Actualities on molecular pathogenesis and repairing processes of cerebral damage in perinatal hypoxic-ischemic encephalopathy

Oxidative and Antioxidative Biomarker Profiles in Neonatal Hypoxic-Ischemic Encephalopathy: Insights for Pathophysiology and Treatment Strategies

BACKGROUND Neonatal hypoxic-ischemic encephalopathy (HIE) is a significant cause of perinatal and postnatal morbidity and mortality worldwide. Catalase (CAT) activity detection is used to determine levels of inflammation and oxidative stress. Glutathione (GSH) is the most critical non-enzymatic endogenous antioxidant. Lipid peroxidation levels marked after hypoxia can be detected based on the level of malondialdehyde (MDA). Ischemia-modified albumin (IMA) is considered a biomarker for cardiac ischemia and is known to increase in the liver, brain, and kidney in states of insufficient oxygenation. We aimed to explain the results and relations between the oxidant and antioxidants to detail oxidant-antioxidant balance and cellular mechanisms. MATERIAL AND METHODS Serum levels of IMA and MDA, as an oxidative stress marker, and CAT and GSH, as antioxidant enzymes, were measured in first blood samples of 59 neonates diagnosed with HIE, with pH <7, base excess >12, and APGAR scores. RESULTS Neonates who were ≥37 weeks of gestation and had hypoxia were included. Compared with healthy newborns (n=32), CAT was statistically significantly lower in the hypoxia group (P=0.0001), while MDA serum levels were significantly higher in neonates with hypoxia (P=0.01). There was no difference between hypoxic and healthy neonates in GSH and IMA measurements (P=0.054, P=0.19 respectively). CONCLUSIONS HIE pathophysiology involves oxidative stress and mitochondrial energy production failure. Explaining the pathways between oxidant-antioxidant balance and cell death, which explains the pathophysiology of HIE, is essential to develop treatment strategies that will minimize the effects of oxygen deprivation on other body organs, especially the brain.

Oligodendrocyte progenitor cells' fate after neonatal asphyxia-Puzzling implications for the development of hypoxic-ischemic encephalopathy

Premature birth or complications during labor can cause temporary disruption of cerebral blood flow, often followed by long-term disturbances in brain development called hypoxic-ischemic (HI) encephalopathy. Diffuse damage to the white matter is the most frequently detected pathology in this condition. We hypothesized that oligodendrocyte progenitor cell (OPC) differentiation disturbed by mild neonatal asphyxia may affect the viability, maturation, and physiological functioning of oligodendrocytes. To address this issue, we studied the effect of temporal HI in the in vivo model in P7 rats with magnetic resonance imaging (MRI), microscopy techniques and biochemical analyses. Moreover, we recreated the injury in vitro performing the procedure of oxygen-glucose deprivation on rat neonatal OPCs to determine its effect on cell viability, proliferation, and differentiation. In the in vivo model, MRI evaluation revealed changes in the volume of different brain regions, as well as changes in the directional diffusivity of water in brain tissue that may suggest pathological changes to myelinated neuronal fibers. Hypomyelination was observed in the cortex, striatum, and CA3 region of the hippocampus. Severe changes to myelin ultrastructure were observed, including delamination of myelin sheets. Interestingly, shortly after the injury, an increase in oligodendrocyte proliferation was observed, followed by an overproduction of myelin proteins 4 weeks after HI. Results verified with the in vitro model indicate, that in the first days after damage, OPCs do not show reduced viability, intensively proliferate, and overexpress myelin proteins and oligodendrocyte-specific transcription factors. In conclusion, despite the increase in oligodendrocyte proliferation and myelin protein expression after HI, the production of functional myelin sheaths in brain tissue is impaired. Presented study provides a detailed description of oligodendrocyte pathophysiology developed in an effect of HI injury, resulting in an altered CNS myelination. The described models may serve as useful tools for searching and testing effective of effective myelination-supporting therapies for HI injuries.

The role of ApoE in fatty acid transport from neurons to astrocytes under ischemia/hypoxia conditions

BACKGROUND

The aim of this study was to investigate whether ischemia/hypoxia conditions induce fatty acid transport from neurons to astrocytes and whether this mechanism is affected by ApoE isoforms.

METHODS AND RESULTS

A neonatal rat model of hypoxic-ischemic brain damage was established. Excessive accumulation of lipid droplets and upregulation of ApoE expression occurred in the hippocampus and cerebral cortex after hypoxia-ischemia, which implied the occurrence of abnormal fatty acid metabolism. Lipid peroxidation was induced in an oxygen-glucose deprivation and reperfusion (OGDR) model of ApoE-/- primary neurons. The number of BODIPY 558/568 C12-positive particles (fatty acid markers) transferred from neurons to astrocytes was significantly increased with the addition of human recombinant ApoE compared with that in the OGDR group, which significantly increased the efficiency of fatty acid transport from neurons to astrocytes and neuronal viability. However, ApoE4 was found to be associated with lower efficiency in fatty acid transport and less protective effects in OGDR-induced neuronal cell death than both ApoE2 and ApoE3. COG133, an ApoE-mimetic peptide, partially compensated for the adverse effects of ApoE4. FABP5 and SOD1 gene and protein expression levels were upregulated in astrocytes treated with BODIPY 558/568 C12 particles.

CONCLUSIONS

In conclusion, ApoE plays an important role in mediating the transport of fatty acids from neurons to astrocytes under ischemia/hypoxia conditions, and this transport mechanism is ApoE isoform dependent. ApoE4 has a low transfer efficiency and may be a potential target for the clinical treatment of neonatal hypoxic-ischemic encephalopathy.

Pathophysiological aspects of neonatal anoxia and temporal expression of S100β in different brain regions

The aim of this study was to investigate the temporal variations of S100β in the hippocampus, cerebellum and cerebral cortex of neonatal rats (Wistar strain) under anoxic conditions. Real-time PCR and western blotting techniques were used for gene expression and protein analysis. Animals were divided into two groups, a control group and an anoxic group, and further separated at different time points for analysis. After anoxia, S100β gene expression showed a significant peak in the hippocampus and cerebellum after 2 h, followed by a decline compared to the control group at other time points. The increased gene expression in these regions was also accompanied by an increase in S100β protein levels in the anoxia group, observable 4 h after injury. In contrast, S100β mRNA content in the cerebral cortex never exceeded control values at any time point. Similarly, the protein content of S100β in the cerebral cortex did not show statistically significant differences compared to control animals at any assessment time point. These results suggest that the production profile of S100β differs by brain region and developmental stage. The observed differences in vulnerability between the hippocampus, cerebellum and cerebral cortex may be attributed to their distinct developmental periods. The hippocampus and cerebellum, which develop earlier than the cerebral cortex, showed more pronounced effects in response to anoxia, which is supported by the gene expression and protein content in this study. This result reveals the brain region-dependent nature of S100β as a biomarker of brain injury.

Magnetic resonance spectroscopy and liquid chromatography-mass spectrometry metabolomics study may differentiate pre-eclampsia from gestational hypertension

OBJECTIVE

To investigate the findings of magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and serum metabolomics for differentiating pre-eclampsia (PE) from gestational hypertension (GH).

METHODS

This prospective study enrolled 176 subjects including a primary cohort with healthy non-pregnant women (HN, n = 35), healthy pregnant women (HP, n = 20), GH (n = 27), and PE (n = 39) and a validation cohort with HP (n = 22), GH (n = 22), and PE (n = 11). T1 signal intensity index (T1SI), apparent diffusion coefficient (ADC) value, and the metabolites on MRS were compared. The differentiating performances of single and combined MRI and MRS parameters for PE were evaluated. Serum liquid chromatography-mass spectrometry (LC-MS) metabolomics was investigated by sparse projection to latent structures discriminant analysis.

RESULTS

Increased T1SI, lactate/creatine (Lac/Cr), and glutamine and glutamate (Glx)/Cr and decreased ADC value and myo-inositol (mI)/Cr in basal ganglia were found in PE patients. T1SI, ADC, Lac/Cr, Glx/Cr, and mI/Cr yielded an area under the curves (AUC) of 0.90, 0.80, 0.94, 0.96, and 0.94 in the primary cohort, and of 0.87, 0.81, 0.91, 0.84, and 0.83 in the validation cohort, respectively. A combination of Lac/Cr, Glx/Cr, and mI/Cr yielded the highest AUC of 0.98 in the primary cohort and 0.97 in the validation cohort. Serum metabolomics analysis showed 12 differential metabolites, which are involved in pyruvate metabolism, alanine metabolism, glycolysis, gluconeogenesis, and glutamate metabolism.

CONCLUSIONS

MRS is expected to be a noninvasive and effective tool for monitoring GH patients to avoid the development of PE.

KEY POINTS

• Increased T1SI and decreased ADC value in the basal ganglia were found in PE patients than in GH patients. • Increased Lac/Cr and Glx/Cr, and decreased mI/Cr in the basal ganglia were found in PE patients than in GH patients. • LC-MS metabolomics showed that the major differential metabolic pathways between PE and GH were pyruvate metabolism, alanine metabolism, glycolysis, gluconeogenesis, and glutamate metabolism.

Repurposed Edaravone, Metformin, and Perampanel as a Potential Treatment for Hypoxia-Ischemia Encephalopathy: An In Vitro Study

Hypoxia-ischemia encephalopathy results from the interruption of oxygen delivery and blood flow to the brain. In the developing brain, it can lead to a brain injury, which is associated with high mortality rates and comorbidities. The hippocampus is one of the brain regions that may be affected by hypoxia-ischemia with consequences on cognition. Unfortunately, clinically approved therapeutics are still scarce and limited. Therefore, in this study, we aimed to test three repurposed drugs with good pharmacological properties to evaluate if they can revert, or at least attenuate, the deleterious effects of hypoxia-ischemia in an in vitro model. Edaravone, perampanel, and metformin are used for the treatment of stroke and amyotrophic lateral sclerosis, some forms of epileptic status, and diabetes type 2, respectively. Through cell viability assays, morphology analysis, and detection of reactive oxygen species (ROS) production, in two different cell lines (HT-22 and SH-SY5Y), we found that edaravone and low concentrations of perampanel are able to attenuate cell damage induced by hypoxia and oxygen-glucose deprivation. Metformin did not attenuate hypoxic-induced events, at least in the initial phase. Among these repurposed drugs, edaravone emerged as the most efficient in the attenuation of events induced by hypoxia-ischemia, and the safest, since it did not exhibit significant cytotoxicity, even in high concentrations, and induced a decrease in ROS. Our results also reinforce the view that ROS and overexcitation play an important role in the pathophysiology of hypoxia-ischemia brain injury.

Development of a composite diffusion tensor imaging score correlating with short-term neurological status in neonatal hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is the most common cause of neonatal acquired brain injury. Although conventional MRI may predict neurodevelopmental outcomes, accurate prognostication remains difficult. As diffusion tensor imaging (DTI) may provide an additional diagnostic and prognostic value over conventional MRI, we aimed to develop a composite DTI (cDTI) score to relate to short-term neurological function. Sixty prospective neonates treated with therapeutic hypothermia (TH) for HIE were evaluated with DTI, with a voxel size of 1 × 1 × 2 mm. Fractional anisotropy (FA) and mean diffusivity (MD) from 100 neuroanatomical regions (FA/MD *100 = 200 DTI parameters in total) were quantified using an atlas-based image parcellation technique. A least absolute shrinkage and selection operator (LASSO) regression was applied to the DTI parameters to generate the cDTI score. Time to full oral nutrition [short-term oral feeding (STO) score] was used as a measure of short-term neurological function and was correlated with extracted DTI features. Seventeen DTI parameters were selected with LASSO and built into the final unbiased regression model. The selected factors included FA or MD values of the limbic structures, the corticospinal tract, and the frontotemporal cortices. While the cDTI score strongly correlated with the STO score (rho = 0.83, p = 2.8 × 10-16), it only weakly correlated with the Sarnat score (rho = 0.27, p = 0.035) and moderately with the NICHD-NRN neuroimaging score (rho = 0.43, p = 6.6 × 10-04). In contrast to the cDTI score, the NICHD-NRN score only moderately correlated with the STO score (rho = 0.37, p = 0.0037). Using a mixed-model analysis, interleukin-10 at admission to the NICU (p = 1.5 × 10-13) and tau protein at the end of TH/rewarming (p = 0.036) and after rewarming (p = 0.0015) were significantly associated with higher cDTI scores, suggesting that high cDTI scores were related to the intensity of the early inflammatory response and the severity of neuronal impairment after TH. In conclusion, a data-driven unbiased approach was applied to identify anatomical structures associated with some aspects of neurological function of HIE neonates after cooling and to build a cDTI score, which was correlated with the severity of short-term neurological functions.

Serum troponin I: a potential biomarker of hypoxic-ischemic encephalopathy in term newborns

OBJECTIVE

This study was intended to evaluate the predictive values of serum procalcitonin (PCT), lactate, creatine kinase (CK-MB), and troponin I on the diagnosis and staging of neonatal hypoxic-ischemic encephalopathy (HIE).

MATERIALS AND METHODS

We retrospectively retrieved data from electronic medical records at our children's hospital, and we included all term newborns admitted between December 2018 and June 2020 with features of perinatal asphyxia. Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to measure and evaluate the predictive values of biomarkers. p values < 0.05 were set as statistical significance.

RESULTS

A total of 201 neonates were included. They were grouped as control (n = 40), mild HIE (n = 105), moderate HIE (n = 36), and severe HIE (n = 20). Serum lactate, PCT, CK-MB, and troponin I levels in severe hypoxic-ischemic brain injury group were significantly higher than those in mild to moderate hypoxic-ischemic brain injury group and control group (p < 0.05). Based on ROC and AUC analysis, troponin I showed highest predictive ability with AUC of 0.904, and sensitivity and specificity of 95.00% and 87.50% respectively.

CONCLUSION

Serum troponin I has a good predictive value for neonatal hypoxic-ischemic encephalopathy after perinatal asphyxia.

Amide proton transfer (APT) imaging-based study on the correlation between brain pH and voltage-gated proton channels in piglets after hypoxic-ischemic brain injury

Background

The normal regulation of brain pH is particularly critical for protein structure and enzymatic catalysis in the brain. This study aimed to investigate the regulation mechanism of brain pH after hypoxic-ischemic brain injury (HIBI) through the combination of amide proton transfer (APT) imaging, the analysis of brain pH levels, and the analysis of voltage-gated proton channel (Hv1) expression in piglets with HIBI.

Methods

A total of 59 healthy piglets (age range, 3-5 days after birth; body weight, 1-1.5 kg) were selected. Six piglets were excluded due to death, modeling failure, or motion artifacts, leaving a total of 10 animals in the control group and 43 animals in the HIBI model group. At different time points (0-2, 2-6, 6-12, 12-24, 24-48, and 48-72 hours) after HIBI, brain pH, Hv1 expression, and APT values were measured and analyzed. The statistical analysis of data was performed using the independent samples t-test, analysis of variance, and Spearman rank correlation analysis. A P value less than 0.05 indicated statistical significance.

Results

As shown by the immunofluorescent staining results after HIBI, Hv1 protein expression in the basal ganglia reached a peak value at 0-2 hours, with a statistically significant difference between 0-2 hours and other time points (P<0.001). In piglets, the APT value reached a trough at 0-2 hours after HIBI, and subsequently, it gradually increased, and there was a significant difference between the control group and all HIBI model subgroups (P<0.001) except for the 2-6 hours subgroup (P=0.602). Brain pH decreased after HIBI and reached a trough at 0-2 hours, then gradually increased. Hv1 protein expression, pH, and APT values were all correlated (P<0.001).

Conclusions

After HIBI, values of brain pH, APT, and the expression of Hv1 changed over time and had a linear correlation. This suggests that there was a shift in brain hydrogen ions (H⁺) in the neural network and a change in brain pH after hypoxic-ischemic (HI) injury.

Evaluation of the role of ischemia modified albumin in neonatal hypoxic-ischemic encephalopathy

BACKGROUND

Birth asphyxia is a leading cause of neonatal mortality. Ischemia-modified albumin (IMA) levels may have a predictive role in the identification and prevention of hypoxic disorders, as they increase in cases of ischemia of the liver, heart, brain, bowel, and kidney.

PURPOSE

This study aimed to assess the value of IMA levels as a diagnostic marker for neonatal hypoxic-ischemic encephalopathy (HIE).

METHODS

Sixty newborns who fulfilled 3 or more of the clinical and biochemical criteria and developed HIE as defined by Levene staging were included in our study as the asphyxia group. Neonates with congenital malformation, systemic infection, intrauterine growth retardation, low-birth weight, cardiac or hemolytic disease, family history of neurological diseases, congenital or perinatal infections, preeclampsia, diabetes, and renal diseases were excluded from the study. Sixty healthy neonates matched for gestational age and with no maternal history of illness, established respiration at birth, and an Apgar score ≥7 at 1 and 5 minutes were included as the control group. IMA was determined by double-antibody enzymelinked immunosorbent assay of a cord blood sample collected within 30 minutes after birth.

RESULTS

Cord blood IMA levels were higher in asphyxiated newborns than in controls (250.83±36.07 pmol/mL vs. 120.24±38.9 pmol/mL). Comparison of IMA levels by HIE stage revealed a highly significant difference among them (207.3±26.65, 259.28±11.68, 294.99±4.41 pmol/mL for mild, moderate, and severe, respectively). At a cutoff of 197.6 pmol/mL, the sensitivity was 84.5%, specificity was 86%, positive predictive value was 82.8%, negative predictive value was 88.3%, and area under the curve was 0.963 (P<0.001).

CONCLUSION

IMA levels can be a reliable marker for the early diagnosis of neonatal HIE and can be a predictor of injury severity.

Critical Shifts in Cerebral White Matter Lipid Profiles After Ischemic-Reperfusion Brain Injury in Fetal Sheep as Demonstrated by the Positive Ion Mode MALDI-Mass Spectrometry

Ischemic-reperfusion (I/R) injury to cerebral white matter during the perinatal period leads to long-term cognitive and motor disabilities in children. Immature white matter oligodendrocytes are especially vulnerable to metabolic insults such as those caused by hypoxic, ischemic, and reperfusion injury. Consequences include an impaired capacity of oligodendrocytes to generate and maintain mature lipid-rich myelin needed for efficient neuronal conductivity. Further research is needed to increase an understanding of the early, possibly reversible myelin-associated pathologies that accompany I/R white matter injury. This experiment characterized I/R time-dependent alterations in cerebral white matter lipid profiles in an established fetal sheep model. Fetal sheep (127 days gestation) were subjected to 30 min of bilateral carotid artery occlusion followed by 4 h (n = 5), 24 h (n = 7), 48 h (n = 3), or 72 h (n = 5) of reperfusion, or sham treatment (n = 5). Supraventricular cerebral white matter lipids were analyzed using the positive ionization mode matrix-assisted laser desorption/ionization mass spectrometry. Striking I/R-associated shifts in phospholipid (PL) and sphingolipid expression with a prominent upregulation of cardiolipin, phosphatidylcholine, phosphatidylinositol monomannoside, sphingomyelin, sulfatide, and ambiguous or unidentified lipids were observed to occur mainly at I/R-48 and normalized or suppressed responses at I/R-72. In fetal sheep, cerebral I/R caused major shifts in white matter myelin lipid composition favoring the upregulated expression of diverse PLs and sphingolipids which are needed to support neuronal membrane, synaptic, metabolic, and cell signaling functions.

Early identification of neonatal mild hypoxic-ischemic encephalopathy by amide proton transfer magnetic resonance imaging: A pilot study

PURPOSE

This study aimed to evaluate the amide proton transfer (APT) values in neonates with mild hypoxic-ischemic encephalopathy (HIE) using APT imaging.

METHOD

A total of 30 full-term neonates with mild HIE (16 males and 14 females; mean postnatal age 4.2 days, age range 2-7 days) and 12 normal neonates (six males and six females; mean postnatal age 3.3 days, age range 2-5 days) underwent conventional magnetic resonance imaging and APT imaging. APT measurements were performed in multiple regions of interest (ROIs) in the brain. APT values were statistically analyzed to assess for significant differences between the mild HIE and normal neonates in different regions of the brain, and correlation with neonatal gestational age.

RESULTS

In 30 neonates with mild HIE, 10% (3/30) of the HIE patients had normal conventional MRI. There were significant differences in APT values of the HIE group in bilateral caudate, bilateral thalamus, bilateral centrum semiovale and left globus pallidus/putamen (p < 0.05), and no statistical difference was observed in right globus pallidus/putamen (p = 0.051) and brainstem (p = 0.073) between the two groups. Furthermore, APT values in bilateral caudate, bilateral globus pallidus/putamen, bilateral thalamus, and brainstem regions (p < 0.05) exhibited positive linear correlations with gestational age in the control group, except for bilateral centrum semiovale (right: Pearson's r = 0.554, p = 0.062; left: Pearson's r = 0.561, p = 0.058). In the mild HIE groups, no significant correlation with gestational age was found in all regions.

CONCLUSIONS

APT imaging is a feasible and useful technique with diagnostic capability for neonatal HIE.

GSK-3β/mTORC1 Couples Synaptogenesis and Axonal Repair to Reduce Hypoxia Ischemia-Mediated Brain Injury in Neonatal Rats

Glycogen synthase kinase 3 beta (GSK-3β) plays an important role in neurological outcomes after brain injury. However, its roles and mechanisms in hypoxia-ischemia (HI) are unclear. Activation of mTOR complex 1 (mTORC1) has been proven to induce the synthesis of proteins associated with regeneration. We hypothesized that GSK-3β inhibition could activate the mTORC1 signaling pathway, which may reduce axonal injury and induce synaptic protein synthesis and functional recovery of synapses after HI. By analyzing a P7 rat model of cerebral HI and an in vitro ischemic (oxygen glucose deprivation) model, we found that GSK-3β inhibitors (GSK-3β siRNA or lithium chloride) activated mTORC1 signaling, leading to increased expression of synaptic proteins, including synapsin 1, PSD95, and GluR1, and the microtubule-associated protein Tau and decreased expression of the axonal injury-associated protein amyloid precursor protein. These changes contributed to attenuated axonal injury (decreased amyloid precursor protein staining and axonal loss by silver staining), improved electrophysiological properties of synapses, and enhanced spatial memory performance in the Morris water maze. However, inhibition of mTORC1 by rapamycin blocked the benefits induced by GSK-3β inhibition, suggesting that GSK-3β inhibition induces synaptogenesis and axonal repair via mTORC1 signaling, which may benefit neonatal rats subjected to HI.

Neuroprotective Care of Extremely Preterm Infants in the First 72 Hours After Birth

Birth at extremely low gestational ages presents a significant threat to infants' survival, health, development, and future well-being. After birth, a critical period of brain development must continue outside the womb. Neuro-supportive and neuroprotective family centered developmental care for and standardized care practices for extremely preterm infants have been shown to improve outcomes. Neuroprotective interventions must include a focus on the emotional connections of infants and their families. Being in skin-to-skin contact with the mother is the developmentally expected environment for all mammals and is especially important for supporting physiologic stability and neurodevelopment of preterm infants.

Neuroprotective effects of the new Na channel blocker rs100642 in global ischemic brain injury

INTRODUCTION

RS100642, a mexiletine analogue, is a novel sodium channel blocker with neuroprotective and antioxidant activities. The protectivity of RS100642, which has been shown against focal cerebral ischemia, was investigated in global cerebral ischemia in this study.

MATERIAL AND METHODS

Global cerebral ischemia was induced for five minutes in adult male Wistar Albino rats via the 4-vessel occlusion method. Intravenous administration of 1 mg/kg RS100642 following reperfusion for 30 min (RS100642 group) was compared with a sham treatment group (ischemia group) and nonischemized group (control) histologically based on morphology and caspase-3 immunohistochemistry, and biochemically based both on measurement of oxidative stress including malondialdehyde (MDA) levels, superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities and on assessment of apoptosis including caspase-3 and -8 activities and tumor necrosis factor α (TNF-α) levels at the end of 6 h.

RESULTS

While the RS100642 group had significantly lower MDA levels and higher SOD activities than the sham treatment group (p < 0.05), GPx and CAT activities of the RS100642 and sham treatment groups were similar (p > 0.05) and significantly lower than those of the controls (p < 0.05). Necrosis and caspase-3 activity and immunoreactivity in the RS100642 group were significantly lower than those in the sham treatment group (p < 0.05), while there was no significant difference between groups regarding caspase-8 and TNF-α (p > 0.05).

CONCLUSIONS

Na⁺ channel blockade by RS100642 has remarkable neuroprotective effects following global brain ischemia/reperfusion damage. Further research is required to determine the optimum dose and time of administration.

Inhibition of the PI3K/Akt signaling pathway impedes the restoration of neurological function following hypoxic-ischemic brain damage in a neonatal rabbit model

OBJECTIVE

Hypoxic-ischemic brain damage (HIBD), frequently occurring in infancy and childhood, is a major cause of mortality and severe neurologic impairment. This study was performed to examine the effect of the PI3K/Akt signaling pathway on HIBD in a neonatal rabbit model.

MATERIALS AND METHODS

Uterine artery occlusion was used to establish HIBD models in neonatal rabbits, which were then subjected to sham operation, dimethyl sulfoxide (2 mL) or LY294002 (inhibitor of PI3K/Akt signaling pathway, 6.4 μg/kg). Behavioral neurological assessment was performed in neonatal rabbits delivered by cesarean section, after which serum neuron-specific enolase (NSE) level and cerebral water content were determined. The level of cleaved caspase-3 level and apoptosis of neurons were observed by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. Furthermore, the expression of PI3K/Akt signaling pathway- and apoptosis-related factors was examined.

RESULTS

In neonatal rabbits, HIBD increased the fetal death rate; reduced neurological scores of posture, righting reflex, and deglutition reflex; elevated serum NSE levels, cerebral water content, cleaved caspase-3-positive expression in hippocampal CA1 region and apoptotic neurons; inactivated PI3K/Akt signaling pathway as well as reduced Bcl-2 expression and increased BAD and Bax expression. Notably, the treatment of LY294002 further aggravated neurological impairment in neonatal rabbits in response to HIBD.

CONCLUSION

Following the HIBD caused by intrauterine asphyxia, the LY294002 administered through auricular vein infusion into pregnant rabbits exacerbates neurological impairment of neonatal rabbits, suggesting that inhibition of PI3K/Akt signaling pathway may serve as a candidate therapeutic target for neurological recovery.

Rapid Alterations in Cerebral White Matter Lipid Profiles After Ischemic-Reperfusion Brain Injury in Fetal Sheep as Demonstrated by MALDI-Mass Spectrometry

BACKGROUND

Perinatal ischemia-reperfusion (I/R) injury of cerebral white matter causes long-term cognitive and motor disabilities in children. I/R damages or kills highly metabolic immature oligodendroglia via oxidative stress, excitotoxicity, inflammation, and mitochondrial dysfunction, impairing their capacity to generate and maintain mature myelin. However, the consequences of I/R on myelin lipid composition have not been characterized.

OBJECTIVE

This study utilized matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to assess alterations in cerebral supraventricular white matter myelin lipid profiles in a fetal sheep model of perinatal I/R.

METHODS

Fetal sheep (127 days gestation) were studied after 30 minutes of bilateral carotid artery occlusion followed by 4 (n = 5), 24 (n = 7), 48 (n = 3), or 72 (n = 5) hours of reperfusion, or sham treatment (n = 5). White matter lipids were analyzed by negative ion mode MALDI-MS.

RESULTS

Striking I/R-associated shifts in phospholipid and sphingolipid expression occurred over the 72-hour time course with most responses detected within 4 hours of reperfusion and progressing at the 48- and 72-hour points. I/R decreased expression of phosphatidic acid and phosphatidylethanol amine and increased phosphatidylinositol, sulfatide, and lactosylceramide.

CONCLUSIONS

Cerebral I/R in mid-gestation fetal sheep causes rapid shifts in white matter myelin lipid composition that may reflect injury, proliferation, or recovery of immature oligodendroglia.

Neonatal hypoxic-ischemic encephalopathy: emerging therapeutic strategies based on pathophysiologic phases of the injury

Neonatal hypoxic ischemic encephalopathy (HIE) is an important cause of neonatal death and disability. At present, there is no unified standard and specialized treatment method for neonatal HIE. In clinical practice, we have found that a gap remains between preclinical medical research and clinical application in the treatment of neonatal HIE. To promote an organic combination of preclinical research and clinical application, we propose the different phases as intervention targets, based on the pathophysiologic changes in phases I, II, and III of neonatal HIE; moreover, we suggest transformative medicine as a principle that may improve the therapeutic effect by blocking the progression of the disease to an irreversible stage. For instance, in phase I, mild hypothermia, free radical scavenger (erythropoietin, hydrogen-rich saline), excitatory amino acid receptor blocker, and neuroprotective agents should be administered to neonates with moderate/severe HIE; in phase II, following phase I treatment, anti-inflammatory agents, neuroprotective or nerve regeneration agents, and stem cell transplantation should be administered to patients; in phase III, anti-inflammatory agents, neuroprotective or nerve regeneration agents, and stem cell transplantation should be administered to patients. As soon as the patient's condition has stabilized, acupuncture, massage, and rehabilitation training should be performed. Following further study of stem cells, stem cell transplantation is expected to become the most promising therapeutic candidate for treatment of severe neonatal HIE with its sequelae.

Vitamin A bio-modulates apoptosis via the mitochondrial pathway after hypoxic-ischemic brain damage

Our previous studies demonstrated that vitamin A deficiency (VAD) can impair the postnatal cognitive function of rats by damaging the hippocampus. The present study examined the effects of retinoic acid (RA) on apoptosis induced by hypoxic-ischemic damage in vivo and in vitro, and investigated the possible signaling pathway involved in the neuroprotective anti-apoptotic effects of RA. Flow cytometry, immunofluorescence staining and behavioral tests were used to evaluate the neuroprotective and anti-apoptotic effects of RA. The protein and mRNA levels of RARα, PI3K, Akt, Bad, caspase-3, caspase-8, Bcl-2, Bax, and Bid were measured with western blotting and real-time PCR, respectively. We found impairments in learning and spatial memory in VAD group compared with vitamin A normal (VAN) and vitamin A supplemented (VAS) group. Additionally, we showed that hippocampal apoptosis was weaker in the VAN group than that in VAD group. Relative to the VAD group, the VAN group also had increased mRNA and protein levels of RARα and PI3K, and upregulated phosphorylated Akt/Bad levels in vivo. In vitro, excessively low or high RA signaling promoted apoptosis. Furthermore, the effects on apoptosis involved the mitochondrial membrane potential (MMP). These data support the idea that sustained VAD following hypoxic-ischemic brain damage (HIBD) inhibits RARα, which downregulates the PI3K/Akt/Bad and Bcl-2/Bax pathways and upregulates the caspase-8/Bid pathway to influence the MMP, ultimately producing deficits in learning and spatial memory in adolescence. This suggests that clinical interventions for HIBD should include suitable doses of VA.

Association between the use of magnesium sulfate as neuroprotector in prematurity and the neonatal hemodynamic effects

PURPOSE

Cerebral palsy is often associated with prematurity and magnesium sulfate (MgSO₄) has been used as a neuroprotector, with favorable results. However, its mechanism of action has not been fully elucidated. This study aimed to evaluate the association between MgSO₄ at the imminent premature delivery and neonatal hemodynamic effects.

MATERIALS AND METHODS

A cross-sectional study involving 94 newborns (NB) between 24 and 32 weeks at a Brazilian hospital was performed. Bivariate analysis between the use or the non-use of MgSO₄ and hemodynamic characteristics was performed, using the Chi-square test.

RESULTS

NB were evaluated between those who received MgSO₄ (27.7) and those who did not (72.3%). Normal heart rate was verified in 62.8% of NB, normal respiratory rate in 70.2%, and normal temperature in 22.3%. Oxygen saturation higher or equal than 95% was evidenced in 85.1% of NB, normal hemoglucotest in 74.5%, and hemoglobin greater or equal than 16.4 g/dL in 30.9%. Non-invasive ventilation was performed in 48.9% of NB, while 51.1% were submitted to endotracheal ventilation. There was no significance relation detected between the use of MgSO₄ and the hemodynamic characteristics.

CONCLUSIONS

MgSO₄ does not appear to influence hemodynamic factors as a cause of the neuroprotection in premature NB.

Measurement of Lactate Content and Amide Proton Transfer Values in the Basal Ganglia of a Neonatal Piglet Hypoxic-Ischemic Brain Injury Model Using MRI

BACKGROUND AND PURPOSE

As amide proton transfer imaging is sensitive to protein content and intracellular pH, it has been widely used in the nervous system, including brain tumors and stroke. This work aimed to measure the lactate content and amide proton transfer values in the basal ganglia of a neonatal piglet hypoxic-ischemic brain injury model by using MR spectroscopy and amide proton transfer imaging.

MATERIALS AND METHODS

From 58 healthy neonatal piglets (3-5 days after birth; weight, 1-1.5 kg) selected initially, 9 piglets remained in the control group and 43 piglets, in the hypoxic-ischemic brain injury group. Single-section amide proton transfer imaging was performed at the coronal level of the basal ganglia. Amide proton transfer values of the bilateral basal ganglia were measured in all piglets. The ROI of MR spectroscopy imaging was the right basal ganglia, and the postprocessing was completed with LCModel software.

RESULTS

After hypoxic-ischemic insult, the amide proton transfer values immediately decreased, and at 0-2 hours, they remained at their lowest level. Thereafter, they gradually increased and finally exceeded those of the control group at 48-72 hours. After hypoxic-ischemic insult, the lactate content increased immediately, was maximal at 2-6 hours, and then gradually decreased to the level of the control group. The amide proton transfer values were negatively correlated with lactate content (r = -0.79, P < .05).

CONCLUSIONS

This observation suggests that after hypoxic-ischemic insult, the recovery of pH was faster than that of lactate homeostasis.

Ataxia in children: early recognition and clinical evaluation

Background

Ataxia is a sign of different disorders involving any level of the nervous system and consisting of impaired coordination of movement and balance. It is mainly caused by dysfunction of the complex circuitry connecting the basal ganglia, cerebellum and cerebral cortex.

A careful history, physical examination and some characteristic maneuvers are useful for the diagnosis of ataxia. Some of the causes of ataxia point toward a benign course, but some cases of ataxia can be severe and particularly frightening.

Methods

Here, we describe the primary clinical ways of detecting ataxia, a sign not easily recognizable in children. We also report on the main disorders that cause ataxia in children.

Results

The causal events are distinguished and reported according to the course of the disorder: acute, intermittent, chronic-non-progressive and chronic-progressive.

Conclusions

Molecular research in the field of ataxia in children is rapidly expanding; on the contrary no similar results have been attained in the field of the treatment since most of the congenital forms remain fully untreatable. Rapid recognition and clinical evaluation of ataxia in children remains of great relevance for therapeutic results and prognostic counseling.

The association between pro- and anti-inflammatory cytokine polymorphisms and periventricular leukomalacia in newborns with hypoxic-ischemic encephalopathy

Background

Periventricular leukomalacia (PVL) is a frequent consequence of hypoxic-ischemic injury. Functional cytokine gene variants that result in altered production of inflammatory (tumor necrosis factor-alpha [TNF-α] and interleukin-1beta [IL-1β]) or anti-inflammatory (interleukin-10 [IL-10]) cytokines may modify disease processes, including PVL.

Objective

The aim of this study was to evaluate if there is a relationship between the two proinflammatory polymorphisms (TNF-α-1031T/C and IL-1β-511C/T) and the anti-inflammatory polymorphism IL-10-1082G/A and PVL risk in Brazilian newborns with and without this injury.

Materials and methods

A cross-sectional case-control study performed at the Neonatal Intensive Care Unit of the Children’s Hospital and Maternity of the São José do Rio Preto Medical School (FAMERP). Fifty preterm and term newborns were examined as index cases and 50 term newborns as controls, of both sexes for both groups. DNA was extracted from peripheral blood leukocytes, and the sites that encompassed the three polymorphisms were amplified by polymerase chain reaction-restriction fragment length polymorphism.

Results

Gestational age ranged from 25 to 39 weeks, in the case group, and in the control group it ranged from 38 to 42.5 weeks (P<0.0001). Statistically significant association was found between TNF-α-1031T/C high expression genotype TC (odds ratio [OR], 2.495; 95% confidence interval [CI], 1.10–5.63; P=0.043) as well as between genotypes (TC + CC) (OR, 2.471; 95% CI, 1.10–5.55; P=0.044) and risk of PVL. Statistically significant association was found between IL-1β-511C/T high expression genotypes (CT + TT) (OR, 23.120; 95% CI, 1.31–409.4; P=0.003) and risk of PVL. Statistically significant association between IL-10-1082G/A high expression genotype GG (OR, 0.07407; 95% CI, 0.02–0.34; P<0.0001) as well as between IL-10-1082G high expression allele (OR, 0.5098; 95% CI, 0.29–0.91; P=0,030) and PVL reduced risk was observed. There was a statistically significant association between TC/CT/GA genotype combination and the risk of PVL (OR, 6.469; 95% CI, 2.00–20.92; P=0.001).

Conclusion

There is evidence of an association between the polymorphisms TNF-α-1031T/C, IL-1β-511C/T, and IL-10-1082G/A and PVL risk in this Brazilian newborn population studied.

Neonatal hypoxic ischemic encephalopathy-related biomarkers in serum and cerebrospinal fluid

Neonatal hypoxic ischemic encephalopathy (HIE) is a common disease caused by perinatal asphyxia, a major cause of neonatal death, neurological behavior, and long-term disability. Currently, the diagnosis and prognosis of neonatal HIE are based on nervous system clinical manifestations, imaging and electrophysiological examination. These take time and late diagnosis allows brain injury to occur in newborns, so that infants of many brain injury missed the best treatment time, left with varying degrees of neurological sequelae. The use of biomarkers to monitor brain injury and evaluate neuroprotective effects might allow the early intervention and treatment of neonatal HIE to reduce mortality rates. This study reviewed the mechanism of neonatal hypoxic ischemic encephalopathy in relation to numerous brain-related biomarkers including NSE, S-100β, GFAP, UCH-L1, Tau protein, miRNA, LDH, and CK-BB. In early diagnosis of neonatal HIE, S-100β and activin A seems to be better biomarkers. Biomarkers with the greatest potential to predict long-term neurologic handicap of neonates with HIE are GFAP and UCH-L1 and when combined with other markers or brain imaging can increase the detection rate of HIE. Tau protein is a unique biological component of nervous tissues, and might have value for neonatal HIE diagnosis. Combination of more than two biological markers should be a future research direction.

Comparing 3T T1-weighted sequences in identifying hyperintense punctate lesions in preterm neonates

BACKGROUND AND PURPOSE

The loss of contrast on T1-weighted MR images at 3T may affect the detection of hyperintense punctate lesions indicative of periventricular leukomalacia in preterm neonates. The aim of the present study was to determine which 3T T1-weighted sequence identified the highest number of hyperintense punctate lesions and to explore the relationship between the number of hyperintense punctate lesions and clinical outcome.

MATERIALS AND METHODS

The presence of hyperintense punctate lesions was retrospectively evaluated in 200 consecutive preterm neonates on 4 axial T1-weighted sequences: 3-mm inversion recovery and spin-echo and 1- and 3-mm reformatted 3D-fast-field echo. Statistically significant differences in the number of hyperintense punctate lesions were evaluated by using a linear mixed-model analysis. Logistic regression analysis was used to assess the relation between the number of hyperintense punctate lesions and neuromotor outcome at 3 months.

RESULTS

Thirty-one neonates had at least 1 hyperintense punctate lesion indicative of periventricular leukomalacia in at least 1 of the 4 sequences. The 1-mm axial reformatted 3D-fast-field echo sequence identified the greatest number of hyperintense punctate lesions (P < .001). No statistically significant differences were found among the 3-mm T1-weighted sequences. The greater number of hyperintense punctate lesions detected by the 1-mm reformatted T1 3D-fast-field echo sequence in the central region of the brain was associated with a worse clinical outcome.

CONCLUSIONS

At 3T, the 1-mm axial reformatted T1 3D-fast-field echo sequence identified the greatest number of hyperintense punctate lesions in the central region of preterm neonate brains, and this number was associated with neuromotor outcome.

Proteomic analysis of immature rat pups brain in response to hypoxia and ischemia challenge

Hypoxia and ischemia significantly affects perinatal brain development, even worse in preterm infants. However, the details of the mechanism leading to permanent brain damage after hypoxia-ischemia attack have not been fully elucidated. Proteomics could provide insight into the potential mechanism and help to promote the clinical treatment. In this study, quantitative analysis was performed 24 hours after hypoxia-ischemia using liquid-chromatography mass spectrometry coupled to label-free analysis. Compared to control, 193 proteins were present only in hypoxic-ischemic group. In addition, 34 proteins were more than 2 folds up-regulated and 14 proteins were more than 2 folds down-regulated in hypoxia-ischemia group. Gene Ontology database showed that the majority of differentially expressed proteins comprised mitochondrial proteins et al. Molecular function analysis revealed that the majority of proteins were involved in ion binding et al. Biological process analysis showed that the majority of proteins were involved in response to organic substance et al. STRING 9.0 software analysis were used to explore the complex interactions existed among the proteins. Western blot were used to verify the fold changes of some proteins-microtubule-associated protein 2 and microtubule-associated protein tau. This novel study performed a full-scale screening of the proteomics research in hypoxic-ischemic brain damage of immature rat.

Molecular pathogenesis of myocardial remodeling and new potential therapeutic targets in chronic heart failure

It is well known that the natural history of chronic heart failure (CHF),regardless of age and aetiology,is characterized by progressive cardiac dysfunction refractory to conventional cardiokinetic, diuretic and peripheral vasodilator therapy. Several previous studies, both in animals and humans, showed that the key pathogenetic element of CHF negative clinical evolution is constituted by myocardial remodeling. This is a complex pathologic process of ultrastructural rearrangement of the heart induced by various neuro-humoral factors released by cardiac fibrocells in response to biomechanical stress connected to chronic haemodynamic overload. Typical features of myocardial remodeling are represented by cardiomyocytes hypertrophy and apoptosis, extracellular matrix alterations, mesenchymal fibrotic and phlogistic processes and by cardiac gene expression modifications with fetal genetic program reactivation. In the last years, increasing knowledge of subtle molecular and cellular mechanisms involved in myocardial remodeling has led to the discovery of some new potential therapeutic targets capable of inducing its regression. In this paper our attention is focused on the possible use of antiapoptotic and antifibrotic agents, and on the fascinating perspectives offered by the development of myocardial gene therapy and, in particular, by myocardial regenerative therapy.

Pathophysiological role of inflammatory molecules in paediatric ischaemic brain injury

Ischaemic stroke is one of the major causes of death and lifelong disability also in the paediatric population. Strong scientific effort has been put to clarify the pathophysiology of this disease in adults. However, only few studies have been performed in children. Preliminary results indicate that pathophysiological processes might differently affect the poststroke neuronal injury in neonates as compared to children. During the neural development, selective molecular mechanisms might be differently triggered by an ischaemic insult, thus potentially resulting in defined postischaemic clinical outcomes. Basic research studies in neonatal animal models of cerebral ischaemia have recently shown a potential role of soluble inflammatory molecules (such as cytokines, chemokines and oxidants) as pivotal players of neuronal injury in both perinatal and childhood ischaemic stroke. Although larger clinical trials are still needed to confirm these preliminary results, the potential benefits of selective treatments targeting inflammation in perinatal asphyxia encephalopathy might represent a promising investigation field in the near future. In this review, we will update evidence on the pathophysiological role of soluble inflammatory mediators in neonatal and childhood ischaemic stroke. Recent evidence on potential anti-inflammatory treatments to improve paediatric stroke prognosis will be discussed.