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Ayman Aljohani, Yenifer Guerra, Maria Piqueras, Richard Lee, Sanjoy Bhattacharya; Differential Comparison of Aqueous Humor Phosphatidylcholines from Control and Glaucomatous Donors. Invest. Ophthalmol. Vis. Sci. 2013;54(15):1970.
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To compare the phosphatidylcholines (PC) of the aqueous humor (AQH) from control and primary open angle glaucoma (POAG) donors by mass spectrometric shotgun lipidomics. Our hypothesis is that select PCs are absent in POAG AQH, which may contribute to increased stiffness of trabecular meshwork in POAG.
The human AQH samples were collected adhering to tenets of declaration of Helsinki under IRB approved protocols from control and POAG donors of diverse race and both genders with mean age of 55 ±8 years (n=10 each). Controls were cataract surgery patients. AQH PCs were extracted using the Bligh and Dyer method, re-suspended in Isoproyl, Acetonitrile solution and analyzed on a TSQ Quantum Access Max instrument in positive mode. Precursor ion scan (PIS) for phosphocholines (PC; product m/z of 184) were performed using direct infusion. Ratiometric quantification was performed for m/z range of 200-1000. The PC species of control and glaucoma patients were identified using MZmine 2.9 version and database from lipidmaps.org. The profiles were compared using in-house written softwares. Further confirmatory analyses were performed on a high resolution Q-exactive mass spectrometer.
Overall total amount of PCs in POAG normalized to protein amounts were always less than that in controls. We found 7 and 4 unique PCs in controls and POAG AQH respectively. The number of unique PC species that showed up are 2 in control (12:0/14:1(9Z)), PC(13:0/20:5(5Z,8Z,11Z,14Z,17Z))] and only one in POAG [PC(12:0/14:1(9Z))] AQH.
Lower amounts of phosphatidylcholines were found in POAG compared to controls. This was confirmed by high resolution mass spectrometry. Absence of select PC species in POAG is likely to contribute to reduced membrane fluidity and likely result in stiffness to TM cells in glaucoma.
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