An automated method for high-throughput amino acid analysis, using precolumn derivatization high-performance liquid chromatography/electrospray mass spectrometry (HPLC/ESI-MS), was developed and evaluated. The precolumn derivatization step was performed in the reaction port of a home-built auto-sampler system. Amino acids were derivatized with 3-aminopyridyl-N-hydroxysuccinimidyl carbamate, and a 3 microm Wakosil-II 3C8-100HG column (100 x 2.1 mm i.d.) was used for separation. To achieve a 13 min cycle for each sample, the derivatization and separation steps were performed in parallel. The results of the method evaluation, including the linearity, and the intra- and inter-precision, were sufficient to measure physiological amino acids in human plasma samples. The relative standard deviations of typical amino acids in actual human plasma samples were below 10%.

These results suggest that, in schizophrenia, regional thalamocortical white matter pathology is specifically associated with cortical pathology in regions where fibers connect.

A method for the comprehensive analysis of hydrophilic metabolites, based on a combination of high-performance liquid chromatography and mass spectrometry, is described. We evaluated three types of stationary phases to achieve the separation of highly hydrophilic metabolites. Good chromatographic retention and separation of these metabolites were achieved on a pentafluorophenylpropyl-bonded silica column with gradient elution, using 0.1% aqueous formic acid and acetonitrile as the mobile phase. The optimized conditions allowed the comprehensive determination of the standard 49 kinds of amino acids, 6 kinds of amines, 45 kinds of organic acids, 18 kinds of nucleic bases, 5 kinds of nucleosides, and 14 kinds of nucleotides, and then the linearity, dynamic range, detection limit, and precision of the retention time and the peak area were validated. We applied this method for the targeted analysis of the components in soy sauce. The results from the quantitative determination of amino acids were compared to those obtained with an amino acid analyzer, and the accuracy was in the range between 85 and 119%. The accuracy of other detected components was confirmed to be 105-133% by the recovery rate after the addition of standard compounds. We also applied the method for the nontargeted metabolic profiling of the components in several kinds of soy sauces with the principal component analysis. They were classified by the manufacturing methods, and the components that corresponded to the differences were identified. This method could be useful for the targeted analysis of hydrophilic metabolites as well as their nontargeted metabolic profiling.

Although the effects of aging on the neural correlates of schizophrenia have been researched for many years, no clear conclusion has been reached. While some studies have demonstrated progressive age-related gray matter reductions in schizophrenia, other studies have not found evidence of progression. Moreover, it remains unclear whether the influence of aging on global or regional cortical thickness differs between schizophrenia patients and healthy controls. This study aimed to confirm previous reports of reduced cortical thickness in schizophrenia, and to investigate the effects of age on global and regional cortical thickness. Eighty-three patients with schizophrenia (six first-episode patients and 77 chronic patients; age range=18-55 years) and 90 age-, gender- and education-matched healthy controls (age range=19-56 years) underwent structural magnetic resonance imaging (MRI) using a 3-Tesla scanner. Surface-based analysis was applied to assess cortical thickness in the whole brain. The patient group exhibited both global and regional cortical thinning in regions including the prefrontal and temporal cortices. The correlation between age and cortical thickness showed a similar pattern in patients and controls, both globally and regionally. These results suggest that the reduction of cortical thickness in schizophrenia might not be progressive over the course of the illness, indicating that pathological processes occur in a relatively limited period of time around the onset of illness.