| 1. |
- Ahrén, Bo, et al.
(författare)
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Disturbed alpha-cell function in mice with beta-cell specific overexpression of human islet amyloid polypeptide.
- 2008
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2008
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Tidskriftsartikel (refereegranskat)abstract
- Exogenous administration of islet amyloid polypeptide (IAPP) has been shown to inhibit both insulin and glucagon secretion. This study examined alpha-cell function in mice with beta-cell specific overexpression of human IAPP (hIAPP) after an oral protein gavage (75 mg whey protein/mouse). Baseline glucagon levels were higher in transgenic mice (41 +/- 4.0 pg/mL, n = 6) than in wildtype animals (19 +/- 5.1 pg/mL, n = 5, P = .015). In contrast, the glucagon response to protein was impaired in transgenic animals (21 +/- 2.7 pg/mL in transgenic mice versus 38 +/- 5.7 pg/mL in wildtype mice at 15 minutes; P = .027). Baseline insulin levels did not differ between the groups, while the insulin response, as the glucagon response, was impaired after protein challenge (P = .018). Glucose levels were not different between the groups and did not change significantly after protein gavage. Acetaminophen was given through gavage to the animals (2 mg/mouse) to estimate gastric emptying. The plasma acetaminophen profile was similar in the two groups of mice. We conclude that disturbances in glucagon secretion exist in mice with beta-cell specific overexpression of human IAPP, which are not secondary to changes in gastric emptying. The reduced glucagon response to protein challenge may reflect a direct inhibitory influence of hIAPP on glucagon secretion.
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| 2. |
- Andersson, Arne, et al.
(författare)
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Amyloid Deposition in Transplanted Human Pancreatic Islets : A Conceivable Cause of Their Long-Term Failure
- 2008
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Ingår i: EXPERIMENTAL DIABETES RESEARCH. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2008:562985
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Tidskriftsartikel (refereegranskat)abstract
- Following the encouraging report of the Edmonton group, there was a rejuvenation of the islet transplantation field. After that, more pessimistic views spread when long-term results of the clinical outcome were published. A progressive loss of the beta-cell function meant that almost all patients were back on insulin therapy after 5 years. More than 10 years ago, we demonstrated that amyloid deposits rapidly formed in human islets and in mouse islets transgenic for human IAPP when grafted into nude mice. It is, therefore, conceivable to consider amyloid formation as one potential candidate for the long-term failure. The present paper reviews attempts in our laboratories to elucidate the dynamics of and mechanisms behind the formation of amyloid in transplanted islets with special emphasis on the impact of long-term hyperglycemia.
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| 3. |
- Dahlfors, Gunilla, et al.
(författare)
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Inhibitory effect of diabetes on proliferation of vascular smooth muscle after balloon injury in rat aorta
- 2000
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Ingår i: Experimental Diabetes Research. - 1687-5214 .- 1687-5303. ; 1:2, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- The effect of streptozotocin-induced diabetes on cell proliferation in rat aortic intima-media, as well as on local gene expression of transforming growth factor-β1 (TGF-β1) was studied. TGF-β1 mRNA was measured by solution hybridization and TGF-β1 protein by ELISA. Proliferation was measured by bromodeoxyuridine incorporation into DNA two days after balloon injury. All BrdU-labelled cells observed were smooth muscle cells. After a diabetes duration of 2 and 4 weeks, labelled cells were significantly fewer compared with controls. Circulating levels of total TGF-β1 were lowered in rats with 2 weeks diabetes. Although the balloon injury procedure by itself stimulated the gene expression of TGF-β1, no significant difference in TGF-β1 mRNA content between diabetic and control rats after injury was found. In conclusion: vascular smooth muscle proliferation in vivo is inhibited by the diabetic state in this model of insulin deficient diabetes and this inhibition is not related to an impaired local expression of TGF-β1.
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| 4. |
- Ekberg, K, et al.
(författare)
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Effect of C-peptide on diabetic neuropathy in patients with type 1 diabetes
- 2008
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Ingår i: Experimental diabetes research. - : Hindawi Limited. - 1687-5303 .- 1687-5214. ; 2008, s. 457912-
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Tidskriftsartikel (refereegranskat)abstract
- Recent results indicate that proinsulin C-peptide, contrary to previous views, exerts important physiological effects and shows the characteristics of a bioactive peptide. Studies in type 1 diabetes, involving animal models as well as patients, demonstrate that C-peptide in replacement doses has the ability to improve peripheral nerve function and prevent or reverse the development of nerve structural abnormalities. Peripheral nerve function, as evaluated by determination of sensory nerve conduction velocity and quantitative sensory testing, is improved by C-peptide replacement in diabetes type 1 patients with early stage neuropathy. Similarly, autonomic nerve dysfunction is ameliorated following administration of C peptide for up to 3 months. As evaluated in animal models of type 1 diabetes, the improved nerve function is accompanied by reversal or prevention of nerve structural changes, and the mechanisms of action are related to the ability of C-peptide to correct diabetes-induced reductions in endoneurial blood flow and in -ATPase activity and modulation of neurotrophic factors. Combining the results demonstrates that C-peptide may be a possible new treatment of neuropathy in type 1 diabetes.
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| 5. |
- Elfving, Maria, et al.
(författare)
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Maternal enterovirus infection during pregnancy as a risk factor in Offspring Diagnosed with Type 1 Diabetes between 15 and 30 years of age
- 2008
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; , s. 271958-
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Tidskriftsartikel (refereegranskat)abstract
- Maternal enterovirus infections during pregnancy may increase the risk of offspring developing type 1 diabetes during childhood. The aim of this study was to investigate whether gestational enterovirus infections increase the offspring's risk of type 1 diabetes later in life. Serum samples from 30 mothers without diabetes whose offspring developed type 1 diabetes between 15 and 25 years of age were analyzed for enterovirus-specific immunoglobulin M (IgM) antibodies and enterovirus genome (RNA), and compared to a control group. Among the index mothers, 9/30 (30%) were enterovirus IgM-positive, and none was positive for enterovirus RNA. In the control group, 14/90 (16%) were enterovirus IgM-positive, and 4/90 (4%) were positive for enterovirus RNA (n.s.). Boys of enterovirus IgM-positive mothers had approximately 5 times greater risk of developing diabetes (OR 4.63; 95% CI 1.22-17.6), as compared to boys of IgM-negative mothers (P < .025). These results suggest that gestational enterovirus infections may be related to the risk of offspring developing type 1 diabetes in adolescence and young adulthood.
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| 6. |
- Engelbertsen, Daniel, et al.
(författare)
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Increased Inflammation in Atherosclerotic Lesions of Diabetic Akita-LDLr(-/-) Mice Compared to Nondiabetic LDLr(-/-) Mice.
- 2012
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2012:Nov.,28
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Tidskriftsartikel (refereegranskat)abstract
- Background. Diabetes is associated with increased cardiovascular disease, but the underlying cellular and molecular mechanisms are poorly understood. One proposed mechanism is that diabetes aggravates atherosclerosis by enhancing plaque inflammation. The Akita mouse has recently been adopted as a relevant model for microvascular complications of diabetes. Here we investigate the development of atherosclerosis and inflammation in vessels of Akita mice on LDLr(-/-) background. Methods and Results. Akita-LDLr(-/-) and LDLr(-/-) mice were fed high-fat diet from 6 to 24 weeks of age. Blood glucose levels were higher in both male and female Akita-LDLr(-/-) mice (137% and 70%, resp.). Male Akita-LDLr(-/-) mice had markedly increased plasma cholesterol and triglyceride levels, a three-fold increase in atherosclerosis, and enhanced accumulation of macrophages and T-cells in plaques. In contrast, female Akita-LDLr(-/-) mice demonstrated a modest 29% increase in plasma cholesterol and no significant increase in triglycerides, atherosclerosis, or inflammatory cells in lesions. Male Akita-LDLr(-/-) mice had increased levels of plasma IL-1β compared to nondiabetic mice, whereas no such difference was seen between female diabetic and nondiabetic mice. Conclusion. Akita-LDLr(-/-) mice display considerable gender differences in the development of diabetic atherosclerosis. In addition, the increased atherosclerosis in male Akita-LDLr(-/-) mice is associated with an increase in inflammatory cells in lesions.
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| 7. |
- Forst, T, et al.
(författare)
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New tricks by an old dog
- 2008
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Ingår i: Experimental diabetes research. - : Hindawi Limited. - 1687-5303 .- 1687-5214. ; 2008, s. 384219-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Hach, T, et al.
(författare)
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C-peptide and its C-terminal fragments improve erythrocyte deformability in type 1 diabetes patients
- 2008
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Ingår i: Experimental diabetes research. - : Hindawi Limited. - 1687-5303 .- 1687-5214. ; 2008, s. 730594-
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis. Data now indicate that proinsulin C-peptide exerts important physiological effects and shows the characteristics of an endogenous peptide hormone. This study aimed to investigate the influence of C-peptide and fragments thereof on erythrocyte deformability and to elucidate the relevant signal transduction pathway.Methods. Blood samples from 23 patients with type 1 diabetes and 15 matched healthy controls were incubated with 6.6 nM of either human C-peptide, C-terminal hexapeptide, C-terminal pentapeptide, a middle fragment comprising residues 11–19 of C-peptide, or randomly scrambled C-peptide. Furthermore, red blood cells from 7 patients were incubated with C-peptide, penta- and hexapeptides with/without addition of ouabain, EDTA, or pertussis toxin. Erythrocyte deformability was measured using a laser diffractoscope in the shear stress range 0.3–60 Pa.Results. Erythrocyte deformability was impaired by 18–25% in type 1 diabetic patients compared to matched controls in the physiological shear stress range 0.6–12 Pa(P<.01–.001). C-peptide, penta- and hexapeptide all significantly improved the impaired erythrocyte deformability of type 1 diabetic patients, while the middle fragment and scrambled C-peptide had no detectable effect. Treatment of erythrocytes with ouabain or EDTA completely abolished the C-peptide, penta- and hexapeptide effects. Pertussis toxin in itself significantly increased erythrocyte deformability.Conclusion/interpretation. C-peptide and its C-terminal fragments are equally effective in improving erythrocyte deformability in type 1 diabetes. The C-terminal residues of C-peptide are causally involved in this effect. The signal transduction pathway isCa2+-dependent and involves activation of red blood cellNa+,K+-ATPase.
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| 9. |
- Hoppener, J. W. M., et al.
(författare)
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Human Islet Amyloid Polypeptide Transgenic Mice: In Vivo and Ex Vivo Models for the Role of hIAPP in Type 2 Diabetes Mellitus
- 2008
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303.
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Tidskriftsartikel (refereegranskat)abstract
- Human islet amyloid polypeptide (hIAPP), a pancreatic islet protein of 37 amino acids, is the main component of islet amyloid, seen at autopsy in patients with type 2 diabetes mellitus (DM2). To investigate the roles of hIAPP and islet amyloid in DM2, we generated transgenic mice expressing hIAPP in their islet beta cells. In this study, we found that after a long-term, high-fat diet challenge islet amyloid was observed in only 4 of 19 hIAPP transgenic mice. hIAPP transgenic females exhibited severe glucose intolerance, which was associated with a downregulation of GLUT-2 mRNA expression. In isolated islets from hIAPP males cultured for 3 weeks on high-glucose medium, the percentage of amyloid containing islets increased from 5.5% to 70%. This ex vivo system will allow a more rapid, convenient, and specific study of factors influencing islet amyloidosis as well as of therapeutic strategies to interfere with this pathological process. Copyright (C) 2008 J. W. M. Hoppener et al.
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| 10. |
- Ludvigsen, Eva, et al.
(författare)
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Altered Expression of Somatostatin Receptors in Pancreatic Islets from NOD Mice Cultured at Different Glucose Concentrations In Vitro and in Islets Transplanted to Diabetic NOD Mice In Vivo
- 2011
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2011, s. 623472-
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Tidskriftsartikel (refereegranskat)abstract
- Somatostatin acts via five receptors (sst1-5). We investigated if the changes in pancreatic islet sst expression in diabetic NOD mice compared to normoglycemic mice are a consequence of hyperglycemia or the ongoing immune reaction in the pancreas. Pancreatic islets were isolated from NOD mice precultured for 5 days and further cultured for 3 days at high or low glucose before examined. Islets were also isolated from NOD mice and transplanted to normal or diabetic mice in a number not sufficient to cure hyperglycemia. After three days, the transplants were removed and stained for sst1-5 and islet hormones. Overall, changes in sst islet cell expression were more common in islets cultured in high glucose concentration in vitro as compared to the islet transplantation in vivo to diabetic mice. The beta and PP cells exhibited more frequent changes in sst expression, while the alpha and delta cells were relatively unaffected by the high glucose condition. Our findings suggest that the glucose level may alter sst expressed in islets cells; however, immune mechanisms may counteract such changes in islet sst expression.
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