John R. Lever

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Recently, we have developed the positron emitting radiotracer N1'-([11C]methyl)naltrindole ([11C]MeNTI) and demonstrated its high selectivity for delta opioid receptors in the mouse brain [Lever et al. (1992) Eur. J. Pharmacol., 216:449-450]. In the present study, we examined the selectivity of [11C]MeNTI for the delta opioid receptor in the human brain,(More)
Development of cancer receptor-specific gold nanoparticles will allow efficient targeting/optimum retention of engineered gold nanoparticles within tumors and thus provide synergistic advantages in oncology as it relates to molecular imaging and therapy. Bombesin (BBN) peptides have demonstrated high affinity toward gastrin-releasing peptide (GRP) receptors(More)
Alterations in a variety of neurotransmitter systems have been identified in experimental models of epilepsy and in brain tissue from patients with intractable temporal lobe seizures. The availability of new high-affinity radioligands permits the study of some neuroreceptors in vivo with positron emission tomography (PET). We previously characterized the in(More)
We examined the mechanisms involved in protein kinase C (PKC)-dependent down-regulation of dopamine transporter (DAT) activity and cell surface expression by treating heterologously expressing cells with the clathrin-mediated endocytosis inhibitor concanavalin A (Con A) or the cholesterol depleter/membrane raft disrupter methyl-beta-cyclodextrin (MbetaC)(More)
Variously substituted phenyltropanes are proven as superb binding ligands for the dopamine transporter (DAT). In this study, we examine four N-substituted phenyltropanes which are derivatives of RTI-55 as in vivo binding ligands in mice. In this series, the methyl group on the nitrogen was replaced by a propyl (RTI-310), an allyl (RTI-311), a butyl(More)
The iodine-125 analog of the dopaminergically selective cocaine analog 3 beta-(4-iodophenyl)tropane-2 beta-carboxylic acid isopropyl ester (RT1-121) was evaluated as a probe for the dopamine transporter in rat striatum. Saturation and kinetic studies indicated that [125I]RTI-121 binds to both high and low affinity components. The Kd of the high affinity(More)
A selective ligand for the dopamine transporter 3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid isopropyl ester (RTI-121) has been labeled with iodine-125 by electrophilic radioiododestannylation. The [125I]RTI-121 was obtained in good yield (86 +/- 7%, n = 3) with high radiochemical purity (> 99%) and specific radioactivity (1210-1950 mCi/mumol). After(More)
The present study examined short- and long-term effects of MDMA (3,4-methylene-dioxymethamphetamine) on serotonin (5-HT2 and 5-HT1c) receptors in the brain of the rat. N1-Methyl-2-[125I]lysergic acid diethylamide ([125I]MIL) was used to label these receptors in vitro and in vivo. The usefulness of [125I]MIL for in vivo detection of changes in 5-HT2(More)
A no-carrier-added synthesis of 9-[(3-[18F]-fluoro-1-hydroxy-2-propoxy)methyl]-guanine ([18F]-FHPG) is reported. The 9-[(1,3-dihydroxy-2-propoxy)methyl)guanine (DHPG) was converted to 9-[N2,O-bis(methoxytrityl)-3-(tosyl)-2-propoxy-methyl]guanine by treatment with methoxytrityl chloride followed by tosylation. The tosylate was reacted with [18F]-KF in the(More)
The novel photoaffinity ligand N-[4-(4-azido-3-(125)I-iodophenyl)-butyl]-2-beta-carbomethoxy-3beta-(4-chlorophenyl) tropane ([(125)I]MFZ 2-24) was used to investigate the site for cocaine binding on the dopamine transporter (DAT). [(125)I]MFZ 2-24 irreversibly labeled both rat striatal and expressed human DAT with high affinity and appropriate(More)