Age-associated changes in integral cholesterol and cholesterol sulfate concentrations in human scalp hair and finger nail clippings

In contrast to surface lipids originating from the sebaceous glands, membra ne-forming integral lipids occur in keratinized tissues of skin, and skin a ppendages like fingernail plates or scalp hair. After removal of lipids of sebaceous origin by exhaustive solvent extraction, lyophilizing and hydroly zing fingernail plate and scalp hair samples, fractions of integral cholest erol (CH) and cholesterol sulfate (CS) were quantified using gas chromatogr aphy. We studied these bound lipids and the serum lipids of 70 healthy subj ects, aged 20.1 to 92.0 years. We observed higher amounts of CS in hair cli p pings of men than of women (775 +/- 241 vs 662 +/- 239 nmol/g hair, respe ctively). The highest amounts of CS were found in men with serum LDL-CH > 4 .14 mmol/L; this subgroup also showed the highest CH values in fingernail c lippings (2293 +/- 621 nmol/g nail). However, analysis of integral lipids o f hair and fingernail plate clippings had little significance in detecting hypercholesterolemia in normal persons. An increase in integral CH levels i n fingernail clippings with donor age was noted, independently of variation s in serum CH or LDL-CH. This correlation proved to be significant in men ( R=0.43), but not in women (R=0.38). In contrast, in women but not in men we found donor age correlated with internal CH of hair samples (R=0.43) and w ith CS of nail plates (R=-0.59), independently of serum CH or LDL-CH variat ions. This age-dependent decrease in CS levels might explain the previously observed higher incidence of brittle nails in women. Obviously, the metabo lism of internal lipids CH and CS in fingernail and scalp hair differs betw een genders, and shows age-associated changes. (C) 2001, Editrice Kurtis.