A previous report of this work (Ringeissen et al. 2003) described the use of 
nuclear magnetic resonance (NMR) spectroscopy coupled with multivariate 
statistical data analysis (MVDA) to identify novel biomarkers of peroxisome 
proliferation (PP) in Wistar Han rats. Two potential biomarkers of peroxisome 
proliferation in the rat were described, N-methylnicotinamide (NMN) and 
N-methyl-4-pyridone-3-carboxamide (4PY). The inference from these results was 
that the tryptophan-nicotinamide adenine dinucleotide (NAD(+)) pathway was 
altered in correlation with peroxisome proliferation, a hypothesis subsequently 
confirmed by TaqMan analysis of the relevant genes encoding two key enzymes in 
the pathway, aminocarboxymuconate-semialdehyde decarboxylase (EC 4.1.1.45) and 
quinolinate phosphoribosyltransferase (EC 2.4.2.19). The objective of the 
present study was to investigate these data further and identify other 
metabolites in the NMR spectrum correlating equally with PP. MVDA Partial Least 
Squares (PLS) models were constructed that provided a better prediction of PP in 
Wistar Han rats than levels of 4PY and NMN alone. The resulting Wistar Han rat 
predictive models were then used to predict PP in a test group of Sprague Dawley 
rats following administration of fenofibrate. The models predicted the presence 
or absence of PP (above on arbitrary threshold of >2-fold mean control) in all 
Sprague Dawley rats in the test group.