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Devi Kalyan Karumanchi, Elizabeth R Gaillard, James P Dillon; BIOMARKERS FOR EARLY DIAGNOSIS OF DIABETIC EYE DISEASES Devi Kalyan Karumanchi1, J. Dillon1, E.R. Gaillard1,2 1Department of Chemistry and Biochemistry, Northern Illinois University, Dekalb, IL 2Department of Biological Sciences, Northern Illinois University, Dekalb, IL. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5721.
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To investigate the physical and chemical biomarkers for the glycolytic modifications in the lens in order to develop a diagnostic tool for the early diagnosis of diabetes related eye diseases.
Lens proteins as well as intact lenses were glycated and the formation of advanced glycation endproducts (AGEs) were characterized using steady state fluorescence and time resolved single photon counting. The biophysical changes in the protein were studied using Dynamic and Static Light Scattering, Small Angle X-ray Scattering by measuring the change in scattering intensities.
From the steady state fluorescence measurements, we have observed a resonance energy transfer between tryptophan and AGEs. Also, with increase in time of glycation, we have observed that the AGEs absorb at wavelengths longer than 370 nm. We measured the fluorescence lifetimes of glycated protein with excitation at 370 nm and emission was monitored at 440 nm using time correlated single photon counting to be around 0.5, 2.8 and 9.8 ns with varying relative contributions. Small angle X-ray scattering data showed the change in inter-particle distances and structural spacing. Dynamic and Static light scattering data indicates an increase in particle size, molecular weight and decrease in protein diffusivity.
The eye lens doesn’t have any protein turnover and hence is an ideal tissue to study the early stage glycation due to hyperglycemic conditions. By screening for the formation of AGEs and quantifying the resulting physicochemical changes, we should be able to diagnose the development of diabetes at a very early stage. This in turn, will help in initiating the treatment/precautionary measures from an early stage and hence prevent the progression of the diseases like diabetic retinopathy and loss of vision.
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