Age-dependent damage of hair cuticle: contribution of S100A3 protein and its citrullination.

BACKGROUND: There are two types of damage pattern of human hair cuticle: type L, where the cell membrane complex is split and the cuticle lifts up, and type E, where the fragile substructure of the cuticle cell (endocuticle) is broken. In our previous paper, it was reported that the dominant damage pattern shifts from type L to E with the subjects' age around the 40s. Loss of the cuticle due to daily grooming stresses increases with the subjects' age and is related to the level of type E damage. It is supposed that deterioration of endocuticle advances the loss of cuticle. S100A3 protein, located at the endocuticle, was found to be citrullinated and transformed into tetramer to improve its Ca(2+) -binding ability. It is postulated that this biochemical property affects the maturation of cuticle and contributes to its reinforcement. AIMS: This study aims to elucidate the role that S100A3 plays in age-dependent cuticle damage. METHODS: Hair fibers collected from Japanese females were evaluated for the content and citrullination rate of S100A3, incidence of type E damage, and resistance of cuticle. RESULTS: In the aged hair, the content of S100A3 was positively correlated with the level of type E damage and low resistance to stress. Hair fibers in which S100A3 is highly citrullinated, however, showed low levels of type E damage and high resistance of cuticle, even in the aged hair as well as at younger ages. CONCLUSIONS: S100A3 and its citrullination process are related to rigidity of endocuticle of aged hair.

Age-dependent changes in damage processes of hair cuticle.

BACKGROUND: Human hair cuticle is always exposed to various stresses and then gradually lost in daily life. There are two typical patterns of cuticle damage: type L, where the cell membrane complex, the structure located between cuticle cells, is split and the cuticle lifts up, and type E, where the fragile substructure of the cuticle cell (endocuticle) is damaged so that its rugged residue is exposed. We previously reported that type L damage preferentially occurs in the case of Japanese females in their 20s to 40s. AIMS: This study aims to elucidate the age-dependent change of cuticle and its effect on hair properties. METHODS: Hair fibers collected from Japanese females (ranging from 10 to 70 years old) were evaluated in the aspects of inclination for each type of damage, resistance of cuticle against grooming stresses and content of fatty acid 18-MEA on hair surface. RESULTS: It was revealed that the dominant damage pattern shifts from type L to E with aging. Furthermore, the cuticle becomes gradually less resistant to daily grooming stress. The dominance of type E damage accelerates cuticle loss. Reduction of 18-MEA on weathered hair is accelerated with aging on elder hair. CONCLUSIONS: It has been reported that various age-dependent changes of whole hair shaft, such as diameter, density, elasticity, etc., occur in the age range of 40s and 50s. In this study, it was revealed that cuticle becomes more fragile and the hair surface properties deteriorate in the same age range.

Changes in structure and geometric properties of human hair by aging.

To clarify hair changes by aging, the effect of age on hair properties was investigated from macro- to microscopic view points. Sensory hair luster tests were performed on 230 Japanese females from 10 to 70 years of age, revealing that hair luster decreases with age. The age dependence of the hair diameter and the ellipticity of the hair cross section could not explain luster reduction by aging. It has been determined that an irregular increase in fiber curvature occurs with age and is a cause of luster reduction with aging. A detailed structural analysis by synchrotron radiation microbeam X-ray diffraction revealed that the inhomogeneity in the lateral distribution of the hair microstructure increased with age and relates to the irregular increase in curvature. Such an increase in curvature is one of the important factors that leads to a poor alignment of hairs and luster reduction, and is related to the appearance of aging hair.

Changes in hair properties by Eucalyptus extract.

A long-term usage investigation of a scalp lotion containing Eucalyptus extract, which increases the amount of ceramide in the skin, was carried out to explore the change in physical properties of the hair fiber. Half-head or whole-head usage studies of a scalp lotion with Eucalyptus extract were carried out for the following groups: Japanese female, Japanese senior female, Japanese male, and Caucasian female panelists. As a result, the improvement in hair luster and bounce in the root part of the hair were recognized by the panelists after the long-term application of the scalp lotion with Eucalyptus extract. Measurement of hair gloss intensity and bending stress at the root suggests that this improvement is based on changes in these physical properties. These results indicate that the recognition of panelists is based on an actual change in the hair fiber properties. The efficacy of Eucalyptus extract is expressed regardless of race, age, or gender, since similar results were confirmed in all panelist groups. In order to investigate the cause of these phenomena, we measured the elasticity (Young's modulus) of the new-growth part of the cortex in Eucalyptus extract-treated hair and placebo hair by the nano-indentation method of atomic force microscopy (AFM). These results suggest that the Young's modulus of the new-growth part of the cortex in Eucalyptus extract treated-hair increases in comparison with placebo hair. The IR spectra of treated samples of hair show changes that appear to confirm a decrease in the alpha-helix structure and an increase in the beta-sheet structure.

A study of the volume and bounce decrease in hair with aging using bending elasticity measurements.

Hair diameters and bending stresses were measured for chemically untreated regions of hair close to the scalp, collected from 38 Japanese female (age range: 26 to 51) and 35 Caucasian female (age range: 20 to 40) volunteers. For the bending stress measurements, a new methodology to obtain averaged Young's modulus has been developed in which 50 fibers are measured together to give reproducible data, overcoming the individual differences in each hair fiber. By comparing the resulting data of the fibers collected from the panelists younger than 40 years of age, no significant difference in Young's modulus between Japanese and Caucasian hair was recognized, and the modulus was ca. 10 GPa, regardless of the hair diameter. On the other hand, there existed cases in which fibers showed lower Young's moduli, and these fibers were from senior panelists who were conscious of the decrease in hair volume and bounce with aging. This result indicates that the decrease in volume and bounce in hair with aging is not only caused by a decrease in hair diameter and fewer hairs per square centimeter of scalp but also by some internal change in the hair.

Characterization of hair lipid images by argon sputter etching-scanning electron microscopy.

Hair lipid images, as visualized by argon sputter etching-scanning electron microscopy (ASE-SEM), reveal convex structures with a stitch pattern (SP) at the cell membrane complex (CMC) in the transverse hair plane. Based on interindividual variation, different features of the convex SP were classified into Types 0 to 4 with the corresponding scores 0 to 4. Observations using hair fibers collected from 27 Japanese females revealed significant positive correlations between the scores and the levels of exogenous lipids, which suggests that exogenous lipids internalized at the CMC predominantly constitute the convex SP. Intraindividual variation with different levels of exogenous lipids among hair fibers derived from individual females may be relevant to the uneven physicochemical properties of hair fibers on the scalp. Observations of 380 hair fibers collected from Japanese (Mongoloid), German and American (Caucasoid) females aged 3 to 77 yr demonstrated similar age-related changes in the lipid images, which represent an increase and then a decrease in levels of exogenous lipids with increasing age. This suggests that age-related changes in exogenous lipids are attributable to alterations in sebum excreted during aging and that this elicits age-related changes in physical parameters, which affect human hair texture.

Structural analysis of human hair fibers under the ultra-high voltage electron microscope.

Three-dimensional structural analyses of human hair fibers and comparison of the different fibers were tried by using the Ultra-high Voltage Electron Microscope (UHVEM). The analysis condition, sample preparation, and a machine state were adjusted to the suitable condition for tilting observation of from -70 degree to +70 degree, at 2 degrees intervals. The tomography of hair fiber was successfully reconstructed from the different angle pictures with IMODE software in a computer. By using UHVEM, the various human hair fibers from Japanese and Caucasians were investigated and discussed about their structures.

Influence of internal structures of hair fiber on hair appearance. III. Generation of light-scattering factors in hair cuticles and the influence on hair shine.

The effects of thermal treatments on hair fiber induced by blow-drying have been investigated. It was found that the hair shows whitish and powdery appearance after heat drying, especially when dark hair is rapidly dried from a wet condition. For all kinds of hair, the appearance of numerous glittering speckles was confirmed on the cuticle surface by optical microscopic observations. SEM images of hair transverse and longitudinal sections with glittering speckles revealed that the splitting of cuticle layers generated by blow-drying occurred not only at the outermost parts of cuticle cells but also at the inner parts of the cellular interfaces. The release and uptake of moisture through fiber surfaces induces deformation of cuticle cells, probably because of anisotropic swelling or drying of the cells. The cuticles with glittering speckles are found to be fragile and are easily damaged in combination with other mechanical stresses such as combing force. Furthermore, the authors have found an efficient system for both improving hair shine and preventing cuticle damage caused by the blow-drying/combing process.