This study was conducted to clarify whether 8-anilinonaphthalene-1-sulfonic acid (8,1-ANS), a fluorescent probe that is used to measure hydrophobic changes of the microenvironment formed by proteins, can be used to measure the degree of hydrophobicity of corneocytes. Firstly, the fluorescence intensity of 8,1-ANS in keratin films in which COOH groups were chemically modified with hexylamine or with Alexa Fluor 594 cadaverine to increase hydrophobicity was examined. Increase of hydrophobicity in these chemically modified keratin films was indicated by measuring a contact angle of deionized H₂O. The fluorescence intensity of keratin films originating from 8,1-ANS showed increases that corresponded to the decreased fluorescence intensity of Alexa Fluor 594 cadaverine, which was used to label COOH groups that remained after the covalent bonding of hexylamine. Furthermore, keratin films with COOH groups that were fluorescence-labelled with Alexa Fluor 594 cadaverine also showed increased fluorescence intensity of 8,1-ANS. These results showed that 8,1-ANS changed its fluorescence intensity in response to the hydrophobic modification of keratin films, which indicated the applicability of 8,1-ANS to measure the hydrophobicity of corneocytes. The fluorescence intensity originating from 8,1-ANS labeling of corneocytes, which were chemically modified to increase their hydrophobicity, was then examined. The fluorescence intensity of corneocytes that originated from 8,1-ANS showed changes corresponding to the hydrophobic modifications. These results demonstrated that 8,1-ANS is a useful fluorescent probe to measure the hydrophobicity of corneocytes.

Evaluation of the razor performances is usually carried out by sensory evaluation and blade cutting load measurement, but there are few studies that measure skin damages quantitively. Some previous studies tried to measure it with transepidermal water loss (TEWL) measurement and reported that razor shaving lowered skin barrier function. However, they did not describe precise conditions of the shaving and TEWL measurement, nor the mechanism of increasing TEWL value.

In this study, to evaluate the effects of razor shaving on the skin, we conducted two experiments using excised porcine ear skin. One was measurement of temporal changes in TEWL and stratum corneum (SC) water content before and after the shaving. The other was estimation of removed SC depth by shaving using combination of the fluorescent staining and tape stripping methods.

We confirmed that TEWL and SC water content were slightly increased by the shaving though the increase was far less than that induced by repetitive tape strippings. Evaluation of the gradient of fluorescent-stained SC revealed that the removed SC depth by the shaving was almost the same as that of the first tape stripping. These results indicated that shaving caused damage to skin but it was probably very slight.

Biomedical science to date has created domain knowledge through typification using natural language, hypotheses based on causal models, and hypothesis testing using statistics. However, domain knowledge cannot be used to realize personalized medicine or preventive medicine based on life course data. This is because the life system is a nonlinear open system. To overcome this problem, we have developed discriminators and predictors using machine learning. Furthermore, to improve the reproducibility of machine learning predictions, we have developed a method to link the identification of targets by machine learning and domain knowledge systematized as a network structure through the concept of states. In addition to probabilistic predictive inference with reference to prior events, we are also investigating the integration of thermodynamics and information science to develop deductive inference based on the second law of thermodynamics.

Surfactants have been contributing to the development of a clean and comfortable life as a main component of cosmetics and detergents. However, economic development would affect the balance of supply and demand for surfactants in the future. The current ways of using surfactants could cause a short supply in the future. In order for all consumers to sustain a comfortable life, surfactants are required to (1) be derived from extra vegetable oils (for the earth), (2) be highly surface active to maintain the product qualities (for consumers), and (3) be extremely water-soluble (for global use). Surfactant suppliers have the responsibility to develop technologies that can satisfy these requirements at the same time. Bio-based internal olefin sulfonate salt (Bio IOS), which was recently developed, is produced from C16 and C18 vegetable fats, which have been generally considered unsuitable as raw materials for surfactants. Moreover, it can satisfy the above (2) and (3) requirements, which are generally considered not to be compatible with each other. Thus, Bio IOS should be expected to be a novel trigger for the development of more sustainable surfactants.

This paper introduced the psychological approach researches on odor perception. Odor perception occurs when odorants present in the environment are received in the nasal cavity. Although we are not yet aware of it, it is unknown how the lack of stimulation of the olfactory system affects us. The author discussed some findings on characteristics of odor perception. One of these was the effect of scents on the evaluation of impressions of people, and the other was the lack of consistency of in odor perception.

The lack of consistency in odor perception was indicated by low task performance in the repeated odor exposure task and low correlations between similarity ratings evaluation of two odor pairs. The possibility that verbalization of odor stimuli may bring stability to odor perception was also noted.

After melanosis faciei femina, two outbreaks of severe side effects caused by cosmetics have occurred since 2009. One is an immediate wheat allergy percutaneously sensitized to hydrolyzed wheat protein contained in facial soaps (HWP-IWA) that included 0.3% of a specific type of HWP, Glupearl 19S. A total of 2,111 cases developed allergic contact urticaria, anaphylaxis, and/or wheat-dependent exercise-induced anaphylaxis (WDEIA) after using the soaps.

The other one is Rhododenol-induced leukoderma (RDL) due to a skin-whitening agent rhododendrol (Rhododenol) (RD) approved by the Ministry of Health, Labour and Welfare as a quasi-drug. A total of 19,609 individuals developed leukoderma, that is about 2.4% of those who used whitening cosmetics (cosmetics) containing 2% RD.

The author served as chairpersons of the special committee of the Japanese Society of Allergology for HWP-IWA, and of the Japanese Dermatological Association for RDL. Both committees carried out epidemiological studies, established diagnostic criteria and provided practical guidance to treat and care the patients. Both committees performed and reviewed clinical, basic, and genetic research on the pathomechanism, and provided information to the medical doctors and the patients.

In this article, HWP-IWA and RDL are reviewed from a viewpoint of a dermatologist and the chairpersons of the special committees.

Adverse effects to cosmetics are multifactorial; of these, contact dermatitis is the most common, and shows eczematous reactions such as papules, erythema, and vesicles at contact sites with the causative agent. Contact dermatitis is classified into three types: irritant contact dermatitis, allergic contact dermatitis, and photocontact dermatitis. All are initiated by the penetration of a chemical. Its epicutaneous stimulus make keratinocytes secrete cytokines, and inflammation depending on the innate immune system. Allergic contact dermatitis is a delayed-type hypersensitivity reaction mainly involving T cells and antigen-presenting dendric cells. Recent studies demonstrated that the innate immune system plays an important role for its sensitization and expression of eczema phases. Photocontact dermatitis is produced from the combination of a skin contact with a compound together with ultraviolet light. Contact urticaria patients develop localized wheal immediately after direct contact with a causative substance. It is divided into three types: immunological, non-immunological, and one with unclear mechanism. Immunological contact urticaria is a type I sensitivity immunological reaction, and this type can produce anaphylactoid reactions. The mechanism of leukoderma due to rhododendrol is thought caused by the metabolite that is a product of rhododenol bound to tyrosinase. The metabolite produces reactive oxygen species and depletes the intracellular antioxidant glutathione, which to be responsible for melanocytes death. Cosmetics occasionally lead to exacerbation of skin diseases: e.g., atopic dermatitis and acne vulgaris. In such cases, most are produced by inadequate choice of cosmetics, respectively.

Cosmetics can cause allergic contact dermatitis, irritant contact dermatitis, contact urticaria, depigmentation, and other skin disorders. The skin testing methods for allergic contact dermatitis and allergic contact urticaria are described in this paper. A 48-h closed patch test, open test, or repeated open application test (ROAT) is used to diagnose allergic contact dermatitis, which is a delayed allergy. A photopatch test is required to test photoallergic contact dermatitis. Rinse-off cosmetic products should be diluted with 1% aqueous solution and applied for 48-h closed patch test, while powder products should be mixed with approximately 30% petrolatum and applied. Hair coloring agents and permanent wave agents with irritant properties should not be subjected to closed patch test but instead undergo an open test. It is also useful to perform a ROAT to diagnose allergic contact dermatitis. On the other hand, a prick test should be performed to diagnose contact urticaria, which is an immediate allergy.