Clinical disagreement on the diagnosis of transient ischemic attack: is the patient or the doctor to blame?

model for the study of neurotransmitter metabolism.'Therefore, we attempted to measure the concentration of glutamate and aspartate in platelets. We studied 12 healthy subjects ranging in age from 20 to 47 years (six men, six women). All were free of drugs known to affect platelet function for at least 2 weeks before the study. Blood (8 ml), drawn from an antecubital vein from subjects resting in the supine position, was placed into plastic tubes containing citrate. Platelet-rich plasma (PRP) was obtained after centrifugation at l(>5g for 15 minutes. Platelets were counted using a Baker-810 platelet analyzer. Thereafter, 1 ml PRP was centrifuged at 2500g for 15 minutes to obtain a platelet pellet, which was resuspended in 1 ml saline and sonicated for 5 minutes; 30 mg/ml sulfosalicylic acid was added to deproteinize the platelet preparation. This preparation was then centrifuged at 1200# for 5 minutes, and an aliquot of the supernatant was injected into a Millipore/Waters high-performance liquid chromatography column (Milford, Massachusetts) connected with a Perkin-Elmer fluorescence spectrometer (Norwalk, Connecticut). Glutamate and aspartate were measured using norvaline as an internal standard.