Calcium-dependent action potentials in mouse spinal cord neurons in cell culture

Following blockade of membrane potassium conductance with tetraethylammonium ions or 3-aminopyridine, long-duration action potentials were recorded from mouse spinal cord neurons in primary dissociated cell culture. The action potentials were calcium-dependent since they: (1) were not blocked by the sodium-channel blocker tetrodotoxin, (2) could be recorded in sodium-free, calcium-containing medium (3) could not be evoked in sodium-containing, calcium-free medium, (4) were blocked by calcium channel blockers manganese and cobalt and (5) had overshot amplitudes that varied linearly with the log of the extracellular calcium concentration (slope of 27.5 mV/decade change in calcium concentration).     

Quantification in Patient Urine Samples of Felbamate and Three Metabolites: Acid Carbamate and Two Mercapturic Acids

PURPOSE: Previously we proposed and provided evidence for the metabolic pathway of felbamate (FBM), which leads to the reactive metabolite, 3-carbamoyl-2-phenylpropion-aldehyde. This aldehyde carbamate was suggested to be the reactive intermediate in the oxidation of 2-phenyl-1,3-propanediol monocarbamate to the major human metabolite 3-carbamoyl-2-phenylpropionic acid. In addition, the aldehyde carbamate was found to undergo spontaneous elimination to 2-phenylpropenal, commonly known as atropaldehyde. Moreover, atropaldehyde was proposed to play a role in the development of toxicity during FBM therapy. Evidence for atropaldehyde formation in vivo was reported with the identification of modified N-acetyl-cysteine conjugates of atropaldehyde in both human and rat urine after FBM administration. Identification of the atropaldehyde-derived mercapturic acids in urine after FBM administration is consistent with the hypothesis that atropaldehyde is formed in vivo and that it reacts with thiol nucleophiles. Based on the hypothesis that the potential for toxicity will correlate to the amount of atropaldehyde formed, we sought to develop an analytic method that would quantify the amount of relevant metabolites excreted in patient urine. METHODS: We summarize the results of an LC/MS method used to quantify FBM, 3-carbamoyl-2-phenylpropionic acid and two atropaldehyde-derived mercapturic acids in the patient population. RESULTS: Analysis was performed on 31 patients undergoing FBM therapy. The absolute quantities of FBM and three metabolites were measured. CONCLUSIONS: This method demonstrated sufficient precision for the identification of patients exhibiting "abnormal" levels of atropaldehyde conjugates and may hold potential for patient monitoring.     

Total abdominal and pelvic radiotherapy in the management of early stage ovarian carcinoma

In a prospective study, 57 women with early stage ovarian carcinoma received total abdominal and pelvic radiotherapy (TAPR) following radical surgery. The whole abdomen received 22.5 Gy m.p.d. by large opposed fields in 18 fractions over 4 1/2 weeks, with 8 MeV X rays, followed by a further 22.5 Gy in 10 fractions over 2 weeks to the pelvis alone, using a dosage and technique similar to that described from the Princess Margaret Hospital, Toronto. The actuarial 5-year relapse-free and overall survival figures were 49 and 57% respectively, which appear to be significantly worse than those reported from Toronto (73% and 75%). The incidence of severe bowel toxicity (7%) was higher. There was no correlation between survival and FIGO stage at laparotomy, but a significant correlation with histological grade. These data do not seem to support the idea of a "curative" role for post-operative irradiation at this dosage in these patients.