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  • 1
    ISSN: 1432-2307
    Keywords: Immunohistochemistry ; Pituitary gland ; Pituitary adenomas ; Cytokeratins ; Intermediate filaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ten non-neoplastic pituitary glands and 22 pituitary adenomas producing different hormones were studied by immunofluorescence microscopy as well as peroxidase-antiperoxidase and biotin-avidin techniques on frozen sections and formalin-fixed, paraffin-embedded material using antibodies to cytokeratin, vimentin, GFAP, neurofilament protein and different pituitary hormones. The endocrine cells in non-neoplastic pituitary glands as well as in most pituitary adenomas were cytokeratin-positive. The cytoplasmic cytokeratin distribution patterns of non-neoplastic and tumor cells were similar and typical of the type of hormone produced: GH-producing normal cells showed a paranuclear condensation of cytokeratin-reactive intermediate filaments; this accumulation was even further accentuated in GH-producing adenomas resulting in fibrous bodies (Kovacs and Horvath 1978) decorated by cytokeratin antibodies. Prolactin-producing cells showed a less intense cytoplasmic cytokeratin-specific staining with focal paranuclear accentuation in non-neoplastic as well as in neoplastic glands. ACTH-producing cells in normal pituitary glands as well as in adenomas exhibited a strong and more uniform cytoplasmic cytokeratin staining. The cytokeratin reactivity in glycoprotein hormone-producing cells of non-neoplastic tissue and adenomas was weak. Vimentin and GFAP reactivity was confined to agranular folliculo-stellate cells. The specific and different distribution patterns of cytokeratins in pituitary cells can, therefore, provide an (indirect) indication to the production of a specific hormone if immunocytochemistry fails to demonstrate hormone production.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-072X
    Keywords: Nitrogenase regulation ; Glutamine synthetase ; Ammonia switch-off ; Rhodopseudomonas palustris
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nitrogenase activity in Rhodopseudomonas palustris is subject to a rapid switch-off in response to exogenous ammonia. When cells were grown on limiting nitrogen and eventually became nitrogen deficient, nitrogenase synthesis was fully derepressed but the enzyme was insensitive to ammonia. The transformation of ammonia-sensitive to ammonia-insensitive cells was a slow, but fully reversible process. The switch-off effect in ammonia-sensitive cells paralleled changes in the adenylylation state of glutamine synthetase. Ammonia-insensitive cells, however, showed similar changes in glutamine synthetase activity although nitrogenase activity was unaffected. We conclude that nitrogenase regulation and adenylylation of glutamine synthetase are independent processes, at least under conditions of nitrogen deficiency.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Nitrogen fixation ; Nitrogenase regulation ; Glutamine synthetase ; Methionine suofoximine ; Rhodospirillaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Methionine sulfoximine (MSX), an irreversible inhibitor of glutamine synthetase of Rhodopseudomonas palustris restored nitrogenase activity to cells in which nitrogenase had been completely inhibited by ammonia switch-off. After addition of MSX, there was a lag period before nitrogenase activity was fully restored. During this lag, glutamine synthetase activity progressively decreased, and near the time of its complete inhibition, nitrogenase activity resumed. Nitrogenase switch-off by ammonia thus required active glutamine synthetase. Glutamine itself caused nitrogenase inhibition whose reversal by MSX depended on the relative ratio of MSX to glutamine. Unlike ammonia, glutamine inhibited nitrogenase under conditions where glutamine synthetase activity was absent. This indicates that glutamine is the effector molecule in nitrogenase switch-off, for instance by interacting with the enzymatic system for Fe protein inactivation. The effects of glutamine and MSX were also dependent on the culture age. Possible explanation for this and for the competitive effects are a common binding site within the regulatory apparatus for nitrogenase, or, in part, within a common transport system. Some observations with MSX were extended to Rhodopseudomonas capsulata and agreed with those in R. palustris.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 65 (1984), S. 35-40 
    ISSN: 1432-0533
    Keywords: Immunohistochemistry ; Folliculo-stellate cells ; Pituitary gland ; Pituitary adenoma ; S-100 protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Presence and distribution of S-100 protein (S-100), neuron-specific enolase (NSE), cytokeratin polypeptides, glial fibrillary acidic protein (GFAP), vimentin, actin, lysozyme and pituitary hormones (prolactin, hGH, ACTH, β-FSH, β-LH, β-TSH, alpha subunit) in folliculo-stellate cells (FSC) were studied in seven normal human pituitary glands and 28 pituitary adenomas using peroxidase-antiperoxidase and the avidin-biotin immunohistochemical techniques. Approximately 5% of the cells of the adenohypophysis were agranular, non-hormon-producing FSC most of which showed a conspicuous and strong reaction with S-100 antibodies but some were, in addition, GFAP- and vimentin-positive. In contrast to endocrine cells (EC), FSC were not decorated by antibodies to NSE or cytokeratins. In addition to supportive functions, these cells, due to their close special relationship to EC, seem to have transport and other metabolic functions yet to be elucidated. By their S-100 reactivity and their distribution FSC are comparable to glial cells of the central and schwann and satellite cells of the peripheral nervous system (PNS) as well as to supportive cells in neuroendocrine organs and related tumors (e.g., pheochromocytomas, paragangliomas, carcinoids). With one exception, S-100 reactive FSC were not found in pituitary adenomas. The immunohistochemical demonstration of S-100 protein in pituitary tissue is, therefore, a reliable aid in the discrimination between adenomas and normal pituitary tissue, particularly in small and poorly preserved specimens. In one adenoma FSC were found in addition to ACTH-producing tumor cells. This seems to be an extremely rare event suggesting a combination tumor.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 165-176 
    ISSN: 0739-4462
    Keywords: Lepidoptera ; radioimmunoassay ; enzyme immunoassay ; equilibrium dialysis ; monoclonal antibody ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Numerous studies have demonstrated regulation of specific lepidopteran proteins by pharmacological doses of insect juvenile hormone (JH). In this study, topical application of a 1 pg dose of JH I to fourth stadium larvae of the black (bl) mutant strain of the tobacco hornworm, Manduca sexta, induced a 50% increase in the titer of hemolymph juvenile hormone binding protein (hJHBP). Radioimmunoassay confirmed that JH titers were lower in bl larvae than in wild-type larvae at the time of JH treatment. Enzyme immunoassay analysis of hJHBP titers demonstrated that regulation by JH I was dose-dependent at doses up to 10 pg and that the response was saturated above 100 pg. Western blotting and equilibrium dialysis confirmed these results and demonstrated that hJHBP from bl larvae had the same molecular mass and displayed the same affinity for JH I as hJHBP isolated from wild-type larvae. Time course studies showed that regulation was complex: 1 2 h after JH I treatment, hJHBP titers were twofold lower in treated than in control bl larvae, while 44 h after treatment they were twofold higher. JH I regulation of hJHBP titers in bl larvae was independent of changes in total hemolymph protein. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 30 (1995), S. 295-306 
    ISSN: 0739-4462
    Keywords: radioimmunoassay ; JH I ; JH II ; JH III ; hemolymph ; insect hormone ; Manducasexta sexta ; Hyalophora cecropia ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recent refinements in juvenile hormone radioimmunoassay technology now make this method significantly more sensitive and easier to use. Rabbit poly-clonal antisera against (10R) JH III and racemic JH II have been developed to determine hemolymph hormone titers in the low picogram range. The antisera display minimal cross-reactivity with JH metabolites, JH analogs, and hemolymph lipids. One antiserum recognizes racemic JH I, II, and (10R) III almost equivalently, exhibiting 50% displacement between 100 and 130 pg per tube. Another antiserum is JH II-specific and exhibits 50% displacement at 35 pg per tube. Assay sensitivity has been enhanced by using (10R,11S) [methyl-3H]-JH II of very high specific activity (〉 80 Ci/mmol) generated with Hyalophora cecropia accessory gland S-adenosylmethionine transferase and S-[methyl-3H]-adenosyl-L-methionine. Preparation of biological samples has been simplified with overall recoveries of JH from hemolymph ranging between 60 and 75%. © 1995 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 23 (1993), S. 147-152 
    ISSN: 0739-4462
    Keywords: honey bee ; Apis mellifera ; juvenile hormone ; radioimmunoassay ; hemolymph ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Juvenile hormone from the hemolymph of adult worker honey bees of known age and behavioral status was extracted and analyzed by two different radioimmunoassays in two independent laboratoies. The assays are different in hapten attachment, radiolabeled tracer, and the method by which bound and unbound hormone are separated. Despite these differences in the methods, hormone determinations were in excellent agreement at lower levels (0-50 ng/ml) but diverged as the hormone concentrations increased (〉 50 ng/ml). The relative changes are in good agreement, with a correlation coefficient of 0.97. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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