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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 76 (1988), S. 204-207 
    ISSN: 1432-0533
    Keywords: S-Antigen ; Monoclonal antibodies ; Cerebellar medulloblastoma ; Photoreceptor cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A series of 16 cerebellar medulloblastomas were studied immunohistochemically using a four-step immunoperoxidase (PAP) method and a monoclonal antibody (MAbA9-C6) which defines an epitope of the retinal S-antigen, a protein known to occur in retinal photoreceptor cells and pinealocytes of the pineal gland as well as in retinoblastomas, pineocytomas and pineoblastomas. Immunopositivity was demonstrated in a variable number of tumor cells in 50% of the cases. This finding may be an indication of a differentiation potential of medulloblastomas along the photoreceptor cell lineage. Alternatively, it may simply indicate the non-specificity of the retinal antigen in the neoplastic state.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Choroid plexus papilloma ; Oncocytes ; Intermediate filaments ; Glial fibrillary acidic protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The histiopathological features of a choroid plexus papilloma in a 27-year-old male are described. The tumor displayed marked oncocytic transformation and glial differentiation of the epithelium in areas in which there was also marked sclerosis of the fibrovascular cores. Non-membrane-bound bodies of intermediate filaments characterized ultrastructurally the cells with glial differentiation.
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  • 3
    ISSN: 1432-0533
    Keywords: Subependymal giant cell astrocytoma ; GFA protein ; NF protein ; Neuron-specific enolase ; Immunoperoxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-two cases of subependymal giant cell astrocytoma (SGCA), five of which associated with tuberous sclerosis, were reviewed by conventional neurohistological stains and by peroxidase-antiperoxidase (PAP) immunohistochemistry for glial fibrillary acidic (GFA) protein, the 68 Kd neurofilament subunit (68 Kd-NF), and neuron-specific enolase (NSE). Neurohistological stains confirmed the presence of PTAH-positive fibrils and the absence of Nissl bodies and of neurites originating from the tumor cells. GFA protein-positive cells were present in all tumors not associated with tuberous sclerosis. However, the number of positive cells in each tumor was highly variable. GFA protein-positive cells were rare in the two SGCA accompanying tuberous sclerosis and absent in the remaining three. Neurohistological stains showed no differences between GFA protein-positive and negative cells. 68 Kd-NF-positive cells were found in six tumors. In one tumor, associated with tuberous sclerosis, it was present in the large ganglion-like cells only. NSE-positive cells were found in 13 of 18 tumors examined, including four of the five SGCA associated with tuberous sclerosis. The significance of NSE-positivity in central neuroepithelial neoplasms in respect of their possible neuronal origin remains open. This study suggests that the SGCA, especially those associated with tuberous sclerosis, include cells that are apparently unable to express GFA protein. Some of the tumor cells express the 68 Kd-NF, but this expression falls short of the complete expression of neuronal differentiation. The unique morphological appearances of the SGCA and the discrepancies reported in electron-microscopic and immunohistochemical studies suggest that the cell of origin of these tumors is the product of a dysgenetic event in early development. As a result, the potential of that cell for astrocytic or neuronal differentiation may be incompletely or aberrantly expressed, in particular when the stigmata of tuberous sclerosis are also present. No evidence of obvious ganglionic differentiation and no inference of a neuronal origin of the tumor cells in SGCA could be adduced from the present histochemical findings. This study supports the general interpretation of these tumors as a variant of astrocytoma.
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  • 4
    ISSN: 0014-5793
    Keywords: Alternative splicing ; Intron ; Polymerase chain reaction
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1570-7458
    Keywords: Homoptera ; Aphididae ; Acyrthosiphon pisum ; Medicago sativa ; resistance ; amino acids ; sucrose ; phloem sap ; artificial diet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé L'analyse (sucres et acides aminés) de la sève de 4 cultivars de luzerne (Medicago sativa) caractérisés pour leur résistance au puceron du pois (Acyrthosiphon pisum (Harris)) (Homoptera: Aphididae), est réalisée sur des exsudats de phloème. La teneur en sucres (exprimée en équivalent saccharose) montre d'importantes différences: rapport de 1 à 3 respectivement entre les clones sensible et résistant. La teneur globale en acides aminés exsudés varie en sens inverse, entraînant une corrélation négative pour les 4 clones étudiés entre le rapport sucre/acides aminés (0,6 à 3,6) et la résistance mesurée par le taux net de reproduction à 14 jours (78,5 à 11,2 larves/femelle). L'analyse des acidses aminés révèle de plus des différences qualitatives entre cultivars, notamment pour certains acides aminés essentiels méthionine, histidine, lysine, aromatiques. Le rôle de l'équilibre en acides aminés et en sacharose dans la résistance de certains cultivars au puceron du pois est apprécié par des mesures de la reproduction de A. pisum sur des milieux artificiels reproduisant le rapport sucre/acides aminés et/ou le spectre des acides aminés des 2 clones extrêmes (sensible et résistant). La résistance n'apparaît pas être le résultat d'une simple différence de la qualité nutritionnelle de la sève; la balance en acides aminés doit cependant participer pour une part à la résistance au puceron.
    Notes: Abstract Sugars and amino acids were analysed in the phloem sap (sampling by the exudation method) of four clones of lucerne (Medicago sativa L.) characterized by their resistance to the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae). Differences in the qualitative amino acid balance are shown and a negative correlation between the reproductive rate of the aphid and the sugars/amino acids ratio is underlined. To demonstrate any causal relationship between these two variables, the reproduction of A. pisum on artificial diets copying the sap of the two extreme clones (resistant and susceptible) was measured. The results show that the resistance is not a simple nutritional effect; however, the amino acid balance contributes to the resistance exhibited by some cultivars.
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