May KM Leung

Learn More
The presence of morphine-like and codeine-like substances was demonstrated in the pedal ganglia, hemolymph, and mantle tissues of the mollusc Mytilus edulis. The pharmacological activities of the endogenous morphine-like material resemble those of authentic morphine. Both substances were found to counteract, in a dose-dependent manner, the stimulatory(More)
Tetracyclines are now recognized to have non-antimicrobial properties with therapeutic potential--for example, these agents can inhibit pathologic collagenolysis by blocking mammalian collagenases and other matrix-degrading metalloproteinases. In the current study, adult human subjects with moderate chronic periodontitis were administered specially(More)
Evidence for the participation of opioid neuropeptides in immunoregulatory activities, especially cellular adherence and migration, has been obtained in representatives of two phyla of invertebrates, the mollusc Mytilus edulis and the insect Leucophaea maderae. The injection of a synthetic analog of [Met]enkephalin [( D-Ala2,Met5]enkephalinamide, DAMA;(More)
An acid extract of pedal ganglia of the mollusc Mytilus edulis was fractionated by high-pressure liquid chromatography with a reverse-phase column. Peak fractions with retention times of those of [Met]- and [Leu]enkephalin were subjected to binding assays in both invertebrate and vertebrate tissues. The results showed that these fractions have the same(More)
Various reports have shown that invertebrate hemocytes are responsive to mammalian neuropeptides and cytokines. In the present study, we demonstrate that corticotropin-releasing factor (CRF) and adrenocorticotropin (ACTH) fragments (1-24), (1-4), (4-9), (1-13), (1-17), and (11-24) significantly stimulate molluscan hemocyte migration, and the whole sequence(More)
The present report demonstrates that both mouse thymocytes and Mytilus edulis hemocytes contain a novel type of dopamine receptor. Scatchard analysis of these data revealed a single class of high-affinity binding sites with an affinity constant (Kd) of 6.6 nM, and a binding site density (Bmax) of 141 pmol/g protein in mice and a Kd of 7.6 nM and a Bmax of(More)
This study deals with a novel role of morphine in the modulation of cellular responsiveness to immunostimulatory substances that, at first glance, appears to be in contrast to the well documented immunoinhibitory short-term effects of opiate alkaloids on cells simultaneously exposed to stimulatory molecules. Vertebrate and invertebrate immunocytes(More)
D'-Ala-2 met-5-enkephalinamide application to the cerebral ganglia of Leucophaea maderae results in a decrease in locomotor activity. The opiate antagonist, naloxone, can block this effect as well as the depressant effect of morphine on locomotor activity. D-Ala-2,leu-5-enkephalinamide and dynorphin enhance locomotor activity following their topical(More)
A new therapeutic approach involves the discovery by the "Stony Brook group," that tetracyclines, but not other antibiotics, can inhibit host-derived collagen-destructive enzymes. This newly discovered property of tetracyclines is unrelated to the antimicrobial activity of these drugs. Examples support the hypothesis that this unexpected property of(More)