ENVIRONMENTAL PARAMETERS ON SWEAT GLAND ACTIVITY 259 consistently perspired “sensibly” (eccrine activity) from the volar forearm earlier and more prolifi cally than Subject 1. Without debate, it is not statistically sound to draw solid conclu- sions from such a small study. However, since the two subjects were involved in 50 trials in the hot box and had become acutely familiar with their own sweating habits, trends in “I will sweat” vs. “I will not sweat” were very clearly understood prior to screening the fl ux density method. Hence, the authors believe that trends in fl ux density pulsing frequency are poten- tially related to “I will sweat today.” Continuing, TEWL measurements are typically recorded in environments that preclude emotional and sudorifi c interference. In our pre-equilibration/ acclimatization study, both subjects were isolated in the cool or warm conditions to curtail the inclusion of additional stresses. Initially, TEWL-like data, with TEWL-like fl ux density pro- fi les, were collected after emerging from cool environments (9–14 g−2 h−1) however, as the body warmed during acclimatization, upward trends in fl ux density (insensible water loss) steadily rose to plateaus. At the fl ux plateaus (≥30 min), both subjects clearly recognized they felt equilibrated and were “ready to sweat.” Hence, although increases in insensible sweating may not correlate with imminent eccrine sweating, increases and plateauing of vapor fl ux may be useful in assessing the proper environmental equilibration protocol for a subject. CONCLUDING REMARKS We adapted an established procedure to conduct studies of antiperspirant effi cacy using skin replica technology in conjunction with image analysis. Rheological analysis of skin replica gelation provided an understanding of the system’s kinetic behavior allowing it to be transferred easily to the in vivo procedure. Gravimetric studies were carried out to de- termine the kinetic behavior of axillae sweating. Differences in sudoriferous behavior were found to arise depending on the environmental conditions of the test. Further, other external factors, such as diet and physical motility, were found to greatly infl uence sweat output in the axillae. In addition, IR thermal imaging provided insight for the overall sweating behavior with respect to the method conditions. Monitoring variations in vapor fl ux from the skin surface improved the understanding of proper protocols for assigning equilibration times in the test procedure. In closing, we describe an affordable hot room testing capability for antiperspirant technologies that can be established in most labora- tories. Future work in this area will include a detailed analysis comparing effi cacy testing of antiperspirant technologies using this technique with established FDA protocols. ACKNOWLEDGMENTS We would like to thank Hani Fares and Linda Foltis for their collaboration and advice on antiperspirant technology and testing protocols. Also, we greatly appreciate the encour- agement and support of Bret Clark, Diane Kennedy, Ruthann Mekita, Gopi Menon, David J. Moore, Seher Ozkan, Donald Prettypaul, and Santosh Yadav. Finally, a great debt of gratitude is owed to all the volunteers involved in this study for their dedication and generous support. REFERENCES (1) H. J. Hurley, “The eccrine sweat glands: structure and function” in The Biology of the Skin, R.K. Freinkel and D.T. Woodley Eds., (The Parthenon Publishing Group, New York, 2002), pp. 47–76.

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