Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Endothelial dysfunction in the setting of cardiovascular risk factors, such as hypercholesterolemia, hypertension, diabetes mellitus, chronic smoking, as well as in the setting of heart failure, has been shown to be at least partly dependent on the production of reactive oxygen species (ROS), such as the superoxide radical, and the subsequent decrease in vascular bioavailability of nitric oxide (NO). Superoxide-producing enzymes involved in increased oxidative stress within vascular tissue include the NAD(P)H oxidase, the xanthine oxidase, and mitochondrial superoxide-producing enzymes. Superoxide produced by the NADPH oxidase may react with NO released by endothelial nitric oxide synthase (eNOS), thereby generating peroxynitrite. Peroxynitrite in turn has been shown to uncouple eNOS, thereby switching an antiatherosclerotic NO-producing enzyme to an enzyme that may initiate or even accelerate the atherosclerotic process by producing superoxide. Increased oxidative stress in the vasculature, however, is not restricted to the endothelium and has also been demonstrated to occur within the smooth muscle cell layer in the setting of hypercholesterolemia, diabetes mellitus, hypertension, congestive heart failure, and nitrate tolerance. Increased superoxide production by the endothelial and/or smooth muscle cells has important consequences with respect to signaling by the soluble guanylyl cyclase (sGC) and the cGMP-dependent protein kinase I (cGK-I), the activity and expression of which has been shown to be regulated in a redox-sensitive fashion. The present review summarizes current concepts concerning eNOS uncoupling and also focuses on the consequences for downstream signaling with respect to activity and expression of the sGC and cGK-I in various diseases.
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PMID:Vascular consequences of endothelial nitric oxide synthase uncoupling for the activity and expression of the soluble guanylyl cyclase and the cGMP-dependent protein kinase. 1587 5

Insulin resistance and central obesity are often associated with hypertension. The metabolic syndrome is a cluster of these common clinical disorders, and is related with an increased risk for cardiovascular diseases. A number of pro-inflammatory cytokines derived from adipose tissues have been thought to contribute to the development of insulin resistance and accelerated atherosclerosis. Among them, TNF-alpha has been most widely studied; it not only suppresses the insulin signaling, but also elicits vascular inflammation. Indeed, inhibition of TNF-alpha was found to improve insulin resistance in obese rats and reduce the progression of atherosclerosis in apolipoprotein E knockout mice, respectively. These observations demonstrate that TNF-alpha could play a central role in the pathogenesis of insulin resistance and accelerated atherosclerosis in the metabolic syndrome. Considering that the primary goals of treatment for hypertensive patients with the metabolic syndrome are prevention of the development of diabetes and cardiovascular events, anti-hypertensive drugs that have abilities to block the TNF-alpha signaling would be desirable as a first-line therapy for these patients. In the process of the search for such a unique anti-hypertensive drug, we have recently found that azelnidipine, a newly developed and commercially used long-acting dihydropyridine-based calcium antagonist (DHP), inhibited TNF-alpha-induced activator protein-1 activation and interleukin-8 expression in human umbilical vein endothelial cells by suppressing NADPH oxidase-mediated reactive oxygen species generation. The concentration of azelnidipine that was found effective in these in vitro-experiments is well within the therapeutic range. Since endothelial cells do not possess voltage-operated L-type calcium channels, these observations suggest that the beneficial effects of azelnidipine are not likely due to calcium channel blocking property, but due to its unique anti-oxidative ability. Furthermore, we have very recently found that serum levels of monocyte chemoattractant protein-1, a biomarker for subclinical atherosclerosis, were significantly decreased by the treatment of azelnidipine in patients with essential hypertension. In this paper, we would like to hypothesize that due to its unique TNF-alpha signal modulatory, anti-oxidative property, azelnidipine may be a promising DHP that targets diabetes and cardiovascular diseases in hypertensive patients with the metabolic syndrome.
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PMID:Unique atheroprotective property of azelnidipine, a dihydropyridine-based calcium antagonist. 1589 34

We have shown that short-term exposure of rat small coronary arteries (RSCAs) to high glucose enhances superoxide (O2-*) formation and impairs cAMP-mediated dilation by reducing voltage-gated K+ (Kv) channel function. However, it is not clear whether the impairment also occurs in diabetes mellitus (DM), where alternate mechanisms could mask or aggravate vasodilator dysfunction. RSCAs were isolated from control and streptozotocin-induced diabetic rats. Reduced constriction to 4-aminopyridine (4-AP) was observed in RSCAs from DM rats, indicating Kv channel impairment. Forskolin increased 4-AP-inhibitable K+ channel open-state probability and whole cell K+ current density in coronary myocytes from non-DM rats but had little effect on K+ current density in cells from DM rats. Diminished dilation to 8-bromo-cAMP, forskolin, or isoproterenol was observed in DM RSCAs. The attenuated dilation to forskolin or isoproterenol in DM RSCAs was partially restored by application of the superoxide dismutase mimetic manganese[III] tetrakis (4-benzoic acid) porphyrin. Histofluorescence studies using hydroethidine revealed a blockage of O2-* generation by the NADPH oxidase inhibitor apocynin in DM RSCAs. Sepiapterin, a precursor of tetrahydrobiopterin, had little effect on hyperglycemia-induced O2-* formation. Consistent with the findings from the concurrent fluorescence study, apocynin also partially restored the reduced dilator response to forskolin in DM RSCAs. Forskolin-induced cAMP production was unaltered in DM. We conclude that in diabetes, enhanced O2-* formation by activation of NADPH oxidase impairs cAMP-medicated dilation in RSCAs by inhibiting Kv channel activity.
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PMID:Enhanced oxidative stress impairs cAMP-mediated dilation by reducing Kv channel function in small coronary arteries of diabetic rats. 1593 95

Diabetes induces oxidative stress and leads to attenuation of cardiac K+ currents. We investigated the role of superoxide ions and angiotensin II (ANG II) in generating and linking oxidative stress to the modulation of K+ currents under diabetic conditions. K+ currents were measured using patch-clamp methods in ventricular myocytes from streptozotocin (STZ)-induced diabetic rats. Superoxide ion levels, indicating oxidative stress, were measured by fluorescent labelling with dihydroethidium (DHE). ANG II content was measured using enzyme-linked immunosorbent asssay (ELISA). The results showed DHE fluorescence to be significantly higher in cells from diabetic males, compared to controls. Relief of stress by the NADPH oxidase inhibitor apocynin or by superoxide dismutase (SOD) but not by catalase reversed the attenuation of K+ currents and reduced DHE fluorescence. In cells from diabetic females, neither apocynin nor SOD augmented K+ currents, ANG II was not elevated and DHE fluorescence was significantly weaker than in cells from males. Reduced glutathione (GSH) also augmented K+ currents in cells from diabetic males but not females. In ovariectomized diabetic females K+ currents were augmented by GSH and apocynin. Current augmentation and the attenuation of DHE fluorescence by apocynin were significantly blunted by excess ANG II (300 nm). Diabetic male rats pretreated with the angiotensin-converting enzyme (ACE) inhibitor quinapril were hyperglycaemic, but their cellular ANG II levels and DHE fluorescence were significantly decreased. In cells from these rats, K+ currents were insensitive to apocynin. In conclusion, diabetes-related oxidative stress attenuates K+ currents through ANG II-generated increased superoxide ion levels. When ANG II levels are lower, as in diabetic females or following ACE inhibition in males, oxidative stress is reduced, with blunted alterations in K+ currents.
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PMID:Modulation of potassium currents by angiotensin and oxidative stress in cardiac cells from the diabetic rat. 1594 65

The nox2-dependent NADPH oxidase was shown to be a major superoxide source in vascular disease, including diabetes. Smooth muscle cells of large arteries lack the phagocytic gp91phox subunit of the enzyme; however, two homologues have been identified in these cells, nox1 and nox4. It remained to be established whether also increases in protein levels of the nonphagocytic NADPH oxidase contribute to increased superoxide formation in diabetic vessels. To investigate changes in the expression of these homologues, we measured their expression in aortic vessels of type I diabetic rats. Eight weeks after streptozotocin treatment, we found a doubling in nox1 protein expression, while the expression of nox4 remained unchanged. This was associated with a significant increase in the NADPH oxidase activity in membrane fractions of diabetic heart and aortic tissue. Furthermore, we observed a decreased sensitivity of diabetic vessels to acetylcholine and nitroglycerin and a decrease in both acetylcholine-stimulated NO production and phosphorylation of VASP, despite an increase in endothelial NO synthase (NOSIII) expression. In addition, xanthine oxidase activity was markedly increased in plasma and 100,000 g supernatant of cardiac tissue of diabetic rats, while myocardial mitochondrial superoxide formation was only weakly enhanced. We conclude that in addition to phagocytic NADPH oxidase, also nonphagocytic, vascular NADPH oxidase subunit nox1, uncoupled NOSIII, and plasma xanthine oxidase contribute to endothelial dysfunction in the setting of diabetes mellitus.
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PMID:Differential effects of diabetes on the expression of the gp91phox homologues nox1 and nox4. 1599 37

Renal hypertrophy and extracellular matrix accumulation are early features of diabetic nephropathy. We investigated the role of the NAD(P)H oxidase Nox4 in generation of reactive oxygen species (ROS), hypertrophy, and fibronectin expression in a rat model of type 1 diabetes induced by streptozotocin. Phosphorothioated antisense (AS) or sense oligonucleotides for Nox4 were administered for 2 weeks with an osmotic minipump 72 h after streptozotocin treatment. Nox4 protein expression was increased in diabetic kidney cortex compared with non-diabetic controls and was down-regulated in AS-treated animals. AS oligonucleotides inhibited NADPH-dependent ROS generation in renal cortical and glomerular homogenates. ROS generation by intact isolated glomeruli from diabetic animals was increased compared with glomeruli isolated from AS-treated animals. AS treatment reduced whole kidney and glomerular hypertrophy. Moreover, the increased expression of fibronectin protein was markedly reduced in renal cortex including glomeruli of AS-treated diabetic rats. Akt/protein kinase B and ERK1/2, two protein kinases critical for cell growth and hypertrophy, were activated in diabetes, and AS treatment almost abolished their activation. In cultured mesangial cells, high glucose increased NADPH oxidase activity and fibronectin expression, effects that were prevented in cells transfected with AS oligonucleotides. These data establish a role for Nox4 as the major source of ROS in the kidneys during early stages of diabetes and establish that Nox4-derived ROS mediate renal hypertrophy and increased fibronectin expression.
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PMID:Nox4 NAD(P)H oxidase mediates hypertrophy and fibronectin expression in the diabetic kidney. 1613 19

In diabetes mellitus, the formation and accumulation of advanced glycation end products (AGEs) progress. There is a growing body of evidence to show that AGEs-their receptor (RAGE) interactions are involved in the development and progression of diabetic retinopathy. Bisphosphonates are potent inhibitors of bone resorption and are widely used drugs for the treatment of osteoporosis and osteolytic bone metastasis. Recently, farnesyl pyrophosphate synthase has been shown as a molecular target of nitrogen-containing bisphosphonates, and inhibition of post-translational prenylation of small molecular weight G proteins is likely involved in their anti-resorptive activity on osteoclasts. NADPH oxidase-derived reactive oxygen species (ROS) generation is required for the AGE-RAGE signaling in vascular wall cells, and small G protein Rac is a critical component of vascular NADPH oxidase complex. These observations let us to speculate that minodronate, a newly developed nitrogen-containing bisphosphonate, might be a promising remedy for treating patients with diabetic retinopathy by inhibiting the AGE-RAGE signaling pathways through suppression of ROS generation via inhibition of Rac prenylation. In this paper, we like to propose the possible ways of testing our hypotheses: (1) Does treatment with minodronate decrease the risk for the development and progression of diabetic retinopathy in osteoporotic patients? (2) If the answer is yes, is this beneficial effect of minodronate superior to that of other nitrogen-noncontaining bisphosphonates with equihypolipidemic properties? (3) Does minodronate treatment suppress NADPH oxidase-mediated ROS generation in retinas of diabetic animals? (4) Does treatment with pyridoxamine, a post-Amadori inhibitor of AGE formation, attenuate these beneficial effects of minodronate on diabetic retinopathy? These clinical and animal studies could clarify whether the use of minodronate is of benefit in patients with AGE-RAGE-related disorders such as diabetic retinopathy, even in the absence of osteoporosis.
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PMID:Minodronate, a nitrogen-containing bisphosphonate, is a promising remedy for treating patients with diabetic retinopathy. 1621 33

Leprechaunism features a clinical constellation characterized by extreme insulin resistance, growth retardation, and several distinct developmental abnormalities. One puzzling observation about leprechaunism is that mutations in the insulin receptor gene frequently associated with this syndrome cannot account for the aberrant responses of cultured cells to other growth factors. Here we report that the generation of reactive oxygen species (ROS) is impaired in cells from leprechaunism patients, thus shedding new light on this issue. Stimulation of patients' skin fibroblast cells with platelet-derived growth factor (PDGF) resulted in a lower-level tyrosine phosphorylation of cytosolic proteins compared with that seen in normal cells. In addition, consistent with the hypothesis that ROS mediate the level of tyrosine phosphorylation of cytosolic proteins through inactivation of protein tyrosine phosphatases (PTPases), patient fibroblast cells showed a significantly higher phosphatase activity than normal cells. We further showed that the lower-level tyrosine phosphorylation in response to growth factors results from the downregulation of an NADPH oxidase, Nox4, which in turn results in the reduction of ROS generation. Ectopic expression of Nox4 in the patient fibroblast cells consistently restored PDGF-induced ROS production and regulation of PTPase activities. Taken together, these data provide insight into the mechanisms through which growth retardation is associated with leprechaunism syndrome.
Diabetes 2005 Nov
PMID:Impaired generation of reactive oxygen species in leprechaunism through downregulation of Nox4. 1624 42

Diabetes mellitus is a main risk factor for vascular diseases. Vascular injury induced by diabetes mellitus is characterized by endothelial dysfunction attributable to an increased oxidative stress. So far, the molecular mechanisms involved in the vasculotoxic effects of diabetes are only partially known. We examined the effect of diabetes mellitus on oxidative stress and Rac-1 activation, a small G-protein involved in the activation of NADPH oxidase. Our results show that oxidative stress in vessels of different murine models of diabetes mellitus and in endothelial cells treated with high glucose is associated with an increased Rac-1/PAK binding and Rac-1 translocation from cytosol to plasma membrane, thus demonstrating an enhanced Rac-1 activity. More important, selective Rac-1 inhibition by an adenoviral vector carrying a dominant negative mutant of Rac-1 protected from oxidative stress and vascular dysfunction induced by diabetes mellitus. Our study demonstrates that Rac-1 plays a crucial role in diabetes-induced vascular injury, and it could be a target of novel therapeutic approaches to reduce vascular risk in diabetes mellitus.
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PMID:Selective Rac-1 inhibition protects from diabetes-induced vascular injury. 1635 2

Arachidonic acid metabolites, some of which may activate thromboxane A(2) receptors (TPr) and contribute to the development of diabetes complications, including nephropathy, are elevated in diabetes. This study determined the effect of blocking TPr with S18886 or inhibiting cyclooxygenase with aspirin on oxidative stress and the early stages of nephropathy in streptozotocin-induced diabetic apolipoprotein E(-/-) mice. Diabetic mice were treated with S18886 (5 mg . kg(-1) . day(-1)) or aspirin (30 mg . kg(-1) . day(-1)) for 6 weeks. Neither S18886 nor aspirin affected hyperglycemia or hypercholesterolemia. There was intense immunohistochemical staining for nitrotyrosine in diabetic mouse kidney. In addition, a decrease in manganese superoxide dismutase (MnSOD) activity was associated with an increase in MnSOD tyrosine-34 nitration. Tyrosine nitration was significantly reduced by S18886 but not by aspirin. Staining for the NADPH oxidase subunit p47(phox), inducible nitric oxide synthase, and 12-lipoxygenase was increased in diabetic mouse kidney, as were urine levels of 12-hydroxyeicosatetraenoic acid and 8-iso-prostaglandin F(2alpha). S18886 attenuated all of these markers of oxidant stress and inflammation. Furthermore, S18886 significantly attenuated microalbuminuria in diabetic mice and ameliorated histological evidence of diabetic nephropathy, including transforming growth factor-beta and extracellular matrix expression. Thus, in contrast to inhibiting cyclooxygenase, blockade of TPr may have therapeutic potential in diabetic nephropathy, in part by attenuating oxidative stress.
Diabetes 2006 Jan
PMID:The thromboxane receptor antagonist S18886 attenuates renal oxidant stress and proteinuria in diabetic apolipoprotein E-deficient mice. 1638 Apr 83


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