A9 INTESTINAL ORGANOID TRANSPLANTATION REVERSED THE INTESTINAL EPITHELIUM DAMAGE IN EXPERIMENTAL NECROTIZING ENTEROCOLITIS

NOT PUBLISHED AT AUTHOR’S REQUEST

Structural Basis for Achieving GSK-3β Inhibition with High Potency, Selectivity, and Brain Exposure for Positron Emission Tomography Imaging and Drug Discovery

Using structure-guided design, several cell based assays, and microdosed positron emission tomography (PET) imaging, we identified a series of highly potent, selective, and brain-penetrant oxazole-4-carboxamide-based inhibitors of glycogen synthase kinase-3 (GSK-3). An isotopologue of our first-generation lead, [3H]PF-367, demonstrates selective and specific target engagement in vitro, irrespective of the activation state. We discovered substantial ubiquitous GSK-3-specific radioligand binding in Tg2576 Alzheimer's disease (AD), suggesting application for these compounds in AD diagnosis and identified [11C]OCM-44 as our lead GSK-3 radiotracer, with optimized brain uptake by PET imaging in nonhuman primates. GSK-3β-isozyme selectivity was assessed to reveal OCM-51, the most potent (IC50 = 0.030 nM) and selective (>10-fold GSK-3β/GSK-3α) GSK-3β inhibitor known to date. Inhibition of CRMP2T514 and tau phosphorylation, as well as favorable therapeutic window against WNT/β-catenin signaling activation, was observed in cells.

Abstract PD1-06: A phase 1b dose-escalation and expansion study of the BCL-2 inhibitor venetoclax combined with tamoxifen in ER and BCL-2–positive metastatic breast cancer (MBC)

Background: Venetoclax, a potent and selective inhibitor of the survival protein BCL-2 (recently approved in CLL and in development in other hematopoietic malignancies), has yet to be evaluated in pts with solid tumors. BCL-2 is overexpressed in ˜85% of ER+ breast cancer. Pre-clinical findings using patient-derived xenograft breast tumor models suggest that venetoclax synergizes with endocrine therapy by increasing apoptosis. Here we report mBEP, an investigator-initiated phase 1b study of venetoclax with tamoxifen in 33 pts with ER+ (>1%), BCL-2+ (>10%, 2-3+ intensity) and HER2– MBC.

Methods: We conducted a 3+3 dose escalation study comprising cohorts receiving venetoclax 200, 400, 600 or 800 mg/d with tamoxifen 20 mg/d (continued until progression). The primary endpoint was to determine the maximum tolerated dose (MTD), define dose-limiting toxicities (DLTs) and identify the recommended phase 2 dose (RP2D). In a dose expansion phase (at the RP2D), secondary endpoints including safety and tolerability, response at 24 wks (RECIST v1.1), clinical benefit rate (CBR) and progression-free survival (PFS) were studied.

Results: In the escalation phase (n=15 pts), treatment was well tolerated with no DLTs or high-grade (Gd 3/4) adverse events observed, apart from asymptomatic on-target lymphopenia (Gd 3, 2/15 pts). MTD was not reached. The 800 mg/d dose was selected as the RP2D and the cohort expanded to include 24 pts with ≥24 wks follow up (range 24-105 wks). Fifteen pts had received prior regimens for MBC (median 3, range 1-9) that included tamoxifen in 5/15.

For the RP2D cohort (n=24), overall responses (OR) included 1 CR (4%) and 12 PR (50%), with 5 SD (21%), corresponding to a CBR of 75%. The 9 pts treated in the first line setting experienced a 78% OR (7/9 pts) and 11% SD (1/9 pts), equating to an 89% CBR. The data are immature for determining median PFS for the RP2D cohort (currently 40+ wks).

Treatment responses were pre-empted by metabolic responses (FDG-PET) at 4 wks (seen in 13/16 (81%) pts studied), and correlated with serial changes in circulating tumor DNA (ctDNA). Intriguingly, responses and clinical benefit were observed in pts with plasma-detected ESR1 mutations (4/10 and 7/10, respectively).

The most common treatment-related AEs (CTCAE v4.0) for all pts were lymphopenia in 29/33 (88%; 57% Gd 1-2, 30% Gd 3-4), neutropenia in 24/33 (73%; 67% Gd 1-2, 6% Gd 3), nausea in 22/33 (67%; all ≤Gd 2), anemia in 13/33 (39%; 33% Gd 1-2, 6% G3), thrombocytopenia in 11/33 (33%; all ≤Gd 2), vomiting in 11/33 (33%, all ≤Gd 2), diarrhea in 10/33 (30%; 24% Gd 1-2, 6% Gd 3), infection in 9/33 (27%; 18% Gd 2, 9% Gd 3) and fatigue in 7/33 (21%; all ≤Gd 2). There was one possible treatment-related SAE (infection).

Conclusions: In the first clinical study to evaluate venetoclax in a solid tumor, we demonstrate that combining venetoclax with endocrine therapy has a tolerable safety profile and elicits remarkable activity in ER+ and BCL-2+ MBC. These findings support further investigation of combination therapy for patients with BCL-2-positive breast cancer.

Sponsor: The Royal Melbourne Hospital (ACTRN12615000702516)

Citation Format: Lindeman GJ, Lok SW, Whittle JR, Siow ZR, Bergin AR, Dawson S-J, Desai J, Gray DH, Liew D, Mann GB, Murugasu A, Roberts AW, Rosenthal MA, Shackleton K, Sherman P, Silva MJ, Teh C, Travers A, Vaillant F, Visvader JE. A phase 1b dose-escalation and expansion study of the BCL-2 inhibitor venetoclax combined with tamoxifen in ER and BCL-2–positive metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD1-06.

Synthesis and Initial In Vivo Evaluation of [11C]AZ683-A Novel PET Radiotracer for Colony Stimulating Factor 1 Receptor (CSF1R)

Positron emission tomography (PET) imaging of Colony Stimulating Factor 1 Receptor (CSF1R) is a new strategy for quantifying both neuroinflammation and inflammation in the periphery since CSF1R is expressed on microglia and macrophages. AZ683 has high affinity for CSF1R (Ki = 8 nM; IC50 = 6 nM) and >250-fold selectivity over 95 other kinases. In this paper, we report the radiosynthesis of [11C]AZ683 and initial evaluation of its use in CSF1R PET. [11C]AZ683 was synthesized by 11C-methylation of the desmethyl precursor with [11C]MeOTf in 3.0% non-corrected activity yield (based upon [11C]MeOTf), >99% radiochemical purity and high molar activity. Preliminary PET imaging with [11C]AZ683 revealed low brain uptake in rodents and nonhuman primates, suggesting that imaging neuroinflammation could be challenging but that the radiopharmaceutical could still be useful for peripheral imaging of inflammation.

Intranasal Opioid Administration in Rhesus Monkeys: PET Imaging and Antinociception

The goal of this study was to evaluate the effects of intranasally administered opioids in rhesus monkeys using the tail-withdrawal assay, and to correlate these effects with measures of receptor occupancy using positron emission tomography (PET) imaging. Initial experiments characterized the antinociceptive effects of intranasal (IN) fentanyl and buprenorphine relative to intramuscular (IM) injection. Fentanyl (0.010-0.032 mg/kg) and buprenorphine (0.1-1.0 mg/kg) produced dose-dependent increases in tail-withdrawal latency that did not differ between routes of delivery. The second experiment compared the ability of IN and intravenous (IV) naloxone (NLX) to block the antinociceptive effects IV fentanyl, and to measure receptor occupancy at equipotent doses of NLX using PET imaging. IN and IV NLX (0.0032-0.032 mg/kg) produced dose-dependent decreases in fentanyl-induced antinociception. Again, there was no difference observed in overall potency between routes. PET imaging showed that IV and IN NLX produced similar decreases in receptor occupancy as measured by [¹¹C]carfentanil blocking, although there was a trend for IV NLX to produce marginally greater occupancy changes. This study validated the first procedures to evaluate the IN effects of opioids in rhesus monkeys.

Investigation of Proposed Activity of Clarithromycin at GABAA Receptors Using [(11)C]Flumazenil PET

Clarithromycin is a potential treatment for hypersomnia acting through proposed negative allosteric modulation of GABAA receptors. We were interested whether this therapeutic benefit might extend to Parkinson's disease (PD) patients because GABAergic neurotransmission is implicated in postural control. Prior to initiating clinical studies in PD patients, we wished to better understand clarithromycin's mechanism of action. In this work we investigated whether the proposed activity of clarithromycin at the GABAA receptor is associated with the benzodiazepine binding site using in vivo [(11)C]flumazenil positron emission tomography (PET) in primates and ex vivo [(3)H]flumazenil autoradiography in rat brain. While the studies demonstrate that clarithromycin does not change the K d of FMZ, nor does it competitively displace FMZ, there is preliminary evidence from the primate PET imaging studies that clarithromycin delays dissociation and washout of flumazenil from the primate brain in a dose-dependent fashion. These findings would be consistent with the proposed GABAA allosteric modulator function of clarithromycin. While the results are only preliminary, further investigation of the interaction of clarithromycin with GABA receptors and/or GABAergic medications is warranted, and therapeutic applications of clarithromycin alone or in combination with flumazenil, to treat hyper-GABAergic status in PD at minimally effective doses, should also be pursued.

Synthesis of Diverse (11)C-Labeled PET Radiotracers via Direct Incorporation of [(11)C]CO2

Three new positron emission tomography (PET) radiotracers of interest to our functional neuroimaging and translational oncology programs have been prepared through new developments in [(11)C]CO2 fixation chemistry. [(11)C]QZ (glutaminyl cyclase) was prepared via a tandem trapping of [(11)C]CO2/intramolecular cyclization; [(11)C]tideglusib (glycogen synthase kinase-3) was synthesized through a tandem trapping of [(11)C]CO2 followed by an intermolecular cycloaddition between a [(11)C]isocyanate and an isothiocyanate to form the 1,2,4-thiadiazolidine-3,5-dione core; [(11)C]ibrutinib (Bruton's tyrosine kinase) was synthesized through a HATU peptide coupling of an amino precursor with [(11)C]acrylic acid (generated from [(11)C]CO2 fixation with vinylmagnesium bromide). All radiochemical syntheses are fully automated on commercial radiochemical synthesis modules and provide radiotracers in 1-5% radiochemical yield (noncorrected, based upon [(11)C]CO2). All three radiotracers have advanced to rodent imaging studies and preliminary PET imaging results are also reported.

Synthesis and Evaluation of [(18)F]RAGER: A First Generation Small-Molecule PET Radioligand Targeting the Receptor for Advanced Glycation Endproducts

The receptor for advanced glycation endproducts (RAGE) is a 35 kDa transmembrane receptor that belongs to the immunoglobulin superfamily of cell surface molecules. Its role in Alzheimer's disease (AD) is complex, but it is thought to mediate influx of circulating amyloid-β into the brain as well as amplify Aβ-induced pathogenic responses. RAGE is therefore of considerable interest as both a diagnostic and a therapeutic target in AD. Herein we report the synthesis and preliminary preclinical evaluation of [(18)F]RAGER, the first small molecule PET radiotracer for RAGE (Kd = 15 nM). Docking studies proposed a likely binding interaction between RAGE and RAGER, [(18)F]RAGER autoradiography showed colocalization with RAGE identified by immunohistochemistry in AD brain samples, and [(18)F]RAGER microPET confirmed CNS penetration and increased uptake in areas of the brain known to express RAGE. This first generation radiotracer represents initial proof-of-concept and a promising first step toward quantifying CNS RAGE activity using PET. However, there were high levels of nonspecific [(18)F]RAGER binding in vitro, likely due to its high log P (experimental log P = 3.5), and rapid metabolism of [(18)F]RAGER in rat liver microsome studies. Therefore, development of second generation ligands with improved imaging properties would be advantageous prior to anticipated translation into clinical PET imaging studies.

In Vivo Metabolic Trapping Radiotracers for Imaging Monoamine Oxidase-A and -B Enzymatic Activity

The isozymes of monoamine oxidase (MAO-A and MAO-B) are important enzymes involved in the metabolism of numerous biogenic amines, including the neurotransmitters serotonin, dopamine, and norepinephrine. Recently, changes in concentrations of MAO-B have been proposed to be an in vivo marker of neuroinflammation associated with Alzheimer's disease. Previous developments of in vivo radiotracers for imaging changes in MAO enzyme expression or activity have utilized the irreversible propargylamine-based suicide inhibitors or high-affinity reversibly binding inhibitors. As an alternative approach, we have investigated 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines as metabolic trapping agents for the monoamine oxidases. MAO-mediated oxidation and spontaneous hydrolysis yield 1-[(11)C]methyl-2,3-dihydro-4-pyridinone as a hydrophilic metabolite that is trapped within brain tissues. Radiotracers with phenyl, biphenyl, and 7-coumarinyl ethers were evaluated using microPET imaging in rat and primate brains. No isozyme selectivity for radiotracer trapping was observed in the rat brain for any compound, but in the monkey brain, the phenyl ether demonstrated MAO-A selectivity and the coumarinyl ether showed MAO-B selectivity. These are lead compounds for further development of 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines with optimized brain pharmacokinetics and isozyme selectivity.

Identification of quantitative trait loci influencing inflammation-mediated alveolar bone loss: insights into polygenic inheritance of host-biofilm disequilibria in periodontitis

BACKGROUND AND OBJECTIVE

The relative contribution of genetic and environmental factors to the onset and progression of periodontitis is inconclusive. Despite the high prevalence, phenotypic heterogeneity and significant local and systemic implications of this disease, early detection and individualized therapy are problematic. Using a murine model of periodontitis in a panel of 17 recombinant inbred mice, the current study addressed the heritability of, and oral dysbiosis associated with, inflammation-mediated alveolar bone loss (iABL), the hallmark of periodontitis.

MATERIAL AND METHODS

Quantitative trait locus (QTL) genomics and quantitative PCR for over 99% of known murine oral microbiota were used.

RESULTS

It was found that iABL is a polygenic trait with 32.7% heritability. One suggestive QTL, nicknamed inflammation-mediated alveolar bone loss locus (iABLL), was identified on chromosome 2. Eleven genes involved in innate immune responses and bone metabolism, particularly related to macrophage and osteoblast function, namely Etl4, Pdss1, Cobll1, 9330158F14Rik, Xirp2, Stk39, Mettl5, Metapl1, Itga6, Pdk1 and Sp3, were found in the iABLL using cis expression QTL and nonsynonymous single nucleotide polymorphism analyses. Specific oral microbiome shifts in saliva and tongue mucosa are associated with disease in this model.

CONCLUSION

Our results indicate that complex host-biofilm interactions generate pathogenic states that extend beyond subgingival biofilms and periodontal tissues. Although no temporal relationship between the onset of iABL and microbiome changes were established, our findings suggest that host factors may be responsible for pathogenic shifts in subgingival biofilms when persistent and undisturbed.

Synthesis and Initial in Vivo Studies with [(11)C]SB-216763: The First Radiolabeled Brain Penetrative Inhibitor of GSK-3

Quantifying glycogen synthase kinase-3 (GSK-3) activity in vivo using positron emission tomography (PET) imaging is of interest because dysregulation of GSK-3 is implicated in numerous diseases and neurological disorders for which GSK-3 inhibitors are being considered as therapeutic strategies. Previous PET radiotracers for GSK-3 have been reported, but none of the published examples cross the blood-brain barrier. Therefore, we have an ongoing interest in developing a brain penetrating radiotracer for GSK-3. To this end, we were interested in synthesis and preclinical evaluation of [(11)C]SB-216763, a high-affinity inhibitor of GSK-3 (K i = 9 nM; IC50 = 34 nM). Initial radiosyntheses of [(11)C]SB-216763 proved ineffective in our hands because of competing [3 + 3] sigmatropic shifts. Therefore, we have developed a novel one-pot two-step synthesis of [(11)C]SB-216763 from a 2,4-dimethoxybenzyl-protected maleimide precursor, which provided high specific activity [(11)C]SB-216763 in 1% noncorrected radiochemical yield (based upon [(11)C]CH3I) and 97-100% radiochemical purity (n = 7). Initial preclinical evaluation in rodent and nonhuman primate PET imaging studies revealed high initial brain uptake (peak rodent SUV = 2.5 @ 3 min postinjection; peak nonhuman primate SUV = 1.9 @ 5 min postinjection) followed by washout. Brain uptake was highest in thalamus, striatum, cortex, and cerebellum, areas known to be rich in GSK-3. These results make the arylindolemaleimide skeleton our lead scaffold for developing a PET radiotracer for quantification of GSK-3 density in vivo and ultimately translating it into clinical use.

Targeting Metal-Aβ Aggregates with Bifunctional Radioligand [11C]L2-b and a Fluorine-18 Analogue [18F]FL2-b

Interest in quantifying metal-Aβ species in vivo led to the synthesis and evaluation of [¹¹C]L2-b and [¹⁸F]FL2-b as radiopharmaceuticals for studying the metallobiology of Alzheimer’s disease (AD) using positron emission tomography (PET) imaging. [¹¹C]L2-b was synthesized in 3.6% radiochemical yield (nondecay corrected, n = 3), >95% radiochemical purity, from the corresponding desmethyl precursor. [¹⁸F]FL2-b was synthesized in 1.0% radiochemical yield (nondecay corrected, n = 3), >99% radiochemical purity, from a 6-chloro pyridine precursor. Autoradiography experiments with AD positive and healthy control brain samples were used to determine the specificity of binding for the radioligands compared to [¹¹C]PiB, a known imaging agent for β-amyloid (Aβ) aggregates. The K_d for [¹¹C]L2-b and [¹⁸F]FL2-b were found to be 3.5 and 9.4 nM, respectively, from those tissue studies. Displacement studies of [¹¹C]L2-b and [¹⁸F]FL2-b with PiB and AV-45 determined that L2-b binds to Aβ aggregates differently from known radiopharmaceuticals. Finally, brain uptake of [¹¹C]L2-b was examined through microPET imaging in healthy rhesus macaque, which revealed a maximum uptake at 2.5 min (peak SUV = 2.0) followed by rapid egress (n = 2).

Synthesis and evaluation of [11C]PBD150, a radiolabeled glutaminyl cyclase inhibitor for the potential detection of Alzheimer's disease prior to amyloid β aggregation

The phenol of 1-(3-(1H-imidazol-1-yl)propyl)-3-(4-hydroxy-3-methoxyphenyl)thiourea was selectively carbon-11 labelled to generate [¹¹C]PBD150 in 7.3% yield from [¹¹C]methyl triflate (non-decay corrected; radiochemical purity ≥95%, specific activity = 5.7 Ci/µmol, n=5). Evaluation of [¹¹C]PBD150 by small animal PET imaging (mouse and rat) determined it does not permeate the blood brain barrier, indicating previously described therapeutic effect in transgenic mice was likely not the result of inhibiting central nervous system glutaminyl cyclase.

High affinity radiopharmaceuticals based upon lansoprazole for PET imaging of aggregated tau in Alzheimer's disease and progressive supranuclear palsy: synthesis, preclinical evaluation, and lead selection

Abnormally aggregated tau is the hallmark pathology of tauopathy neurodegenerative disorders and is a target for development of both diagnostic tools and therapeutic strategies across the tauopathy disease spectrum. Development of carbon-11- or fluorine-18-labeled radiotracers with appropriate affinity and specificity for tau would allow noninvasive quantification of tau burden using positron emission tomography (PET) imaging. We have synthesized [(18)F]lansoprazole, [(11)C]N-methyl lansoprazole, and [(18)F]N-methyl lansoprazole and identified them as high affinity radiotracers for tau with low to subnanomolar binding affinities. Herein, we report radiosyntheses and extensive preclinical evaluation with the aim of selecting a lead radiotracer for translation into human PET imaging trials. We demonstrate that [(18)F]N-methyl lansoprazole, on account of the favorable half-life of fluorine-18 and its rapid brain entry in nonhuman primates, favorable kinetics, low white matter binding, and selectivity for binding to tau over amyloid, is the lead compound for progression into clinical trials.

Synthesis and evaluation of [(11)C]PyrATP-1, a novel radiotracer for PET imaging of glycogen synthase kinase-3β (GSK-3β)

INTRODUCTION

The dysfunction of glycogen synthase kinase-3β (GSK-3β) has been implicated in a number of diseases, including Alzheimer's disease. The ability to non-invasively quantify GSK-3β activity in vivo is therefore of critical importance, and this work is focused upon development of inhibitors of GSK-3β radiolabeled with carbon-11 to examine quantification of the enzyme using positron emission tomography (PET) imaging.

METHODS

(11)C PyrATP-1 was prepared from the corresponding desmethyl-piperazine precursor in an automated synthesis module. In vivo rodent and primate imaging studies were conducted on a Concorde MicroPET P4 scanner to evaluate imaging properties and in vitro autoradiography studies with rat brain samples were carried out to examine specific binding.

RESULTS

2035±518MBq (55±14mCi) of [(11)C]PyrATP-1 was obtained (1%-2% non-corrected radiochemical yield at end-of-synthesis based upon [(11)C]CO2) with high chemical (>95%) and radiochemical (>99%) purities, and good specific activities (143±52GBq/μmol (3874±1424Ci/mmol)), n=5. In vivo microPET imaging studies revealed poor brain uptake in rodents and non-human primates. Pretreatment of rodents with cyclosporin A resulted in moderately increased brain uptake suggesting Pgp transporter involvement. Autoradiography demonstrated high levels of specific binding in areas of the rodent brain known to be rich in GSK-3β.

CONCLUSION

(11)C PyrATP-1 is readily synthesized using standard carbon-11 radiochemistry. However the poor brain uptake in rodents and non-human primates indicates that the radiotracer is not suitable for the purposes of quantifying GSK-3β in neurological and psychiatric disorders.

Novel fluorine-18 PET radiotracers based on flumazenil for GABAA imaging in the brain

INTRODUCTION

Two 7-fluoroimidazobenzodiazepines (AH114726 and GEH120348), analogs of flumazenil, were labeled with fluorine-18 and evaluated as alternative radioligands for in vivo imaging of the GABAA/benzodiazepine receptor by comparing them to [(11)C]flumazenil in rhesus monkey.

METHODS

Radiotracers were prepared from the corresponding nitro-precursors in an automated synthesis module, and primate imaging studies were conducted on a Concorde MicroPET P4 scanner. The brain was imaged for 60 (12 × 5 min frames) or 90 min (18 × 5 min frames), and data was reconstructed using the 3D MAP algorithm. Specificity of [(18)F]AH114726 and [(18)F]GEH120348 was confirmed by displacement studies using unlabeled flumazenil.

RESULTS

[(18)F]GEH120348 and [(18)F]AH114726 were obtained in 13-24% yields (end of synthesis) with high chemical (>95%) and radiochemical (>99%) purities, and high specific activities (2061 ± 985 Ci/mmol). The in vivo pharmacokinetics of [(18)F]AH114726 and [(18)F]GEH120348 were determined in a non-human primate and directly compared with [(11)C]flumazenil. Both fluorine-18 radioligands showed time-dependent regional brain distributions that correlated with the distribution of [(11)C]flumazenil and the known concentrations of GABAA/benzodiazepine receptors in the monkey brain. [(18)F]AH114726 exhibited maximal brain uptake and tissue time-radioactivity curves that were most similar to [(11)C]flumazenil. In contrast, [(18)F]GEH120348 showed higher initial brain uptake but very different pharmacokinetics with continued accumulation of radioactivity into the cortical regions of high GABA/benzodiazepine receptor concentrations and very little clearance from the regions of low receptor densities. Rapid washout of both radiotracers occurred upon treatment with unlabeled flumazenil.

CONCLUSION

The ease of the radiochemical synthesis, together with in vivo brain pharmacokinetics most similar to [(11)C]flumazenil, support that [(18)F]AH114726 is a suitable option for imaging the GABAA receptor.

(-)-[(18) F]Flubatine: evaluation in rhesus monkeys and a report of the first fully automated radiosynthesis validated for clinical use

(-)-[(18) F]Flubatine was selected for clinical imaging of α4 β2 nicotinic acetylcholine receptors because of its high affinity and appropriate kinetic profile. A fully automated synthesis of (-)-[(18) F]flubatine as a sterile isotonic solution suitable for clinical use is reported, as well as the first evaluation in nonhuman primates (rhesus macaques). (-)-[(18) F]Flubatine was prepared by fluorination of the Boc-protected trimethylammonium iodide precursor with [(18) F]fluoride in an automated synthesis module. Subsequent deprotection of the Boc group with 1-M HCl yielded (-)-[(18) F]flubatine, which was purified by semi-preparative HPLC. (-)-[(18) F]Flubatine was prepared in 25% radiochemical yield (formulated for clinical use at end of synthesis, n = 3), >95% radiochemical purity, and specific activity = 4647 Ci/mmol (171.9 GBq/µmol). Doses met all quality control criteria confirming their suitability for clinical use. Evaluation of (-)-[(18) F]flubatine in rhesus macaques was performed with a Concorde MicroPET P4 scanner (Concorde MicroSystems, Knoxville, TN). The brain was imaged for 90 min, and data were reconstructed using the 3-D maximum a posteriori algorithm. Image analysis revealed higher uptake and slower washout in the thalamus than those in other areas of the brain and peak uptake at 45 min. Injection of 2.5 µg/kg of nifene at 60 min initiated a slow washout of [(18) F]flubatine, with about 25% clearance from the thalamus by the end of imaging at 90 min.

Evaluation of [(11)C]N-Methyl Lansoprazole as a Radiopharmaceutical for PET Imaging of Tau Neurofibrillary Tangles

[(11)C]N-Methyl lansoprazole ([(11)C]NML, 3) was synthesized and evaluated as a radiopharmaceutical for quantifying tau neurofibrillary tangle (NFT) burden using positron emission tomography (PET) imaging. [(11)C]NML was synthesized from commercially available lansoprazole in 4.6% radiochemical yield (noncorrected RCY, based upon [(11)C]MeI), 99% radiochemical purity, and 16095 Ci/mmol specific activity (n = 5). Log P was determined to be 2.18. A lack of brain uptake in rodent microPET imaging revealed [(11)C]NML to be a substrate for the rodent permeability-glycoprotein 1 (PGP) transporter, but this could be overcome by pretreating with cyclosporin A to block the PGP. Contrastingly, [(11)C]NML was not found to be a substrate for the primate PGP, and microPET imaging in rhesus revealed [(11)C]NML uptake in the healthy primate brain of ∼1600 nCi/cc maximum at 3 min followed by rapid egress to 500 nCi/cc. Comparative autoradiography between wild-type rats and transgenic rats expressing human tau (hTau +/+) revealed 12% higher uptake of [(11)C]NML in the cortex of brains expressing human tau. Further autoradiography with tau positive brain samples from progressive supranuclear palsy (PSP) patients revealed colocalization of [(11)C]NML with tau NFTs identified using modified Bielschowsky staining. Finally, saturation binding experiments with heparin-induced tau confirmed K d and Bmax values of [(11)C]NML as 700 pM and 0.214 fmol/μg, respectively.

In vivo [11C]dihydrotetrabenazine binding in rat striatum: sensitivity to dopamine concentrations

INTRODUCTION

The sensitivity of the in vivo binding of [(11)C]dihydrotetrabenazine ([(11)C]DTBZ) and [(11)C]methylphenidate ([(11)C]MPH) to their respective targets - vesicular monoamine transporter type 2 (VMAT2) and neuronal membrane dopamine transporter - after alterations in endogenous levels of dopamine was examined in the rat brain.

METHODS

In vivo binding of [(11)C]DTBZ and [(11)C]MPH was determined using a bolus+infusion protocol. The in vitro number of VMAT2 binding sites was determined by autoradiography.

RESULTS

Repeated dosing with alpha-methyl-p-tyrosine (AMPT) at doses that significantly (-75%) depleted brain tissue dopamine levels resulted in increased (+36%) in vivo [(11)C]DTBZ binding to VMAT2 in the striatum. The increase in binding could be completely reversed via treatment with L-DOPA/benserazide to restore dopamine levels. There were no changes in the total number of VMAT2 binding sites, as measured using in vitro autoradiography. No changes were observed for in vivo [(11)C]MPH binding to the dopamine transporter in the striatum following AMPT pretreatment.

CONCLUSION

These results indicate that large reductions in dopamine concentrations in the rat brain can produce modest but significant changes in the binding of radioligands to VMAT2, which can be reversed by replenishment of dopamine using exogenous L-DOPA.

Isolated posterior cerebral artery dissection: report of three cases

Isolated dissection of the posterior cerebral artery (PCA) is a rare but important cause of stroke in younger patients, particularly women. We present 3 cases of dissection of the P2 segment of the PCA. In 2 patients, an association with minor axial head trauma was documented, suggesting shearing injury of the PCA as it crosses over the free edge of the tentorium. The clinical and imaging findings are discussed, and the therapeutic management is reviewed.

Behavioral and neurochemical consequences of long-term intravenous self-administration of MDMA and its enantiomers by rhesus monkeys

The effects of self-administered 3,4-methylenedioxymethamphetamine (MDMA) on behavior and neurochemistry have not been previously studied in laboratory primates. We investigated the capacity of MDMA and its enantiomers to maintain contingent responding over an extended duration, whether any decrements in the reinforcing effects of these compounds would be observed over time, whether such decrements would be MDMA-selective, and whether any neurochemical correlates could be identified. Animals were previously trained to self-administer cocaine, then exposed to periodic substitutions of various doses of racemic MDMA and its enantiomers; full dose-effect curves were generated for each MDMA compound repeatedly over the duration of the study. After approximately 18 months of MDMA self-administration, drug exposure was halted and after at least 2 months drug abstinence, animals were scanned using positron emission tomography (PET) with the vesicular monoamine transporter (VMAT) ligand dihydrotetrabenazine (DTBZ). Shortly thereafter, animals were euthanized, brains were dissected, and samples were assayed for brain monoamines and their metabolites using high-performance liquid chromatography (HPLC), and for VMAT using DTBZ binding. The reinforcing effects of racemic and R(-)-MDMA were reduced over a long series (months) of individual self-administration access periods; the reinforcing effects of S+-MDMA were more resistant to this effect, but were attenuated for one animal. The reinforcing effects of cocaine were not altered by chronic MDMA self-administration, nor was the VMAT binding potential as assessed by PET. Further, there were no measurable decrements in serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) or VMAT in any brain regions assayed. The reinforcing effects of MDMA are selectively attenuated by chronic MDMA self-administration, although this behavioral change appears to occur in the absence of any frank neurochemical correlates of toxicity.

Removal of hormones and pharmaceuticals in the Advanced Water Recycling Demonstration Plant in Queensland, Australia

An advanced water recycling demonstration plant was employed to investigate the effectiveness of a number of treatment technologies in the removal of some residuals of commonly prescribed pharmaceuticals as well as natural and synthetic hormones found in sewage. Analysis of targeted compounds was carried out by solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). Initial tests were undertaken to determine the background concentrations of the analytes during various stages of treatment. Subsequent tests, undertaken by spiking with standard solutions of the target compounds provided further information on the removal efficiencies of some selected treatment modules. The results of the study indicate that while ozonation, microfiltration and nanofiltration were partially effective, treatment by reverse osmosis was the most universally successful in the removal of the target residuals. While significantly more data is required for a full evaluation, this initial investigation suggests that reverse osmosis may be an effective means of removing a wider range of pharmaceutically active residuals and hormones from treated sewage.

Total knee arthroplasty after open reduction and internal fixation of fractures of the tibial plateau: a minimum five-year follow-up study

BACKGROUND

There is little information in the literature regarding the outcome of total knee arthroplasty following open reduction and internal fixation of fractures of the tibial plateau. The goal of this study was to evaluate the results of such procedures after a minimum of five years of follow-up.

METHODS

We retrospectively analyzed the outcomes of fifteen total knee arthroplasties performed at an average of 38.6 months (range, eight months to eleven years) after open reduction and internal fixation of a fracture of the tibial plateau in fifteen consecutive patients. The average duration of follow-up after the total knee arthroplasty procedures was 6.2 years (range, 5.4 to 11.1 years). The average age of the patients was fifty-six years (range, thirty-seven to sixty-eight years) at the time of the arthroplasty. We evaluated the outcomes on the basis of the Hospital for Special Surgery knee score, the Short Form-36 score, and radiographs of the knees.

RESULTS

The average Hospital for Special Surgery knee score was 51 points (range, 20 to 74 points) before the arthroplasty, and it increased to 80 points (range, 44 to 91 points) postoperatively. Four knees were scored as excellent, eight had a good result, one was rated as fair, and two had a poor result. The average Short Form-36 scores were 58.0 points for general health, 72.4 points for bodily pain, 72.1 points for mental health, 58.3 points for physical functioning, 84.6 points for physical role functioning, 81.0 points for social functioning, and 57.7 points for vitality. The average active postoperative arc of motion was 105 degrees (range, 70 degrees to 135 degrees ) compared with 87 degrees (range, 20 degrees to 125 degrees ) preoperatively. Incomplete radiolucencies were noted on all of the postoperative radiographs made after the total knee arthroplasties. There was a high rate of infection (three patients), patellar tendon disruption (two patients), and postoperative secondary procedures (three patients required closed manipulation). The patients with infection were considered to have a failure of treatment: two required arthrodesis, and one required a two-stage exchange.

CONCLUSION

On the basis of our results, we concluded that total knee arthroplasty after open reduction and internal fixation of a fracture of the tibial plateau decreases pain and improves knee function, but the procedure is technically demanding and is associated with a high failure rate (five of fifteen).

Distinct outcomes of chloride diarrhoea in two siblings with identical genetic background of the disease: implications for early diagnosis and treatment

BACKGROUND

Congenital chloride diarrhoea (CLD, OMIM 214700) is a serious inherited defect of intestinal electrolyte absorption transmitted in an autosomal recessive fashion. The major clinical manifestation is diarrhoea with high chloride content which can be balanced by substitution. The molecular pathology involves an epithelial Cl(-)/HCO(3)(-) exchanger protein, encoded by the solute carrier family 26, member 3 gene (SLC26A3), previously known as CLD or DRA (downregulated in adenomas). To date, almost 30 different mutations in the SLC26A3 gene have been identified throughout the world. No clear genotype-phenotype correlation has been established.

PATIENTS/METHODS

Two siblings presenting with CLD were studied for disease history, supplementation, or other treatments, and for mutations in the SLC26A3 gene.

RESULTS

Mutation analysis revealed a homozygous I544N mutation in both patients. However, despite the uniform genetic background of CLD in this family, the clinical picture and outcome of the disease were remarkably different between siblings. The older sibling had a late diagnosis and chronic course of the disease whereas the younger one, who was diagnosed soon after birth and immediately received supplementation therapy, grows and develops normally.

CONCLUSION

Time of diagnosis, substitution therapy, compliance, and compensatory mechanisms are more important modulators of the clinical picture of CLD than the type of mutation in the SLC26A3 gene.

JlpA, a novel surface-exposed lipoprotein specific to Campylobacter jejuni, mediates adherence to host epithelial cells

A 1116 bp open reading frame (ORF), designated jlpA, encoding a novel species-specific lipoprotein of Campylobacter jejuni TGH9011, was identified from recombinant plasmid pHIP-O. The jlpA gene encodes a polypeptide (JlpA) of 372 amino acid residues with a molecular mass of 42.3 kDa. JlpA contains a typical signal peptide and lipoprotein processing site at the N-terminus. The presence of a lipid moiety on the JlpA molecule was confirmed by the incorporation of [3H]-palmitic acid. Immunoblotting analysis of cell surface extracts prepared using glycine-acid buffer (pH 2.2) and proteinase K digestion of whole cells indicated that JlpA is a surface-exposed lipoprotein in C. jejuni. JlpA is loosely associated with the cell surface, as it is easily extracted from the C. jejuni outer membrane by detergents, such as sarcosyl and Triton X-100. JlpA is released to the culture medium, and its concentration increases in a time-dependent fashion. The adherence of both insertion and deletion mutants of jlpA to HEp-2 epithelial cells was reduced compared with that of parental C. jejuni TGH9011. Adherence of C. jejuni to HEp-2 cells was inhibited in a dose-dependent manner when the bacterium was preincubated with anti-GST-JlpA antibodies or when HEp-2 cells were preincubated with JlpA protein. A ligand-binding immunoblotting assay showed that JlpA binds to HEp-2 cells, which suggests that JlpA is C. jejuni adhesin.

ICTS, an interventional cardiology training system

In this article, we present an Interventional Cardiology Training System developed by the Medical Application Group at Mitsubishi Electric in collaboration with the Center for Innovative Minimally Invasive Therapy. The core of the ICTS is a computer simulation of interventional cardiology catheterization. This simulation integrates clinical expertise, research in learning, and technical innovations to create a realistic simulated environment. The goal of this training system is to augment the training of new cardiology fellows as well as to introduce cardiologists to new devices and procedures. To achieve this goal, both the technical components and the educational content of the ICTS bring new and unique features: a simulated fluoroscope, a physics model of a catheter, a haptic interface, a fluid flow simulation combined with a hemodynamic model and a learning system integrated in a user interface. The simulator is currently able to generate--in real-time--high quality x-ray images from a 3D anatomical model of the thorax, including a beating heart and animated lungs. The heart and lung motion is controlled by the hemodynamic model, which also computes blood pressure and EKG. The blood flow is then calculated according to the blood pressure and blood vessel characteristics. Any vascular tool, such as a catheter, guide wire or angioplasty balloon can be represented and accurately deformed by the flexible tool physics model. The haptics device controls the tool and provides appropriate feedback when contact with a vessel wall is detected. When the catheter is in place, a contrast agent can be injected into the coronary arteries; blood and contrast mixing is computed and a visual representation of the angiogram is displayed by the x-ray renderer. By bringing key advances in the area of medical simulation--with the real-time x-ray renderer for instance--and by integrating in a single system both high quality simulation and learning tools, the ICTS opens new perspectives for computer based training systems.

Rapid and differential losses of in vivo dopamine transporter (DAT) and vesicular monoamine transporter (VMAT2) radioligand binding in MPTP-treated mice

The dose- and time-dependent changes of in vivo radioligand binding to the neuronal membrane dopamine transporter (DAT) and vesicular monoamine transporter type 2 (VMAT2) were examined in mouse brain after MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) administrations. Regional brain distribution studies were done in male C57BL/6 mice using simultaneous injections of d-threo-[(3)H]methylphenidate (DAT) and (+)-alpha-[(11)C]dihydrotetrabenazine (VMAT2). Single (55 mg/kg i.p. ) or multiple (4 x 10 mg/kg i.p., 1-hour intervals) administration of MPTP caused significant reductions in [(3)H]methylphenidate and [(11)C]dihydrotetrabenazine specific striatal binding, measured 14 days later. The single high dose of MPTP produced greater losses of [(11)C]dihydrotetrabenazine binding than did the multiple MPTP dosing regimen. Using the single high dose of MPTP, changes of in vivo binding of the two radioligands were determined at 1, 3, and 14 days after neurotoxin injection. At 1 day, there are large losses of [(3)H]methylphenidate binding (DAT) but no changes in [(11)C]dihydrotetrabenazine binding to the VMAT2 site in the striatum. At 3 and 14 days, there were >50% losses of binding of both bot radioligands, but significantly (P < 0.001) greater losses of VMAT2 binding of [(11)C]dihydrotetrabenazine. These studies indicate that the losses of the neuronal membrane and vesicular transporters are not always equal, and do not occur in the same time frame, after administration of the neurotoxin MPTP.

Magnetic resonance imaging to distinguish the type and severity of pediatric inflammatory bowel diseases

BACKGROUND

The distinction between ulcerative colitis and Crohn's disease is important, because treatment options and clinical course may vary. Magnetic resonance imaging (MRI) allows noninvasive transmural assessment of the intestine and may facilitate differentiation of ulcerative colitis from Crohn's disease. The objective of this prospective study was to determine whether MRI differentiates Crohn's disease from ulcerative colitis in children as effectively as colonoscopy with mucosal biopsies.

METHODS

Fifteen patients underwent colonoscopy with biopsies followed by abdominal MRI. The MRI diagnosis, determined by two radiologists independently completing a standardized form was compared with the gastroenterologic diagnosis.

RESULTS

After colonoscopy and review of histology, Crohn's disease was diagnosed in nine patients, ulcerative colitis in five, and indeterminate colitis in one, who was excluded from study. Agreement of the MRI diagnosis with the gastroenterologic diagnosis was 4 of 4 (100%) for ulcerative colitis, 4 of 10 (40%) for Crohn's disease considering both radiologists, and 5 of 10 (50%) for Crohn's disease for each radiologist individually. Percentage of enhancement by MRI did not correlate with the severity of inflammation determined at endoscopy among the patients with Crohn's disease (r = -0.3, P = 0.366). There was agreement on severity of inflammation in three of four patients with ulcerative colitis.

CONCLUSIONS

Current MRI interpretation of inflammatory bowel disease did not adequately recognize Crohn's disease in children. Therefore, colonoscopy with biopsy remains the most accurate tool for determining the type and severity of inflammatory bowel disease in children and adolescents.

Dynamics of a shallow fluidized bed

The results of the experimental study of the dynamics of a shallow fluidized bed are reported. The behavior of granular material is controlled by the interplay of two factors--levitation due to the upward airflow, and sliding back due to gravity. Near the threshold of instability, the system shows critical behavior with remarkably long transient dynamics. The experimental observations are compared with a simple cellular automata model.

Canadian Helicobacter Study Group Consensus Conference on the Approach to Helicobacter pylori Infection in Children and Adolescents

Gastric infection with Helicobacter pylori is common in both children and adults, but children are considerably less susceptible to peptic ulcers and other pathological sequelae. As a result, the risk to benefit ratio of diagnostic studies and therapeutic regimens for H pylori in adults are likely different from those in pediatric populations. These guidelines for the management of pediatric H pylori infection, developed by the Canadian Helicobacter Study Group, are designed to identify when the diagnosis and treatment of H pylori may improve patient care. Given the low prevalence of this infection in Canada, it is important to recognize that indiscriminate testing and treatment programs in children are not recommended, and indeed may threaten the optimal care of children. Diagnostic tests should be employed judiciously and be reserved for children who are most likely to derive measurable benefit, such as those likely to have peptic ulcer disease. At this time a test and treat strategy in children cannot be considered prudent, evidence based or cost effective. It is appropriate to limit diagnosis and treatment to children and adolescents in whom H pylori has been identified during endoscopic investigation.

N-[11C]methylpiperidine esters as acetylcholinesterase substrates: an in vivo structure-reactivity study

A series of simple esters incorporating the N-[11C]methylpiperidine structure were examined as in vivo substrates for acetylcholinesterase in mouse brain. 4-N-[11C]Methylpiperidinyl esters, including the acetate, propionate and isobutyrate esters, are good in vivo substrates for mammalian cholinesterases. Introduction of a methyl group at the 4-position of the 4-piperidinol esters, to form the ester of a teritary alcohol, effectively blocks enzymatic action. Methylation of 4-N-[11C]methylpiperidinyl propionate at the 3-position gives a derivative with increased in vivo reactivity toward acetylcholinesterase. Esters of piperidinecarboxylic acids (nipecotic, isonipecotic and pipecolinic acid ethyl esters) are not hydrolyzed by acetylcholinesterase in vivo, nor do they act as in vivo inhibitors of the enzyme. This study has identified simple methods to both increase and decrease the in vivo reactivity of piperidinyl esters toward acetylcholinesterase.

Outcome after ileoanal anastomosis in pediatric patients with ulcerative colitis

BACKGROUND

To review the outcome after restorative proctocolectomy among children and adolescents with ulcerative colitis at a pediatric inflammatory bowel disease center.

METHODS

The records of all patients with ulcerative colitis undergoing colectomy and ileoanal anastomosis at The Hospital for Sick Children, Toronto, Canada, were reviewed. Questionnaires concerning functional results were sent to patients with restored transanal defecation.

RESULTS

Seventy three patients (mean age, 13.2 years; range, 2.6-18.8 years) underwent ileoanal anastomosis (19 straight ileoanal anastomosis, 41 J pouch, 13 S pouch) between January 1980 and June 1995 and were observed 5.8+/-3.3 years. The ileoanal anastomosis is nonfunctional in 19 (26%) patients. Excision rates according to type of restorative procedure were J pouch, 7% (3 of 41); S pouch, 32% (4 of 13); and straight ileoanal anastomosis, 32% (6 of 19). Failure was usually attributable to intractable diarrhea among patients with straight ileoanal anastomosis but was caused by anastomotic leak or pelvic-perianal sepsis among patients with pouch procedures. Failure rates did not vary with age at ileoanal anastomosis. Among patients retaining ileoanal continuity, continence problems reported in the questionnaire were frequent and tended to be more extreme among younger patients. Overall, 90% of respondents reported satisfaction with the functional outcome of the restorative operation.

CONCLUSIONS

The success rate of the ileoanal anastomosis/J-pouch procedure is comparable to that in adult series. The ileoanal anastomosis/J-pouch procedure is the operation of choice for children and adolescents who want ileoanal continuity restored after colectomy for ulcerative colitis.