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)

Prolonged hyperglycemia, dyslipidemia and oxidative stress in diabetes result in the production and accumulation of AGEs. It is now clear that AGEs contribute to the development and progression of cardiovascular disease in diabetes, as well as other complications. AGEs are thought to act through receptor-independent and dependent mechanisms to promote vascular damage, fibrosis and inflammation associated with accelerated atherogenesis. As a result, novel therapeutic agents to reduce the accumulation of AGEs in diabetes have gained interest as potential cardioprotective approaches. A variety of agents have been developed which are examined in detail in this review. These include aminoguanidine, ALT-946, pyridoxamine, benfotiamine, OPB-9195, alagebrium chloride, N-phenacylthiazolium bromide and LR-90. In addition, it has been demonstrated that a number of established therapies have the ability to reduce the accumulation of AGEs in diabetes including ACE inhibitors, angiotensin receptor antagonists, metformin, peroxisome proliferators receptor agonists, metal chelators and some antioxidants. The fact that many of these inhibitors of AGEs are effective in experimental models, despite their disparate mechanisms of action, supports the keystone role of AGEs in diabetic vascular damage. Nonetheless, the clinical utility of AGE inhibition remains to be firmly established. Optimal metabolic and blood pressure control, that is achieved early and sustained indefinitely, remains the best recourse for inhibition of AGEs until more specific interventions become a clinical reality.
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PMID:The role of AGEs and AGE inhibitors in diabetic cardiovascular disease. 1602 65

This review addresses the recent litterature devoted to the risk of severe infections in patients with diabetes and to the potential influence of diabetes on the function of natural immunity. Although much controversy still exists regarding the incidence of infections in diabetic patients, several studies confirm that diabetes mellitus is associated with an increased severity and mortality in community acquired pneumonia. Furthermore, the risk of severe bacteremia (especially associated with Streptococcus pneumoniae) is higher in diabetic patients. Polynuclear neutrophils are clearly influenced by the diabetic state. On the one hand, their antimicrobial function is inhibited by hyperglycaemia, due to inhibition of G6PD or diversion of NADPH in the polyol pathway; on the other hand, the AGE/RAGE/NF-kappaB pathway involved in the pathogenesis of chronic complications of diabetes could also amplify inflammatory systemic manifestations associated with infections and play a role in the higher mortality rate observed in diabetic subjects with severe infections. These observations argue for the systematic vaccination of all diabetic patients against influenza and Streptococcus pneumoniae, for the reappraisal of diabetes as a significant pejorative risk factor in community acquired pneumonia and for intensive insulin therapy in all diabetic patients with severe infection.
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PMID:[Alterations in natural immunity and risk of infection in patients with diabetes mellitus]. 1603 24

Glycated hemoglobins are minor components of human hemoglobin (Hb). These are formed nonenzymatically by condensation of glucose or other reducing sugars with alpha- and beta-chains of hemoglobin A. The subfraction HbA1c, a nonenzymatic glycation at the amino-terminal valines of the beta-chain, was identified by the author in the 1960s as a minor "abnormal fast-moving hemoglobin band" in diabetic patients during routine screening for hemoglobin variants. This finding later turned out to be an important biomolecular marker with clinical and pathological applications. Measurement of HbA1c in diabetic patients is an established procedure for evaluating long-term control of diabetes, and the introduction of this measurement represents an outstanding contribution to the quality of care of diabetic patients in this century. More importantly, HbA1c is the first example of in vivo nonenzymatic glycation of proteins, and its discovery opened new and still-growing avenues of research on Maillard reactions in biological systems, including the concept of advanced glycation/lipoxidation end products (AGEs/ALEs) and the development of diabetic complications and various diseases associated with aging. Although interest in the Maillard reaction is growing rapidly, much remains to be done in this field, including detection and characterization of all in vivo AGEs/ALEs, development and clinical applications of AGE inhibitors and breakers, as well as investigations into the possible roles of the Maillard reaction in regulatory biology and carcinogenesis.
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PMID:The discovery of glycated hemoglobin: a major event in the study of nonenzymatic chemistry in biological systems. 1603 17

Advanced glycation end products/peptides (AGE/peptides) originate by in vivo enzymatic digestion of nonenzymatically glycated proteins, which are produced by reaction of glucose with primary amino groups present in the protein chain following the Maillard pattern. AGE/peptides are highly reactive species and can interact with tissue and circulating proteins, leading to tissue modification and impaired protein functionality. Serum levels of AGE/peptides are reported to be particularly high in diabetes (in terms of higher production) or in end-stage renal disease (in terms of accumulation). For these reasons, their structural identification is of high interest, giving information on their relationship with the pathological state and allowing the design of possible therapeutic interventions. We report here some preliminary results obtained by liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) and matrix-assisted laser desorption ionization MS (MALDI-MS) investigations carried out on the low-molecular-weight serum peptide fraction from 10 healthy subjects, 10 patients with poorly controlled diabetes, and 10 patients with end-stage nephropathy.
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PMID:Advanced glycation end products/peptides: an in vivo investigation. 1603 47

It is believed that intracellular and extracellular advanced glycation (AGEs) or lipoxidation end products (ALEs), together with dysregulated glucose and lipid metabolism, are important contributors to oxidant or carbonyl stress, enhanced cellular redox-sensitive transcription factor activity, and impaired innate immune defense, causing over time inappropriate inflammatory responses. However, neither the magnitude nor the persistent nature of this increased prooxidant state are completely understood. A significant correlation has been found between ingested and circulating AGEs in humans in recent years. Based on animal studies, the injurious impact of diet-derived AGEs to vascular and kidney tissues is estimated to rival or even exceed that caused by hyperglycemia or hyperlipidemia. Consistent with this view, dietary AGE restriction has been associated with suppression of several immune defects, insulin resistance, and diabetic complications, whether genetically or diet induced, despite persistent diabetes. These findings are in support of clinical evidence from subjects with diabetes or vascular or kidney disease. Most recently, evidence from animal studies points to AGE restriction as an effective means for extending median life span, similar to that previously shown by marked caloric restriction. We conclude that excessive AGE consumption, in the current dietary/social structure, represents an independent factor for inappropriate oxidant stress responses, which may promote the premature expression of complex diseases associated with adult life, such as diabetes and cardiovascular disease.
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PMID:Advanced glycation in health and disease: role of the modern environment. 1603 66

ERM proteins (ezrin, radixin, and moesin) have recently been identified as a new class of AGE-binding proteins. ERM proteins link the plasma membrane with the actin cytoskeleton and regulate cell shape, motility, adhesion, and signal transduction. ERM proteins have three structural domains: the N-terminal domain, a coiled midregion, and the C-terminal domain. The N-terminal domain binds to a number of plasma membrane ligands and is involved in signal transduction, while the C-domain binds to actin filaments. Binding studies with isolated structural domains showed that glycated proteins bind to an epitope within the N-terminal domain of ezrin (aa 1-324). It is postulated that some of the cellular effects of AGEs leading to diabetic complications may be mediated by binding to this region of ezrin, thereby interrupting the cross-linking between the plasma membrane and actin cytoskeleton and downstream signaling pathways. Indeed, changes in actin arrangement, cell shape, and adhesion have been described in diabetes, and AGE-BSA inhibits ezrin-dependent tubulogenesis of LLC-PK1 proximal tubular cells. For future development of antagonists, further identification of the ezrin-binding epitope for glycated proteins is required.
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PMID:Localization of the ezrin binding epitope for glycated proteins. 1603 85

The accelerated formation of advanced glycation/lipoxidation end products (AGEs/ALEs) has been implicated in the pathogenesis of various diabetic complications. Several natural and synthetic compounds have been proposed and advanced as inhibitors of AGE/ALE formation. We examined the effects of two new AGE/ALE inhibitors, LR-9 and LR-74, on the prevention of early renal disease and dyslipidemia in streptozotocin (STZ)-induced diabetic rats. Diabetic rats were treated with either LR-9 or LR-74 for 32 weeks. Progression of renal disease was evaluated by measurements of urinary albumin and plasma creatinine concentrations. AGE-induced chemical modification of the tail tendon collagen and levels of Nepsilon-(carboxymethyl)- and (carboxyethyl)- lysines (CML and CEL) in skin collagen were measured. AGE/ALE levels in kidneys were determined by immunohistochemistry. Plasma lipids and their lipid hydroperoxide concentrations were also determined. Treatment of either LR-9 or LR-74 significantly inhibited the increase in albuminuria, plasma creatinine, hyperlipidemia, and plasma lipid peroxidation in diabetic rats without any effects on hyperglycemia. Both compounds also reduced CML-AGE accumulation in kidney glomeruli and tubules, AGE-linked fluorescence and cross-linking of tail collagen, and levels of CML and CEL in skin collagen. These results suggest that both LR compounds can inhibit the progression of renal disease and also prevent dyslipidemia in experimental diabetes. These compounds may have an additional beneficial effect as an antioxidant against lipid peroxidation, and thus may provide alternative therapeutic options for the treatment of various diabetic macrovascular complications.
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PMID:Renoprotective and lipid-lowering effects of LR compounds, novel advanced glycation end product inhibitors, in streptozotocin-induced diabetic rats. 1603 4

Advanced glycation and lipoxidation end products (AGEs/ALEs) have been implicated in the pathogenesis of the major microvascular complications of diabetes mellitus: nephropathy, neuropathy, and retinopathy. This article reviews the evidence regarding the peripheral nerve and its vascular supply. Most investigations done to assess the role of AGEs/ALEs in animal models of diabetic neuropathy have used aminoguanidine as a prototypic inhibitor. Preventive or intervention experiments have shown treatment benefits for motor and sensory nerve conduction velocity, autonomic nitrergic neurotransmission, nerve morphometry, and nerve blood flow. The latter depends on improvements in nitric oxide-mediated endothelium-dependent vasodilation and is responsible for conduction velocity improvements. A mechanistic interpretation of aminoguanidine's action in terms of AGE/ALE inhibition is made problematic by the relative lack of specificity. However, other unrelated compounds, such as pyridoxamine and pyridoxamine analogues, have recently been shown to have beneficial effects similar to aminoguanidine, as well as to improve pain-related measures of thermal hyperalgesia and tactile allodynia. These data also stress the importance of redox metal ion-catalyzed AGE/ALE formation. A further approach is to decrease substrate availability by reducing the elevated levels of hexose and triose phosphates found in diabetes. Benfotiamine is a transketolase activator that directs these substrates to the pentose phosphate pathway, thus reducing tissue AGEs. A similar spectrum of improvements in nerve and vascular function were noted when using benfotiamine in diabetic rats. Taken together, the data provide strong support for an important role for AGEs/ALEs in the etiology of diabetic neuropathy.
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PMID:Inhibitors of advanced glycation end product formation and neurovascular dysfunction in experimental diabetes. 1603 6

Several diseases (atherosclerosis, diabetes mellitus, chronic renal failure) are associated with oxidative and carbonyl stress, microinflammation and eventually autoimmune reaction. Both oxidative and carbonyl stress cause damage to important biological structures-proteins, carbohydrates, lipids and nucleic acids and may enhance inflammatory response. New compounds and modified structures are formed, among them advanced oxidation protein products (AOPP), advanced glycation end products (AGEs-e.g. pentosidine, carboxymethyllysine) and advanced lipoperoxidation end products (ALEs). Accumulation of glycoxidation products, upregulation of protective mechanisms like glyoxalase I as well as enhanced transcription of genes coding for cytokines, growth factors and adhesive molecules via AGE-RAGE (receptor for AGEs) interaction and subsequent increase of classical acute phase reactants (e.g. CRP-C-reactive protein or orosomucoid) can be observed in a variety of chronic diseases. Additionally, several RAGE gene polymorphisms have shown association with some pathological states-diabetic complications, vascular damage, inflammatory response or antioxidant status. Recent advances in understanding the pathogenesis of chronic diseases provide new possibilities for diagnostics and monitoring of severely ill patients, however, further studies are still required to establish efficient therapeutical strategies.
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PMID:Advanced glycoxidation end products in chronic diseases-clinical chemistry and genetic background. 1608 33

Glycation is common posttranslational modification of proteins impairing their function, which occurs during diabetes mellitus and aging. Beside extracellular glycation of long-lived proteins, intracellular modifications of short-lived proteins by more reactive sugars like fructose are possible. The process includes free oxygen radicals (glycoxidation). In an attempt to reduce glycoxidation and formation of advanced glycation products (AGE), influence of 0.2-1.2 mM uric acid as endogenous antioxidant on glycoxidation of purified pig heart aspartate aminotransferase (AST) by 50 mM and 500 mM D-fructose in vitro was studied. Uric acid at 1.2 mM concentration reduced AST activity decrease and formation of total AGE products caused by incubation in vitro of the enzyme with sugar up to 25 days at 37 degrees C. The results thus support the hypothesis that uric acid has beneficial effects in controlling protein glycoxidation. The in vitro system AST-fructose proved to be a useful tool for investigation of glycation process.
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PMID:Glycation-induced inactivation of aspartate aminotransferase, effect of uric acid. 1618 93


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