Plasma protein glycation in Alzheimer's disease

Recent studies have suggested that formation of advanced glycation end-prod ucts (AGEs) in some brain proteins could be associated with Alzheimer's dis ease. These AGEs can be produced by various sugars (hexose, pentose, glycer aldehyde and oxidative products of vitamin C). In this study, we quantified plasma protein glycation specifically derived from glucose in patients wit h Alzheimer's disease with different grades of cognitive disorders. Two groups of Alzheimer patients were studied: a group with moderate Alzhei mer's disease (n=6, 9<MMS<20) and a severe Alzheimer group (n=13, MMS<9) wh o were compared with an age-matched control group (n=10, MMS>23) and a grou p of subjects with diabetes (n=31). Protein glycation was evaluated in plas ma with a highly specific HPLC-UV technique, using furosine, which is the a cid hydrolysis product of epsilon-deoxy-fructosyl-lysine Plasma furosine was almost two times higher in subjects with Alzheimer's di sease (p < .005) than in controls, but still 50% lower than in diabetic pat ients (P<.02). Pasting plasma glucose levels were significantly correlated to the furosine concentration. To explain these results, an eventual impair ment in glucose peripheral use or an increase in protein glycation rate ass ociated with Alzheimer's disease should be explored.