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  • 1
    Electronic Resource
    Electronic Resource
    Differential modulation of chemosensitivity to alkylating agents and platinum compounds by DNA repair modulators in human lung cancer cell lines (2000)
    Springer
    Journal of cancer research and clinical oncology 126 (2000), S. 198-204 
    Details
    ISSN: 1432-1335
    Keywords: Key words DNA repair ; Resistance modifier ; Drug resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Modulation of DNA repair represents one strategy to overcome cellular drug resistance to alkylating agents and platinum compounds. The effects of different known DNA repair modulators such as O 6-benzylguanine (6 μg/ml), fludarabine (25 ng/ml), aphidicolin (8.5 ng/ml), pentoxifylline (1.4 μg/ml) and methoxamine (12.4 μg/ml) on the cytotoxicity of mafosfamide, chlorambucil, 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU), cisplatin and carboplatin were tested in human lung cancer cell lines. Methods: Chemosensitivity of the human adenocarcinoma cell line MOR/P and the cisplatin-resistant subline MOR/CPR as well as the large-cell lung cancer cell line L23/P and its cisplatin-resistant counterpart L23/CPR were evaluated by the MTT colorimetric assay. Results: O 6-benzylguanine, an inhibitor of O 6-alkylguanine-DNA alkyltransferase, significantly sensitised MOR/P and MOR/CPR cells to the cytotoxic effect of BCNU. Fludarabine, methoxamine and aphidicolin did not change the chemosensitivity of the parental and cisplatin-resistant cell lines to any cytotoxic drug tested. Interestingly, O 6-benzylguanine enhanced the chemoresistance of parental and cisplatin-resistant cell lines to platinum compounds. Also, pentoxifylline increased resistance of the MOR cell lines to mafosfamide. Conclusions: Modulation of DNA repair elicits not only chemosensitisation but may also enhance cellular resistance to DNA-affine drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004320050033
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  • 2
    Electronic Resource
    Electronic Resource
    Type and position of promoter elements in retroviral vectors have substantial effects on the expression level of an enhanced green fluorescent protein reporter gene (2000)
    Springer
    Journal of cancer research and clinical oncology 126 (2000), S. 391-399 
    Details
    ISSN: 1432-1335
    Keywords: Key words Retroviral vector ; Green fluorescent protein ; Gene therapy ; Internal promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Although gene transfer with retroviral vectors has already been applied to patients as part of clinical protocols, low expression of transgenes in target cells still remains a problem. Therefore, we compared various retroviral vectors using different promoters and backbones for expression of the enhanced green fluorescent protein (EGFP) reporter gene in fibroblasts and CD34+ cells. Methods: The N2A retroviral vector was used to test expression from the herpes simplex virus thymidine kinase promoter (vector N2A-TK-EGFP), a human phosphoglycerate kinase promoter (vector N2A-PGK-EGFP), and the SV40 promoter (vector N2A-SV-EGFP). Additional constructs used the spleen focus-forming virus (SFFV) long terminal repeat (LTR) as promoter and expressed EGFP alone (vector SFβ1-EGFP) or EGFP and a downstream (vector SFβ1-EGFP-IRES) or upstream (vector SFβ1-IRES-EGFP) internal ribosomal entry site. Results: For NIH 3T3 cells the fluorescence-activated cell sorting analysis revealed that the most active internal promoter was the SV40 promoter in the vector N2A-SV-EGFP (mean fluorescence intensity, MFI, 66.7 ± 0.4), followed by N2A-PGK-EGFP (26.3 ± 1.8 MFI), and N2A-TK-EGFP (4.8 ± 0.1 MFI). Expression from the SFβ1-EGFP vector (82.6 ± 6.7 MFI) and the SFβ1-EGFP-IRES vector (102.8 ± 6.2 MFI) was higher than from SFβ1-IRES-EGFP vector (15.5 ± 1.8 MFI). In human CD34-positive cells, the EGFP expression from all vectors was considerably lower than in fibroblasts with the SFβ1-EGFP vector still being four- to fivefold more active than the internal promoters tested. Conclusion: The SFFV LTR seems to allow a high expression of transgenes, as long as the transgene is not expressed downstream of an internal ribosomal entry site. Internal promoters may be useful for targeted gene expression in specific cell types, but the reduced level of expression from some internal promoters has to be taken into consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008487
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  • 3
    Electronic Resource
    Electronic Resource
    Ras-Farnesyltransferase-Inhibitoren (2000)
    Springer
    Der Onkologe 6 (2000), S. S24 
    Details
    ISSN: 1433-0415
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Mutationen in Ras-(Proto-)Onkogenen führen zu unkontrolliertem Funktionsgewinn (“gain of function”) für die entsprechenden Ras-Proteine. Diese unkontrolliert aktiven Ras-Proteine sind wesentliche Faktoren in der humanen Kanzerogenese und somit eine attraktive Zielgruppe für pharmakologisch-antineoplastische Interventionen. Zur Ras-Aktivierung sind bestimmte biochemische Modifikationen notwendig, von denen die Prenylierungsreaktion durch die Farnesyltransferase (FTAse) besonders wichtig ist. Es wurden mittlerweile eine Vielzahl strukturell unterschiedlicher Moleküle entwickelt, die teilweise hochpotent und selektiv die FTase in Zellkulturen sowie in unterschiedlichen Tiermodellen inhibieren. Neben den gut dokumentierten in-vitro- und in-vivo-Aktivitäten von FTase-Inhibitoren sind die exakten zellphysiologischen Mechanismen der Zytotoxizität bisher nur unvollständig bekannt. Es gibt zudem experimentelle Hinweise auf synergistische oder additive Zytotoxizität durch die Kombination von FTase-Inhibitoren mit gegenwärtigen Standardzytostatika.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007610070009
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  • 4
    Electronic Resource
    Electronic Resource
    The amount of BCR-ABL fusion transcripts detected by the real-time quantitative polymerase chain reaction method in patients with Philadelphia chromosome positive chronic myeloid leukemia correlates with the disease stage (2000)
    Springer
    Annals of hematology 79 (2000), S. 424-431 
    Details
    ISSN: 1432-0584
    Keywords: Key words BCR-ABL fusion transcripts ; Real-time quantitative polymerase chain reaction ; Philadelphia chromosome ; Chronic myeloid leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The use of the real-time reverse-transcription polymerase-chain reaction (RT-PCR) method to quantify BCR-ABL transcripts before and after allogeneic transplant was prospectively studied in 65 patients with chronic myeloid leukemia (CML). The expression of the BCR-ABL transcript was determined and normalized using the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) housekeeping gene product as an endogenous reference. In the single step real-time PCR assay, tenfold serial dilutions of cDNA of the K5652 cell line remained positive down to 100 pg cDNA only. However, molecular relapses of CML after transplant were only safely detectable when a nested real-time PCR assay was performed, which was able to detect 1–10 pg cDNA from a tenfold serial dilution. The median normalized BCR-ABL transcript level was measured as 0.004% in 17 patients with a molecular relapse, 0.4% in 7 patients with a cytogenetic relapse, 2.6% in 36 patients with a stable phase of CML, and 36% in 5 patients with a relapse in a blast crisis. The analyzed median normalized amount of BCR-ABL transcript differed significantly (P〈0.001) between the various disease stages. In ten CML patients with relapse, the real-time PCR method was used to monitor the response of various immunotherapies as donor leukocyte infusions, withdrawal of immunosuppression, or interferon-α application. The results of the quantitative evaluation of BCR-ABL transcripts reflected very well the clinical effect of the different applied immunotherapies. The new real-time PCR method seems to be a suitable technique for the early detection of relapse after allogeneic transplant in patients with the BCR-ABL transcript. Its ability to distinguish between molecular and cytogenetic relapse (P〈0.001) allows early therapeutic decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770000169
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  • 5
    Electronic Resource
    Electronic Resource
    Transplant activities in Germany in 1998 – a survey facilitated by the National Registry for Hemopoietic Stem Cell Transplantation (2000)
    Springer
    Annals of hematology 79 (2000), S. 437-443 
    Details
    ISSN: 1432-0584
    Keywords: Key words Blood stem cell transplantation ; Data management quality control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To improve the infrastructure of hemopoietic stem-cell transplantations in our country, the German Registry for Hemopoietic Stem-Cell Transplantations (DRST) was established in 1998. The present paper summarizes the current status of the DRST and gives a survey of transplant activities in Germany in 1998 in terms of transplant units, transplant types, transplant frequencies and underlying diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770000194
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  • 6
    Electronic Resource
    Electronic Resource
    Long-term survival after induction therapy with idarubicin and cytosine arabinoside for de novo acute myeloid leukemia (2000)
    Springer
    Annals of hematology 79 (2000), S. 533-542 
    Details
    ISSN: 1432-0584
    Keywords: Key words Acute myeloid leukemia ; Cytosine arabinoside ; Idarubicin ; Induction therapy ; Karyotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We treated 153 patients with de novo acute myeloid leukemia (AML) with two induction courses of conventional-dose cytosine arabinoside (ara-C) and idarubicin (AIDA) followed by either a third course of AIDA, high-dose ara-C or bone-marrow transplantation. The complete remission (CR) rate for all patients was 63.4%, with a higher CR rate for patients with a normal (versus unfavorable) karyotype (73.2% vs 52.5%;P=0.038). The probability of overall survival (OS) was 30.7% after 5 years (26.3% after 7 years). Improved OS at 5 years could be observed for patients up to 50 years old versus patients older than 50 years of age (37.6% vs 19.9%;P=0.001) and patients with a normal (versus unfavorable) karyotype (42.9% vs 14.1%;P=0.0016). Disease-free survival (DFS) after 5 years was 33.2% for all 97 CR patients and was significantly better for patients with a normal (versus unfavorable) karyotype (44.3% vs 12.3%;P=0.003). Multivariate analysis revealed that the age for OS (P〈0.02) and the karyotype for both OS (P〈0.03) and DFS (P〈0.05) were independent prognostic factors. In conclusion, AIDA is an effective and well-tolerated induction regimen (even in elderly patients) with a 5-year survival of more than 30% when combined with ara-C-containing postremission therapy. The karyotype is the most powerful prognostic factor for predicting the outcome of patients treated with this protocol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770000193
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