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  • 11
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In einem über 61 Tage laufenden Großversuch wurden 168 erwachsene ♂ Ratten in 8 Gruppen geteilt, deren jede anfänglich 21 Tiere enthielt. Im Verlaufe des Versuches verendeten 13 Tiere vorzeitig aus verschiedenen Gründen. Die überlebenden Tiere wurden ausgewertet. Es zeigt sich, daß nach contrainsulärer Behandlung mit Alloxan die B-Zellen des Inselapparates schwer geschädigt, zu einem großen Teil vernichtet sind. Demgegenüber vermehren sich die A-Zellen relativ und absolut, was ein Absinken des nichtnormalisierten Inselquotienten auf ¯Q=0,7983 zur Folge hat. Die alloxandiabetischen Tiere zeigen gegenüber anderen eine signifikant erhöhte Letalität. Schützt man alloxandiabetische Tiere durch chronische antithyreoidale Behandlung mit Methylthiouracil, so kommt es durch Verhinderung der diabetischen Nebennierenhyperplasie und durch Beschränkung der abundanten A-Zellvermehrung zu einer deutlichen Erhöhung der Lebenserwartung. Insgesamt waren bei 155 Ratten N total=7971 Inseln mit einem Gesamtzellbestand von 319444 A-Zellen und 414 811 B-Zellen ausgezählt worden. Dieses Material war in den 8 Gruppen nichtnormal verteilt, so daß vorerst nur die Verteilungspolygone der A- bzw. B-Zellen und der Inselquotienten nach X 2 gruppenweise miteinander verglichen werden konnten. Dieses parameterfreie Verfahren gestattet immerhin schon jetzt die Aussage, daß kombinierte antithyreoidal-antadenohypophysäre Behandlung mit Methylthiouracil + p-Hydroxypropiophenon die mittlere A-Zellzahl/Insel erhöht und somit den Inselquotienten absinken läßt. Daraus kann auf eine Vermaschung der Regelkreise für Inselorgan und Schilddrüse geschlossen und eine Abhängigkeit zumindest der insulären A-Zellen vom hypophysär kontrollierten Endocrinium vermutet werden. Weitere, nach dem gewählten Testverfahren noch nicht statistisch gesicherte Befunde verstärken diesen Eindruck. Eine Vermaschung des B-Zellregelkreises mit dem der Nebennierenrinde kann als gesichert gelten.
    Notes: Summary In male adult rats treated with alloxan, in which the B-cells of the pancreatic islets are largely destroyed, the A-cells increase in number, both relatively and absolutely. The high lethality in animals with alloxan diabetes can be reduced by chronic antithyroid treatment with methylthiouracil. This protection is based on (a) the prevention of the adrenal hyperplasia characteristic of the diabetic condition, and (b) a reduction in A-cell proliferation. A large material (7971 islets) was statistically evaluated with the result that the average number of A-cells per islet is increased after combined antithyroid-antadenohypophysis treatment with methylthiouracil and p-hydroxypropiophenon. This indicates a functional relationship between islet tissue and thyroid, more specifically a dependency of at least the A-cells on the endocrine system that is controlled by the adenohypophysis. A functional interdependence between B-cells and adrenal cortex seems to be a certainty.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 308 (1981), S. 133-136 
    ISSN: 1618-2650
    Keywords: Best. von T-2-Toxin in Lebensmitteln ; Chromatographie, Dünnschicht ; Fluorescenzspektren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Ein Verfahren zur quantitativen Bestimmung von T-2-Toxin in verschimmeltem Reis bzw. Mais durch Extraktion, dünnschicht-chromatographische Trennung und Fluorescenzintensitätsmessung der mit H2SO4 behandelten DC-Platte wird vorgestellt. Fluorescenzabsorptions- und Fluorescenzemissionsspektrum werden angegeben. Die Abhängigkeit der Mycotoxinkonzentration von der Fluorescenzintensität wird durch eine Gleichung beschrieben. Die analytische Detektion von T-2-Toxin läßt sich durch ein 4-(p-Nitrobenzyl)pyridin-Derivat und dessen Absorptionsspektrum bestätigen. Versuche mit zugesetztem T-2-Toxin zeigten einen Analysenfehler von weniger als 10%.
    Notes: Summary A procedure is described for the determination of T-2 toxin in extracts from mouldy rice and maize by thin-layer chromatography (TLC) and subsequent fluorescence intensity measurement of the H2SO4-treated TLC plates. The fluorescence absorption and emission spectra are presented. The dependence of the concentration of the mycotoxin on fluorescence intensity is described by an equation. The detection of T-2 toxin can be confirmed by colour reaction with 4-(p-nitrobenzyl)pyridine yielding a blue derivative. Experiments with added toxin revealed an analytical error smaller than 10%.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1371-1377 
    ISSN: 1434-193X
    Keywords: Homoenolate equivalents, chiral ; Alkylation ; 1-Aminoallyl anions, chiral ; β-Methyl ketones, chiral ; Asymmetric synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-Substituted aliphatic ketones 10 have been obtained in excellent optical yields by alkylation of the aminoallyllithium compound endo-8, a homoenolate equivalent of hexane-3-one, using prolinol ether (SMP) as the chiral auxiliary. The intermediate endo-8 was generated by tin-lithium exchange of the 3-stannylated enamine 7a with butyllithium. An improved hydrolysis procedure for the resulting enamines is described. Some mechanistic implications with respect to the formation as well as the alkylation of endo-8 are discussed.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 122 (1989), S. 1263-1275 
    ISSN: 0009-2940
    Keywords: Rotational barriers ; Olefins, strained ; Heat of hydrogenation ; Force-field calculation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rotational Barriers of Strained OlefinesFor the olefins 1-8 heats of formation have been derived from heats of hydrogenation and force-field calculations, respectively. From the kinetics of their geometrical isomerisation the corresponding values for the transition states were obtained. The rotational barriers, which vary by nearly 30 kcal/mol, can be described by a unique torsional potential (65.9 ± 0.9 kcal/mol), which is independent of the degree of substitution, if a correction is made for the steric energy contribution in the ground- and transition-states.
    Notes: Für die Olefine 1-8 wurde durch Hydrierwärme-Messung bzw. Kraftfeld-Rechnung die Bildungsenthalpie der Grundzustände und durch kinetische Analyse der geometrischen Isomerisierung die der Übergangszustände ermittelt. Die um fast 30 kcal/mol variierenden Rotationsenthalpien lassen sich mit einer einheitlichen, vom Substitutionsgrad unabhängigen Torsionsbarriere (65.9 ± 0.9 kcal/mol) beschreiben, wenn um die sterischen Energiebeiträge der Grund- und Übergangszustand korrigiert wird.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sodium butyrate affects cell differentiation in confluent epidermal keratinocyte cultures by considerably increasing the spontaneous formation of cross-linked envelopes in normal human keratinocytes (NHK). It also favors the development of envelope competence in the Simian virus-40 (SV-40)-transformed human foreskin keratinocyte line SV-K14. It completely abolishes the inhibitory effect of serum and retinoic acid on the expression of plasma membrane-associated transglutaminase. However, other markers of epidermal differentiation that are also under the control of retinoids such as keratins or the enzyme cholesterol sulfotransferase are not affected by butyrate. The level of the cellular retinoic acid binding protein (CRABP) is considerably increased in its presence. Butyrate does not interfere with the binding of retinoids to their cellular binding proteins. Our observations suggest that sodium butyrate stimulates cornified envelope formation via the induction of the plasma membrane-associated transglutaminase required for cornified envelope synthesis and, additionally, by abolishing the inhibitory effect of retinoids on the expression of this enzyme.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Publication Date: 2021-09-21
    Description: Der Band thematisiert Entscheiden als eine soziale Praxis, die keineswegs selbstverständlich sondern in hohem Maße voraussetzungsvoll ist und die mit unterschiedlichen Zumutungen einhergeht. Entscheiden nimmt je nach sozialen Umständen ganz unterschiedliche Formen an und unterliegt demnach dem historischen Wandel. Die Beiträge des Bandes gehen anhand ausgewählter Fallbeispiele, die vom mittelalterlichen Europa bis hin zum gegenwärtigen Indien reichen, unterschiedlichen Aspekten von Kulturen des Entscheidens nach. Sie nehmen Narrative und Praktiken des Entscheidens ebenso in den Blick wie den Einsatz von Ressourcen in Prozessen des Entscheidens und diskutieren Ansätze, Entscheiden in einer geistes- und kulturwissenschaftlichen Perspektive zu analysieren. Der Band zeigt so die vielfältigen Möglichkeiten auf, wie Entscheiden untersucht werden kann, wenn dieses als eine historisch wandelbare soziale Praxis und als kulturell diverses Phänomen begriffen wird.
    Keywords: Education ; Decision-making & Problem Solving ; bic Book Industry Communication::J Society & social sciences::JN Education
    Language: German
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  • 17
    Publication Date: 2008-06-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 18
    Publication Date: 2006-10-30
    Print ISSN: 0031-9155
    Electronic ISSN: 1361-6560
    Topics: Biology , Medicine , Physics
    Published by Institute of Physics
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  • 19
    Publication Date: 2015-05-29
    Description: Several gap junction connexins have been shown to be essential for appropriate placental development and function. It is known that the expression and distribution of connexins change in response to environmental oxygen levels. The placenta develops under various oxygen levels, beginning at a low oxygen tension of approximately 2% and increasing to a tension of 8% after the onset of the uteroplacental circulation. Moreover, it has been shown that during preeclampsia placentas are subjected to chronic hypoxia. Therefore, we investigated oxygen sensitivity of placental connexins 43 and 46. Using the trophoblast cell line Jar we demonstrated that the expression of connexin43 increased during acute hypoxia but decreased during chronic hypoxia. Chronic hypoxia resulted in the translocation of connexin43 from the membrane to the cytoplasm and in a reduction in its communication properties. In contrast, the expression of connexin46 was down-regulated during chronic hypoxia and was translocated from perinuclear areas to the cell membrane. Hypoxia-inducible factor (HIF) knockdown showed that the translocation of connexin43 but not that of connexin46 was HIF-2α dependent and was mediated by phosphoinositide 3-kinase. The upregulation of connexin43 in combination with the down-regulation of connexin46 was confirmed in placental explants cultivated under low oxygen and in placentas with early-onset preeclampsia. Taken together, in Jar cells placental connexins 43 and 46 are regulated during periods of low oxygen in opposite manners. The oxygen sensing of connexins in the trophoblast may play a role in physiological and pathophysiological oxygen conditions and thus may contribute to preeclampsia. This article is protected by copyright. All rights reserved
    Electronic ISSN: 0091-7419
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Wiley
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  • 20
    Publication Date: 2010-01-12
    Print ISSN: 0897-4756
    Electronic ISSN: 1520-5002
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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