Kazue Tsukahara

Inhibition of ultraviolet‐B‐induced wrinkle formation by an elastase‐inhibiting herbal extract: implication for the mechanism underlying elastase‐associated wrinkles

Background  Previously, we have demonstrated that fibroblast‐derived elastase plays an essential role in the increased three‐dimensional tortuosity of elastic fibers, contributing to the loss of skin elasticity in UV‐B‐exposed skin. This decrease in skin elasticity is closely associated with the formation of wrinkles induced by UV exposure.

Dermal fluid translocation is an important determinant of the diurnal variation in human skin thickness.

Background Ultrasonography has been used as a non‐invasive approach to measure skin thickness. To date there have been no studies on diurnal variations in skin thickness.

Ovariectomy is sufficient to accelerate spontaneous skin ageing and to stimulate ultraviolet irradiation‐induced photoageing of murine skin

Summary Background  Wrinkling and sagging of the skin during photoageing is physiologically associated with diminished elasticity, which can be attributed to increased fibroblast‐derived elastase activity. This degrades the dermal elastic fibres needed to maintain the three‐dimensional structure of the skin. We previously reported that ovariectomy accelerates ultraviolet (UV)B‐induced wrinkle formation in rat hind limb skin by altering the three‐dimensional structure of elastic fibres.

Age‐related changes in the three‐dimensional morphological structure of human facial skin

The human face shows morphological changes with age. Although these changes are generally recognized as wrinkle formation, there have been no quantitative studies of three‐dimensional morphological changes with age in each area of the face. The object of the present study, therefore, was to evaluate age‐related three‐dimensional morphological changes in each area of the face.

Age-Related Alterations of Echogenicity in Japanese Skin

Background: Ultrasonic methods are commonly used for the noninvasive measurement of skin thickness. The effects of ageing on the skin have been reported to differ between Asians and Caucasians. Therefore, it is possible that the echogenicity of the skin on ultrasonographic images reflects differences in the skin architecture and properties that may vary among races and environments. Objective and Methods: Since there have been a few reports on ageing-related changes in ultrasonic echogenicity in Caucasian skin, but not in Asian skin, we evaluated age-related changes in the echogenicity of ultrasonographic images by the ultrasonic B mode at 3 sites on the face (forehead, eye corners, cheeks) considered as sun-exposed areas and on the ventral forearms considered as weakly sun-exposed areas in 130 Japanese females aged from 18 to 83 years. The dermis was divided into 3 layers (upper, middle, lower), and echogenicity was evaluated in each area. Results: No age-related change in echogenicity was observed in the entire dermis. When the dermis was divided into 3 layers (upper, middle and lower dermis), the echogenicity was decreased in the upper layer and increased in the lower layer with age in all skin areas tested. In contrast, there were no age-related changes of echogenicity in the middle dermis. Conclusion: These findings suggest that, as for Caucasians, echogenicity in the upper and lower dermis is a useful tool for evaluating skin ageing in the Japanese.

Ovariectomy Accelerates Photoaging of Rat Skin

We have previously reported the formation of wrinkles, a decrease in skin elasticity and a loss in the linearity of dermal elastic fibers in rat hind limb skin irradiated with ultraviolet radiation in wavelength ranging 290–320 nm (UVB) at a suberythemal dose for 6 weeks. Estrogens are considered effective in preventing photoaging in postmenopausal females, but the role of estrogen in the skin remains unclear. In this study we have evaluated the influence of short‐term chronic UVB irradiation at a suberythemal dose on the skin of ovariectomized rats. An ovariectomy or a sham operation was performed on each 3 week–old female Sprague‐Dawley rat. Starting 1 week after the operation the hind limb skin of each rat was irradiated with UVB at a suberythemal dose (130 mJ/cm2) three times a week for 3 or 6 weeks. Decreases in elasticity and wrinkle formation in the skins of ovariectomized animals were induced more quickly than in the skins of sham‐operated animals following UVB irradiation. The linearity of elastic fibers in the ovariectomy group decreased significantly compared with the sham‐operation group, but erythema in the ovariectomy group was induced more readily than in the sham‐operation group following UVB irradiation. These findings suggest that decreases in the estrogen levels after ovariectomy accelerate photoaging in terms of the morphology and physical properties of the skin surface and the three‐dimensional structure of elastic fibers.

New formulation of chemical peeling agent: histological evaluation in sun-damaged skin model in hairless mice

BACKGROUND chemical peelings injure the superficial skin, which is then restored by healing of the wound. OBJECTIVES to document the acute and chronic histological changes produced by applying chemical peeling agents used clinically to the UVB-irradiated skin of hairless mice, which served as a model of sun-damaged skin. DESIGN three chemical peeling agents, 30% salicylic acid, dissolved in macrogol (a new formulation), 35% trichloroacetic acid (TCA) dissolved in distilled water and 20% glycolic acid dissolved in glycerin were applied to the backs of UVB-irradiated hairless mice. Untreated, irradiated areas of skin served as controls. Specimens were evaluated histologically at 3, 14, 28, and 70 days. RESULTS chronic UVB irradiation produced an irregular hypertrophy of the epidermis. The treated areas of irradiated skin recovered by day 70. At 28 days, all skin specimens treated with chemical peeling agents exhibited a unique connective tissue layer composed of fine collagen fibers beneath the epidermis. While 35% TCA produced severe tissue damage marked by inflammation up to day 14, no inflammatory infiltrates were seen with 30% salicylic acid in macrogol at 70 days. CONCLUSIONS chemical peeling with 30% salicylic acid dissolved in macrogol led to reorganization of the epidermis and a rebuilding of the superficial dermal connective tissue important in reducing wrinkles, and without evidence of inflammatory infiltrates in an animal model of sun-damaged skin. Findings suggest a possible clinical benefit.

Carbon dioxide laser treatment promotes repair of the three-dimensional network of elastic fibres in rat skin.

Background  We have previously reported that ultraviolet (UV) B irradiation induces a loss of linearity in the three‐dimensional structure of dermal elastic fibres, which results in the reduction of elastic properties of the skin and leads to wrinkle formation. We further reported that repair of wrinkles by all‐trans retinoic acid is accompanied by recovery of the linearity of elastic fibres. Carbon dioxide (CO2) lasers are widely used for treating wrinkles in cosmetic surgery.

Effect of room humidity on the formation of fine wrinkles in the facial skin of Japanese.

Background/purpose: Changes in humidity are commonly known to influence the condition of the skin. Previous studies of the skin dealt with variations in relative humidity (RH) either through statistical analysis or by maintaining room humidity at a constant level; however, the range of humidity and the length of acclimation varied in each study. This study aimed to determine whether the generally used ranges of RH are truly acceptable for studies of human skin.

Gender‐dependent differences in degree of facial wrinkles

This study aimed to reveal gender‐dependent differences in the degree of facial wrinkles.