Hexosamine and Hydroxyproline Alterations in Chronically Sun-Damaged Skin.

1. The upper dermis of chronically sun-damaged human skin contains more hexosamine and less hydroxyproline than the upper dermis from unexposed areas. 2. The increased hexosamine confirms the presence of increased acid mucopolysaccharides seen histologically in sun-damaged skin, but the decreased hydroxyproline does not identify the elastin staining material as either elastin or “degraded” collagen. 3. The upper dermis of sun-damaged skin has higher hexosamine and lower hydroxyproline levels than the lower-most dermis of the same specimen, thus the localization of the biochemical alteration corresponds with the localization of the histologic abnormality.