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M Desmond

Publications and source records attributed to M Desmond.

6 recordsLinked to original sources
PubMed1996

L-3,4-dihydroxyphenylalanine increases the quantal size of exocytotic dopamine release in vitro.

The catecholamine precursor L-3,4-dihydroxyphenylalanine (L-DOPA) is used to augment striatal dopamine (DA), although its mechanism of altering neurotransmission is not well understood. We observed the effects of L-DOPA on catecholamine release in ventral midbrain neuron and PC12 pheochromocytoma cell line cultures. In ventral midbrain neuron cultures exposed to 40 mM potassium-containing media, L-DOPA (100 microM for 1 h) increased DA release by > 10-fold. The elevated extracellular DA levels were not significantly blocked by the DA/norepinephrine transport inhibitor nomifensine, demonstrating that reverse transport through catecholamine-uptake carriers plays little role in this release. In PC12 cells, where DA release from individual secretory vesicles can be observed, L-DOPA (50 microM for 1 h) elevated DA release in high-potassium media by 370%. Amperometric measurements demonstrated that L-DOPA (50 microM for 40-70 min) did not raise the frequency of vesicular exocytosis but increased the average size of quantal release to at least 250% of control levels. Together, these findings suggest that L-DOPA can increase stimulation-dependent transmitter release from DA cells by augmenting cytosolic neurotransmitter, leading to increased quantal size.

Animals↗
PubMed1988

Case mix for nursing home payment: resource utilization groups, version II.

A study of 3,427 nursing home residents in New York State, measuring both resources used and resident characteristics, was used to develop a resident classification system for payment purposes. The system balances clinical, statistical, and administrative criteria, making it useful both for the New York State Medicaid payment system and for quality of care and facility management.

Activities of Daily Living↗