How emotional changes affect skin odor and its impact on others.

The gas emanating from human skin is known to vary depending on one's physical condition and diet. Thus, skin gas has been gaining substantial scholarly attention as an effective noninvasive biomarker for understanding different physical conditions. This study focuses on the relationship between psychological stress and skin gas, which has remained unclear to date. It has been deduced that when participants were subjected to interviews confirmed as stressful by physiological indicators, their skin emitted an odor similar to stir-fried leeks containing allyl mercaptan and dimethyl trisulfide. This characteristic, recognizable odor appeared reproducibly during the stress-inducing situations. Furthermore, the study deduced that individuals who perceive this stress odor experience subjective tension, confusion, and fatigue (Profile of Mood States scale). Thus, the study findings indicate the possibility of human nonverbal communication through odor, which could enhance our understanding of human interaction.

1-(2-Hydroxyethyl)-2-imidazolidinone, a heparanase and matrix metalloproteinase inhibitor, improves epidermal basement membrane structure and epidermal barrier function.

Daily exposure to sunlight is known to affect the structure and function of the epidermal basement membrane (BM), as well as epidermal differentiation and epidermal barrier function. The aim of this study is to clarify whether the inhibition of BM-degrading enzymes such as heparanase and matrix metalloproteinase 9 (MMP-9) can improve the epidermal barrier function of facial skin, which is exposed to the sun on a daily basis. 1-(2-hydroxyethyl)-2-imidazolidinone (HEI) was synthesized as an inhibitor of both heparanase and MMP-9. HEI inhibited not only the BM damage at the DEJ but also epidermal proliferation, differentiation, water contents and transepidermal water loss abnormalities resulting from ultraviolet B (UVB). This was determined in this study by the use of UVB-induced human cultured skins as compared with the control without HEI. Moreover, topical application of HEI improved epidermal barrier function by increasing water content and decreasing transepidermal water loss in daily sun-exposed facial skin as compared with non-treated skins. These results suggest that the inhibition of both heparanase and MMP-9 is an effective way to care for regularly sun-exposed facial skin by protecting the BM from damage.

Stratum corneum drying drives vertical compression and lipid organization and improves barrier function in vitro.

The stratum corneum dehydrates after exogenous hydration due to skincare or bathing. In this study, sheets of stratum corneum were isolated from reconstructed human epidermis and the barrier function and structure of these sheets were assessed during drying with the aim of improving our understanding of skincare. Water diffusion through the sheets of stratum corneum decreased with drying, accompanied by decreased thickness and increased visible light transmission through the sheets. Electron paramagnetic resonance revealed that the order parameter values of stratum corneum lipids increased with drying. X-ray diffraction analysis revealed increases in the diffraction intensity of lamellar structures, with an 11-12 nm periodicity and spacing of 0.42 nm for lattice structures with drying. These results suggest that the drying process improves the barrier function of the stratum corneum by organizing the intercellular lipids in a vertically compressed arrangement.

Comparison of sagging at the cheek and lower eyelid between male and female faces.

BACKGROUND: Facial sagging is a well-known morphological feature associated with aging and reduced dermal elasticity. Its morphological characteristics and mechanism have been studied in females, but it is unclear whether or not there is a gender difference. AIMS: The aim of this study was to clarify the morphological characteristics of sagging and the mechanism of sagging formation in male faces as compared with female faces, focusing on changes in dermal elasticity. METHODS: Faces of 98 healthy Japanese male volunteers, in their 20s-60s, were photographed at an angle of 45°. Upper and lower cheek sagging severity was evaluated by using photograph-based grading criteria. In addition, new photograph-based grading criteria of sagging severity at the lower eyelid were established and used. Dermal elasticity was measured using a non-invasive, in vivo suction skin elasticity meter, Cutometer(®). Furthermore, photographs of 108 healthy Japanese female volunteers in their 20s-60s were used to compare the difference in the morphological characteristics of sagging between males and females. RESULTS: Male facial sagging was prominent at the lower eyelid, upper cheek and lower cheek. Sagging severity in the upper and lower cheek was almost the same between males and females at all ages, whereas sagging at the lower eyelid in males was significantly more severe than that in females after middle age. Although dermal extensibility (U(f)) was not related to age, total deformation recovery (U(a)), -(amount of deformation) -(U(f)-U(a)), overall elasticity of the skin including creep and creep recovery (U(a)/U(f)), net elasticity excluding viscoelastic creep (U(r)/U(e)), ratio of elastic recovery to total deformation (U(r)/U(f)) and -(ratio of viscoelastic to elastic distention) -(U(v)/U(e)) were all significantly negatively related to age in both men and women. Furthermore, as in female faces, male facial sagging was significantly negatively related to dermal elasticity parameters, such as -(U(f)-U(a)), U(a)/U(f), U(r)/U(e) and U(r)/U(f). CONCLUSION: These results indicate that the morphology and areas of sagging in male faces are similar to those in females in the cheek, but sagging at the lower eyelid is more severe in males after middle age. Furthermore, the dermal elasticity of male facial skin decreased with age similar to that of females, and may therefore be associated with the sagging formation in male faces.

Functional characteristics of the skin surface of children approaching puberty: age and seasonal influences.

The aim of this study was to determine differences in the functional properties of the stratum corneum of children and adults, focusing on the influence of approaching puberty. Biophysical measurements were made of the stratum corneum of 32 healthy Japanese children aged 10-14 years and their mothers in summer and the following winter. The children showed significantly lower skin surface hydration. Stratum corneum barrier function, evaluated in terms of trans-epidermal water loss, was poorer on the forearm in the children than in the adults regardless of season. By contrast, the stratum corneum barrier of the cheek, which was better in the children, tended to become poorer when the children reached puberty. Although the immaturity of the cornified envelopes of the superficial corneocytes, which ratio increased significantly in winter, was not different from that of adults, the corneocytes were significantly smaller in the children, suggesting a more rapid turnover of the stratum corneum. The amount of skin surface lipid, which was measured only on the cheek, remained low until 13 years of age, but at 14 years of age it increased remarkably, approaching adult levels. We conclude that, until puberty, most functional characteristics of the skin of children remain distinct from those of adults.

Combined effects of ethanol and L-menthol on hairless rat stratum corneum investigated by synchrotron X-ray diffraction.

Synchrotron X-ray diffraction was employed to evaluate the effect of ethanol and l-menthol on lipid arrangements in the stratum corneum of hairless rats. Two sharp diffractions (S=2.40 and S=2.67, corresponding to spacing of 0.417 nm and 0.374 nm respectively) were observed on the broad hump peak derived from soft keratin. To assist in understanding the effects of treatment with ethanol and l-menthol, an abundance ration of lipid hydrocarbon chain packing index (R(H/O)) was defined as R(H/O)=(Peak area at S=2.40 nm(-1))/(Peak area at S=2.67 nm(-1)). When ethanol was applied to the stratum corneum the intensities of diffraction peaks declined slightly. The R(H/O) values observed were not affected by variations in ethanol concentrations in the range 0-40% (w/w). The R(H/O) values did not change even when treatment with ethanol (40%, w/w) was extended to 8 h. These results suggested that lipid arrangements in the stratum corneum were not affected by ethanol. On the other hand, exposure of the stratum corneum to 2% (w/w) L-menthol caused a significant decrease in R(H/O) value. It was shown that L-menthol was dispersed through the stratum corneum, intruded mainly into hexagonal hydrocarbon chain packing, and disrupted the regular organization of these structures.

Intense pulsed light therapy for superficial pigmented lesions evaluated by reflectance-mode confocal microscopy and optical coherence tomography.

Intense pulsed light (IPL) therapy is reported to be effective for pigment removal from pigmented lesions. However, the dynamic mechanism of pigment removal by IPL therapy is not completely understood. We investigated the mechanism of IPL therapy for the removal of pigmented skin lesions through non-invasive observation of the epidermis. Subjects with solar lentigines on the face were treated with three sessions of IPL therapy. The solar lentigines were observed on consecutive days after the treatments using reflectance-mode confocal microscopy (RCM) and optical coherence tomography (OCT). In addition, desquamated microcrusts that formed after the treatment were investigated by transmission electron microscopy (TEM). The images of RCM and OCT showed that the melanosomes in the epidermal basal layer rapidly migrated to the skin surface. The TEM images of the extruded microcrusts revealed numerous melanosomes together with cell debris. It was also found that the IPL irradiated melanocytes in the lesions seemed to be left intact and resumed their high activity after treatment. We conclude that IPL therapy effectively removed the dense melanosomes in the epidermal-basal layer. However, additional application of suppressive drugs such as hydroquinone or Q-switched laser irradiation is necessary to suppress the remaining active melanocytes.