Adult acute disseminated encephalomyelitis associated with poststreptococcal infection.

Acute disseminated encephalomyelitis (ADEM) is a monophasic illness that is thought to develop from antigenic mimicry with antibodies having cross-reactivity to host epitopes in the nervous system. The disorder typically follows an exanthematous or recent viral infection. In contrast, complications from bacterial poststreptococcal infections more commonly give rise to disorders in the pediatric population including Sydenham's chorea, pediatric autoimmune neuropsychiatric disorders, and ADEM. We present the novel case of documented streptococcal pharyngitis and elevated antideoxyribonuclease B (ADNB) titers in an adult giving rise to ADEM. Furthermore, the absence of basal ganglia abnormalities on MRI and the degree of leukocytosis in the CSF distinguish the adult form of ADEM from childhood ADEM and adult viral demyelinating diseases.

Reading impairment in the neuronal migration disorder of periventricular nodular heterotopia.

OBJECTIVE: To define the behavioral profile of periventricular nodular heterotopia (PNH), a malformation of cortical development that is associated with seizures but reportedly normal intelligence, and to correlate the results with anatomic and clinical features of this disorder. METHODS: Ten consecutive subjects with PNH, all with epilepsy and at least two periventricular nodules, were studied with structural MRI and neuropsychological testing. Behavioral results were statistically analyzed for correlation with other features of PNH. RESULTS: Eight of 10 subjects had deficits in reading skills despite normal intelligence. Processing speed and executive function were also impaired in some subjects. More marked reading difficulties were seen in subjects with more widely distributed heterotopia. There was no correlation between reading skills and epilepsy severity or antiepileptic medication use. CONCLUSION: The neuronal migration disorder of periventricular nodular heterotopia is associated with an impairment in reading skills despite the presence of normal intelligence.

Filamin A mutations cause periventricular heterotopia with Ehlers-Danlos syndrome.

OBJECTIVE: To define the clinical, radiologic, and genetic features of periventricular heterotopia (PH) with Ehlers-Danlos syndrome (EDS). METHODS: Exonic sequencing and single stranded conformational polymorphism (SSCP) analysis was performed on affected individuals. Linkage analysis using microsatellite markers on the X-chromosome was performed on a single pedigree. Western blotting evaluated for loss of filamin A (FLNA) protein and Southern blotting assessed for any potential chromosome rearrangement in this region. RESULTS: The authors report two familial cases and nine additional sporadic cases of the EDS-variant form of PH, which is characterized by nodular brain heterotopia, joint hypermobility, and development of aortic dilatation in early adulthood. MRI typically demonstrated bilateral nodular PH, indistinguishable from PH due to FLNA mutations. Exonic sequencing or SSCP analyses of FLNA revealed a 2762 delG single base pair deletion in one affected female. Another affected female harbored a C116 single point mutation, resulting in an A39G change. A third affected female had a 4147 delG single base pair deletion. One pedigree with no detectable exonic mutation demonstrated positive linkage to the FLNA locus Xq28, an affected individual in this family also had no detectable FLNA protein, but no chromosomal rearrangement was detected. CONCLUSION: These results suggest that the Ehlers-Danlos variant of periventricular heterotopia (PH), in part, represents an overlapping syndrome with X-linked dominant PH due to filamin A mutations.

Autosomal recessive form of periventricular heterotopia.

BACKGROUND: Familial periventricular heterotopia (PH) represents a disorder of neuronal migration resulting in multiple gray matter nodules along the lateral ventricular walls. Prior studies have shown that mutations in the filamin A (FLNA) gene can cause PH through an X-linked dominant inheritance pattern. OBJECTIVE: To classify cortical malformation syndromes associated with PH. METHODS: Analyses using microsatellite markers directed toward genomic regions of FLNA and to a highly homologous autosomal gene, FLNB, were performed on two pedigrees to evaluate for linkage with either filamin gene. RESULTS: Two consanguineous pedigrees with PH that suggest an autosomal recessive inheritance pattern are reported. MRI of the brain revealed periventricular nodules of cerebral gray matter intensity, typical for PH. Seizures or developmental delay appeared to be a common presenting feature. Microsatellite analysis suggested no linkage to FLNA or FLNB. CONCLUSIONS: Autosomal recessive PH is another syndromic migrational disorder, distinct from X-linked dominant PH. Further classification of these different syndromes will provide an approach for genetic evaluation.

Periventricular heterotopia associated with chromosome 5p anomalies.

Periventricular heterotopia (PH) is characterized by neuronal nodules along the lateral ventricles. Whereas mutations in X-linked FLNA cause such cortical malformations, the authors report two cases of PH localizing to chromosome 5p. Both subjects have complex partial seizures. MRI demonstrated bilateral nodular PH, with subcortical heterotopia or focal gliosis. FISH identified a duplication of 5p15.1 [46,XX,dup(5)(p15.1p15.1)] and a trisomy of 5p15.33 [46,XY,der(14)t(5;14)(p15.33;p11.2) mat]. These findings suggest a new PH locus along the telomeric end of chromosome 5p.

Mutations in the X-linked filamin 1 gene cause periventricular nodular heterotopia in males as well as in females.

Periventricular heterotopia (PH) is a human neuronal migration disorder in which many neurons destined for the cerebral cortex fail to migrate. Previous analysis showed heterozygous mutations in the X-linked gene filamin 1 (FLN1), but examined only the first six (of 48) coding exons of the gene and hence did not assess the incidence and functional consequences of FLN1 mutations. Here we perform single-strand conformation polymorphism (SSCP) analysis of FLN1 throughout its entire coding region in six PH pedigrees, 31 sporadic female PH patients and 24 sporadic male PH patients. We detected FLN1 mutations by SSCP in 83% of PH pedigrees and 19% of sporadic females with PH. Moreover, no PH females (0/7 tested) with atypical radiographic features showed FLN1 mutations, suggesting that other genes may cause atypical PH. Surprisingly, 2/24 males analyzed with PH (9%) also carried FLN1 mutations. Whereas FLN1 mutations in PH pedigrees caused severe predicted loss of FLN1 protein function, both male FLN1 mutations were consistent with partial loss of function of the protein. Moreover, sporadic female FLN1 mutations associated with PH appear to cause either severe or partial loss of function. Neither male could be shown to be mosaic for the FLN1 mutation in peripheral blood lymphocytes, suggesting that some neurons in the intact cortex of PH males may be mutant for FLN1 but migrate adequately. These results demonstrate the sensitivity and specificity of DNA testing for FLN1 mutations and have important functional implications for models of FLN1 protein function in neuronal migration.

Neural precursor differentiation following transplantation into neocortex is dependent on intrinsic developmental state and receptor competence.

Reconstruction of neocortical circuitry by transplantation of neural precursors, or by manipulation of endogenous precursors, may depend critically upon both local microenvironmental control signals and the intrinsic competence of populations of precursors to appropriately respond to external molecular controls. Dependence on the developmental state of donor or endogenous precursor cells in achieving appropriate differentiation, integration, and connectivity is not clearly understood. Recent studies have demonstrated the ability to generate expandable, often clonal neural precursors at various stages of development. Transplantation of a variety of these precursors suggests that precursor differentiation and integration within the central nervous system (CNS) may depend directly on the level of cellular maturation, with less differentiated, earlier stage precursors offering more flexible but less efficient integration and more differentiated, later stage precursors offering more efficient differentiation to specific phenotypes. To further investigate this hypothesis within neocortex, we used the relatively immature HiB5 multipotent neural precursor cell line derived from embryonic day 16 hippocampus, which is less mature than precursor types that have demonstrated neuronal differentiation in adult neocortex. HiB5 cells labeled fluorescently, radioactively, and genetically were transplanted into murine neocortex under three different conditions expected to offer varying levels of instructive and permissive microenvironmental signals: (1) the developing cortex in utero; (2) regions of adult neocortex undergoing targeted pyramidal neuronal degeneration in which developmental signals are upregulated and in which later stage precursors and immature neurons undergo directed pyramidal neuron differentiation; or (3) the intact adult neocortex. Differentiation and integration of transplanted cells were examined histologically and immunocytochemically by morphology and using neuronal- and glial-specific markers. We found that these precursors underwent differentiation toward cortical neuron phenotypes with characteristic morphologies when transplanted in utero, but failed to do so under either of the adult conditions. HiB5 precursors demonstrated highly immature characteristics in vitro, consistently expressing neuroepithelial but not glial or neuronal markers. Under all conditions, donor cells survived and migrated 1-2 mm from the injection track 2 to 4 weeks after transplantation. HiB5 neural precursors transplanted into the developing cortex of embryonic mice in utero migrated within the cortex, integrated well into the host parenchyma, and differentiated toward morphologically diverse, neuronal phenotypes. HiB5 cells transplanted into the intact cortex of adult mice survived, but did not show neuronal differentiation. In contrast to slightly later stage neural precursors and embryonic neurons used in previous transplantation studies, the HiB5 cells also failed to undergo neuronal differentiation after transplantation into regions undergoing induced apoptotic neuronal degeneration in adult cortex. These results suggested that these early hippocampal-derived precursors might not be fully competent to respond to later stage differentiation and/or survival signals important in neocortex and known to be upregulated in regions undergoing targeted neuronal apoptosis, including the TrkB neurotrophin receptor ligands BDNF and NT-4/5. We investigated this hypothesis and found that undifferentiated HiB5 cells lack catalytic trkB neurotrophin receptors at the mRNA and protein levels, while confirming that they express trkC receptors under the same conditions. Taken together, these findings support a progressive sequence of neural precursor differentiation and a spectrum of competence by precursors to respond to instructive microenvironmental signals. (ABSTRACT TRUNCATED)

Differentiation of transplanted neural precursors varies regionally in adults striatum.

In the current experiments, we address the emerging hypothesis that transplanted neural precursor cells can respond to local microenvironmental signals in the post-developmental brain and exhibit patterns of differentiation that depend critically on specific location within the brain. HiB5 precursor cells were transplanted into adult mouse cortex, corpus callosum, and multiple positions in striatum, and assessed for differentiation by morphology and immunocytochemistry. Our results indicate that the likelihood of both neuronal and glial differentiation of transplanted precursors depends on proximity to the medial striatum or subventricular zone of the adult host, supporting the concept that microenvironmental signals can critically affect the differentiation fate of neural precursors, and suggesting the potential to manipulate such signals in the adult brain.

Cortical interneurons upregulate neurotrophins in vivo in response to targeted apoptotic degeneration of neighboring pyramidal neurons.

Intercellular signals provided by growth and neurotrophic factors play a critical role during neurogenesis and as part of cellular repopulation strategies directed toward reconstruction of complex CNS circuitry. Local signals influence the differentiation of transplanted and endogenous neurons and neural precursors, but the cellular sources and control over expression of these molecules remain unclear. We have previously examined microenvironmental control in neocortex over neuron and neural precursor migration and differentiation following transplantation, using an approach of targeted apoptotic neuronal degeneration to specific neuronal populations in vivo. Prior results suggested the hypothesis that upregulated or reexpressed developmental signal molecules, produced by degenerating pyramidal neurons and/or by neighboring neurons or nonneuronal cells, may be responsible for observed events of directed migration, differentiation, and connectivity by transplanted immature neurons and precursors. To directly investigate this hypothesis, we analyzed the gene expression of candidate and control neurotrophins, growth factors, and receptors within regions of targeted neuronal cell death, first by quantitative Northern blot analysis and then by in situ hybridization combined with immunocytochemical analysis. The genes for BDNF, NT-4/5, trkB receptors, and to a lesser extent NT-3 were upregulated specifically within the regions of neocortex undergoing targeted neuronal degeneration and specifically during the period of ongoing pyramidal neuron apoptosis. Upregulation occurred during the same 3-week period as the previously investigated cellular events of directed migration, differentiation, and integration. No upregulation was seen in panels of control neurotrophins, growth factors, and receptors that are not as developmentally regulated in cortex or that are thought to have primary actions in other CNS regions. In situ hybridization and immunocytochemistry revealed that BDNF mRNA expression was upregulated specifically by local interneurons adjacent to degenerating pyramidal neurons. These findings suggest specific effects of targeted apoptosis on neurotrophin and other gene expression via mechanisms, including intercellular signaling between degenerating pyramidal neurons and surrounding interneurons. Further understanding of these and other controls over neocortical projection neuron differentiation may provide insight regarding normal neocortical development, intercellular signaling induced by apoptosis, and toward reconstruction and cellular repopulation of complex neocortical and other CNS circuitry.

Targeted neocortical cell death in adult mice guides migration and differentiation of transplanted embryonic neurons.

Local expression of cellular and molecular signals is required for normal neuronal migration and differentiation during neocortical development and during periods of plasticity in the adult brain. We have previously shown that neonatal and juvenile mice that induction of apoptotic degeneration in neocortical pyramidal neurons by targeted photolysis provides an altered environment that directs migration and differentiation of transplanted embryonic neurons. Here we employ the same paradigm in adult mice to test whether targeted photolysis induces the reexpression in the mature brain of developmental signals that control migration, differentiation and integration of embryonic neurons. We examined both the time course of migration and the morphologic and immunocytochemical differentiation of embryonic neurons transplanted into regions of targeted photolytic cell death. Pyramidal neurons in neocortical lamina II/III underwent photolytically induced apoptosis after retrograde incorporation of the photoactive chromophore chlorine e6 and transdural exposure to 674 nm near-infrared laser energy. Embryonic day 17 neocortical neurons were prelabeled with fluorescent nanospheres and the lipophilic dye PKH26, transplanted into regions of ongoing neuronal degeneration in adult mice, and examined histologically and immunocytochemically. Transplanted neurons began migration into regions of neuronal death within 3 d and differentiated into large pyramidal neurons similar to those degenerating. In contrast, neurons transplanted into intact cortex did not migrate, and they differentiate into small presumptive interneurons. Migration up to 430 microM in experimental mice was complete by 2 weeks; approximately 45% of the donor neurons migrated greater than 3 SDs beyond the mean for neurons transplanted into intact neocortex of age-matched adult hosts. Following migration, dendrites and axons of many donor neurons were properly oriented toward the pial surface and corpus callosum, indicating integration into the host parenchyma. Neurofilament and neuron-specific enolase staining further support appropriate differentiation and integration. These results indicate that signals guiding neuronal migration and differentiation in neocortex are reexpressed in adult mice well beyond the period of corticogenesis within regions of targeted photolytic cell death. Elucidating the molecular mechanisms underlying these events by comparison with adjacent unperturbed regions will contribute to efforts toward future therapeutic transplantation and control over endogenous plasticity.

Apoptotic mechanisms in targeted neuronal cell death by chromophore-activated photolysis.

Apoptosis influences early development and later refinement in adult tissues. Experiments in which embryonic neurons or multipotent neural precursor cells are transplanted into regions of neuronal degeneration following targeted photolytic cell death show similar regulation of neuronal migration and differentiation. In those experiments, transplanted cells sought to restore normal cytoarchitecture by preferential migration into neuron deficient regions, assumption of pyramidal morphology, and early process elongation. Control transplants into intact and kainic acid lesioned cortex failed to elicit similar responses. We investigated the possibility that mechanisms of neuronal death common to apoptosis and targeted photolysis could explain the similar developmental influences. We assessed the pathways of cellular injury and eventual cell death in neuroblastoma and PC12 cell cultures labeled with nanospheres carrying the chromophore NH4-chlorin e6 and subjected to photoactivation (1) pharmacologically by scavengers of singlet oxygen and inhibitors of lysosomal proteases, (2) histologically by electron, fluorescence, and light microscopy, and (3) biochemically with binding of cellular DNA by propridium iodide, 3'-OH DNA end terminal labeling, and gel electrophoresis. We found that nanospheres were incorporated into lysosomes, and exposure to light energy led to singlet oxygen (1O2) production and cell death within both neuroblastoma and PC-12 cell lines. Scavengers of 1O2 prevented cell toxicity, while inactivation of lysosomal proteases reduced cell death. Morphologically, degenerating cells revealed release of proteases from lysosomes and disruption of cytoskeletal proteins. Apoptotic characteristics including early loss of cell adhesion, plasma membrane blebbing, and nuclear condensation and convolution were observed. Biochemically, DNA fragmentation was present in cells stained with propridium iodide and observed by 3'-OH end terminal labeling and gel electrophoresis. Thus, cells targeted by photolytically generated 1O2 undergo a form of cell autolysis whose final common pathway is apoptotic. The slow, nonnecrotic process of targeted neuronal cell death in vivo may activate many of the same physiological cues activated by programmed cell death during normal development and during organizational refinement in the adult vertebrate nervous system. This may potentially explain the migration and differentiation of neocortical neurons and neural precursors transplanted into these regions of neuronal degeneration.

Iron acquisition and hemolysin production by Campylobacter jejuni.

Campylobacter jejuni strains were tested for their ability to acquire iron from various iron sources present in humans. Hemin, hemoglobin, hemin-hemopexin, and hemoglobin-haptoglobin stimulated the growth of C. jejuni strains in low-iron medium. Transferrin, lactoferrin, and ferritin were unable to provide iron to the strains tested. Derivatives of the naturally transformable C. jejuni strain 81-176 were isolated on the basis of their inability to use hemin as an iron source. These mutants were also unable to use hemoglobin, hemin-hemopexin, or hemoglobin-haptoglobin as iron sources. Some mutants lacked a 71,000-Da iron-regulated outer membrane protein, while others appeared to retain all of their outer membrane proteins. Growth curves and a recombination experiment that exploited natural transformation were used to further characterize the mutants. A hemolytic activity was shown to be produced by several C. jejuni strains, but it did not appear to be iron regulated.

Calcium-mediated neuronal degeneration following singlet oxygen production.

NONINVASIVE photolytic injury to targeted neuronal subpopulations in vivo causes unique, slowly progressive neuronal degeneration. To examine the mechanisms of degeneration toward development and transplantation studies, cytosolic calcium levels were measured in vitro from neocortical neurons after incorporation of photoactive nanospheres and laser-activated singlet oxygen production within lysosomes. Cytosolic calcium increased irreversibly, predominantly from extracellular sources through channel-mediated mechanisms and increased membrane porosity. Propidium iodide studies demonstrated gradual loss of membrane integrity over hours to days. The calcium channel blocker nimodipine, or calcium-free medium, partially protected neurons from calcium flux and cell death. Results suggest calcium-dependent and independent mechanisms of neuronal degeneration following singlet oxygen production.