Kouichi Nakagawa obtained his Ph.D. from Boston University in 1989 and did postdoctoral researches at Northwestern University and University of Denver. Now, he is a Professor of Graduate School of Health Sciences at Hirosaki University. He has published more than 60 papers in international Journals and 8 book chapters, and serving on an editorial board member of Analytical Chemistry Insights.
EPR (electron paramagnetic resonance) spin-probe method along with spectral simulation was used to investigate structural changes of various stratum corneum (SC). The SC was stripped consecutively from one to three or four times using a glass plate coated with a cyanoacrylate resin. Aliphatic spin probes, 5-doxylstearic acid (5-DSA) and 3β-doxyl-5α-cholestane (CHL), were used to evaluate the SC ordering. EPR spectrum of 5-DSA incorporated in the SC demonstrated a characteristic peak for the first strip. A slow-tumbling simulation for 5-DSA showed clear differences in EPR intensities as well as ordering values (S0) of the SC for control and terpenes treated SC. In addition, a little, broad three-line pattern of 5-DSA in psoriasis vulgaris stratum corneum (pv-SC) was observed. The spectral pattern of pv-SC is quite different from those of control SC reported. The S0-values obtained for the pv-SC and the control were approximately 0.20 and 0.49, respectively. The statistical analysis suggests that the 0.20 value of pv-SC is significantly smaller than the 0.49 value of the control (p < 0.01). The results suggest that the pv-SC is less rigid of the structure than that of the control SC, indicating irregular architecture of pv-SC. Therefore, the present EPR results can be useful for analyses of various SC.