Monday, November 19, 2012

ADVANCED GLYCATION END PRODUCTS: AN INTRODUCTION


The molecular mechanism by which hyperglycemia produces toxic effect is unknown, but glycation of tissue proteins may be important. Nonenzymatic attachment of glucose to long lived proteins like collagen or DNA, produces stable Amadori early Glycated products. These undergo a series of additional rearrangements dehydration and fragmentation reactions, resulting in stable advanced glycation end products (AGE). The amounts of these products do not return to normal when hyperglycemia is corrected and they accumulate continuously over the lifespan of the protein. Hyperglycemia accelerates the formation of protein-bound AGE, and patients with diabetes mellitus thus have more AGE than healthy subjects. Through effects on the functional properties of protein and extracellular matrix, AGE may contribute to the microvascular and macrovascular complications of diabetes mellitus. Moreover an inhibitor of AGE formation, aminoguanidine has been shown to prevent several complications of diabetes in animal model.

In healthy people Hb-AGE accounts for 0.4% of circulating Hb, with significantly higher in diabetes mellitus. After acute change in glycemia, Hb-AGE level changes, but the rate of alteration is 23% slower than that of HbA1c. Thus Hb-AGE provides a measure of diabetic control longer than that indicated by GHb, reflecting blood glucose concentration over a greater proportion of life of red blood cells. 
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