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- Boon, Hanneke, 1981-, et al.
(författare)
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Intravenous AICAR administration reduces hepatic glucose output and inhibits whole body lipolysis in type 2 diabetic patients
- 2008
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Ingår i: Diabetologia. - Heidelberg : Springer Berlin/Heidelberg. - 0012-186X .- 1432-0428. ; 51:10, s. 1893-1900
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: The 5'-AMP-activated protein kinase (AMPK) pathway is intact in type 2 diabetic patients and is seen as a target for diabetes treatment. In this study, we aimed to assess the impact of the AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR) on both glucose and fatty acid metabolism in vivo in type 2 diabetic patients. METHODS: Stable isotope methodology and blood and muscle biopsy sampling were applied to assess blood glucose and fatty acid kinetics following continuous i.v. infusion of AICAR (0.75 mg kg(-1) min(-1)) and/or NaCl (0.9%) in ten male type 2 diabetic patients (age 64 +/- 2 years; BMI 28 +/- 1 kg/m(2)). RESULTS: Plasma glucose rate of appearance (R (a)) was reduced following AICAR administration, while plasma glucose rate of disappearance (R (d)) was similar in the AICAR and control test. Consequently, blood glucose disposal (R (d) expressed as a percentage of R (a)) was increased following AICAR infusion (p < 0.001). Accordingly, a greater decline in plasma glucose concentration was observed following AICAR infusion (p < 0.001). Plasma NEFA R (a) and R (d) were both significantly reduced in response to AICAR infusion, and were accompanied by a significant decline in plasma NEFA concentration. Although AMPK phosphorylation in skeletal muscle was not increased, we observed a significant increase in acetyl-CoA carboxylase phosphorylation (p < 0.001). CONCLUSIONS/INTERPRETATION: The i.v. administration of AICAR reduces hepatic glucose output, thereby lowering blood glucose concentrations in vivo in type 2 diabetic patients. Furthermore, AICAR administration stimulates hepatic fatty acid oxidation and/or inhibits whole body lipolysis, thereby reducing plasma NEFA concentration. © 2008 The Author(s).
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| 2. |
- Bosselaar, Marlies, et al.
(författare)
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Intra-arterial AICA-riboside administration induces NO-dependent vasodilation in vivo in human skeletal muscle
- 2009
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Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - Bethesda, MD : American Physiological Society. - 0193-1849 .- 1522-1555. ; 297:3, s. E759-E766
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Tidskriftsartikel (refereegranskat)abstract
- In animal models, administration of the adenosine analog AICA-riboside has shown beneficial effects on ischemia-reperfusion injury and glucose homeostasis. The vascular and/or metabolic effects of AICA-riboside administration in humans remain to be established. AICA-riboside was infused intra-arterially in four different dosages up to 8 mg·min-1·dl-1 in 24 healthy subjects. Forearm blood flow (FBF) and glucose uptake and plasma glucose, free fatty acid, and AICA-riboside concentrations were assessed. We also combined AICAriboside infusion (2 mg·min-1·dl -1) with the intra-arterial administration of the adenosine receptor antagonist caffeine (90 μg·min-1·dl-1; n = 6) and with the endothelial NO synthase inhibitor L-NMMA (0.4 mg·min-1·dl-1; n = 6). Additional in vitro experiments were performed to explain our in vivo effects of AICA-riboside in humans. AICA-riboside increased FBF dose dependently from 2.0 ± 0.2 to 13.2 ± 1.9 ml·min-1·dl-1 maximally (P < 0.05 for all dosages). The latter was not reduced by caffeine administration but was significantly attenuated by L-NMMA infusion. Despite high plasma AICA-riboside concentrations, forearm glucose uptake did not change. In vitro experiments showed rapid uptake of AICA-riboside by the equilibrative nucleoside transporter in erythrocytes and subsequent phosphorylation to AICA-ribotide. We conclude that AICA-riboside induces a potent vasodilator response in humans that is mediated by NO. Despite high local plasma concentrations, AICA-riboside does not increase skeletal muscle glucose uptake. Copyright © 2009 the American Physiological Society.
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| 3. |
- Reischuk, Raphael M., et al.
(författare)
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Maintaining State in Propagation Solvers
- 2009
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Ingår i: PRINCIPLES AND PRACTICE OF CONSTRAINT PROGRAMMING. - Berlin, Heidelberg : Springer. - 9783642042430 ; , s. 692-706
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Konferensbidrag (refereegranskat)abstract
- Constraint propagation solvers interleave propagation, removing impossible values from variable domains, with search. The solver state is modified during propagation. But search requires the solver to return to a previous state. Hence a, propagation solver must determine how to maintain state during propagation and forward and backward search. This paper sets out the possible ways in which a propagation solver call choose to maintain state, and the restrictions that such choices place on the resulting system. Experiments illustrate the result of various choices for the three principle state components of a solver: variables, propagators, and dependencies between them. This paper also provides the first realistic comparison of trailing versus copying for state restoration.
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