ABSTRACT
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 9.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 9.2 Subjects and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
9.2.1 Subjects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 9.2.2 Skin Regions and Timing for Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
9.3 Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.1 Water Content in Stratum Corneum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.2 Transepidermal Water Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.3 Skin Surface pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.4 Parakeratotic Index of Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.5 Free Amino Acid in Stratum Corneum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 9.3.6 Ceramides in Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
9.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 9.4.1 Water Content in Stratum Corneum. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 9.4.2 Transepidermal Water Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 9.4.3 Skin Surface pH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 9.4.4 Parakeratotic Cells in Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 9.4.5 Free Amino Acid Content in Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 9.4.6 Ceramide Levels in Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 9.4.7 Characteristics of Stratum Corneum in Various Types of Dry Skin . . . . . . . . . . . . 103
9.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
We investigated the characteristics of the dry skin in patients with atopic dermatitis (AD) and those on hemodialysis (HD) using noninvasive methods. Transepidermal water loss (TEWL), water content, parakeratotic cells, free amino acid and ceramide in stratum corneum (SC), and skin surface pH were examined on lesional and nonlesional skin in the dorsolumbar part of AD patients, HD patients, and healthy normal controls. The water content in SC on lesional and nonlesional skin was markedly lower in the AD patients than in the normal controls. The water content in SC was also lower in HD patients. The level of free amino acids, which represents the natural moisturizing factor (NMF) in SC, was decreased in both patient groups, which corresponded with the decrease of their water content in SC. TEWL was high in AD patients, but that in HD patients was almost similar to that in the controls. The level of the ceramides, which are closely related to the barrier function of SC, was lower in AD patients than in HD patients or in the controls, which was in agreement with the results of TEWL. In the composition of ceramides, the HD patients showed a higher percentage of ceramides 2
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Dry Skin and Moisturizers: Chemistry and
and 3 and a lower ratio of 1, 4/5, and 6 in comparison with the controls. No parakeratotic corneocytes were found in the controls or HD patients, while they were found in not only the lesional but also nonlesional skin of AD patients, indicating the presence of mild inflammation even in nonlesional skin. The conversion ratio of ornithine, which is a free amino acid component in SC, to citrulline was lower in AD patients than in HD patients or the controls. This suggested increased epidermal proliferation in AD patients. The skin surface pH value was high in both AD and HD patients, and the latter showed a higher value than the former. Except for pH, the results of all of the measurements in the nonlesional skin of AD patients were found to be intermediate between those of the lesional skin and the normal controls, showing that the lesional skin is physiologically different from the nonlesional skin.
