Using 'off the shelf', computer programs to mine additional insights from published data: diurnal variation in...

We describe the use of available computer programs to mine additional insights from published data. Graphs from four studies of ACTH and cortisol plasma levels collected throughout the 24 h day in humans were scanned into digital form and the data points extracted. To investigate the magnitude of ACTH stimulation of cortisol secretion across the 24 h, Monte Carlo methods were used to fit the parameters of a computer model of the ACTH-adrenal axis to the extracted data. ACTH was found to have a greater effect on cortisol secretion during the peaks of the cycle than at the nadir. This finding could not be explained by previously published dose response curves of ACTH effect. This implies that other modulators influence the effect of ACTH on the adrenal. This study also demonstrates how available computer programs can be used to examine models of physiologic regulation using data already available in the literature.