In conclusion, endoscopy is not recommended for children living in developed countries who are asymptomatic after accidental caustic ingestion.

Levetiracetam is a new antiepileptic drug prescribed for the treatment of patients with refractory partial seizures with or without secondary generalization as well as for the treatment of juvenile myoclonic epilepsy. A rapid and specific method by high-performance liquid chromatography diode array detection was developed to measure the concentration of levetiracetam in human plasma. The trough plasma concentrations measured in 69 epileptic patients treated with 500 to 3000 mg/d of levetiracetam ranged from 1.1 to 33.5 microg/mL. The mean (range) levetiracetam plasma concentrations in responders and nonresponders were 12.9 microg/mL (4.6-21 microg/mL) and 9.5 microg/mL (1.1-20.9 microg/mL), respectively. A wide variability in concentration-response relationships was observed in patients. Using a receiver operating characteristic curve, the threshold levetiracetam concentration for a therapeutic response was 11 microg/mL. The sensitivity and specificity for this threshold levetiracetam concentration were 73% and 71%, respectively. According to chi analysis, this finding was not significant probably because of the small number of patients and because of their refractory seizure type. Nevertheless, the levetiracetam plasma concentration could be used to help clinicians detect severe intoxication or to verify compliance by repeating the measurement in patients.

A screening program aimed at the discovery of new antimicrotubule agents yielded RPR112378 and RPR115781, two natural compounds extracted from the Indian plant Ottelia alismoides. We report their isolation, structural determination, and mechanisms of action. RPR112378 is an efficient inhibitor of tubulin polymerization (IC(50) = 1.2 microM) and is able to disassemble preformed microtubules. Regarding tubulin activity, RPR115781 is 5-fold less active than RPR112378. Tubulin-RPR112378 complexes, when isolated by gel filtration, were able to block further tubulin addition to growing microtubules, a mechanism that accounts for the substoichiometric effect of the drug. RPR112378 was found to prevent colchicine binding but not vinblastine binding to tubulin. Although colchicine binding is known to induce an increase of tubulin GTPase activity, no such increase was observed with RPR112378. We show that RPR112378 is a highly cytotoxic compound and that RPR115781 is 10, 000-fold less active as an inhibitor of KB cell growth. Part of the cytotoxicity of RPR112378 is probably caused by a reaction of addition with sulfhydryl groups, an observation that has not been made with RPR115781. In conclusion, these molecules represent a new class of inhibitors of microtubule assembly with potential therapeutic value.

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Objective To assess telomerase activity (involved in cell immortalization and detectable in most malignant tumours but not in normal somatic tissues) as a marker in cancer diagnosis. Patients and methods Tissue telomerase activity was assayed by two different techniques, the telomeric repeat amplification protocol‐polymerase chain reaction (TRAP‐PCR) and a telomerase PCR‐enzyme linked immunosorbent assay. Malignant and inflammatory bladder lesions and their adjacent normal tissues were assessed for telomerase activity in a group of 18 patients, 14 of whom had urothelial carcinoma and four a nonspecific inflammatory lesion of the bladder. Results Eleven of the 14 tumour samples analysed were telomerase‐positive and two of the three telomerase‐negative tumour samples had a detectable ‘telomerase inhibitor’. In the apparently normal tissues next to bladder tumours, four of the 14 specimens were telomerase‐positive. Interestingly, these lesions were always next to high‐grade muscle‐invasive bladder tumours (pT2G3). Two of the four nonspecific inflammatory lesions (one of cystitis glandularis and one of severe dysplasia), known to be preneoplastic lesions, were also telomerase‐positive. Conclusion These results strongly suggest that the reactivation of telomerase may be an early event in bladder carcinogenesis, preceding morphological changes related to malignant transformation. Telomerase activity may therefore be useful both as an indicator of malignant potential in preneoplastic lesions, e.g. cystitis glandularis and severe dysplasia, and as a prognostic marker of bladder tumour relapse or progression.

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Administration of cyamemazine, an antipsychotic drug with anxiolytic properties, together with other antipsychotic agents is common in patients with schizophrenia. This retrospective study investigated the effects of cyamemazine on the steady-state plasma concentrations of risperidone and 9-hydroxyrisperidone in 47 patients treated with 1 to 12 mg/day of risperidone. Of these 47 patients, 24 were receiving cyamemazine comedication ("cyamemazine" group) and 23 patients were treated with risperidone alone ("control" group). Plasma concentrations were measured using a high-performance liquid chromatographic method with photodiode-array ultraviolet detection. The median plasma concentration of risperidone was significantly higher in the cyamemazine group (31.5 ng/mL) than in the control group (5.0 ng/mL), whereas the 9-hydroxyrisperidone median concentration was significantly lower in the cyamemazine group (16.5 ng/mL versus 39.0 ng/mL in the control group). However, the sum of risperidone plus 9-hydroxyrisperidone (active moiety) plasma concentration was not significantly affected by cyamemazine comedication. A combination with cyamemazine resulted in an inverted metabolic ratio (risperidone/9-hydroxyrisperidone). These findings suggest that cyamemazine inhibits the 9-hydroxylation of risperidone and is probably an inhibitor of cytochrome P450 2D6 as are many other phenothiazine drugs.