15 Fakultätsübergreifend / Sonstige Einrichtung

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    Reduced cavitation-induced cellular damage by the antioxidative effect of vitamin E
    (1994) Suhr, Dierk; Brümmer, Franz; Irmer, Ulrich; Schlachter, Manfred; Hülser, Dieter F.
    Fragmentation of human urinary and biliary stones by shock waves in extracorporeal lithotripsy is accompanied by tissue damage. Both the fragmentation as well as the side effects are often attributed to cavitation. The hazardous potential of cavitation is not only of a physical nature but also of a chemical nature, because of the generation of free radicals, e.g. ·OH, ·H and ·O2. After the application of shock waves, we have demonstrated cavitation-generated free radicals in cell-free solutions and also in the surviving and intact suspended MGH-U1 cells by hydroethidine measurements. Under electron microscopical inspection, the same cells exhibited perinuclear cisternae, damaged mitochondria and numerous intracellular vacuoles. The contribution of free radicals to cell damage was investigated by reducing the vitamin E level in rats by a tocopherol free diet and by incubating L1210 cells in a tocopherol enriched medium. After 250 shock waves, ex vivo erythrocytes revealed a 75% increase in total cell disruption over cells from non-depleted rats. The in vitro experiments with L1210 cells exhibited a moderate protection by the addition of this scavenger of free radicals.
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    Der Stickstoffhaushalt immergrüner mediterraner Hartlaubblätter
    (1988) Diamantoglou, Stergos; Kull, Ulrich
    The seasonal variations of major nitrogenous components (total N, protein N) in sclerophyllous leaves of four mediterranean species - Ceratonia siliqua, Olea europaea var. sylvestris, Pistacia lentiscus and Quercus coccifera - were investigated throughout the whole lifetime of the leaves. The leaf-longevity of the first two species mentioned is about two yars, that of the latter two species is somewhat longer than one year. As reference values the raw fibre content and the total chlorophyll content of the leaves were also measured. The raw fibre content increase during leaf-growth, there-after it remains constant. In the leaves having a lifetime of two years, in the spring of the second year an additional increase, although weak, is observed. The chlorophyll content rises during the leaf growth, then remains unchanged for some time, but begins to decrease early. In the leaves of Ceratonia and Olea the shrinkage is recognized already in the spring of the second year. During the period of senescence, the decrease of chlorophyll a is more distinct than that of chlorophyll b. The total N content in all cases decreases during leaf-growth and then remains constant. In Ceratonia leaves it is reasonably high considering that it is an evergreen species. Rather early the N-content begins to decrease; which is intensified during the last months of the lifetime the leaves. This is due to the well-known export of N-compounds from senescent tissues. In Ceratonia leaves the N-content increases during the first winter; obviously they serve as N-storage organs. The content of protein-N in all species shows essentially the same variations as that of total N. Results of tests carried out in the months of January and August revealed that the proline content in the leaves of all species is higher during the drought period than during the cold period. Using the different reference-values, the variations of N-content during leaf longevity of the four species are discussed in connection with reflections on maintenance costs.
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    Cyclic-AMP reception and cell recognition in dictyostelium discoideum
    (1975) Gerisch, Günther; Malchow, Dieter; Huesgen, Adolfine; Nanjundiah, Vidyanand; Roos, Werner; Wick, Ursula; Hülser, Dieter F.
    Single cells of the slime mold, Dictyostelium discoideum, aggregate into a multicellular organism in response to cyclic AMP, which they detect by binding to cellsurface receptors. During the aggregation phase, two different responses to cyclic-AMP are observed. First, the cells orientate by chemotaxis towards the source of a concentration gradient which initially is a group of cells forming an aggregation center. Second, the cells relay pulses which are periodically generated by the centers.
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    Osmotische Verhältnisse und Zuckergehalte im Jahresgang bei Bäumen Ost-Afghanistans. 2, Cercii griffithii und Pistacia cabulica
    (1972) Kull, Ulrich; Breckle, Siegmar-Walter
    In der Kohe Daman-Ebene nördlich von Kabul gibt es einige weitbekannte Standorte von Cercis griffithii. Die Standorte, meist im Geröll oder auf Fels, scheinen in den meisten Fällen nicht grundwasserfern zu sein. Südwestlich von Kabul finden sich an trockenem Felsstandort alte Pistazien mit dicken Stämmen. Diese Relikte können sowohl als Zeiger eines früher wesentlich dichteren Vorkommens und weiterreichender Verbreitung angesehen werden. Die Jahresgänge der osmotischen Verhältnisse wie auch der Brechungsindices des Zellsaftes zeigen in den Blättern dieser beiden sommergrünen Arten Maxima im Spätsommer. Die Speicherkohlenhydrate zeigen in Rinden von Cercis vor allem Saccharose, Glucose und Stärke eine ausgeprägte Jahresperiodik, welche derjenigen von Quercus baloot und der mitteleuropäischer Arten ähnlich ist. Das winterliche Zuckermaximum ist mit einem Auftreten geringer Mengen von Raffinose verknüpft. In den Blättern von Cercis erfolgt mit zunehmendem Blattalter eine Abnahme der Zucker- und Stärkegehalte. Pistacia cabulica weist kein winterliches Maximum des Gesamtzuckergehaltes auf und führt weder Galaktoside noch Fructoside. Rinden und Blätter besitzen Maximalwerte des Zuckergehalts während der sommerlichen Trockenperiode. Die Berechnung des prozentualen Anteils des Gesamtzuckergehaltes am potentiellen osmotischen Druck läßt erkennen, daß die letztgenannte Größe vom Zuckerhaushalt je nach Art mehr oder weniger unabhängig ist.
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    Über den Nachweis von Aminosäuren in Kalksteinen des Weißen Jura der Schwäbischen Alb
    (1967) Hiller, Karl; Kull, Ulrich
    Es wird über einen erstmaligen, papierchromatographischen Nachweis von Aminosäuren in Kalksteinen des Weißen Jura der Schwäbischen Alb berichtet. In den Kalksteinen der Algen-Schwamm-Riffe treten unterschiedliche Gehalte an Aminosäuren in der vorwiegend anorganisch entstandenen Grundmasse einerseits und in den eng benachbarten, organischen Komponenten (Schwammumien, Kalkkrusten, Stromatolithen) andererseits auf.
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    Arachidonovaja kislota obratimo blokiruet vysokopronicaemye mežkletočnye kontakty
    (1994) Hülser, Dieter F.; Zempel, Günther; Reuss, Bernhard; Suhr, Dierk; Sarovskaja, Julija J.; Murav'eva, O. V.; Dunina-Barkovskaja, Antonina; Margolis, Leonid B.
    The effect of arachidonic on intercellular coupling via gap junctions has been studied in BICR/M1R k cells - a mammary tumor cell line of the Marshall ratt. Arachidonic acid is shown to reversibly block both ionic and dye coupling in a dose-dependent manner. The cells recoupled after the washout with either serum- or albumin (essentially fatty acid-free)-containing solution. The intercellular pH decreased from 7,2 to 7,0 after arachidonic acid treatment; the same pH shift in the absence of arachidonic acid, however, had no effect on the junctional permeability. Flow cytometric measurments revealed an arachidonic acid-induced increase of the cytoplasmic free Ca 2+ concentration which was also reversible upon albumin treatment. Intracellular Ca 2+ or H+ are unlikely to be involved in the mechanism of the arachidonic acid effect on intercellular coupling: high resolution measurments using double whole-cell technique also show reversible blockage of the junctional conductance in the presence of arachidonic acid while the pipette solution was buffered with 10 mM HEPES and 10 mM EGTA to clamp intracellular calcium and proton concentrations. We suggest that arachiconic acid directly affects the gap junction channels, probably interfering with the lipid-protein interactions.
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    Pulsed high-power-sonication of concrements, cancer cells and rodent-tumors in vivo
    (1989) Riedlinger, Rainer E.; Brümmer, Franz; Hülser, Dieter F.
    Extracorporeal lithotripsy has been successfully established, based on different principles of generating and focusing the shock waves. Lithotripters have also been used to investigate the influence of shocks to cancer cells and solid tumors. With two different trans-mitters (spark-gap type XL-1 and piezo-resonance type MW 2) we applied shock waves and short high power US-pulses to suspended and immobilized tumor cells and multicell spheroids. With MW 2 significant local damage on cell spheroids in gelatin was achieved, caused by locally controlled cavitation. The results are compared to each other.
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    Effects of abscisic acid on photosynthesis of protoplasts from Petunia hybrida
    (1974) Hoffmann, Franz; Kull, Ulrich
    Protoplasts from plants are suitable experimental objects for investigations in which substances are taken up by cells, since chemicals can reach the cell surface directly. Therefore, it is convenient to use them for experiments concerned with effects of phytohormones on metabolism. So far, some work on the application of auxins 1-3 has been described, and recently we have made some investigations on the influence of zeatin on photosynthesis and respiration of isolated mesophyll protoplasts from Petunia.
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    Differential effects of lesions of the dorsomedial and dorsolateral caudate putamen on reaction time performance in rats
    (1994) Hauber, Wolfgang; Schmidt, Werner J.
    In order to investigate the role of the dorsomedial and dorsolateral caudate-putamen (CPu) in movement initiation of rats, we examined the effects of quinolinic acid lesions (30 nmol in 1 μl) in these striatal subregions in a simple reaction time task. Results show that lesions of the dorsomedial, but not of the dorsolateral CPu increased reaction times. These findings provide further evidence for a functional heterogenity of the CPu and demonstrate an involvement of the dorsomedial CPu in processes related to rapid initiation of responses
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    Nervous-system-specific carcinogenesis by ethylnitrosourea in the rat: molecular and cellular aspects
    (1977) Rajewsky, Manfred F.; Augenlicht, Leonard H.; Biessmann, Harald; Goth, Regine; Hülser, Dieter F.; Laerum, Ole D.; Lomakina, L. Ya.
    A lead in the search for cellular determinants favoring neoplastic transformation may be provided by the pronounced tissue specificity of the oncogenic effect of certain carcinogens which do not require enzymatic metabolic activation, i.e., in cases where this specificity cannot be due to tissue differences in the activity of enzymes involved in the formation of the ultimate reactants. A carcinogen that fulfills this condition is the ethylating agent N-ethyl-N-nitrosourea (EtNU). Alkylation of nucleic acid constituents by N-nitroso compounds in relation to mutagenesis and carcinogenesis has received considerable attention recently.