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Summary: Regional CMR g lc was measured in seven healthy volunteers with positron emission tomography using [I-IIC]D-glucose. Regional CBF was measured us· ing [IIC]fluoromethane. The arteriovenous differences of unlabeled glucose and oxygen together with IIC metabo lites were also measured. In addition to the loss of [llC]COZ' a loss of acidic IIC metabolites was also de tected. A three-compartment model was applied to the tracer data in the time interval 0-24 min. After correction for the loss of IIC metabolites, the tracer method gave an

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Twenty-four acutely ill schizophrenic patients (DSM-III-R), 18-42 years old, were treated for 6 weeks with sulpiride. Sulpiride was administered in three different daily dosages (starting with 400, 800 or 1200 mg) according to a double blind randomized administration schedule. The monoamine metabolites (MAM) homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA), 4-hydroxy-3-methoxy-phenylglycol (HMPG) and the amino acids tyrosine, tryptophan, glutamate and glutamine were measured in serum before treatment and once a week during treatment. There were no significant differences between healthy controls and schizophrenic patients in serum levels of monoamine metabolites and amino acids before treatment. There was no dose-response effect of sulpiride on serum levels of the monoamine metabolites or the amino acids. The results are therefore based on the whole group of patients. During treatment the HMPG levels were reduced at all points in time. The serum level of HVA was significantly reduced after 6 weeks. The 5-HIAA and the amino acid levels were not changed during treatment. There were no significant correlations among the monoamine metabolites before treatment. During treatment, however, significant correlations were found among MAM and amino acids. Since the biochemical findings during the treatment were not related to the dose or the concentration of sulpiride the results may be related to secondary biochemical effects of sulpiride and/or to changes in the clinical state following treatment.

The synthesis of D- and L-(1-11C)tyrosine, starting with 11C-cyanide, is reported. DL-(1-11C)Tyrosine was prepared by the Bücherer-Strecker reaction, from carrier added 11C-cyanide with an incorporation of 80% in 20 min. The isolation of the pure D- and L-amino acid isomers from the enantiomeric mixture was accomplished within 15 min by preparative HPLC using a chiral stationary phase and a phosphate buffer as the mobile phase. Typically, the total synthesis time was 50 min (including purification) from end of trapping of 11C-cyanide, with a radiochemical yield of D- and L-amino acid of 40%-60%. The D- and L-(1-11C)tyrosine were both obtained optically pure, with a carrier added specific activity of 0.3-0.5 Ci/mmol and a radiochemical purity better than 99%. The 11C labelled L-tyrosine was used in an in vivo study in the human brain using positron emission tomography (PET).