Abstract
Purpose: :
To identify the endogenous Psychosine and glycolipids of the trabecular meshwork (TM) by mass spectrometric shotgun lipidomics.
Methods: :
The human TM samples were collected adhering to tenets of declaration of Helsinki under IRB approved protocols. The TM were obtained from Caucasian donors with mean age of 60 ± 6 years (n=8 each). Control TM samples were from cadavers and left over rim tissues of penetrating keratoplasty surgery respectively. Lipids were extracted using the Bligh and Dyer method, and re-suspended in Isopropyl, Acetonitrile solution. For lipid analyses we have used positive ion mode neutral loss scan (NLS) for psychosine (neutral product loss of m/z 180) using a collision energy of 24 and spray voltage of 4000V with a TSQ Quantum Access Max instrument. The samples were infused and scanned for one minute between 200 m/z to 1000 m/z. Ratiometric quantification was performed using quantitative galactosyl sphingosine D-galactosyl-ß1-1'-D-erythro-sphingosine (parent mass 461.64).
Results: :
We found several lipid species in the human TM that are identified by NLS scan for neutral loss of m/z 180. We found a number of glycolipids (sugar moiety: neutral loss of m/z 180) that were identified in scan of m/z 180 neutral loss. Unique glycolipids in controls that are absent in glaucomatous TM are being subjected to further characterization using high-resolution mass spectrometry.
Conclusions: :
We found unique glycolipids in control TM that are either absent or present in very low (sub picomole) levels in glaucomatous samples.
Keywords: lipids • trabecular meshwork • aqueous