George K. L. Tiong

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Rat pups were exposed in utero to the opiates methadone or buprenorphine by administering subcutaneous injections to the mothers daily for the duration of pregnancy. Met- and Leu-enkephalin in the brains of the pups were measured by specific radioimmunoassays. Methadone at 8 mg/kg but not 4 mg/kg significantly reduced enkephalin levels in the striatum.(More)
Substance P (SP) and calcitonin gene-related peptide (CGRP) are putative transmitters in the central and peripheral (sensory) nervous systems. In this study, we examined the effects of dependence on and withdrawal from morphine and methadone on brain SP and CGRP content. Female Long Evans rats (70-100 g) were provided with plain drinking water or solutions(More)
An enzyme-linked immunosorbent assay (ELISA) for the sulphoxide derivative of the opioid peptide methionine enkephalin (MOE) was developed and found to be sensitive and highly specific. Methionine enkephalin itself showed only low cross-reactivity (1.8%) in the assay while leucine enkephalin and the endorphins showed cross-reactivity no higher than 0.6%.(More)
Opioids were administered to female Long Evans rats in their drinking water. Maintenance doses of 0.8 and 0.4 mg/ml for morphine and methadone, respectively, were achieved using an ascending dosage schedule. Rats were decapitated 0, 20, or 60 min after naloxone (10 mg/kg, IP) or saline. Brain met-enkephalin-like immunoreactivity (ME-LI) was determined by(More)
Assays for the potent, highly lipophilic analgesic buprenorphine described in the literature include the radioimmunoassay (RIA), radioreceptor assay (RRA) and selected ion-monitoring. Problems arise with the use of hazardous and unstable ligand in the RIA and RRA and the need for an extraction step for RRA and selected ion-monitoring. An enzyme immunoassay(More)
1. A radio-immunoassay (RIA) for methionine-enkephalin sulfoxide was developed and was used to measure methionine-enkephalin, after oxidation, in the rat brain. 2. The RIA was performed together with assays that use commercially available met- and leu-enkephalin antisera. 3. Evidence is presented here indicating that antisera raised against the native(More)
1. An immunoassay technique employing an enzyme-labelled ligand was developed for the sulfoxide derivative of the opioid peptide methionine-enkephalin (MOE). 2. The sensitivity of the enzyme immunoassay (EIA) was approximately twofold higher than that achieved in the radio-immunoassay (RIA) using tritiated ligand. Cross-reactivities of leucine-enkephalin(More)
A conjugate of luteinizing hormone releasing hormone (LHRH) and avidin was used for immunizing mice and sheep. In mice, a range of adjuvants co-administered with the conjugate was shown to affect antibody titre and isotype. The commercially available Montanide and Ribi adjuvant emulsions, polyadenylic-polyuridylic acid, Quil A and Freund's complete adjuvant(More)