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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Histopathology 29 (1996), S. 0 
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a recent study we described a population of small epithelial cells (SEC) in human hepatoblastoma that exhibit ultrastructural features of the oval cells of rodents. Both SEC and oval cells are immunoreactive for cytokeratin 7, a marker of biliary differentiation, and it was postulated that SEC, like oval cells, are closely related to hepatic stem cells. This study was undertaken to investigate whether SEC also exhibit immunolabelling for albumin, a marker of hepatocytic differentiation, and to determine whether other antigens typical of oval cells are detectable in hepatoblastoma.〈section xml:id="abs1-2"〉〈title type="main"〉Methods and results:Hepatoblastomas of various subtypes were investigated by electron microscopy, and by immunohistochemistry with the monoclonal antibodies OV-1 and OV-6, which recognize antigens associated with oval cells. Double-labelling for cytokeratin 7 and albumin was carried out by immuno-electron microscopy. OV-1 stained scattered cells in seven of 12 tumours investigated and OV-6 in nine. On immunoelectron-microscopic investigation, SEC exhibited labelling for both cytokeratin 7 and albumin.〈section xml:id="abs1-3"〉〈title type="main"〉Conclusions:The results demonstrate that antigens associated with oval cells are found in certain cells in hepatoblastoma. SEC, like oval cells, co-express markers for hepatocytic and biliary differentiation. The findings further support the hypothesis that SEC are closely related to the putative bipotent hepatic stem cell, which, by definition, gives rise to both hepatocytes and biliary epithelial cells.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Cancer Genetics and Cytogenetics 38 (1989), S. 167 
    ISSN: 0165-4608
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Cancer Genetics and Cytogenetics 38 (1989), S. 164 
    ISSN: 0165-4608
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1463
    Keywords: Keywords:β-actin ; β2-microglobulin ; competitive RT-PCR ; GAPDH ; post-mortem ; RNA ; Trk B ; Trk C.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. RNA isolated from frozen human post-mortem brain tissue was used for analysis of five gene products with a recently developed sensitive and competitive RT-PCR technique. Samples varying in post-mortem intervals up to four days from controls, schizophrenics and alcoholics were analyzed. Evaluation of three housekeeping genes, as well as Trk B and Trk C demonstrated that the levels of mRNA transcripts were stable in brain samples at all time periods (one to four days) examined. This observation demonstrates that this RT-PCR protocol is a sensitive and reliable method to study relative amounts of mRNAs. The overall stability of housekeeping transcripts implicates the value of post-mortem brain samples for differential gene expression studies.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2307
    Keywords: Hepatoblastoma ; Adhesion molecules ; CALLA ; Immunohistochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hepatoblastoma is an embryonal tumour of the liver, which often contains tissue components with multidirectional differentiation. The occurrence of cell surface antigens in this tumour has not been studied systematically, and we therefore investigated 20 hepatoblastomas for the expression of common acute lymphoblastic leukaemia antigen (CALLA) and cell adhesion molecules (CAMs) in their different tissue components. Epithelial tumour cells of fetal differentiation contained E-cadherin. This protein did not occur in tumour areas with embryonal or mesenchymal differentiation. In contrast, immature embryonal and anaplastic cells expressed CALLA and the hyaluronate receptor (HCAM, CD44). Both fetal and embryonal areas stained irregularly positive for ICAM-1, which, in contrast, was not present on anaplastic cells. Immature fibrous tissue did not contain any of these molecules except for ICAM-1. However, some cells adjacent to, or enclosed in, osteoid were positive for HCAM and NCAM. Like small undifferentiated hepatoblastoma cells, primitive mesenchymal spindle-shaped cells also expressed CALLA, HCAM, and the polysialylated embryonic form of NCAM strongly. This last is not present on other epithelial or mesenchymal tumour cells. Hepatoblastoma cells of varying differentiation express distinct patterns of CAMs and CALLA. Our results give further insight into their histogenesis and cellular interactions and may explain their variable ability for invasive growth and formation of metastases.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0533
    Keywords: Key words Vascular endothelial growth factor ; Brain tumor ; Astrocytoma ; Angiogenesis ; Vascularization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Marked neovascularization is a hallmark of many neoplasms in the nervous system. Recent reports indicate that the endothelial mitogen vascular endothelial growth factor (VEGF) may play a critical role in the regulation of vascular endothelial proliferation in malignant gliomas. Using novel monoclonal antibodies to the VEGF polypeptide we have determined the expression and cellular distribution of VEGF protein in a representative series of 171 human central nervous system (CNS) tumors by immunohistochemistry and immunoblotting. In agreement with previous in situ hybridization data, 19 out of 20 glioblastomas (95%) showed immunoreactivity for VEGF, whereas both the percentage of immunoreactive tumors and the extent of immunoreactivity for VEGF were significantly lower in astrocytomas. Of the pilocytic astrocytomas (WHO grade I) 44% were immunoreactive for VEGF, but we observed several cases with pronounced vascular proliferates in the absence of VEGF. In ependymomas, meningiomas, hemangioblastomas, and primitive neuroectodermal tumors, there was no correlation between VEGF expression, vascular endothelial proliferation and the grade of malignancy. Oligodendrogliomas and the oligodendroglial component of mixed gliomas lacked immunoreactive VEGF, indicating that endothelial growth factors other than VEGF may regulate tumor angiogenesis in these neoplasms. Western blot analysis showed a predominant VEGF protein species of 23 kDa and confirmed the immunohistochemical data in all cases. Our findings demonstrate that VEGF is expressed in a wide spectrum of brain tumors in which it may induce neovascularization. However, other angiogenic factors also appear to contribute to the vascularization of CNS neoplasms.
    Type of Medium: Electronic Resource
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