title: Increased levels of diadenosine polyphosphates in dry eye.
abstract: OBJECTIVE
  To analyze the levels of the diadenosine polyphosphates Ap4A and Ap5A in tears, in a set of control subjects and in groups of symptomatic and nonsymptomatic persons with dry eye.
  
  
  METHODS
  Ninety-seven subjects participated in the study. The subjects were divided into five experimental groups: control subjects; symptomatic patients with normal tear secretion; symptomatic patients with low tear secretion; forced blink; and corneal mechanical stimulation provided by a gas esthesiometer. The Schirmer I test was used to measure and collect tear secretions from each subject. All samples were processed by high pressure liquid chromatography (HPLC) and their Ap4A and Ap5A levels determined.
  
  
  RESULTS
  The levels of Ap4A and Ap5A in tears were greater in all symptomatic patients than in control subjects, especially in symptomatic subjects with low tear secretion. Within the symptomatic subjects with normal tear secretion, significant differences in concentrations of Ap4A and Ap5A were found between men and women. In the forced blink experiments, concentrations of the Ap4A and Ap5A rose with increasing blink frequency. When the cornea was mechanically stimulated, the levels of Ap4A and Ap5A rose significantly during both moderate and high-flow rate tests.
  
  
  CONCLUSIONS
  The increased levels of Ap4A and Ap5A in tears of patients with dry eye allow these dinucleotides to be used as objective biomarkers in dry eye conditions.
authors.affiliation: Departamento de Optica II (Optometría y Visión), Escuela Universitaria de Optica, Universidad Complutense de Madrid, Madrid, Spain. assumpta@opt.ucm.es
authors.forename: Assumpta
authors.initials: A
authors.lastname: Peral
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Carracedo
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Acosta
authors.forename: Juana
authors.initials: J
authors.lastname: Gallar
authors.forename: Jesús
authors.initials: J
authors.lastname: Pintor
mesh_terms: D000328:Adult; D002851:Chromatography, High Pressure Liquid; D015226:Dinucleoside Phosphates / Q000378:metabolism*; D015352:Dry Eye Syndromes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D013666:Tears / Q000378:metabolism*
chemical_list: D015226:Dinucleoside Phosphates; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate