EFFECT OF PERMING/BLEACHING ON CUTICLES 223 a b 14 C 8 Perm )IOI( )IOI( Bleach 12 10 ,,...., * * ........ i i -d" 8 -d" � � 4 ( 6 ( 4 2 2 0 0 0.3 1 3 0 0 1 3 10 Thio&lyct-olate (%) �� (%) Figure 2. Effects of perming and bleaching on the size of delaminated cuticles. (a) Confocal microscopy of cuticles delaminated from permed and bleached hair. Cuticle suspensions were prepared from hair samples treated with various concentrations of thioglycolate and hydrogen peroxide (bottom row). Note the size of delaminated cuticles from permed (b) and bleached hair (c). The area of cuticle fragments was computed by gradational analysis of each confocal image. Values represent the average of three independent experiments ± SD. Statistical analyses were performed by t-test of the values obtained without hair treatment chemicals. * p 0.05 ** p 0.01. precise identification of each isoelectric variant of S 1 00A3 required further investiga­ tion, observed acidic shifts of the protein spots suggested that several cysteine residues in the S 100A3 protein were converted into cysteic acid by oxidation with hydrogen peroxide. Our 2D PAGE analyses showed that S100A3 with a higher content of cysteic acid occupied a higher proportion in bleached hair treated with a higher concentration of hydrogen peroxide (Figure 4). DISCUSSION Various techniques, such as morphological observation of hair fiber using scanning electron microscopy and tensile measurement, have been employed to monitor hair damage. However, the critical differences between the perm and bleach inductive dam­ aging mechanism(s) have never been studied. In this study, we report that the manner

224 JOURNAL OF COSMETIC SCIENCE 300 6 � ........... li... cu 250 5 . (\J .c b.D b.D -4 ' 200 b.D '-"' C · 150 3 +-' a 0 a i- a.. ,-- 100 -2 en "'C "'O 50 1 w 0 0 0 0.3 1 3 Thioglycholate (%) Figure 3. Total protein and S 1 00A3 eluted from hair into permanent waving lotion. Total protein (gray box) and S100A3 (black box) levels were determined by Bradford assay and Western blot analysis, respec­ tively. n.d., not detected. of cuticle delamination processes largely depends on the experienced perming and bleaching treatments. Our results indicate that cuticles delaminated from permed hair are remarkably larger than those from untreated hair. Those from harshly bleached hair can, however, be smaller. Based on these findings, we present now a more precise model for chemically induced hair damage, which encompasses both SlO0A3 elution and oxidization during various hair treatment procedures (Figure 5). We detected a close correlation between the concentration of S 1 00A3 in the permanent waving lotion and the enlargement of the delaminated cuticles. We propose that re­ ducing permanent waving lotion releases S 1 00A3 from the inner part of the endocuticle (5) so that the cuticle becomes more easily delaminated. This study shows that the cuticles of permed hair tend to delaminate into large fragments. Interestingly, the loss of a low amount of S 1 00A3 already damages the adhesion sites between the cuticles, and is sufficient to enlarge the cuticle fragments. This reinforces our postulation that SlO0A3 is a structural component linking adjacent cuticles. Our previous hair damage model could not explain why in bleaching treatments induced hair damage occurs without loss of Sl00A3. Recent observation by transmission electron microscopy showed severe damage in the endocuticle upon bleaching treatment (11). This study has shown that several SlO0A3 spots were observed on 2D-PAGE without any chemical treatment, but the oxidized forms, shifted to acidic pl, increased dramati­ cally by employing hydrogen peroxide. The acidic pl shift of Sl00A3 is observed within