Surgical interventions and short-term outcomes for preterm infants with post-haemorrhagic hydrocephalus: a multicentre cohort study.

OBJECTIVE: To (1) describe differences in types and timing of interventions, (2) report short-term outcomes and (3) describe differences among centres from a large national cohort of preterm infants with post-haemorrhagic hydrocephalus (PHH). DESIGN: Cohort study of the Children's Hospitals Neonatal Database from 2010 to 2022. SETTING: 41 referral neonatal intensive care units (NICUs) in North America. PATIENTS: Infants born before 32 weeks' gestation with PHH defined as acquired hydrocephalus with intraventricular haemorrhage. INTERVENTIONS: (1) No intervention, (2) temporising device (TD) only, (3) initial permanent shunt (PS) and (4) TD followed by PS (TD-PS). MAIN OUTCOME MEASURES: Mortality and meningitis. RESULTS: Of 3883 infants with PHH from 41 centres, 36% had no surgical intervention, 16% had a TD only, 19% had a PS only and 30% had a TD-PS. Of the 46% of infants with TDs, 76% were reservoirs; 66% of infants with TDs required PS placement. The percent of infants with PHH receiving ventricular access device placement differed by centre, ranging from 4% to 79% (p<0.001). Median chronological and postmenstrual age at time of TD placement were similar between infants with only TD and those with TD-PS. Infants with TD-PS were older and larger than those with only PS at time of PS placement. Death before NICU discharge occurred in 12% of infants, usually due to redirection of care. Meningitis occurred in 11% of the cohort. CONCLUSIONS: There was significant intercentre variation in rate of intervention, which may reflect variability in care or referral patterns. Rate of PS placement in infants with TDs was 66%.

Differential Susceptibility to Propofol and Ketamine in Primary Cultures of Young and Senesced Astrocytes.

The adverse effects of general anesthesia on the long-term cognition of young children and senior adults have become of concern in recent years. Previously, mechanistic and pathogenic investigations focused on neurons, and little is known about the effect of commonly used intravenous anesthetics such as propofol and ketamine on astrocytes. Recently, astrocyte dysfunction has been implicated in a wide range of age-related brain diseases. In this study, we examined the survival and viability of both young and senescent astrocytes in culture after adding propofol and ketamine to the media at varying strengths. Oxidative stimulus was applied to commercially available fetal cell lines of human astrocytes in vitro to induce morphological changes in cellular senescence. Our results indicate that propofol reduces the survival of young astrocytes as compared to controls, as well as to ketamine. These effects were seen in comparisons of total cell count and at both high and low dose concentrations. High doses of propofol also significantly reduced cell viability compared to those exposed to baseline controls and ketamine. Senescent astrocytes, on the other hand, demonstrated cell count reductions as compared to baseline controls and ketamine when exposed to either DMSO or propofol. The data show differential susceptibility of young astrocytes to propofol than to ketamine. The observed cell count reduction may be related to the adverse effects of propofol on mitochondrial function and free radical production, as described in previous studies. We speculate that ketamine may have a more favorable safety profile in infants and young children.

Chitin-Derived AVR-48 Prevents Experimental Bronchopulmonary Dysplasia (BPD) and BPD-Associated Pulmonary Hypertension in Newborn Mice.

Bronchopulmonary dysplasia (BPD) is the most common complication of prematurity and a key contributor to the large health care burden associated with prematurity, longer hospital stays, higher hospital costs, and frequent re-hospitalizations of affected patients through the first year of life and increased resource utilization throughout childhood. This disease is associated with abnormal pulmonary function that may lead to BPD-associated pulmonary hypertension (PH), a major contributor to neonatal mortality and morbidity. In the absence of any definitive treatment options, this life-threatening disease is associated with high resource utilization during and after neonatal intensive care unit (NICU) stay. The goal of this study was to test the safety and efficacy of a small molecule derivative of chitin, AVR-48, as prophylactic therapy for preventing experimental BPD in a mouse model. Two doses of AVR-48 were delivered either intranasally (0.11 mg/kg), intraperitoneally (10 mg/kg), or intravenously (IV) (10 mg/kg) to newborn mouse pups on postnatal day (P)2 and P4. The outcomes were assessed by measuring total inflammatory cells in the broncho-alveolar lavage fluid (BALF), chord length, septal thickness, and radial alveolar counts of the alveoli, Fulton's Index (for PH), cell proliferation and cell death by immunostaining, and markers of inflammation by Western blotting and ELISA. The bioavailability and safety of the drug were assessed by pharmacokinetic and toxicity studies in both neonatal mice and rat pups (P3-P5). Following AVR-48 treatment, alveolar simplification was improved, as evident from chord length, septal thickness, and radial alveolar counts; total inflammatory cells were decreased in the BALF; Fulton's Index was decreased and lung inflammation and cell death were decreased, while angiogenesis and cell proliferation were increased. AVR-48 was found to be safe and the no-observed-adverse-effect level (NOAEL) in rat pups was determined to be 100 mg/kg when delivered via IV dosing with a 20-fold safety margin. With no reported toxicity and with a shorter half-life, AVR-48 is able to reverse the worsening cardiopulmonary phenotype of experimental BPD and BPD-PH, compared to controls, thus positioning it as a future drug candidate.

Epidermal Growth Factor Receptor Inhibition Reverses Cellular and Transcriptomic Alterations Induced by Hypoxia in the Neonatal Piglet Brain.

Acute hypoxia (HX) causes extensive cellular damage in the developing human cerebral cortex. We found increased expression of activated-EGFR in affected cortical areas of neonates with HX and investigated its functional role in the piglet, which displays a highly evolved, gyrencephalic brain, with a human-like maturation pattern. In the piglet, HX-induced activation of EGFR and Ca2+/calmodulin kinase IV (CaMKIV) caused cell death and pathological alterations in neurons and glia. EGFR blockade inhibited CaMKIV activation, attenuated neuronal loss, increased oligodendrocyte proliferation, and reversed HX-induced astrogliosis. We performed for the first time high-throughput transcriptomic analysis of the piglet cortex to define molecular responses to HX and to uncover genes specifically involved in EGFR signaling in piglet and human brain injury. Our results indicate that specific molecular responses modulated by EGFR may be targeted as a therapeutic strategy for HX injury in the neonatal brain.

Noninvasive monitoring of brain edema after hypoxia in newborn piglets.

BackgroundDevelopment of cerebral edema after brain injury carries a high risk for brain damage and death. The present study tests the ability of a noninvasive cerebral edema monitoring system that uses near-infrared spectroscopy (NIRS) with water as the chromophore of interest to detect brain edema following hypoxia.MethodsVentilated piglets were exposed to hypoxia for 1 h, and then returned to normal oxygen levels for 4 h. An NIRS sensor was placed on the animal's head at baseline, and changes in light attenuation were converted to changes in H2O. Cerebral water content and aquaporin-4 protein (AQP4) expression were measured.ResultsThe system detected changes in NIRS-derived water signal as early as 2 h after hypoxia, and provided fivefold signal amplification, representing a 10% increase in brain water content and a sixfold increase in AQP4, 4 h after hypoxia. Changes in water signal correlated well with changes in cerebral water content (R=0.74) and AQP4 expression (R=0.97) in the piglet brain.ConclusionThe data show that NIRS can detect cerebral edema early in the injury process, thus providing an opportunity to initiate therapy at an earlier and more effective time-point after an insult than is available with current technology.

Effect of Concurrent Src Kinase Inhibition with Short-Duration Hypothermia on Ca2+/Calmodulin Kinase IV Activity and Neuropathology after Hypoxia-Ischemia in the Newborn Swine Brain.

BACKGROUND: Hypoxia-ischemia (HI) results in increased activation of Ca2+/calmodulin kinase IV (CaM kinase IV) mediated by Src kinase. Therapeutic hypothermia ameliorates neuronal injury in the newborn. HYPOTHESIS: Inhibition of Src kinase concurrently with hypothermia further attenuates the hypoxia-induced increased activation of CaM kinase IV compared with hypothermia alone. DESIGN/METHODS: Ventilated piglets were exposed to HI, received saline or a selective Src kinase inhibitor (PP2), and were cooled to 33°C. Neuropathology, adenosine triphosphate (ATP) and phosphocreatine (PCr) concentrations, and CaM kinase IV activity were determined. RESULTS: The neuropathology mean score (mean ± SD) was 0.4 ± 0.43 in normoxia-normothermia (p < 0.05 vs. hypoxia-normothermia), 3.5 ± 0.89 in hypoxia-normothermia (p < 0.05 vs. normoxia-normothermia), 0.7 ± 0.73 in hypoxia-hypothermia (p < 0.05 vs. normoxia-normothermia), and 0.5 ± 0.70 in normoxia-hypothermia (p < 0.05 vs. hypoxia-normothermia). The CaM kinase IV activity in cerebral tissue (pmol Pi/mg protein/min; mean ± SD) was 2,002 ± 729 in normoxia-normothermia, 1,704 ± 18 in normoxia-hypothermia, 6,017 ± 2,510 in hypoxia-normothermia, 4,104 ± 542 in hypoxia-hypothermia (p < 0.05 vs. normoxia-hypothermia), and 2,165 ± 415 in hypoxia-hypothermia with PP2 (p < 0.05 vs. hypoxia-hypothermia). The hypoxic groups with and without hypothermia or Src kinase inhibitor were comparable in the levels of ATP and PCr, indicating that they were similar in their degree of energy failure prior to treatments. Hypothermia or Src kinase inhibitor (PP2) did not restore the ATP and PCr levels. CONCLUSIONS: Hypothermia and Src kinase inhibition attenuated apoptotic cell death and improved neuropathology after hypoxia. The combination of short-duration hypothermia with Src kinase inhibition following hypoxia further attenuates the increased activation of CaM kinase IV compared to hypothermia alone in the newborn swine brain.

Effect of sustained postnatal systemic inflammation on hippocampal volume and function in mice.

BACKGROUND: Premature infants are at risk for persistent neurodevelopmental impairment. Children born preterm often exhibit reduced hippocampal volumes that correlate with deficits in working memory. Perinatal inflammation is associated with preterm birth and brain abnormalities. Here we examine the effects of postnatal systemic inflammation on the developing hippocampus in mice. METHODS: Pups received daily intraperitoneal injections of lipopolysaccharide (LPS) or saline between days 3 and 13. Ex vivo magnetic resonance imaging (MRI) and microscopic analysis of brain tissue was performed on day 14. Behavioral testing was conducted at 8-9 wk of age. RESULTS: MR and microscopic analysis revealed a 15-20% reduction in hippocampal volume in LPS-treated mice compared with controls. Behavioral testing revealed deficits in hippocampal-related tasks in LPS-treated animals. Adult mice exposed to LPS during the postnatal period were unable to select a novel environment when re-placed within a 1-min delay, were less able to remember a familiar object after a 1-h delay, and had impaired retention of associative fear learning after 24 h. CONCLUSION: Systemic inflammation sustained during the postnatal period contributes to reduced hippocampal volume and deficits in hippocampus-dependent working memory. These findings support the novel and emerging concept that sustained systemic inflammation contributes to neurodevelopmental impairment among preterm infants.

Steroids and injury to the developing brain: net harm or net benefit?

Deleterious effects result from both glucocorticoid insufficiency and excess glucocorticoid tissue exposure in the developing brain. Accumulating evidence suggests a net benefit of postnatal glucocorticoid therapy when administered shortly after the first week of life to premature infants with early and persistent pulmonary dysfunction, particularly in those with evidence of relative adrenal insufficiency. The decision to treat with steroids should ensure maximum respiratory benefit at the lowest possible neurologic risk, while avoiding serious systemic complications. Ongoing clinical trials must validate this approach.

Effect of concurrent administration of apoptotic inhibitors and hypothermia on post hypoxic cerebral injury in the newborn.

Neonatal hypoxic-ischemic encephalopathy is known to cause long-term neurodevelopmental impairment. Experimental studies and clinical trials demonstrated that treatment with hypothermia after hypoxic-ischemic insults reduced brain injury. As a result of these data, hypothermia has emerged as the standard of care for treatment of neonatal hypoxic-ischemic encephalopathy. However up to 40% of newborns with hypoxic-ischemic encephalopathy who are treated with hypothermia have significant neurocognitive deficits on follow-up. Obviously, there remains a need to further optimize cooling strategies and to identify adjuvant therapies that could potentially augment the neuroprotective effects and accentuate neuroprotection by hypothermia. As the occurrence of hypoxia in the newborn brain can not be predicted beforehand, the only opportunity we have to improve outcomes after hypoxic-ischemic encephalopathy is to pursue neuroprotective strategies that can be used as an adjunct to therapeutic hypothermia in the post-hypoxia-ischemia period, with special emphasis on mechanism mediating the early stages of hypoxic injury. Previously, we have demonstrated in the newborn piglet that within one hour of exposure to hypoxia, there is increased activation of the enzyme Ca++/calmodulin kinase (CaM Kinase) IV localized in the nucleus, a key regulator of transcription of apoptotic genes. We have also demonstrated that the hypoxia-induced enzyme CaM kinase IV activation is mediated by activation of two protein tyrosine kinases, Src kinase and EGFR kinase and by increased Ca++ influx into the nucleus. Inhibition of Src kinase by the selective inhibitor PP2 and of EGFR kinase by the selective inhibitor PD168393 at the onset of hypoxia prevented CaM kinase IV activation and decreased subsequent hypoxia-induced neuronal death. The aim of this study was to test the hypothesis that the combined treatment with hypothermia and PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), a highly selective inhibitor of Src kinase, immediately after the hypoxic insult may augment the beneficial effect of hypothermia on hypoxia/ischemia- induced neuronal necrosis. To this aim we assessed the levels of CaM Kinase IV activity as well as the levels of Na+-K+-ATPase in the Cerebral Cortex of Newborn Piglets exposed experimental hypoxia that were treated with hypothermia with or without concomitant PP2 administration. 2-3 day old piglets were anesthetized and ventilated. In conclusion, our preliminary data show that concurrent administration of Src kinase inhibitor in combination with induction of whole body hypothermia results in augmented neuroprotection as indicated by further attenuation of hypoxic-ischemic induced CaM kinase IV activation and improvement in neuronal membrane integrity compared to hypothermia alone.

Maternal glucocorticoid exposure alters tight junction protein expression in the brain of fetal sheep.

We examined the expression of tight junction (TJ) proteins in the cerebral cortex, cerebellum, and spinal cord of fetuses after maternal treatment with single and multiple courses of dexamethasone. Ewes received either single courses of four 6-mg dexamethasone or placebo injections every 12 h for 48 h between 104 and 107 days or the same treatment once a week between 76-78 and 104-107 days of gestation. TJ protein expression was determined by Western immunoblot analysis on tissue harvested at 105-108 days of gestation. Blood-brain barrier permeability has been previously quantified with the blood-to-brain transfer constant (K(i)) with alpha-aminoisobutyric acid (39). After a single course of dexamethasone, claudin-5 increased (P < 0.05) in the cerebral cortex, occludin and claudin-1 increased in the cerebellum, and occludin increased in the spinal cord. After multiple dexamethasone courses, occludin and zonula occludens (ZO)-1 increased in the cerebral cortex, and occludin and claudin-1 increased in the cerebellum. Junctional adhesion molecule-A and ZO-2 expressions did not change. Linear regression comparing K(i) to TJ proteins showed inverse correlations with claudin-1 and claudin-5 in the cerebral cortex after a single course and ZO-2 in the spinal cord after multiple courses and direct correlations with ZO-1 in the cerebellum and spinal cord after multiple courses. We conclude that maternal glucocorticoid treatment increases the expression of specific TJ proteins in vivo, patterns of TJ protein expression vary after exposure to single and multiple glucocorticoid courses, and decreases in blood-brain barrier permeability are associated with increases in claudin-1, claudin-5, and ZO-2 expression and decreases in ZO-1 expression. In utero glucocorticoid exposure alters the molecular composition of the barrier and affects fetal blood-brain barrier function.

Fetal inflammatory response and brain injury in the preterm newborn.

Preterm birth can be caused by intrauterine infection and maternal/fetal inflammatory responses. Maternal inflammation (chorioamnionitis) is often followed by a systemic fetal inflammatory response characterized by elevated levels of proinflammatory cytokines in the fetal circulation. The inflammation signal is likely transmitted across the blood-brain barrier and initiates a neuroinflammatory response. Microglial activation has a central role in this process and triggers excitotoxic, inflammatory, and oxidative damage in the developing brain. Neuroinflammation can persist over a period of time and sensitize the brain to subinjurious insults in early and chronic phases but may offer relative tolerance in the intermediate period through activation of endogenous anti-inflammatory, protective, and repair mechanisms. Neuroinflammatory injury not only destroys what exists but also changes what develops.

Na+, K+-ATPase activity and subunit isoform protein abundance: effects of antenatal glucocorticoids in the frontal cerebral cortex and renal cortex of ovine fetuses.

We examined the effects of single and multiple maternal glucocorticoid courses on cerebral cortical (CC) and renal cortical (RC) Na(+),K(+)-ATPase activity and protein isoform abundance in fetal sheep. Ewes received four dexamethasone or placebo injections in the single course (SC) groups, and the same treatment once a week for five-weeks in the multiple course (MC) groups. CC Na(+),K(+)-ATPase a(2)-abundance was higher (P<0.05) and beta(2)-abundance lower in the SC dexamethasone than placebo group, but Na(+),K(+)-ATPase activity did not change. CC Na(+),K(+)-ATPase activity, a(1)-, beta(1) -, and beta(2)-abundance were lower in the MC dexamethasone than placebo group, but a(2)- and a(3)-abundance did not change. Both dexamethasone courses did not affect CC cell number. RC Na(+),K(+)-ATPase activity, a(1)- and beta(1) -abundance were higher in the MC dexamethasone than placebo group, but did not change in the SC dexamethasone group. We conclude MC, but not a SC of dexamethasone, affect fetal cerebral and renal Na(+),K(+)-ATPase, and MC result in differential effects on Na(+),K(+)-ATPase in these organs.

Effects of maternal antenatal glucocorticoid treatment on apoptosis in the ovine fetal cerebral cortex.

We examined the effects of single and multiple maternal glucocorticoid courses on apoptosis in the cerebral cortices of ovine fetuses (CC). Ewes received single dexamethasone or placebo courses at 104-106 or 133-135 days or multiple courses between 76-78 and 104-106 days gestation. In the single-course groups, ewes received four 6 mg dexamethasone or placebo injections every 12 hr for 48 hr. Multiple-course groups received the same treatment once per week for 5 weeks. Neuronal and nonneuronal apoptotic cell numbers per square millimeter were determined with TUNEL and NeuN staining and with caspase-3 enzyme activity on CC tissues harvested at 106-108 (70%) or 135-137 (90%) days of gestation. Apoptotic cell numbers and caspase-3 activity were 50% lower (P < 0.02) after single placebo courses at 90% than 70% gestation; 90% of apoptotic cells were (P < 0.01) nonneuronal at both ages. Nonneuronal apoptotic cells and caspase-3 activity were 40% and 20% lower (P < 0.02) after single dexamethasone than placebo courses at 70%, but not 90%, gestation. Caspase-3 activity was 20% lower (P < 0.01) after multiple dexamethasone than placebo courses, but apoptotic cell number did not differ. We conclude that nonneuronal apoptosis represents the major form of apoptosis in the CC at both 70% and 90% of gestation. Apoptosis in nonneuronal cells decreases with maturity and after a single course of dexamethasone at 70%, but not at 90%, gestation and not after multiple courses at 70% gestation. We speculate that a single course of glucocorticoids exerts maturational changes on the rate of apoptosis in the cerebral cortex of preterm ovine fetuses.

Effects of maternal treatment with corticosteroids on tight junction protein expression in the cerebral cortex of the ovine fetus with and without exposure to in utero brain ischemia.

Maternal treatment with corticosteroids reduces blood-brain barrier permeability in premature ovine fetuses and the incidence of intraventricular hemorrhage in premature infants. We tested the hypothesis that maternally administered corticosteroids increase the expression of tight junction (TJ) proteins in the cerebral cortex of ovine fetuses with and without exposure to in utero brain ischemia. Fetuses at 80% of gestation were studied 18 h after the last of four 4-6 mg dexamethasone or placebo injections were given over 48 h to ewes. Groups were placebo/control, dexamethasone/control, placebo/ischemic, and dexamethasone/ischemic. Ischemia consisted of 30 min of fetal carotid artery occlusion and 72 h of reperfusion. Cerebral cortex was snap frozen. Western immunoblot was used to measure the protein expression of occludin, claudin-1, claudin-5, zonula occludens (ZO)-1, and ZO-2, and a TJ accessory protein annexin-ll. Occludin and annexin-ll protein expression were 48% and 58% higher (P<0.05) in the dexamethasone/ischemic than placebo/control group, respectively. Claudin-5 protein expression was 69% and 73% higher (P<0.05) in the placebo/ischemic and dexamethasone/ischemic than placebo/control group. Claudin-1 expression did not differ among groups. ZO-1 protein expression was 25%, 40%, and 55% lower in the dexamethasone/control, placebo/ischemic, and dexamethasone/ischemic than placebo/control group, respectively. ZO-2 expression was 45% and 70% lower (P<0.01) in the placebo/ischemic and dexamethasone/ischemic than placebo/control group. We conclude that maternal corticosteroid treatment differentially regulates the expression of component proteins of TJs in the cerebral cortex of fetuses exposed to brain ischemia. The functional significance of this differential regulation warrants further investigation.

Aortic dissection in a neonate: case report and review of the literature.

We report a case of aortic dissection causing hypertension in a neonate, which occurred following iatrogenic intimal injury during umbilical arterial cannulation. The intimal flap was diagnosed by color Doppler sonography, and treated by conservative management with complete spontaneous healing of the intimal injury.

Equal antipyretic effectiveness of oral and rectal acetaminophen: a randomized controlled trial [ISRCTN11886401].

BACKGROUND: The antipyretic effectiveness of rectal versus oral acetaminophen is not well established. This study is designed to compare the antipyretic effectiveness of two rectal acetaminophen doses (15 mg/kg) and (35 mg/kg), to the standard oral dose of 15 mg/kg. METHODS: This is a randomized, double-dummy, double-blind study of 51 febrile children, receiving one of three regimens of a single acetaminophen dose: 15 mg/kg orally, 15 mg/kg rectally, or 35 mg/kg rectally. Rectal temperature was monitored at baseline and hourly for a total of six hours. The primary outcome of the study, time to maximum antipyresis, and the secondary outcome of time to temperature reduction by at least 1 degrees C were analyzed by one-way ANOVA. Two-way ANOVA with repeated measures over time was used to compare the secondary outcome: change in temperature from baseline at times 1, 2, 3, 4, 5, and 6 hours among the three groups. Intent-to-treat analysis was planned. RESULTS: No significant differences were found among the three groups in the time to maximum antipyresis (overall mean = 3.6 hours; 95% CI: 3.2-4.0), time to fever reduction by 1 degrees C or the mean hourly temperature from baseline to 6 hours following dose administration. Hypothermia (temperature < 36.5 degrees C) occurred in 11(21.6%) subjects, with the highest proportion being in the rectal high-dose group. CONCLUSION: Standard (15 mg/kg) oral, (15 mg/kg) rectal, and high-dose (35 mg/kg) rectal acetaminophen have similar antipyretic effectiveness.

Bone mineralization in newborns whose mothers received magnesium sulphate for tocolysis of premature labour.

Prolonged maternal magnesium sulphate infusion therapy for tocolysis of premature labour may result in secondary fetal hypermagnesaemia, which has been associated with bony abnormalities in the newborn. We report on four infants, members of two twin pregnancies, who were exposed to prolonged fetal hypermagnesaemia. Three of the infants, all appropriate for gestational age, showed abnormal radiological findings consisting of abnormal mineralisation of long-bone metaphyses owing to fetal hypermagnesaemia. The fourth infant, who was growth retarded, had normal bones. Intrauterine growth restriction appears to be protective against magnesium sulphate-induced abnormal bone mineralisation in the newborn.