Current Alzheimer Research (www.bentham.org/car), 2004, 1, 39-46
Bentham Science Publishers Ltd.(www.bentham.org)

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Involvement of Advanced Glycation End-products (AGEs) in Alzheimer’s Disease

Masayoshi Takeuchi^1,*, Seiji Kikuchi², Nobuyuki Sasaki³, Takako Suzuki¹, Takayuki Watai¹, Mina Iwaki¹, Richard Bucala⁴ and Sho-ichi Yamagishi⁵

¹Department of Biochemistry, Faculty of Pharmaceutical Science, Hokuriku University, Ho-3 Kanagawa-machi, Kanazawa 920-1181, Japan, ²Department of Neurology, Hokkaido University Graduate School of Medicine, K-15, N-7, Sapporo 060-8638, Japan, ³Department of Neuropsychiatry, Sapporo Medical University, S-1, W-16, Sapporo 060-8543, Japan, ⁴Departments of Medicine and Pathology, Yale University School of Medicine, 300 Cedar Street, New Haven CT 06520-8031, U.S.A, ⁵Department of Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011, Japan

*Address correspondence to this author at the Department of Biochemistry, Faculty of Pharmaceutical Science, Hokuriku University, Ho-3 Kanagawa-machi, Kanazawa 920-1181, Japan; Tel: +81-76-229-6197; Fax: +81-76-229-2781; E-mail: m-takeuchi@hokuriku-u.ac.jp

Abstract: The advanced stage of the glycation process (one of the post-translational modifications of proteins) leads to the formation of advanced glycation end-products (AGEs) and plays an important role in the pathogenesis of angiopathy in diabetic patients. It has recently become clear that AGEs also influence physiological aging and neurodegenerative diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS).

Recently we have provided direct immunochemical evidence for the existence of six distinct AGE structures within the AGE-modified proteins and peptides that circulate in the serum of diabetic patients on hemodialysis (DM-HD). We showed a direct toxic effect of the synthetic AGE-2 (glyceraldehyde-derived AGEs) on cortical neuronal cells and provided evidence for a toxic effect of AGE-2 present in DM-HD serum. These results indicate that of the various types of AGE structures that can form in vivo, the AGE-2 structure is likely to play an important role in the pathophysiological processes associated with AGE formation.

In AD brains, AGE-2 epitope was mainly present in the cytosol of neurons in the hippocampus and para-hipocampal gyrus. Protein cross-linking by AGE structures results in the formation of protease-resistant aggregates. Such protein aggregates may interfere with both axonal transport and intracellular protein traffic in neuron.

In this review, we provide an outline of AGEs formation in vivo and propose that the novel structural epitope AGE-2 is an important toxic moiety for neuronal cells in AD.

Keywords: advanced glycation end-products (AGEs), glyceraldehyde-derived AGEs, AGE-2 structure, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Alzheimer’s disease (AD), diabetes mellitus (DM), neurotoxicity, apoptosis.

INTRODUCTION

Alzheimer's disease (AD) is the most common cause of dementia in Western countries and in Japan. AD is characterized pathologically by the presence of senile plaques and neurofibrillary tangles (NFTs), the major constituents of which are the amyloid b protein (Ab) and tau protein, respectively. The deposition of Ab peptides is considered to be an early and causative event in the pathogenesis of AD and increases markedly during progression of the disease, leading in turn to the generation of NFTs and finally neuronal death [1]. It has been demonstrated that advanced glycation end-products (AGEs) can be identified immunohistochemically to be present in both senile plaques and NFTs from patients with AD [2, 3]. Glycation of Ab markedly enhances its aggregation in vitro [4], and the glycation of tau, in addition to hyperphos-phorylation, appears to enhance the formation of paired helical filaments [5, 6]. Taken together, these data imply that AGEs may be an important factor in the progression of neurodegenerative disorders that are characterised by protein aggregation and deposition.

The modification, aggregation, and deposition of proteins are a prominent part of many pathological processes and can play a direct role in tissue damage. The pathological role of the non-enzymatic modification of proteins by glucose, a process that is known as glycation, has become increasingly evident in different diseases. It is now well established that early glycation products undergo progressive modification over time in vivo to the formation of irreversible cross-links, after which these molecules are termed “AGEs”. AGEs have been implicated in the development of many of the pathological sequelae of diabetes and aging, such as atherosclerosis and renal insufficiency [7-10]. Recently, it has become clear that AGEs also have a role in neurodegenerative diseases such as AD [2-4, 6, 11], Parkinson’s disease (PD) [12], Creutzfeldt-Jakob disease [13], and amyotrophic lateral sclerosis (ALS) [14, 15].

In this review, we provide an outline of AGEs formation in vivo and propose that the novel structural epitope AGE-2 (glyceraldehyde-derived AGEs) is an important toxic moiety for neuronal cells in AD.

Non-enzymatic glycation

Reactive derivatives from non-enzymatic glucose-protein condensation reactions, as well as lipids and nucleic acids exposed to reducing sugars, form a heterogenous group of irreversible adducts called “AGEs”. AGEs were originally characterized by a yellow-brown fluorescent color and an ability to form cross-links with and between amino groups [16], but the term is now used for a broad range of advanced products of the glycation process (also called the “Maillard reaction”) [17-19], including N-carboxymethyllysine (CML) and pyrraline, which show neither color nor fluorescence and do not cross-link proteins [20, 21]. CML can be formed from the precursors glyoxal and glycolaldehyde by an intra-molecular Cannizzaro reaction, a process that is largely independent of glucose autoxidation [22]. The concept that CML is a marker of oxidation rather than glycation has recently received support.

The formation of AGEs in vitro and in vivo is dependent on the turnover rate of the chemically modified target, the time available, and the sugar concentration. The structures of the various cross-linked AGEs that are generated in vivo have not yet been completely determined. Because of their heterogeneity and the complexity of the chemical reactions involved, only some AGEs have been structurally characterized in vivo. The structural identity of AGEs with cytotoxic properties remains unknown.

Alternative routes for the formation of various AGEs in vivo

AGEs form by the Maillard process, a non-enzymatic reaction between ketones or aldehydes and the amino groups of proteins that contributes to the aging of proteins and to the pathological complications of diabetes [7-10, 23]. In the hyperglycemia produced by diabetes, this process begins with the conversion of reversible Schiff base adducts to more stable, covalently-bound Amadori rearrangement products. Over the course of days to weeks, these Amadori products undergo further rearrangement reactions to form the irreversibly-bound moieties known as AGEs. Recent studies have suggested that AGEs can arise not only from sugars, but also from carbonyl compounds derived from the autoxidation of sugars and other metabolic pathways [22, 24-26]. In a previous report [27-30], we described the contribution of glucose, a-hydroxyaldehydes (glyceral-dehyde and glycolaldehyde) and dicarbonyl compounds (methylglyoxal, glyoxal and 3-deoxyglucosone) to the glycation of proteins, and we developed anti-AGE antibodies that specifically recognize six distinct classes of AGE structures (AGE-1, glucose-derived AGEs; AGE-2, glyceraldehyde-derived AGEs; AGE-3, glycolaldehyde-derived AGEs; AGE-4, methylglyoxal-derived AGEs; AGE-5, glyoxal-derived AGEs; and AGE-6, 3-deoxyglucosone-derived AGEs) within the circulating proteins and peptides present in serum from diabetic patients on hemodialysis. Based on these data, we proposed a pathway for the formation of distinct AGEs by the Maillard reaction, sugar autoxidation, and sugar metabolic pathways in vivo, as shown in Fig. (1). 

Relationship between Alzheimer’s disease (AD) and glucose tolerance

There is very little known about the relationship between AD and glucose tolerance, and the higher prevalence of AD amongst diabetic patients remains controversial. Recently discovered links between type 2 diabetes and AD are indications of AGE and increased AGE receptor expression in brains of patients with AD [31, 32]. Ott et al. reported that diabetes mellitus almost doubles the risk of dementia and AD [33]. As AGEs are involved in diabetes complications, diabetes might influence AD brain pathology.

To what extent do circulating AGEs play a role in AD pathology? The degradation products of AGE-modified proteins are not cleared during renal dialysis of diabetic patients [27, 34]. These low-molecular-weight AGEs have been shown to be chemically reactive and to contribute to the further modification and damage of tissue proteins [34]. It remains of interest to determine whether AGE formation is involved in abnormal tau protein processing and in the deposition of   Ab that has been observed in the brains of patients undergoing renal dialysis [35].

Riviere et al. quantified plasma protein glycation specifically derived from glucose in AD patients [36]. Protein glycation in plasma, evaluated by plasma furosine, was almost two times greater in subjects with AD than in controls, but still 50% less than in subject with DM. Recently Shuvaev et al. studied changes in the level of an early glycation product, an Amadori product, in cerebrospinal fluid (CSF) in aging and in late-onset AD [37]. The concentration of an Amadori product in CSF correlated with the CSF glucose concentration but did not change with age. In contrast, the level of CSF Amadori product was 1.7 times greater in AD patients than in a non-demented age-matched control group.

Immunohistochemical studies on AGEs in AD brain

The possibility of the involvement of glycation in AD was first suggested in several reports published successively during 1994-5 [2, 4, 6, 38]. Senile plaques and neurofibrillary tangles were positively stained with anti-pyrraline and anti-pentosidine antibodies [2]. Sasaki et al. reported that senile plaques, even diffuse or primitive ones, were positively stained by an anti-serum against glucose-derived AGEs [3]. These findings support the possibility that glycation is involved in the initial stage of plaque formation. Neurofibrillary tangles were also stained positively in that study.

Recently our studies have also suggested that there is a role for AGEs and a receptor for AGEs (RAGE) in AD [11]. We showed that Ab-, AGE-1-, and RAGE-positive granules were present in the perikaryon of hippocampal neurons (especially forms CA3 and CA4) in all subjects (AD and DM patients). In AD brains, most astrocytes (approximately 70-80 %) contained both AGE-1- and RAGE-positive granules, and their distribution was almost the same, while fewer astrocytes contained Ab-positive granules (approximately 20-30 %). This finding suggests the presence of glycated proteins other than Ab. In DM patients and controls, the presence of AGE-1- and RAGE-positive astrocytes was very rare. These data support the hypothesis that glycated Ab  is taken up via RAGE and is degraded through the lysosomal pathway in astrocytes.

RAGE has been proposed to play a major role in the onset of the AD. RAGE is a member of the immunoglobulin superfamily of cell-surface molecules, and it is expressed in a variety of cell types, including endothelial cells, pericyte, mesangial cells, neurons, and glia [32, 39, 40]. RAGE has been shown to be the neuron cell receptor for amyloid b  [41]. The receptor-mediated reactions may further contribute to neuronal degeneration [11]. BIA core surface plasmon resonance assay demonstrated that six distinct classes of AGE structures, only AGEs-1 to -3 were specific bound to RAGE, and that AGE-2 and -3 had higher binding activity than AGE-1 [42].

Ongoing immunohistochemical studies show that AGE-2 also exists in AD brains (submitted data). The localization of AGE-2 was mainly in the perikarya of neurons and the staining pattern was powdery, differing from the dot-like pattern of AGE-1 staining. On the other hand, astrocytes stained weakly with anti AGE-2 antibody when compared to anti AGE-1 antibody. In AD brains, many senile plaques were detected by Ab immunostaining. The AGE-1 antibody also reacted with the senile plaques, mainly the amyloid core [3], but the AGE-2 antibody showed no immunoreactivity with the plaques (submitted data). AGE-1 was present at both intracellular and extracellular sites, while AGE-2 was only detected intracellularly. Protein cross-linking by AGE structures results in the formation of protease-resistant aggregates. Such protein aggregates may interfere with both axonal transport and intracellular protein traffic in neuron.

Neurotoxicity of glyceraldehyde-derived AGEs (AGE-2) in cortical neuronal cell

Recent in vitro studies also support the role of glycation in neuronal cell death [43-45].

vascular wall cells, mesangial cells and cortical neurons [48, 49, 45]. These results suggest a causal role for these types of AGEs in the pathogenesis of diabetic complication and neurodegenerative disease in vivo.

In a prior study, we provided direct immunochemical evidence for the existence of six distinct AGE structures within the AGE-modified proteins and peptides that circulate in the serum of diabetic patients on hemodialysis [27-30]. Incubation of cortical neurons with six immunochemically distinct AGEs, designated AGEs-1 to -6, produced a dose-dependent increase in neuronal cell-death (Figs. 2a & b) [29, 45]. The structural epitope designated AGE-2 was found to have the greatest cytopathic effect and the neurotoxicity of AGE-2 was neutralized by the addition of an anti-AGE-2 specific antibody. Distinct classes of AGE structures also have been established to circulate in the blood of individuals with diabetes mellitus and end-stage renal disease treated by hemodialysis (DM-HD). We fractionated serum from normal control and DM-HD patients by gel filtration and identified two fractions that contained AGE epitopes-1 to -6 [45]. The addition of these two fractions led to the death of cultured neuronal cells and this cytotoxic effect was completely prevented by the addition of the anti-AGE-2 specific antibody, but not by other types of anti-AGE antibodies (Figs. 2c & d) [45]. These results indicate that of the various types of AGE structures that can form in vivo, the AGE-2 structure is likely to play an important role in the pathophysiological processes associated with AGE formation. While the precise structure of AGE-2 remains to be determined, our best evidence to date is that AGE-2 forms by the rearrangement of glyceraldehyde addition products [28].

Relationship between glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and neuronal cell death

The enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is of particular interest because it has been reported to interact strongly with proteins implicated in the pathogenesis of AD [50], Huntington's disease [51], and spinocerebellar ataxia [52]. Recently, Saunders et al. [53] reported that GAPDH activity was decreased by 25 % in cultured cerebellar granule cells after 16 h of 300 mM cytosine b-D-arabinofuranoside (AraC) exposure. Accumulating evidence also suggests that the multi-functional GAPDH protein is involved in apoptosis [53-56]. In our experiments [45], the addition of AGE-2, either synthesized or prepared from DM-HD serum, resulted in a significant decrease in GAPDH activity (25-30 % of control BSA or normal control serum), but no change in CPP32/caspase-3 activity. This decrease in GAPDH activity was prevented by the immunoneutralization of AGE-2. These data suggest that an AGE-2 induced decrease in GAPDH function may contribute importantly to the neurotoxicity of AGE-modified proteins.

Ishitani et al. reported that GAPDH may have an important role in neuronal apoptosis as a “killing protein” [54], based on the overexpression of GAPDH in neurons during the apoptotic process. However, Mazzola et al. reported that GAPDH activity showed a 27% decrease in AD fiblobrasts compared with control cells despite the overexpression of GAPDH, which they explained as occurring in compensation on for the decrease of GAPDH activity [57].

Routes for AGE-2 production

Together with the decline of GAPDH activity, the metabolism of glyceraldehyde-3-phosphate decreases and glyceraldehyde-3-phosphate accumulates intracellularly. Glyceraldehyde-3-phosphate metabolism shifts to another route and the amount of glyceraldehyde is increased, which leads to an increase in the formation of AGE-2. The toxicity of AGE-2 for cultured neurons is strong and it promotes a marked increase of apoptosis. Accordingly, the perikaryal AGE-2 immunopositivity of neurons in our unpublished study probably reflects an increase of AGE-2 in the cytoplasm along with the decline of GAPDH activity.

The energy supply for neurons in the brain is generated from glucose via the glycolytic pathway. As shown in Fig. (3), glyceraldehyde-3-phosphate is an intermediate of this pathway that undergoes enzymatic reduction by GAPDH and eventually forms pyruvate. Some glyceraldehyde-3-phosphate is also transformed to glyceraldehyde, which reacts non-enzymatically with proteins to create AGE-2. It is known that this glycolytic process goes in cytoplasma.

Glucose can be reduced to sorbitol by the action of aldose reductase (AR). Sorbitol is further oxidized by sorbitol dehydrogenase (SDH) to fructose (Fig. 3). Since aldose reductase has high Km for glucose, the pathway is not very active at normal glucose levels. In hyperglycemia, however, glucose levels in insulin-independent tissues, such as brain and nerve tissue, kidney, lens, and the red blood cells, increase and consequently there is an increase in the activity of the polyol pathway [58].

Another common sugar in the diet is fructose, which is a component of the sucrose, table sugar. Fructose may be metabolized by two pathways in cells. It may be phosphorylated by hexokinase, an enzyme that is present in all cells; however, hexokinase has a strong preference for glucose, and glucose, which is present at about 5 mM concentration in blood, is a strong competitive inhibitor of the phosphorylation of fructose. The other pathway of fructose metabolism involves fructokinase and is especially important in liver after a meal. In liver, fructose is phosphorylated to fructose-1-phosphate (F-1-P) by a specific kinase, and the liver aldolase, called aldolase B, can cleave F-1-P, as well as fructose-1,6-bisphosphate (F-1,6-BP), alternatively, muscle aldolase, called aldolase A, is specific for F-1,6-BP. In this case, the products are dihydroxyacetone phosphate and glyceraldehyde (not glyceraldehyde-3-phosphate), (Fig. 3) [59].

Glyceraldehyde can be transported or can leak passively across the plasma membrane. It can react non-enzymatically with proteins to lead to accelerated formation of AGE-2 at both intracellular and extracellular region.

Conclusions

In this review, we provide an outline of AGEs formation in vivo and we discuss evidence for the toxicity of a specific AGE structure, defined as AGE-2, on cortical neurons. We propose the structural epitope AGE-2 is an important toxic moiety for neuronal cells in AD.

Note

Recently, four reviews were published concerning general glycation in AD [60-63].

Acknowledgement

This work was supported in part by grants from Japan Society for the Promotion of Science (Grant-in-Aid for Scientific Research (B), #13470197) to M.T.; Venture Research and Development Center of the Ministry of Education, Culture, Sports, Science and Technology to S.Y.; and the Specific Research Fund of Hokuriku University to M.T.

REFERENCES

[1]                   Selkoe DG. Normal and abnormal biology of the β-amyloid precursor protein. Ann Rev Neurosci 17: 489-517 (1994).

[2]                   Smith MA, Taneda S, Richey PL, Miyata T, Yan SD, Stern D et al. Advanced Maillard reaction end products are associated with Alzheimer disease pathology. Proc Natl Acad Sci USA 91: 5710-5714 (1994).

[3]                   Sasaki N, Fukatsu R, Tsuzuki K, Hayashi Y, Yoshida T, Fujii N et al. Advanced glycation end products in Alzheimer's disease and other neurodegenerative diseases. Am J Pathol 153: 1149-1155 (1998).

[4]                   Vitek MP, Bhattacharya K, Glendening JM, Stopa E, Vlassara H, Bucala R et al. Advanced glycation end products contribute to amyloidosis in Alzheimer disease. Proc Natl Acad Sci USA 91: 4766-4770 (1994).

[5]                   Ledesma MD, Bonary P, Colaco C and Avila J. Analysis of microtuble-associated protein tau glycation in paired helical filaments. J Biol Chem 269: 21614-21619 (1994).

[6]                   Yan SD, Chen X, Schmidt AM, Brett J, Godman G, Zou YS et al. Glycated tau protein in Alzheimer disease: a mechanism for induction of oxidant stress. Proc Natl Acad Sci USA 91: 7787-7791 (1994).

[7]                   Bucala R and Cerami A. Advanced glycosylation: chemistry, biology, and implications for diabetes and aging. Adv Pharmacol 23: 1-34 (1992).

[8]                   Vlassara H, Bucala R and Striker L. Pathogenic effects of advanced glycosylation: biochemical, biologic, and clinical implications for diabetes and aging. Lab Invest 70: 138-151 (1994).

[9]                   Brownlee M. Advanced protein glycosylation in diabetes and aging. Ann Rev Med 46: 223-234 (1995).

[10]              Vlassara H and Palace MR. Diabetes and advanced glycation endproducts. J Int Med 251: 87-101 (2002).

[11]              Sasaki N, Toki S, Choei H, Saito T, Nakano N, Hayashi Y et al. Immunohistochemical distribution of the receptor for advanced glycation end products in neurons and astrocytes in Alzheimer’s disease. Brain Res 888: 256-262 (2001).

[12]              Castellani R, Smith MA, Richey PJ and Petty G. Glycoxidation and oxidative stress in Parkinson disease and diffuse Lewy body disease. Brain Res 737: 195-200 (1996).

[13]              Sasaki N, Takeuchi M, Choei H, Kikuchi S, Hayashi Y, Nakano N et al. Advanced glycation end products (AGE) and their receptor (RAGE) in the brain of patients with Creutzfeldt-Jakob disease with prion plaques. Neurosci Lett 326: 117-120 (2002).

[14]              Kikuchi S, Shinpo K, Ogata A, Tsuji S, Takeuchi M, Makita Z et al. Detection of N-(carboxymethyl)lysine (CML) and non-CML advanced glycation end products in the anterior horn of amyotrophic lateral sclerosis spinal cord. Amyotroph Lateral Scler Other Motor Neuron Disord 3: 63-68 (2002).

[15]              Chou SM, Wang HS, Taniguchi A and Bucala R. Advanced glycation end products in neurofilament conglomeration of motoneurons in familial and sporadic amyotrophic lateral sclerosis. Mol Med 4: 324-332 (1998).

[16]              Vlassara H, Brownlee M and Cerami A. Accumulation of diabetic rat peripheral nerve myelin by macrophages increases with the presence of advanced glycosylation endproducts. J Exp Med 160: 197-207 (1984).

[17]              Maillard LC. Actions des acides amines sur les sucres: formation des melanoidines par voie Methodique. C R Acad Sci 154: 66-68 (1912).

[18]              Reynolds TM. Chemistry of nonenzymatic browning. Adv Food Res 14: 167-283 (1965).

[19]              Njoroge FG and Monnier VM. The chemistry of the Maillard reaction under physiological conditions: a review. Prog Clin Biol Res 304: 85-107 (1989).

[20]              Reddy S, Bichler J, Wells-Knecht KJ, Thorpe SR and Baynes JW. N epsilon-(carboxymethyl)lysine is a dominant advanced glycation end product (AGE) antigen in tissue proteins. Biochemistry 34: 10872-10878 (1995).

[21]              Baynes JW and Thorpe SR. Role of oxidative stress in diabetic complications-a new perspective on a old paradigm. Diabetes 48: 1-7 (1999).

[22]              Glomb MA and Monnier VM. Mechanism of protein modification by glyoxal and glycolaldehyde, reactive intermediates of the Maillard reaction. J Biol Chem 70: 10017-10026 (1995).

[23]              Al-Abed Y, Kapurniotu A and Bucala R. Advanced glycation end products; detection and reversal. Methods Enzymol 309: 152-171 (1999).

[24]              Wells-Knecht KJ, Zyzak DV, Litchfield SR, Thorpe SR and Baynes JW. Mechanism of autoxidative glycosylation: identification of glyoxal and arabinose as intermediates in the autoxidative modification of proteins by glucose. Biochemistry 34: 3702-3709 (1995).

[25]              Thornalley PJ. Pharmacology of methylglyoxalase: formation, modification of proteins and nucleic acids, and enzymatic detoxification-a role in pathogenesis and antiproliferative chemotherapy. Gen Pharmacol 27: 565-573 (1996).

[26]              Thornalley PJ, Langborg A and Minhas HS. Formation of glyoxal, methylglyoxal and 3-deoxyglucosone in the glycation of proteins by glucose. Biochem J 344: 109-116 (1999).

[27]              Takeuchi M, Makita Z, Yanagisawa K, Kameda Y and Koike T. Detection of noncarboxymethyllysine and carboxymethyllysine advanced glycation end products (AGE) in serum of diabetic patients. Mol Med 5: 393-405 (1999).

[28]              Takeuchi M, Makita Z, Bucala R, Suzuki T, Koike T and Kameda Y. Immunological evidence that non-carboxymethyllysine advanced glycation end-products are produced from short chain sugars and dicarbonyl compounds in vivo. Mol Med 6: 114-125 (2000).

[29]              Takeuchi M, Yanase Y, Matsuura N, Yamagishi S, Kameda Y, Bucala R et al. Immunological detection of a novel advanced glycation end-product. Mol Med 7: 783-791 (2001).

[30]              Takeuchi M and Makita Z. Alternative routes for the formation of immunochemically distinct advanced glycation end-products in vivo. Curr Mol Med 1: 305-315 (2001).

[31]              Munch G, Schinzel R, Loske C, Wong A, Durany N, Li JJ et al. Alzheimer's disease-synergistic effects of glucose deficit, oxidative stress and advanced glycation endproducts. J Neural Transm 105: 439-461 (1998).

[32]              Yan SD, Chen X, Fu J, Zhu H, Roher A, Slattery T et al. RAGE and amyloid-beta peptide neurotoxicity in Alzheimer's disease. Nature 382: 685-691 (1996).

[33]              Ott A, Stolk RP, Harskamp F, Pols HAP, Hofman A and Breteler MMB. Diabetes mellitus and the risk of dementia-the Rotterdam study. Neurology 53: 1937-1942 (1999).

[34]              Makita Z, Bucala R, Rayfield EJ, Friedman EA, Kaufman AM, Korbet SM et al. Reactive glycosylation endproducts in diabetic uremia and treatment of renal failure. Lancet 343: 1519-1522 (1994).

[35]              Harrington CR, Wischik CM, McArthur FK, Taylor GA, Edwardson JA and Candy JM. Alzheimer's-disease-like changes in tau protein processing: association with aluminium accumulation in brains of renal dialysis patients. Lancet 343: 993-997 (1994).

[36]              Riviere S, Birlouez-Aragon I and Vellas B. Plasma protein glycation in Alzheimer's disease. Glycoconj J 15: 1039-1042 (1998).

[37]              Shuvaev V, Laffont I, Serot JM, Fujii J, Taniguchi N and Siest G. Increased protein glycation in cerebrospinal fluid of Alzheimer's disease. Neurobiol Aging 22: 397-402 (2001).

[38]              Yan SD, Yan SF, Chen X, Fu J, Chen M, Kuppusamy P et al. Non-enzymatically glycated tau in Alzheimer's disease induces neuronal oxidant stress resulting in cytokine gene expression and release of amyloid b-peptide. Nat Med 1: 693-699 (1995).

[39]              Schmidt AM, Yan SD, Yan SF and Stern D. The biology of the receptor for advanced glycation end products and its ligands. Biochim Biophys Acta-Mol Cell Res 1498: 99-111 (2000).

[40]              Bucciarelli LG, Wendt T, Rong L, Lalla E, Hofmann MA, Goova MT et al. RAGE is a multiligand receptor of the immunoglobulin superfamily: implications for homeostasis and chronic disease. Cell Mol Life Sci 59: 1117-1128 (2002).

[41]              Yan SD, Roher A, Chaney M, Zlokovic B, Schmidt AM and Stern D. Cellular cofactors potentiating induction of stress and cytotoxicity by amyloid bete-peptide. Biochim Biophys Acta-Mol Basis Dis 1502: 145-157 (2000).

[42]              Yonekura H, Yamamoto Y, Sakurai S, Yasui K, Petrova RG, Abedin MJ et al. RAGE engagement and vascular cell derangement by short chain sugar-derived advanced glycation end products. In ‘International Congress Series’. Elservier Scince B V, p.129-135 (2002).

[43]              Loske C, Neumann A, Cunningham AM, Nichol K, Schinzel R, Riederer P et al. Cytotoxicity of advanced glycation endproducts is mediated by oxidative stress. J Neural Transm 105: 1005-1015 (1998).

[44]              Kikuchi S, Shinpo K, Moriwaka F, Makita Z, Miyata T and Tashiro K. Neurotoxicity of methylglyoxal and 3-deoxyglucosone on cultured cortical neurons: synergism between glycation and oxidative stress, possibly involved in neurodegenerative diseases. J Neurosci Res 57: 280-289 (1999).