similar situation is occasionally encountered in parkinsonian patients unresponsive to large doses of Sinemet, who rarely respond to even small doses of a dopamine agonist.It is possible that in some degenerative disorders (e.g., progressive supranuclear palsy), exogenous L-dopa cannot be decarboxylated because of selective damage to all o r most of the striatal elements that contain dopa decarboxylase [2]. In this situation, direct stimulation of the relatively intact postsynaptic dopamine receptors by bromocriptine, a direct dopamine agonist, on the striatal efferent neurons may result in clinical improvement.

No abstract

We tested the brain tissues of the Chamorro people of Guam who died of amyotrophic lateral sclerosis/Parkinsonism dimentia complex (ALS/PDC) for the neurotoxin beta-methylamino-l-alanine (BMAA). We used validated high-pressure liquid chromatography and liquid chromatography-mass spectrometry analyses to test well-characterized archival tissues of the superior frontal gyrus from eight Chamorros from Guam and a comparison group of 15 Canadians. BMAA was found as a free amino acid in 83% of Chamorro ALS/PDC patients (3-10 microg/g) as a protein-associated amino acid in 100% of the Chamorro individuals (149-1190 microg/g). Both forms of BMAA were also found at comparable levels in two Canadians who died of progressive neurodegenerative disease. BMAA, which is produced by cyanobacteria, may be associated with some cases of neurodegenerative disease.