RESUMEN
Resting-state fMRI (rs-fMRI) holds promise as a clinical tool to characterize and monitor the phenotype of different neurological and psychiatric disorders. The most common analysis approach requires the definition of one or more regions-of-interest (ROIs). However this need for a priori ROI information makes rs-fMRI inadequate to survey functional connectivity differences associated with a range of neurological disorders where the ROI information may not be available. A second problem encountered in fMRI measures of connectivity is the need for an arbitrary correlation threshold to determine whether or not two areas are connected. This is problematic because in many cases the differences in tissue connectivity between disease groups and/or control subjects are threshold dependent. In this work we propose a novel voxel-based contrast mechanism for rs-fMRI, the intrinsic connectivity distribution (ICD), that neither requires a priori information to define a ROI, nor an arbitrary threshold to define a connection. We show the sensitivity of previous methods to the choice of connection thresholds and evaluate ICD using a survey study comparing young adults born prematurely to healthy term control subjects. Functional connectivity differences were found in hypothesized language processing areas in the left temporal-parietal areas. In addition, significant clinically-relevant differences were found between preterm and term control subjects, highlighting the importance of whole brain surveys independent of a priori information.
Asunto(s)
Mapeo Encefálico/métodos , Encéfalo/patología , Vías Nerviosas/patología , Humanos , Interpretación de Imagen Asistida por Computador , Recién Nacido , Recien Nacido Prematuro , Imagen por Resonancia Magnética , Adulto JovenRESUMEN
Although a single perinatal or postnatal event may be directly correlated to intraventricular hemorrhage (IVH) in some infants, in other infants IVH may be related to a series of insults. Asphyxia, hypotension, and a pressure-passive low cerebral blood flow (CBF) may lead to an infarction. Subsequent events known to cause sudden rises in the CBF may then produce a hemorrhage into damaged tissues. We report two cases of this proposed model for delayed hemorrhage into infarcted tissues, or late IVH. Both neonates were severely asphyxiated, and both experienced profound hypotension and a low CBF on the first postnatal day. Late IVH was found in both neonates; at 2 to 3 months of age, one neonate was found to have computed tomographic evidence for diffuse encephalomalacia, and the other neonate was noted to have an occipital porencephalic cyst.
Asunto(s)
Hemorragia Cerebral/etiología , Infarto Cerebral/complicaciones , Enfermedades del Prematuro/etiología , Hemorragia Cerebral/diagnóstico , Hemorragia Cerebral/fisiopatología , Infarto Cerebral/diagnóstico , Infarto Cerebral/fisiopatología , Ventrículos Cerebrales , Circulación Cerebrovascular , Femenino , Humanos , Recién Nacido , Enfermedades del Prematuro/diagnóstico , Enfermedades del Prematuro/fisiopatología , MasculinoRESUMEN
Three-channel cassette electroencephalographic (EEG) recording for up to 24 hours was obtained from 37 neonates with clinically diagnosed or suspected seizures but no seizure activity on routine EEG. EEG seizures were recorded in seven patients, five of whom had experienced clinical seizures in the 24 hours prior to cassette EEG recording. EEG seizures were detected in only one of nine neonates with recurring clinical episodes believed unlikely to be seizures and in only one of 18 without recent clinical events. Cassette EEG can enhance the detection and differentiation of seizures in neonates with persistent clinical episodes but is of low yield otherwise.
Asunto(s)
Electroencefalografía/métodos , Enfermedades del Recién Nacido/diagnóstico , Convulsiones/diagnóstico , Apnea/complicaciones , Humanos , Recién Nacido , Enfermedades del Recién Nacido/complicaciones , Enfermedades del Recién Nacido/tratamiento farmacológico , Enfermedades del Recién Nacido/fisiopatología , Fenobarbital/uso terapéutico , Convulsiones/complicaciones , Convulsiones/tratamiento farmacológico , Convulsiones/fisiopatología , Grabación en CintaRESUMEN
The newborn beagle puppy has been demonstrated to provide a good model for neonatal intraventricular hemorrhage (IVH). By randomized computerized design, indomethacin, a known inhibitor of prostaglandin synthetase, was administered to newborn beagle puppies, all of which underwent the experimental model of hemorrhagic hypotension followed by volume reexpansion for the production of IVH, to determine whether indomethacin can prevent intraventricular hemorrhage in this model. Nine percent of all pups receiving indomethacin experienced intraventricular hemorrhage, compared with 80% of animals who received the saline vehicle. In addition, significant alterations in the blood pressure responses to the hemorrhagic hypotension/volume reexpansion insult were noted in this group when compared with control animals.
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Hemorragia Cerebral/prevención & control , Indometacina/administración & dosificación , Animales , Animales Recién Nacidos , Presión Sanguínea/efectos de los fármacos , Hemorragia Cerebral/tratamiento farmacológico , Ventrículos Cerebrales , Circulación Cerebrovascular/efectos de los fármacos , Modelos Animales de Enfermedad , PerrosRESUMEN
OBJECTIVE: The authors reviewed available evidence on neonatal neuroimaging strategies for evaluating both very low birth weight preterm infants and encephalopathic term neonates. IMAGING FOR THE PRETERM NEONATE: Routine screening cranial ultrasonography (US) should be performed on all infants of <30 weeks' gestation once between 7 and 14 days of age and should be optimally repeated between 36 and 40 weeks' postmenstrual age. This strategy detects lesions such as intraventricular hemorrhage, which influences clinical care, and those such as periventricular leukomalacia and low-pressure ventriculomegaly, which provide information about long-term neurodevelopmental outcome. There is insufficient evidence for routine MRI of all very low birth weight preterm infants with abnormal results of cranial US. IMAGING FOR THE TERM INFANT: Noncontrast CT should be performed to detect hemorrhagic lesions in the encephalopathic term infant with a history of birth trauma, low hematocrit, or coagulopathy. If CT findings are inconclusive, MRI should be performed between days 2 and 8 to assess the location and extent of injury. The pattern of injury identified with conventional MRI may provide diagnostic and prognostic information for term infants with evidence of encephalopathy. In particular, basal ganglia and thalamic lesions detected by conventional MRI are associated with poor neurodevelopmental outcome. Diffusion-weighted imaging may allow earlier detection of these cerebral injuries. RECOMMENDATIONS: US plays an established role in the management of preterm neonates of <30 weeks' gestation. US also provides valuable prognostic information when the infant reaches 40 weeks' postmenstrual age. For encephalopathic term infants, early CT should be used to exclude hemorrhage; MRI should be performed later in the first postnatal week to establish the pattern of injury and predict neurologic outcome.
Asunto(s)
Lesiones Encefálicas/diagnóstico , Recién Nacido , Tamizaje Neonatal/normas , Academias e Institutos/normas , Lesiones Encefálicas/diagnóstico por imagen , Humanos , Recien Nacido Prematuro , Imagen por Resonancia Magnética/métodos , Tamizaje Neonatal/métodos , Neurología/normas , Radiografía , UltrasonografíaRESUMEN
Xenon-133 inhalation hemispheric cerebral blood flow (HCBF) determinations at one to two days and four to six days postnatally and at 37 weeks postconceptual age have been correlated with computed tomography (CT) scan and autopsy findings in 15 preterm infants weighing less than 1,250 gm at birth. Ten of these infants had germinal matrix hemorrhages (GMH) or intraventricular hemorrhages (IVH). Although HCBF obtained at one to two days showed no mean difference between the GMH/IVH group and the nonhemorrhage infants, hemispheric flow ratios showed significant discrepancies in the GMH/IVH group. In addition, in four of five patients in whom the hemorrhage appeared asymmetric on CT scan, the side of higher flow correlated with the hemorrhage. At four to six days HCBF showed a lower mean value in the GMH/IVH patients than in the nonhemorrhage patients and differences in the interhemispheric ratios in the GMH/IVH group persisted. There were no differences in the mean HCBF values or hemispheric ratios between the two groups of infants at 37 weeks postconceptual age.
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Hemorragia Cerebral/fisiopatología , Ventrículos Cerebrales/irrigación sanguínea , Circulación Cerebrovascular , Enfermedades del Prematuro/fisiopatología , Hemorragia Cerebral/diagnóstico por imagen , Humanos , Lactante , Recién Nacido , Enfermedades del Prematuro/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Radioisótopos de XenónRESUMEN
BACKGROUND: For preterm infants, intraventricular hemorrhage (IVH) may be associated with adverse neurodevelopmental outcome. We have demonstrated that early low-dose indomethacin treatment is associated with a decrease in both the incidence and severity of IVH in very low birth weight preterm infants. In addition, we hypothesized that the early administration of low-dose indomethacin would not be associated with an increase in the incidence of neurodevelopmental handicap at 4.5 years of age in our study children. METHODS: To test this hypothesis, we provided neurodevelopmental follow-up for the 384 very low birth weight survivors of the Multicenter Randomized Indomethacin IVH Prevention Trial. Three hundred thirty-seven children (88%) were evaluated at 54 months' corrected age, and underwent neurodevelopmental examinations, including the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), the Peabody Picture Vocabulary Test-Revised (PPVT-R), and standard neurologic examinations. RESULTS: Of the 337 study children, 170 had been randomized to early low-dose indomethacin therapy and 167 children had received placebo. Twelve (7%) of the 165 indomethacin children and 11 (7%) of the 158 placebo children who underwent neurologic examinations were found to have cerebral palsy. For the 233 English-monolingual children for whom cognitive outcome data follow, the mean gestational age was significantly younger for the children who received indomethacin than for those who received placebo. In addition, although there were no differences in the WPPSI-R or the PPVT-R scores between the 2 groups, analysis of the WPPSI-R full-scale IQ by function range demonstrated significantly less mental retardation among those children randomized to early low-dose indomethacin (for the indomethacin study children, 9% had an IQ <70, 12% had an IQ of 70-80, and 79% had an IQ >80, compared with the placebo group, for whom 17% had an IQ <70, 18% had an IQ of 70-80, and 65% had an IQ >80). Indomethacin children also experienced significantly less difficulty with vocabulary skills as assessed by the PPVT-R when compared with placebo children. CONCLUSIONS: These data suggest that, for preterm neonates, the early administration of low-dose indomethacin therapy is not associated with adverse neurodevelopmental function at 54 months' corrected age.
Asunto(s)
Antiinflamatorios no Esteroideos/administración & dosificación , Hemorragia Cerebral/prevención & control , Ventrículos Cerebrales , Indometacina/administración & dosificación , Enfermedades del Prematuro/prevención & control , Antiinflamatorios no Esteroideos/efectos adversos , Daño Encefálico Crónico/etiología , Daño Encefálico Crónico/prevención & control , Hemorragia Cerebral/etiología , Preescolar , Relación Dosis-Respuesta a Droga , Femenino , Estudios de Seguimiento , Humanos , Indometacina/efectos adversos , Lactante , Recién Nacido , Enfermedades del Prematuro/etiología , Masculino , Examen Neurológico/efectos de los fármacos , Pruebas Neuropsicológicas , EmbarazoRESUMEN
BACKGROUND: Despite improvements in survival data, the incidence of neurodevelopmental handicaps in preterm infants remains high. To prevent these handicaps, one must understand the pathophysiology behind them. For preterm infants, cerebral ventriculomegaly (VM) may be associated with adverse neurodevelopmental outcome. We hypothesized that although the causes of VM are multiple, the incidence of handicap at 4.5 years of age in preterm infants with this ultrasonographic finding at term would be high. METHODS: To test this hypothesis, we provided neurodevelopmental follow-up for all 440 very low birth weight survivors of the Multicenter Randomized Indomethacin Intraventricular Hemorrhage (IVH) Prevention Trial. A total of 384 children (87%) were evaluated at 54 months' corrected age (CA), and 257 subjects were living in English-speaking, monolingual households and are included in the following data analysis. RESULTS: Moderate to severe low pressure VM at term was documented in 11 (4%) of the English-speaking, monolingual survivors. High grade IVH and bronchopulmonary dysplasia (BPD) were both risk factors for the development of VM. Of 11 (45%) children with VM, 5 suffered grades 3 to 4 IVH, compared with 2/246 (1%) children without VM who experienced grades 3 to 4 IVH. Similarly, 9/11 (82%) children with VM had BPD, compared with 120/246 (49%) children without VM who had BPD. Logistic regression analysis was performed using birth weight, gestational age, gender, Apgar score at 5 minutes, BPD, sepsis, moderate to severe VM, periventricular leukomalacia, grade of IVH, and maternal education to predict IQ <70. Although maternal education was an important and independent predictor of adverse cognitive outcome, in this series of very low birth weight prematurely born children, VM was the most important predictor of IQ <70 (OR: 19.0; 95% CI: 4.5, 80.6). Of children with VM, 6/11 (55%) had an IQ <70, compared with 31/246 (13%) of children without VM. Children with VM had significantly lower verbal and performance scores compared with children without VM. CONCLUSIONS: These data suggest that, for preterm neonates, VM at term is a consequence of the vulnerability of the developing brain. Furthermore, its presence is an important and independent predictor of adverse cognitive and motor development at 4.5 years' CA.
Asunto(s)
Ventrículos Cerebrales/patología , Discapacidades del Desarrollo/etiología , Recién Nacido de muy Bajo Peso , Displasia Broncopulmonar/complicaciones , Preescolar , Trastornos del Conocimiento/etiología , Escolaridad , Estudios de Seguimiento , Humanos , Recién Nacido , Inteligencia , Modelos Logísticos , Pronóstico , Factores de RiesgoRESUMEN
OBJECTIVES: Low-dose indomethacin has been shown to prevent intraventricular hemorrhage (IVH) in very low birth weight neonates, and long-term neurodevelopmental follow-up data are needed to validate this intervention. We hypothesized that the early administration of low-dose indomethacin would not be associated with adverse cognitive outcome at 36 months' corrected age (CA). METHODS: We enrolled 431 neonates of 600 to 1250 g birth weight with no IVH at 6 to 12 hours in a randomized, prospective trial to determine whether low-dose indomethacin would prevent IVH. A priori, neurodevelopmental follow-up examinations, including the Stanford-Binet Intelligence Scale and Peabody Picture Vocabulary Test-Revised, and standard neurologic examinations were planned at 36 months' CA. RESULTS: Three hundred eighty-four of the 431 infants survived (192 [92%] of 209 infants receiving indomethacin versus 192 [86%] of 222 infants receiving saline), and 343 (89%) children were examined at 36 months' CA. Thirteen (8%) of the 166 infants who received indomethacin and 14 (8%) of 167 infants receiving the placebo were found to have cerebral palsy. There were no differences in the incidence of deafness or blindness between the two groups. For the 248 English-monolingual children for whom IQ data follow, the mean gestational age was significantly younger for the infants who received indomethacin than for those who received the placebo. None of the 115 infants who received indomethacin was found to have ventriculomegaly on cranial ultrasound at term, compared with 5 of 110 infants who received the placebo. The mean +/- SD Stanford-Binet IQ score for the 126 English-monolingual children who had received indomethacin was 89.6 +/- 18.92, compared with 85.0 +/- 20.79 for the 122 English-monolingual children who had received the placebo. Although maternal education was strongly correlated with Stanford-Binet IQ at 36 months' CA, there was no difference in educational levels between mothers of the infants receiving indomethacin and the placebo. CONCLUSIONS: Indomethacin administered at 6 to 12 hours as prophylaxis against IVH in very low birth weight infants does not result in adverse cognitive or motor outcomes at 36 months' CA.
Asunto(s)
Hemorragia Cerebral/prevención & control , Desarrollo Infantil/efectos de los fármacos , Inhibidores de la Ciclooxigenasa/administración & dosificación , Indometacina/administración & dosificación , Enfermedades del Prematuro/prevención & control , Hemorragia Cerebral/diagnóstico por imagen , Hemorragia Cerebral/psicología , Distribución de Chi-Cuadrado , Preescolar , Inhibidores de la Ciclooxigenasa/efectos adversos , Humanos , Indometacina/efectos adversos , Lactante , Recién Nacido , Recien Nacido Prematuro , Enfermedades del Prematuro/diagnóstico por imagen , Enfermedades del Prematuro/psicología , Recién Nacido de muy Bajo Peso , Pruebas de Inteligencia/estadística & datos numéricos , Examen Neurológico/estadística & datos numéricos , Ultrasonografía Doppler TranscranealRESUMEN
OBJECTIVES: Parenchymal involvement of intraventricular hemorrhage (IVH) is a major risk factor for neurodevelopmental handicap in very low birth weight neonates. Previous trials have suggested that indomethacin would lower the incidence and severity of IVH in very low birth weight neonates. METHODS: We enrolled 431 neonates of 600- to 1250-g birth weight with no evidence for IVH at 6 to 11 hours of age in a prospective, randomized, placebo-controlled trial to test the hypothesis that low-dose indomethacin (0.1 mg/kg intravenously at 6 to 12 postnatal hours and every 24 hours for two more doses) would lower the incidence and severity of IVH. Serial cranial ultrasound examinations and echocardiographs were performed. RESULTS: There were no differences in the birth weight, gestational age, sex, Apgar scores, and percent of neonates treated with surfactant between the indomethacin and placebo groups. Within the first 5 days, 25 (12%) indomethacin-treated and 40 (18%) placebo-treated neonates developed IVH (P = .03, trend test). Only one indomethacin-treated patient experienced grade 4 IVH compared with 10 placebo-treated neonates (P = .01). Sixteen indomethacin-treated neonates and 29 control neonates died (P = .08); there was a difference favoring indomethacin with respect to survival time (P = .06). Eighty-six percent of all neonates had a patent ductus arteriosus on the first postnatal day; indomethacin was associated with significant ductal closure by the fifth day of life (P < .001). There were no differences in adverse events attributed to indomethacin between the two treatment groups. CONCLUSIONS: Low-dose prophylactic indomethacin significantly lowers the incidence and severity of IVH, particularly the severe form (grade 4 IVH). In addition, indomethacin closes the patent ductus arteriosus and is not associated with significant adverse drug events in very low birth weight neonates.
Asunto(s)
Hemorragia Cerebral/prevención & control , Indometacina/uso terapéutico , Recién Nacido de Bajo Peso , Conducto Arterioso Permeable/tratamiento farmacológico , Femenino , Humanos , Indometacina/administración & dosificación , Indometacina/efectos adversos , Recién Nacido , Recien Nacido Prematuro , Masculino , Estudios Prospectivos , Análisis de Regresión , Resultado del TratamientoRESUMEN
OBJECTIVES: To determine if cerebral palsy (CP) rates were lower in the active treatment group compared with the control group, as improved survival rates of very low-birth-weight infants are postulated to be the cause of the increased incidence of CP in preterm infants, to evaluate relationships between multiple prenatal, perinatal, and postnatal variables and CP to understand better its antecedents in very low-birth-weight infants in the era of surfactant replacement therapy, and to determine the usefulness of a cranial ultrasonographic (US) scan in predicting CP. DESIGN: Inception cohort follow-up study as part of a randomized controlled trial of low-dose indomethacin sodium for the prevention of intraventricular hemorrhage. SETTING: Neonatal intensive care units at 3 medical centers. PATIENTS: Infants with birth weights between 600 and 1250 g were eligible, and 505 infants were enrolled in the original study. Of these infants, 440 (87%) survived; neurologic examinations were completed on 381 infants (86%) at 36 months corrected age. MAIN OUTCOME MEASURES: Statistical analyses were performed to identify the antecedents of CP, including the results of frequent cranial US scans obtained throughout the newborn period. RESULTS: Cerebral palsy was found in 36 (9.5%) of 381 infants at 36 months corrected age (range, 33-39 months corrected age). Univariate analysis identified chorioamnionitis, treatment with surfactant, bronchopulmonary dysplasia, and abnormal cranial US findings as antecedents of CP. Periventricular leukomalacia and ventriculomegaly were associated with the highest detection rates for CP (37% and 30%, respectively) with acceptable false-positive rates. Multivariate analysis identified bronchopulmonary dysplasia and an abnormal cranial US scan showing grade 3 to 4 intraventricular hemorrhage, periventricular leukomalacia, or ventriculomegaly as independent predictors of CP. Odds ratios for the detection of CP using cranial US findings tabulated by hospital day were in the range of 7 to 26 beginning on day 2. CONCLUSION: The results suggest that cranial US findings are useful predictors of CP during a patient's stay in the hospital.
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Hemorragia Cerebral/tratamiento farmacológico , Parálisis Cerebral/diagnóstico , Ventrículos Cerebrales , Indometacina/uso terapéutico , Parálisis Cerebral/complicaciones , Parálisis Cerebral/prevención & control , Corioamnionitis/complicaciones , Femenino , Edad Gestacional , Humanos , Lactante , Recién Nacido , Recien Nacido Prematuro , Recién Nacido de muy Bajo Peso , Leucomalacia Periventricular/complicaciones , Embarazo , Estudios Retrospectivos , Tensoactivos/uso terapéuticoRESUMEN
During a 24-month period, nine neonates with a meningomyelocele were delivered. Of these, four meningomyeloceles were detected antenatally with ultrasound during the third trimester. Sonographic diagnosis was based upon a discontinuity in the fetal spine and the presence of a protruding sac. Obstetric management included serial sonography until fetal pulmonic maturity was established, and subsequent low transverse cesarean section. A method of atraumatic abdominal delivery is described. Neonatal management consisted of early closure of the spinal defect and appropriate shunting of hydrocephalus. A team approach to the perinatal management of meningomyelocele is recommended for optimal outcome.
Asunto(s)
Meningomielocele/cirugía , Diagnóstico Prenatal , Cesárea , Femenino , Humanos , Hidrocefalia/cirugía , Recién Nacido , Meningomielocele/diagnóstico , Embarazo , Tercer Trimestre del Embarazo , UltrasonografíaRESUMEN
Premature infants have been shown to undergo prolonged periods of sublethal hypoxia. There is considerable evidence to link these hypoxic events with neurodevelopmental disorders. As an animal model for this clinical problem, rats were raised from the third day of life in a chamber where the O2 level was 9.5%. After 30 days of hypoxia the rats were sacrificed and their brains processed for determination of the number of cortical neurons. This work was performed to test the hypothesis that chronic hypoxia would result in increased cortical cell death. The hypoxic rats had lower body and brain weights as well as decreased cortical volumes. However, hypoxic rats had increased neuronal density and significantly more cortical neurons than controls (P < 0.05). The results of this study suggest that chronic sublethal hypoxia may lead to reduction in the amount of programmed cell death in the developing neocortex.
Asunto(s)
Recuento de Células , Corteza Cerebral/patología , Hipoxia/patología , Animales , Modelos Animales de Enfermedad , Ratas , Factores de TiempoRESUMEN
Bronchopulmonary dysplasia remains a major cause of neurodevelopmental handicap in preterm infants. Because bronchopulmonary dysplasia may be associated with prolonged hypoxemia without obvious changes in systemic blood pressure, we developed an animal model of chronic sublethal hypoxia to test the hypothesis that this insult results in significant alterations in corticogenesis in the developing brain. Three groups of newborn rats were placed in a chamber with FIO2 9.5% on postnatal day 3 (P3). One group was sacrificed at P13; a second group was sacrificed at P33, and the third group was removed at P33 and reared in normoxia until sacrifice at P63. Control rats were those raised in room air for the corresponding periods of time. Rats were transcardially perfused and the brains were embedded in celloidin and prepared for morphometric analysis using standard stereology methods. Although experimental rat pups in the third group demonstrated 'catch-up' of body weight following return to normoxia, these studies demonstrated both failure of brain growth (p<0.01) and progressive cerebral ventriculomegaly (p<0.01). Decreased subcortical white matter (p<0. 05) and corpus callosum size (p<0.01) were noted at P63 in pups reared under conditions of chronic hypoxia. Decreases in cortical volume (p<0.05) were noted at all three experimental time points for hypoxic-reared pups when compared to control animals. These data suggest that chronic sublethal hypoxia may lead to severe impairments in corticogenesis in an animal model of developing brain.
Asunto(s)
Ventrículos Cerebrales/crecimiento & desarrollo , Ventrículos Cerebrales/patología , Cuerpo Calloso/crecimiento & desarrollo , Cuerpo Calloso/patología , Hipoxia Encefálica/patología , Animales , Animales Recién Nacidos , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/crecimiento & desarrollo , Corteza Cerebral/patología , Ventrículos Cerebrales/efectos de los fármacos , Enfermedad Crónica , Cuerpo Calloso/efectos de los fármacos , Tamaño de los Órganos , Oxígeno/farmacología , RatasRESUMEN
When exposed to chronic sublethal hypoxia the developing brain responds with increases in permeability and angiogenesis. Vascular endothelial growth factor (VEGF) may mediate this response. Here, we present data on the localization of VEGF in the rat brain cortex during postnatal development and its correlation to vascularization. We reared newborn rats under normoxic conditions and in hypoxic chambers (FiO(2) 9.5%), removed them at postnatal days (P) 3, 8, 13, 24, and 33 and prepared the cortical brain tissue for immunohistochemistry, in situ hybridization (ISH), Western blot analyses and vessel density counting. When compared to age-matched controls, hypoxic-reared animals displayed a significant increase in platelet endothelial cell adhesion molecule 1 (PECAM-1) protein levels, cerebral microvascular lumen diameter and number and density of vessels (number of capillaries per area). In control animals, ISH and immunohistochemistry revealed that localization of VEGF is restricted almost exclusively to cortical neurons at early stages of development. As the vascular bed begins to stabilize, predominant VEGF expression switches to maturing glial cells which invest vessels while neuronal expression is reduced to a basal level. In hypoxic animals, early localization of VEGF is also restricted to cortical neurons, however, during later developmental stages, glial cells express elevated levels of VEGF protein and high neuronal expression also persists. Thus chronic sublethal hypoxia disrupts the temporal-spatial expression of VEGF, which correlates with continuing hypoxia-driven angiogenesis.
Asunto(s)
Corteza Cerebral/crecimiento & desarrollo , Corteza Cerebral/metabolismo , Factores de Crecimiento Endotelial/biosíntesis , Hipoxia Encefálica/metabolismo , Linfocinas/biosíntesis , Neovascularización Fisiológica , Neuronas/metabolismo , Animales , Animales Recién Nacidos , Recuento de Células , Corteza Cerebral/irrigación sanguínea , Corteza Cerebral/patología , Enfermedad Crónica , Factores de Crecimiento Endotelial/genética , Regulación del Desarrollo de la Expresión Génica , Proteína Ácida Fibrilar de la Glía/metabolismo , Hipoxia Encefálica/patología , Linfocinas/genética , Microcirculación/metabolismo , Microcirculación/patología , Neuroglía/metabolismo , Neuronas/citología , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , ARN Mensajero/metabolismo , Ratas , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
Chronic sublethal hypoxia has been associated with changes in neurovascular behavior, mediated, in part, by induction of vascular endothelial growth factor-A (VEGF-A(165)). In this report we demonstrate that RBE4 cells (derived from rodent cerebral microvasculature), when cultured in three-dimensional collagen gels: (1) Are induced to undergo increased tube formation in response to VEGF-A(165) in a dose-dependent manner; (2) undergo apoptosis under mild hypoxic conditions; (3) are rescued from the effects of hypoxia by the addition of exogenous VEGF-A(165) in a dose-dependent and inhibitable manner or by co-culture with primary newborn rat astrocytes, which are induced to express increased amounts of VEGF-A in hypoxic conditions. Further, we demonstrate that: (4) The observed astrocyte-produced, VEGF-mediated protection from apoptosis (survival) is inhibitable with soluble recombinant VEGF receptor-1 (sFlt), and is associated with a robust induction of MAPK tyrosine phosphorylation. These findings illustrate the importance of VEGF in the process of neurovascular survival in response to injury in developing brain and provide insight into the signaling pathways involved.
Asunto(s)
Astrocitos/metabolismo , Factores de Crecimiento Endotelial/metabolismo , Endotelio Vascular/citología , Hipoxia Encefálica/metabolismo , Linfocinas/metabolismo , Proteínas Serina-Treonina Quinasas , Animales , Animales Recién Nacidos , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Astrocitos/citología , Comunicación Celular/fisiología , Técnicas de Cultivo de Célula/métodos , División Celular/efectos de los fármacos , División Celular/fisiología , Hipoxia de la Célula/efectos de los fármacos , Hipoxia de la Célula/fisiología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Técnicas de Cocultivo , Colágeno , Factores de Crecimiento Endotelial/farmacología , Geles , Linfocinas/farmacología , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Fosforilación , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-akt , Ratas , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
The risk period for intraventricular hemorrhage (IVH) of the preterm neonate is the first 3-4 postnatal days. For infants of < 34 weeks' gestation, this risk period is independent of gestational age. We hypothesized that this risk period is attributable to the perinatal induction of maturation of the germinal matrix microvasculature and tested this hypothesis by examining changes in the classical ultrastructural features of the blood-brain barrier over the first ten postnatal days in the newborn beagle model for neonatal IVH. Newborn beagle pups (n = 6) were anesthetized and systemically perfused and the brains were removed and prepared for electron microscopic examination. Examination of electron micrographs from the germinal matrix of animals on the first, fourth and tenth postnatal days demonstrated no difference in perimeter lengths and capillary and endothelial cell areas; in contrast, luminal areas significantly decreased across postnatal age (P = 0.04). Significant increases were found in basement membrane area between days 1 and 4 (P = 0.01) and tight junction length (day 1 vs. day 10, P = 0.02). In addition, on day 1, 19% of germinal matrix capillary perimeter was determined not to be covered by supporting cell processes, while by day 10, only 5% was bare. In contrast, the microvessels of the white matter exhibited no changes in these parameters during these three time points. These studies are consistent with the concept that basal lamina deposition and organization precede increases in endothelial cell tight junction formation and coverage by supporting cells.
Asunto(s)
Hemorragia Cerebral/fisiopatología , Microcirculación/fisiología , Animales , Membrana Celular , Modelos Animales de Enfermedad , Femenino , Humanos , Recién Nacido , Microscopía Electrónica , Factores de RiesgoRESUMEN
Although chronic sublethal hypoxia has been shown to promote angiogenesis in the developing brain, the pathogenesis of this response is unknown. We hypothesized that this response may be mediated in part by vascular endothelial growth factor (VEGF). We reared newborn rats (P3) in a chamber with FIO2 of 9.5 +/- 1% (exposed, E). At P33, the animals were removed from the chamber and the brains prepared for immunohistochemistry, mRNA extraction, or horseradish peroxidase (HRP) permeability studies. We also isolated beagle brain germinal matrix endothelial cells from PND 1 beagle pups and placed them in three-dimensional (3-D) coculture with PND 1 rat forebrain astrocytes. Cultures were grown for 6 days in 11% O2 and compared to control 3-D cocultures. When compared to age-matched controls, the experimental rats had significantly increased cortical vascular density (vessels/mm2: 518 +/- 18 vs. 400 +/- 15, P = 0.025). HRP studies demonstrated significantly increased permeability in all cortical vessels examined in experimental rats compared to controls. Compared to controls, VEGF mRNA from hypoxic pups was increased 2.4 times, and immunohistochemical studies of VEGF protein confirmed this finding. Similarly, when compared to controls, hypoxic cocultures of brain microvascular endothelial cells and astrocytes demonstrated significant increase in tubelike structures representing in vitro angiogenesis. Additionally, astrocyte VEGF protein levels increased 4.4-fold in hypoxic compared to control astrocyte cultures and VEGF protein levels increased 1.7-fold in hypoxic compared to control cocultures. Finally, addition of VEGF (10 ng/ml culture medium) to BBMEC alone in 3-D culture elicited not only significant proliferation (P = 0.001) but also increased tube formation. These data demonstrate that the developing brain responds to chronic sublethal hypoxia with increases in permeability and angiogenesis and suggest that VEGF mediates this response.
Asunto(s)
Corteza Cerebral/irrigación sanguínea , Factores de Crecimiento Endotelial/farmacología , Factores de Crecimiento Endotelial/fisiología , Endotelio Vascular/efectos de los fármacos , Hipoxia Encefálica/fisiopatología , Linfocinas/farmacología , Linfocinas/fisiología , Neovascularización Patológica/prevención & control , Neovascularización Fisiológica/efectos de los fármacos , Animales , Animales Recién Nacidos , Astrocitos/citología , Astrocitos/fisiología , División Celular/efectos de los fármacos , Hipoxia de la Célula , Células Cultivadas , Técnicas de Cocultivo , Factores de Crecimiento Endotelial/biosíntesis , Endotelio Vascular/citología , Hipoxia Encefálica/patología , Linfocinas/biosíntesis , Microcirculación , ARN Mensajero/biosíntesis , Ratas , Ratas Sprague-Dawley , Transcripción Genética , Factor A de Crecimiento Endotelial Vascular , Factores de Crecimiento Endotelial VascularRESUMEN
The neurodevelopmental outcome of very low birth weight infants experiencing early-onset intraventricular hemorrhage (IVH) occurring within the first 6 postnatal hours was compared with that of their peers without early-onset IVH at 3 years corrected age. The 440 surviving preterm infants (birth weight 600 to 1,250 g) who had been enrolled in a multicenter, prospectively randomized, controlled trial evaluating the efficacy of postnatal indomethacin to prevent IVH were evaluated with the Stanford-Binet Intelligence Scale and neurological examinations at 3 years corrected age. All study infants had echoencephalography between 5 and 11 hours of life, and testing is reported for all children residing in English monolingual households at 3 years corrected age (i.e., from the obstetric due date). Fifty five of the 73 (75%) infants with IVH within the first 5 to 11 hours survived to 3 years of age, compared with 385 of the 432 (89%) children without early-onset hemorrhage who were alive at 3 years corrected age (P<.001). Eleven of the 29 (38%) English monolingual children with early-onset IVH had Stanford-Binet intelligence quotient scores of less than 70, compared with 47 of the 249 (19%) children without early IVH (P = .03). Similarly, 7 of 28 (25%) early IVH children were found to have cerebral palsy, compared with 20 of 241 (8%) children without early IVH (P = .01). These data suggest that infants who experience the early onset of IVH are at high risk for both cognitive and motor handicaps at 3 years corrected age.
Asunto(s)
Encefalopatías/epidemiología , Hemorragia Cerebral/complicaciones , Recién Nacido de muy Bajo Peso , Envejecimiento , Encefalopatías/etiología , Hemorragia Cerebral/diagnóstico por imagen , Hemorragia Cerebral/prevención & control , Parálisis Cerebral/epidemiología , Parálisis Cerebral/etiología , Humanos , Indometacina/uso terapéutico , Recién Nacido , Pruebas de Inteligencia , Estudios Prospectivos , UltrasonografíaRESUMEN
The Glasgow Coma Scale, which was designed to evaluate level of consciousness after head trauma, has been compared to the Lovejoy scale in 21 patients with Reye's syndrome. Like other investigators, we have noted a poorer prognosis in those patients with higher peak NH3 levels and rapid progression of disease. However, we have also noted that the Glasgow coma scale provides a better, earlier indicator of progressive central nervous system disease than the Lovejoy scale and, therefore, helps physicians caring for such patients to institute intracranial pressure (ICP) monitoring and vigorous measures for the control of elevated ICP earlier than they might otherwise.