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Publication Type: search.filters.UBSTyp.KonferenzbeitragAuthor: search.filters.author.Brümmer, Franz

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Now showing 1 - 6 of 6
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    Biophysical investigations of the in vitro effects of shock waves and ultrasound
    (1993) Brümmer, Franz; Suhr, Dierk; Irmer, Ulrich; Bachleitner, Christoph; Hülser, Dieter F.
    To investigate the interactions of ultrasonic waves with biological tissues, we developed and standardized several in vitro models. Using these systems - artificial stones, human erythrocytes, L1210 mouse leukemia cells, multicellular spheroids, cavitation assay - we are able to elucidate the mechanisms of interaction as well as the cause of clinically observed side effects.
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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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    Biological effects and physical characterization of shock waves by an XL-1 experimental lithotripter
    (1989) Brümmer, Franz; Staudenraus, Joachim; Nesper, Martina; Suhr, Dierk; Eisenmenger, Wolfgang; Hülser, Dieter F.
    Extracorporeal shock wave lithotripsy (ESWL) has become the clinical standard method for non-invasive disintegration not only of concrements in kidney and urinary tract but also of gallstones. Despite the widespread clinical use of ESWL, the mechanism of stone destruction is not yet really understood, but several possibilities (cavitation, shock wave reflection) are discussed. The final cause of various side effects is still under discussion. Nevertheless, during the last few years much effort was put into possible extensions of ESWL applications On the other hand , physical characterizations of shock waves are rarely reported and combined measurements of biological effects in vitro and physical characterization of the applied shock waves are not available. We, therefore, examined the influence of water temperature and gas content on the shock wave efficency in biological systems and determined several physical characteristics (pressure amplitudes, rise time etc.) of the shock waves under the same experimental conditions.
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    Are biological effects of shock waves caused by free radicals?
    (1991) Suhr, Dierk; Brümmer, Franz; Hülser, Dieter F.
    Stone fragmentation in extracorporeal shock wave lithotripsy as well as accompanying tissue damage are attributed to cavitation. We attempted to demonstrate and localize the occurrence of cavitation in cell-free solutions and MGH-U1 cells using sensitive dyes for the detection of cavitation-generated free radicals.
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    Shock waves and free radicals : cell protection by vitamin E in vitro and ex vivo
    (1993) Suhr, Dierk; Brümmer, Franz; Irmer, Ulrich; Schlachter, Manfred; Hülser, Dieter F.
    The application of extracorporeal generated shock waves in medicine for the fragmentation of human kidney and gall stones proved to be a very successful technique. Shock wave lithotripsy, however, is not free of tissue damaging side effects. One major mechanism for the fragmentation of stones as well as for the side effects is cavitation, ie. the formation and movement of bubbles in liquids exposed to tensile forces. Collapse of cavitation bubbIes is accompanied by local "hot spots" of several 1,000 K, thus generating free radicals. We investigated the contribution of these free radicals to cellular injury by varying the cellular amount of a well known scavenger of free radicals, α-tocopherol.
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    Characterization of gap junctions by electrophysiological and electronmicroscopical methods
    (1990) Hülser, Dieter F.; Paschke, Dietmar; Brümmer, Franz; Eckert, Reiner
    Gap junctions are ubiquitous in the animal kingdom from mesozoa to vertebrates. They must be discriminated from desmosomes which anchor cells together to form structural or functional units as well as from tight junctions which 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.