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Twelve genes involved in thiamin biosynthesis in prokaryotes have been identified and overexpressed. Of these, six are required for the thiazole biosynthesis (thiFSGH, thil, and dxs), one is involved in the pyrimidine biosynthesis (thiC), one is required for the linking of the thiazole and the pyrimidine (thiE), and four are kinase genes (thiD, thiM, thiL, and pdxK). The specific reactions catalyzed by ThiEF, Dxs, ThiDM, ThiL, and PdxK have been reconstituted in vitro and ThiS thiocarboxylate has been identified as the sulfur source. The X-ray structures of thiamin phosphate synthase and 5-hydroxyethyl-4-methylthiazole kinase have been completed. The genes coding for the thiamin transport system (thiBPQ) have also been identified. Remaining problems include the cloning and characterization of thiK (thiamin kinase) and the gene(s) involved in the regulation of thiamin biosynthesis. The specific reactions catalyzed by ThiC (pyrimidine formation), and ThiGH and ThiI (thiazole formation) have not yet been identified.

A common polymorphism in the alpha1-antichymotrypsin (ACT) gene is associated with Alzheimer's disease. ACT is also a trophic factor in the hippocampal neurons. In order to examine if the ACT gene plays a role in the pathogenesis of schizophrenic disorders, patients (n = 175) and control subjects (n = 114) were genotyped for ACT. We also investigated the relationship between genotypes and patients' cognitive function as evaluated by the Clinical Dementia Rating Scale and the Mini-Mental State Examination. The results demonstrated no association between schizophrenia and/or cognitive deficit in schizophrenia and ACT polymorphism. The data suggest that the ACT gene is not of major importance for the genesis of schizophrenia. Further studies measuring ACT expression as messenger RNA or serum ACT level may help to exclude the role of ACT in the pathogenesis of schizophrenia.

Schizophrenic disorders are complex genetic disorders and may involve multiple genes of small effect. The presence of apolipoprotein E (apoE) is associated with several neuropsychiatric disorders. Previous studies on apoE genotype distribution in schizophrenia have reported conflicting findings. We studied the genotype frequencies in a large group of schizophrenic patients. The genotype distribution was significantly different between the schizophrenic patients and the control subjects. Persons who were sigma3 carriers have an increased risk of schizophrenia. This result suggests that apoE isoforms may play a functional role in the pathogenesis of schizophrenic disorders. Some possible mechanisms regarding the effect of apoE on the development of schizophrenia are discussed.

The 10(5) resolving power and MS/MS capabilities of Fourier-transform mass spectrometry provide electrospray ionization mass spectra containing >100 molecular and fragment ion mass values of high accuracy. Applying these spectra to the detection and localization of errors and modifications in the DNA-derived sequences of proteins is illustrated with the thiCEFSGH thiamin biosynthesis operon from Escherichia coli. Direct fragmentation of the multiply-charged intact protein ions produces large fragment ions covering the entire sequence; further dissociation of these fragment ions provides information on their sequences. For ThiE (23 kDa), the entire sequence was verified in a single spectrum with an accurate (0.3 Da) molecular weight (Mr) value, with confirmation from MS/MS fragment masses. Those for ThiH (46 kDa) showed that the Mr value (1 Da error) represented the protein without the start Met residue. For ThiF (27 kDa), MS/MS localized a sequence discrepancy to a 34 residue peptide. The first 107 residues of ThiC (74 kDa) were shown to be correct, with C-terminal heterogeneity indicated. For ThiG (predicted Mr = 34 kDa), ESI/FTMS showed two components of 7,310.74 (ThiS) and 26,896.5 Da (ThiG); MS/MS uncovered three reading frame errors and a stop codon for the first protein. MS/MS ions are consistent with 68 fragments predicted by the corrected ThiS/ThiG DNA sequences.

Background: Paroxetine is a potent inhibitor of serotonin re-uptake. Although it has been widely used as an antidepressant in western countries, its efficacy and side effects in the Chinese are unknown., Methods: Patients with major depressive episode were recruited from the outpatient clinic and the acute wards of the Department of Psychiatry, Veterans General Hospital-Taipei in 1994. Severity of depression was evaluated with Hamilton Rating Scale for Depression (HAM-D), Clinical Global Impression (CGI) and the adverse effects were evaluated with Treatment Emergent Symptom Scale (TESS). Forty Chinese patients with HAM-D scores > or = 18 at the beginning of the first dose were randomized to receive paroxetine (20 to 30 mg/day) or imipramine (100 to 125 mg/day). The dosage was designed as a fixed-adjustable regimen for an active treatment period of six weeks. The patients and the clinical investigators were both blind to the medication until the end of the trial., Results: Five patients violating the trial protocol were excluded from this study, leaving 35 patients for efficacy and adverse effect analyses. Sixty-seven percent (12/18) of paroxetine-treated patients and 65% (11/17) of imipramine-treated patients showed a 50% or more reduction in HAM-D scores. The rate of patients whose mood recovered to normal or near-normal (borderline) was higher in the paroxetine group (66.7%) than in the imipramine group (35.3%), but the difference was not statistically significant (p = 0.13). At the end of this trial, the mean reduction of HAM-D scores was similar between groups (20.2 +/- 9.1 vs 15.3 +/- 8.4, p > 0.1). Three patients in the paroxetine group and two patients in the imipramine group withdrew prematurely due to adverse effects of impatience. Adverse effects of anticholinergic effects were reported more frequently in the imipramine group than in the paroxetine group (p = 0.01)., Conclusions: In comparison with imipramine, paroxetine affords fewer anticholinergic adverse effects without the sacrifice of efficacy in the treatment of depressed Chinese patients.