSO2 was halved, and the relative reduction was 55.4% (95% CI 37.6-73.2%; P = .028). Cerebral hyperoxia was observed in NIRS-visible group in 3 neonates with supplemental oxygen and in NIRS-not-visible group in 2. Cerebral injury rate and neurologic outcome at term age was similar in both groups. Two neonates died in the NIRS-not-visible group and none in the NIRS-visible group. No severe adverse reactions were observed.

CONCLUSIONS

Reduction of burden of cerebral hypoxia during immediate transition and resuscitation after birth is feasible by crSO2 monitoring to guide respiratory and supplemental oxygen support.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02017691.

Novel window on early human neurodevelopment via fetal exosomes in maternal blood

Adverse in utero exposures can disrupt fetal brain development, deplete subpopulations of neurons and inhibit formation of normal synaptic connections. A major roadblock to unraveling the precise mechanisms and timing of human neurodevelopmental derangement is the almost complete absence of sensitive noninvasive assessments. We present novel methods for isolating fetal neuronal exosomes from maternal plasma as a noninvasive platform for testing aspects of fetal neurodevelopment as early as the 1st trimester. Our methodology represents an important breakthrough both in understanding mechanisms of injury in vivo in a human system and potentially for monitoring clinical interventions seeking to promote fetal brain health.

Late-life brain volume: a life-course approach. The AGES-Reykjavik study

The "fetal-origins-of-adult-disease" hypothesis proposes that an unfavorable intrauterine environment, estimated from small birth size, may induce permanent changes in fetal organs, including the brain. These changes in combination with effects of (cardiovascular) exposures during adult life may condition the later risk of brain atrophy. We investigated the combined effect of small birth size and mid-life cardiovascular risk on late-life brain volumes. Archived birth records of weight and height were abstracted for 1348 participants of the age, gene/environment susceptibility-Reykjavik study (RS; 2002-2006) population-based cohort, who participated in the original cohort of the RS (baseline 1967). Mid-life cardiovascular risk factors (CVRF) were collected in the RS. As a part of the late-life age, gene/environment susceptibility-RS examination, a brain magnetic resonance imaging was acquired and from it, volumes of total brain, gray matter, white matter, and white matter lesions were estimated. Adjusting for intracranial volume, demographics, and education showed small birth size (low ponderal index [PI]) and increased mid-life cardiovascular risk had an additive effect on having smaller late-life brain volumes. Compared with the reference group (high PI/absence of mid-life CVRF), participants with lower PI/presence of mid-life CVRF (body mass index >25 kg/m(2), hypertension, diabetes, "ever smokers") had smaller total brain volume later in life; B (95% confidence interval) were -10.9 mL (-21.0 to -0.9), -10.9 mL (-20.4 to -1.4), -20.9 mL (-46.9 to 5.2), and -10.8 mL (-19.3 to -2.2), respectively. These results suggest that exposure to an unfavorable intrauterine environment contributes to the trajectory toward smaller brain volume, adding to the atrophy that may be associated with mid-life cardiovascular risk.

Neuroinflammation and structural injury of the fetal ovine brain following intra-amniotic Candida albicans exposure

BACKGROUND

Intra-amniotic Candida albicans (C. Albicans) infection is associated with preterm birth and high morbidity and mortality rates. Survivors are prone to adverse neurodevelopmental outcomes. The mechanisms leading to these adverse neonatal brain outcomes remain largely unknown. To better understand the mechanisms underlying C. albicans-induced fetal brain injury, we studied immunological responses and structural changes of the fetal brain in a well-established translational ovine model of intra-amniotic C. albicans infection. In addition, we tested whether these potential adverse outcomes of the fetal brain were improved in utero by antifungal treatment with fluconazole.

METHODS

Pregnant ewes received an intra-amniotic injection of 10(7) colony-forming units C. albicans or saline (controls) at 3 or 5 days before preterm delivery at 0.8 of gestation (term ~ 150 days). Fetal intra-amniotic/intra-peritoneal injections of fluconazole or saline (controls) were administered 2 days after C. albicans exposure. Post mortem analyses for fungal burden, peripheral immune activation, neuroinflammation, and white matter/neuronal injury were performed to determine the effects of intra-amniotic C. albicans and fluconazole treatment.

RESULTS

Intra-amniotic exposure to C. albicans caused a severe systemic inflammatory response, illustrated by a robust increase of plasma interleukin-6 concentrations. Cerebrospinal fluid cultures were positive for C. albicans in the majority of the 3-day C. albicans-exposed animals whereas no positive cultures were present in the 5-day C. albicans-exposed and fluconazole-treated animals. Although C. albicans was not detected in the brain parenchyma, a neuroinflammatory response in the hippocampus and white matter was seen which was characterized by increased microglial and astrocyte activation. These neuroinflammatory changes were accompanied by structural white matter injury. Intra-amniotic fluconazole reduced fetal mortality but did not attenuate neuroinflammation and white matter injury.

CONCLUSIONS

Intra-amniotic C. albicans exposure provoked acute systemic and neuroinflammatory responses with concomitant white matter injury. Fluconazole treatment prevented systemic inflammation without attenuating cerebral inflammation and injury.

Environmental Chemical Assessment in Clinical Practice: Unveiling the Elephant in the Room

A growing body of evidence suggests chemicals present in air, water, soil, food, building materials and household products are toxicants that contribute to the many chronic diseases typically seen in routine medical practice. Yet, despite calls from numerous organisations to provide clinicians with more training and awareness in environmental health, there are multiple barriers to the clinical assessment of toxic environmental exposures. Recent developments in the fields of systems biology, innovative breakthroughs in biomedical research encompassing the "-omics" fields, and advances in mobile sensing, peer-to-peer networks and big data, provide tools that future clinicians can use to assess environmental chemical exposures in their patients. There is also a need for concerted action at all levels, including actions by individual patients, clinicians, medical educators, regulators, government and non-government organisations, corporations and the wider civil society, to understand the "exposome" and minimise the extent of toxic exposures on current and future generations. Clinical environmental chemical risk assessment may provide a bridge between multiple disciplines that uses new technologies to herald in a new era in personalised medicine that unites clinicians, patients and civil society in the quest to understand and master the links between the environment and human health.

Preterm Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a recognizable and defined clinical syndrome in term infants that results from a severe or prolonged hypoxic-ischemic episode before or during birth. However, in the preterm infant, defining hypoxic-ischemic injury (HII), its clinical course, monitoring, and outcomes remains complex. Few studies examine preterm HIE, and these are heterogeneous, with variable inclusion criteria and outcomes reported. We examine the available evidence that implies that the incidence of hypoxic-ischemic insult in preterm infants is probably higher than recognized and follows a more complex clinical course, with higher rates of adverse neurological outcomes, compared to term infants. This review aims to elucidate the causes and consequences of preterm hypoxia-ischemia, the subsequent clinical encephalopathy syndrome, diagnostic tools, and outcomes. Finally, we suggest a uniform definition for preterm HIE that may help in identifying infants most at risk of adverse outcomes and amenable to neuroprotective therapies.

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings

The chronically instrumented pregnant sheep has been used as a model of human fetal development and responses to pathophysiologic stimuli such as endotoxins, bacteria, umbilical cord occlusions, hypoxia and various pharmacological treatments. The life-saving clinical practices of glucocorticoid treatment in fetuses at risk of premature birth and the therapeutic hypothermia have been developed in this model. This is due to the unique amenability of the non-anesthetized fetal sheep to the surgical placement and maintenance of catheters and electrodes, allowing repetitive blood sampling, substance injection, recording of bioelectrical activity, application of electric stimulation and in vivo organ imaging. Here we describe the surgical instrumentation procedure required to achieve a stable chronically instrumented non-anesthetized fetal sheep model including characterization of the post-operative recovery from blood gas, metabolic and inflammation standpoints.

The role of morphology in mathematical models of placental gas exchange

The performance of the placenta as a gas exchanger has a direct impact on the future health of the newborn. To provide accurate estimates of respiratory gas exchange rates, placenta models need to account for both the physiology of exchange and the organ morphology. While the former has been extensively studied, accounting for the latter is still a challenge. The geometrical complexity of placental structure requires use of carefully crafted approximations. We present here the state of the art of respiratory gas exchange placenta modeling and demonstrate the influence of the morphology description on model predictions. Advantages and shortcomings of various classes of models are discussed, and experimental techniques that may be used for model validation are summarized. Several directions for future development are suggested.

mTOR pathway inhibition prevents neuroinflammation and neuronal death in a mouse model of cerebral palsy

BACKGROUND AND PURPOSE

Mammalian target of rapamycin (mTOR) pathway signaling governs cellular responses to hypoxia and inflammation including induction of autophagy and cell survival. Cerebral palsy (CP) is a neurodevelopmental disorder linked to hypoxic and inflammatory brain injury however, a role for mTOR modulation in CP has not been investigated. We hypothesized that mTOR pathway inhibition would diminish inflammation and prevent neuronal death in a mouse model of CP.

METHODS

Mouse pups (P6) were subjected to hypoxia-ischemia and lipopolysaccharide-induced inflammation (HIL), a model of CP causing neuronal injury within the hippocampus, periventricular white matter, and neocortex. mTOR pathway inhibition was achieved with rapamycin (an mTOR inhibitor; 5mg/kg) or PF-4708671 (an inhibitor of the downstream p70S6kinase, S6K, 75 mg/kg) immediately following HIL, and then for 3 subsequent days. Phospho-activation of the mTOR effectors p70S6kinase and ribosomal S6 protein and expression of hypoxia inducible factor 1 (HIF-1α) were assayed. Neuronal cell death was defined with Fluoro-Jade C (FJC) and autophagy was measured using Beclin-1 and LC3II expression. Iba-1 labeled, activated microglia were quantified.

RESULTS

Neuronal death, enhanced HIF-1α expression, and numerous Iba-1 labeled, activated microglia were evident at 24 and 48 h following HIL. Basal mTOR signaling, as evidenced by phosphorylated-S6 and -S6K levels, was unchanged by HIL. Rapamycin or PF-4,708,671 treatment significantly reduced mTOR signaling, neuronal death, HIF-1α expression, and microglial activation, coincident with enhanced expression of Beclin-1 and LC3II, markers of autophagy induction.

CONCLUSIONS

mTOR pathway inhibition prevented neuronal death and diminished neuroinflammation in this model of CP. Persistent mTOR signaling following HIL suggests a failure of autophagy induction, which may contribute to neuronal death in CP. These results suggest that mTOR signaling may be a novel therapeutic target to reduce neuronal cell death in CP.

H' Shaped Bilobate Placental Partition: A Rare Placenta Variation

Anomalies of placental growth with respect to its shape have been associated with adverse pregnancy outcomes. A very rare form of 'H' bilobate placental partition was observed in a 31-year-old woman presenting at 24 weeks of gestation. This observation was made during a routine obstetrics scan. Sonographic features showed that it was a non-fibroid partition. The placenta featured anterior and posterior portions separated by a large middle, vertical portion. The placenta was antero-posterior semi-circumferential in shape, measuring approximately 16.70 cm in length and 12.48 cm at shorter chorionic plate (minor axis). The middle, vertical part of the placenta partitioned the uterine cavity into two, creating the impression of two separate gestational sacs. The fetus was located in one of these. The patient was eventually delivered through caesarean section at gestational age (GA) of 36 weeks 6 days. The baby had a low birth weight of 1.70 kg. The early detection of this placental anomaly underlines the importance of ultrasonography in obstetrics.

Functional integrity of rostral regions of the immature brainstem is impaired in babies born extremely preterm

OBJECTIVE

Babies born extremely preterm are predisposed to brain damage. We test the hypothesis that functional integrity of the auditory brainstem, particularly the rostral regions, is impaired in extremely preterm babies.

METHODS

We recruited 68 babies who were born at 23-27 weeks of gestation. At term date, these babies were studied by recording and analysing maximum length sequence brainstem auditory evoked response (MLS BAER) with click rates 91-910/s. Detailed data analysis was performed in 65 babies from whom reliable MLS BAER measurements were obtained.

RESULTS

Compared with normal term controls, the extremely preterm babies showed a significant increase in wave V latency, and I-V interval at all rates 91-910/s (p<0.01-0.001). Of two small intervals, I-III interval showed no apparent abnormality, but III-V interval was significantly increased at all rates, which was supported by a significant increase in III-V/I-III interval ratio (all p<0.001). These abnormalities were more significant at higher than at lower rates. The slopes of wave V latency-, I-V interval- and particularly III-V interval-rate functions were all increased. The same was true for the slope of III-V/I-III interval ratio-rate function.

CONCLUSIONS

MLS BAER variables that mainly reflect central neural conduction in the extremely preterm babies were abnormally increased. The most important abnormality was a significant increase in III-V interval and its click rate-dependent change. The abnormalities tended to be more significant than those previously reported in late and very preterm babies.

SIGNIFICANCE

Babies born extremely preterm have a major impairment or maturational delay in functional integrity of the rostral regions of the immature brainstem, which is more significant than in less preterm babies.

Does heart rate variability reflect the systemic inflammatory response in a fetal sheep model of lipopolysaccharide-induced sepsis?

Fetal inflammatory response occurs during chorioamnionitis, a frequent and often subclinical inflammation associated with increased risk for brain injury and life-lasting neurologic deficits. No means of early detection exist. We hypothesized that systemic fetal inflammation without septic shock will be reflected in alterations of fetal heart rate (FHR) variability (fHRV) distinguishing baseline versus inflammatory response states. In chronically instrumented near-term fetal sheep (n = 24), we induced an inflammatory response with lipopolysaccharide (LPS) injected intravenously (n = 14). Ten additional fetuses served as controls. We measured fetal plasma inflammatory cytokine IL-6 at baseline, 1, 3, 6, 24 and 48 h. 44 fHRV measures were determined continuously every 5 min using continuous individualized multi-organ variability analysis (CIMVA). CIMVA creates an fHRV measures matrix across five signal-analytical domains, thus describing complementary properties of fHRV. Using principal component analysis (PCA), a widely used technique for dimensionality reduction, we derived and quantitatively compared the CIMVA fHRV PCA signatures of inflammatory response in LPS and control groups. In the LPS group, IL-6 peaked at 3 h. In parallel, PCA-derived fHRV composite measures revealed a significant difference between LPS and control group at different time points. For the LPS group, a sharp increase compared to baseline levels was observed between 3 h and 6 h, and then abating to baseline levels, thus tracking closely the IL-6 inflammatory profile. This pattern was not observed in the control group. We also show that a preselection of fHRV measures prior to the PCA can potentially increase the difference between LPS and control groups, as early as 1 h post LPS injection. We propose a fHRV composite measure that correlates well with levels of inflammation and tracks well its temporal profile. Our results highlight the potential role of HRV to study and monitor the inflammatory response non-invasively over time.

Fetal microglial phenotype in vitro carries memory of prior in vivo exposure to inflammation

Objective: Neuroinflammation in utero may result in life-long neurological disabilities. The molecular mechanisms whereby microglia contribute to this response remain incompletely understood.

Methods: Lipopolysaccharide (LPS) or saline were administered intravenously to non-anesthetized chronically instrumented near-term fetal sheep to model fetal inflammation in vivo. Microglia were then isolated from in vivo LPS and saline (naïve) exposed animals. To mimic the second hit of neuroinflammation, these microglia were then re-exposed to LPS in vitro. Cytokine responses were measured in vivo and subsequently in vitro in the primary microglia cultures derived from these animals. We sequenced the whole transcriptome of naïve and second hit microglia and profiled their genetic expression to define molecular pathways disrupted during neuroinflammation.

Results:In vivo LPS exposure resulted in IL-6 increase in fetal plasma 3 h post LPS exposure. Even though not histologically apparent, microglia acquired a pro-inflammatory phenotype in vivo that was sustained and amplified in vitro upon second hit LPS exposure as measured by IL-1β response in vitro and RNAseq analyses. While NFKB and Jak-Stat inflammatory pathways were up regulated in naïve microglia, heme oxygenase 1 (HMOX1) and Fructose-1,6-bisphosphatase (FBP) genes were uniquely differentially expressed in the second hit microglia. Compared to the microglia exposed to LPS in vitro only, the transcriptome of the in vivo LPS pre-exposed microglia showed a diminished differential gene expression in inflammatory and metabolic pathways prior and upon re-exposure to LPS in vitro. Notably, this desensitization response was also observed in histone deacetylases (HDAC) 1, 2, 4, and 6. Microglial calreticulin/LRP genes implicated in microglia-neuronal communication relevant for the neuronal development were up regulated in second hit microglia.

Discussion: We identified a unique HMOX1_down and FBP^up phenotype of microglia exposed to the double-hit suggesting interplay of inflammatory and metabolic pathways. Our findings suggest that epigenetic mechanisms mediate this immunological and metabolic memory of the prior inflammatory insult relevant to neuronal development and provide new therapeutic targets for early postnatal intervention to prevent brain injury.

Cortical morphology and early adverse birth events in men with first-episode psychosis

BACKGROUND

Reduced cortical gray-matter volume is commonly observed in patients with psychosis. Cortical volume is a composite measure that includes surface area, thickness and gyrification. These three indices show distinct maturational patterns and may be differentially affected by early adverse events. The study goal was to determine the impact of two distinct obstetrical complications (OCs) on cortical morphology.

METHOD

A detailed birth history and MRI scans were obtained for 36 patients with first-episode psychosis and 16 healthy volunteers.

RESULTS

Perinatal hypoxia and slow fetal growth were associated with cortical volume (Cohen's d = 0.76 and d = 0.89, respectively) in patients. However, the pattern of associations differed across the three components of cortical volume. Both hypoxia and fetal growth were associated with cortical surface area (d = 0.88 and d = 0.72, respectively), neither of these two OCs was related to cortical thickness, and hypoxia but not fetal growth was associated with gyrification (d = 0.85). No significant associations were found within the control sample.

CONCLUSIONS

Cortical dysmorphology was associated with OCs. The use of a global measure of cortical morphology or a global measure of OCs obscured important relationships between these measures. Gyrification is complete before 2 years and its strong relationship with hypoxia suggests an early disruption to brain development. Cortical thickness matures later and, consistent with previous research, we found no association between thickness and OCs. Finally, cortical surface area is largely complete by puberty and the present results suggest that events during childhood do not fully compensate for the effects of early disruptive events.

Preterm birth affects GABAA receptor subunit mRNA levels during the foetal-to-neonatal transition in guinea pigs

Modulation of gamma-aminobutyric acid A (GABAA) receptor signalling by the neurosteroid allopregnanolone has a major role in late gestation neurodevelopment. The objective of this study was to characterize the mRNA levels of GABAA receptor subunits (α4, α5, α6 and δ) that are key to neurosteroid binding in the brain, following preterm birth. Myelination, measured by the myelin basic protein immunostaining, was used to assess maturity of the preterm brains. Foetal guinea pig brains were obtained at 62 days’ gestational age (GA, preterm) or at term (69 days). Neonates were delivered by caesarean section, at 62 days GA and term, and maintained until tissue collection at 24 h of age. Subunit mRNA levels were quantified by RT-PCR in the hippocampus and cerebellum of foetal and neonatal brains. Levels of the α6 and δ subunits were markedly lower in the cerebellum of preterm guinea pigs compared with term animals. Importantly, there was an increase in mRNA levels of these subunits during the foetal-to-neonatal transition at term, which was not seen following preterm birth. Myelination was lower in preterm neonatal brains, consistent with marked immaturity. Salivary cortisol concentrations, measured by EIA, were also higher for the preterm neonates, suggesting greater stress. We conclude that there is an adaptive increase in the levels of mRNA of the key GABAA receptor subunits involved in neurosteroid action after term birth, which may compensate for declining allopregnanolone levels. The lower levels of these subunits in preterm neonates may heighten the adverse effect of the premature decline in neurosteroid exposure.

Bilirubin-induced neural impairment: a special focus on myelination, age-related windows of susceptibility and associated co-morbidities

Bilirubin-induced neurologic dysfunction (BIND) and classical kernicterus are clinical manifestations of moderate to severe hyperbilirubinemia whenever bilirubin levels exceed the capacity of the brain defensive mechanisms in preventing its entrance and cytotoxicity. In such circumstances and depending on the associated co-morbidities, bilirubin accumulation may lead to short- or long-term neurodevelopmental disabilities, which may include deficits in auditory, cognitive, and motor processing. Neuronal cell death, astrocytic reactivity, and microglia activation are part of the bilirubin-induced pathogenesis. Less understood is how abnormal growth and maturation of oligodendrocytes may impact on brain development, affecting the formation of myelin tracts. Based on in-vitro and in-vivo models, as well as in clinical cases presented here, we propose the existence of impaired myelination by bilirubin with long-term sequelae, mainly in pre-term infants. Sensitive time-windows are highlighted and centered on the different developmental-dependent impairments determined by bilirubin, and the influence of sepsis and hypoxia is reviewed.

The contribution of chemoreceptor-network injury to the development of respiratory arrest following subarachnoid hemorrhage

OBJECTIVE

Respiratory arrest following brainstem herniation has been attributed to injuries resulting from compression of the respiratory centers. While it is widely perceived that the chemoreceptor network, consisting of the glossopharyngeal nerve and carotid body (GPN-CB), is essential for the modulation of respiration, its contribution to the development of respiratory arrest has not been investigated. Therefore, the aim of this study was to investigate whether injury to the GPN-CB occurs in animals with respiratory arrest caused by experimentally-induced subarachnoid hemorrhage.

MATERIALS AND METHODS

Eighteen hybrid rabbits were used in this study. Four rabbits (n=4) were used to determine the normal structure of the GPN-CB. The remaining rabbits (n=14) received an autologous blood injection into the cisterna magna to produce a subarachnoid hemorrhage, after which they were observed for 20 days. The number of axons and the neuron density in the glossopharyngeal nerve and carotid body, respectively, were counted by stereological methods. The Mann-Whitney U test was used to analyze the results.

RESULTS

Six of 14 rabbits died within the first week, likely due to brain swelling and crushing injuries that were observed in the brain stem and related structures. In control rabbits, the average neuronal density of the carotid body was 4250 ±1250/mm(3), while the axonal density in the glossopharyngeal nerve was 18000±5100 mm(2). Conversely, in the dead rabbits, the degenerated neuron density of the carotid body was 2100±500/mm(3), while the degenerated axon density in the glossopharyngeal nerve was 8500±2550 mm(2). In addition, histopathological lesions were more severe in the dead rabbits in terms of their glossopharyngeal nerve and carotid body.

CONCLUSION

There is an important relationship between neurodegeneration in the GPN-CB and mortality rates following experimentally-induced hemorrhage. This relationship suggests that injury to the GPN-CB network disrupts the breathing reflex and results in respiratory arrest following a subarachnoid hemorrhage (SAH).

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.

Birth size and brain function 75 years later

BACKGROUND

There are several lines of evidence pointing to fetal and other early origins of diseases of the aging brain, but there are no data directly addressing the hypotheses in an older population. We investigated the association of fetal size to late-age measures of brain structure and function in a large cohort of older men and women and explored the modifying effect of education on these associations.

METHODS

Within the AGES (Age Gene/Environment Susceptibility)-Reykjavik population-based cohort (born between 1907 and 1935), archived birth records were abstracted for 1254 men and women who ∼75 years later underwent an examination that included brain MRI and extensive cognitive assessment.

RESULTS

Adjustment for intracranial volume, demographic and medical history characteristics, and lower Ponderal index at birth (per kg/m(3)), an indicator of third-trimester fetal wasting, was significantly associated with smaller volumes of total brain and white matter; βs (95% confidence intervals) were -1.0 (-1.9 to -0.0) and -0.5 (-1.0 to -0.0) mL. Furthermore, lower Ponderal index was associated with slower processing speed and reduced executive functioning but only in those with low education (β [95% confidence interval]: -0.136 [-0.235 to -0.036] and -0.077 [-0.153 to -0.001]).

CONCLUSIONS

This first study of its kind provides clinical measures suggesting that smaller birth size, as an indicator of a suboptimal intrauterine environment, is associated with late-life alterations in brain tissue volume and function. In addition, it shows that the effects of a suboptimal intrauterine environment on late-life cognitive function were present only in those with lower educational levels.

Placental measurements associated with intelligence quotient at age 7 years

We hypothesized that placental villous branching that is measured by disk chorionic plate expansion and disk thickness is correlated with factors also involved in regulation of branching growth of other fetal viscera (e.g. lung, kidney) including neuronal dendrites, and thus may be associated with variation in childhood intelligence quotient (IQ). IQ at age 7 years was assessed using the Wechsler Intelligence Scale for Children. Placental measures [placental weight (g), thickness (mm), chorionic plate surface diameters (cm), area (cm2), shape, and cord length and cord eccentricity] were independent variables in regression analyses of age 7-year IQ in 12,926 singleton term live born infants with complete placental data. Analyses were stratified on gender with adjustment for socioeconomic status, race, parity, gestational age, exact age at testing and centered parental ages. After adjustment for covariates, placental measurements were independently associated with IQ at age 7 years but results varied by gender. Chorionic plate diameters were only associated with higher IQ in girls. Placental thickness was positively associated with higher IQ for boys and girls. We have previously shown that placental measures affect age 7-year body mass index and diastolic blood pressure. Here we demonstrate that specific measures, placental chorionic plate diameters in girls and disk thickness, independent of gender, are correlated with age 7-year IQ. Further exploration of the possible interaction of these factors on the placental villous arborization reflected by the chorionic plate expansion and placental thickness that correlate with age 7-year IQ, as well as other age 7 somatic features as previously addressed, is indicated.

Diffusion tractography and neuromotor outcome in very preterm children with white matter abnormalities

BACKGROUND

Moderate-to-severe white matter abnormality (WMA) in the newborn has been shown to produce persistent disruptions in cerebral connectivity but does not universally result in neurodevelopmental disability in very preterm (VPT) children. The aims of this hypothesis-driven study were to apply diffusion imaging to: (i) examine whether bilateral WMA detected in VPT children in the newborn period can predict microstructural organization at the age of 7 y and (ii) compare corticospinal tract and corpus callosum (CC) measures in VPT children at the age of 7 y with neonatal WMA with normal vs. impaired motor functioning.

METHODS

Diffusion parameters of the corticospinal tract and CC were compared between VPT 7-y olds with (n = 20) and without (n = 42) bilateral WMA detected in the newborn period. For those with WMA, diffusion parameters were further examined.

RESULTS

Microstructural organization of corticospinal tract and CC tracts at the age of 7 y were altered in VPT children with moderate-to-severe WMA detected at term equivalent age as compared with those without injury. Furthermore, diffusion parameters differed in the CC for children with WMA categorized by motor outcome (n = 8).

CONCLUSION

WMA on conventional magnetic resonance imaging at term equivalent age is associated with altered microstructural organization of the corticospinal tract and CC at 7 y of age.

Abnormal heart rate characteristics are associated with abnormal neuroimaging and outcomes in extremely low birth weight infants

OBJECTIVE

Brain injury in preterm infants may lead to an inflammatory response and central nervous system dysfunction reflected by abnormal heart rate characteristics (HRC). We hypothesized that a continuously monitored HRC index reflecting reduced HR variability and decelerations correlates with abnormal neuroimaging and outcomes in extremely low birth weight infants (ELBW).

STUDY DESIGN

We analyzed the average HRC index within 28 days after birth (aHRC28) and head ultrasound (HUS) in 384 ELBW infants. In 50 infants with brain magnetic resonance imaging (MRI) and 70 infants with Bayley neurodevelopmental testing at 1 year of age, we analyzed the relationship between aHRC28, MRI abnormalities and low Bayley scores.

RESULT

aHRC28 was higher in infants with severe HUS abnormalities (2.65±1.27 for Grade III-IV intraventricular hemorrhage (IVH) or cystic periventricular leukomalacia (cPVL) versus 1.72±0.95 for normal or Grade I-II IVH, P<0.001). Higher aHRC28 was also associated with white matter damage on MRI and death or Bayley motor or mental developmental index <70. Associations persisted after adjusting for gestational age, birth weight and septicemia. For every one point increase in aHRC28, the odds ratio of death or Bayley score <70 was 2.45 (95% CI 1.46, 4.05, P<0.001).

CONCLUSION

A continuously monitored HRC index provides an objective, noninvasive measure associated with abnormal brain imaging and adverse neurologic outcomes in ELBW infants.

The Human Placenta Project: placental structure, development, and function in real time

Despite its crucial role in the health of both the fetus and the pregnant woman, the placenta is the least understood human organ. Since a growing body of evidence also underscores the importance of placental development in the lifelong health of both mother and offspring, this lack of knowledge about placental structure and function is particularly concerning. Given modern approaches and technologies and the ability to develop new methods, we propose a coordinated "Human Placenta Project", with the ultimate goal of understanding human placental structure, development, and function in real time.

Prenatal vitamin C deficiency results in differential levels of oxidative stress during late gestation in foetal guinea pig brains

Antioxidant defences are comparatively low during foetal development making the brain particularly susceptible to oxidative stress during antioxidant deficiencies. The brain is one of the organs containing the highest concentration of vitamin C (VitC) and VitC deficiency during foetal development may place the brain at risk of redox status imbalance. In the present study, we investigated the developmental pattern and effect of VitC deficiency on antioxidants, vitamin E and superoxide dismutase (SOD), assessed oxidative damage by measuring malondialdehyde (MDA), hydroxynonenal (HNE) and nitrotyrosine (NT) and analysed gene and protein expression of apoptosis marker caspase-3 in the guinea pig foetal brain at two gestational (GD) time points, GD 45/pre-term and GD 56/near term following either a VitC sufficient (CTRL) or deficient (DEF) maternal dietary regime. We show that except for SOD, antioxidants and oxidative damage markers are differentially expressed between the two GDs, with high VitC (p<0.0001), NT modified proteins (p<0.0001) and active caspase-3 levels (p<0.05) at pre-term and high vitamin E levels (p<0.0001), HNE (p<0.0001) and MDA (p<0.0001) at near term. VitC deficiency significantly increased SOD activity (p<0.0001) compared to CTRLs at both GDs indicating a compensatory response, however, low levels of VitC significantly elevated MDA levels (p<0.05) in DEF at near term. Our results show a differential regulation of the investigated markers during late gestation and suggest that immature brains are susceptible to oxidative stress due to prenatal vitC deficiency in spite of an induction of protective adaptation mechanisms.

Neuroactive steroids in pregnancy: key regulatory and protective roles in the foetal brain

Neuroactive steroid concentrations are remarkably high in the foetal brain during late gestation. These concentrations are maintained by placental progesterone synthesis and the interaction of enzymes in the placenta and foetal brain. 5α-Pregnane-3α-ol-20-one (allopregnanolone) is a key neuroactive steroid during foetal life, although other 3α-hydroxy-pregnanes may make an additional contribution to neuroactive steroid action. Allopregnanolone modulates GABAergic inhibition to maintain a suppressive action on the foetal brain during late gestation. This action suppresses foetal behaviour and maintains the appropriate balance of foetal sleep-like behaviours, which in turn are important to normal neurodevelopment. Neuroactive steroid-induced suppression of excitability has a key role in protecting the foetal brain from acute hypoxia/ischaemia insults. Hypoxia-induced brain injury is markedly increased if neuroactive steroid levels are suppressed and there is increased seizure activity. There is also a rapid increase in allopregnanolone synthesis and hence levels in response to acute stress that acts as an endogenous protective mechanism. Allopregnanolone has a trophic role in regulating development, maintaining normal levels of apoptosis and increasing myelination during late gestation in the brain. In contrast, chronic foetal stressors, including intrauterine growth restriction, do not increase neuroactive steroid levels in the brain and exposure to repeated synthetic corticosteroids reduce neuroactive steroid levels. The reduced availability of neuroactive steroids may contribute to the adverse effects of chronic stressors on the foetal and newborn brain. Preterm birth also deprives the foetus of neuroactive steroid mediated protection and may increase vulnerability to brain injury and suboptimal development. These finding suggest replacement therapies should be explored. This article is part of a Special Issue entitled 'Pregnancy and steroids'.

Sampling rate of heart rate variability impacts the ability to detect acidemia in ovine fetuses near-term

BACKGROUND

To evaluate the impact of sampling rate on the predictive capability of continuous fetal heart rate (FHR) variability (fHRV) monitoring for detecting fetal acidemia during labor, we tested the performance of the root mean square of successive differences (RMSSD) in R-R intervals from the ECG when acquired with the sampling rate of 4 Hz currently available in FHR monitors, in comparison to the gold standard of 1000 Hz.

METHODS

Near-term ovine fetuses (N = 9) were chronically prepared with precordial electrodes for recording ECG, vascular catheters for blood sampling, and an umbilical cord occluder. For 1 min every 2.5 min, animals underwent mild partial umbilical cord occlusions (UCO) × 1 h, moderate partial UCO × 1 h, then complete UCO × 2 h, or until arterial pH reached <7.00. Arterial blood samples were drawn at baseline and every 20 min during the UCO series. RMSSD was calculated continuously in 5 min windows using an automated, standardized system (CIMVA.com). RESULTS are presented as mean ± SEM with significance assumed for p < 0.05.

RESULTS

Repetitive UCO resulted in pH decreasing from 7.35 ± 0.01 to 7.00 ± 0.03. In all nine animals, RMSSD increased from 16.7 ± 1.0 ms at baseline to 44.4 ± 2.3 ms, 70 ± 15 min prior to reaching the pH nadir when sampled at 1000 Hz. When sampled at 4 Hz, RMSSD at baseline measured 36.1 ± 6.0 ms and showed no significant increase during the UCO series until the pH nadir was reached. Consequently, early detection of severe hypoxic-acidemia would have been missed in all fetuses.

CONCLUSION

RMSSD as a measure of fHRV when calculated from FHR sampled at 1000 Hz allowed for the early detection of worsening hypoxic-acidemia in each fetus. However, when calculated at the low sampling rate of 4 Hz used clinically, RMSSD remained unchanged until terminally when the nadir pH was reached. For early detection of fetal acidemia during labor, more sensitive means of acquiring FHR are therefore recommended than currently deployed, e.g., trans-abdominal fetal ECG.

Aberrant neural synchrony in the maternal immune activation model: using translatable measures to explore targeted interventions

Maternal exposure to infection occurring mid-gestation produces a three-fold increase in the risk of schizophrenia in the offspring. The critical initiating factor appears to be the maternal immune activation (MIA) that follows infection. This process can be induced in rodents by exposure of pregnant dams to the viral mimic Poly I:C, which triggers an immune response that results in structural, functional, behavioral, and electrophysiological phenotypes in the adult offspring that model those seen in schizophrenia. We used this model to explore the role of synchronization in brain neural networks, a process thought to be dysfunctional in schizophrenia and previously associated with positive, negative, and cognitive symptoms of schizophrenia. Exposure of pregnant dams to Poly I:C on GD15 produced an impairment in long-range neural synchrony in adult offspring between two regions implicated in schizophrenia pathology; the hippocampus and the medial prefrontal cortex (mPFC). This reduction in synchrony was ameliorated by acute doses of the antipsychotic clozapine. MIA animals have previously been shown to have impaired pre-pulse inhibition (PPI), a gold-standard measure of schizophrenia-like deficits in animal models. Our data showed that deficits in synchrony were positively correlated with the impairments in PPI. Subsequent analysis of LFP activity during the PPI response also showed that reduced coupling between the mPFC and the hippocampus following processing of the pre-pulse was associated with reduced PPI. The ability of the MIA intervention to model neurodevelopmental aspects of schizophrenia pathology provides a useful platform from which to investigate the ontogeny of aberrant synchronous processes. Further, the way in which the model expresses translatable deficits such as aberrant synchrony and reduced PPI will allow researchers to explore novel intervention strategies targeted to these changes.

Reversible effects of vitamins C and E combination on oxidative stress-induced apoptosis in melamine-treated PC12 cells

Due to its high nitrogen content, melamine was deliberately added to raw milk for increasing the apparent protein content. Previous studies showed that melamine-induced apoptosis and oxidative damage on PC12 cells and rats' hippocampus. Several evidences suggested that vitamin antioxidant reduced oxidative stress and improved organic function. Whether treatments with antioxidant vitamins C or E, otherwise combination of them can attenuate oxidative stress after melamine administration remains to be elucidated. In this study, the reversible effects of vitamin antioxidants was investigated on melamine-induced neurotoxicity in cultured PC12 cells, an in vitro model of neuronal cells. When comparing vitamin C and E, the combination of both statistically increased PC12 cells viability. The results further showed that vitamin complex has effectively reduced the formation of reaction oxygen species, decreased the level of malondialdehyde, and elevated the activities of antioxidative enzymes. Hoechst 33342 staining and flow cytometric analysis of apoptosis showed that vitamin combination treatment effectively prevented PC12 cells from this melamine-induced apoptosis. It revealed the apoptotic nuclear features of the melamine-induced cell death. Additionally, a combination treatment of vitamins effectively inhibited apoptosis via blocking the increased activation of caspase-3. In summary, the vitamin E and C combination treatment could rescue PC12 cells from the injury induced by melamine through the downregulation of oxidative stress and prevention of melamine-induced apoptosis.

White matter loss in a mouse model of periventricular leukomalacia is rescued by trophic factors

Periventricular leukomalacia (PVL) is the most frequent cause of cerebral palsy and other intellectual disabilities, and currently there is no treatment. In PVL, glutamate excitotoxicity (GME) leads to abnormal oligodendrocytes (OLs), myelin deficiency, and ventriculomegaly. We have previously identified that the combination of transferrin and insulin growth factors (TSC1) promotes endogenous OL regeneration and remyelination in the postnatal and adult rodent brain. Here, we produced a periventricular white matter lesion with a single intracerebral injection of N-methyl-d-aspartate (NMDA). Comparing lesions produced by NMDA alone and those produced by NMDA + TSC1 we found that: NMDA affected survival and reduced migration of OL progenitors (OLPs). In contrast, mice injected with NMDA + TSC1 proliferated twice as much indicating that TSC1 supported regeneration of the OLP population after the insult. Olig2-mRNA expression showed 52% OLP survival in mice receiving a NMDA injection and increased to 78% when TSC1 + NMDA were injected simultaneously and ventricular size was reduced by TSC1. Furthermore, in striatal slices TSC1 reduced the inward currents induced by NMDA in medium-sized spiny neurons, demonstrating neuroprotection. Thus, white matter loss after excitotoxicity can be partially rescued as TSC1 conferred neuroprotection to preexisting OLP and regeneration via OLP proliferation. Furthermore, we showed that early TSC1 administration maximizes neuroprotection.

A model of neurodevelopmental risk and protection for preterm infants

The purpose of this article is to introduce a model of neurodevelopmental risk and protection that may explain some of the relationships among biobehavioral risks, environmental risks, and caregiving behaviors that potentially contribute to neurobehavioral and cognitive outcomes. Infants born before 30 weeks of gestation have the poorest developmental prognosis of all infants. These infants have lengthy hospitalization periods in the neonatal intensive care unit (NICU,) an environment that is not always supportive of brain development and long-term developmental needs. The model supports the premise that interventions focused on neuroprotection during the neonatal period have the potential to positively affect long-term developmental outcomes for vulnerable very preterm infants. Finding ways to better understand the complex relationships among NICU-based interventions and long-term outcomes are important to guiding caregiving practices in the NICU.

Preterm birth and neurodevelopment: a review of outcomes and recommendations for early identification and cost-effective interventions

This review summarizes research findings to date on neurological and health outcomes following preterm birth, tools to identify children at risk for neurodevelopmental impairment and interventions to prevent preterm birth and improve outcomes. We bring together findings from research in high- and low-income countries, with an aim to provide a global perspective on the issues. Around the world, preterm birth is rising in importance as a cause of under-five morbidity and mortality, and we project that this trend will continue over time, particularly given the lack of interventions to prevent the condition. With the development of improved screening instruments, further identification and scale up of cost-effective interventions to optimize early childhood development and accelerated research on the underlying biological mechanisms, we have an opportunity to reduce rates of neurodevelopmental impairment, particularly in countries with the highest burden.

Maternal prepregnancy weight status and associations with children's development and disabilities at kindergarten

OBJECTIVE

Obesity is prevalent among women of reproductive age, and developmental disabilities in children continue to increase. We examined associations between mother's prepregnancy body mass index (BMI) and physical and developmental disabilities, and objective measures of reading and math skills and fine and gross motor function in children.

METHODS

We used the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B; n=5200), a cohort of children born in 2001 and followed until kindergarten. Children were classified according to maternal prepregnancy BMI (in kg per m(2)): underweight (BMI <18.5), normal weight (BMI 18.5-24.9), overweight (BMI 25.0-29.9), obese class I (BMI 30.0-34.9) and obese class II/III (BMI ≥ 35.0). Parent reports of doctor-diagnosed disabilities were collected up to kindergarten and classified as learning and behavioral or physical. Children's reading and math and fine and gross motor function were assessed at kindergarten according to standardized tests. Linear and modified logistic regression models were adjusted for maternal sociodemographic variables, family enrichment variables, and children's sex, age and year of kindergarten entry. Additional adjustment for current child BMI was performed in separate models. All data are weighted to be nationally representative of the children born in 2001.

RESULTS

Compared with children of normal-weight mothers, children born to obese class II/III mothers had an increased risk of learning or behavioral (risk ratio 1.67; 95% confidence interval 1.27, 2.21)), but not physical disabilities (risk ratio 0.57; 95% confidence interval 0.27, 1.22). Gross (P<0.001), but not fine (P=0.06) motor function was significantly associated with maternal BMI, but gross motor function was attenuated after adjustment for current child BMI (P=0.05). Children's reading scores (P=0.01) but not math scores (P=0.11) were significantly associated with maternal BMI.

CONCLUSIONS

In this nationally representative US cohort, children born to severely obese mothers had an increased risk for diagnosed learning and behavioral but not physical disabilities by kindergarten.

Outcomes of small for gestational age infants born at <27 weeks' gestation

OBJECTIVE

To determine whether small for gestational age (SGA) infants born at <27 weeks gestational age (GA) are at increased risk for mortality, morbidity, and growth and neurodevelopmental impairment at 18-22 months corrected age.

STUDY DESIGN

This was a retrospective cohort study from National Institute of Child Health and Human Development Neonatal Research Network's Generic Database and Follow-Up Studies. Infants born at <27 weeks GA between January 2006 and July 2008 were included. SGA was defined as birth weight <10th percentile for GA based on Olsen growth curves. Infants with birth weight ≥ 10th percentile for GA were classified as non-SGA. Maternal and infant characteristics, neonatal outcomes, and neurodevelopmental data were compared in SGA and non-SGA infants. Neurodevelopmental impairment was defined as any of the following: cognitive score <70 on the Bayley Scales of Infant Development III, moderate or severe cerebral palsy, bilateral hearing loss (with and without amplification), or blindness (bilateral vision <20/200). Logistic regression analysis was applied to evaluate the associations between SGA status and death or neurodevelopmental impairment.

RESULTS

The SGA group comprised 385 infants; the non-SGA group, 2586 infants. Compared with mothers of non-SGA infants, mothers of SGA infants were more likely to have a high school education, prenatal care, cesarean delivery, pregnancy-induced hypertension, and antenatal corticosteroid exposure. Compared with non-SGA infants, SGA infants had higher mortality and were more likely to have postnatal growth failure, prolonged mechanical ventilation, and postnatal steroid use. SGA status was associated with increased risk of death or neurodevelopmental impairment (OR, 3.91; 95% CI, 2.91-5.25; P < .001).

CONCLUSION

SGA status in infants born at <27 weeks GA is associated with an increased likelihood of postnatal steroid use, mortality, growth failure, and neurodevelopmental impairment at 18-22 months corrected age.

Effects of gestational age at birth on cognitive performance: a function of cognitive workload demands

Objective

Cognitive deficits have been inconsistently described for late or moderately preterm children but are consistently found in very preterm children. This study investigates the association between cognitive workload demands of tasks and cognitive performance in relation to gestational age at birth.

Methods

Data were collected as part of a prospective geographically defined whole-population study of neonatal at-risk children in Southern Bavaria. At 8;5 years, n = 1326 children (gestation range: 23–41 weeks) were assessed with the K-ABC and a Mathematics Test.

Results

Cognitive scores of preterm children decreased as cognitive workload demands of tasks increased. The relationship between gestation and task workload was curvilinear and more pronounced the higher the cognitive workload: GA² (quadratic term) on low cognitive workload: R² = .02, p<0.001; moderate cognitive workload: R² = .09, p<0.001; and high cognitive workload tasks: R² = .14, p<0.001. Specifically, disproportionally lower scores were found for very (<32 weeks gestation) and moderately (32–33 weeks gestation) preterm children the higher the cognitive workload of the tasks. Early biological factors such as gestation and neonatal complications explained more of the variance in high (12.5%) compared with moderate (8.1%) and low cognitive workload tasks (1.7%).

Conclusions

The cognitive workload model may help to explain variations of findings on the relationship of gestational age with cognitive performance in the literature. The findings have implications for routine cognitive follow-up, educational intervention, and basic research into neuro-plasticity and brain reorganization after preterm birth.

Peroxynitrite alters GABAergic synaptic transmission in immature rat hippocampal slices

Increasing of peroxynitrite (ONOO(-)) production during ischemia in the immature brain was considered to be associated with impaired cognitive function. GABAergic synapses played an important role in memory formation including the induction of long-term potentiation (LTP) and long-term depression (LTD) in hippocampus. In the present study, we examined the effects of acute exposure of the ONOO(-) donor, SIN-1 on GABAergic synaptic transmission in immature rat hippocampal slices with whole-cell patch-clamp recordings. The results showed that SIN-1 increased the peak amplitude of evoked inhibitory postsynaptic currents (eIPSCs) and decreased paired pulse ratio via the formation of ONOO(-). In addition, it also increased the frequency of spontaneous (but not miniature) IPSCs in a dose-dependent manner without altering amplitudes or rise and decay times of both (sIPSCs and mIPSCs). It further demonstrated that the presynaptic action of SIN-1 was external calcium dependent and was not related to the changes of interneuron excitability. This study provides electrophysiological evidences from developing hippocampal slices to support that SIN-1 enhances action potential-dependent GABA release. It suggests that the potentiation effect of ONOO(-) may contribute to hyperexcitability and seizures and may underlie one of the mechanisms by which ischemia increases seizure susceptibility in the immature brain.

DISC1: a key lead in studying cortical development and associated brain disorders

For the past decade, DISC1 has been studied as a promising lead to understand the biology underlying major mental illnesses, such as schizophrenia. Consequently, many review articles on DISC1 have been published. In this article, rather than repeating comprehensive overviews of research articles, we will introduce the utility of DISC1 in the study of cortical development in association with a wide range of developmental brain disorders. Cortical development involves cell autonomous and cell nonautonomous mechanisms as well as host responses to environmental factors, all of which involve DISC1 function. Thus, we will discuss the significance of DISC1 in forming an overall understanding of multiple mechanisms that orchestrate corticogenesis and can serve as therapeutic targets in diseases caused by abnormal cortical development.

A young adult with sarcosinemia. No benefit from long duration treatment with memantine

Sarcosinemia is a rare inborn error of metabolism that is characterised by an increased level of sarcosine (N-methylglycine) in the plasma and urine. The enzymatic block results from a deficiency of sarcosine dehydrogenase (SarDH), a liver mitochondrial matrix enzyme that converts sarcosine into glycine. Although this condition may remain inapparent until later life, it has been reported in rare cases to lead to neurodevelopmental disability. A 19-year-old male with sarcosinemia presented with dystonia, developmental delay and cognitive impairment. Magnetic resonance imaging revealed vermian hypotrophy. A 2-year pharmacological treatment with memantine was negative on the clinical signs. In this case, it was concluded that the metabolic block leading to sarcosinemia was responsible of a pathologic condition with mental deficiency and complex neurological signs. A maternal isodisomy discovered in the vicinity of SarDH gene could contribute to this pathology. Deficit of SarDH may be considered as a differential diagnosis of growth failure during prenatal stages and respiratory failure at birth following a slowly progressive developmental delay.

Short and long-term analysis and comparison of neurodegeneration and inflammatory cell response in the ipsilateral and contralateral hemisphere of the neonatal mouse brain after hypoxia/ischemia

Understanding the evolution of neonatal hypoxic/ischemic is essential for novel neuroprotective approaches. We describe the neuropathology and glial/inflammatory response, from 3 hours to 100 days, after carotid occlusion and hypoxia (8% O₂, 55 minutes) to the C57/BL6 P7 mouse. Massive tissue injury and atrophy in the ipsilateral (IL) hippocampus, corpus callosum, and caudate-putamen are consistently shown. Astrogliosis peaks at 14 days, but glial scar is still evident at day 100. Microgliosis peaks at 3–7 days and decreases by day 14. Both glial responses start at 3 hours in the corpus callosum and hippocampal fissure, to progressively cover the degenerating CA field. Neutrophils increase in the ventricles and hippocampal vasculature, showing also parenchymal extravasation at 7 days. Remarkably, delayed milder atrophy is also seen in the contralateral (CL) hippocampus and corpus callosum, areas showing astrogliosis and microgliosis during the first 72 hours. This detailed and long-term cellular response characterization of the ipsilateral and contralateral hemisphere after H/I may help in the design of better therapeutic strategies.

Long-lasting paracrine effects of human cord blood cells on damaged neocortex in an animal model of cerebral palsy

Neonatal asphyxia is an important contributor to cerebral palsy (CP), for which there is no effective treatment to date. The administration of human cord blood cells (hUCBCs) is emerging as a therapeutic strategy for the treatment of neurological disorders. However, there are few studies on the application of hUCBCs to the treatment of neonatal ischemia as a model of CP. Experiments and behavioral tests (mainly motor tests) performed on neonatal hypoxia/ischemia have been limited to short-term effects of hUCBCs, but mechanisms of action have not been investigated. We performed a study on the use of hUCBCs in a rat model of neonatal hypoxia/ischemia and investigated the underlying mechanism for therapeutic benefits of hUCBC treatment. hUCBCs were intravenously transplanted into a rat model of neonatal hypoxia ischemia. hUCBCs increased microglia temporarily in the periventricular striatum in the early phase of disease, protected mature neurons in the neocortex from injury, paved the way for the near-normalization of brain damage in the subventricular zone (SVZ), and, in consequence, significantly improved performance in a battery of behavioral tests compared to the vehicle-treated group. Although the transplanted cells were rarely observed in the brain 3 weeks after transplantation, the effects of the improved behavioral functions persisted. Our preclinical findings suggest that the long-lasting positive influence of hUCBCs is derived from paracrine effects of hUCBCs that stimulate recovery in the injured brain and protect against further brain damage.

Gliosis in neonatal SUDI cases

AIM

To review sudden unexpected infant deaths (SUDI) in the first 28 days of life referred to a Coronial Perinatal Forensic Pathology Service over a 10-year period from 2000 to 2009.

METHODS

Cases were collected from mortuary records, and a retrospective review of autopsy reports and other available infant records was undertaken.

RESULTS

Twenty-four neonatal SUDI were reviewed. For eight infants, a diagnosis was made at autopsy. For the remaining 16 infants, 14 (87.5%) were bedsharing at the time of death. Maori infants and those living in deprived neighbourhoods were over-represented. Only two infants were preterm, and four were growth-restricted. At post-mortem, white matter gliosis was found in 10 of the 16 (62.5%) unexplained SUDI cases.

CONCLUSION

Sudden unexpected infant deaths occur in the first month of life in association with bedsharing. Gliosis may be an important associated risk factor, and its presence indicates a previous insult of prenatal onset.

Electrophysiological auditory responses and language development in infants with periventricular leukomalacia

This study presents evidence suggesting that electrophysiological responses to language-related auditory stimuli recorded at 46weeks postconceptional age (PCA) are associated with language development, particularly in infants with periventricular leukomalacia (PVL). In order to investigate this hypothesis, electrophysiological responses to a set of auditory stimuli consisting of series of syllables and tones were recorded from a population of infants with PVL at 46weeks PCA. A communicative development inventory (i.e., parent report) was applied to this population during a follow-up study performed at 14months of age. The results of this later test were analyzed with a statistical clustering procedure, which resulted in two well-defined groups identified as the high-score (HS) and low-score (LS) groups. The event-induced power of the EEG data recorded at 46weeks PCA was analyzed using a dimensionality reduction approach, resulting in a new set of descriptive variables. The LS and HS groups formed well-separated clusters in the space spanned by these descriptive variables, which can therefore be used to predict whether a new subject will belong to either of these groups. A predictive classification rate of 80% was obtained by using a linear classifier that was trained with a leave-one-out cross-validation technique.

Understanding aberrant white matter development in schizophrenia: an avenue for therapy?

Although historically gray matter changes have been the focus of neuropathological and neuroradiological studies in schizophrenia, in recent years an increasing body of research has implicated white matter structures and its constituent components (axons, their myelin sheaths and supporting oligodendrocytes). This article summarizes this body of literature, examining neuropathological, neurogenetic and neuroradiological evidence for white matter pathology in schizophrenia. We then look at the possible role that antipsychotic medication may play in these studies, examining both its role as a potential confounder in studies examining neuronal density and brain volume, but also the possible role that these medications may play in promoting myelination through their effects on oligodendrocytes. Finally, the role of potential novel therapies is discussed.