Browsing by Author "Brümmer, Franz"

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Open Access
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.
Open Access
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.
Open Access
Biological effects of shock waves
(1990) Brümmer, Franz; Bräuner, Thomas; Hülser, Dieter F.
Extracorporeal shock wave lithotripsy has become established worldwide as the method of choice for the treatment of nephrolithiasis and ureterolithiasis over the last 10 years. Although initial studies showed no damaging effects of the shock waves on organs and tissues, numerous recent reports have presented evidence for severe acute effects and chronic complications after shock wave treatment. The pathophysiological effects on kidneys and the histopathological effects on organs or tissues in man and animal, and also the effects on cells in culture and tumors are sumarized. Suspended and immobilized cell cultures were used to characterize and quantify the efficacy of shock wave. Extended applications of shock waves and possible modifications to shock wave generators are discussed.
Open Access
Biological effects of shock-waves
(1991) Bräuner, Thomas; Brümmer, Franz; Hülser, Dieter F.; Rassweiler, Jens J.
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Open Access
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.
Open Access
Cavitation-generated free radicals during shock wave exposure: investigations with cell-free solutions and suspended cells
(1991) Suhr, Dierk; Brümmer, Franz; Hülser, Dieter F.
Extracorporeally generated shock waves as used in lithotripsy of urinary and biliary stones exhibit side effects in vivo. Furthermore, these shock waves destroy eukaryotic cells during in vitro treatment in suspension. A possible cause of these damaging effects might be cavitation, the growth and collapse of bubbles in liquids exposed to tensile stresses. During the collapse, temperature inside these cavitation bubbles rises up to several thousand K, leading to the formation of free radicals. We demonstrated the occurrence of cavitation-generated free radicals by direct reaction with fluorescent dyes in solution after shock wave treatment and investigated the resulting cell killing by variation of the cellular antioxidative defense status. We present evidence for the generation of intracellular free radicals during shock wave treatment of suspended cells.
Open Access
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.
Open Access
Closing and opening of gap junction pores between two- and threedimensionally cultured tumor cells
(1982) Hülser, Dieter F.; Brümmer, Franz
Intercellular signal transfer via gap junction pores in cultured multicell spheroids of BICR/M1R-K cells decreases with increasing spheroid age. In two days old spheroids the pores allow passage of Lucifer yellow molecules. Two days later, this fluorescent dye is retained in the injected cell even though the cells are still electrically coupled. Gap junction plaques of considerable size are still found in 9 days old spheroids, when the cells are completely uncoupled. The same cells growing as monolayer cultures do not exhibit such a gradual closing of their gap junction pores: Their coupling is established at first cell contact, probably by a gradual opening of the pores, which remain open even up to 9 days in culture.
Open Access
Comparative characterization of the 21-kD and 26-kD gap junction proteins in murine liver and cultured hepatocytes
(1989) Traub, Otto; Look, Jutta; Dermietzel, Rolf; Brümmer, Franz; Hülser, Dieter F.; Willecke, Klaus
Affinity-purified antibodies to mouse liver 26- and 21-kD gap junction proteins have been used to characterize gap junctions in liver and cultured hepatocytes. Both proteins are colocalized in the same gap junction plaques as shown by double immunofluorescence and immunoelectron microscopy. In the lobules of rat liver, the 21-kD immunoreactivity is detected as a gradient of fluorescent spots on apposing plasma membranes, the maximum being in the periportal zone and a faint reaction in the perivenous zone. In contrast, the 26-kD immunoreactivity is evenly distributed in fluorescent spots on apposing plasma membranes throughout the rat liver lobule. Immunoreactive sites with anti-21 kD shown by immunofluorescence are also present in exocrine pancreas, proximal tubules of the kidney, and the epithelium of small intestine. The 21-kD immunoreactivity was not found in thin sections of myocardium and adult brain cortex. Subsequent to partial rat hepatectomy, both the 26- and 21-kD proteins first decrease and after approximately 2 d increase again. By comparison of the 26- and 21-kD immunoreactivity in cultured embryonic mouse hepatocytes, we found (a) the same pattern of immunoreactivity on apposing plasma membranes and colocalization within the same plaque, (b) a similar decrease after 1 d and subsequent increase after 3 d of both proteins, (c) cAMP-dependent in vitro phosphorylation of the 26-kD but not of the 21-kD protein, and (d) complete inhibition of intercellular transfer of Lucifer Yellow in all hepatocytes microinjected with anti-26 kD and, in most cases, partial inhibition of dye transfer after injection of anti-21 kD. Our results indicate that both the 26-kD and the 21-kD proteins are functional gap junction proteins.
Open Access
Cultivation-independent analysis of the bacterial community associated with the calcareous sponge Clathrina clathrus and isolation of Poriferisphaera corsica Gen. Nov., Sp. Nov., belonging to the barely studied class Phycisphaerae in the phylum Planctomycetes
(2020) Kallscheuer, Nicolai; Wiegand, Sandra; Kohn, Timo; Boedeker, Christian; Jeske, Olga; Rast, Patrick; Müller, Ralph-Walter; Brümmer, Franz; Heuer, Anja; Jetten, Mike S. M.; Rohde, Manfred; Jogler, Mareike; Jogler, Christian
Marine ecosystems serve as global carbon sinks and nutrient source or breeding ground for aquatic animals. Sponges are ancient parts of these important ecosystems and can be found in caves, the deep-sea, clear waters, or more turbid environments. Here, we studied the bacterial community composition of the calcareous sponge Clathrina clathrus sampled close to the island Corsica in the Mediterranean Sea with an emphasis on planctomycetes. We show that the phylum Planctomycetes accounts for 9% of the C. clathrus-associated bacterial community, a 5-fold enrichment compared to the surrounding seawater. Indeed, the use of C. clathrus as a yet untapped source of novel planctomycetal strains led to the isolation of strain KS4T. The strain represents a novel genus and species within the class Phycisphaerae in the phylum Planctomycetes and displays interesting cell biological features, such as formation of outer membrane vesicles and an unexpected mode of cell division.
Open Access
Effect of shock waves on suspended and immobilized L1210 cells
(1989) Brümmer, Franz; Brenner, Joachim; Bräuner, Thomas; Hülser, Dieter F.
L1210 mouse leukemia cells have been exposed to different doses of shock waves generated by underwater spark discharge at 18 kV in an experimental lithotripter (XL1, Dornier). Histological and flow cytometric investigations revealed severe damage and a LD50 of about 420 shock waves when the cells were treated as suspensions. Cells immobilized in gelatine, however, were unaffected, indicating that secondary effects are responsible for the cellular damage. Possible mechanisms such as cavitation, jets, and shear forces are discussed.
Open Access
Einwirkung von Stosswellen auf tierische Zellkulturen : durchflußzytometrische Untersuchungen physiologischer Parameter
(1988) Brümmer, Franz; Brenner, Joachim; Bräuner, Thomas; Nesper, Martina; Hülser, Dieter F.
Ziel unserer Arbeiten ist die Charakterisierung biologischer und physikalischer Eigenschaften von Stoßwellen sowie die Abgrenzung primärer Stoßwellenwirkungen von sekundären Wirkungen auf biologisches Material.
Open Access
Einwirkung von Stosswellen auf tierische Zellkulturen : licht- und elektronenmikroskopische Untersuchungen
(1988) Bräuner, Thomas; Brümmer, Franz; Hülser, Dieter F.
Zur Charakterisierung biologischer Eigenschaften von Stoßwellen setzten wir Einzelzellsuspensionen der Maus-Leukämie-Zellinie L1210 sowie kugelförmig wachsende Zellaggregate, sogenannte Multizell-Sphäroide, verschiedener Tumorzellinien ein.
Open Access
Gap junction formation in rabbit uterine epithelium in response to embryo recognition
(1988) Winterhager, Elke; Brümmer, Franz; Dermietzel, Rolf; Hülser, Dieter F.; Denker, Hans-Werner
Gap junction formation was studied in the uterine epithelium of nonpregnant, pregnant, and pseudopregnant rabbits in the periimplantation phase (6, 7, 8 days post coitum/post human gonadotropin injection) using freeze-fracture and immunocytochemistry as well as intracellular Lucifer yellow injection. At implantation (7 days post coitum) the uterine epithelial cells of the implantation chamber become junctionally coupled as evidenced by all three methods used. Gap junction protein (26K) becomes detectable immunocytochemically with a monoclonal antibody at 6 days post coitum in the epithelium surrounding the blastocyst, i.e., in the forming implantation chamber. The same sequence of events, starting with the presence of the gap junction protein before cell-to-cell coupling becomes evident, was observed in the blastocyst-free segments 1 day later. In contrast, uterine epithelium of nonpregnant and pseudopregnant animals in comparable phases shows an extremely low degree of coupling. The presence of the blastocyst is a necessary condition for the induction of gap junctions as demonstrated by unilateral pregnancy produced by tubal ligation. Thus, gap junction formation is one of the first maternal responses to a locally acting signal of the blastocyst.
Open Access
Gap Junctions in Multizell-Sphäroiden
(1982) Brümmer, Franz; Hülser, Dieter F.
In a two-dimensionally growing monolayer the same morphological structure as in vivo may be detected, however, as we have shown for gap junctions, their regulatory activity may be retarded. Cells growing in three-dimensional multicell-spheroids may re-establish their regulatory activities and, therefore, match the in vivo conditions more closely. Multicell-spheroids enable in vitro investigations on differentiating systems and on interactions between normal and malignant cells, thus substituting costly in vivo experiments.
Open Access
Genesis of amorphous calcium carbonate containing alveolar plates in the ciliate Coleps hirtus (Ciliophora, Prostomatea)
(2013) Lemloh, Marie-Louise; Marin, Frédéric; Herbst, Frédéric; Plasseraud, Laurent; Schweikert, Michael; Baier, Johannes; Bill, Joachim; Brümmer, Franz
Open Access
Histopathology of shock wave treated tumor cell suspensions and multicell tumor spheroids
(1989) Bräuner, Thomas; Brümmer, Franz; Hülser, Dieter F.
L1210 mouse leukemia cell suspensions exposed to 500 shock waves (SW) in an experimental lithotripter (XLI, Dornier) revealed severe cellular damage. Apart from cell fragments and cellular debris, cells exhibited alterations of shape, vacuolisation of the cytoplasm, perinuclear cisternae, swelling of mitochondria or rupture of the mitochondrial fine structure, and permeabilization of the cell membrane. Treatment of multicell tumor spheroids of both HeLa and EMT6/Ro cells in suspension with 500 SW resulted either in loss of peripheral cells and serious cellular damage in the outer regions or in a fragmentation of the spheroids. Many of the geometrically intact cells exhibited the same histopathological alterations as the suspended L1210 cells. Immobilization of the spheroids in agar or gelatine, however, prevented spheroids from being agitated and accelerated during SW-exposure. After treatment with 500 SW, spheroids immobilized in gelatine were not different from control cultures, as investigated with light- and electronmicroscopy. From our results we conclude that spheroids in suspension are subject to cavitation and liquid jet formation, causing not only acceleration and shearing forces but also collisions which account for the observed cell damage.
Open Access
Hydrolyzable microplastics in soil : low biodegradation but formation of a specific microbial habitat?
(2022) Schöpfer, Lion; Schnepf, Uwe; Marhan, Sven; Brümmer, Franz; Kandeler, Ellen; Pagel, Holger
Microplastics (MP, plastic particles between 0.1 and 5000 μm) contaminate agricultural soils through the application of organic fertilizers, sewage sludge, and plastic mulch. MP surfaces and the MP-soil interface provide specific habitats for soil microorganisms - the plastisphere. Microorganisms in the plastisphere may benefit from utilizing MP as a carbon (C) source. Hydrolyzable MP with ester bonds are susceptible to enzymatic depolymerization by hydrolysis. In a microcosm experiment, we investigated MP biodegradation of small and large (< 0.5 mm and 0.5-2 mm respectively), hydrolyzable (a poly(lactic acid)/poly(butylene co-adipate terephthalate) blend, PLA/PBAT) and non-hydrolyzable (low-density polyethylene, LDPE) polymers, and the effects of these MP on microorganisms in dry and wet MP-amended soil. MP affected neither abundance and composition of the main soil microbial groups (fungi, Gram-negative, and Gram-positive bacteria), specific activities of ß-glucosidase, ß-xylosidase, lipase, and phenoloxidase, nor respiration in MP-amended soil. Only large PLA/PBAT particles in dry soil were significantly mineralized (15.4% of initial PLA/PBAT-C after 230 days). PLA/PBAT mineralization coincided with enhanced lipase and ß-glucosidase activities on the surfaces of individual PLA/PBAT particles extracted from the soil after incubation (compared to LDPE and non-incubated PLA/PBAT particles). We detected cracks on the surfaces of PLA/PBAT particles using scanning electron microscopy, indicating initiation of MP biodegradation, presumably due to depolymerization by lipases. Results suggest that the PLA/PBAT plastisphere is a polymer-specific habitat for lipase-producing soil microorganisms. Our study demonstrates that analyzing biogeochemical interactions within polymer-specific plastispheres is essential to assess MP fate and their impacts on microbially driven soil processes.
Open Access
In situ laboratory for plastic degradation in the Red Sea
(2022) Brümmer, Franz; Schnepf, Uwe; Resch, Julia; Jemmali, Raouf; Abdi, Rahma; Kamel, Hesham Mostafa; Bonten, Christian; Müller, Ralph-Walter
Degradation and fragmentation of plastics in the environment are still poorly understood. This is partly caused by the lack of long-term studies and methods that determine weathering duration. We here present a novel study object that preserves information on plastic age: microplastic (MP) resin pellets from the wreck of the SS Hamada, a ship that foundered twenty-nine years ago at the coast of Wadi el Gemal national park, Egypt. Its sinking date enabled us to precisely determine how long MP rested in the wreck and a nearby beach, on which part of the load was washed off. Pellets from both sampling sites were analyzed by microscopy, X-ray tomography, spectroscopy, calorimetry, gel permeation chromatography, and rheology. Most pellets were made of low-density polyethylene, but a minor proportion also consisted of high-density polyethylene. MP from inside the wreck showed no signs of degradation compared to pristine reference samples. Contrary, beached plastics exhibited changes on all structural levels, which sometimes caused fragmentation. These findings provide further evidence that plastic degradation under saltwater conditions is comparatively slow, whereas UV radiation and high temperatures on beaches are major drivers of that process. Future long-term studies should focus on underlying mechanisms and timescales of plastic degradation.
Open Access
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.