Die Aktivität der Methionin-Synthetase (5-Methyl-5,6,7,8-tetrahydrofolsäure: Homocystein Methyltransferase) als Proliferationsparameter in wachsenden Zellen1

Sauer, H.; Wilms, K.; Wilmanns, W.; Jaenicke, Lothar

doi:10.1159/000208406

Cited by 12 publications

(9 citation statements)

References 10 publications

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“…The activity in stimulated PBL, for example, increased with cell transformation and while peaking during active proliferation did not subsequently decline abruptly (Hall, 1984). Sauer et al (1973) found the MS activity of lymphoblasts to peak early, but then to decline sharply. This is in contrast to the RPMI 6410 lymphoblasts that expressed maximum MS activity at 72 h when the binding of TC 11-Cbl was the least (data not shown).…”

Section: Day Of Culturementioning

confidence: 98%

Cyclic activity of the receptors of cobalamin bound to transcobalamin II

Hall

Colligan

Begley

1987

Journal Cellular Physiology

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The activity of receptors specific for human transcobalamin II-Cobalamin (TC II-Cbl) were measured in virus-transformed lymphoblasts, hepatocytes (hepatoma) and diploid fibro lasts. In all three types of human cells the receptor activity increased as cells went from a resting phase to the most actively dividing phase. Receptor activity declined as cell division slowed. The changes in activity of lymphoblasts and hepatocytes were produced by changes in receptor number and not by changes in affinity between receptors and TC II-Cbl. The basis of the change in fibroblasts was not clear. The Cbl-dependent methionine synthetase activity of fibroblasts, in contrast, tended to be greatest when the cultures were confluent and replication had slowed. As the fibroblasts became senescent the receptor activity for TC II-Cbl declined and the fluctuations with the phase of the cell were blunted. However, the release of apo TC II from the cells was maintained. These observations must be taken into consideration when the respective cells are used as models. Even more important are the implications of the observations of the changes in receptor activity for TC II-Cbl for the regulation of the entry of Cbl into cells.

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Section: Day Of Culturementioning

confidence: 98%

Cyclic activity of the receptors of cobalamin bound to transcobalamin II

Hall

Colligan

Begley

1987

Journal Cellular Physiology

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“…At diagnosis, four patients were in stage I, 10 in stage 11, and seven in stage 111 according to Tura et al (1981). methionine synthetase is especially active in the S-phase of the cell cycle (Sauer et al 1973). The median survival was 40.3 months (range 0.1-112.5 months).…”

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confidence: 99%

Cobalamin forms and analogues in plasma and myeloid cells during chronic myelogenous leukaemia related to clinical condition

Gimsing

1995

Br J Haematol

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Plasma and buffy coat specimens of CML patients with untreated disease, in chronic and accelerated phase, and in overt blastic crises were analysed for the cobalamin patterns using non-polar extraction, thin-layer chromatography and bioautography . Splenic tissue specimens from four splenectomized patients in accelerated phase were analysed similarly. Cellular extracts were separated into two compartments by adsorption to haptocorrin antibodies. Plasma concentrations of all cobalamin forms were increased in CML. The proportion of methylcobalamin was significantly lower than in a reference population, and a low plasma proportion of methylcobalamin was associated with a poor prognosis. Buffy coat cells and splenic tissue had a higher proportion of 5'-deoxyadenosylcobalamin and a lower proportion of methylcobalamin than plasma; still, there was relatively more methylcobalamin than in normal tissue. The haptocorrin-bound compartment differed from the non-haptocorrin compartment in untreated or chronic phase patients by binding less methylcobalamin. An estimate of cobalamin analogues in plasma was achieved by comparing two different isotope dilution assays employing a cobalamin-specific binder, intrinsic factor, and a nonspecific binder, hog non-intrinsic factor. Values for total cobalamin and analogues were increased to the same degree in CML plasma.

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“…Enzyme activity is higher in normal lymphocytes than in granulocytes and is higher still in lymphocytes from patients with CLL. Others (12,43) have found that leukocytic enzyme activity is increased in acute but not chronic leukemias. Since in these experiments lymphocytes were not isolated before preparation of cell extracts, reported normal values cannot be compared directly with the values reported here.…”

Section: Discussionmentioning

confidence: 97%

“…In a number of instances, increased methyltransferase activity can be correlated with accelerated cell division, e.g., in certain phases of lymphoblastic leukemia or during the log phase of growth in phytohemagglutininstimulated lymphocytes (43). Methyltransferase activity has been found to increase in parallel with certain enzymes known to participate in cell division (e.g., DNA polymerase and thymidine kinase) (43).…”

Section: Discussionmentioning

confidence: 99%