Structural analysis of the cell membrane complex in the human hair cuticle using microbeam X-ray diffraction: relationship with the effects of hair dyeing.

This article deals with the structure of the cell membrane complex (CMC) in the human hair cuticle. The microbeam X-ray provided a pattern of small-angle scattering from the CMC in the cuticle with no sample preparations, including slicing and pre-staining of hair. The thickness of the beta- and delta-layers, substructure in CMC, was estimated by analysis of the scattering pattern. We used hair samples extracted with several solvents, and found that solvent extraction changed the thickness of the beta- and delta-layers in a manner dependent on the type of solvent. Extraction of hair with solvent was also shown to have effects on the extent of dyeing. There was a high correlation between the extent of dyeing and the thickness of the delta-layer, i.e., a thin layer tended to show a high amount of dyeing, whereas there was no significant correlation between the thickness of the beta-layer and the extent of dyeing.

Dissimilar effect of perming and bleaching treatments on cuticles: advanced hair damage model based on elution and oxidation of S100A3 protein.

Hair treatment chemicals induce sudden and severe hair damage. In this study, we examined cuticles from untreated, permed, and bleached hair that were mechanically discriminated by shaking in water. Both perming and bleaching treatments are prone to easily delaminate cuticles. Confocal microscopy revealed that the cuticles of permed hair were delaminated with larger pieces than untreated ones. On the other hand, the cuticles of bleached hair tend to fragment into small peptides. At the minimum concentration of thioglycolate required to elute S100A3 protein from the endocuticle into the reductive permanent waving lotion, enlarged delaminated cuticle fragments were observed. Although S100A3 is retained in bleached hair, S100A3 is irreversibly oxidized upon bleaching treatment. It is likely that the oxidative cleavage of disulfide bonds between cuticle-constituting proteins, including S100A3, results in the fragile property of cuticles. Here we present a more comprehensive model of hair damage based on a diverse mechanism of cuticle delamination.

Practical use of labile protein as an index of hair.

Because of small fluctuations, it is difficult to evaluate hair damage caused by bleaching using previously utilized hair damage indexes. Application of commercial bleaching products elevates partially extractable labile hair protein amounts in the range of 0.4-1.2 mg/g of hair. Within this range, the level of labile protein fluctuates greatly, depending on the extent of bleaching. In the current study, it was found that the effects of alkaline constituents and various peptides contained in bleaching lotions on hair damage could be evaluated by measuring labile protein amounts without employing harsher bleaching conditions.