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  • 1
    Language: English
    In: Neuroscience, June 28, 2012, Vol.213, p.47(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.neuroscience.2012.03.050 Byline: A. Martin (a), E. SAN Sebastian (b), V. Gomez-Vallejo (c), J. Llop (c) Keywords: [.sup.13N]ammonia; [ 13 N ] NH 4 + ; PET; brain perfusion; stroke; cerebral ischemia Abbreviations: PET, positron emission tomography; MCA, middle cerebral artery; CCA, common carotid artery; ROIs, regions of interest; MRI, magnetic resonance imaging Abstract: a* PET with [13.sup.N] NH.sub.4.sup.+ evidenced brain-blood hyperperfusion after experimental stroke. a* Brain hyperperfusion was observed in both infarcted and remote regions. a* [13.sup.N] NH.sub.4.sup.+ is a useful biomarker to monitor hemodynamic changes after ischemia. a* These results may contribute to understand the evolution of cerebral ischemia. Author Affiliation: (a) Molecular Imaging Unit, CIC biomaGUNE, Spain (b) Imaging Analytics, Molecular Imaging Unit, CIC biomaGUNE, Spain (c) Radiochemistry, Molecular Imaging Unit, CIC biomaGUNE, Spain Article History: Accepted 20 March 2012
    Keywords: Evolution (Biology) ; Ammonia ; Neurosciences ; Ischemia
    ISSN: 0306-4522
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Neuroscience, 28 June 2012, Vol.213, pp.47-53
    Description: ► PET with evidenced brain–blood hyperperfusion after experimental stroke. ► Brain hyperperfusion was observed in both infarcted and remote regions. ► is a useful biomarker to monitor hemodynamic changes after ischemia. ► These results may contribute to understand the evolution of cerebral ischemia. It is well known that after cerebral ischemia, brain suffers blood flow changes over time that have been correlated with inflammation, angiogenesis and functional recovery processes. Nevertheless, post-ischemic spatiotemporal changes of brain perfusion have not been fully investigated to date. Here we tested whether PET with [ N]ammonia would evidence the perfusion changes presented by different brain regions in an experimental model of brain ischemia. Seven rats were subjected to a 2-h transient middle cerebral artery occlusion with reperfusion. PET studies were performed longitudinally using [ N]ammonia at 1, 3, 7, 14, 21 and 28 days after cerebral ischemia. PET imaging showed a significant increase in [ N]ammonia uptake at 7 days after cerebral ischemia with respect to one day after the occlusion in the cerebral territory irrigated by the MCA in both the ischemic and contralateral hemispheres. This increase was followed by a return to control values at day 28 after ischemia onset. Brain regions located both inside and outside the primary infarct areas showed similar perfusion changes after cerebral ischemia. [ N]ammonia shows hemodynamic changes after stroke involving hyperperfusion that might be related to angiogenesis and functional recovery. Long-term blood hyperperfusion is found both in ischemic and remote areas to infarction. These results may contribute to a better understanding of the evolution of cerebral ischemic lesion in animal models.
    Keywords: [13n]Ammonia ; [Formula Omitted] ; Pet ; Brain Perfusion ; Stroke ; Cerebral Ischemia ; Anatomy & Physiology
    ISSN: 0306-4522
    E-ISSN: 1873-7544
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  • 3
    Language: English
    In: Chemical Communications, 2016, Vol.52(80), pp.11931-11934
    Description: A simple, straightforward and efficient method for the synthesis of [18F]CF4 and [18F]SF6 based on an ion beam-induced isotopic exchange reaction is presented. Positron emission tomography ventilation studies in rodents using [18F]CF4 showed a uniform distribution of the radiofluorinated gas within the lungs and rapid elimination after discontinuation of the administration.
    Keywords: Chemistry;
    ISSN: 1359-7345
    E-ISSN: 1364-548X
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  • 4
    Language: English
    In: Journal of Neuroscience, 04/15/2015, Vol.35(15), pp.5998-6009
    Description: PET imaging of nicotinic acetylcholine receptors (nAChRs) could become an effective tool for the diagnosis and therapy evaluation of neurologic diseases. Despite this, the role of nAChRs α4β2 receptors after brain diseases such as cerebral ischemia and its involvement in inflammatory reaction is still largely unknown. To investigate this, we performed in parallel in vivo magnetic resonance imaging (MRI) and positron emission tomography (PET) with 2[(18)F]-fluoro-A85380 and [(11)C]PK11195 at 1, 3, 7, 14, 21, and 28 d after middle cerebral artery occlusion (MCAO) in rats. In the ischemic territory, PET with 2[(18)F]-fluoro-A85380 and [(11)C]PK11195 showed a progressive binding increase from days 3-7, followed by a progressive decrease from days 14-28 after cerebral ischemia onset. Ex vivo immunohistochemistry for the nicotinic α4β2 receptor and the mitochondrial translocator protein (18 kDa) (TSPO) confirmed the PET findings and demonstrated the overexpression of α4β2 receptors in both microglia/macrophages and astrocytes from days 7-28 after experimental ischemic stroke. Likewise, the role played by α4β2 receptors on neuroinflammation was supported by the increase of [(11)C]PK11195 binding in ischemic rats treated with the α4β2 antagonist dihydro-β-erythroidine hydrobromide (DHBE) at day 7 after MCAO. Finally, both functional and behavioral testing showed major impaired outcome at day 1 after ischemia onset, followed by a recovery of the sensorimotor function and dexterity from days 21-28 after experimental stroke. Together, these results suggest that the nicotinic α4β2 receptor could have a key role in the inflammatory reaction underlying cerebral ischemia in rats.
    Keywords: 2[18f]-Fluoro-A85380 ; Pet ; Tspo ; [11c]Pk11195 ; Cerebral Ischemia ; Α4β2 ; Positron-Emission Tomography ; Encephalitis -- Diagnostic Imaging ; Infarction, Middle Cerebral Artery -- Complications ; Receptors, Nicotinic -- Metabolism;
    ISSN: 0270-6474
    E-ISSN: 1529-2401
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  • 5
    Language: English
    In: Neuroscience, 2011, Vol.182, pp.208-216
    Description: Background and purpose: Positron emission tomography (PET) studies in humans have used C-flumazenil (FMZ) to assess neuronal viability after stroke. Here we aimed to study whether C-FMZ binding was sensitive to neuronal damage in the acute phase following ischemia/reperfusion in the rat brain. Experimental procedures: Transient (2 h followed by reperfusion) and permanent intraluminal middle cerebral artery occlusion was carried out. C-FMZ binding was studied by PET up to 24 h after the onset of ischemia. Tissue infarction was evaluated post-mortem at 24 h. Immunohistochemistry against a neuronal nuclei specific protein (NeuN) was performed to assess neuronal injury. Results: No decrease in C-FMZ binding was detected in the ipsilateral cortex up to 24 h post-ischemia in the model of transient occlusion despite the fact that rats developed cortical and striatal infarction, and neuronal injury was clearly apparent at this time. In contrast, C-FMZ binding was significantly depressed in the ipsilateral cortex at 24 h following permanent ischemia. Conclusions: This finding evidences that C-FMZ binding is not sensitive to neuronal damage on the acute phase of ischemia/reperfusion in the rat brain. ▶We used PET with C-flumazenil to evaluate brain ischemia in rats. ▶ C-flumazenil is not sensitive to neuronal death in transient cerebral ischemia. ▶ C-flumazenil binding was clearly altered in animals subjected to permanent ischemia. ▶With reperfusion, C-flumazenil bound even in the pannecrotic infracted brain. ▶Our results contrast with previous published descriptive studies in humans.
    Keywords: 11c-Flumazenil ; Pet ; Central Benzodiazepine Receptors ; Stroke ; Infarction ; Middle Cerebral Artery Occlusion ; Anatomy & Physiology
    ISSN: 0306-4522
    E-ISSN: 1873-7544
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  • 6
    Language: English
    In: Journal of Controlled Release, 28 September 2015, Vol.214, pp.76-84
    Description: Highly aggressive cancer types such as pancreatic cancer possess a mortality rate of up to 80% within the first 6 months after diagnosis. To reduce this high mortality rate, more sensitive diagnostic tools allowing an early stage medical imaging of even very small tumours are needed. For this purpose, magnetic, biodegradable nanoparticles prepared using recombinant human serum albumin (rHSA) and incorporated iron oxide (maghemite, -Fe O ) nanoparticles were developed. Galectin-1 has been chosen as target receptor as this protein is upregulated in pancreatic cancer and its precursor lesions but not in healthy pancreatic tissue nor in pancreatitis. Tissue plasminogen activator derived peptides (t-PA-ligands), that have a high affinity to galectin-1 have been chosen as target moieties and were covalently attached onto the nanoparticle surface. Improved targeting and imaging properties were shown in mice using single photon emission computed tomography–computer tomography (SPECT–CT), a handheld gamma camera, and magnetic resonance imaging (MRI).
    Keywords: Rhsa Nanoparticles ; Maghemite ; T-PA-Ligands to Galectins ; T-Papeptide1lac ; Single Photon Emission Computed Tomography–Computer Tomography (Spect–CT) ; Handheld Gamma Camera ; Magnetic Resonance Imaging (Mri) ; Pharmacy, Therapeutics, & Pharmacology
    ISSN: 0168-3659
    E-ISSN: 1873-4995
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  • 7
    Language: English
    In: RSC Advances, 2016, Vol.6(111), pp.109633-109638
    Description: The use of the positron emitter nitrogen-13 ( 13 N) has been historically restricted due to its short half-life ( T 1/2 = 9.97 min). However, its stable isotopes (nitrogen-14 and nitrogen-15) are present in many biologically active molecules; therefore, the incorporation of 13 N in the toolbox of PET chemists might be a valuable option for the preparation of new labelled compounds or incorporation of the label in different positions. Here we present the unprecedented radiosynthesis of 13 N-labelled polysubstituted triazoles via Huisgen cycloaddition by reaction of 13 N-labelled aromatic azides with alkyne derivatives and aldehydes. Six different 13 N-labelled triazoles were successfully synthesized. After automatization of the synthetic process and optimization of experimental conditions, one selected triazole could be prepared with high radiochemical purity and decay-corrected radiochemical yields of 11 2%. The amount of activity obtained should be sufficient to approach future in vitro and in vivo studies. The novel methodology might open new avenues for the preparation of radiotracers which cannot be labelled using other more conventional positron emitters.
    ISSN: RSC Advances
    E-ISSN: 2046-2069
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  • 8
    Language: English
    In: Dalton transactions (Cambridge, England : 2003), 07 June 2015, Vol.44(21), pp.9915-20
    Description: Due to their high boron content and rich chemistry, dicarba-closo-dodecaboranes (carboranes) are promising building blocks for the development of drug candidates with application in Boron Neutron Capture Therapy. However, the non-invasive determination of their pharmacokinetic properties to predict therapeutic efficacy is still a challenge. Herein, we have reported the unprecedented preparation of mono-[(125)I] iodinated decaborane via a catalyst-assisted isotopic exchange. Subsequent reactions of the radiolabelled species with acetylenes in acetonitrile under microwave heating yield the corresponding (125)I-labelled, Cc-substituted o-carboranes with good overall radiochemical yields in short reaction times. The same synthetic strategy was successfully applied to the preparation of (131)I-labelled analogues, and further extension to other radioisotopes of iodine such as (124)I (positron emitter) or (123)I (gamma emitter) can be envisaged. Hence, the general strategy reported here is suitable for the preparation of a wide range of radiolabelled Cc-substituted o-carborane derivatives. The labelled compounds might be subsequently investigated in vivo by using nuclear imaging techniques such as Single Photon Emission Computerized Tomography or Positron Emission Tomography.
    Keywords: Boranes -- Chemistry ; Iodine Radioisotopes -- Chemistry ; Radiopharmaceuticals -- Chemistry
    ISSN: 14779226
    E-ISSN: 1477-9234
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  • 9
    Language: English
    In: Chemical communications (Cambridge, England), 29 September 2016, Vol.52(80), pp.11931-11934
    Description: A simple, straightforward and efficient method for the synthesis of [F]CF and [F]SF based on an ion beam-induced isotopic exchange reaction is presented. Positron emission tomography ventilation studies in rodents using [F]CF showed a uniform distribution of the radiofluorinated gas within the lungs and rapid elimination after discontinuation of the administration.
    E-ISSN: 1364-548X
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 10
    Language: English
    In: Journal of Materials Chemistry B, 2017, Vol.5(6), pp.1143-1147
    Description: Water-dispersible dextran-based single-chain polymer nanoparticles (SCPNs) were prepared in aqueous media and under mild conditions. Radiolabeling of the resulting biocompatible materials allowed the study of lung deposition of aqueous aerosols after intratracheal nebulization...
    Keywords: Aerosols ; Media ; Tomography ; Deposition ; Synthesis ; Nanoparticles ; Emission Analysis ; Biology ; Miscellaneous Sciences (So) ; Chemical and Electrochemical Properties (MD) ; Chemical and Electrochemical Properties (Ep) ; Chemical and Electrochemical Properties (Ed) ; Chemical and Electrochemical Properties (EC);
    ISSN: 2050-750X
    E-ISSN: 2050-7518
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