Evaluation and improvement of QSAR predictions of skin sensitization for pesticides.

In vivo skin sensitization assays have to be provided by applicants to the competent authorities in the European Union for the approval of active substances (AS) in pesticides. This study aimed to test the practicability of in silico predictions for AS by freely available (Q)SAR tools to evaluate their use as a time- and cost-effective alternative to animal testing in the context of the 3R concept. Predictions of skin sensitization for 48 selected sensitizing and non-sensitizing AS by the software programs CAESAR, Toxtree, OECD (Q)SAR Toolbox, CASE Ultra, Leadscope and SciQSAR were collected and compared. Different data evaluation methodologies (score definition, mean, weighted mean, threshold score definition) were applied to optimize the predictions. The calculation methods were internally cross-validated and further validated with an additional validation set of 80 AS. Although the presented calculation methodologies are not suitable as a stand-alone method, this study has shown weaknesses and strengths of some prominent (Q)SAR programs and diverse combinatorial options in the prediction of skin sensitization by pesticidal AS. The present study will help to foster discussions on in silico alternatives to animal testing in the pesticide area.

Treatment of familial hypercholesterolemia with a combination of bezafibrate and guar.

The effect of guar (15.6 g/day), a dietary fibre, and simultaneous administration of bezafibrate (600 mg/day) during dietetic treatment on the plasma lipoproteins and apolipoproteins was investigated in 12 patients with familial hypercholesterolemia (corresponding to the HLP type IIa pattern). Either bezafibrate alone or bezafibrate in combination with guar was administered in a cross-over study for 3 months. Guar led to an additional lowering of the total cholesterol in the plasma by 7% (P less than or equal to 0.05) associated with a fall of the low density lipoprotein cholesterol (LDL-cholesterol (LDL-cholesterol) by 13% (P less than or equal to 0.01) without any changes in the very low density lipoprotein (VLDL) and high density lipoprotein (HDL) cholesterols. In parallel with the decrease in LDL-cholesterol, the apoprotein B also was diminished by 20% (P less than or equal to 0.05). The plasma triglyceride level and the triglyceride distribution within the individual lipoprotein fractions were not altered in any consistent manner by the addition of guar. Neither the fasting plasma glucose level nor the body weight were affected. The side-effects due to guar treatment consisted of slight nausea, meteorism and constipation, but this did not in any of the cases lead to early termination of the study. These results demonstrate that guar exerts its cholesterol-lowering effect in addition to that of bezafibrate.