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  • 1
    Electronic Resource
    Electronic Resource
    Attenuation of Parasite cAMP Levels in T. cruzi-Host Cell Membrane Interactions In Vitro (1995)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 42 (1995), S. 0 
    Details
    ISSN: 1550-7408
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previous investigations have shown that the adhesion of T. cruzi plasma membrane vesicles (PMV) to monolayers of host cell myoblasts and to immobilized heart muscle sarcolemma membranes (PAM) on polyaerylamide beads is mediated by the interaction of T. cruzi attachment sites with the muscarinic cholinergic and β-adrenergic receptors of the host cell membrane. It has also been shown that this interaction is blunted by the specific antagonists of the mammalian receptors atropine and propranol, respectively. In the studies reported here, PAM also rapidly attached to swimming T. cruzi trypomastigotes in a complex, concentration-dependent fashion and binding isotherms showed that the equilibrium between free and bound PAM is rapidly reached within 2 minutes of incubation in physiologically balanced salt solutions. In this time frame, trypomastigote cAMP levels are significantly reduced from steady state values within 30 seconds of the addition of PAM in a buffer system containing a diesterase inhibitor. Maximal attenuation of cAMP levels was measured between 1 and 2 minutes of the addition of PAM to T. cruzi trypomastigotes. The degree of cAMP level attenuation was reduced by blocking PAM attachment with either atropine or propranol. On the basis of these results we propose that a likely pathway for the negative parasite signal generated upon adhesion of host muscle cell membranes to the surface of the flagellates is from the parasite's surface attachment sites directly to a Pertussis toxin sensitive inhibitory protein Gi, thereby blunting adenyl cyclase activity and cAMP formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1550-7408.1995.tb01535.x
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  • 2
    Electronic Resource
    Electronic Resource
    Hypercholesterolemia increases manganese superoxide dismutase immunoreactive macrophages in myocardium (1995)
    Springer
    Histochemistry and cell biology 104 (1995), S. 295-300 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effect of hypercholesterolemia on manganese superoxide dismutase (MnSOD)-containing macrophages was investigated in male New Zealand white rabbits. Macrophages from control animals, which were marked with the RAM-11 antibody, demonstrated co-localization with MnSOD immunoreactivity, e.g. in the peri- and paravascular space within the myocardium, but not in the bone marrow. In rabbits fed a 0.5% cholesterol-enriched diet for 42 days, a significant increase (P〈0.01) of MnSOD-immunoreactive macrophages within the myocardium was found concomitant to the drastic elevation of serum cholesterol level. In the bone marrow, MnSOD immunoreactivity did not change after cholesterol feeding. Thus in cholesterol-fed rabbits, the increase of MnSOD-containing macrophages seems to parallel that of lipoproteins. MnSOD is considered as being protective against the cytotoxic effects of those superoxide anions, possibly generated in macrophages, which are involved in the metabolism of modified lipoproteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01464325
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  • 3
    Electronic Resource
    Electronic Resource
    Significant Transport of Doxorubicin into the Brain with Polysorbate 80-Coated Nanoparticles (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1564-1569 
    Details
    ISSN: 1573-904X
    Keywords: brain tumors ; brain targeting ; doxorubicin ; nanoparticles ; polysorbate 80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate the possibility of delivering of anticancer drugs into the brain using colloidal carriers (nanoparticles). Methods. Rats obtained 5 mg/kg of doxorubicin by i v. injection in form of 4 preparations : 1. a simple solution in saline, 2. a simple solution in polysorbate 80 1% in saline, 3. bound to poly (butyl cyanoacrylate) nanoparticles, and 4. bound to poly(butyl cyanoacrylate) nanoparticles overcoated with 1% polysorbate 80 (Tween® 80). After sacrifice of the animals after 10 min, 1, 2, 4, 6, and 8 hours, the doxorubicin concentrations in plasma, liver, spleen, lungs, kidneys, heart and brain were determined after extraction by HPLC. Results. No significant difference in the body distribution was observed between the two solution formulations. The two nanoparticle formulations very significantly decreased the heart concentrations. High brain concentrations of doxorubicin (〉6 μg/g) were achieved with the nanoparticles overcoated with polysorbate 80 between 2 and 4 hours. The brain concentrations observed with the other three preparations were always below the detection limit (〈 0.1 |μg/g). Conclusions. The present study demonstrates that the brain concentration of systemically administered doxorubicin can be enhanced over 60-fold by binding to biodegradable poly(butyl cyanoacrylate) nanoparticles, overcoated with the nonionic surfactant polysorbate 80. It is highly probable that coated particles reached the brain intact and released the drug after endocytosis by the brain blood vessel endothelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018983904537
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  • 4
    Electronic Resource
    Electronic Resource
    An Extremal Problem For Random Graphs And The Number Of Graphs With Large Even-Girth (1998)
    Springer
    Combinatorica 18 (1998), S. 101-120 
    Details
    ISSN: 1439-6912
    Keywords: AMS Subject Classification (1991) Classes:  05A16, 05C35, 05C38, 05C80
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: C 2 k -free subgraph of a random graph may have, obtaining best possible results for a range of p=p(n). Our estimates strengthen previous bounds of Füredi [12] and Haxell, Kohayakawa, and Łuczak [13]. Two main tools are used here: the first one is an upper bound for the number of graphs with large even-girth, i.e., graphs without short even cycles, with a given number of vertices and edges, and satisfying a certain additional pseudorandom condition; the second tool is the powerful result of Ajtai, Komlós, Pintz, Spencer, and Szemerédi [1] on uncrowded hypergraphs as given by Duke, Lefmann, and Rödl [7].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009804
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  • 5
    Electronic Resource
    Electronic Resource
    In vitro evaluation of biocompatibility of different wound dressing materials (1995)
    Springer
    Journal of materials science 6 (1995), S. 201-205 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The in vitro biocompatibility of newly developed wound dressings consisting of different chitosan salts (chitosan lactate, glutamate and chloride) and a chitosan derivative (methylpyroolidinone chitosan) was compared with three commercially available wound dressings made of collagen, calciumalginate, and gelatin, by evaluation in a fibroblast cell culture system. Three experimental models which reflect relevant stages of wound healing were used, and the significant influence of the experimental setting on the results was demonstrated. Collagen and methylpyrrolidinone chitosan were the most compatible materials under the investigated test conditions. Chitosan chloride and glutamate were the least compatible substances. The results indicated that wound dressings made of chitosan lactate and methylpyrrolidinone chitosan as well as the three commercially available dressings are well tolerated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146856
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  • 6
    Electronic Resource
    Electronic Resource
    Nemertean predation on the tropical fiddler crab Uca musica (1997)
    Springer
    Hydrobiologia 365 (1997), S. 233-239 
    Details
    ISSN: 1573-5117
    Keywords: Hoplonemertean ; fiddler crab ; predatory behavior ; anti-predator defenses ; intertidal ; Panama
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We saw 79 predatory interactions between a new speciesof monostiliferous, suctorial hoplonemertean and thefiddler crabs Uca musica (77 cases) and U.stenodactylus (2 cases). At an intertidal sand barin the Pacific entrance of the Panama Canal, worms ateabout 0.1% of the adult crab population per day. Themode of attack and the spatial and temporaldistributions of interactions suggest the worm is anambush predator. When struck by a worm‘s sticky,mucous-covered proboscis, crabs produced copious foamfrom their buccal area. Mucous-laden crabs thatescaped, again foamed indicating that the foam maycounteract the mucus. If the attack led to a kill,the struggling crab soon became quiescent, as istypical in other nemertean-prey interactions. Theworm inverted its proboscis, found ingress to thecrab‘s body and fed. Crabs escaped by autotomizingappendages entwined by the proboscis, by forcefullypulling away and by remaining quiescent, then movingaway when the worm inverted its proboscis and beforeit entered the crab. Immobility, a response to visualpredators, may falsely indicate paralysis to the wormand cause it to invert its proboscis, therebyproviding the crab with an opportunity to escape. This predator-prey interaction seems to incorporategeneralized predator tactics and fortuitous preydefenses that give worms and crabs about an evenchance of success.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003141401259
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  • 7
    Electronic Resource
    Electronic Resource
    The Role of Serum Complement on the Organ Distribution of Intravenously Administered Poly (methyl methacrylate) Nanoparticles: Effects of Pre-Coating with Plasma and with Serum Complement (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1055-1058 
    Details
    ISSN: 1573-904X
    Keywords: nanoparticles ; body distribution ; plasma proteins ; complement ; reticulo-endothelial system ; opsonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The organ distribution of radiolabeled poly (methyl methacrylate) (PMMA) nanoparticles coated with plasma proteins and serum complement in rats was studied in order to determine the effect of serum complement on the particle phagocytosis by the organs of the reticulo-endothelial system (RES). Methods. PMMA-nanoparticles were coated overnight with plasma proteins or serum complement, and injected into Wistar rats. The body distribution of nanoparticles was measured by means of scintillation counting of organ samples. In addition, proteins adsorbed to the particle surface were inactivated by heat treatment prior to injection, and the particles's distribution was measured as described above. Results. Whereas uncoated nanoparticles (control group) were mainly taken up by the Kupffer cells in the liver, incubation of the particles in plasma for 12 h followed by heat inactivation reduced the particle concentrations in the liver to merely 22% after 30 min. After 120 min, liver concentrations were still lower than the control group, and almost 30% of the administered dose of the heat-inactivated particle group was present in non-RES organs and tissues. Particles with non-inactivated complement were accumulated in the lung at concentrations of 29% after 30 min, which increased to 71% after 120 min, whereas those coated with inactivated complement reached lung concentrations above 70% already after 30 min. Conclusions. Particles coated with plasma components are able to avoid uptake by the RES, especially after heat inactivation of the plasma components adsorbed. Adsorption and heat inactivation of complement proteins alone, however, does not have the same result as coating with plasma proteins followed by heat inactivation. Therefore, it is concluded that plasma components other than complement proteins take part in the process of RES activation and phagocytosis of injected nanoparticles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016010808522
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  • 8
    Electronic Resource
    Electronic Resource
    Delivery of Loperamide Across the Blood-Brain Barrier with Polysorbate 80-Coated Polybutylcyanoacrylate Nanoparticles (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 325-328 
    Details
    ISSN: 1573-904X
    Keywords: loperamide ; nanoparticles ; polysorbate 80 ; drug delivery ; brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The possibility of using polysorbate 80-coated nanoparticles for the delivery of the water insoluble opioid agonist loperamide across the blood-brain barrier was investigated. The analgesic effect after i.v. injection of the preparations was used to indicate drug transport through this barrier. Methods. Loperamide was incorporated into PBCA nanoparticles. Drug-containing nanoparticles were coated with polysorbate 80 and injected intravenously into mice. Analgesia was then measured by the tail-flick test. Results. Intravenous injection of the particulate formulation resulted in a long and significant analgesic effect. A polysorbate 80 loperamide solution induced a much less pronounced and very short analgesia. Uncoated nanoparticles loaded with loperamide were unable to produce analgesia. Conclusions. Polysorbate 80-coated PBCA nanoparticles loaded with loperamide enabled the transport of loperamide to the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012098005098
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  • 9
    Electronic Resource
    Electronic Resource
    Influence of Chitosan Microspheres on the Transport of Prednisolone Sodium Phosphate Across HT-29 Cell Monolayers (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 58-65 
    Details
    ISSN: 1573-904X
    Keywords: chitosan microspheres ; HT-29B6 cell monolayers ; small intestine ; prednisolone sodium phosphate ; drug absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present study was performed to investigate the influence of chitosan microspheres on transport of the hydrophilic, antiinflammatory drug prednisolone sodium phosphate (PSP) across the epithelial barrier. Methods. Microspheres were prepared using a precipitation method and loaded with PSP. Transport studies were performed in a diffusion cell chamber using the polarized human cell line HT-29B6. Porcine small intestine and fluorescence-labeled microspheres were used to investigate penetration ability of microspheres. Results. It was shown that transport of PSP drug solution was not saturable across the cell monolayers (P = 8.68 ± 8.24 × 10−6 cm sec−1) and no sodium dependency could be established. EGTA treatment resulted in an increased permeability (P = 18.69 ± 1.09 × 10−6 cm sec−1). After binding of prednisolone to chitosan microspheres its permeability was enhanced drastically compared with the drug solution (P = 35.37 ± 3.21 ×10−6 cm sec−1). This effect was prevented by EGTA treatment (P = 15.11 ± 2.57 × 10−6 cm sec−1). Furthermore the supporting effect of chitosan microspheres was impaired by pH and ion composition of the medium, whereas the effect remained unchanged in cells treated with bacterial lipopolysaccharides. In vitro incubation of fluorescence-labeled microspheres in the lumen of freshly excised intestine revealed a significant amount of the spheres in the submucosa. Conclusions. Chitosan microspheres are a useful tool to improve the uptake of hydrophilic substances like PSP across epithelial layers. The effect is dependent on the integrity of the intercellular cell contact zones and the microparticles are able to pass the epithelial layer. Their potential benefit under inflammatory conditions like in inflammatory bowel disease, in order to establish high drug doses at the region of interest, remains to be shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011996619500
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  • 10
    Electronic Resource
    Electronic Resource
    Halmzählung oder Parzellentotalernte — wie genau sind Prädatorbonituren im Winterweizen? (1997)
    Springer
    Journal of pest science 70 (1997), S. 121-126 
    Details
    ISSN: 1612-4766
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Zusammenfassung In den Jahren 1994 bis 1996 erfolgten an 3 Standorten (Mitteldeutsches Trockengebiet bei Halle/S., Fläming und Magdeburger Börde) methodische Untersuchungen zur Dichteerfassung von Prädatoren in Winterweizen. In insgesamt 13 Erhebungen wurden jeweils 5 Feldbonituren (6 m laufende Drillreihe und dazugehöriger Bodenbereich) mit einer „absoluten” Methode, der Parzellentotalernte (D-VAC-Absaugung und Pflanzenentnahme innerhalb eines 1 m2-Käfigs, Auswertung der Arthropoden im Labor) verglichen. Die Analyse der einzelnen Erhebungen mittels U-Test nachMann undWhitney ergab für nur 8 der 55 Vergleiche signifikante Unterschiede. Es zeigten sich keine klaren Trends. Bei Betrachtung der mittleren Dichte der Nützlinge auf der Grundlage der Dichten in den 13 Erhebungen stellten sich für die Boniturren im Vergleich zu den Parzellentotalernten folgende relative Abundanzen und Signifikanzen im t-Test heraus: Coccinellidenimagines 0,88 (P〉0,10), Coccinellidenlarven 0,88 (P〉0,10), Syrphidenlarven 0,92 (P〉0,10), Chrysopidenlarven 0,84 (P〉0,10), Carabidenimagines 0,24 (P=0,054), Staphylinidenimagines 0,14 (P=0,002), adulte Spinnen 0.48 (P=0,058). Die beachtliche Unterschätzung der polyphagen Raubarthropoden in den Boninturen wird diskutiert.
    Notes: Abstract Methodical investigations on predator recording in winter wheat were performed at 3 sites in Middle Germany (Flaeming, Magdeburger Boerde, Middle German dry region near Halle/S.) in 1994 to 1996. In 13 field studies tiller counts (5× 6 m drill row with corresponding soil surface) were compared with the total plot harvest (an „absolute method”, combination of D-VAC suction sampling and vegetation harvest within a 1 m2-cage, laboratory determination of arthropods). The U-test analysis of each survey according toMann andWhitney shows only 8 significant differences in 55 comparisons. There were no clear trends. Considering the average predator densities in 13 investigations, the following relative densities (and significances using t-test) were calculated for field counts in comparison with the total plot harvest: coccinellid adults −0.88 (P〉0.10), coccinellid larvae −0.88 (P〉0.10), syrphid larvae −0.92 (P〉0.10), chrysopid larvae −0.84 (P〉0.10), adult carabids −0.24 (P=0.054), adult staphylinids −0.14 (P=0.002) and adult spiders −0.48 (P=0.058). The important underestimation of polyphagous predatory arthropods in field counts is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01904747
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