Publications by authors named "Laila R B Santos"

Aims/hypothesis: The rapid remission of type 2 diabetes by a diet very low in energy correlates with a marked improvement in glucose-stimulated insulin secretion (GSIS), emphasising the role of beta cell dysfunction in the early stages of the disease. In search of novel mechanisms of beta cell dysfunction after long-term exposure to mild to severe glucotoxic conditions, we extensively characterised the alterations in insulin secretion and upstream coupling events in human islets cultured for 1-3 weeks at ~5, 8, 10 or 20 mmol/l glucose and subsequently stimulated by an acute stepwise increase in glucose concentration.

Methods: Human islets from 49 non-diabetic donors (ND-islets) and six type 2 diabetic donors (T2D-islets) were obtained from five isolation centres.

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Over the last decade, cases of metabolic syndrome and type II diabetes have increased exponentially. Exercise and ω-3 polyunsaturated fatty acid (PUFA)-enriched diets are usually prescribed but no therapy is effectively able to restore the impaired glucose metabolism, hypertension, and atherogenic dyslipidemia encountered by diabetic patients. PUFAs are metabolized by different enzymes into bioactive metabolites with anti- or pro-inflammatory activity.

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Type 2 diabetes (T2D) arises when the pancreatic beta-cell fails to compensate for increased insulin needs due to insulin resistance. Glucolipotoxicity (GLT) has been proposed to induce beta-cell dysfunction in T2D by formation of reactive oxygen species (ROS). Here, we examined if modeling glucolipotoxic conditions by high glucose-high free fatty acid (FFA) exposure (GLT) regulates beta-cell iron transport, by increasing the cytosolic labile iron pool (LIP).

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Objective: The glucose stimulation of insulin secretion (GSIS) by pancreatic β-cells critically depends on increased production of metabolic coupling factors, including NADPH. Nicotinamide nucleotide transhydrogenase (NNT) typically produces NADPH at the expense of NADH and ΔpH in energized mitochondria. Its spontaneous inactivation in C57BL/6J mice was previously shown to alter ATP production, Ca influx, and GSIS, thereby leading to glucose intolerance.

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High glucose-induced oxidative stress and increased NADPH oxidase-2 (NOX2) activity may contribute to the progressive decline of the functional β-cell mass in type 2 diabetes. To test that hypothesis, we characterized, in islets from male NOX2 knockout (NOX2-KO) and wild-type (WT) C57BL/6J mice cultured for up to 3 weeks at 10 or 30 mmol/l glucose (G10 or G30), the in vitro effects of glucose on cytosolic oxidative stress using probes sensing glutathione oxidation (GRX1-roGFP2), thiol oxidation (roGFP1) or HO (roGFP2-Orp1), on β-cell stimulus-secretion coupling events and on β-cell apoptosis. After 1-2 days of culture in G10, the glucose stimulation of insulin secretion (GSIS) was ∼1.

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Inhibition or deletion of the soluble epoxide hydrolase (sEH) has been linked to reduced cholesterol and protection against atherosclerosis. This study set out to identify sEH substrate(s) or product(s), altered in livers from sEH(-/-) mice that contribute to these beneficial effects. In livers and isolated hepatocytes, deletion of sEH decreased expression of HMG CoA reductase, fatty acid synthase and low density lipoprotein receptor.

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The glucose stimulation of insulin secretion by pancreatic β-cells depends on increased production of metabolic coupling factors, among which changes in NADPH and ROS (reactive oxygen species) may alter the glutathione redox state (EGSH) and signal through changes in thiol oxidation. However, whether nutrients affect EGSH in β-cell subcellular compartments is unknown. Using redox-sensitive GFP2 fused to glutaredoxin 1 and its mitochondria-targeted form, we studied the acute nutrient regulation of EGSH in the cytosol/nucleus or the mitochondrial matrix of rat islet cells.

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This study investigated the potentially detrimental effects of copper and elevated aquatic CO(2) (hypercarbia), alone or in combination, on pacu, Piaractus mesopotamicus. Fish were exposed for 48 h to control (no copper addition in normocarbia), to 400 μg Cu(2+)L(-1), to hypercarbic (1% CO(2); PCO(2) = 6.9 mm Hg) water and to 400 μg Cu(2+)L(-1) + hypercarbia.

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Background: Thyroid hormones (THs) are known to regulate protein synthesis by acting at the transcriptional level and inducing the expression of many genes. However, little is known about their role in protein expression at the post-transcriptional level, even though studies have shown enhancement of protein synthesis associated with mTOR/p70S6K activation after triiodo-L-thyronine (T3) administration. On the other hand, the effects of TH on translation initiation and polypeptidic chain elongation factors, being essential for activating protein synthesis, have been poorly explored.

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Positive acute effects of fatty acids (FA) on glucose-stimulated insulin secretion (GSIS) and reactive oxygen species (ROS) formation have been reported. However, those studies mainly focused on palmitic acid actions, and reports on oleic acid (OA) are scarce. In this study, the effect of physiological OA levels on β-cell function and the mechanisms involved were investigated.

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Nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase complex has been shown to be involved in the process of glucose-stimulated insulin secretion (GSIS). In this study, we examined the effect of palmitic acid on superoxide production and insulin secretion by rat pancreatic islets and the mechanism involved. Rat pancreatic islets were incubated during 1 h with 1 mM palmitate, 1% fatty acid free-albumin, 5.

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Copper sulfate is widely used in aquaculture. Exposure to this compound can be harmful to fish, resulting in oxidative metabolism alterations and gill tissue damage. Pacu, Piaractus mesopotamicus, (wt = 43.

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