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Background: Many children with severe traumatic brain injury (TBI) receive magnetic resonance imaging (MRI) during hospitalization. There are insufficient data on how different patterns of injury on early MRI inform outcomes., Methods: Children (3-17 years) admitted in 2010-2021 for severe TBI (Glasgow Coma Scale [GCS] score < 9) were identified using our site's trauma registry. We used multivariable modeling to determine whether the hemorrhagic diffuse axonal injury (DAI) grade and the number of regions with restricted diffusion (subcortical white matter, corpus callosum, deep gray matter, and brainstem) on MRI obtained within 7 days of injury were independently associated with time to follow commands and with Functional Independence Measure for Children (WeeFIM) scores at the time of discharge from inpatient rehabilitation. We controlled for the clinical variables age, preadmission cardiopulmonary resuscitation, pupil reactivity, motor GCS score, and fever (> 38 °C) in the first 12 h., Results: Of 260 patients, 136 (52%) underwent MRI within 7 days of injury at a median of 3 days (interquartile range [IQR] 2-4). Patients with early MRI were a median age of 11 years (IQR 7-14), 8 (6%) patients received cardiopulmonary resuscitation, 19 (14%) patients had bilateral unreactive pupils, the median motor GCS score was 1 (IQR 1-4), and 82 (60%) patients had fever. Grade 3 DAI was present in 46 (34%) patients, and restricted diffusion was noted in the corpus callosum in 75 (55%) patients, deep gray matter in 29 (21%) patients, subcortical white matter in 23 (17%) patients, and the brainstem in 20 (15%) patients. After controlling for clinical variables, an increased number of regions with restricted diffusion, but not hemorrhagic DAI grade, was independently associated with longer time to follow commands (hazard ratio 0.68, 95% confidence interval 0.53-0.89) and worse WeeFIM scores (estimate β - 4.67, 95% confidence interval - 8.33 to - 1.01)., Conclusions: Regional restricted diffusion on early MRI is independently associated with short-term outcomes in children with severe TBI. Multicenter cohort studies are needed to validate these findings and elucidate the association of early MRI features with long-term outcomes in children with severe TBI., (© 2023. Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society.)

Purpose of Review: The purpose is to describe the latest research on epidemiology, causes, and morbidities of stroke in neonates and children., Recent Findings: The global incidence of childhood stroke is approximately 2 per 100 000 person-years, which is significantly lower compared to neonates (20-40 per 100 000 live births) and adults (80-90 per 100 000 person-years). Placental abnormalities are a risk factor for perinatal stroke, although cause is usually multifactorial. In children, nonatherosclerotic arteriopathies and arteriovenous malformations are major causes of ischemic and hemorrhagic strokes, respectively. The perinatal period confers a high risk of stroke and can lead to long-term disability, including motor delay, cognitive or speech impairment, and epilepsy. Recent studies suggest that at least 50% of survivors of perinatal stroke have abnormal neurodevelopmental scores in long-term follow up. Childhood stroke is associated with significant morbidity, including epilepsy, motor impairments, and behavioral disability. Recent studies have also identified an association between pediatric stroke and behavioral disorders, such as attention deficit hyperactivity disorder and autism., Summary: Perinatal and childhood strokes are important causes of neurological morbidity. Given the low incidence of childhood stroke, prospective research studies on epidemiology, causes, and outcomes remain limited, highlighting the need for continued multisite collaborations., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Traumatic brain injury (TBI) is the leading cause of death and disability in children, but effective tools for predicting outcome remain elusive. Although many pediatric patients receive early magnetic resonance imaging (MRI), data on its utility in prognostication are lacking. Diffuse axonal injury (DAI) is a hallmark of TBI detected on early MRI and was shown previously to improve prognostication in adult patients with TBI. In this exploratory study, we investigated whether DAI grade correlates with functional outcome and improves prognostic accuracy when combined with core clinical variables and computed tomography (CT) biomarkers in pediatric patients with moderate-severe TBI (msTBI)., Methods: Pediatric patients (≤ 19 years) who were admitted to two regional level one trauma centers with a diagnosis of msTBI (Glasgow Coma Scale [GCS] score < 13) between 2011 and 2019 were identified through retrospective chart review. Patients who underwent brain MRI within 30 days of injury and had documented clinical follow-up after discharge were included. Age, pupil reactivity, and initial motor GCS score were collected as part of the International Mission for Prognosis and Analysis of Clinical Trials in TBI (IMPACT) model. Imaging was reviewed to calculate the Rotterdam score (CT) and DAI grade (MRI) and to evaluate for presence of hypoxic-ischemic injury (MRI). The primary outcome measure was the Pediatric Cerebral Performance Category Scale (PCPCS) score at 6 months after TBI, with favorable outcome defined as PCPCS scores 1-3 and unfavorable outcome defined as PCPCS scores 4-6. The secondary outcome measure was discharge disposition to home versus to an inpatient rehabilitation facility., Result: Of 55 patients included in the study, 45 (82%) had severe TBI. The most common mechanism of injury was motor vehicle collision (71%). Initial head CT scans showed acute hemorrhage in 84% of patients. MRI was acquired a median of 5 days after injury, and hemorrhagic DAI lesions were detected in 87% of patients. Each 1-point increase in DAI grade increased the odds of unfavorable functional outcome by 2.4-fold. When controlling for core IMPACT clinical variables, neither the DAI grade nor the Rotterdam score was independently correlated with outcome and neither significantly improved outcome prediction over the IMPACT model alone., Conclusions: A higher DAI grade on early MRI is associated with worse 6-month functional outcome and with discharge to inpatient rehabilitation in children with acute msTBI in a univariate analysis but does not independently correlate with outcome when controlling for the GCS score. Addition of the DAI grade to the core IMPACT model does not significantly improve prediction of poor neurological outcome. Further study is needed to elucidate the utility of early MRI in children with msTBI., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society.)

In spinal muscular atrophy, a neurodegenerative disease caused by ubiquitous deficiency in the survival motor neuron (SMN) protein, sensory-motor synaptic dysfunction and increased excitability precede motor neuron (MN) loss. Whether central synaptic dysfunction and MN hyperexcitability are cell-autonomous events or they contribute to MN death is unknown. We addressed these issues using a stem-cell-based model of the motor circuit consisting of MNs and both excitatory and inhibitory interneurons (INs) in which SMN protein levels are selectively depleted. We show that SMN deficiency induces selective MN death through cell-autonomous mechanisms, while hyperexcitability is a non-cell-autonomous response of MNs to defects in pre-motor INs, leading to loss of glutamatergic synapses and reduced excitation. Findings from our in vitro model suggest that dysfunction and loss of MNs result from differential effects of SMN deficiency in distinct neurons of the motor circuit and that hyperexcitability does not trigger MN death., (Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.)

The function of human nervous system is critically dependent on proper interneuronal communication. Exosomes and other extracellular vesicles are emerging as a novel form of information exchange within the nervous system. Intraluminal vesicles within multivesicular bodies (MVBs) can be transported in neural cells anterogradely or retrogradely in order to be released into the extracellular space as exosomes. RNA loading into exosomes can be either via an interaction between RNA and the raft-like region of the MVB limiting membrane, or via an interaction between an RNA-binding protein-RNA complex with this raft-like region. Outflow of exosomes from neural cells and inflow of exosomes into neural cells presumably take place on a continuous basis. Exosomes can play both neuro-protective and neuro-toxic roles. In this review, we characterize the role of exosomes and microvesicles in normal nervous system function, and summarize evidence for defective signaling of these vesicles in disease pathogenesis of some neurodegenerative diseases., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Characterization of HIV-1 interactions with host cells is critical for cell biology studies of HIV-1. This unit describes a set of methods and protocols to perform quantitative assays of HIV-1 binding, internalization, infection, and cell-cell transmission. The protocols include: (1) generating infectious single-cycle or replication-competent HIV-1 stocks, (2) an HIV-1 binding and internalization assay, (3) HIV-1 infection of target cells and quantification of viral infection, and (4) HIV-1 cell-cell transmission assays. These functional assays provide useful tools to quantitatively study HIV-1 infection and viral transmission.

Young male Fischer-344 rats were fed a diet containing 2% blueberry (BB) extract or control diet for at least 8 weeks and then received bilateral hippocampal injections of kainic acid (KA 200 ng/0.5 microl) or phosphate buffered saline (PBS). One week later rats were trained in one-way active footshock avoidance in a straight runway followed the next day by training in a footshock motivated 14-unit T-maze with documented sensitivity to hippocampal glutamatergic manipulations. Based on analyses of several performance variables, KA-treated rats exhibited clearly impaired learning performance; however, the BB diet significantly reduced this impairment. Supporting the behavioral findings, stereological assessment of CA1 pyramidal neurons documented greater neuronal loss in KA-treated controls compared to KA-treated rats on the BB diet. In an in vitro experiment, FaO cells grown in medium supplemented with serum from BB-fed rats had enhanced viability after exposure to hydrogen peroxide. These findings suggest that BB supplementation may protect against neurodegeneration and cognitive impairment mediated by excitotoxicity and oxidative stress.

Human immunodeficiency virus type 1 (HIV-1) enters dendritic cells (DCs) through endocytosis and viral receptor-mediated fusion. Although endocytosis-mediated HIV-1 entry can generate productive infection in certain cell types, including human monocyte-derived macrophages, productive HIV-1 infection in DCs appears to be dependent on fusion-mediated viral entry. It remains to be defined whether endocytosed HIV-1 in DCs can initiate productive infection. Using HIV-1 infection and cellular fractionation assays to measure productive viral infection and entry, here we show that HIV-1 enters monocyte-derived DCs predominately through endocytosis; however, endocytosed HIV-1 cannot initiate productive HIV-1 infection in DCs. In contrast, productive HIV-1 infection in DCs requires fusion-mediated viral entry. Together, these results provide functional evidence in understanding HIV-1 cis-infection of DCs, suggesting that different pathways of HIV-1 entry into DCs determine the outcome of viral infection.

Dendritic cells (DCs) transmit human immunodeficiency virus type 1 (HIV-1) to CD4(+) T cells through the trans- and cis-infection pathways; however, little is known about the relative efficiencies of these pathways and whether they are interdependent. Here we compare cis- and trans-infections of HIV-1 mediated by immature DCs (iDCs) and mature DCs (mDCs), using replication-competent and single-cycle HIV-1. Monocyte-derived iDCs were differentiated into various types of mDCs by lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-alpha), and CD40 ligand (CD40L). iDCs and CD40L-induced mDCs were susceptible to HIV-1 infection and mediated efficient viral transmission to CD4(+) T cells. Although HIV-1 cis-infection was partially restricted in TNF-alpha-induced mDCs and profoundly blocked in LPS-induced mDCs, these cells efficiently promoted HIV-1 trans-infection of CD4(+) T cells. The postentry restriction of HIV-1 infection in LPS-induced mDCs was identified at the levels of reverse transcription and postintegration, using real-time PCR quantification of viral DNA and integration. Furthermore, nucleofection of DCs with HIV-1 proviral DNA confirmed that impaired gene expression of LPS-induced mDCs was responsible for the postentry restriction of HIV-1 infection. Our results suggest that various DC subsets in vivo may differentially contribute to HIV-1 dissemination via dissociable cis- and trans-infections.

Dendritic cells (DCs) potently stimulate the transmission of human immunodeficiency virus type 1 (HIV-1) to CD4(+) T cells. Immature DCs (iDCs) located in submucosal tissues can capture HIV-1 and migrate to lymphoid tissues, where they become mature DCs (mDCs) for effective antigen presentation. DC maturation promotes HIV-1 transmission; however, the underlying mechanisms remain unclear. Here we have compared monocyte-derived iDCs and mDCs for their efficiencies and mechanisms of HIV-1 transmission. We have found that mDCs significantly facilitate HIV-1 endocytosis and efficiently concentrate HIV-1 at virological synapses, which contributes to mDC-enhanced viral transmission, at least in part. mDCs were more efficient than iDCs in transferring HIV-1 to various types of target cells independently of C-type lectins, which partially accounted for iDC-mediated HIV-1 transmission. Efficient HIV-1 trans-infection mediated by iDCs and mDCs required contact between DCs and target cells. Moreover, rapid HIV-1 degradation occurred in both iDCs and mDCs, which correlated with the lack of HIV-1 retention-mediated long-term viral transmission. Our results provide new insights into the mechanisms underlying DC-mediated HIV-1 transmission, suggesting that HIV-1 exploits mDCs to facilitate its dissemination within lymphoid tissues.

Dendritic cells (DCs) potently stimulate the cell-cell transmission of human immunodeficiency virus type 1 (HIV-1). However, the mechanisms that underlie DC transmission of HIV-1 to CD4(+) T cells are not fully understood. DC-SIGN, a C-type lectin, efficiently promotes HIV-1 trans infection. DC-SIGN is expressed in monocyte-derived DCs (MDDCs), macrophage subsets, activated B lymphocytes, and various mucosal tissues. MDDC-mediated HIV-1 transmission to CD4(+) T cells involves DC-SIGN-dependent and -independent mechanisms. DC-SIGN transmission of HIV-1 depends on the donor cell type. HIV-1 Nef can upregulate DC-SIGN expression and promote DC-T-cell clustering and HIV-1 spread. Nef also downregulates CD4 expression; however, the effect of the CD4 downmodulation on DC-mediated HIV-1 transmission has not been examined. Here, we report that CD4 expression levels correlate with inefficient HIV-1 transmission by monocytic cells expressing DC-SIGN. Expression of CD4 on Raji B cells strongly impaired DC-SIGN-mediated HIV-1 transmission to T cells. By contrast, enhanced HIV-1 transmission was observed when CD4 molecules on MDDCs and DC-SIGN-CD4-expressing cell lines were blocked with specific antibodies. Coexpression of CD4 and DC-SIGN in Raji cells promoted the internalization and intracellular retention of HIV-1. Interestingly, internalized HIV-1 particles were sorted and confined to late endosomal compartments that were positive for CD63 and CD81. Furthermore, in HIV-1-infected MDDCs, significant downregulation of CD4 by Nef expression correlated with enhanced viral transmission. These results suggest that CD4, which is present at various levels in DC-SIGN-positive primary cells, is a key regulator of HIV-1 transmission.

Male Fischer-344 rats (n = 38) at 5 months old were tested in a Morris water maze to determine if treatment with the cholinesterase inhibitor, phenserine (PHEN), would overcome a learning impairment induced by scopolamine (SCOP), a muscarinic cholinergic receptor antagonist. Each rat was randomly assigned to one of five groups to receive two intraperitoneal injections 60 and 30 min, prior to testing, respectively, as follows: (1) saline-saline (SAL); (2) saline-1.0 mg/kg (SCOP); (3) 2 mg/kg PHEN- SCOP (PHEN2); (4) 4 mg/kg PHEN-SCOP (PHEN4); and (5) 1 mg/kg PHEN-SAL (PHEN1). Maze testing occurred across 5 days with 4 days of acquisition trials (4 trials per day) and a fifth day consisting of a single 120 sec probe trial. PHEN1 and SAL were combined into one control (CON) group for purposes of statistical analysis for both acquisition and probe trials as comparison of the two groups revealed that they did not significantly differ on any measure. SCOP-treated rats were significantly impaired compared to CON in learning the location of the submerged platform as measured by latency to locate the platform and the distance traversed to find the platform across days of testing. The PHEN4 group had significantly lower latencies and traveled a shorter distance to reach the submerged platform when compared to SCOP on the fourth day of trials while the PHEN2 group traveled more directly to the submerged platform but did not have shorter latencies than the SCOP group. For probe trials, CON rats swam closer to the target area (a measure of proximity to the removed platform) than did all other groups, and the PHEN4 group swam in an area more proximate to the target area than did the SCOP-treated group. These findings demonstrate the ability of this drug to improve learning when cholinergic function has been impaired in a spatial memory task.