| 11. |
- Valladolid-Acebes, Ismael, et al.
(författare)
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Lowering apolipoprotein CIII protects against high-fat diet-induced metabolic derangements
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- Increased levels of apolipoprotein CIII (apoCIII), a key regulator of lipid metabolism, result in obesity-related metabolic derangements. We investigated mechanistically whether lowering or preventing high-fat diet (HFD)-induced increase in apoCIII protects against the detrimental metabolic consequences. Mice, first fed HFD for 10 weeks and thereafter also given an antisense (ASO) to lower apoCIII, already showed reduced levels of apoCIII and metabolic improvements after 4 weeks, despite maintained obesity. Prolonged ASO treatment reversed the metabolic phenotype due to increased lipase activity and receptor-mediated hepatic uptake of lipids. Fatty acids were transferred to the ketogenic pathway, and ketones were used in brown adipose tissue (BAT). This resulted in no fat accumulation and preserved morphology and function of liver and BAT. If ASO treatment started simultaneously with the HFD, mice remained lean and metabolically healthy. Thus, lowering apoCIII protects against and reverses the HFD-induced metabolic phenotype by promoting physiological insulin sensitivity.
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| 12. |
- Ekberg, Karin, et al.
(författare)
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C-Peptide replacement therapy and sensory nerve function in type 1 diabetic neuropathy
- 2007
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 30:1, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - C-peptide replacement in animals results in amelioration of diabetes-induced functional and structural abnormalities in peripheral nerves. The present study was undertaken to examine whether C-peptide administration to patients with type 1 diabetes and peripheral neuropathy improves sensory nerve function. RESEARCH DESIGN AND METHODS - This was an exploratory, double-blinded, randomized, and placebo-controlled study with three study groups that was carried out at five centers in Sweden. C-peptide was given as a replacement dose (1.5 mg/day, divided into four subcutaneous doses) or a dose three times higher (4.5 mg/day) during 6 months. Neurological examination and neurophysiological measurements were performed before and after 6 months of treatment with C-peptide or placebo. RESULTS - The age of the 139 patients who completed the protocol was 44.2 ± 0.6 (mean ± SE) years and their duration of diabetes was 30.6 ± 0.8 years. Clinical neurological impairment (NIA) (score >7 points) of the lower extremities was present in 86% of the patients at baseline. Sensory nerve conduction velocity (SCV) was 2.6 ± 0.08 SD below body height-corrected normal values at baseline and improved similarly within the two C-peptide groups (P < 0.007). The number of patients responding with a SCV peak potential improvement >1.0 m/s was greater in C-peptide-treated patients than in those receiving placebo (P < 0.03). In the least severely affected patients (SCV < 2.5 SD below normal at baseline, n = 70) SCV improved by 1.0 m/s (P < 0.014 vs. placebo). NIA score and vibration perception both improved within the C-peptide-treated groups (P < 0.011 and P < 0.002). A1C levels (7.6 ± 0.1% at baseline) decreased slightly but similarly in C-peptide- and placebo-treated patients during the study. CONCLUSIONS - C-peptide treatment for 6 months improves sensory nerve function in early-stage type 1 diabetic neuropathy.
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| 13. |
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| 14. |
- Nyrén, Rakel, et al.
(författare)
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Localization of lipoprotein lipase and GPIHBP1 in mouse pancreas : effects of diet and leptin deficiency
- 2012
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Ingår i: BMC Physiology. - : BioMed Central (BMC). - 1472-6793. ; 12, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Lipoprotein lipase (LPL) hydrolyzes triglycerides in plasma lipoproteins and enables uptake of lipolysis products for energy production or storage in tissues. Our aim was to study the localization of LPL and its endothelial anchoring protein glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1) in mouse pancreas, and effects of diet and leptin deficiency on their expression patterns. For this, immunofluorescence microscopy was used on pancreatic tissue from C57BL/6 mouse embryos (E18), adult mice on normal or high-fat diet, and adult ob/ob-mice treated or not with leptin. The distribution of LPL and GPIHBP1 was compared to insulin, glucagon and CD31. Heparin injections were used to discriminate between intracellular and extracellular LPL.RESULTS: In the exocrine pancreas LPL was found in capillaries, and was mostly co-localized with GPIHBP1. LPL was releasable by heparin, indicating localization on cell surfaces. Within the islets, most of the LPL was associated with beta cells and could not be released by heparin, indicating that the enzyme remained mostly within cells. Staining for LPL was found also in the glucagon-producing alpha cells, both in embryos (E18) and in adult mice. Only small amounts of LPL were found together with GPIHBP1 within the capillaries of islets. Neither a high fat diet nor fasting/re-feeding markedly altered the distribution pattern of LPL or GPIHBP1 in mouse pancreas. Islets from ob/ob mice appeared completely deficient of LPL in the beta cells, while LPL-staining was normal in alpha cells and in the exocrine pancreas. Leptin treatment of ob/ob mice for 12 days reversed this pattern, so that most of the islets expressed LPL in beta cells.CONCLUSIONS: We conclude that both LPL and GPIHBP1 are present in mouse pancreas, and that LPL expression in beta cells is dependent on leptin.
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| 15. |
- Sun, Jia, et al.
(författare)
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Cathelicidins positively regulate pancreatic beta-cell functions
- 2016
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 30:2, s. 884-894
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Tidskriftsartikel (refereegranskat)abstract
- Cathelicidins are pleiotropic antimicrobial peptides largely described for innate antimicrobial defenses and, more recently, immunomodulation. They are shown to modulate a variety of immune or nonimmune host cell responses. However, how cathelicidins are expressed by beta cells and modulate beta-cell functions under steady-state or proinflammatory conditions are unknown. We find that cathelicidin-related antimicrobial peptide (CRAMP) is constitutively expressed by rat insulinoma b-cell clone INS-1 832/13. CRAMP expression is inducible by butyrate or phenylbutyric acid and its secretion triggered upon inflammatory challenges by IL-1 beta or LPS. CRAMP promotes b-cell survival in vitro via the epidermal growth factor receptor (EGFR) and by modulating expression of antiapoptotic Bcl-2 family proteins: p-Bad, Bcl-2, and Bcl-xL. Also via EGFR, CRAMP stimulates glucose-stimulated insulin secretion ex vivo by rat islets. A similar effect is observed in diabetes-prone nonobese diabetic (NOD) mice. Additional investigation under inflammatory conditions reveals that CRAMP modulates inflammatory responses and beta-cell apoptosis, asmeasured by prostaglandin E2 production, cyclooxygenases (COXs), and caspase activation. Finally, CRAMP-deficient cnlp(-/-) mice exhibit defective insulin secretion, and administration of CRAMP to prediabetic NOD mice improves blood glucose clearance upon glucose challenge. Our finding suggests that cathelicidins positively regulate beta-cell functions and may be potentially used for intervening b-cell dysfunction-associated diseases.
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| 16. |
- Wen, Quan
(författare)
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Islet hormonal hypersecretion and metformin’s effect on islet hormonal secretion studied in vitro and in vivo
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Childhood obesity has surged globally. Elevated levels of free fatty acids contribute to hyperinsulinemia, hyperproinsulinemia, and hyperglucagonemia connected with both obesity and type 2 diabetes mellitus (T2DM). Metformin has beneficial effects on islets by influencing metabolism and reducing stress-induced cell death. The aim of the study was to define underlying mechanisms of free fatty acids induced islet hormone hypersecretion, especially in insulin, proinsulin and glucagon and how metformin influenced hormone levels in vitro and in vivo.Glucose stimulated insulin secretion (GSIS) from isolated human islets increased after culture in palmitate for up to 1 day, but declined with continued palmitate exposure. Whereas addition of metformin increased GSIS from islets exposed to palmitate for 1 day, metformin reduced GSIS from islets exposed to palmitate for 0.5 day. In some children with obesity insulin levels were accentuated after metformin treatment for at least 6 months, whereas insulin levels were attenuated in other children. The reduction of insulin levels was accompanied by lowering in 2-h glucose and triglycerides levels.In islets, palmitate treatment also increased proinsulin secretion, which was connected with decreasing prohormone convertase 1/3 (PC1/3) and carboxypeptidase E (CPE). Metformin normalized expression of PC1/3 and CPE, and proinsulin and insulin secretion. In children with obesity, metformin treatment reduced the proinsulin to insulin ratio (PI:I) in subjects with T2DM as well as in subjects with prediabetes, coupled with reduced 2-hour glucose and HbA1c.To address the role of palmitate on glucagon secretion we cultured αTC1 cells with palmitate. Palmitate exposure increased glucagon secretion, which was accompanied by increased ATP production, maximal respiratory capacity and protein levels of fission protein DRP-1. Knockdown or inhibition of DRP-1 decreased ATP production and glucagon secretion. Long-term palmitate treatment also changed transcripts levels of genes related to glycolysis and TCA cycle metabolism.In conclusion, metformin has beneficial effects on hyperinsulinemia and insulin processing, if introduced when insulin secretory levels are high and stable and not declining. Additionally, palmitate-induced glucagon hypersecretion was connected with increased mitochondrial fission protein DRP-1 and metabolism. Thereby, the thesis could contribute to understanding T2DM development and delineate ways to prevent its development.
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