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

Plasma activity of the enzyme semicarbazide-sensitive amine oxidase (SSAO) is high in diabetes. Production of angiotoxic substances (an aldehyde, hydrogen peroxide, and ammonia) in vessel walls is catalysed by SSAO, suggesting a role for SSAO in the development of complications of diabetes. The objective of the present study was to follow up plasma SSAO activity (measured radiometrically), HbA(1c) (using ion exchange chromatography), and retinopathy (by fundus photography) after 2.8 years, in 34 patients with Type 2 diabetes. We also measured urinary levels of an SSAO substrate, methylamine, by fluorometric high-performance liquid chromatography (HPLC). As at baseline, plasma SSAO activity was now higher in subjects with retinopathy (mean 19.5) than in subjects without retinopathy (mean 16.0), 95% confidence interval (CI) for difference 0.6-6.3 nmol benzylamine ml(-1) plasma h(-1). SSAO activity had not changed significantly since baseline, mean difference -1.65 and 95% CI for difference -3.76 to 0.46 nmol benzylamine ml(-1) plasma h(-1). Mean HbA(1c) level remained higher for patients with retinopathy (now 7.9%) compared to those without retinopathy (6.1%), 95% CI for difference 0.6-3.0%. Comparing baseline and the present study, retinopathy was nonproliferative; level had worsened for five and improved for two patients. Urinary methylamine/creatinine ratio was lower in the group of patients with retinopathy (mean 0.99) than in those without retinopathy (mean 1.78), 95% CI for difference 0.1-1.5 microg mg(-1). The results of the present study are compatible with a role for SSAO in the development of diabetic retinopathy.
J Diabetes Complications
PMID:Follow-up of plasma semicarbazide-sensitive amine oxidase activity and retinopathy in Type 2 diabetes mellitus. 1152 99

Diabetes is a known risk factor of atherosclerosis, moderate consumption of alcohol was reported to reduce the cardiovascular morbidity and mortality. This review presents information on the possible mechanisms of the antiatherogenic effect of alcohol and data of the effect of moderate alcohol drinking on the prevention of cardiovascular diseases. Red wine contains polyphenols with an antioxidant effect, alcohol is metabolized to acetaldehyde which was proved to inhibit the formation of advanced glycation endproducts (AGE) and lipoprotein oxidation. Diabetic patients may benefit from moderate consumption of alcohol beverages only if the risk of hypoglycemia is safely excluded.
 ...
PMID:[Atherosclerosis, alcohol and diabetes]. 1213 55

Protein tyrosine phosphatases (PTPs) are a large family of enzymes that catalyze the hydrolytic removal of the phosphoryl group from phosphotyrosyl (pY) proteins. PTP inhibitors provide potential treatment of human diseases/conditions such as diabetes and obesity as well as useful tools for studying the function of PTPs in signaling pathways. In this work, we have shown that certain aryl-substituted aldehydes act as reversible, slow-binding inhibitors of modest potency against PTP1B, SHP-1, and a dual-specificity phosphatase, VHR. Attachment of the tripeptide Gly-Glu-Glu to the para position of cinnamaldehyde resulted in an inhibitor (Cinn-GEE) of substantially increased potency against all three enzymes (e.g., K(I) = 5.4 microM against PTP1B). The mechanism of inhibition was investigated using Cinn-GEE specifically labeled with (13)C at the aldehyde carbon and (1)H-(13)C heteronuclear single-quantum coherence spectroscopy. While Cinn-GEE alone showed a single cross-peak at delta 9.64 ((1)H) and delta 201 ((13)C), the PTP1B/Cinn-GEE complex showed three distinct cross-peaks at delta 7.6-7.8 ((1)H) and 130-137 ((13)C). Mutation of the catalytic cysteine (Cys-215 in PTP1B) into alanine had no effect on the cross-peaks, whereas mutation of a conserved active-site arginine (Arg-221 in PTP1B) to alanine abolished all three cross-peaks. Similar experiments with Cinn-GEE that had been labeled with (13)C at the benzylic position revealed a change in the hybridization state (from sp(2) to sp(3)) for the benzylic carbon as a result of binding to PTP1B. These results rule out the possibility of a free aldehyde, aldehyde hydrate, or hemithioacetal as the enzyme-bound inhibitor form. Instead, the data are consistent with the formation of an enamine between the aldehyde group of the inhibitor and the guanidine group of Arg-221 in the PTP1B active site. These aldehydes may provide a general core structure that can be further developed into highly potent and specific PTP inhibitors.
 ...
PMID:Peptidyl aldehydes as reversible covalent inhibitors of protein tyrosine phosphatases. 1218 56

Diabetes is associated with ventricular dysfunction. Ethanol consumption increases the risk of cardiovascular disease among diabetics. Acetaldehyde (ACA), the main ethanol metabolite, depresses cardiac contraction and contributes to ethanol-induced cardiac dysfunction. This study examined the influence of gender and diabetes on ACA-induced myocardial dysfunction. Adult male and female rats were made diabetic with streptozotocin (55 mg/kg). Left ventricular papillary muscles were isolated and stimulated to contract at 0.5 Hz. The mechanical parameters measured were peak tension development, time-to-peak tension (TPT), time-to-90% relaxation (RT90), and maximum velocities of tension development and decline (+/-VT). TPT and RT90 were comparably similar between genders. The +/-VT appeared to be slower in myocardium from female rats when compared to that of male counterparts, although the difference was not significant. Experimental diabetes elicited severe hyperglycemia, cardiac hypertrophy, hepatomegaly, and renal hypertrophy in both male and female animals. Myocardial mechanical properties exhibited prolonged TPT and RT90 in diabetic myocardium from both genders. The +/-VT was significantly reduced by diabetes in male but not in female myocardium. Acute ACA exposure decreased myocardial tension development and the +/-VT and shortened TPT and RT90 in myocardium from normal and diabetic rats of both genders. The ACA-induced depressant response on tension development was slightly enhanced by the diabetic state. In conclusion, these data suggest that the development of diabetes-induced myocardial dysfunction is similar between male and female animals and that the ACA-induced myocardial depressant action may be affected by diabetes but not by gender.
 ...
PMID:The influence of gender, diabetes, and acetaldehyde on the intrinsic contractile properties of isolated rat myocardium. 1221 95

Glycation (nonenzymatic glycosylation of proteins) is known to be increased as a result of hyperglycaemia in diabetes. Moreover, cell glutathione concentration has been found to be lower in diabetics and such depletion may impair the cell defence against toxic radical species. Ribose being a potent reducing sugar expected to be increased in cells of diabetics where the pentose phosphate pathway is enhanced, its putative condensation with glutathione was investigated. Reduced glutathione (GSH) was incubated with ribose and the structure of the resultant product was assessed by mass spectrometry, as well as the measurement of its remaining thiol group. A covalent reaction clearly occurred between the reducing sugar and GSH, to give an adduct named N-ribosyl-1-glutathione. This adduct appears to be the Amadori product resulting from the condensation of the primary amine group of GSH with the aldehyde group of ribose. Interestingly, the adduct could not be used as a proper substrate by glutathione peroxidase although it keeps its thiol group. We conclude that the coupling of GSH with a monosaccharide such as ribose might contribute to the decreased cell GSH and glutathione peroxidase activity observed in diabetics.
 ...
PMID:Covalent coupling of reduced glutathione with ribose: loss of cosubstrate ability to glutathione peroxidase. 1259 81

The 2-oxoaldehyde methylglyoxal (MeG) is the precursor to a number of the known advanced glycation endproducts (AGE) implicated in the development of diabetic complications. Other 2-oxoaldehydes that are important in AGE formation, such as glyoxal, glucosone, deoxyglucosone, xylosone and deoxyxylosone, are produced by nonenzymatic reactions. By contrast, MeG is produced by both enzymatic and nonenzymatic processes, most of which appear to be enhanced in diabetes. MeG may be a major precursor to formation of AGE, and rates of production of MeG depend upon physiological conditions such as hyperglycemia and ketoacidosis. MeG is also unique compared to the other 2-oxoaldehydes in its complex metabolism. At least four pathways contribute to detoxification of MeG: (1) aldose reductase, a member of the aldo-keto reductase superfamily, catalyzes the NADPH-dependent reduction of a wide range of aldehydes. MeG is the best of the known physiological aldehyde substrates of aldose reductase. The distribution of aldose reductase in human tissue is restricted; there is little expression in liver; (2) the ubiquitous and highly active glyoxalase system converts MeG into D-lactate. However, this system depends upon the availability of glutathione; activity is severely limited by conditions of oxidative stress that impact levels of glutathione; (3) betaine aldehyde dehydrogenase, also known as ALDH9, is able to catalyze the oxidation of MeG to pyruvate, although less efficiently than with its substrate betaine aldehyde; (4) the long-known but not widely studied 2-oxoaldehyde dehydrogenases (2-ODHs) catalyze the oxidation of MeG to pyruvate, primarily in liver. There are two NADP-dependent 2-ODHs in human liver. Both of these require an activating amine. The physiological activator is unknown.
 ...
PMID:Methylglyoxal metabolism and diabetic complications: roles of aldose reductase, glyoxalase-I, betaine aldehyde dehydrogenase and 2-oxoaldehyde dehydrogenase. 1260 21

Apoptosis of vascular endothelial cells (VECs) and concomitant proliferation of the underlying vascular smooth muscle cells (VSMCs) in large arteries are the key features of atherosclerosis and restenosis. However, the mechanisms underlying endothelial cell death and abnormal smooth muscle cell proliferation during the development of vascular lesions remain unclear. We have previously demonstrated that treatment with inhibitors of the aldehyde-metabolizing enzyme and aldose reductase (AR) attenuates restenosis of balloon-injured rat carotid arteries. The inhibition of AR also prevents the apoptosis of VECs induced by the tumor necrosis factor-alpha (TNF-alpha). Apoptosis of the VECs was determined by the incorporation of [3H]-thymidine and the activation of caspase-3. Stimulation of the VECs with TNF-alpha led to an increase in the DNA-binding activity of the transcription factor, nuclear factor-kappa binding protein (NF-kappaB) and the induction of the adhesion molecule (ICAM)-1. Treatment of VECs with the AR inhibitor, tolrestat, prevented the activation of NF-kappaB and diminished ICAM-1 induction stimulated by TNF-alpha. These results indicate an obligatory requirement of AR activity in the transduction of intracellular signaling initiated by the ligation of the TNF-alpha receptors leading to the activation of NF-kappaB. Although the specific signaling events interrupted by AR inhibition remain unknown, our results suggest that product(s) of AR catalysis may be essential for NF-kappaB activation. These observations could form the basis of future investigations into the therapeutic utility of AR inhibitors in preserving endothelial function and integrity during atherosclerosis and diabetes.
 ...
PMID:Role of aldose reductase in TNF-alpha-induced apoptosis of vascular endothelial cells. 1260 46

Glycation, one of the post-translational modifications of proteins, is a nonenzymatic reaction initiated by the primary addition of a sugar aldehyde or ketone to the amino groups of proteins. In the early stage of glycation, the synthesis of intermediates leading to the formation of Amadori compounds occurs. In the late stage, advanced glycation end products (AGE) are irreversibly formed after a complex cascade of reactions. Several AGEs have been characterized chemically, while other new compounds remain to be identified. To date, studies of the contribution of glycation to diseases have been primarily focused on its relationship to diabetes and diabetes-related complications. However, glucose-induced damage is not limited to diabetic patients. Although it does not cause rapid or remarkable cell damage, glycation advances slowly and accompanies every fundamental process of cellular metabolism. It has recently become clear that glycation also affects physiological aging and neurodegenerative diseases such as Alzheimer's disease and amyotrophic lateral sclerosis. Glycation alters the biological activity of proteins and their degradation processes. Protein cross-linking by AGE results in the formation of detergent-insoluble and protease-resistant aggregates. Such aggregates may interfere with both axonal transport and intracellular protein traffic in neurons. In addition, glycation reactions lead to the production of reactive oxygen species. Conversely, glycation is promoted by oxidative stress. We speculate on the presence of synergism between glycation and oxidative stress. In this review, we provide an outline of glycation and propose some possible mechanisms of its cytotoxicity and defense systems against it.
 ...
PMID:Glycation--a sweet tempter for neuronal death. 1266 85

Aldose-, aldehyde and renal specific oxido reductase (RSOR) belong to the family of aldo-keto reductases (AKRs). They are monomeric (alpha/beta)8-barrel proteins with a molecular weight ranging from 30 to 40 kDa, and at present include more than 60 members. Except for RSOR, they are expressed in a wide variety of animal and plant species and in various tissues. They catalyze NADPH-dependent reduction of various aliphatic and aromatic aldehyde and ketones. During the past three decades aldehyde reductase (AKR1A) and aldose reductase (AKR1B) have been extensively investigated, and the gene regulation of AKR1B has been noted to be heavily influenced by hyperglycemic state and high glucose ambience in various culture systems. AKR1B catalyzes the conversion of glucose to sorbitol in concert with a coenzyme, NADPH. The newly discovered RSOR has certain structural and functional similarities to AKR1B and seems to be relevant to the renal complications of diabetes mellitus. Like other AKRs, it has a NADPH binding motif, however, it is located at the N-terminus and it probably undergoes N-linked glycosylation in order to achieve functional substrate specificity. Besides the AKR3 motif, it has very little nucleotide or protein sequence homology with other members of the AKR family. Nevertheless, gene regulation of RSOR, like AKR1B, is heavily modulated by carbonyl, oxidative and osmotic stresses, and thus it is anticipated that its discovery would lead to the development of new inhibitors as well as gene therapy targets to alleviate the complications of diabetes mellitus in the future.
 ...
PMID:Gene regulation of aldose-, aldehyde- and a renal specific oxido reductase (RSOR) in the pathobiology of diabetes mellitus. 1287 Nov 37

Long-term, heavy alcohol consumption is associated with both acute and chronic pancreatitis. Progression of pancreatitis may lead to multiple comorbidities including maldigestion, diabetes, and pancreatic cancer. Understanding the underlying molecular, biochemical, and cellular mechanisms by which alcohol ingestion leads to the development of pancreatitis may help to develop strategies for the treatment and prevention of the disease. The National Institute on Alcohol Abuse and Alcoholism and the Office of Rare Diseases of National Institutes of Health sponsored a satellite symposium on "Mechanisms of Alcoholic Pancreatitis" at the annual meeting of the American Pancreatic Association, Chicago, IL, November 2002. For this symposium, 8 speakers were invited to address the following issues: (1) epidemiology of alcoholic pancreatitis; (2) pathophysiology of alcoholic pancreatitis; (3) animal models of alcoholic pancreatitis--roles of cholecystokinin (CCK) and viral infections; (4) alcohol and zymogen activation in the pancreatic acinar cell; (5) role of alcohol metabolism in alcoholic pancreatitis; (6) pancreatic stellate cell activation in alcoholic pancreatitis; and (7) genetic predisposition to alcoholic chronic pancreatitis. It was concluded that alcohol abuse is a major contributory factor to the development of both acute and chronic pancreatitis. The injurious effects of ethanol on the pancreas may be mediated through (1) sensitization of acinar cells to CCK-induced premature activation of zymogens; (2) potentiation of the effect of CCK on the activation of transcription factors, nuclear factor kappaB (NF-kappaB) and activating protein-1 (AP-1); (3) generation of toxic metabolites such as acetaldehyde and fatty acid ethyl esters; (4) sensitization of the pancreas to the toxic effects of coxsackievirus B3; and (5) activation of pancreatic stellate cells by acetaldehyde and oxidative stress and subsequent increased production of collagen and other matrix proteins.
 ...
PMID:Mechanisms of alcoholic pancreatitis. Proceedings of a conference. Chicago, Illinois, USA, November 2002. 1457 87


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>