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Uptake of 14C- and 11C-labeled glutamate, glutamine and aspartate in vitro and in vivo
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
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2000 In: Anticancer Research, no 20, 251-256 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2000. no 20, 251-256 p.
URN: urn:nbn:se:uu:diva-90209OAI: oai:DiVA.org:uu-90209DiVA: diva2:162485
Available from: 2003-04-24 Created: 2003-04-24 Last updated: 2015-09-24Bibliographically approved
In thesis
1. Positron Emission Tomography in the Management of Neuroendocrine Tumors
Open this publication in new window or tab >>Positron Emission Tomography in the Management of Neuroendocrine Tumors
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Neuroendocrine tumors (NET´s) are often characterized by overproduction of peptide hormones. In spite of pronounced clinical symptoms, the tumor lesions can be small and difficult to detect. The general aim of this thesis was to investigate, in vitro and in vivo, some of the potential monoamine pathways present in NET´s, using radiolabeled tracers for positron emission tomography (PET), with the intention to explore the value of PET-imaging in the management of NET´s.

We used the 11C-labeled serotonin precursor 5-hydroxy tryptophan (HTP) as the tracer for imaging of NET´s. More than 95% of the subjects displayed a high tracer uptake on PET and tumor detection rate with PET was higher in >50% of the patients compared both to computed tomography (CT) and somatostatin receptor scintigraphy (SRS). The primary tumor was imaged by PET in 84% (16/19), compared to 47% and 42% for SRS and CT, respectively. Tumor visibility was better with PET due to a higher tumor-to-background ratio and a better spatial resolution. There was a strong correlation (r = .907) between changes in urinary-5-hydroxy indole acetic acid and changes in transport rate of 11C-5-HTP during treatment, indicating the use of PET in treatment monitoring of NET´s.

Pretreatment with carbidopa decreased the urinary radioactivity concentration four-fold and significantly (p<0.001) increased the tumor tracer uptake. This greatly improved image interpretation and tumor lesion detection.

A screening for expression of monoamine pathways in NET´s revealed a high in vitro binding of the monoamineoxidase-A ligand harmine to tumor sections. PET examinations with 11C-harmine could visualize tumors in all patients, including non-functioning endocrine pancreatic tumors (EPT´s).

Finally, the in vitro turnover and in vivo distribution of the amino acids glutamate, glutamine and aspartate was investigated. Limited uptake in vivo indicates the lack of utility for these substances as PET-tracers for imaging and characterization of NET´s.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 77 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1233
Medicine, Neuroendocrine tumor (NET), carcinoid, endocrine pancreatic tumor (EPT), Positron Emission Tomography (PET), serotonin-precursor, 5-hydroxytrytophan (5-HTP), Medicin
National Category
Dermatology and Venereal Diseases
Research subject
urn:nbn:se:uu:diva-3356 (URN)91-554-5561-1 (ISBN)
Public defence
2003-05-16, Roberg salen, Ingång 40, 4tr, Uppsala, 13:15
Available from: 2003-04-24 Created: 2003-04-24 Last updated: 2011-04-14Bibliographically approved

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Antoni, Gunnar
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