The role of systemic chemotherapy and optimal regimen in thymic carcinoma remains uncertain. We evaluated the clinical responsiveness of ADOC (cisplatin, doxorubicin, vincristine, and cyclophosphamide) chemotherapy for advanced thymic carcinoma that have distant metastatic or unresectable lesions. From 1996 to 2000, we treated eight cases of thymic carcinoma. According to the classification by Masaoka et al., the clinical stage in one case was IVa, whereas the others were IVb. Histologic subtypes were as follows: four cases were squamous cell carcinoma, two cases were undifferentiated, and two were small-cell carcinoma. All patients received 50 mg/m2 of cisplatin and 40 mg/m2 of doxorubicin intravenously on day 1, 0.6 mg/m2 of vincristine intravenously on day 3, and 700 mg/m2 of cyclophosphamide intravenously on day 4, ADOC regimen, respectively, at 3- to 4-week intervals. Six patients obtained a partial response after ADOC chemotherapy and the overall clinical response rate was 75%. There were no life-threatening side effects noted. Cisplatin plus VP-16 chemotherapy (PVP) was performed in three cases before the ADOC regimen, but PVP chemotherapy did not show beneficial effects in two patients. Median survival time was 19 months. ADOC chemotherapy appears to have significant activity against thymic carcinoma.
High doses of glycine have been reported to improve negative schizophrenic symptoms, suggesting that ingested glycine activates glutamatergic transmission via N-methyl-D-aspartate (NMDA) receptors. However, the pharmacokinetics of administered glycine in the brain has not been evaluated. In the present study, the time- and dose-dependent distributions of administered glycine were investigated from a pharmacokinetic viewpoint. Whole-body autoradiography of radiolabeled glycine was performed, and time-concentration curves for glycine and serine in plasma, cerebrospinal fluid (CSF), and brain tissues were obtained. Furthermore, pharmacokinetic parameters were calculated. For a more detailed analysis, the amount of glycine uptake in the brain was evaluated using the brain uptake index method. Radiolabeled glycine was distributed among periventricular organs in the brain. Oral administration of 2 g/kg of glycine significantly elevated the CSF glycine concentration above the ED50 value for NMDA receptors. The glycine levels in CSF were 100 times lower than those in plasma. Glycine levels were elevated in brain tissue, but with a slower time-course than in CSF. Serine, a major metabolite of glycine, was elevated in plasma, CSF, and brain tissue. Glycine uptake in brain tissue increased in a dose-dependent manner. Time-concentration curves revealed that glycine was most likely transported via the blood-CSF barrier and activated NMDA receptors adjacent to the ventricles. The pharmacokinetic analysis and the brain uptake index for glycine suggested that glycine was transported into brain tissue by passive diffusion. These results provide further insight into the potential therapeutic applications of glycine.
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