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  • 1
    ISSN: 1432-0533
    Keywords: Neurofibromatosis 2 ; Bilateral acoustic neurofibromatosis ; Ghal hamartomas ; Immunohistochemistry ; S-100 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bilateral acoustic neurofibromatosis (neurofibromatosis 2, NF2) accounts for less than 10% of all cases of neurofibromatosis and manifests itself with bilateral acoustic schwannomas, multiple schwannomas of spinal nerve roots, meningiomas, glial tumors and hamartomatous CNS lesions. We have observed dysplastic foci of immature neuroectodermal cells in the cerebral cortex and basal ganglia of six patients afflicted with neurofibromatosis 2, ranging from occasional clusters of immature, dysplastic cells to numerous, confluent lesions. These cells, although often polymorphic and multinuclear did not show mitotic acitivity or a tendency for neoplastic transformation. To determine the histogenesis of these foci, extensive immunocytochemical reactions were carried out with antibodies to a variety of glial, neuronal and nonneural cell lineages. With the exception of S-100 protein, no immunoreactivity was detectable. S-100 was consistently expressed in these foci, irrespective of their size, location, and degree of polymorphism. On the basis of cytological appearance, distribution and immunoreactivity we tentatively designate these foci as glial micro-hamartomas. Although we did not systematically analyze the CNS of patients with von Recklinghausen neurofibromatosis (neurofibromatosis 1, NF1), the present study strongly suggests that these micro-hamartomas constitute a morphological hallmark of bilateral acoustic neurofibromatosis (NF2).
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Medullomyoblastoma ; Neuronal differentiation ; Hamartoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This report describes an unusual medullo-myoblastoma which developed in the cerebellar vermis of a 6-year-old girl. Histological investigation showed a highly cellular and predominantly undifferentiated tumor. Myogenic differentiation was prominent in clusters of large tumor cells with eosinophilic cytoplasm and immunoreactivity for desmin and myoglobin. Electron microscopy revealed the presence of immature Z-bands. Immunohistochemically, numerous cells showed incipient expression of myoblastic marker antigens, supporting the view that medulloblastomas and related primitive neuroectodermal tumors possess the potential for non-neural differentiation. In addition, there was evidence of advanced neuronal differentiation, with expression of neuron-specific enolase, synaptophysin, retinal S-antigen, and the formation of ganglioid tumor cells. Occassional neoplastic cells expressed glial fibrillary acidic protein without morphologically detectable astrocytic differentiation. Associated with the neoplasm was brain tissue containing clusters of neuronal cells and focal accumulations of immature oligodendroglia-like cells which expressed neuronal marker antigens. This unusual component resembled a hamartomatous lesion and would support the hypothesis that the cerebellar medullomyoblastoma originated from a teratomatous or malformative lesion. Alternatively, this component may constitute the end stage of advanced neuronal differentiation of a primitive neuroectodermal tumor.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Epilepsy ; Pathology ; Tumor ; Malformation ; Inflammation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The surgical treatment of chronic pharmacoresistant epilepsies is increasing rapidly. Although several studies have reported on histopathological findings in temporal lobe epilepsy, little is known about the surgical pathology of other seizure disorders. Here we report the histopathological fingings in 63 consecutive surgical specimens of patients who were operated for chronic pharmacoresistant epileptic seizures other than temporal lobe epilepsy (37 corticectomies, 19 functional hemispherectomies, 5 lobectomies, 1 multilobectomy, and 1 frontal lobe deafferentiation combined with a temporal lobectomy). There were structural lesions in 85.7% of the specimens. In 16 cases (25.4%) the predominant lesions were malformative (focal glioneuronal hamartias and hamartomas, vascular malformations, abundant ectopic neurons in the white matter, microgyria, and arachnoid cyst). Lesions indicating preor perinatal necrosis such as porencephaly, ulegyria, and congenital hemiatrophy were present in 7 cases (11.1%). Twelve specimens (19.0%) contained low-grade neoplasms (7 gangliogliomas, 3 astrocytomas, 1 oligoden-droglioma and 1 oligoastrocytoma). There were 3 cases of Rasuussen encephalitis, 1 specimen with atrophy and gliosis due to previous herpetic encephalitis and 1 case with an old abscess wall. Posttraumatic or postoperative changes were the predominant finding in 7 specimens (11.1%). In 7 patients there were only nonspecific changes such as cortical atrophy and gliosis or old hemorrhage. No structural alterations were identified in 9 specimens (14.3%). The findings suggest that the structural lesions observed in the great majority of the specimens were closely related to the pathogenesis of intractable seizures.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0533
    Keywords: HIV encephalitits ; HIV myelitis ; Human immunodeficiency virus ; Polymerase chain reaction ; In situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The presence and distribution of human immunodeficiency virus (HIV) were examined in the CNS of two children with severe HIV encephalitis and myelitis. Using polymerase chain reaction-mediated DNA amplification and subsequent Southern analysis, proviral HIV gag sequences were identified in brain tissue of both patients. In situ hybridization using antisense oligonucleotide probes revealed abundant HIV gag and env/nef RNAs selectively in areas with histopathological evidence for HIV-induced tissue damage. The spinal cord of one patient exhibited a striking subpial accumulation of HIV RNAs strongly suggestive of a liquorigenic spread of the infection. HIV RNAs were typically associated with cells of the monocyte/macrophage lineage, as shown by a combined immunohistochemical and in situ hybridization procedure. The present study supports the view that the pattern and distribution of HIV-induced brain lesions is largely determined by the extent of focal HIV replication within the CNS.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 79 (1990), S. 473-479 
    ISSN: 1432-0533
    Keywords: Central neurocytoma ; Neuronal differentiation ; Glial differentiation ; Synaptophysin ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Central neurocytoma has been characterised by its intraventricular localisation, predominant occurrence in young adults, oligodendroglioma-like histology, benign course and ultrastructural evidence for neuronal differentiation. Eleven intraventricular central neurocytomas were studied histopathologically, employing cell type-specific immunocytochemical markers and electron microscopic analysis. In the past, these lesions have caused diagnostic problems since central neurocytomas share basic histopathological features with other periventricular neoplasms. Accordingly, several tumours of this series had previously been classified as ependymomas of the foramen of Monro or oligodendrogliomas. Although generally regarded as benign lesions, two central neurocytomas of this series showed histopathological evidence of anaplasia, with focal necrosis, mitotic activity and vascular proliferation. All central neurocytomas exhibited immunoreactivity for neuronspecific enolase and synaptophysin, indicating consistent neuronal differentiation. Three tumours were studied by electron microscopy and contained synaptic vesicles, neuritic processes and neurosecretory granules. In addition, one tumour contained ganglioid cells and this was associated with focal immunoreactivity for neurofilament protein, suggesting that some central neurocytomas may, at least focally, continue to differentiate towards the formation of mature neurons. Two of the tumours expressed glial fibrillary acidic protein in a considerable percentage of neoplastic cells which demonstrates a capacity for bipotential, i.e. glial and neuronal differentiation. We conclude that the central neurocytoma can be reliably diagnosed using antibodies to neuron-specific enolase and synaptophysin, and that histogenetically, this neoplasm is derived from a neuroectodermal precursor cell capable of both, neuronal and glial differentiation. The hypothesis is proposed that the central neurocytoma originates from the subependymal plate of the lateral ventricles, an embryonal matrix cell layer which postnatally maintains a limited proliferative potential.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0533
    Keywords: AIDS-Cerebral toxoplasmosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Frequency, pathogenesis and morphological features of toxoplasmosis were assessed in a consecutive autopsy study. Among 204 patients who died from AIDS in Zurich during 1981–1990, 46 (23%) showed morphological evidence of cerebral toxoplasmosis. In 38 out of 46 cases (83%), toxoplasmosis was restricted to the central nervous system (CNS) and, therefore, pathogenetically classified as reactivation of a latent infection. Acute, systemic toxoplasmosis most frequently involved heart and lungs in addition to the CNS and was observed in 7 cases (15%). These patients probably acquired the infection during HIV-induced immunosuppression. Latent infection with intracerebral tissue cysts but no inflammatory response was present in only one case. Diffuse, necrotizing toxoplasma encephalitis with widespread, confluent areas of necrosis was mainly observed during the early period of the AIDS epidemic and restricted to 6 patients (13%) who did not receive chemotherapy. The majority of patients (83%) had multiple, macroscopically well-circumscribed abscesses with preferential location in the cerebral hemispheres. Of all CNS regions, the rostral basal ganglia were most frequently affected (78% of cases). Since 1989, chronic, burnt-out lesions were observed. These were mainly composed of lipid-laden macrophages and immunocyto-chemistry for Toxoplasma gondii usually failed to detect the parasite. This changing pattern of CNS lesions probably reflects improved clinical management of patients with AIDS.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Limbic P300 potentials can be recorded within the mesial temporal lobes of patients with temporal lobe epilepsy (TLE). To delineate possible mechanisms of their generation and pathological alteration, we analysed limbic P300s in 55 TLE patients with and 29 without Ammon’s horn sclerosis (AHS) and correlated their amplitudes with neuronal cell counts in 30 histopathological specimens. Limbic P300 amplitudes were reduced on the side of the epileptogenic focus only in patients with AHS. Moreover, in AHS patients, limbic P300 latencies were prolonged bilaterally; and in patients with left-sided AHS, amplitudes were reduced bilaterally. Both findings suggest bilateral functional deficits in TLE with unilateral AHS. Limbic P300 areas correlated significantly with neuronal densities of dentate gyrus granule cells but not hippocampal pyramidal cells in the CA1–4 (cornu ammonis) subfields. This finding points to a potential mechanism for the bilateral effects of unilateral AHS as both dentate gyri exhibit strong reciprocal contralateral connectivity.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Der Onkologe 4 (1998), S. 580-588 
    ISSN: 1433-0415
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Die heterogene Gruppe der malignen Gliome umfaßt so verschiedene Tumoren wie die anaplastischen Astrozytome, anaplastischen Oligodendrogliome, anaplastischen Oligoastrozytome (sog. Mischgliome), Glioblastome, anaplastischen Ependymome und auch anaplastische Tumoren des Plexus chorioideus. In diesem Beitrag möchten wir den momentanen Stand der neuropathologischen Diagnostik dieser Entitäten beleuchten sowie Kontroversen und neue Entwicklungen aufzeigen.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 108 (1984), S. 56-59 
    ISSN: 1432-1335
    Keywords: DNA methylation ; Rat ; Procarbazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cytostatic drug procarbazine has previously been shown to be a potent transplacental neurotropic carcinogen in rats. Following a single IP administration of (14C-methylprocarbazine (110 mg/kg) on day 22 of gestation, methylation products with cellular DNA were determined in fetal and maternal rat organs. The concentration of the major adduct N7-methylguanine was highest in the maternal liver (224 μmol/mol guanine). Fetal and nonhepatic maternal tissues exhibited significantly lower levels, but differed little from each other. In brain, lung, intestines, and placenta the O 6-methylguanine/N7-methylguanine ratio was close to 0.11, indicating that procarbazine, like other methylating carcinogens, initiates malignant transformation via methyldiazonium hydroxide as the ultimate reactant. Following a single dose of (14C-methyl)procarbazine to newborn animals, methylpurine values were 30–60 times lower than after prenatal administration. This suggests that DNA alkylation in nonhepatic tissues occurs by systemic distribution of a proximate carcinogen formed in the adult rat liver.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0533
    Keywords: Key words Plaque formation ; β-Amyloid precursor ; protein  ; Alzheimer’s disease ;  Transplantation ; βA4 peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Abnormal processing of β-amyloid precursor protein (APP) and precipitation of amyloidogenic βA4 peptide have been implicated in the pathogenesis of Alzheimer’s disease (AD). In an attempt to generate an in vivo model of APP-associated pathology, we have introduced recombinant retroviral vectors harboring normal and mutant cDNAs for human neuron-specific APP 695 into fetal rat brain transplants. A minor population of recombinant neural cells with expression of APP was identified immunohistochemically in the grafts. The expression was maintained during an observation period of 9 months. Neurons with strong immunoreactivity for human APP exhibited markedly swollen perikarya and showed signs of cell degeneration. At 6 months post-transplantation, recombinant grafts developed APP-positive neuropil deposits with morphological features of neuritic plaques, but without βA4 peptide immunoreactivity. No difference was observed between wild-type APP and the mutant APP construct derived from a family with autosomal dominant AD. These observations indicate that long-term neuronal overexpression of human APP has the potential to generate APP plaques in the rodent brain.
    Type of Medium: Electronic Resource
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