Long term neuropsychological outcomes of a pediatric ETANTR brain tumor: A case study

Survivors of pediatric brain tumors are at high risk for long-term neuropsychological difficulties. In the current case study, we present longitudinal neuropsychological data spanning 10 years (from age 9 to 19 years) of a patient with a rare, very large, bifrontal, embryonal tumor with abundant neuropil and true rosettes (ETANTR), which is typically associated with poor survivorship and significant neurological impact. Results demonstrated that the patient had largely intact cognitive functioning with specific difficulties in executive functioning, fine motor skills, and adaptive functioning at her most recent neuropsychology 10-year follow-up. These results highlight outcomes for a patient with remarkable resiliency in the context of numerous risk factors (a very large tumor size, multi-modal treatment, and seizure history). Patient protective factors (a high level of cognitive reserve, family support, and appropriate comprehensive educational services) likely contributed to the patient's favorable neuropsychological outcome. The patient's age at brain tumor diagnosis (9 years) and associated treatment was at a critical period of development for emerging higher order cognitive functions which likely impacted acquisition of executive functioning skills and secondarily adaptive skill outcomes. Consequently, pediatric brain tumor survivors with ETANTR or other frontal tumors require targeted screening of executive functions and proactive interventions.

Neuropil-like islands are a possible pathogenetic link between glioblastoma and gangliocytoma/ganglioglioma in a case of synchronous bilateral brain tumors

Neuropil-like islands (NIs) are a histologic hallmark of glioneuronal tumors with neuropil-like islands (GTNIs), but GTNIs are presently not considered a homogeneous entity. The essence of GTNI is likely its glial component, and NIs are now considered aberrant neuronal differentiation or metaplasia. The case we report herein is a 41-year-old woman who was synchronously affected by two brain tumors: one was a glioblastoma (glioblastoma multiforme, GBM), of isocitrate dehydrogenase (IDH)-wild type, with NIs in the left parietal lobe, and the other was histologically a composite gangliocytoma (GC)/anaplastic ganglioglioma (GG) with NIs in the right medial temporal lobe. While both tumors were genetically wild type for IDH, histone H3, and v-raf murine sarcoma viral oncogene homolog B1 (BRAF), the former tumor, but not the latter, was mutated for telomerase reverse transcriptase promoter gene (TERT). A recent systematic study using DNA methylation profiling and next-generation sequencing showed that anaplastic GG separate into other WHO tumor types, including IDH-wild-type GBM. It suggested a diagnostic scheme where an anaplastic GG is likely an IDH-wild-type GBM if it is a BRAF wild type, IDH wild type, and TERT promoter mutant tumor. The likely scenario in this patient is that the GBM results from the progression of GC/anaplastic GG due to the superimposed TERT promoter mutation and the propagation of newly generated GBM cells in the contralateral hemisphere. A systematic analysis using DNA methylation profiling and next-generation sequencing was not available in this study, but the common presence of NIs histologically noted in the two tumors could support this scenario. Although a sufficient volume of molecular and genetic testing is sine qua non for the accurate understanding of brain tumors, the importance of histologic observation cannot be overemphasized.

Genomic Profiling of a Case of Glioneuronal Tumor with Neuropil-like Islands

Glioneuronal tumor with neuropil-like islands (GNTNI) is a very rare subtype of glioneuronal tumor. We present a case of a 62-year-old man with GNTNI. Two adjacent lesions in the left parietal lobe were removed by left parietal craniotomy. The histological findings were glial cell proliferation and scattered rosettes consisting of synaptophysin-positive and NeuN-positive cells, leading to the diagnosis of GNTNI. Target sequencing revealed a genetic alteration similar to glioblastoma, IDH-wild type, which suggested adjuvant therapies. There are few previous reports on the treatment of this disease, and the patient should be followed carefully.

Glioneuronal tumor with neuropil-like islands in the spinal cord: A case report and literature review

RATIONALE

Glioneuronal tumor with neuropil-like islands (GTNI) is a distinctive neoplasm located in the cerebrum. Moreover, spinal GTNI is extremely rare. Herein, we present a case of spinal GTNI and review the related literature.

PATIENT CONCERNS

A 38-year-old Chinese woman presented to our hospital with a 6-month history of neck pain and a 1-month history of dizziness.

DIAGNOSES

Magnetic resonance imaging revealed a large intramedullary mass spanning the length of the spinal cord from C1 to C4. Microscopic and immunohistochemical examinations of the tumor tissue revealed findings typical of GTNI.

INTERVENTIONS

The patient underwent C1 to C4 intraspinal gross tumor resection.

OUTCOMES

Follow-up results showed that the patient had no recurrence 6 months after tumor resection.

LESSONS

GTNI in the spinal cord is a highly rare neoplasm with poor prognosis. Therefore, clinicians and pathologists should differentiate GTNI from other benign glioneuronal tumors, and long-term follow-up of patients with spinal GTNI is necessary.

The effects of aging on neuropil structure in mouse somatosensory cortex-A 3D electron microscopy analysis of layer 1

This study has used dense reconstructions from serial EM images to compare the neuropil ultrastructure and connectivity of aged and adult mice. The analysis used models of axons, dendrites, and their synaptic connections, reconstructed from volumes of neuropil imaged in layer 1 of the somatosensory cortex. This shows the changes to neuropil structure that accompany a general loss of synapses in a well-defined brain region. The loss of excitatory synapses was balanced by an increase in their size such that the total amount of synaptic surface, per unit length of axon, and per unit volume of neuropil, stayed the same. There was also a greater reduction of inhibitory synapses than excitatory, particularly those found on dendritic spines, resulting in an increase in the excitatory/inhibitory balance. The close correlations, that exist in young and adult neurons, between spine volume, bouton volume, synaptic size, and docked vesicle numbers are all preserved during aging. These comparisons display features that indicate a reduced plasticity of cortical circuits, with fewer, more transient, connections, but nevertheless an enhancement of the remaining connectivity that compensates for a generalized synapse loss.

ATRX loss in glioneuronal tumors with neuropil-like islands indicates similarity to diffuse astrocytic tumors

Glioneuronal tumor with neuropil-like islands (GTNI) is a rare, recently described neoplasm, whose pathogenesis has not been studied extensively. The role of ATRX mutations, a class-defining alteration in diffuse astrocytic neoplasms, has not been assessed in GTNIs previously. We therefore aimed to assess the status of ATRX, along with IDH1, 1p/19q and p53, in cases of GTNI in order to evaluate the molecular profile of these tumors. All cases of GTNI diagnosed at our Institute were retrieved and clinicopathological features were reviewed. Immunohistochemistry for ATRX, IDH1 and p53 was performed. We identified four cases of GTNI, majority of which occurred in young adults. Loss of ATRX immunoexpression, a surrogate marker for ATRX mutation, was seen in all four cases. All cases were immunopositive for p53, while IDH1 positivity was seen in all three cases assessed. 1p/19q codeletion was absent in the three cases analyzed. These results indicate that the molecular pathogenesis of GTNIs similar to that of diffuse astrocytic tumors. Further, the loss of ATRX expression is seen in both the glial as well as neuronal components, indicating that both arise from the same tumor stem/progenitor cell and that the latter may be a metaplastic change. Thus, loss of ATRX immunoexpression, shown for the first time in these tumors, along with immunopositivity for p53 and IDH1, indicates that these tumors are molecular astrocytomas, and their clinical behaviour is likely to recapitulate that of ATRX-mutant and IDH-mutant diffuse astrocytomas of the same grade.

[Clinicopathologic features of embryonal tumor with multilayered rosettes and gene analysis on chromosome 19q13.42]

OBJECTIVE

To investigate the clinicopathologic features and 19q13.42 gene changes in embryonal tumors with multilayered rosettes (ETMR).

METHODS

Immunohistochemistry and fluorescence in situ hybridization (FISH) were performed in three ETMRs.

RESULTS

The average age of the patients were 34 months. Imaging revealed huge masses with inhomogeneous enhancement and two cases showed cystic lesions. Follow-up data showed 14 and 38 months survival in two children, the third had a recurrence 4 months after operation. Morphologically, the tumor was mainly composed of dense small primitive neuroepithelial cells in patchy or multilayer rosettes within a background of advanced neuronal differentiation, containing neurocytes, ganglion cells, and neuropil-like background. Immunohistochemical staining showed the neuronal marker, synaptophysin, was positive in differentiated areas. Nestin as a neural stem cell marker was immunoreactive in the primitive neuroepithelial cells including multilayered rosettes. Neurons with positive expression of NeuN were observed occasionally. Ki-67 index was up to 40%-80% in the undifferentiated cells and rosettes, but was only 1%-3% in the differentiated areas. CD99 was positive in perivascular papillary pattern areas in one case. 19q13.42 amplification was detected in more than 30% of tumor cells in all cases.

CONCLUSIONS

ETMR is a unique entity with distinctive clinical and pathological features. Chromosome 19q13.42 abnormality is valuable for confirming the diagnosis and for further treatment research.

Cell number and neuropil alterations in subregions of the anterior hippocampus in a female monkey model of depression

BACKGROUND

The anterior hippocampus is associated with emotional functioning and hippocampal volume is reduced in depression. More women are clinically depressed than men, yet the depressed female brain is little studied. We reported reduced anterior hippocampal volume in behaviorally depressed adult female cynomolgus macaques; the mechanisms contributing to that reduction are unknown. The present study represents the first systematic morphological investigation of the entire hippocampus in depressed female primates.

METHODS

Cellular determinants of hippocampal size were examined in subregions of anterior and posterior hippocampus in antidepressant-naïve, adult female monkeys characterized for behavioral depression and matched on variables that influence hippocampal size (n = 8 depressed, 8 nondepressed). Unbiased stereology was used to estimate neuronal and glial numbers, neuronal soma size, and regional and layer volumes.

RESULTS

Neuropil and cell layer volumes were reduced in cornu ammonis (CA)1 and dentate gyrus (DG) of the anterior but not the posterior hippocampus of depressed compared with nondepressed monkeys. Glial numbers were 30% lower in anterior CA1 and DG of depressed monkeys, with no differences observed in the posterior hippocampus. Granule neuron number tended toward a reduction in anterior DG; pyramidal neuron number was unchanged in any region. Size of pyramidal neurons and glial densities tended to be reduced throughout the whole hippocampus of depressed monkeys, whereas neuronal densities were unchanged.

CONCLUSIONS

The reduced size of the anterior hippocampus in depressed female monkeys appears to arise from alterations in numbers of glia and extent of neuropil, but not numbers of neurons, in CA1 and DG.

Electrophysiological correlations of morphological restructuring in experimental local ischemia of different severity in the rat sensorimotor cortex

Local cerebrovascular disorders were modeled by reversible photochemical clotting of hemispheric cortical vessels. Mild ischemia led to reversible edema in the surface layers of the cortex: cytotoxic edema of the neuropile, primarily of the distal dendrites. This status led to an increase in the lower delta rhythm frequency band power. After administration of systemic anesthetic, delta rhythm appeared sooner in the ischemic foci than in intact cortical areas. More severe ischemia led to the appearance of dark and pyknotic neurons and reduction of oscillation power in all EEG spectrum bands. Restructuring of primarily dendrites caused by local moderate ischemia of the surface cortical layers at the early stage of neurodegenerative processes stimulated the inhibitory recovery processes.

LIN28A immunoreactivity is a potent diagnostic marker of embryonal tumor with multilayered rosettes (ETMR)

Embryonal tumor with multilayered rosettes (ETMR, previously known as ETANTR) is a highly aggressive embryonal CNS tumor, which almost exclusively affects infants and is associated with a dismal prognosis. Accurate diagnosis is of critical clinical importance because of its poor response to current treatment protocols and its distinct biology. Amplification of the miRNA cluster at 19q13.42 has been identified previously as a genetic hallmark for ETMR, but an immunohistochemistry-based assay for clinical routine diagnostics [such as INI-1 for atypical teratoid rhabdoid tumor (AT/RT)] is still lacking. In this study, we screened for an ETMR-specific marker using a gene-expression profiling dataset of more than 1,400 brain tumors and identified LIN28A as a highly specific marker for ETMR. The encoded protein binds small RNA and has been implicated in stem cell pluripotency, metabolism and tumorigenesis. Using an LIN28A specific antibody, we carried out immunohistochemical analysis of LIN28A in more than 800 childhood brain-tumor samples and confirmed its high specificity for ETMR. Strong LIN28A immunoexpression was found in all 37 ETMR samples tested, whereas focal reactivity was only present in a small (6/50) proportion of AT/RT samples. All other pediatric brain tumors were completely LIN28A-negative. In summary, we established LIN28A immunohistochemistry as a highly sensitive and specific, rapid, inexpensive diagnostic tool for routine pathological verification of ETMR.

The glial regenerative response to central nervous system injury is enabled by pros-notch and pros-NFκB feedback

Organisms are structurally robust, as cells accommodate changes preserving structural integrity and function. The molecular mechanisms underlying structural robustness and plasticity are poorly understood, but can be investigated by probing how cells respond to injury. Injury to the CNS induces proliferation of enwrapping glia, leading to axonal re-enwrapment and partial functional recovery. This glial regenerative response is found across species, and may reflect a common underlying genetic mechanism. Here, we show that injury to the Drosophila larval CNS induces glial proliferation, and we uncover a gene network controlling this response. It consists of the mutual maintenance between the cell cycle inhibitor Prospero (Pros) and the cell cycle activators Notch and NFκB. Together they maintain glia in the brink of dividing, they enable glial proliferation following injury, and subsequently they exert negative feedback on cell division restoring cell cycle arrest. Pros also promotes glial differentiation, resolving vacuolization, enabling debris clearance and axonal enwrapment. Disruption of this gene network prevents repair and induces tumourigenesis. Using wound area measurements across genotypes and time-lapse recordings we show that when glial proliferation and glial differentiation are abolished, both the size of the glial wound and neuropile vacuolization increase. When glial proliferation and differentiation are enabled, glial wound size decreases and injury-induced apoptosis and vacuolization are prevented. The uncovered gene network promotes regeneration of the glial lesion and neuropile repair. In the unharmed animal, it is most likely a homeostatic mechanism for structural robustness. This gene network may be of relevance to mammalian glia to promote repair upon CNS injury or disease.

Hemispheric comparisons of neuron density in the planum temporale of schizophrenia and nonpsychiatric brains

Postmortem and in vivo studies of schizophrenia frequently reveal reduced cortical volume, but the underlying cellular abnormalities are incompletely defined. One influential hypothesis, especially investigated in Brodmann's area 9 of prefrontal cortex, is that the number of neurons is normal, and the volume change is caused by reduction of the surrounding neuropil. However, studies have differed on whether the cortex has the increased neuron density that is predicted by this hypothesis. In a recent study of bilateral planum temporale (PT), we reported smaller volume and width of the outer cortex (layers I-III), especially in the left hemisphere, among subjects with schizophrenia. In the present study, we measured neuron density and size in the same PT samples, and also in prefrontal area 9 of the same brains. In the PT, separate stereological measurements were made in layers II, IIIc, and VI, whereas area 9 was sampled in layer IIIb-c. In both cortical regions, there was no significant effect of schizophrenia on neuronal density or size. There was, nevertheless, a trend-level right>left hemispheric asymmetry of neuron density in the PT, which may partially explain the previously reported left>right asymmetry of cortical width. In schizophrenia, our findings suggest that closer packing of neurons may not always explain reduced cortical volume, and subtly decreased neuron number may be a contributing factor.

A 3-year- old girl with altered mental status, gait difficulty, and vomiting

We report a case of a 3-year-old girl with a 9-month history of focal neurologic finding and signs of increased intracranial pressure. Radiological imaging studies showed a minimally heterogeneous enhancing large tumor involving left parietal region and partly filling the left lateral ventricle. Microscopically, the tumor contained prominent small true rosettes set into areas of fibrillar neuropil-like matrix. Foci of cellular tumor with extensive apoptosis were present. The neuropil-like areas and true rosettes were positive for synaptophysin immunostain. The tumor was negative for GFAP and neurofilament protein immunostains. MIB-1 proliferation index was high focally approaching 80%.

Use of laser microdissection in the investigation of facial motoneuron and neuropil molecular phenotypes after peripheral axotomy

The mechanism underlying axotomy-induced motoneuron loss is not fully understood, but appears to involve molecular changes within the injured motoneuron and the surrounding local microenvironment (neuropil). The mouse facial nucleus consists of six subnuclei which respond differentially to facial nerve transection at the stylomastoid foramen. The ventromedial (VM) subnucleus maintains virtually full facial motoneuron (FMN) survival following axotomy, whereas the ventrolateral (VL) subnucleus results in significant FMN loss with the same nerve injury. We hypothesized that distinct molecular phenotypes of FMN existed within the two subregions, one responsible for maintaining cell survival and the other promoting cell death. In this study, we used laser microdissection to isolate VM and VL facial subnuclear regions for molecular characterization. We discovered that, regardless of neuronal fate after injury, FMN in either subnuclear region respond vigorously to injury with a characteristic "regenerative" profile and additionally, the surviving VL FMN appear to compensate for the significant FMN loss. In contrast, significant differences in the expression of pro-inflammatory cytokine mRNA in the surrounding neuropil response were found between the two subnuclear regions of the facial nucleus that support a causative role for glial and/or immune-derived molecules in directing the contrasting responses of the FMN to axonal transection.

Neuroprotective effect of erythropoietin in amyotrophic lateral sclerosis (ALS) model in vitro. Ultrastructural study

Erythropoietin (EPO) is a chemokine hormone that is widely distributed throughout the body including nervous system. For last years its role as cytokine involved in many physiological processes out of the bone marrow has been suggested. Moreover, it plays a very important role in CNS as potential neuroprotective agent. There is much evidence that EPO protects neuronal cells in vitro and in vivo models of brain injury, independently of its erythropoietic action. The aim of this study was to determine the potential neuroprotective effects of erythropoietin on the glutamate-mediated injury of motor neurons (MNs) in vitro. The study was performed on organotypic cultures of the rat lumbar spinal cord subjected to glutamate uptake blocker, DL-threo-beta-hydroxyaspartate (THA) and pretreated with EPO. Ultrastructural study evidenced that the spinal cord cultures pretreated with EPO exhibited less severe neuronal injury. The cultures exposed to EPO + THA showed inhibition of early MNs degeneration, including various mode of degenerative changes caused by THA, whereas in the later period the typical postsynaptic necrotic changes of neuronal cells occurred. However, the ultrastructural characteristics of apoptotic MNs changes were not observed during the whole period of observation. The results of this study indicate that, in the model of chronic glutamate excitotoxicity, EPO exhibits the neuroprotective ability mainly through prevention of apoptotic neuronal changes.

Ultrastructure of hippocampal field CA1 in rats after status epilepticus induced by systemic administration of kainic acid

The ultrastructure of hippocampal field CA1 in rats was studied 14 days after status epilepticus induced by administration of kainic acid. Structural changes were seen in 40% of cells, predominantly interneurons, which showed both reversible changes (mitochondria with an electron-dense matrix or small numbers of short cristae, moderate dilation of rough endoplasmic reticulum (RER) cisterns, and small numbers of ribosomes) and more significant abnormalities: swollen mitochondria with very small numbers of cristae, which were partially degraded, some with damaged mitochondrial membranes, along with pathologically damaged RER components and focal or peripheral chromatolysis. Chromatolyzed areas sometimes contained membrane-like includes and vacuoles. In addition, the neuropil contained occasional large osmiophilic formations surrounded by astrocyte processes with accumulations of glycogen or gliofibrils. Synaptoarchitectonics were also altered. Asymmetrical synapses were often seen on small dendrites and spines, with highly osmiophilic postsynaptic zones, their synaptic terminals containing numerous synaptic vesicles and large vesicles with electron-dense cores. Some presynaptic endings showed clear signs of classical dark-type degeneration. As the nucleus remained intact in all types of altered neurons, it appears that most cells underwent pathological changes of the necrotic type.

Long lasting pure freezing of gait preceding progressive supranuclear palsy: a clinicopathological study

Primary progressive freezing of gait (PPFG) is the term used to designate an uncommon condition featuring freezing of gait with frequent falls, without bradykinesia, rigidity or tremor, and unresponsive to levodopa. There are very few pathological reports of patients with PPFG in the literature. We report on 2 patients (one with pathological confirmation) diagnosed initially as PPFG and evolving into clinically defined progressive supranuclear palsy (PSP) more than 10 years after onset of symptoms. These 2 cases suggest that PPFG can represent the initial manifestation of a neurodegenerative disease, such as PSP, rather than a differentiated nosological entity.

Diffuse glioma growth: a guerilla war

In contrast to almost all other brain tumors, diffuse gliomas infiltrate extensively in the neuropil. This growth pattern is a major factor in therapeutic failure. Diffuse infiltrative glioma cells show some similarities with guerilla warriors. Histopathologically, the tumor cells tend to invade individually or in small groups in between the dense network of neuronal and glial cell processes. Meanwhile, in large areas of diffuse gliomas the tumor cells abuse pre-existent "supply lines" for oxygen and nutrients rather than constructing their own. Radiological visualization of the invasive front of diffuse gliomas is difficult. Although the knowledge about migration of (tumor)cells is rapidly increasing, the exact molecular mechanisms underlying infiltration of glioma cells in the neuropil have not yet been elucidated. As the efficacy of conventional methods to fight diffuse infiltrative glioma cells is limited, a more targeted ("search & destroy") tactic may be needed for these tumors. Hopefully, the study of original human glioma tissue and of genotypically and phenotypically relevant glioma models will soon provide information about the Achilles heel of diffuse infiltrative glioma cells that can be used for more effective therapeutic strategies.

Immunohistochemistry for PrPSc in natural scrapie reveals patterns which are associated with the PrP genotype

Immunohistochemistry for PrPSc is used widely in scrapie diagnosis. In natural scrapie cases the use of immunohistochemistry (IHC) has revealed the existence of up to 12 different morphological types of immunostained deposits. The significance of this pattern variability in relation to genotype has not been studied extensively in natural disease. In this study we recorded in detail PrPSc patterns at the obex level of the medulla oblongata from 163 animals derived from 55 flocks which presented through passive surveillance in the UK and Italy. A strong association was seen between PrPSc patterns and PrP genotype, particularly in relation to codon 136. In a blind assessment of this association we were able to predict, with over 80% accuracy, the genotype of 151 scrapie cases which were presented through passive surveillance from 13 farms. The genotype of these cases was ARQ/ARQ or VRQ/VRQ. The association of PrPsc patterns with genotype was generally stronger in those farms where all the affected animals belonged to a single genotype compared with farms where both genotypes were identified, with the exception of one farm in which the genotype of all affected sheep was ARQ/ARQ and the PrPSc patterns were of the VRQ/VRQ type. Our observations support the hypothesis that the observed association between specific IHC patterns and genotypes may in fact be strain driven but in natural disease individual scrapie strains may demonstrate a genotypic tropism.

Glioneuronal Tumor With Neuropil-like Islands (GTNI): A Report of 8 Cases With Chromosome 1p/19q Deletion Analysis

Glioneuronal tumor with neuropil-like islands (GTNI) is a rare neoplasm harboring circumscribed loci of neuronal differentiation and diffusely infiltrating astroglial and oligodendrocytelike components. We report 8 previously unpublished examples of GTNI, specifically studied for chromosome 1p and 19q allelic losses. All tumors showed characteristic histologic features and immunoprofile. One primary tumor displayed frankly malignant histology with frequent mitoses, microvascular proliferation, and necrosis. This tumor progressed within months of the initial resection. Three other tumors (2 low-grade and 1 showing only focal microvascular proliferation) recurred at 2 years, 3 years, and 1 year, respectively. All cases were evaluated for 1p/19q allelic losses by standard polymerase chain reaction-based loss of heterozygosity assays. No evidence of 1p/19q losses was found in 7 of 8 tumors. One tumor demonstrated small interstitial deletions at 1p36 (at D1S1612 and D1S513, but not at D1S548 or D1S1592) and a small interstitial deletion at 19q13 (at D19S219 and D19S412, but not at PLA2G4C). The lack of large, whole-arm 1p/19q losses (such as those found in oligodendroglial tumors), aberrant p53 expression, and the predominance of astroglial components may indicate a biologic relationship of the GTNI to diffuse astrocytoma. Although GTNI shares some morphologic features with recently reported cases of oligodendroglioma with neurocytic differentiation, the 2 tumors appear different at the molecular genetic level.

Mechanical heterogeneity of the rat hippocampus measured by atomic force microscope indentation

Knowledge of brain tissue mechanical properties may be critical for formulating hypotheses about traumatic brain injury (TBI) mechanisms and for accurate TBI simulations. To determine the local mechanical properties of anatomical subregions within the rat hippocampus, the atomic force microscope (AFM) was adapted for use on living brain tissue. The AFM provided advantages over alternative methods for measuring local mechanical properties of brain because of its high spatial resolution, high sensitivity, and ability to measure live samples under physiologic conditions. From AFM indentations, a mean pointwise or depth-dependent apparent elastic modulus, E, was determined for the following hippocampal subregions: CA1 pyramidal cell layer (CA1P) and stratum radiatum (CA1SR), CA3 pyramidal cell layer (CA3P) and stratum radiatum (CA3SR), and the dentate gyrus (DG). For all regions, E was indentation-depth-dependent, reflecting the nonlinearity of brain tissue. At an indentation depth of 3microm, E was 234 +/- 152 Pa for CA3P, 308 +/- 184 Pa for CA3SR, 137 +/- 97 Pa for CA1P, 169 +/- 52 Pa for CA1SR, and 201 +/- 133 Pa for DG (mean +/- SD). Our results demonstrate for the first time that the hippocampus is mechanically heterogeneous. Based on our findings, we discuss hypotheses accounting for experimentally observed patterns of hippocampal cell death, which can be tested with biofidelic finite element models of TBI.

Neuronal intranuclear and neuropil inclusions for pathological assessment of Huntington's disease

To evaluate the usefulness of neuronal intranuclear inclusions and neuropil inclusions for the pathological assessment of Huntington's disease (HD), their presence in neocortex was assessed by ubiquitin and N-terminal huntingtin immunohistochemistry in a consecutive series of 195 autopsy brains of individuals with a positive or tentative clinical diagnosis of, or at risk for, HD. The findings were correlated with striatal pathology (n = 190), CAG repeat length (n = 85) and original pathological diagnosis (n = 186). The antibodies detected both these inclusions in 181 patients with HD pathology > or = Vonsattel et al's grade I, five patients lacking striatal tissue for review, and two at-risk individuals with grade 0 and grade I HD pathology, respectively. One patient with HD-like pathology and two patients and four at-risk individuals without HD pathology lacked HD inclusions. In the genetically analyzed cases, the inclusions were exclusively and consistently observed in association with repeat expansion [(CAG)(n) > or = 39, n = 81]. Thirteen inclusion-positive cases, including the grade 0 at-risk individual, had a false negative original pathological diagnosis of HD and four had an unjustly questionable diagnosis. A false positive diagnosis was made in the inclusion-negative case with HD-like pathology. These results indicate that immunohistochemical analysis for HD inclusions facilitates the pathological evaluation of HD and enhances its accuracy.

Individual dopaminergic neurons show raised iron levels in Parkinson disease

OBJECTIVE

Evidence suggests that abnormal iron metabolism is associated with Parkinson disease (PD), with raised iron levels found in pathologically affected areas in PD. It is unknown if this elevated iron is actually associated with neurons or reactive glia, and we therefore addressed this issue by determining if raised iron was present in single dopaminergic neurons.

METHODS

We used unfixed frozen sections from postmortem tissue of PD patients and elderly normal individuals to avoid metal contamination and translocation. Levels of iron and other elements were measured using sensitive and specific wavelength dispersive electron probe x-ray microanalysis coupled with cathodoluminescence spectroscopy in individual substantia nigra dopaminergic neurons.

RESULTS

We identified raised intraneuronal iron in single defined substantia nigra neurons in PD (mean neuronal iron 2,838 vs 1,611, p < 0.0001) but not in other movement disorders such as Huntington disease. These findings were unrelated to the density of remaining neurons.

CONCLUSIONS

Primary changes in neuronal iron could lead to neurodegeneration in Parkinson disease.

Altered distribution of KCC2 in cortical dysplasia in patients with intractable epilepsy

PURPOSE

To examine the distribution of KCC2, a neuron-specific K(+)-Cl(-) cotransporter, in human cortical dysplasia (CD).

METHODS

The immunohistochemical expression of KCC2 was investigated in 18 CD specimens obtained during epilepsy surgery. The histopathologic diagnoses were focal CD (FCD) type I (eight cases), FCD type II (six cases), and hemimegalencephaly (HME; four cases). Tissue sections were immunostained for KCC2 and compared with control sections.

RESULTS

In the mature nondysplastic cortex, all the layers showed diffuse neuropil staining for KCC2. The somata were stained much less, although subcortical ectopic neurons displayed dense staining in the cytosol (intrasomatic staining). In FCD type I, the cortex showed neuropil staining for KCC2 with less-stained somata. Aberrant giant pyramidal neurons were also less stained at the soma, whereas immature neurons showed intrasomatic staining. Increased numbers of ectopic neurons with intrasomatic staining were noted in the subcortical white matter. In FCD type II, dysmorphic neurons displayed dense intrasomatic staining with reduced staining of the neighboring neuropils. Balloon cells did not stain for KCC2. Dysmorphic neurons in HME also showed intrasomatic staining.

CONCLUSIONS

Neurons in CD tissues expressed KCC2. However, the subcellular distribution of KCC2 was altered, which might have affected the ionic homeostasis of Cl(-) and K(+) involved in epileptic activity within CD tissues.

Embryonal tumor with abundant neuropil and true rosettes (ETANTR): report of a case with prominent neurocytic differentiation

We report a case of a 2 year-old boy who initially presented with macrocephaly and severe global developmental delay. Imaging revealed a large left temporo-parietal mass that was lobulated, calcified, focally enhancing and partially cystic. A second surgery was required for tumor recurrence approximately one year later, and tissue from that resection proved to be diagnostic for an embryonal tumor with abundant neuropil and true rosettes (ETANTR). Only 12 cases of this rare pediatric embryonal tumor have been previously documented, and as of 2000, the WHO has not recognized ETANTR as a distinct entity (Kleihues P, Cavenee WK (2000) International agency for research on cancer: pathology and genetics of tumors of the nervous system. IARC Press, Lyon). As opposed to prior cases, our patient's tumor exhibited extensive neurocytic elements. Two recently described cases were examined via fluorescence in situ hybridization (FISH), with one demonstrating isochromosome 17q (i17q) and the second exhibiting polysomies of chromosomes 2, 8, 17 and 22 (Fuller C, Fouladi M, Gajjar A, Dalton J, Sanford RA, Helton KJ (2000) Am J Clin Pathol 126: 277-283). Via FISH analysis, we found normal dosages of chromosomes 2, 8 and 17. Our case expands the histopathologic spectrum of ETANTR, illustrating marked neuronal differentiation towards neurocytes. The lack of common PNET-associated FISH abnormalities in this case adds to the limited cytogenetic genetic data on this rare pediatric embryonal neoplasm.

Neuroinhibitory molecules in Alzheimer's disease

Aberrant neurite growth is one of the neuropathological signatures of the Alzheimer's disease brain, both around amyloid plaques and in the cortical neuropil. Disruption of neuroinhibitory or repulsive growth and guidance signals, as well as of neurotrophic or permissive signals, may contribute to this dystrophic growth. Hence, therapeutic efforts directed exclusively at restoring neurotrophic activity are unlikely to meet with success. The molecular species responsible for neuroinhibitory effects in the Alzheimer's disease brain are beginning to be elucidated.

Differential morphology and composition of inclusions in the R6/2 mouse and PC12 cell models of Huntington’s disease

The histological hallmark feature of Huntington's disease (HD) and other polyglutamine repeat diseases is the presence of intracellular inclusions. Much work has been devoted to trying to determine the relationship between inclusion formation and neuronal injury. However, little attention has been paid to the variability and characteristics of inclusions themselves. Here, we characterize the morphological and biochemical composition of inclusions in both a transgenic mouse model (R6/2 line) and an inducible cell culture model of HD (iPC12Q74). We identified several morphologically distinct kinds of inclusions in different locations (nuclei, cytoplasm and cellular processes). Ubiquitin colocalized completely with all of these inclusions in both the iPC12Q72 and R6/2 models. In the inclusions in iPC12Q74 cells, the 20S and 11S proteasome subunits colocalized variably, and the 19S subunit did not colocalize at all. In inclusions in R6/2 mouse neurons, the 20S subunit colocalized completely, but neither the 11S nor the 19S subunits colocalized at all. While the role of inclusions in the pathogenesis of HD continues to be debated, we suggest that the content and structure of inclusions vary considerably, not only from cell to cell but even within individual cells. Their role in the pathogenesis of HD is likely to depend on their location as well as their composition.

Fortschritte in der neurobiologischen Erforschung der Schizophrenie

Causal treatment options for schizophrenia are lacking due to our restricted knowledge of its etiology and pathogenesis. However, recently three postulated disposition genes for schizophrenia have been increasingly better confirmed: dysbindin, neuregulin-1, and G(72)/DAOA genes. These genes code proteins involved in processes ranging from brain development to the maintenance of glutamatergic transmission in the mature brain. Current interpretation of neuroanatomical findings points at reminiscences of disturbed brain development and a loss of nonneuronal elements, the so-called neuropil, as a correlate of brain atrophy. This reduction in neuropil is mainly caused by synaptic elements. Biochemical findings supporting this show that besides the dopaminergic and serotonergic system, glutamatergic transmission is also disturbed in schizophrenia. All these findings fit very well with the presumed functions of the disposition genes. Hypothesis-free approaches in structural brain imaging and the combination of functional imaging with relevant gene variants open new avenues for using markers from brain imaging to improve the diagnosis of schizophrenia and judge the response to neuroleptic treatment. Despite the enormous increase in knowledge for example in genetic research, the risk variants known until now provide no contribution to early diagnosis of schizophrenia. Furthermore, pharmacogenetics is currently unable to give a clear answer as to whether a single patient is responding to treatment or not.

Unchanged scrapie pathology in brain tissue of tyrosine kinase Fyn-deficient mice

Fyn is a 59-kDa member of the Src family of tyrosine kinases synthesized on cytosolic polysomes and then targeted to the plasma membrane where it clusters in caveolae-like membrane microdomains. The cellular isoform of the prion protein (PrP) has also been identified to be a caveolar constituent and to participate in signal transduction events concerning cell survival and differentiation via recruitment of Fyn. We studied the scrapie infection of mice deficient for Fyn (Fyn(-/-)) to clarify the role of Fyn in an in vivo model of transmissible spongiforme encephalopathies. Fyn(-/-) mice died on average 9 days earlier than wild-type control mice, but no differences were seen regarding activation of astrocytes, vacuolization of the neuropil, and accumulation of misfolded prion protein. The experimental model suggests that a deficiency for Fyn is detrimental in prion diseases, although it has no major effect on the clinical course of an experimental prion infection of the CNS.

An ultrastructural analysis of cellular death in the CA1 field in the rat hippocampus after transient forebrain ischemia followed by 2, 4 and 10 days of reperfusion

An ultrastructural study was performed to investigate the type of cellular death that occurs in hippocampal CA1 field pyramidal neurons after 10 and 20 min of transient cerebral ischemia in the male adult Wistar rats, followed by 2, 4 and 10 days of reperfusion. The four-vessel occlusion method was used to induce ischemic insult for either 10 or 20 min, following which the animals were submitted to either 2, 4 or 10 days of reperfusion. The animals were then anaesthetised, and their brains removed, dehydrated, embedded, sectioned and examined under a transmission electron microscope. After ischemic insult, neurons from the CA1 field presented alterations, corresponding to the initial, intermediate and final stages of the degenerative process. The only difference observed between the 10 and 20 min ischemic groups was the degree of damage; the reaction was stronger in 20 min groups than in the 10 min groups. While neurons were found in the different stages of oncotic necrosis in all groups, differences were found between the groups in relation to prevalent stages. In both ischemic groups, after 2 days of reperfusion, the initial stage of oncotic necrosis was prevalent and large numbers of neurons appeared normal. In both groups, after 4 days of reperfusion, most of the neurons showed more advanced alterations, typical of an intermediate stage. In both groups, after 10 days of reperfusion, alterations corresponding to the intermediate and final stages of oncotic necrosis were also predominant. However, few intact neurons were identified and the neuropile appeared more organised, with numerous glial cells. In summary, the pyramidal neurons of the CA1 field displayed selective vulnerability and exhibited a morphological death pattern corresponding exclusively to an oncotic necrotic pathway.

Contraindications of VEGF-based therapeutic angiogenesis: Effects on macrophage density and histology of normal and ischemic brains

Therapeutic angiogenesis by vascular endothelial growth factor (VEGF) is advocated as a promising treatment strategy for brain ischemic stroke. However, data in the literature demonstrating the benefit of therapeutic angiogenesis are contradictory. In this paper, we describe the effects of non-angiogenic and angiogenic doses of VEGF165 on macrophage density and histology of normal and ischemic brains of adult rats. VEGF165 was administered intra-arterially for 7 days following temporary occlusion of the middle cerebral artery. In contrast to ischemic brains treated with non-angiogenic doses of VEGF165 which showed preserved neuropil and reduced numbers of macrophages, ischemic brains treated by an angiogenic dose showed phagocytized neuropil and high macrophage density. Though neither non-angiogenic nor angiogenic doses caused macrophage infiltration in normal brains, damage of the brain matrix occurred with the angiogenic dose. These results suggest an angiogenic dose of VEGF165 injures the nervous tissue rather than promote recovery. Angiogenesis by VEGF monotherapy for ischemic stroke should be viewed with caution, or avoided. Since our data show intravascular administration of VEGF165 does not cause macrophage inflammation, in contrast to reports in the literature whereby VEGF165 was applied directly to the brain, our findings also indicate the relationships between VEGF, angiogenesis, and macrophage inflammation are governed by the route VEGF is administered to the brain.

Embryonal tumor with abundant neuropil and true rosettes. A new entity or only variations of a parent neoplasms (PNETs)? This is the dilemma

A rare embryonal brain tumor has been diagnosed in a 4-year-old boy. The mass, located at the pons and mesencephalon, has been histologically classified as an embryonal tumor containing abundant neuropil and true rosettes. After surgical complete removal of the neoplasia, the child received intensive combined chemotherapy and radiotherapy. He is alive and free of disease at 34 months from surgery. Difficulties in histological definition, possible suggestions for treatment proposals are discussed.

Hippocampal sclerosis dementia with tauopathy

In some elderly individuals with dementia, hippocampal sclerosis (HS) is the only remarkable autopsy finding. The cause of HS in this setting is puzzling, since known causes of HS such as seizures or global hypoxic-ischemic episodes are rarely present. We here describe a series of HS cases that have a widespread neuronal and/or glial tauopathy. Of 14 consecutive cases of HS, 12 had been clinically diagnosed with dementia and/or Alzheimer's disease (AD) while 2 were non-demented; 7 cases had also been clinically diagnosed with parkinsonism. In addition to HS, 6 cases also met pathologic diagnostic criteria for AD. Gallyas silver staining and immunohistochemistry with the AT8 antibody revealed a glial and/or neuronal tauopathy in 12 of 14 cases, with frequent positive neurons and/or glial cells in the neocortex, basal ganglia, thalamus and/or limbic regions; in addition, 8 of the 14 cases had argyrophilic grains. Screening for known tau mutations was negative in all cases. Western blots of sarkosyl-insoluble tau protein showed a mixture of 3- and 4-repeat forms. The results suggest that most cases of HS dementia are sporadic multisystem tauopathies; we suggest the term "hippocampal sclerosis dementia with tauopathy" (HSDT) for these.

Argyrophilic grain disease: neuropathology, frequency in a dementia brain bank and lack of relationship with apolipoprotein E

Argyrophilic grain disease (AGD) is a recently recognized disorder whose relationship to dementia as well as genetic or biochemical features remain incompletely characterized in part due to diagnostic difficulties engendered by concomitant pathologies. In the present study, we reviewed a consecutive series of over 300 brains referred for evaluation of dementia for presence of argyrophilic grains (AGs). AGs were found in the hippocampal region and amygdala, and were accompanied by coiled bodies in the underlying white matter and ballooned neurons in the limbic lobe. Ballooned neurons were also found in the limbic lobe in a number of cases of advanced Alzheimer's disease (AD) that did not have AGs, supporting the lack of diagnostic significance of ballooned neurons confined to limbic lobe. The frequency of AGD in this series of dementia brains was 4.9% and was similar to the frequency in other autopsy series of nondemented cases, supporting the notion that there is no obligatory relationship between AGD and dementia. In the present series, ApoE epsilon4 allele frequency of AGD was dependent on concurrent AD, with AGD cases lacking AD similar to controls and cases with concurrent AD similar to AD. This suggests that AGD is an independent disease process from AD.

Apolipoprotein D is a component of compact but not diffuse amyloid-beta plaques in Alzheimer's disease temporal cortex

Apolipoprotein D (apoD) is elevated in Alzheimer's disease (AD) cortex, localizing to cells, blood vessels, and neuropil deposits (plaques). The role of apoD in AD pathology and the extent of its co-distribution with diffuse (amorphous) and compact (dense fibrillar) amyloid-beta (Abeta) plaques are currently unclear. To address this issue, we combined apoD and Abeta immunohistochemistry with ThioS/X-34 staining of the beta-pleated sheet protein conformation in temporal cortex from 36 AD patients and 12 non-demented controls. ApoD-immunoreactive, Abeta-immunoreactive, and ThioS/X-34-stained plaques were detected exclusively in AD tissue. Dual-immunolabeling showed that 63% of Abeta plaques co-localized apoD. All apoD plaques contained Abeta protein and ThioS/X-34 fluorescence. Compared to controls, AD cases showed elevated vascular and intracellular apoD immunostaining which localized primarily to cells clustered within plaques and around large blood vessels. ApoD-immunoreactive cells within plaques morphologically matched MHC-II- and CD-68-immunoreactive microglia, and did not contain the astrocytic marker GFAP, which labeled a subset of apoD-immunoreactive cells surrounding plaques. These data suggest that neuropil deposits of apoD localize only to a subset of Abeta plaques, which contain compact aggregates of fibrillar Abeta. Elevated apoD in AD brain may influence Abeta aggregation, or facilitate phagocytosis and transport of Abeta fibrils from plaques to cerebral vasculature.

Synaptic differences in the patch matrix compartments of subjects with schizophrenia: a postmortem ultrastructural study of the striatum

The striatum processes motor, cognitive, and limbic circuitry. Striatal patch and matrix compartments are organized differently in many aspects including connectivity. Abnormalities in either compartment could have different functional consequences. The present study compares the synaptic organization in the patches and matrix in subjects with schizophrenia (SZ, n = 14) versus normal controls (NC, n = 8). Postmortem striatal tissue was processed for calbindin immunocytochemistry to identify the patch versus matrix compartments, prepared for electron microscopy, and analyzed using stereology. Several synaptic changes were observed in the SZ subjects vs. NCs including a higher density of cortical-type synapses in the putamen patch (44% higher) and in the caudate matrix (36% higher) in SZ cases on typical antipsychotic drugs. These changes appeared to be normalized rather than caused by treatment. The abnormal connectivity may represent a failure of normal synaptic pruning and may play a role in limbic or cognitive dysfunction in schizophrenia.

Synapse loss from chronically elevated glucocorticoids: Relationship to neuropil volume and cell number in hippocampal area CA3

Individuals with clinical disorders associated with elevated plasma glucocorticoids, such as major depressive disorder and Cushing's syndrome, are reported to have smaller hippocampal volume. To understand how the hippocampus responds at the cellular and subcellular levels to glucocorticoids and how such changes are related to volume measures, we have undertaken a comprehensive study of glucocorticoid effects on hippocampal CA3 volume and identified elements in the neuropil including astrocytic volume and cell and synapse number and size. Male Sprague-Dawley rats were injected with corticosterone (40 mg/kg), the primary glucocorticoid in rodents, or vehicle for 60 days. The CA3 was further subdivided so that the two-thirds of CA3 (nearest the dentate gyrus) previously shown to be vulnerable to corticosterone could be analyzed as two separate subfields. Corticosterone had no effect on neuropil volume or glial volume in the proximal subfield but caused a strong tendency for astrocytic processes to make up a larger proportion of the tissue and for volume of tissue made of constituents other than glial cells (primarily neuronal processes) to be smaller in the middle subfield. Within the neuropil, there were no cellular or subcellular profiles that indicated degeneration, suggesting that corticosterone does not cause prolonged damage. Corticosterone did not reduce cell number or cell or nonperforated synapse size but did cause a pronounced loss of synapses. This loss occurred in both subfields and, therefore, was independent of volume loss. Together, the findings suggest that volume measures can underestimate corticosterone effects on neural structure.

Temporal profile of ultrastructural changes in cortical neurons after a compression lesion

We studied the occurrence of apoptosis and secondary delayed cell death at various time points in the penumbra zone, which is the target for therapeutic intervention after stroke. A compression lesion was induced in the right sensory motor cortex of rat brains. At 0.5, 1, 3, 6, 12, 24, 48 and 72 h after lesioning, motor functions were evaluated by behavioral tests, and cortical layers IV and V were examined by electron microscopy. Behavioral recovery was observed at 48 h after lesioning. At 0.5-1 h in the lesioned area, the neuropil was expanded and contained affected cells. Apoptotic cells were found between 0.5-72 h, and at 12 h, 47.3 % of the total cell number was apoptotic cells. On the contralateral side, cells showed an enlarged endoplasmic reticulum at 3 h, indicating secondary delayed cell death. Our results show that a compression lesion is a useful model for studying ultrastructural changes in injured cells. The lesion results in the penumbra zone with apoptotic cell death between 0.5-72 h. As secondary delayed cell death occurred on the contralateral side at three hours after lesioning might be the time period during which injured, but still viable, neurons can be targets for acute treatment.

Transient ischemia-induced changes of neurofilament 200 kDa immunoreactivity and protein content in the main olfactory bulb in gerbils

This study was carried out to investigate alterations of neurofilament 200 kDa (NF-200) and its polyphosphorylation form (RT97) immunoreactivity and protein content in the main olfactory bulb (MOB) after 5 min of transient forebrain ischemia in gerbils. In the sham-operated group, weak NF-200 immunoreactivity was detectable in a few somata of mitral cells, which projected weak NF-200-immunoreactive processes to the external plexiform layer (EPL). At 1-5 days after ischemia, strong NF-200 and RT97 immunoreactivity was shown by the mitral cell processes; however, somata of mitral cells did not show NF-200 immunoreactivity. At this time point, strong NF-200-immunoreactive mitral cell processes ran to the EPL and glomerular layer (GL). Thereafter, NF-200 and RT97 immunoreactivity was decreased up to 30 days after ischemia. In the 15 days post-ischemic group, the distribution pattern of NF-200 and RT97 immunoreactivity was slightly lower than that in the 1-5 days post-ischemic groups. In the 30 days post-ischemic group, moderate NF-200 and RT97 immunoreactivity was found in the mitral cells processes, but the immunoreactivity in the EPL and GL nearly disappeared. A Western blot study showed a pattern of NF-200 and RT97 expression at all post-ischemic time points similar to that of immunohistochemistry after ischemia. This result indicates that NF-200 and RT97 accumulates in injured mitral cell processes a few days after transient ischemia, which suggests that the axonal transport in the MOB may be disturbed during this period after transient ischemia.

Morphologic and neurochemical abnormalities in the auditory brainstem of the genetically epilepsy-prone hamster (GPG/Vall)

PURPOSE

This study was performed to evaluate whether audiogenic seizures, in a strain of genetically epilepsy-prone hamsters (GPG/Vall), might be associated with morphologic alterations in the cochlea and auditory brainstem. In addition, we used parvalbumin as a marker of neurons with high levels of activity to examine changes within neurons.

METHODS

Cochlear histology as well as parvalbumin immunohistochemistry were performed to assess possible abnormalities in the GPG/Vall hamster. Densitometry also was used to quantify levels of parvalbumin immunostaining within neurons and fibers in auditory nuclei.

RESULTS

In the present study, missing outer hair cells and spiral ganglion cells were observed in the GPG/Vall hamster. In addition, an increase was noted in the size of spiral ganglion cells as well as a decrease in the volume and cell size of the cochlear nucleus (CN), the superior olivary complex nuclei (SOC), and the nuclei of the lateral lemniscus (LL) and the inferior colliculus (IC). These alterations were accompanied by an increase in levels of parvalbumin immunostaining within CN, SOC, and LL neurons, as well as within parvalbumin-immunostained fibers in the CN and IC.

CONCLUSIONS

These data are consistent with a cascade of atrophic changes starting in the cochlea and extending along the auditory brainstem in an animal model of inherited epilepsy. Our data also show an upregulation in parvalbumin immunostaining in the neuropil of the IC that may reflect a protective mechanism to prevent cell death in the afferent sources to this nucleus.

Metabolite Changes in Normal-Appearing Gray and White Matter Are Linked With Disability in Early Primary Progressive Multiple Sclerosis

BACKGROUND

Abnormalities in normal-appearing brain tissues may contribute to disability in primary progressive multiple sclerosis (PPMS), where few lesions are seen on conventional imaging.

OBJECTIVES

To evaluate the mechanisms underlying disease progression in the early phase of PPMS by measuring metabolite concentrations in normal-appearing white matter (NAWM) and cortical gray matter (CGM) and to assess their relationship with clinical outcomes.

DESIGN

Case-control study.

SETTING

Tertiary referral hospital. Patients Forty-three consecutive patients within 5 years of onset of PPMS and 44 healthy control subjects.

MAIN OUTCOME MEASURES

Concentrations of choline-containing compounds, phosphocreatine, myo-inositol, total N-acetyl-aspartate (tNAA), and glutamate-glutamine were estimated using proton magnetic resonance spectroscopic imaging. Brain parenchymal, white matter and gray matter fractions and proton density and gadolinium-enhancing lesion loads were calculated. The Expanded Disability Status Scale and Multiple Sclerosis Functional Composite scores were recorded.

RESULTS

In CGM, concentrations of the tNAA (P<.001) and glutamate-glutamine (P = .005) were lower in patients with PPMS than in controls. In NAWM, myo-inositol levels were higher (P = .002) and tNAA levels were lower (P = .005) in patients with PPMS than in controls. The Expanded Disability Status Scale score correlated with the tNAA concentration in CGM (r = -0.44; P = .03) and with myo-inositol (r = 0.41; P = .01) and glutamate-glutamine concentrations (r = 0.41; P = .01) in NAWM. Proton density lesion load correlated negatively with CGM tNAA concentration and positively with NAWM myo-inositol concentration.

CONCLUSION

Metabolite changes, which differ in CGM and NAWM, occur in early PPMS and are linked with disability.

Size frequency distribution of prion protein (PrP) aggregates in variant Creutzfeldt-Jakob disease (vCJD)

The frequency distribution of aggregate size of the diffuse and florid-type prion protein (PrP) plaques was studied in various brain regions in cases of variant Creutzfeldt-Jakob disease (vCJD). The size distributions were unimodal and positively skewed and resembled those of beta-amyloid (A beta) deposits in Alzheimer's disease (AD) and Down's syndrome (DS). The frequency distributions of the PrP aggregates were log-normal in shape, but there were deviations from the expected number of plaques in specific size classes. More diffuse plaques were observed in the modal size class and fewer in the larger size classes than expected and more florid plaques were present in the larger size classes compared with the log-normal model. It was concluded that the growth of the PrP aggregates in vCJD does not strictly follow a log-normal model, diffuse plaques growing to within a more restricted size range and florid plaques to larger sizes than predicted.

Ultrastructural study of aggregates in the spinal cord of transgenic mice with a G93A mutant SOD1 gene

The ultrastructural features of SOD1-positive aggregates were determined to clarify whether these aggregates are associated with the pathogenesis of SOD1 mutant mice. We examined the spinal cord of transgenic mice expressing a G93A mutant human SOD1 gene with fewer copies (gene copy 10). At the early presymptomatic stage (age 24 weeks), SOD1- and ubiquitin-positive granular, linear, or round deposits were found occasionally in the neuropil of the anterior horns. Ultrastructurally, small filamentous aggregates were observed occasionally in the neuronal processes including the axons in the anterior horns. At the late presymptomatic stage (28 weeks), SOD1- and ubiquitin-positive deposits and Lewy body-like inclusions (LIs) were frequently demonstrated in the neuronal processes including cord-like swollen axons and in some remaining anterior horn neurons. Ultrastructurally, larger filamentous aggregates were frequent, predominating in the neuronal processes of the anterior horns including the proximal axons, but were rare in the somata and dendrites. The aggregates usually consisted of interwoven intermediate filaments (about 10-15 nm in diameter) and frequently contained electron-dense cores in the center resembling LIs. Occasionally the aggregates consisted mainly of granular, amorphous, or vesicular substance, showing fewer filamentous structures. At the symptomatic stages (32 and 35 weeks), LIs were frequently demonstrated within the neuronal processes in the anterior horns, particularly in the cord-like swollen axons. Many more prominent SOD1- and ubiquitin-positive deposits were observed over the whole white matter columns and in the gray matter of the anterior and posterior horns than at the previous stage. Ultrastructurally, aggregates frequently contained electron-dense cores, and were frequently observed in cord-like swollen axons consisting of accumulated neurofilaments. A high level of human SOD1-and ubiquitin-immunogold labeling was present in small to large aggregates even at the presymptomatic stages, and the aggregates increased in size and frequency with time. Compactly packed filaments and electron-dense cores of aggregates showed SOD1-and ubiquitin-immunogold labeling more prominently than in loosely packed filaments. These findings suggest that the accumulation of SOD1-positive aggregates in the neuronal processes, predominantly in the axons, constitutes an important determinant of neurotoxicity and the pathogenesis of this animal model, probably causing impairment of axonal transport by the sequestration of mutant SOD1 protein within aggregates, or in part by physically blocking the axonal transport.

Ependymoma with neuropil-like islands: a case report with diagnostic and histogenetic implications

We describe a case of ependymoma with neuronal differentiation in form of neuropil-like islands. A 6-year-old boy presented at clinical examination for a short history of headaches and vomiting. Brain computed tomography showed a large, partially cystic, parieto-occipital lesion. The tumor was composed by glial fibrillary acidic protein-positive round cells with a perivascular arrangement and scattered neuropil-like islands, showing intense positivity for synaptophysin. Despite radiotherapy, the tumor recurred, showing frank features of anaplasia, but lacking the neuropil-like islands. The histological features of the tumor are discussed in the light of the concept that neuronal differentiation can occur occasionally in gliomas of different lineage without affecting the expected biological behavior.

Alzheimer's pathology in human temporal cortex surgically excised after severe brain injury

Traumatic brain injury (TBI) is a risk factor for the development of Alzheimer's disease (AD). This immunohistochemical study determined the extent of AD-related changes in temporal cortex resected from individuals treated surgically for severe TBI. Antisera generated against Abeta species (total Abeta, Abeta(1-42), and Abeta(1-40)), the C-terminal of the Abeta precursor protein (APP), apolipoprotein E (apoE), and markers of neuron structure and degeneration (tau, ubiquitin, alpha-, beta-, and gamma-synuclein) were used to examine the extent of Abeta plaque deposition and neurodegenerative changes in 18 TBI subjects (ages 18-64 years). Diffuse cortical Abeta deposits were observed in one third of subjects (aged 35-62 years) as early as 2 h after injury, with only one (35-year old) individual exhibiting "mature", dense-cored plaques. Plaque-like deposits, neurons, glia, and axonal changes were also immunostained with APP and apoE antibodies. In plaque-positive cases, the only statistically significant change in cellular immunostaining was increased neuronal APP (P = 0.013). There was no significant correlation between the distribution of Abeta plaques and markers of neuronal degeneration. Diffuse tau immunostaining was localized to neuronal cell soma, axons or glial cells in a larger subset of individuals. Tau-positive, neurofibrillary tangle (NFT)-like changes were detected in only two subjects, both of more advanced age and who were without Abeta deposits. Other neurodegenerative changes, evidenced by ubiquitin- and synuclein-immunoreactive neurons, were abundant in the majority of cases. Our results demonstrate a differential distribution and course of intra- and extra-cellular AD-like changes during the acute phase following severe TBI in humans. Abeta plaques and early evidence of neuronal degenerative changes can develop rapidly after TBI, while fully developed NFTs most likely result from more chronic disease- or injury-related processes. These observations lend further support to the hypothesis that head trauma significantly increases the risk of developing pathological and clinical symptoms of AD, and provide insight into the molecular mechanisms that initiate these pathological cascades very early during severe brain injury.

[Synaptic plasticity of neocortex of albino rats in diffuse-focal injuries of the brain]

In an experiment conducted using mature albino rats, the regularities of reorganization of synaptic architectonics of cortical layer I of the brain were studied in the areas of diffuse-focal injuries. The models of acute break of systemic circulation (clinical death) as a result of 6-minute-long mechanical asphyxia, compression of common carotid arteries for 20 min (ischemia) and rotatory sublethal injury according to Noble-Collip method (cranial trauma), were used. Using the methods of electron microscopy and morphometric analysis, it was shown that a reduction in a general numerical density of synapses was accompanied by the changes in relative and absolute numbers of major variants of synaptic organization. The content of large simple and perforated contacts was increased, as well as of synapses with invaginated synaptic membranes, containing mitochonria and spine apparatus. The changes detected are considered as a structural basis for realization of the mechanisms of synaptic plasticity in diffuse-focal injuries of the brain.

Microanatomy of the dysplastic neocortex from epileptic patients

Focal cortical dysplasia (FCD) is a pathology that is characterized by the abnormal development of the neocortex. Indeed, a wide range of abnormalities in the cortical mantle have been associated with this pathology, including cytoarchitectonic alterations and the presence of dysmorphic neurons, balloon cells and ectopic neurons in the white matter. FCD is commonly associated with epilepsy, and hence we have studied the ultrastructure of cortical tissue resected from three subjects with intractable epilepsy secondary to cortical dysplasia to identify possible alterations in synaptic circuitry, using correlative light and electron microscopic methods. While the balloon cells found in this tissue do not appear to receive synaptic contacts, the ectopic neurons in the white matter were abnormally large and were surrounded by hypertrophic basket formations immunoreactive for the calcium-binding protein parvalbumin. Furthermore, these basket formations formed symmetrical (inhibitory) synapses with both the somata and the proximal portion of the dendrites of these giant ectopic neurons. A quantitative analysis revealed that in the dysplastic tissue, the density of excitatory and inhibitory synapses was different from that of the normal adjacent cortex. Both increases and decreases in synaptic density were observed, as well as changes in the proportion of excitatory and inhibitory synapses. However, we could not establish a common pattern of changes, either in the same patients or between different patients. These results suggest that cortical dysplasia leads to multiple changes in excitatory and inhibitory synaptic circuits. We discuss the possible relationship between these alterations and epilepsy, bearing in mind the possible limitations that preclude the extrapolation of the results to the whole population of epileptic patients with dysplastic neocortex.