| 1. |
- Bunck, M. C., et al.
(författare)
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Exenatide affected circulating cardiovascular risk biomarkers independently of changes in body composition
- 2010
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Ingår i: Diabetes Care. - 0149-5992. ; 33:8, s. 1734-1737
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE To study the effect of exenatide on body composition and circulating cardiovascular risk biomarkers. RESEARCH DESIGN AND METHODS Metformin-treated patients with type 2 diabetes (N = 69) were randomized to exenatide or insulin glargine and treated for 1 year. Body composition was evaluated by dual-energy X-ray absorptiometry. Additionally, body weight, waist circumference, and cardiovascular biomarkers were measured. RESULTS Treatment with exenatide for 1 year significantly reduced body weight, waist circumference, and total body and trunkal fat mass by 6, 5, 11, and 13%, respectively. In addition, exenatide increased total adiponectin by 12% and reduced high-sensitivity C-reactive protein by 61%. Insulin glargine significantly reduced endothelin-1 by 7%. These changes were statistically independent of the change in total body fat mass and body weight. CONCLUSIONS Exenatide treatment for 1 year reduced body fat mass and improved the profile of circulating biomarkers of cardiovascular risk. No significant changes were seen with insulin glargine except a trend for reduced endothelin-1 levels.
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| 2. |
- Bunck, Mathijs C, et al.
(författare)
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One-year treatment with exenatide vs. insulin glargine: effects on postprandial glycemia, lipid profiles, and oxidative stress.
- 2010
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 212:1, s. 223-9
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The objective of the present study was to investigate the effects of one-year treatment with exenatide or Insulin Glargine, followed by a 5-week off-drug period, on postprandial lipidaemia, glycaemia and measures of oxidative stress. METHODS: Sixty-nine metformin-treated patients with type 2 diabetes were randomised (using apermuted block randomisation scheme stratified by site and baseline HbA(1c) stratum (< or = 8.5% or >8.5%) of which 60 completed (exenatide n=30; Insulin Glargine n=30) the pre-treatment and on-drug meal test. Postprandial glucose, lipids and lipoproteins, and oxidative stress markers were studied at week -1, 51, and after a 5-week off-drug period following a breakfast and lunch mixed-meal containing 50 g fat, 75 g carbohydrates, and 35 g protein. RESULTS: 51-Week exenatide treatment resulted in a significant reduction of prandial glucose, triglycerides, apo-B48, calculated VLDL-C, FFA and MDA excursions whereas Insulin Glargine predominantly reduced fasting glucose, FFA and MDA. Changes in markers of oxidative stress were related to changes in postprandial glucose and triglyceride excursions, independent of treatment arm. All postprandial measures returned to pre-treatment values in both groups after 5-week cessation of study treatment. CONCLUSION: Exenatide showed beneficial effects on postprandial glycaemia and lipidaemia, and these effects were related to changes in the oxidative stress markers MDA and oxLDL during one year of treatment as compared to Insulin Glargine. Following cessation of both exenatide and Insulin Glargine measures returned to pre-treatment values, suggesting that ongoing treatment is necessary to maintain the beneficial effects of either therapy.
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| 3. |
- Gustafson, Birgit, 1951, et al.
(författare)
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Activation of Canonical Wingless-type MMTV Integration Site Family (Wnt) Signaling in Mature Adipocytes Increases Beta-Catenin Levels and Leads to Cell Dedifferentiation and Insulin Resistance
- 2010
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Ingår i: The Journal of Biological Chemistry. - 0021-9258. ; 285, s. 14031-14041
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Tidskriftsartikel (refereegranskat)abstract
- Canonical Wnt ligands are secreted by several cell types in the adipose tissue. We examined if mature adipocytes can also be target cells and found that canonical Wnt activation by Wnt3a induced a marked dedifferentiation of both 3T3-L1 and human adipocytes. Typical adipogenic markers were reduced while undifferentiated cell markers like Pref-1/Dlk1, Wnt10b, and Gata2 were increased. The cells also became insulin-resistant with impaired upstream insulin signaling and reduced glucose uptake. Wnt3a stabilized B-catenin in the absence of the LRP6 receptor and with maintained axin and Dickkopf-1 protein expression. PPARgamma was repressed and PPARgamma ligands could not restore the adipogenic markers or reduce the B-catenin levels. The dedifferentiated adipocytes expressed the myofibroblast marker alpha-smooth muscle actin and were also susceptible to osteogenic transdifferentiation. These results identify a novel pathway in mature adipose cells that is critical for maintaining the normal adipocyte phenotype and insulin sensitivity.
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| 4. |
- Gustafson, Birgit, 1951, et al.
(författare)
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Thiazolidinediones increase the wingless-type MMTV integration site family (WNT) inhibitor Dickkopf-1 in adipocytes: a link with osteogenesis
- 2010
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Ingår i: Diabetologia. - 0012-186X. ; 53:3, s. 536-540
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: Dickkopf-1 (DKK1) is a secreted inhibitor of canonical wingless-type MMTV integration site family (WNT) signalling; the key pathway for cell fate and development. Inhibition of WNT signalling by DKK1 in precursor cells promotes adipogenesis and inhibits osteogenesis. Previous studies have shown that treatment of type 2 diabetic patients with thiazolidinediones (TZDs) reduces bone density and increases risk of bone fractures, while body fat is increased. METHODS: We examined the effect of TZDs on secretion and DKK1 levels in pre-adipocytes and mature adipose cells and also measured circulating DKK1 levels in 11 patients with type 2 diabetes before and after treatment with the TZD rosiglitazone for 90 days. RESULTS: TZDs added in vitro rapidly increased DKK1 protein levels and secretion in both fully differentiated adipose cells and pre-adipocytes undergoing differentiation. In parallel, beta-catenin levels, a marker of canonical WNT signalling, were reduced. Serum levels of DKK1 were also increased in several of the patients with type 2 diabetes after treatment with rosiglitazone for 90 days. CONCLUSIONS/INTERPRETATION: These results provide a novel mechanism whereby peroxisome proliferator-activated receptor-gamma activation can terminate WNT signalling and promote adipogenesis. Furthermore, they provide an explanation for why TZD treatment can lead to reduced bone formation and increased risk of fractures, since inhibited WNT signalling in progenitor cells promotes adipogenesis while osteogenesis is reduced.
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| 5. |
- Nerstedt, Annika, 1960, et al.
(författare)
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AMP-activated protein kinase inhibits IL-6-stimulated inflammatory response in human liver cells by suppressing phosphorylation of signal transducer and activator of transcription 3 (STAT3)
- 2010
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Ingår i: Diabetologia. - 0012-186X. ; 53:11, s. 2406-2416
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Tidskriftsartikel (refereegranskat)abstract
- AIM/HYPOTHESIS: The aim of the study was to examine the possible role of AMP-activated protein kinase (AMPK) in the regulation of the inflammatory response induced by cytokine action in human liver cells. METHODS: IL-6-stimulated expression of the genes for acute-phase response markers serum amyloid A (SAA1, SAA2) and haptoglobin (HP) in the human hepatocarcinoma cell line HepG2 were quantified after modulation of AMPK activity by pharmacological agonists (5-amino-4-imidazole-carboxamideriboside [AICAR], metformin) or by using small interfering (si) RNA transfection. The intracellular signalling pathway mediating the effect of AMPK on IL-6-stimulated acute-phase marker expression was characterised by assessing the phosphorylation levels of the candidate protein signal transducer and activator of transcription 3 (STAT3) in response to AMPK agonists. RESULTS: AICAR and metformin markedly blunt the IL-6-stimulated expression of SAA cluster genes as well as of haptoglobin in a dose-dependent manner. Moreover, the repression of AMPK activity by siRNA significantly reversed the inhibition of SAA expression by both AICAR and metformin, indicating that the effect of the agonists is dependent on AMPK. For the first time we show that AMPK appears to regulate IL-6 signalling by directly inhibiting the activation of the main downstream target of IL-6, STAT3. CONCLUSIONS/INTERPRETATION: We provide evidence for a key function of AMPK in suppression of the acute-phase response caused by the action of IL-6 in liver, suggesting that AMPK may act as an intracellular link between chronic low-grade inflammation and metabolic regulation in peripheral metabolic tissues.
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| 6. |
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| 7. |
- Smith, Ulf, 1943, et al.
(författare)
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Antagonistic effects of thiazolidinediones and cytokines in lipotoxicity.
- 2010
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Ingår i: BBA - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 0006-3002 .- 1388-1981. ; 1801, s. 377-380
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Tidskriftsartikel (refereegranskat)abstract
- Ectopic lipid accumulation is promoted by obesity and an impaired ability to accumulate triglycerides in the subcutaneous depots. The adipose tissue is dysregulated in hypertrophic obesity, i.e., when the adipose cells have become enlarged. In some individuals, however, obesity is a consequence of a recruitment of new adipocytes, i.e., a hyperplastic obesity. This form of obesity is usually not associated with the metabolic complications and is termed "obese but metabolically normal". We here review recent findings showing that hypertrophic obesity is associated with an impaired differentiation of committed preadipocytes. This may be a primary (genetic?) event, thus leading to hypertrophic fat cells and the associated inflammation. However, it is also possible that the inflammation is a primary event allowing, in particular, TNFalpha to inhibit preadipocyte differentiation. TNFalpha, instead, promotes a partial transdifferentiation of the preadipocytes to assume a macrophage-like phenotype. PPARgamma activation promotes adipogenesis but can apparently not overcome the impaired preadipocyte differentiation seen in hypertrophic obesity.
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| 8. |
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| 9. |
- Wallerstedt, Emelie, 1981, et al.
(författare)
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Protein kinase C-δ is involved in the inflammatory effect of IL-6 in mouse adipose cells
- 2010
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Ingår i: Diabetologia. - 0012-186X. ; 53:5, s. 946-954
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis The aim of the study was to address the role of protein kinase C-δ (PKCδ) on phosphorylation of signal transducer and activator of transcription 3 (STAT3) and activation of inflammatory genes in response to IL-6 in adipose cells. Methods Differentiated mouse 3T3-L1 adipocytes preincubated with the PKCδ inhibitor rottlerin and mouse embryonic fibroblasts (MEFs) lacking PKCδ were incubated with IL-6 and/or insulin. RNA was extracted and the gene expression was analysed by real-time PCR, while the proteins from total, nuclear and cytoplasmic lysates were analysed by immunoblotting. Results Inhibition of PKCδ by rottlerin significantly reduced both Ser-727 and Tyr-705 phosphorylation of STAT3. Consequently, nuclear translocation of STAT3 and the IL-6-induced gene transcription and protein release of the inflammatory molecule serum amyloid A 3 (SAA3) were reduced. Similarly, the IL-6-regulated gene transcription of Il-6 (also known as Il6) to Hp and the feedback inhibitor of IL-6, Socs3, were also attenuated by rottlerin. Furthermore, PKCδ was found to translocate to the nucleus following IL-6 treatment and this was also reduced by rottlerin. In agreement with the effect of rottlerin, Pkcδ (also known as Prkcd) −/− MEFs also displayed a markedly reduced ability of IL-6 to activate the transcription of Saa3, Hp, Socs3 and Il6 genes compared with wild-type MEFs. These results correlated with a reduced nuclear translocation and phosphorylation of STAT3. Conclusions/interpretation These results show that PKCδ plays a key role in the inflammatory effect of IL-6 in adipose cells and may be a suitable target for novel anti-inflammatory agents.
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