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  • 1
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 5827-5829 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Transport measurements on large single crystals of Cd0.8Zn0.2Te:Cl indicate that Cl donors form DX centers in CdZnTe. We have observed persistent photoconductivity (PPC) with an annealing temperature Ta≈130 K. Hall-effect experiments indicate that the PPC arises from a persistent increase in the density of charge carriers; the saturation density is Nsat=6×1016 cm−3. The deep binding energy of the DX center is Ed=0.22 eV. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 661-673 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe a family of reversible holographic storage materials which exploit the bistability of the crystal defect known as the "DX" center. Crystals containing these defects have the characteristics of local photorefractive materials in that their refractive index is modified in proportion to the local optical energy absorbed. This refractive index change, which results from the release of electrons from the DX deep trap states into the conduction band, is persistent at low temperatures due to a capture barrier, Ecap, which limits reformation of the DX centers. The effect is reversed by heating above an annealing temperature, which scales with Ecap and varies with the crystal host and active dopant. A number of DX materials have now been identified with long-term persistence temperatures ranging from 50 to 180 K. In this paper, we briefly review the physics of the DX center and present theoretical estimates of several important optical properties of these materials based on a simple model. We calculate spatial resolution, maximum refractive index shift, and sensitivity, and compare our predictions with measurements on one member of the DX family, AlGaAs:Te. In a 345 μm thick sample of this material doped at 9×1017 cm−3, we find a refractive index shift, Δn, of 2×10−3 and an exposure sensitivity, S, of 0.012 cm3/J. Our expectation that the maximum refractive index change scales linearly with the doping density is consistent with our previous measurement of Δn=1.1×10−2 obtained for a sample of AlGaAs:Si doped at 4×1018 cm−3. The measured values of Δn and S, are, respectively, two and three orders of magnitude larger than corresponding values for the photorefractive material LiNbO3, and are shown here to be independent of exposing irradiance from 10−3 to 108 W/cm2. At the latter irradiance, the refractive index shift is shown to occur with a material response time shorter than our measurement limit of several picoseconds. Thus, this material exhibits high sensitivity, large refractive index change, and fast write time, all desirable properties of an optical holographic storage medium. Phase gratings written in AlGaAs:Te using low-power (mW) beams from infrared diode lasers give diffraction efficiencies from 30% to 55% for grating periods from 0.13 to 15 μm. No degradation of sensitivity is observed after large numbers of exposure–erasure cycles. Experiments with multiple-hologram exposures show that the DX materials require no exposure schedule: equal strength holograms are obtained using equal exposures. Binary data have been stored in the form of multiplexed two-dimensional arrays of pixel bits. Required material and system parameters are estimated for a 1 Tbyte holographic storage device based on angle multiplexing in a DX material. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-2307
    Keywords: Adult Niemann-Pick disease ; Generalized AL-amyloidosis ; Progressive liver failure ; Fibroblast culture ; Immunohistochemistry ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report a case in which an adult form of Niemann-Pick disease (type B of NPD) was associated with a rapidly progressive generalized AL amyloidosis of kappa type. Both diagnosis were made by biopsy, the NPD by bone marrow biopsy and fibroblast culture, the amyloidosis by liver biopsy. Malignant non-Hodgkin lymphoma was not found. The patient, a 67-year-old woman, died from hepatic coma subsequent to a progressive liver failure. We discuss possible relations between the lysosomal storage disease and the development and rapid progression of amyloidosis.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 70 (1999), S. 114-122 
    ISSN: 1433-0385
    Keywords: Key words: Focal hepatic disease ; Imaging ; Diagnostic strategy ; Diagnostic efficacy. ; Schlüsselwörter: Focale Leberläsionen ; Bildgebung ; diagnostische Effizienz.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Abhängig vom Primärtumor treten bei bis zu 80 % der Patienten mit einem extrahepatischen Malignom Lebermetastasen auf. Für ein zielgerichtetes, therapeutisches Management dieser Patienten ist erforderlich, daß Lebermetastasen ausgeschlossen oder nachgewiesen werden und ggf. in ihrer Zahl, Lokalisation und Größe bestimmt werden. Prinzipiell kommen dazu Sonographie, Computertomographie (CT), Magnetresonanztomographie (MRT), nuklearmedizinische Verfahren und Angiographie in Frage. Alle diese Methoden wurden laufend weiterentwickelt und technisch verbessert, so daß auch ihre diagnostische Aussagekraft zugenommen hat. Die biphasische, Kontrastmittel-verstärkte Spiral-CT (SCT) und MRT mit modernen Pulssequenzen und gewebespezifischen Kontrastmitteln haben sich hinsichtlich ihrer diagnostischen Effizienz und der Reproduzierbarkeit der Untersuchungsergebnisse als überlegen erwiesen. Mit SCT und MRT wird in der Diagnostik focaler Leberläsionen eine Sensitivität und Spezifität von jeweils 80–95 % erreicht. Die Verfahren besitzen darüber hinaus den Vorteil, daß sie nichtinvasiv sind. Die diagnostische Strategie bei der Abklärung von Lebermetastasen hat neben den Stärken und Schwächen der Untersuchungsmethoden die jeweilige klinische Situation des Patienten zu beachten, sollte schnell zu konklusiven Ergebnissen kommen und nicht zuletzt Kosten-Nutzen-Gesichtspunkte berücksichtigen.
    Notes: Summary. Liver metastases are much more common than primary hepatic malignancies and may occur in up to 80 % of patients with extrahepatic malignancies. To optimize the patient's management, precise detection or exclusion of liver metastases, as well as assessment of their number and extent, is indispensable. For imaging of liver metastases, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), scintigraphy, and angiography can be utilized. All these methods have been technically improved with benefits for diagnostic utility. Biphasic contrast-enhanced spiral CT (SCT) and MRI with modern pulse sequences and tissue-specific contrast agents are superior to other imaging modalities in terms of diagnostic efficacy and reproducibility of results. With SCT and MRI sensitivities and specificities in the diagnosis of focal hepatic disease are in the range of 80–95 %. Moreover, their non-invasiveness is a strong advantage. The diagnostic strategy in the assessment of liver metastases has to take into account both the strengths and limitations of the respective method. Additionally, the clinical situation of a particular patient has to be considered, and conclusive diagnostic results have to be achieved in a short time in order to ensure a favourable cost-effectiveness relation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 39 (1997), S. 554-556 
    ISSN: 1432-0843
    Keywords: Key words Idarubicin ; Pharmacokinetics ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A three-compartment model was fitted to idarubicin data in a NONMEM pooled-data approach. Clearance (CL) of 221.7 ml/min was relatively high, and drug distribution was rapid (CLD=248.3 ml/min) and extensive [steady-state volume of distribution (Vss) 24 l]. The area under the concentration-time curve (AUC) of idarubicinol was 8 times that of idarubicin. Concentrations of idarubicin (idarubicinol) measured in the myocardium at 24 h after i.v. administration of idarubicin were 20 (5) times those determined in plasma. Tissue concentrations of idarubicinol were up to 400 times those of idarubicin, indicating that the active metabolite contributes significantly to the overall drug action.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1289
    Keywords: Schlüsselwörter Familiäre Amyloid Polyneuropathie ; Transthyretin ; Amyloidose ; Genetische Lebererkrankung ; Lebertransplantation ; Key words Familial Amyloid Polyneuropathy ; Transthyretin ; Amyloidosis ; Genetic liver disease ; Liver Transplantation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A 59-year old male of German origin noticed exercise-independent cardiac arrhythmia two years before admission. An alanine 47 transthyretin variant of Familial Amyloid Polyneuropathy with hypertrophic cardiomyopathy, peripheral sensory-motor polyneuropathy, I. degree AV heart block was diagnosed. To diminish production and deposition of mutant transthyretin and to prevent disease progression orthotopic liver transplantation was performed. Prior to transplant the patient complained of inappetence. Postoperatively, he received a chemically defined enteral nutrition regime that was discontinued after 30 months until return of appetite and weight gain indicated marked improvement. However, a duodenal biopsy still demonstrated amyloid deposits 24 months after transplantation. Echocardiographic findings remained unchanged. Neurologic examination showed an improvement of sensory-motor polyneuropathy with regression of electromyographic changes. Only traces of variant transthyretin were detectable in plasma samples taken 12 months after the operation. During the 3 year follow-up, no additional symptoms have occurred and progression of amyloidosis was prevented. Currently, orthotopic liver transplantation is the only specific treatment to prevent progression of familial amyloid polyneuropathy.
    Notes: Zusammenfassung Anläßlich der Abklärung von Herzrhythmusstörungen wurde bei einem 59-jährigen Patienten deutscher Herkunft eine Familiäre Amyloid Polyneuropathie (FAP) mit hypertropher Kardiomyopathie, beginnender peripherer Polyneuropathie, AV-Block I. Grades, intermittierend II. Grades Typ MOBITZ, und einer Aminosäuresubstitution von Glycin durch Alanin an Position 47 des Transthyretins (TTR Ala47) diagnostiziert. Um die weitere Bildung und Ablagerung des mutierten Transthyretins zu reduzieren und den Progreß der Erkrankung zumindest aufzuhalten, wurde die Indikation zur Lebertransplantation gestellt. Bei sonstiger Symptomfreiheit entwickelte der Patient bereits vor Transplantation eine progrediente Inappetenz. Postoperativ erhielt der Patient eine enteral-supportive Ernährung über Duodenalsonde für einen Zeitraum von 30 Monaten, bis sich der Appetit verbesserte und das Körpergewicht stabilisierte. In Biopsien der Duodenalschleimhaut ließ sich 24 Monate nach Transplantation weiterhin Amyloid nachweisen. Wie bereits vorTransplantation bestanden eine Verminderung von Magenperistaltik und Duodenalmotilität sowie eine hypertrophe Kardiomyopathie ohne wesentliche funktionelle Einschränkungen. Eine diskrete Verbesserung der sensomotorischen Polyneuropathie konnte anhand der Normalisierung elektromyographischer Veränderungen belegt werden. 12 Monate nach Transplantation waren nur noch Spuren der Transthyretinvariante (TTR Ala47) im Plasma zu finden. Während des bisherigen Beobachtungszeitraumes von mehr als 3 Jahren nach Transplantation sind keine neuen Symptome aufgetreten. Eine Progression der Erkrankung konnte eindeutig verhindert werden. Die orthotope Lebertransplantation ist gegenwärtig die einzige erfolgversprechende Therapieform, um eine Progression der Familiären Amyloid Polyneuropathie zu verhindern.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2277
    Keywords: Key words Xenotransplantation ; liver ; intravital microscopy ; Liver transplantation ; xenografting ; hemoperfusion ; intravital microscopy ; Intravital microscopy ; liver transplantation ; xenografting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The main targets of xenogeneic rejection mechanisms are the endothelial cells of the graft. Their activation and the consequent alteration of the organ's microcirculation lead to the destruction of the xenograft. Microhemodynamic changes occurring during this process are still poorly characterized. The aim of this study was to analyze the microcirculation during xenogeneic ex vivo hemoperfusion of rat livers and to monitor the impact of treatment strategies using intravital fluorescence microscopy. In contrast to the isogeneic control group, blood flow almost completely stopped within the first minutes of xenoperfusion. Simultaneously, perfusion pressure increased and bile production was reduced. Acetylsalicylate (Aspisol) and the platelet-activating factor antagonist WEB 2170 improved the microcirculation and function of the xenoperfused liver. The combination showed a synergistic effect. After apheresis of preformed xenogeneic antibodies, the parameters measured were comparable with those seen in isogeneic experiments. Complement degradation with cobra venom factor revealed a minor improvement in perfusion. A rapid, extensive, and irreversible leukocyte accumulation in terminal portal vessels was observed in all xenogeneic experiments. Blood counts of the perfusate confirmed the early trapping of leukocytes and platelets in the xenoperfused liver, indicating nonimmunological, cellular involvement in this rejection process.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2277
    Keywords: Key words Xenogeneic liver hemoperfusion ; Intravital microscopy ; Fucoidin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since the main feature of hyperacute rejection is a disturbance of the xenograft's microcirculation, we analyzed microhemodynamic parameters during xenogeneic hemoperfusion of the guinea pig (GP) liver and investigated the contribution of leukocytes to the rejection process using intravital fluorescence microscopy. Isolated GP livers were hemoperfused via the portal vein in a recirculating system with a constant flow of 1 ml/min per g liver. In contrast to isogeneic perfusion with heparinized GP blood, a disturbance in the microcirculation was observed during xenogeneic perfusion using heparinized rat blood, with significantly higher values of perfusion pressure, reduced sinusoidal perfusion rates, and a larger number of stagnant leukocytes. A complete breakdown of the microcirculation, with the highest values of perfusion pressure and the smallest perfusion index, was associated with 100 % accumulated leukocytes when rat blood was anticoagulated with sodium citrate. Almost isogeneic perfusion values were obtained when fucoidin, which inhibits L-selectin-dependent cell interaction, was added to heparinized rat blood. These data indicate that leukocyte-endothelial cell interaction contributes to xenogeneic rejection.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-3297
    Keywords: Acoustic startle response ; sensitization ; amygdala ; Roman high- and low-avoidance rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract To investigate the emotional reactions of two rat strains selectively bred for good and poor two-way avoidance acquisition (RHA/Verh and RLA/Verh), male animals of both strains were tested in an acoustic startle response test. They received 40 acoustic stimuli followed by 10 electric foot shocks and another 30 acoustic stimuli. RLA/Verh rats showed a significantly higher startle response compared to RHA/Verh animals, indicating a stronger emotional reaction to acoustic stimuli. In addition, the former showed a stronger response to foot shocks. Combined with earlier findings, we conclude that selection for two-way avoidance learning does not result in cognitive defects in the RLA/Verh strain but, rather, in stronger emotional reactions to fearful stimuli.
    Type of Medium: Electronic Resource
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