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  • 1
    ISSN: 1432-0533
    Keywords: Medulloblastoma ; S-Antigen ; Rod-opsin ; Prognosis ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Biopsy specimens of 66 medulloblastomas were investigated by means of S-antigen and rod-opsin immunocytochemistry. The patients were operated between 1969 and 1988 and the medical records were retrospectively evaluated to correlate the immunocytochemical features of the tumors to the course of the disease. S-antigen- and rod-opsin-immunoreactive tumor cells were found in 19 out of 66 cases. Since in the normal non-neoplastic state immunoreactive S-antigen and rod-opsin are restricted to retinal photoreceptors and a class of pinealocytes derived from photoreceptor cells, the occurrence of these proteins in certain tumor cells of medulloblastomas suggests a differentiation of these cells along the photoreceptor cell lineage and allows the identification of a special subtype of medulloblastoma displaying photoreceptor-specific characteristics. This subtype appears to be closely related to retinoblastomas and pineal cell tumors. The incidence of this subtype corresponds to approximately 30% of all medulloblastomas. Correlation between the demonstration of immunoreactive S-antigen and rod-opsin and the course of the disease revealed a 10-year survival rate of 50.6% for patients with medulloblastomas displaying photoreceptor-specific characteristics and maximally 11% for patients suffering from medulloblastomas devoid of these markers. Although the statistical evaluation does not provide a significant result, the estimatedP-value of 0.085 indicates a distinct trend toward a better prognosis for patients suffering from medulloblastomas with photoreceptor-specific features. The validity of this trend needs to be proven in further studies with a greater number of patients.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Medulloblastoma ; Retinal ; Rod-opsin ; S-Antigen ; Photoreceptor cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the present study was to evaluate the putative photoreceptor differentiation found in certain cerebellar medulloblastomas. The analyses were focussed on S-antigen, rod-opsin (the apoprotein of the visual pigment rhodopsin) and 11-cis retinal (the prosthetic group of rhodopsin). Fresh frozen and paraffinembedded biopsy specimens of three medulloblastomas were investigated by means of immunocytochemistry, enzyme-linked immunosorbent assay (ELISA), high-pressure liquid chromatography (HPLC), and immunoblotting. As shown in paraffin sections, one out of the three tumors (tumor A) contained S-antigen- and rod-opsin-immunoreactive tumor cells. The immunoblotting technique revealed in this tumor a single protein band of approximately 48–50 kDa that reacted with the S-antigen antibody and three protein bands of approximately 40, 75 and 110 kDa recognized by the rod-opsin antibody. These bands could not be detected in the two remaining tumors (tumor B and C). The rod-opsin content of tumor A was quantified by the ELISA; 11.7 pmol rod-opsin were calculated for the biopsy. The HPLC demonstrated the presence of 11-cis- and all-trans-retinal in tumor A, but not in tumors B and C. Furthermore, it was shown that 11-cis-retinal was converted to all-trans-retinal upon illumination of the tumor extract. The ratio between 11-cis-and all-trans-retinal was approximately 1:1 before illumination and 3:5 after illumination. A total of 2–3 pmol of retinal was found in the biopsy of tumor A. In addition all-trans-retinol was present in this tumor. The results indicate that certain medulloblastomas express a functional photopigment and S-antigen, another protein of the phototransduction cascade. They strongly support the concept that medulloblastoma cells may differentiate along the photoreceptor cell lineage.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0533
    Keywords: Interphotoreceptor retinoid-binding protein (IRBP) ; Medulloblastoma ; Retinoblastoma ; Pineocytoma (-blastoma)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Previously, immunoreactive rod-opsin and S-antigen (arrestin), two highly characteristic markers of retinal photoreceptors and pinealocytes, were shown to be present in certain medulloblastoma cells. It, thus, has been suggested that such cells differentiate along the photoreceptor lineage. This is corroborated in the present immunocytochemical investigation using antibodies against another photoreceptor-cell marker, the interphotoreceptor retinoid-binding protein (IRBP). As shown in preparations of human retina and pineal organ, IRBP can be successfully demonstrated in formalinfixed and paraffin-embedded tissue: the IRBP immunoreaction is located to the outer and inner segments of retinal photoreceptor cells and to perikarya of certain pinealocytes. Examination of formalin-fixed, paraffinembedded biopsy specimens of 66 cerebellar medulloblastomas revealed varying numbers of IRBP-immunoreactive tumor cells in 19 cases that were formerly shown to contain rod-opsin and S-antigen immunoreaction. IRBP-immunoreactive tumor cells were also found in a retinoblastoma and a pineocytoma, but not in neuroblastoma, ganglioneuroblastoma, glioblastoma, oligodendroglioma and astrocytoma. The results indicate: (1) cerebellar medulloblastomas are heterogeneous in their differentiation potential; (2) one type of medulloblastoma displays photoreceptor characteristics; (3) this type appears to be closely related to retinoblastoma and pineal cell tumors; and (4) all three types of tumors may display additional common features to be explored in future studies.
    Type of Medium: Electronic Resource
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