Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitric oxide (NO) is important in the regulation of renal tubular function. We have investigated whether glycated proteins could impair the NO production by examining the effects of Amadori products (AP-BSA) and advanced glycation end products (AGE-BSA) on primary cultures of rabbit proximal tubular epithelial (PTE) cells. Nitric oxide synthase activity was assessed by measurement of the conversion of L-arginine to L-citrulline and by production of NO, after short-term (30 min) or long-term (1 or 3 days) incubation. Short incubations of PTE cells with either 200 microg/ml AP-BSA or 40 microg/ml AGE-BSA significantly decreased NO production. AP-BSA (3000 microg/ml) inhibited the Ca(2+)-dependent NOS activity even though above 50 microg/ml it increased Ca(2+)-independent NOS activity. In contrast, 40 microg/ml AGE-BSA inhibited both isoforms of NOS. Longer incubations with 200 microg/ml AP-BSA or 250 microg/ml AGE-BSA decreased NO release and inhibited Ca(2+)-dependent and -independent NOS activities. APs did not affect NO release by S-nitroso-N-acetyl-penicillamine (SNAP), while 250 microg/ml AGEs decreased it. After 3 days incubation, glycation products had no effect on the NOS cell content. Cell viability and proliferation were not modified under these experimental conditions, suggesting that the fall in NO production was not due to there being fewer cells. These data indicate that APs and AGEs directly inhibit NOS activity, and additionally that AGEs quench released NO. Thus, both types of glycated proteins alter the production of NO by PTE cells and could participate in the renal tubule dysfunction associated with aging and diabetes.
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PMID:Inhibition of nitric oxide synthase activity by early and advanced glycation end products in cultured rabbit proximal tubular epithelial cells. 1106 90

Methylglyoxal (MG), an alpha-dicarbonyl compound, can be produced in vivo by several metabolic pathways and the Maillard reaction. It reacts rapidly with proteins to form advanced glycation end products or AGEs. We previously isolated and characterized a blue fluorescent product of the reaction between MG and arginine, which we named argpyrimidine. We found that argpyrimidine was stable to acid hydrolysis, which allowed us to hydrolyze tissue proteins with 6 N HCl and quantify argpyrimidine by high-performance liquid chromatography. Here we report argpyrimidine concentrations in human lens and serum proteins as determined by HPLC. We have also measured pentosidine, a fluorescent AGE derived from pentose sugars, and compared the concentrations of pentosidine and argpyrimidine. We found two- to threefold higher argpyrimidine concentrations in diabetic serum proteins than in nondiabetic controls (9.3 +/- 6.7 vs 4.4 +/- 3.4 pmol/mg). We found a significant correlation (P = 0.0001) between serum protein argpyrimidine and glycosylated hemoglobin. Argpyrimidine concentrations were approximately seven times greater in brunescent cataractous lenses than in aged noncataractous lenses. Pentosidine concentrations in serum and lens proteins were much lower than argpyrimidine concentrations; in general, argpyrimidine levels were 10--25 times higher than pentosidine. Results from our study confirm that MG-mediated arginine modifications occur in vivo and provide a method for assessing protein-arginine modification by MG in aging and diabetes.
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PMID:Chromatographic quantification of argpyrimidine, a methylglyoxal-derived product in tissue proteins: comparison with pentosidine. 1123 39

Engagement of the receptor for advanced glycation end products (RAGE) by products of nonenzymatic glycation/oxidation triggers the generation of reactive oxygen species (ROS), thereby altering gene expression. Because dissection of the precise events by which ROS are generated via RAGE is relevant to the pathogenesis of complications in AGE-related disorders, such as diabetes and renal failure, we tested the hypothesis that activation of NADPH oxidase contributed, at least in part, to enhancing oxidant stress via RAGE. Here we show that incubation of human endothelial cells with AGEs on the surface of diabetic red blood cells, or specific AGEs, (carboxymethyl)lysine (CML)-modified adducts, prompted intracellular generation of hydrogen peroxide, cell surface expression of vascular cell adhesion molecule-1, and generation of tissue factor in a manner suppressed by treatment with diphenyliodonium, but not by inhibitors of nitric oxide. Consistent with an important role for NADPH oxidase, although macrophages derived from wild-type mice expressed enhanced levels of tissue factor upon stimulation with AGE, macrophages derived from mice deficient in a central subunit of NADPH oxidase, gp91phox, failed to display enhanced tissue factor in the presence of AGE. These findings underscore a central role of NADPH oxidase in AGE-RAGE-mediated generation of ROS and provide a mechanism for altered gene expression in AGE-related disorders.
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PMID:Activation of NADPH oxidase by AGE links oxidant stress to altered gene expression via RAGE. 1128 50

Vascular complications arising from multiple environmental and genetic factors are responsible for many of the disabilities and short life expectancy associated with diabetes mellitus. Here we provide the first direct in vivo evidence that interactions between advanced glycation end products (AGEs; nonenzymatically glycosylated protein derivatives formed during prolonged hyperglycemic exposure) and their receptor, RAGE, lead to diabetic vascular derangement. We created transgenic mice that overexpress human RAGE in vascular cells and crossbred them with another transgenic line that develops insulin-dependent diabetes shortly after birth. The resultant double transgenic mice exhibited increased hemoglobin A(1c) and serum AGE levels, as did the diabetic controls. The double transgenic mice demonstrated enlargement of the kidney, glomerular hypertrophy, increased albuminuria, mesangial expansion, advanced glomerulosclerosis, and increased serum creatinine compared with diabetic littermates lacking the RAGE transgene. To our knowledge, the development of this double transgenic mouse provides the first animal model that exhibits the renal changes seen in humans. Furthermore, the phenotypes of advanced diabetic nephropathy were prevented by administering an AGE inhibitor, (+/-)-2-isopropylidenehydrazono-4-oxo-thiazolidin-5-ylacetanilide (OPB-9195), thus establishing the AGE-RAGE system as a promising target for overcoming this aspect of diabetic pathogenesis.
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PMID:Development and prevention of advanced diabetic nephropathy in RAGE-overexpressing mice. 1145 79

The excess of glucose appears to play an important and specific role in the genesis of macroangiopathy in diabetics. Activation of protein kinase-C, the sorbitol pathway, and AGE formation are thought to be the major pathways linking the degree of glycaemic compensation with the pathogenetic process of macrovascular disease. HSPG is likely to be a key element in this process since it is a regulator of endothelial permeability, vascular antithrombotic capacity, insulin sensitivity (with respect to lipoprotein lipase availability), and vascular extracellular matrix content and smooth-muscle-cell activation. Loss of HSPG is suggested clinically by the presence of microalbuminuria, to the development of which diabetic control also contributes significantly. However, genetic factors also seem to be involved. Much more insight into the precise mechanismus is necessary to unravel the cellular and molecular chains of events for the premature and accelerated atherosclerosis in diabetic patients.
Exp Clin Endocrinol Diabetes 2001
PMID:The atherosclerotic process and its exacerbation by diabetes. 1146 May 93

Receptor for advanced glycation end-products (RAGE), and two of its ligands, AGE and EN-RAGEs (members of the S100/calgranulin family of pro-inflammatory cytokines), display enhanced expression in slowly resolving full-thickness excisional wounds developed in genetically diabetic db+/db+ mice. We tested the concept that blockade of RAGE, using soluble(s) RAGE, the extracellular ligand-binding domain of the receptor, would enhance wound closure in these animals. Administration of sRAGE accelerated the development of appropriately limited inflammatory cell infiltration and activation in wound foci. In parallel with accelerated wound closure at later times, blockade of RAGE suppressed levels of cytokines; tumor necrosis factor-alpha; interleukin-6; and matrix metalloproteinases-2, -3, and -9. In addition, generation of thick, well-vascularized granulation tissue was enhanced, in parallel with increased levels of platelet-derived growth factor-B and vascular endothelial growth factor. These findings identify a central role for RAGE in disordered wound healing associated with diabetes, and suggest that blockade of this receptor might represent a targeted strategy to restore effective wound repair in this disorder.
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PMID:Blockade of receptor for advanced glycation end-products restores effective wound healing in diabetic mice. 1148 96

RENAL TRANSPLANT OUTCOME: Analysis of 5-year transplant survival in the UK showed a number of significant factors influencing outcome of adult cadaveric renal transplantation. Data from 5,963 first grafts and 1,078 regrafts carried out between 1990-1997 showed year of graft, recipient age and diabetes, donor age, kidney exchange between centres and HLA matching to influence 5-year outcome. The most important prognostic factor was donor age: the risk of transplant failure within 5 years for grafts using kidneys from donors aged 60 years and over was double that of grafts using donors aged 18-34 years. Unlike the effect of donor age, the influence of HLA matching would appear to be diminishing with time. In contrast to transplants in the 1980's, the difference in 5-year transplant survival between 000 mismatched and favourably matched (100, 010 or 110 mismatched) transplants is no longer significant. An analysis of posttransplant survival for first grafts in different epochs (0-3 months, 3 months to 3 years and beyond 3 years) showed that one factor affected short-term outcome (exchange of kidneys between centres), whereas others affected outcome throughout the epochs (most notably donor age, recipient age and recipient diabetes). RECIPIENT AND DONOR AGE MATCHING: The mean recipient age in the UK and Republic of Ireland increased by 5 years between 1981-1990 but has remained at approximately 45 years since then. The mean donor age increased by 7 years to 42.5 years (s.e. 0.5) between 1981-1991 and since then has increased at a slower rate to 43.4 years (s.e. 0.5) in 1998. The mean donor-recipient age difference for more than 15,000 transplants carried out between 1990-1998 has decreased, primarily due to increasing donor age over this time. However, the introduction of a new Kidney Allocation Scheme in the UK in July 1998, part of which is aimed at minimising age differences, has increased the likelihood that recipients aged over 60 years will be allocated grafts from donors closer to their own age than previously. The new UK Kidney Allocation Scheme also gave children increased access to well-matched adult organs leading to an increased mean age difference for this group between July-December 1998. DONOR AND RECIPIENT HLA MATCHING: Modifications to the Kidney Allocation Scheme introduced in January 1997 with the aim of increasing the number of well-matched transplants has led to a rise in 000 mismatched grafts from 5% to 7% and favourably matched (100/010/110 mismatches) from 29% to 36% between 1990-1992 and 1996-1998. Over this same time the proportion of 2 DR-mismatched grafts has decreased from 10% to 4%. The revised Kidney Allocation Scheme implemented in July 1998 gave a further increase in priority to 000 mismatches, increasing the proportion of these transplants to 12% for the last half of 1998, a level which has been maintained since then.
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PMID:Renal transplantation in the UK and Republic of Ireland. 1151 4

In rats with streptozotocin (STZ) induced diabetes the effect of (watersoluble) thiamine nitrate and of (lipidsoluble) benfotiamine on peripheral nerve function (motor nerve conduction velocity) as well as on the formation of advanced glycation end-products in peripheral nerve tissue was studied. In one group of animals drug administration was started immediately after diabetes induction (prevention study) and in another group two months after diabetes induction (treatment study). Motor nerve conduction velocity (NCV) dropped by 10.5% in diabetic animals, carboxymethyl-lysine (CML) rose to a 3.5fold concentration, deoxyglucosone (3DG)-type AGE formation was increased 5.1fold compared with controls. After three months preventive administration of both vitamin B(1) preparations NCV had increased substantially compared with results in diabetic controls. It was nearly normal after six months with benfotiamine, while the administration of thiamine nitrate resulted in no further amelioration. NCV was nearly normalized after six months of benfotiamine application but not with thiamine. Furthermore, benfotiamine induced a major inhibition of neural imidazole-type AGE formation and completely prevented diabetes induced glycoxidation products (CML). Treatment with thiamine did not significantly affect AGE or cmL levels. Unlike treatment with water-soluble thiamine nitrate timely administration of liposoluble prodrug benfotiamine was effective in the prevention of functional damage and of AGE and cmL formation in nerves of diabetic rats.
Exp Clin Endocrinol Diabetes 2001
PMID:Efficacy of benfotiamine versus thiamine on function and glycation products of peripheral nerves in diabetic rats. 1157 71

Receptor for AGE (RAGE), a member of the immunoglobulin superfamily, was first identified as a specific cell surface interaction site for Advanced Glycation Endproducts, or AGEs. AGEs, the products of nonenzymatic glycation/oxidation of proteins/lipids, accumulate in natural aging and disorders such as diabetes, renal failure and amyloidoses. Interaction of AGEs with RAGE has been linked to chronic inflammatory and vascular dysfunction that characterizes the chronic complications of these disorders. Recent studies have indicated that RAGE is a multiligand receptor, serving as a specific cell surface, signal transducing receptor for amphoterin, a molecule with implications for neurite outgrowth in neuronal development and in tumor cell proliferation and spread. RAGE is also a receptor for amyloid-beta peptide, whose interaction with neuronal and microglial RAGE within the CNS is linked to sustained inflammation and neuronal toxicity and cell death. RAGE also serves as a signal-transducing receptor for EN-RAGEs, and related members of the S100/calgranulin family of proinflammatory cytokines; consequences of this interaction include initiation and propagation of inflammatory responses. Consistent with an important role for ligand-RAGE interaction in these settings, blockade of RAGE suppresses chronic cellular activation and dysfunction in murine models of diabetic complications, inflammation and tumor proliferation and metastasis. Taken together, an new paradigm is emerging which links RAGE, a gene encoded within the Major Histocompatibility Complex (MHC) Class III regions, to central host response mechanisms in homeostasis and chronic disease.
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PMID:Receptor for age (RAGE) is a gene within the major histocompatibility class III region: implications for host response mechanisms in homeostasis and chronic disease. 1157 72

RAGE (receptor for advanced glycation end products) is a multiligand cell surface molecule of the immunoglobulin superfamily. It was originally described as a receptor for protein adducts formed by glycoxidation (AGEs) that accumulate in diseases such as diabetes and renal failure. Performing RT-PCR and Western blot analysis we intended to determine RAGE expression in the human colon adenocarcinoma cell line Caco-2. Moreover, Caco-2 cells were incubated in the presence of AGEs. Since RAGE ligation triggers the p21(ras) signal transduction pathway the activation state of p44/42 (ERK1/2) MAP kinases was determined. Here we demonstrate for the first time that Caco-2 cells express RAGE and that administration of the food-derived casein-linked AGE N(epsilon)-(carboxymethyl)lysine (Cas-CML) results in Caco-2 p44/42 (ERK1/2) MAP kinase activation.
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PMID:RAGE expression and AGE-induced MAP kinase activation in Caco-2 cells. 1170 25


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