| 1. |
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| 2. |
- Antoni, Gunnar, et al.
(author)
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In Vivo Visualization of Amyloid Deposits in the Heart with C-11-PIB and PET
- 2013
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In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 54:2, s. 213-220
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Journal article (peer-reviewed)abstract
- Cardiac amyloidosis is a differential diagnosis in heart failure and is associated with high mortality. There is currently no noninvasive imaging test available for specific diagnosis. N-[methyl-C-11]2-(4'-methylamino-phenyl)-6-hydroxybenzothiazole (C-11-PIB) PET is used in the evaluation of brain amyloidosis. We evaluated the potential use of C-11-PIB PET in systemic amyloidosis affecting the heart. Methods: Patients (n = 10) diagnosed with systemic amyloidosis-including heart involvement of either monoclonal immunoglobulin light-chain (AL) or transthyretin (ATTR) type- and healthy volunteers (n = 5) were investigated with PET/CT using C-11-PIB to study cardiac amyloid deposits and with C-11-acetate to measure myocardial blood flow to study the impact of global and regional perfusion on PIB retention. Results: Myocardial C-11-PIB uptake was visually evident in all patients 15-25 min after injection and was not seen in any volunteer. A significant difference in C-11-PIB retention in the heart between patients and healthy controls was found. The data indicate that myocardial amyloid deposits in patients diagnosed with systemic amyloidosis could be visualized with C-11-PIB. No correlation between C-11-PIB retention index and myocardial blood flow as measured with C-11-acetate was found on the global level, whereas a positive correlation on the segmental level was seen in a single patient. Conclusion: C-11-PIB and PET could be a method to study systemic amyloidosis of type AL and ATTR affecting the heart and should be investigated further both as a diagnostic tool and as a noninvasive method for treatment follow-up.
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| 3. |
- Bergman, Sara, et al.
(author)
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Synthesis and Labelling of a Piperazine-Based Library of 11C-Labeled Ligands for Imaging of the Vesicular Acetylcholine Transporter
- 2014
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In: Journal of labelled compounds & radiopharmaceuticals. - : Wiley. - 0362-4803 .- 1099-1344. ; 57:8, s. 525-532
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Journal article (peer-reviewed)abstract
- The cholinergic system is involved in neurodegenerative diseases, and visualization of cholinergic innervations with positron emission tomography (PET) would be a useful tool in understanding these diseases. A ligand for the vesicular acetylcholine transporter (VAChT), acknowledged as a marker for cholinergic neurons, could serve as such a PET tracer. The aim was to find a VAChT PET tracer using a library concept to create a small but diverse library of labeled compounds. From the same precursor and commercially available aryl iodides 6a-f, six potential VAChT PET tracers, [C-11]-(+/-)5a-f, were C-11-labeled by a palladium (0)-mediated aminocarbonylation, utilizing a standard protocol. The labeled compounds [C-11]-(+/-)5a-f were obtained in radiochemical purities >95% with decay-corrected radiochemical yields and specific radioactivities between 4-25% and 124-597 GBq/mu mol, respectively. Autoradiography studies were then conducted to assess the compounds binding selectivity for VAChT. Labeled compounds [C-11]-(+/-)5d and [C-11]-(+/-)5e showed specific binding but not enough to permit further preclinical studies. To conclude, a general method for a facile synthesis and labeling of a small piperazine-based library of potential PET tracers for imaging of VAChT was shown, and in upcoming work, another scaffold will be explored using this approach.
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| 4. |
- Bernal, Ximena E., et al.
(author)
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Empowering Latina scientists
- 2019
-
In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Journal article (other academic/artistic)
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| 5. |
- Blom, Elisabeth, et al.
(author)
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68Ga-Labeling of RGD peptides and biodistribution
- 2012
-
In: International Journal of Clinical and Experimental Medicine. - 1940-5901. ; 5:2, s. 165-172
-
Journal article (peer-reviewed)abstract
- Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labeled with 68Ga for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labeling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2',2'',2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid (DOTA) chelator were labeled at 90 ± 5°C using conventional or microwave heating reaching 90% of 68Ga incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 μM. The compound having 2,2',2''-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labeled at room temperature within 5 min using 2.5 μM peptide precursor. Two of the compounds contained a poly (ethylene glycol) (PEG) linker to the chelator. The biodistribution of the analogues was studied in male rats.
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| 6. |
- Blom, Elisabeth, et al.
(author)
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Ga-68-Labeling of RGD peptides and biodistribution
- 2012
-
In: International Journal of Clinical and Experimental Medicine. - 1940-5901. ; 5:2, s. 165-172
-
Journal article (peer-reviewed)abstract
- Several peptides comprising Arg-Gly-Asp (RGD) domain and macrocyclic chelator were labeled with Ga-68 for the imaging of angiogenesis. The analogues varied in peptide constitution, linker and chelator type. The labeling efficiency did not vary with the peptide constitution and linker type, but depended on the chelator type. Four of the compounds containing 2,2', 2 '', 2'''-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl) tetraacetic acid (DOTA) chelator were labeled at 90 +/- 5 degrees C using conventional or microwave heating reaching 90% of Ga-68 incorporation after 5 and 2 min respectively, when the concentration of the precursor was 2.5 mu M. The compound having 2,2', 2 ''-(1,4,7-triazonane1,4,7-triyl)triacetic acid (NOTA) as the chelator could be labeled at room temperature within 5 min using 2.5 mu M peptide precursor. Two of the compounds contained a poly (ethylene glycol) (PEG) linker to the chelator. The biodistribution of the analogues was studied in male rats.
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| 7. |
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| 8. |
- Cheung, Pierre, et al.
(author)
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PET Imaging of GPR44 by Antagonist [C-11]MK-7246 in Pigs
- 2021
-
In: Biomedicines. - : MDPI. - 2227-9059. ; 9:4
-
Journal article (peer-reviewed)abstract
- A validated imaging marker for beta-cell mass would improve understanding of diabetes etiology and enable new strategies in therapy development. We previously identified the membrane-spanning protein GPR44 as highly expressed and specific to the beta cells of the pancreas. The selective GPR44 antagonist MK-7246 was radiolabeled with carbon-11 and the resulting positron-emission tomography (PET) tracer [C-11]MK-7246 was evaluated in a pig model and in vitro cell lines. The [C-11]MK-7246 compound demonstrated mainly hepatobiliary excretion with a clearly defined pancreas, no spillover from adjacent tissues, and pancreatic binding similar in magnitude to the previously evaluated GPR44 radioligand [C-11]AZ12204657. The binding could be blocked by preadministration of nonradioactive MK-7246, indicating a receptor-binding mechanism. [C-11]MK-7246 showed strong potential as a PET ligand candidate for visualization of beta-cell mass (BCM) and clinical translation of this methodology is ongoing.
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| 9. |
- Christensen, Lars, et al.
(author)
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Five theorems on Gorenstein global dimensions
- 2023
-
In: Algebra and Coding Theory- Virtual Conference in Honor of Tariq Rizvi Noncommutative Rings and their Applications VII, 2021 and Virtual Conference on Quadratic Forms, Rings and Codes, 2021. - : American Mathematical Society (AMS). - 9781470468590 ; , s. 67-78
-
Conference paper (peer-reviewed)abstract
- We expand on two existing characterizations of rings of Gorenstein (weak) global dimension zero and give two new characterizations of rings of finite Gorenstein (weak) global dimension. We also include the answer to a question of Y. Xiang on Gorenstein weak global dimension of group rings.
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| 10. |
- Christensen, Lars Winther, et al.
(author)
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A refinement of Gorenstein flat dimension via the flat–cotorsion theory
- 2021
-
In: Journal of Algebra. - : Elsevier BV. - 0021-8693 .- 1090-266X. ; 567, s. 346-370
-
Journal article (peer-reviewed)abstract
- We introduce a refinement of the Gorenstein flat dimension for complexes over an associative ring—the Gorenstein flat- cotorsion dimension—and prove that it, unlike the Gorenstein flat dimension, behaves as one expects of a homological di- mension without extra assumptions on the ring. Crucially, we show that it coincides with the Gorenstein flat dimension for complexes where the latter is finite, and for complexes over right coherent rings—the setting where the Gorenstein flat dimension is known to behave as expected.
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| 11. |
- Christensen, Lars Winther, et al.
(author)
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Gorenstein weak global dimension is symmetric
- 2021
-
In: Mathematische Nachrichten. - : Wiley. - 0025-584X .- 1522-2616. ; 294:11, s. 2121-2128
-
Journal article (peer-reviewed)abstract
- We study the Gorenstein weak global dimension of associative rings and its relation to the Gorenstein global dimension. In particular, we prove the conjecture that the Gorenstein weak global dimension is a left-right symmetric invariant – just like the (absolute) weak global dimension.
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| 12. |
- Christensen, Lars Winther, et al.
(author)
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The Singularity Category Of An Exact Category Applied To Characterize Gorenstein Schemes
- 2023
-
In: Quarterly Journal of Mathematics. - : Oxford University Press (OUP). - 0033-5606 .- 1464-3847. ; 74:1, s. 1-27
-
Journal article (peer-reviewed)abstract
- We construct a non-affine analogue of the singularity category of a Gorenstein local ring. With this, Buchweitz’s classic equivalence of three triangulated categories over a Gorenstein local ring has been generalized to schemes, a project started by Murfet and Salarian more than ten years ago. Our construction originates in a framework we develop for singularity categories of exact categories. As an application of this framework in the non-commutative setting, we characterize rings of finite finitistic dimension.
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| 13. |
- Christensen, Lars Winther, et al.
(author)
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The stable category of Gorenstein flat sheaves on a noetherian scheme
- 2020
-
In: Proceedings of the American Mathematical Society. - : American Mathematical Society (AMS). - 0002-9939 .- 1088-6826. ; 149:2, s. 525-538
-
Journal article (peer-reviewed)abstract
- For a semiseparated noetherian scheme, we show that the cate- gory of cotorsion Gorenstein flat quasi-coherent sheaves is Frobenius and a natural non-affine analogue of the category of Gorenstein projective modules over a noetherian ring. We show that this coheres perfectly with the work of Murfet and Salarian that identifies the pure derived category of F-totally acy- clic complexes of flat quasi-coherent sheaves as the natural non-affine analogue of the homotopy category of totally acyclic complexes of projective modules.
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| 14. |
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| 15. |
- Díaz-Sánchez, Adrian A., et al.
(author)
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Molecular detection and identification of tick-borne pathogens in Equus caballus and ticks from western Cuba : [Detección e identificación molecular de patógenos transmitidos por garrapatas en Equus caballus y garrapatas del occidente de Cuba]
- 2022
-
In: Biotecnologia Aplicada. - : Elfos Scientiae. - 0864-4551 .- 1027-2852. ; 39:2, s. 2501-2505
-
Journal article (peer-reviewed)abstract
- Babesia caballi, Theileria equi and several species of rickettsias are agents of vector-borne diseases that affect equines. The objective of this study was to detect infections by B. caballi and T. equi in horses and to identify rickettsias in horses and ticks in the western region of Cuba. Two nPCR assays were developed and standardized for the detection of B. caballi and T. equi. Blood samples from horses and ticks were collected. Identification by blood smear and molecular detection and identification of B. caballi, T. equi and Rickettsia spp. were carried out. Intraerythrocytic formations compatible with B. caballi and T. equi were observed. The nPCR showed that 25 % of the samples were positive for B. caballi, 73 % for T. equi and 20 % showed coinfection. The results were confirmed with the partial sequencing of the genes bc48 (B. caballi) and ema-1 (T. equi). The sequencing of the 18S rRNA gene of T. equi demonstrated the presence of at least two genotypes of T. equi isolates in Cuba. The real time qPCR assay and sequencing revealed the presence of Rickettsia amblyommatis in A. mixtum and Rickettsia felis in D. nitens.Conclusions: These results constitute the first piece of molecular evidence of B. caballi and T. equi in horses and the first report of R. felis in D. nitens in Cuba, which broadens the knowledge about the distribution of pathogens and the spectrum of potential vectors contributing to the strengthening of management and control programs.
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| 16. |
- Eich, Torsten, et al.
(author)
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Positron emission tomography : A real-time tool to quantify early islet engraftment in a preclinical large animal model
- 2007
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In: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337 .- 1534-6080. ; 84:7, s. 893-898
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Journal article (peer-reviewed)abstract
- Background. Clinical islet transplantation is currently being explored as a therapeutic option for persons with type I diabetes and hypoglycemic unawareness. Techniques to monitor graft survival are urgently needed to optimize the procedure. Therefore, the objective of the present study was to develop a technique for imaging survival of transplanted islets in the peritransplant and early posttransplant phase.Methods. Isolated porcine islets were labeled in vitro with 2-deoxy-2[18F]fluoro-D-glucose ([18F]FDG) and infused intraportally into anesthetized pigs (n=10). Dynamic examination was performed on a positron emission tomography/computed tomography hybrid system.Results. More than 95% of the radioactivity was confined to the islets at the time of transplantation. The peak percentage of infused radioactivity within the liver, quantified at the end of the islet infusion, was only 54±5.1%. The distribution of the radioactivity in the liver was found to be heterogeneous. A whole-body examination showed no accumulation in the lungs or brain; extrahepatic radioactivity was, except urinary excretion, evenly distributed in the pig body.Conclusions. Our results imply that almost 50% of the islets were damaged to the extent that the FDG contained was release within minutes after intraportal transplantation. The distribution of radioactivity without accumulation in the brain indicates that the activity is released from lysed islet cells in the form of [18F]FDG-6P rather than native [18F]FDG. The presented technique shows promise to become a powerful and quantitative tool, readily available in the clinic, to evaluate initial islet engraftment and survival.
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| 17. |
- Eriksson, Olof, et al.
(author)
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5-Fluoro-[beta-C-11]-L-tryptophan is a functional analogue of 5-hydroxy-[beta-C-11]-L-tryptophan in vitro but not in vivo
- 2013
-
In: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 40:4, s. 567-575
-
Journal article (peer-reviewed)abstract
- INTRODUCTION: 5-Hydroxy-[β-(11)C]-L-tryptophan ([(11)C]HTP) is an established positron emission tomography (PET) imaging agent for neuroendocrine tumors (NETs). It has also been used for other clinical research purposes in neurology and diabetes. However, its widespread use is limited by the short physical half-life of the radionuclide and a difficult radiosynthesis. Therefore, a Fluorine-18 labeled analogue, 5-[(18)F]Fluoro-L-tryptophan ([(18)F]FTRP), has been proposed as a functional analogue. There is no published method for the synthesis of L-[(18)F]FTRP. We have therefore developed a synthesis of 5-fluoro-[β-(11)C]-L-tryptophan ([(11)C]FTRP), based on the existing chemo-enzymatic method for [(11)C]HTP and evaluated the potential usefulness of radiolabeled FTRP as a substitute for [(11)C]HTP.METHODS: The in vitro and in vivo behavior of [(11)C]FTRP, including the dependence of key enzymes in the serotonergic metabolic pathway, was investigated in NET cell lines, NET xenograft carrying immunodeficient mice, normal rats and in non-human primate. [(11)C]HTP was used for direct comparison.RESULTS: Uptake of [(11)C]FTRP in NET cell lines in vitro was mediated by enzymes involved in serotonin synthesis and metabolism, similar to [(11)C]HTP. In vivo biodistribution, either in rodent or non-human primate, was not affected by selectively inhibiting enzymatic steps in the serotonergic metabolic pathway.CONCLUSION: [(11)C]FTRP has in vitro biological function similar to that of [(11)C]HTP. However, this function is not retained in vivo as shown by biodistribution and PET/CT studies. Radiolabeled FTRP is thus not likely to provide an advantage over [(11)C]HTP in PET imaging in oncology, neurology or diabetes.
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| 18. |
- Estrada, Sergio, et al.
(author)
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[C-11]UCB-A, a novel PET tracer for synaptic vesicle protein 2 A
- 2016
-
In: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 43:6, s. 325-332
-
Journal article (peer-reviewed)abstract
- Introduction: Development of a selective and specific high affinity PET tracer, [C-11]UCB-A, for the in vivo study of SV2A expression in humans. Radiochemistry and preclinical studies in rats and pigs including development of a tracer kinetic model to determine V-T. A method for the measurement of percent intact tracer in plasma was developed and the radiation dosimetry was determined in rats. Results: 3-5 GBq of [C-11]UCB-A could be produced with radiochemical purity exceeding 98% with a specific radioactivity of around 65 GBq/mu mol. In vitro binding showed high selective binding towards SV2A. [C-11]UCB-A displayed a dose-dependent and reversible binding to SV2A as measured with PET in rats and pigs and the V-T could be determined by Logan analysis. The dosimetry was favorable and low enough to allow multiple administrations of [C-11]UCB-A to healthy volunteers, and the metabolite analysis showed no sign of labeled metabolites in brain. Conclusions: We have developed the novel PET tracer, [C-11]UCB-A, that can be used to measure SV2A expression in vivo. The dosimetry allows up to 5 administrations of 400 MBq of [C-11]UCB-A in humans. Apart from measuring drug occupancy, as we have shown, the tracer can potentially be used to compare SV2A expression between individuals because of the rather narrow range of baseline V-T values. This will have to be further validated in human studies.
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| 19. |
- Estrada, Sergio, et al.
(author)
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Preclinical evaluation of [C-11]GW457427 as a tracer for neutrophil elastase
- 2022
-
In: Nuclear Medicine and Biology. - : Elsevier. - 0969-8051 .- 1872-9614. ; 106-107, s. 62-71
-
Journal article (peer-reviewed)abstract
- Introduction: Neutrophils are part of the innate immune system and function as a first line of defense against invading microorganisms. Overactivity of the immune system may result in a devastating immuno-inflammation with extensive damage to tissue leading to organ damage and/or failure. The literature suggests several human diseases in which neutrophil elastase (NE) is postulated to be important in the pathophysiology including inflammatory bowel disease (IBD), chronic obstructive pulmonary disorder (COPD), abdominal aortic aneurysms (AAA), breast and lung cancer, and recently also in Sars-cov-2 virus infection (Covid-19). In particular, the lungs are affected by the destructive power of the protease neutrophil elastase (NE). In this paper, we report the pre-clinical development of a selective and specific positron emission tomography (PET) tracer, [C-11] GW457427, as an in vivo biomarker for the study of NE, now available for human studies.Methods: [C-11]GW457427 was produced by methylation of GW447631 using [C-11]methyl triflate and GMP validated production and quality control methods were developed. Chemical purity was high with no traces of the precursor GW611437 or other uv-absorbing compounds. A method for the determination of intact [C-11] GW457427 in plasma was developed and the binding characteristics were evaluated in vitro and in vivo. An animal model for lung inflammation was used to investigate the specificity and sensitivity of the [C-11]GW457427 tracer for neutrophil elastase (NE) in pulmonary inflammation, verified by blockade using two structurally different elastase inhibitors.Results: [C-11]GW457427 was obtained in approximately 45% radiochemical yield and with a radiochemical purity higher than 98%. Molar activity was in the range 130-360 GBq/mu mol. Binding to NE was shown to be highly specific both in vitro and in vivo and a significantly higher uptake of tracer was found in a lipopolysaccharide mouse model of pulmonary inflammation compared with control animals. The uptake in lung tissue measured as standardized uptake value (SUV) strongly correlated with tissue NE content as measured by ELISA. In vitro studies also showed specific tracer binding in aortic tissue of patients with abdominal aorta aneurysm (AAA). The rate of metabolism in rats was appropriate considering the critical balance between available tracer for binding and requirement for blood clearance with about 40% and 20% intact [C-11]GW457427 in plasma at 5 and 40 min, respectively. Radioactivity was cleared from blood and organs in control animals with mainly hepatobiliary excretion with distribution in the intestines and the urinary bladder; but without retention of the tracer in healthy organs of interests such as the lung, liver, kidneys or in the cardiovascular system. A dosimetry study in rat indicated that the whole-body effective dose was 2.2 mu Sv/MBq with bone marrow as the limiting organ. It is estimated that up to five PET-CT investigations could be performed in humans without exceeding a total dose of 10 mSv.Conclusion: [C-11]GW457427 is a promising in vivo PET-biomarker for NE with high specific binding demonstrated both in vitro and in vivo. A GMP validated production method including quality control has been developed and a microdosing toxicity study performed with no adverse signs. [C-11]GW457427 is currently being evaluated in a First-In-Man PET study.
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| 20. |
- Hall, Håkan, et al.
(author)
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Pharmacological characterization of 18F-labeled vorozole analogs
- 2012
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In: Journal of labelled compounds & radiopharmaceuticals. - : Wiley. - 0362-4803 .- 1099-1344. ; 55:14, s. 484-490
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Journal article (peer-reviewed)abstract
- Two F-18-labeled analogs of vorozole ([F-18]FVOZ and [F-18]FVOO) have been developed as potential tools for the in vivo characterization of aromatase. The pharmacologicalproperties of these radioligands were evaluated using in vitro binding and in vivo distribution studies in the rat and primate. Saturation binding studies using rat ovary gave K-D and B-max values of 0.21 +/- 0.1 nM and 210 +/- 20 fmol/mg, respectively, for [F-18]FVOZ, and 7.6 +/- 1nMand 293 +/- 12fmol/mg, respectively, for [F-18]FVOO. Organ distribution studies in rats showed the highest accumulation in the adrenal glands, with standardized uptake values (SUVs) of 15 to 20, followed by ovaries and liver with SUVs of approximately 5. Ex vivo and in vitro autoradiography of the rat brain showed specific binding of both [F-18]FVOZ and [F-18]FVOO mainly in the amygdala. Positron emission tomography (PET) studies were performed in the Rhesus monkey, and these showed displaceable binding in the amygdala and the hypothalamus preoptic area. The PET images were also analyzed using masked volume-wise principal component analysis. These studies suggest that [F-18]FVOZ might be a suitable tracer for the study of aromatase in vitro and in vivo, and could be an alternative to [C-11]vorozole in human PET studies.
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| 21. |
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| 22. |
- Hallgren, Jenny, et al.
(author)
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Histidines are critical for heparin-dependent activation of mast cell tryptase.
- 2004
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In: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 173:3, s. 1868-75
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Journal article (peer-reviewed)abstract
- Mast cell tryptase is a tetrameric serine protease that is stored in complex with negatively charged heparin proteoglycans in the secretory granule. Tryptase has potent proinflammatory properties and has been implicated in diverse pathological conditions such as asthma and fibrosis. Previous studies have shown that tryptase binds tightly to heparin, and that heparin is required in the assembly of the tryptase tetramer as well as for stabilization of the active tetramer. Because the interaction of tryptase with heparin is optimal at acidic pH, we investigated in this study whether His residues are of importance for the heparin binding, tetramerization, and activation of the tryptase mouse mast cell protease 6. Molecular modeling of mouse mast cell protease 6 identified four His residues, H35, H106, H108, and H238, that are conserved among pH-dependent tryptases and are exposed on the molecular surface, and these four His residues were mutated to Ala. In addition, combinations of different mutations were prepared. Generally, the single His-Ala mutations did not cause any major defects in heparin binding, activation, or tetramerization, although some effect of the H106A mutation was observed. However, when several mutations were combined, large defects in all of these parameters were observed. Of the mutants, the triple mutant H106A/H108A/H238A was the most affected with an almost complete inability to bind to heparin and to form active tryptase tetramers. Taken together, this study shows that surface-exposed histidines mediate the interaction of mast cell tryptase with heparin and are of critical importance in the formation of active tryptase tetramers.
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| 23. |
- Hellstrom-Lindahl, Ewa, et al.
(author)
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In vitro binding of [H-3]PIB to human amyloid deposits of different types
- 2014
-
In: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 21:1, s. 21-27
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Journal article (peer-reviewed)abstract
- Systemic amyloidosis is caused by extracellular deposition of insoluble fibrillar proteins arranged in beta-pleated sheets. [C-11] PIB has been used in PET studies to assess A beta deposition in brain of patients with Alzheimer's disease (AD). The possibility to visualize other types of amyloid deposits with [C-11] PIB would be of potential clinical importance in early diagnosis and for following therapeutic effects. In the present study, we evaluated in vitro binding of [3 H] PIB to tissues containing transthyretin (ATTR), immunoglobulin light-chain (AL), amyloid protein A (AA) and Ab amyloid. We found significantly higher binding of [H-3] PIB in tissue from systemic amyloidoses than in control tissue, i.e. 4.7 times higher (p<0.05). [H-3] PIB showed the highest affinity to cortex of AD brain (IC50 = 3.84 nM), while IC50 values were much higher for ATTR, AA and AL type of amyloidosis and large variations in affinity were observed even within tissues having the same type of amyloidosis. Extraction with guanidine-HCl, which disrupts the beta-sheet structure, decreased the protein levels and, concomitantly, the binding of [H-3] PIB in all four types of amyloidoses.
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| 24. |
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| 25. |
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| 26. |
- Hulsart Billström, Gry, 1982-, et al.
(author)
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Non-invasive tri-modal visualisation via PET/SPECT/μCT of recombinant human bone morphogenetic protein-2 retention and associated bone regeneration : A proof of concept
- 2018
-
In: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 285, s. 178-186
-
Journal article (peer-reviewed)abstract
- Bone morphogenetic proteins (BMP's) are vital for bone and cartilage formation, where bone morphogenetic protein-2 (BMP-2) is acknowledged as a growth factor in osteoblast differentiation. However, uncontrolled delivery may result in adverse clinical effects. In this study we investigated the possibility for longitudinal and non-invasive monitoring of implanted [125I]BMP-2 retention and its relation to ossification at the site of implantation. A unilateral critically sized femoral defect was produced in the left limb of rats while the right femur was retained intact as a paired reference control. The defect was filled with a hyaluronan hydrogel with 25% hydroxyapatite alone (carrier control; n = 2) or combined with a mixture of [125I]BMP-2 (150 μg/ml; n = 4). Bone formation was monitored using micro computed tomography (μCT) scans at 1, 3, 5, 7, 9 and 12 weeks. The retention of [125I]BMP-2 was assessed with single photon emission computed tomography (SPECT), and the bone healing process was followed with sodium fluoride (Na18F) using positron emission tomography (PET) at day 3 and at week 2, 4, and 6. A rapid burst release of [125I]BMP-2 was detected via SPECT. This was followed by a progressive increase in uptake levels of [18F]fluoride depicted by PET imaging that was confirmed as bone formation via μCT. We propose that this functional, non-invasive imaging method allows tri-modal visualisation of the release of BMP-2 and the following in vivo response. We suggest that the potential of this novel technique could be considered for preclinical evaluation of novel smart materials on bone regeneration.
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| 27. |
- Kehler, Jan, et al.
(author)
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Discovery and Development of C-11-Lu AE92686 as a Radioligand for PET Imaging of Phosphodiesterase10A in the Brain
- 2014
-
In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 55:9, s. 1513-1518
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Journal article (peer-reviewed)abstract
- Phosphodiesterase 10A (PDE10A) plays a key role in the regulation of brain striatal signaling, and several pharmaceutical companies currently investigate PDE10A inhibitors in clinical trials for various central nervous system diseases. A PDE10A PET ligand may provide evidence that a clinical drug candidate reaches and binds to the target. Here we describe the successful discovery and initial validation of the novel radiolabeled PDE10A ligand 5,8-dimethyl-2-[2-((1-C-11-methyl)-4-phenyl-1H-imidazol-2-yl)-ethyl]-[1,2,4]triazolo[1,5-a]pyridine (C-11-Lu AE92686) and its tritiated analog H-3-Lu AE92686. Methods: Initial in vitro experiments suggested Lu AE92686 as a promising radioligand, and the corresponding tritiated and C-11-labeled compounds were synthesized. 3H-Lu AE92686 was evaluated as a ligand for in vivo occupancy studies in mice and rats, and C-11-Lu AE92686 was evaluated as a PET tracer candidate in cynomolgus monkeys and in humans. Results: C-11-Lu AE92686 displayed high specificity and selectivity for PDE10A-expressing regions in the brain of cynomolgus monkeys and humans. Similar results were found in rodents using 3H-Lu AE92686. The binding of C-11-Lu AE92686 and 3H-Lu AE92686 to striatum was completely and dose-dependently blocked by the structurally different PDE10A inhibitor 2-[4-(1-methyl-4-pyridin-4-yl-1H-pyrazol-3-yl)-phenoxymethyl]-quinoline (MP-10) in rodents and in monkeys. In all species, specific binding of the radioligand was seen in the striatum but not in the cerebellum, supporting the use of the cerebellum as a reference region. The binding potentials (BPND) of C-11-Lu AE92686 in the striatum of both cynomolgus monkeys and humans were evaluated by the simplified reference tissue model with the cerebellum as the reference tissue, and BPND was found to be high and reproducible-that is, BP(ND)s were 6.5 +/- 0.3 (n = 3) and 7.5 +/- 1.0 (n = 12) in monkeys and humans, respectively. Conclusion: Rodent, monkey, and human tests of labeled Lu AE92686 suggest that C-11-Lu AE92686 has great potential as a human PET tracer for the PDE10A enzyme.
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| 28. |
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| 29. |
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| 30. |
- Lendvai, Gabor, et al.
(author)
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Biodistribution of Ga-68-labeled LNA-DNA mixmer antisense oligonucleotides for rat Chromogranin-A
- 2008
-
In: Oligonucleotides. - : Mary Ann Liebert Inc. - 1545-4576 .- 1557-8526. ; 18:1, s. 33-49
-
Journal article (peer-reviewed)abstract
- In vivo monitoring of gene expression may be accomplished using a most advanced imaging technology such as positron emission tomography (PET). However, a range of methodological and biological hurdles needs exploration. In the present study, 20-mer DNA-LNA (locked nucleic acid) mixmer oligonucleotides specific for rat Chromogranin-A (Chg-A) mRNA were labeled with Ga-68 and their biodistribution were investigated in rats; namely, two Antisense (LNA1, LNA2-differing only in the positioning of LNA modification), Mismatched, and Sense sequences. In addition, in vivo and in vitro metabolite analysis of LNA1 and LNA2 was compared, and hybridization in solution was performed to verify the hybridization ability after labeling. Furthermore, semiquantitative polymerase chain reaction was carried out to find organs expressing Chg-A mRNA in the rat. The biodistribution patterns altered according to the sequence and the positioning of LNA modification. The pattern of Mismatched-differing only in two nucleotides from the two Antisenses-was similar to that of Sense, whereas the pattern of LNA1 and LNA2 showed differences. Uptake in the adrenal gland was twofold higher with LNA2 compared to the other three oligonucleotides. Intact LNA2 could be observed in the 60-minute sample in vivo, whereas in vitro, the intact compound of both Antisenses could also be detected after 2 hours. Hybridization in solution revealed that the two Antisenses retained their hybridization abilities after Ga-68-labeling. With decreasing magnitude, Chg-A mRNA was expressed in the adrenal gland, intestine, testis, and pancreas. This study further supported LNA-DNA mixmer to be a favorable modification for antisense targeting approach with respect to hybridization and longer plasma residence; however, the organ uptake was dominated by processes irrelevant to specific hybridization.
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| 31. |
- Lendvai, Gabor, et al.
(author)
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Non-hybridisation saturable mechanisms play a role in the uptake of 68Ga-labelled LNA-DNA mixmer antisense oligonucleotides in rats
- 2009
-
In: Oligonucleotides. - : Mary Ann Liebert Inc. - 1545-4576 .- 1557-8526. ; 19:3, s. 223-231
-
Journal article (peer-reviewed)abstract
- Oligonucleotides (ODN) are key molecules for the aim of preventing translation of a gene product or monitoring gene expression in tissues. However, multiple methodological and biological hurdles need to be solved before in vivo application in humans will be possible. For positron emission tomography (PET) investigations, a 20-mer DNA-locked nucleic acid (LNA) mixmer ODN specifi c for rat chromogranin-A mRNA was labeled with Ga-68 and its uptake was examined in vivo in rats with and without blocking of scavenger receptors by polyribo-nucleotides. In addition, uptake studies of Ga-68-LNA were performed with respect to time and concentration in human and rat cell lines. The human cell lines did not express the target mRNA. Both polyinosinic acid (poly-I) and polyadenylic acid (poly-A) reduced the uptake in rat tissues and in human cell lines. Poly-I was found to be more effective in the liver whereas poly-A was more effective in the kidney. In addition, the blockade by poly-I was statistically significant in the pancreas, adrenal gland, bone marrow, intestine, testis, urinary bladder, muscle, parotid gland, and heart, whereas poly-A also caused significant reduction in pancreas, adrenal gland, and bone marrow but not as much as in kidney. Cell culture study showed a 2-phase dose-dependent uptake characteristic with a saturable and a passive diffusion-like phase; however, these 2 phases were not so well expressed in the rat cell line. The results suggest that scavenger receptors or other saturable processes unrelated to hybridization may be involved in the tissue uptake of Ga-68-LNA and in the clearance of antisense ODN through the liver, kidney, spleen, and bone marrow. The fact that these processes may be sequence-dependent suggests that proof of in vivo hybridization through imaging may not be obtained by only comparing sense and antisense sequences and proving dose-dependency.
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| 32. |
- Lendvai, Gábor, 1969-
(author)
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Radiolabelled Oligonucleotides for Evaluation of in vivo Hybridisation Utilising PET Methodology
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Antisense oligonucleotides (ODN) may interfere in gene expression on the basis of hybridising to its complementary messenger RNA (mRNA) sequence in the cell thereby preventing the synthesis of the peptide. Therefore, these ODNs may be potential drugs to treat human diseases by “knocking down” the expression of responsible genes or correcting the maturation process of mRNA in the field called antisense therapy. Moreover, antisense ODNs upon labelling are also potential imaging agents to monitor gene expression in vivo, i.e. to accomplish in vivo hybridisation. This would provide a non-invasive tool compared to present methods, which require tissue samples. This goal may be reached using positron emission tomography (PET) methodology. PET is a most advanced in vivo imaging technology, which would allow exploring the fate of radionuclide-labelled antisense ODNs in the body; thereby providing information about biodistribution and quantitative accumulation in tissues to assess pharmacokinetic properties of ODNs. This kind of evaluation is important as part of the characterisation of antisense therapeutics but also as part of the development of antisense imaging agents.The present study aimed to investigate 76Br- and 68Ga-labelled ODNs of five different modifications: phosphodiester, phosphorothioate, 2'-O-methyl phosphodiester, locked nucleic acid (LNA), and peptide nucleic acid. The study included exploration of the hybridisation abilities of these ODNs after labelling; furthermore, the biodistribution, metabolite analysis and uptake of the ODNs in rats regarding non-hybridisation and hybridisation specific uptake was conducted. Among the ODNs studied, LNA-DNA mixmer (LNA and DNA nucleotides in alternation along the sequence) displayed the most promising characteristics considering a higher retention in tissues, stability and longer plasma residence. However, biodistribution data demonstrated a non-hybridisation specific distribution in rat tissues with kidney, liver, spleen and bone marrow being the organs of high uptake. Scavenger receptors or other saturable processes unrelated to hybridisation may play a role in tissue uptake and in clearance of antisense ODNs through these organs. These processes may be sequence dependent suggesting that proof of in vivo hybridisation through imaging needs much more elaborate evaluations than just comparison of sense and antisense sequences and proving dose-dependency.
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Nordeman, Patrik, et al.
(author)
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11C-Labeling of a Potent Hydroxyethylamine BACE-1 Inhibitor and Evaluation in vitro and in vivo
- 2014
-
In: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 41:6, s. 536-543
-
Journal article (peer-reviewed)abstract
- Introduction: The enzyme beta-secretase 1 (BACE-1) is associated with the catalytic cleavage of amyloid precursor protein (APP) which leads to the production of amyloid-p, an amyloidogenic peptide that forms insoluble fibrils and is linked to neurodegeneration and Alzheimer's disease (AD). A PET-radioligand for the quantification of BACE-1 would be useful for the understanding of AD. In this report, we describe the synthesis and carbon-11 radiolabeling of a potent hydroxyethylamine BACE-1 enzyme inhibitor (BSI-IV) and its evaluation in vitro and in vivo. Methods: (11)[C]-N-1-((2S,3R)-4-(cyclopropylamino)-3-hydroxy-1-phenylbutan-2-y1)-5-(N-methylmethylsulfonamido)-N-3-((R)-1-phenylethyl)isophthalamide, a p-secretase inhibitor, denoted here as [C-11]BSIIV was synthesized through a palladium-mediated aminocarbonylation with an aryl halide precursor (I or Br) and [C-11]CO. The effect of different palladium/ligand-complexes on radiochemical yield in the carbonylative reaction was investigated. The binding of the labeled compound to BACE-1 enzyme was studied in vitro by frozen section autoradiography from brains of healthy rats. Dynamic small animal PET-CT studies and ex vivo biodistribution were performed in male rats. Results: The halide precursors were synthesized in six steps starting from methyl-3-nitrobenzoate with an overall yield of 21-26%. [C-11]BSI-IV was obtained in 29 +/- 12% decay corrected radiochemical yield (n = 12) with a specific activity of 790 +/- 155 GBq/umol at the end of synthesis with a radiochemical purity of >99%. The predinical studies showed that [C-11]BSI-IV has a rapid metabolism in rat with excretion to the small intestines. Conclusion: [C-11]BSI-IV was obtained in sufficient amount and purity to enable predinical investigation. The predinical studies showed low specific binding in vitro and fast clearance in vivo and a low uptake in the brain. These findings suggests that [C-11]BSI-IV has limited use as a PET-ligand for the study of BACE-1 or AD.
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| 38. |
- Nordeman, Patrik, Docent, et al.
(author)
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18F-Radiolabeling and Preliminary Evaluation of a HSP90 ligand
- 2021
-
In: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 157
-
Journal article (peer-reviewed)abstract
- PURPOSE: With the ambition of improving the management of pancreatic neuroendocrine tumors (P-NETs), we developed and preliminary validated a novel fluorine-18 labelled HSP90 ligand.METHODS: A precursor containing methoxymethyl ethers protecting groups and a tosyl as leaving group was synthesized. The target compound was labeled with nucleophilic 18F-fluoride and the protecting groups was subsequently removed with hydrochloric acid before purification. In vitro cell- and frozen section autoradiography and in vivo animal studies were performed.RESULTS: The precursor was successfully synthesized and utilized in the 18F-radiolabeling giving 0.5-1.0 GBq of pure product with a synthesis time of 70 min. In vitro experiments indicated a high specific binding, but in vivo studies showed no tumor uptake due to fast hepatobiliary metabolism and excretion.CONCLUSIONS: Despite the unfavorable in vivo properties of the tracer, the promising results from in vitro autoradiography experiments in frozen sections of P-NETs from surgical resection encourage us to continue the project aiming the improvement of in vivo properties of the tracer.
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| 39. |
- Nordeman, Patrik, et al.
(author)
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C-11 and F-18 Radiolabeling of Tetra- and Pentathiophenes as PET-Ligands for Amyloid Protein Aggregates
- 2016
-
In: ACS Medicinal Chemistry Letters. - : American Chemical Society (ACS). - 1948-5875. ; 7:4, s. 368-373
-
Journal article (peer-reviewed)abstract
- Three oligothiophenes were evaluated as PET ligands for the study of local and systemic amyloidosis ex vivo using tissue from patients with amyloid deposits and in vivo using healthy animals and PET-CT. The ex vivo binding studies revealed that all three labeled compounds bound specifically to human amyloid deposits. Specific binding was found in the heart, kidney, liver, and spleen. To verify the specificity of the oligothiophenes toward amyloid deposits, tissue sections with amyloid pathology were stained using the fluorescence exhibited by the compounds and evaluated with multiphoton microscopy. Furthermore, a in vivo monkey PET-CT study showed very low uptake in the brain, pancreas, and heart of the healthy animal indicating low nonspecific binding to healthy tissue. The biological evaluations indicated that this is a promising group of compounds for the visualization of systemic and localized amyloidosis.
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| 40. |
- Nordling, Sofia, 1985-, et al.
(author)
-
Enhanced protection of the renal vascular endothelium improves early outcome in kidney transplantation : Preclinical investigations in pig and mouse
- 2018
-
In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
-
Journal article (peer-reviewed)abstract
- Ischemia reperfusion injury is one of the major complications responsible for delayed graft function in kidney transplantation. Applications to reduce reperfusion injury are essential due to the widespread use of kidneys from deceased organ donors where the risk for delayed graft function is especially prominent. We have recently shown that coating of inflamed or damaged endothelial cells with a unique heparin conjugate reduces thrombosis and leukocyte recruitment. In this study we evaluated the binding capacity of the heparin conjugate to cultured human endothelial cells, to kidneys from brain-dead porcine donors, and to murine kidneys during static cold storage. The heparin conjugate was able to stably bind cultured endothelial cells with high avidity, and to the renal vasculature of explanted kidneys from pigs and mice. Treatment of murine kidneys prior to transplantation reduced platelet deposition and leukocyte infiltration 24 hours post-transplantation, and significantly improved graft function. The present study thus shows the benefits of enhanced protection of the renal vasculature during cold storage, whereby increasing the antithrombotic and anti-adhesive properties of the vascular endothelium yields improved renal function early after transplantation.
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| 41. |
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| 42. |
- Puuvuori, Emmi, et al.
(author)
-
PET imaging of neutrophil elastase with 11C-GW457427 in Acute Respiratory Distress Syndrome in pigs
- 2023
-
In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine and Molecular Imaging. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 64:3, s. 423-429
-
Journal article (peer-reviewed)abstract
- Today, there is a lack of clinically available imaging techniques to detect and quantify specific immune cell populations. Neutrophils are one of the first immune cells at the site of inflammation, and they secrete the serine protease neutrophil elastase (NE), which is crucial in the fight against pathogens. However, the prolonged lifespan of neutrophils increases the risk that patients will develop severe complications, such as acute respiratory distress syndrome (ARDS). Here, we evaluated the novel radiolabeled NE inhibitor 11C-GW457427 in a pig model of ARDS, for detection and quantification of neutrophil activity in the lungs. Methods: ARDS was induced by intravenous administration of oleic acid to 5 farm pigs, and 4 were considered healthy controls. The severity of ARDS was monitored by clinical parameters of lung function and plasma biomarkers. Each pig was studied with 11C-GW457427 and PET/CT, before and after pretreatment with the NE inhibitor GW311616 to determine in vivo binding specificity. PET image data were analyzed as SUVs and correlated with immunohistochemical staining for NE in biopsies. Results: The binding of 11C-GW457427 was increased in pig lungs with induced ARDS (median SUVmean, 1.91; interquartile range [IQR], 1.67-2.55) compared with healthy control pigs (P < 0.05 and P = 0.03, respectively; median SUVmean, 1.04; IQR, 0.66-1.47). The binding was especially strong in lung regions with high levels of NE and ongoing inflammation, as verified by immunohisto-chemistry. The binding was successfully blocked by pretreatment of an NE inhibitor drug, which demonstrated the in vivo specificity of 11C-GW457427 (P < 0.05 and P = 0.04, respectively; median SUVmean, 0.60; IQR, 0.58-0.77). The binding in neutrophil-rich tissues such as bone marrow (P < 0.05 and P = 0.04, respectively; baseline median SUVmean, 5.01; IQR, 4.48-5.49; block median SUVmean, 1.57; IQR, 0.95-1.85) and spleen (median SUVmean, 2.14; IQR, 1.19-2.36) was also high in all pigs. Conclusion: 11C-GW457427 binds to NE in a porcine model of oleic acid-induced lung inflammation in vivo, with a specific increase in regional lung, bone marrow, and spleen SUV. 11C-GW457427 is a promising tool for localizing, tracking, and quantifying neutrophil-facilitated inflammation in clinical diagnostics and drug development.
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| 43. |
- Razifar, Pasha, et al.
(author)
-
An automated method for delineating a reference region using masked volumewise principal-component analysis in 11C-PIB PET
- 2009
-
In: Journal of Nuclear Medicine Technology. - : Society of Nuclear Medicine. - 0091-4916 .- 1535-5675. ; 37:1, s. 38-44
-
Journal article (peer-reviewed)abstract
- Kinetic modeling using a reference region is a common method for the analysis of dynamic PET studies. Available methods for outlining regions of interest representing reference regions are usually time-consuming and difficult and tend to be subjective; therefore, MRI is used to help physicians and experts to define regions of interest with higher precision. The current work introduces a fast and automated method to delineate the reference region of images obtained from an N-methyl-(11)C-2-(4'-methylaminophenyl)-6-hydroxy-benzothiazole ((11)C-PIB) PET study on Alzheimer disease patients and healthy controls using a newly introduced masked volumewise principal-component analysis.METHODS: The analysis was performed on PET studies from 22 Alzheimer disease patients (baseline, follow-up, and test/retest studies) and 4 healthy controls, that is, a total of 26 individual scans. The second principal-component images, which illustrate the kinetic behavior of the tracer in gray matter of the cerebellar cortex, were used as input data for automatic delineation of the reference region. To study the variation associated with the manual and proposed automatic methods, we defined the reference region repeatedly.RESULTS: As expected, the automatic method showed no variation whereas the manual method varied significantly on repetition. Furthermore, the automatic method was significantly faster, more robust, and less biased.CONCLUSION: The automatic method is helpful in the delineation of the reference region of (11)C-PIB PET studies of the human brain and is much faster and more precise than manual delineation.
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| 44. |
- Razifar, Pasha, et al.
(author)
-
Principal component analysis with pre-normalization improves the signal-to-noise ratio and image quality in positron emission tomography studies of amyloid deposits in Alzheimer's disease
- 2009
-
In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 54:11, s. 3595-3612
-
Journal article (peer-reviewed)abstract
- This study introduces a new approach for the application of principal component analysis (PCA) with pre-normalization on dynamic positron emission tomography (PET) images. These images are generated using the amyloid imaging agent N-methyl [C-11]2-(4'-methylaminophenyl)-6-hydroxybenzothiazole ([C-11]PIB) in patients with Alzheimer's disease (AD) and healthy volunteers (HVs). The aim was to introduce a method which, by using the whole dataset and without assuming a specific kinetic model, could generate images with improved signal-to-noise and detect, extract and illustrate changes in kinetic behavior between different regions in the brain. Eight AD patients and eight HVs from a previously published study with [C-11] PIB were used. The approach includes enhancement of brain regions where the kinetics of the radiotracer are different from what is seen in the reference region, pre-normalization for differences in noise levels and removal of negative values. This is followed by slice-wise application of PCA (SW-PCA) on the dynamic PET images. Results obtained using the new approach were compared with results obtained using reference Patlak and summed images. The new approach generated images with good quality in which cortical brain regions in AD patients showed high uptake, compared to cerebellum and white matter. Cortical structures in HVs showed low uptake as expected and in good agreement with data generated using kinetic modeling. The introduced approach generated images with enhanced contrast and improved signal-to-noise ratio (SNR) and discrimination power (DP) compared to summed images and parametric images. This method is expected to be an important clinical tool in the diagnosis and differential diagnosis of dementia.
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| 45. |
- Rosestedt, Maria, et al.
(author)
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Radiolabelling and positron emission tomography imaging of a high-affinity peptide binder to collagen type 1
- 2021
-
In: Nuclear Medicine and Biology. - : Elsevier. - 0969-8051 .- 1872-9614. ; 93, s. 54-62
-
Journal article (peer-reviewed)abstract
- IntroductionPathological formation of fibrosis, is an important feature in many diseases. Fibrosis in liver and pancreas has been associated to metabolic disease including type 1 and 2 diabetes. The current methods for detecting and diagnosing fibrosis are either invasive, or their sensitivity to detect fibrosis in early stage is limited. Therefore, it is crucial to develop non-invasive methods to detect, stage and study the molecular processes that drive the pathology of liver fibrosis. The peptide LRELHLNNN was previously identified as a selective binder to collagen type I with an affinity of 170 nM. Radiolabelled LRELHLNNN thus constitute a potential PET tracer for fibrosis.MethodLRELHLNNN was conjugated to a DOTA/NOTA moiety via a PEG2-linker. DOTA-PEG2-LRELHLNNN was labelled with Gallium-68 and NOTA- PEG2-LRELHLNNN with aluminium fluoride-18. Biodistribution of [68Ga]Ga-DOTA-PEG2-LRELHLNNN and [18F]AlF-NOTA-PEG2-LRELHLNNN was performed in healthy rats ex vivo and in vivo. The 68Ga-labelled analogue was evaluated in a mouse model of liver fibrosis by PET/MRI-imaging. The human predicted dosimetry of the tracers was extrapolated from rat ex vivo biodistribution studies at 10, 20, 40, 60, 120, 180 min (only fluoride-18) post-injection.ResultsThe peptides were successfully radiolabelled with gallium-68 and aluminium fluoride-18, respectively. The biodistribution of [68Ga]Ga-DOTA-PEG2-LRELHLNNN and [18F]AlF-NOTA-PEG2-LRELHLNNN was favorable showing rapid clearance and low background binding in organs where fibrosis may develop. Binding of [68Ga]Ga-DOTA-PEG2-LRELHLNNN to fibrotic liver was higher than surrounding tissues in mice with induced hepatic fibrosis. However, the binding was in the range of SUV 0.3, indicating limited targeting of the tracer to liver. The extrapolated human predicted dosimetric profiles of [68Ga]Ga-DOTA-PEG2-LRELHLNNN and [18F]AlF-NOTA-PEG2-LRELHLNNN were beneficial, potentially allowing at least three PET examinations annually.ConclusionsWe describe the modification, radiolabelling and evaluation of the collagen type I binding peptide LRELHLNNN. The resulting radiotracer analogues demonstrated suitable biodistribution and dosimetry. [68Ga]Ga-DOTA-PEG2-LRELHLNNN exhibited binding to hepatic fibrotic lesions and is a promising tool for PET imaging of fibrosis.Advances in knowledgeValidation of a new collagen targeting PET tracer.Implications for patient careEarly, non-invasive diagnosis and stratification of fibrosis in order to improve the diagnosis, staging and treatment of patients with diseases involving fibrosis.
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| 46. |
- Sellberg, Felix, et al.
(author)
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A novel polymer-based carbonyl scavenger for the detection of ischemic tissues
-
Other publication (other academic/artistic)abstract
- PurposePolyvinylalcohol-carbazate (PVAC) is a soluble functionalized polymer acting as a carbonyl scavenger. This study aimed to create a radiolabelled PVAC and investigate the pharmacokinetics and biodistribution of PVAC in naïve animals and ischemia models. MethodsPVAC was labelled using radionuclide [18F]FBA to track the substance with PET. Sprague Dawley rats underwent an ischemic event, either to the hind limb or to the kidney, while others served as controls. To study the pharmacokinetics rats were injected with radiolabelled or fluorochrome labelled PVAC. Radiolabelled PVAC was injected, and animals were followed by PET for 90 min, biodistribution ex vivo was finally examined. Injection of fluorochrome-labelled PVAC was followed by repeated blood sampling to measure the circulating concentration. ResultsIn control animals, PVAC was mainly confined to the bloodstream followed by elimination via kidneys and accumulation in the bladder. Ex vivo biodistribution of PVAC confirmed the highest uptake in urine followed by blood, kidneys and other well-perfused organs. The elimination of I.V. administered PVAC was split into a fast phase (t1/2 = 0.2 h) followed by a slow phase (t1/2 = 10.73 h), with near-complete elimination from blood after 48 h. Both the ischemic kidney (fourfold increase, p = <0.001) and limb models (threefold increase, p = <0.001) demonstrated a higher uptake of PVAC in ischemic tissues, ex vivo radioactivity detection.ConclusionLabelled PVAC, an aldehyde-carbonyl scavenger, is a promising new strategy to detect ischemic tissues. Potential therapeutic effects of PVAC on ischemic injuries should be investigated further.
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| 47. |
- Selvaraju, Ram Kumar, et al.
(author)
-
Dosimetry of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in rodents, pigs, non-human primates and human - : repeated scanning in human is possible.
- 2015
-
In: American journal of nuclear medicine and molecular imaging. - 2160-8407. ; 5:3, s. 259-69
-
Journal article (peer-reviewed)abstract
- Quantitative PET imaging with [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 has potential use in diabetes and cancer. However, the radiation dose to the kidneys has been a concern for the possibility of repeated imaging studies in humans. Therefore, we investigated the dosimetry of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 based on the biodistribution data in rats, pigs, non-human primates (NHP) and a human.Organ distribution of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in rats (Male Lewis; n=12; 30, 60, and 80 min) was measured ex vivo. The dynamic uptake of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 in the abdomen was assessed by PET/CT scanning of pigs (male; n = 4, 0-60 min), NHP (Female; cynomolgus; n=3; 0-90 min), and human (female; n=1; 0-40, 100, 120 min).The organ distribution data in each species were extrapolated to those of a human, assuming similar distribution between the species. Residence times were assessed by trapezoidal approximation of the kinetic data. Organ doses (mGy/MBq) and the whole body effective dose (mSv/MBq), was extrapolated by using the OLINDA/EXM 1.1 software. The extrapolated human whole body effective dose was 0.017 ± 0.004 (rats), 0.014 ± 0.004 (pigs), 0.017 ± 0.004 (NHP), and 0.016 (human) mSv/MBq. The absorbed dose to the kidneys was limiting:0.33 ± 0.06 (rats), 0.28±0.05 (pigs), 0.65 ± 0.11 (NHP), and 0.28 (human) mGy/MBq, which corresponded to the maximum yearly administered amounts of 455 (rat), 536 (pig), 231 (NHP), and 536 (human) MBq before reaching the yearly kidney limiting dose of 150 mGy. More than 200 MBq of [(68)Ga]Ga-DO3A-VS-Cys(40)-Exendin-4 can be administered yearly in a human, allowing for repeated (2-4 times) scanning. This potentially enables longitudinal clinical PET imaging studies of the GLP-1R in the pancreas, transplanted islets, or insulinoma.
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| 48. |
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| 49. |
- Silins, Isabella, 1983-, et al.
(author)
-
Para-chloro-2-[18F]fluoroethyl-etomidate : A promising new PET radiotracer for adrenocortical imaging
- 2021
-
In: International Journal of Medical Sciences. - : Ivyspring International Publisher. - 1449-1907. ; 18:10, s. 2187-2196
-
Journal article (peer-reviewed)abstract
- Introduction: [11C]Metomidate ([11C]MTO), the methyl ester analogue of etomidate, was developed as a positron emission tomography (PET) radiotracer for adrenocortical tumours and has also been suggested for imaging in primary aldosteronism (PA). A disadvantage of [11C]MTO is the rather high non-specific binding in the liver, which impacts both visualization and quantification of the uptake in the right adrenal gland. Furthermore, the short 20-minute half-life of carbon-11 is a logistic challenge in the clinical setting.Objectives: The aim of this study was to further evaluate the previously published fluorine-18 (T1/2=109.5 min) etomidate analogue, para-chloro-2-[18F]fluoroethyl etomidate; [18F]CETO, as an adrenal PET tracer.Methods: In vitro experiments included autoradiography on human and cynomolgus monkey (non-human primate, NHP) tissues and binding studies on adrenal tissue from NHPs. In vivo studies with [18F]CETO in mice, rats and NHP, using PET and CT/MRI, assessed biodistribution and binding specificity in comparison to [11C]MTO.Results: The binding of [18F]CETO in the normal adrenal cortex, as well as in human adrenocortical adenomas and adrenocortical carcinomas, was shown to be specific, both in vitro (in humans) and in vivo (in rats and NHP) with an in vitro Kd of 0.66 nM. Non-specific uptake of [18F]CETO in NHP liver was found to be low compared to that of [11C]MTO.Conclusions: High specificity of [18F]CETO to the adrenal cortex was demonstrated, with in vivo binding properties qualitatively surpassing those of [11C]MTO. Non-specific binding to the liver was significantly lower than that of [11C]MTO. [18F]CETO is a promising new PET tracer for imaging of adrenocortical disease and should be evaluated further in humans.
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| 50. |
- Stevens, Marc, 1984-
(author)
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Multicomponent Reactions in 11C/12C Chemistry : – Targeting the Angiotensin II Subtype 2 Receptor
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Section 1 of this thesis contains an introduction to method development in organic synthesis, multicomponent reactions, sulfonyl azides, tracer development in 11C chemistry and the biological target.Section 2 describes the use of sulfonyl azides in carbonylative chemistry. Paper I covers development of a diazotransfer protocol. In total, 30 arylsulfonyl azides were synthesised from primary sulfonamides (20–90% yield). 15N mechanistic studies were carried out and in Paper II, the products were converted into sulfonamides, sulfonylureas and sulfonyl carbamates (19–90% yield). For ureas and carbamates, a two-chamber protocol was employed to release CO from Mo(CO)6. 15N mechanistic studies showed that the sulfonamides were formed by direct displacement of azide.Section 3 covers imaging and biological studies of the angiotensin II receptor subtype 2 (AT2R). In Paper III, 12 11C-sulfonyl carbamates were prepared in isolated radiochemical yields of 3–51% via Rh(I)-mediated carbonylation. The first non-peptide AT2R agonist, C21, was labelled (isolated RCY 24±10%, SA 34–51 GBq/µmol). C21 was tested in a prostate cancer assay, followed by biodistribution and small-animal PET studies. In Paper IV, a 11C-labelled AT2R ligand prepared via Pd(0)-mediated aminocarbonylation was used for autoradiography, biodistribution and small-animal PET studies. Section 4 describes the development of a multicomponent method for the synthesis of 3,4-dihydroquinazolinones (Paper V). 31 3,4-dihydroquinazolinones were synthesized via a cyclic iminium ion.
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