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- Christesen, Henrik B. T., et al.
(författare)
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Rapid genetic analysis in congenital hyperinsulinism
- 2007
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Ingår i: Hormone Research. - : S. Karger AG. - 0301-0163. ; 67:4, s. 184-188
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Tidskriftsartikel (refereegranskat)abstract
- Backgound: In severe, medically unresponsive congenital hyperinsulinism (CHI), the histological differentiation of focal versus diffuse disease is vital, since the surgical management is completely different. Genetic analysis may help in the differential diagnosis, as focal CHI is associated with a paternal germline ABCC8 or KCNJ11 mutation and a focal loss of maternal chromosome 11p15, whereas a maternal mutation, or homozygous/compound heterozygous ABCC8 and KCNJ11 mutations predict diffuse-type disease. However, genotyping usually takes too long to be helpful in the absence of a founder mutation. Methods: In 4 patients, a rapid genetic analysis of the ABBC8 and KCNJ11 genes was performed within 2 weeks on request prior to the decision of pancreatic surgery. Results: Two patients had no mutations, rendering the genetic analysis non-informative. Peroperative multiple biopsies showed diffuse disease. One patient had a paternal KCNJ11 mutation and focal disease confirmed by positron emission tomography scan and biopsies. One patient had a de novo heterozygous ABBC8 mutation and unexplained diffuse disease confirmed by positron emission tomography scan and biopsies. Conclusion: A rapid analysis of the entire ABBC8 and KCNJ11 genes should not stand alone in the preoperative assessment of patients with CHI, except for the case of maternal, or homozygous/compound heterozygous disease-causing mutations. Copyright (c) 2007 S. Karger AG, Basel.
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- Miettinen, PJ, et al.
(författare)
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Downregulation of EGF receptor signaling in pancreatic islets causes diabetes due to impaired postnatal beta-cell growth
- 2006
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:12, s. 3299-3308
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Tidskriftsartikel (refereegranskat)abstract
- Epidermal growth factor receptor (EGF-R) signaling is essential for proper fetal development and growth of pancreatic islets, and there is also evidence for its involvement in β-cell signal transduction in the adult. To study the functional roles of EGF-R in β-cell physiology in postnatal life, we have generated transgenic mice that carry a mutated EGF-R under the pancreatic duodenal homeobox-1 promoter (E1-DN mice). The transgene was expressed in islet β- and δ-cells but not in α-cells, as expected, and it resulted in an ∼40% reduction in pancreatic EGF-R, extracellular signal–related kinase, and Akt phosphorylation. Homozygous E1-DN mice were overtly diabetic after the age of 2 weeks. The hyperglycemia was more pronounced in male than in female mice. The relative β-cell surface area of E1-DN mice was highly reduced at the age of 2 months, while α-cell surface area was not changed. This defect was essentially postnatal, since the differences in β-cell area of newborn mice were much smaller. An apparent explanation for this is impaired postnatal β-cell proliferation; the normal surge of β-cell proliferation during 2 weeks after birth was totally abolished in the transgenic mice. Heterozygous E1-DN mice were glucose intolerant in intraperitoneal glucose tests. This was associated with a reduced insulin response. However, downregulation of EGF-R signaling had no influence on the insulinotropic effect of glucagon-like peptide-1 analog exendin-4. In summary, our results show that even a modest attenuation of EGF-R signaling leads to a severe defect in postnatal growth of the β-cells, which leads to the development of diabetes.
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- Virtanen, Ismo, et al.
(författare)
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Blood vessels of human islets of Langerhans are surrounded by a double basement membrane
- 2008
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 51:7, s. 1181-91
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: Based on mouse study findings, pancreatic islet cells are supposed to lack basement membrane (BM) and interact directly with vascular endothelial BM. Until now, the BM composition of human islets has remained elusive. METHODS: Immunohistochemistry with specific monoclonal and polyclonal antibodies as well as electron microscopy were used to study BM organisation and composition in human adult islets. Isolated islet cells and function-blocking monoclonal antibodies and recombinant soluble Lutheran peptide were further used to study islet cell adhesion to laminin (Lm)-511. Short-term cultures of islets were used to study Lutheran and integrin distribution. RESULTS: Immunohistochemistry revealed a unique organisation for human Lm-511/521 as a peri-islet BM, which co-invaginated into islets with vessels, forming an outer endocrine BM of the intra-islet vascular channels, and was distinct from the vascular BM that additionally contained Lm-411/421. These findings were verified by electron microscopy. Lutheran glycoprotein, a receptor for the Lm alpha5 chain, was found prominently on endocrine cells, as identified by immunohistochemistry and RT-PCR, whereas alpha(3) and beta(1) integrins were more diffusely distributed. High Lutheran content was also found on endocrine cell membranes in short-term culture of human islets. The adhesion of dispersed beta cells to Lm-511 was inhibited equally effectively by antibodies to integrin and alpha(3) and beta(1) subunits, and by soluble Lutheran peptide. CONCLUSIONS/INTERPRETATION: The present results disclose a hitherto unrecognised BM organisation and adhesion mechanisms in human pancreatic islets as distinct from mouse islets.
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