Natural skin surface pH is mildly acidic, but the relationship between skin surface pH and rough skin is not sufficiently elucidated. Recently, it has become clear that Na⁺/H⁺ exchanger 1 (NHE1) plays an important role in the acidification of skin surface. NHE1 exists on the cell membrane of keratinocytes and regulates intracellular pH by effectively extruding H⁺ ions from intracellular compartments in exchange for external sodium ions, which also controls the acidification of extracellular microdomains and, consequently, contributes to the skin surface pH. In this study, we investigated the relationship between NHE1 protein amount, skin surface pH, and the onset of rough skin on cheek skin of male subjects. The skin surface pH value was measured and the stratum corneum was tape-stripped twice at monthly intervals. NHE1 protein amount was measured by Western blotting, and the multilayer exfoliation state was observed with microscope and quantified. As a result, a negative correlation was found between the changes in NHE1 protein amount and skin surface pH value. Also, there were a positive relationship between the changes in skin surface pH value and multilayer exfoliation score and a negative relationship between the changes in NHE1 protein amount and multilayer exfoliation score. That is, the relation between NHE1 protein amount, skin surface pH, and the onset of rough skin was confirmed. On the basis of these results, NHE1 may be involved in skin surface pH control and the onset of rough skin, and the functional decline of NHE1 is considered to induce an increase in skin surface pH value and an onset of rough skin.

Although many previous studies have focused on the association between beauty and happiness, there have been few studies on the association between variation in the evaluation of beauty and happiness. The purpose of this study was to examine the association between variation in the evaluation of beauty and happiness in Japan, England and China. We used data from a cross-sectional survey of 1,500 women of between 20 and 69 years of age, which was collected online in Japan, England and China. We performed logistic regression to calculate the odds ratios and 95% confidence intervals for happiness. We found that after controlling for the socio-economic status, the odds ratios (95% confidence intervals) for happiness in individuals with a physically beautiful appearance (in comparison to non-beautiful individuals) at both the present time and 15 years previously were 4.70 (1.72–12.82), 4.38 (2.23–8.60), 10.60 (4.67–24.06) in Japan, England and China, respectively. The results indicated that higher subjective beauty was intertemporally associated with higher happiness in Japan, England and China. Further studies should be performed to investigate the association between the intertemporal evaluation of beauty and happiness.

Hair follicle is one of skin appentages and contains hair bulge where stem cells for maintenance of epidermis, hair follicle and sebaceous gland. Terminal hair consists of hair cortex, medulla and cuticle. Hair follicle has hair cycle, repeating tissue regeneration and regression. There are three phases such as anagen, catagen and telogen. In androgenetic alopecia (AGA), anagen is shortened, resulting in miniaturization of hair follicle. Then, hair shaft diameter is also smaller. As a new AGA drug, dutasteride is interesting because there are some cases showing better effect by dutasteride than finasterid.

The market scale of hair growth stimulants including medicines and quasi-drugs in Japan was 67.5 billion yen at 2016. It is expected that the market of hair growth stimulant for women will be bigger in future. Therefore, the market needs to develop new hair growth stimulants. Nowadays, it is difficult to develop novel medicines or novel quasi-drugs for hair growth, because the wave of animal experiment abolition is getting bigger in the world-wide cosmetics industry. Under such circumstances, despite authorities approving over 30 active quasi-drugs in the field of hair tonic products, most of these drugs are not fully utilized. It will be important that we reevaluate these approved active ingredients. And, the importance of digging out the approved quasi-drugs is expected to increase in the future. In this lecture, I would like to describe a reassessment of approved active quasi-drugs for hair growth and its evaluation methods.

Many Japanese individuals develop gray hair with age, and thus hair dye products are useful for aesthetics and everyday life. However, there has been an increase in the number of cases of contact dermatitis following the use of hair dye. Allergic contact dermatitis has been observed in many patients and some cases develop contact urticaria as an immediate hypersensitivity reaction to hair dye. It is therefore important for individuals to perform an initial strand and allergy test before using a product, and to visit a medical institution immediately if skin symptoms are seen following the use of hair dye. In my presentation, I described the actual symptoms of skin disorders induced by using hair care products, the allergens related to hair dye use, and the efforts of administrative bodies such as the Japan Hair Color Industry Association and the Skin Safety Case Information Network (SSCI-Net) website.

Cosmetics that are used daily to keep our skin healthy and to make it look attractive, are available in many types where ingredients comprising them vary depending on the formulation in which they are contained. The infant stage of modern Japanese cosmetic history just after the Meiji Restoration (1868) saw many novel products appearing on the market one after another due to demands and changes in consumer perceptions, new findings in dermatology and the birth of new ingredients and development of formulation technologies, where up until then, only limited items e.g., facial cleansers and skin lotions for skincare and face powders, rouge and eyebrow pencils for makeup were commercially available. The myriad of cosmetic formulations available today are the fruits of the technology development history to meet consumer demands. With the recent advent of consumers demanding both efficacy and safety concurrently, cosmetic research and development too has entered a new era, and changes are envisaged in marketing strategies as well. Hence, to safely make full use of the products that flood the market today, their proper usage should be understood and executed correctly. This article will attempt to outline the types and usage of skincare cosmetic products that flourish the market through tracing the history of cosmetic technologies and marketing strategies.