title: Advanced glycation end product (AGE) modified proteins in tears of diabetic patients.
abstract: OBJECTIVE
  High glucose level in diabetic patients may lead to advanced glycation end product (AGE) modified proteins. This study investigated AGE modified proteins in tears and compared their levels in diabetic patients (DM) with non-diabetic controls (CTL).
  
  
  METHODS
  Basal tears were collected from DM with (DR) or without (DNR) retinopathy and CTL. Total AGE modified proteins were detected quantitatively by a dot immunobinding assay. The AGE modified proteins were separated in 1D- and 2D-SDS gels and detected by western-blotting. The individual AGE modified proteins were also compared between groups using densitometry.
  
  
  RESULTS
  Compared with the CTL group, tear concentrations of AGE modified proteins were significantly elevated in DR and DNR groups. The concentration of AGE modified proteins in diabetic tears were positively correlated with AGE modified hemoglobin (HbA1c) and postprandial blood glucose level (PBG). Western blotting of AGE modified proteins from 1D-SDS gels showed several bands, the major one at around 60 kDa. The intensities of AGE modified protein bands were higher in DM tears than in CTL tears. Western blotting from 2D-SDS gels showed a strongly stained horizontal strip, which corresponded to the major band in 1D-SDS gels. Most of the other AGE modified protein species were within molecular weight of 30-60 kDa, PI 5.2-7.0. Densitometry analysis demonstrated several AGE modified proteins were elevated in DR or DNR tears.
  
  
  CONCLUSIONS
  Total and some individual AGE modified proteins were elevated in DM tears. AGE modified proteins in tears may be used as biomarkers to diagnose diabetes and/or diabetic retinopathy.
authors.affiliation: Brien Holden Vision Institute, Sydney, NSW 2052, Australia. z.zhao@brienholdenvision.org
authors.forename: Zhenjun
authors.initials: Z
authors.lastname: Zhao
authors.forename: Jingfang
authors.initials: J
authors.lastname: Liu
authors.forename: Bingyin
authors.initials: B
authors.lastname: Shi
authors.forename: Shuixiang
authors.initials: S
authors.lastname: He
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Yao
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Willcox
mesh_terms: D000368:Aged; D015153:Blotting, Western; D016022:Case-Control Studies; D003920:Diabetes Mellitus / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005136:Eye Proteins / Q000378:metabolism*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D013666:Tears / Q000378:metabolism*
chemical_list: D005136:Eye Proteins; D006442:Glycated Hemoglobin; D017127:Glycation End Products, Advanced; C517652:hemoglobin A1c protein, human
references.citation: Optom Vis Sci. 1997 Jan;74(1):8-13
references.pmid: 9148269
references.citation: J Diabetes Complications. 2008 Jul-Aug;22(4):261-6
references.pmid: 18413194
references.citation: Atherosclerosis. 1992 Apr;93(3):237-44
references.pmid: 1590828
references.citation: AAPS PharmSci. 1999;1(4):E20
references.pmid: 11741216
references.citation: Ann N Y Acad Sci. 2008 Apr;1126:42-5
references.pmid: 18448794
references.citation: Biochemistry (Mosc). 2008 Apr;73(4):381-92
references.pmid: 18457567
references.citation: Ophthalmology. 1983 Jun;90(6):585-91
references.pmid: 6888852
references.citation: Pathobiology. 2006;73(5):244-51
references.pmid: 17314495
references.citation: Adv Exp Med Biol. 2002;506(Pt A):555-65
references.pmid: 12613960
references.citation: Br J Ophthalmol. 2000 Jan;84(1):19-21
references.pmid: 10611093
references.citation: Kobe J Med Sci. 1989 Feb;35(1):1-9
references.pmid: 2507822
references.citation: Biochimie. 2009 Jan;91(1):35-43
references.pmid: 18718499
references.citation: Invest Ophthalmol Vis Sci. 1983 May;24(5):623-30
references.pmid: 6841010
references.citation: J Indian Med Assoc. 2003 Aug;101(8):481-3
references.pmid: 15071801
references.citation: Br J Ophthalmol. 2007 Mar;91(3):397-8
references.pmid: 17322470
references.citation: Int Ophthalmol Clin. 1987 Spring;27(1):2-6
references.pmid: 3818196
references.citation: Exp Eye Res. 2004 Mar;78(3):347-60
references.pmid: 15106912
references.citation: Acta Ophthalmol (Copenh). 1994 Oct;72(5):576-80
references.pmid: 7887155
references.citation: Glycoconj J. 1995 Oct;12(5):618-21
references.pmid: 8595250
references.citation: Genome Biol. 2006;7(8):R72
references.pmid: 16901338
references.citation: Ocul Surf. 2007 Jul;5(3):228-39
references.pmid: 17660896
references.citation: Curr Eye Res. 1997 Jun;16(6):577-88
references.pmid: 9192167
references.citation: Ann Acad Med Singap. 2006 Jun;35(6):400-7
references.pmid: 16865190
references.citation: Ophthalmologica. 1982;184(2):87-91
references.pmid: 7063175
references.citation: Acta Med Scand. 1981;210(4):313-6
references.pmid: 7315531
references.citation: BMC Ophthalmol. 2002 Oct 31;2:4
references.pmid: 12489986
references.citation: Curr Eye Res. 2006 Nov;31(11):895-901
references.pmid: 17114114
references.citation: Invest Ophthalmol Vis Sci. 2005 Oct;46(10):3589-96
references.pmid: 16186338
references.citation: Ophthalmologe. 1994 Apr;91(2):235-9
references.pmid: 8012143
references.citation: Diabetes Metab Res Rev. 2008 May-Jun;24 Suppl 1:S19-24
references.pmid: 18442180
references.citation: Adv Exp Med Biol. 1994;350:231-8
references.pmid: 8030482
references.citation: Graefes Arch Clin Exp Ophthalmol. 2001 Apr;239(4):257-63
references.pmid: 11450489
references.citation: Eye Contact Lens. 2003 Jan;29(1 Suppl):S80-2; discussion S83-4, S192-4
references.pmid: 12772738
references.citation: Curr Pharm Des. 2008;14(10):962-8
references.pmid: 18473846
references.citation: J Cell Mol Med. 2009 Aug;13(8B):1751-1764
references.pmid: 19602045
references.citation: Eur J Clin Chem Clin Biochem. 1992 Oct;30(10):651-6
references.pmid: 1493158
references.citation: Curr Pharm Des. 2008;14(10):953-61
references.pmid: 18473845
references.citation: Curr Pharm Des. 2008;14(10):969-72
references.pmid: 18473847
references.citation: Ann N Y Acad Sci. 2005 Jun;1043:676-80
references.pmid: 16037292
references.citation: Electrophoresis. 1997 Dec;18(15):2811-5
references.pmid: 9504814
references.citation: Antioxid Redox Signal. 2009 Dec;11(12):3071-109
references.pmid: 19489690
references.citation: Curr Diabetes Rev. 2008 May;4(2):92-100
references.pmid: 18473756
references.citation: Optom Vis Sci. 2008 Aug;85(8):653-60
references.pmid: 18677223
references.citation: Diabetes Res. 1991 Jan;16(1):1-9
references.pmid: 1818791
references.citation: Diabetes Care. 2004 Jan;27 Suppl 1:S84-7
references.pmid: 14693935
references.citation: Ocul Surf. 2007 Oct;5(4):280-93
references.pmid: 17938838
references.citation: Dev Ophthalmol. 2008;41:1-20
references.pmid: 18453758