[ Diabetes Type 1 ]

Diabetes-induced increased oxidative stress in cardiomyocytes is sustained by a positive feedback loop involving Rho


Challenges to effective pharmacologic management of symptomatic diabetic peripheral neuropathy include the limited effectiveness of available medicines, frequent side effects, and the need for ongoing symptom assessment and treatment titration for maximal effectiveness. Whereas positive feedback tends to lead to instability via exponential growth, oscillation or chaotic behavior, negative feedback generally promotes stability. Diabetes provides a pertinent case of chronic disease management with a particular focus on patient self-management. Phosphorylation-deficient, constitutively active FoxO1 inhibited the high glucose-induced phosphorylation of Akt to suppress the phosphorylation/inactivation of PRAS40 and mTORC1 activity. We find that human islet β-cells express glycine receptors (GlyR), notably the GlyRα1 subunit, and the glycine transporter (GlyT) isoforms GlyT1 and GlyT2. Depletion of SIK1 promoted higher cAMP concentration and increased insulin secretion from primary islets, suggesting that SIK1 controls insulin secretion through the regulation of cAMP signaling. By using a consensus phosphorylation site of SIK1, we identified PDE4D as a new substrate for this kinase family.

In normal-weight diabetics who do not have increased insulin resistance, the model predicts that more than 85% of beta cell function has to be lost for the basal plasma glucose to rise to 6 mmol/liter, but a further 5%–10% loss increases the basal plasma glucose to over 10 mmol/liter. I had to finger prick, and instead of being presented with a wealth of data on which to make a decision I had a single, point in time data point with no other information. These studies will further our understanding of the molecular mechanism underlying the interconnection between circadian rhythm and metabolism. These data suggest that, in the diabetic heart, the RhoA/ROCK pathway contributes to contractile dysfunction at least in part by sustaining PKCβ(2) activation and ROS production via a positive feedback loop that requires an intact cytoskeleton.

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