Hiroyuki Ohsu

Unusual wrinkle formation after temporary skin fixation followed by UVB irradiation in hairless mouse skin

Abstract Generally, many wrinkles form on the human face, and temporary wrinkles eventually become permanent. We evaluated the effects of temporary skin fixation on wrinkle formation after UVB irradiation using the back skin of hairless mice. In the group treated with UVB irradiation immediately after production using cyanoacrylate resin of an artificial groove parallel to the midline, wrinkles formed parallel to the midline, an uncommon direction for wrinkle formation in this mouse model. These wrinkles did not disappear even when the skin was stretched. No such changes were observed in the group in which only the temporary groove alone was produced without UVB irradiation. In 3‐D surface parameter analysis, all roughness parameters in the group treated with UVB irradiation immediately after production of an artificial groove were significantly increased relative to the age‐matched control group. In contrast, no differences were observed between the group in which only the temporary groove alone was produced without UVB irradiation and age‐matched controls. The results of this study suggest that both a temporary groove in the skin and UVB irradiation are necessary for wrinkle formation in the back skin of hairless mice.

Age-related discontinuous changes in the in vivo fluorescence of human facial skin

We measured the 325-nm laser-induced fluorescence of the skin of the face and ventral forearm in seventy Japanese female volunteers, and evaluated the effects of age and exposure to sunlight. The subjects were arbitrarily grouped into 10-year age-groups. In slightly exposed areas such as the ventral forearm, the average laser-induced intensity ratio at 390 nm to 430 nm showed no significant differences with the age group. In areas markedly exposed to sunlight such as the corners of the eyes and mouth, the average laser-induced intensity ratio showed a discontinuous decrease with age. These findings suggested that dermal fluorophore changes differ with the skin areas and are affected by sunlight exposure.