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  • 1
    ISSN: 1432-1335
    Keywords: Key words Acute lymphoblastic leukemia ; Methotrexate polyglutamates ; Thymidylate synthase ; Salvage pathway ; Relapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: In about 25% of patients suffering from acute lymphoblastic leukemia (ALL) treatment failures occur that are most likely due to development of resistance to methotrexate (MTX). Blasts from patients with ALL were evaluated for MTX uptake, formation of long-chain MTX polyglutamates (MTX-Glu5+6), cytotoxicity and thymidylate synthase inhibition by MTX and compared to blasts from patients with acute myelogenous leukemia (AML). Methods: Radioactively labeled MTX-Glu n were analyzed by means of HPLC. Thymidylate synthase activity was measured by a tritium-release assay. Cytotoxicity was determined by trypan blue exclusion. Results: In most ALL blasts (n = 9) large amounts of MTX-Glu5+6 (1.06–7.03 pmol/107cells) and high cytotoxicity (43.5%–92.7%) were found, while in others small amounts of MTX-Glu5+6 (0.0–0.39 pmol/107cells) caused only weak cytotoxicity (6.0%–27.9%) (n = 5, 2 relapsed patients). Resistance to MTX in blasts from AML patients (n = 5) was also caused by reduced synthesis of MTX-Glu5+6 (0.0–0.42 pmol/107cells). In contrast, some ALL blasts (n = 7, 4 relapsed patients) were able to survive MTX treatment despite large amounts of MTX-Glu5+6 (1.5–5.05 pmol/107cells) and extensive thymidylate synthase inhibition. Conclusions: Since the majority of ALL patients were examined at first diagnosis, an inherent mechanism of resistance seems most likely. We propose a mechanism based on the switch of thymidylate synthesis to the salvage pathway.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0474
    Keywords: Schlüsselwörter Nephroblastom ; Klinische Studie ; Präoperative Chemotherapie ; Diagnostische Sicherheit ; Therapiereduktion ; Key words Nephroblastoma ; Clinical trial ; Pre-operative chemotherapy ; Diagnostic accuracy ; Reduction of therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Background: In a new study the intensity of treatment used in the former Wilms' Tumor Study of the „Gesellschaft für Pädiatrische Onkologie und Hämatologie“ (GPOH) since 1980 had to be reduced maintaining the good results. Methods: 1989 the strategy of the International Society of Pediatric Oncology (SIOP) with pre-operative chemotherapy after diagnostic imaging was adopted. The pretreatment should reduce the tumorsize to allow complete tumor resection in most patients. Results: Of 505 patients enrolled in the study over 5.25 years from 78 participating centers, 486 had a nephroblastoma, 14 another malignant tumor and 5 a benign renal lesion. Of 438 patients with nephroblastoma aged between 0.5 and 16 years 85.4 % received pre-operative chemotherapy. Compared to the prior study the percentage of patients with irradiation (22.8 %) was lowered and the cumulative dose of Adriamycin for higher stages and unfavourable histology reduced. The 91 % probability of crude survival after 3 years for all nephroblastoma patients was similiar to the former study. Conclusions: The concept of general pre-operative chemotherapy for nephroblastoma was accepted by GPOH with evident reduction of treatment intensity compared to the prior study.
    Notes: Zusammenfassung Hintergrund: Die intensive Therapie der von der Gesellschaft für Pädiatrische Onkologie und Hämatologie (GPOH) ab 1980 durchgeführten Wilmstumorstudie sollte in der Folgestudie unter Wahrung der guten Ergebnisse reduziert werden. Methode: 1989 wurde das Therapiekonzept der International Society of Pediatric Oncology (SIOP) mit präoperativer Chemotherapie nach bildgebender Diagnose übernommen, wobei der Tumor durch die Vorbehandlung verkleinert wird, damit er bei einem Großteil der Kinder vollständig entfernbar ist. Ergebnisse: Bei 505 in 5,25 Jahren aus 78 Kliniken gemeldeten Patienten hatten 486 ein Nephroblastom, 14 ein anderes Malignom und 5 eine benigne renale Läsion. Von 438 gemeldeten Nephroblastompatienten zwischen 0,5 und 16 Jahren erhielten 85,4 % präoperativ eine Chemotherapie. Der Anteil bestrahlter Nephroblastompatienten (22,8 %) und die kumulative Adriamycindosis bei hohen Stadien bzw. hoher Malignität wurden im Vergleich zur Vorstudie reduziert bei ähnlicher Überlebenswahrscheinlichkeit von 91 % nach 3 Jahren. Schlußfolgerung: Das Konzept einer generellen präoperativen Chemotherapie zur Nephroblastombehandlung ist in der GPOH mit gutem Ergebnis und deutlicher Therapiereduktion im Vergleich zur Vorstudie durchzuführen.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0584
    Keywords: Acute leukemia ; (4; 11) chromosome translocation ; Early B-precursor cell origin ; Mixed lineage leukemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Clinical and laboratory features of seven patients with acute leukemia associated with the (4; 11) chromosome translocation are presented. Leukemic blasts of these patients showed lymphoid morphology in 6 (although 1 was treated for monoblastic leukemia 3 years earlier) and monocytoid morphology in 1, were positive for TdT and HD 37 (CD 19) in 6 patients, whereas weak expression of CALLA was seen in only 1 patient and T-lineage-associated antigens in none. Leukemic blasts from four patients showed the simultaneous expression of B-lymphoid and myeloid antigens, suggesting leukemogenesis in a very early multipotent progenitor cell. In 2 patients an isochromosome of the long arm of No. 7 chromosome was found in the leukemic karyotypes in addition to t (4; 11) (q21; q23); in one instance present at diagnosis, in the other one occurring at relapse. In one other patient leukemia karyotype also demonstrated trisomy 8. Leukemic cells of three patients were investigated by molecular genetics and demonstrated immunoglobulin gene rearrangements for the Ig heavy chain sequences but not for the light chain constant regions and T cell receptor sequences. All patients were treated by intensive chemotherapy. Four of the 7 patients are in continuous complete remission. The longest event-free survival time (over 2 1/2 years) was seen in one patient who had also DOWN-syndrome. Including these 7 patients a clinical analysis of 71 patients with t (4; 11) acute leukemia was made, emphasizing the following characteristics at diagnosis: female sex (62%), age under 2 years (49%), leukocyte count over 100×109/1 (61%), splenomegaly (80%), CNS-disease (11%). Survival of over 2 years was reported in less than 15% of the patients. It remains to be seen if risk-adapted treatment can alter the course of this early B-precursor acute leukemia with hitherto very bad prognosis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1335
    Keywords: Key words Acute lymphoblastic leukemia ; Methotrexate polyglutamates ; Lymphoblast preparation ; Red blood cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Blasts isolated from bone marrow aspirates or blood samples of patients with acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) were compared for uptake of methotrexate (MTX) and formation of MTX polyglutamates (MTX-Glu n ). Red blood cells (RBC) from the same patient samples were also analyzed. Methods: Blasts were isolated by standard density centrifugation. RBC were prepared from the pellet of the same centrifugation. MTX-Glu n were analyzed by means of HPLC and radiochemical quantification. Results: In lymphoblasts isolated from blood, the distribution patterns of MTX-Glu n were the same as in bone marrow lymphoblasts, but the total amount of MTX-Glu n accumulated in blood lymphoblasts was reduced by 41%–51% when compared to the same number of bone marrow lymphoblasts of the same patient. RBC accumulated MTX but no formation of MTX-Glu n occurred. Conclusions: The determination of MTX and MTX-Glu n in lymphoblasts isolated from blood samples of patients with common ALL provides qualitative information on the capacity of the blasts to form MTX-Glu n since distribution patterns of MTX and MTX-Glu n parallel that of bone marrow lymphoblasts. The amounts of MTX-Glu n accumulated, however, were much lower in blood lymphoblasts. Blood lymphoblasts are therefore not useful for a quantitative analysis of MTX-Glu n . The contribution of RBC to MTX and MTX-Glu n in vitro is only marginal and residual RBC in lymphoblast preparations from bone marrow can therefore be ignored.
    Type of Medium: Electronic Resource
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