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- Ahren, Jonatan, et al.
(författare)
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Increased beta-cell volume in mice fed a high-fat diet A dynamic study over 12 months
- 2010
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Ingår i: Islets. - : Informa UK Limited. - 1938-2022 .- 1938-2014. ; 2:6, s. 353-356
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Tidskriftsartikel (refereegranskat)abstract
- As we previously demonstrated, there is an adaptive increase in insulin secretion in insulin resistance in the model of high-fat fed female mice. Since it is assumed that islets also adapt to insulin resistance with beta-cell expansion, we have now examined beta-cell volume in this experimental model. Female C57BL/6JBomTac mice were therefore fed a high-fat diet (60% fat from lard) for three, six or twelve months and beta-cell volume was estimated as beta-cell area per islet, individual beta-cell size and beta-cell number per islet. Control animals were fed a normal chow (11% fat). We found that beta-cell area per islet and total number of beta-cells per islet were increased already after three months of high-fat feeding and that this increase was sustained throughout the twelve month study period. In contrast, individual beta-cell size showed a dynamic pattern with a reduction after three months followed by increase after six and twelve months. The number of apoptosis (caspase-3) positive beta-cells was reduced after three months, whereas there was no difference in proliferation (Ki-67) positive cells, although these were generally rarely observed. Thus, we conclude that insulin resistance accompanying high-fat feeding in mice is followed by progressive beta-cell expansion as evident by early increased islet beta-cell volume and total number of beta-cells, whereas individual beta-cell size showed a dynamic response. The model is also associated with an early reduced apoptosis, which may contribute to the increased beta-cell volume.
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| 3. |
- Bülow, Birgitta, et al.
(författare)
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Adrenal incidentaloma - follow-up results from a Swedish prospective study
- 2006
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Ingår i: European journal of endocrinology / European Federation of Endocrine Societies. - : Oxford University Press (OUP). - 0804-4643 .- 1479-683X. ; 154:3, s. 419-23
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To examine the risk of developing adrenal carcinomas and clinically overt hypersecreting tumours during short-term follow-up in patients with adrenal incidentalomas. DESIGN: 229 (98 males and 131 females) patients with adrenal incidentalomas were investigated in a prospective follow-up study (median time 25 months; range 3-108 months). The patients were registered between January 1996 and July 2001 and followed until December 2004. Twenty-seven Swedish hospitals contributed with follow-up results. METHODS: Diagnostic procedures were undertaken according to a protocol including reinvestigation with computed tomography scans after 3-6 months, 15-18 months and 27-30 months, as well as hormonal evaluation at baseline and after 27-30 months of follow-up. Operation was recommended when the incidentaloma size increased or if there was a suspicion of a hypersecreting tumour. RESULTS: The median age at diagnosis of the 229 patients included in the follow-up study was 64 years (range 28-84 years) and the median size of the adrenal incidentalomas when discovered was 2.5 cm (range 1-8 cm). During the follow-up period, an increase in incidentaloma size of > or =0.5 cm was reported in 17 (7.4%) and of > or =1.0 cm was reported in 12 (5.2%) of the 229 patients. A decrease in size was seen in 12 patients (5.2%). A hypersecreting tumour was found in 2% of the hormonally investigated patients: Cushing's syndrome (n = 2) and phaeochromocytoma (n = 1). Eleven patients underwent adrenalectomy, but no cases of primary adrenal malignancy were observed. CONCLUSIONS: Patients with adrenal incidentaloma had a low risk of developing malignancy or hormonal hypersecretion during a short-term follow-up period.
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| 4. |
- Dencker, Magnus, et al.
(författare)
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Body fat related to daily physical activity and insulin concentrations in non-diabetic children.
- 2008
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 28, s. 211-215
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Tidskriftsartikel (refereegranskat)abstract
- This study explored the associations between body fat versus daily physical activity and insulin concentrations in non-diabetic young children in a cross-sectional study of 172 children (93 boys and 79 girls) aged 8-11 years. Blood samples were analysed for serum insulin and daily physical activity was measured by accelerometers. Time spent performing vigorous activity was estimated from accelerometer data by using established cut-off points. Dual-energy x-ray absorptiometry (DXA) was used to quantify abdominal fat mass (AFM) and total body fat (TBF), also calculated as percentage of body weight (BF%). Body fat distribution was calculated as AFM/TBF. Body fat distribution was independently linked to both insulin concentrations and physical activity. In contrast, TBF, AFM, and BF% were linked to physical activity only and not to insulin concentrations. In conclusion in this population of non-diabetic children, body fat distribution was independently associated with increased concentrations of insulin and deceased amount of vigorous activity per day. Also, AFM, TBF, and BF% were independently related to minutes of vigorous activity per day.
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| 5. |
- Pacini, Giovanni, et al.
(författare)
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Reappraisal of the intravenous glucose tolerance index for a simple assessment of insulin sensitivity in mice
- 2009
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Ingår i: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 296:5, s. 1316-1324
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Tidskriftsartikel (refereegranskat)abstract
- Pacini G, Ahren M, Ahren B. Reappraisal of the intravenous glucose tolerance index for a simple assessment of insulin sensitivity in mice. Am J Physiol Regul Integr Comp Physiol 296: R1316-R1324, 2009. First published February 11, 2009; doi: 10.1152/ajpregu.90575.2008.- Mice are increasingly used in studies where measuring insulin sensitivity (IS) is a common procedure. The glucose clamp is labor intensive, cannot be used in large numbers of animals, cannot be repeated in the same mouse, and has been questioned as a valid tool for IS in mice; thus, the minimal model with 50-min intravenous glucose tolerance test (IVGTT) data was adapted for studies in mice. However, specific software and particular ability was needed. The aim of this study was to establish a simple procedure for evaluating IS during IVGTT in mice (CSI). IVGTTs (n = 520) were performed in NMRI and C57BL/6J mice (20-25g). After glucose injection (1 g/kg), seven samples were collected for 50 min for glucose and insulin measurements, analyzed with a minimal model that provided the validated reference IS (S-perpendicular to). By using the regression CS perpendicular to = alpha(1) + alpha(2) x K-G/AUC(D), where K-G is intravenous glucose tolerance index and AUC(D) is the dynamic area under the curve, IS was calculated in 134 control animals randomly selected (regression CSI vs. S-I: r = 0.66, P < 0.0001) and yielded alpha(1) = 1.93 and alpha(2) = 0.24. KG is the slope of log (glucose(5-20)) and AUCD is the mean dynamic area under insulin curve in the IVGTT. By keeping fixed alpha(1) and alpha(2), CSI was validated in 143 control mice (4.7 +/- 0.2 min . mu U- . ml(-1), virtually identical to S-I: 4.7 +/- 0.3, r = 0.89, P < 0.0001); and in 123 mice in different conditions: transgenic, addition of neuropeptides, incretins, and insulin (CSI: 6.0 +/- 0.4 vs. SI: 6.1 +/- 0.4, r = 0.94, P < 0.0001). In the other 120 animals, CSI revealed its ability to segregate different categories, as does S-I. This easily usable formula for calculating CSI overcomes many experimental obstacles and may be a simple alternative to more complex procedures when large numbers of mice or repeated experiments in the same animals are required.
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| 8. |
- Abdelgadir, M, et al.
(författare)
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Reduced leptin concentrations in subjects with type 2 diabetes mellitus in Sudan.
- 2002
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 51:3, s. 304-306
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Tidskriftsartikel (refereegranskat)abstract
- Differences have been observed in the relationship between leptin and metabolic perturbations in glucose homeostasis. Because no information is available from indigenous African populations with diabetes, the purpose of this study was to investigate the possible associations between leptin and different clinical and biochemical characteristics of a large group of subjects with type 2 diabetes mellitus in Sudan. A total of 104 (45 men and 59 women) consecutive type 2 diabetes patients and 75 control subjects (34 men and 41 women) were studied. The body mass index (BMI), blood glucose, serum insulin, and proinsulin were measured and related to serum leptin concentrations. Leptin was higher in females than in males and correlated significantly to BMI. The main novel finding was that serum leptin was significantly lower in diabetic subjects compared with controls in both females (P =.0001) and males (P =.019), although BMI did not differ between diabetic and nondiabetic subjects. Diabetic subjects treated with sulphonylurea (n = 81) had lower BMI than those treated with diet alone or other hypoglycemic drugs (n = 23) (P =.0017), but there was no difference in leptin levels between the 2 groups after adjustment for BMI (P =.87). In diabetic subjects, serum leptin correlated positively with the homeostatic assessment (HOMA) of both beta-cell function (P =.018) and insulin resistance (P =.038), whereas in control subjects, leptin correlated with insulin resistance (P =.0016), but not with beta-cell function. Diabetic subjects had higher proinsulin levels (P =.0031) and higher proinsulin to insulin ratio (P =.0003) than nondiabetic subjects. In univariate analysis, proinsulin showed a weak correlation to leptin (P =.049). In conclusion, we show in a large cohort of Sudanese subjects with type 2 diabetes that circulating leptin levels are lower in diabetic subjectss than in controls of similar age and BMI. The lower serum leptin in diabetic subjects may be a consequence of differences in fat distribution.
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| 9. |
- Abels, Mia, et al.
(författare)
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CART is overexpressed in human type 2 diabetic islets and inhibits glucagon secretion and increases insulin secretion
- 2016
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 59:9, s. 1928-1937
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis Insufficient insulin release and hyperglucagonaemia are culprits in type 2 diabetes. Cocaine- and amphetamine-regulated transcript (CART, encoded by Cartpt) affects islet hormone secretion and beta cell survival in vitro in rats, and Cart(-/-) mice have diminished insulin secretion. We aimed to test if CART is differentially regulated in human type 2 diabetic islets and if CART affects insulin and glucagon secretion in vitro in humans and in vivo in mice. Methods CART expression was assessed in human type 2 diabetic and non-diabetic control pancreases and rodent models of diabetes. Insulin and glucagon secretion was examined in isolated islets and in vivo in mice. Ca2+ oscillation patterns and exocytosis were studied in mouse islets. Results We report an important role of CART in human islet function and glucose homeostasis in mice. CART was found to be expressed in human alpha and beta cells and in a subpopulation of mouse beta cells. Notably, CART expression was several fold higher in islets of type 2 diabetic humans and rodents. CART increased insulin secretion in vivo in mice and in human and mouse islets. Furthermore, CART increased beta cell exocytosis, altered the glucose-induced Ca2+ signalling pattern in mouse islets from fast to slow oscillations and improved synchronisation of the oscillations between different islet regions. Finally, CART reduced glucagon secretion in human and mouse islets, as well as in vivo in mice via diminished alpha cell exocytosis. Conclusions/interpretation We conclude that CART is a regulator of glucose homeostasis and could play an important role in the pathophysiology of type 2 diabetes. Based on the ability of CART to increase insulin secretion and reduce glucagon secretion, CART-based agents could be a therapeutic modality in type 2 diabetes.
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