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  • 1
    ISSN: 1432-0533
    Keywords: Experimental malignant Schwannomas ; Tissue and organ culture ; Differentiation ; Invasion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Explants from seven nerve sheath tumors (four cranial and three spinal) induced in rats by transplacental ethylnitrosourea were grown on collagen-coated coverslips and in organ culture systems, using sponge foam matrices and Millipore filter platforms. Their sequential morphological features in vitro were compared to those of a human acoustic Schwannoma maintained in similar culture systems. The original experimental tumors were either undifferentiated or poorly differentiated malignant Schwannomas. In cultures on collagen-coated coverslips the explants demonstrated cellular features that were considerably more anaplastic than those of the human acoustic Schwannoma. On the other hand, in organ culture systems, in which viable cultures were maintained up to 82 days, many of the experimental tumor explants exhibited progressive differentiation, with nuclear palisading, increasing whorl formation and abundant reticulin fibers, and their pattern of histological organization came therefore closely to resemble that of the cultured acoustic Schwannoma. Unlike the latter, however, the cultured experimental tumors infiltrated the sponge foam matrices, a feature that mimicked the invasive character of the original tumors in vivo. Included normal ganglion cells remained demonstrable in the cultures up to 69 days in vitro.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Experimental malignant Schwannomas ; Melanin and melanogenesis ; Tissue and organ culture ; Electron microscopy ; Pigmented nerve sheath tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Four melanin pigment-containing intracranial tumors were found in three Long-Evans rats in the course of experimental oncogenesis by transplacental ethylnitrosourea (ENU). One of them was a leptomeningeal melanoma. Aside from the presence of scattered melanin-pigmented cells, the other three had the typical histological features of ENU-induced malignant nerve sheath tumors. Two of the three tumors were studied by electron microscopy and in tissue and organ culture systems. One of them demonstrated progressive melanogenesis in vitro; the other failed to produce more melanin and showed increasing differentiation, with a Schwannoma-like pattern by light microscopy. Melanosomes and premelanosomes were identified in both tumors by electron microscopy; the other fine structural features were those of malignant Schwannomas. These observations are relevant to the controversy on the histogenesis of pigmented nerve sheath tumors occasionally encountered in man and on the relationship of these tumors to pigmented nevi. The findings in the present study support the view of Masson that neoplastic nerve sheath cells are capable of melanogenesis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Experimental malignant Schwannomas ; Organ culture ; Electron microscopy ; Differentiation ; Microtubules ; Basal lamina ; Perineurial fibroblasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The sequential electron microscopic features of six malignant nerve sheath tumors (three cranial and three spinal) induced in rats by transplacental ethylnitrosourea and maintained in organ culture systems were compared with those of a human acoustic Schwannoma similarly cultured. After 4 weeks in vitro, the malignant tumor cells often showed progressive elongation of their processes, with the development of an interdigitating pattern resembling that seen in well-differentiated Schwannomas. This was accompanied by an increase of microtubules. Basal lamina formation, less well-developed and less complete than in the benign Schwannoma in this study, was maintained in culture. Some explants demonstrated an increase in number and width of collagen fibrils, accompanied by a relative concomitant decrease of intercellular basement membrane material. The malignant tumor cells also showed numerous micropinocytotic vesicles and various junctional complexes, which are characteristic of perineurial cells. Since the origin of the experimental tumors from adult Schwann cells seems well established, this apparent contradiction is best resolved by the concept that Schwann cells and perineurial fibroblasts are functional variants of the same cell type.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neuro-oncology 7 (1989), S. 89-101 
    ISSN: 1573-7373
    Keywords: brain tumors ; Corynebacterium parvum ; tumor retardation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experiments were performed to determine the effectiveness of Corynebacterium parvum on resistance to growth and development of tumor in the central nervous system. A syngeneic sarcoma was injected intracerebrally into C3H/HeN/MTV negative female mice that had received intraperitoneal injections of C. parvum or saline prior to tumor inoculation or that received intraperitoneal C. parvum or saline after tumor inoculation. Groups then received an intracerebral injection of C. parvum or saline. Our results reveal that intracerebral C. parvum elicited an intracerebral inflammatory reaction which was enhanced by prior systemic priming with C. parvum. Any inflammatory reaction produced by C. parvum retarded the growth of intracerebrally-implanted sarcoma and significantly increased the survival of mice bearing such tumors. These results suggest that C. parvum may be an effective therapeutic agent in the treatment of neoplasia of the central nervous system.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neuro-oncology 7 (1989), S. 261-267 
    ISSN: 1573-7373
    Keywords: brain tumor ; IL-2 ; C. Parvum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The toxicity of IL-2 and/or C. Parvum when injected directly into the mouse brain was examined by survival and histopathology using different numbers of injections, different doses of IL-2, different solvents for the IL-2, and different doses and routes of administration of C. Parvum. Two injections was found significantly to increase mortality (19%) over a single injection (4%). Mortality from two injections of 30,000 U (23%) or 60,000U (20%) was higher than from two injections of 15,000U (12%). The mortality from two injections with normal saline as solvent was much higher (29%) than from two injections with sterile water (19%) or D5W (9%). Two injections of IL-2 given simultaneously with C. Parvum showed a much higher mortality (26%) than other doses and routes of C. Parvum administration. Mice dying acutely (6–24 days) of toxicity showed an extensive mononuclear infiltrate at the site of injection. The brains of surviving mice (sacrificed at 30 days) showed a mild residual mononuclear cell infiltrate with the exception of mice which had received IL-2 and C. Parvum simultaneously. Brains from this latter group had an extensive residual mononuclear cell infiltrate.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurocytology 2 (1973), S. 457-464 
    ISSN: 1573-7381
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The finding of intracellular septate desmosome-like structures in a human acoustic Schwannoma maintained in an organ culture system is detailed. These structures differ in their cellular location from the intercellular septate junctional complexes which have been described in invertebrates and in a few vertebrate tissues. They also differ from the inter- and intramitochondrial septate structures which have occasionally been reported, in that they are not related to mitochondria but rather to the cell plasma membrane. Intracellular septate complexes of this type have not previously been described.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cancer and metastasis reviews 1 (1982), S. 203-213 
    ISSN: 1573-7233
    Keywords: CNS metastasis ; rats ; mice ; arterial dissemination ; brain preference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Reliable animal models of metastatic disease to the central nervous system (CNS) are a necessary prerequisite to understanding those mechanisms of development and growth of neoplasia which may be unique to the brain. The ideal model, which should mimic the clinical picture of CNS metastasis in humans, has yet to be developed. Available models contain some degree of artificiality in that they depend upon either arterial inoculation of a tumor cell bolus or intravenous injection of a bolus of cells from a selected tumor cell colony which shows preference for the brain. Applications as well as advantages and disadvantages of the various models are considered.
    Type of Medium: Electronic Resource
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