Neuroprotection in the newborn infant

Evaluating the healing effects of docosahexaenoic acid in neonates with bilirubin-induced brain injury

BACKGROUND

Neonatal brain injury due to bilirubin toxicity presents critical need for effective healing treatments. Docosahexaenoic acid (DHA), having neuroprotective properties, offers potential therapeutic benefits in promoting brain repair and recovery.

OBJECTIVES

This study focused on evaluating the healing capabilities of DHA in neonatal brains damaged by bilirubin-induced injury, with particular attention to its role in enhancing brain tissue repair mechanisms.

METHODS

Employing the bilirubin encephalopathy model in neonatal Sprague-Dawley rats and neuronal cell cultures, we investigated the therapeutic impact of DHA.

RESULTS

The study measured improvements in brain tissue integrity, assessed bilirubin levels, analyzed gene and protein expressions pertinent to the brain's recovery process. DHA administration resulted in significant repair in neonatal brains, evidenced by reduction in bilirubin levels and restoration of normal brain tissue architecture.

CONCLUSION

Molecular analysis indicated the distinct modulation of the CTBP1/miR-155-5p/KDM5A pathway, critical for cellular repair processes and marked decrease in markers of cellular damage and stress.

Neuroprotection for neonatal hypoxic-ischemic encephalopathy: A review of novel therapies evaluated in clinical studies

Therapeutic hypothermia is an effective therapy for moderate-to-severe hypoxic-ischemic encephalopathy (HIE) in infants born at term or near-term in high-resource settings. Yet there remains a substantial proportion of infants who do not benefit or who will have significant disability despite therapeutic hypothermia. Novel investigational therapies that may confer additional neuroprotection by targeting known pathogenic mechanisms of hypoxic-ischemic brain injury are under development. This review focuses on putative neuroprotective agents that have shown promise in animal models of HIE, and that have been translated to clinical studies in neonates with HIE. We include agents that have been studied both with and without concurrent therapeutic hypothermia. Our review therefore addresses not just neonatal HIE in high-resource countries where therapeutic hypothermia is the standard of care, but also neonatal HIE in low- and middle-income countries where therapeutic hypothermia has been shown to be ineffective, and where the greatest burden of HIE-related morbidity and mortality exists.

Kinetics of Circulating Progenitor Cells and Chemotactic Factors in Full-Term Neonates with Encephalopathy: Indications of Participation in the Endogenous Regenerative Process

Preclinical studies have shown that progenitor cells (PCs) are mobilized toward injured tissues to ameliorate damage and contribute to regeneration. The exogenous therapeutic administration of PCs in children affected by neonatal encephalopathy (NE) is a promising, yet underreported, topic. In this prospective study, we investigated whether endogenous circulating progenitor cells (CPCs) are involved in intrinsic regeneration mechanisms following neonatal brain injury. Thirteen full-term infants with moderate/severe NE, eleven with perinatal stress, and twelve controls were enrolled. Blood samples were collected on days 1, 3, 9, 18, and 45, as well as at 8 and 24 months of life, and were analyzed with a focus on Endothelial Progenitor Cells, Haematopoietic Stem Cells, and Very Small Embryonic-Like Stem Cells, in addition to chemotactic factors (erythropoietin, IGF-1, and SDF-1). Correlations between CPCs, chemotactic factors, and brain injury were assessed using serum levels of brain injury biomarkers (S100B and neuron-specific enolase), brain MRIs, and Bayley III developmental scores. Increased brain injury biomarkers were followed by the upregulation of SDF-1 receptor and erythropoietin and, finally, by elevated CPCs. These findings suggest a potential endogenous regenerative effort, primarily observed in the moderate encephalopathy group, but this is suppressed in cases of severe brain injury. Mimicking and enhancing endogenous regeneration pathways in cases of failure-regarding cell type and timeframe-could provide a novel therapeutic model.

Perinatal asphyxia and hypothermic treatment from the endocrine perspective

Introduction

Perinatal asphyxia is one of the three most important causes of neonatal mortality and morbidity. Therapeutic hypothermia represents the standard treatment for infants with moderate-severe perinatal asphyxia, resulting in reduction in the mortality and major neurodevelopmental disability. So far, data in the literature focusing on the endocrine aspects of both asphyxia and hypothermia treatment at birth are scanty, and many aspects are still debated. Aim of this narrative review is to summarize the current knowledge regarding the short- and long-term effects of perinatal asphyxia and of hypothermia treatment on the endocrine system, thus providing suggestions for improving the management of asphyxiated children.

Results

Involvement of the endocrine system (especially glucose and electrolyte disturbances, adrenal hemorrhage, non-thyroidal illness syndrome) can occur in a variable percentage of subjects with perinatal asphyxia, potentially affecting mortality as well as neurological outcome. Hypothermia may also affect endocrine homeostasis, leading to a decreased incidence of hypocalcemia and an increased risk of dilutional hyponatremia and hypercalcemia.

Conclusions

Metabolic abnormalities in the context of perinatal asphyxia are important modifiable factors that may be associated with a worse outcome. Therefore, clinicians should be aware of the possible occurrence of endocrine complication, in order to establish appropriate screening protocols and allow timely treatment.

Beyond brain injury biomarkers: chemoattractants and circulating progenitor cells as biomarkers of endogenous rehabilitation effort in preterm neonates with encephalopathy

Introduction

Preclinical work and studies in adults have shown that endogenous regeneration efforts that involve mobilization of progenitor cells take place after brain injury. However, kinetics of endogenous circulating progenitor cells (CPCs) in preterm neonates is not well described, particularly their possible role regarding brain injury and regeneration. We aimed to assess the kinetics of CPCs in neonates with encephalopathy of prematurity in relation to brain injury biomarkers, chemoattractants and relevant antenatal and postanal clinical factors, in an effort to outline the related pathophysiology.

Materials and methods

47 preterm neonates (of 28-33 weeks GA) were enrolled: 31 newborns with no or minimal brain injury (grade I IVH) and 16 prematures with encephalopathy (grade III or IV IVH, PVL or infarct). Peripheral blood samples obtained on days 1, 3, 9, 18 and 45 after birth were analyzed using flow cytometry, focusing on EPCs (early and late Endothelial Progenitor Cells), HSCs (Hematopoietic Stem Cells) and VSELs (Very Small Embryonic-Like Stem Cells). At the same time-points serum levels of S100B, Neuron-specific Enolase (NSE), Erythropoietin (EPO), Insulin-like growth factor-1 (IGF-1) and SDF-1 were also measured. Neonates were assessed postnatally with brain MRI, and with Bayley III developmental test at 2 years of corrected age.

Results

Preterms with brain injury proved to have significant increase of S100B and NSE, followed by increase of EPO and enhanced mobilization mainly of HSCs, eEPCs and lEPCs. IGF-1 was rather decreased in this group of neonates. IGF-1 and most CPCs were intense decreased in cases of antenatal or postnatal inflammation. S100B and NSE correlated with neuroimaging and language scale in Bayley III test, providing good prognostic ability.

Conclusion

The observed pattern of CPCs' mobilization and its association with neurotrophic factors following preterm brain injury indicate the existence of an endogenous brain regeneration process. Kinetics of different biomarkers and associations with clinical factors contribute to the understanding of the related pathophysiology and might help to early discriminate neonates with adverse outcome. Timely appropriate enhancement of the endogenous regeneration effort, when it is suppressed and insufficient, using neurotrophic factors and exogenous progenitor cells might be a powerful therapeutic strategy in the future to restore brain damage and improve the neurodevelopmental outcome in premature infants with brain injury.

Transcranial photoacoustic characterization of neurovascular physiology during early-stage photothrombotic stroke in neonatal pigletsin vivo

OBJECTIVE

Perinatal ischemic stroke is estimated to occur in 1/2300-1/5000 live births, but early differential diagnosis from global hypoxia-ischemia is often difficult. In this study, we tested the ability of a hand-held transcranial photoacoustic (PA) imaging probe to non-invasively detect a focal photothrombotic stroke (PTS) within 2 h of stroke onset in a gyrencephalic piglet brain.

APPROACH

About 17 stroke lesions of approximately 1 cm²area were introduced randomly in anterior or posterior cortex via the light/dye PTS technique in anesthetized neonatal piglets (n= 11). The contralateral non-ischemic region served as control tissue for discrimination contrast for the PA hemoglobin metrics: oxygen saturation, total hemoglobin (tHb), and individual quantities of oxygenated and deoxygenated hemoglobin (HbO₂and HbR).

MAIN RESULTS

The PA-derived tissue oxygen saturation at 2 h yielded a significant separation between control and affected regions-of-interest (p< 0.0001), which were well matched with 24 h post-stroke cerebral infarction confirmed in the triphenyltetrazolium chloride-stained image. The quantity of HbO₂also displayed a significant contrast (p= 0.021), whereas tHb and HbR did not. The analysis on receiver operating characteristic curves and multivariate data analysis also agreed with the results above.

SIGNIFICANCE

This study shows that a hand-held transcranial PA neuroimaging device can detect a regional thrombotic stroke in the cerebral cortex of a neonatal piglet. In particular, we conclude that the oxygen saturation metric can be used alone to identify regional stroke lesions. The lack of change in tHb may be related to arbitrary hand-held imaging configuration and/or entrapment of red blood cells within the thrombotic stroke.

Early Biomarkers of Hypoxia and Inflammation and Two-Year Neurodevelopmental Outcomes in the Preterm Erythropoietin Neuroprotection (PENUT) Trial

BACKGROUND

In the Preterm Erythropoietin (Epo) NeUroproTection (PENUT) Trial, potential biomarkers of neurological injury were measured to determine their association with outcomes at two years of age and whether Epo treatment decreased markers of inflammation in extremely preterm (<28 weeks' gestation) infants.

METHODS

Plasma Epo was measured (n=391 Epo, n=384 placebo) within 24h after birth (baseline), 30min after study drug administration (day 7), 30min before study drug (day 9), and on day 14. A subset of infants (n=113 Epo, n=107 placebo) had interferon-gamma (IFN-γ), Interleukin (IL)-6, IL-8, IL-10, Tau, and tumour necrosis factor-α (TNF-α) levels evaluated at baseline, day 7 and 14. Infants were then evaluated at 2 years using the Bayley Scales of Infant and Toddler Development, 3rd Edition (BSID-III).

FINDINGS

Elevated baseline Epo was associated with increased risk of death or severe disability (BSID-III Motor and Cognitive subscales <70 or severe cerebral palsy). No difference in other biomarkers were seen between treatment groups at any time, though Epo appeared to mitigate the association between elevated baseline IL-6 and lower BSID-III scores in survivors. Elevated baseline, day 7 and 14 Tau concentrations were associated with worse BSID-III Cognitive, Motor, and Language skills at two years.

INTERPRETATION

Elevated Epo at baseline and elevated Tau in the first two weeks after birth predict poor outcomes in infants born extremely preterm. However, no clear prognostic cut-off values are apparent, and further work is required before these biomarkers can be widely implemented in clinical practice.

FUNDING

PENUT was funded by the National Institute of Neurological Disorders and Stroke (U01NS077955 and U01NS077953).

Dexmedetomidine and Phosphocreatine Post-treatment Provides Protection against Focal Cerebral Ischemia-reperfusion Injury in Rats

In this study we investigated the neuroprotective efficacy of dexmedetomidine (Dex) and phosphocreatine (PCr) alone or in combination in a rat model of focal cerebral ischemia-reperfusion injury (I/R). I/R was induced by intraluminal middle cerebral artery occlusion (MCAO) and reperfusion. Male Sprague-Dawley rats were randomly allocated to the Sham group and I/R group, and the I/R group was further divided into three subgroups: Dex (9 μg.kg⁻¹ Dex), PCr (180 mg.kg⁻¹ PCr) and Dex + PCr (9 μg.kg⁻¹ Dex + 180 mg.kg⁻¹ PCr). All treatments were given intravenously at the onset of reperfusion. After 24 hr of reperfusion, the neurological deficit score (NDS) was determined and a magnetic resonance imaging (MRI) scan was performed. Serum concentrations of malonaldehyde (MDA) and 4-hydroxynonenal (4-HNE) were measured and cerebral infarct volume was estimated by triphenyl tetrazolium chloride (TTC) staining. Blood brain barrier, neuronal and mitochondrial damage was assessed by optical and electron microscopy. Neuronal injury was further assessed using double cleaved caspase-3 and NeuN immunofluorescent staining. Compared with group I/R, Dex and PCr significantly reduced the neurological deficit score (P < 0.01), infarct volume (P < 0.01), and brain blood barrier, neuronal and mitochondrial damage. The level of oxidative stress (P < 0.001) and neuronal injury (P < 0.001) also decreased and surviving neurons increased (P < 0.001). Compared with Dex or PCr alone, the combination treatment had overall greater effects (P < 0.05). These results indicate that posttreatment with Dex or PCr decreases focal cerebral I/R injury and that these agents in combination have greater protective effects than each alone.

Formulation and Efficacy of Catalase-Loaded Nanoparticles for the Treatment of Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal hypoxic-ischemic encephalopathy is the leading cause of permanent brain injury in term newborns and currently has no cure. Catalase, an antioxidant enzyme, is a promising therapeutic due to its ability to scavenge toxic reactive oxygen species and improve tissue oxygen status. However, upon in vivo administration, catalase is subject to a short half-life, rapid proteolytic degradation, immunogenicity, and an inability to penetrate the brain. Polymeric nanoparticles can improve pharmacokinetic properties of therapeutic cargo, although encapsulation of large proteins has been challenging. In this paper, we investigated hydrophobic ion pairing as a technique for increasing the hydrophobicity of catalase and driving its subsequent loading into a poly(lactic-co-glycolic acid)-poly(ethylene glycol) (PLGA-PEG) nanoparticle. We found improved formation of catalase-hydrophobic ion complexes with dextran sulfate (DS) compared to sodium dodecyl sulfate (SDS) or taurocholic acid (TA). Molecular dynamics simulations in a model system demonstrated retention of native protein structure after complexation with DS, but not SDS or TA. Using DS-catalase complexes, we developed catalase-loaded PLGA-PEG nanoparticles and evaluated their efficacy in the Vannucci model of unilateral hypoxic-ischemic brain injury in postnatal day 10 rats. Catalase-loaded nanoparticles retained enzymatic activity for at least 24 h in serum-like conditions, distributed through injured brain tissue, and delivered a significant neuroprotective effect compared to saline and blank nanoparticle controls. These results encourage further investigation of catalase and PLGA-PEG nanoparticle-mediated drug delivery for the treatment of neonatal brain injury.

Precision Medicine in Neonates: A Tailored Approach to Neonatal Brain Injury

Despite advances in neonatal care to prevent neonatal brain injury and neurodevelopmental impairment, predicting long-term outcome in neonates at risk for brain injury remains difficult. Early prognosis is currently based on cranial ultrasound (CUS), MRI, EEG, NIRS, and/or general movements assessed at specific ages, and predicting outcome in an individual (precision medicine) is not yet possible. New algorithms based on large databases and machine learning applied to clinical, neuromonitoring, and neuroimaging data and genetic analysis and assays measuring multiple biomarkers (omics) can fulfill the needs of modern neonatology. A synergy of all these techniques and the use of automatic quantitative analysis might give clinicians the possibility to provide patient-targeted decision-making for individualized diagnosis, therapy, and outcome prediction. This review will first focus on common neonatal neurological diseases, associated risk factors, and most common treatments. After that, we will discuss how precision medicine and machine learning (ML) approaches could change the future of prediction and prognosis in this field.

Endogenous erythropoietin signaling regulates migration and laminar positioning of upper-layer neurons in the developing neocortex

Erythropoietin (EPO), the hypoxia-inducible hematopoietic hormone, has well-established neuroprotective/neurotrophic roles in the developing central nervous system and the therapeutic potential of EPO has been widely explored in clinical studies for the treatment of perinatal hypoxic brain lesion, as well as prematurity. Here, we reveal that both EPO and Epo receptor (EPOR) are expressed in the developing rat somatosensory cortex during radial migration and laminar positioning of granular and supragranular neurons. Experimental deregulation of EPO signaling using genetic approaches results in aberrant migration, as well as permanent neuronal misplacement leading to abnormal network activity and protracted sensory behavioral deficits. We identify ERK as the downstream effector of the EPO signaling pathway for neuronal migration. These findings reveal a crucial role for endogenous EPO signaling in neuronal migration, and offer important insights for understanding how the temporary deregulation of EPO could result in migration defects that lead to abnormal behavior in the adult.

Hypoxia-inducible factor: role in cell survival in superoxide dismutase overexpressing mice after neonatal hypoxia-ischemia

Background

Sixty percent of infants with severe neonatal hypoxic-ischemic encephalopathy die, while most survivors have permanent disabilities. Treatment for neonatal hypoxic-ischemic encephalopathy is limited to therapeutic hypothermia, but it does not offer complete protection. Here, we investigated whether hypoxia-inducible factor (HIF) promotes cell survival and suggested neuroprotective strategies.

Purpose

HIF-1α deficient mice have increased brain injury after neonatal hypoxia-ischemia (HI), and the role of HIF-2α in HI is not well characterized. Copper-zinc superoxide dismutase (SOD)1 overexpression is not beneficial in neonatal HI. The expression of HIF-1α and HIF-2α was measured in SOD1 overexpressing mice and compared to wild-type littermates to see if alteration in expression explains this lack of benefit.

Methods

On postnatal day 9, C57Bl/6 mice were subjected to HI, and protein expression was measured by western blotting in the ipsilateral cortex of wild-type and SOD1 overexpressing mice to quantify HIF-1α and HIF-2α. Spectrin expression was also measured to characterize the mechanism of cell death.

Results

HIF-1α protein expression did not significantly change after HI injury in the SOD1 overexpressing or wild-type mouse cortex. However, HIF-2α protein expression increased 30 minutes after HI injury in the wild-type and SOD1 overexpressing mouse cortex and decreased to baseline value at 24 hours after HI injury. Spectrin 145/150 expression did not significantly change after HI injury in the SOD1 overexpressing or wild-type mouse cortex. However, spectrin 120 expression increased in both wild-type and SOD1 overexpressing mouse at 4 hours after HI, which decreased by 24 hours, indicating a greater role of apoptotic cell death.

Conclusion

HIF-1α and HIF-2α may promote cell survival in neonatal HI in a cell-specific and regional fashion. Our findings suggest that early HIF-2α upregulation precedes apoptotic cell death and limits necrotic cell death. However, the influence of SOD was not clarified; it remains an intriguing factor in neonatal HI.

Short-, Mid-, and Long-Term Effect of Granulocyte Colony-Stimulating Factor/Stem Cell Factor and Fms-Related Tyrosine Kinase 3 Ligand Evaluated in an In Vivo Model of Hypoxic-Hyperoxic Ischemic Neonatal Brain Injury

Hematopoietic growth factors are considered to bear neuroprotective potential. We have previously shown that delayed treatment with granulocyte colony-stimulating factor (G-CSF)/stem cell factor (SCF) and Fms-related tyrosine kinase 3 ligand (FL) ameliorates excitotoxic neonatal brain injury. The effect of these substances in combined-stressor neonatal brain injury models more closely mimicking clinical conditions has not been investigated. The aim of this study was to assess the short-, mid-, and long-term neuroprotective potential of G-CSF/SCF and FL in a neonatal model of hypoxic-hyperoxic ischemic brain injury. Five-day-old (P5) CD-1 mice were subjected to unilateral common carotid artery ligation and subsequent alternating periods of hypoxia and hyperoxia for 65 minutes. Sixty hours after injury, pups were randomly assigned to intraperitoneal treatment with (i) G-CSF (200 μg/kg)/SCF (50 μg/kg), (ii) FL (100 μg/kg), or (iii) vehicle every 24 hours for three or five consecutive days. Histopathological and functional outcomes were evaluated on P10, P18, and P90. Baseline outcome parameters were established in sham-treated and healthy control animals. Gross brain injury did not significantly differ between treatment groups at any time point. On P10, caspase-3 activation and caspase-independent apoptosis were similar between treatment groups; cell proliferation and the number of BrdU-positive vessels did not differ on P18 or P90. Neurobehavioral assessment did not reveal significant differences between treatment groups in accelerod performance, open field behavior, or novel object recognition capacity on P90. Turning behavior was more frequently observed in G-CSF/SCF- and FL-treated animals. No sex-specific differences were detected in any outcome parameter evaluated. In hypoxic-hyperoxic ischemic neonatal brain injury, G-CSF/SCF and FL treatment does not convey neuroprotection. Prior to potential clinical use, meticulous assessment of these hematopoietic growth factors is mandated.

Astrocyte-produced carbon monoxide and the carbon monoxide donor CORM-A1 protect against cerebrovascular dysfunction caused by prolonged neonatal asphyxia

Neonatal asphyxia leads to cerebrovascular disease and neurological complications via a mechanism that may involve oxidative stress. Carbon monoxide (CO) is an antioxidant messenger produced via a heme oxygenase (HO)-catalyzed reaction. Cortical astrocytes are the major cells in the brain that express constitutive HO-2 isoform. We tested the hypothesis that CO, produced by astrocytes, has cerebroprotective properties during neonatal asphyxia. We developed a survival model of prolonged asphyxia in newborn pigs that combines insults of severe hypoxia, hypercapnia, and acidosis while avoiding extreme hypotension and cerebral blood flow reduction. During the 60-min asphyxia, CO production by brain and astrocytes was continuously elevated. Excessive formation of reactive oxygen species during asphyxia/reventilation was potentiated by the HO inhibitor tin protoporphyrin, suggesting that endogenous CO has antioxidant effects. Cerebral vascular outcomes tested 24 and 48 h after asphyxia demonstrated the sustained impairment of cerebral vascular responses to astrocyte- and endothelium-specific vasodilators. Postasphyxia cerebral vascular dysfunction was aggravated in newborn pigs pretreated with tin protoporphyrin to inhibit brain HO/CO. The CO donor CO-releasing molecule-A1 (CORM-A1) reduced brain oxidative stress during asphyxia/reventilation and prevented postasphyxia cerebrovascular dysfunction. The antioxidant and antiapoptotic effects of HO/CO and CORM-A1 were confirmed in primary cultures of astrocytes from the neonatal pig brain exposed to glutamate excitotoxicity. Overall, prolonged neonatal asphyxia leads to neurovascular injury via an oxidative stress-mediated mechanism that is counteracted by an astrocyte-based constitutive antioxidant HO/CO system. We propose that gaseous CO or CO donors can be used as novel approaches for prevention of neonatal brain injury caused by prolonged asphyxia. NEW & NOTEWORTHY Asphyxia in newborn infants may lead to lifelong neurological disabilities. Using the model of prolonged asphyxia in newborn piglets, we propose novel antioxidant therapy based on systemic administration of low doses of a carbon monoxide donor that prevent loss of cerebral blood flow regulation and may improve the neurological outcome of asphyxia.

Functional up-regulation of the M-current by retigabine contrasts hyperexcitability and excitotoxicity on rat hypoglossal motoneurons

KEY POINTS

Excessive neuronal excitability characterizes several neuropathological conditions, including neurodegenerative diseases such as amyotrophic lateral sclerosis. Hypoglossal motoneurons (HMs), which control tongue muscles, are extremely vulnerable to this disease and undergo damage and death when exposed to an excessive glutamate extracellular concentration that causes excitotoxicity. Our laboratory devised an in vitro model of excitotoxicity obtained by pharmacological blockade of glutamate transporters. In this paradigm, HMs display hyperexcitability, collective bursting and eventually cell death. The results of the present study show that pharmacological up-regulation of a K⁺ current (M-current), via application of the anti-convulsant retigabine, prevented all hallmarks of HM excitotoxicity, comprising bursting, generation of reactive oxygen species, expression of toxic markers and cell death. ○Our data may have translational value to develop new treatments against neurological diseases by using positive pharmacological modulators of the M-current.

ABSTRACT

Neuronal hyperexcitability is a symptom characterizing several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). In the ALS bulbar form, hypoglossal motoneurons (HMs) are an early target for neurodegeneration because of their high vulnerability to metabolic insults. In recent years, our laboratory has developed an in vitro model of a brainstem slice comprising the hypoglossal nucleus in which HM neurodegeneration is achieved by blocking glutamate clearance with dl-threo-β-benzyloxyaspartate (TBOA), thus leading to delayed excitotoxicity. During this process, HMs display a set of hallmarks such as hyperexcitability (and network bursting), reactive oxygen species (ROS) generation and, finally, cell death. The present study aimed to investigate whether blocking early hyperexcitability and bursting with the anti-convulsant drug retigabine was sufficient to achieve neuroprotection against excitotoxicity. Retigabine is a selective positive allosteric modulator of the M-current (I_M ), an endogenous mechanism that neurons (comprising HMs) express to dampen excitability. Retigabine (10 μm; co-applied with TBOA) contrasted ROS generation, release of endogenous toxic factors into the HM cytoplasm and excitotoxicity-induced HM death. Electrophysiological experiments showed that retigabine readily contrasted and arrested bursting evoked by TBOA administration. Because neuronal I_M subunits (Kv7.2, Kv7.3 and Kv7.5) were expressed in the hypoglossal nucleus and in functionally connected medullary nuclei, we suggest that they were responsible for the strong reduction in network excitability, a potent phenomenon for achieving neuroprotection against TBOA-induced excitotoxicity. The results of the present study may have translational value for testing novel positive pharmacological modulators of the I_M under pathological conditions (including neurodegenerative disorders) characterized by excessive neuronal excitability.

Protein S100B in umbilical cord blood as a potential biomarker of hypoxic-ischemic encephalopathy in asphyxiated newborns

BACKGROUND

Neonatal hypoxic ischemic encephalopathy (HIE) is a devastating condition resulting from a sustained lack of oxygen during birth. The interest in identifying a relevant biomarker of HIE has thrown into limelight the role of protein S100B as a clinical diagnostic marker of hypoxic brain damage in neonates.

AIMS

To evaluate the diagnostic value of protein S100B, measured in umbilical cord blood immediately after birth, as a useful biomarker in the diagnosis of HIE Sarnat stages II-III as well as a marker for long-term mortality and morbidity.

STUDY DESIGN

Protein S100B was analyzed in cord blood sampled at birth from 13 newborns later diagnosed with stage II-III HIE and compared with 21 healthy controls. S100B concentrations were related to cord artery pH, amplitude-integrated electroencephalography (aEEG), stage of HIE, and death/sequelae up to an age of 6years. Both parametric and non-parametric statistics were used with a two-sided P<0.05 considered significant.

RESULTS

The difference in S100B concentration was marginally statistically significant between HIE cases and controls (P=0.056). Cord blood acidosis (P=0.046), aEEG pattern severity (P=0.030), HIE severity (P=0.027), and condition at 6-year follow-up (healthy/permanent sequelae/death; P=0.027) were all related to an increase in S100B concentration.

CONCLUSIONS

Protein S100B in neonates suffering from HIE stages II-III appeared elevated in umbilical cord blood at birth. The S100B concentrations were positively associated to the severity of disease and the risk of suffering from neurodevelopmental sequelae and even death.

Therapeutic Hypothermia Provides Variable Protection against Behavioral Deficits after Neonatal Hypoxia-Ischemia: A Potential Role for Brain-Derived Neurotrophic Factor

BACKGROUND

Despite treatment with therapeutic hypothermia (TH), infants who survive hypoxic ischemic (HI) encephalopathy (HIE) have persistent neurological abnormalities at school age. Protection by TH against HI brain injury is variable in both humans and animal models. Our current preclinical model of hypoxia-ischemia (HI) and TH displays this variability of outcomes in neuropathological and neuroimaging end points with some sexual dimorphism. The detailed behavioral phenotype of this model is unknown. Whether there is sexual dimorphism in certain behavioral domains is also not known. Brain-derived neurotrophic factor (BDNF) supports neuronal cell survival and repair but may also be a marker of injury. Here, we characterize the behavioral deficits after HI and TH stratified by sex, as well as late changes in BDNF and its correlation with memory impairment.

METHODS

HI was induced in C57BL6 mice on postnatal day 10 (p10) (modified Vannucci model). Mice were randomized to TH (31°C) or normothermia (NT, 36°C) for 4 h after HI. Controls were anesthesia-exposed, age- and sex-matched littermates. Between p16 and p39, growth was followed, and behavioral testing was performed including reflexes (air righting, forelimb grasp and negative geotaxis) and sensorimotor, learning, and memory skills (open field, balance beam, adhesive removal, Y-maze tests, and object location task [OLT]). Correlations between mature BDNF levels in the forebrain and p42 memory outcomes were studied.

RESULTS

Both male and female HI mice had an approximately 8-12% lower growth rate (g/day) than shams (p ≤ 0.01) by p39. TH ameliorated this growth failure in females but not in males. In female mice, HI injury prolonged the time spent at the periphery (open field) at p36 (p = 0.004), regardless of treatment. TH prevented motor impairments in the balance beam and adhesive removal tests in male and female mice, respectively (p ≤ 0.05). Male and female HI mice visited the new arm of the Y-maze 12.5% (p = 0.05) and 10% (p = 0.03) less often than shams, respectively. Male HI mice also had 35% lower exploratory preference score than sham (p ≤ 0.001) in the OLT. TH did not prevent memory impairments found with Y-maze testing or OLT in either sex (p ≤ 0.01) at p26. At p42, BDNF levels in the forebrain ipsilateral to the HI insult were 1.7- to 2-fold higher than BDNF levels in the sham forebrain, and TH did not prevent this increase. Higher BDNF levels in the forebrain ipsilateral to the insult correlated with worse performance in the Y-maze in both sexes and in OLT in male mice (p = 0.01).

CONCLUSIONS

TH provides benefit in specific domains of behavior following neonatal HI. In general, these benefits accrued to both males and females, but not in all areas. In some domains, such as memory, no benefit of TH was found. Late differences in individual BDNF levels may explain some of these findings.

Selective head cooling during neonatal seizures prevents postictal cerebral vascular dysfunction without reducing epileptiform activity

Epileptic seizures in neonates cause cerebrovascular injury and impairment of cerebral blood flow (CBF) regulation. In the bicuculline model of seizures in newborn pigs, we tested the hypothesis that selective head cooling prevents deleterious effects of seizures on cerebral vascular functions. Preventive or therapeutic ictal head cooling was achieved by placing two head ice packs during the preictal and/or ictal states, respectively, for the ∼2-h period of seizures. Head cooling lowered the brain and core temperatures to 25.6 ± 0.3 and 33.5 ± 0.1°C, respectively. Head cooling had no anticonvulsant effects, as it did not affect the bicuculline-evoked electroencephalogram parameters, including amplitude, duration, spectral power, and spike frequency distribution. Acute and long-term cerebral vascular effects of seizures in the normothermic and head-cooled groups were tested during the immediate (2-4 h) and delayed (48 h) postictal periods. Seizure-induced cerebral vascular injury during the immediate postictal period was detected as terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive staining of cerebral arterioles and a surge of brain-derived circulating endothelial cells in peripheral blood in the normothermic group, but not in the head-cooled groups. During the delayed postictal period, endothelium-dependent cerebral vasodilator responses were greatly reduced in the normothermic group, indicating impaired CBF regulation. Preventive or therapeutic ictal head cooling mitigated the endothelial injury and greatly reduced loss of postictal cerebral vasodilator functions. Overall, head cooling during seizures is a clinically relevant approach to protecting the neonatal brain by preventing cerebrovascular injury and the loss of the endothelium-dependent control of CBF without reducing epileptiform activity.

Trophic factors intervention regenerates the nestin-expressing cell population in a model of perinatal excitotoxicity: Implications for perinatal brain injury and prematurity

We previously showed that TSC1 (a combination of transferrin and IGF-1) is a potent inductor of myelinogenesis in myelin deficient rats and in demyelinated adult mice. More recently, we demonstrated that regeneration of oligodendrocyte progenitors and myelin are possible with a single dose of TSC1 in a mouse model of Premature birth. Here, using the same mouse model of perinatal white matter damage due to glutamate excitotoxicity (GME), we tested the hypothesis that regeneration of endogenous nestin-expressing neural progenitors improves the outcome of prematurity. Treatments: N-methyl-D-aspartate (NMDA), saline, NMDA+TSC1 together or NMDA followed byTSC1 3 days later, were stereotaxically delivered into the corpus callosum of P4 mouse pups. Fluorescence analysis showed an intense enrichment of nestin-expressing cells in groups injected with NMDA+TSC1 from which many were generated by proliferation. Moreover, when TSC1 was injected three days after the primary insult it was still able to reduce ventricular enlargement and extensively rescue nestin-expressing progenitors. Cells co-expressing the proliferation marker Ki67, CNPase and faint nestin label were more abundant in groups injected with MNDA+TSC1 at 35 days after injection. Stereological analysis showed that the number of nestin-expressing cells in the sub-ventricular zone correlated inversely with the volume of the ventricle. A delayed administration of TSC1 after excitotoxicity reduced ventriculomegaly but not as much as, when NMDA and TSC1 were injected simultaneously. Thus, the earliest TSC1 was administered, the more tissue was rescued as shown by reduced ventriculomegaly. Astrocytes responded to GME by upregulating the expression of estrogen receptor and this expression was attenuated in the presence of TSC1 suggesting a decreased inflammation and a lesser need for estrogen-mediated central nervous system (CNS) neuroprotection.

A meta-analysis of the protective effect of recombinant human erythropoietin (rhEPO) for neurodevelopment in preterm infants

The purpose of this study is to assess the efficacy and safety of recombinant human erythropoietin (rhEPO) for improving neurodevelopment outcomes in preterm infants. According to the requirements of Cochrane systematic review, a literature search was performed among PubMed, EMBASE, Cochrane Central Register of Controlled Trials, Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, Wan Fang Data, and VIP INFORMATION from the establishment of the database from January 1999 to December 2011. Quality assessments of clinical trials were carried out. Randomized controlled trials (RCTs) or quasi-RCTs with rhEPO in preterm infants were enrolled, and RevMan5.0 software was used for meta-analysis. Data extraction, quality assessment, and meta-analysis for the results of homogeneous studies were done by two reviewers. The trials were analyzed using weighted mean difference (WMD) for continuous data and odds ratio (OR) for dichotomous data, both kinds of data were expressed by 95 % CI. For homogenous data (P ≥ 0.10), fixed effect model was calculated. Two RCTs and 3 quasi-RCTs including 233 preterm infants (119 of treatment group and 114 of control group) were included in the analysis. The results of quality assessment were that 1 study was A, 1 was B, and 3 were C. There was evidence of a significant effect of therapeutic rhEPO on the outcomes of MDI scores [WMD = 7.77, 95 % CI (3.49-12.06), P = 0.0004], PDI scores [WMD = 3.85, 95 % CI (0.62-7.09), P = 0.02] at 18-22 months and NBNA scores [WMD = 1.96, 95 % CI (1.56-2.37), P < 0.00001] at 40 weeks of corrected gestational age. However, rhEPO had no effect on MDI <70 (OR = 0.70, 95 % CI 0.31-1.61), PDI <70 (OR = 2. 46, 95 % CI 0.94-6.45), cerebral palsy (OR = 1.08, 95 % CI 0.39-2.99), blindness (OR = 0.34, 95 % CI 0.01-8.56), and hearing loss (OR = 1.04, 95 % CI 0.06-17.15). There were no differences between groups with respect to the percentage of preterm infants with severe retinopathy of prematurity of stage III or above (OR = 1.30, 95 % CI 0.50-3.43), severe intraventricular hemorrhage of stage III or above (OR = 2. 91, 95 % CI 0.64-13.23), necrotizing enterocolitis (OR = 0.57, 95 % CI 0.13-2.54), and borderline personality disorder (OR = 1. 06, 95 % CI 0.50-2.26). The rhEPO treatment has beneficial effect on the neurodevelopment outcomes without severe adverse side effect in preterm infants.

Neuroprotective body hypothermia among newborns with hypoxic ischemic encephalopathy: three-year experience in a tertiary university hospital. A retrospective observational study

CONTEXT AND OBJECTIVE

Neonatal hypoxic-ischemic encephalopathy is associated with high morbidity and mortality. Studies have shown that therapeutic hypothermia decreases neurological sequelae and death. Our aim was therefore to report on a three-year experience of therapeutic hypothermia among asphyxiated newborns.

DESIGN AND SETTING

Retrospective study, conducted in a university hospital.

METHODS

Thirty-five patients with perinatal asphyxia undergoing body cooling between May 2009 and November 2012 were evaluated.

RESULTS

Thirty-nine infants fulfilled the hypothermia protocol criteria. Four newborns were removed from study due to refractory septic shock, non-maintenance of temperature and severe coagulopathy. The median Apgar scores at 1 and 5 minutes were 2 and 5. The main complication was infection, diagnosed in seven mothers (20%) and 14 newborns (40%). Convulsions occurred in 15 infants (43%). Thirty-one patients (88.6%) required mechanical ventilation and 14 of them (45%) were extubated within 24 hours. The duration of mechanical ventilation among the others was 7.7 days. The cooling protocol was started 1.8 hours after birth. All patients showed elevated levels of creatine phosphokinase, creatine phosphokinase- MB and lactate dehydrogenase. There was no severe arrhythmia; one newborn (2.9%) presented controlled coagulopathy. Four patients (11.4%) presented controlled hypotension. Twenty-nine patients (82.9%) underwent cerebral ultrasonography and 10 of them (34.5%) presented white matter hyper-echogenicity. Brain magnetic resonance imaging was performed on 33 infants (94.3%) and 11 of them (33.3%) presented hypoxic-ischemic changes. The hospital stay was 23 days. All newborns were discharged. Two patients (5.8%) needed gastrostomy.

CONCLUSION

Hypothermia as therapy for asphyxiated newborns was shown to be safe.

Inflammation-induced sensitization of the brain in term infants

Perinatal insults are a leading cause of infant mortality and amongst survivors are frequently associated with neurocognitive impairment, cerebral palsy (CP), and seizure disorders. The events leading to perinatal brain injury are multifactorial. This review describes how one subinjurious factor affecting the brain sensitizes it to a second injurious factor, causing an exacerbated injurious cascade. We will review the clinical and experimental evidence, including observations of high rates of maternal and fetal infections in term-born infants with neonatal encephalopathy and cerebral palsy. In addition, we will discuss preclinical evidence for the sensitizing effects of inflammation on injuries, such as hypoxia-ischaemia, our current understanding of the mechanisms underpinning the sensitization process, and the possibility for neuroprotection.

Tract-based spatial statistics to assess the neuroprotective effect of early erythropoietin on white matter development in preterm infants

Despite improved survival, many preterm infants undergo subsequent neurodevelopmental impairment. To date, no neuroprotective therapies have been implemented into clinical practice. Erythropoietin, a haematopoietic cytokine used for treatment of anaemia of prematurity, has been shown to have neuroprotective and neuroregenerative effects on the brain in many experimental studies. The aim of the study was to assess the effect of recombinant human erythropoietin on the microstructural development of the cerebral white matter using tract-based spatial statistics performed at term equivalent age. A randomized, double-blind placebo-controlled, prospective multicentre study applying recombinant human erythropoietin in the first 42 h after preterm birth entitled 'Does erythropoietin improve outcome in preterm infant' was conducted in Switzerland (NCT00413946). Preterm infants were given recombinant human erythropoietin (3000 IU) or an equivalent volume of placebo (NaCl 0.9%) intravenously before 3 h of age after birth, at 12-18 h and at 36-42 h after birth. High resolution diffusion tensor imaging was obtained at 3 T in 58 preterm infants with mean (standard deviation) gestational age at birth 29.75 (1.44) weeks, and at scanning at 41.1 (2.09) weeks. Imaging was performed at a single centre. Voxel-wise statistical analysis of the fractional anisotropy data was carried out using tract-based spatial statistics to test for differences in fractional anisotropy between infants treated with recombinant human erythropoietin and placebo using a general linear model, covarying for the gestational age at birth and the corrected gestational age at the time of the scan. Preterm infants treated with recombinant human erythropoietin demonstrated increased fractional anisotropy in the genu and splenium of the corpus callosum, the anterior and posterior limbs of the internal capsule, and the corticospinal tract bilaterally. Mean fractional anisotropy was significantly higher in preterm infants treated with recombinant human erythropoietin than in those treated with placebo (P < 0.001). We conclude that early recombinant human erythropoietin administration improves white matter development in preterm infants assessed by diffusion tensor imaging and tract-based spatial statistics.

Interdisciplinary approach to neurocritical care in the intensive care nursery

Neurocritical care is a multidisciplinary subspecialty that combines expertise in critical care medicine, neurology, and neurosurgery, and has led to improved outcomes in adults who have critical illnesses. Advances in resuscitation and critical care have led to high rates of survival among neonates with life-threatening conditions such as perinatal asphyxia, extreme prematurity, and congenital malformations. The sequelae of neurologic conditions arising in the neonatal period include lifelong disabilities such as cerebral palsy and epilepsy, as well as intellectual and behavioral disabilities. Centers of excellence have adapted the principles of neurocritical care to reflect the needs of the developing newborn brain, including early involvement of a neurologist for recognition and treatment of neurologic conditions, attention to physiology to help prevent secondary brain injury, a protocol-driven approach for common conditions like seizures and hypoxic-ischemic encephalopathy, and education of specialized teams that use brain monitoring and imaging to evaluate the effect of critical illness on brain function and development.

Depressed heart rate variability is associated with abnormal EEG, MRI, and death in neonates with hypoxic ischemic encephalopathy

OBJECTIVE

Asphyxia can lead to autonomic nervous system dysfunction, including depressed heart rate variability (HRV). We tested the hypothesis that low HRV is associated with adverse short-term outcomes of abnormalities on electroencephalogram (EEG) and brain magnetic resonance imaging (MRI) and death in neonates with hypoxic ischemic encephalopathy (HIE).

STUDY DESIGN

Neonates undergoing hypothermia therapy for HIE underwent monitoring of HRV. HRV in the first day after birth and after hypothermia and rewarming (days 4-7) were analyzed in relation to death and severity of abnormal findings on EEG and MRI.

RESULTS

A total of 37 neonates had data available in the first 24 hour after birth and 67 had data days 2 to 7. Depressed HRV was significantly associated with adverse outcomes of death or moderate-to-severe abnormalities on EEG or MRI. In the first 24 hours, the odds ratio (OR) of one or more adverse outcomes for every 10-millisecond decrease in HRV was 3.19 (95% CI, 1.3-7.8; p = 0.01). HRV improved over time but low HRV remained significantly associated with adverse outcomes days 4 to 7 (OR, 2.72; CI, 1.32-5.61; p < 0.01).

CONCLUSIONS

Monitoring HRV, which is reflected in the heart rate characteristic index, may provide useful adjunct information on the severity of brain injury in infants with HIE.

Early intervention after perinatal stroke: opportunities and challenges

Perinatal stroke is the most common cause of hemiplegic cerebral palsy. No standardized early intervention exists despite evidence for a critical time window for activity-dependent plasticity to mould corticospinal tract development in the first few years of life. Intervention during this unique period of plasticity could mitigate the consequences of perinatal stroke to an extent not possible with later intervention, by preserving the normal pattern of development of descending motor pathways. This article outlines the broad range of approaches currently under investigation. Despite significant progress in this area, improved early detection and outcome prediction remain important goals.

Protection by vascular prostaglandin E2 signaling in hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) in neonates is a leading cause of neurological impairment. Significant progress has been achieved investigating the pathologic contributions of excitotoxicity, oxidative stress, and neuroinflammation to cerebral injury in HIE. Less extensively investigated has been the contribution of vascular dysfunction, and whether modulation of cerebral perfusion may improve HIE outcome. Here, we investigated the function of the prostaglandin E2 (PGE2) EP4 receptor, a vasoactive Gαs-protein coupled receptor (GPCR), in rodent models of neonatal HIE. The function of PGE2 signaling through the EP4 receptor was investigated using pharmacological and conditional knockout genetic strategies in vivo in rodent models of HIE. Pharmacologic activation of the EP4 receptor with a selective agonist was significantly cerebroprotective both acutely and after 7days. Measurement of cerebral perfusion during and after hypoxia-ischemia demonstrated that EP4 receptor activation improved cerebral perfusion in both the contralateral and ipsilateral hypoxic-ischemic hemispheres. To test whether vascular EP4 signaling exerted a critical function in HIE injury, cell specific conditional knockout mouse pups were generated in which endothelial EP4 receptor was selectively deleted postnatally. VE-Cadherin Cre-ER(T2);EP4(lox/lox) pups demonstrated significant increases in cerebral injury as compared to VE-Cadherin Cre-ER(T2);EP4(+/+) control littermates, indicating that endothelial EP4 signaling is protective in HIE. Our findings identify vascular PGE2 signaling through its EP4 receptor as protective in HIE. Given the pharmacologic accessibility of endothelial EP4 GPCRs, these data support further investigation into novel approaches to target cerebral perfusion in neonatal HIE.

Cannabinoids: well-suited candidates for the treatment of perinatal brain injury

Perinatal brain injury can be induced by a number of different damaging events occurring during or shortly after birth, including neonatal asphyxia, neonatal hypoxia-ischemia and stroke-induced focal ischemia. Typical manifestations of these conditions are the presence of glutamate excitoxicity, neuroinflammation and oxidative stress, the combination of which can potentially result in apoptotic-necrotic cell death, generation of brain lesions and long-lasting functional impairment. In spite of the high incidence of perinatal brain injury, the number of clinical interventions available for the treatment of the affected newborn babies is extremely limited. Hence, there is a dramatic need to develop new effective therapies aimed to prevent acute brain damage and enhance the endogenous mechanisms of long-term brain repair. The endocannabinoid system is an endogenous neuromodulatory system involved in the control of multiple central and peripheral functions. An early responder to neuronal injury, the endocannabinoid system has been described as an endogenous neuroprotective system that once activated can prevent glutamate excitotoxicity, intracellular calcium accumulation, activation of cell death pathways, microglia activation, neurovascular reactivity and infiltration of circulating leukocytes across the blood-brain barrier. The modulation of the endocannabinoid system has proven to be an effective neuroprotective strategy to prevent and reduce neonatal brain injury in different animal models and species. Also, the beneficial role of the endocannabinoid system on the control of the endogenous repairing responses (neurogenesis and white matter restoration) to neonatal brain injury has been described in independent studies. This review addresses the particular effects of several drugs that modulate the activity of the endocannabinoid system on the progression of different manifestations of perinatal brain injury during both the acute and chronic recovery phases using rodent and non-rodent animal models, and will provide a complete description of the known mechanisms that mediate such effects.

Esophageal mechanosensitive mechanisms are impaired in neonates with hypoxic-ischemic encephalopathy

OBJECTIVES

To test the hypothesis that esophageal mechanodistention in infants with hypoxic-ischemic encephalopathy (HIE) results in altered upper esophageal sphincter (UES), esophageal body, and lower esophageal sphincter (LES) responses, compared with controls. As a secondary aim, we tested the hypothesis that infants with HIE receiving therapeutic hypothermia had different aerodigestive reflex characteristics than infants with HIE who received traditional neonatal care.

STUDY DESIGN

Provocative esophageal manometry was performed in 34 neonates (27 with HIE and 7 controls). Mechanodistention was performed using graded volumes of air. Peristaltic reflexes, UES contractile reflexes, and LES relaxation reflexes were analyzed for frequency, magnitude, and aberrancies.

RESULTS

Infants with HIE demonstrated more rapid recruitment of responses and greater UES magnitude (P < .05). They had more frequent secondary peristalsis and lower LES nadir pressures with prolonged LES nadir durations (P < .05). Most notable were the prolonged peristaltic response durations and increases in the number of polymorphic waveforms (P < .05). Compared with infants with HIE receiving traditional care, infants with HIE treated with hypothermia had higher UES pressures and shorter peristaltic response duration (P < .05).

CONCLUSIONS

Mechanodistention in infants with HIE results in upregulation of central vagal effects (ie, heightened cholinergic excitatory responses as demonstrated by exaggerated UES contractile reflex activity and heightened inhibitory responses evident by exaggerated LES relaxation reflex activity). Prolonged and poorly coordinated peristaltic responses may underlie dysfunction of aerodigestive regulation. Modulation of sensorimotor aspects of aerodigestive reflexes is altered in infants with HIE, and hypothermia may further modify such effects.

Peripartum consultations expand the role of the fetal/neonatal neurologist

The peripartum period entails the next prenatal interval when novel neuroprotective strategies will be designed and tested. Research development will lead to novel evaluations for maternal-fetal pairs who require inpatient treatment and possible delivery for worsening or acute neurologic problems. Future studies should critically compare serial fetal surveillance assessments with postnatal clinical findings to detect and treat more accurately fetal/neonatal brain disorders that begin or worsen during the peripartum period. Clinical management decisions require an interdisciplinary treatment approach. Protocols may begin before and during parturition, and continue through neonatal resuscitation and early postnatal periods into infancy. Appropriate choices of preventive, rescue, and repair neuroprotective interventions must consider both the timing and etiologies of encephalopathies in the context of maternal, fetal, placental, and neonatal diseases.

Ultrasonografía craneal neonatal

La neuroecografía está posicionada en  la práctica clínica, de acuerdo a la literatura consultada, como un procedimiento con una especificidad  y  efectividad  que  permite  dar  un reporte diagnóstico con seguridad. Esta técnica tiene como ventajas la exploración en tiempo real, el carácter atóxico e inocuo  del procedimiento  y  el  corto  tiempo  en  el  que  se realiza, según  la experticia del  realizador. Como herramienta diagnóstica  en recién nacidos  pretérminos  una  de  las principales indicaciones para la solicitud del procedimiento es poder hacer la   identificación de las alteraciones visibles en  la  anatomía  macroscópica,  teniendo  en cuenta  las ventajas proporcionadas por  la ventana acústica utilizada en el estudio sonográfico, las cuales dependen principalmente de la proximidad del transductor a la neuroanatomía que se desea explorar.

Doxycycline treatment in a neonatal rat model of hypoxia-ischemia reduces cerebral tissue and white matter injury: a longitudinal magnetic resonance imaging study

Doxycycline may potentially be a neuroprotective treatment for neonatal hypoxic-ischemic brain injury through its anti-inflammatory effects. The aim of this study was to examine any long-term neuroprotection by doxycycline treatment on cerebral gray and white matter. Hypoxic-ischemic brain injury was induced in 7-day-old rats. Pups were treated with either doxycycline (HI+doxy) or saline (HI+vehicle) by intraperitoneal injection at 1 h after hypoxia-ischemia (HI). At 6 h after HI, MnCl(2) was injected intraperitoneally for later manganese-enhanced magnetic resonance imaging (MRI). MRI was performed with diffusion-weighted imaging on day 1 and T(1) -weighted imaging and diffusion tensor imaging at 7, 21 and 42 days after HI. Animals were killed after MRI on day 42 and histological examinations of the brains were performed. There was a tendency towards lower lesion volumes on diffusion maps among HI+doxy than HI+vehicle rats at 1 day after HI. Volumetric MRI showed increasing differences between groups with time after HI, with less cyst formation and less cerebral tissue loss among HI+doxy than HI+vehicle pups. HI+doxy pups had less manganese enhancement on day 7 after HI, indicating reduced inflammation. HI+doxy pups had higher fractional anisotropy on diffusion tensor imaging in major white matter tracts in the injured hemisphere than HI+vehicle pups, indicating less injury to white matter and better myelination. Histological examinations supported the MRI results. Lesion size on early MRI was highly correlated with final injury measures. In conclusion, a single dose of doxycycline reduced long-term cerebral tissue loss and white matter injury after neonatal HI, with an increasing effect of treatment with time after injury.

An interdisciplinary fetal/neonatal neurology program

A fetal/neonatal neurology program should encompass interdisciplinary service, educational and research objectives, merging curricula concerning maternal, placental, fetal and neonatal contributions to brain health and disease. This approach is anchored by research in early life programming that demonstrates that prenatal and postnatal factors influence long-term neurologic health. This concept also supports the design of neuroprotective interventions during critical periods of brain development when brain circuitries more optimally adapt to maturational challenges. Preventive, rescue and repair protocols will transform pediatric medical practices, to promote improved childhood outcomes. Inclusion of life-course science and research will identify medical and socioeconomic factors that favorably or adversely affect quality of life into adulthood. Greater awareness of the convergence of developmental origins of brain health and disease and developmental aging theories will influence public health policies, to encourage financial support for programs that will improve the quality of life for the child and adult.

Molecular mechanisms of neonatal brain injury

Fetal/neonatal brain injury is an important cause of neurological disability. Hypoxia-ischemia and excitotoxicity are considered important insults, and, in spite of their acute nature, brain injury develops over a protracted time period during the primary, secondary, and tertiary phases. The concept that most of the injury develops with a delay after the insult makes it possible to provide effective neuroprotective treatment after the insult. Indeed, hypothermia applied within 6 hours after birth in neonatal encephalopathy reduces neurological disability in clinical trials. In order to develop the next generation of treatment, we need to know more about the pathophysiological mechanism during the secondary and tertiary phases of injury. We review some of the critical molecular events related to mitochondrial dysfunction and apoptosis during the secondary phase and report some recent evidence that intervention may be feasible also days-weeks after the insult.

Current controversies in newer therapies to treat birth asphyxia

Despite major advances in monitoring technology and knowledge of fetal and neonatal pathophysiology, neonatal hypoxic-ischemic encephalopathy (HIE) remains one of the main causes of severe adverse neurological outcome in children. Until recently, there were no therapies other than supportive measures. Over the past several years, mild hypothermia has been proven to be safe to treat HIE. Unfortunately, this neuroprotective strategy seems efficient in preventing brain injury in some asphyxiated newborns, but not in all of them. Thus, there is increasing interest to rapidly understand how to refine hypothermia therapy and add neuroprotective or neurorestorative strategies. Several promising newer treatments to treat birth asphyxia and prevent its devastating neurological consequences are currently being tested. In this paper, the physiopathology behind HIE, the currently available treatment, the potential alternatives, and the next steps before implementation of these other treatments are reviewed.

Targeting neonatal ischemic brain injury with a pentapeptide-based irreversible caspase inhibitor

Brain protection of the newborn remains a challenging priority and represents a totally unmet medical need. Pharmacological inhibition of caspases appears as a promising strategy for neuroprotection. In a translational perspective, we have developed a pentapeptide-based group II caspase inhibitor, TRP601/ORPHA133563, which reaches the brain, and inhibits caspases activation, mitochondrial release of cytochrome c, and apoptosis in vivo. Single administration of TRP601 protects newborn rodent brain against excitotoxicity, hypoxia-ischemia, and perinatal arterial stroke with a 6-h therapeutic time window, and has no adverse effects on physiological parameters. Safety pharmacology investigations, and toxicology studies in rodent and canine neonates, suggest that TRP601 is a lead compound for further drug development to treat ischemic brain damage in human newborns.

Erythropoietin in neonatal brain protection: the past, the present and the future

Over the last decade, neuroprotective effects of erythropoietin (Epo) and its underlying mechanisms in terms of signal transduction pathways have been defined and there is a growing interest in the potential therapeutic use of Epo for neuroprotection. Several mechanisms by which Epo provides neuroprotection are recognized. In this review, we focused on the neuroprotective mechanisms of Epo and provide a short overview on both experimental and clinical studies, testing Epo as a neuroprotective agent in the neonatal brain injury, and the safety concerns with the clinical use of Epo treatment in neonates.

A new neurological focus in neonatal intensive care

Advances in the care of high-risk newborn babies have contributed to reduced mortality rates for premature and term births, but the surviving neonates often have increased neurological morbidity. Therapies aimed at reducing the neurological sequelae of birth asphyxia at term have brought hypothermia treatment into the realm of standard care. However, this therapy does not provide complete protection from neurological complications and a need to develop adjunctive therapies for improved neurological outcomes remains. In addition, the care of neurologically impaired neonates, regardless of their gestational age, clearly requires a focused approach to avoid further injury to the brain and to optimize the neurodevelopmental status of the newborn baby at discharge from hospital. This focused approach includes, but is not limited to, monitoring of the patient's brain with amplitude-integrated and continuous video EEG, prevention of infection, developmentally appropriate care, and family support. Provision of dedicated neurocritical care to newborn babies requires a collaborative effort between neonatologists and neurologists, training in neonatal neurology for nurses and future generations of care providers, and the recognition that common neonatal medical problems and intensive care have an effect on the developing brain.

Treatment advances in neonatal neuroprotection and neurointensive care

Knowledge of the nature, prognosis, and ways to treat brain lesions in neonatal infants has increased remarkably. Neonatal hypoxic-ischaemic encephalopathy (HIE) in term infants, mirrors a progressive cascade of excito-oxidative events that unfold in the brain after an asphyxial insult. In the laboratory, this cascade can be blocked to protect brain tissue through the process of neuroprotection. However, proof of a clinical effect was lacking until the publication of three positive randomised controlled trials of moderate hypothermia for term infants with HIE. These results have greatly improved treatment prospects for babies with asphyxia and altered understanding of the theory of neuroprotection. The studies show that moderate hypothermia within 6 h of asphyxia improves survival without cerebral palsy or other disability by about 40% and reduces death or neurological disability by nearly 30%. The search is on to discover adjuvant treatments that can further enhance the effects of hypothermia.

Perinatal asphyxia in a nonhuman primate model

Perinatal asphyxia is a leading cause of brain injury in neonates, occurring in 2-4 per 1,000 live births, and there are limited treatment options. Because of their similarity to humans, nonhuman primates are ideal for performing preclinical tests of safety and efficacy for neurotherapeutic interventions. We previously developed a primate model of acute perinatal asphyxia using 12-15 min of umbilical cord occlusion. Continuing this research, we have increased cord occlusion time from 15 to 18 min and extended neurodevelopmental follow-up to 9 months. The purpose of this report is to evaluate the increase in morbidity associated with 18 min of asphyxia by comparing indices obtained from colony controls, nonasphyxiated controls and asphyxiated animals. Pigtail macaques were delivered by hysterotomy after 0, 15 or 18 min of cord occlusion, then resuscitated. Over the ensuing 9 months, for each biochemical and physiologic parameters, behavioral and developmental evaluations, and structural and spectroscopic MRI were recorded. At birth, all asphyxiated animals required resuscitation with positive pressure ventilation and exhibited biochemical and clinical characteristics diagnostic of hypoxic-ischemic encephalopathy, including metabolic acidosis and attenuated brain activity. Compared with controls, asphyxiated animals developed long-term physical and cognitive deficits. This preliminary report characterizes the acute and chronic consequences of perinatal asphyxia in a nonhuman primate model, and describes diagnostic imaging tools for quantifying correlates of neonatal brain injury as well as neurodevelopmental tests for evaluating early motor and cognitive outcomes.

Treating inflammation in childhood neurodegenerative disorders

Inflammation of the central nervous system is a prominent feature in many childhood neurodegenerative conditions, with various studies demonstrating the upregulation of the innate and adaptive immune system. Recent evidence also suggests that this inflammatory process can contribute to further neurodegeneration. Furthermore, immunosuppression in mouse models of a few lysosomal storage disorders has demonstrated that attenuation of this immune response can influence the clinical and neuropathological progression. However, there are significant challenges before this finding translates to patient care. Treating inflammation in neurodegenerative conditions requires the identification of the time point when inflammation becomes pathogenic, after which the safest therapeutic strategies are required to target the various components and confounders of inflammation. Nevertheless, as the progress made towards effective gene-, cellular-, and enzyme-based therapy in most of these disorders has been disappointing, treating pathogenic inflammation may offer the clinician another therapeutic strategy in managing these devastating disorders.

Perinatal events and early magnetic resonance imaging in therapeutic hypothermia

OBJECTIVE

To compare the association between perinatal events and the pattern and extent of brain injury on early magnetic resonance imaging in newborn infants with and without therapeutic hypothermia for hypoxic-ischemic encephalopathy.

STUDY DESIGN

We performed a cohort study of 35 treated and 25 nontreated neonates who underwent magnetic resonance imaging. The injury patterns were defined a priori as: normal, watershed, or basal ganglia/thalamus-predominant, as well as a dichotomous outcome of moderate-to-severe versus mild-no injury.

RESULTS

Neonates with hypothermia had less extensive watershed and basal ganglia/thalamus injuries and a greater proportion had normal imaging. Therapeutic hypothermia was associated with a decreased risk of both basal ganglia/thalamus injury (relative risk, 0.29; 95% CI, 0.10 to 0.81, P = .01) and moderate-severe injury. Neonates with sentinel events showed a decrease in basal ganglia/thalamus-predominant injury and an increase in normal imaging. All neonates with decreased fetal movements had injury, predominantly watershed, regardless of therapeutic hypothermia.

CONCLUSIONS

These results validate reports of reduced brain injury after therapeutic hypothermia and suggest that perinatal factors are important indicators of response to treatment.

[Cerebral palsy and perinatal asphyxia (II--Medicolegal implications and prevention)]

Obstetric litigation is a growing problem in developed countries and its escalating cost together with increasing medical insurance premiums is a major concern for maternity service providers, leading to obstetric practice cessation by many practitioners. Fifty-four to 74 % of claims are based on cardiotocographic (CTG) abnormalities and their interpretation followed by inappropriate or delayed reactions. A critical analysis is performed about the nine criteria identified by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics in their task force on Neonatal Encephalopathy and Cerebral Palsy: four essential criteria defining neonatal asphyxia and five other suggesting an acute intrapartum event sufficient to cause cerebral palsy in term newborns. The importance of placental histologic examination is emphasized in order to confirm sudden catastrophic events occurring before or during labor or to detect occult thrombotic processes affecting the fetal circulation, patterns of decreased placenta reserve and adaptative responses to chronic hypoxia. It may also exclude intrapartum hypoxia by revealing some histologic patterns typical of acute chorioamnionitis and fetal inflammatory response or compatible with metabolic diseases. Magnetic resonance imaging (MRI) of the infant's damaged brain is very contributive to elucidate the mechanism and timing of asphyxia in conjunction with the clinical picture, by locating cerebral injuries predominantly in white or grey matter. Intrapartum asphyxia is sometimes preventable by delivering weak fetuses by cesarean sections before birth, by avoiding some "sentinel" events, and essentially by responding appropriately to CTG anomalies and performing an efficient neonatal resuscitation. During litigation procedures, it is necessary to have access to a readable CTG, a well-documented partogram, a complete analysis of umbilical cord gases, a placental pathology and an extensive clinical work-up of the newborn infant including cerebral MRI. Malpractice litigation in obstetric care can be reduced by permanent CTG education, respect of national CTG guidelines, use of adjuncts such as fetal blood sampling for pH or lactates, regular review of adverse events in Clinical Risk Management (CRM) groups and periodic audits about low arterial cord pH in newborns, admission to neonatal unit, the need for assisted ventilation and the decision-to-delivery interval for emergency operative deliveries. Considering the fast occurrence of fetal cerebral hypoxic injuries, and thus despite an adequate management, many intrapartum asphyxias will not be preventable. Conversely, well-documented hypoxic-ischemic brain insults during the antenatal period do not automatically exclude intrapartum suboptimal obstetric care.