Using adult stem cells, Johns Hopkins researchers and a consortium of colleagues nationwide say they have generated the type of human neuron specifically damaged by Parkinson’s disease (PD) and used various drugs to stop the damage.Their experiments on cells in the laboratory, reported in the July 4 issue of the journal Science Translational Medicine, could speed the search for new drugs to treat the incurable neurodegenerative disease, but also, they say, may lead them back to better ways of using medications that previously failed in clinical trials.