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  • 1
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract On guinea-pig heart we investigated whether cyclic AMP serves as a messenger for H1- and/or H2-mediated responses to histamine. (1) On papillary muscle histamine elicited positive inotropic responses which were antagonized by burimamide but not by promethazine. The stimulation of H2-receptors was not only associated with an increase in contractility but also with an increase in cAMP. As shown by the time course of effects for 10−5 M histamine, the maximal increase in cAMP preceded the maximum in contractility. The mechanical and biochemical responses to histamine were potentiated by the phosphodiesterase inhibitor papaverine, but antagonized by burimamide. (2) On the left guinea-pig atrium containing H1-receptors the inotropic response to histamine (10−5 M) was not accompanied by increases in cAMP at stimulation frequencies of 0.5 and 2 Hz, respectively. In addition, in the presence of papaverine (3×10−5 M) no change in the cyclic AMP level occurred after application of histamine. Papaverine by itself, however, concomitantly increased contractility and cyclic AMP at a stimulation frequency of 0.5 Hz. In contrast, at 2 Hz papaverine increased only cAMP leaving the contractility unchanged. At this frequency the well-known Ca2+-antagonistic effect comes into prominence, thus masking the positive inotropic effect atributable to the inhibition of the phosphodiesterase. (3) On the right guinea-pig atrium the mediation of the positive charonotropic response to histamine by H2-receptors which is partly involved in the inotropic effect via the frequency-force relationship does not lead to a concomitant increase in cAMP. Also, in the presence of papaverine, histamine had no influence on the cAMP. However, papaverine potentiated the cardioacceleration produced by histamine. Although it is very likely that the cAMP in the sinus node rises, we were not able to detect an increase in cAMP in the whole atrial tissue. From the present results the conclusion can be drawn that the mediation of the inotropic effect due to stimulation of H2-receptors by histamine is associated with an increase of cyclic AMP, whereas that of H1-receptors is not. The view that cAMP may be the second messenger in the chronotropic action of histamine needs further elucidation by experiments on sino-atrial cells.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 116 (1978), S. 452-464 
    ISSN: 1420-9136
    Keywords: Trace gases ; Atmosphere ; Sources and Sinks ; Methane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In 1972 average mixing ratio of methane in the troposphere was 1.41 ppm and 1.3 ppmv for the northern and southern hemisphere, respectively, which corresponds to a total amount of 4×1015 g of CH4 present in the atmosphere. Most is of recent biologic origin.14C analyses show that no more than 20 percent is released by fossil sources. The various ecosystems producing CH4 are discussed and the total annual production is estimated to lie between 5.5×1014 g/yr and 11×1014 g/yr. The corresponding turnover times for atmospheric CH4 range from 4 to 7 yrs. The destruction of CH4 takes place mainly in the troposphere, most probably through the reaction of CH4 + OH ↠ CH3 + H2O. About 10 percent of the CH4 is destroyed in the stratosphere. The CH4 cycle contributes on the order of 1 percent to the atmospheric carbon cycle.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1420-9136
    Keywords: Electron paramagnetic resonance ; Free radicals ; Matrix isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract With some special adaptations the technique of matrix isolation followed by detection through electron paramagnetic resonance (EPR) can also be used for the measurement of atmospheric radical concentrations. A light weight cryogenic sampling device has been constructed. It uses condensation of atmospheric CO2 or H2O at 77 K for matrix formation and trapping of the radicals. The sampler has been flown on a balloon for stratospheric sampling. First data on stratospheric, HO2 and NO2 at 32 km altitude have been obtained on a flight on 8 August 1976 and will be reported.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 121 (1976), S. 81-87 
    ISSN: 1432-1076
    Keywords: Na, K-ATPase ; Salt-losing Syndrome ; Tubular sodium reabsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wir berichten über zwei Schwestern mit kongenitalem renalem Salzverlustsyndrom. Das Serum-Na war stark herabgesetzt, das Serum-K erhöht. Auch bei stark vermindertem Serum-Na-Werten wurde Kochsalz fortgesetzt im Urin ausgeschieden. Im übrigen war die Nierenfunktion intakt; Kreatinin- und Jod-Hippuran-Clearance ergaben normale Werte. Eine primäre Nebennierenrindenstörung konnte ausgeschlossen werden. Das Cortisol im Plasma war normal, Aldosteron und Renin waren kompensatorisch erhöht. Die Medikation von DOCA blied ohne Erfolg. Das erste Kind verstarb in einem auswärtigen Krankenhaus. Die Schwester konnte mit hohen Kochsalzzulagen zum Gedeihen gebracht werden. In dem bioptischen Nierenpräparat des zweiten Kindes wurde histologisch außer einer mäßigen Hyperplasie der juxtaglomerulären Apparate kein pathologischer Befund erhoben. In den durch Mikrodissektion gewonnenen Tubuli war, abgesehen von geringen Aktivitäten im aufsteigenden Schenkel der Henleschen Schleife, keine Na, K-ATPase nachweisbar. Dieser Befund erklärt höchstwahrscheinlich die renalen Salzverluste, da das Enzym für den Transport von Na und K durch die Tubuluszelle notwendig ist.
    Notes: Abstract In the serum of two infant sisters with a congenital renal salt-losing syndrome, Na was rather low and K considerably increased. Even with Na levels of 126 mval/l, sodium was excreted in the urine. Creatinine and hippurate clearances were normal. Primary disturbances of the steroid metabolism were not detectable; plasma cortisol was normal, aldosterone and renin were compensatorily increased. Treatment with DOCA was unsuccessful. Whereas the first infant died (in another hospital), the second one throve well with high oral substitution of NaCl. There were no pathological findings other than a moderate hyperplasia of the juxtaglomerular apparatus, in a kidney biopsy. Except for minimal activity in the ascending limb of Henle's loop, there was no membrane bound Na, K-ATPase in the microdissected tubules. This finding most probably explains the renal salt loss, as this enzyme is necessary for the transcellular flow of sodium and potassium.
    Type of Medium: Electronic Resource
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  • 5
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    Unknown
    Berlin : Periodicals Archive Online (PAO)
    Deutsche Zeitschrift für Philosophie. 23:12 (1975) 1648 
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 259 (1976), S. 157-158 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] RECENTLY evidence1 showed that microorganisms can transform certain lead compounds into Me4Pb; addition of Me3PbOAc to sediment samples apparently always increased the production of Me4Pb. The addition, of lead(II) compounds did not, however, lead to definite effects, and with pure bacterial ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 63 (1979), S. 245-251 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The activities of N-acetyl-β,d-glucosaminidase (NAG, EC 3.2.1.30),β,d-galactosidase (β-gal, EC 3.2.1.23) and acid phosphatase (ac-Pase, EC 3.1.3.2) were measured in the glomeruli, five segments of the proximal and four segments of the distal tubule of normal male Wistar rats. The activities of NAG andβ-gal are 3- to 5-fold higher in the first part of the proximal tubule than in other segments and very low in glomeruli. We propose that the distribution of these two glycosidases reflects the contribution of the different tubular segments to the reabsorption of glycoproteins. The maximal activity of ac-Pase was found in the straight part of the proximal tubule. It was only 1.5-fold higher than in the distal tubule. Moreover, the activity in glomeruli is rather high. We conclude that ac-Pase is not primarily involved in the handling of reabsorbed molecules.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Complex Catalysis. X. α-Olefin Insertion into the Trihapto-allyl-nickel(II) Group: Synthesis and Properties of Bis(pentahapto-1,8-nonadiene-5-yl-nickel(II)-difluorophosphate)By reaction of (h3-C3H5)2Ni with difluorophosphoric acid in ether under addition of 1,5-hexadiene bis(pentahapto-1,8-nonadiene-5-yl-nickel(II)-difluorophosphate) could be synthesized in good yield, proving thereby preparatively the 1,2-addition of the trihapto-allyl-nickel(II) fragment to the double bond of an α-olefin for the first time.
    Notes: Durch Reaktion von (h3-C3H5)2Ni mit Difluorophosphorsäure in Ether unter Zusatz von 1,5-Hexadien konnte in guter Ausbeute Bis(pentahapto-1,8-nonadien-5-yl-nickel(II)-difluorophosphat) dargestellt und damit erstmalig die 1,2-Addition des Trihaptoallyl-nickel(II)-Fragments an die Doppelbindung eines α-Olefins präparativ bewiesen werden.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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