Naslov
Association between lens protein glycation and cataract development in diabetic rats

Autori
Turk, Zdenka ; Mišur, Irena ; Slijepčević, Milivoj ; Ročić, Boris

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts of the 16th International Diabetes Federation Congress ; u: Diabetologia 40 (1997) (S) / Ferrannini, E. - Heidelberg : Springer, 1997, A437-A437

Skup
International Diabetes Federation Congress (16 ; 1997)

Mjesto i datum
Helsinki, Finska, 20.07.1997. - 25.07.1997

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Glycation; lens proteins; cataract; phlorizin

Sažetak
To assess the temporal association between glycation of lens proteins and the creation of polymeric products believed to contribute to the onset of cataract we followed the formation of early and late glycated adducts in the lenses of hyperglycaemic rats during a period of 5 mo.We examined, whether phlorizin treatment of diabetic rats by inhibiting renal tubular glucose reabsorption influences advanced glycation process.The study groups included controls (C), untreated diabetic rats (D), and diabetic rats receiving insulin alone (DI) or in combination with phlorizin (DIP).Lenses were removed at 4 and 20 wk, and advanced glycated products in alkali- soluble lens proteins were determined by their spectrofluorescence (385/335nm).In 20-wk untreated diabetic as compared to control rats, a significant increase was observed in the fluorescence level (3.25 1.02 vs 1.61 0.17 FU/mg, p<0.001), while in 4-wk animals the increase was from 1.26 0.11 FU/mg in controls to 1.80 0.25 FU/mg in diabetics, p<0.001.Daily treatment of 20-wk diabetic rats with insulin alone (2.46 0.48 FU/mg) or in combination with phlorizin (2.30 0.26 FU/mg) did not significantly influence lens fluorescence level.The amount of glucose bound ketoamine linkage was estimated after acid hydrolysis as released 5- hydroxymethylfurfural (HMF).In 20-wk controls, it was slightly higher than in 4-wk controls (0.57ą0.31vs0.41 0.20 nmol HMF/mg, respectively).The diabetic group showed a significant increase, however.In 4-wk diabetics, a level of 1.07 0.36 nmol HMF/mg was found, while in 20-wk animals the glycated protein amount rose to 2.46 0.79 nmol HMF/mg.In addition to the increases in glycated content with continuing diabetic hyperglycaemia, significant changes in protein composition of alkali-soluble lenses developed.The SDS-PAGE pattern showed an appearance of protein polymers of heterogeneous size (C-4wk: 3.0 1.1% vs C- 20wk:17.9 2.9% D-4wk:7.3 2.1% vs D- 20wk:19.8 3.6%) and the proteins of high molecular weight (HMW).Only a small amount of these HMW proteins was present in controls (C- 20wk: 2.5 1.2%) and short-term diabetes (D- 4wk: 0.8 0.2%), whereas in long-term untreated diabetes there was a dramatic increase (D-20wk: 30.5 3.2%) with a corresponding decrease in other peaks.All diabetic animals from this group had macroscopically detectable cataractous lenses.The treatment with insulin or insulin/phlorizin followed the HMW protein level of the untreated animals (28.2 4.0% or 27.08 3.3% vs 30.52 3.32%).

Izvorni jezik
Engleski

Znanstvena područja
Kliničke medicinske znanosti

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