Neuro-Specific and Immuno-Inflammatory Biomarkers in Umbilical Cord Blood in Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVES

The aim of the study was to evaluate neuronal injury and immuno-inflammatory biomarkers in umbilical cord blood (UCB) at birth, in cases with perinatal asphyxia with or without hypoxic-ischemic encephalopathy (HIE), compared with healthy controls and to assess their ability to predict HIE.

STUDY DESIGN

In this case-control study, term infants with perinatal asphyxia were recruited at birth. UCB was stored at delivery for batch analysis. HIE was diagnosed by clinical Sarnat staging at 24 h. Glial fibrillary acidic protein (GFAP), the neuronal biomarkers tau and neurofilament light protein (NFL), and a panel of cytokines were analyzed in a total of 150 term neonates: 50 with HIE, 50 with asphyxia without HIE (PA), and 50 controls. GFAP, tau, and NFL concentrations were measured using ultrasensitive single-molecule array (Simoa) assays, and a cytokine screening panel was applied to analyze the immuno-inflammatory and infectious markers.

RESULTS

GFAP, tau, NFL, and several cytokines were significantly higher in newborns with moderate and severe HIE compared to a control group and provided moderate prediction of HIE II/III (AUC: 0.681-0.827). Furthermore, the levels of GFAP, tau, interleukin-6 (IL-6), and interleukin-8 (IL-8) were higher in HIE II/III cases compared with cases with PA/HIE I. IL-6 was also higher in HIE II/III compared with HIE I cases.

CONCLUSIONS

Biomarkers of brain injury and inflammation were increased in umbilical blood in cases with asphyxia. Several biomarkers were higher in HIE II/III versus those with no HIE or HIE I, suggesting that they could assist in the prediction of HIE II/III.

Aberrant expression of miR-199a in newborns with hypoxic-ischemic encephalopathy and its diagnostic and prognostic significance when combined with S100B and NSE

Neonatal hypoxic-ischemic encephalopathy (HIE) is a disorder mainly due to asphyxia during the perinatal period, and late diagnosis leads to high mortality. In this study, the expression of microRNA-199a (miR-199a) in HIE newborns was investigated, as well as its clinical significance in HIE diagnosis and prognosis. Circulating levels of S100B and NSE in HIE newborns were measured using enzyme-linked immunosorbent assay, and the expression of miR-199a was analyzed using quantitative real-time PCR. The diagnostic value of miR-199a, S100B and NSE was evaluated using the receiver operating characteristic (ROC) analysis, and their prognostic value was assessed by the evaluation of Gesell intellectual development of the HIE newborns. HIE newborns possessed significantly increased levels of S100B and NSE and decreased miR-199a (all P < 0.01). The Neonatal Behavioral Neurological Assessment (NBNA) score of HIE newborns was negatively correlated with S100B and NSE, while was positively correlated miR-199a. The ROC analysis results showed the diagnostic value of serum miR-199a, and the combined detection of miR-199a, S100B and NSE could obtained the highest diagnostic accuracy in HIE newborns. miR-199a expression was lowest in newborns with severe HIE, and it had diagnostic potential to distinguish HIE cases with different severity. Regarding the prognosis of neonatal HIE, the correlation of miR-199a, S100B, NSE with Gesell intellectual development was found in HIE newborns. The decreased miR-199a in HIE newborns serves as a potential diagnostic biomarker and may help to improve the diagnostic and prognostic value of S100B and NSE in neonatal HIE.

Effects of therapeutic hypothermia on death among asphyxiated neonates with hypoxic-ischemic encephalopathy: A systematic review and meta-analysis of randomized control trials

Background

Hypoxic perinatal brain injury is caused by lack of oxygen to baby’s brain and can lead to death or permanent brain damage. However, the effectiveness of therapeutic hypothermia in birth asphyxiated infants with encephalopathy is uncertain. This systematic review and meta-analysis was aimed to estimate the pooled relative risk of mortality among birth asphyxiated neonates with hypoxic-ischemic encephalopathy in a global context.

Methods

We used the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines to search randomized control trials from electronic databases (PubMed, Cochrane library, Google Scholar, MEDLINE, Embase, Scopus, Web of Science, Cochrane Central Register of Controlled Trials (CENTRAL), and meta register of Current Controlled Trials (mCRT)). The authors extracted the author’s name, year of publication, country, method of cooling, the severity of encephalopathy, the sample size in the hypothermic, and non-hypothermic groups, and the number of deaths in the intervention and control groups. A weighted inverse variance fixed-effects model was used to estimate the pooled relative risk of mortality. The subgroup analysis was done by economic classification of countries, methods of cooling, and cooling devices. Publication bias was assessed with a funnel plot and Eggers test. A sensitivity analysis was also done.

Results

A total of 28 randomized control trials with a total sample of 35, 92 (1832 hypothermic 1760 non-hypothermic) patients with hypoxic-ischemic encephalopathy were used for the analysis. The pooled relative risk of mortality after implementation of therapeutic hypothermia was found to be 0.74 (95%CI; 0.67, 0.80; I² = 0.0%; p<0.996). The subgroup analysis revealed that the pooled relative risk of mortality in low, low middle, upper-middle and high income countries was 0.32 (95%CI; -0.95, 1.60; I² = 0.0%; p<0.813), 0.5 (95%CI; 0.14, 0.86; I² = 0.0%; p<0.998), 0.62 (95%CI; 0.41–0.83; I² = 0.0%; p<0.634) and 0.76 (95%CI; 0.69–0.83; I² = 0.0%; p<0.975) respectively. The relative risk of mortality was the same in selective head cooling and whole-body cooling method which was 0.74. Regarding the cooling device, the pooled relative risk of mortality is the same between the cooling cap and cooling blanket (0.74). However, it is slightly lower (0.73) in a cold gel pack.

Conclusions

Therapeutic hypothermia reduces the risk of death in neonates with moderate to severe hypoxic-ischemic encephalopathy. Both selective head cooling and whole-body cooling method are effective in reducing the mortality of infants with this condition. Moreover, low income countries benefit the most from the therapy. Therefore, health professionals should consider offering therapeutic hypothermia as part of routine clinical care to newborns with hypoxic-ischemic encephalopathy especially in low-income countries.

Excess cerebral oxygen delivery follows return of spontaneous circulation in near-term asphyxiated lambs

Hypoxic-ischaemia renders the neonatal brain susceptible to early secondary injury from oxidative stress and impaired autoregulation. We aimed to describe cerebral oxygen kinetics and haemodynamics immediately following return of spontaneous circulation (ROSC) and evaluate non-invasive parameters to facilitate bedside monitoring. Near-term sheep fetuses [139 ± 2 (SD) days gestation, n = 16] were instrumented to measure carotid artery (CA) flow, pressure, right brachial arterial and jugular venous saturation (SaO2 and SvO2, respectively). Cerebral oxygenation (crSO2) was measured using near-infrared spectroscopy (NIRS). Following induction of severe asphyxia, lambs received cardiopulmonary resuscitation using 100% oxygen until ROSC, with oxygen subsequently weaned according to saturation nomograms as per current guidelines. We found that oxygen consumption did not rise following ROSC, but oxygen delivery was markedly elevated until 15 min after ROSC. CrSO2 and heart rate each correlated with oxygen delivery. SaO2 remained > 90% and was less useful for identifying trends in oxygen delivery. CrSO2 correlated inversely with cerebral fractional oxygen extraction. In conclusion, ROSC from perinatal asphyxia is characterised by excess oxygen delivery that is driven by rapid increases in cerebrovascular pressure, flow, and oxygen saturation, and may be monitored non-invasively. Further work to describe and limit injury mediated by oxygen toxicity following ROSC is warranted.

Neonatal hypoxia-ischemia in rat elicits a region-specific neurotrophic response in SVZ microglia

BACKGROUND

Recent findings describe microglia as modulators of neurogenesis in the subventricular zone (SVZ). SVZ microglia in the adult rat are thought to adopt a neurotrophic phenotype after ischemic stroke. Early postnatal microglia are endogenously activated and may therefore exhibit an increased sensitivity to neonatal hypoxia-ischemia (HI). The goal of this study was to investigate the impact of cortico-striatal HI on the microglial phenotype, function, and gene expression in the early postnatal SVZ.

METHODS

Postnatal day (P)7 rats underwent sham or right-hemispheric HI surgery. Microglia in the SVZ, the uninjured cortex, and corpus callosum were immunohistochemically analyzed at P10, P20, and P40. The transcriptome of microdissected SVZ and cortical microglia was analyzed at P10 and P20, and the effect of P10 SVZ microglia on neurosphere generation in vitro was studied.

RESULTS

The microglial response to HI was region-specific. In the SVZ, a microglial accumulation, prolonged activation and phagocytosis was noted that was not observed in the cortex and corpus callosum. The transcriptome of SVZ microglia and cortical microglia were distinct, and after HI, SVZ microglia concurrently upregulated pro- and anti-inflammatory as well as neurotrophic genes. In vitro, microglia isolated from the SVZ supported neurosphere generation in a concentration-dependent manner.

CONCLUSIONS

Microglia are an inherent cellular component of the early postnatal SVZ and undergo developmental changes that are affected on many aspects by neonatal HI injury. Our results demonstrate that early postnatal SVZ microglia are sensitive to HI injury and display a long-lasting region-specific response including neurotrophic features.

Novel interventions to reduce oxidative-stress related brain injury in neonatal asphyxia

Perinatal asphyxia-induced brain injury may present as hypoxic-ischemic encephalopathy in the neonatal period, and disability including cerebral palsy in the long term. The brain injury is secondary to both the hypoxic-ischemic event and the reoxygenation-reperfusion following resuscitation. Early events in the cascade of brain injury can be classified as either inflammation or oxidative stress through the generation of free radicals. The objective of this paper is to present efforts that have been made to limit the oxidative stress associated with hypoxic-ischemic encephalopathy. In the acute phase of ischemia/hypoxia and reperfusion/reoxygenation, the outcomes of asphyxiated infants can be improved by optimizing the initial delivery room stabilization. Interventions include limiting oxygen exposure, and shortening the time to return of spontaneous circulation through improved methods for supporting hemodynamics and ventilation. Allopurinol, melatonin, noble gases such as xenon and argon, and magnesium administration also target the acute injury phase. Therapeutic hypothermia, N-acetylcysteine2-iminobiotin, remote ischemic postconditioning, cannabinoids and doxycycline target the subacute phase. Erythropoietin, mesenchymal stem cells, topiramate and memantine could potentially limit injury in the repair phase after asphyxia. To limit the injurious biochemical processes during the different stages of brain injury, determination of the stage of injury in any particular infant remains essential. Currently, therapeutic hypothermia is the only established treatment in the subacute phase of asphyxia-induced brain injury. The effects and side effects of oxidative stress reducing/limiting medications may however be difficult to predict in infants during therapeutic hypothermia. Future neuroprotection in asphyxiated infants may indeed include a combination of therapies. Challenges include timing, dosing and administration route for each neuroprotectant.

Brain oxidative damage in murine models of neonatal hypoxia/ischemia and reoxygenation

The brain is one of the main organs affected by hypoxia and reoxygenation in the neonatal period and one of the most vulnerable to oxidative stress. Hypoxia/ischemia and reoxygenation leads to impairment of neurogenesis, disruption of cortical migration, mitochondrial damage and neuroinflammation. The extent of the injury depends on the clinical manifestation in the affected regions. Preterm newborns are highly vulnerable, and they exhibit severe clinical manifestations such as intraventricular hemorrhage (IVH), retinopathy of prematurity (ROP) and diffuse white matter injury (DWMI) among others. In the neonatal period, the accumulation of high levels of reactive oxygen species exacerbated by the immature antioxidant defense systems in represents cellular threats that, if they exceed or bypass physiological counteracting mechanisms, are responsible of significant neuronal damage. Several experimental models in mice mimic the consequences of perinatal asphyxia and the use of oxygen in the reanimation process that produce brain injury. The aim of this review is to highlight brain damage associated with oxidative stress in different murine models of hypoxia/ischemia and reoxygenation.

Neuroprotective strategies following perinatal hypoxia-ischemia: Taking aim at NOS

Perinatal asphyxia is characterized by oxygen deprivation and lack of perfusion in the perinatal period, leading to hypoxic-ischemic encephalopathy and sequelae such as cerebral palsy, mental retardation, cerebral visual impairment, epilepsy and learning disabilities. On cellular level PA is associated with a decrease in oxygen and glucose leading to ATP depletion and a compromised mitochondrial function. Upon reoxygenation and reperfusion, the renewed availability of oxygen gives rise to not only restoration of cell function, but also to the activation of multiple detrimental biochemical pathways, leading to secondary energy failure and ultimately, cell death. The formation of reactive oxygen species, nitric oxide and peroxynitrite plays a central role in the development of subsequent neurological damage. In this review we give insight into the pathophysiology of perinatal asphyxia, discuss its clinical relevance and summarize current neuroprotective strategies related to therapeutic hypothermia, ischemic postconditioning and pharmacological interventions. The review will also focus on the possible neuroprotective actions and molecular mechanisms of the selective neuronal and inducible nitric oxide synthase inhibitor 2-iminobiotin that may represent a novel therapeutic agent for the treatment of hypoxic-ischemic encephalopathy, both in combination with therapeutic hypothermia in middle- and high-income countries, as well as stand-alone treatment in low-income countries.

Lung injury after asphyxia and hemorrhagic shock in newborn piglets: Analysis of structural and inflammatory changes

OBJECTIVE

Asphyxia of newborns is a severe and frequent challenge of the peri- and postnatal period. The purpose of this study was to study early morphological, immunological and structural alterations in lung tissue after asphyxia and hemorrhage (AH).

METHODS

44 neonatal piglets (age 32 hrs) underwent asphyxia and hemorrhage (AH) and were treated according to the international liaison committee of resuscitation (ILCOR) guidelines. For this study, 15 piglets (blood transfusion (RBC) n = 9; NaCl n = 6, mean age 31 hrs) were randomly picked. 4 hours after ROSC (return of spontaneous circulation), lung tissue and blood samples were collected.

RESULTS

An elevation of myeloperoxidase (MPO) activity was observed 4 hrs after AH accompanied by an increase of surfactant D after RBC treatment. After AH tight junction proteins Claudin 18 and junctional adhesion molecule 1 (JAM1) were down-regulated, whereas Occludin was increased. Furthermore, after AH and RBC treatment dephosphorylated active form of Connexin 43 was increased.

CONCLUSIONS

AH in neonatal pigs is associated with early lung injury, inflammation and alterations of tight junctions (Claudin, Occludin, JAM-1) and gap junctions (Connexin 43) in lung tissue, which contributes to the development of lung edema and impaired function.

[Oxidative stress in perinatal asphyxia and hypoxic-ischaemic encephalopathy]

Birth asphyxia is one of the principal causes of early neonatal death. In survivors it may evolve to hypoxic-ischaemic encephalopathy and major long-term neurological morbidity. Prolonged and intense asphyxia will lead to energy exhaustion in tissues exclusively dependent on aerobic metabolism, such as the central nervous system. Energy deficit leads to ATP-dependent pumps blockage, with the subsequent loss of neuronal transmembrane potential. The most sensitive areas of the brain will die due to necrosis. In more resistant areas, neuronal hyper-excitability, massive entrance of ionic calcium, activation of NO-synthase, free radical generation, and alteration in mitochondrial metabolism will lead to a secondary energy failure and programmed neuronal death by means of the activation of the caspase pathways. A third phase has recently been described that includes persistent inflammation and epigenetic changes that would lead to a blockage of oligodendrocyte maturation, alteration of neurogenesis, axonal maturation, and synaptogenesis. In this scenario, oxidative stress plays a critical role causing direct damage to the central nervous system and activating metabolic cascades leading to apoptosis and inflammation. Moderate whole body hypothermia to preserve energy stores and to reduce the formation of oxygen reactive species attenuates the mechanisms that lead to the amplification of cerebral damage upon resuscitation. The combination of hypothermia with coadjuvant therapies may contribute to improve the prognosis.

Trans-resveratrol enriched maternal diet protects the immature hippocampus from perinatal asphyxia in rats

Trans-resveratrol (tRESV), a polyphenol with antioxidant properties, is common in many food sources, hence easily accessible for study as a maternal dietary supplement in perinatal asphyxia (PA). Hypoxic-ischemic encephalopathy secondary to PA affects especially vulnerable brain areas such as hippocampus and is a leading cause of neonatal morbidity. The purpose of this study is to identify new epigenetic mechanisms of brain inflammation and injury related to PA and to explore the benefit of tRESV enriched maternal diet. The hippocampal interleukin 1 beta (IL-1b), tumour necrosis factor alpha (TNFα) and S-100B protein, at 24-48h after 90min of asphyxia were assessed in postnatal day 6 rats whose mothers received either standard or tRESV enriched diet. The expression of non-coding microRNAs miR124, miR132, miR134, miR146 and miR15a as epigenetic markers of hippocampus response to PA was determined 24h post-asphyxia. Our results indicate that neural response to PA could be epigenetically controlled and that tRESV reduces asphyxia-related neuroinflammation and neural injury. Moreover, tRESV could increase, through epigenetic mechanisms, the tolerance to asphyxia, with possible impact on the neuronal maturation. Our data support the neuroprotective quality of tRESV when used as a supplement in the maternal diet on the offspring's outcome in PA.

Oxygen and oxidative stress in the perinatal period

Fetal life evolves in a hypoxic environment. Changes in the oxygen content in utero caused by conditions such as pre-eclampsia or type I diabetes or by oxygen supplementation to the mother lead to increased free radical production and correlate with perinatal outcomes. In the fetal-to-neonatal transition asphyxia is characterized by intermittent periods of hypoxia ischemia that may evolve to hypoxic ischemic encephalopathy associated with neurocognitive, motor, and neurosensorial impairment. Free radicals generated upon reoxygenation may notably increase brain damage. Hence, clinical trials have shown that the use of 100% oxygen given with positive pressure in the airways of the newborn infant during resuscitation causes more oxidative stress than using air, and increases mortality. Preterm infants are endowed with an immature lung and antioxidant system. Clinical stabilization of preterm infants after birth frequently requires positive pressure ventilation with a gas admixture that contains oxygen to achieve a normal heart rate and arterial oxygen saturation. In randomized controlled trials the use high oxygen concentrations (90% to 100%) has caused more oxidative stress and clinical complications that the use of lower oxygen concentrations (30-60%). A correlation between the amount of oxygen received during resuscitation and the level of biomarkers of oxidative stress and clinical outcomes was established. Thus, based on clinical outcomes and analytical results of oxidative stress biomarkers relevant changes were introduced in the resuscitation policies. However, it should be underscored that analysis of oxidative stress biomarkers in biofluids has only been used in experimental and clinical research but not in clinical routine. The complexity of the technical procedures, lack of automation, and cost of these determinations have hindered the routine use of biomarkers in the clinical setting. Overcoming these technical and economical difficulties constitutes a challenge for the immediate future since accurate evaluation of oxidative stress would contribute to improve the quality of care of our neonatal patients.

Molecular hydrogen affords neuroprotection in a translational piglet model of hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is the major consequence of perinatal asphyxia (PA) in term neonates. Although the newborn piglet is an accepted large animal PA/HIE model, there is no consensus on PA-induction methodology to produce clinically relevant HIE. We aimed to create and to characterize a novel PA model faithfully reproducing all features of asphyxiation including severe hypercapnia resulting in HIE, and to test whether H₂ is neuroprotective in this model. Piglets were anaesthetised, artificially ventilated, and intensively monitored (electroencephalography, core temperature, O₂ saturation, arterial blood pressure and blood gases). Asphyxia (20 min) was induced by ventilation with a hypoxic-hypercapnic (6%O₂ - 20%CO₂) gas mixture. Asphyxia-induced changes in the cortical microcirculation were assessed with laser-speckle contrast imaging and analysis. Asphyxia was followed by reventilation with air or air containing hydrogen (2.1%H₂, 4 hours). After 24 hours survival, the brains were harvested for neuropathology. Our PA model was characterized by the development of severe hypoxia (pO2 = 27 ± 4 mmHg), and combined acidosis (pH = 6.76 ± 0.04; pCO₂ = 114 ± 11 mmHg; lactate = 12.12 ± 0.83 mmol/L), however, cortical ischemia did not develop during the stress. Severely depressed electroencephalography (EEG), and marked neuronal injury indicated the development of HIE. H₂ was neuroprotective shown both by the enhanced recovery of EEG and by the significant preservation of neurons in the cerebral cortex, hippocampus, basal ganglia, and the thalamus. H2 appeared to reduce oxidative stress shown by attenuation of 8-hydroxy-2'-deoxyguanosine immunostaining. In summary, this new PA piglet model is able to induce moderate/severe HIE, and the efficacy of hydrogen post-treatment to preserve neuronal activity/function in this PA/HIE model suggests the feasibility of this safe and inexpensive approach in the treatment of asphyxiated babies.

[Effect of leptin on expression of calpain-1 and Bcl-2 and apoptosis in myocardial tissue of neonatal rats after asphyxia]

OBJECTIVE

To study the effect of leptin on the expression of calcium-activated neutral protease 1 (calpain-1) and B cell lymphoma-2 (Bcl-2) and apoptosis in the myocardial tissue of neonatal rats after asphyxia.

METHODS

A total of 48 neonatal rats were randomly and equally divided into normal control group, asphyxia group, leptin treatment groups, and calpain-1 inhibitor (CAI-1) group. The neonatal rat model of asphyxia under normal atmospheric condition was established in all groups except the control group. For the leptin treatment groups, rats received 20, 80, and 160 μg/kg leptin by intraperitoneal injection immediately after model establishment, respectively. For the CAI-1 group, rats received 10 mg/kg CAI-1 by intraperitoneal injection immediately after model establishment. For all the groups, the myocardial tissue was collected at 2 hours after model establishment. Immunohistochemistry was used to measure the expression of calpain-1 and Bcl-2. The TUNEL method was used to evaluate apoptosis of myocardial cells.

RESULTS

The expression of calpain-1 and Bcl-2 and apoptosis index (AI) were significantly higher in the asphyxia group than in the normal control group (P˂0.05). The leptin treatment groups and the CAI-1 group had significantly lower expression of calpain-1, significantly lower AI, and significantly higher expression of Bcl-2 than the asphyxia group (P˂0.05). The CAI-1 group had the largest changes in all the indices compared with the asphyxia group. However, there were no significant differences in all indices between the 160 μg/kg leptin treatment group and the CAI-1 group. After asphyxia, the expression of calpain-1 was positively correlated with AI, while the expression of Bcl-2 was negatively correlated with AI and the expression of calpain-1 (P˂0.05).

CONCLUSIONS

Leptin reduces apoptosis of myocardial cells in asphyxiated neonatal rats by the inhibition of calpain-1 activation and upregulation of Bcl-2 expression.

Inflammatory Biomarkers of Birth Asphyxia

Although therapies in addition to whole-body cooling are being developed to treat the neonate at risk for hypoxic-ischemic encephalopathy, we have no quickly measured serum inflammatory or neuronal biomarkers to acutely and accurately identify brain injury or to follow the efficacy of therapy. This review covers inflammatory serum biomarkers in the setting of birth asphyxia that can help assess the degree or severity of encephalopathy at birth and neurodevelopmental outcomes. These biomarkers still need to be independently validated in large cohorts before they are ready for clinical implementation in practice.

The Role of Plasma and Urine Metabolomics in Identifying New Biomarkers in Severe Newborn Asphyxia: A Study of Asphyxiated Newborn Pigs following Cardiopulmonary Resuscitation

BACKGROUND

Optimizing resuscitation is important to prevent morbidity and mortality from perinatal asphyxia. The metabolism of cells and tissues is severely disturbed during asphyxia and resuscitation, and metabolomic analyses provide a snapshot of many small molecular weight metabolites in body fluids or tissues. In this study metabolomics profiles were studied in newborn pigs that were asphyxiated and resuscitated using different protocols to identify biomarkers for subject characterization, intervention effects and possibly prognosis.

METHODS

A total of 125 newborn Noroc pigs were anesthetized, mechanically ventilated and inflicted progressive asphyxia until asystole. Pigs were randomized to resuscitation with a FiO2 0.21 or 1.0, different duration of ventilation before initiation of chest compressions (CC), and different CC to ventilation ratios. Plasma and urine samples were obtained at baseline, and 2 h and 4 h after return of spontaneous circulation (ROSC, heart rate > = 100 bpm). Metabolomics profiles of the samples were analyzed by nuclear magnetic resonance spectroscopy.

RESULTS

Plasma and urine showed severe metabolic alterations consistent with hypoxia and acidosis 2 h and 4 h after ROSC. Baseline plasma hypoxanthine and lipoprotein concentrations were inversely correlated to the duration of hypoxia sustained before asystole occurred, but there was no evidence for a differential metabolic response to the different resuscitation protocols or in terms of survival.

CONCLUSIONS

Metabolic profiles of asphyxiated newborn pigs showed severe metabolic alterations. Consistent with previously published reports, we found no evidence of differences between established and alternative resuscitation protocols. Lactate and pyruvate may have a prognostic value, but have to be independently confirmed.

Cerebral blood flow and oxygenation in infants after birth asphyxia. Clinically useful information?

The term 'luxury perfusion' was coined nearly 50 years ago after observation of bright-red blood in the cerebral veins of adults with various brain pathologies. The bright-red blood represents decreased oxygen extraction and hence the perfusion is 'luxurious' compared to oxygen needs. Gradual loss of cellular energy charge during the hours following severe birth asphyxia was observed twenty years later by sequential cranial magnetic resonance spectroscopy. This led to the concept of delayed energy failure that is linked to mitochondrial dysfunction and apoptotic cell death. Abnormally increased perfusion and lack of normal cerebral blood flow regulation are also typically present, but whether the perfusion abnormalities at this secondary stage are detrimental, beneficial, or a mere epiphenomenon remains elusive. In contrast, incomplete reoxygenation of the brain during and following resuscitation is likely to compromise outcome. The clinical value of cerebral oximetry in this context can only be examined in a randomised clinical trial.

Neonatal encephalopathic cerebral injury in South India assessed by perinatal magnetic resonance biomarkers and early childhood neurodevelopmental outcome

Although brain injury after neonatal encephalopathy has been characterised well in high-income countries, little is known about such injury in low- and middle-income countries. Such injury accounts for an estimated 1 million neonatal deaths per year. We used magnetic resonance (MR) biomarkers to characterise perinatal brain injury, and examined early childhood outcomes in South India.

METHODS

We recruited consecutive term or near term infants with evidence of perinatal asphyxia and a Thompson encephalopathy score ≥6 within 6 h of birth, over 6 months. We performed conventional MR imaging, diffusion tensor MR imaging and thalamic proton MR spectroscopy within 3 weeks of birth. We computed group-wise differences in white matter fractional anisotropy (FA) using tract based spatial statistics. We allocated Sarnat encephalopathy stage aged 3 days, and evaluated neurodevelopmental outcomes aged 3½ years using Bayley III.

RESULTS

Of the 54 neonates recruited, Sarnat staging was mild in 30 (56%); moderate in 15 (28%) and severe in 6 (11%), with no encephalopathy in 3 (6%). Six infants died. Of the 48 survivors, 44 had images available for analysis. In these infants, imaging indicated perinatal rather than established antenatal origins to injury. Abnormalities were frequently observed in white matter (n = 40, 91%) and cortex (n = 31, 70%) while only 12 (27%) had abnormal basal ganglia/thalami. Reduced white matter FA was associated with Sarnat stage, deep grey nuclear injury, and MR spectroscopy N-acetylaspartate/choline, but not early Thompson scores. Outcome data were obtained in 44 infants (81%) with 38 (79%) survivors examined aged 3½ years; of these, 16 (42%) had adverse neurodevelopmental outcomes.

CONCLUSIONS

No infants had evidence for established brain lesions, suggesting potentially treatable perinatal origins. White matter injury was more common than deep brain nuclei injury. Our results support the need for rigorous evaluation of the efficacy of rescue hypothermic neuroprotection in low- and middle-income countries.

Ultrasound parameters and L/S ratio in prediction of perinatal outcome in term-growth restricted newborns

AIM

The relation between biophysical profile (BPP), cerebroplacental (C/P) ratio, and lecithin/sphingomyelin (L/S) ratio as a predictor perinatal outcome in term intrauterine growth restricted (IUGR) neonates was evaluated.

MATERIALS AND METHODS

A retrospective study of the perinatal outcome of 77 term monofetal pregnancies complicated with IUGR fetuses (< 10 percentile) who were terminated by cesarean section in 2010 was performed at the Institute of Gynecology and Obstetrics, Belgrade.

RESULTS

The most frequent early neonatal complication was asphyxia. The authors found a strong correlation between the L/S ratio and birth weight (BW) r = 0.609, as well as between BPP and Apgar score 5 r = 0.583. Significant negative correlation was found between asphyxia and BPP r = -0.398, as well as between asphyxia and C/P ratio r = -0.379.

CONCLUSION

In serous IUGR neonates, low values of BPP and L/S ratios predicted asphyxia.

Changes of positron emission tomography in newborn infants at different gestational ages, and neonatal hypoxic-ischemic encephalopathy

Cerebral glucose metabolism was measured by (18)F-fluorodeoxyglucose position emission tomography in infants at different gestational ages and with neonatal hypoxic-ischemic encephalopathy. Thirty-six preterm and term infants at different gestational ages without brain injury were divided into four subgroups: ≤32 weeks (n = 4), 33-34 weeks (n = 5), 35-36 weeks (n = 12), and ≥37 weeks (n = 15). Twenty-four newborn infants with hypoxic-ischemic encephalopathy were divided into three subgroups: mild (n = 13), moderate (n = 7), and severe (n = 4). Cerebral glucose metabolism manifested a trend toward increase, and the structure of cranial (18)F-fluorodeoxyglucose positron emission tomography images became clear with increased gestational age, especially at ≥37 weeks. Uptakes of (18)F-fluorodeoxyglucose in the ≥37-week group were significantly higher than in the ≤32-week group (P < 0.01). Cerebral glucose metabolism changed significantly in neonatal hypoxic-ischemic encephalopathy, and was either unbalanced bilaterally or relatively low at all sites. Moreover, uptakes of (18)F-fluorodeoxyglucose were significantly lower in severe than in mild and medium hypoxic-ischemic encephalopathy (P < 0.05). Cerebral glucose metabolism, as measured by (18)F-fluorodeoxyglucose positron emission tomography, may prove useful for estimating brain development and injury in newborn infants, and its clinical values need further investigation.

End-tidal CO₂ detection of an audible heart rate during neonatal cardiopulmonary resuscitation after asystole in asphyxiated piglets

Even brief interruption of cardiac compressions significantly reduces critical coronary perfusion pressure during cardiopulmonary resuscitation (CPR). End-tidal CO₂ (ETCO₂) monitoring may provide a continuous noninvasive method of assessing return of spontaneous circulation (ROSC) without stopping to auscultate for heart rate (HR). However, the ETCO₂ value that correlates with an audible HR is unknown. Our objective was to determine the threshold ETCO₂ that is associated with ROSC after asphyxia-induced asystole. Neonatal swine (n = 46) were progressively asphyxiated until asystole occurred. Resuscitation followed current neonatal guidelines with initial ventilation with 100% O₂ followed by cardiac compressions followed by epinephrine for continued asystole. HR was auscultated every 30 s, and ETCO₂ was continuously recorded. A receiver operator curve was generated using the calculated sensitivity and specificity for various ETCO₂ values, where a positive test was defined as the presence of HR >60 bpm by auscultation. An ETCO₂ cut-off value of 14 mm Hg is the most sensitive ETCO₂ value with the least false positives. When using ETCO₂ to guide uninterrupted CPR in this model of asphyxia-induced asystole, auscultative confirmation of return of an adequate HR should be performed when ETCO₂ ≥ 14 mm Hg is achieved. Correlation during human neonatal CPR needs further investigation.

[Effects of Ucf-101 on expression of Omi/HtrA2 in kidneys of postasphyxial neonatal rats]

OBJECTIVE

To investigate the expression of serine protease Omi/HtrA2 in kidneys of postasphyxial neonatal rats, and to study the effects of Ucf-101 on apoptosis and the expression of Omi/HtrA2 in these rats.

METHODS

Seventy-two neonatal Wistar rats of 7-10 days old were randomly divided into 3 groups: control, postasphyxial model, Ucf-101-treated postasphyxialThe postasphyxial model was established by normobaric asphyxiaExpression of Omi/HtrA2 was determined with streptavidin-peroxidase immunohistochemistry 2, 24 and 48 hrs after asphyxia. Terminal deoxynuleotidyl-mediated nick end labeling (TUNEL) was used to ascertain the apoptosis of renal cells.

RESULTS

Compared with the control group, OmiHtrA2 expression in renal cells began to increase 2 hrs after asphyxia and peaked at 24 hrs. The expression of Omi/HtrA2 in the Ucf-101-treated postasphyxial group was significantly lower than that in the postasphyxial model group (P<0.01). TUNEL-positive cells began to increase 2 hrs after asphyxia and peaked at 24 hrs in the postasphyxial model group when compared with the control group. The number of TUNEL-positive cells in the Ucf-101-treated postasphyxial group was significantly lower than that in the postasphyxial model group at all time points (P<0.01).

CONCLUSIONS

The expression of Omi/HtrA2 in kidneys is increased in postasphyxial neonatal rats. The increased Omi/HtrA2 expression may play an important role in the development of postasphyxial renal injury. Treatment with Ucf-101 can reduce the expression of Omi/HtrA2 in kidneys of postasphyxial neonatal rats and thus reduce renal tububar epithelial cell apoptosis.

Nitrated plasma albumin as a marker of nitrative stress and neonatal encephalopathy in perinatal asphyxia

Reactive nitrogen species (RNS) have been shown to play a major role in the pathophysiology of hypoxic-ischemic cerebral injury. Using a novel sensitive ELISA allowing the quantification of nitrated albumin (nitroalbumin) in plasma, we tested the hypothesis that perinatal asphyxia increases nitrating RNS generation by verifying whether the concentration of one of its target proteins is correlated with the clinical outcome. We assayed nitroalbumin in 114 plasma samples collected during the first hour, at day 1, and at day 4 of life from 48 term newborns suffering from perinatal asphyxia and correlated this marker with neurological and systemic neonatal outcomes. Nitroalbumin levels at day 1, but not at days 0 and 4, were significantly increased in patients who developed moderate or severe encephalopathy compared to those who had a normal neurological evolution or developed mild encephalopathy (median: 14.4 ng/ml versus 7.3 ng/ml, respectively). In contrast, nitroalbumin concentration at day 1 was not associated with systemic complications. First-hour and fourth-day nitroalbumin concentrations did not differ with respect to the neonatal neurological course. At day 0, nitroalbumin levels also correlated with circulating leukocytes. We conclude that plasma nitroalbumin seems to be a specific marker of neurological injury after perinatal asphyxia and may serve as a secondary end-point in neuroprotective clinical trials.

How much and for how long does the neonatal myocardium suffer from mild perinatal asphyxia?

Cardiac troponins can be useful in monitoring cardiac injury following perinatal distress. We report here an increase of cardiac troponin I (cTnI) to 2.84 microg/l at 3 weeks (age-related median: 0.07 microg/l) followed by normalization in a newborn with an uneventful clinical course after resuscitation at birth. Serial echocardiographs showed normal cardiac function. Such a time course of cTnI, not previously reported, could be due to either a greater sensitivity of biochemical markers than of instrumental tools or birth asphyxia. Larger studies are needed

Linoleic and arachidonic acid in perinatal asphyxia and prematurity

OBJECTIVES

Long-chain polyunsaturated fatty acids (LC-PUFA) are important for fetal and infant growth and development. The effects of prematurity and perinatal asphyxia on the levels of linoleic acid (LA) and arachidonic acid (AA) in plasma and red blood cell (RBC) membranes were investigated.

METHODS

Fifty-five neonates were studied: 18 full term neonates with perinatal asphyxia (group A), nine preterm neonates (group B), and 28 healthy term neonates (group C). Non-esterified and total levels of LA and AA in plasma and RBC membranes were estimated using gas chromatography within the first day of life. Malondialdehyde (MDA) levels were measured using the thiobarbituric acid (TBA) reactivity method.

RESULTS

Compared to group C, statistically significant lower levels of plasma free and total AA and free LA were observed in group A, whereas statistically significant higher levels of RBC total LA and AA were observed in RBC membranes of group B. A negative correlation between MDA and LC-PUFA levels was found.

CONCLUSION

Perinatal asphyxia is associated with a reduction in LC-PUFA levels, most likely as a result of increased oxidative stress. Premature infants soon after birth have higher LC-PUFA levels than term neonates, probably reflecting the overall metabolic activity and/or intrauterine transport of LC-PUFA.

Oxidative stress of the newborn in the pre- and postnatal period and the clinical utility of melatonin

Newborns, and especially those delivered preterm, are probably more prone to oxidative stress than individuals later in life. Also during pregnancy, increased oxygen demand augments the rate of production of reactive oxygen species (ROS) and women, even with normal pregnancies, experience elevated oxidative stress and lipid peroxidation compared with nonpregnant women. Also, there appears to be an increase in ROS generation in the placenta of pre-eclamptic women. In comparison with healthy adults, newborn infants have lower levels of plasma antioxidants such as vitamin E, beta-carotene, and sulphydryl groups, lower levels of plasma metal binding proteins including ceruloplasmin and transferrin, and reduced activity of erythrocyte superoxide dismutase. This review summarizes conditions of newborns where there is elevated oxidative stress. Included in this group of conditions is asphyxia, respiratory distress syndrome and sepsis and the review also summarizes the literature related to clinical trials of antioxidant therapies and of melatonin, a highly effective antioxidant and free radical scavenger. The authors document there is general agreement that short-term melatonin therapy may be highly effective and that it has a remarkably benign safety profile, even when neonates are treated with pharmacological doses. Significant complications with long-term melatonin therapy in children and adults also have not been reported. None of the animal studies of maternal melatonin treatment or in postnatal life have shown any treatment-related side effects. The authors conclude that treatment with melatonin might result in a wide range of health benefits, improved quality of life and reduced healthcare costs and may help reduce complications in the neonatal period.

Neonatal encephalopathy: treatment with hypothermia

In this article, the role of hypothermia and neuroprotection for neonatal encephalopathy will be discussed. The incidence of encephalopathy due to hypoxia ischemia as well as the pathophysiology will be presented. The diagnosis of encephalopathy in full-term neonates will be discussed. The current management of brain injury that occurs with hypoxia ischemia and the role of hypothermia in preventing brain injury in fetal and neonatal animal models will be reviewed. The current data from randomized control trials of hypothermia as neuroprotection for full-term infants will be presented along with the results of meta-analyses of these trials. Lastly, the status of ongoing neonatal hypothermia trials will be summarized.

Do apparent diffusion coefficient measurements predict outcome in children with neonatal hypoxic-ischemic encephalopathy?

BACKGROUND AND PURPOSE

Diffusion-weighted imaging (DWI) permits early detection and quantification of hypoxic-ischemic (HI) brain lesions. Our aim was to assess the predictive value of DWI and apparent diffusion coefficient (ADC) measurements for outcome in children with perinatal asphyxia.

MATERIALS AND METHODS

Term neonates underwent MR imaging within 10 days after birth because of asphyxia. MR imaging examinations were retrospectively evaluated for HI brain damage. ADC was measured in 30 standardized brain regions and in visibly abnormal areas on DWI. In survivors, developmental outcome until early school age was graded into the following categories: 1) normal, 2) mildly abnormal, and 3) definitely abnormal. For analysis, category 3 and death (category 4) were labeled "adverse," 1 and 2 were "favorable," and 2-3 and death were "abnormal" outcome. Differences in outcome between infants with and without DWI abnormalities were analyzed by using chi(2) tests. The nonparametric Mann-Whitney U test analyzed whether ADC values in visible DWI abnormalities correlated with age at imaging. Logistic regression analysis tested the predictive value for outcome of the ADC in each standardized brain region. Receiver operating characteristic analysis was used to find optimal ADC cutoff values for each region for the various outcome scores.

RESULTS

Twenty-four infants (13 male) were included. Mean age at MR imaging was 4.3 days (range, 1-9 days). Seven infants died. There was no difference in outcome between infants with and without visible DWI abnormalities. Only ADC of the posterior limb of the internal capsule correlated with age. ADC in visibly abnormal DWI regions did not have a predictive value for outcome. Of all measurements performed, only the ADC in the normal-appearing basal ganglia and brain stem correlated significantly with outcome; low ADC values were associated with abnormal/adverse outcome, and higher ADC values, with normal/favorable outcome (basal ganglia: P = .03 for abnormal, P = .01 for adverse outcome; brain stem: P = .006 for abnormal, P = .03 for adverse outcome).

CONCLUSIONS

ADC values in normal-appearing basal ganglia and brain stem correlated with outcome, independently of all MR imaging findings including those of DWI. ADC values in visibly abnormal brain tissue on DWI did not show a predictive value for outcome.

CDP-choline (citicoline) attenuates brain damage in a rat model of birth asphyxia

To estimate protective potential of citicoline in a model of birth asphyxia, the drug was given to 7-day old rats subjected to permanent unilateral carotid artery occlusion and exposed for 65 min to a hypoxic gas mixture. Daily citicoline doses of 100 or 300 m/kg, or vehicle, were injected intraperitoneally for 7 consecutive days beginning immediately after the end of the ischemic-hypoxic insult, and brain damage was assessed by gross zorphology score and weight deficit two weeks after the insult. Caspase-3, alpha-fodrin, Bcl-2, and Hsp70 levels were assessed at 0, 1, and 24 h after the end of the hypoxic insult in another group of rat pups subjected to the same insult and given a single dose of 300 m/kg of citicoline or the vehicle. Citicoline markedly reduced caspase-3 activation and Hsp70 expression 24 h after the insult, and dose-dependently attenuated brain damage. In the context of the well-known excellent safety profile of citicoline, these data suggest that clinical evaluation of the efficacy of the drug in human birth asphyxia may be warranted.

Nitrotyrosine in human neonatal spinal cord after perinatal asphyxia

BACKGROUND

Spinal cord injury has been reported after perinatal asphyxia in full-term neonates.

OBJECTIVES

To examine the role of excessive nitric oxide production in perinatal spinal cord injury.

SUBJECTS AND METHODS

Tissue samples of 18 full-term neonates who died of hypoxic-ischemic encephalopathy were analyzed for the presence of nitrotyrosine (NT).

RESULTS

NT was demonstrated in 5 of these 18 neonates. In addition, activated caspase 3, a marker of apoptosis, and CD68, as a marker of inflammation, could be demonstrated in some infants.

CONCLUSIONS

excessive nitric oxide production and subsequent NT formation is seen in spinal cord tissue after severe perinatal asphyxia. This finding may be relevant for the development of neuroprotective strategies.

The sex differences of cerebrospinal fluid levels of interleukin 8 and antioxidants in asphyxiated newborns

Newborn males are more sensitive to brain injury than newborn females are. The aim of the present study was to find an explanation for this. We used the neuron-specific enolase (NSE) levels in the cerebrospinal fluid (CSF) for the classification of 32 newborns (19 males and 13 females) on their fifth postnatal day. The NSE levels were higher than normal (8.4 +/- 1.6 ng/mL) in 10 newborn males and 6 females and were, respectively, considered asphyxiated male and female groups. The remaining newborns, 9 males and 7 females, had normal CSF levels of NSE and were considered normal newborn male and female groups. The CSF samples were measured for 12 cytokines, using a cytokine array kit, and for total hydroperoxide and biological antioxidant potentials (BAPs), using the free radical analytic system. Among the 12 cytokines measured, only interleukin 8 (IL-8) was properly detected. The CSF levels of IL-8 were higher in the asphyxiated newborn females than in the other three groups. The mean CSF levels of BAPs in the asphyxiated newborn females were higher compared with the other three groups, but significance was detected only in comparison with the BAP levels in the CSF samples of the normal newborn males. There were no differences in total hydroperoxide levels among the groups. There are sex-related differences in the CSF levels of IL-8 and antioxidants in asphyxiated newborns, with higher levels in newborn females; this might contribute in the sexual dimorphism regarding the fact that females have better protection from brain injury than the males.

[Birth asphyxia and hypoxic ischemic encephalopathy, incidence and obstetric risk factors]

OBJECTIVE

Modern medical practice has changed dramatically during the past decades because of improved technology. Still, fetal surveillance during labor is relatively unchanged since 1960 s when fetal heart rate monitoring (FHR) became standard practice. Newborn infants are still suffering from birth asphyxia and in severe cases leading to hypoxic ischemic encephalopathy (HIE) which sometimes results in permanent neurological damage. The incidence of birth asphyxia and HIE in Iceland is unknown and so are the risk factors for severe asphyxia. The objective of this study was to assess the incidence, obstetric risk factors and the sequela of severe asphyxia at Landspitali university hospital (LSH).

MATERIAL AND METHODS

All term infants born at LSH from 1.1.1997- 31.12.2001 with birth asphyxia, defined as five minute Apgar score %lt;6, were included in the study (n=127). Clinical information were collected retrospectively from maternal records on maternal diseases during pregnancy, cardiotocogram (CTG), type of birth, the presence of meconium and operative delivery rates. Information was also collected regarding birth asphyxia and HIE in the neonatal period.

RESULTS

The incidence of birth asphyxia was 9.4/1000 live term births during the study period, with increasing incidence during the three last years. The incidence of HIE was 1.4/ 1,000 live term births. Severe maternal diseases during pregnancy were not a significant risk factor for asphyxia. The amniotic fluid was meconium stained in fifty percent of cases and the umbilical cord was wrapped around the fetal neck in 41% of cases. Abnormal CTG tracing was observed in 66% of cases in the study group and in 79% of the HIE cases. Operative deliveries were significantly more common in the study cohort compared with other deliveries at LSH at the same time: ventouse delivery 22% vs 6.8% (p<0,001), forceps delivery 6.3% vs 1,03% (p<0,001), emergency cesarean section 19.7% vs 11.4% ( p=0,008).

CONCLUSION

The incidence of birth asphyxia is higher in LSH compared with the incidence found in other studies. Signs of fetal distress on CTG and delivery with operative interventions are common. With current available methods to detect intrapartum asphyxia there is a poor correlation with CTG and the development of HIE after severe asphyxia. The presence of severe maternal diseases does not correlate with increased incidence of asphyxia, presumably due to increased surveillance of these pregnancies and a lower treshold for intervention during delivery. In low risk pregnancies there is a lack of appropriate methods with high sensitivity and specificity to detect intrapartum asphyxia.

Can tissue oxygenation index (TOI) and cotside neurophysiological variables predict outcome in depressed/asphyxiated newborn infants?

BACKGROUND

Diagnostic tools of birth asphyxia provide only an uncertain prediction of neurological outcome.

AIMS

To assess whether TOI and DeltaCBV, combined with a set of biochemical and neurophysiological variables, have any diagnostic and prognostic value in birth depression or asphyxia.

STUDY DESIGN

Case control study at the nursery and NICU of the Padova University Children's Hospital.

SUBJECTS

22 term neonates with an Apgar score < or = 6 at 5', a 1-h umbilical artery pH value < or = 7.25 with an increased base deficit and a gestational age > or = 36 weeks; 15 healthy term infants with an Apgar score > or = 9 at 5'.

OUTCOME MEASURES

Troponin I and NIRS measurements (TOI and DeltaCBV) were assessed in both groups. Blood gases, neurological evaluation, US, NIRS, EEG and SEP were evaluated in the infants with depression or asphyxia.

RESULTS

Troponin I was higher in the study group than in controls (p=0.04), showing a correlation with base excess values. In the depressed/asphyxiated neonates with an abnormal outcome at 1 year, TOI rose to 80.1% vs 66.4% in controls (p=0.04) and 74.7% in infants with a normal 1-year outcome. A multiple regression model showed a significant multiple correlation coefficient, R=0.79, p<0.001, where the predictive variables significantly associated with outcome were SEP and BE.

CONCLUSIONS

Troponin I is a useful short-term index of birth asphyxia or perinatal depression. An increased TOI suggests a risk of abnormal neurological outcome at 1 year. Among the cotside variables, BE and evoked potential abnormalities were the best predictors of abnormal outcome in this study.

Plasma and urinary endothelin-1 concentrations in asphyxiated newborns [corrected]

The aim of this study was to determine if there is any correlation between the hypoxia induced deterioration of renal functions and urinary excretions of endothelin (ET). Therefore using a sensitive and specific radioimmunoassay, we have investigated plasma ET-1 concentrations and urine ET-1 excretions in healthy and asphyxiated newborns. Sixteen newborns (10 boys, 6 girls) with perinatal asphyxia or hypoxia of variable seriousness which were followed at Newborn Intensive Care Unit in Eskisehir Osmangazi University Faculty of Medicine were enrolled. Simultaneously, gestation and weight matched 10 newborns (6 boys, 4 girls) with no asphyxia (first minute Apgar score >7) were enrolled as controls. Plasma ET-1 concentrations of the asphyxiated infants (61.8+/-79.3 pg/ml, between 23.4-125.2 pg/ml) were higher than in the control group (29.3+/-22.1 pg/ml, between 12.3 and 50.8 pg/ml, p<0.05). However creatinine clearance values were not different between the two groups (p>0.05), mean fractional excretion of sodium levels (FeNa%) were higher in the study group than the controls (p<0.01). Urinary ET-1 concentrations in the asphyxiated infants were 144.6+/-63.4 pg/ml versus 70.1+/-27.7 pg/ml in the control group (p<0.001). The ET clearance were more elevated in the asphyxiated newborns than in the healthy infants (p<0.05). Urinary ET-1/Cr ratio in the hypoxic infants were significantly elevated in the first day of life when compared with those of healthy infants (p<0.05). Total ET excretion was negatively correlated with FeNa (%) (r=-0.603, p<0.05). Plasma ET-1 concentrations of the asphyxiated infants reduced at 48 hours of age (p<0.001). Fifth minute Apgar score was negatively correlated with urinary ET-1 levels (r=-0.615, p<0.01), urinary Na excretion (r=-0.583, p<0.01), FeNa (%) (r=-0.597, p<0.01) and total ET excretion (r=-0.560, p<0.01) and positively correlated with ET clearance (r=0.559, p<0.05). Urinary ET-1 levels were negatively correlated with umbilical artery BE levels (r=-0.612, p<0.05). To our study, elevated urinary ET-1 levels were observed during perinatal asphyxia and urinary ET-1 levels were negatively correlated with 5th minute Apgar score and cord blood base excess levels. For this reason urinary ET-1 levels could be a marker of perinatal asphyxia as cord blood ET-1 levels. With investigations showing renal production is independent from plasma and increased urinary ET-1/Cr levels in newborn with perinatal asphyxia and also negative correlation between the total ET excretion and FeNa, urinary ET-1 levels could be served as a useful marker to detecting also impaired renal functions in infants with perinatal asphyxia.

Relationship between opioid therapy, tissue-damaging procedures, and brain metabolites as measured by proton MRS in asphyxiated term neonates

To examine the effects of opioid and tissue-damaging procedures (TDPs) [i.e. procedures performed in the neonatal intensive care unit (NICU) known to result in pain, stress, and tissue damage] on brain metabolites, we reviewed the medical records of 28 asphyxiated term neonates (eight opioid-treated, 20 non-opioid treated) who had undergone magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopy (MRS) within the first month of life as well as eight newborns with no clinical findings of asphyxial injury. We found that lower creatine (Cr), myoinositol (Ins), and N-acetylaspartate (NAA)/choline (Cho) (p < or = 0.03) and higher Cho/Cr and glutamate/glutamine (Glx) Cr (p < or = 0.02) correlated with increased TDP incidence in the first 2 d of life (DOL). We also found that occipital gray matter (OGM) NAA/Cr was decreased (p = 0.03) and lactate (Lac) was present in a significantly higher amount (40%; p = 0.03) in non-opioid-treated neonates compared with opioid-treated neonates. Compared with controls, untreated neonates showed larger changes in more metabolites in basal ganglia (BG), thalami (TH), and OGM with greater significance than treated neonates. Our data suggest that TDPs affect spectral metabolites and that opioids do not cause harm in asphyxiated term neonates exposed to repetitive TDPs in the first 2-4 DOL and may provide a degree of neuroprotection.

Glutamate-mediated excitotoxicity in neonatal hippocampal neurons is mediated by mGluR-induced release of Ca++ from intracellular stores and is prevented by estradiol

Hypoxic/ischemic (HI) brain injury in newborn full-term and premature infants is a common and pervasive source of life time disabilities in cognitive and locomotor function. In the adult, HI induces glutamate release and excitotoxic cell death dependent on NMDA receptor activation. In animal models of the premature human infant, glutamate is also released following HI, but neurons are largely insensitive to NMDA or AMPA/kainic acid (KA) receptor-mediated damage. Using primary cultured hippocampal neurons we have determined that glutamate increases intracellular calcium much more than kainic acid. Moreover, glutamate induces cell death by activating Type I metabotropic glutamate receptors (mGluRs). Pretreatment of neurons with the gonadal steroid estradiol reduces the level of the Type I metabotropic glutamate receptors and completely prevents cell death, suggesting a novel therapeutic approach to excitotoxic brain damage in the neonate.

Effect of allopurinol supplementation on nitric oxide levels in asphyxiated newborns

This study aimed to investigate the effect of allopurinol in the management of cerebral hypoxia-ischemia by monitoring nitric oxide levels of serum and cerebrospinal fluid. Sixty asphyxiated infants were divided randomly into two groups. Group I infants (n = 30) received allopurinol (40 mg/kg/day, 3 days) within 2 hours after birth. Group II infants (n = 30) received a placebo. Twenty healthy neonates served as control subjects. Cerebrospinal fluid and serum nitric oxide levels were measured within 0-24 hours and 72-96 hours after birth. Both serum and cerebrospinal fluid concentrations of nitric oxide were higher in severely asphyxiated infants (40.86 +/- 8.97, 17.3 +/- 3.63 micromol/L, respectively) but lower in mildly asphyxiated infants (25.85 +/- 3.57, 5.70 +/- 2.56 micromol/L, respectively) than in moderately asphyxiated infants (35.86 +/- 5.38, 11.06 +/- 3.37 micromol/L, respectively) within the first 0-24 hours after birth. Serum nitric oxide levels in control subjects were lower than those of moderately and severely asphyxiated infants. Serum nitric oxide levels of Group I infants within 72-96 hours after birth decreased significantly from their corresponding levels within 0-24 hours after birth. The asphyxiated newborns treated with allopurinol had better neurologic and neurodevelopmental outcome at 12 or more months of age.

Neuroprotective effect of the peptides ADNF-9 and NAP on hypoxic-ischemic brain injury in neonatal rats

Perinatal asphyxia is an important cause of neonatal mortality and subsequent serious sequelae such as motor and cognitive deficits and seizures. Recent studies have demonstrated that short peptides derived from activity-dependent neurotrophic factor (ADNF) and activity-dependent neuroprotective protein (ADNP) are neuroprotective at femtomolar concentrations. However, the effect of these peptides on the hypoxic-ischemic brain injury model is unknown. The aim of this study is to investigate the effects of the peptides ADNF-9 and NAP on neurodegeneration and cerebral nitric oxide (NO) production in a neonatal rat model of hypoxic-ischemic brain injury. Seven-day-old Wistar Albino rat pups have been used in the study (n=42). Experimental groups in the study were: sham-operated group, ADNF-9-treated hypoxia-ischemia group, NAP-treated hypoxia-ischemia group, ADNF-9+NAP-treated hypoxia-ischemia group, and vehicle-treated group. In hypoxia-ischemia groups, left common carotid artery was ligated permanently on the seventh postnatal day. Two hours after the procedure, hypoxia (92% nitrogen and 8% oxygen) was applied for 2.5 h. ADNF-9, NAP, and ADNF-9+NAP were injected (intraperitoneally; i.p.) as a single dose immediately after the hypoxia period. Brain nitrite levels, neuronal cell death, and apoptosis were evaluated in both hemispheres (carotid ligated or nonligated) 72 h after the hypoxic-ischemic insult. Histopathological evaluation demonstrated that ADNF-9 and NAP significantly diminished number of "apoptotic cells" in the hippocampal CA1, CA2, CA3, and gyrus dentatus regions in both hemispheres (ligated and nonligated). When compared with vehicle-treated group, combination treatment with ADNF-9+NAP did not significantly reduce "apoptotic cell death" in any of the hemispheres. ADNF-9 and NAP, when administered separately, significantly preserved the number of neurons CA1, CA2, CA3, and dentate gyrus regions of the hippocampus, when compared with vehicle-treated group. The density of the CA1, CA2, and dentate gyrus neurons was significantly higher when combination therapy with ADNF-9+NAP was used in the carotid ligated hemispheres. In the nonligated hemispheres, combination therapy preserved the number of neurons only in the CA1 and dentate gyrus regions. Brain nitrite levels were evaluated by Griess reagent and showed that hypoxic-ischemic injury caused a significant increase in NO production. Brain nitrite levels in ADNF-9+NAP-treated animals were not different in carotid ligated or nonligated hemispheres. The peptides ADNF-9 and NAP significantly decreased NO overproduction in the hypoxic-ischemic hemisphere, whereas no significant change appeared in hypoxia alone and also in the sham-operated group. These results suggest the beneficial neuroprotective effect of ADNF-9 and NAP in this model of neonatal hypoxic-ischemic brain injury. To our knowledge, this is the first study that demonstrates a protective effect of these peptides against hypoxia-ischemia in the developing brain.

Plasticity of the central nervous system (CNS) following perinatal asphyxia: does nicotinamide provide neuroprotection?

We have investigated the idea that nicotinamide, a non-selective inhibitor of the sentinel enzyme Poly(ADP-ribose) polymerase-I (PARP-1), provides neuroprotection against the long-term neurological changes induced by perinatal asphyxia. Perinatal asphyxia was induced in vivo by immersing foetuses-containing uterine horns removed from ready-to-deliver rats into a water bath for 20 min. Sibling caesarean-delivered pups were used as controls. The effect of perinatal asphyxia on neurocircuitry development was studied in vitro with organotypic cultures from substantia nigra, neostriatum and neocortex, platted on a coverslip 3 days after birth. After approximately one month in vitro (DIV 25), the cultures were treated for immunocytochemistry to characterise neuronal phenotype with markers against the N-methyl-D-aspartate receptor subunit 1 (NR1), the dopamine pacemaker enzyme tyrosine hydroxylase (TH), and nitric oxide synthase (NOS), the enzyme regulating the bioavailability of NO. Nicotinamide (0.8 mmol/kg, i.p.) or saline was administered to asphyctic and caesarean-delivered pups 24, 48 and 72 h after birth. It was found that nicotinamide treatment prevented the effect of perinatal asphyxia on several neuronal parameters, including TH- and NOS-positive neurite atrophy and NOS-positive neuronal loss; supporting the idea that nicotinamide constitutes a therapeutic alternative for the effects produced by sustained energy-failure conditions, as occurring during perinatal asphyxia.

Prognostic value of 1H-MRS in neonatal encephalopathy

The aim of this study was to determine the prognostic value of proton magnetic resonance spectroscopy in neonatal encephalopathy. Studies were carried out in 11 consecutive term newborns with encephalopathy probably caused by hypoxic-ischemic injury. The clinical evaluation included pregnancy data, labor conditions, encephalopathy grade, presence of seizures, and necessity of antiepileptic drug therapy. Polygraphic recordings were obtained in all cases. Interest areas evaluated by spectroscopy were the basal ganglia and thalami. Among the cases, N-acetylaspartate/creatine, choline/creatine, and lactate/creatine ratios were calculated and related to the clinical variables, polygraphic recordings, and 6-month neurodevelopmental outcome. Abnormal follow-up occurred in 5 of 11 patients (45.4%) and was clearly related to an Apgar score <5 at 5 minutes (P = 0.003), encephalopathy grade (P = 0.02), early neonatal seizures (P = 0.02), and antiepileptic therapy (P = 0.01). No relationship was observed between spectroscopy results and polygraphic recordings profile. The lowest mean N-acetylaspartate/creatine ratio was observed in four of five patients with an adverse outcome and, although not statistically significant, demonstrated a clear trend to unfavorable follow-up (t test = 0.06). The choline/creatine ratios could not be related to follow-up in our sample. The most consistently observed abnormality on the spectra was the presence of the lactate peak in four of five patients with unfavorable outcome, with a high relative risk to determine evolution in the sample, relative risk 7.0 (chi2 = 0.01, 95% confidence interval = 1.1-42.9).

A dose-response study of graded reoxygenation on the carotid haemodynamics, matrix metalloproteinase-2 activities and amino acid concentrations in the brain of asphyxiated newborn piglets

PURPOSE

It is controversial to choose an appropriate oxygen concentration to resuscitate asphyxiated newborns regarding the clinical and biochemical oxidative effects. We examined the vasomotor response to reoxygenation with graded reoxygenation and the effects on matrix metalloproteinases and amino acids of the immature brain.

METHODS

Thirty-two piglets (1-3 days, 1.5-2.1 kg) were instrumented for continuous monitoring of left common carotid and pulmonary arterial flows (Transonic). Piglets were randomized to a sham-operated control group (without hypoxia/reoxygenation) or 2 h hypoxia induced by decreasing the inspired oxygen concentration to 10-15%, followed by reoxygenation with 21, 50 or 100% oxygen for 1 h and then 21% oxygen for 3 h (n=8 each). The brains were then flash frozen and analyzed for matrix metalloproteinases and amino acid levels by zymography and HPLC, respectively.

RESULTS

After 2 h oxygen deprivation, the absolute carotid flow remained similar but accounted for 38% of cardiac output (increased from 17% at baseline, p=0.001). During early reoxygenation, the flow rose in the piglets resuscitated with air (p<0.05), but not in those with supplemental oxygen. Carotid vascular resistance correlated significantly with the arterial partial pressure of oxygen (r=0.7). There was an oxygen-dependent increase in global cerebral activity of matrix metalloproteinase-2 with specific increases in the basal ganglia of all hypoxic-reoxygenated brains. There were no significant differences in glutamate and other amino acids in any brain regions.

CONCLUSIONS

Although using high oxygen concentration to resuscitate asphyxiated newborn piglets increased carotid vascular resistance and cerebral matrix metalloproteinase-2 activity, there is no detrimental effect observed in this acute model of hypoxia-reoxygenation.

Oxidative metabolism, apoptosis and perinatal brain injury

Perinatal hypoxic-ischaemic injury (HII) is a significant cause of neurodevelopmental impairment and disability. Studies employing 31P magnetic resonance spectroscopy to measure phosphorus metabolites in situ in the brains of newborn infants and animals have demonstrated that transient hypoxia-ischaemia leads to a delayed disruption in cerebral energy metabolism, the magnitude of which correlates with the subsequent neurodevelopmental impairment. Prominent among the biochemical features of HII is the loss of cellular ATP, resulting in increased intracellular Na+ and Ca2+, and decreased intracellular K+. These ionic imbalances, together with a breakdown in cellular defence systems following HII, can contribute to oxidative stress with a net increase in reactive oxygen species. Subsequent damage to lipids, proteins, and DNA and inactivation of key cellular enzymes leads ultimately to cell death. Although the precise mechanisms of neuronal loss are unclear, it is now clear both apoptosis and necrosis are the significant components of cell death following HII. A number of different factors influence whether a cell will undergo apoptosis or necrosis, including the stage of development, cell type, severity of mitochondrial injury and the availability of ATP for apoptotic execution. This review will focus on some pathological mechanisms of cell death in which there is a disruption to oxidative metabolism. The first sections will discuss the process of damage to oxidative metabolism, covering the data collected both from human infants and from animal models. Following sections will deal with the molecular mechanisms that may underlie cerebral energy failure and cell death in this form of brain injury, with a particular emphasis on the role of apoptosis and mitochondria.

Metabolomic and bioinformatic analyses in asphyxiated neonates

OBJECTIVES

We tested the application of bioinformatic algorithms in studying the metabolomic profiles of neonatal urine samples with clinical evidence of severe asphyxia at birth and subsequent neurodevelopmental handicap.

DESIGN AND METHODS

The clinical outcomes of 256 newborns that required direct admission to neonatal intensive care unit for respiratory support or did not require direct admission were studied. Urinary metabolite profiles were measured by high throughput mass spectrometry and analyzed by bioinformatic methods.

RESULTS

We found a positive relationship between suppressed biochemical networks involved in macromolecular synthesis and birth asphyxia associated with significant neonatal oxidative stress and morbidity. The metabolomic discriminators between good neonatal outcome and poor neonatal outcome were established using hierarchical clustering analysis. Concentrations of eight urinary organic acids in distinct biochemical pathways were elevated and significantly associated with the prognosis of neurodevelopmental handicap with high sensitivity and specificity: ethylmalonate, 3-hydroxy-3-methylglutarate, 2-hydroxy-glutarate and 2-oxo-glutarate were associated with good neonatal outcome, whereas glutarate, methylmalonate, 3-hydroxy-butyrate and orotate were associated with poor outcome.

CONCLUSIONS

The data demonstrated the potential application of bioinformatics methods in this metabolomic study and proved its clinical relevance.

Neuroprotective effects of topiramate after hypoxia-ischemia in newborn piglets

BACKGROUND

Perinatal hypoxia-ischemia (HI) is associated with delayed cerebral damage, which involves receptor-mediated excitotoxicity. Until now, successful interventions to reduce excitotoxicity early after HI in experimental settings failed to transform into clinical applications owing to negative side effects. A promising new approach using the anticonvulsant Topiramate (TPM) has shown to be effective to reduce brain damage after early HI in a rodent model of combined TPM-hypothermia. Here, we used TPM solely administered 1 h after HI in a neonatal piglet model in order to verify possible neuroprotection.

METHODS

Newborn piglets were subjected to HI by transient occlusion of carotid arteries and hypotension (62-65% of baseline). Fifteen minutes later, an additional reduction of the inspired oxygen fraction to 0.06 was performed for 13 min. One cohort (VEHICLE, n = 8) received saline solution i.v. 1 h after HI and then twice a day. Two further cohorts were treated at same times with TPM (HI-TPM10, n = 8, loading dose 20 mg/kg; maintenance dose 10 mg/kg/day; HI-TPM20, n = 8, loading dose 50 mg/kg; maintenance dose 20 mg/kg/day). Untreated animals (CONTROL, n = 8) received all experimental procedures except HI. Animals were monitored 3 days after HI concerning occurrence of seizures as well as neurological and behavioral functions. After 72 h, the brains were perfused and processed to assess neuronal loss and DNA-fragments (TUNEL staining).

RESULTS

There was a significant reduction of neuronal cell loss in HI-TPM20 animals. However, apoptosis was increased in the frontal white matter of HI-TPM20 animals.

CONCLUSIONS

Exclusive TPM treatment shows neuroprotection in newborn piglets after HI.

Prenatal hypoxia-induced adaptation and neuroprotection that is inducible nitric oxide synthase-dependent

The incidence of perinatal stroke is approximately 0.025%. About two thirds of these patients develop long-lasting neurological deficits. Preconditioning-induced neuroprotection, a phenomenon in which application of a stimulus induces brain ischemic tolerance, is investigated to improve outcome after a perinatal stroke. We applied prenatal hypoxia to fetuses by exposing 22-day pregnant mother rats to 15% oxygen for 30 min and subjected newborns with or without this prenatal hypoxia to brain ischemia 48 h later. Newborns with the prenatal hypoxia had a lower mortality rate, less brain tissue and neuronal loss and fewer active caspase 3 (an indicator for cell apoptosis) positive brain cells than newborns with the brain ischemia only. This neuroprotection was abolished by an inhibitor of inducible nitric oxide synthase (iNOS). The expression of iNOS proteins but not endothelial and neuronal NOS proteins was increased by the prenatal hypoxia. Thus, the prenatal hypoxia-induced neuroprotection may be iNOS-dependent.

Mitochondrial impairment in the developing brain after hypoxia-ischemia

The pattern of cell death in the immature brain differs from that seen in the adult CNS. During normal development, more than half of the neurons are removed through apoptosis, and mediators like caspase-3 are highly upregulated. The contribution of apoptotic mechanisms in cell death appears also to be substantial in the developing brain, with a marked activation of downstream caspases and signs of DNA fragmentation. Mitochondria are important regulators of cell death through their role in energy metabolism and calcium homeostasis, and their ability to release apoptogenic proteins and to produce reactive oxygen species. We find that secondary brain injury is preceded by impairment of mitochondrial respiration, signs of membrane permeability transition, intramitochondrial accumulation of calcium, changes in the Bcl-2 family proteins, release of proapoptotic proteins (cytochrome C, apoptosis inducing factor) and downstream activation of caspase-9 and caspase-3 after hypoxia-ischemia. These data support the involvement of mitochondria-related mechanisms in perinatal brain injury.

Effect of perinatal asphyxia on tyrosine hydroxylase and D2 and D1 dopamine receptor mRNA levels expressed during early postnatal development in rat brain

This study was designed to investigate the postnatal developmental plasticity of the mesostriatal and mesolimbic dopamine systems that occurs following perinatal asphyxia. The time course and patterning of the changes in levels of tyrosine hydroxylase (TH), and D1 and D2 dopamine receptor (R) mRNA in the cell body region, substantia nigra and ventral tegmental area (SN/VTA), and projection fields, striatum and limbic regions at the age of 6 and 24 h, and 1 week after asphyxia were studied with a quantitative reverse transcription polymerase chain reaction method with appropriate internal cRNA standard. In Caesarean-delivered control rats (Sprague-Dawley), TH, D2R and D1R mRNA levels showed regional and temporal specificity in both absolute levels and developmental kinetics during the first week of life. TH mRNA levels were >10-fold higher in SN/VTA than in striatum and limbic regions. Compared to Caesarean delivered controls, severe asphyxia (15-20 min) induced an increase of TH and D2R mRNA in SN/VTA 6 h and 1 week after birth. In addition, asphyxia induced an increase of TH mRNA in the projection fields, striatum and limbic regions, at 1 week. Perinatal asphyxia did not appear to exert any effect on D1R mRNA levels. No differences in any of the parameters were observed between spontaneous- and Caesarean-delivered animals. The present results indicate that perinatal asphyxia triggers coordinated changes in the expression of TH, and dopamine receptor mRNA in SN/VTA, striatum and limbic regions. These changes may affect differently dopamine D2R and D1R expression along development, contributing to long-term neurocircuitry imbalances.