Modeling and Knowledge-Based Systems

Diagnostics for the identification and removal of poorly behaved parameters 

Evaluate in terms of similar compounds and statistical reliability 

The advent of molecular graphics and other facets of computational chemistry has led to an increased use of steric and electronic parameters in QSAR studies, and these quantities can now be calculated more precisely and 

Many of the aforementioned features are combined in integrated molecular modeling software such as SYBYL, Chem-X, COSMIC,80 Quanta and CHARMm, BIOGRAF, Insight and Discover, Chemlab, and MOLIDEA. These packages are available on a variety of hardware platforms ranging from personal computers (PCs) to mainframe computers. 

A number of computer-based expert systems have emerged that are more directly focused on toxicity evaluation these are HAZARDEXPERT (with its accompanying package, METABOLEXPERT), DEREK,86 and COMPACT.87-91 

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In Chapter 4, David Lewis introduces computer-assisted methods in the evaluation of chemical toxicology. He points out that any substance can be toxic, and thus it is the dose of the substance that determines a toxic response. How, then, does one predict toxicity Lewis examines QSAR methods, pattern recognition techniques, computer modeling, and knowledge-based systems to answer this question. Ideally, one would like to assess toxicity of a structure before the compound is synthesized. To bring all this into focus, emphasis is placed on the cytochromes P450. 

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