title: Mass spectrometric analyses of phosphatidylcholines in alkali-exposed corneal tissue.
abstract: OBJECTIVE
  The aims were to determine whether exposure to sodium hydroxide results in predictable changes in phosphatidylcholine (PC) in corneal tissue and if PC profile changes correlate to exposure duration. PCs are major components of the cell membrane lipid bilayer and are often involved in biological processes such as signaling.
  
  
  METHODS
  Enucleated porcine (n = 140) and cadaver human eyes (n = 20) were exposed to water (control) and 11 M NaOH. The corneas were excised and lipids were extracted using the Bligh and Dyer method with suitable modifications. Class-specific lipid identification was carried out using a ratiometric lipid standard on a TSQ Quantum Access Max mass spectrometer. Protein amounts were determined using Bradford assays.
  
  
  RESULTS
  Control and alkali-treated corneas showed reproducible PC spectra for both porcine and human corneas. Over 200 PCs were identified for human and porcine control and each experimental time point. Several PC species (m/z values) consequent upon alkali exposure could not be ascribed to a recorded PC species. Control and treated groups showed 41 and 29 common species among them for porcine and human corneas, respectively. The unique PC species peaked at 12 minutes and at 30 minutes for human and porcine corneas followed by a decline consistent with an interplay of alkali penetration and hydrolyses at various time points.
  
  
  CONCLUSIONS
  Alkali exposure dramatically changes the PC profile of cornea. Our data are consistent with penetration and hydrolysis as stochastic contributors to changes in PCs due to exposure to alkali for a finite duration and amount.
authors.affiliation: Bascom Palmer Eye Institute, University of Miami, Miami, Florida, USA.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Crane
authors.forename: Hong-Uyen
authors.initials: HU
authors.lastname: Hua
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Coggin
authors.forename: Bogdan G
authors.initials: BG
authors.lastname: Gugiu
authors.forename: Byron L
authors.initials: BL
authors.lastname: Lam
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Bhattacharya
mesh_terms: D000468:Alkalies / Q000633:toxicity; D000818:Animals; D002057:Burns, Chemical / Q000378:metabolism*; D003315:Cornea / Q000737:chemistry*; D065306:Corneal Injuries; D004195:Disease Models, Animal; D005126:Eye Burns / Q000378:metabolism*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D010713:Phosphatidylcholines / Q000032:analysis*; D013552:Swine
chemical_list: D000468:Alkalies; D010713:Phosphatidylcholines