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1.
Fickweiler S Abels C Karrer S Bäumler W Landthaler M Hofstädter F Szeimies RM 《Journal of photochemistry and photobiology. B, Biology》1999,48(1):27-35
9-Acetoxy-2,7,12,17-tetrakis-(beta-methoxyethyl)-porphycene (ATMPn) is a promising new photosensitizer characterized by high absorption around 640 nm and high singlet oxygen yield. To study the mechanism of action in vitro we have investigated uptake, intracellular localization, cell survival and ultrastructural changes following photodynamic treatment in human cell lines derived from the skin (SCL1 and SCL2, squamous cell carcinoma; HaCaT keratinocytes; N1 fibroblasts). Using flow cytometry we have determined the cellular fluorescence as a marker for the uptake of ATMPn after incubation for 60 min. Co-staining with ATMPn and fluorescent dyes specific for cell organelles reveals an intracellular localization of ATMPn in lysosomes. Following irradiation using an incoherent light source (580-740 nm) and a light fluence of 24 J cm-2, phototoxicity is determined by means of the 3-4.5 dimethylthiazol-2,5 diphenyl tetrazolium bromide (MTT) assay. For all cell lines ATMPn concentrations above 15 nM yield a significant phototoxic effect. The 50% effective concentration, EC50, for SCL1 cells is 11.2 +/- 2.9 nM ATMPn. ATMPn uptake and phototoxicity are more effective for HaCaT and SCL1 as compared to SCL2 and N1 cells. Growth curves confirmed the results of the MTT assay. Because of the high lysosomal accumulation of ATMPn, already low photosensitizer concentrations without dark toxicity yield a high photodynamic effect. Immunofluorescence and electron microscopy reveal damage to tonofilaments, plasma membrane and mitochondria, indicating a mechanism unrelated to apoptosis. A dose yielding complete cell killing, as needed for oncological indications, might lead to necrosis, whereas lower sub-lethal doses result in induction of apoptosis. 相似文献
2.
Colloid and Polymer Science - 相似文献
3.
E. Cherbuliez Pl. Plattner S. Ariel R. Wahl Muhlemann E. Abderhalden P. Karrer W. Karrer H. Thomann E. Horlacher W. Mäder S. L. Jodidi V. Henriques S. P. L. Sörensen J. Tillmans P. Hirsch F. Stoppel L. Michaelis H. Bauer E. Strauss C. J. Weber J. Froideveaux 《Analytical and bioanalytical chemistry》1932,87(3-4):142-147
4.
Growth of quaternary AlInGaN/GaN heterostructures by plasma-induced molecular beam epitaxy 总被引:2,自引:0,他引:2
A. P. Lima C. R. Miskys U. Karrer O. Ambacher A. Wenzel B. Rauschenbach M. Stutzmann 《Journal of Crystal Growth》2000,220(4):341-344
Epitaxial growth of AlInGaN/GaN heterostructures on sapphire substrates was achieved by plasma-induced molecular beam epitaxy. Different alloy compositions were obtained by varying the growth temperature with constant Al, In, Ga and N fluxes. The In content in the alloy, measured by Rutherford backscattering spectroscopy, increased from 0.4% to 14.5% when the substrate temperature was decreased from 775°C to 665°C. X-ray reciprocal space maps of asymmetric AlInGaN (2.05) reflexes were used to measure the lattice constants and to verify the lattice match between the quaternary alloy and the GaN buffer layers. 相似文献
5.
K. W. Gemmell J. Monteath Robertson G. A. Sim Karl Bernauer A. Guggisberg M. Hesse H. Schmid P. Karrer 《Helvetica chimica acta》1969,52(3):689-701
Treatment of the Calebash alkaloid C-calebassine ( 1 ), C40H48N4O2++·2X?, with hot mineral acid yielded the anhydro-isocalebassine acid adduct 3H , with the formula C40H47N4O+++·3X?.H2O. This was converted into anhydro-isocalebassine methyl ether salts ( 4 ) C41H48N4O++·2X?·H2O with alkaline dimethyl sulphate. A total X-ray analysis of the orthorhombic diiodide led to formula 4 . The conversion of C-calebassine ( 1 ) into 4 involves a radical change in the central part of the molecule. The structure of the acid adduct 3H can be deduced from the structure of 4. Treatment of 3 H with warm methanol or treatment of C-calebassine ( 1 ) with acetic acid yielded a pale yellow compound 2 , C40, H44N4++·2X?·H2O. The central part of the molecule 2 contains a pyrrole ring, and most probably this is an intermediate in the conversion of 1 into 3 H by mineral acid. The changes of 3 H and 2 in acidic, neutral and basic media can be shown by electronic spectroscopy. Reaction of 3 H with 1 mole of oxygen at pH 4 converted it into a stable blood-red oxidation product C40H44N4O2++·2X? containing a merocyanine system. The structure 7 , proposed for this compound, is discussed. 相似文献
6.
B. Karrer G. Ghoshal 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(2):239-245
There has been a considerable amount of interest in recent years on the robustness of networks to failures. Many previous
studies have concentrated on the effects of node and edge removals on the connectivity structure of a static network; the networks are considered to be static in the sense that no compensatory measures are allowed for recovery of
the original structure. Real world networks such as the world wide web, however, are not static and experience a considerable
amount of turnover, where nodes and edges are both added and deleted. Considering degree-based node removals, we examine the
possibility of preserving networks from these types of disruptions. We recover the original degree distribution by allowing
the network to react to the attack by introducing new nodes and attaching their edges via specially tailored schemes. We focus
particularly on the case of non-uniform failures, a subject that has received little attention in the context of evolving
networks. Using a combination of analytical techniques and numerical simulations, we demonstrate how to preserve the exact degree distribution of the studied networks from various forms of attack. 相似文献
7.
Schott & Gen. J. Królikowski P. Karrer und K. Schöpp 《Fresenius' Journal of Analytical Chemistry》1936,107(1-2):44-45
Ohne Zusammenfassung 相似文献
8.
9.
P. Karrer 《Colloid and polymer science》1930,52(3):304-319
Ohne Zusammenfassung 相似文献
10.
J. R. Hymon H. Schmid P. Karrer A. Boller H. Els P. Fahrni A. Fürst 《Helvetica chimica acta》1969,52(6):1564-1602
The course of the reactions involved in the process of degradation of strychnine ( 1 ) to Wieland-Gumlich aldehyde (WGA) ( 2 ), first performed by Wieland, Kaziro & Gumlich , has been elucidated. 23-Isonitrosostrychnine hydrochloride ( 9a ) upon treatment with thionyl chloride undergoes a fragmentation (2nd order Beckmann rearrangement), thus furnishing N(a)-cyanoformyl-WGA hydrochloride ( 14a ). On heating in an acidic medium, the latter compound is transformed — at least partially via the cyclic urethane 15 — into WGA ( 2 ), which is an important keyintermediate in the syntheses of strychnine and curare alkaloids. The compound 2 can now be obtained in high purity and good yield. A corresponding degradation has been realized with quaternary analogues ( 27 → 3 ) as well as with 10-chlorostrychnine ( 58 → 62 ). 10-Chlorostrychnine ( 58 ) was prepared by chlorination of strychnine with chlorine in conc. hydrochloric acid according to Leuchs & Steinborn. As by-products of the reaction, 10, 15-dichlorostrychnine ( 59 ) and 10, 15, 19-trichlorostrychnine ( 60 ) could be identified. Starting from WGA a series of derivatives have been prepared. Special mention is made of the two epimeric methyl ethers 18 and 19 . The absolute configuration at the centre 17 of WGA and of these two substances has been established by optical comparisons of 3 epimeric pairs. The methyl ether 18 , by-product « B », is obtained if methanol is used in working up the Beckmann rearrangement products of 23-isonitrosostrychnine hydrochloride ( 9a ). A second by-product, « A », results by working up under alkaline conditions. This compound has the structure 44 with inverted configuration at centre 16. Degradation of 44 under controlled conditions leads either to WG-diol ( 42 ) or to 16-epi-WG-diol ( 51 ). Besides « A z.rdang; and « B » a series of by-products and intermediates ( 16, 17, 11a, 22. 23, 24 and 25 ) could be detected in the course of the process of strychnine degradation. 相似文献