title: Exogenous origin of n-alkanes in pathologic scale.
abstract: BACKGROUND
  Although n-alkanes accumulate in some disorders of cornification, recent studies using radioactive carbon 14 content by accelerator mass spectrometry point to an exogenous origin for alkanes in normal stratum corneum, and their derivation in congenital ichthyosiform erythroderma remains controversial.
  
  
  RESULTS
  Using 14C content to measure sample age, the n-alkane fractions from two patients with congenital ichthyosiform erythroderma contained no detectable contemporary materials. By electron microscopy, alkane-enriched emollients (petrolatum [Vaseline]) permeated to all levels of stratum corneum of hairless mice, expanding the intercellular domains and distorting membrane bilayers. Similar ultrastructural changes were also observed in the stratum corneum of patients with congenital ichthyosiform erythroderma. When alkanes were excluded, no differences in lipid content were evident between two forms of autosomal recessive ichthyosis.
  
  
  CONCLUSIONS
  These data demonstrate that scale n-alkanes in disorders of cornification derive from environmental sources and indicate the pervasiveness of petroleum-based emollients in skin. Therefore, epidermal lipid analyses must be interpreted with caution. However, these studies do not rule out an important therapeutic and/or pathogenic role for exogenous n-alkanes in skin.
authors.affiliation: Dermatology Service, Veterans Affairs Medical Center, San Francisco, CA 94121.
authors.forename: M L
authors.initials: ML
authors.lastname: Williams
authors.forename: J S
authors.initials: JS
authors.lastname: Vogel
authors.forename: R
authors.initials: R
authors.lastname: Ghadially
authors.forename: B E
authors.initials: BE
authors.lastname: Brown
authors.forename: P M
authors.initials: PM
authors.lastname: Elias
mesh_terms: D000328:Adult; D000473:Alkanes / Q000032:analysis / Q000493:pharmacokinetics*; D000818:Animals; D006801:Humans; D016113:Ichthyosiform Erythroderma, Congenital / Q000378:metabolism / Q000473:pathology*; D050356:Lipid Metabolism; D008055:Lipids / Q000032:analysis; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D008854:Microscopy, Electron; D012867:Skin / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D014018:Tissue Distribution
chemical_list: D000473:Alkanes; D008055:Lipids