de Fine Olivarius F, Wulf H C, Crosby J, Norval M
Department of Dermatology D 92, Bispebjerg Hospital, University of Copenhagen, Bispebjerg Bakke 23, DK-2400 NV Copenhagen, Denmark.
Br J Dermatol. 1998 Oct;139(4):605-9. doi: 10.1046/j.1365-2133.1998.02455.x.
Episodes of intense sun exposure, particularly in childhood, seem to carry a risk for the development of malignant melanoma in later life. However, little is known about photosensitivity and natural photoprotection in children. In adult subjects, photoprotection is provided mainly by the epidermal content of melanin and the thickness of the stratum corneum, while the amount of urocanic acid (UCA), a major ultraviolet-absorbing component of the stratum corneum, is not thought to contribute significantly to photoprotection. The minimal erythema dose (MED) was determined in 22 healthy children aged 6-13 years and in 36 healthy adults (mean age 28.1 years). Pigmentation was measured at six body sites by use of reflectance spectroscopy and the concentration of UCA isomers was measured in a sun-exposed area (upper back) and in unexposed buttock skin. No significant differences between children and adults were found, either in pigmentation at exposed and unexposed body sites, or in MED. The concentration of total UCA was significantly higher in the children than in the adults on the buttock (median 22.2 vs. 13.6 nmol/cm2), but not on the back. On exposed back skin, the children had a significantly higher percentage of cis-UCA than the adults (median 60.1 vs. 28.3%), while no difference was found on the buttock. In both groups, a significant correlation was found between pigmentation and MED (children: Spearman correlation coefficient 0. 58, P = 0.006; adults: Spearman correlation coefficient 0.69, P < 0. 0001), indicating that pigmentation is of major importance in determining photosensitivity in children as well as in adults. The concentration of total UCA did not correlate with the MED in either group.
强烈的阳光照射，尤其是在儿童时期，似乎会增加日后患恶性黑色素瘤的风险。然而，关于儿童的光敏感性和自然光保护作用，我们所知甚少。在成年受试者中，光保护主要由表皮中的黑色素含量和角质层厚度提供，而角质层中主要的紫外线吸收成分尿刊酸（UCA）的含量，一般认为对光保护作用贡献不大。对22名6至13岁的健康儿童和36名健康成年人（平均年龄28.1岁）测定了最小红斑量（MED）。通过反射光谱法在六个身体部位测量色素沉着，并在阳光暴露区域（上背部）和未暴露的臀部皮肤中测量UCA异构体的浓度。无论是在暴露和未暴露身体部位的色素沉着，还是在MED方面，儿童和成年人之间均未发现显著差异。臀部皮肤中儿童的总UCA浓度显著高于成年人（中位数分别为22.2和13.6 nmol/cm²），但背部没有差异。在暴露的背部皮肤上，儿童的顺式-UCA百分比显著高于成年人（中位数分别为60.1%和28.3%），而在臀部未发现差异。在两组中，均发现色素沉着与MED之间存在显著相关性（儿童：Spearman相关系数0.58，P = 0.006；成年人：Spearman相关系数0.69，P < 0.0001），这表明色素沉着在决定儿童和成年人的光敏感性方面都至关重要。两组中总UCA浓度均与MED无关。
