BK/TD models for analyzing in vitro impedance data on cytotoxicity.

The ban of animal testing has enhanced the development of new in vitro technologies for cosmetics safety assessment. Impedance metrics is one such technology which enables monitoring of cell viability in real time. However, analyzing real time data requires moving from static to dynamic toxicity assessment. In the present study, we built mechanistic biokinetic/toxicodynamic (BK/TD) models to analyze the time course of cell viability in cytotoxicity assay using impedance. These models account for the fate of the tested compounds during the assay. BK/TD models were applied to analyze HepaRG cell viability, after single (48 h) and repeated (4 weeks) exposures to three hepatotoxic compounds (coumarin, isoeugenol and benzophenone-2). The BK/TD models properly fit the data used for their calibration that was obtained for single or repeated exposure. Only for one out of the three compounds, the models calibrated with a single exposure were able to predict repeated exposure data. We therefore recommend the use of long-term exposure in vitro data in order to adequately account for chronic hepatotoxic effects. The models we propose here are capable of being coupled with human biokinetic models in order to relate dose exposure and human hepatotoxicity.

Impaired glucose tolerance in obese white children and adolescents: three to five year follow-up in untreated patients.

OBJECTIVE: Impaired glucose tolerance (IGT) is a predictor of type 2 diabetes in adults. However, the converting rate from IGT to diabetes is largely unknown in obese children. METHODS: We analyzed all 128 obese white European children diagnosed with IGT at our institution in the years 2003-2006 (mean age 13.5 ± 2.1 years, 53% female, mean BMI 31.7 ± 6.1 kg/m²) 3.0-5.6 years (mean 3.9 ± 0.6 years) later with an oral glucose tolerance test (oGTT). RESULTS: At follow-up, 20 (16%) children remained in the IGT status, 96 (75%) children converted to normal glucose metabolism, 3 (2%) children developed type 2 diabetes, and 9 (7%) children were lost to follow-up. Comparing the children according to their outcome concerning glucose metabolism at follow-up demonstrated that 2 h glucose levels in oGTT at baseline were significantly (p<0.001) higher in the children remaining IGT and highest in children developing diabetes, while the children did not differ in respect of age, gender, BMI, blood pressure, fasting glucose levels at baseline, or length of follow-up period. Apart from children developing diabetes, who increased their body weight, all the other children did not change their BMI, blood pressure, or fasting glucose levels significantly at follow-up. CONCLUSIONS: Obese white children with IGT will likely convert to normal glucose metabolism in the next 3-5 years. Risk factors for developing type 2 diabetes in follow-up were higher 2 h glucose levels in oGTT at baseline and weight gain.

Cryopreserved porcine hepatocytes: expression and induction of cytochrome P450, isoform CYP2E1.

Cryopreservation of porcine hepatocytes for their use in bioartificial liver devices may result in reduced cytochrome P450 (CYP) enzyme activity. The aim of this study was to assess the effects of several CYP inducers on the isoform CYP2E1 protein expression in cryopreserved porcine hepatocytes. Isolated porcine hepatocytes were cryopreserved for 1 month, thawed, and cultured for 3 days. During medium culture, the hepatocytes were exposed to the following CYP inducers: dimethyl sulfoxide, rifampicin, phenobarbital, 3-methylcholanthrene, and dexamethasone. CYP2E1 protein expression was determined by immunoblotting. CYP2E1 protein levels were constantly detected in cryopreserved porcine hepatocytes. CYP inducers did not modify CYP2E1 protein levels. Long-term cryopreserved porcine hepatocytes preserved their capacity for CYP2E1 protein expression, although exposure of these hepatocytes to CYP inducers did not modify the CYP2E1 protein expression.

A double-blind controlled trial of bovine brain gangliosides in amyotrophic lateral sclerosis.

We conducted a double-blind controlled study of the effect of brain gangliosides in amyotrophic lateral sclerosis. Nineteen patients received intramuscular gangliosides (40 mg/d) for 6 months, and 21 received placebo. The deterioration rates for approximately 120 clinical and electrophysiologic parameters of neuromuscular function were analyzed, but no statistically significant beneficial effect of the drug was demonstrated. However, the large coefficient of variation for each item indicated that a sample size of several hundred patients would have been necessary to exclude the possibility that the drug produced a 25% slowing of progression of the disease.

Dissociation between free and bound phenytoin levels in presence of valproate sodium.

A dissociation of free vs bound phenytoin levels is frequently observed in the presence of therapeutic doses of valproate sodium. This leads at times to symptoms and signs of phenytoin intoxication despite "therapeutic" plasma levels. The importance of supplementing bound levels with free levels is stressed when combined therapy of this type is used in epileptic patients.