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- Rosenstock, J, et al.
(författare)
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Effects of the DPP-4 Inhibitor Vildagliptin on Incretin Hormones, Islet Function, and Postprandial Glycemia in Subjects with Impaired Glucose Tolerance
- 2008
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Ingår i: Diabetes Care. - : American Diabetes Association. - 1935-5548 .- 0149-5992. ; 31:1, s. 30-35
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study was conducted to determine the effects of vildagliptin on incretin hormone levels, islet function, and postprandial glucose control in subjects with impaired glucose tolerance (IGT). Research Design and Methods: A 12-week double-blind, randomized, parallel-group study comparing vildagliptin (50 mg qd) and placebo was conducted in 179 subjects with IGT (2-h glucose= 9.1 mmol/l, A1C= 5.9%). Plasma levels of intact GLP-1 and GIP, glucose, insulin, C-peptide, and glucagon were measured during standard meal tests performed at baseline and Week 12. Insulin secretory rate (ISR) was estimated by C-peptide deconvolution. The between-group differences (vildagliptin - placebo) in the adjusted mean changes from baseline to endpoint in the total and incremental (Delta) AUC(0-2h) for these analytes were assessed by ANCOVA; glucose AUC(0-2h) was the primary outcome variable. Results: Relative to placebo, vildagliptin increased GLP-1 (DeltaAUC, +6.0+/-1.2 pmol/l*h, P<0.001) and GIP (DeltaAUC, +46.8+/-5.4 pmol/l*h, P<0.001) and decreased glucagon (DeltaAUC, -3.0 +/- 1.0 pmol/l*h, P=0.003). Although postprandial insulin levels were unaffected (DeltaAUC, +20.8+/-35.7 pmol/l*h, P=0.561), prandial glucose excursions were reduced (DeltaAUC, -1.0+/-0.3 mmol/l*h, P<0.001), representing approximately 30% decrease relative to placebo. Beta-cell function as assessed by the ISR AUC(0-2h)/glucose AUC(0-2h) was significantly increased (+6.4 +/- 2.0 pmol*min(-1)*m(-2)*mM(-1), P=0.002). Adverse event profiles were similar in the two treatment groups and no hypoglycemia was reported. Conclusions: The known effects of vildagliptin on incretin levels and islet function in type 2 diabetes were reproduced in subjects with IGT with a 32% reduction in postprandial glucose excursions and no evidence of hypoglycemia or weight gain.
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- Jendle, Johan, 1963-, et al.
(författare)
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Better glycaemic control and less weight gain with once weekly dulaglutide vs bedtime insulin glargine, both combined with thrice daily lispro, in type 2 diabetes (AWARD-4)
- 2014
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 57:Suppl 1, s. S23-S24
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Background and aims: This 52 week, parallel-arm, open-label, phase 3 study compared two doses of the once weekly GLP-1 receptor agonist dulaglutide (DU) versus bedtime insulin glargine, all combined with pre-meal insulin lispro with or without metformin, in patients with type 2 diabetes mellitus inadequately controlled on conventional insulin therapy. Insulin glargine and insulin lispro were titrated to attempt to reach glycaemic targets.Materials and methods: Patients (N = 884; mean baseline characteristics: age 59.4 years; duration of diabetes 12.7 years; HbA1c 8.5%; body weight 91.1 kg; BMI 32.5 kg/m2; total daily insulin dose 56 U) were randomised (1:1:1) to once weekly DU 1.5 mg, DU 0.75 mg, or bedtime insulin glargine titrated-to-target. The primary objective was to compare the change in HbA1c from baseline of DU 1.5 mg with insulin glargine at 26 weeks for noninferiority (margin 0.4%) and if met, then superiority was tested.Results: At 26 and 52 weeks, both DU doses were statistically superior to insulin glargine for HbA1c change from baseline. Insulin glargine was associ-ated with greater fasting serum glucose reduction compared with both DU doses. The mean prandial insulin doses at 26 weeks were 93 U for DU 1.5 mg, 97 U for DU 0.75 mg, and 68 U for insulin glargine. The insulin glargine dose was 65 U. Similar insulin doses were observed at 52 weeks. Body weight decreased with DU 1.5 mg and increased with DU 0.75 mg and insulin glar-gine at 52 weeks. The rate of documented symptomatic hypoglycaemia (≤3.9 mmol/L) at 52 weeks was 31.0, 35.0,and 39.9 events/patient/year for DU 1.5 mg, DU 0.75 mg, and insulin glargine, respectively. The number of severe hypoglycaemia events was 11 for DU 1.5 mg, 15 for DU 0.75 mg, and 22 for insulin glargine. Nausea, diarrhoea, and vomiting were more common with DU 1.5 mg (25.8%, 16.6%, and 12.2%, respectively) and DU 0.75 mg (17.7%, 15.7%, and 10.6%) versus insulin glargine (3.4%, 6.1%, and 1.7%).Conclusion: DU compared to insulin glargine, both combined with insu-lin lispro, resulted in better glycaemic control, less body weight gain, no in-creased risk of hypoglycaemia, and more common reporting of gastrointes-tinal adverse events.
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| 5. |
- Sheldrake, Merlin, et al.
(författare)
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Arbuscular mycorrhizal fungal community composition is altered by long-term litter removal but not litter addition in a lowland tropical forest
- 2017
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 214:1, s. 455-467
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Tidskriftsartikel (refereegranskat)abstract
- Tropical forest productivity is sustained by the cycling of nutrients through decomposing organic matter. Arbuscular mycorrhizal (AM) fungi play a key role in the nutrition of tropical trees, yet there has been little experimental investigation into the role of AM fungi in nutrient cycling via decomposing organic material in tropical forests. We evaluated the responses of AM fungi in a long-term leaf litter addition and removal experiment in a tropical forest in Panama. We described AM fungal communities using 454-pyrosequencing, quantified the proportion of root length colonised by AM fungi using microscopy, and estimated AM fungal biomass using a lipid biomarker. AM fungal community composition was altered by litter removal but not litter addition. Root colonisation was substantially greater in the superficial organic layer compared with the mineral soil. Overall colonisation was lower in the litter removal treatment, which lacked an organic layer. There was no effect of litter manipulation on the concentration of the AM fungal lipid biomarker in the mineral soil. We hypothesise that reductions in organic matter brought about by litter removal may lead to AM fungi obtaining nutrients from recalcitrant organic or mineral sources in the soil, besides increasing fungal competition for progressively limited resources.
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| 6. |
- Sheldrake, Merlin, et al.
(författare)
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Responses of arbuscular mycorrhizal fungi to long-term inorganic and organic nutrient addition in a lowland tropical forest
- 2018
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Ingår i: ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 12:10, s. 2433-2445
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Tidskriftsartikel (refereegranskat)abstract
- Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest productivity will be influenced by anthropogenic change. Here we assessed the influence of long-term inorganic and organic nutrient additions and nutrient depletion on AM fungi, using two adjacent experiments in a lowland tropical forest in Panama. We characterised AM fungal communities in soil and roots using 454-pyrosequencing, and quantified AM fungal abundance using microscopy and a lipid biomarker. Phosphorus and nitrogen addition reduced the abundance of AM fungi to a similar extent, but affected community composition in different ways. Nutrient depletion (removal of leaf litter) had a pronounced effect on AM fungal community composition, affecting nearly as many OTUs as phosphorus addition. The addition of nutrients in organic form (leaf litter) had little effect on any AM fungal parameter. Soil AM fungal communities responded more strongly to changes in nutrient availability than communities in roots. This suggests that the ‘dual niches’ of AM fungi in soil versus roots are structured to different degrees by abiotic environmental filters, and biotic filters imposed by the plant host. Our findings indicate that AM fungal communities are fine-tuned to nutrient regimes, and support future studies aiming to link AM fungal community dynamics with ecosystem function.
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| 9. |
- Forsmark, Benjamin, et al.
(författare)
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Shifts in microbial community composition and metabolism correspond with rapid soil carbon accumulation in response to 20 years of simulated nitrogen deposition
- 2024
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Ingår i: Science of the Total Environment. - 0048-9697. ; 918
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic nitrogen (N) deposition and fertilization in boreal forests frequently reduces decomposition and soil respiration and enhances C storage in the topsoil. This enhancement of the C sink can be as strong as the aboveground biomass response to N additions and has implications for the global C cycle, but the mechanisms remain elusive. We hypothesized that this effect would be associated with a shift in the microbial community and its activity, and particularly by fungal taxa reported to be capable of lignin degradation and organic N acquisition. We sampled the organic layer below the intact litter of a Norway spruce (Picea abies (L.) Karst) forest in northern Sweden after 20 years of annual N additions at low (12.5 kg N ha−1 yr−1) and high (50 kg N ha−1 yr−1) rates. We measured microbial biomass using phospholipid fatty-acid analysis (PLFA) and ergosterol measurements and used ITS metagenomics to profile the fungal community of soil and fine-roots. We probed the metabolic activity of the soil community by measuring the activity of extracellular enzymes and evaluated its relationships with the most N responsive soil fungal species. Nitrogen addition decreased the abundance of fungal PLFA markers and changed the fungal community in humus and fine-roots. Specifically, the humus community changed in part due to a shift from Oidiodendron pilicola, Cenococcum geophilum, and Cortinarius caperatus to Tylospora fibrillosa and Russula griseascens. These microbial community changes were associated with decreased activity of Mn-peroxidase and peptidase, and an increase in the activity of C acquiring enzymes. Our results show that the rapid accumulation of C in the humus layer frequently observed in areas with high N deposition is consistent with a shift in microbial metabolism, where decomposition associated with organic N acquisition is downregulated when inorganic N forms are readily available.
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