Suppressor of cytokine signaling-1 inhibits caspase activation and protects from cytokine-induced beta cell death.

Pancreatic beta cell damage caused by proinflammatory cytokines interleukin-1beta (IL-1beta), interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) is a key event in the pathogenesis of type 1 diabetes. The suppressor of cytokine signaling-1 (SOCS-1) blocks IFNgamma-induced signaling and prevents diabetes in the non-obese diabetic mouse. Here, we investigated if SOCS-1 overexpression in primary beta cells provides protection from cytokine-induced islet cell dysfunction and death.

Inositol pyrophosphates: structure, enzymology and function.

The stereochemistry of the inositol backbone provides a platform on which to generate a vast array of distinct molecular motifs that are used to convey information both in signal transduction and many other critical areas of cell biology. Diphosphoinositol phosphates, or inositol pyrophosphates, are the most recently characterized members of the inositide family. They represent a new frontier with both novel targets within the cell and novel modes of action.

Beneficial role of pancreatic microenvironment for angiogenesis in transplanted pancreatic islets.

Pancreatic islets implanted heterotopically (i.e., into the kidney, spleen, or liver) become poorly revascularized following transplantation.

Suramin inhibits the CD40-CD154 costimulatory interaction: a possible mechanism for immunosuppressive effects.

Suramin is a symmetric polysulfonated naphthylamine-benzamide urea derivative approved for the treatment of trypanosomiasis and onchocerciasis and a known P2 (ATP/UTP purine receptor) antagonist. Here, we report its ability to inhibit the important CD40-CD154 costi-mulatory interaction required for T cell activation and the development of an effective immune response. In vitro, it inhibited the binding of both human and murine CD154 (CD40L) to their receptor (CD40) even in the presence of protein-containing media and prevented the CD154-induced proliferation of human B cells as well as the corresponding increase in surface expression of CD86, CD80, CD40, and MHC class II in a concentration-dependent manner.

An ancient duplication of exon 5 in the Snap25 gene is required for complex neuronal development/function.

Alternative splicing is an evolutionary innovation to create functionally diverse proteins from a limited number of genes. SNAP-25 plays a central role in neuroexocytosis by bridging synaptic vesicles to the plasma membrane during regulated exocytosis. The SNAP-25 polypeptide is encoded by a single copy gene, but in higher vertebrates a duplication of exon 5 has resulted in two mutually exclusive splice variants, SNAP-25a and SNAP-25b.

Comparison of wireless 48-h (Bravo) versus traditional ambulatory 24-h esophageal pH monitoring.

Objective: To compare wireless with catheter-based esophageal pH recordings.

Material And Methods: Forty-five patients with symptoms suggestive of gastroesophageal reflux disease and 47 healthy volunteers were investigated in a university-affiliated hospital; 48-h wireless esophageal pH recording was performed. During the first 24 h, simultaneous traditional pH recording by catheter was undertaken.

Noninvasive high-resolution in vivo imaging of cell biology in the anterior chamber of the mouse eye.

There is clearly a demand for an experimental platform that enables cell biology to be studied in intact vascularized and innervated tissue in vivo. This platform should allow observations of cells noninvasively and longitudinally at single-cell resolution. For this purpose, we use the anterior chamber of the mouse eye in combination with laser scanning microscopy (LSM).

Real-time monitoring of apoptosis by caspase-3-like protease induced FRET reduction triggered by amyloid aggregation.

Amyloid formation is cytotoxic and can activate the caspase cascade. Here, we monitor caspase-3-like activity as reduction of fluorescence resonance energy transfer (FRET) using the contstruct pFRET2-DEVD containing enhanced cyan fluorescent protin (EYFP) linked by the caspase-3 specific cleavage site residues DEVD. Beta-TC-6 cells were transfected, and the fluoorescence was measured at 440 nm excitation and 535 nm (EYFP) and 480 nm (ECFP) emission wavelength.

Parachuting from fixed objects: descriptive study of 106 fatal events in BASE jumping 1981-2006.

Objective: To analyse the characteristics of fatal incidents in fixed object sport parachuting (building, antenna, span, earth (BASE) jumping) and create a basis for prevention.

Design: Descriptive epidemiological study.

Participants: Data on reported fatal injury events (n = 106) worldwide in 1981-2006 retrieved from the BASE fatality list.

Glutamate is a positive autocrine signal for glucagon release.

An important feature of glucose homeostasis is the effective release of glucagon from the pancreatic alpha cell. The molecular mechanisms regulating glucagon secretion are still poorly understood. We now demonstrate that human alpha cells express ionotropic glutamate receptors (iGluRs) that are essential for glucagon release.

Insulin signaling in the pancreatic beta-cell.

The appropriate function of insulin-producing pancreatic beta-cells is crucial for the regulation of glucose homeostasis, and its impairment leads to diabetes mellitus, the most common metabolic disorder in man. In addition to glucose, the major nutrient factor, inputs from the nervous system, humoral components, and cell-cell communication within the islet of Langerhans act together to guarantee the release of appropriate amounts of insulin in response to changes in blood glucose levels. Data obtained within the past decade in several laboratories have revitalized controversy over the autocrine feedback action of secreted insulin on beta-cell function.

Activin B receptor ALK7 is a negative regulator of pancreatic beta-cell function.

All major cell types in pancreatic islets express the transforming growth factor (TGF)-beta superfamily receptor ALK7, but the physiological function of this receptor has been unknown. Mutant mice lacking ALK7 showed normal pancreas organogenesis but developed an age-dependent syndrome involving progressive hyperinsulinemia, reduced insulin sensitivity, liver steatosis, impaired glucose tolerance, and islet enlargement. Hyperinsulinemia preceded the development of any other defect, indicating that this may be one primary consequence of the lack of ALK7.

Proteins in the insulin-secreting cell line MIN6 bind the imidazoline compound BL11282.

The imidazoline BL11282 stimulates insulin release and alters islet proteomes. Subcellular fractions of MIN6 cells showed that the membrane fraction exhibited binding to BL11282 on a Biacore chip and to BL11282-labelled magnetic beads. Bound material extracted from the beads showed a approximately 50 kDa differential band upon SDS-PAGE and a weaker 100 kDa band.

Automated, high-throughput assays for evaluation of human pancreatic islet function.

An important challenge in pancreatic islet transplantation in association with type 1 diabetes is to define automatic high-throughput assays for evaluation of human islet function. The physiological techniques presently used are amenable to small-scale experimental samples and produce descriptive results. The postgenomic era provides an opportunity to analyze biological processes on a larger scale, but the transition to high-throughput technologies is still a challenge.

Noninvasive in vivo imaging of pancreatic islet cell biology.

Advanced imaging techniques have become a valuable tool in the study of complex biological processes at the cellular level in biomedical research. Here, we introduce a new technical platform for noninvasive in vivo fluorescence imaging of pancreatic islets using the anterior chamber of the eye as a natural body window. Islets transplanted into the mouse eye engrafted on the iris, became vascularized, retained cellular composition, responded to stimulation and reverted diabetes.

The imidazoline RX871024 induces death of proliferating insulin-secreting cells by activation of c-jun N-terminal kinase.

An insufficient number of insulin-producing beta-cells is a major cause of defective control of blood glucose in both type 1 and type 2 diabetes. The aim of this study was to clarify whether the insulinotropic imidazolines can affect the survival of highly proliferating insulin-secreting cells, here exemplified by the MIN6 cell line. Our data demonstrate that RX871024, but not efaroxan, triggered MIN6 cell death and potentiated death induced by a combination of the pro-inflammatory cytokines interleukin-1beta, interferon- gamma and tumor necrosis factor-alpha.

Requirement of inositol pyrophosphates for full exocytotic capacity in pancreatic beta cells.

Inositol pyrophosphates are recognized components of cellular processes that regulate vesicle trafficking, telomere length, and apoptosis. We observed that pancreatic beta cells maintain high basal concentrations of the pyrophosphate diphosphoinositol pentakisphosphate (InsP7 or IP7). Inositol hexakisphosphate kinases (IP6Ks) that can generate IP7 were overexpressed.

Automated, High-Throughput Assays for Evaluation of Human Pancreatic Islet Function.

An important challenge in pancreatic islet transplantation in association with type 1 diabetes is to define automatic high-throughput assays for evaluation of human islet function. The physiological techniques presently used are amenable to small-scale experimental samples and produce descriptive results. The postgenomic era provides an opportunity to analyze biological processes on a larger scale, but the transition to high-throughput technologies is still a challenge.

Arachidonic acid signaling is involved in the mechanism of imidazoline-induced KATP channel-independent stimulation of insulin secretion.

The mechanism by which the novel, pure glucose-dependent insulinotropic, imidazoline derivative BL11282 promotes insulin secretion in pancreatic islets has been investigated. The roles of KATP channels, alpha2-adrenoreceptors, the I1-receptor-phosphatidylcholine-specific phospholipase (PC-PLC) pathway and arachidonic acid signaling in BL11282 potentiation of insulin secretion in pancreatic islets were studied. Using SUR1(-/-) deficient mice, the previous notion that the insulinotropic activity of BL11282 is not related to its interaction with KATP channels was confirmed.

Distribution of intraportally implanted microspheres and fluorescent islets in mice.

The aim of the study was to evaluate the distribution of intraportally transplanted islets in mice. We initially administered 2000 polystyrene microspheres with a diameter of 50 microm intraportally into normoglycemic C57BL/6 mice. In separate experiments other mice were injected similarly with 300 microspheres each with a diameter of 100 or 200 microm.

Glucose recruits K(ATP) channels via non-insulin-containing dense-core granules.

beta cells rely on adenosine triphosphate-sensitive potassium (K(ATP)) channels to initiate and end glucose-stimulated insulin secretion through changes in membrane potential. These channels may also act as a constituent of the exocytotic machinery to mediate insulin release independent of their electrical function. However, the molecular mechanisms whereby the beta cell plasma membrane maintains an appropriate number of K(ATP) channels are not known.