| 1. |
- Adori, Monika, et al.
(författare)
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Hepatic Innervations and Nonalcoholic Fatty Liver Disease
- 2023
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Ingår i: Seminars in liver disease (Print). - : Thieme Medical Publishers, Inc.. - 0272-8087 .- 1098-8971. ; 43:02, s. 149-162
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Forskningsöversikt (refereegranskat)abstract
- Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disorder. Increased sympathetic (noradrenergic) nerve tone has a complex role in the etiopathomechanism of NAFLD, affecting the development/progression of steatosis, inflammation, fibrosis, and liver hemodynamical alterations. Also, lipid sensing by vagal afferent fibers is an important player in the development of hepatic steatosis. Moreover, disorganization and progressive degeneration of liver sympathetic nerves were recently described in human and experimental NAFLD. These structural alterations likely come along with impaired liver sympathetic nerve functionality and lack of adequate hepatic noradrenergic signaling. Here, we first overview the anatomy and physiology of liver nerves. Then, we discuss the nerve impairments in NAFLD and their pathophysiological consequences in hepatic metabolism, inflammation, fibrosis, and hemodynamics. We conclude that further studies considering the spatial-temporal dynamics of structural and functional changes in the hepatic nervous system may lead to more targeted pharmacotherapeutic advances in NAFLD.
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| 2. |
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| 3. |
- Ham, Seungmin, et al.
(författare)
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Role of G protein-coupled receptor kinases (GRKs) in β2-adrenoceptor-mediated glucose uptake
- 2024
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Ingår i: Pharmacology Research & Perspectives. - 2052-1707. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Truncation of the C-terminal tail of the beta(2)-AR, transfection of beta ARKct or over-expression of a kinase-dead GRK mutant reduces isoprenaline-stimulated glucose uptake, indicating that GRK is important for this response. We explored whether phosphorylation of the beta(2)-AR by GRK2 has a role in glucose uptake or if this response is related to the role of GRK2 as a scaffolding protein. CHO-GLUT4myc cells expressing wild-type and mutant beta(2)-ARs were generated and receptor affinity for [H-3]-CGP12177A and density of binding sites determined together with the affinity of isoprenaline and BRL37344. Following receptor activation by beta(2)-AR agonists, cAMP accumulation, GLUT4 translocation, [H-3]-2-deoxyglucose uptake, and beta(2)-AR internalization were measured. Bioluminescence resonance energy transfer was used to investigate interactions between beta(2)-AR and beta-arrestin2 or between beta(2)-AR and GRK2. Glucose uptake after siRNA knockdown or GRK inhibitors was measured in response to beta(2)-AR agonists. BRL37344 was a poor partial agonist for cAMP generation but displayed similar potency and efficacy to isoprenaline for glucose uptake and GLUT4 translocation. These responses to beta(2)-AR agonists occurred in CHO-GLUT4myc cells expressing beta(2)-ARs lacking GRK or GRK/PKA phosphorylation sites as well as in cells expressing the wild-type beta(2)-AR. However, beta(2)-ARs lacking phosphorylation sites failed to recruit beta-arrestin2 and did not internalize. GRK2 knock-down or GRK2 inhibitors decreased isoprenaline-stimulated glucose uptake in rat L6 skeletal muscle cells. Thus, GRK phosphorylation of the beta(2)-AR is not associated with isoprenaline- or BRL37344-stimulated glucose uptake. However, GRKs acting as scaffold proteins are important for glucose uptake as GRK2 knock-down or GRK2 inhibition reduces isoprenaline-stimulated glucose uptake.
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| 4. |
- Iqbal, Muhammad Naeem, et al.
(författare)
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Activity and Stability of Nanoconfined Alpha-Amylase in Mesoporous Silica
- 2023
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Ingår i: ACS Materials Science Au. - 2694-2461. ; 3:6, s. 659-668
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Tidskriftsartikel (refereegranskat)abstract
- Mesoporous silica particles (MSPs) have been studied for their potential therapeutic uses in controlling obesity and diabetes. Previous studies have shown that the level of digestion of starch by α-amylase is considerably reduced in the presence of MSPs, and it has been shown to be caused by the adsorption of α-amylase by MSPs. In this study, we tested a hypothesis of enzymatic deactivation and measured the activity of α-amylase together with MSPs (SBA-15) using comparably small CNP-G3 (2-chloro-4-nitrophenyl alpha-d-maltotrioside) as a substrate. We showed that pore-incorporated α-amylase was active and displayed higher activity and stability compared to amylase in solution (the control). We attribute this to physical effects: the coadsorption of CNP-G3 on the MSPs and the relatively snug fit of the amylase in the pores. Biosorption in this article refers to the process of removal or adsorption of α-amylase from its solution phase into the same solution dispersed in, or adsorbed on, the MSPs. Large quantities of α-amylase were biosorbed (about 21% w/w) on the MSPs, and high values of the maximum reaction rate (Vmax) and the Michaelis–Menten constant (KM) were observed for the enzyme kinetics. These findings show that the reduced enzymatic activity for α-amylase on MSP observed here and in earlier studies was related to the large probe (starch) being too large to adsorb in the pores, and potato starch has indeed a hydrodynamic diameter much larger than the pore sizes of MSPs. Further insights into the interactions and environments of the α-amylase inside the MSPs were provided by 1H fast magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and 13C/15N dynamic nuclear polarization MAS NMR experiments. It could be concluded that the overall fold and solvation of the α-amylase inside the MSPs were nearly identical to those in solution.
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| 5. |
- Jaunsleine, Krista, et al.
(författare)
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Development of novel β2-adrenergic receptor agonists for the stimulation of glucose uptake – The importance of chirality and ring size of cyclic amines
- 2024
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Ingår i: Bioorganic & Medicinal Chemistry Letters. - 0960-894X .- 1464-3405. ; 97
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Tidskriftsartikel (refereegranskat)abstract
- β2-Adrenergic receptor (β2AR) agonists have been reported to stimulate glucose uptake (GU) by skeletal muscle cells and are therefore highly interesting as a possible treatment for type 2 diabetes (T2D). The chirality of compounds often has a great impact on the activity of β2AR agonists, although this has thus far not been investigated for GU. Here we report the GU for a selection of synthesized acyclic and cyclic β-hydroxy-3-fluorophenethylamines. For the N-butyl and the N-(2-pentyl) compounds, the (R) and (R,R) (3d and 7e) stereoisomers induced the highest GU. When the compounds contained a saturated nitrogen containing 4- to 7-membered heterocycle, the (R,R,R) enantiomer of the azetidine (8a) and the pyrrolidine (9a) had the highest activity. Altogether, these results provide pivotal information for designing novel β2AR agonist for the treatment of T2D.
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| 6. |
- van Beek, Sten M. M., et al.
(författare)
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Effect of β2-agonist treatment on insulin-stimulated peripheral glucose disposal in healthy men in a randomised placebo-controlled trial
- 2023
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- β2-agonist treatment improves skeletal muscle glucose uptake and whole-body glucose homeostasis in rodents, likely via mTORC2-mediated signalling. However, human data on this topic is virtually absent. We here investigate the effects of two-weeks treatment with the β2-agonist clenbuterol (40 µg/day) on glucose control as well as energy- and substrate metabolism in healthy young men (age: 18-30 years, BMI: 20-25 kg/m2) in a randomised, placebo-controlled, double-blinded, cross-over study (ClinicalTrials.gov-identifier: NCT03800290). Randomisation occurred by controlled randomisation and the final allocation sequence was seven (period 1: clenbuterol, period 2: placebo) to four (period 1: placebo, period 2: clenbuterol). The primary and secondary outcome were peripheral insulin-stimulated glucose disposal and skeletal muscle GLUT4 translocation, respectively. Primary analyses were performed on eleven participants. No serious adverse events were reported. The study was performed at Maastricht University, Maastricht, The Netherlands, between August 2019 and April 2021. Clenbuterol treatment improved peripheral insulin-stimulated glucose disposal by 13% (46.6 ± 3.5 versus 41.2 ± 2.7 µmol/kg/min, p = 0.032), whereas skeletal muscle GLUT4 translocation assessed in overnight fasted muscle biopsies remained unaffected. These results highlight the potential of β2-agonist treatment in improving skeletal muscle glucose uptake and underscore the therapeutic value of this pathway for the treatment of type 2 diabetes. However, given the well-known (cardiovascular) side-effects of systemic β2-agonist treatment, further exploration on the underlying mechanisms is needed to identify viable therapeutic targets.
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