| 1. |
- Antoni, Gunnar, et al.
(author)
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Synthesis of l-2,4-Diamino[4-11C]butyric acid and its use in some In vitro and In vivo tumour models
- 1997
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 24:6, s. 595-601
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Journal article (peer-reviewed)abstract
- l-2,4-Diamino[4-11C]butyric acid (DAB) was synthesized by an enzyme catalysed carrier added (0.1 μmol KCN) reaction of hydrogen [11C]cyanide with O-acetyl-l-serine followed by reduction. l-[11C]DAB was obtained with a radiochemical purity higher than 96% and with a decay corrected radiochemical yield of 30–40% within a 32 min reaction time. The enantiomeric excess was 98%. The uptake of l-[11C]DAB was investigated in multicellular aggregates of six different cell lines and animal tumour models. l-[11C]DAB is potentially useful for the assessment of pharmacokinetics of l-DAB in vivo for part of its evaluation as an antitumoural agent, although its use for diagnostic purposes seems limited.
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| 2. |
- Bergström, Mats, et al.
(author)
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Modulation of organ uptake of 11C-labelled L-DOPA
- 1997
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 24, s. 15-
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Journal article (peer-reviewed)abstract
- The present study was undertaken to investigate if pretreatment with pharmacological agents could change the organ uptake of 11C-labelled L-DOPA, and especially if the urinary excretion could be decreased. L-[beta-11C]DOPA was injected IV into unanesthetized Sprague-Dawley rats. After 20 min the rats were decapitated and organs taken out for radioactivity measurements. The uptake in the organs was investigated in animals only given the tracer, and in animals pretreated with drugs such as decarboxylase inhibitors carbidopa and benserazide as well as the monoamine oxidase inhibitors deprenyl, clorgyline, and the COMT inhibitor OR-486. A marked decrease in the urinary radioactivity was observed after carbidopa and benserazide administration. HPLC analysis revealed that under native conditions the major part of urinary radioactivity existed as dopamine, which was eliminated by the decarboxylase inhibitors. After pretreatment with the COMT inhibitor OR-486, the radioactivity uptake in the pancreas increased fourfold as compared to non-treated animals. HPLC analysis showed that this correlated with a marked increase in radiolabelled DOPAC. In the other organs and with the other drugs, only small effects were observed. With L-[beta-11C]fluoroDOPA as a tracer, similar results were observed although the increase in the pancreas by OR-486 had a lower magnitude. These studies suggest that it might be possible to improve the diagnostic ratio of L-[beta-11C]DOPA or L-[18F]fluoroDOPA in whole-body PET studies by pretreating the patient with decarboxylase inhibitor for reducing the urinary excretion and potentially increase the target organ uptake by COMT inhibition.
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| 3. |
- Forngren, B H, et al.
(author)
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Determination of specific radioactivity for Br-76-labeled compounds measuring the ratio between Br-76 and Br-79 using packed capillary liquid chromatography mass spectrometry
- 2000
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 27:8, s. 851-853
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Journal article (peer-reviewed)abstract
- Packed capillary liquid chromatography with electrospray mass spectrometry was used for direct determination of the specific radioactivity by calculation of isotope ratios between the Br-76- and Br-76-labeled analogues of N-((3 aminomethyl)benzyl) 4-bromobenzamide. Using 20 muL injections on packed capillary columns, sufficient mass sensitivity was attained for the determination on an injected amount of radioactivity corresponding to approximately 2 MBq (0.3 pmol of the Br-76 isotopic analogue). NUCL MED BIOL 27;6:851-853, 2000. (C) 2000 Elsevier Science Inc. All rights reserved.
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| 4. |
- Höglund, Johanna, et al.
(author)
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Optimized indirect (76)Br-bromination of antibodies using N-succinimidyl para-[76Br]bromobenzoate for radioimmuno PET
- 2000
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 27:8, s. 837-43
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Journal article (peer-reviewed)abstract
- Monoclonal antibody 38S1 was radiobrominated with the positron emitter (76)Br (T(1/2) = 16.2 h). Indirect labeling was performed using N-succinimidyl para-(tri-methylstannyl)benzoate (SPMB) as the precursor molecule. SPMB was labeled using Chloramine-T yielding N-succinimidyl para-[(76)Br]bromobenzoate, which was then conjugated to the antibody. Optimization of the labeling conditions and further conjugation gave a total yield ( mean+/-max error) of 49+/-2%. The immunoreactivity of the antibodies was retained after labeling. Thus, antibodies intended for positron emission tomography can be labeled with (76)Br, which gives high yields and preserved immunoreactivity when using the SPMB technique described.
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| 5. |
- Kälkner, Karl-Mikael, et al.
(author)
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Positron emission tomography (PET) with 11C-5-hydroxytryptophan (5-HTP) in patients with metastatic hormone-refractory prostatic adenocarcinoma
- 1997
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 24:4, s. 319-325
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Journal article (peer-reviewed)abstract
- The discovery of neuroendocrine differentiation in hormone-refractory prostatic adenocarcinoma has opened a potentially new therapeutic approach in this group of patients with a poor prognosis and few effective therapy modalities. Based on previous findings of increased uptake of 11C-5-hydroxytryptophan (11C-5-HTP) in neuroendocrine tumours using the PET technique, this tracer was applied in the study of 10 patients with metastatic hormone-refractory prostatic adenocarcinoma. In three patients, the study was repeated after treatment. An increased uptake of 11C-5-HTP was observed in all investigated skeletal lesions, although the magnitude of the uptake was moderate. The difference between the standard uptake values (SUV) in normal bone and metastatic lesions was significant (p < 0.001). A kinetic analysis of the uptake of 11C-5-HTP demonstrates an increase during the first minutes followed by a wash-out and a stabilization of the tissue/blood ratio at about 2. The Patlak plots demonstrated a gradual increase in the transport rate during the first 20 to 30 min, after which a constant level was observed. The SUV varied between patients and between lesions over time and treatment. The uptake of 11C-5-HTP discriminates metastatic lesions from normal bone and may thus aid in the diagnosis and, potentially, in treatment monitoring of metastatic hormone-refractory prostatic adenocarcinoma. Uptake kinetics are characterized by a wash-out and cannot alone be used as proof of neuroendocrine differentiation in hormone-refractory prostatic adenocarcinoma.
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| 6. |
- Lövqvist, Anna, et al.
(author)
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76Br-labeled monoclonal anti-CEA antibodies for radioimmuno positron emission tomography
- 1995
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 22:1, s. 125-131
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Journal article (peer-reviewed)abstract
- For the application of anti-tumor monoclonal antibodies (MAbs) in positron emission tomography (PET), labeling radionuclides with half-lives allowing a suitable time frame for imaging are required. The anti-CEA MAb 38S1 was labeled with the positron emitting nuclide 76Br (t1/2 16 h) using bromoperoxidase (BPO), and subsequently affinity purified. A procedure was devised to allow reproducible production of MAb-preparations of high immunoreactivity and with acceptable bromination yield. The biological activity of 76Br-38S1 was retained and comparable to that of chloramine-T labeled 125I-38S1, as tested in vitro.
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| 7. |
- Mårs, Ulla, et al.
(author)
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Positron emission tomography of experimental melanoma with [76Br]5-bromo-2-thiouracil
- 2000
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 27:8, s. 845-9
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Journal article (peer-reviewed)abstract
- Positron emission tomography (PET) has evolved as a new diagnostic modality in cancer patients. Thioureylenes, such as thiouracil and methimazole, are known to be incorporated into growing melanin and selectively retained in melanotic melanoma. In the present study we used [(76)Br]5-bromo-2-thiouracil as tracer for PET imaging of human and murine melanotic melanoma transplanted subcutaneously into rats. The melanomas were clearly depicted 1 day after the injection, when [(76)Br]5-bromo-2-thiouracil was retained in the tumors though the overall radioactivity concentration in the body had declined. Accumulation of (76)Br was also seen in bladder, liver, and kidney. In addition, the rats were simultaneously injected with [(125)I]5-iodo-2-thiouracil and the tissue distribution of radioactivity was mapped by whole-body autoradiography. The results confirmed the selective uptake of thiouracil in the melanoma where the concentration of (125)I-radioactivity was about three-fold higher than that in the liver and lungs. These results show the possibility of using [(76)Br]5-bromo-2-thiouracil for PET diagnostics of melanoma, including dosimetry, prior to targeted therapy using [(131)I]5-iodo-2-thiouracil or [(211)At]5-astato-2-thiouracil.
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| 8. |
- Orlova, Anna, et al.
(author)
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Cellular processing of (125)I- and (111)in-labeled epidermal growth factor(EGF) bound to cultured A431 tumor cells
- 2000
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 27:8, s. 827-35
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Journal article (peer-reviewed)abstract
- Low molecular weight of epidermal growth factor (EGF) enables better intratumoral penetration in comparison with larger targeting proteins, but the cellular retention of EGF-associated radioactivity is poor for directly iodinated EGF. An attempt was made to improve intracellular retention by the use of metal-diethylenetriaminepentaacetic acid or nonphenolic linker (N-succinimidyl-para-iodobenzoate) as labeling agents. The use of nonphenolic linker did not improve retention of the radioactivity in A431 carcinoma cell line. The use of the radiometal label provided an appreciable prolongation of radioactivity residence inside the cell.
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| 9. |
- Orlova, Anna, et al.
(author)
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Cellular processing of 125I- and 111in-labeled epidermal growth factor (EGF) bound to cultured A431 tumor cells
- 2000
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In: Nuclear Medicine and Biology. - 0969-8051 .- 1872-9614. ; 27:8, s. 827-835
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Review (other academic/artistic)abstract
- Low molecular weight of epidermal growth factor (EGF) enables better intratumoral penetration in comparison with larger targeting proteins, but the cellular retention of EGF-associated radioactivity is poor for directly iodinated EGF. An attempt was made to improve intracellular retention by the use of metal-diethylenetriaminepentaacetic acid or nonphenolic linker (N-succinimidyl-para-iodobenzoate) as labeling agents. The use of nonphenolic linker did not improve retention of the radioactivity in A431 carcinoma cell line. The use of the radiometal label provided an appreciable prolongation of radioactivity residence inside the cell.
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| 10. |
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