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OBJECTIVE The focus of this modified Delphi study was to investigate and build consensus regarding the medical management of children with moderate and severe acute spinal cord injury (SCI) during their initial inpatient hospitalization. This impetus for the study was based on the AANS/CNS guidelines for pediatric SCI published in 2013, which indicated that there was no consensus provided in the literature describing the medical management of pediatric patients with SCIs. METHODS An international, multidisciplinary group of 19 physicians, including pediatric neurosurgeons, orthopedic surgeons, and intensivists, were asked to participate. The authors chose to include both complete and incomplete injuries with traumatic as well as iatrogenic etiologies (e.g., spinal deformity surgery, spinal traction, intradural spinal surgery, etc.) due to the overall low incidence of pediatric SCI, potentially similar pathophysiology, and scarce literature exploring whether different etiologies of SCI should be managed differently. An initial survey of current practices was administered, and based on the responses, a follow-up survey of potential consensus statements was distributed. Consensus was defined as ≥ 80% of participants reaching agreement on a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree). A final meeting was held virtually to generate final consensus statements. RESULTS Following the final Delphi round, 35 statements reached consensus after modification and consolidation of previous statements. Statements were categorized into the following eight sections: inpatient care unit, spinal immobilization, pharmacological management, cardiopulmonary management, venous thromboembolism prophylaxis, genitourinary management, gastrointestinal/nutritional management, and pressure ulcer prophylaxis. All participants stated that they would be willing or somewhat willing to change their practices based on consensus guidelines. CONCLUSIONS General management strategies were similar for both iatrogenic (e.g., spinal deformity, traction, etc.) and traumatic SCIs. Steroids were recommended only for injury after intradural surgery, not after acute traumatic or iatrogenic extradural surgery. Consensus was reached that mean arterial pressure ranges are preferred for blood pressure targets following SCI, with goals between 80 and 90 mm Hg for children at least 6 years of age. Further multicenter study of steroid use following acute neuromonitoring changes was recommended.

Background: For long-stay patients (LSP) in pediatric intensive care units (PICU), frequently rotating providers can lead to ineffective information sharing and retention, varying goals and timelines, and delayed decisions, likely contributing to prolonged admissions. Primary intensivists (one physician serves as a consistent resource for the patient/family and PICU providers) and primary nurses (a small team of PICU nurses provide consistent bedside care) seek to augment usual transitory PICU care, by enhancing continuity and, potentially, decreasing length of stay (LOS). Methods: A single-centered, partially blinded randomized controlled trial of primary intensivists and nurses versus usual care. PICU patients admitted for or expected to be admitted for >10 days and who had ≥1 complex chronic condition were eligible. A block randomization with 1:1 allocation was used. The primary outcome was PICU LOS. Multiple secondary outcomes were explored. Results: Two hundred LSPs were randomized—half to receive primaries and half to usual care. The two groups were not significantly different in their baseline and admission characteristics. LSPs randomized to receive primaries had a shorter, but non-significant, mean LOS than those randomized to usual care (32.5 vs. 37.1 days, respectively, p = .19). Compared to LSPs in the usual care group, LSPs in the primary group had fewer unplanned intubations. Among LSPs that died, DNR orders were more prevalent in the primary group. Other secondary outcome and balance metrics were not significantly different between the two groups. Conclusion: Primary intensivists and nurses may be an effective strategy to counteract transitory PICU care and serve the distinctive needs of LSPs. However, additional studies are needed to determine the ways and to what extent they may accomplish this.

INTRODUCTIONTraumatic brain injury (TBI) is a debilitating neurological disorder caused by an impact to the head by an outside force. TBI results in persistent cognitive impairments, including fear generalization, the inability to distinguish between aversive and neutral stimuli. The mechanisms underlying fear generalization have not been fully elucidated, and there are no targeted therapeutics to alleviate this symptom of TBI.METHODSTo identify the neural ensembles mediating fear generalization, we utilized the ArcCreERT2x enhanced yellow fluorescent protein (EYFP) mice, which allow for activity-dependent labeling and quantification of memory traces. Mice were administered a sham surgery or the controlled cortical impact (CCI) model of TBI. Mice were then administered a contextual fear discrimination (CFD) paradigm and memory traces were quantified in numerous brain regions. In a separate group of mice, we tested if (R,S)-ketamine could decrease fear generalization and alter the corresponding memory traces in TBI mice.RESULTSTBI mice exhibited increased fear generalization when compared with sham mice. This behavioral phenotype was paralleled by altered memory traces in the DG, CA3, and amygdala, but not by alterations in inflammation or sleep. In TBI mice, (R,S)-ketamine facilitated fear discrimination and this behavioral improvement was reflected in DG memory trace activity.CONCLUSIONSThese data show that TBI induces fear generalization by altering fear memory traces, and that this deficit can be improved with a single injection of (R,S)-ketamine. This work enhances our understanding of the neural basis of TBI-induced fear generalization and reveals potential therapeutic avenues for alleviating this symptom.

Genomic assessment previously took months to result and was unable to impact clinical care in the pediatric intensive care unit (PICU). The advent of rapid exome sequencing potentially changes this. We investigated the impact of rapid exome sequencing in a pilot study on pediatric patients admitted to a single PICU with new-onset metabolic/neurologic disease.Rapid exome sequencing (7 days to verbal result) was performed on (n = 10) PICU patients age 6 years admitted with new-onset metabolic/neurologic disease. The primary outcome of interest was inpatient LOS, which served as a proxy for inpatient cost.A significant reduction in median LOS was identified when comparing PICU patients who underwent rapid exome sequencing to historical controls. From those patients who underwent rapid sequencing, five had likely pathogenic variants. In three cases with diagnostic genetic results, there was a modification to clinical care attributable to information provided by exome sequencing.This pilot study demonstrates that rapid exome sequencing is feasible to do in the PICU, that genetic results can be returned quickly enough to impact critical care decision-making and management. In a select population of PICU patients, this technology may contribute to a decrease in hospital length of stay.Ten prospectively enrolled PICU patients with defined clinical criteria and their parents underwent rapid exome sequencing. Fifty percent received a genetic diagnosis, and medical management was affected for 60% of those patients. Median hospital LOS was significantly decreased in this selective subset of PICU patients. Genetic disorders and congenital anomalies are a leading cause of pediatric mortality. Genomic assessment previously took weeks to months for results and was therefore unable to acutely impact clinical care in the pediatric intensive care unit (PICU). The recent advent of rapid exome sequencing changes this in selected patients. Rapid exome sequencing is feasible to do in a PICU. Genetic results can be returned quickly enough to impact critical care decision-making. When done in a carefully selected subset of pediatric patients, rapid exome sequencing can potentially decrease hospital LOS.

Rapid genetic sequencing is an established and important clinical tool for management of pediatric critical illness. The burden of risk variants in children with critical illness but a non-diagnostic exome has not been explored. This was a retrospective case-control analysis of research whole exome sequencing data that first underwent a diagnostic pipeline to assess the association of rare loss-of-function variants with critical illness in children with diagnostic and non-diagnostic whole exome sequencing including those with virally mediated respiratory failure. Using a gene-based collapsing approach, the odds of a child with critical illness carrying rare loss-of-function variants were compared to controls. A subset of children with virally mediated respiratory failure was also compared to controls. Cases were drawn from the general pediatric ward and pediatric intensive care unit (PICU) at Morgan Stanley Children’s Hospital of NewYork-Presbyterian (MSCH) – Columbia University Irving Medical Center (CUIMC) and from the Office of the Chief Medical Examiner (OCME) of New York City. Of the 285 enrolled patients, 228 (80.0%) did not receive a diagnosis from WES. After quality control filtering and geographic ancestry matching, an analysis of 232 children with critical illness compared to 5,322 healthy and unrelated controls determined cases to harbor more predicted loss-of-function (pLOFs) in genes with a LOEUF score ≤ 0.680 (p-value = 1.0 × 10−5). After quality control and geographic ancestry matching, a subset of 176 children without a genetic diagnosis compared to 5,180 controls harbored pLOFs in genes without a disease association (OR 1.7, CI [1.2 – 2.3], FDR adjusted p-value = 4.4 × 10−3) but not in genes with a disease association (OR 1.2, CI [0.8 – 1.7], FDR adjusted p-value = 0.40). This enrichment primarily existed among ultra-rare variants not found in public data sets. Among a subset of 25 previously healthy children with virally mediated respiratory failure compared to 2,973 controls after quality control and geographic ancestry matching, cases harbored more variants than controls in genes without a disease association at the same LOEUF threshold ≤ 0.680 (OR 2.8, CI [1.2 – 7.2], FDR adjusted p-value = 0.026) but not in genes with a disease association (OR 0.7, CI [0.2 – 2.2], FDR adjusted p-value = 0.84). Finally, children with critical illness for whom whole exome sequencing data from both biological parents were available, we found an enrichment of de novo pLOF variants in genes without a disease association among 114 children without a genetic diagnosis (unadjusted p-value < 0.05) but not among 46 children with a genetic diagnosis. Children with critical illness and non-diagnostic whole exome sequencing may still carry risk variants for their clinical presentation in genes not previously associated with disease.

Traumatic brain injury (TBI) can lead to neurodegenerative diseases such as Alzheimer's disease (AD) through mechanisms that remain incompletely characterized. Similar to AD, TBI models present with cellular metabolic alterations and modulated cleavage of amyloid precursor protein (APP). Specifically, AD and TBI tissues display increases in amyloid-β as well as its precursor, the APP C-terminal fragment of 99 a.a. (C99). Our recent data in cell models of AD indicate that C99, due to its affinity for cholesterol, induces the formation of transient lipid raft domains in the ER known as mitochondria-associated endoplasmic reticulum (ER) membranes ("MAM" domains). The formation of these domains recruits and activates specific lipid metabolic enzymes that regulate cellular cholesterol trafficking and sphingolipid turnover. Increased C99 levels in AD cell models promote MAM formation and significantly modulate cellular lipid homeostasis. Here, these phenotypes were recapitulated in the controlled cortical impact (CCI) model of TBI in adult mice. Specifically, the injured cortex and hippocampus displayed significant increases in C99 and MAM activity, as measured by phospholipid synthesis, sphingomyelinase activity and cholesterol turnover. In addition, our cell type-specific lipidomics analyses revealed significant changes in microglial lipid composition that are consistent with the observed alterations in MAM-resident enzymes. Altogether, we propose that alterations in the regulation of MAM and relevant lipid metabolic pathways could contribute to the epidemiological connection between TBI and AD.

Pediatricians caring for patients with child abuse or neglect (CABN) may experience secondary traumatic stress (STS) from traumatized patients, or burnout (BO) from workplace stress. This may be buffered by compassion satisfaction (CS), positive meaning from one’s work. For this study, STS, BO, and CS specific to a pediatrician’s care of CABN were assessed for residents, hospitalists, intensivists, and outpatient physicians. Using the Professional Quality of Life Scale modified for CABN experiences, participants (n = 62) had a mean STS score at the 84th percentile, a mean BO score at the 66th percentile, and a mean CS score at the 17th percentile. Reporting one CABN patient as most emotionally impactful predicted STS, caring for all types of CABN predicted BO, and perceived knowledge no longer predicted CS when adjusting for the experience of mandated reporting or CABN fatality. These results highlight the need to support pediatricians involved with CABN.

Cerebral edema and the subsequent increased intracranial pressure are associated with mortality and poor outcome following traumatic brain injury. Previous in vitro studies have shown that the Gibbs-Donnan effect, which describes the tendency of a porous, negatively charged matrix to attract positive ions and water, applies to brain tissue and that enzymatic reduction of the fixed charge density can prevent tissue swelling. We tested whether hyaluronidase, an enzyme that degrades the large, negatively charged glycosaminoglycan hyaluronan, could reduce brain edema after traumatic brain injury. In vivo, intracerebroventricular injection of hyaluronidase after controlled cortical impact in mice reduced edema in the ipsilateral hippocampus at 24 h by both the wet-weight/dry-weight method (78.15 ± 0.65% vs. 80.4 ± 0.46%; p 2-weighted magnetic resonance imaging (13.88 ± 3.09% vs. 29.23 ± 6.14%; p

ImportanceDiagnostic genetic testing can lead to changes in management in the pediatric intensive care unit. Genetic risk in children with critical illness but nondiagnostic exome sequencing (ES) has not been explored.ObjectiveTo assess the association between loss-of-function (LOF) variants and pediatric critical illness.Design, Setting, and ParticipantsThis genetic association study examined ES first screened for causative variants among 267 children at the Morgan Stanley Children’s Hospital of NewYork-Presbyterian, of whom 22 were otherwise healthy with viral respiratory failure; 18 deceased children with bronchiolitis from the Office of the Chief Medical Examiner of New York City, of whom 14 were previously healthy; and 9990 controls from the Institute for Genomic Medicine at Columbia University Irving Medical Center. The ES data were generated between January 1, 2015, and December 31, 2020, and analyzed between January 1, 2017, and September 2, 2022.ExposureCritical illness.Main Outcomes and MeasuresOdds ratios and P values for genes and gene-sets enriched for rare LOF variants and the loss-of-function observed/expected upper bound fraction (LOEUF) score at which cases have a significant enrichment.ResultsThis study included 285 children with critical illness (median [range] age, 4.1 [0-18.9] years; 148 [52%] male) and 9990 controls. A total of 228 children (80%) did not receive a genetic diagnosis. After quality control (QC), 231 children harbored excess rare LOF variants in genes with a LOEUF score of 0.680 or less (intolerant genes) (P = 1.0 × 10−5). After QC, 176 children without a diagnosis harbored excess ultrarare LOF variants in intolerant genes but only in those without a known disease association (odds ratio, 1.8; 95% CI, 1.3-2.5). After QC, 25 children with viral respiratory failure harbored excess ultrarare LOF variants in intolerant genes but only in those without a known disease association (odds ratio, 2.8; 95% CI, 1.1-6.6). A total of 114 undiagnosed children were enriched for de novo LOF variants in genes without a known disease association (observed, 14; expected, 6.8; enrichment, 2.05).Conclusions and RelevanceIn this genetic association study, excess LOF variants were observed among critically ill children despite nondiagnostic ES. Variants lay in genes without a known disease association, suggesting future investigation may connect phenotypes to causative genes.

Microglia, the resident immune cells of the brain, are crucial in the development of the nervous system. Recent evidence demonstrates that microglia modulate adult hippocampal neurogenesis by inhibiting cell proliferation of neural precursors and survival both in vitro and in vivo, thus maintaining a balance between cell division and cell death in the neural stem cell pool. There are increasing reports suggesting these microglia found in neurogenic niches differ from their counterparts in non-neurogenic areas. Here, we present evidence that microglia in the hippocampal neurogenic niche are a specialized population that express genes known to regulate neurogenesis. By comprehensively profiling myeloid lineage cells in the hippocampus using single cell RNA-sequencing, we resolve transcriptomic differences in microglia originating from the subgranular zone. These cells have lower expression of genes associated with homeostatic microglia and increased expression of genes associated with phagocytosis. Intriguingly, this small yet distinct population expresses a gene signature with substantial overlap with previously characterized phenotypes, including disease associated microglia (DAM), a particularly unique and compelling microglial state.

Polymorphisms in the apolipoprotein E (ApoE) gene confer a major genetic risk for the development of late-onset Alzheimer’s disease (AD) and are predictive of outcome following traumatic brain injury (TBI). Alterations in adult hippocampal neurogenesis have long been associated with both the development of AD and recovery following TBI, and ApoE is known to play a role in this process. In order to determine how ApoE might influence hippocampal injury-induced neurogenesis, we developed a novel conditional system whereby functional ApoE from astrocytes was ablated just prior to injury. While successfully ablating 90% of astrocytic ApoE just prior to a closed cortical impact injury in mice, we observed an attenuation in the development of newly born neurons using a GFP-expressing retrovirus, but not in existing hippocampal neurons visualized with a Golgi stain. Intriguingly, animals with a “double-hit”, i.e. injury and ApoE conditionally inactivated in astrocytes, demonstrated the most pronounced impairments in the hippocampal-dependent Morris water maze test, failing to exhibit spatial memory after both acquisition and reversal training trials. In comparison, conditional knockout mice without injury displayed impairments but only in the reversal phase of the test, suggesting accumulative effects of astrocytic ApoE deficiency and traumatic brain injury on AD-like phenotypes. Together, these findings demonstrate that astrocytic ApoE is required for functional injury-induced neurogenesis following traumatic brain injury.Significance StatementApoE has long been implicated in the development of Alzheimer’s disease and recovery from traumatic brain injury via unknown mechanisms. Using a novel conditional ablation model of mouse ApoE and subsequent tracing of individual hippocampal neurons, we demonstrate its requirement in injury-induced neurogenesis for proper dendritic arborization and cognitive function in hippocampal-dependent learning and memory tasks.

23 p.-5 fig.-3 tab.-1 graph. abst., Traumatic brain injury (TBI) can lead to neurodegenerative diseases such as Alzheimer’s disease (AD) through mechanisms that remain incompletely characterized. Similar to AD, TBI models present with cellular metabolic alterations and modulated cleavage of amyloid precursor protein (APP). Specifically, AD and TBI tissues display increases in amyloid-β as well as its precursor, the APP C-terminal fragment of 99 a.a. (C99). Our recent data in cell models of AD indicate that C99, due to its affinity for cholesterol, induces the formation of transient lipid raft domains in the ER known as mitochondria-associated endoplasmic reticulum (ER) membranes (“MAM” domains). The formation of these domains recruits and activates specific lipid metabolic enzymes that regulate cellular cholesterol trafficking and sphingolipid turnover. Increased C99 levels in AD cell models promote MAM formation and significantly modulate cellular lipid homeostasis. Here, these phenotypes were recapitulated in the controlled cortical impact (CCI) model of TBI in adult mice. Specifically, the injured cortex and hippocampus displayed significant increases in C99 and MAM activity, as measured by phospholipid synthesis, sphingomyelinase activity and cholesterol turnover. In addition, our cell type-specific lipidomics analyses revealed significant changes in microglial lipid composition that are consistent with the observed alterations in MAM-resident enzymes. Altogether, we propose that alterations in the regulation of MAM and relevant lipid metabolic pathways could contribute to the epidemiological connection between TBI and AD., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the U.S. National Institutes of Health (T32-DK007647 to RRA; R21NS125395 to LS; S10-OD016214 and P30-CA013330 to FPM; R01-EB029523 to WM; R01-NS095803 to SGK; R01-NS088197 to RJD; R01-AG056387 to EA-G) and the U.S. Department of Defense (National Defense Science and Engineering Graduate Fellowship, FA9550-11-C-0028, to RRA).

Supplemental Digital Content is available in the text., Objectives: The disease caused by severe acute respiratory syndrome coronavirus 2, known as coronavirus disease 2019, has resulted in a global pandemic. Reports are emerging of a new severe hyperinflammatory syndrome related to coronavirus disease 2019 in children and adolescents. The Centers for Disease Control and Prevention has designated this disease multisystem inflammatory syndrome in children. Our objective was to develop a clinical inpatient protocol for the evaluation, management, and follow-up of patients with this syndrome. Data Sources: The protocol was developed by a multidisciplinary team based on relevant literature related to coronavirus disease 2019, multisystem inflammatory syndrome in children, and related inflammatory syndromes, as well as our experience caring for children with multisystem inflammatory syndrome in children. Data were obtained on patients with multisystem inflammatory syndrome in children at our institution from the pre-protocol and post-protocol periods. Data Synthesis: Our protocol was developed in order to identify cases of multisystem inflammatory syndrome in children with high sensitivity, stratify risk to guide treatment, recognize co-infectious or co-inflammatory processes, mitigate coronary artery abnormalities, and manage hyperinflammatory shock. Key elements of evaluation include case identification using broad clinical characteristics and comprehensive laboratory and imaging investigations. Treatment centers around glucocorticoids and IV immunoglobulin with biologic immunomodulators as adjuncts. Multidisciplinary follow-up after discharge is indicated to manage continued outpatient therapy and evaluate for disease sequelae. In nearly 2 months, we admitted 54 patients with multisystem inflammatory syndrome in children, all of whom survived without the need for invasive ventilatory or mechanical circulatory support. After institution of this protocol, patients received earlier treatment and had shorter lengths of hospital stay. Conclusions: This report provides guidance to clinicians on evaluation, management, and follow-up of patients with a novel hyperinflammatory syndrome related to coronavirus disease 2019 known as multisystem inflammatory syndrome in children. It is based on the relevant literature and our experience. Instituting such a protocol during a global pandemic is feasible and is associated with patients receiving treatment and returning home more quickly.

The occurrence of dreaming during rapid eye movement (REM) sleep prompts interest in the role of REM sleep in hippocampal-dependent episodic memory. Within the mammalian hippocampus, the dentate gyrus (DG) has the unique characteristic of exhibiting neurogenesis persisting into adulthood. Despite their small numbers and sparse activity, adult-born neurons (ABNs) in the DG play critical roles in memory; however, their memory function during sleep is unknown. Here, we investigate whether young ABN activity contributes to memory consolidation during sleep using Ca 2+ imaging in freely moving mice. We found that contextual fear learning recruits a population of young ABNs that are reactivated during subsequent REM sleep against a backdrop of overall reduced ABN activity. Optogenetic silencing of this sparse ABN activity during REM sleep alters the structural remodeling of spines on ABN dendrites and impairs memory consolidation. These findings provide a causal link between ABN activity during REM sleep and memory consolidation.

This case series describes clinical characteristics, treatment, and outcomes of 17 previously healthy SARS-CoV-2-infected children and adolescents with an inflammatory phenotype overlapping with but distinct from Kawasaki disease and toxic shock syndrome admitted to a New York City hospital in late April and early May 2020.

Various brain injuries lead to the activation of adult neural stem/progenitor cells in the mammalian hippocampus. Subsequent injury-induced neurogenesis appears to be essential for at least some aspects of the innate recovery in cognitive function observed following traumatic brain injury (TBI). It has previously been established that Apolipoprotein E (ApoE) plays a regulatory role in adult hippocampal neurogenesis, which is of particular interest as the presence of the human ApoE isoform ApoE4 leads to significant risk for the development of late-onset Alzheimer's disease, where impaired neurogenesis has been linked with disease progression. Moreover, genetically modified mice lacking ApoE or expressing the ApoE4 human isoform have been shown to impair adult hippocampal neurogenesis under normal conditions. Here, we investigate how controlled cortical impact (CCI) injury affects dentate gyrus development using hippocampal stereotactic injections of GFP-expressing retroviruses in wild-type (WT), ApoE-deficient and humanized (ApoE3 and ApoE4) mice. Infected adult-born hippocampal neurons were morphologically analyzed once fully mature, revealing significant attenuation of dendritic complexity and spine density in mice lacking ApoE or expressing the human ApoE4 allele, which may help inform how ApoE influences neurological diseases where neurogenesis is defective.

Ongoing investigation from the Pediatric Anesthesia NeuroDevelopment Assessment (PANDA) study hopes to examine the long-term effect on cognitive and language development of a single anesthetic exposure in children undergoing inguinal hernia repair. The fifth PANDA Symposium, held in April 2016, continued the mission of previous symposia to examine evidence from basic science and clinical studies on potential neurotoxic effects of anesthetics on developing brain. At the 2016 Symposium, a panel of specialists from nonsurgical pediatric disciplines including anesthesiology, radiology, neurology, gastroenterology, oncology, cardiology, and critical care reviewed use of anesthesia in their practices, including how concern over possible neurodevelopmental effects of early childhood anesthetic exposure has changed discussion with patients and families regarding risks and benefits of imaging studies and interventional procedures involving sedation or anesthesia. This paper summarizes presentations from nonsurgical pediatric specialists at the 2016 PANDA Symposium.

Traumatic brain injury (TBI) is associated with adverse effects on brain functions, including sensation, language, emotions and/or cognition. Therapies for improving outcomes following TBI are limited. A better understanding of the pathophysiological mechanisms of TBI may suggest novel treatment strategies to facilitate recovery and improve treatment outcome. Aberrant activation of cyclin-dependent kinase 5 (Cdk5) has been implicated in neuronal injury and neurodegeneration. Cdk5 is a neuronal protein kinase activated via interaction with its cofactor p35 that regulates numerous neuronal functions, including synaptic remodeling and cognition. However, conversion of p35 to p25 via Ca(2+) -dependent activation of calpain results in an aberrantly active Cdk5/p25 complex that is associated with neuronal damage and cell death. Here, we show that mice subjected to controlled cortical impact (CCI), a well-established experimental TBI model, exhibit increased p25 levels and consistently elevated Cdk5-dependent phosphorylation of microtubule-associated protein tau and retinoblastoma (Rb) protein in hippocampal lysates. Moreover, CCI-induced neuroinflammation as indicated by increased astrocytic activation and number of reactive microglia. Brain-wide conditional Cdk5 knockout mice (Cdk5 cKO) subjected to CCI exhibited significantly reduced edema, ventricular dilation, and injury area. Finally, neurophysiological recordings revealed that CCI attenuated excitatory post-synaptic potential field responses in the hippocampal CA3-CA1 pathway 24 h after injury. This neurophysiological deficit was attenuated in Cdk5 cKO mice. Thus, TBI induces increased levels of p25 generation and aberrant Cdk5 activity, which contributes to pathophysiological processes underlying TBI progression. Hence, selectively preventing aberrant Cdk5 activity may be an effective acute strategy to improve recovery from TBI. Traumatic brain injury (TBI) increases astrogliosis and microglial activation. Moreover, TBI deregulates Ca(2+) -homeostasis triggering p25 production. The protein kinase Cdk5 is aberrantly activated by p25 leading to phosphorylation of substrates including tau and Rb protein. Loss of Cdk5 attenuates TBI lesion size, indicating that Cdk5 is a critical player in TBI pathogenesis and thus may be a suitable therapeutic target for TBI.

Partial recovery from even severe traumatic brain injury (TBI) is ubiquitous and occurs largely through unknown mechanisms. Recent evidence suggests that hippocampal neural stem/progenitor cell (NSPC) activation and subsequent neurogenesis are responsible for at least some aspects of spontaneous recovery following TBI. Apolipoprotein E (ApoE) regulates postnatal neurogenesis in the hippocampus and is therefore a putative mediator of injury-induced neurogenesis. Further, ApoE isoforms in humans are associated with different cognitive outcomes following TBI. To investigate the role of ApoE in injury-induced neurogenesis, we exposed wild-type, ApoE-deficient, and human ApoE isoform-specific (ApoE3 and ApoE4) transgenic mice crossed with nestin-green fluorescent protein (GFP) reporter mice to controlled cortical impact (CCI) and assessed progenitor activation at 2 d post-injury using unbiased stereology. GFP+ progenitor cells were increased by approximately 120% in the ipsilateral hippocampus in injured wild-type mice, compared with sham mice (p

In healthy adults, transfusion of older stored red blood cells (RBCs) produces extravascular hemolysis and circulating non–transferrin-bound iron. In a prospective, observational study of critically ill children, we examined the effect of RBC storage duration on the extent of hemolysis by comparing laboratory measurements obtained before, and 4 hr after, RBC transfusion (N = 100) or saline/albumin infusion (N = 20). Transfusion of RBCs stored for longer than 4 weeks significantly increased plasma free hemoglobin (P

pCH is an important risk factor for brain injury and long-term morbidity in children, occurring during the developmental stages of neurogenesis, neuronal migration, and myelination. We show that a rodent model of pCH results in an early decrease in mature myelin. Although pCH does increase progenitor oligodendrocytes in the developing brain, BrdU labeling revealed a loss in dividing progenitor oligodendrocytes, indicating a defect in mature cell replacement and myelinogenesis. Mice continued to exhibited hypomyelination, concomitant with long-term impairment of motor function, weeks after cessation of pCH. The implication of a novel neuroimmunologic interplay, pCH also induced a significant egress of infiltrating CD4 T cells into the developing brain. This pCH-mediated neuroinflammation included oligodendrocyte-directed autoimmunity, with an increase in peripheral myelin-specific CD4 T cells. Thus, both the loss of available, mature, myelin-producing glial cells and an active increase in autoreactive, myelin-specific CD4 T cell infiltration into pCH brains may contribute to early pCH-induced hypomyelination in the developing CNS. The elucidation of potential mechanisms of hypoxia-driven autoimmunity will expand our understanding of the neuroimmune axis during perinatal CNS disease states that may contribute to long-term functional disability.

Although a myriad of pathological responses contribute to traumatic brain injury (TBI), cerebral dysfunction has been closely linked to cell death mechanisms. A number of therapeutic strategies have been studied in an attempt to minimize or ameliorate tissue damage; however, few studies have evaluated the inherent protective capacity of the brain. Endogenous neural stem/progenitor cells (NSPCs) reside in distinct brain regions and have been shown to respond to tissue damage by migrating to regions of injury. Until now, it remained unknown whether these cells have the capacity to promote endogenous repair. We ablated NSPCs in the subventricular zone to examine their contribution to the injury microenvironment after controlled cortical impact (CCI) injury. Studies were performed in transgenic mice expressing the herpes simplex virus thymidine kinase gene under the control of the nestin(δ) promoter exposed to CCI injury. Two weeks after CCI injury, mice deficient in NSPCs had reduced neuronal survival in the perilesional cortex and fewer Iba-1-positive and glial fibrillary acidic protein-positive glial cells but increased glial hypertrophy at the injury site. These findings suggest that the presence of NSPCs play a supportive role in the cortex to promote neuronal survival and glial cell expansion after TBI injury, which corresponds with improvements in motor function. We conclude that enhancing this endogenous response may have acute protective roles after TBI.

OBJECTIVES We analyzed a prospective database of pediatric traumatic brain injury patients to identify predictors of outcome and describe the change in function over time. We hypothesized that neurologic status at hospital discharge would not reflect the long-term neurologic recovery state. DESIGN This is a descriptive cohort analysis of a single-center prospective database of pediatric traumatic brain injury patients from 2001 to 2012. Functional outcome was assessed at hospital discharge, and the Glasgow Outcome Scale Extended Pediatrics or Glasgow Outcome Scale was assessed on average at 15.8 months after injury. SETTING Children's Medical Center Dallas, a single-center PICU and Level 1 Trauma Center. PATIENTS Patients, 0-17 years old, with complicated-mild/moderate or severe accidental traumatic brain injury. MEASUREMENTS AND MAIN RESULTS Dichotomized long-term outcome was favorable in 217 of 258 patients (84%), 80 of 82 patients (98%) with complicated-mild/moderate injury and 133 of 172 severe patients (77%). In the bivariate analysis, younger age, motor vehicle collision as a mechanism of injury, intracranial pressure monitor placement, cardiopulmonary resuscitation at scene or emergency department, increased hospital length of stay, increased ventilator days (all with p < 0.01) and occurrence of seizures (p = 0.03) were significantly associated with an unfavorable outcome. In multiple regression analysis, younger age (p = 0.03), motor vehicle collision (p = 0.01), cardiopulmonary resuscitation (p < 0.01), and ventilator days (p < 0.01) remained significant. Remarkably, 28 of 60 children (47%) with an unfavorable Glasgow Outcome Scale at hospital discharge improved to a favorable outcome. In severe patients with an unfavorable outcome at hospital discharge, younger age was identified as a risk factor for remaining in an unfavorable condition (p = 0.1). CONCLUSIONS Despite a poor neurologic status at hospital discharge, many children after traumatic brain injury will significantly improve at long-term assessment. The factors most associated with outcomes were age, cardiopulmonary resuscitation, motor vehicle collision, intracranial pressure placement, days on a ventilator, hospital length of stay, and seizures. The factor most associated with improvement from an unfavorable neurologic status at discharge was being older.

Background The molecular mechanism underlying progressive memory loss in Alzheimer’s disease is poorly understood. Neurogenesis in the adult hippocampus is a dynamic process that continuously changes the dentate gyrus and is important for hippocampal plasticity, learning and memory. However, whether impairments in neurogenesis affect the hippocampal circuitry in a way that leads to memory deficits characteristic of Alzheimer’s disease is unknown. Controversial results in that regard were reported in transgenic mouse models of amyloidosis. Methods Here, we conditionally ablated adult neurogenesis in APPswe/PS1ΔE9 mice by crossing these with mice expressing nestin-driven thymidine kinase (δ-HSV-TK). Results These animals show impairment in performance in contextual conditioning and pattern separation tasks following depletion of neurogenesis. Importantly, these deficits were not observed in age-matched APPswe/PS1ΔE9 or δ-HSV-TK mice alone. Furthermore, we show that cognitive deficits were accompanied by the upregulation of hyperphosphorylated tau in the hippocampus and in immature neurons specifically. Interestingly, we observed upregulation of the immediate early gene Zif268 (Egr-1) in the dentate gyrus, CA1 and CA3 regions of the hippocampus following learning in the neurogenesis-depleted δ-HSV-TK mice. This may suggest overactivation of hippocampal neurons in these areas following depletion of neurogenesis. Conclusions These results imply that neurogenesis plays an important role in the regulation of inhibitory circuitry of the hippocampus. This study suggests that deficits in adult neurogenesis may contribute to cognitive impairments, tau hyperphosphorylation in new neurons and compromised hippocampal circuitry in Alzheimer’s disease. Electronic supplementary material The online version of this article (10.1186/s13024-017-0207-7) contains supplementary material, which is available to authorized users.

Because pediatric intensive care units (PICUs) improve survival for a range of acute diseases, attention has turned toward ensuring the best possible functional outcomes after critical illness. The neurocritical care of children is of increasing interest. However, the pediatric population encompasses a heterogeneous set of neurologic conditions, with several possible models of how best to address them. This article reviews the special challenges faced by PICUs with regards to diseases, technologies, and skills and the progress that has been made in treatment, monitoring, and prognostication. Recent advances in translational research expected to modify the field in the near-term are described.

Disrupted thyroid hormone function evokes severe physiological consequences in the immature brain. In adulthood, although clinical reports document an effect of thyroid hormone status on mood and cognition, the molecular and cellular changes underlying these behavioural effects are poorly understood. More recently, the subtle effects of thyroid hormone on structural plasticity in the mature brain, in particular on adult hippocampal neurogenesis, have come to be appreciated. However, the specific stages of adult hippocampal progenitor development that are sensitive to thyroid hormone are not defined. Using nestin-green fluorescent protein reporter mice, we demonstrate that thyroid hormone mediates its effects on hippocampal neurogenesis by influencing Type 2b and Type 3 progenitors, although it does not alter proliferation of either the Type 1 quiescent progenitor or the Type 2a amplifying neural progenitor. Thyroid hormone increases the number of doublecortin (DCX)-positive Type 3 progenitors, and accelerates neuronal differentiation into both DCX-positive immature neurones and neuronal nuclei-positive granule cell neurones. Furthermore, we show that this increase in neuronal differentiation is accompanied by a significant induction of specific transcription factors involved in hippocampal progenitor differentiation. In vitro studies using the neurosphere assay support a direct effect of thyroid hormone on progenitor development because neurospheres treated with thyroid hormone are shifted to a more differentiated state. Taken together, our results indicate that thyroid hormone mediates its neurogenic effects via targeting Type 2b and Type 3 hippocampal progenitors, and suggests a role for proneural transcription factors in contributing to the effects of thyroid hormone on neuronal differentiation of adult hippocampal progenitors.

Glioblastoma multiforme is the most common primary malignant brain tumour, with a median survival of about one year. This poor prognosis is due to therapeutic resistance and tumour recurrence after surgical removal. Precisely how recurrence occurs is unknown. Using a genetically engineered mouse model of glioma, here we identify a subset of endogenous tumour cells that are the source of new tumour cells after the drug temozolomide (TMZ) is administered to transiently arrest tumour growth. A nestin-ΔTK-IRES-GFP (Nes-ΔTK-GFP) transgene that labels quiescent subventricular zone adult neural stem cells also labels a subset of endogenous glioma tumour cells. On arrest of tumour cell proliferation with TMZ, pulse-chase experiments demonstrate a tumour re-growth cell hierarchy originating with the Nes-ΔTK-GFP transgene subpopulation. Ablation of the GFP+ cells with chronic ganciclovir administration significantly arrested tumour growth, and combined TMZ and ganciclovir treatment impeded tumour development. Thus, a relatively quiescent subset of endogenous glioma cells, with properties similar to those proposed for cancer stem cells, is responsible for sustaining long-term tumour growth through the production of transient populations of highly proliferative cells.

Using a transgenic mouse (Mus musculus) in which nestin-expressing progenitors are labeled with enhanced green fluorescent protein, we previously characterized the expression of excitatory amino acid transporter 2 (GltI) and excitatory amino acid transporter 1 (Glast) on early neural progenitors in vivo. To address their functional role in this cell population, we manipulated their expression in P7 neurospheres isolated from the dentate gyrus. We observed that knockdown of GltI or Glast was associated with decreased bromodeoxyuridine incorporation and neurosphere formation. Moreover, we determined that both glutamate transporters regulated progenitor proliferation in a calcium-dependent and metabotropic glutamate receptor-dependent manner. To address the relevance of this in vivo, we utilized models of acquired brain injury, which are known to induce hippocampal neurogenesis. We observed that GltI and Glast were specifically upregulated in progenitors following brain injury, and that this increased expression was maintained for many weeks. Additionally, we found that recurrently injured animals with increased expression of glutamate transporters within the progenitor population were resistant to subsequent injury-induced proliferation. These findings demonstrate that GltI and Glast negatively regulate calcium-dependent proliferation in vitro and that their upregulation after injury is associated with decreased proliferation after brain trauma.

Many genes regulating adult neurogenesis have been identified and are known to play similar roles during early neuronal development. We recently identified apolipoprotein E (ApoE) as a gene the expression of which is essentially absent in early brain progenitors but becomes markedly upregulated in adult dentate gyrus stem/progenitor cells. Here, we demonstrate that ApoE deficiency impairs adult dentate gyrus development by affecting the neural progenitor pool over time. We utilized ApoE-deficient mice crossed to a nestin-GFP reporter to demonstrate that dentate gyrus progenitor cells proliferate more rapidly at early ages, which is subsequently accompanied by an overall decrease in neural progenitor cell number at later time points. This appears to be secondary to over-proliferation early in life and ultimate depletion of the Type 1 nestin- and GFAP-expressing neural stem cells. We also rescue the proliferation phenotype with an ApoE-expressing retrovirus, demonstrating that ApoE works directly in this regard. These data provide novel insight into late hippocampal development and suggest a possible role for ApoE in neurodegenerative diseases.

Chronic hypoxia (CH) is a major risk factor for impaired cognitive function in various disease states, particularly in the context of cyanotic congenital heart disease. While most brain development occurs prenatally, the dentate gyrus (DG) of the hippocampus harbors progenitor stem cells that contribute to its ongoing development postnatally. It is unclear how exposure to CH might affect postnatal hippocampal development, so we utilized a transgenic mouse that expresses enhanced green fluorescent protein (eGFP) within this progenitor population to determine the effect of CH on the DG. We find that exposure to 10% oxygen from postnatal day 3 to 28, results in a smaller DG with long-term impairment of hippocampal neurogenesis. Since the mammalian target of rapamycin (mTOR) pathway is a well-known regulator of cell proliferation and growth and is sensitive to hypoxia, we investigated its activation upon exposure to CH and find it to be attenuated specifically in neural progenitor cells. Systemic inhibition of the mTOR pathway using rapamycin also caused impairment of hippocampal neurogenesis that mimics exposure to CH. Our findings demonstrate that CH results in long-term impairment of hippocampal neurogenesis and is mediated, in part, by attenuation of the mTOR pathway.

Significant spontaneous recovery occurs after essentially all forms of serious brain injury, although the mechanisms underlying this recovery are unknown. Given that many forms of brain injury such as traumatic brain injury (TBI) induce hippocampal neurogenesis, we investigated whether these newly generated neurons might play a role in recovery. By modeling TBI in transgenic mice, we determined that injury-induced newly generated neurons persisted over time and elaborated extensive dendritic trees that stably incorporated themselves throughout all neuronal layers of the dentate gyrus. When we selectively ablated dividing stem/progenitors at the time of injury with ganciclovir in a nestin–HSV–TK transgenic model, we eliminated injury-induced neurogenesis and subsequently diminished the progenitor pool. Moreover, using hippocampal-specific behavioral tests, we demonstrated that only injured animals with neurogenesis ablated at the time of injury lost the ability to learn spatial memory tasks. These data demonstrate a functional role for adult neurogenesis after brain injury and offer compelling and testable therapeutic options that might enhance recovery.

Adult hippocampal neurogenesis occurs throughout life and is believed to participate in cognitive functions such as learning and memory. A number of genes that regulate adult hippocampal neurogenesis have been identified, although most of these have been implicated in progenitor proliferation and survival, but not in the development into fully differentiated neurons. Among these genes, apolipoprotein E (ApoE) is particularly compelling because the human ApoE isoform E4 is a risk factor for the development of Alzheimer’s disease, where hippocampal neurogenesis is reported to be dysfunctional. To investigate the effects of ApoE and its human isoforms on adult hippocampal neurogenesis and neuronal development, retroviruses carrying a GFP-expressing vector were injected into wild-type (WT), ApoE-deficient, and human targeted replacement (ApoE3 and ApoE4) mice to infect progenitors in the dentate gyrus and analyze the morphology of fully developed GFP-expressing neurons. Analysis of these adult-born neurons revealed significant decreases in the complexity of dendritic arborizations and spine density in ApoE-deficient mice compared with WT mice, as well as in ApoE4 mice compared with ApoE3. These findings demonstrate that ApoE deficiency and the ApoE4 human isoform both impair hippocampal neurogenesis and give insight into how ApoE may influence hippocampal-related neurological diseases.

The adult brain maintains two regions of neurogenesis from which new neurons are born, migrate to their appropriate location, and become incorporated into the circuitry of the CNS. One of these, the subgranular zone of the hippocampal dentate gyrus, is of primary interest because of the role of this region in learning and memory. We show that mice lacking EphB1, and more profoundly EphB1 and EphB2, have significantly fewer neural progenitors in the hippocampus. Furthermore, other aspects of neurogenesis, such as polarity, cell positioning, and proliferation are disrupted in animals lacking the EphB1 receptor or its cognate ephrin-B3 ligand. Our data strongly suggest that EphB1 and ephrin-B3 cooperatively regulate the proliferation and migration of neural progenitors in the hippocampus and should be added to a short list of candidate target molecules for modulating the production and integration of new neurons as a treatment for neurodegenerative diseases or brain injury.

The mechanisms underlying astrocyte heterogeneity in the developing mouse brain are poorly understood. The bHLH transcription factor Olig2 is essential for motoneuron and oligodendrocyte formation; however, its role in astrocyte development remains obscure. During cortical development, Olig2 is transiently expressed in immature developing astrocytes at neonatal stages and is progressively downregulated in astrocytes at late postnatal stages. To assess the function of Olig2 in astrocyte formation, we conditionally ablated Olig2 in a spatiotemporally controlled manner. In the Olig2-ablated cortex and spinal cord, the formation of astrocytes in the white matter is severely compromised. Temporally controlled mutagenesis revealed that postnatal Olig2 function is required for astrocyte differentiation in the cerebral white matter. By contrast, astrocytes in the cortical gray matter are formed, but with sustained GFAP upregulation in the superficial layers. Cell type-specific mutagenesis and fate-mapping analyses indicate that abnormal astrocyte formation is at least in part attributable to the loss of Olig2 in developing astrocytes and their precursors. Thus, our studies uncover a crucial role for Olig2 in white matter astrocyte development and reveal divergent transcriptional requirements for,and developmental sources of, morphologically and spatially distinct astrocyte subpopulations.

Brain lesions after traumatic brain injury (TBI) are heterogeneous, rendering outcome prognostication difficult. The aim of this study is to investigate whether early magnetic resonance imaging (MRI) of lesion location and lesion volume within discrete brain anatomical zones can accurately predict long-term neurological outcome in children post-TBI. Fluid-attenuated inversion recovery (FLAIR) MRI hyperintense lesions in 63 children obtained 6.2±5.6 days postinjury were correlated with the Glasgow Outcome Scale Extended-Pediatrics (GOS-E Peds) score at 13.5±8.6 months. FLAIR lesion volume was expressed as hyperintensity lesion volume index (HLVI)=(hyperintensity lesion volume / whole brain volume)×100 measured within three brain zones: zone A (cortical structures); zone B (basal ganglia, corpus callosum, internal capsule, and thalamus); and zone C (brainstem). HLVI-total and HLVI-zone C predicted good and poor outcome groups (p

Acute seizures after a severe brain insult can often lead to epilepsy and cognitive impairment. Aberrant hippocampal neurogenesis follows the insult but the role of adult-generated neurons in the development of chronic seizures or associated cognitive deficits remains to be determined. Here we show that the ablation of adult neurogenesis before pilocarpine-induced acute seizures in mice leads to a reduction in chronic seizure frequency. We also show that ablation of neurogenesis normalizes epilepsy-associated cognitive deficits. Remarkably, the effect of ablating adult neurogenesis before acute seizures is long lasting as it suppresses chronic seizure frequency for nearly 1 year. These findings establish a key role of neurogenesis in chronic seizure development and associated memory impairment and suggest that targeting aberrant hippocampal neurogenesis may reduce recurrent seizures and restore cognitive function following a pro-epileptic brain insult., Aberrant hippocampal neurogenesis often occurs after acute seizures that produce epilepsy and cognitive impairment but the role of neurogenesis in the development of epilepsy is unclear. Here the authors suppress adult neurogenesis in mice preceding seizures and show that it reduces subsequent chronic seizure frequency and epilepsy-associated cognitive decline.

A few short years ago it would have been hard to imagine that anyone might suggest a bone marrow transplant for pediatric traumatic brain injury. The concept of bone marrow-derived cell-based therapies is, however, not a new concept. Nearly 150 years ago, Cohnheim observed that intravenous dye delivery in animals resulted in dye-labeled scar tissue at distal injury sites [1]. This startling discovery suggested that progenitor cells within the bone marrow could become something other than circulating red blood cells, leukoctyes, and platelets. Although more than a century has passed since this pluripotent “potential” of bone marrow-derived cells was first described, in many ways our understanding of the mechanisms and relevance of this exciting phenomenon remain surprisingly rudimentary.

Neural stem cells in the mammalian brain persist and are functional well into adulthood. There is, however, little insight into mechanisms that control adult neural stem cell survival. Mice deficient in the proapoptotic molecule Bax exhibit increased numbers of multipotent progenitor cells in the adult subventricular zone. In vitro, these progenitors behave as neural stem cells and utilize Bax and caspase activation to direct cell death. We demonstrate that the predominate mechanism underlying caspase and Bax-mediated adult neural stem cell death lies in the modulation of calcium flux through interaction with the IP3 receptor.

Neural stem cells have recently been shown to contribute to the cellular remodeling that occurs following traumatic brain injury (TBI). Potential sources for these stem cells from within the brain include the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus. Using intraventricular injections of the fluorescent vital dye DiO in mice, we demonstrate that the subventricular zone population of stem cells can be reliably labeled and followed over time. By following these injections with a contralateral controlled cortical injury we demonstrate that cells from the subventricular zone migrate to the most proximally injured cortical areas. Using doublelabeling immunohistochemistry with anti-nestin, anti-GFAP, and anti-NeuN antibodies we demonstrate that labeled cells from the subventricular zone contribute primarily to the astroglial scar following injury. We do not observe any contribution to deeper areas of injury including the hippocampus. These data demonstrate that the subventricular zone contributes to brain remodeling following TBI, though neural stem cell sources outside the subventricular zone appear to play reparative roles as well.