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- Tovedal, Thomas, et al.
(author)
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Blood Flow Quantitation by Positron Emission Tomography During Selective Antegrade Cerebral Perfusion
- 2017
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In: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975 .- 1552-6259. ; 103:2, s. 610-616
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Journal article (peer-reviewed)abstract
- BACKGROUND: Perfusion strategies during aortic surgery usually comprise hypothermic circulatory arrest (HCA), often combined with selective antegrade cerebral perfusion (SACP) or retrograde cerebral perfusion. Cerebral blood flow (CBF) is a fundamental parameter for which the optimal level has not been clearly defined. We sought to determine the CBF at a pump flow level of 6 mL/kg/min, previously shown likely to provide adequate SACP at 20°C in pigs.METHODS: Repeated positron emission tomography (PET) scans were used to quantify the CBF and glucose metabolism throughout HCA and SACP including cooling and rewarming. Eight pigs on cardiopulmonary bypass were assigned to either HCA alone (n = 4) or HCA+SACP (n = 4). The CBF was measured by repeated [(15)O]water PET scans from baseline to rewarming. The cerebral glucose metabolism was examined by [(18)F]fluorodeoxyglucose PET scans after rewarming to 37°C.RESULTS: Cooling to 20°C decreased the cortical CBF from 0.31 ± 0.06 at baseline to 0.10 ± 0.02 mL/cm(3)/min (p = 0.008). The CBF was maintained stable by SACP of 6 mL/kg/min during 45 minutes. After rewarming to 37°C, the mean CBF increased to 0.24 ± 0.07 mL/cm(3)/min, without significant differences between the groups at any time-point exclusive of the HCA period. The net cortical uptake (Ki) of [(18)F]fluorodeoxyglucose after rewarming showed no significant difference between the groups.CONCLUSIONS: Cooling autoregulated the CBF to 0.10 mL/cm(3)/min, and 45 minutes of SACP at 6 mL/kg/min maintained the CBF in the present model. Cerebral glucose metabolism after rewarming was similar in the study groups.
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- Varasteh, Zohreh, et al.
(author)
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In Vitro and In Vivo Evaluation of a F-18-Labeled High Affinity NOTA Conjugated Bombesin Antagonist as a PET Ligand for GRPR-Targeted Tumor Imaging
- 2013
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In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12, s. e81932-
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Journal article (peer-reviewed)abstract
- Expression of the gastrin-releasing peptide receptor (GRPR) in prostate cancer suggests that this receptor can be used as a potential molecular target to visualize and treat these tumors. We have previously investigated an antagonist analog of bombesin (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2, RM26) conjugated to 1,4,7-triazacyclononane-N,N',N ''-triacetic acid (NOTA) via a diethylene glycol (PEG(2)) spacer (NOTA-P2-RM26) labeled with Ga-68 and In-111. We found that this conjugate has favorable properties for in vivo imaging of GRPR-expression. The focus of this study was to develop a F-18-labelled PET agent to visualize GRPR. NOTA-P2-RM26 was labeled with F-18 using aluminum-fluoride chelation. Stability, in vitro binding specificity and cellular processing tests were performed. The inhibition efficiency (IC50) of the [F-nat]AlF-NOTA-P2-RM26 was compared to that of the Ga-nat-loaded peptide using I-125-Tyr(4)-BBN as the displacement radioligand. The pharmacokinetics and in vivo binding specificity of the compound were studied. NOTA-P2-RM26 was labeled with F-18 within 1 h (60-65% decay corrected radiochemical yield, 55 GBq/mu mol). The radiopeptide was stable in murine serum and showed high specific binding to PC-3 cells. [F-nat]AlF-NOTA-P2-RM26 showed a low nanomolar inhibition efficiency (IC50=4.4 +/- 0.8 nM). The internalization rate of the tracer was low. Less than 14% of the cell-bound radioactivity was internalized after 4 h. The biodistribution of [F-18]AlF-NOTA-P2-RM26 demonstrated rapid blood clearance, low liver uptake and low kidney retention. The tumor uptake at 3 h p. i. was 5.5 +/- 0.7 % ID/g, and the tumor-to-blood, -muscle and -bone ratios were 87 +/- 42, 159 +/- 47, 38 +/- 16, respectively. The uptake in tumors, pancreas and other GRPR-expressing organs was significantly reduced when excess amount of non-labeled peptide was co-injected. The low uptake in bone suggests a high in vivo stability of the Al-F bond. High contrast PET image was obtained 3 h p. i. The initial biological results suggest that [F-18]AlF-NOTA-P2-RM26 is a promising candidate for PET imaging of GRPR in vivo.
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- Aarnio, Mikko, et al.
(author)
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Evaluation of PET tracers [11C]D-deprenyl, [11C]L-dideuteriumdeprenyl and [18F]FDG for Visualization of Acute Inflammation in a Rat Model of Pain - Preliminary Findings.
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Other publication (other academic/artistic)abstract
- Purpose: Positron emission tomography with the radioligand [11C]D-deprenyl has shown an increased signal at the location of pain in patients with ankle sprains, rheumatoid arthritis and chronic whiplash injury, but the mechanism of this tracer uptake and its exact binding site in inflammation or tissue injury is still unclear. The aim of this study was to further evaluate [11C]D-deprenyl´s usefulness as a marker of acute inflammation.Methods: An animal PET/CT study was performed three days after the induction of a rat model of inflammatory or surgical pain. Fourteen adult male Sprague-Dawley rats and three tracers [11C]D-deprenyl, [11C]L-dideuterumdeprenyl and [18F]fluorodeoxyglucose were used. Results: No [11C]D-deprenyl accumulation was seen in a rat model of musculoskeletal pain. In the rat model of inflammatory pain all three ligands were shown to visualize the inflamed ankle joint with much lower uptake in the control ankle joint. The uptake was largest with [11C]D-deprenyl and [11C]L- dideuteriumdeprenyl, where approximately 1 % of the injected dose could be found in the affected ankle joint during the first minutes, whereas the uptake of [18F]FDG was approximately 0.5 % of the injected dose. However, the ratio of uptake of the injected ankle joint versus the control ankle joint was much higher for [18F]FDG (around 10 fold increase) than for the two deprenyl enantiomers (2 – 3 fold increase). The uptake pattern of [11C]D-deprenyl and [11C]L-dideuteriumdeprenyl did not show signs of specific binding or irreversible trapping.Conclusions: Contrary to our expectations, of the three tracers only [18F]FDG may be used as markers of peripheral inflammation in a rat model of inflammatory pain. However, as a high site-specificity is required, [11C]D-deprenyl and [11C]L-dideyteriumdeprenyl deserve further exploration regarding sensitivity, specificity and uptake mechanisms in human pain syndromes.
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- Abelev, Betty, et al.
(author)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Journal article (peer-reviewed)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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- Abelev, Betty, et al.
(author)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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- Abelev, Betty, et al.
(author)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :7
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Journal article (peer-reviewed)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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- Andersen, Thomas L., et al.
(author)
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Application of Methyl Bisphosphine-Ligated Palladium Complexes for Low Pressure N-C-11-Acetylation of Peptides
- 2017
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In: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 56:16, s. 4549-4553
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Journal article (peer-reviewed)abstract
- A mild and effective method is described for C-11-labeling of peptides selectively at the N-terminal nitrogen or at internal lysine positions. The presented method relies on the use of specific biphosphine palladium-methyl complexes and their high reactivity towards amino-carbonylation of amine groups in the presence [C-11] carbon monoxide. The protocol facilitates the production of native N-C-11-acetylated peptides, without any structural modifications and has been applied to a selection of bioactive peptides.
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- Andersen, Thomas L., et al.
(author)
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Efficient C-11-Carbonylation of Isolated Aryl Palladium Complexes for PET : Application to Challenging Radiopharmaceutical Synthesis
- 2015
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 137:4, s. 1548-1555
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Journal article (peer-reviewed)abstract
- We describe the successful implementation of palladium-aryl oxidative addition complexes as stoichiometric reagents in carbonylation reactions with (CO)-C-11 to produce structurally challenging, pharmaceutically relevant compounds. This method enables the first C-11-carbonyl labeling of an approved PET tracer, [C-11]raclopride, for the dopamine D2/D3 receptor by carbonylation with excellent radiochemical purity and yield. Two other molecules, [C-11]olaparib and [C-11]JNJ 31020028, were efficiently labeled in this manner. The technique distinguishes itself from existing methods by the markedly improved purity profiles of the tracer molecules produced and provides access to complex structures in synthetically useful yields, hereby offering a viable alternative to other C-11-labeling strategies.
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