title: Amino Acid profiles in human tear fluids analyzed by high-performance liquid chromatography and electrospray ionization tandem mass spectrometry.
abstract: OBJECTIVE
  To identify the 23 amino acid profiles in human tear fluids, and to evaluate whether the ocular disease conditions reflect the amino acid profiles.
  
  
  METHODS
  Laboratory investigation.
  
  
  METHODS
  We evaluated the concentrations and relative composition of 23 amino acids in tear fluids obtained from 31 healthy volunteers using reversed-phase high-performance liquid chromatography and electrospray ionization tandem mass spectrometry, and compared them with those in plasma and aqueous humor. We also evaluated the tear-fluid amino acid profiles from 33 affected subjects.
  
  
  RESULTS
  The amino acid profiles of the basal tear and reflex tear were found to be similar, and 4 distinct groups of healthy volunteers (male, female, young, and elderly) showed similar profiles. Absolute concentrations of taurine (Tau) and L-glutamine were significantly dominant in these tear fluids. The relative compositions of Tau, L-glutamic acid, L-arginine (Arg), and citrulline in the tear fluid were significantly higher than those in the plasma and aqueous humor. Analysis of the hierarchical clustering of the amino acid profiles clearly distinguished severe ocular surface diseases from non-ocular surface diseases. The relative compositions of Tau, L-methionine, and Arg decreased in severe ocular surface disease subjects compared with non-ocular surface disease subjects.
  
  
  CONCLUSIONS
  Tear-fluid amino acid profiles differ from those in plasma and aqueous humor. Steady-state tear-fluid amino acid profiles might reflect ocular-surface homeostasis and the observed changes of amino acids might have a close relation with the disease conditions on the ocular surface.
authors.affiliation: Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Nakatsukasa
authors.forename: Chie
authors.initials: C
authors.lastname: Sotozono
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Shimbo
authors.forename: Nobukazu
authors.initials: N
authors.lastname: Ono
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyano
authors.forename: Akira
authors.initials: A
authors.lastname: Okano
authors.forename: Junji
authors.initials: J
authors.lastname: Hamuro
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kinoshita
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology; D000596:Amino Acids / Q000378:metabolism*; D001082:Aqueous Humor / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003229:Conjunctival Diseases / Q000378:metabolism*; D003316:Corneal Diseases / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D015422:Scleral Diseases / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D013262:Stevens-Johnson Syndrome / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D013666:Tears / Q000378:metabolism*; D055815:Young Adult
chemical_list: D000596:Amino Acids