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| 2. |
- Eskola, Olli, et al.
(författare)
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Tracer Level Electrophilic Synthesis and Pharmacokinetics of the Hypoxia Tracer [F-18]EF5
- 2012
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Ingår i: Molecular Imaging and Biology. - : Springer Science and Business Media LLC. - 1536-1632 .- 1860-2002. ; 14:2, s. 205-212
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Tidskriftsartikel (refereegranskat)abstract
- 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide labeled with [F-18]-fluorine ([F-18]EF5), a promising tracer for tumor hypoxia, has previously been synthesized in low yields and low specific radioactivity. In pharmacokinetic evaluations, in the presence of non-radioactive EF5, a uniform and low background uptake and high in vivo stability of [F-18]EF5 have been demonstrated. Our purpose was to increase the specific radioactivity of [F-18]EF5 to enable to study the pharmacokinetics at trace level. [F-18]EF5 was synthesized using high specific radioactivity electrophilic [F-18]F-2 as labelling reagent. Biodistribution of [F-18]EF5 was determined in a prostate tumor mouse model, and formation of radiolabelled metabolites was studied in mouse, rat and human plasma. On average, 595 +/- 153 MBq of [F-18]EF5 was produced. Specific radioactivity was 6.6 +/- 1.9 GBq/mu mol and the radiochemical purity exceeded 99.0%. [F-18]EF5 was distributed uniformly in tissues, with highest uptake in liver, kidney, and intestine. Several radiolabelled metabolites were detected in mouse plasma and tissues, whereas low amounts of metabolites were detected in human and rat plasma. [F-18]EF5 was synthesized by electrophilic labelling with high quality and high yields. Pharmacokinetics of [F-18]EF5 was determined at trace level in several species. Our results suggest that the trace-level approach does not affect the biodistribution of [F-18]EF5. Extensive metabolism was seen in mouse.
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- Lubberink, Mark, et al.
(författare)
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Validity of Simplified 3′-Deoxy-3′-[18F]Fluorothymidine Uptake Measures for Monitoring Response to Chemotherapy in Locally Advanced Breast Cancer
- 2012
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Ingår i: Molecular Imaging and Biology. - : Springer Science and Business Media LLC. - 1536-1632 .- 1860-2002. ; 14:6, s. 777-782
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Tidskriftsartikel (refereegranskat)abstract
- Purpose:Positron emission tomography using 3′-deoxy-3′-[18F]fluorothymidine ([18F]FLT) has been suggested as a means for monitoring response to chemotherapy. The aim of this study was to evaluate the validity of simplified uptake measures for assessing response to chemotherapy using [18F]FLT in locally advanced breast cancer (LABC).Procedures:Fifteen LABC patients underwent dynamic [18F]FLT scans both prior to and after the first cycle of chemotherapy with fluorouracil, epirubicin or doxorubicin, and cyclophosphamide. The net uptake rate constant of [18F]FLT, K i , determined by non-linear regression (NLR) of an irreversible two-tissue compartment model was used as the gold standard. In addition to Patlak graphical analysis, standardised uptake values (SUV) and tumour-to-whole blood ratio (TBR) were used for analysing [18F]FLT data. Correlations and relationships between simplified uptake measures and NLR before and after chemotherapy were assessed using regression analysis.Results: No significant differences in both pre- and post-chemotherapy relationships between any of the simplified uptake measures and NLR were found. However, changes in SUV between baseline and post-therapy scans showed a significant negative bias and slope less than one, while TBR did not.Conclusions:In LABC, TBR instead of SUV may be preferred for monitoring response to chemotherapy with [18F]FLT.
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- van Assema, Danielle M. E., et al.
(författare)
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P-Glycoprotein Function at the Blood-Brain Barrier : Effects of Age and Gender
- 2012
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Ingår i: Molecular Imaging and Biology. - : Springer Science and Business Media LLC. - 1536-1632 .- 1860-2002. ; 14:6, s. 771-776
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Tidskriftsartikel (refereegranskat)abstract
- PurposeP-glycoprotein (Pgp) is an efflux transporter involved in transport of several compounds across the blood–brain barrier (BBB). Loss of Pgp function with increasing age may be involved in the development of age-related disorders, but this may differ between males and females. Pgp function can be quantified in vivo using (R)-[11C]verapamil and positron emission tomography. The purpose of this study was to assess global and regional effects of both age and gender on BBB Pgp function.ProceduresThirty-five healthy men and women in three different age groups were included. Sixty minutes dynamic (R)-[11C]verapamil scans with metabolite-corrected arterial plasma input curves were acquired. Grey matter time–activity curves were fitted to a validated constrained two-tissue compartment plasma input model, providing the volume of distribution (V T) of (R)-[11C]verapamil as outcome measure.ResultsIncreased V T of (R)-[11C]verapamil with aging was found in several large brain regions in men. Young and elderly women showed comparable V T values. Young women had higher V T compared with young men.ConclusionsDecreased BBB Pgp is found with aging; however, effects of age on BBB Pgp function differ between men and women.
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- Wallberg, Helena, et al.
(författare)
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Evaluation of the Radiocobalt-Labeled [MMA-DOTA-Cys(61)]-Z(HER2:2395)-Cys Affibody Molecule for Targeting of HER2-Expressing Tumors
- 2010
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Ingår i: Molecular Imaging and Biology. - : Springer Science and Business Media LLC. - 1536-1632 .- 1860-2002. ; 12:1, s. 54-62
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Tidskriftsartikel (refereegranskat)abstract
- Imaging using positron emission tomography (PET) in the field of nuclear medicine is becoming increasingly important. The aim of this study was to develop a method for labeling of affibody molecules with radiocobalt for PET applications. The human epidermal growth factor receptors type 2 (HER2) binding affibody molecule DOTA-Z(2395)-C was radiolabeled with (57)Co (used as a surrogate of (55)Co). The binding specificity and cellular processing of the labeled compound was studied in vitro followed by in vivo characterization in normal and tumor-bearing mice. Furthermore, a comparative biodistribution study was performed with a (111)In-labeled counterpart. DOTA-Z(2395)-C was successfully labeled with radiocobalt with nearly quantitative yield. The compound displayed good retention on cells over time and high tumor accumulation of radioactivity in animal studies. Imaging studies showed clear visualization of HER2-positive tumors. Furthermore, the radiocobalt label provided better tumor-to-organ ratios than (111)In. Radiocobalt is a promising label for affibody molecules for future PET applications.
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- Wållberg, Helena, et al.
(författare)
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Evaluation of the Radiocobalt-Labeled [MMA-DOTA-Cys61]-ZHER2:2395-Cys Affibody Molecule for Targeting of HER2-Expressing Tumors
- 2010
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Ingår i: Molecular Imaging and Biology. - : Springer Science and Business Media LLC. - 1536-1632 .- 1860-2002. ; 12:1, s. 54-62
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Imaging using positron emission tomography (PET) in the field of nuclear medicine is becoming increasingly important. The aim of this study was to develop a method for labeling of affibody molecules with radiocobalt for PET applications. PROCEDURES: The human epidermal growth factor receptors type 2 (HER2) binding affibody molecule DOTA-Z(2395)-C was radiolabeled with (57)Co (used as a surrogate of (55)Co). The binding specificity and cellular processing of the labeled compound was studied in vitro followed by in vivo characterization in normal and tumor-bearing mice. Furthermore, a comparative biodistribution study was performed with a (111)In-labeled counterpart. RESULTS: DOTA-Z(2395)-C was successfully labeled with radiocobalt with nearly quantitative yield. The compound displayed good retention on cells over time and high tumor accumulation of radioactivity in animal studies. Imaging studies showed clear visualization of HER2-positive tumors. Furthermore, the radiocobalt label provided better tumor-to-organ ratios than (111)In. CONCLUSIONS: Radiocobalt is a promising label for affibody molecules for future PET applications.
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