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  • 1
    Digitale Medien
    Digitale Medien
    Killing of Fas ligand-resistant renal carcinoma cells by interleukin-2- and BCG-activated effector cells (2000)
    Springer
    Cancer immunology immunotherapy 49 (2000), S. 369-376 
    Details
    ISSN: 1432-0851
    Schlagwort(e): Key words Renal cell carcinoma ; Immunotherapy ; Perforin ; IL-2 ; Bacillus Calmette-Guérin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Activated cytolytic effector cells like lymphokine-activated killer (LAK) and the recently described bacillus-Calmette-Guérin-activated killer (BAK) cells are thought to mediate antitumor effects against metastatic renal cell carcinoma (RCC) and superficial bladder cancer respectively. Perforin and Fas ligand (FasL) have been described as the major lytic principles in cellular cytotoxicity. Using a radioactive-release assay and specific inhibitors, we investigated the molecular mechanisms used by LAK and BAK cells in the lysis of renal carcinoma cells. In addition, we evaluated the susceptibility of RCC cells to FasL-mediated cytotoxicity. LAK and BAK cells effectively lysed the renal cancer cell line SK-RC-35 upon cell-cell contact. Both effector cell populations were shown to produce perforin and FasL as determined by reverse transcriptase/polymerase chain reaction (RT-PCR). Using fluorescence-activated cell sorting analyses and RT-PCR, we detected a marked Fas receptor (Fas, CD95) expression on RCC cells. However, RCC cells were shown to be resistant to killing by recombinant FasL and lysis by BAK and LAK cells was not inhibited in the presence of anti-FasL antibody. In contrast, the cytotoxicity exerted by LAK and BAK cells was drastically reduced in the presence of the Ca2+-chelating agent EGTA as well as concanamycin A, a specific inhibitor of perforin-mediated lysis. These results demonstrate that cytolysis of FasL-resistant RCC cells by activated immune cells is mediated via perforin. Our findings give further insights into the molecular mechanisms involved in the elimination of RCC by cytotoxic lymphocytes activated with biological response modifiers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002620000118
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  • 2
    Digitale Medien
    Digitale Medien
    Mechanisms of Fluorescence Quenching in Donor—Acceptor Labeled Antibody—Antigen Conjugates (2000)
    Springer
    Journal of fluorescence 10 (2000), S. 147-147 
    Details
    ISSN: 1573-4994
    Schlagwort(e): Cyanine dyes ; energy transfer ; electron transfer ; Poisson distribution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The cyanine dyes Cy5 and Cy5.5 are presented as a new long wavelength-excitable donor-acceptor dye pair for homogeneous fluoroimmunoassays. The deactivation pathways responsible for the quenching of the fluorescence of the antibody-bound donor are elucidated. Upon binding of the donor dye to the antibodies at low dye/protein ratios, its fluorescence quantum yield rises to unity. Higher dye/protein ratios lead to progressive aggregation of the dyes, which results in quenching of monomer fluorescence due to resonance energy transfer (RET) from the monomers to the nonfluorescent dimers. The dependence of the quenching efficiency on the labeling ratio is described quantitatively by assuming a Poisson distribution of the dyes over the antibodies. The maximum fluorescence intensity per antibody is obtained at a labeling ratio of 4. Upon formation of the antibody-antigen complex, electron transfer and RET to the antigen-bound acceptor dye occur. Steady-state and time-resolved fluorescence measurements reveal that approximately 50% of the donor quenching is due to RET, while the residual quenching effect is caused by the static quenching process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009443125878
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  • 3
    Digitale Medien
    Digitale Medien
    A modular femoral implant for uncemented stem revision in THR (2000)
    Springer
    International orthopaedics 24 (2000), S. 134-138 
    Details
    ISSN: 1432-5195
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé   Nous avons évalué les premiers résultats de 142 opérations de changement de la prothèse fémorale sans ciment avec le système MRP-Titan modulaire. Dans 70 cas on a observé avant l’intervention des altérations importantes du fémur (typ 2C et typ 3 après Paprosky). Une greffe osseuse dans la zone de défaut n`a été nécessaire que dans 31 cas. Pendant un temps postopératoire de 2.3 années en moyenne, deux implant a dûêtre changéà cause d`un descellement aseptique de la prothèse. Une deuxième opération a été nécessaire dans cinq cas à cause de luxations répétées. Au niveau fonctionnel, on mesure une amélioration du score de Harris de 37.4 points à 92.4 points. Dans 122 cas on a trouvé un rétablissement de la structure osseuse avec une régénération dans la zone de défaut. Des ostéolyses locales n`ont pas été visibles.
    Notizen: Abstract  We present the early results of 142 uncemented femoral stem revisions using the modular MRP-Titan system. There were 70 cases with marked preoperative femoral bone defects (Paprosky type 2C and type 3); and bone grafts were used in 31 cases. At a mean follow-up of 2.3 years five cases were re-revised due to dislocation and two due to aseptic loosening. The mean Harris hip score improved from 37.4 preoperatively to 92.4. In 122 cases progressive bone regeneration on X-ray was seen; and no further osteolysis was observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002640000135
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  • 4
    Digitale Medien
    Digitale Medien
    Tensile strained InGaAs/InP multiple-quantum-well structures studied by magneto-optical spectroscopy (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4303-4307 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Low-temperature (1.8 K) magneto-optical absorption experiments have been performed on two tensile strained In1−xGaxAs/InP multiple-quantum-well samples. By using derivative spectra and the effective-mass equation of a quasi-two-dimensional exciton, we are able to determine the exciton ground state energy more accurately and to identify higher excited exciton states up to the 5S level. Data of the effective masses for the light hole and the heavy hole are given. Furthermore, the effect of nonparabolicity is discussed. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.373069
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  • 5
    Digitale Medien
    Digitale Medien
    Annealing of Ni80Fe20/Cu and Co/Cu multilayers (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4852-4854 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Ni80Fe20/Cu and Co/Cu multilayers with Cu layer thicknesses corresponding to the first and second antiferromagnetic (afm) coupling maximum were prepared by dc-magnetron sputtering and investigated with respect to their annealing behavior. The as-deposited films showed giant magnetoresistance (GMR) up to 50% at room temperature. The annealing behavior of the multilayers belonging to the same Cu layer thickness is found to be very similar up to 200 °C. For both kind of multilayers with a Cu layer thickness of about 1 nm (first afm maximum) the GMR degrades upon annealing in excess of 140 °C. However, with a Cu layer thickness of about 2 nm (second afm maximum) the multilayers are stable with respect to their GMR properties even after prolonged exposure up to 200 °C. Moreover, in some cases even an improvement of GMR upon the annealing procedure may be found. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.373180
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  • 6
    Digitale Medien
    Digitale Medien
    Scaling properties of three-dimensional isotropic magnetohydrodynamic turbulence (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 4889-4900 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A comprehensive picture of three-dimensional (3D) isotropic magnetohydrodynamic (MHD) turbulence is presented based on the first 5123-mode numerical simulations performed. Both temporal and spatial scaling properties are studied. For finite magnetic helicity H the energy decay is governed by the constancy of H and the decrease of the ratio of kinetic and magnetic energy Γ=EK/EM. A simple model consistent with a series of simulation runs predicts the asymptotic decay laws E∼t−1/2, EK∼t−1. For nonhelical MHD turbulence, H(similar, equals)0, the energy decays faster, E∼t−1. The energy spectrum follows a k−5/3 law, clearly steeper than k−3/2 previously found in 2D MHD turbulence. The scaling exponents of the structure functions are consistent with a modified She–Leveque model ζpMHD=p/9+1−(1/3)p/3, which corresponds to a basic Kolmogorov scaling and sheet-like dissipative structures. The difference between the 3D and the 2D behavior can be related to the eddy dynamics in 3D and 2D hydrodynamic turbulence. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1322562
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  • 7
    Digitale Medien
    Digitale Medien
    Admittance spectroscopy of efficient CuInS2 thin film solar cells (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 5474-5481 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Thermal admittance spectroscopy is applied to characterize the trap properties of high-efficiency CuInS2/CdS/ZnO thin film solar cells. To that aim, the capacitance spectrum is examined in detail. Nontrap capacitance contributions like freeze-out of free carriers and series resistance are discussed. The dependence of the resistance on the sample area is used to identify its physical origin. Simulation results of a transmission line model are in good agreement with the spreading resistance of the ZnO window layer. Defect spectra, i.e., the distribution of the deep trapping states in the band gap, are extracted from the admittance spectra, using a method established by T. Walter, R. Herberholz, C. Müller, and H. W. Schock [J. Appl. Phys, 80, 4411 (1996)]. Arrhenius data of the traps are drawn best from the spectrum of conductance versus temperature. The defect spectra do not depend on the buffer layer. Generally, they show a high constant background trap density with some broad peaks. Two new trap levels at 0.3 and 0.5 eV are found, confirmed by deep level transient spectroscopy and identified as majority carrier traps in the bulk of the p-type CuInS2 absorber. An increasing density of the trap at 0.5 eV correlates with a decreasing open-circuit voltage. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1312838
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  • 8
    Digitale Medien
    Digitale Medien
    Active length control of two phase locked CO2 lasers with a digital signal processor (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 3298-3305 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Two CO2 lasers are phase locked together by injection locking, where radiation between the two lasers is exchanged using a copper prism as a beam folding device in the resonators. Extraction of the output radiation is achieved by a common output coupler. As this method is only utilizing reflective optics (except for the output coupler), it is also practical as a technique for phase-locking lasers with powers in the multikilowatt range. Single frequency oscillation is only achieved if the lengths of both resonators are within a so-called locking range. This can only be fulfilled if the length of one resonator is actively controlled. The method of detection of the phase difference between the lasers and actively controlling the length of one resonator is presented as well as its implementation into a digital signal processor. Stable phase locked operation is achieved and proved through detection of twice the intensity in the far field in the phase-locked regime. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1288263
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  • 9
    Digitale Medien
    Digitale Medien
    Highly charged ion based time-of-flight emission microscope (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2077-2081 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: An emission microscope using highly charged ions as the excitation source has been designed, constructed, and operated. A novel "acorn" objective lens has been used to simultaneously image electron and secondary ion emission. A resistive anode-position sensitive detector is used to determine the x–y position and time of arrival of the secondary events at the microscope image plane. Contrast in the image can be based on the intensity of the electron emission and/or the presence of particular secondary ions. Spatial resolution of better than 1 μm and mass resolution m/Δm of better than 400 were demonstrated. Background rejection from uncorrelated events of greater than an order of magnitude is also achieved. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1150582
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  • 10
    Digitale Medien
    Digitale Medien
    Soft X Rays: The Alternative? (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of interventional cardiology 13 (2000), S. 0 
    Details
    ISSN: 1540-8183
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: SummaryIntravascular radiation therapy to prevent restenosis remains promising and is currently undergoing large randomized clinical trials. Intravascular brachytherapy sources include beta particles, gamma rays, and now, soft X rays. The presented, but unpublished data from the START trial indicate that beta radiation is effective in the treatment of in-stent restenosis. However, the limited range of beta particles in tissue increase the complexity for treating large arteries, more dose asymmetry with imperfect centering, and the potential for shadowing when treating calcified or stented arteries. These dosing problems are avoided with high energy gamma rays, but at a cost of increased radiation exposure. Soft X rays generated by high voltage, miniaturized x-ray tubes may be turned off at will, pose little radiation exposure risk to medical personnel, provide a satisfactory dose profile to the artery, and do not require special use licensing. The higher LET and RBE for soft X rays indicates that lower doses may be as effective. Soft x-ray sources will permit a new therapy to enter the expanding discipline of vascular brachytherapy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1540-8183.2000.tb00324.x
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