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Tracing charge transfer in argon dimers by XUV-pump IR-probe experiments at FLASH
Charge transfer (CT) at avoided crossings of excited ionized states of argon dimers is observed using a two-color pump-probe experiment at the free-electron laser in Hamburg (FLASH). The process is initiated by the absorption of three 27-eV-photons from the pump pulse, which leads to the population of Ar2+*-Ar states. Due to nonadiabatic coupling between these one-site doubly ionized states and tw
H 2 influence on experimental diabetes induced by heterologous and homologous immunization and by virus
Alloxan cytotoxicity in vitro : Microscope photometric analyses of trypan blue uptake by pancreatic islet cells in suspension
Suspensions of islet cells were prepared by shaking pancreatic islets from non inbred ob/ob mice in a Ca 2+ free buffer. The cells were incubated with or without 20 mM alloxan, and subsequently with Trypan Blue. The uptake of Trypan Blue by cell nuclei was analysed by microscope photometry and by counting the frequency of cells appearing stained on visual inspection. Cells classified as stained o
Scanning electron microscopy of the surface of dispersed B cells in suspension
The pancreatic β cell recognition of insulin secretagogues. XII. Insulin release in response to halogenated hexosamines
The effects of N iodoacetyl 2 amino 2 deoxy (D) glucose and various N bromoacetylglycosylamines on the release of insulin from microdissected pancreatic islets of non inbred ob/ob mice were studied. N Bromoacetyl β (D) glucosylamine (10 m(M)) initiated insulin release in the absence of (D) glucose and, at concentrations of 2.5-10 m(M), but not 20 m(M), potentiated insulin release in response to 10
Preparation and characterization of plasma membrane-enriched fractions from rat pancreatic islets
Methods have been developed for the isolation on a semi-micro scale of a plasma membrane-enriched fraction from rat islets of Langerhans. An important feature of these experiments is the use of 125I-labeled wheat germ agglutinin as a specific probe for plasma membrane-containing fractions. The partly purified plasma membrane fraction had a density in sucrose of about 1.10 and was enriched in the a
Evaluation of the viability of dispersed B cells in suspension
The dynamics of insulin release from mouse pancreatic islet cells in suspension
The overall dynamics of glucose-induced insulin release was strikingly similar in dispersed cells and intact islets perifused in parallel. Both preparations exhibited a latency of 1-2 min, after which period there was a brisk rise of insulin release followed by a sustained second phase. During the second phase, insulin release from dispersed cells attained a stable plateau rate, whereas the releas
Studies on the function of pancreatic islet cell membranes.
Pancreatic islets rich in beta-cells were isolated from non-inbred ob/ob-mice and used for studying various aspects of the function of the plasma membrane. A review is given of the authors' work along the following lines: the role of transmembrane transport or membrane binding in the recognition of insulin-releasing sugars, amino acids, sulfonylureas, and sulphydryl-blocking agents; the role of cy
Stimulation of insulin release by thiols
The effects of thiol compounds on insulin release were studied in microdissected pancreatic islets of non-inbred ob/ob mice. In control experiments the reactivity of thiols against 6,6′-dithiodinicotinic acid and the degradation of mouse insulin were measured. At a concentration of 0.1 mM, 1-thio-D-glucose or reduced glutathione potentiated the insulin-releasing action of 10 mM D-glucose without a
Glucagon and insulin release from the allografted canine pancreas
Six previously pancreatectomized dogs were transplanted with ductligated, pancreatic allografts. Glucagon and insulin levels in the venous outflow from the graft and in the systemic circulation were determined during the first 60 minutes after transplantation. Two of the dogs were subjected to L-arginine stimulation 5 days after transplantation and the glucagon levels in the venous outflow from th
The use of dispersed pancreatic islet cells in measurements of transmembrane transport
Suspensions of dispersed islet cells were prepared by shaking collagenaseisolated pancreatic islets of ob ob-mice in Ca2+-free buffer. The dispersed cells exhibited a glucose uptake with stereospecificity for the d isomer and concentrated Rb+ about 30-fold from a medium containing 70 μm RbCl. These results compare well with previous observations on unbroken islets and indicate that the dispersion
Influence of neuraminidase treatment on the release of insulin and the islet content of insulin, sialic acid and adenosine 3',5' cyclic monophosphate
The pancreatic β cell recognition of insulin secretagogues : does cyclic AMP mediate the effect of glucose?
Insulin release and the content of cAMP were studied in microdissected pancreatic islets of non inbred ob/ob (obese) mice. In the absence of 3 isobutyl 1 methylxanthine, a phosphodiesterase inhibitor, 20 mM glucose had no effect on cAMP save a very small initial rise detectable by a freeze stop perifusion technique only. However, combined with this methylxanthine, 20 mM glucose produced significan
Cytotoxic effects of a thiol reactive ferritin compound on isolated pancreatic β cells and the protective action of L cysteine
The effects of an electron dense thiol reagent, Hg phenylazo ferritin, on β cell ultrastructure was studied in cell suspensions from mouse pancreatic islets. This type of thiol reagent induced severe damage in the β cells. The ferritin particles were traced with the electron microscope and found to be bound to the plasma membrane as well as to various cytoplasmic structures. The β cell cytotoxic a
Effects of pancreozymin and secretin on insulin release and the role of the exocrine pancreas
Mouse pancreatic islets microdissected free from, or surrounded by, exocrine cells were used to study the effects of secretin and choleeystokinm-pancreozymin on insulin release. Both secretin and cholecystokinin-pancreozymin potentiated glucose-stimulated insulin release regardless of whether exocrine cells were present. The results fail to support the idea that the presence of the exocrine parenc
The preparation of, and studies on, free cell suspensions from mouse pancreatic islets
Pancreatic islets, isolated from the pancreas of obese-hyperglycemic mice, were used to prepare free islet cells in suspension. Batches of 100 islets were disrupted by mechanical shaking for 10 sec in a Ca2+-free HEPES-buffered Krebs-Ring'er medium containing 1 mM EGTA. From 200-500 islets, about 2.2×106 cells could be obtained in suspension, corresponding to a yield of roughly 55% as calculated f
Assessment of Ultra-Short Heart Variability Indices Derived by Smartphone Accelerometers for Stress Detection
Body acceleration due to heartbeat-induced reaction forces can be measured as mobile phone accelerometer (m-ACC) signals. Our aim was to test the feasibility of using m-ACC to detect changes induced by stress by ultra-short heart rate variability (USV) indices (standard deviation of normal-to-normal interval-SDNN and root mean square of successive differences-RMSSD). Sixteen healthy volunteers wer
Influence of the mutation "diabetes" on insulin release and islet morphology in mice of different genetic backgrounds
Mice, 7-8-mo old, of the C57BL/KsJ-db strain and homozygotic for the mutant gene db, exhibited marked hyperglycemia and moderately elevated serum insulin levels. Light and electron microscopy provided evidence of a slightly decreased proportion of β cells in the pancreatic islets, irregular islet architecture with intraislet ducts, and degenerative as well as hypertrophic changes in the individua