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  • 1
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    Adenosine diphosphate as an intracellular regulator of insulin secretion (1996)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1996-06-21
    Description: Adenosine triphosphate (ATP)-sensitive potassium (KATP) channels couple the cellular metabolic state to electrical activity and are a critical link between blood glucose concentration and pancreatic insulin secretion. A mutation in the second nucleotide-binding fold (NBF2) of the sulfonylurea receptor (SUR) of an individual diagnosed with persistent hyperinsulinemic hypoglycemia of infancy generated KATP channels that could be opened by diazoxide but not in response to metabolic inhibition. The hamster SUR, containing the analogous mutation, had normal ATP sensitivity, but unlike wild-type channels, inhibition by ATP was not antagonized by adenosine diphosphate (ADP). Additional mutations in NBF2 resulted in the same phenotype, whereas an equivalent mutation in NBF1 showed normal sensitivity to MgADP. Thus, by binding to SUR NBF2 and antagonizing ATP inhibition of KATP++ channels, intracellular MgADP may regulate insulin secretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nichols, C G -- Shyng, S L -- Nestorowicz, A -- Glaser, B -- Clement, J P 4th -- Gonzalez, G -- Aguilar-Bryan, L -- Permutt, M A -- Bryan, J -- New York, N.Y. -- Science. 1996 Jun 21;272(5269):1785-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. cnichols@cellbio.wustl.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8650576" target="_blank"〉PubMed〈/a〉
    Keywords: *ATP-Binding Cassette Transporters ; Adenosine Diphosphate/*metabolism/pharmacology ; Adenosine Triphosphate/*metabolism/pharmacology ; Amino Acid Sequence ; Animals ; Cell Line, Transformed ; Cercopithecus aethiops ; Cricetinae ; Diazoxide/pharmacology ; Humans ; Hyperinsulinism/genetics ; Hypoglycemia/genetics ; Insulin/*secretion ; Islets of Langerhans/metabolism ; Molecular Sequence Data ; Patch-Clamp Techniques ; Point Mutation ; Potassium Channels/drug effects/genetics/*metabolism ; *Potassium Channels, Inwardly Rectifying ; Receptors, Drug/drug effects/genetics/*metabolism ; Rubidium/metabolism ; Sulfonylurea Receptors ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Nuclear magnetic resonance imaging of the vitreous body (1984)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1984-01-27
    Description: Imaging with proton nuclear magnetic resonance is a valuable new tool for studying the vitreous body of the eye. It is particularly suited for the detection of vitreal liquefaction and intraocular hemorrhage because of the dependence of the signal on the physical environment of water. Conversely, the vitreous body provides a new model for studying changes in proton relaxation times of protein solutions in biological systems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gonzalez, R G -- Cheng, H M -- Barnett, P -- Aguayo, J -- Glaser, B -- Rosen, B -- Burt, C T -- Brady, T -- 1-K04-CA00848-02/CA/NCI NIH HHS/ -- 1R01-EY04424/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1984 Jan 27;223(4634):399-400.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6318321" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cattle ; Eye Diseases/pathology ; *Magnetic Resonance Spectroscopy ; Microbial Collagenase ; Retinal Hemorrhage/*pathology ; Vitreous Body/*pathology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Basement membrane collagen: degradation by migrating endothelial cells (1983)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1983-07-15
    Description: One of the first steps in neovascularization is dissolution of the basement membrane at the point of endothelial outgrowth. An assay was developed to determine whether basement membrane collagens (types IV and V) are degraded by endothelial cells migrating toward a chemotactic stimulus. Fetal bovine endothelial cells were placed on one side of a filter containing the collagen substrate, and a chemoattractant derived from retinal extracts was placed on the opposite side. Degradation of both type IV and type V collagens was observed when the retinal factor was placed on the side of the filter opposite the endothelial cells. Metalloproteinases that cleaved type IV and type V collagens could be extracted from the endothelial cells with detergents. Such endothelial cell-associated (possibly membrane-bound) proteinases may locally disrupt the basement membrane and facilitate the outgrowth of capillary sprouts toward the angiogenic stimulus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kalebic, T -- Garbisa, S -- Glaser, B -- Liotta, L A -- New York, N.Y. -- Science. 1983 Jul 15;221(4607):281-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/6190230" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Basement Membrane/*metabolism ; Cattle ; Cell Movement ; Chemotaxis ; Collagen/*metabolism ; Endothelium/metabolism ; Neovascularization, Pathologic ; Retina/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    On the value of surface saturated area dynamics mapped with thermal infrared imagery for modeling the hillslope-riparian-stream continuum (2016)
    Wiley
    Details
    Publication Date: 2016-10-08
    Description: The highly dynamic processes within a hillslope-riparian-stream (HRS) continuum are known to affect streamflow generation, but are yet not fully understood. Within this study, we simulated a headwater HRS continuum in western Luxembourg with an integrated hydrologic surface subsurface model (HydroGeoSphere). The model was set up with thorough consideration of catchment-specific attributes and we performed a multi criteria model evaluation (4 years) with special focus on the temporally varying spatial patterns of surface saturation. We used a portable thermal infrared (TIR) camera to map surface saturation with a high spatial resolution and collected 20 panoramic snapshots of the riparian zone (approx. 10 m x 20 m) under different hydrologic conditions. Qualitative and quantitative comparison of the processed TIR panoramas and the corresponding model output panoramas revealed a good agreement between spatiotemporal dynamic model and field surface saturation patterns. A double logarithmic linear relationship between surface saturation extent and discharge was similar for modeled and observed data. This provided confidence in the capability of an integrated hydrologic surface subsurface model to represent temporal and spatial water flux dynamics at small (HRS continuum) scales. However, model scenarios with different parameterizations of the riparian zone showed that discharge and surface saturation were controlled by different parameters and hardly influenced each other. Surface saturation only affected very fast runoff responses with a small volumetric contribution to stream discharge, indicating that the dynamic surface saturation in the riparian zone does not necessarily imply a major control on runoff generation. This article is protected by copyright. All rights reserved.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
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    Revisiting afro-alpine Lake Garba Guracha in the Bale Mountains of Ethiopia: rationale, chronology, geochemistry, and paleoenvironmental implications (2020)
    Springer Netherlands
    Details
    Publication Date: 2023-06-08
    Description: Previous paleolimnological studies demonstrated that the sediments of Garba Guracha, situated at 3950 m asl in the afro-alpine zone of the Bale Mountains of Ethiopia, provide a complete Late Glacial and Holocene paleoclimate and environmental archive. We revisited Garba Guracha in order to retrieve new sediment cores and to apply new environmental proxies, e.g. charcoal, diatoms, biomarkers, and stable isotopes. Our chronology is established using 210Pb dating and radiocarbon dating of bulk sedimentary organic matter, bulk n-alkanes, and charcoal. Although bedrock was not reached during coring, basal ages confirm that sedimentation started at the earliest ~ 16 cal kyr BP. The absence of a systematic age offset for the n-alkanes suggests that “pre-aging” is not a prominent issue in this lake, which is characterised by a very small afro-alpine catchment. X-ray fluorescence scans and total organic carbon contents show a prominent transition from minerogenic to organic-rich sediments around 11 cal kyr BP coinciding with the Holocene onset. While an unambiguous terrestrial versus aquatic source identification seems challenging, the n-alkane-based Paq proxy, TOC/N ratios, δ13C values, and the sugar biomarker patterns suggest a predominantly autochthonous organic matter source. Supraregional climate events, such as the African Humid Period, the Younger Dryas (YD), a 6.5 cal kyr BP short drying event, and the 4.2 cal kyr BP transition to overall drier climate are recorded in our archive. The Garba Guracha record suggests that northern hemisphere forcings played a role in the Eastern African highland paleoclimate.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Keywords: ddc:551 ; Paleolimnology ; Afro-alpine ; Radiocarbon dating ; XRF scanning ; Sedimentation rate ; Biomarkers
    Language: English
    Type: doc-type:article
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  • 6
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    Reconstructing the Paleo‐Ecological Diet of Snow Petrels (Pagodroma nivea) From Modern Samples and Fossil Deposits: Implications for Southern Ocean Paleoenvironmental Reconstructions (2023)
    Details
    Publication Date: 2024-02-15
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉Snow petrels (〈italic〉Pagodroma nivea〈/italic〉), which are endemic to the Antarctic region, produce proventricular stomach oil from ingested food for feeding purposes but also spit the oil in the immediate surrounds of the nests, where it forms encrustations over time (Antarctic mumiyo). These deposits provide a unique opportunity to understand the paleo‐ecological diet of snow petrels and because the seabirds forage in the ocean, they potentially provide an archive of past marine environmental conditions in the Southern Ocean. For validating methods for reconstructions we use compositional data obtained on modern stomach oils and DNA data from fecal samples of snow petrels. We find that the distribution of carboxylic acid compounds in modern stomach oils and in the fossil deposits are consistent with variable contributions of fish and krill, which are the main constituents of modern snow petrel diet, and allows inference of past changes in snow petrel diet from the fossil record. Analyses of mumiyo deposits from six regions in East Antarctica reveal systematic differences in the isotopic composition of organic matter (δ〈sup〉13〈/sup〉C and δ〈sup〉15〈/sup〉N) and carboxylic acid patterns. This may suggest regional and/or temporal variability in the composition of snow petrels diet, likely differing in response to the prevailing environmental conditions in the foraging range of the birds, such as sea‐ice variability, polynya activity and primary productivity. Our study provides confidence for using these approaches for broader scale paleo‐studies in the future and for an assessment of the temporal changes and regional variability in snow petrel diet.〈/p〉
    Description: Plain Language Summary: To better understand interactions of biological and physical processes in Antarctic marine ecosystems, we investigate fossil deposits of stomach oil of snow petrels for their use as a geological archive for past environmental changes. The deposits form over time in the surroundings of the nesting cavities of snow petrels, which produce stomach oil from ingested food but also spit it at nest robbers. In fresh oil the lipid and isotopic composition can be traced back to the composition of snow petrel food, such as variable proportions of fish and krill. From comparing the lipid and δ〈sup〉13〈/sup〉C‐isotopic composition of modern oil to fossil deposits we suggest it is possible to identify changes in the diet of snow petrels in the fossil record. Since the composition of the diet is closely linked to the prevailing environmental conditions in the marine foraging region of the birds, such as summer sea ice extent, this information can be used for paleoenvironmental reconstructions. Our study of deposits from widely separated regions in Antarctica shows that there are spatial and temporal differences in the composition of stomach oil deposits, likely related to the prevailing environmental conditions. This finding underpins the application of our approach.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Modern stomach oil and feces of snow petrels are used to validate paleo‐proxies for environmental reconstructions in East Antarctica〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Biomarkers and isotopic composition of fossil stomach oil deposits of snow petrels reflect past composition in diet〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Changes in the composition of the paleo‐ecological diet reflect variations of environmental conditions in the coastal Southern Ocean〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Australian Antarctic Division http://dx.doi.org/10.13039/501100005108
    Description: https://doi.org/10.1594/PANGAEA.951357
    Keywords: ddc:560 ; Antarctica ; paleoclimate ; sea ice ; fatty acids ; stable isotopes ; stomach oil deposits
    Language: English
    Type: doc-type:article
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  • 7
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    Bestimmung substanzspezifischer d13C-Verhältnisse in Ligninphenolen mittels Gaschromatographie-Verbrennungs-Isotopenmassenspektrometrie (GC-C-IRMS) (2002)
    In:  EPIC3DBG-Workshop, Stabile Isotope in der Bodenkunde, 11-12.3.2002, Göttingen 11. und 12. März 2002.
    Details
    Publication Date: 2019-07-17
    Description: Die isotopische Zusammensetzung einer Substanz ist eine Stoffeigenschaft und nicht von der gemessenen Konzentration abhängig. Dennoch fanden wir bei der substanzspezifischen d13C-Analyse von phenolischen Ligninoxidationsprodukten eine Abhängigkeit des d13C-Wertes von der injizierten Substanz-Menge. Durch systematische Untersuchung der einzelnen Gerätekomponenten der Gaschromatographie-Verbrennungs-Isotopenmassenspektrometrie-(GC-C-IRMS)-Konfiguration konnten die Ursachen des mengenabhängigen Isotopen-Signals lokalisiert und mittels geeigneter Parameterwahl weitgehend minimiert werden. Die durchgeführten Experimente ergaben, dass die Isotopenfraktionierung weder am IRMS noch am Oxidationsreaktor stattfindet. Allerdings führen Veränderungen der Injektionsparameter, wie Splitfluss-Rate, Splitless-Zeit und die Spritzenlänge und deren Eintauchtiefe zu deutlich veränderter Abhängigkeit des d13C-Wertes von der injizierten Stoffmenge. Durch Optimierung dieser Parameter konnte die Injektionsmengenabhängigkeit reduziert, jedoch nicht vollständig eliminiert werden, die verbleibende Abhängigkeit konnte durch Anpassung logarithmischer Kalibrierfunktionen rechnerisch korrigiert werden. Angewandt wurde die so optimierte Methode zur substanzspezifischen Bestimmung des d13C-Wertes von phenolischen Ligninoxidationsprodukten als terrestrischen Biomarker höherer Pflanzen innerhalb einer Paläostudie.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 8
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    Amount-dependent isotopic fractionation during compound-specific isotope analysis (2003)
    In:  EPIC3Rapid communications in mass spectrometry, 17, pp. 970-977, ISSN: 0951-4198
    Details
    Publication Date: 2019-07-17
    Description: The performance of a gas chromatography-combustion-isotope ratio mass spectrometry system (GC-C-IRMS) with respect to the dependence of d13C values on the amount of sample is presented. Particular attention is paid to the localization of the amount-dependent isotopic fractionation within the system. Injection experiments with varying amounts of gases (CO2, n-hexane, and toluene) revealed that neither the detector unit nor the combustion reactor, but rather the conditions in the split/splitless injector, contributed to this effect. Although optimization of injector parameters was performed and a reduction of this adverse effect from 3 to 1 was achieved, it was not possible to eliminate isotopic fractionation completely. Consequently, additional injector parameters have to be considered and adjusted to achieve injection conditions free of fractionation. For routine analysis of the compound-specific d13C analysis of different biomarkers in many environmental samples, perfect optimization may not always be reached. Therefore, in order to prevent systematic errors in the measured d13C values due to different sample concentrations, it is suggested that correction for the remaining unknown amount-dependent fractionation can be made by means of co-analyzing standards of varying analyte concentrations and known d13C values. Residual overall amount-dependent isotope-fractionation can thus be corrected mathematically.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    d13C of individual lignin phenols in a postglacial lake deposit in Nepal: A reassessment of the vegetation/climate reconstruction based on bulk-d13C (2002)
    In:  EPIC3ACS NATIONAL MEETING, Stable Isotope Signatures for Establishing Paleoenvironmental Change, Session II: Isotopes for Environmental Change Over Long Timescales, April 2002, Orlando, USA.
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
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    Sequestration and turnover of plant- and microbially derived sugars in a temperate grassland soil during 7 years exposed to elevated atmospheric pCO2 (2007)
    In:  EPIC3Global Change Biology Volume 13, Issue 2, February 2007, Pages 478-490,13, 2, pp. 478-490
    Details
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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