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Introduction: Radiolabeled phosphatidylserine (PS)-binding peptides represent an innovative strategy for molecular imaging of apoptosis with positron emission tomography (PET). The goal of this study was the radiopharmacological evaluation of radiolabeled peptides for their binding to PS on apoptotic cancer cells, involving metabolic stability, cellular uptake, biodistribution, and dynamic PET imaging experiments., Methods: Binding of peptides LIKKPF, PGDLSR, FBz-LIKKPF, FBz-PGDLSR, FBAM-CLIKKPF and FBAM-CPGDLSR to PS was analyzed in a newly developed radiometric binding assay using (64)Cu-labeled wild-type annexin-V as radiotracer. Radiolabeling of most potent peptides with fluorine-18 was carried out with thiol-selective prosthetic group [(18)F]FBAM to give [(18)F]FBAM-CLIKKPF and [(18)F]FBAM-CPGDLSR. [(18)F]FBAM-labeled peptides were studied in camptothecin-induced apoptotic human T lymphocyte Jurkat cells, and in a murine EL4 tumor model of apoptosis using dynamic PET imaging and biodistribution., Results: Peptides LIKKPF and PGDLSR inhibited binding of (64)Cu-labeled annexin-V to immobilized PS in the millimolar range (IC50 10-15 mM) compared to annexin-V (45 nM). Introduction of FBAM prosthetic group slightly increased inhibitory potencies (FBAM-CLIKKPF: IC50 = 1 mM; FBAM-CPGDLSR: IC50 = 6 mM). Radiolabeling succeeded in good radiochemical yields of 50-54% using a chemoselective alkylation reaction of peptides CLIKKPF and CPGDLSR with [(18)F]FBAM. In vivo metabolic stability studies in mice revealed 40-60% of intact peptides at 5 min p.i. decreasing to 25% for [(18)F]FBAM-CLIKKPF and less than 5% for [(18)F]FBAM-CPGDLSR at 15 min p.i.. Cell binding of [(18)F]FBAM-CLIKKPF in drug-treated Jurkat cells was significantly higher compared to untreated cells, but this was not observed for [(18)F]FBAM-CPGDLSR. Dynamic PET imaging experiments showed that baseline uptake of [(18)F]FBAM-CLIKKPF in EL4 tumors was higher (SUV(5min) 0.46, SUV(60min) 0.13) compared to [(18)F]FBAM-CPGDLSR (SUV(5min) 0.16, SUV(60min) 0.10). Drug-treated EL4 tumors did not show an increased uptake for both [(18)F]FBAM-labeled peptides., Conclusion: Although both (18)F-labeled peptides [(18)F]FBAM-CLIKKPF and [(18)F]FBAM-CPGDLSR showed higher binding to apoptotic Jurkat cells in vitro, their in vivo uptake profiles were not different in apoptotic EL4 tumors. This may explained by the relatively low potency of both compounds to compete with binding of (64)Cu-labeled annexin-V to PS. Overall the novel competitive radiometric PS-binding assay with (64)Cu-labeled annexin-V represents a versatile and very robust screening platform to analyze potential PS-binding compounds in vitro. Further studies will be necessary to evaluate alternative peptide structures toward their use as PET radiotracers imaging apoptosis in vivo., Advances in Knowledge and Implications for Patient Care: Development of peptide-based radiotracers for imaging apoptosis in vivo remains a significant challenge., (Copyright © 2015 Elsevier Inc. All rights reserved.)

A series of novel fluorine-containing cyclooxygenase-2 (COX-2) inhibitors was designed and synthesized based on the previously reported fluorescent COX-2 imaging agent celecoxib-NBD (3; NBD=7-nitrobenzofurazan). In vitro COX-1/COX-2 inhibitory data show that N-(4-fluorobenzyl)-4-(5-p-tolyl-3-trifluoromethylpyrazol-1-yl)benzenesulfonamide (5; IC50 =0.36 μM, SI>277) and N-fluoromethyl-4-(5-p-tolyl-3-trifluoromethylpyrazol-1-yl)benzenesulfonamide (6; IC50 =0.24 μM, SI>416) are potent and selective COX-2 inhibitors. Compound 5 was selected for radiolabeling with the short-lived positron emitter fluorine-18 ((18) F) and evaluated as a positron emission tomography (PET) imaging agent. Radiotracer [(18) F]5 was analyzed in vitro and in vivo using human colorectal cancer model HCA-7. Although radiotracer uptake into COX-2-expressing HCA-7 cells was high, no evidence for COX-2-specific binding was found. Radiotracer uptake into HCA-7 tumors in vivo was low and similar to that of muscle, used as reference tissue., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Introduction: Lysyl oxidase (LOX; ExPASy ENZYME entry: EC 1.4.3.13) and members of the LOX-like family, LOXL1-LOXL4, are copper-dependent enzymes that can modify proteins of the extracellular matrix. Expression of LOX is elevated in many human cancers, including breast cancer. LOX expression correlates with the level of tissue hypoxia, and it is known to play a critical role in breast cancer metastasis. The goal of the present study was to target LOX with (1) molecular probe fluorescent labeling to visualize LOX in vitro and (2) a radiolabeled peptide to target LOX in vivo in three different preclinical models of breast cancer., Methods: Gene expression of all five members of the LOX family was analyzed at the transcript level via microarray analysis using tissue biopsy samples from 176 patients with breast cancer. An oligopeptide sequence (GGGDPKGGGGG) was selected as a substrate-based, LOX-targeting structure. The peptide was labeled with fluorescein isothiocyanate (FITC) for confocal microscopy experiments with the murine breast cancer cell line EMT-6. In vivo molecular imaging experiments were performed using a C-terminal amidated peptide, GGGDPKGGGGG, labeled with a short-lived positron emitter, fluorine-18 ((18)F), for positron emission tomography (PET) in three different breast cancer models: EMT6, MCF-7 and MDA-MB-231. The PET experiments were carried out in the presence or absence of β-aminopropionitrile (BAPN), an irreversible inhibitor of LOX., Results: Immunostaining experiments using a LOX-specific antibody on EMT-6 cells cultured under hypoxic conditions confirmed the elevation of LOX expression in these cells. An FITC-labeled oligopeptide, FITC-Ava-GGGDPKGGGGG-NH2, was found to be localized in different cellular compartments under these conditions. After injection of [(18)F]fluorobenzoate-GGGDPKGGGGG-NH2, radioactivity uptake was visible in all three breast cancer models in vivo. Tumor uptake was reduced by predosing the animals with 2 mg of BAPN 4 h or 24 h before injection of the radiotracer., Conclusions: The present data support further investigation into the development of LOX-binding radiolabeled peptides as molecular probes for molecular imaging of LOX expression in cancer.

Current translational cancer research is directed to the development of high affinity peptide ligands for targeting neuropeptide receptors overexpressed in different types of cancer. Besides their desired high binding affinity to the receptor, the suitability of radiolabeled peptides as targeting vectors for molecular imaging and therapy depends on additional aspects such as high tumor-to-background ratio, favorable clearance pattern from nontarget tissue, and sufficient metabolic stability in vivo. This study reports how a switch from the prosthetic group, N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB), to 2-deoxy-2-[(18)F]fluoro-d-glucose ([(18)F]FDG) effects the metabolic pathway of an (18)F-labeled bombesin derivative, QWAV-Sar-H-FA01010-Tle-NH2. (18)F-Labeled bombesin derivatives represent potent peptide ligands for selective targeting of gastrin-releasing peptide (GRP) receptor-expressing prostate cancer. Radiosynthesis of (18)F-labeled bombesin analogues [(18)F]FBz-Ava-BBN2 and [(18)F]FDG-AOAc-BBN2 was achieved in good radiochemical yields of ~50% at a specific activity exceeding 40 GBq/μmol. Both nonradioactive compounds FBz-Ava-BBN2 and FDG-AOAc-BBN2 inhibited binding of [(125)I]Tyr(4)-bombesin(1-14) in PC3 cells with IC50 values of 9 and 16 nM, respectively, indicating high inhibitory potency. Influence of each prosthetic group was further investigated in PC3 mouse xenografts using dynamic small animal PET imaging. In comparison to [(18)F]FBz-Ava-BBN2, total tumor uptake levels were doubled after injection of [(18)F]FDG-AOAc-BBN2 while renal elimination was increased. Blood clearance and in vivo metabolic stability were similar for both compounds. The switch from [(18)F]SFB to [(18)F]FDG as the prosthetic group led to a significant reduction in lipophilicity which resulted in more favorable renal clearance and increased tumor uptake. The presented single step radiolabeling-glycosylation approach represents an innovative strategy for site-directed peptide labeling with the short-lived positron emitter (18)F while providing a favorable pharmacokinetic profile of (18)F-labeled peptides.

Background: Epithelial ovarian cancer (EOC) is characterized by the overexpression of cancer antigen 125 (CA125), a mucinous glycoprotein that serves as a tumor biomarker. Early diagnosis of EOC is plagued by its asymptomatic nature of progression and the limitations of currently used immunoassay techniques that detect CA125 as a shed antigen in serum samples. Presently, there is no technique available for the in vivo evaluation of CA125 expression in malignant tissues. Moreover, there could be an unexplored pathophysiological time window for the detection of CA125 in EOC, during which it is expressed on tumor cells prior to being shed into the bloodstream. A method for the in vivo evaluation of CA125 expression on ovarian neoplasms earlier along disease progression and/or recurrence can potentially contribute to better disease management. To this end, the present work utilizes an anti-CA125 monoclonal antibody (MAb) and a single-chain variable fragment (scFv) labeled with the positron-emitting radionuclide (64)Cu for preclinical molecular imaging of CA125 expression in vivo., Methods: Anti-CA125 MAb and scFv were prepared and functionally characterized for target binding prior to being tested as radiotracers in a preclinical setting., Results: Immunoblotting, immunofluorescence, and flow cytometry revealed specific binding of CA125-targeting vectors to NIH:OVCAR-3 cells and no binding to antigen-negative SKOV3 cells. (64)Cu-labeled anti-CA125 MAb and scFv were obtained in specific activities of 296 and 122 MBq/mg, respectively. Both radioimmunoconjugate vectors demonstrated highly selective binding to NIH:OVCAR-3 cells and virtually no binding to SKOV3 cells. In vivo radiopharmacological evaluation using xenograft mouse models injected with (64)Cu-labeled anti-CA125 MAb provided a standardized uptake value (SUV) of 5.76 (29.70 %ID/g) in OVCAR3 tumors 24 h post-injection (p.i.) versus 1.80 (5.91 %ID/g) in SKOV3 tumors. (64)Cu-labeled anti-CA125 scFv provided an SUV of 0.64 (3.21 %ID/g) in OVCAR3 tumors 24 h p.i. versus 0.25 (1.49 %ID/g) in SKOV3 tumors. Results from small-animal PET imaging were confirmed by ex vivo autoradiography and immunohistochemistry., Conclusions: Radiolabeling of anti-CA125 MAb and scFv with (64)Cu did not compromise their immunoreactivity. Both radioimmunoconjugates presented specific tumor uptake and expected biological clearance profiles. This renders them as potential immuno-PET probes for targeted in vivo molecular imaging of CA125 in EOC.

Background: The multitargeting tyrosine kinase inhibitor (TKI) sunitinib is currently the first-line drug therapy for metastasizing renal cell carcinoma (RCC). TKIs have profound effects on tumor angiogenesis, leading to modifications of the tumor microenvironment. The goal of this study was to determine whether these treatment-induced changes can be detected with [(18)F]FAZA., Methods: The present study utilized positron emission tomography (PET) to analyze tumor oxygenation status during and after sunitinib therapy in the murine Caki-1 RCC tumor model. Dynamic and static scans were performed, as well as ex vivo biodistributions at 3 h post injection (p.i.). Immunohistochemical analysis of tumor tissue was carried out for the quantification of pimonidazole binding and the hypoxia-associated factors CD-31, Ki-67, and Von Willebrand factor (VWF). In addition, in vitro cellular uptake studies were done to analyze the direct effects of sunitinib on the Caki-1 cells., Results: During therapy with sunitinib (40 mg/kg/day), uptake of [(18)F]FAZA into Caki-1 mice decreased by 46 ± 5% (n = 4; 5 days) at 3 h post injection (p.i.) during the first study and 22 ± 5% (n = 8; 9 days) during the long-term study, indicating a decrease in the tumor's hypoxia level. However, when drug therapy was stopped, this effect was reversed completely, and the tumor [(18)F]FAZA uptake increased to 126 ± 6% (n = 6) of the control tumor uptake, indicative of an even higher level of tumor hypoxia compared to the therapy starting point. Sunitinib had no direct effect on [(18)F]FAZA uptake into Caki-1 cells in vitro., Conclusion: [(18)F]FAZA PET could be used to monitor drug response during sunitinib therapy in RCC and may guide combination therapies based on the tumor's hypoxia status.

Introduction: (18)F-labeled amino acids are important PET radiotracers for molecular imaging of cancer. This study describes synthesis and radiopharmacological evaluation of 2-amino-5-(4-[(18)F]fluorophenyl)pent-4-ynoic acid ([(18)F]FPhPA) as a novel amino acid radiotracer for oncologic imaging., Methods: (18)F]FPhPA was prepared using Pd-mediated Sonogashira cross-coupling reaction between 4-[(18)F]fluoroiodobenzene ([(18)F]FIB) and propargylglycine. The radiopharmacological profile of [(18)F]FPhPA was evaluated in comparison with O-(2-[(18)F]fluoroethyl)-L-tyrosine ([(18)F]FET) using the murine breast cancer cell line EMT6 involving cellular uptake studies, radiotracer uptake competitive inhibition experiments and small animal PET imaging., Results: (18)F]FPhPA was prepared in 42±10% decay-corrected radiochemical yield with high radiochemical purity >95% after semi-preparative HPLC purification. Cellular uptake of L-[(18)F]FPhPA reached a maximum of 58±14 % radioactivity/mg protein at 90 min. Lower uptake was observed for racemic and D-[(18)F]FPhPA. Radiotracer uptake inhibition studies by synthetic and naturally occurring amino acids suggested that Na(+)-dependent system ASC, especially ASCT2, and Na(+)-independent system L are important amino acid transporters for [(18)F]FPhPA uptake into EMT6 cells. Small animal PET studies demonstrated similar high tumor uptake of [(18)F]FPhPA in EMT6 tumor-bearing mice compared to [(18)F]FET reaching a maximum standardized uptake value (SUV) of 1.35 after 60 min p.i.. Muscle uptake of [(18)F]FPhPA was higher (SUV30min=0.65) compared to [(18)F]FET (SUV30min=0.40), whereas [(18)F]FPhPA showed a more rapid uptake and clearance from the brain compared to [(18)F]FET., Conclusion: L-[(18)F]FPhPA is the first (18)F-labeled amino acid prepared through Pd-mediated cross-coupling reaction., Advances in Knowledge and Implications for Patient Care: L-[(18)F]FPhPA displayed promising properties as a novel amino acid radiotracer for molecular imaging of system ASC and system L amino acid transporters in cancer., (Copyright © 2014 Elsevier Inc. All rights reserved.)

6-Deoxy-6-[(18)F]fluoro-D-fructose (6-[(18)F]FDF) is a promising PET radiotracer for imaging GLUT5 in breast cancer. The present work describes GMP synthesis of 6-[(18)F]FDF in an automated synthesis unit (ASU) and dosimetry calculations to determine radiation doses in humans. GMP synthesis and dosimetry calculations are important prerequisites for first-in-human clinical studies of 6-[(18)F]FDF. The radiochemical synthesis of 6-[(18)F]FDF was optimized and adapted to an automated synthesis process using a Tracerlab FXFN ASU (GE Healthcare). Starting from 30 GBq of cyclotron-produced n.c.a. [(18)F]fluoride, 2.9 ± 0.1 GBq of 6-[(18)F]FDF could be prepared within 50 min including HPLC purification resulting in an overall decay-corrected radiochemical yield of 14 ± 3% (n = 11). Radiochemical purity exceeded 95%, and the specific activity was greater than 5.1 GBq/μmol. Sprague-Dawley rats were used for biodistribution experiments, and dynamic and static small animal PET experiments. Biodistribution studies served as basis for allometric extrapolation to the standard man anatomic model and normal organ-absorbed dose calculations using OLINDA/EXM software. The calculated human effective dose for 6-[(18)F]FDF was 0.0089 mSv/MBq. Highest organ doses with a dose equivalent of 0.0315 mSv/MBq in a humans were found in bone. Injection of 370 MBq (10 mCi) of 6-[(18)F]FDF results in an effective whole body radiation dose of 3.3 mSv in humans, a value comparable to that of other (18)F-labeled PET radiopharmaceuticals. The optimized automated synthesis under GMP conditions, the good radiochemical yield and the favorable human radiation dosimetry estimates support application of 6-[(18)F]FDF in clinical trials for molecular imaging of GLUT5 in breast cancer patients.

Cyclooxygenase (COX) is the key enzyme within the complex conversion of arachidonic acid into prostaglandins (PGs). Inhibitors of this enzyme represent a particularly promising class of compounds for chemoprevention and cancer therapy. The experimental data on the involvement of COX isoform COX-2 in tumour development and progression, as well as the observed overexpression of COX-2 in a variety of human cancers provide the rationale for targeting COX-2 for molecular imaging and therapy of cancer. A series of trifluoromethyl-substituted pyrimidines was prepared as a novel class of selective COX-2 inhibitors, based on the lead structure 1a. All compounds were tested in cyclooxygenase (COX) assays in vitro to determine COX-1 and COX-2 inhibitory potency and selectivity. Molecular docking studies using the catalytic site of COX-1 and COX-2, respectively, provided complementary theoretical support for the obtained experimental biological structure–activity relationship data of three highly potent and selective fluorobenzyl-containing COX-2 inhibitors. Selected fluorobenzyl-substituted pyrimidine derivatives were further developed as (18)F-labelled radiotracers ([(18)F]1a, [(18)F]2a, [(18)F]3a). Radiotracers [(18)F]1a and [(18)F]2a were radiolabelled using 4-[(18)F]fluorobenzylamine ([(18)F]FBA) as a building block. Radiotracer [(18)F]3a was radiofluorinated directly using a nucleophilic aromatic substitution reaction with no-carrier-added (n.c.a.) [(18)F]fluoride on an iodylaryl compound as a labelling precursor.

Objectives: To elucidate the impact of the mucosa on detrusor muscle function by investigating force of contraction under various stimulatory conditions and during subsequent relaxation using catecholamines., Patients and Methods: Detrusor tissue was obtained from patients who had undergone cystectomy for bladder cancer and strips of intact or mucosa-denuded muscle were set up for force measurement. Preparations were precontracted with KCl, carbachol or electric-field stimulation (EFS). Precontracted strips were relaxed using increasing concentrations of catecholamines in the absence and presence of the subtype-selective β-adrenoceptor (AR) blockers CGP 20712A (β1-ARs), ICI 118,551 (β2-ARs), and L-748,337 (β3-ARs)., Results: Force development in response to KCl (40 mM), carbachol (1 μM) or EFS was larger in the absence of mucosa than in intact muscle strips. The force of contraction of mucosa-denuded strips with detached urothelium incubated in the same chamber was as low as in intact strips. Noradrenaline relaxed precontracted detrusor strips to a significantly larger extent and at lower concentrations in denuded than in intact strips. CGP 20712A did not affect noradrenaline-induced relaxation of denuded and intact strips, and ICI 118,551 did not influence noradrenaline-induced relaxation in denuded strips, but abolished the difference between denuded and intact strips. The antagonism of the relaxant effects of noradrenaline by L-748,337 was slightly smaller in intact than denuded strips., Conclusions: The mucosa of human detrusor strips impairs force development when stimulated with KCl, carbachol or EFS. The mucosa also blunts the relaxing effects of catecholamines. The latter effect does not involve the activation of β1-ARs but only of β2-ARs, whereas β3-ARs mediate the relaxation of human detrusor., (© 2013 The Authors. BJU International © 2013 BJU International.)

Introduction: Bombesin (BBN) and BBN analogues have attracted much attention as high-affinity ligands for selective targeting of the gastrin-releasing peptide (GRP) receptor. GRP receptors are overexpressed in a variety of human cancers including prostate cancer. Radiolabeled BBN derivatives are promising diagnostic probes for molecular imaging of GRP receptor-expressing prostate cancer. This study describes the synthesis and radiopharmacological evaluation of various metabolically stabilized fluorobenzoylated bombesin analogues (BBN-1, BBN-2, BBN-3)., Methods: Three fluorobenzoylated BBN analogues containing an aminovaleric (BBN-1, BBN-2), or an aminooctanoic acid linker (BBN-3) were tested in a competitive binding assay against (125)I-[Tyr(4)]-BBN for their binding potency to the GRP receptor. Intracellular calcium release in human prostate cancer cells (PC3) was measured to determine agonistic or antagonistic profiles of fluorobenzoylated BBN derivatives. Bombesin derivative BBN-2 displayed the highest inhibitory potency toward GRP receptor (IC50 = 8.7 ± 2.2 nM) and was subsequently selected for radiolabeling with fluorine-18 ((18)F) through acylation with N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). The radiopharmacological profile of (18)F-labeled bombesin [(18)F]BBN-2 was evaluated in PC3 tumor-bearing NMRI nude mice involving metabolic stability studies, biodistribution experiments and dynamic small-animal PET studies., Results: All fluorobenzoylated BBN derivatives displayed high inhibitory potency toward the GRP receptor (IC50=8.7-16.7 nM), and all compounds exhibited antagonistic profiles as determined in an intracellular calcium release assay. The (18)F-labeled BBN analogue [(18)F]BBN-2 was obtained in 30% decay-corrected radiochemical yield with high radiochemical purity >95% after semi-preparative HPLC purification. [(18)F]BBN-2 showed high metabolic stability in vivo with 65% of the radiolabeled peptide remaining intact after 60 min p.i. in mouse plasma. Biodistribution experiments and dynamic small-animal PET studies demonstrated high tumor uptake of [(18)F]BBN-2 in PC3 xenografts (2.75 ± 1.82 %ID/g after 5 min and 2.45 ± 1.25 %ID/g after 60 min p.i.). Specificity of radiotracer uptake in PC3 tumors was confirmed by blocking experiments., Conclusion: The present study demonstrates that (18)F-labeled BBN analogue [(18)F]BBN-2 is a suitable PET radiotracer with favorable metabolic stability in vivo for molecular imaging of GRP receptor-positive prostate cancer., (© 2013.)

The radiometal (64)Cu is now widely used in the development of diagnostic imaging agents for positron emission tomography (PET). The present study has led to the development and evaluation of a novel chelating agent for (64)Cu: the new monothiourea tripodal ligand 1-benzoyl-3-{6-[(bis-pyridin-2-ylmethyl-amino)-methyl]-pyridin-2-yl}-thiourea (MTUBo). X-ray crystallographic analysis has shown this ligand forms a mononuclear complex with copper(II) and co-ordinates via a trigonal bipyramidal N4S array of donor atoms. Promisingly, cell uptake studies revealed that (64)Cu-MTUBo selectively accumulates in EMT-6 cells incubated under hypoxic conditions which may result from its relatively high Cu(II/I) redox potential. Small-animal PET imaging and ex vivo biodistribution studies in EMT-6 tumor bearing BALB/c mice revealed significant tumor uptake after 1 h p.i., yielding tumor-to-muscle (T/M) and tumor-to-blood (T/B) ratios of 8.1 and 1.1, respectively. However, injection of (64)Cu-acetate resulted in similar uptake indicating that the observed uptake was most likely non-specific. Despite showing high in vitro stability, it is likely that in vivo the complex undergoes transchelation to proteins within the blood in a relatively short timeframe. For comparison, the hypoxia imaging agent (64)Cu-ATSM was also evaluated in the same murine tumor model and showed about 60% higher tumor uptake than (64)Cu-MTUBo.

The copper-free click chemistry reaction between norbornene and tetrazine species is known to proceed in a rapid, reliable and selective manner under mild conditions. Due to these attractive properties, this reaction has recently been explored as a generally applicable method of bioconjugation. Here, we report a convenient synthetic procedure towards a novel (18)F-labelled norbornene derivative ([(18)F]NFB) and have evaluated its ability to undergo strain-promoted copper-free click chemistry reactions with two model tetrazine species: an asymmetric dipyridyl tetrazine derivative (Tz) and a tetrazine thiourea-coupled stabilised bombesin peptide (TT-BBN). In both cases, [(18)F]NFB was found to undergo rapid and high-yielding click chemistry reactions. Furthermore, as reactions of this type could also potentially be used in vivo to facilitate the development of a novel pretargeting approach for tumour imaging and therapy, we have also assessed the radiopharmacological profile (bioavailability, biodistribution, blood clearance and metabolic stability) of [(18)F]NFB in normal BALB/c mice. This radiolabelled compound exhibits both high bioavailability and metabolic stability with approximately 90% remaining intact up to 30 min following administration.

Localized hypoxia, the physiological hallmark of many clinical pathologies, is the consequence of acute or chronic ischemia in the affected region or tissue. The versatility, sensitivity, quantitative nature, and increasing availability of positron emission tomography (PET) make it the preclinical and clinical method of choice for functional imaging of tissue hypoxia at the molecular level. The progress and current status of radiotracers for hypoxia-specific PET imaging are reviewed in this article including references mainly focused on radiochemistry and also relevant to molecular imaging of hypoxia in preclinical and clinical studies., (Copyright © 2013 John Wiley & Sons, Ltd.)

Introduction: Phosphopeptides represent interesting compounds to study and elucidate cellular protein phosphorylation/dephosphorylation processes underlying various signal transduction pathways. However, studies of phosphopeptide action in cells are severely constrained by the negatively charged phosphate moiety of the phosphopeptide resulting in poor transport through the cell membrane. The following study describes the synthesis and radiopharmacological evaluation of two (18)F-labeled phosphopeptide-cell-penetrating peptide dimers. The polo-like kinase-1-binding hexaphosphopeptide H-Met-Gln-Ser-pThr-Pro-Leu-OH was coupled to cell-penetrating peptides (CPPs), either sC18, a cathelicidin-derived peptide, or the human calcitonin derivative hCT(18-32)-k7., Methods: Radiolabeling was accomplished with the prosthetic group N-succinimidyl 4-[(18)F]fluorobenzoate ([(18)F]SFB) using both, conventional and microfluidic-based bioconjugation of [(18)F]SFB to N-terminal end of phosphopeptide part of the peptide dimers. Cellular uptake studies in human cancer cell lines HT-29 and FaDu cells at 4 °C and 37 °C and small animal PET in BALB/c mice were utilized for radiopharmacological characterization., Results: Isolated radiochemical yields ranged from 2% to 4% for conventional bioconjugation with [(18)F]SFB. Significantly improved isolated radiochemical yields of up to 26% were achieved using microfluidic technology. Cellular uptake studies of radiolabeled phosphopeptide and phosphopeptide-CPP dimers indicate enhanced internalization of 50% ID/mg protein after 2 h for both phosphopeptide dimers compared to the phosphopeptide alone (<1% ID/mg protein). In vivo biodistribution of (18)F-labeled peptide dimers was determined with small animal PET revealing a superior biodistribution pattern of sC18-containing peptide dimer MQSpTPL-sC18 [(18)F]4., Conclusion: ([18)F]SFB labeling of the phosphopeptide-CPP dimers using a microfluidic system leads to an improved chemoselectivity towards the N-terminal NH(2) group compared to the conventional labeling approach. Cell-penetrating peptide sC18 can be considered as an ideal molecular shuttle for intracellular delivery of the Plk1-PBD-binding hexaphosphopeptide as demonstrated by its favourable radiopharmacological profile., (Copyright © 2012 Elsevier Inc. All rights reserved.)

A series of fluorobenzoylated di- and tripeptides as potential leads for the development of molecular probes for imaging of COX-2 expression was prepared according to standard Fmoc-based solid-phase peptide synthesis. All peptides were assessed for their COX-2 inhibitory potency and selectivity profile in a fluorescence-based COX binding assay. Within the series of 15 peptides tested, cysteine-containing peptides numbered 7, 8, 11 and 12, respectively, were the most potent COX-2 inhibitors possessing IC(50) values ranging from 5 to 85 μM. Fluorobenzoylated tripeptides 7 and 8 displayed some COX-2 selectivity (COX-2 selectivity index 2.1 and 1.6), whereas fluorobenzoylated dipeptides 11 and 12 were shown not to be COX-2 selective. Fluorbenzoylated tripeptide FB-Phe-Cys-Ser-OH was further used in molecular modeling docking studies to determine the binding mode within the active site of the COX-2 enzyme., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A new synthesis of O-(2-[(18)F]fluoroethyl)-L-tyrosine [(18)F]FET was developed using a NanoTek® microfluidic synthesis system (Advion BioSciences, Inc.). Optimal reaction conditions were studied through screening different reaction parameters like temperature, flow rate, reaction time, concentration of the labeling precursor, and the applied volume ratio between the labeling precursor and [(18)F]fluoride. [(18)F]FET was obtained after HPLC purification with 50% decay-corrected radiochemical yield starting from as little as 40 μg of labeling precursor. Small animal PET studies in EMT-6 tumor bearing mice showed radioactivity accumulation in the tumor (SUV(60min) 1.21±0.2) resulting in an slightly increasing tumor-to-muscle ratio over time., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Positron emission tomography (PET) allows detection of functional changes in malignant tissue. Establishment of an immortalized immunocompetent breast cancer mouse model would provide a useful platform for the analysis of novel cancer treatment strategies. This study describes a comparative functional evaluation of murine breast cancer models established from polyoma virus middle T antigen (PyMT)-derived tumors using small animal PET imaging with [(18)F]FDG and [(18)F]FLT. Primary PyMT tumor-derived cells and a cell line derived from these tumors (MTHJ) were injected subcutaneously into immunocompetent FVB mice to generate breast cancer xenografts. Tumor growth rates were comparable in both models and tumors were analyzed after 4-5 weeks post-injection. [(18)F]FDG uptake in vitro followed a comparable trend in both models but reached higher uptake levels in primary PyMT cells vs. MTHJ cells after 120 min. At all time points, [(18)F]FLT uptake was significantly higher in MTHJ compared to primary PyMT cells. Dynamic small animal PET imaging with [(18)F]FDG revealed standardized uptake values (SUVs) of 2.5±0.1 (n=8) in tumors from primary cells and 2.8±0.4 (n=6) in MTHJ tumors after 60 min p.i.. The corresponding tumor-muscle-ratios were 9.3±1.5 and 10.4±0.9, respectively. Uptake of [(18)F]FLT resulted in slightly higher SUV(60min) in MTHJ tumors (1.1±0.1, n=6) compared to tumors from primary cells (SUV(60min)=0.9±0.05, n=8, p=0.07). The tumor-muscle-ratio was comparable in both tumors (2.1±0.2 and 1.8±0.1, respectively). The PET imaging data demonstrates that the functional profile of immunocompetent murine breast tumor model MTHJ remains the same as in primary-derived PyMT tumors in vivo. Metabolic and proliferative rates as assessed with [(18)F]FDG and [(18)F]FLT are comparable in both tumor models. The observed high SUV(60min) of 2.8±0.4 with [(18)F]FDG in MTHJ tumors allows one to monitor efficacy of therapeutic interventions connected with changes in metabolic response of the tumor by means of small animal PET.

The copper-free strain-promoted click chemistry between (18)F-labeled aza-dibenzocyclooctyne [(18)F]FB-DBCO and various azides is described. [(18)F]FB-DBCO was prepared in 85% isolated radiochemical yield (decay-corrected) through acylation of amino aza-dibenzocyclooctyne 1 with N-succinimidyl 4-[(18)F]fluorobenzoate ([(18)F]SFB). [(18)F]FB-DBCO showed promising radiopharmacological profil with fast blood clearance as assessed with dynamic small animal PET studies. Metabolic stability of [(18)F]FB-DBCO was 60% of intact compound after 60 min post injection in normal Balb/C mice and blood clearance half-life was determined to be 53 s based on the time-activity-curve (TAC). Copper-free click chemistry was performed with various azides at low concentrations (1-2 μM) which differed in their structural complexity in different solvents (methanol, water, phosphate buffer and in bovine serum albumin (BSA) solution). Reaction proceeded best in methanol (>95% yield after 15 min at room temperature), whereas reaction in BSA required longer reaction times of 60 min and 40 °C upon completion.

Introduction: Several clinical studies have shown low or no expression of GLUT1 in breast cancer patients, which may account for the low clinical specificity and sensitivity of 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) used in positron emission tomography (PET). Therefore, it has been proposed that other tumor characteristics such as the high expression of GLUT2 and GLUT5 in many breast tumors could be used to develop alternative strategies to detect breast cancer. Here we have studied the in vitro and in vivo radiopharmacological profile of 6-deoxy-6-[(18)F]fluoro-D-fructose (6-[(18)F]FDF) as a potential PET radiotracer to image GLUT5 expression in breast cancers., Methods: Uptake of 6-[(18)F]FDF was studied in murine EMT-6 and human MCF-7 breast cancer cells over 60 min and compared to [(18)F]FDG. Biodistribution of 6-[(18)F]FDF was determined in BALB/c mice. Tumor uptake was studied with dynamic small animal PET in EMT-6 tumor-bearing BALB/c mice and human xenograft MCF-7 tumor-bearing NIH-III mice in comparison to [(18)F]FDG. 6-[(18)F]FDF metabolism was investigated in mouse blood and urine., Results: 6-[(18)F]FDF is taken up by EMT-6 and MCF-7 breast tumor cells independent of extracellular glucose levels but dependent on the extracellular concentration of fructose. After 60 min, 30±4% (n=9) and 12±1% (n=7) ID/mg protein 6-[(18)F]FDF was found in EMT-6 and MCF-7 cells, respectively. 6-deoxy-6-fluoro-d-fructose had a 10-fold higher potency than fructose to inhibit 6-[(18)F]FDF uptake into EMT-6 cells. Biodistribution in normal mice revealed radioactivity uptake in bone and brain. Radioactivity was accumulated in EMT-6 tumors reaching 3.65±0.30% ID/g (n=3) at 5 min post injection and decreasing to 1.75±0.03% ID/g (n=3) at 120 min post injection. Dynamic small animal PET showed significantly lower radioactivity uptake after 15 min post injection in MCF-7 tumors [standard uptake value (SUV)=0.76±0.05; n=3] compared to EMT-6 tumors (SUV=1.23±0.09; n=3). Interestingly, [(18)F]FDG uptake was significantly different in MCF-7 tumors (SUV(15 min) 0.74±0.12 to SUV(120 min) 0.80±0.15; n=3) versus EMT-6 tumors (SUV(15 min) 1.01±0.33 to SUV(120 min) 1.80±0.25; n=3). 6-[(18)F]FDF was shown to be a substrate for recombinant human ketohexokinase, and it was metabolized rapidly in vivo., Conclusion: Based on the GLUT5 specific transport and phosphorylation by ketohexokinase, 6-[(18)F]FDF may represent a novel radiotracer for PET imaging of GLUT5 and ketohexokinase-expressing tumors., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Purpose: Combination therapy of male lower urinary tract symptoms with α(1)-adrenoceptor and muscarinic receptor antagonists attracts increasing interest. Propiverine is a muscarinic receptor antagonist possessing additional properties, i.e., block of L-type Ca(2+) channels. Here, we have investigated whether propiverine and its metabolites can additionally antagonize α(1)-adrenoceptors., Methods: Human prostate and porcine trigone muscle strips were used to explore inhibition of α(1)-adrenoceptor-mediated contractile responses. Chinese hamster ovary (CHO) cells expressing cloned human α(1)-adrenoceptors were used to determine direct interactions with the receptor in radioligand binding and intracellular Ca(2+) elevation assays., Results: Propiverine concentration-dependently reversed contraction of human prostate pre-contracted with 10 μM phenylephrine (-log IC(50) [M] 4.43 ± 0.08). Similar inhibition was observed in porcine trigone (-log IC(50) 5.01 ± 0.05), and in additional experiments consisted mainly of reduced maximum phenylephrine responses. At concentrations ≥1 μM, the propiverine metabolite M-14 also relaxed phenylephrine pre-contracted trigone strips, whereas metabolites M-5 and M-6 were ineffective. In radioligand binding experiments, propiverine and M-14 exhibited similar affinity for the three α(1)-adrenoceptor subtypes with -log K (i) [M] values ranging from 4.72 to 4.94, whereas the M-5 and M-6 did not affect [(3)H]-prazosin binding. In CHO cells, propiverine inhibited α(1)-adrenoceptor-mediated Ca(2+) elevations with similar potency as radioligand binding, again mainly by reducing maximum responses., Conclusions: In contrast to other muscarinic receptor antagonists, propiverine exerts additional L-type Ca(2+)-channel blocking and α(1)-adrenoceptor antagonist effects. It remains to be determined clinically, how these additional properties contribute to the clinical effects of propiverine, particularly in male voiding dysfunction.

Introduction: Microfluidic technology allows fast reactions in a simple experimental setup, while using very low volumes and amounts of starting material. Consequently, microfluidic technology is an ideal tool for radiolabeling reactions involving short-lived positron emitters. Optimization of the complex array of different reaction conditions requires knowledge of the different reaction parameters linked to the microfluidic system as well as their influence on the radiochemical yields. 1-(5-Deoxy-5-fluoro-α-d-arabinofuranosyl)-2-nitroimidazole ([(18)F]FAZA) is a frequently used radiotracer for PET imaging of tumor hypoxia. The present study describes the radiosynthesis of [(18)F]FAZA by means of microfluidic technology and subsequent small animal PET imaging in EMT-6 tumor-bearing mice., Methods: Radiosyntheses were performed using the NanoTek Microfluidic Synthesis System (Advion BioSciences, Inc.). Optimal reaction conditions were studied through screening different reaction parameters like temperature, flow rate, residency time, concentration of the labeling precursor (1-(2,3-di-O-acetyl-5-O-tosyl-α-d-arabinofuranosyl)-2-nitroimidazole) and the applied volume ratio between the labeling precursor and [(18)F]fluoride., Results: Optimized reaction conditions at low radioactivity levels (1 to 50 MBq) afforded 63% (decay-corrected) of HPLC-purified [(18)F]FAZA within 25 min. Higher radioactivity levels (0.4 to 2.1 GBq) gave HPLC-purified [(18)F]FAZA in radiochemical yields of 40% (decay-corrected) within 60 min at a specific activity in the range of 70 to 150 GBq/μmol. Small animal PET studies in EMT-6 tumor-bearing mice showed radioactivity accumulation in the tumor (SUV(20min) 0.74 ± 0.08) resulting in an increasing tumor-to-muscle ratio over time., Conclusions: Microfluidic technology is an ideal method for the rapid and efficient radiosynthesis of [(18)F]FAZA for preclinical radiopharmacological studies. Careful analysis of various reaction parameters is an important requirement for the understanding of the influence of different reaction parameters on the radiochemical yield using microfluidic technology. Exploration of microfluidic technology for the radiosynthesis of other PET radiotracers in clinically relevant radioactivity levels is currently in progress., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Unlabelled: (18)F-3'-Deoxy-3'-fluorothymidine ((18)F-FLT) is a PET tracer that accumulates in proliferating tissues. The current study was undertaken to determine whether equilibrative nucleoside transporter 1 (ENT1) is important for (18)F-FLT uptake in normal tissues and tumors., Methods: ENT1-knockout (ENT1(-/-)) mice were generated and compared with wild-type (ENT1(+/+)) mice using small-animal (18)F-FLT PET. In addition, ENT1(+/+) mice were also injected with the ENT1 inhibitor nitrobenzylmercaptopurine ribonucleoside phosphate (NBMPR-P) at 1 h before radiotracer injection, followed by (18)F-FLT small-animal PET. Tissues of interest were analyzed for thymidine kinase 1 and nucleoside transporters by immunoblotting and immunohistochemistry, respectively, and plasma thymidine levels were analyzed by liquid chromatography-mass spectrometry. Human lung carcinoma A549 cells were stably transfected with pSUPER-producing short-hairpin RNA against human ENT1 (hENT1) or a scrambled sequence with no homology to mammalian genes (A549-pSUPER-hENT1 and A549-pSUPER-SC, respectively). Cultured transfected cells were characterized for hENT1 transcript levels and (18)F-FLT uptake using real-time polymerase chain reaction and (3)H-FLT uptake assays, respectively. Transfected A549 cells were grown as xenograft tumors in NIH-III mice, which were analyzed by (18)F-FLT small-animal PET., Results: Compared with noninjected ENT1(+/+) mice, ENT1(+/+) mice injected with NBMPR-P and ENT1(-/-) mice displayed a reduced percentage injected dose per gram (%ID/g) for (18)F-FLT in the blood (84 and 81%, respectively) and an increased %ID/g for (18)F-FLT in the spleen (188 and 469%, respectively) and bone marrow (266 and 453%, respectively). ENT1(-/-) mice displayed 1.65-fold greater plasma thymidine levels than did ENT1(+/+) mice. Spleen tissue from ENT1(+/+) and ENT1(-/-) mice displayed similar thymidine kinase 1 protein levels and significant concentrative nucleoside transporter 1 and 3 staining. Compared with A549-pSUPER-SC cells, A549-pSUPER-hENT1 cells displayed 0.45-fold hENT1 transcript levels and 0.68-fold (3)H-FLT uptake. Compared with A549-pSUPER-SC xenograft tumors, A549-pSUPER-hENT1 xenograft tumors displayed 0.76-fold %ID/g values (ex vivo gamma-counts) and 0.65-fold maximum standardized uptake values (PET image analysis) for (18)F-FLT uptake at 1 h after tracer injection., Conclusion: Loss of ENT1 activity significantly affected (18)F-FLT biodistribution in mice and (18)F-FLT uptake in xenograft tumors, suggesting that nucleoside transporters are important mediators of (18)F-FLT uptake in normal and transformed cells.

Interleukin-2 inducible T-cell kinase (ITK) is one of five kinases that belong to the Tec kinase family that plays an important role in T-cell and mast cell signaling. Various reports point to a role of ITK in the treatment of allergic asthma. For example, it was shown that mice lacking ITK have reduced airway hyperresponsiveness, inflammation and tracheal responses in an allergic asthma model. In this article, we disclose novel ITK inhibitors based on (4 or 5-aryl)pyrazolyl-indole scaffold that were also found to be selective for ITK over other kinases like IRK, CDK2, GSK3ss and PKA., (Copyright 2010 Elsevier Ltd. All rights reserved.)

The muscarinic receptor antagonist propiverine used for therapy of overactive bladder undergoes first pass metabolism, leading to several active metabolites, which affect muscarinic receptors and L-type Ca(2+) channels with different potencies. M-5, the major metabolite in blood, and M-6 can be synthesized as cis- and trans-isomers. We systematically investigated the pharmacodynamic profiles of the isomers on detrusor contractile function. In murine and porcine detrusor, the effects of the derivatives were examined on contractions induced by electric field stimulation (EFS), cumulatively increasing concentrations of carbachol or high KCl concentration. EFS contractions were concentration-dependently reduced by the M-5 and M-6 isomers although to a different extent. M-5(cis) was slightly more potent than M-5(trans), but the differences did not reach statistical significance. M-6(cis) was significantly more potent than M-6(trans). Responses to carbachol were antagonized by all compounds due to rightward shifts of the concentration-response curves, but only M-5(trans) also significantly reduced the maximum response. pK (B) values obtained with Schild plot analysis indicated slightly higher potency for M-6(cis) than M-6(trans). Ca(2+) influx-dependent contractions elicited by K(+) depolarization were less impaired by low concentrations of the M-6 isomers, but strongly suppressed by 100 microM of the M-5 isomers, suggesting an additional effect of the two M-5 isomers on Ca(2+) influx. All investigated isomers of M-5 and M-6 are biologically active in reducing detrusor contraction in animal tissue. While M-5( cis,) M-6(cis), and M-6(trans) possess surmountable or partially surmountable antagonistic properties at muscarinic receptors, M-5(trans) is a strong non-competitive antagonist. However, at higher concentration ranges, all four compounds seem to have additional effects on Ca(2+) influx.

(-)-Isoproterenol [4-[1-hydroxy-2-[(1-methylethyl)amino]ethyl]-1,2-benzene diol hydrochloride] relaxes murine detrusor through beta-adrenoceptors (ARs); however, the beta-AR subtypes involved are unknown. beta(2)-ARs have been associated with caveolae, plasma-lemmal scaffolding domains that are absent in caveolin-1 (cav-1) knockout (KO) mice. Here, we studied detrusor responses in the absence and presence of beta-AR subtype-selective antagonists in wild-type (WT) and cav-1 KO mice. To inquire whether the murine detrusor model is relevant to man, beta-AR subtypes that mediate (-)-isoproterenol-evoked human detrusor relaxation were investigated. In WT mice, (-)-isoproterenol concentration-dependently relaxed the KCl (40 mM)-precontracted detrusor (-logEC(50)M = 8.04, E(max) = 62%). The effects of (-)-isoproterenol were surmountably antagonized by the beta(2)-AR-selective antagonist ICI 118,551 [(+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl)amino]-2-butanol] (pK(B) = 9.28) but not affected by the beta(1)-AR-selective antagonist CGP 20712 [1-[2-((3-carbamoyl-4-hydroxy)phenoxy)ethylamino]-3-[4-(1-methyl-4-trifluoromethyl-2-imidazolyl)phenoxy]-2-propanol] and beta(3)-AR-selective L-748,337 [(S)-M-[4-[2-[3-[3-[acetamidomethyl)phenoxy)-2-hydroxypropyl]-amino]-ethyl]-phenylbenzsulfonamide)], suggesting involvement of beta(2)-AR only. The cav-1 KO detrusor displayed significant contractile dysfunction. (-)-Isoproterenol was less potent and efficient in relaxing detrusor from cav-1 KO (-logEC(50)M, 7.76; E(max) = 44%), but ICI 118,551 caused similar antagonism (pK(B) = 9.15), suggesting that beta(2)-AR function persisted in cav-1 KO. The beta(3)-AR-selective antagonist L-748,337 in the presence of ICI 118,551 and CGP 20712 caused additional blockade of (-)-isoproterenol effects in cav-1 KO, consistent with a beta(3)-AR involvement during relaxation and suppression of this effect in WT. (-)-Isoproterenol relaxed human detrusor muscle precontracted with carbachol (-logEC(50)M = 6.39, E(max) = 52%). However, the effects of (-)-isoproterenol in human detrusor were not blocked by CGP 20712 or ICI 118,551 but antagonized by L-748,337 (pK(B) = 7.65). We conclude that murine detrusor relaxation occurs via beta(2)-AR, and loss of caveolae does not perturb beta(2)-AR function but unmasks an additional activation of beta(3)-AR. In contrast, detrusor relaxation in man is mediated exclusively via beta(3)-AR.

The non-selective muscarinic receptor antagonist propiverine impairs L-type Ca(2+) currents (I(Ca,L)) in human detrusor smooth muscle cells and atrial cardiomyocytes. Here, we have investigated the effects of three metabolites of propiverine on human cardiac I(Ca,L). Propiverine reduced I(Ca)(,L) with a -logIC(50) [M] value of 4.1, M-5 only showed minor effect on I(Ca)(,L) at high concentrations, M-6 did not influence I(Ca)(,L) at all. Like the parent compound M-14 also reduced I(Ca)(,L) (-logIC(50) [M]=4.6). We conclude, that propiverine and M-14 reduce cardiac I(Ca)(,L) at higher concentrations than in detrusor cells and therefore preferentially reduce I(Ca)(,L) in the urinary bladder than in the heart.

Urinary bladder function is known to mature during fetal and postnatal development, including changes in neurotransmitter regulation of detrusor contraction. However, only few experimental data are available about muscarinic receptor antagonist function in the urinary bladder from young animals. In the present study, we compare the muscarinic receptor-mediated contractions in juvenile and adult porcine detrusor and the effects of antimuscarinic compounds. Urinary bladders from young (8-12 weeks; 12- to 35-kg body weight) and mature pigs (>40 weeks; >100 kg) were compared. Muscarinic receptor expression was assessed by real time polymerase chain reaction and radioligand binding. Muscle contraction was measured with a force transducer; L-type Ca2+ currents (ICa,L) of isolated detrusor myocytes were recorded with standard voltage clamp technique. Juvenile and adult detrusor expressed similar quantities of the messenger RNA of M2 and M3 receptors. The number of [3H]QNB-binding sites and their affinity for the radioligand were also similar between juvenile and adult detrusor. In contrast, maximum contractile responses to the muscarinic receptor agonist carbachol were slightly larger in juvenile than adult bladders. On the other hand, carbachol was slightly less potent in juvenile than in adult tissue. The M3 antagonist DAU 5884 and the spasmolytic drug propiverine inhibited contractile responses with comparable efficacies and potencies in juvenile and adult tissue. ICa,L was somewhat smaller in juvenile than in adult cells. Taken together, these data suggest that expression and function of M2 and M3 receptors are similar in the detrusor of juvenile and mature pigs. Therefore, similar responses to antimuscarinic compounds could be expected in young and adult patients.

Drugs that prolong the QT interval by blocking human ether-a-go-go (HERG) channels may enhance the risk of ventricular arrhythmia. The spasmolytic drug propiverine is widely used for the therapy of overactive bladder (OAB). Here, we have investigated the effects of propiverine on cardiac ion channels and action potentials as well as on contractile properties of cardiac tissue, in order to estimate its cardiac safety profile, because other drugs used in this indication had to be withdrawn due to safety reasons. Whole-cell patch clamp technique was used to record the following cardiac ion currents: rapidly and slowly activating delayed rectifier K+ current (I(Kr), I(Ks)), ultra rapidly activating delayed rectifier K+ current (I(Kur)), inwardly rectifying K+ current I(K1), transient outward K+ current (I(to)), and L-type Ca2+ current (I(Ca,L)). Action potentials in cardiac tissue biopsies were recorded with conventional microelectrodes. The torsade de pointes screening assay (TDPScreen) was used for drug scoring. Propiverine blocked in a concentration-dependent manner HERG channels expressed in HEK293 cells, as well as native I(Kr) current in ventricular myocytes of guinea pig (IC50 values: 10 microM and 1.8 microM respectively). At high concentrations (100 microM), propiverine suppressed I(Ks). I(K1) and the transient outward current I(to) and I(Kur) were not affected. In guinea-pig ventricular and human atrial myocytes, propiverine also blocked I(Ca,L) (IC50 values: 34.7 microM and 41.7 microM, respectively) and reduced force of contraction. Despite block of I(Kr), action potential duration was not prolonged in guinea-pig and human ventricular tissue, but decreased progressively until excitation failed altogether. Similar effects were observed in dog Purkinje fibers. Propiverine obtained a low score in the TDPScreen. In conclusion, in vitro and in vivo studies of propiverine do not provide evidence for an enhanced cardiovascular safety risk. We propose that lack of torsadogenic risk of propiverine is related to enhancement of repolarization reserve by block of I(Ca,L).

Basal cell carcinoma of the skin (BCC) is the most common skin tumor in Caucasians worldwide. Different therapeutic options are available to treat BCC, including topical immunotherapy. Imiquimod is topical Toll-like receptor 7 agonist that activates anti-tumor immune response and has been recently approved for the treatment of superficial BCC (sBCC). We sought to investigate the influence of imiquimod treatment on the members of the Notch signaling pathway, whose activity is known to be decreased in BCCs. Six patients with sBCC were evaluated for Notch1, Jagged1 and Delta1 expression before (pre-treatment) and after the beginning of the topical treatment (post-treatment) with imiquimod using real-time PCR and immunohistochemistry. We show selective transcriptional up-regulation of Notch pathway members (Notch1, Jagged1 and Delta1) in tumor cells of the sBCC post-treatment. Furthermore, we demonstrate minor increase of Notch1 protein expression on infiltrating cells as well as strong increase in Jagged1 protein expression in regressing sBCC tumors post-treatment. In this way, imiquimod may act as a stimulator of the Notch pathway in sBCC tumor cells by up-regulating protein expression of the Notch ligand, Jagged1. Via induction of Notch signaling imiquimod may exert tumor suppressor function, which together with its proinflammatory properties results in tumor regression.

Carbachol-induced detrusor contractions are mainly mediated via M3 receptor subtype and depend not only on Ca2+ release from the intracellular calcium stores but also on Ca2+ influx via L-type Ca2+ channels. The purpose of this study was to examine the different contributions of Ca2+ influx and Ca2+ release underlying muscarinic receptor-mediated contractions in human, porcine and murine urinary bladder. Detrusor contractions were measured in urothelium-denuded detrusor strips as responses to cumulatively increasing carbachol concentrations, release of intracellular Ca2+ was determined in Chinese hamster ovary cells stably transfected with human muscarinic M3 (hM3) receptors. In human tissue, 1 microM of the L-type Ca2+-channel blocker nifedipine reduced carbachol contractions to 74%, in pig to 18% and in mouse to 27% of pre-drug controls. 2-aminoethoxyphenyl borate (2-APB, 300 microM), which impairs inositol trisphosphate (IP3)-induced release of Ca2+, reduced carbachol responses in human detrusor to 60%, in pig to 35% and in mouse to 20%, whereas block of the Ca2+-induced Ca2+ release with ryanodine had no significant effect on carbachol contractions in all three species. Carbachol-induced release of intracellular Ca2+ in Chinese hamster ovary cells expressing muscarinic hM3 receptors was completely prevented by 100 microM 2-APB. The direct intracellular IP3 receptor antagonist xestospongin C (10 microM) reduced carbachol-stimulated intracellular Ca2+ to 41% of the control value. Blockade of ATP-dependent Ca2+ uptake into intracellular stores with thapsigargin was associated with a concentration-dependent increase of detrusor contraction, but limited on-top contractions with carbachol. In conclusion, carbachol-induced contractions in human, porcine and mouse detrusor depend differently on Ca2+ influx, since potency of nifedipine reducing muscarinic receptor-mediated detrusor contraction is lower in human bladder. On the other hand, slight species differences are also found when inhibiting IP3-induced Ca2+ release and Ca2+ reuptake into intracellular stores. Taken together, our data show considerable species differences between human, porcine and murine detrusor regarding the relative contributions of Ca2+ influx and maybe also carbachol-induced Ca2+ release that could be of relevance when using different animal models.

Propiverine is a commonly used antimuscarinic drug used as therapy for symptoms of an overactive bladder. Propiverine is extensively biotransformed into several metabolites that could contribute to its spasmolytic action. In fact, three propiverine metabolites (M-5, M-6 and M-14) have been shown to affect various detrusor functions, including contractile responses and L-type calcium-currents, in humans, pigs and mice, albeit with different potency. The aim of our study was to provide experimental evidence for the relationship between the binding of propiverine and its metabolites to human muscarinic receptor subtypes (hM(1)-hM(5)) expressed in chinese hamster ovary cells, and to examine the effects of these compounds on muscarinic receptor-mediated detrusor function. Propiverine, M-5, M-6 and M-14 bound to hM(1)-hM(5) receptors with the same order of affinity for all five subtypes: M-6 > propiverine > M-14 > M-5. In HEK-293 cells expressing hM(3), carbachol-induced release of intracellular Ca(2+) ([Ca(2+)](i)) was suppressed by propiverine and its metabolites; the respective concentration-response curves for carbachol-induced Ca(2+)-responses were shifted to the right. At higher concentrations, propiverine and M-14, but not M-5 and M-6, directly elevated [Ca(2+)](i). These results were confirmed for propiverine in human detrusor smooth muscle cells (hDSMC). Propiverine and the three metabolites decreased detrusor contractions evoked by electric field stimulation in a concentration-dependent manner, the order of potency being the same as the order of binding affinity. We conclude that, in comparison with the parent compound, loss of the aliphatic side chain in propiverine metabolites is associated with higher binding affinity to hM(1)-hM(5) receptors and higher functional potency. Change from a tertiary to a secondary amine (M-14) results in lower binding affinity and reduced potency. Oxidation of the nitrogen (M-5) further lowers binding affinity as well as functional potency.

In isolated detrusor strips, propiverine is known to be effective to decrease contractions elicited by electric field stimulation (EFS). Here we investigated whether the metabolites M-5, M-6 and M-14 of propiverine retain the pharmacological properties of the parent compound also in juvenile organisms. EFS-induced contractions of detrusor strips from juvenile pigs are more sensitive to atropine than strips from mature pigs. The atropine-resistant component of contraction is also significantly larger in juvenile pigs. Propiverine, its metabolites M-5, M-14 and also tolterodine completely reduced detrusor contraction in juvenile pigs. M-6 almost did not affect atropine-resistant contractions. We conclude that juvenile pig detrusors possess a higher atropine-resistant component of EFS-elicited contraction. Nevertheless order of potency and efficacy of propiverine and its metabolites M-5 and M-14 are similar in juvenile and mature pigs, while M-6 only reduces atropine-sensitive contractions in the juvenile organism.

Openers of K(ATP) channels are known to inhibit KCl-, carbachol- and also electrically induced contractions in detrusor muscle strips from various species. Contractions of isolated strips of urinary bladder are usually of higher amplitude when the urothelium has been removed. This has been explained by the release of an urothelium-derived relaxing factor. In this study we examined whether intact urothelium may modulate the effect of the selective KATP channel opener rilmakalim. Contractile responses to 85 mM KCl and 10 microM carbachol were measured in detrusor strips from mouse, pig and man. In the presence of an intact urothelium, contractions were significantly reduced in strips from all three species investigated. In preparations with urothelium rilmakalim reduced KCl contractions with similar potency and efficacy [-logIC50 (M) 4.6 to 5.1; Effmax reduction to 14-30% of control]. However, in urothelium-denuded strips rilmakalim was more potent in pig (-logIC50 5.5) than in mouse and man (-logIC50 4.7 and 4.4, respectively). The order of potency for rilmakalim to suppress carbachol-induced contractions was pig (-logIC50 6.7)>man (5.8)>mouse (4.7); contractions were significantly more reduced in pig (Effmax reduction to 11+/-2%, n=10) and in mouse (21+/-2%, n=8) than in human detrusor (55+/-5%, n=5). The presence of urothelium did not affect the concentration-response curves for rilmakalim, with the exception of KCl-induced contractions in pig. Only the rilmakalim-induced relaxation of carbachol-mediated contractions in pig were prevented by the KATP channel blocker glibenclamide. We conclude that with this one exception, the responses to rilmakalim in detrusor contractions were not mediated by KATP channel opening.

1. Besides its antimuscarinic effects, propiverine may possess an additional mode of action. We compared the effects of propiverine, three of its metabolites (M-5, M-6, M-14) and atropine in human, pig and mouse urinary bladder preparations in order to elucidate the nature of a possible additional mode of action. 2. Like the parent compound, M-5, M-6 and M-14 reduced to variable degrees the contractions elicited by electric field stimulation (EFS) of isolated, urothelium-denuded detrusor strips. In mouse the atropine-resistant and therefore the nonadrenergic, noncholinergic component of contractile response to EFS was reduced by M-5, M-14 and propiverine, but was hardly affected by M-6. 3. Atropine, propiverine and M-6 significantly shifted the cumulative concentration-response curves for carbachol (CCh) to higher concentrations. Atropine and M-6 did not affect the maximum tension induced by CCh. Propiverine, M-5 and M-14 reduced the maximum CCh effect, suggesting at least one additional mode of action. This pattern of response was observed in all the three species, albeit with some differences in sensitivity to the various agents. 4. In freshly isolated human detrusor smooth muscle cells, propiverine and M-14 inhibited the nifedipine-sensitive L-type calcium current (I(Ca)) in a concentration-dependent manner. In contrast, the effects of M-5 and M-6 on I(Ca) were insignificant in the concentration range examined. 5. The investigated responses to propiverine and its metabolites suggest that impairment of maximum CCh-induced contractions is due to strong effect on I(Ca) and that this may be associated with the presence of the aliphatic side chain.

Purpose: We investigated whether the contractility of isolated human detrusor muscle, responsiveness to commonly used spasmolytic drugs, and expression of selected muscarinic and purinergic (P2X) receptor subtypes (M2, M3, P2X1 and P2X3) change with age., Materials and Methods: Tissues were taken from 63 patients 37 to 84 years old undergoing radical cystectomy. Specimens from 49 patients were used for contractility studies and those from 50 were used for mRNA analysis., Results: Propiverine, oxybutynin, tolterodine and atropine decreased contractions evoked by electric field stimulation to different degrees. However, neither the efficacy nor potency of the drugs showed age related changes. Since human detrusor muscle shows atropine resistant noncholinergic responses, we also studied the putative age dependence of concentration-response curves to the muscarinic agonist carbachol, and the purinergic agonists adenosine triphosphate (ATP) and alpha-beta-methylene-ATP. Sensitivity to alpha-beta-methylene-ATP increased with age, while the efficacy and potency of spasmolytic drugs did not depend on age. In addition, mRNA detected for M2, M3, P2X1 and P2X3 receptors did not change with age., Conclusions: Our results do not provide evidence for age related contractile deterioration in human detrusor muscle strips, nor do they suggest that responses to anticholinergic spasmolytic drugs change substantially with age.

Copper-64 ( T(1/2)=12.7 h; beta(+): 0.653 MeV, 17.4%; beta(-): 0.578 MeV, 39%) is produced in a biomedical cyclotron and has applications in both imaging and therapy. Macrocyclic chelators are widely used as bifunctional chelators to bind copper radionuclides to antibodies and peptides owing to their relatively high kinetic stability. In this paper, we evaluated three tetraaza macrocyclic ligands with two, three, and four pendant methanephosphonate functional groups. DO2P [1,4,7,10-tetraazacyclododecane-1,7-di(methanephosphonic acid)], DO3P [1,4,7,10-tetraazacyclododecane-1,4,7-tri(methanephosphonic acid)], and DOTP [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetra(methanephosphonic acid)] were all radiolabeled with (64)Cu in high radiochemical yields. Copper-64-labeled DO2P and DOTP were highly stable in rat serum out to 24 h, while (64)Cu-DO3P remained 73% intact, with the remainder possibly forming a (64)Cu(.)2DO3P dimer by 24 h. The biodistribution experiments were performed in normal Sprague-Dawley rats. Of the three complexes, (64)Cu-DO2P demonstrated the most optimal clearance through the blood and liver. Copper-64-DO3P and (64)Cu-DOTP exhibited higher liver uptake and longer retention of liver activity, possibly because of the large negative charge of the complexes under physiological conditions. All three (64)Cu-labeled complexes showed high accumulation in bone, likely due to the binding of the methanephosphonate groups to hydroxyapatite. These results suggest that this series of methanephosphonate macrocyclic ligands may be useful as potential bone-imaging agents. The thermodynamic stability constants of the Cu(II) complexes with these three ligands were determined, and were found to be significantly higher than those of their acetate analogues. The Cu(II)-DO2P complex exhibited the highest stability constant among divalent transition metal ion DO2P complexes. Metabolism studies of (64)Cu-DO2P in rat liver suggest that the DO2P ligand may be used as a bifunctional chelator for copper radionuclides in radiodiagnostic or radiotherapeutic studies.

Malnutrition is frequent in chronic hemodialysis patients. Standard nutritional evaluation is based on anthropometric, laboratory and clinical parameters from which a malnutrition index can be derived. Bioelectrical impedance, more rapid and practical, can be used to evaluate body composition. The goals of our study were to: 1) evaluate the incidence of and some of the factors associated with malnutrition in hemodialysis patients; 2) assess the accuracy of a scoring system based on impedance results to identify malnourished patients as defined by the malnutrition index (based on anthropometric, laboratory and clinical parameters). Standard nutritional evaluation and impedance measurements were performed on 33 chronic hemodialysis patients. Using malnutrition index, 18 patients (54%) were severely or moderately malnourished. Dietary assessment revealed a high proportion of patients with insufficient protein or calorie intake. By multiple regression analysis, the only factor significantly correlated with the malnutrition index was calorie intake (r = 0.44); age, sex, years on hemodialysis, protein intake were not. Results obtained with impedance were strongly correlated to those obtained with anthropometry for the proportion of fat mass (r = 0.72) and lean body mass (r = 0.71) and for the malnutrition index (r = 0.78). The sensitivity of the scoring system based on impedance to identify moderately or severely malnourished patients as determined by standard nutritional evaluation was 100% and its specificity was 80%. The positive and negative predictive values were respectively 85% and 100%. In summary, malnutrition is frequent and associated with low caloric intake. Bioelectrical impedance, with the use of the scoring system we describe, can be used to correctly evaluate the nutritional status of hemodialysis patients.