04 Fakultät Energie-, Verfahrens- und Biotechnik

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5

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1986 - 198921990 - 19924

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Publication Type: search.filters.UBSTyp.BuchbeitragAuthor: search.filters.author.Hülser, Dieter F.

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Now showing 1 - 6 of 6
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    Gap junctions: correlated electrophysiological recordings and ultrastructural analysis by fast freezing and freeze-fracturing
    (1989) Hülser, Dieter F.; Paschke, Dietmar; Greule, Joachim
    The effect of glutardialdehyde on the dynamic organization of gap junctions cannot only be seen by electrophysiological measurements where the uncoupling of cells occurs within 3 min, but also by freeze fracturing the cells. Gap junctions from unfixed cells rapidly frozen by dipping into liquid propane appear polymorphic; loosely packed and clustered plaques are found, as well as tightly packed aggregates, which are mainly found in fixed preparations. Whether these different structures correspond with different functional states, or whether they depend on the local configuration of the contacting membranes is difficult to decide. The presented results, however, support the idea of active (coupling competent) gap junctions with loosely packed channels and nonactive (permanently closed) gap junctions where the channels are tightly packed.
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    Patch clamp techniques for the characterization of membrane channels
    (1991) Eckert, Reiner; Paschke, Dietmar; Hülser, Dieter F.
    The examples demonstrate that by means of high resolution patch clamp recordings, physiological properties of the cell membrane may be elucidated on the molecular level of individual ion channels.
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    Intercellular communication in three-dimensional culture
    (1992) Hülser, Dieter F.
    The coordination of cell growth and differentiation as well as of tissue homeostasis and synchronization of tissue functions requires the transfer of information between cells. This may be achieved by an unidirectional signal flow, as is the case with secreted molecules (hormones. neurotransmitters) and or with membrane-bound receptors (sperm-egg binding, immune system). It can also follow a nonrectifying mode. as is observed for direct intercellular communication via gap junctions that are founed in regions of close cell-to-cell contact. These membrane channels are not only bidirectionally permeable and facilitate the free exchange of charged and neutral molecules, but also connect adjacent cells mechanically. They must be clearly discriminated from desmosomes, which anchor cells together to form structural or functional units, as well as from tight junctions that seal membranes of epithelial cells to each other so that the paracellular path becomes impermeable to molecules, and a polarity of apical and basolateral surface is maintained.
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    Interzelluläre Kommunikation in dreidimensional wachsenden Multizell-Sphäroiden : ein Zellkulturmodell zur Verringerung von Tierversuchen
    (1986) Hülser, Dieter F.; Bräuner, Thomas; Brümmer, Franz
    Am Beispiel dieser direkten interzellulären Kommunikation konnten wir zeigen, daß in zweidimensional wachsenden Zellkulturen auch die in Tieren gefundenen Strukturen der gap junctions ausgebildet werden, ohne daß die üblichen Funktionen geleistet werden. Sobald die Zellen jedoch mit einem Züchtungstrick dazu gebracht werden, dreidimensional wachsende Zellaggregate zu formen, lassen sich an ihnen auch wieder Regulationsleistungen und Organisationsmerkmale nachweisen, wie man sie vom intakten Organismus her kennt. Diese Multizell-Sphäroide zeigen das gleiche histologische Bild wie kleine Tumorknötchen und sind wie diese durch das Auftreten von zentralen Nekrosen charakterisiert. An solchen Modelltumoren konnten wir einen Zusammenhang zwischen der Strahlenresistenz von Tumorzellen und ihrem Kopplungsverhalten nachweisen (1). Diese Ergebnisse führten zu klinischen Versuchen, bei denen vor der Bestrahlung von Tumorpatienten die wirksame minimale Strahlendosis durch Kommunikationsmessungen an Tumorbiopsien ermittelt wurden (2). Messungen der Strahlenresistenz der entsprechenden Tumore nach Transplantation in Nacktmäuse können so entfallen. Ergänzend zu diesen Experimenten untersuchen wir jetzt den Zusammenhang zwischen Invasivität von Tumorzellen und ihrer Fähigkeit zur interzellulären Kommunikation mit konfrontierten Gewebe. Dies kann nicht mehr ausschließlich ihrer dem mit Multizell-Sphäroiden aus permanent wachsenden Zellinien durchgeführt werden, da ein Zielgewebe benötigt wird, dessen Zellen sich nicht mehr teilen (proliferieren). Solche nicht-proliferierenden Multizell-Sphäroide kann man aus neun Tage lang bebrüteten Hühnereiern gewinnen.
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    Biological effects of shock-waves
    (1991) Bräuner, Thomas; Brümmer, Franz; Hülser, Dieter F.; Rassweiler, Jens J.
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    A rapid method for the determination of absolute particle sizes in a flow cytometer
    (1991) Brenner, Joachim; Hülser, Dieter F.
    The most precise determination of a cell-size distribution can be expected by registering the signal of a three-dimensional size (particle volume). This is best performed in a flow cytometer with an integrated volume measurement according to the Coulter-principle.This electrical measurement is very fast and is more precise than the forward-scatter method which is used alternativly in flow cytometry. The mean size of particles which has been determined by the Coulter-principle is mostly given by arbitrary units. We, therefore, present here a simple and fast calibration method which allows the transformation of arbitrary to absolute values. In addition we compared these data with one- and two-dimensional measurements under the microscope and an image-processing-system, respectively.