Neonatal Ischemic Brain Injury Research Articles

Group III metabotropic glutamate receptors: guardians against excitotoxicity in ischemic brain injury, with implications for neonatal contexts

AbstractThe group III metabotropic glutamate receptors (mGluRs), comprising mGluR4, mGluR6, mGluR7, and mGluR8, offer neuroprotective potential in mitigating excitotoxicity during ischemic brain injury, particularly in neonatal contexts. They are G-protein coupled receptors that inhibit adenylyl cyclase and reduce neurotransmitter release, mainly located presynaptically and acting as autoreceptors. This review aims to examine the differential expression and function of group III mGluRs across various brain regions such as the cortex, hippocampus, and cerebellum, with a special focus on the neonatal stage of development. Glutamate excitotoxicity plays a crucial role in the pathophysiology of brain ischemia in neonates. While ionotropic glutamate receptors are traditional targets for neuroprotection, their direct inhibition often leads to severe side effects due to their critical roles in normal neurotransmission and synaptic plasticity. Group III mGluRs provide a more nuanced and potentially safer approach by modulating rather than blocking glutamatergic transmission. Their downstream signaling cascade results in the regulation of intracellular calcium levels, neuronal hyperpolarization, and reduced neurotransmitter release, effectively decreasing excitotoxic signaling without completely suppressing essential glutamatergic functions. Importantly, the neuroprotective effects of group III mGluRs extend beyond direct modulation of glutamate release influencing glial cell function, neuroinflammation, and oxidative stress, all of which contribute to secondary injury cascades in brain ischemia. This comprehensive analysis of group III mGluRs multifaceted neuroprotective potential provides valuable insights for developing novel therapeutic strategies to combat excitotoxicity in neonatal ischemic brain injury.

Математичний аналіз оцінки рівня гомоцистеїну в сироватці крові як предиктора розвитку менінгіту в новонароджених із гіпоксично-ішемічним ураженням центральної нервової системи

The main reason for the development of neonatal hypoxic-ischemic encephalopathy is inadequate oxygen supply to brain tissue, due to a combination of hypoxemia and ischemia. Hypoxia leads to disruption of oxidative processes and the development of acidosis, decreased energy balance of the cell, an excess of excitatory neurotransmitters, impaired metabolism of glia and neurons. Excess homocysteine can also induce a cascade of events in hippocampal neurons, producing in response to acute bacterial meningitis and accumulating in the central nervous system, reaching neurotoxic levels. Understanding the pathological mechanisms of neonatal ischemic Brain injury will help optimize treatment and reduce the degree of hypoxic-ischemic damage. The purpose of the study was to assess the level of homocysteine in the blood serum as a predictor of the development of meningitis in newborns with hypoxic-ischemic lesions of the central nervous system using mathematical analysis. Material and methods. The following research methods were used in the course of work: clinical-anamnestic (subjective and objective examination data), laboratory (biochemical, immunological method, enzyme-linked immunosorbent assay method), instrumental (neurosonography), methods of mathematical statistics. Statistical processing of all obtained results performed on a personal computer using the license software package Statistics 13.0 (StatSoftInc, serial number JPZ8041382130ARCN10-J) and MS Excel. We used the following methods of statistical analysis in the study: descriptive statistics, parametric and nonparametric methods of comparison of mean groups, correlation analysis, multiple linear and logistic regression analysis, utility statistics: odds ratio, relative risk, ROC analysis. Results and discussion. The relationship between homocysteine and hemoglobin and gestational age was found to be direct and reversed with bilirubin. The use of linear regression analysis allowed predicting the value of homocysteine by known values of one or more predictor variables. A ROC analysis was performed to assess the diagnostic significance of homocysteine levels as an indicator of oxidative stress and to express it in some integral indicators. Conclusion. The analysis showed that high levels of homocysteine in newborns can be considered as a statistically significant indicator of oxidative stress and a predictor of meningitis in premature infants. The probability of developing meningitis in premature infants with high homocysteine levels is 1.15 times higher than in full-term infants with central nervous system lesions (p> 0.05) and 8 times higher (p <0.05) than in full-term relatively healthy infants

Brain microstructural development in neonates with critical congenital heart disease: An atlas-based diffusion tensor imaging study.

BackgroundBrain microstructural maturation progresses rapidly in the third trimester of gestation and first weeks of life, but typical microstructural development may be influenced by the presence of critical congenital heart disease (CHD).ObjectiveThe aim of this study was to investigate the pattern of white matter (WM) microstructural development in neonates with different types of critical CHD. The secondary aim was to examine whether there is an association between WM microstructural maturity and neonatal ischemic brain injury.MethodsFor this prospective, longitudinal cohort study, 74 term born neonates underwent diffusion tensor imaging (DTI) before (N = 56) and after (N = 71) cardiac surgery performed <30 days of life for transposition of the great arteries (TGA), single ventricle physiology with aortic arch obstruction (SVP-AO), left- (LVOTO) or right ventricle outflow tract obstruction (RVOTO). Microstructural integrity was investigated by fractional anisotropy (FA) and by mean diffusivity (MD) in 16 white matter (WM) structures in three WM regions with correction for postmenstrual age. Ischemic brain injury was defined as moderate-severe white matter injury or stroke.ResultsBefore cardiac surgery, the posterior parts of the corona radiata and internal capsule showed significantly higher FA and lower MD compared to the anterior parts. Centrally-located WM structures demonstrated higher FA compared to peripherally-located structures. Neonates with TGA had higher FA in projection-, association- and commissural WM before surgery, when compared to other CHD groups. Neonates with LVOTO showed lower preoperative MD in these regions, and neonates with SVP-AO higher MD. Differences in FA/MD between CHD groups were most clear in centrally located WM structures. Between CHD groups, no differences in postoperative FA/MD or in change from pre- to postoperative FA/MD were seen. Neonatal ischemic brain injury was not associated with pre- or postoperative FA/MD.ConclusionsCollectively, these findings revealed brain microstructural WM development to follow the same organized pattern in critical CHD as reported in healthy and preterm neonates, from posterior-to-anterior and central-to-peripheral. Neonates with TGA and LVOTO showed the most mature WM microstructure before surgery and SVP-AO the least mature. Degree of WM microstructural immaturity was not associated with ischemic brain injury.

Myeloid cell IRF4 signaling protects neonatal brains from hypoxic ischemic encephalopathy

Interferon regulatory factor 4 (IRF4), a transcription factor recognized as a key regulator of lymphoid and myeloid cell differentiation, has recently been recognized as a critical mediator of macrophage activation. Previously we have reported that IRF4 signaling is closely correlated with anti-inflammatory polarization of microglia in adult mice after stroke. However, IRF4's role in the inflammatory response in the immature brain is unknown. Using a model of neonatal hypoxic ischemic encephalopathy (HIE) we investigated the regulatory action of IRF4 signaling in the activation of microglia and monocytes after HIE. IRF4 myeloid cell conditional knockout (CKO) postnatal day 10 (P10) male pups were subjected to a 60-min hypoxic-ischemic insult by the Rice-Vanucci model (RVM). IRF4 gene floxed mice (IRF4fl/fl) were used as controls. Brain atrophy and behavioral deficits were measured 7 days after HIE. Flow cytometry (FC) was performed to examine central (microglial activation) and peripheral immune cell responses by both cell membrane and intracellular marker staining. Serum levels of cytokines were determined by ELISA. The results showed that IRF4 CKO pups had increased tissue loss and worse behavioral deficits than IRF4fl/fl mice seven days after HIE. FC demonstrated significantly more infiltration of monocytes and neutrophils in the ischemic brains of IRF4 CKO vs IRF4fl/fl pups. IRF4 CKO ischemic microglia were more pro-inflammatory as evidenced by higher expression of the pro-inflammatory marker CD68, and increased intracellular TNFα and IL-1β levels compared to controls. In addition, IRF4 deletion from myeloid cells resulted in increased levels of circulating pro-inflammatory cytokines and higher endothelial MMP9 expression after HIE. These data indicate that IRF4 signaling in myeloid cells plays a regulatory role in neuroinflammation and that deletion of myeloid IRF4 is detrimental to HIE injury, suggesting that IRF4 could serve as a potential therapeutic target for neonatal ischemic brain injury.

Absolute lymphocyte and neutrophil counts in neonatal ischemic brain injury.

Objectives:This study aimed to identify differences in absolute neutrophils, lymphocytes, and neutrophil-to-lymphocyte ratio between neonates with two forms of ischemic brain injury, hypoxic-ischemic encephalopathy, and acute ischemic stroke, compared to controls. We also aimed to determine whether this neutrophil/lymphocyte response pattern is associated with disease severity or is a consequence of the effects of total-body cooling, an approved treatment for moderate-to-severe hypoxic-ischemic encephalopathy.Methods:A retrospective chart review of 101 neonates with hypoxic-ischemic encephalopathy + total-body cooling (n = 26), hypoxic-ischemic encephalopathy (n = 12), acute ischemic stroke (n = 15), and transient tachypnea of the newborn (n = 48) was conducted; transient tachypnea of the newborn neonates were used as the control group. Absolute neutrophil count and absolute lymphocyte count at three time-intervals (0–12, 12–36, and 36–60 h after birth) were collected, and neutrophil-to-lymphocyte ratio was calculated.Results:Hypoxic-ischemic encephalopathy + total-body cooling neonates demonstrated significant time-interval-dependent changes in absolute lymphocyte count and neutrophil-to-lymphocyte ratio levels compared to transient tachypnea of the newborn and acute ischemic stroke patients. Pooled analysis of absolute lymphocyte count for neonates with acute ischemic stroke and hypoxic-ischemic encephalopathy (not hypoxic-ischemic encephalopathy + total-body cooling) revealed that absolute lymphocyte count changes occurring at 0–12 h are likely due to disease progression, rather than total-body cooling treatment.Conclusion:These data suggest that the neutrophil/lymphocyte response is modulated following neonatal ischemic brain injury, representing a possible target for therapeutic intervention. However, initial severity of hypoxic-ischemic encephalopathy among these patients could also account for the observed changes in the immune response to injury. Thus, additional work to clarify the contributions of cooling therapy and disease severity to neutrophil/lymphocyte response following hypoxic-ischemic encephalopathy in neonates is warranted.

Future perspectives of cell therapy for neonatal hypoxic-ischemic encephalopathy.

Neonatal ischemic brain injury causes permanent motor-deficit cerebral palsy. Hypoxic-ischemic encephalopathy (HIE) is a very serious condition that can result in death and disability. In 1997, we reported that irreversible neuronal cell damage is induced by the elevation of intracellular Ca ion concentration that has occurred in sequence after excess accumulation of the excitatory neurotransmitter glutamate during ischemia. We also reported that hypothermia was effective in treating ischemic brain damage in rats by suppressing energy loss and raising intracellular Ca ion concentration. Following the 2010 revised International Liaison Committee on Resuscitation guideline, our group developed the Guideline for the treatment of Hypothermia in Japan, and we started online case registry in January 2012. However, therapeutic hypothermia must be initiated within the first 6 h after birth. By contrast, cell therapy may have a much longer therapeutic time window because it might reduce apoptosis/oxidative stress and enhance the regenerative process. In 2014, we administered autologous umbilical cord blood stem cell (UCBC) therapy for neonatal HIE, for the first time in Japan. We enrolled five full-term newborns with moderate-to-severe HIE. Our autologous UCBC therapy is leading to new protocols for the prevention of ischemic brain damage.

Promoting neuroregeneration after perinatal arterial ischemic stroke: neurotrophic factors and mesenchymal stem cells.

Newborns suffering from perinatal arterial ischemic stroke (PAIS) are at risk of neurodevelopmental problems. Current treatment options for PAIS are limited and mainly focus on supportive care, as presentation of PAIS is beyond the time window of current treatment strategies. Therefore, recent focus has shifted to interventions that stimulate regeneration of damaged brain tissue. From animal models, it is known that the brain increases its neurogenic capability after ischemic injury, by promoting neural cell proliferation and differentiation. However, neurogenesis is not maintained at the long term, which consequently impedes full repair leading to adverse consequences later in life. Boosting neuroregeneration of the newborn brain using treatment with neurotrophic factors and/or mesenchymal stem cells (MSCs) may be promising novel therapeutic strategies to improve neurological prospects and quality of life of infants with PAIS. This review focuses on effectiveness of neurotrophic growth factors, including erythropoietin, brain-derived neurotrophic factor, vascular endothelial growth factor, glial-derived neurotrophic factor, and MSC therapy, in both experimental neonatal stroke studies and first clinical trials for neonatal ischemic brain injury.

Neuroprotective effects of orientin on oxygen-glucose deprivation/reperfusion-induced cell injury in primary culture of rat cortical neurons.

Orientin (luteolin-8-C-glucoside) is a phenolic compound found abundantly in millet, juice, and peel of passion fruit and has been shown to have antioxidant properties. In the present study, we explored the effects of orientin on oxygen-glucose deprivation/reperfusion (OGD/RP)-induced cell injury in primary culture of rat cortical neurons using an in vitro model of neonatal ischemic brain injury. The reduced cell viability and elevated lactate dehydrogenase leakage were observed after OGD/RP exposure, which were then reversed by orientin (10, 20, and 30 µM) pretreatment in a dose-dependent manner. Additionally, OGD/RP treatment resulted in significant oxidative stress, accompanied by enhanced intracellular reactive oxygen species (ROS) generation, and obvious depletion in the activities of intracellular Mn-superoxide dismutase, catalase, and glutathione peroxidase antioxidases. However, these effects were dose dependently restored by orientin pretreatment. We also found that orientin pretreatment dose dependently suppressed [Ca2+]i increase and mitochondrial membrane potential dissipation caused by OGD/RP in primary culture of rat cortical neurons. Western blot analysis showed that OGD/RP exposure induced a distinct decrease of Bcl-2 protein and a marked elevation of Bax, caspase-3, and cleaved caspase-3 proteins; whereas these effects were dose dependently reversed by orientin incubation. Both the caspase-3 activity and the apoptosis rate were increased under OGD/RP treatment, but was then dose dependently down-regulated by orientin (10, 20, and 30 µM) incubation. Moreover, orientin pretreatment dose dependently inhibited OGD/RP-induced phosphorylation of JNK and ERK1/2. Notably, JNK inhibitor SP600125 and ERK1/2 inhibitor PD98059 also dramatically attenuated OGD/RP-induced cell viability loss and ROS generation, and further, orientin failed to protect cortical neurons with the interference of JNK activator anisomycin or ERK1/2 activator FGF-2. Taken together, these results demonstrated that orientin has significant neuroprotective effects against OGD/RP-induced cell injury via JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons. Impact statement Orientin has been used in traditional eastern medicine and reported to possess antioxidant properties. However, the effects of orientin on neonatal ischemic brain injury and the underlying mechanisms involved have not been studied. Our results showed that orientin exerts significant neuroprotective effects on cell injury caused by oxygen-glucose deprivation/reperfusion via the JNK and ERK1/2 signaling pathways in primary culture of rat cortical neurons, implying the potential therapeutic application of orientin via the suppression of oxidative stress and cell apoptosis. This research suggested that orientin may be used as a therapeutic and preventive option for newborn cerebral ischemia/reperfusion injury.

Mesenchymal stem cells attenuate MRI-identifiable injury, protect white matter, and improve long-term functional outcomes after neonatal focal stroke in rats.

Cell therapy has emerged as a potential treatment for many neurodegenerative diseases including stroke and neonatal ischemic brain injury. Delayed intranasal administration of mesenchymal stem cells (MSCs) after experimental hypoxia-ischemia and after a transient middle cerebral artery occlusion (tMCAO) in neonatal rats has shown improvement in long-term functional outcomes, but the effects of MSCs on white matter injury (WMI) are insufficiently understood. In this study we used longitudinal T2-weighted (T2W) and diffusion tensor magnetic resonance imaging (MRI) to characterize chronic injury after tMCAO induced in postnatal day 10 (P10) rats and examined the effects of delayed MSC administration on WMI, axonal coverage, and long-term somatosensory function. We show unilateral injury- and region-dependent changes in diffusion fraction anisotropy 1 and 2 weeks after tMCAO that correspond to accumulation of degraded myelin basic protein, astrocytosis, and decreased axonal coverage. With the use of stringent T2W-based injury criteria at 72 hr after tMCAO to randomize neonatal rats to receive intranasal MSCs or vehicle, we show that a single MSC administration attenuates WMI and enhances somatosensory function 28 days after stroke. A positive correlation was found between MSC-enhanced white matter integrity and functional performance in injured neonatal rats. Collectively, these data indicate that the damage induced by tMCAO progresses over time and is halted by administration of MSCs. © 2016 Wiley Periodicals, Inc.

Iron metabolism, oxidative stress, and neonatal brain injury.

The brain injury associated with neonatal hypoxia ischemia (HI) is a major contributor to neonatal mortality and neurodevelopment retardation. Approximately 30–40% of infants with brain injury will die and 20–40% of survivors will develop significant neurological disorders and lifelong disability, such as cerebral palsy, seizures, visual impairment, mental retardation, learning impairment and epilepsy. Preterm birth is a high risk factor for neonatal brain injury. In the U.S., nearly 12% of babies are born preterm, and care of preterm infants accounts for more than half of pediatric health care dollars spent (Juul and Ferriero, 2014). A greater understanding of the complex mechanisms that result in neonatal hypoxia ischemic brain injury is the key to developing new protective therapeutics.

Stem cells for neonatal stroke- the future is here.

STEM CELLS In recent years stem cell therapy has emerged as a potential treatment for neonatal ischemic brain injury. The efficacy of cellbased therapies in restoring damaged brain tissue has been tested in a multitude of models for different CNS diseases. Several different stem and progenitor cell populations have been utilized as cell-based therapy, including neural stem cells, embryonic stem cells, human umbilical cord blood cells (HUBCs), hematopoietic stem and progenitor cells, and mesenchymal stem cells (MSCs). Most stem cell types appear to enhance recovery to some extent (Pimentel-Coelho and Mendez-Otero, 2010). However, because of their low immunogenicity, availability and positive results obtained from preclinical studies, MSCs are a particularly promising candidate to repair the devastating effects that are associated with neonatal stroke. MSCs were first isolated and identified in bone marrow, but can now be isolated from many tissues, including adipose tissue, muscle, skin and extraembryonic tissues like the placenta, umbilical cord and Wharton’s jelly. The latter sources are of particular interest for neonates that experience an ischemic event around the time of birth, at which time cells can be harvested and transplanted from an autologous source. MSCs derived from different sources have slightly different characteristics, but as of yet it is unknown whether this influences their therapeutic potential. Our group and others have shown that administration of MSCs reduces lesion volume, provides positive effects on the white matter and improves motor function (van Velthoven et al., 2012). Numerous studies have been done under the premise that transplanted stem cells contribute to brain repair by directly replacing damaged or lost tissue. While there is evidence that transplanted cells undergo differentiation toward neuronal lineages, improved outcomes have been observed even when survival of transplanted cells is low and engrafted cells are absent. This suggests that rather than replacing damaged cells, transplanted cells may improve outcome via indirect mechanisms. For example, MSCs have been shown to secrete many factors that can influence important processes like apoptosis, neurogenesis, angiogenesis and synaptogenesis.

Automated Core–Penumbra Quantification in Neonatal Ischemic Brain Injury

Neonatal hypoxic-ischemic brain injury (HII) and arterial ischemic stroke (AIS) result in irreversibly injured (core) and salvageable (penumbral) tissue regions. Identification and reliable quantification of salvageable tissue is pivotal to any effective and safe intervention. Magnetic resonance imaging (MRI) is the current standard to distinguish core from penumbra using diffusion-perfusion mismatch (DPM). However, subtle MR signal variations between core-penumbral regions make their visual delineation difficult. We hypothesized that computational analysis of MRI data provides a more accurate assessment of core and penumbral tissue evolution in HII/AIS. We used two neonatal rat-pup models of HII/AIS (unilateral and global hypoxic-ischemia) and clinical data sets from neonates with AIS to test our noninvasive, automated computational approach, Hierarchical Region Splitting (HRS), to detect and quantify ischemic core-penumbra using only a single MRI modality (T2- or diffusion-weighted imaging, T2WI/DWI). We also validated our approach by comparing core-penumbral images (from HRS) to DPM with immunohistochemical validation of HII tissues. Our translational and clinical data results showed that HRS could accurately and reliably distinguish the ischemic core from penumbra and their spatiotemporal evolution, which may aid in the vetting and execution of effective therapeutic interventions as well as patient selection.

Pretreatment with the monoacylglycerol lipase inhibitor URB602 protects from the long-term consequences of neonatal hypoxic–ischemic brain injury in rats

The endocannabinoids are emerging as natural brain protective substances that exert potentially beneficial effects in several neurological disorders by virtue of their hypothermic, immunomodulatory, vascular, antioxidant, and antiapoptotic actions. This study was undertaken to assess whether preventing the deactivation of the endocannabinoid 2-arachidonoylglycerol (2-AG) with the monoacylglycerol lipase (MAGL) inhibitor URB602 can provide neuroprotective effects in hypoxia-ischemia (HI)-induced brain injury. URB602 was administered into the right lateral ventricle 30 min before 7-day-old pup rats were subjected to HI. The neuroprotective effect was evaluated on postnatal day (PN) 14 or at adulthood (PN80) using behavioral and histological analyses. Activated caspase-3 expression and propidium iodide labeling were assessed as indexes of apoptotic and necrotic cell death, respectively. Pretreatment with URB602 reduced apoptotic and necrotic cell death, as well as the infarct volume measured at PN14. At adulthood, URB602-treated HI animals performed better at the T-maze and the Morris maze, and also showed a significant reduction of brain damage. These results demonstrate that a pretreatment with URB602 significantly reduces brain damage and improves functional outcome, indicating that endocannabinoid-degrading enzymes may represent an important target for neuroprotection in neonatal ischemic brain injury.

Neonatal ischemic brain injury: what every radiologist needs to know

We present a pictorial review of neonatal ischemic brain injury and look at its pathophysiology, imaging features and differential diagnoses from a radiologist's perspective. The concept of perinatal stroke is defined and its distinction from hypoxic-ischemic injury is emphasized. A brief review of recent imaging advances is included and a diagnostic approach to neonatal ischemic brain injury is suggested.

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.

Effects of basic fibroblast growth factor on neurogenesis in the subventricular zone of 3-day-old rats following brain ischemia

Objective To investigate the effects of exogenous basic fibroblast growth factor (bFGF) on neurogenesis in the subventricular zone (SVZ) of 3-day-old rats following brain ischemia. Methods Seventy-two brain ischemia models of 3-day-old SD rats were established by ligating bilateral common carotid artery. The models were divided into treatment group with 10 ng/g bFGF injection and the control group with saline. Another 36 rats underwent operation without ischemia served as sham-operate group. Proliferating cells were labeled by bromodeoxyuridine (BrdU) through intraperitoneal injection in a cumulative protocol. Rats were killed at 4, 7 and 14 days after ischemic injury. Immunofluoreseence assays, Western blot and real-time PCR were used to observe cellular changes, including the protein expression of nestin, Tuj1, glial fibrillary acidic protein (GFAP) and NG2, and also their mRNA expression in SVZ, respectively. Results (1) Immunofluorescence assay showed that the number of BrdU1/nestin+ cells in SVZ of treatment group was the highest at day 7 after operation [(48. 7±5.9)/field], higher than those in control [(32. 2±3. 1)/field] and sham-operate group [(17.3±1.6)/field] (P<0. 01). The number of BrdU+/Tuj1+ cells, BrdU+/ GFAP+ cells and BrdU+/NG2+ cells in SVZ of treatment group were highest at day 14 after brain ischemia [(92.6±9.7) ,(58.2±6.1) ,(57.3±5.4)/field, respectively], higher than those in control [(65. 8±7. 1), (42. 1 ± 4. 4), (37.8 ± 3. 2)/field, respectively] and sham-operate group [(35.3± 3. 1), (33.6± 3.4), (22.4 ± 2. 1)/field, respectively] (P<0. 01 ). (2) Western blot and real-time PCR analysis found that the expressions of nestin protein and mRNA peaked on day 7, and the expressions of Tuj1, GFAP, and NG2 protein and mRNA peaked on day 14 after operation. The highest expression of nestin, Tuj1, GFAP, and NG2 protein and mRNA were detected in the treatment group. Conclusions bFGF not only increases the proliferation of neural stem cells in SVZ, but also stimulates the differentiation of these cells into neurons, astrocytes, and oligodendroeytes after ischemic injury, bFGF helps repair neonatal ischemic brain injury in rats. Key words: Fibroblast growth factor 2; Brain ischemia; Nerve regeneration; Rats

Cerebral Blood Flow Velocity in the Human Newborn: The Value of Its Determination

An ultrasonic technique based on measurement of the Doppler frequency shift produced by the movement of red blood cells in an insonated vessel has been useful for measurement of cerebral blood flow velocity in the newborn. When the transducer is applied to the anterior fontanel, flow velocity in each anterior cerebral artery can be determined noninvasively. Reliable application ofthe technique requires utilization of both the audible and visible signals produced by the instrument. Experience and awareness of the anatomy are also important in interpretation. Serial measurements of cerebral blood flow velocity have provided useful information concerning changes in the cerebral circulation under important neonatal circumstances. Examples of the latter include PDA, pneumothorax, hydrocephalus, and hyperviscosity. Most of the changes in the cerebral circulation appear to reflect directly systemic hemodynamic changes. This relation between cerebral and systemic hemodynamic events is compatible with other observations, indicating that in the human newborn—particularly the infant most at risk for hypoxic-ischemic and/or hemorrhagic brain injury—the cerebral circulation is pressure passive. Indeed, the changes in the cerebral circulation observed so far with the Doppler technique may have important implications for the genesis of neonatal ischemic and hemorrhagic brain injury.