Search results for "islets of Langerhans"

The Influence of Insulin on Local Amyloidosis of the Islets of Langerhans and Insulinoma

1980

Summary Amyloid-containing islets of Langerhans from the pancreas of 75 diabetics and one case of an amyloid-containing insulinoma were investigated. By light and electron microscopy, amyloid deposits were observed between the B cells and adjacent capillaries. The cytoplasm of B cells and extracellular amyloid display immunohistological binding of anti-insulin antibody. Correspondingly, ferritin-labeled anti-insulin antibody was found by electron microscopy on and between the amyloid fibrils. Insulin or proinsulin (or a protein closely related to insulin) thus appears to be a.component of the protein which constitutes the amyloid. The molecular weight and mode of deposition of this form of …

Oxygen profile of microencapsulated islets: effect of immobilised hemoglobin in the alginate matrix

2001

Evaluation of B-cell secretion and peripheral insulin resistance during pregnancy and after delivery in gestational diabetes mellitus with obesity

1988

Nine pregnant women with gestational diabetes mellitus (GDM) were studied. Six normal pregnant women and six normal nonpregnant women were evaluated as control groups. All the women underwent oral glucose tolerance test and glucose clamp during the third trimester of pregnancy and two months after delivery. During OGTT, glucose, C-peptide and insulin plasma levels were determined. C-peptide and insulin values in the late phase of OGTT were higher during pregnancy than after delivery in both groups. In gestational diabetic women, the M-value in the second steady-state during glucose clamp was lower than in controls, both during pregnancy and after delivery. Nevertheless, in both groups the M…

Intraportal transplantation of allogenic pancreatic islets encapsulated in barium alginate beads in diabetic rats.

2003

The survival of microencapsulated islets transplanted into the unmodified peritoneal cavity is limited, even if capsular overgrowth is restricted to a minimum, due to an insufficient oxygen supply to the islets. Therefore, research efforts should focus on finding or creating a transplantation site, which permits a closer contact between the encapsulated islets and the blood. For this reason, the liver could be an interesting candidate. The aim of the present study was to test the hypothesis that the intraportal transplantation of allogenic islets encapsulated in small-sized barium alginate beads is safe and succeeds to induce normoglycemia in diabetic rats. The intraportal transplantation o…

Soluble N-ethylmaleimide-sensitive-factor attachment protein and N-ethylmaleimide-insensitive factors are required for Ca2+-stimulated exocytosis of …

1996

Ca2+ stimulates exocytosis in permeabilized insulin-secreting cells. To investigate the putative cytosolic components involved in the Ca2+ response, HIT-T15 cells (a pancreatic B-cell line) were permeabilized with streptolysin-O, a procedure that allows rapid exchange of soluble components including macromolecules. We found that in this cell preparation the secretory response to Ca2+ but not to guanosine 5'-[gamma-thio]triphosphate was lost as a function of time and could be restored by rat brain cytosol in a concentration-dependent manner. Reconstitutive activity of rat brain cytosol was found in a high-molecular-mass heat-labile partially N-ethylmaleimide(NEM)-sensitive fraction. The NEM-…

Synthesis and evaluation of (S)-2-(2-[18F]fluoroethoxy)-4-([3-methyl-1-(2-piperidin-1-yl-phenyl)-butyl-carbamoyl]-methyl)-benzoic acid ([18F]repaglin…

2004

18F-labeled non-sulfonylurea hypoglycemic agent (S)-2-(2-[(18)F]fluoroethoxy)-4-((3-methyl-1-(2-piperidin-1-yl-phenyl)-butylcarbamoyl)-methyl)-benzoic acid ([(18)F]repaglinide), a derivative of the sulfonylurea-receptor (SUR) ligand repaglinide, was synthesized as a potential tracer for the non-invasive investigation of the sulfonylurea 1 receptor status of pancreatic beta-cells by positron emission tomography (PET) in the context of type 1 and type 2 diabetes. [(18)F]Repaglinide could be obtained in an overall radiochemical yield (RCY) of 20% after 135 min with a radiochemical purity higher than 98% applying the secondary labeling precursor 2-[(18)F]fluoroethyltosylate. Specific activity w…

SNAP-25a and -25b isoforms are both expressed in insulin-secreting cells and can function in insulin secretion

1999

The tSNARE (the target-membrane soluble NSF-attachment protein receptor, where NSF is N-ethylmaleimide-sensitive fusion protein) synaptosomal-associated protein of 25 kDa (SNAP-25) is expressed in pancreatic B-cells and its cleavage by botulinum neurotoxin E (BoNT/E) abolishes stimulated secretion of insulin. In the nervous system, two SNAP-25 isoforms (a and b) have been described that are produced by alternative splicing. Here it is shown, using reverse transcriptase PCR, that messages for both SNAP-25 isoforms are expressed in primary pancreatic B and non-B cells as well as in insulin-secreting cell lines. After transfection, both isoforms can be detected at the plasma membrane as well a…

Synthesis and evaluation of a glibenclamide glucose-conjugate: a potential new lead compound for substituted glibenclamide derivatives as islet imagi…

2007

The search for novel SUR1-ligands originates from the idea to influence the in vivo behaviour by adding new structural moieties to the glibenclamide structure while preserving its binding affinity. Important application of novel conjugates might be their use as radioactively labelled tracer probes in the non-invasive investigation of the islet mass. It is known that the imaging quality of a tracer could be improved by increasing its hydrophilicity, which leads to a reduced plasma protein binding and diminished the unspecific uptake by various organs. In this study the glucose molecule was chosen as a substitute of glibenclamide to enhance hydrophilicity. As expected glucose conjugation lead…

Fibroblast Growth Factor 21 (FGF21) Protects against High Fat Diet Induced Inflammation and Islet Hyperplasia in Pancreas

2015

Fibroblast growth factor 21 (FGF21) is an important endocrine metabolic regulator expressed in multiple tissues including liver and adipose tissue. Although highest levels of expression are in pancreas, little is known about the function of FGF21 in this tissue. In order to understand the physiology of FGF21 in the pancreas, we analyzed its expression and regulation in both acinar and islet tissues. We found that acinar tissue express 20-fold higher levels than that observed in islets. We also observed that pancreatic FGF21 is nutritionally regulated; a marked reduction in FGF21 expression was noted with fasting while obesity is associated with 3–4 fold higher expression. Acinar and islet c…

Senile amyloidosis: Principles of localization in a heterogeneous form of amyloidosis

1983

In order to identify amyloid deposits in patients over 60 years of age (so-called senile amyloid), the following five tissues were investigated under the light and electron microscope : 1. pituitary gland, 2. pancreatic islets of Langerhans, 3. heart, 4. aorta, and 5. brain. In all an increasing incidence of amyloid deposits was found with increasing age, and in the brain a significant quantitative increase in amyloid deposits with increasing age was observed. Despite the biochemical heterogeneity of amyloid found in old age, all the deposits seen in tissues examined were morphologically similar. Typical amyloid fibrils were always found (diameter 60–100 A), and these were invariably deposi…