It is well known that changes in physical properties of hair fibers occur as a result of hair damage. Therefore various measurements have been performed for explication of that phenomenon. By component analysis, it has been found that loss of proteins and lipids from hair fibers after such chemical treatments as bleaching or permanent waving are related to physical property changes; however, it has not been possible to identify where hair damage occurs by component analysis alone. To overcome this problem, we have conducted analysis of the structure of damaged hair using X-ray techniques such as XANES and X-ray fluorescence mapping.

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It has been well known that the UV radiation in sunlight accelerates premature skin aging, and this feature of skin aging is commonly termed photo-aged skin. Cosmetic companies have recently recommended that consumers use sunscreens to prevent the risk of photo-aged skin. In general, sunscreen effects have been realized by formulating UV-scattering agents such as TiO₂ and ZnO, and organic UV-absorbing agents. Among sunscreen agents, octyl methoxycinnamate (OMC) and 4-tert-butyl-4'-methoxydibenzoylmethane (BMDBM) are widely used and are known to cause photo-degradation during UV irradiation. However, the photo-degradation of UV absorbers on topically treated skin during sun exposure leads to a decrease of their photo-protective capability, which results in sunburn formation and the acceleration of photo-aged skin formation. In order to reduce the photo-degradation of UV absorbers and to prevent skin damage, it is critical to understand the basic behavior of UV absorbers in a thin layer such as when topically applied on the skin. This study was conducted to find clues for solutions to preventing these phenomena. Among UV absorbers, BMDBM gave the highest degree of photo-degradation. Furthermore, the degree of photo-degradation of BMDBM showed a negative relationship with the polarities of oil solvents in the following systems: BMDBM simply solubilized in oil and W/O emulsions without silicone oil. In combinations of BMDBM formulated with different UVB absorbers, the pair of BMDBM and OMC showed an equivalent photo-degradation in UVB and UVA regions. However, the pairs of BMDBM and 2-hydroxy-4-methoxybenzophenone (HMBP) or ethylhexyl triazone (EHT) gave a higher photo-degradation in the region of UVA than of UVB. Photo-stabilizers such as octcrylene(OCR)and methoxyoctocrylene(MOCR)required more than the same concentration of UV absorber to prevent photo-degradation. These results suggest that the photo-degradation of BMDBM occurs partially through the formation of some radicals.

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Stratifin (SFN), a member of the 14-3-3 protein family, is expressed in epidermal keratinocytes. It was reported that SFN is induced in a p53-dependent manner after DNA damage, acts as an inhibitor of cell cycle progression and is involved in apoptosis induction. It was also reported that SFN is related to collagen metabolism through regulation of expression of collagen and matrix metalloproteinase in dermal fibroblasts. However, the roles of SFN in skin aging are not clearly understood. In this study, the association of SFN with the mechanism of intrinsic skin aging was investigated. SFN mRNA expression and protein levels increased significantly in keratinocytes treated with bromodeoxyuridine (BrdU), an inducer of a senescence-like phenomenon. SFN significantly decreased filaggrin and serine palmitoyltransferase mRNA expression in epidermal keratinocytes. SFN also decreased type I collagen and hyaluronan synthase 2 mRNA expression in dermal fibroblasts. The increase of SFN mRNA expression in BrdU-treated keratinocytes was suppressed by the addition of Love-in-a-mist extract. Therefore, an increase of SFN triggered by cellular senescence may be one of the causes of alterations observed in intrinsic aging skin. In addition, Love-in-a-mist extract suppressed cellular senescence-induced increase of SFN mRNA expression and is considered to be an effective anti-aging ingredient for skin.

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Because of the concern of many consumers, it is important to study make-up deterioration, which is a phenomenon in which foundation falls into wrinkles with time. Nevertheless, few studies on that deterioration have been carried out so far. Aiming for development of a base make-up preventing the deterioration, we investigated in the following three steps. In the first study, from a survey and visual observation of ladies'faces, we clarified the mechanism of the deterioration around the smile lines, which was caused by two factors,“coming-off”and“agglomeration”of the powders in the foundation after wetting with sebum and being moved into wrinkles by facial movements. In the second investigation, based on the above-mentioned mechanism, we reproduced the deterioration in vitro and developed a method of quantitative evaluation of“agglomeration”and“coming-off”of the powders in the foundation by using histogram analysis. In the third study, using this method, we evaluated various cosmetic raw materials and found a superior combination of elastic polymer and high molecular weight silicone. By using this combination, we formulated the make-up base. This make-up base was confirmed to be long-lasting around smile lines.

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