The liver pharmacological and xenobiotic gene response repertoire

We have used a supervised classification approach to systematically mine a large microarray database derived from livers of compound-treated rats. Thirty-four distinct signatures (classifiers) for pharmacological and toxicological end points can be identified. Just 200 genes are sufficient to classify these end points. Signatures were enriched in xenobiotic and immune response genes and contain un-annotated genes, indicating that not all key genes in the liver xenobiotic responses have been characterized. Many signatures with equal classification capabilities but with no gene in common can be derived for the same phenotypic end point. The analysis of the union of all genes present in these signatures can reveal the underlying biology of that end point as illustrated here using liver fibrosis signatures. Our approach using the whole genome and a diverse set of compounds allows a comprehensive view of most pharmacological and toxicological questions and is applicable to other situations such as disease and development

Nitrification and denitrification in the activated sludge process

The characteristics of the single-sludge nitrification-denitrification process were investigated using influent organics as the carbon source and nitrate as an electron acceptor to see if any oxygen savings could be obtained. The key research tools used were mathematical modeling, computer simulation, the library, and discussions with experienced operating engineers. A mathematical model was obtained from the literature for the nitrification process. The summary of simulations using the model was that complete nitrification can be achieved at a temperature of 20\sp\circC, with a dissolved oxygen concentration of 2 mg/l and a sludge age of 4-5 days. A mathematical model was developed for the single-sludge nitrification-denitrification process and the influence of denitrification on oxygen requirements was studied by simulation. The conclusion was that, depending on the COD/NH\sb4\sp+ ratio, savings in oxygen, by the use of nitrate as an electron acceptor are in the range of 3 to 8 percent