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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 78 (1989), S. 472-483 
    ISSN: 1432-0533
    Keywords: Astroblastoma ; Electron microscopy ; Immunohistochemistry ; Organ culture ; Tanycytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two examples of cerebral astroblastoma have been studied by electron microscopy and immunohistochemistry, one of them having been maintained in vitro in an organ-culture matrix system for 8 months and the explants studied by light and electron microscopy at different time intervals. The fine structural characteristics were those of a glial cell type with features intermediary between those of astrocytes and ependymocytes. They recapitulated the structure of the tanycyte, a glial precursor cell which is normally found scattered along the ependymal lining of the embryonal and neonatal mammalian brain, but is distinct from epithelial ependymocytes. The possible origin of some astroblastomas from such a cell would account for a number of characteristics in this enigmatic type of glioma.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Immunohistochemistry ; Medulloepithelioma ; Cytoskeletal proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four examples of human cerebral medulloepithelioma were studied immunohistochemically with a panel of antibodies and antisera to neuronal and glial proteins. The tumors, in addition to primitive medullary epithelium, contained areas of neuroblastic, ganglionic, astrocytic, ependymoblastic and ependymal differentiation, and, in one tumor, areas resembling polar spongioblastoma. Tumor cells throughout the primitive medullary epithelium displayed focal immunocreactivity for vimentin, glial fibrillary acidic (GFA) protein and for the neuron-associated class III β-tubulin isotype. Neuroblasts showed immunoreactivity for the class III β-tubulin isotype, microtubule-associated protein 2 and neuron-specific enolase. Immunoreactivity for neurofilament epitopes and synaptophysin was detected in areas of ganglionic differentiation and coincided with the demonstration of neurofibrils in Bielschowsky's silver impregnations. Vimentin was the only marker detected in ependymoblastic and ependymal rosettes or in areas of polar spongioblastoma, as well as in mesenchymal, cells. The results indicate that, even in very primitive neoplastic neuroepithelium, immunocytochemical evidence of early commitment of some of the cells to a neuronal or glial lineage can be demonstrated. The neuron-associated class III β-tubulin isotype appears to be one of the earliest markers indicative of neuronal differentiation in normal and neoplastic primitive neuroepithelium.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Glioblastomas ; Organ culture method ; Autoradiography ; Kinetics ; Growth fraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Five human glioblastomas maintained in an organ culture system were studied by autoradiography to determine, after 8 days in vitro, the growth fraction (GF) of the explants, their total cell cycle time (T C) and cell cycle phase durations (T S,T G1,T G2 andT M), and their potential doubling time (T pot) after pulse-labeling with [3H] TdR for 1 h. These parameters were derived from computer analysis of fraction of labeled mitoses (FLM) curves. The results fell into two groups. In two tumors, the cultures had a GF of 0.25 and 0.23. From the FLM curves were derived aT C of 89 and 83 h, aT S of 16.5 and 9.5 h, and aT G1 of 60 and 61 h.T M was estimated at 0.9 and 0.6 h, andT G2 12h. TheT pot was 12 days. These values approximate those reported for glioblastomas and other human malignancies in vivo. The explants of three other glioblastomas gave different FLM curves: the derivedT S were increased to 36 and 55 h, estimatedT M ranged from 2.4 to 4.5 h, andT G2 ranged from 11 to 20 h.T C andT G1 could not be estimated. In two tumors the GF was reduced to 0.12 and 0.11, with aT pot of respectively 52 and 39 days. These values are comparable to those reported for astrocytomas of intermediate malignancy. In the third tumor, the GF was only 0.014. The reduction in GF and the lengthening of cell cycle components in this group of explants are similar to the kinetic changes reported in some in vivo tumors and three-dimensional in vitro systems that have reached a plateau stage of growth. They are probably related to the greater opportunities for cell-to-cell contacts and the resulting increased differentiation favored by the organ culture technique.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1463
    Keywords: Autoradiography ; neurotensin ; schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Neurotensin, an endogenous peptide and putative neurotransmitter, exhibits a wide range of interactions with dopaminergic neurons and displays some actions akin to neuroleptics. Moreover, neurotensin receptors are abundant in specific layers of the entorhinal cortex where cytoarchitectural abnormalites have been reported in schizophrenia. We therefore examined the entorhinal cortex from postmortem specimens of five control patients and six schizophrenic patients for alterations in neurotensin receptor quantitation and distribution using receptor autoradiography. Specific125I-neurotensin binding was concentrated in layer II cell clusters, with a 40% reduction in binding in the schizophrenic group (p〈0.05). Moderate binding was observed in both cohorts in deep layers V/VI, with negligible binding in the hippocampus. There was no statistical difference in quantitative neurotensin binding in other lamina of the entorhinal cortex of schizophrenics compared with controls. The characteristic laminar pattern of binding did not differ between cohorts. The reduction in neurotensin binding in schizophrenics is consistent with an increasing number of reports of structural abnormalities in the medial temporal lobe of schizophrenics in general and the entorhinal cortex in particular. Further studies are required to examine the evidence for neuroanatomic and neurochemical pathology in the entorhinal cortex.
    Type of Medium: Electronic Resource
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