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)

When used alone, both vanadate and hydrogen peroxide (H2O2) are weakly insulin-mimetic, while in combination they are strongly synergistic due to the formation of aqueous peroxovanadium species pV(aq). Administration of these pV(aq) species leads to activation of the insulin receptor tyrosine kinase (IRK), autophosphorylation at tyrosine residues and inhibition of phosphotyrosine phosphatases (PTPs). We therefore undertook to synthesize a series of peroxovanadium (pV) compounds containing one or two peroxo anions, an oxo anion and an ancillary ligand in the inner co-ordination sphere of vanadium, whose properties and insulin-mimetic potencies could be assessed. These pV compounds were shown to be the most potent inhibitors of PTPs yet described. Their PTP inhibitory potency correlated with their capacity to stimulate IRK activity. Some pV compounds showed much greater potency as inhibitors of insulin receptor (IR) dephosphorylation than epidermal growth factor receptor (EGFR) dephosphorylation, implying relative specificity as PTP inhibitors. Replacement of vanadium with either molybdenum or tungsten resulted in equally potent inhibition of IR dephosphorylation. However IRK activation was reduced by greater than 80% suggesting that these compounds did not access intracellular PTPs. The insulin-like activity of these pV compounds were demonstrable in vivo. Intra venous (i.v.) administration of bpV(pic) and bpV(phen) resulted in the lowering of plasma glucose concentrations in normal rats in a dose dependent manner. The greater potency of bpV(pic) compared to bpV(phen) was explicable, in part, by the capacity of the former but not the latter to act on skeletal muscle as well as liver. Finally administration of bpV(phen) and insulin led to a synergism, where tyrosine phosphorylation of the IR beta-subunit increased by 20-fold and led to the appearance of four insulin-dependent in vivo substrates. The insulin-mimetic properties of the pV compounds raises the possibility for their use as insulin replacements in the management of diabetes mellitus.
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PMID:Peroxovanadium compounds: biological actions and mechanism of insulin-mimesis. 892 47

To evaluate whether granulocyte-colony stimulating factor (G-CSF) improves an impaired production of oxygen-derived free radicals by neutrophils from poorly controlled NIDDM patients, we studied the effect of G-CSF on myeloperoxidase (MPO) activity and chemiluminescence amplified by a Cypridina luciferin analog (CLA-DCL), which is dependent on O2 generation, and luminol (L-DCL), which is dependent on OCl(-) generation, in response to formyl-methonyl-leucyl-phenylalanine. Both CLA-DCL and L-DCL by neutrophils from the diabetic group (n = 15, HbA(1c) >10%) were significantly decreased (26 and 37%, respectively: P < 0.01) compared with the age-matched normal control group (n = 15), and L-DCL was more sensitive to this inhibition than CLA-DCL (P < 0.05). In both control and diabetic neutrophils, G-CSF significantly enhanced both CLA-DCL (175% in control and 156% in diabetic) and L-DCL (283% in control and 346% in diabetic). In diabetic neutrophils, the enhancing effect of G-CSF on L-DCL was more sensitive than on CLA-DCL (P < 0.001). There was a positive correlation between HbA(1c) and the enhancing effect of G-CSF on L-DCL in diabetic patients (P < 0.05), but not on CLA-DCL. MPO activity was also decreased in the diabetic group (63%, P < 0.05), and G-CSF improved this impaired MPO activity (184%, P < 0.01). Furthermore, there was a positive correlation between HbA(1c) and the improving effect of G-CSF on MPO activity (P < 0.05). Because bacterial infection still accounts for an important cause of morbidity and mortality in diabetic patients, these data suggest that G-CSF may be useful as a drug to prevent the aggravation of bacterial infection by improving neutrophil function, especially through H2O2-MPO-OCl(-) mechanism, in poorly controlled diabetic patients.
Diabetes 1997 Jan
PMID:Effect of granulocyte-colony stimulating factor on generation of oxygen-derived free radicals and myeloperoxidase activity in neutrophils from poorly controlled NIDDM patients. 897 Oct 93

Interleukin-1 (IL-1) may be a mediator of beta-cell damage in insulin-dependent diabetes mellitus (IDDM). The IL-1 mechanism of action on insulin-producing cells probably includes activation of the transcription nuclear factor kappa B (NF-kappa B), increased transcription of the inducible form of nitric oxide synthase (iNOS) and the subsequent production of nitric oxide (NO). Reactive oxygen intermediates, particularly H2O2, have been proposed as second messengers for NF-kappa B activation. In the present study, we tested whether ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), a glutathione peroxidase mimicking compound, could counteract the effects of IL-1 beta, H2O2 and alloxan in rat pancreatic islets and in the rat insulinoma cell line RINm5F (RIN cells). Some of these experiments were also reproduced in human pancreatic islets. Ebselen (20 microM) prevented the increase in nitrite production by rat islets exposed to IL-1 beta for 6 hr and induced significant protection against the acute inhibitory effects of alloxan or H2O2 exposure, as judged by the preserved glucose oxidation rates. However, ebselen failed to prevent the increase in nitrite production and the decrease in glucose oxidation and insulin release by rat islets exposed to IL-1 beta for 24 hr. Ebselen prevented the increase in nitrite production by human islets exposed for 14 hr to a combination of cytokines (IL-1 beta, tumor necrosis factor-alpha and interferon-gamma). In RIN cells, ebselen counteracted both the expression of iNOS mRNA and the increase in nitrite production induced by 6 hr exposure to IL-beta but failed to block IL-1 beta-induced iNOS expression following 24 hr exposure to the cytokine. Moreover, ebselen did not prevent IL-1 beta-induced NF-kappa B activation. As a whole, these data indicate that ebselen partially counteracts cytokine-induced NOS activation in pancreatic beta-cells, an effect not associated with inhibition of NF-kappa B activation.
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PMID:Ebselen and cytokine-induced nitric oxide synthase expression in insulin-producing cells. 898 32

Glycosylation (glycation) of proteins is a major complication of hyperglycemia in diabetes. This study has examined the effect of hydrogen peroxide (H2O2) and tertiary-butylhydroperoxide (TBH) and vitamin E (E) on glycation of hemoglobin (GHb). The RBC (15%) in phosphate-buffered saline were treated with 5-50 mM glucose (G) with and without H2O2 or TBH at 37 degrees C for 1-3 d. Glycation of hemoglobin was assessed by GHb formation using Glyc-affinity columns. There was an increase in the GHb formation with increasing G concentrations. GHb formation increased significantly in the presence of H2O2 at all G concentrations. The increase in GHb was blocked when RBC were pretreated with E. E also inhibited formation of malondialdehyde (MDA), an end product of lipid peroxidation, as assessed by the thiobarbituric acid reactivity. Similar increase in the GHb formation was observed when TBH was used instead of H2O2 to induce oxidant stress to the RBC. To examine any role of MDA per se in increased glycation, RBC were treated ex vivo with and without exogenous standard MDA. GHb formation was significantly higher with G-MDA in contrast to G alone. Thus, increased oxygen radicals activity can initiate per-oxidation of lipids and MDA accumulation, which in turn, can stimulate glycation of proteins in diabetes. E can block the glycation of proteins by inhibiting MDA formation.
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PMID:The effect of oxygen radicals metabolites and vitamin E on glycosylation of proteins. 901 22

Free radical activity may contribute to atherosclerotic lesions which in diabetic subjects may frequently lead to vascular complications. It is known that oxidative stress is associated to diabetes. Protein glycation and glucose oxidation could be possible source of free radicals. 28 non insulin dependent diabetic subjects (NIDDM) were examined. 20 healthy subjects matched for age, sex and for the presence of hypertension and hyperlipidemia were also studied. Hydrogen peroxide, measured by intracellular levels of the fluorescent 2,7-dichloro-fluorescein (DCF), was considered as indicative parameter of free radical production. The results showed that in resting platelets the basal level of hydrogen peroxide was significantly higher in diabetic subjects than in controls. Moreover, after stimulation with thrombin, collagen, phorbol myristate acetate (PMA) and platelet activating factor (PAF), platelets of diabetic subjects generated significantly higher amounts of hydrogen peroxide than controls. Moreover, platelet aggregation induced by adenosine 5'-diphosphate (ADP) and plasma beta TG levels were higher in diabetics than in controls. In diabetic patients platelet free radical production and functional activity are increased and therefore could play a role in the elevated thrombotic risk described in diabetes.
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PMID:Hyperactivity and increased hydrogen peroxide formation in platelets of NIDDM patients. 917 36

Increased oxidant stress has been suggested to occur in diabetes and to contribute to the development of late diabetic complications. Whether oxidant stress plays a role in the development or progression of insulin resistance is not known. In this study we hypothesized that exposing 3T3-L1 adipocytes to prolonged micromolar concentrations of H2O2 would reduce their acute metabolic responses to insulin stimulation. 3T3-L1 adipocytes exposed to 25 mU/ml glucose oxidase (GO) for 18 h exhibited a threefold increase in basal 2-deoxyglucose (2-DG) uptake activity. However, net increase in 2-DG uptake activity after acute insulin (100 nM) stimulation was 355 +/- 56 pmol.mg protein-1.min-1 in control vs. 198 +/- 41 pmol.mg protein-1.min-1 in GO-pretreated cells (P < 0.05). Basal lipogenesis activity was significantly enhanced by GO, but acute insulin stimulation resulted in significantly reduced lipogenesis activity (29 +/- 4 vs. 11 +/- 1 nmol glucose/well for control and 50 mU/ml GO, respectively, P = 0.001). Glycogen synthase alpha activity was reduced by GO (78 +/- 1 vs. 43 +/- 2 pmol UDP-glucose.mg protein-1.min-1, P = 0.03), whereas insulin stimulation of glycogen synthase was reduced, exhibiting a right shift in the insulin dose-response curve. These effects of GO were associated with increased GLUT-1 and reduced GLUT-4 protein and mRNA content. In conclusion, our data suggest that oxidant stress alters glucose transporters expression and insulin-stimulated metabolism in 3T3-L1 adipocytes.
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PMID:Oxidant stress reduces insulin responsiveness in 3T3-L1 adipocytes. 917 96

Alloxan-induced diabetic rats were treated with insulin (i.p.) or with Capparis decidua powder as a hypoglycaemic agent mixed with diet. The effect was assessed on lipid peroxidation (LPO) and the antioxidant defense system in rat tissues. The increased levels of blood glucose in diabetes produce superoxide anions and hydroxyl radicals in the presence of transition metal ions which cause oxidative damage to cell membranes. The heart tissue showed an increased lipid peroxidation (LPO) in diabetic rats while no significant change was observed in the liver and kidney. The treatment with C. decidua lowered LPO in these tissues even more effectively than insulin-treated rats. The superoxide dismutase (SOD) activity increased in the heart and kidneys in the diabetic group of rats probably to increase dismutation of superoxide anions. However, treatment with C. decidua decreased SOD activity in the liver and kidney and was comparable to control rats. Catalase (CAT) activity was not significantly affected in any of the tissues in diabetic and insulin-treated animals, however, CAT activity markedly increased in tissues with C. decidua treatment. Total and Se-dependent glutathione peroxidase (GSH-Px) in the heart was markedly lowered in diabetic rats which recovered with insulin as well as with C. decidua treatment. The increase in GSH-Px and CAT activity with C. decidua treatment may lower H2O2 toxicity and reduce oxidative stress in diabetes. However, glutathione (GSH) content in the heart and kidney and glutathione reductase (GSH-R) activity in all the tissues studied increased in diabetic rats while treatment with insulin lowered GSH content and GSH-R activity in these tissues. The treatment with C. decidua also decreased GSH-R activity in the kidney and heart which resulted in the decrease in GSH content in these tissues. The changes such as the increase in kidney and heart SOD may be an adaptive response in order to neutralize superoxide anions. The increase in GSH content and GSH-R activity in the tissue are in response to neutralize superoxide anions and to counteract oxidative stress in diabetes. Glutathione S-transferase (GST) was not significantly affected in diabetic rat tissue, however, heart GST increased with antidiabetic treatments. The increase in glucose-6-phosphate dehydrogenase (G6PDH) in the kidney and heart of diabetic rats subsequently decreased with C. decidua treatment. The increase in G6PDH in tissues may increase NADPH generation required for GSH-R activity and GSH production. It is suggested that these changes initially counteract the oxidative stress in diabetes, however, a gradual decrease in the antioxidative process may be one of the factors which results in chronic diabetes. The data indicate that C. decidua may have potential use as an antidiabetic agent and in lowering oxidative stress in diabetes.
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PMID:Action of capparis decidua against alloxan-induced oxidative stress and diabetes in rat tissues. 936 67

In our previous study (Diabetes 44:520-526, 1995), endothelial cells cultured in high glucose condition showed impairment of an oxidant-induced activation of the pentose phosphate pathway (PPP) and a reduced supply of NADPH to the glutathione redox cycle. To gain insight into the mechanisms of this impairment, the protective effect of pyruvate was studied in human umbilical vein endothelial cells cultured in either 5.5 mmol/l glucose (normal glucose [NG] condition) or 33 mmol/l glucose (high glucose [HG] condition). Through pretreatment of cells with 0.2 mmol/l pyruvate for 5-7 days in the HG condition, glucose oxidation through the PPP and total cellular NADPH content in the presence of 0.2 mmol/l H2O2 were increased by 54 (P < 0.05) and 34%, respectively, and glutathione-dependent degradation of H2O2 in HG cells was enhanced by 41% (P < 0.01), when compared with those cells to which pyruvate was not added. The addition of pyruvate significantly reduced the fructose 1,6-bisphosphate (FDP) content and free cytoplasmic NADH/NAD ratio, estimated by increased pyruvate/lactate ratio in NG and HG cells exposed to H2O2. Furthermore, the addition of pyruvate also showed a 46% reduction (P < 0.01) of endothelial cell damage induced by H2O2 in HG cells. These results indicate that abnormalities in PPP activation and glutathione redox cycle activity induced by H2O2 in HG cells are compensated, and that the accentuated reductive stress is improved by an addition of pyruvate. These pyruvate effects are associated with protection against an oxidant-induced endothelial cell injury in the high glucose condition.
Diabetes 1997 Dec
PMID:Pyruvate improves deleterious effects of high glucose on activation of pentose phosphate pathway and glutathione redox cycle in endothelial cells. 939 1

Diabetes is associated with a hypercoagulable state that contributes to macrovascular complications, including cardiovascular events. The glycation reaction, a consequence of chronic hyperglycemia, has also been implicated in the pathogenesis of diabetic complications. Glycated proteins have receptors on monocytes and generate reactive oxygen species that can regulate the expression of a number of genes. As abnormal monocyte expression of tissue factor (TF), the main initiator of the coagulation cascade, is responsible for thrombosis in a number of clinical settings, we studied the effect of glycated albumin on monocyte TF expression. Mononuclear cells were incubated with glycated albumin for 24 hours, and monocyte TF activity was measured with a plasma recalcification time assay; TF antigen was measured by ELISA and TF mRNA by RT-PCR. Glycated albumin induced blood monocyte expression of the procoagulant protein TF at the mRNA level. Oxidative stress appeared to be involved in this effect, as the antioxidant N-acetylcysteine diminished TF mRNA accumulation in stimulated monocytes. Hydroxyl radicals, which may be generated inside cells from H2O2 via the Fenton reaction, also appeared to be involved in this effect, as hydroxyl radical scavengers downregulated TF activity and antigen levels (but not TF mRNA). Finally, the involvement of activated protein tyrosine kinase in the transmission of the signal from the membrane to the nucleus was suggested by the inhibitory effect of herbimycin A. These results point to a new mechanism for the hypercoagulability often described in diabetic patients and suggest that antioxidants or protein tyrosine kinase inhibitors might be of therapeutic value in this setting.
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PMID:Effect of advanced glycation end product-modified albumin on tissue factor expression by monocytes. Role of oxidant stress and protein tyrosine kinase activation. 940 71

Glycoxidation reactions lead to the formation of permanent, irreversible chemical modifications and cross-links in protein, such as the glycoxidation products carboxymethyllysine (CML) and pentosidine. It has been implicated that CML as well as Amadori products play a role in the formation of superoxidative products, such as H2O2 and advanced glycosylation endproducts in trapping LDL. Therefore, a possible relationship between glycoxidation and lipoperoxidation might exist because oxidized lipoprotein, which has been directly linked to atheroma formation, could be produced by the superoxidative products released from the pathway of CML formation. Using a CML-specific monoclonal antibody (6D12) and a specific antiserum against hexitol-lysine (HL), an Amadori product, we studied the relationship between glycoxidation and lipoperoxidation by determining the aortic CML contents with ELISA and the fluorescence levels of lipoperoxidation side products, malondialdehyde (MDA) and hydroxynonenal (HNE) from STZ-induced diabetic rats and age-matched control rats. The immunohistochemical and ultrastructural changes relevant to glycoxidation and lipoperoxidation were also studied. The CML content measured by ELISA in DM rats was significantly higher than that in the control rats at 28 weeks (n = 11, P < 0.01). The levels of MDA-linked and HNE-linked fluorescence in the DM rats increased in a similar way and were significantly higher than the levels in control rats at 28 weeks (n = 11, both P < 0.01 at 28 weeks). The CML contents correlated with the fluorescence levels of both MDA-linked (n = 19, r = 0.638, P < 0.01) and HNE-linked fluorescence (n = 19, r = 0.629, P < 0.01) only in the DM rats, but not in the control rats. Our immunohistochemical study thus demonstrated that CML was initially formed in the aortic media of diabetic rats in the 16th week of diabetes, localized primarily in the extracellular matrix surrounding the aortic smooth muscle cells after HL occurred early in the 2nd week of diabetes. Consequently, a significant increase in the extracellular matrix and decrease in the area of the SMCs were observed in the aortic media in the DM rats by a morphometrical study. The in vivo results of this study provided the first evidence that CML correlated with fluorescence levels of MDA and HNE, and thus suggested the existence of a close relationship between glycoxidation and lipoperoxidation in vivo. This information is thus considered to shed some new light on the etiology of atherogenesis in diabetes.
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PMID:Glycoxidation in aortic collagen from STZ-induced diabetic rats and its relevance to vascular damage. 954 7


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