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  • 1990-1994  (3)
  • Protein purification  (2)
  • Apoptose  (1)
  • 1
    ISSN: 1432-1963
    Keywords: Schlüsselwörter bcl-2 ; Osteosarkom ; Apoptose ; programmierter Zelltod ; Immunhistologie ; Proliferation ; Key words bcl-2 ; Osteosarcoma ; Apoptosis ; programmed cell death ; Immunohistochemistry ; Proliferation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The relationsship between the growth of tumors and the expression of the protooncogen Bcl-2 could be shown in epithelial tumors. A bcl-2 expression leads to a prolonged cell survival due to an inhibition of apoptosis. The potential meaning of bcl-2 expression in mesenchymal tumors remains still unknown. The fact, that the heterogenous group of osteosarkoma is not sufficiently characterized at present, suggested to investigate the bcl-2 expression in osteosarcoma. Thus, immunohistochemistry was used to analyze 47 specimens of different osteosarcomas of 36 patients. Sixteen cases (46 %) showed a strong expression of bcl-2 and 13 cases (35 %) were moderately positiv for bcl-2. Seven cases (19 %) were negative for bcl-2. The heterogenous, negative up to strong expression of bcl-2 yield clues, that the Bcl-2 controlled regulation of programmed cell death could be an important factor of cellular kinetics. Additionally the cellular proliferationrate was determined with the monoklonal antibody MIB 1, directed against the Ki-67 epitop. The data of bcl-2 expression and cellular proliferationrate lead to a classification correlating with the histological classification. To verify the importance of apoptosis in the genesis of mesenchymal tumors and whether Bcl-2 may play an important role as a predictive factor for the prognosis of osteosarcoma, further investigations will be needed.
    Notes: Zusammenfassung Bei zahlreichen epithelialen Geweben konnte ein Zusammenhang zwischen Tumorwachstum und der Expression des Protoonkogens Bcl-2 nachgewiesen werden. Eine bcl-2-Expression ist verbunden mit verlängertem Zellüberleben infolge einer Apoptoseinhibition. Hingegen ist über die bcl-2-Expression und deren mögliche Bedeutung in mesenchymalen Tumoren wenig bekannt. Da die heterogene Gruppe der Osteosarkome mit den derzeitigen methodischen Mitteln nicht hinreichend charakterisierbar ist, wurde die bcl-2-Expression untersucht. Immunhistologisch wurden 47 Osteosarkompräparate von 36 Patienten unterschiedlicher Subtypen analysiert. Von den 36 Fällen zeigten in der Biopsie 16 Fälle (46 %) eine stark positive und 13 Fälle (35 %) eine mittelgradig positive bcl-2 Expression. Sieben Fälle (19 %) waren bcl-2-negativ. Die heterogene, fehlende bis starke bcl-2-Expression deutet darauf hin, daß in Osteosarkomen die Bcl-2-gesteuerte Regulation des programmierten Zelltodes einen Faktor in der zellulären Wachstumskinetik darstellt. Zusätzlich wurde die Proliferationsrate, anhand des gegen das Ki-67-Antigen gerichteten monoklonalen Antikörper MIB-1 bestimmt. Aus den Daten zur bcl-2-Expression und Proliferationsrate ergibt sich eine Einteilung, die eine Übereinstimmung mit der histologischen Klassifikation aufweist. Welche Bedeutung die Apoptose in der Genese mesenchymaler Tumoren hat und ob die bcl-2-Expression einen prädiktiven Wert für die Prognose von Osteosarkomen besitzt, bedarf weiterer Untersuchungen.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Enzyme modulation ; Nitrate reductase ; Protein kinase ; Protein phosphorylation ; Protein purification ; Spinacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using a three-step purification procedure, two protein fractions which catalyzed the ATP-dependent in-activation of nitrate reductase (NR) were obtained from spinach (Spinacia oleracea L.) leaf extracts. Purification involved ammonium-sulfate fractionation, anion-exchange chromatography and size-exclusion chromatography. The capacity of the fractions to inactivate NR by preincubation with ATP was examined by using as target either a crude NR-ammonium sulfate precipitate or partially purified NR (ppNR). The fractions were also examined for protein-kinase activity by measuring the phosphorylation of histone III S (or casein) with γ-[32P]ATP as substrate, and subsequent SDS-PAGE, autoradiography and liquid scintillation counting of cut-off histone bands. The two proteins had apparent molecular weights in the 67-kDa and 100-kDa region (termed P67 and P100, respectively). Neither P67 nor P100 alone was able to inactivate ppNR by preincubation with ATP. However, when P100 and P67 were added together to ppNR, ATP-dependent inactivation was observed, with a half-time of about 10 min. The P67, but not P100 had histone-kinase activity (casein was not phosphorylated). Using the partially purified system, various compounds were examined as possible effectors of NR inactivation. Sugar phosphates had little effect on the inactivation of NR. Addition of AMP at very high concentrations (5 mM), and removal of Mg2+ by excess EDTA also prevented the inactivation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Enzyme modulation ; Nitrate reductase ; Protein kinase ; Protein phosphorylation ; Protein purification ; Spinacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using a three-step purification procedure, two protein fractions which catalyzed the ATP-dependent in-activation of nitrate reductase (NR) were obtained from spinach (Spinacia oleracea L.) leaf extracts. Purification involved ammonium-sulfate fractionation, anion-exchange chromatography and size-exclusion chromatography. The capacity of the fractions to inactivate NR by preincubation with ATP was examined by using as target either a crude NR-ammonium sulfate precipitate or partially purified NR (ppNR). The fractions were also examined for protein-kinase activity by measuring the phosphorylation of histone III S (or casein) withγ-[32P]ATP as substrate, and subsequent SDS-PAGE, autoradiography and liquid scintillation counting of cut-off histone bands. The two proteins had apparent molecular weights in the 67-kDa and 100-kDa region (termed P67 and P100, respectively). Neither P67 nor P100 alone was able to inactivate ppNR by preincubation with ATP. However, when P100 and P67 were added together to ppNR, ATP-dependent inactivation was observed, with a half-time of about 10 min. The P67, but not P100 had histone-kinase activity (casein was not phosphorylated). Using the partially purified system, various compounds were examined as possible effectors of NR inactivation. Sugar phosphates had little effect on the inactivation of NR. Addition of AMP at very high concentrations (5 mM), and removal of Mg2+ by excess EDTA also prevented the inactivation.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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