Comparative Analysis of the Tear Protein Expression After Photorefractive Keratectomy Using Two-Dimensional Electrophoresis

PURPOSE:To investigate the change in the tear protein composition of patients who underwent refractive surgery. METHODS: Tear samples were collected before photorefrative keratectomy (PRK), on the first, the second, and the third postoperative day, and then a month after the operation from 40 eyes of 20 patients. These tear samples were analyzed using two-dimensional gel electrophoresis (2-DE). Matrix-associated laser desorption/ionization time of flight (MALDI-TOF) was employed for the identification of expressed proteins. Control tear samples were collected from 40 eyes of 20 healthy volunteers who had no history of ocular surgery or pathology. RESULTS: On the first postoperative day, lipocalin-1 precursor, lipocalin-1, and lysozyme were up-regulated. On the second postoperative day, serum albumin precursor and serum albumin were up-regulated. The tears collected on the third postoperative day and after 1 month had similar protein expression levels to the control group. Lipocalin 1 precursor and lysozyme were up-regulated and down-regulated after reftactive surgery, respectively. However, each protein had a different molecular weight and isopotential point. CONCLUSIONS: The tear protein composition changed uniquely in the early postoperative period, and proteins with different isopotential points were detected after PRK. We hypothesized that the healing process might influence the expression of the tear proteins.

Identification of alpha-2u globulin in the rat preputial gland by MALDI-TOF analysis.

The low molecular mass proteins found in the pheromonal sources such as urine, saliva, glandular secretion etc have been reported as ligand carriers for the processes of chemocommunication in mammals. The preputial gland plays an important role in the production of olfactory signals for pheromonal communication. Thus, in the present study, alpha-2u globulin having molecular mass of 18 kDa has been identified in the preputial gland of Norway rat (Rattus norvegicus) by in-gel trypsin digestion and analyzing the resulting peptides by MALDI-TOF. Since preputial gland is one of the major pheromonal sources in rat, the results suggest that alpha-2u globulin might act as a carrier for hydrophobic odorants of preputial gland.