Objective To evaluate the therapeutic effect of endothelin antagonist on ultraviolet B (UVB)-induced pigmentation in guinea pigs.Methods A skin pigmentation model was established by UVB irradiation in guinea pigs.The modeled animals were divided into 3 groups to be treated with sodium chloride physiological solution (blank control group),an endothelin antagonist (endothelin antagonist group) and arbutin (positive control group),respectively.Before the UVB irradiation,as well as after 15-and 30-day UVB irradiation,Mexameter(R) MX 18 was used to detect the melanin index in the dorsal skin of guinea pigs.After 30-day consecutive treatment,melanin index,the number of melanocytes in the epidermis and melanin content were compared among the above 3 groups.Results After 30-day UVB irradiation,the melanin index in the 9 UVB-irradiated areas on the dorsal skin of guinea pigs significantly increased compared with that before the radiation (P ＜ 0.0001).After 30-day treatment with the 1‰ endothelin antagonist,the melanin index in the UVB-irradiated areas significantly decreased compared with that in the positive control group (P ＜ 0.0001).Melanin content index-1 (MCI-1) was significantly lower in the endothelin antagonist group than in the blank control group (P ＜ 0.05),while no significant difference in MCI-2 was observed among the 3 groups (P ＞ 0.05).Conclusion Topical application of the endothelin antagonist has a certain therapeutic effect on UVB-induced pigmentation in guinea pigs.

Objective To study the ultramicrostructure change and keartin(KRT1) expression in skin lesion of symmetrical acral keratoderma(SAK) .Methods Thirteen cases of SAK in the First Affiliated Hospital of Fujian Medical University and the outpatient department of the Dongguan Municipal Sixth People′s Hospital were selected as the study subjects .The histopathological samples were taken from the wrist site .The retinoic acid preparation or corticosteroid preparation or Chinese medicine preparation were not externally used within 2 months before taking skin lesion sample .The healthy control skin samples were the normal skin in 12 cases by plastic surgical resection .The ultramicrostructural change were observed by the transmission electron microscopy .The KRT1 expression in skin lesion of 13 cases of SAK and healthy skin tissue of 12 cases were measured by immunohistochemistry method .Results The SAK ultramicrostructures manifested by the interruption of keratinizing envelope continuity in horny layer , and remarkable aggregation of keratin filament in upper stratum spinosum and surrounding nucleus of granular layer .KRT1 was ex-pressed in the cells of SAK skin lesion and basal layer ,spinous layer ,granular layer and horny layer .The cytoplasm and cytomem-brane staining was common .The KRT1 expression in skin lesion was significantly higher than that in normal skin (t=2 .210 ,P=0 .038) .Conclusion The ultramicrostructure features of SAK skin lesion are abnormal differentiation of epidermis keratin fila-ments ,which might be related with overexpression of KRT 1 .