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CXC chemokine receptors in the central nervous system: Role in cerebellar neuromodulation and development.

Chemokines and their receptors are constitutively present in the central nervous system (CNS), expressed in neurons and glial cells. Much evidence suggests that, beyond their involvement in neuroinflammation, these proteins play a role in neurodevelopment and neurophysiological signaling. The goal of this review is to summarize recent information concerning expression, signaling, and function of CXC chemokine receptor in the CNS, with the main focus on the developmental and neuromodulatory actions of chemokines in the cerebellum.

Cerebellum↗

Interaction between Plasmodium falciparum and human immunodeficiency virus type 1 on the central nervous system of African children.

Plasmodium falciparum and human immunodeficiency virus type 1 (HIV-1) infections are common in children living in sub-Saharan Africa (SSA). Both of these pathogens affect the central nervous system (CNS). Most HIV-1 infection of children in this region is acquired from infected mothers, particularly during breast-feeding and at the time of delivery. Over a third of children infected by birth will have died before their first birthday, before overt CNS manifestations have developed. The most common manifestations of primary CNS infection include neurodevelopmental delay, impaired brain growth, motor deficits, and behavioral problems. These deficits may also result from infections, neoplasm, or stroke. Cognitive impairments become more evident if the child survives for longer, but in Africa, children rarely survive past their fifth birthday. In malaria endemic areas, severe falciparum malaria usually develops after 6 months of age, and most of the CNS manifestations are more common in children over 1 year old. About 11% of children develop neurological deficits following cerebral malaria, most of which improve within 2 years of the insult. However, up to 24% of children may have neurocognitive impairments following severe malaria. The effect of milder malaria and coincidental parasitization on cognitive function is unknown. Other comorbidities that are common in SSA, such as malnutrition or micronutrient deficiencies, may influence children's neurodevelopment. The coinfection of malaria and HIV-1 may aggravate the neurodevelopmental impairments documented in these children. However, to date there are little published data, although it may have a profound effect of children living in SSA.

Africa↗

Somatosensory and visual evoked potentials in children with cerebral palsy: correlations and discrepancies with MRI findings and clinical picture.

PURPOSE: To determine if there is any association between the findings of visual evoked potentials (VEPs), somatosensory evoked potentials (SEPs), and magnetic resonance imaging (MRI) findings with the neurodevelopment and severity in children with cerebral palsy (CP). METHODS: The present study included 15 children with spastic diplegic CP and five children with spastic hemiplegic CP and 42 healthy children as controls. The number of the controls was two-times greater than the study group to increase statistical power of this study. VEPs and SEPs were recorded in the CP children and compared with healthy controls. All MR scans were obtained using a 1.5 T MR scanner. RESULTS: A significant difference was found in the latencies P100 (VEP) between the CP and controls. No correlations between increased P100 latencies and asphyxia, prematurity, the CP severity, MRI findings and mental retardation were noted. A significant difference in N13-N20 conductions (SEPs) between the subjects with CP and the control group was found. SEPs were positively correlated with mental retardation in CP children. The brain lesions in MRI showed a significant correlation with the CP severity scores and mental retardation. CONCLUSION: The differences in VEPs and SEPs were determined between CP children and healthy children. The MRI findings were positively correlated with the CP severity and mental retardation.

Adolescent↗

Using a parental checklist to identify diagnostic groups in children with communication impairment: a validation of the Children's Communication Checklist--2.

BACKGROUND: The Children's Communication Checklist (CCC 1998) was revised in 2003 (CCC-2) to provide a general screen for communication disorder and to identify pragmatic/social interaction deficits. Two validation studies were conducted with different populations of children with language and communication impairments. METHODS & PROCEDURES: In Study 1, the questionnaire was given to families of 87 children attending full-time special education for specific language impairment, pragmatic language impairments or autistic spectrum disorders. In addition, the teachers of half the sample completed CCC-2 forms for the same children, providing evidence for interrater agreement. In Study 2, the sample was increased to include 24 children with similar diagnoses in educational contexts in Scotland and 27 children referred for clinical evaluation at a neurodevelopment centre. OUTCOMES & RESULTS: The CCC-2 distinguished children with communication impairments from non-impaired peers. Furthermore, the social-interaction deviance composite (SIDC) of the CCC-2 identified children with disproportionate pragmatic and social difficulties in relation to their structural language impairments. This measure also had good interrater agreement (r=0.79). CONCLUSIONS: CCC-2 provides a useful screening measure for communication impairment and can be helpful in identifying children who should be referred for more detailed assessment of possible autistic spectrum disorder. However, the present data highlight substantial overlap amongst groups with 'distinct' diagnoses. It is suggested that it is unrealistic to use the CCC-2 to make categorical distinctions on this continuum of disorder.

Child↗

Perinatal exposure to polychlorinated biphenyls differentially affects cerebellar development and motor functions in male and female rat neonates.

Perinatal exposure to polychlorinated biphenyls (PCBs) interacts with genetics and impacts the course of the central nervous system (CNS) development in both humans and animals. To test the hypothesis that the neurobehavioral impairments, and specifically motor dysfunctions following perinatal PCB exposure in rats are associated with changes in a specific brain region, the cerebellum, we compared neurodevelopment, motor behavior, cerebellar structure, and protein expression in rat neonates exposed to the PCB mixture Aroclor 1254 (A1254, 10.0 mg/kg/day) from gestational day 11 until postnatal day (P) 21 with that of controls. Body mass of PCB-exposed pups was not affected at birth, but was significantly lower than that of controls between birth and weaning; by P21 the difference was greater in females than in males. A1254 exposure delayed ear unfolding and impaired performance on the following behavioral tests: (1) righting response on P3-P6; (2) negative geotaxis on P5-P7; (3) startle response on P10-P12; and (4) a rotorod on P12, with PCB-male pups more severely affected than female. Changes in the behavior of PCB pups were associated with changes in cerebellar structure and protein expression. Cerebellar mass was more reduced in PCB-male than PCB-female pups. Analysis of selected cerebellar proteins revealed an increase in GFAP expression, greater in male than in female, and a decrease in L1 expression in both sexes. These results suggest that PCB exposure affects behavior and cerebellar development differently in male and female rat neonates, with greater effects in males. Further studies of neonatal PCB exposure will establish whether the environmental pollutants can contribute to the sex-related preponderance of certain neuropsychiatric disorders.

Analysis of Variance↗

The antenatal development of fetal behavioral patterns assessed by four-dimensional sonography.

The investigation of fetal intrauterine activities has been enabled by the development of two-dimensional ultrasound. It has been shown that the earliest signs of fetal motor activity can be in the late embryonic period, and that the characteristics of fetal motor patterns change constantly throughout gestation. During the first trimester of pregnancy, the repertoire and frequency fetal movement patterns constantly expand, whereas the second and third trimesters are characterized by the progressive organization of fetal activities into complex and clearly distinct behavioral patterns. The comparison of real time ultrasonic studies of fetal behavior with the morphological studies of fetal brains has revealed that the appearance of new behavioral patterns or the transition of existing patterns directly reflect the complex neurodevelopment processes. It has been suggested that the assessment of fetal behavioral patterns could give us insight into the integrity of fetal central nervous system and enable the early detection of cerebral dysfunctions. The development of a new ultrasonic technique, four dimensional sonography, could represent a significant improvement in the assessment of fetal behavior. According to the preliminary results, this new technique could open a new perspective for the investigations of fetal behavioral patterns and contribute significantly to our better understanding of complex neurodevelopmental events. The most important neurodevelopmental events, the basic technology of 4D ultrasound and its application in the assessment of functional development of fetal central nervous system will be the subject of this review.

Animals↗

Perinatal and neurodevelopmental outcome with isolated fetal ventriculomegaly: a systematic review.

OBJECTIVE: To establish the perinatal and neurodevelopmental outcomes of fetuses diagnosed with isolated ventriculomegaly (IVM). METHODS: A systematic review of cohort, case/control studies, case series and case reports of IVM (unilateral or bilateral enlargement of the lateral ventricle, >or=10 mm, with no additional diagnosis at the time of the initial ultrasound), identified by searching, without language restrictions, The Cochrane Library, MEDLINE and Embase databases in June 2004. RESULTS: No cohort study was retrieved but 577 cases were identified in one case/control study and 29 case series/case reports. Of 207 cases with follow-up and known gestational age at diagnosis, normal developmental outcomes were found in 82%, mild impairments in 9% and moderate/severe impairments in 10%. Prenatal diagnosis could possibly have reduced the risk of moderate/severe impairments to 7%. In 137 cases followed to at least 20 months of age, 79% had normal neurodevelopment, 10% were mildly delayed and 11% had moderate/severe developmental delays. CONCLUSIONS: Outcome was favorable in 85% of IVM cases, decreasing to 79% when cases were followed to at least 20 months of age. We recommend prospective cohort studies with new diagnostic modalities to better identify the underlying conditions relating to moderate/severe impairments in the remaining cases.

Cerebral Ventricles↗

Study of the reproductive effects in rats surgically implanted with depleted uranium for up to 90 days.

In 2001, the Naval Health Research Center Toxicology Detachment was funded by the U.S. Army Medical Research Acquisition Activity (USAMRAA) to conduct a study of the effects of surgically implanted depleted uranium (DU) pellets on adult rat reproductive success and development across two successive generations. This article presents some of the findings for the group of offspring from adult rats mated at 30 d post surgical implantation of DU pellets. Adult male and female Sprague-Dawley rats (P1 generation) were surgically implanted with 0, 4, 8, or 12 DU pellets (1 x 2 mm). The P1 generation was then cross-mated at 30 d post surgical implantation. Urine collected from P1 animals at 27 d post surgical implantation showed that DU was excreted in the urine of DU-implanted animals in a dose-dependent manner. DU surgical implantation did not have a negative impact on P1 reproductive success, survival, or body weight gain through post surgical implantation d 90. There were no statistically significant differences in F1 birth weight, survival, and litter size at postnatal day (PND) 0, 5, and 20. No gross physical abnormalities identified in the offspring were attributable to neonatal DU exposure. A series of neurodevelopment and immune function assessments were also conducted on F1 offspring. No group differences were observed that were related to parental DU exposure. Studies are ongoing on the impact of leaving DU embedded in soft tissue for 120 d on rat reproduction and subsequent offspring survival and development.

Animals↗

Potential effects of certain persistent organic pollutants and endocrine disrupting chemicals on the health of children.

Persistent organic pollutants are lipophilic, man-made chemicals that are highly resistant to degradation. Due to their persistence, they have become distributed in small quantities throughout the world. They bioaccumulate in thefood chain and are stored in fatty tissues. Biomagnifications up the food chain result in potential widespread human exposure to these chemicals. Exposure to persistent organic pollutants has been associated with many adverse human health effects, including impaired neurodevelopment, immune and reproductive function. Many persistent organic pollutants also possess the ability to disrupt the normal functioning of the endocrine system. There is an increasing concern that low-level exposure to these endocrine disrupting chemicals may have adverse health impacts, particularly during fetal, neonatal, and childhood development. Both the nature and severity of health outcomes may depend on the developmental time-period during which chemical exposure occurs. This report summarizes scientific evidence on health effects of low-level exposure to persistent organic pollutants and endocrine disrupting chemicals.

Animals↗

Paroxetine use throughout pregnancy: does it pose any risk to the neonate?

A newborn of a SSRI-treated mother presented with lethargy, no crying, and no response to tactile stimulation. EEG findings were abnormal. Laboratory and clinical evaluations were normal. He recovered at the age of two weeks. Serotonin is a neurotransmitter that has an important roll in pain modulation during fetal neurodevelopment. We suspect these symptoms are attributed to the intrauterine exposure to paroxetine, through modulation of pain signals.

Abnormalities, Drug-Induced↗

Fetal glucocorticoid exposure and hypothalamo-pituitary-adrenal (HPA) function after birth.

The fetus may be exposed to increased endogenous glucocorticoid or synthetic glucocorticoid in late gestation. Indeed, 7-10% of pregnant women in Europe and North America are treated with synthetic glucocorticoid to promote lung maturation in fetuses at risk of preterm delivery. Such therapy is effective in reducing respiratory complications. However, very little is known about the mechanisms by which synthetic glucocorticoid or prenatal stress influence neurodevelopment in the human, or whether specific time windows of increased sensitivity exist. Glucocorticoids are essential for many aspects of normal brain development. However, there is growing evidence that exposure of the fetal brain to excess glucocorticoid can have lifelong effects on neuroendocrine function and behavior. We have shown that both endogenous glucocorticoid and synthetic glucocorticoid exposure has a number of rapid effects in the fetal brain in late gestation, including modification of neurotransmitter systems and transcriptional machinery. Such fetal exposure permanently alters hypothalamo-pituitary-adrenal (HPA) function in prepubertal, postpubertal, and aging offspring, in a sex-dependent manner. These effects are linked to changes in central glucocorticoid feedback machinery after birth. Prenatal glucocorticoid manipulation also leads to modification of HPA-associated behaviors, brain and organ morphology, as well as altered regulation of other endocrine systems. Permanent changes in endocrine function will have a long-term impact on health, since elevated cumulative exposure to endogenous glucocorticoid is linked to the premature onset of pathologies associated with aging.

Animals↗

The triple A syndrome is due to mutations in ALADIN, a novel member of the nuclear pore complex.

The triple A syndrome (MIM#231550) is a rare autosomal recessive disorder characterized by adrenocorticotropic hormone (ACTH) resistant adrenal failure, achalasia, alacrima, and a variety of neurological and dermatological features. The triple A syndrome is caused by mutations in the AAAS gene, which encodes a protein known as ALADIN (ALacrima Achalasia aDrenal Insufficiency Neurologic disorder). ALADIN is a new WD-repeat protein that has no significant homology to any previously identified WD-repeat protein. It has been shown that it colocalizes with nuclear pore complexes (NPCs), a finding that strongly suggests an involvement of ALADIN in nucleocytoplasmic transport. An investigation of 110 families with triple A syndrome disclosed mutation hot spots including Q15K (exon 1), and S293P (exon 8), which occur in 17 and 21 families from different geographical regions, respectively. The variable phenotype of all patients cannot be correlated with the localization and the nature of the ALADIN mutations. Thus, modifying genes/factors may be involved in the progression of this neurodegenerative disease. The lack of AAAS mutations in eight patients and negative linkage to chromosome 12q13 in three families are suggestive of genetic heterogeneity. To examine the cellular localization of ALADIN mutants causing triple A syndrome, we investigated nine different ALADIN-mutants: 2 nonsense (W84X, Q456X), 2 frameshift (F157fsX171, G397fsX414) and 5 point mutations (Q15K, L25P, H160R, S263P, L381R) by transfection experiments with green fluorescence protein. Mutants were predominantly localized in the cytoplasm, but also found in the nucleus indicating that ALADIN is essential for NPC targeting. To investigate physiological functions of ALADIN in vivo, we generated and analysed Aaas-/- knockout mice by homologous recombination in embryonic stem cells. Surprisingly, required animals lack any gross abnormality in adrenal and nervous system function. Further studies have to investigate the role of ALADIN at NPCs and to identify interacting proteins. Functional analyses of ALADIN may permit further understanding of its role for adrenocortical function and neurodevelopment.

Adrenal Gland Diseases↗

Mutations in microcephalin cause aberrant regulation of chromosome condensation.

Microcephalin (MCPH1) is a gene mutated in primary microcephaly, an autosomal recessive neurodevelopmental disorder in which there is a marked reduction in brain size. PCC syndrome is a recently described disorder of microcephaly, short stature, and misregulated chromosome condensation. Here, we report the finding that MCPH1 primary microcephaly and PCC syndrome are allelic disorders, both having mutations in the MCPH1 gene. The two conditions share a common cellular phenotype of premature chromosome condensation in the early G2 phase of the cell cycle, which, therefore, appears to be a useful diagnostic marker for individuals with MCPH1 gene mutations. We demonstrate that an siRNA-mediated depletion of MCPH1 is sufficient to reproduce this phenotype and also show that MCPH1-deficient cells exhibit delayed decondensation postmitosis. These findings implicate microcephalin as a novel regulator of chromosome condensation and link the apparently disparate fields of neurogenesis and chromosome biology. Further characterization of MCPH1 is thus likely to lead to fundamental insights into both the regulation of chromosome condensation and neurodevelopment.

Animals↗

Identification of FOXP2 truncation as a novel cause of developmental speech and language deficits.

FOXP2, the first gene to have been implicated in a developmental communication disorder, offers a unique entry point into neuromolecular mechanisms influencing human speech and language acquisition. In multiple members of the well-studied KE family, a heterozygous missense mutation in FOXP2 causes problems in sequencing muscle movements required for articulating speech (developmental verbal dyspraxia), accompanied by wider deficits in linguistic and grammatical processing. Chromosomal rearrangements involving this locus have also been identified. Analyses of FOXP2 coding sequence in typical forms of specific language impairment (SLI), autism, and dyslexia have not uncovered any etiological variants. However, no previous study has performed mutation screening of children with a primary diagnosis of verbal dyspraxia, the most overt feature of the disorder in affected members of the KE family. Here, we report investigations of the entire coding region of FOXP2, including alternatively spliced exons, in 49 probands affected with verbal dyspraxia. We detected variants that alter FOXP2 protein sequence in three probands. One such variant is a heterozygous nonsense mutation that yields a dramatically truncated protein product and cosegregates with speech and language difficulties in the proband, his affected sibling, and their mother. Our discovery of the first nonsense mutation in FOXP2 now opens the door for detailed investigations of neurodevelopment in people carrying different etiological variants of the gene. This endeavor will be crucial for gaining insight into the role of FOXP2 in human cognition.

Alternative Splicing↗

Mutation in Rab3 GTPase-activating protein (RAB3GAP) noncatalytic subunit in a kindred with Martsolf syndrome.

We identified a homozygous missense mutation in the noncatalytic subunit (RAB3GAP2) of RAB3GAP that results in abnormal splicing in a family with congenital cataracts, hypogonadism, and mild mental retardation (Martsolf syndrome). Recently, mutations in the catalytic subunit of RAB3GAP (RAB3GAP1), a key regulator of calcium-mediated hormone and neurotransmitter exocytosis, were reported in Warburg micro syndrome, a severe neurodevelopmental condition with overlapping clinical features. RAB3GAP is a heterodimeric protein that consists of a catalytic subunit and a noncatalytic subunit encoded by RAB3GAP1 and RAB3GAP2, respectively. We performed messenger RNA-expression studies of RAB3GAP1 and RAB3GAP2 orthologues in Danio rerio embryos and demonstrated that, whereas developmental expression of rab3gap1 was generalized (similar to that reported elsewhere in mice), rab3gap2 expression was restricted to the central nervous system. These findings are consistent with RAB3GAP2 having a key role in neurodevelopment and may indicate that Warburg micro and Martsolf syndromes represent a spectrum of disorders. However, we did not detect RAB3GAP2 mutations in patients with Warburg micro syndrome. These findings suggest that RAB3GAP dysregulation may result in a spectrum of phenotypes that range from Warburg micro syndrome to Martsolf syndrome.

Abnormalities, Multiple↗

Comparative study of mortality and morbidity in premature infants (birth weight, < 1,250 g) with candidemia or candidal meningitis.

Little information is available on long-term neurodevelopment of premature neonates with invasive candidal infections. We retrospectively studied the outcomes for 25 premature neonates (birth weight, < 1,250 g) with candidemia or candidal meningitis (cases) and compared them with 25 neonates matched for birth weight (+/- 100 g) and gestational age (+/- 1 week) (controls). Durations of antibiotic therapy, artificial ventilation, invasive catheterizations, and hyperalimentation were longer for cases than for controls. Cases had a higher final grade of intraventricular hemorrhage than did controls (median: 3.0 vs. 2.5, respectively; P < .05). Forty-four percent (11 of 25) of cases and 16% (4 of 25) of controls died (P > .05), and 29% (4 of 14) of surviving cases and 14% (3 of 21) of controls were disabled (P > .05). More cases had combined mortality and neurodevelopmental disabilities than did controls (60% vs. 28%, respectively; P < .05). Use of invasive therapies should be minimized for premature neonates at risk for invasive candidal infection that is associated with adverse outcomes.

Candida↗

Effects of environmental synthetic chemicals on thyroid function.

Synthetic chemicals are released into the environment by design (pesticides) or as a result of industrial activity. It is well known that natural environmental chemicals can cause goiter or thyroid imbalance. However, the effects of synthetic chemicals on thyroid function have received little attention, and there is much controversy over their potential clinical impact, because few studies have been conducted in humans. This article reviews the literature on possible thyroid disruption in wildlife, humans, and experimental animals and focuses on the most studied chemicals: the pesticides DDT, amitrole, and the thiocarbamate family, including ethylenethiourea, and the industrial chemicals polyhalogenated hydrocarbons, phenol derivatives, and phthalates. Wildlife observations in polluted areas clearly demonstrate a significant incidence of goiter and/or thyroid imbalance in several species. Experimental evidence in rodents, fish, and primates confirms the potentiality for thyroid disruption of several chemicals and illustrates the mechanisms involved. In adult humans, however, exposure to background levels of chemicals does not seem to have a significant negative effect on thyroid function, while exposure at higher levels, occupational or accidental, may produce mild thyroid changes. The impact of transgenerational, background exposure in utero on fetal neurodevelopment and later childhood cognitive function is now under scrutiny. There are several studies linking a lack of optimal neurological function in infants and children with high background levels of exposure to polychlorinated biphenyls (PCBs), dioxins, and/or co-contaminants, but it is unclear if the effects are caused by thyroid disruption in utero or direct neurotoxicity.

Amitrole↗

Fatty acid composition of brain, retina, and erythrocytes in breast- and formula-fed infants.

Breast-fed infants score better on visual and developmental tests than do formula-fed infants and this has been related to higher concentrations of erythrocyte docosahexaenoic acid (DHA, 22:6 omega 3). This prompted an investigation into the relationship between brain, retina, and erythrocyte fatty acids and diet in infancy. Total lipids of erythrocytes, retina, and brain cortex from 35 term infants were analyzed by capillary gas chromatography. Breast-fed infants had a greater proportion of DHA in their erythrocytes and brain cortex relative to those fed formula (P < 0.005) but differences were not observed in retina. Cortex DHA increased in breast-fed (but not formula-fed) infants with age (r2 = 0.72, P < 0.01, n = 15), largely an effect of length of feeding (r2 = 0.62, P < 0.01, n = 35). There was an association between age at death and erythrocyte DHA with cortex DHA (r2 = 0.50, P < 0.01). In contrast, accretion of cortex arachidonic acid was dependent on age but not diet. The higher concentration of DHA in brains of breast-fed infants may explain the improved neurodevelopment reported in breast-fed compared with formula-fed infants.

Arachidonic Acid↗