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  • 1
    ISSN: 0173-0835
    Keywords: T cell receptor ; Cutaneous T cell lymphoma ; Polymerase chain reaction ; Temperature gradient gel electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Cutaneous T cell lymphomas (CTCL) can be differentiated from benign inflammatory dermatoses by the demonstration of clonal T cells in skin biopsy. As a marker of the T cell clonality, the rearrangement of the T cell receptor (TCR) genes is amplified by polymerase chain reaction (PCR) and subsequently analyzed by several electrophoresis techniques. Since the validity of this approach depends substantially on the separating capacity of the applied electrophoresis technique, we investigated in the present study the lower detection limit and the sensitivity of heteroduplex-loaded polyacrylamide gel electrophoresis on MDE® (mutation detection enhancement) gels (HD-MDE PAGE), of heteroduplex-loaded temperature gradient gel electrophoresis (HD-TGGE) and fragment analysis (FA) on sequencing gels. Genomic DNA from formalin-fixed, paraffin-embedded skin biopsies of 53 CTCL specimens and 27 samples of benign dermatoses was analyzed by TCRy PCR followed by electrophoretic separation. Clonality was detected by HD-MDE PAGE in 22, by HD-TGGE in 34, and by FA in 33 of the 53 CTCL cases. Additionally, FA revealed an oligoclonal fragment profile in seven CTCL specimens. In the 27 samples from benign dermatoses, HD-MDE PAGE and HD-TGGE showed the expected polyclonal pattern in 26, and FA in 25 specimens. HD-TGGE and FA detected a clonal pattern down to a dilution of 103 monoclonal cells in 106 peripheral blood mononuclear cells (PBMC), while HD-MDE PAGE revealed a detection limit of 104 monoclonal cells in 106 PBMC. In conclusion, HD-TGGE and FA possess a higher sensitivity and lower detection limit than HD-MDE PAGE. Therefore, both former techniques are useful tools for the routine diagnostic procedure. With regard to time and cost, we recommend HD-TGGE.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XIX. On the Thermal Aging of an Al2O3/Cr2O3/K2O Dehydrocyclization Catalyst Made by Impregnation and its RegenerationAn Al2O3/Cr2O3/K2O catalyst was aged at different temperatures in hydrogen flow. These samples and the regenerated ones (prepared by oxidation and subsequent reduction under mild conditions of the aged samples) were investigated by means of reflectance spectroscopy, EPR, oxygen chemisorption, determination of oxidizability and microcatalytic measurements of the activity in the dehydrocyclization of n-hexane.The reversible and irreversible processes occurring during the thermal aging are discussed. The importance of the oxidizability of the chromia for the regenerability of the catalysts is explained.
    Notes: Ein Al2O3/Cr2O3/K2O-Katalysator wurde bei verschiedenen Temperaturen im Wasserstoffstrom gealtert. Die so erhaltenen Proben sowie aus ihnen hergestellte regenerierte (oxydierte und anschließend unter relativ milden Bedingungen reduzierte) Präparate wurden mit Hilfe der Reflexionsspektroskopie, der paramagnetischen Elektronenresonanz, der Sauerstoffchemisorption, der Bestimmung der Oxydierbarkeit und der mikrokatalytischen Messung der Aktivität bei der Dehydrocyclisierung von n-Hexan untersucht. Die bei der thermischen Alterung ablaufenden reversiblen und irreversiblen Vorgänge werden diskutiert und die Rolle der Oxydierbarkeit des Chromoxids für die Regenerierbarkeit der Katalysatoren dargelegt.
    Additional Material: 9 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XX. On the Influence of the Chromia Concentration on the Thermal Aging of Al2O3/Cr2O3/K2O Dehydrocyclization Catalysts Made by ImpregnationIt is reported on the thermal aging of catalysts containing 20% Cr2O3 + 4% K2O, 10% Cr2O3 + 2% K2O, 5% Cr2O3 + 1% K2O and 2.5% Cr2O3 + 0.5% K2O. Both catalysts with a high content of chromia (and potassium oxide) are characterized by high thermal stability. The portion of irreversible aging compared with that of the reversible aging decreases with increasing chromia concentration: A “reserve” of chromia is an important prerequisite to the regenerability of the catalysts.
    Notes: Es wird über die thermische Alterung von Katalysatoren berichtet, die 20% Cr2O3 + 4% K2O, 10% Cr2O3 + 2% K2O, 5% Cr2O3 + 1% K2O bzw. 2,5% Cr2O3 + 0,5% K2O auf γ-Al2O3 als Träger enthalten. Die beiden Katalysatoren hoher Chromoxid- (und Kaliumoxid-) Konzentration zeichnen sich durch hohe thermische Stabilität aus. Mit steigender Chromoxidkonzentration nimmt der Anteil der irreversiblen gegenüber dem der reversiblen Alterung ab: Eine gute Regenerierbarkeit der Katalysatoren setzt eine Chromoxidreserve voraus.
    Additional Material: 8 Ill.
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  • 4
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Studies on Oxide Catalysts. XVIII. On the Suitability of Different Aluminas as Carriers for Al2O3/Cr2O3/K2O Impregnation Catalysts.Suitability of 10 Al2O3/Cr2O3/K2O catalysts prepared on the basis of various Al2O3 carriers for the dehydrocyclization of n-hexane was investigated. These catalysts were classified with respect to the dispersion of chromia by means of X-ray diffraction studies, measurement of spin intensity (β-phase, EPR signal), and reflectance spectroscopy. The accessible chromia surface area was determined by oxygen chemisorption measurements. Aluminas with a high surface area which don't restrict the accessibility to the chromia are suitable carriers.
    Notes: Unter Verwendung unterschiedlich hergestellter Übergangsformen des Aluminiumoxids wurden zehn Al2O3/Cr2O3/K2O-Katalysatoren erhalten und auf ihre Eignung für die Dehydrocyclisierung von n-Hexan untersucht. Mit Hilfe von Röntgenphasenanalysen, Spinintensitätsmessungen des β-Signals (EPR) und reflexionsspektroskopischen Untersuchungen konnten die Katalysatoren hinsichtlich der Dispersität des Chromoxids klassifiziert werden. Sauerstoffchemisorptionsmessungen dienten zur Bestimmung der Größe der zugänglichen Chromoxidoberfläche. Geeignet als Träger sind Aluminiumoxide, die durch ein großes Oberflächenangebot eine hohe Dispersität des Chromoxids ermöglichen und die Zugänglichkeit zur Chromoxidoberfläche nicht beeinträchtigen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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