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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 35 (1980), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The role of asparagine as precursor for the neurotransmitter aspartate was investigated in rat striatum in vitro.14C-asparagine incubated with striatal slices is converted to a great extent to 14C-aspartate which is released in a calcium-dependent manner by high KCl. Furthermore, a frontoparietal cortex ablation of two weeks produces a decrease of more than 70% in the striatal release of newly synthetized 14C-aspartate, whereas the striatal GABA release is unaffected. This suggests that asparagine is a possible pre-cursor in vitro for transmitter aspartate in the striatum. This reaction is dependent on intact corticostriatal fibres.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 733 (1994), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 38 (1980), S. 437-441 
    ISSN: 1432-1106
    Keywords: Glutamate, aspartate, GABA ; In vitro release ; Cochlear nerve lesion ; Cochlear nucleus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pool studies of glutamate and aspartate have suggested a transmitter role for these amino acids in cochlear nerve endings. As further evidence. the K+-evoked release of glutamate, aspartate and GABA was measured in cat cochlear nucleus slices in vitro and compared to the release following a cochlear nerve lesion. Using [3H]glutamine as precursor, the K+-evoked release of glutamate and γ-aminobutyric acid (GABA) was respectively 4.1 and 7.2 times the spontaneous release. Using [14C]glutamate as a marker, the K+-evoked release of glutamate and GABA was respectively 7.1 and 2.8 times the basal release. All K+-evoked releases were Ca++-dependent. Nine days after unilateral lesion of the cochlear nerve in the cat, the glutamate release decreased by about 75% on the lesioned side compared to the intact one, whereas the GABA release was not decreased. The labelled tissue glutamate, either synthesized from [3H]glutamine or labelled with [14C]glutamate, was also markedly decreased on the lesioned side. In comparison, the evoked release of aspartate, newly synthesized from [14C]glutamate, remained low and was only decreased by about 45% after cochlear nerve lesions. Comparing cat with rat cochlear nucleus, the glutamate release was similar in both animals, whereas the GABA release was much higher in the rat. It is concluded that glutamate and to a lesser extent aspartate are likely to be released from cochlear nerve terminals, supporting a transmitter role in these nerve fibres for both amino acids.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Les résultats de la localisation de tumeurs insulaires du pancréas par l'administration intraveineuse de deux analogues marqués de la somatostatine, le 123 I-Tyr3-octréotide et le 11 Inoctréotide, ont été analysés chez 25 patients. Les tumeurs primitives et des métastases, souvent méconnues jusqu'alors, ont été visualisées chez 20 des 25 patients (80%). Parallèlement, la détectionin vitro des récepteurs de la somatostatine des tumeurs ainsi visualiséesin vivo sont en faveur d'une liaison à la tumeurin vivo, spécifique des récepteurs en question. La détection de ces récepteursin vivo était un facteur prédictif d'un effet suppressif sur l'hypersécrétion hormonale des tumeurs. Il s'agit d'un moyen d'investigation facile, rapide et sûr de localiser les tumeurs endocrines primitives du pancréas ainsi que leurs métastases, souvent encore cliniquement et radiologiquement muettes.
    Abstract: Resumen Presentamos los resultados de la visualización de tumores insulares en 25 pacientes luego de la administración intravenosa de dos análogos de la somatostatina marcados con radioisótopos (123I-Ty3-octreótido y 111 In-octreótido). Los tumores primarios, así como las metástasis distantes, frecuentemente desapercibidas, fueron visualizados en 20 de 25 pacientes (80%). La detección paralelain vitro de receptores de somatostatina en tales tumores, que tambión habían sido visualizadosin vivo, indica que la ligazónin vivo representa ligazón a receptores específicos de somatostatina. La detección de receptores de somatostatina en estos tumoresin vivo predijo un buen efecto supresor del octreótido sobre su hipersecreción hormonal. El procedimiento es sencillo, rápido, libre de peligro y muy valioso en la localización de los tumores endocrinos primarios del páncreas, así como de sus metástasis, que frecuentemente permanecen ocultas en los exámenes radiológicos y clínicos.
    Notes: Abstract The results of visualization of the islet cell tumors of 25 patients after intravenous administration of two isotope-labeled somatostatin analogs (123I-Tyr3-octreotide and111In-octreotide) are described. The primary tumors, as well as previously often unrecognized distant metastases were visualized in 20 of the 25 patients (80%). Parallel in vitro detection of somatostatin receptors on those tumors that had also been visualized in vivo indicates that the ligand binding to the tumor in vivo indeed represents binding to specific somatostatin receptors. The detection of somatostatin receptors on these tumors in vivo predicted a good suppressive effect of octreotide on hormonal hypersecretion by these tumors. It is an easy, quick, harmless procedure that is valuable for localization of primary endocrine pancreatic tumors and their often radiologically and clinically not yet recognized metastases.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 282 (1990), S. 139-141 
    ISSN: 1432-069X
    Keywords: Psoriasis ; Skin ; Somatostatin receptors ; Epidermal growth factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-7217
    Keywords: buserelin ; LHRH-agonists ; rat mammary tumor ; sandostatin ; somatostatin analogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of treatment with a somatostatin analog (Sandostatin, SMS201-995) were investigated in female rats with dimethylbenzanthracene(DMBA)-induced rat mammary tumors. A 3-week treatment was performed using sandostatin, the LHRH-agonist buserelin alone, or buserelin in combination with sandostatin. Twice daily sandostatin treatment was performed with dosages of 0.05 µg, 0.2 µg, 1 µg, 5 µg, and 20 µg. Buserelin was used in a 2 × 5 µg/day dosage. The combined results from six different experiments show that the various dosages of sandostatin caused no tumor growth inhibition. Somatostatin receptors could not be demonstrated in these mammary tumors. Sandostatin treatment by daily injections did not suppress levels of growth hormone, prolactin, or epidermal growth factor-like activities. Estrogen (ER) and progesterone (PgR) receptor contents of the mammary tumors were not changed. In contrast, buserelin treatment caused highly significant tumor remission. The combined treatment with sandostatin and buserelin did not alter the treatment results obtained after treatment with buserelin alone. In conclusion, sandostatin treatment in this tumor model had no direct growth inhibitory effect and did not cause an endocrine inhibition of mammary tumor growth. However, these results do not exclude antitumor effects in human breast cancer in view of the presence of somatostatin receptors in approximately 20–45% of human tumors, besides possible different endocrine effects.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1619-7089
    Keywords: Scintigraphy ; Somatostatin ; Sarcoidosis ; Tuberculosis ; Wegener's granulomatosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Normal as well as activated lymphocytes and macrophages have previously been shown by radioreceptor analysis to express somatostatin receptors (SS-R). The somatostatin (SS) analogue [111In-DTPA-d-Phe1]octreotide (111In-octreotide) is already used successfully in the visualization of a variety of neuro-endocrine tumours and malignant lymphomas. In the present study 20 consecutive patients were investigated, 12 with sarcoidosis, one with both sarcoidosis and aspergillosis, four with tuberculosis and three with Wegener's granulomatosis. For in vivo SS-R imaging, total-body scintigraphy was performed 24 and 48 h after the administration of 111In-octreotide. Granuloma localizations could be visualized in all patients studied; additional sites were found in nine patients with sarcoidosis and in two patients with tuberculosis. In vitro autoradiography of fresh tissue biopsies, using the SS analogue [125I-Tyr3]octreotide, showed binding at sites that were microscopically identified as granulomatous inflammation. These observations demonstrate the expression of SS-R by human granulomas. This scintigraphy procedure may contribute to a more precise staging and evaluation of granulomatous diseases, but more importantly it may be a sensitive indicator of the efficacy of glucocorticoid and/or immunosuppressive therapy.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1619-7089
    Keywords: Somatostatin ; Octreotide ; Tumour targeting ; Receptor imaging ; Apudoma ; Lymphoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Various tumours, classically specified as either neuroendocrine or non-neuroendocrine, contain high numbers of somatostatin receptors, which enable in vivo localization of the primary tumour and its metastases by scintigraphy with the radiolabelled somatostatin analogue octreotide. In addition granulomas and autoimmune processes can be visualized because of local accumulation of somatostatin receptor-positive activated mononuclear leucocytes. In many instances a positive scintigram predicts a favourable response to treatment with octreotide. It is tempting to speculate that octreotide labelled with an appropriate radionuclide might be used in cancer therapy. The successful application of radiolabelled octreotide in scintigraphy indicates the possible usefulness of other radiolabelled peptides, either native peptides or derivatives of these, in, for example, nuclear oncology. The small size of these peptides, e.g. bombesin and substance P, is of the utmost importance for a relatively fast blood clearance, thus leading to low background radioactivity. In this way peptides are powerful alternatives to (fragments of) monoclonal antibodies, the application of which to scintigraphic localization of specific cell surface antigen-bearing tumours is plagued by slow blood clearance and, hence, high background levels.
    Type of Medium: Electronic Resource
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