A trial of a method to trace metabolic pathways of nucleic acids in keratinocytes.

It is well known that furocumarins produce a photoaddition compound with DNA, RNA, and certain kinds of amino acids upon exposure to long-wave ultraviolet light (UVA). It is also well known that both psoralens and psoralen photoconjugated compounds are fluorescent. After 8-methoxypsoralen was administered systemically and subsequently activated by UVA exposure, the hair and the epidermis were taken and observed under a fluorescent light microscope. The fluorescent materials appeared to be able to trace the metabolic pathway of psoralen-conjugated compounds such as DNA, RNA, and certain kinds of amino acids. Large amounts of nuclear proteins appeared to be transformed from nuclear proteins into certain structural proteins in keratinocytes.