Disparities in Pediatric Epilepsy Remission Are Associated With Race and Ethnicity.

OBJECTIVE: The purpose of our study was to assess whether race/ethnicity was associated with seizure remission in pediatric epilepsy. METHODS: This was a retrospective population-based cohort study of children who were evaluated for new-onset epilepsy in the clinic, emergency department, and/or hospital by a pediatric neurologist in an integrated health care delivery system. Children were between ages 6 months and 15 years at their initial presentation of epilepsy. The cohort, identified through an electronic database, was assembled over 6 years, with no less than 5 years of follow-up. All children were evaluated for race, ethnicity, insurance type, and socioeconomic background. Patient outcome was determined at the conclusion of the study period and categorized according to their epilepsy control as either drug resistant (pharmacoresistant and intractable) or drug responsive (controlled, probable remission, and terminal remission). RESULTS: In the final cohort of 776 patients, 63% were drug responsive (control or seizure remission). After controlling for confounding socioeconomic and demographic factors, children of Hispanic ethnicity experienced reduced likelihood (hazard) of drug-responsive epilepsy (hazard ratio 0.6, P < .001), and had longer median time to remission (8 years; 95% CI 5.9-9.6 years) compared to white non-Hispanic patients (5.6 years; 95% CI 4.9-6.1 years). Among Hispanic patients, higher health care costs were associated with reduced likelihood of drug responsiveness. SIGNIFICANCE: We found that Hispanic ethnicity is associated with a reduced likelihood of achieving seizure control and remission. This study suggests that factors associated with the race/ethnicity of patients contributes to their likelihood of achieving seizure freedom.

Autism Spectrum Disorder and Neonatal Serum Magnesium Levels in Preterm Infants.

Premature birth is associated with increased risk of autism spectrum disorder. Antenatal maternal magnesium administration is known to reduce subsequent risk of cerebral palsy including among premature infants, suggesting a potentially broader neuroprotective role for magnesium. Our objective was to determine whether magnesium could be protective against autism spectrum disorders in premature infants. A cohort of 4855 preterm children was identified, magnesium levels from 24 to 48 hours of life recorded, and subsequent autism spectrum disorder status determined. Adjusted relative risk of autism spectrum disorder with each 1 mg/dL increase in neonatal magnesium level was 1.15 (95% confidence interval: 0.86-1.53). Analysis of variance indicated that magnesium levels varied by gestational age and maternal antenatal magnesium supplementation, but not autism spectrum disorder status (F1,4824 = 1.43, P = .23). We found that neonatal magnesium levels were not associated with decreased autism spectrum disorder risk. Future research into autism spectrum disorder risks and treatments in premature infants is needed.

A Novel Developmental Role for Dopaminergic Signaling to Specify Hypothalamic Neurotransmitter Identity.

Hypothalamic neurons expressing histamine and orexin/hypocretin (hcrt) are necessary for normal regulation of wakefulness. In Parkinson's disease, the loss of dopaminergic neurons is associated with elevated histamine levels and disrupted sleep/wake cycles, but the mechanism is not understood. To characterize the role of dopamine in the development of histamine neurons, we inhibited the translation of the two non-allelic forms of tyrosine hydroxylase (th1 and th2) in zebrafish larvae. We found that dopamine levels were reduced in both th1 and th2 knockdown, but the serotonin level and number of serotonin neurons remained unchanged. Further, we demonstrated that th2 knockdown increased histamine neuron number and histamine levels, whereas increased dopaminergic signaling using the dopamine precursor l-DOPA (l-3,4-dihydroxyphenylalanine) or dopamine receptor agonists reduced the number of histaminergic neurons. Increases in the number of histaminergic neurons were paralleled by matching increases in the numbers of hcrt neurons, supporting observations that histamine regulates hcrt neuron development. Finally, we show that histaminergic neurons surround th2-expressing neurons in the hypothalamus, and we suggest that dopamine regulates the terminal differentiation of histamine neurons via paracrine actions or direct synaptic neurotransmission. These results reveal a role for dopaminergic signaling in the regulation of neurotransmitter identity and a potential mechanism contributing to sleep disturbances in Parkinson's disease.

Neonatal Magnesium Levels Between 24 and 48 Hours of Life and Outcomes for Epilepsy and Motor Impairment in Premature Infants.

OBJECTIVE: Elevated rates of epilepsy and motor impairments including cerebral palsy are observed in children who were born prematurely. Maternal antenatal magnesium supplementation has been associated with decreased rates of cerebral palsy in infants born prematurely. Our objective was to determine whether the neonatal serum magnesium level between 24 and 48 hours after birth is associated with better long-term neurodevelopmental outcomes (epilepsy, motor impairment) in premature infants. METHODS: We performed a retrospective cohort analysis in infants born less than 37-weeks gestation over a ten-year period. Prenatal, perinatal, and postnatal clinical and demographic information was collected. Crude and adjusted odds ratios were estimated under generalized linear models with generalized estimating equations to examine the association of the neonatal serum magnesium level between 24 and 48 hours after birth with the risk of epilepsy and/or motor impairment (spasticity; hypotonia; cerebral palsy). RESULTS: The final cohort included 5461 infants born less than 37-weeks gestation from 2002 to 2011. The adjusted relative risk ratio for the combined outcomes of epilepsy and/or motor impairment, controlling for gestational age, current age, maternal magnesium supplementation, maternal steroid administration, five-minute Apgar score, neonatal infection, need for vasopressor use, and birth weight and with serum magnesium level as the main independent variable, was 0.85 (P = 0.24). Stratified analyses by gestational age less than 32 or greater than 32 weeks were not significantly associated with adverse neurodevelopmental outcome (risk ratio = 0.79 and 1.2, P = 0.12 and 0.49, respectively). A multivariate analysis for the risk of motor impairment alone had a risk ratio of 0.94 (P = 0.72). CONCLUSION: This study demostrates that the neonatal magnesium level between 24 and 48 hours of life in premature infants is not significantly associated with the risk for developing epilepsy or motor impairment.

Motor Behavior Mediated by Continuously Generated Dopaminergic Neurons in the Zebrafish Hypothalamus Recovers after Cell Ablation.

Postembryonic neurogenesis has been observed in several regions of the vertebrate brain, including the dentate gyrus and rostral migratory stream in mammals, and is required for normal behavior [1-3]. Recently, the hypothalamus has also been shown to undergo continuous neurogenesis as a way to mediate energy balance [4-10]. As the hypothalamus regulates multiple functional outputs, it is likely that additional behaviors may be affected by postembryonic neurogenesis in this brain structure. Here, we have identified a progenitor population in the zebrafish hypothalamus that continuously generates neurons that express tyrosine hydroxylase 2 (th2). We develop and use novel transgenic tools to characterize the lineage of th2(+) cells and demonstrate that they are dopaminergic. Through genetic ablation and optogenetic activation, we then show that th2(+) neurons modulate the initiation of swimming behavior in zebrafish larvae. Finally, we find that the generation of new th2(+) neurons following ablation correlates with restoration of normal behavior. This work thus identifies for the first time a population of dopaminergic neurons that regulates motor behavior capable of functional recovery.

Hypothalamic radial glia function as self-renewing neural progenitors in the absence of Wnt/ß-catenin signaling.

The vertebrate hypothalamus contains persistent radial glia that have been proposed to function as neural progenitors. In zebrafish, a high level of postembryonic hypothalamic neurogenesis has been observed, but the role of radial glia in generating these new neurons is unclear. We have used inducible Cre-mediated lineage labeling to show that a population of hypothalamic radial glia undergoes self-renewal and generates multiple neuronal subtypes at larval stages. Whereas Wnt/ß-catenin signaling has been demonstrated to promote the expansion of other stem and progenitor cell populations, we find that Wnt/ß-catenin pathway activity inhibits this process in hypothalamic radial glia and is not required for their self-renewal. By contrast, Wnt/ß-catenin signaling is required for the differentiation of a specific subset of radial glial neuronal progeny residing along the ventricular surface. We also show that partial genetic ablation of hypothalamic radial glia or their progeny causes a net increase in their proliferation, which is also independent of Wnt/ß-catenin signaling. Hypothalamic radial glia in the zebrafish larva thus exhibit several key characteristics of a neural stem cell population, and our data support the idea that Wnt pathway function may not be homogeneous in all stem or progenitor cells.

Neonatal magnesium levels correlate with motor outcomes in premature infants: a long-term retrospective cohort study.

OBJECTIVE: Chronic neurological deficits are a significant complication of preterm birth. Magnesium supplementation has been suggested to have neuroprotective function in the developing brain. Our objective was to determine whether higher neonatal serum magnesium levels were associated with better long-term neurodevelopmental outcomes in very-low birth weight infants. STUDY DESIGN: A retrospective cohort of 75 preterm infants (<1500 g, gestational age <27 weeks) had follow-up for the outcomes of abnormal motor exam and for epilepsy. Average total serum magnesium level in the neonate during the period of prematurity was the main independent variable assessed, tested using a Wilcoxon rank-sum test. RESULTS: Higher average serum magnesium level was associated with a statistically significant decreased risk for abnormal motor exam (p = 0.037). A lower risk for epilepsy in the group with higher magnesium level did not reach statistical significance (p = 0.06). CONCLUSION: This study demonstrates a correlation between higher neonatal magnesium levels and decreased risk for long-term abnormal motor exam. Larger studies are needed to evaluate the hypothesis that higher neonatal magnesium levels can improve long-term neurodevelopmental outcomes.

Sim1a and Arnt2 contribute to hypothalamo-spinal axon guidance by regulating Robo2 activity via a Robo3-dependent mechanism.

Precise spatiotemporal control of axon guidance factor expression is a prerequisite for formation of functional neuronal connections. Although Netrin/Dcc- and Robo/Slit-mediated attractive and repulsive guidance of commissural axons have been extensively studied, little is known about mechanisms controlling mediolateral positioning of longitudinal axons in vertebrates. Here, we use a genetic approach in zebrafish embryos to study pathfinding mechanisms of dopaminergic and neuroendocrine longitudinal axons projecting from the hypothalamus into hindbrain and spinal cord. The transcription factors Sim1a and Arnt2 contribute to differentiation of a defined population of dopaminergic and neuroendocrine neurons. We show that both factors also control aspects of axon guidance: Sim1a or Arnt2 depletion results in displacement of hypothalamo-spinal longitudinal axons towards the midline. This phenotype is suppressed in robo3 guidance receptor mutant embryos. In the absence of Sim1a and Arnt2, expression of the robo3 splice isoform robo3a.1 is increased in the hypothalamus, indicating negative control of robo3a.1 transcription by these factors. We further provide evidence that increased Robo3a.1 levels interfere with Robo2-mediated repulsive axon guidance. Finally, we show that the N-terminal domain unique to Robo3a.1 mediates the block of Robo2 repulsive activity. Therefore, Sim1a and Arnt2 contribute to control of lateral positioning of longitudinal hypothalamic-spinal axons by negative regulation of robo3a.1 expression, which in turn attenuates the repulsive activity of Robo2.

Cardiac testing and outcomes in infants after an apparent life-threatening event.

OBJECTIVES: We sought to determine the yield of cardiac testing and to identify predictors of cardiac disease in infants with an apparent life-threatening event (ALTE). DESIGN: Retrospective longitudinal cohort study. SETTING: Paediatric hospital providing primary and tertiary care that is part of an integrated healthcare system. PATIENTS: Infants hospitalised for an ALTE from 1999 to 2003. MAIN EXPOSURES: Cardiac testing used at time of ALTE and results, and clinical risk factors for cardiac disease. OUTCOME MEASURES: Short-term (during hospitalisation) and long-term (through November 2009) follow-up for any diagnosis of significant cardiac anatomic or rhythm abnormality. RESULTS: Study criteria were met by 485 infants (mean age 1.9, SD±2.2 months; 49% boys). Cardiac testing was performed on 219 (45%) patients during ALTE hospitalisation, identifying two patients with significant cardiac disease (cardiomyopathy, ventricular pre-excitation). During 7.7 years of follow-up, three additional significant cardiac diagnoses (ventricular pre-excitation, frequent ventricular ectopy, moderate aortic stenosis) were identified. All cardiac tests had low positive predictive value (PPV). Significant cardiac disease was associated with prematurity (22% vs 80%, p=0.002), but not age, gender, prior ALTE or rescue breaths. CONCLUSIONS: This longitudinal study of an ALTE cohort revealed significant cardiac disease in <1% of patients. Prematurity was the only clinical predictor identified. ECG was sensitive for identifying significant cardiac disease, but routine testing warrants further investigation because of the low PPV.

Hypoxia disruption of vertebrate CNS pathfinding through ephrinB2 Is rescued by magnesium.

The mechanisms of hypoxic injury to the developing human brain are poorly understood, despite being a major cause of chronic neurodevelopmental impairments. Recent work in the invertebrate Caenorhabditis elegans has shown that hypoxia causes discrete axon pathfinding errors in certain interneurons and motorneurons. However, it is unknown whether developmental hypoxia would have similar effects in a vertebrate nervous system. We have found that developmental hypoxic injury disrupts pathfinding of forebrain neurons in zebrafish (Danio rerio), leading to errors in which commissural axons fail to cross the midline. The pathfinding defects result from activation of the hypoxia-inducible transcription factor (hif1) pathway and are mimicked by chemical inducers of the hif1 pathway or by expression of constitutively active hif1α. Further, we found that blocking transcriptional activation by hif1α helped prevent the guidance defects. We identified ephrinB2a as a target of hif1 pathway activation, showed that knock-down of ephrinB2a rescued the guidance errors, and showed that the receptor ephA4a is expressed in a pattern complementary to the misrouting axons. By targeting a constitutively active form of ephrinB2a to specific neurons, we found that ephrinB2a mediates the pathfinding errors via a reverse-signaling mechanism. Finally, magnesium sulfate, used to improve neurodevelopmental outcomes in preterm births, protects against pathfinding errors by preventing upregulation of ephrinB2a. These results demonstrate that evolutionarily conserved genetic pathways regulate connectivity changes in the CNS in response to hypoxia, and they support a potential neuroprotective role for magnesium.

Homeodomain protein otp and activity-dependent splicing modulate neuronal adaptation to stress.

Regulation of corticotropin-releasing hormone (CRH) activity is critical for the animal's adaptation to stressful challenges, and its dysregulation is associated with psychiatric disorders in humans. However, the molecular mechanism underlying this transcriptional response to stress is not well understood. Using various stress paradigms in mouse and zebrafish, we show that the hypothalamic transcription factor Orthopedia modulates the expression of CRH as well as the splicing factor Ataxin 2-Binding Protein-1 (A2BP1/Rbfox-1). We further show that the G protein coupled receptor PAC1, which is a known A2BP1/Rbfox-1 splicing target and an important mediator of CRH activity, is alternatively spliced in response to a stressful challenge. The generation of PAC1-hop messenger RNA isoform by alternative splicing is required for termination of CRH transcription, normal activation of the hypothalamic-pituitary-adrenal axis and adaptive anxiety-like behavior. Our study identifies an evolutionarily conserved biochemical pathway that modulates the neuronal adaptation to stress through transcriptional activation and alternative splicing.

The hypothalamic neuropeptide oxytocin is required for formation of the neurovascular interface of the pituitary.

The hypothalamo-neurohypophyseal system (HNS) is the neurovascular structure through which the hypothalamic neuropeptides oxytocin and arginine-vasopressin exit the brain into the bloodstream, where they go on to affect peripheral physiology. Here, we investigate the molecular cues that regulate the neurovascular contact between hypothalamic axons and neurohypophyseal capillaries of the zebrafish. We developed a transgenic system in which both hypothalamic axons and neurohypophyseal vasculature can be analyzed in vivo. We identified the cellular organization of the zebrafish HNS as well as the dynamic processes that contribute to formation of the HNS neurovascular interface. We show that formation of this interface is regulated during development by local release of oxytocin, which affects endothelial morphogenesis. This cell communication process is essential for the establishment of a tight axovasal interface between the neurons and blood vessels of the HNS. We present a unique example of axons affecting endothelial morphogenesis through secretion of a neuropeptide.

Cerebral sinovenous thrombosis in children: another reason to treat iron deficiency anemia.

Iron deficiency anemia is a rare cause of cerebral sinovenous thrombosis in children. We report three cases of cerebral sinovenous thrombosis and iron deficiency anemia treated at Primary Children's Medical Center in Salt Lake City, Utah, between 1998 and 2001. The children were 9, 19, and 27 months old at the time of admission. Hemoglobin levels ranged from 6.6 to 7.0 g/dL, mean corpuscular volume levels from 45 to 56 fL, and platelet counts from 248,000 to 586,000/microL. Magnetic resonance imaging and magnetic resonance venography revealed thrombosis of the straight sinus and internal cerebral veins in all three children, with the addition of the vein of Galen, left transverse and sigmoid sinuses, and upper left internal jugular vein in one child. Recovery ranged from excellent to poor in 3 months to 3 years of follow-up. Four additional cases, ages 6 to 22 months, were found in the English-language literature. Evaluation for prothrombotic disorders was negative in all children, including the current cases. Treatments have included thrombectomy, corticosteroids, mannitol, heparin, low-molecular-weight heparin, warfarin, aspirin, blood transfusion, and iron supplementation, but there is no consensus regarding therapy, other than to correct the anemia and treat iron deficiency. Iron deficiency anemia, a preventable cause of cerebral sinovenous thrombosis, deserves consideration when cerebral sinovenous thrombosis is detected in young children.

Metamizole use by Latino immigrants: a common and potentially harmful home remedy.

A 4-year-old boy presented with fever, septic arthritis, and persistent neutropenia. Bone marrow biopsy revealed no evidence of neoplasia. Additional history disclosed that the patient had been given metamizole for pain before onset of his illness. Metamizole, a nonsteroidal antiinflammatory agent, is prohibited in the United States because of the risk of agranulocytosis but is widely used in Mexico and other countries. The increasing number of Latinos in the United States and the extensive cross-border transfer of medicines raise concerns that metamizole use and associated complications may become more frequent. After identification of the index patient, additional inquiry revealed that the patient's mother was hospitalized previously for overwhelming sepsis associated with metamizole use. These cases prompted an investigation of metamizole use in an urban pediatric clinic, which revealed that 35% of Spanish-speaking Latino families had used metamizole; 25% of these families had purchased the medication in the United States. We conclude that metamizole use is common and may be underrecognized in immigrant Latino patients. Physicians in the United States, especially those who practice primary care, hematology/oncology, and infectious diseases, must be aware of the availability and use of metamizole in specific patient populations and its potential for harmful side effects.