Insulin oxidative state

Insulin binding to the extracellular side of cell membranes initiates the insulin cascade , a series of phosphorylation/dephosphorylation steps. A postulated mechanism for vanadium is substitution of vanadate for phosphate in the transition state structure of protein tyrosine phosphatases (PTP).267,268 In normal physiological conditions, the attainable oxidation states of vanadium are V111, Viv and Vv. Relevant species in solution are vanadate, (a mixture of HV042-/ H2VOO and vanadyl V02+. Vanadyl is not a strong inhibitor of PTPs, suggesting other potential mechanisms for insulin mimesis for this cation. 

The oxidation state of cysteine in peptides such as glutathione may easily be recognized by the downfield shift of the signal of Cp in the cysteine residue upon oxidation from — CH2SH to -CH2-S-S- [89,790], The signal of the CH2 S-S-CH2- moiety at 41.6 ppm is also recognized in the spectra of oxytocin, vasopressin and insulin [790],... 

The effect of PJ consumption by patients with CAS on their serum oxidative state was measured also as serum concentration of antibodies against Ox-LDL.31 A significant (p < 0.01) reduction in the concentration of antibodies against Ox-LDL by 24 and 19% was observed after 1 and 3 months of PJ consumption, respectively (from 2070 61 EU/mL before treatment to 1563 69 and 1670 52 F.lI/mL after 1 and 3 months of PJ consumption, respectively). Total antioxidant status (TAS) in serum from these patients was substantially increased by 2.3-fold (from 0.95 0.12 nmol/L at baseline up to 2.20 0.25 nmol/L after 12 months of PJ consumption). These results indicate that PJ administration to patients with CAS substantially reduced their serum oxidative status and could thus inhibit plasma lipid peroxidation. The susceptibility of the patient s plasma to free radical-induced oxidation decreased after 12 months of PJ consumption by 62% (from 209 18 at baseline to 79 6 nmol of peroxides/milliliter). The effect of PJ consumption on serum oxidative state was recently measured also in patients with non-insulin-dependent diabetes mellitus (NIDDM). Consumption of 50 mL of PJ per day for a period of 3 months resulted in a significant reduction in serum lipid peroxides and thiobarbituric acid reactive substance (TBAR) levels by 56 and 28%, respectively.32... 

The potentially serious aspects of vanadium pollution, the function of biologically occurring enzyme systems, the role of vanadium on the function of numerous enzymes, and the associated role in the insulin-mimetic vanadium compounds are inextricably linked. The key to our understanding all such functionality relies on understanding the basic chemistry that underlies it. This chemistry is determined to a significant extent by the V(IV) and V(V) oxidation states but clearly is not restricted to these states. Indeed, the redox interplay between the vanadium oxidation states can be a critical aspect of the biological functionality of vanadium, particularly in enzymes such as the vanadium-dependent nitrogenases, where redox reactions are the basis of the enzyme functionality. 

Comparison of V(IV,V) hydroxamic acid complexes showed the V(V) complex induced a stronger insulin-enhancing effect than the V(IV) complex, and both complexes were better than either of the salts, vanadyl sulfate or sodium vanadate, in relieving the symptoms of mice with STZ-induced diabetes. The distribution of vanadium in tissues was the same irrespective of the complex administered however, the tissue distribution of vanadium when the salts were administered was different from that seen after vanadium complex administration [146], These results suggest that the difference in the antidiabetic activity of the hydroxaminic acid V complexes is related to the different oxidation state, although there was no difference in the final tissue distribution of these complexes. 

Glucagon exerts a ketogenic action on the liver which is more pronounced in insulin-deficient states. This action is thought to be due mainly to the inhibition of acetyl-CoA carboxylase with resulting decrease in malonyl-CoA. Malonyl-CoA is an inhibitor of carnitine acyltransferase I which is the rate-limiting step for mitochondrial fatty acid oxidation. A decrease in malonyl-CoA is thus postulated to lead to overproduction of acetyl-CoA which is then condensed to form ketone bodies. 

In diabetes mellitus, blood glucose homoeostasis and rate of lipolysis in adipose tissue appear to be associated. This relationship is most apparent in an insulin-deficient state, where glucose homoeostasis is maintained at the expense of other fuel sources, mainly FFA. Insulin deficiency initiates lipolysis. The increase in fatty acid oxidation further favours hepatic gluconeogenesis. 

Vanadium is a transitional metal found in relative abundance in nature. It can readily change its oxidation state and take an anionic or a cationic form. Vanadium has insulinlike effects in that it induces a sustained fall in blood glucose level in insulin-dependent animals. Recent shortterm trials with vanadium salts seem promising in type II (non-insulin-dependent) diabetic patients in whom liver and peripheral insulin resistance was attenuated, indicating the therapeutic potential of vanadium salts. 

III.B.5) (184). The rates of Cr(VI) reduction in the cells are probably determined by Cr(VI) diffusion through the cell membranes thus, Cr(III) was the dominant (>90%) oxidation state in the Cr(VI) treated mammalian cells (as shown by microprobe XANES spectroscopy) (89). Therefore, it is unlikely that Cr(VI) as such is responsible for the kinase activation seen in intact Cr(VI) treated cells (295, 626). The role of Cr(VI), which permeates the cell membranes much more easily than Cr(III) (Section III.B.l), is probably its delivery of high intracellular Cr(III) concentrations. Such high intracellular Cr(III) concentrations can then act as an insulin mimetic [while insulin potentiation is observed at lower Cr(III) concentrations] (495). 

Yousefzade G, Nakhaee A. Insulin-induced hypoglycemia and stress oxidative state in healthy people. Acta Diabetol 2012 49(Suppl. l) S81-5. 

The rate of mitochondrial oxidations and ATP synthesis is continually adjusted to the needs of the cell (see reviews by Brand and Murphy 1987 Brown, 1992). Physical activity and the nutritional and endocrine states determine which substrates are oxidized by skeletal muscle. Insulin increases the utilization of glucose by promoting its uptake by muscle and by decreasing the availability of free long-chain fatty acids, and of acetoacetate and 3-hydroxybutyrate formed by fatty acid oxidation in the liver, secondary to decreased lipolysis in adipose tissue. Product inhibition of pyruvate dehydrogenase by NADH and acetyl-CoA formed by fatty acid oxidation decreases glucose oxidation in muscle. 

Some flavonoids, such as procyanidins, have antidiabetic properties because they improve altered glucose and oxidative metabolisms of diabetic states (Pinent and others 2004). Extract of grape seed procyanidins (PE) administered orally to streptozotocin-induced diabetic rats resulted in an antihyperglycemic effect, which was significantly increased if PE administration was accompanied by a low insulin dose (Pinent and others 2004). The antihyperglycemic effect of PE may be partially due to the insuli-nomimetic activity of procyanidins on insulin-sensitive cell lines. 

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