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EDITORIAL FOCUS

On the maturation of mathematical modeling of endocrine systems

Department of Medicine, University of California, Los Angeles, California 90025

THIS JOURNAL WAS FOUNDED AS a separate section of the American Journal of Physiology in the mid-1970s, with an expressed aim of making a congenial home for mathematical modeling of physiological systems. As the founding Editor, I made modest suggestions concerning styles of presentation (2) and established a mathematical modeling forum. As modeling practice matured, publications exhibiting dynamics of endocrine signals began to appear (3), but the true flowering of the enterprise occurred only after the general availability of microassays for hormones and of computers running strong statistical and simulation programs. The combination of richer data sets, especially from frequent sampling, with powerful data processing (e.g., using various distribution functions, linear and nonlinear filters and estimators, novel spectroscopic analyzers, mutual information, and Akaike information criteria, tests of "regularity" with the approximate entropy of Pincus, etc.) now exposes with unprecedented clarity the signal patterns constituting command and control in endocrine systems.

A study by D. M. Keenan and J. D. Veldhuis (1) appearing in this issue of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology is the latest in a series in which they and colleagues have revealed the dynamic richness of endocrine signaling in full splendor, drawing on many of the advances mentioned above. On the basis of this achievement, the authors are able to provide improved physiological accounts of the operations of the systems under study—here the hypothalamic-pituitary-glucocorticoid system in healthy human beings. Furthermore, as an extra dividend, they have exposed a diurnal (circadian rhythm?) contribution to the dynamic pattern, whose mechanism is yet to be specified.

The basis for my enthusiasm for this mature, new picture of the adrenal glucocorticoid system dynamics can be appreciated by comparing it with the best I could do 40 years ago (for example, see their Ref. 7). The substantial improvements by Keenan and Veldhuis give me great pleasure and satisfaction to see.

FOOTNOTES  

Address for reprint requests and other correspondence: F. E. Yates, Dept. of Medicine, Univ. of California, Los Angeles, CA (E-mail: feyates{at}aol.com).

REFERENCES

1. Keenan DM and Veldhuis JD. Cortisol feedback state governs adrenocorticotropin secretory-burst shape, frequency, and mass in a dual-waveform construct: time-of-day dependent regulation. Am J Physiol Regul Integr Comp Physiol 285: R950-R961, 2003.[Abstract/Free Full Text]
2. Yates FE. Good manners in good modeling: mathematical models and computer simulations of physiological systems. Am J Physiol Regul Integr Comp Physiol 234: R159-R160, 1978.[Free Full Text]
3. Yates FE. Analysis of endocrine signals: the engineering and physics of biochemical communication systems. Biol Reprod 24: 73-94, 1981.[Abstract]

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Yates, F. E. Search for Related Content PubMed PubMed Citation Articles by Yates, F. E.