Rosa Maria Moresco

A voxel-based PET study of dopamine transporters in Parkinson's disease: relevance of age at onset.

We used positron emission tomography (PET) and the dopamine transporter (DAT) ligand [(11)C]FECIT to measure loss of nigrostriatal dopaminergic neurons in early phase of early onset (EOPD) and late onset Parkinsons disease (LOPD). The analysis was carried out with both regions of interest and voxelwise method (SPM2), at group and single subject levels. Genetic analysis tested for the mutations occurring most frequently in Caucasian population. A significant, bilateral, asymmetric DAT reduction was observed in both EOPD and LOPD. Noteworthy, the side and severity of DAT binding reduction significantly correlated with the severity and asymmetry of motor clinical scores. The two EOPD patients carrying mutations in the PARK2 and PARK6 genes, respectively, displayed the lowest values, bilaterally. This work demonstrates that severity of nigrostriatal damage in early disease phase of sporadic PD is not dependent on age at onset. Genetically determined PD is associated with more severe and widespread dopaminergic impairment.

Time course of metabolic activity and cellular infiltration in a murine model of acid-induced lung injury

PurposeThis study investigates whether positron emission tomography (PET) can be used to monitor the inflammatory response and its correlation with the later fibroproliferative phase in an experimental model of acute lung injury.MethodsHydrochloric acid (0.1xa0N, pH 1, 1.5xa0ml/kg) was instilled into the right bronchus of mice. A group of mice underwent a micro-computed tomography (CT) scan 1xa0h after lung injury and a series of 2-[18F]fluorine-2-deoxy-d-glucose (FDG)-PET scans (6, 24 and 48xa0h and 7xa0days after surgery). After 21xa0days respiratory static compliance was assessed and lung tissue was collected in order to measure the hydroxy (OH)-proline content. Other groups of mice underwent micro-CT and micro-PET scans at the same time points, and then were immediately killed to assess arterial blood gases and histology.ResultsHistological analysis showed the recruitment of neutrophils and macrophages into the damaged lung, reaching the peak at 24 and 48xa0h, respectively. The time course of the [18F]FDG signal, used as a marker of inflammation, correlated with that of recruited inflammatory cells. In mice killed 21xa0days after the surgery, a correlation was found between reduced respiratory static compliance and high PET signal 7xa0days after lung injury. The PET signal also correlated with the OH-proline content.ConclusionsThis study demonstrated that PET imaging is a valid means of tracking the inflammatory response, also in longitudinal studies. Moreover, a correlation was found between persistence of the inflammatory response and fibrotic evolution of the injury.

Asymmetric synthesis and preliminary evaluation of (R)- and (S)-[11C]bisoprolol, a putative β1-selective adrenoceptor radioligand

(+/-)-1-[4-(2-Isopropoxyethoxymethyl)-phenoxy]-3-isopropylamino-2-propanol (bisoprolol) is a potent, clinically used beta(1)-adrenergic agent. (R)-(+) and (S)-(-) enantiomers of bisoprolol were labelled with carbon-11 (t(1/2)=20.4 min) as putative tracers for the non-invasive assessment of the beta(1)-adrenoceptor subtype in the human heart and brain with positron emission tomography (PET). The radiosynthesis consisted of reductive alkylation of des-iso-propyl precursor with [2-11C]acetone in the presence of sodium cyanoborohydride and acetic acid. The stereo-conservative synthesis of (R)-(+) and (S)-(-)-1-[4-(2-isopropoxyethoxymethyl)-phenoxy]-3-amino-2-propanol to be used as the precursors for the radiosynthesis of [11C]bisoprolol enantiomers was readily accomplished by the use of the corresponding chiral epoxide in three steps starting from the commercially available hydroxybenzyl alcohol. The final labelled product (either (+) or (-)-1-[4-(-isopropoxyethoxymethyl)-phenoxy]-3- [11C]isopropylamino-2-propanol) was obtained in 99% radiochemical purity in 30 min with 15+/-5% (EOS, non-decay corrected) radiochemical yield and 3.5+/-1 Ci/micromol specific radioactivity. Preliminary biological evaluation of the tracer in rats showed that about 30% of heart uptake of [11C](S)-bisoprolol is due to specific binding. The high non-specific uptake in lung might mask the heart uptake, thus precluding the use of [11C](S)-bisoprolol for heart and lung studies by PET. The remarkably high uptake of the tracer in rat brain areas rich of beta-adrenergic receptors such as pituitary (1.8+/-0.3% I.D. at 30 min) was blocked by pre-treatment with the beta-adrenergic antagonists propranolol (45%) and bisoprolol (51%, p<0.05). [11C](S)-bisoprolol deserves further evaluation in other animal models as a putative beta(1) selective radioligand for in vivo investigation of central adrenoceptors.

Synthesis and in vivo evaluation of [11C]CGP62349, a new GABAB receptor antagonist

Abstract This paper describes the radiosynthesis of [11C]CGP62349, a potential ligand to assess GABAB receptors in vivo. 11C was introduced by O-methylation of the corresponding des-methyl precursor, namely CGP67780. The final product was obtained with a reliable method in good yield. The radioligand was tested in monkey, revealing negligible blood-brain barrier penetration and brain uptake, thus prompting us to search for a new target structure with a better lipophilicity.

Synthesis and in vivo evaluation of 3‐[11C]methyl‐(3‐methoxy‐naphthalen)‐2‐yl‐(1‐benzyl‐piperidin)‐4‐yl‐acetate (SB‐235753), as a putative dopamine D4 receptors antagonist for PET

(3-Methoxy-naphthalen)2-yl-(1-benzyl-piperidin)4-yl-acetate (SB-235753) was labelled with 11C (t1/2=20·4 min) as a putative radioligand for the non-invasive assessment of Dopamine D4 receptors in vivo with positron emission tomography (PET). n n n nThe precursor for the radiosynthesis 3-hydroxynaphthyl-2-[N-benzyl)-piperidyl]-acetate hydrochloride was prepared by a four-step synthesis starting from ethyl-4-pyridyl acetate. The radiolabelling consisted of methylation with [11C]methyltriflate in dimethylformamide in the presence of potassium hydroxide. [11C]SB-235753, was synthesised in 30 min with a radiochemical yield of 10±5% (EOS, non-decay corrected) with 99% radiochemical purity and specific radioactivity of 10±3 Ci/μmol. n n n nBiodistribution studies in rats with [11C]SB-235753 showed the uniform distribution of the tracer within different areas of the murine brain. At 30 min after injection 99% of the radioligand in plasma and 100% in cerebellum was metabolised. These findings suggest that [11C]SB-235753 can not be a suitable tracer for dopamine D4 receptor studies with PET. Copyright

Synthesis and in vivo evaluation of [11C]ICI 118551 as a putative subtype selective β2-adrenergic radioligand

Erytro-(+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[ iso-propylamino]-2-butanol (ICI 118551) a potent clinically used beta2 adrenergic antagonist, was labelled with carbon-11 (t1/2 = 20.4 min) as a potential radioligand for the non-invasive assessment of beta2 adrenergic receptors in the lung with positron emission tomography (PET). The radiolabelled compound was prepared by reductive N-alkylation of its des-isopropyl precursor with [2-11C]acetone. (+/-)-[11C]ICI 118551 was obtained in greater than 98% radiochemical purity in 30 min with a radiochemical yield of 15 + 5% (non-decay corrected) and a specific radioactivity 2.5 +/- 0.5 Ci/micromol. The biological evaluation of racemic erythro (+/-)-[11C]ICI 118551 in rats and Macaca Nemestrina shows a high radioactivity uptake in lung and heart. However, in both animal models no detectable displacement of lung radioactivity concentration was observed after pre-treatment with propranolol or ICI 118551, which indicates that in this organ, radioligand uptake is mostly due to non-specific binding. The biological data suggest that erythro (+/-)-[11C]ICI 118551 is not adequate to be further developed as a tracer for beta2 adrenergic receptor imaging in vivo.

Leukocytes recruited by tumor-derived HMGB1 sustain peritoneal carcinomatosis

ABSTRACT The factors that determine whether disseminated transformed cells in vivo yield neoplastic lesions have only been partially identified. We established an ad hoc model of peritoneal carcinomatosis by injecting colon carcinoma cells in mice. Tumor cells recruit inflammatory leukocytes, mostly macrophages, and generate neoplastic peritoneal lesions. Phagocyte depletion via clodronate treatment reduces neoplastic growth. Colon carcinoma cells release a prototypic damage-associated molecular pattern (DAMP)/alarmin, High Mobility Group Box1 (HMGB1), which attracts leukocytes. Exogenous HMGB1 accelerates leukocyte recruitment, macrophage infiltration, tumor growth and vascularization. Lentiviral-based HMGB1 knockdown or pharmacological interference with its extracellular impair macrophage recruitment and tumor growth. Our findings provide a preclinical proof of principle that strategies based on preventing HMGB1-driven recruitment of leukocytes could be used for treating peritoneal carcinomatosis.

[11C]RN5: A new agent for the in vivo imaging of myocardial α1-adrenoceptors

Abstract The radiolabelling with the positron-emitter Carbon-11 and the biological evaluation in rats of 3-[2-[4-(2-[ 11 C]methoxyphenyl)piperazin-1-yl]ethyl]pyrimido[5,4- b ]indole-2,4-dione ([ 11 C]RN5), α 1 -adrenoceptor antagonist ( K i =0.21 nM), as a putative radioligand for the non-invasive assessment of α 1 -adrenoceptors with positron emission tomography (PET) is reported. The radiosynthesis procedure consisted of O -methylation of des -methyl precursor with [ 11 C]methyl iodide in the presence of potassium hydroxide in dimethylformamide (DMF) at 80 °C. [ 11 C]RN5 was obtained in >99% radiochemical purity in 25 min with a radiochemical yield in the 20–30% range, end of synthesis (EOS) (non-decay corrected) and a specific radioactivity of 92.5±18.5 GBq/μmol. Pre-clinical studies in rats showed a high uptake of [ 11 C]RN5 in heart, spleen, adrenal gland, lung and kidney but not in the brain. Inhibition studies with high doses of different adrenergic antagonists indicate that more than 70% of myocardial uptake of [ 11 C]RN5 is due to specific binding to α 1 -adrenoceptors. Our results indicate that [ 11 C]RN5 is suitable to be further developed as a potential radioligand for the in vivo PET imaging of myocardial α 1 -adrenoceptors in humans.

Identification of imaging biomarkers for the assessment of tumour response to different treatments in a preclinical glioma model

PurposeHypoxia-inducible factor 1α (HIF-1α) activity is one of the major players in hypoxia-mediated glioma progression and resistance to therapies, and therefore the focus of this study was the evaluation of HIF-1α modulation in relation to tumour response with the purpose of identifying imaging biomarkers able to document tumour response to treatment in a murine glioma model.MethodsU251-HRE-mCherry cells expressing Luciferase under the control of a hypoxia responsive element (HRE) and mCherry under the control of a constitutive promoter were used to assess HIF-1α activity and cell survival after treatment, both in vitro and in vivo, by optical, MRI and positron emission tomography imaging.ResultsThis cell model can be used to monitor HIF-1α activity after treatment with different drugs modulating transduction pathways involved in its regulation. After temozolomide (TMZ) treatment, HIF-1α activity is early reduced, preceding cell cytotoxicity. Optical imaging allowed monitoring of this process in vivo, and carbonic anhydrase IX (CAIX) expression was identified as a translatable non-invasive biomarker with potential clinical significance. A preliminary in vitro evaluation showed that reduction of HIF-1α activity after TMZ treatment was comparable to the effect of an Hsp90 inhibitor, opening the way for further elucidation of its mechanism of action.ConclusionThe results of this study suggest that the U251-HRE-mCherry cell model can be used for the monitoring of HIF-1α activity through luciferase and CAIX expression. These cells can become a useful tool for the assessment and improvement of new targeted tracers for potential theranostic procedures.

A novel AMPK activator reduces glucose uptake and inhibits tumor progression in a mouse xenograft model of colorectal cancer.

SummaryThe anticancer activity of a novel pure 1,4-Diaryl-2-azetidinone (1), endowed with a higher solubility than the well known Combretastatin A4, is tested in mice. We previously reported that Compound (1) showed specific antiproliferative activity against duodenal and colon cancer cells, inducing activation of AMP-activated protein kinase and apoptosis. Here we estimate that the maximum tolerated dose in a mouse model is 40xa0mg/kg; the drug is well tolerated both in single dose and in repeated administration schedules. The drug displays a significant antitumor activity and a tumor growth delay when administered at the MTD both in single and fractionated i.v. administration in a mouse xenograft model of colorectal cancer. Arrest of tumor growth and relapse after drug suspension are parallel to modification in glucose demand as shown by PET studies with [18u2009F] FDG. These data strongly support Compound (1) as a promising molecule for in vivo treatment of colorectal cancer.