Brain injury in the premature infant: overview of clinical aspects, neuropathology, and pathogenesis

Pediatric Cranial Ultrasound Revisited: A Comprehensive Review

ABSTRACT

Cranial ultrasound (CUS) is an indispensable tool in the evaluation of intracranial pathology in premature and term neonates and older infants. Familiarity with standard cranial ultrasound techniques and parameters, normal anatomy, and commonly encountered abnormalities is crucial for providing appropriate care for these patients. This review provides a comprehensive overview of cranial ultrasound in clinical practice.

Birth weight and head circumference discordance and outcome in preterms: results from the EPIPAGE-2 cohort

OBJECTIVE

To determine whether the relative measurement of birth weight (BW) and head circumference (HC) in preterm infants is associated with neurological outcomes.

METHODS

The EPIPAGE-2 Study included 3473 infants born before 32 weeks' gestation, classified based on their Z-score of BW and HC on the Fenton curves as concordant (≤1 SD apart) or discordant (>1 SD difference). We defined four mutually exclusive categories: discordant smaller BW (sBW) with BW-1SD and concordant small measurement (CsM) with BW and HC concordant and both ≤-1SD. Neurological outcomes at 5.5 years were evaluated with standard tests.

RESULTS

2592 (74.8%) preterm neonates were categorised as CM, 258 (7.4%) CsM, 378 (10.9%) sHC and 239 (6.9%) sBW. Compared with the CM children, those born with CsM had significantly higher risks of cognitive deficiency (adjusted OR (aOR) 1.3, 95% CI (1.0 to 2.0)), developmental coordination disorders (aOR 2.6 (1.5 to 4.4)) and need for special school services (aOR 2.3 (1.5 to 3.7)). Those born with sBW had significantly lower risk of cognitive deficiency (aOR 0.6 (0.4 to 0.9)) and the sHC group significantly higher risk of developmental coordination disorders (aOR 1.8 (1.0 to 3.2)).

CONCLUSIONS

The relative discordance of these preterm infants' BW and HC was associated with their neurological outcomes. It merits further exploration as an indirect indicator of development.

TRIAL REGISTRATION NUMBER

NCT03078439.

The histologic fetal inflammatory response and neonatal outcomes: systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the prognostic role of concomitant histological fetal inflammatory response with chorioamnionitis on neonatal outcomes through a systematic review and meta-analysis of existing literature.

DATA SOURCES

The primary search was conducted on October 17, 2021, and it was updated on May 26, 2023, across 4 separate databases (MEDLINE, the Cochrane Central Register of Controlled Trials, Embase, and Scopus) without using any filters.

STUDY ELIGIBILITY CRITERIA

Observational studies reporting obstetrical and neonatal outcomes of infant-mother dyads with histological chorioamnionitis and histological fetal inflammatory response vs infant-mother dyads with histological chorioamnionitis alone were eligible. Studies that enrolled only preterm neonates, studies on neonates born before 37 weeks of gestation, or studies on neonates with very low birthweight (birthweight <1500 g) were included. The protocol was registered with the International Prospective Register of Systematic Reviews (registration number: CRD42021283448).

METHODS

The records were selected by title, abstract, and full text, and disagreements were resolved by consensus. Random-effect model-based pooled odds ratios with corresponding 95% confidence intervals were calculated for dichotomous outcomes.

RESULTS

Overall, 50 studies were identified. A quantitative analysis of 14 outcomes was performed. Subgroup analysis using the mean gestational age of the studies was performed, and a cutoff of 28 weeks of gestation was implemented. Among neonates with lower gestational ages, early-onset sepsis (pooled odds ratio, 2.23; 95% confidence interval, 1.76-2.84) and bronchopulmonary dysplasia (pooled odds ratio, 1.30; 95% confidence interval, 1.02-1.66) were associated with histological fetal inflammatory response. Our analysis showed that preterm neonates with a concomitant histological fetal inflammatory response are more likely to develop intraventricular hemorrhage (pooled odds ratio, 1.54; 95% confidence interval, 1.18-2.02) and retinopathy of prematurity (pooled odds ratio, 1.37; 95% confidence interval, 1.03-1.82). The odds of clinical chorioamnionitis were almost 3-fold higher among infant-mother dyads with histological fetal inflammatory response than among infant-mother dyads with histological chorioamnionitis alone (pooled odds ratio, 2.99; 95% confidence interval, 1.96-4.55).

CONCLUSION

This study investigated multiple neonatal outcomes and found association in the case of 4 major morbidities: early-onset sepsis, bronchopulmonary dysplasia, intraventricular hemorrhage, and retinopathy of prematurity.

Does Antenatal Progesterone Administration Modify the Risk of Neonatal Intraventricular Hemorrhage?

OBJECTIVE

 Progesterone administration has been associated with improved neurological outcomes following traumatic brain injury in adults. However, studies examining the effect of progesterone on the risk of neonatal intraventricular hemorrhage (IVH) are inconsistent. We sought to determine if maternal administration of intramuscular 17-α-hydroxyprogesterone caproate (17-OHPC) is associated with decreased rates of IVH in infants born before 32-weeks gestation.

STUDY DESIGN

 This is a retrospective study of liveborn singleton deliveries between 20- and 32-weeks gestation at two large academic medical centers from January 1, 2012 to August 30, 2020. Data were extracted from hospital electronic medical record data warehouses using standardized definitions and billing and diagnosis codes. We evaluated receipt of 17-OHPC in the antepartum period and diagnosis of IVH (grade I-IV, per Volpe classification) during the neonatal delivery hospitalization encounter. Bivariate and multivariate analyses were performed to examine the association between 17-OHPC and neonatal IVH adjusting for potential confounders. Odds ratio (ORs) and 95% confidence intervals (CIs) were presented.

RESULTS

 Among 749 neonates born between 20- and 32-week gestation, 140 (18.7%) of their mothers had received antenatal 17-OHPC and 148 (19.8%) were diagnosed with IVH after birth. No significant association was observed between maternal 17-OHPC and neonatal IVH in unadjusted (OR 1.14, 95% CI 0.72-1.78) or adjusted analyses (adjusted odds ratio 1.14, 95% CI 0.71-1.84). Independent of exposure to 17-OHPC, as expected, infants born <28-weeks gestation or those with very low birthweight (<1,500 g) were at an increased risk of IVH (OR 2.32, 95% CI 1.55-3.48 and OR 2.19, 95% CI 1.09-4.38, respectively).

CONCLUSION

 Antenatal maternal 17-OHPC administration was not associated with the risk of neonatal IVH. Further research may be warranted to determine whether timing, route of delivery, and duration of progesterone therapy impact rates of neonatal IVH.

KEY POINTS

· This study aimed to compare the frequency of intraventricular hemorrhage in preterm neonates exposed to antenatal 17-α-hydroxyprogesterone caproate to those not exposed.. · In neonates born at <32-weeks gestation, maternal use of progesterone is not associated with the risk of intraventricular hemorrhage.. · In contrast to preclinical and adult data, this study suggests that progesterone exposure is not associated with the prevention of neonatal brain injury..

Prediction of bronchopulmonary dysplasia in very preterm infants: competitive risk model nomogram

Objective

To develop predictive clinical models of bronchopulmonary dysplasia (BPD) through competing risk analysis.

Methods

Retrospective observational cohort study, including preterm newborns ≤32 weeks gestational age, conducted between January 1, 2013 and September 30, 2022 in a third-level Neonatal Intensive Care Unit in Spain. A prediction study was carried out using competing risk models, where the event of interest was BPD and the competing event was death. A multivariate competing risk model was developed separately for each postnatal day (days 1, 3, 7 and 14). Nomograms to predict BPD risk were developed from the coefficients of the final models and internally validated.

Results

A total of 306 patients were included in the study, of which 73 (23.9%) developed BPD and 29 (9.5%) died. On day 1, the model with the greatest predictive capacity was that including birth weight, days since rupture of membranes, and surfactant requirement (area under the receiver operating characteristic (ROC) curve (AUC), 0.896; 95% CI, 0.792-0.999). On day 3, the final predictive model was based on the variables birth weight, surfactant requirement, and Fraction of Inspired Oxygen (FiO2) (AUC, 0.891; 95% CI, 0.792-0.989).

Conclusions

Competing risk analysis allowed accurate prediction of BPD, avoiding the potential bias resulting from the exclusion of deceased newborns or the use of combined outcomes. The resulting models are based on clinical variables measured at bedside during the first 3 days of life, can be easily implemented in clinical practice, and can enable earlier identification of patients at high risk of BPD.

Detailed statistical analysis plan for a secondary Bayesian analysis of the SafeBoosC-III trial: a multinational, randomised clinical trial assessing treatment guided by cerebral oximetry monitoring versus usual care in extremely preterm infants

BACKGROUND

Extremely preterm infants have a high mortality and morbidity. Here, we present a statistical analysis plan for secondary Bayesian analyses of the pragmatic, sufficiently powered multinational, trial-SafeBoosC III-evaluating the benefits and harms of cerebral oximetry monitoring plus a treatment guideline versus usual care for such infants.

METHODS

The SafeBoosC-III trial is an investigator-initiated, open-label, randomised, multinational, pragmatic, phase III clinical trial with a parallel-group design. The trial randomised 1601 infants, and the frequentist analyses were published in April 2023. The primary outcome is a dichotomous composite outcome of death or severe brain injury. The exploratory outcomes are major neonatal morbidities associated with neurodevelopmental impairment later in life: (1) bronchopulmonary dysplasia; (2) retinopathy of prematurity; (3) late-onset sepsis; (4) necrotising enterocolitis; and (5) number of major neonatal morbidities (count of bronchopulmonary dysplasia, retinopathy of prematurity, and severe brain injury). The primary Bayesian analyses will use non-informed priors including all plausible effects. The models will use a Hamiltonian Monte Carlo sampler with 1 chain, a sampling of 10,000, and at least 25,000 iterations for the burn-in period. In Bayesian statistics, such analyses are referred to as 'posteriors' and will be presented as point estimates with 95% credibility intervals (CrIs), encompassing the most probable results based on the data, model, and priors selected. The results will be presented as probability of any benefit or any harm, Bayes factor, and the probability of clinical important benefit or harm. Two statisticians will analyse the blinded data independently following this protocol.

DISCUSSION

This statistical analysis plan presents a secondary Bayesian analysis of the SafeBoosC-III trial. The analysis and the final manuscript will be carried out and written after we publicise the primary frequentist trial report. Thus, we can interpret the findings from both the frequentists and Bayesian perspective. This approach should provide a better foundation for interpreting of our findings.

TRIAL REGISTRATION

ClinicalTrials.org, NCT03770741. Registered on 10 December 2018.

Brain organoids for hypoxic-ischemic studies: from bench to bedside

Our current knowledge regarding the development of the human brain mostly derives from experimental studies on non-human primates, sheep, and rodents. However, these studies may not completely simulate all the features of human brain development as a result of species differences and variations in pre- and postnatal brain maturation. Therefore, it is important to supplement the in vivo animal models to increase the possibility that preclinical studies have appropriate relevance for potential future human trials. Three-dimensional brain organoid culture technology could complement in vivo animal studies to enhance the translatability of the preclinical animal studies and the understanding of brain-related disorders. In this review, we focus on the development of a model of hypoxic-ischemic (HI) brain injury using human brain organoids to complement the translation from animal experiments to human pathophysiology. We also discuss how the development of these tools provides potential opportunities to study fundamental aspects of the pathophysiology of HI-related brain injury including differences in the responses between males and females.

Clinical Variables Associated With Grade III and IV Intraventricular Hemorrhage (IVH) in Preterm Infants Weighing Less Than 750 Grams

BACKGROUND

Despite innovative advances in neonatal medicine, intraventricular hemorrhage (IVH) continues to be a significant complication in neonatal intensive care units globally.

OBJECTIVE

The study aimed to discern the variables heightening the risk of severe IVH (Grade III and IV) in extremely premature infants weighing less than 750 grams. We postulated that a descending hematocrit (Hct) trend during the first week of life could serve as a predictive marker for the development of severe IVH in this vulnerable population.

METHODS

This retrospective case-control study encompassed infants weighing less than 750 grams at birth, diagnosed with Grade III and/or IV IVH, and born in a tertiary center from 2009 to 2014. A group of 17 infants with severe IVH was compared with 14 gestational age-matched controls. Acid-base status, glucose, fluid goal, urine output, and nutrient (caloric and protein) intake during the first four days of life were meticulously evaluated. Statistically significant variables from baseline data were further analyzed via univariable and multivariable logistic regression analyses, ensuring control for potential confounding variables.

RESULTS

The univariate logistic regression model delineated odds ratios (ORs) of 0.842 for day 2 average Hct (confidence interval [CI], 0.718-0.987) and 0.16 for urine output on day 3 (CI, 0.024-1.056), with the remaining six variables demonstrating no significant association. In the post-multivariable regression analysis, day 2 Hct was the only significant variable (OR, 0.731; 95% CI, 0.537-0.995; P=0.04). The receiver operating characteristic (ROC) curve analysis portrayed an area under the curve of 71% for the day 2 Hct variable.

CONCLUSION

The study revealed that a dip in Hct on day 2 of life augments the likelihood of Grade III and IV IVH among extremely premature infants with a birth weight of less than 750 grams. This insight amplifies our understanding of risk factors associated with severe IVH development in extremely preterm infants, potentially aiding in refining preventive strategies and optimizing clinical management and treatment of these affected infants.

Cerebral gray matter injuries in infants with intraventricular hemorrhage

While intraventricular hemorrhage (IVH) predominantly damages the periventricular white matter, it induces substantial injury to the cerebral gray matter. IVH destroys the germinal matrix, suppresses neurogenesis, and disrupts corticogenesis, thereby reducing the number of neurons in the upper cortical layer and volume of the cerebral gray matter. The pathogenesis of gray matter injury is attributed to IVH-induced oxidative stress, inflammation, and mass effect damaging the germinal matrix as well as to post-hemorrhagic ventricular dilation (PHVD). The IVH-induced cerebral gray matter injury and PHVD contribute to cognitive deficits and neurobehavioral disorders. Neuroimaging has enhanced our understanding of cerebral gray matter injury and is a valuable predictor of neurodevelopmental outcomes. Evidence from therapies tested in preclinical models and clinical trials suggests that strategies to promote neurogenesis, reduce cerebral inflammation and oxidative stress, and remove blood clots from the ventricles might enhance the outcome of these infants. This review offers an integrated view of new insights into the mechanisms underlying gray matter injury in premature infants with IVH and highlights the imminent therapies to restore neurodevelopmental dysfunction in IVH survivors.

Ultrasound imaging of preterm brain injury: fundamentals and updates

Neurosonography has become an essential tool for diagnosis and serial monitoring of preterm brain injury. Preterm infants are at significantly higher risk of hypoxic-ischemic injury, intraventricular hemorrhage, periventricular leukomalacia and post-hemorrhagic hydrocephalus. Neonatologists have become increasingly dependent on neurosonography to initiate medical and surgical interventions because it can be used at the bedside. While brain MRI is regarded as the gold standard for detecting preterm brain injury, neurosonography offers distinct advantages such as its cost-effectiveness, diagnostic utility and convenience. Neurosonographic signatures associated with poor long-term outcomes shape decisions regarding supportive care, medical or behavioral interventions, and family members' expectations. Within the last decade substantial progress has been made in neurosonography techniques, prompting an updated review of the topic. In addition to the up-to-date summary of neurosonography, this review discusses the potential roles of emerging neurosonography techniques that offer new functional insights into the brain, such as superb microvessel imaging, elastography, three-dimensional ventricular volume assessment, and contrast-enhanced US.

Perinatal Hyperoxia and Developmental Consequences on the Lung-Brain Axis

Approximately 11.1% of all newborns worldwide are born preterm. Improved neonatal intensive care significantly increased survival rates over the last decades but failed to reduce the risk for the development of chronic lung disease (i.e., bronchopulmonary dysplasia (BPD)) and impaired neurodevelopment (i.e., encephalopathy of prematurity (EoP)), two major long-term sequelae of prematurity. Premature infants are exposed to relative hyperoxia, when compared to physiological in-utero conditions and, if needed to additional therapeutic oxygen supplementation. Both are associated with an increased risk for impaired organ development. Since the detrimental effects of hyperoxia on the immature retina are known for many years, lung and brain have come into focus in the last decade. Hyperoxia-induced excessive production of reactive oxygen species leading to oxidative stress and inflammation contribute to pulmonary growth restriction and abnormal neurodevelopment, including myelination deficits. Despite a large body of studies, which unraveled important pathophysiological mechanisms for both organs at risk, the majority focused exclusively either on lung or on brain injury. However, considering that preterm infants suffering from BPD are at higher risk for poor neurodevelopmental outcome, an interaction between both organs seems plausible. This review summarizes recent findings regarding mechanisms of hyperoxia-induced neonatal lung and brain injury. We will discuss common pathophysiological pathways, which potentially link both injured organ systems. Furthermore, promises and needs of currently suggested therapies, including pharmacological and regenerative cell-based treatments for BPD and EoP, will be emphasized. Limited therapeutic approaches highlight the urgent need for a better understanding of the mechanisms underlying detrimental effects of hyperoxia on the lung-brain axis in order to pave the way for the development of novel multimodal therapies, ideally targeting both severe preterm birth-associated complications.

Sonography in Childhood and Adolescence for General Radiologists - More Possibilities Than Expected

Sonography is the most common imaging modality in childhood and adolescence. The rapid availability, absence of X-rays, bedside applicability, e. g., in intensive care units, the lack of need for sedation, and last but not least the very good ultrasound conditions in the vast majority of cases are the main advantages of sonography. Due to the spectrum of patients, from premature infants to adolescents, a great variety of questions arise for the examiner. This requires knowledge of the various disease patterns in the different age groups. Proper handling of the young patients as well as their parents is essential in order to make the examination conditions as optimal as possible. Due to the smaller body size compared to adults, sonographic examinations of the abdomen and thorax in children and adolescents are usually possible with very good image quality. In the majority of cases, a definitive diagnosis is made by sonography without additional cross-sectional imaging, which is more common in adults. Due to the acoustic windows provided by the still open fontanelles, excellent image quality of the central nervous system is usually possible in the first year of life. In most cases, complex MRI examinations are not necessary. Due to the partly still missing ossification of the bony structures, further acoustic windows are available, which allow an examination of, e. g., the spinal canal. Ultrasound also plays a major role in the examination of soft tissues and the musculoskeletal system in childhood and adolescence, not only in hip ultrasound. The aim of this article is to show this very broad spectrum for colleagues working predominantly in adult radiology, to highlight some representative examples and to present the respective clinical features in childhood and adolescence. KEY POINTS::   · Ultrasound is the most important initial imaging modality in children and adolescents.. · Often, no further cross-sectional imaging is necessary.. · The most important area of application is the abdomen and pelvis.. · Furthermore, there are additional special applications such as CNS in neonates and infants, thorax, musculoskeletal system.. CITATION FORMAT: · Schaal MC, Moritz JD, Mentzel H et al. Sonography in Childhood and Adolescence for General Radiologists - More Possibilities Than Expected.... Fortschr Röntgenstr 2021; DOI: 10.1055/a-1681-2136.

Effectiveness of Early Physiotherapy in an Infant With a High Risk of Developmental Delay

Premature birth is the most common cause for a stay in the neonatal intensive care unit (NICU) among neonates. Premature birth leads to prematurity, which is associated with complications such as respiratory distress syndrome (RDS), hyperbilirubinemia, gastroesophageal reflux (GERD), intraventricular hemorrhage (periventricular leukomalacia), retinopathy of prematurity (ROP), and so on. These secondary complications are of great concern and need to be handled with care to prevent the further deterioration of the quality of life of the baby as he grows. So, the early physiotherapeutic interventional approach comes into light and plays an important role in neonatal care.This case study demonstrates an infant boy of seven months chronological age, who had a preterm birth history with a poor APGAR (Appearance, Pulse, Grimace, Activity, and Respiration) score and NICU stay during the first three months of life. He approached the physiotherapy outpatient department with a complaint of delayed motor milestones like an absence of head holding, rolling, opening of hand, as well as delayed social-emotional development, Ryles tube (RT) in situ, with frequent episodes of GERD, neck rotated to the left side, high irritability, tactile defensiveness of both hands, and difficulty in regulating his sensory systems. Outcome measures used were gross motor function measure (GMFM), sensory profile, and rotating chair test. Early interventional physiotherapy was given including neurodevelopmental techniques (NDT), oromotor stimulation, sensory integration, passive stretching, and myofascial release for six days per week with each session of 45 minutes. The results demonstrated the achievement of motor milestones till sitting independently, reduced episodes of GERD, discontinued RT in situ, improved mobility of neck on both sides, reduced irritability, and started reaching, grasping along with bimanual tasks.

Cord blood S100B: reference ranges and interest for early identification of newborns with brain injury

Background Neurological complications are common in the premature and full-term neonates admitted to the intensive care unit, but the diagnosis of these complications is often difficult to make. S100B protein, measured in cord blood, may represent a valuable tool to better identify patients at risk of brain injury. Methods As a first step, we established S100B cord blood serum reference intervals from 183 preterm and 200 full-term neonates. We then measured cord blood serum S100B to identify neurological complications in 272 neonates hospitalized at the neonatal intensive care unit (NICU). Diagnosis of brain injury relied on imaging examination. Results The 95th percentiles of S100B concentration in cord blood were established as 1.21 μg/L for the 383 neonates, 0.96 μg/L for full-term neonates and 1.36 μg/L for premature neonates. Among the 272 neonates hospitalized at the NICU, 11 presented neurological complications. Using 1.27 μg/L as the optimal sensitivity/specificity threshold, S100B differentiate neonates with and without neurological complications with a sensitivity of 45.5% (95% confidence intervals [CI]: 16.7-76.6) and a specificity of 88.9% (95% CI: 84.4-92.4) (p = 0.006). In combination with arterial pH (<7.25), sensitivity increased to 90.9% (95% CI: 58.7-99.8), while specificity was 51.2% (95% CI: 44.8-57.7). The sensitivity is significantly (p = 0.03) increased in comparison to S100B alone. The specificity is significantly higher with S100B only than with pH + S100B (p < 0.001). Conclusions Cord blood S100B protein, in combination with arterial cord blood pH, has the potential to help clinicians to detect at birth neurological complications in neonates hospitalized in an NCIU.

The cerebral haemodynamic response to somatosensory stimulation in preterm newborn lambs is reduced with dopamine or dobutamine infusion

BACKGROUND

In the adult brain, increases in neural activity lead to increases in local blood flow. However, in the preterm neonate, studies of cerebral functional haemodynamics have yielded inconsistent results, including negative responses suggesting decreased perfusion and localised tissue hypoxia, probably due to immature neurovascular coupling. Furthermore, the impact of vasoactive medications, such as dopamine and dobutamine used as inotropic therapies in preterm neonates, on cerebrovascular responses to somatosensory input is unknown. We aimed to characterise the cerebral haemodynamic functional response after somatosensory stimulation in the preterm newborn brain, with and without dopamine or dobutamine treatment.

METHODS

We studied the cerebral haemodynamic functional response in 13 anaesthetised preterm lambs, using near infrared spectroscopy to measure changes in cerebral oxy- and deoxyhaemoglobin (ΔoxyHb, ΔdeoxyHb) following left median nerve stimulation using stimulus trains of 1.8, 4.8 and 7.8 s. The 4.8 and 7.8 s stimulations were repeated during dopamine or dobutamine infusion.

RESULTS

Stimulation always produced a somatosensory evoked response. Majority of preterm lambs demonstrated positive functional responses (i.e. increased ΔoxyHb) in the contralateral cortex following stimulus trains of all durations. Dopamine increased baseline oxyHb and total Hb, whereas dobutamine increased baseline deoxyHb. Both dopamine and dobutamine reduced the evoked ΔoxyHb responses to 4.8 and 7.8 s stimulations.

CONCLUSIONS

Somatosensory stimulation increases cerebral oxygenation in the preterm brain, consistent with increased cerebral blood flow due to neurovascular coupling. Notably, our results show that dopamine/dobutamine reduces oxygen delivery relative to consumption in the preterm brain during somatosensory stimulations, suggesting there may be a risk of intermittent localised tissue hypoxia which has clear implications for clinical practice and warrants further investigation.

Decreased content of ascorbic acid (vitamin C) in the brain of knockout mouse models of Na+,K+-ATPase-related neurologic disorders

Na⁺,K⁺-ATPase is a crucial protein responsible for maintaining the electrochemical gradients across the cell membrane. The Na⁺,K⁺-ATPase is comprised of catalytic α, β, and γ subunits. In adult brains, the α3 subunit, encoded by ATP1A3, is predominantly expressed in neurons, whereas the α2 subunit, encoded by ATP1A2, is expressed in glial cells. In foetal brains, the α2 is expressed in neurons as well. Mutations in α subunits cause a variety of neurologic disorders. Notably, the onset of symptoms in ATP1A2- and ATP1A3-related neurologic disorders is usually triggered by physiological or psychological stressors. To gain insight into the distinct roles of the α2 and α3 subunits in the developing foetal brain, whose developmental dysfunction may be a predisposing factor of neurologic disorders, we compared the phenotypes of mouse foetuses with double homozygous knockout of Atp1a2 and Atp1a3 (α2α3-dKO) to those with single knockout. The brain haemorrhage phenotype of α2α3-dKO was similar to that of homozygous knockout of the gene encoding ascorbic acid (ASC or vitamin C) transporter, SVCT2. The α2α3-dKO brain showed significantly decreased level of ASC compared with the wild-type (WT) and single knockout. We found that the ASC content in the basal ganglia and cerebellum was significantly lower in the adult Atp1a3 heterozygous knockout mouse (α3-HT) than in the WT. Interestingly, we observed a significant decrease in the ASC level in the basal ganglia and cerebellum of α3-HT in the peripartum period, during which mice are under physiological stress. These observations indicate that the α2 and α3 subunits independently contribute to the ASC level in the foetal brain and that the α3 subunit contributes to ASC transport in the adult basal ganglia and cerebellum. We propose that decreases in ASC levels may affect neural network development and are linked to the pathophysiology of ATP1A2- and ATP1A3-related neurologic disorders.

Decreased Incidence of Intraventricular Hemorrhage in Extremely Low Birth Weight Infants Using Customized Circulatory Management to Evaluate the Hemodynamic Change of Patent Ductus Arteriosus

Background: In extremely low birth weight (ELBW) infants, the patent ductus arteriosus (PDA) with left-to-right shunt and an increase in systemic artery resistance may cause increasing preload and afterload of the left ventricle. The immature myocardium in ELBW infants has a limited ability to respond to the change, which leads to hemorrhagic complications. In this study, we detected the hemodynamic change of cardiac performance and applied a clinical strategy to prevent PDA-associated hemorrhagic complications in ELBW infants. Methods: We enrolled ELBW infants at a single medical center in Taiwan. The customized circulatory management was performed by echocardiography after birth until the PDA closed. Inotropic agents were administrated according to the requirements of hemodynamic parameters or clinical conditions. The primary outcomes were hemorrhagic complications including pulmonary hemorrhage and intraventricular hemorrhage (IVH) greater than grade II. The secondary outcomes were the rate of surgical ligation of PDA, mortality, necrotizing enterocolitis, and bronchopulmonary dysplasia. Results: A total of 20 ELBW infants were evaluated by customized circulatory management from 2019 to 2020. We reviewed 35 ELBW infants born between 2017 and 2018 in our hospital, who served as the non-management group. The management group had a significantly lower incidence rate of IVH greater than grade 2 (p = 0.02). Other outcomes showed no significant differences. Dobutamine was prescribed in 8 cases in the management group, and end-systolic wall stress (ESWS) was significantly decreased after Dobutamine administration (p = 0.017). Conclusion: The incidence rate of IVH greater than grade II in ELBW infants decreased after use of customized circulatory management in our study. The strategy of customized circulatory management might be an effective "early target therapy" for hemodynamically significant PDA in high-risk ELBW infants. Inotropic therapy with Dobutamine could be a useful medical choice for improving cardiac function to prevent hemorrhagic complications.

Increased peak end-expiratory pressure in ventilated preterm lambs changes cerebral microvascular perfusion: direct synchrotron microangiography assessment

Positive end-expiratory pressure (PEEP) improves oxygenation in mechanically ventilated preterm neonates by preventing lung collapse. However, high PEEP may alter cerebral blood flow secondarily to the increased intrathoracic pressure, predisposing to brain injury. The precise effects of high PEEP on cerebral hemodynamics in the preterm brain are unknown. We aimed to assess the effect of PEEP on microvessels in the preterm brain by using synchrotron radiation (SR) microangiography, which enables in vivo real-time high-resolution imaging of the cerebral vasculature. Preterm lambs (0.8 gestation, n = 4) were delivered via caesarean section, anesthetized, and ventilated. SR microangiography of the right cerebral hemisphere was performed with iodine contrast administered into the right carotid artery during PEEP ventilation of 5 and 10 cmH₂O. Carotid blood flow was measured using an ultrasonic flow probe placed around the left carotid artery. An increase of PEEP from 5 to 10 cmH₂O increased the diameter of small cerebral vessels (<150 µm) but decreased the diameter of larger cerebral vessels (>500 µm) in all four lambs. Additionally, the higher PEEP increased the cerebral contrast transit time in three of the four lambs. Carotid blood flow increased in two lambs, which also had increased carbon dioxide levels during PEEP 10. Our results suggest that PEEP of 10 cmH₂O alters the preterm cerebral hemodynamics, with prolonged cerebral blood flow transit and engorgement of small cerebral microvessels likely due to the increased intrathoracic pressure. These microvascular changes are generally not reflected in global assessment of cerebral blood flow or oxygenation.NEW & NOTEWORTHY An increase of positive end-expiratory pressure (PEEP) from 5 to 10 cmH₂O increased the diameter of small cerebral vessels (<150 µm) but decreased the diameter of larger cerebral vessels (>500 µm). This suggests increased intrathoracic pressure due to high PEEP can drive microvessel engorgement in the preterm brain, which may play a role in cerebrovascular injury.

Machine Learning to Support Hemodynamic Intervention in the Neonatal Intensive Care Unit

Hemodynamic support in neonatal intensive care is directed at maintaining cardiovascular wellbeing. At present, monitoring of vital signs plays an essential role in augmenting care in a reactive manner. By applying machine learning techniques, a model can be trained to learn patterns in time series data, allowing the detection of adverse outcomes before they become clinically apparent. In this review we provide an overview of the different machine learning techniques that have been used to develop models in hemodynamic care for newborn infants. We focus on their potential benefits, research pitfalls, and challenges related to their implementation in clinical care.

Cranial ultrasound findings in preterm germinal matrix haemorrhage, sequelae and outcome

Germinal matrix-intraventricular haemorrhage (GMH-IVH), periventricular haemorrhagic infarction (PHI) and its complication, post-haemorrhagic ventricular dilatation (PHVD), are still common neonatal morbidities in preterm infants that are highly associated with adverse neurodevelopmental outcome. Typical cranial ultrasound (CUS) findings of GMH-IVH, PHI and PHVD, their anatomical substrates and underlying mechanisms are discussed in this paper. Furthermore, we propose a detailed descriptive classification of GMH-IVH and PHI that may improve quality of CUS reporting and prediction of outcome in infants suffering from GMH-IVH/PHI.

Fetal Inflammatory Response Syndrome and Cerebral Oxygenation During Immediate Postnatal Transition in Preterm Neonates

Introduction: Fetal inflammatory response syndrome (FIRS), defined as elevated umbilical cord blood interleukin-6 (IL-6) values > 11 pg/ml, is associated with an increased risk of neonatal morbidity and mortality. The primary aim of the present study was to evaluate a potential influence of FIRS on cerebral oxygen saturation (crSO2) and fractional tissue oxygen extraction (cFTOE) during immediate postnatal transition in preterm neonates. The secondary aim was to analyze the potential influence of FIRS on cerebral injury and mortality. Methods: Secondary outcome parameters of prospective observational studies were analyzed. Preterm neonates with measured IL-6 values from umbilical cord blood and cerebral near-infrared spectroscopy (NIRS) measurements during immediate transition after birth were included. Preterm neonates with FIRS (FIRS group) were matched 1:1 for gestational age (± 1 week) to preterm neonates without FIRS (non-FIRS group). crSO2, cFTOE, arterial oxygen saturation (SpO2), heart rate (HR), and fraction of inspired oxygen (FiO2) were compared between both groups. In addition, cerebral injury and mortality were compared between both groups. Results: A total of 46 preterm neonates were included. Twenty-three neonates in the FIRS group [median gestational age 32.1 (IQR 30.3-33.0) weeks; median IL-6 19.7 (IQR 12.2-37.0) pg/ml] were compared to 23 neonates in the non-FIRS group [gestational age: 32.0 (30.4-33.1) weeks; IL-6: 5.4 (3.0-6.7) pg/ml]. cFTOE showed significantly lower values within the first 4 min and a trend toward lower values in minute 5 after birth in the FIRS group. There were no significant differences in crSO2 within the first 15 min after birth between the two groups. SpO2 was significantly lower in minutes 5 and 6 and HR was significantly lower in minutes 2 and 4 after birth in the FIRS group compared to the non-FIRS group. Survival without cerebral injury was similar in both groups. Conclusion: In preterm neonates with FIRS the crSO2 was similar despite significantly lower cFTOE values during the first minutes after birth. This observation may be a result of compromised oxygen consumption and delivery in the first minutes after birth in neonates with FIRS.

Cerebral near-infrared spectroscopy monitoring versus treatment as usual for extremely preterm infants: a protocol for the SafeBoosC randomised clinical phase III trial

BACKGROUND

Cerebral oxygenation monitoring may reduce the risk of death and neurologic complications in extremely preterm infants, but no such effects have yet been demonstrated in preterm infants in sufficiently powered randomised clinical trials. The objective of the SafeBoosC III trial is to investigate the benefits and harms of treatment based on near-infrared spectroscopy (NIRS) monitoring compared with treatment as usual for extremely preterm infants.

METHODS/DESIGN

SafeBoosC III is an investigator-initiated, multinational, randomised, pragmatic phase III clinical trial. Inclusion criteria will be infants born below 28 weeks postmenstrual age and parental informed consent (unless the site is using 'opt-out' or deferred consent). Exclusion criteria will be no parental informed consent (or if 'opt-out' is used, lack of a record that clinical staff have explained the trial and the 'opt-out' consent process to parents and/or a record of the parents' decision to opt-out in the infant's clinical file); decision not to provide full life support; and no possibility to initiate cerebral NIRS oximetry within 6 h after birth. Participants will be randomised 1:1 into either the experimental or control group. Participants in the experimental group will be monitored during the first 72 h of life with a cerebral NIRS oximeter. Cerebral hypoxia will be treated according to an evidence-based treatment guideline. Participants in the control group will not undergo cerebral oxygenation monitoring and will receive treatment as usual. Each participant will be followed up at 36 weeks postmenstrual age. The primary outcome will be a composite of either death or severe brain injury detected on any of the serial cranial ultrasound scans that are routinely performed in these infants up to 36 weeks postmenstrual age. Severe brain injury will be assessed by a person blinded to group allocation. To detect a 22% relative risk difference between the experimental and control group, we intend to randomise a cohort of 1600 infants.

DISCUSSION

Treatment guided by cerebral NIRS oximetry has the potential to decrease the risk of death or survival with severe brain injury in preterm infants. There is an urgent need to assess the clinical effects of NIRS monitoring among preterm neonates.

TRIAL REGISTRATION

ClinicalTrial.gov, NCT03770741. Registered 10 December 2018.

Detailed statistical analysis plan for the SafeBoosC III trial: a multinational randomised clinical trial assessing treatment guided by cerebral oxygenation monitoring versus treatment as usual in extremely preterm infants

BACKGROUND

Infants born extremely preterm are at high risk of dying or suffering from severe brain injuries. Treatment guided by monitoring of cerebral oxygenation may reduce the risk of death and neurologic complications. The SafeBoosC III trial evaluates the effects of treatment guided by cerebral oxygenation monitoring versus treatment as usual. This article describes the detailed statistical analysis plan for the main publication, with the aim to prevent outcome reporting bias and data-driven analyses.

METHODS/DESIGN

The SafeBoosC III trial is an investigator-initiated, randomised, multinational, pragmatic phase III trial with a parallel group structure, designed to investigate the benefits and harms of treatment based on cerebral near-infrared spectroscopy monitoring compared with treatment as usual. Randomisation will be 1:1 stratified for neonatal intensive care unit and gestational age (lower gestational age (< 26 weeks) compared to higher gestational age (≥ 26 weeks)). The primary outcome is a composite of death or severe brain injury at 36 weeks postmenstrual age. Primary analysis will be made on the intention-to-treat population for all outcomes, using mixed-model logistic regression adjusting for stratification variables. In the primary analysis, the twin intra-class correlation coefficient will not be considered. However, we will perform sensitivity analyses to address this. Our simulation study suggests that the inclusion of multiple births is unlikely to significantly affect our assessment of intervention effects, and therefore we have chosen the analysis where the twin intra-class correlation coefficient will not be considered as the primary analysis.

DISCUSSION

In line with the Declaration of Helsinki and the International Conference on Harmonization Good Clinical Practice guidelines, we have developed and published this statistical analysis plan for the SafeBoosC III trial, prior to any data analysis.

TRIAL REGISTRATION

ClinicalTrials.org, NCT03770741. Registered on 10 December 2018.

Movement Imitation Therapy for Preterm Babies (MIT-PB): a Novel Approach to Improve the Neurodevelopmental Outcome of Infants at High-Risk for Cerebral Palsy

To improve the neurodevelopmental outcome in infants with high grade intraventricular haemorrhage and cramped-synchronised (CS) general movements (GMs). Four very preterm infants with intraventricular haemorrhage grade III (n = 3) or intraventricular haemorrhage with apparent periventricular haemorrhagic infarction (n = 1) were diagnosed with CS GMs at 33 to 35 weeks postmenstrual age. A few days later MIT-PB [Movement Imitation Therapy for Preterm Babies], an early intervention programme, was commenced: the instant an infant showed CS movements, the therapist intervened by gently guiding the infant's limbs so as to manoeuvre and smoothen the movements, thereby imitating normal GM sequences as closely as possible (at least for 10 min, 5 times a day, with increasing frequency over a period of 10 to 12 weeks). After a period of consistent CS GMs, the movements improved. At 14 weeks postterm age, the age specific GM pattern, fidgety movements, were normal in three infants, one infant had abnormal fidgety movements. At preschool age, all participants had a normal neurodevelopmental outcome. This report on four cases demonstrates that mimicking normal and variable GM sequences might have a positive cascading effect on neurodevelopment. The results need to be interpreted with caution and replication studies on larger samples are warranted. Nonetheless, this innovative approach may represent a first step into a new intervention strategy.

Interrelationship Between Hemodynamics, Brain Volumes, and Outcome in Hypoplastic Left Heart Syndrome

BACKGROUND

The long-term impact of altered hemodynamics after stage II in children with hypoplastic left heart syndrome (HLHS) and hypoplastic left heart complex (HLHC) on cerebral growth and neurodevelopmental outcome is unknown. We aimed to investigate whether elevated central venous and atrial filling pressures before the Fontan procedure may be associated with smaller brain volumes and poorer neurodevelopmental outcome after the initial hybrid procedure.

METHODS

In a two-center cohort study semiautomated segmentation of cerebral magnetic resonance imaging scans was conducted in 25 children with HLHS/HLHC (25 hybrid) before the Fontan procedure (27.6 ± 4.3 months) and in 8 healthy control subjects (29.7 ± 9.5 months). Study patients were evaluated with the Bayley Scales of Infant and Toddler Development III (Bayley-III) and a neurologic examination. Hemodynamic measures after stage II were assessed with cardiac catheterization at 2 years of age before Fontan completion. Children with known genetic comorbidities were excluded.

RESULTS

In HLHS/HLHC patients higher atrial filling pressures (6 ± 3 mm Hg; range, 2-14) were correlated with reduced brain volumes and lower language composite score, whereas higher Glenn pressures (10 ± 3 mm Hg; range, 6-16) were related to higher cerebrospinal fluid, reduced brain volumes, and lower cognitive, language, and motoric composite scores in the Bayley-III. Compared with control subjects white matter volumes were reduced and cerebrospinal fluid volumes increased in study patients.

CONCLUSIONS

These data suggest that altered cardiovascular hemodynamics after stage II influence brain growth and neurodevelopmental outcome in infants with HLHS/HLHC.

The Association of Intraventricular Hemorrhage and Acute Kidney Injury in Premature Infants from the Assessment of the Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) Study

BACKGROUND

Acute kidney injury (AKI) and intraventricular hemorrhage (IVH) are common in premature infants. We previously demonstrated that infants with AKI have a higher hazards ratio to develop grade ≥2 IVH when controlling for confounders. However, that single-center study was unable to show an overall association.

OBJECTIVES

To test the hypothesis that infants diagnosed with AKI have an increased risk of IVH independent of variables associated with both AKI and IVH, we performed a study on 825 infants from the Assessment of Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) study (a 24-center multinational retrospective cohort).

METHOD

A neonatal modified KDIGO definition of AKI was used based on serum creatinine (SCr) and/or urine output criteria. Baseline SCr was defined as the lowest previous value. IVH was diagnosed with head ultrasounds.

RESULTS

AKI was documented in 22.2% (183/825) of infants and IVH in 14.3% (118/825). Infants with AKI (n = 183) were more likely to have IVH (26.8%, 49/183) than those without AKI (n= 642) who had IVH (10.7%, 69/642, p < 0.0001). After controlling for 5-min Apgar score, vasopressor support within the first week of age, and gestational age, infants with AKI had 1.6 times higher adjusted odds to develop any grade IVH (95% CI 1.04-2.56). Furthermore, infants of gestational age of 22-28 weeks had 1.9 times higher adjusted odds to develop IVH (OR 1.87, 95% CI 1.08-3.23).

CONCLUSIONS

We present the first multicenter evaluation of the association between AKI and IVH in premature infants showing a significant independent association between AKI and IVH. Development of strategies to reduce AKI may also reduce IVH.

Association between Subcortical Morphology and Cerebral White Matter Energy Metabolism in Neonates with Congenital Heart Disease

Complex congenital heart disease (CHD) is associated with neurodevelopmental impairment, the mechanism of which is unknown. Cerebral cortical dysmaturation in CHD is linked to white matter abnormalities, including developmental vulnerability of the subplate, in relation to oxygen delivery and metabolism deficits. In this study, we report associations between subcortical morphology and white matter metabolism in neonates with CHD using quantitative magnetic resonance imaging (MRI) and spectroscopy (MRS). Multi-modal brain imaging was performed in three groups of neonates close to term-equivalent age: (1) term CHD (n = 56); (2) preterm CHD (n = 37) and (3) preterm control group (n = 22). Thalamic volume and cerebellar transverse diameter were obtained in relation to cerebral metrics and white matter metabolism. Short echo single-voxel MRS of parietal and frontal white matter was used to quantitate metabolites related to brain maturation (n-acetyl aspartate [NAA], choline, myo-inositol), neurotransmitter (glutamate), and energy metabolism (glutamine, citrate, creatine and lactate). Multi-variate regression was performed to delineate associations between subcortical morphological measurements and white matter metabolism controlling for age and white matter injury. Reduced thalamic volume, most pronounced in the preterm control group, was associated with increased citrate levels in all three group in the parietal white matter. In contrast, reduced cerebellar volume, most pronounced in the preterm CHD group, was associated with reduced glutamine in parietal grey matter in both CHD groups. Single ventricle anatomy, aortic arch obstruction, and cyanotic lesion were predictive of the relationship between reduced subcortical morphometry and reduced GLX (particularly glutamine) in both CHD cohorts (frontal white matter and parietal grey matter). Subcortical morphological associations with brain metabolism were also distinct within each of the three groups, suggesting these relationships in the CHD groups were not directly related to prematurity or white matter injury alone. Taken together, these findings suggest that subplate vulnerability in CHD is likely relevant to understanding the mechanism of both cortical and subcortical dysmaturation in CHD infants. Future work is needed to link this potential pattern of encephalopathy of CHD (including the constellation of grey matter, white matter and brain metabolism deficits) to not only abnormal fetal substrate delivery and oxygen conformance, but also regional deficits in cerebral energy metabolism.

Utility of prenatal Doppler ultrasound to predict neonatal impaired cerebral autoregulation

OBJECTIVE

Determine if abnormal prenatal Doppler ultrasound indices are predictive of postnatal impaired cerebral autoregulation.

STUDY DESIGN

Prospective cohort study of 46 subjects, 24⁰-29⁶ weeks' gestation. Utilizing near-infrared spectroscopy and receiver-operating characteristic analysis, impaired cerebral autoregulation was defined as >16.5% time spent in a dysregulated state within 96 h of life. Normal and abnormal Doppler indices were compared for perinatal outcomes.

RESULTS

Subjects with abnormal cerebroplacental ratio (n = 12) and abnormal umbilical artery pulsatility index (n = 13) were likely to develop postnatal impaired cerebral autoregulation (p ≤ 0.02). Abnormal cerebroplacental ratio was associated with impaired cerebral autoregulation between 24 and 48 h of life (p = 0.016). These subjects have increased risk for fetal growth restriction, lower birth weight, lower Apgar scores, acidosis, and severe intraventricular hemorrhage and/or death (p < 0.05).

CONCLUSION

Abnormal cerebroplacental ratio and umbilical artery pulsatility index are associated with postnatal impairment in cerebral autoregulation and adverse outcome.

Fine Motor Skill Mediates Visual Memory Ability with Microstructural Neuro-correlates in Cerebellar Peduncles in Prematurely Born Adolescents

Adolescents born preterm (PT) with no evidence of neonatal brain injury are at risk of deficits in visual memory and fine motor skills that diminish academic performance. The association between these deficits and white matter microstructure is relatively unexplored. We studied 190 PTs with no brain injury and 92 term controls at age 16 years. The Rey-Osterrieth Complex Figure Test (ROCF), the Beery visual-motor integration (VMI), and the Grooved Pegboard Test (GPT) were collected for all participants, while a subset (40 PTs and 40 terms) underwent diffusion-weighted magnetic resonance imaging. PTs performed more poorly than terms on ROCF, VMI, and GPT (all P < 0.01). Mediation analysis showed fine motor skill (GPT score) significantly mediates group difference in ROCF and VMI (all P < 0.001). PTs showed a negative correlation (P < 0.05, corrected) between fractional anisotropy (FA) in the bilateral middle cerebellar peduncles and GPT score, with higher FA correlating to lower (faster task completion) GPT scores, and between FA in the right superior cerebellar peduncle and ROCF scores. PTs also had a positive correlation (P < 0.05, corrected) between VMI and left middle cerebellar peduncle FA. Novel strategies to target fine motor skills and the cerebellum may help PTs reach their full academic potential.

Measuring Near-Infrared Spectroscopy Derived Cerebral Autoregulation in Neonates: From Research Tool Toward Bedside Multimodal Monitoring

Introduction: Cerebral autoregulation (CAR), the ability of the human body to maintain cerebral blood flow (CBF) in a wide range of perfusion pressures, can be calculated by describing the relation between arterial blood pressure (ABP) and cerebral oxygen saturation measured by near-infrared spectroscopy (NIRS). In literature, disturbed CAR is described in different patient groups, using multiple measurement techniques and mathematical models. Furthermore, it is unclear to what extent cerebral pathology and outcome can be explained by impaired CAR. Aim and methods: In order to summarize CAR studies using NIRS in neonates, a systematic review was performed in the PUBMED and EMBASE database. To provide a general overview of the clinical framework used to study CAR, the different preprocessing methods and mathematical models are described and explained. Furthermore, patient characteristics, definition of impaired CAR and the outcome according to this definition is described organized for the different patient groups. Results: Forty-six articles were included in this review. Four patient groups were established: preterm infants during the transitional period, neonates receiving specific medication/treatment, neonates with congenital heart disease and neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia. Correlation, coherence and transfer function (TF) gain are the mathematical models most frequently used to describe CAR. The definition of impaired CAR is depending on the mathematical model used. The incidence of intraventricular hemorrhage in preterm infants is the outcome variable most frequently correlated with impaired CAR. Hypotension, disease severity, dopamine treatment, injury on magnetic resonance imaging (MRI) and long term outcome are associated with impaired CAR. Prospective interventional studies are lacking in all research areas. Discussion and conclusion: NIRS derived CAR measurement is an important research tool to improve knowledge about central hemodynamic fluctuations during the transitional period, cerebral pharmacodynamics of frequently used medication (sedatives-inotropes) and cerebral effects of specific therapies in neonatology. Uniformity regarding measurement techniques and mathematical models is needed. Multimodal monitoring databases of neonatal intensive care patients of multiple centers, together with identical outcome parameters are needed to compare different techniques and make progress in this field. Real-time bedside monitoring of CAR, together with conventional monitoring, seems a promising technique to improve individual patient care.

Reduction of brain volumes after neonatal cardiopulmonary bypass surgery in single-ventricle congenital heart disease before Fontan completion

BackgroundLittle is known about the relationship between brain volumes and neurodevelopmental outcome at 2 years of age in children with single-ventricle congenital heart disease (CHD). We hypothesized that reduced brain volumes may be associated with adverse neurodevelopmental outcome.MethodsVolumetric segmentation of cerebral magnetic resonance imaging (MRI) scans was carried out in 44 patients without genetic comorbidities and in 8 controls. Neurodevelopmental outcome was assessed with the Bayley-III scales.ResultsGray matter (GM), deep GM, white matter (WM), and cerebrospinal fluid (CSF) volumes were 611±59, 43±4.5, 277±30, and 16.4 ml, respectively (interquartile range (IQR) 13.1, 23.3 ml). Children undergoing neonatal cardiopulmonary bypass surgery showed smaller deep GM (P=0.005) and WM (P=0.021) volumes. Brain volumes were smaller in patients compared with controls (GM: P=0.017, deep GM: P=0.012, and WM: P=0.015), whereas CSF volumes were greater (P=0.014). Of all intracranial volumes, only CSF volume was associated with neurodevelopmental outcome, accounting for 21% (P=0.011) of variability in the cognitive composite score when combined with common risk factors in a multivariable analysis.ConclusionIncreased CSF volume represents a significant risk factor for neurodevelopmental impairment in children with single-ventricle CHD. Later assessments are warranted to determine the prognostic role of intracranial volumes for long-term outcome.

Disentangling How the Brain is "Wired" in Cortical (Cerebral) Visual Impairment

Cortical (cerebral) visual impairment (CVI) results from perinatal injury to visual processing structures and pathways of the brain and is the most common cause of severe visual impairment or blindness in children in developed countries. Children with CVI display a wide range of visual deficits including decreased visual acuity, impaired visual field function, as well as impairments in higher-order visual processing and attention. Together, these visual impairments can dramatically influence a child's development and well-being. Given the complex neurologic underpinnings of this condition, CVI is often undiagnosed by eye care practitioners. Furthermore, the neurophysiological basis of CVI in relation to observed visual processing deficits remains poorly understood. Here, we present some of the challenges associated with the clinical assessment and management of individuals with CVI. We discuss how advances in brain imaging are likely to help uncover the underlying neurophysiology of this condition. In particular, we demonstrate how structural and functional neuroimaging approaches can help gain insight into abnormalities of white matter connectivity and cortical activation patterns, respectively. Establishing a connection between how changes within the brain relate to visual impairments in CVI will be important for developing effective rehabilitative and education strategies for individuals living with this condition.

[Protective effect of histone acetylation against cortical injury in neonatal rats]

OBJECTIVE

To investigate the protective effect of histone acetylation against hypoxic-ischemic cortical injury in neonatal rats.

METHODS

A total of 90 neonatal rats aged 3 days were divided into three groups: sham-operation, cortical injury model, and sodium butyrate (a histone deacetylase inhibitor) treatment. The rats in the model and the sodium butyrate treatment groups were intraperitoneally injected with lipopolysaccharide (0.05 mg/kg), and then right common carotid artery ligation was performed 2 hours later and the rats were put in a hypoxic chamber (oxygen concentration 6.5%) for 90 minutes. The rats in the sham-operation group were intraperitoneally injected with normal saline and the right common carotid artery was only separated and exposed without ligation or hypoxic treatment. The rats in the sodium butyrate treatment group were intraperitoneally injected with sodium butyrate (300 mg/kg) immediately after establishment of the cortical injury model once a day for 7 days. Those in the sham-operation and the model groups were injected with the same volume of normal saline. At 7 days after establishment of the model, Western blot was used to measure the protein expression of histone H3 (HH3), acetylated histone H3 (AH3), B-cell lymphoma/leukemia-2 (Bcl-2), Bcl-2-associated X protein (BAX), cleaved caspase-3 (CC3), and brain-derived neurotrophic factor (BDNF). Immunofluorescence assay was used to measure the expression of 5-bromo-2'-deoxyuridine (BrdU) as the cortex cell proliferation index.

RESULTS

The sodium butyrate treatment group had a significantly lower HH3/AH3 ratio than the model group (P<0.05), which suggested that the sodium butyrate treatment group had increased acetylation of HH3. Compared with the model group, the sodium butyrate treatment group had a significant increase in Bcl-2/Bax ratio, a significant reduction in CC3 expression, and a significant increase in BDNF expression (P<0.05). The sodium butyrate treatment group had a significant increase in the number of BrdU-positive cells in the cortex compared with the model group (P<0.05), and BrdU was mainly expressed in the neurons.

CONCLUSIONS

Increased histone acetylation may protect neonatal rats against cortical injury by reducing apoptosis and promoting regeneration of neurons. The mechanism may be associated with increased expression of BDNF.

Cerebral versus Ocular Visual Impairment: The Impact on Developmental Neuroplasticity

Cortical/cerebral visual impairment (CVI) is clinically defined as significant visual dysfunction caused by injury to visual pathways and structures occurring during early perinatal development. Depending on the location and extent of damage, children with CVI often present with a myriad of visual deficits including decreased visual acuity and impaired visual field function. Most striking, however, are impairments in visual processing and attention which have a significant impact on learning, development, and independence. Within the educational arena, current evidence suggests that strategies designed for individuals with ocular visual impairment are not effective in the case of CVI. We propose that this variance may be related to differences in compensatory neuroplasticity related to the type of visual impairment, as well as underlying alterations in brain structural connectivity. We discuss the etiology and nature of visual impairments related to CVI, and how advanced neuroimaging techniques (i.e., diffusion-based imaging) may help uncover differences between ocular and cerebral causes of visual dysfunction. Revealing these differences may help in developing future strategies for the education and rehabilitation of individuals living with visual impairment.

Mild intrauterine hypoperfusion reproduces neurodevelopmental disorders observed in prematurity

Severe intrauterine ischemia is detrimental to the developing brain. The impact of mild intrauterine hypoperfusion on neurological development, however, is still unclear. We induced mild intrauterine hypoperfusion in rats on embryonic day 17 via arterial stenosis with metal microcoils wrapped around the uterine and ovarian arteries. All pups were born with significantly decreased birth weights. Decreased gray and white matter areas were observed without obvious tissue damage. Pups presented delayed newborn reflexes, muscle weakness, and altered spontaneous activity. The levels of proteins indicative of inflammation and stress in the vasculature, i.e., RANTES, vWF, VEGF, and adiponectin, were upregulated in the placenta. The levels of mRNA for proteins associated with axon and astrocyte development were downregulated in fetal brains. The present study demonstrates that even mild intrauterine hypoperfusion can alter neurological development, which mimics the clinical signs and symptoms of children with neurodevelopmental disorders born prematurely or with intrauterine growth restriction.

Does hyperglycemia in hypernatremic preterm infants increase the risk of intraventricular hemorrhage?

OBJECTIVE

Hypernatremia and hyperglycemia are highly prevalent in preterm infants during the first week after birth, and both can lead to hyperosmolarity and osmotic shifts. The objective is to determine whether hyperglycemia increases the risk of intraventricular hemorrhage (IVH) in hypernatremic preterm infants.

STUDY DESIGN

Single-center retrospective medical record review of 216 infants <1000 g birth weight and <29 weeks gestational age (admitted over a 9-year period) who had serum sodium levels and blood glucose levels monitored at least every 24 h and more frequently if indicated during the first 10 days after birth. Hyperglycemia was defined as persistently high blood glucose (usually >200 mg dl(-1)) treated with an insulin infusion. Hypernatremia was defined as a serum sodium level of ⩾150 mmol l(-1) on repeated measurements.

RESULTS

Of the 216 infants studied, 76 (35%) developed hyperglycemia and 126 (58%) developed hypernatremia. IVH developed more frequently in infants with hyperglycemia (P=0.006, odds ratio (OR) 2.3, 95% confidence interval (CI) 1.3 to 4.1), in infants with hypernatremia (P=0.018, OR 2.0, 95% CI 1.2 to 3.5) and in infants with hypernatremia plus hyperglycemia (P=0.001, OR 3.2, 95% CI 1.6 to 6.4). Multivariate regression analysis confirmed the independent association of higher risk of IVH with the presence of hypernatremia plus hyperglycemia (P=0.015, OR 2.6, 95% CI 1.2 to 5.5) but not with hypernatremia or hyperglycemia alone.

CONCLUSION

Hyperglycemia increases the risk of IVH in hypernatremic preterm infants.

Risk factors for periventricular white matter injury in very low birthweight neonates

BACKGROUND

The development of periventricular white matter injury (PWMI) in the preterm neonate is the most common insult portending neurologic impairment and is linked with the later development of cerebral palsy. The pathogenesis of PWMI targets premyelinating oligodendrocytes of the periventricular region secondary to free radicals, cytokine toxicity, and excitatory neurotransmitters. The primitive nature of the vasculature in the developing fetal cortex lends to its predilection to PWMI and cerebral ischemia with less arterial anastomoses at arterial border zones and failure to compensate for global hypotension, termed the "pressure-passive" circulation.

OBJECTIVE

Our objective is to determine the relative risk (RR) of fetal metabolic acidosis and perinatal infection in the development of PWMI in very low birthweight (VLBW) (<1500 g) neonates.

STUDY DESIGN

This is a cohort study of all VLBW neonates admitted to our neonatal intensive care unit from April 2009 through December 2014, comparing those who developed PWMI on neonatal head ultrasound at 6 weeks of life to those who did not. Neonates with chromosomal or major congenital abnormalities were excluded. Generalized linear modeling, adjusting for variables significantly different on bivariate analysis, was conducted.

RESULTS

During this 5-year and 8-month period there were 374 VLBW neonates admitted; 35 (9.4%) had PWMI. VLBW neonates without PWMI were significantly more likely to have intrauterine growth restriction (2.9% PWMI, 21.5% no PWMI; P = .006), while those neonates with PWMI had a significantly lower gestational age (26.3 ± 2.2 vs 28.0 ± 2.5 weeks; P < .001) and birthweight (868 ± 237 vs 993 ± 276 g; P = .009). There was no significant difference in umbilical arterial pH (7.25 ± 0.15 vs 7.27 ± 0.09; P = .34), base deficit (4.6 ± 6.0 vs 3.4 ± 3.3 mmol/L; P = .11), or pH <7.0 or base deficit >12 mmol/L at birth (10.7% vs 3.2%; P = .09). On bivariate analysis neonates with PWMI had a significant increase in positive cerebrospinal fluid (CSF) cultures (22.9% vs 1.5%; P < .001). The initial lumbar puncture was performed at a similar day of life, and neonates with PWMI had significantly elevated CSF white blood cell counts (5%, 50%, and 95%; 16, 175, and 709/mm(3); 1, 3, and 27/mm(3); P = .008). Generalized linear modeling, adjusted for gestational age and the presence of intrauterine growth restriction, showed that fetal metabolic acidosis had RR 2.59 (95% confidence interval, 1.14-5.92; P = .02) and neonatal CSF infection had RR 4.94 (95% confidence interval, 2.4-10.3; P < .001) for association with PWMI.

CONCLUSION

The RR of neonatal CSF infection being associated with PWMI was 2-fold greater than metabolic acidosis at the time of birth. Decreasing the incidence of CSF infections would have a greater impact on preventing PWMI, a precursor of cerebral palsy.

Decreased and Increased Anisotropy along Major Cerebral White Matter Tracts in Preterm Children and Adolescents

Premature birth is highly prevalent and associated with neurodevelopmental delays and disorders. Adverse outcomes, particularly in children born before 32 weeks of gestation, have been attributed in large part to white matter injuries, often found in periventricular regions using conventional imaging. To date, tractography studies of white matter pathways in children and adolescents born preterm have evaluated only a limited number of tracts simultaneously. The current study compares diffusion properties along 18 major cerebral white matter pathways in children and adolescents born preterm (n = 27) and full term (n = 19), using diffusion magnetic resonance imaging and tractography. We found that compared to the full term group, the preterm group had significantly decreased FA in segments of the bilateral uncinate fasciculus and anterior segments of the right inferior fronto-occipital fasciculus. Additionally, the preterm group had significantly increased FA in segments of the right and left anterior thalamic radiations, posterior segments of the right inferior fronto-occipital fasciculus, and the right and left inferior longitudinal fasciculus. Increased FA in the preterm group was generally associated with decreased radial diffusivity. These findings indicate that prematurity-related white matter differences in later childhood and adolescence do not affect all tracts in the periventricular zone and can involve both decreased and increased FA. Differences in the patterns of radial diffusivity and axial diffusivity suggest that the tissue properties underlying group FA differences may vary within and across white matter tracts. Distinctive diffusion properties may relate to variations in the timing of injury in the neonatal period, extent of white matter dysmaturity and/or compensatory processes in childhood.

Pretreatment with Resveratrol Prevents Neuronal Injury and Cognitive Deficits Induced by Perinatal Hypoxia-Ischemia in Rats

Despite advances in neonatal care, hypoxic-ischemic brain injury is still a serious clinical problem, which is responsible for many cases of perinatal mortality, cerebral palsy, motor impairment and cognitive deficits. Resveratrol, a natural polyphenol with important anti-oxidant and anti-inflammatory properties, is present in grapevines, peanuts and pomegranates. The aim of the present work was to evaluate the possible neuroprotective effect of resveratrol when administered before or immediately after a hypoxic-ischemic brain event in neonatal rats by analyzing brain damage, the mitochondrial status and long-term cognitive impairment. Our results indicate that pretreatment with resveratrol protects against brain damage, reducing infarct volume, preserving myelination and minimizing the astroglial reactive response. Moreover its neuroprotective effect was found to be long lasting, as behavioral outcomes were significantly improved at adulthood. We speculate that one of the mechanisms for this neuroprotection may be related to the maintenance of the mitochondrial inner membrane integrity and potential, and to the reduction of reactive oxygen species. Curiously, none of these protective features was observed when resveratrol was administered immediately after hypoxia-ischemia.

Sex differences in cell genesis, hippocampal volume and behavioral outcomes in a rat model of neonatal HI

Hypoxia-ischemia (HI) of the brain in near-term and term infants is a leading cause of infant mortality and lifelong disability but current therapeutic approaches remain limited. Males consistently display greater vulnerability to the deleterious consequences of HI in both humans and animal models. Neurogenesis increases after neonatal HI and offers a potential therapeutic target for recovery. The steroid hormone estradiol has been extensively explored as a neuroprotectant in adult models of stroke but with mixed results. Less consideration has been afforded to this naturally occurring agent in the developing brain, which has unique challenges from the adult. Using a model of term HI in the rat we have explored the impact of this insult on cell genesis in the hippocampus of males and females and the ability of estradiol treatment immediately after insult to restore function. Both short-term (3 days) and long-term (7 days) post-injury were assessed and revealed that only females had markedly increased cell genesis on the short-term but both sexes were increased long-term. A battery of behavioral tests revealed motor impairment in males and compromised episodic memory while both sexes were modestly impaired in spatial memory. Juvenile social play was also depressed in both sexes after HI. Estradiol therapy improved behavioral performance in both sexes but did not reverse a deficit in hippocampal volume ipsilateral to the insult. Thus the effects of estradiol do not appear to be via cell death or proliferation but rather involve other components of neural functioning.

Antioxidant Treatments Recover the Alteration of Auditory-Evoked Potentials and Reduce Morphological Damage in the Inferior Colliculus after Perinatal Asphyxia in Rat

Maturation of the auditory pathway is dependent on the central nervous system myelination and it can be affected by pathologies such as neonatal hypoxic ischemic (HI) encephalopathy. Our aim was to evaluate the functional integrity of the auditory pathway and to visualize, by histological and cellular methods, the damage to the brainstem using a neonatal rat model of HI brain injury. To carry out this morphofunctional evaluation, we studied the effects of the administration of the antioxidants nicotine, melatonin, resveratrol and docosahexaenoic acid after hypoxia-ischemia on the inferior colliculus and the auditory pathway. We found that the integrity of the auditory pathway in the brainstem was altered as a consequence of the HI insult. Thus, the auditory brainstem response (ABR) showed increased I-V and III-V wave latencies. At a histological level, HI altered the morphology of the inferior colliculus neurons, astrocytes and oligodendricytes, and at a molecular level, the mitochondria membrane potential and integrity was altered during the first hours after the HI and reactive oxygen species (ROS) activity is increased 12 h after the injury in the brainstem. Following antioxidant treatment, ABR interpeak latency intervals were restored and the body and brain weight was recovered as well as the morphology of the inferior colliculus that was similar to the control group. Our results support the hypothesis that antioxidant treatments have a protective effect on the functional changes of the auditory pathway and on the morphological damage which occurs after HI insult.

PAI-1-derived peptide EEIIMD prevents hypoxia/ischemia-induced aggravation of endothelin- and thromboxane-induced cerebrovasoconstriction

BACKGROUND

Babies are frequently exposed to cerebral hypoxia and ischemia (H/I) during the perinatal period as a result of stroke, problems with delivery or post delivery respiratory management. The sole FDA approved treatment for acute stroke is tissue-type plasminogen activator (tPA). Endogenous tPA is upregulated and potentiates impairment of pial artery dilation in response to hypotension after H/I in pigs. Mitogen-activated protein kinase (MAPK), a family of at least 3 kinases, ERK, p38 and JNK, is also upregulated after H/I, with ERK contributing to impaired vasodilation. This study examined the hypothesis that H/I aggravates the vascular response to two important procontractile mediators released during CNS ischemia, endothelin-1 (ET-1) and thromboxane, which is further enhanced by tPA and ERK MAPK.

METHODS

Cerebral hypoxia (pO(2) 35 mmHg for 10 min via inhalation of N(2)) followed immediately by ischemia (global intracranial pressure elevation for 20 min) was produced in chloralose anesthetized piglets equipped with a closed cranial window.

RESULTS

H/I aggravated pial artery vasconstriction induced by ET-1 and the thromboxane mimetic U 46619. Potentiated vasoconstrictor responses were blocked by EEIIMD, an inhibitor of tPA's signaling and vascular activities, but unchanged by its inactive analogue EEIIMR. The cerebrospinal fluid concentration of ERK MAPK determined by ELISA was increased by H/I, potentiated by tPA, but blocked by EEIIMD. The ERK MAPK antagonist U 0126 blocked H/I augmented enhancement of ET-1 and U 46619 vasoconstriction.

CONCLUSIONS

These data indicate that H/I aggravates ET-1 and thromboxane mediated cerebral vasoconstriction by upregulating endogenous tPA and ERK MAPK.

Reduced thalamic volume in preterm infants is associated with abnormal white matter metabolism independent of injury

INTRODUCTION

Altered thalamocortical development is hypothesized to be a key substrate underlying neurodevelopmental disabilities in preterm infants. However, the pathogenesis of this abnormality is not well-understood. We combined magnetic resonance spectroscopy of the parietal white matter and morphometric analyses of the thalamus to investigate the association between white matter metabolism and thalamic volume and tested the hypothesis that thalamic volume would be associated with diminished N-acetyl-aspartate (NAA), a measure of neuronal/axonal maturation, independent of white matter injury.

METHODS

Data from 106 preterm infants (mean gestational age at birth: 31.0 weeks ± 4.3; range 23-36 weeks) who underwent MR examinations under clinical indications were included in this study.

RESULTS

Linear regression analyses demonstrated a significant association between parietal white matter NAA concentration and thalamic volume. This effect was above and beyond the effect of white matter injury and age at MRI and remained significant even when preterm infants with punctate white matter lesions (pWMLs) were excluded from the analysis. Furthermore, choline, and among the preterm infants without pWMLs, lactate concentrations were also associated with thalamic volume. Of note, the associations between NAA and choline concentration and thalamic volume remained significant even when the sample was restricted to neonates who were term-equivalent age or older.

CONCLUSION

These observations provide convergent evidence of a neuroimaging phenotype characterized by widespread abnormal thalamocortical development and suggest that the pathogenesis may involve impaired axonal maturation.

Could cord blood cell therapy reduce preterm brain injury?

Major advances in neonatal care have led to significant improvements in survival rates for preterm infants, but this occurs at a cost, with a strong causal link between preterm birth and neurological deficits, including cerebral palsy (CP). Indeed, in high-income countries, up to 50% of children with CP were born preterm. The pathways that link preterm birth and brain injury are complex and multifactorial, but it is clear that preterm birth is strongly associated with damage to the white matter of the developing brain. Nearly 90% of preterm infants who later develop spastic CP have evidence of periventricular white matter injury. There are currently no treatments targeted at protecting the immature preterm brain. Umbilical cord blood (UCB) contains a diverse mix of stem and progenitor cells, and is a particularly promising source of cells for clinical applications, due to ethical and practical advantages over other potential therapeutic cell types. Recent studies have documented the potential benefits of UCB cells in reducing brain injury, particularly in rodent models of term neonatal hypoxia–ischemia. These studies indicate that UCB cells act via anti-inflammatory and immuno-modulatory effects, and release neurotrophic growth factors to support the damaged and surrounding brain tissue. The etiology of brain injury in preterm-born infants is less well understood than in term infants, but likely results from episodes of hypoperfusion, hypoxia–ischemia, and/or inflammation over a developmental period of white matter vulnerability. This review will explore current knowledge about the neuroprotective actions of UCB cells and their potential to ameliorate preterm brain injury through neonatal cell administration. We will also discuss the characteristics of UCB-derived from preterm and term infants for use in clinical applications.

Patent ductus arteriosus ligation and adverse outcomes: causality or bias?

Observational studies have associated patent ductus arteriosus (PDA) ligation in preterm infants with increased chronic lung disease (CLD), retinopathy of prematurity, and neurodevelopmental impairment at long-term follow-up. Although the biological rationale for this association is incompletely understood, there is an emerging secular trend toward a permissive approach to the PDA. However, insufficient adjustment for postnatal, pre-ligation confounders, such as intraventricular hemorrhage and the duration and intensity of mechanical ventilation, suggests the presence of residual bias due to confounding by indication, and obliges caution in interpreting the ligation-morbidity relationship. A period of conservative management after failure of medical PDA closure may be considered to reduce the number of infants treated with surgery. Increased mortality and CLD in infants with persistent symptomatic PDA suggests that surgical ligation remains an important treatment modality for preterm infants.

Creatine supplementation during pregnancy: summary of experimental studies suggesting a treatment to improve fetal and neonatal morbidity and reduce mortality in high-risk human pregnancy

While the use of creatine in human pregnancy is yet to be fully evaluated, its long-term use in healthy adults appears to be safe, and its well documented neuroprotective properties have recently been extended by demonstrations that creatine improves cognitive function in normal and elderly people, and motor skills in sleep-deprived subjects. Creatine has many actions likely to benefit the fetus and newborn, because pregnancy is a state of heightened metabolic activity, and the placenta is a key source of free radicals of oxygen and nitrogen. The multiple benefits of supplementary creatine arise from the fact that the creatine-phosphocreatine [PCr] system has physiologically important roles that include maintenance of intracellular ATP and acid–base balance, post-ischaemic recovery of protein synthesis, cerebral vasodilation, antioxidant actions, and stabilisation of lipid membranes. In the brain, creatine not only reduces lipid peroxidation and improves cerebral perfusion, its interaction with the benzodiazepine site of the GABA_A receptor is likely to counteract the effects of glutamate excitotoxicity – actions that may protect the preterm and term fetal brain from the effects of birth hypoxia. In this review we discuss the development of creatine synthesis during fetal life, the transfer of creatine from mother to fetus, and propose that creatine supplementation during pregnancy may have benefits for the fetus and neonate whenever oxidative stress or feto-placental hypoxia arise, as in cases of fetal growth restriction, premature birth, or when parturition is delayed or complicated by oxygen deprivation of the newborn.

Prophylactic erythropoietin exacerbates ventilation-induced lung inflammation and injury in preterm lambs

Ventilation-induced lung injury (VILI) of preterm neonates probably contributes to the pathogenesis of bronchopulmonary dysplasia (BPD). Erythropoietin (EPO) has been suggested as a therapy for BPD. The aim of this study was to determine whether prophylactic administration of EPO reduces VILI in preterm newborn lambs. Lambs at 126 days of gestation (term is 147 days) were delivered and ventilated with a high tidal volume strategy for 15 min to cause lung injury, then received gentle ventilation until 2 h of age. Lambs were randomized to receive intravenous EPO (5000 IU kg(-1): Vent+EPO; n = 6) or phosphate-buffered saline (Vent; n = 7) soon after birth: unventilated controls (UVC; n = 8) did not receive ventilation or any treatment. Physiological parameters were recorded throughout the experimental procedure. Samples of lung were collected for histological and molecular assessment of inflammation and injury. Samples of liver were collected to assess the systemic acute phase response. Vent+EPO lambs received higher F IO 2, P aO 2 and oxygenation during the first 10 min than Vent lambs. There were no differences in physiological indices beyond this time. Total lung injury score, airway wall thickness, inflammation and haemorrhage were higher in Vent+EPO lambs than in Vent lambs. Lung inflammation and early markers of lung and systemic injury were elevated in ventilated lambs relative to unventilated lambs; EPO administration further increased lung inflammation and markers of lung and systemic injury. Prophylactic EPO exacerbates VILI, which may increase the incidence and severity of long-term respiratory disease. More studies are required before EPO can be used for lung protection in preterm infants.

RBC-coupled tPA Prevents Whereas tPA Aggravates JNK MAPK-Mediated Impairment of ATP- and Ca-Sensitive K Channel-Mediated Cerebrovasodilation After Cerebral Photothrombosis

The sole Food and Drug Administration-approved treatment for acute stroke is tissue-type plasminogen activator (tPA), but tPA aggravates impairment of cerebrovasodilation during hypotension in a newborn pig photothrombotic model of stroke. Coupling to carrier red blood cells (RBC) enhances thrombolytic effects of tPA, while reducing its side effects. ATP- and Ca-sensitive K channels (Katp and Kca) are important regulators of cerebrovascular tone and mediate cerebrovasodilation during hypotension. Mitogen-activated protein kinase, a family of at least three kinases, ERK, p38, and c-Jun-N-terminal kinase (JNK), is upregulated after photothrombosis. This study examined the effect of photothrombosis on Katp- and Kca-induced cerebrovasodilation and the roles of tPA and JNK during/after injury. Photothrombosis blunted vasodilation induced by the Katp agonists cromakalim, calcitonin gene-related peptide, and the Kca agonist NS 1619, which was aggravated by injection of tPA. In contrast, both pre- or post-injury thrombosis injection of RBC-tPA and JNK antagonist SP 600125 prevented impairment of Katp- and Kca-induced vasodilation. Therefore, JNK activation in thrombosis impairs K channel-mediated cerebrovasodilation. Standard thrombolytic therapy of central nervous system ischemic disorders using free tPA poses the danger of further dysregulation of cerebrohemodynamics by impairing cation-mediated control of cerebrovascular tone, whereas RBC-coupled tPA both restores reperfusion and normalizes cerebral hemodynamics.