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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 327 (1970), S. 1052-1053 
    ISSN: 1435-2451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of gynecology and obstetrics 219 (1975), S. 497-498 
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0711
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 20 (1981), S. 219-224 
    ISSN: 1432-1041
    Keywords: triamterene ; folate antagonism ; triamterene metabolites ; dihydrofolate reductase ; DNA metabolism ; human leucocytes ; BJAB-B95-8 ; lymphoma cell line
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The inhibitory effect of triamterene and its metabolites on human leucocyte dihydrofolate reductase has been studied. Under test conditions with dihydrofolic acid 0.5×10−5 M, triamterene 7×10−5 M produced total enzyme inhibition, whereas the metabolites hydroxytriamterene and the sulphate ester of hydroxytriamterene were less effective inhibitors; at their maximum attainable concentration of 5×10−5 M, dihydrofolate reductase was inhibited by 80% and 50%, respectively. Cultures of the BJAB-B95-8 human lymphoma cell line were incubated with various concentrations of triamterene. Because of their increased specific activity of dihydrofolate reductase, the cells were able to maintain normal DNA metabolism, as measured by the ratio of the incorporation rates of 3H-deoxyuridine and 3H-thymidine, as well as normal cell growth at 1×10−6 M, and in some cases at 1 × 10−5 M triamterene. At 8×10−5 M triamterene, the strong inhibitory effect caused severe impairment of DNA metabolism and subsequently dissolution of the cell culture. The results are discussed in relation to the possible toxic side effects of long-term triamterene treatment in patients suffering from alcoholic cirrhosis, who may have impaired metabolism of triamterene and a concomitant severe folate deficiency.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 50 (1972), S. 986-990 
    ISSN: 1432-1440
    Keywords: Methionine synthetase ; clinical chemistry ; folic acid ; vitamin B12 ; one-carbon units ; nucleotide biosynthesis ; Methionin-Synthetase ; klinische Chemie ; Folsäure ; Vitamin B12 ; Einkohlenstoffeinheiten ; Nucleotid-Biosynthese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wegen der Schlüsselstellung der Methionin-Synthetase (MS) im Stoffwechsel der Folsäure und damit der Einkohlenstoff-Einheiten sowie der „essentiellen“ Aminosäure Methionin als Starter der Protein- und Enzymsynthese wurde ein unaufwendiges und gut reproduzierbares Bestimmungsverfahren für dieses Enzyme ausgearbeitet. Nach Ermittlung der optimalen Bedingungen wurden Organe verschiedener Tiere auf ihre MS-Aktivität geprüft. Eine Anwendung des routinemäßig einfachen Verfahrens für kinetische Untersuchungen an menschlichem Gewebe und Blutzellen scheint möglich. Zellen, die eine große Teilungsrate und somit eine erhöhte Nucleotid- und Proteinsynthese aufweisen, haben offenbar eine erhöhte spezifisch Aktivität der Methionin-Synthetase gegenüber langsam oder nicht mehr wachsenden Populationen.
    Notes: Summary The methionine synthetase (MS) reaction holds a key role in the metabolism of folic acid and one-carbone units. Of secondary importance probably is the formation of the “essential” amino acid methionine which induces protein and enzyme synthesis. Based on the formation of labelled methionine from14C-methyl-tetrahydrofolate, an assay for MS activity is described which is both easily performed and reproduced. Optimal conditions were established and several organs of different animals screened for their MS activity. In rapidly dividing cells in which nucleotide and protein synthesis is elevated, the specific activity of MS is enhanced as compared to slowly or not at all growing cell populations. It seems feasible to adopt this simple assay in the routine analysis of cellular biokinetics in human tissues and blood cells.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 50 (1972), S. 991-994 
    ISSN: 1432-1440
    Keywords: Methionine synthetase ; nucleotide biosynthesis ; essential amino acid ; blood cells ; bone-marrow ; leukaemia ; Methionin-Synthetase ; Nucleotid-Biosynthese ; essentielle Aminosäure ; Blutzellen ; Knochenmark ; Leukämie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Methioninsynthetase-Aktivität wurde in verschiedenen menschlichen Geweben, malignen Neubildungen, normalen und pathologischen Zellen des Blutes und Knochenmarks nachgewiesen und damit eine Synthese von Methionin in ausreichender Menge im menschlichen Organismus bewiesen. Der essentielle Charakter dieser Aminosäure ist damit aufgehoben. In den normalen Blutzellen verhält sich die Methioninsynthetase entsprechend der gesteigerten Stoffwechselaktivität kernhaltiger und teilungsfähighiger Zellen. Bei akuten myeloischen Leukämien ist die MS-Aktivität im Vergleich zu normalen Leukocyten- und Knochenmarkwerten um das 3,5- bzw. 2fache erhöht. Hingegen zeigen die Blutzellen von akuten und chronischen lymphatischen wie auch von chronisch myeloischen Leukämien subnormale Werte. Diese unterschiedlichen Aktivitäten der Methioninsynthetase in der akuten myeloischen Leukämie und der akuten lymphatischen Leukämie sowie den chronischen Formen lassen sich differentialdiagnostisch in der Weise verwerten, daß die angegebene Methode zur Enzymdiagnose und Kontrolle von Leukämien dienen kann. Ebenso kann ein Therapieerfolg dokumentiert werden.
    Notes: Summary Methionine synthetase (MS) activity was determined in different normal and carcinomatous human tissues, as well as in normal and pathological cells of both blood and bone-marrow. It was demonstrable that a sufficient amount of methionine is synthesized in the human body. That methionine is no longer to be considered an essential amino acid is thus proven. In normal blood cells, methionine synthetase is proportional to the metabolic activity of nucleus-containing or proliferating cells. In acute myelocytic leukaemia, MS activity is 3.5 times higher in leukocytes and 2 times higher in bonemarrow cells compared to normal subjects. In contrast, the blood cells of acute and chronic lymphatic leukaemia and chronic myelocytic leukamia show subnormal values. the different activities of methionine synthetase can be used to distinguish acute myelocytic leukaemia from acute lymphatic leukaemia, as well as from the chronic forms, and to assess the therapeutic progress.
    Type of Medium: Electronic Resource
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