Linked Life Data

510081

Source:http://linkedlifedata.com/resource/pubmed/id/510081

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1980-2-28
pubmed:abstractText
PG19T3 mouse melanoma cells were selected for resistance to methotrexate. Nine sub-lines that are resistant to concentrations of methotrexate ranging from 1.27 x 10(-7) M, to 1 x 10(-4) M methotrexate were selected and characterised in terms of their content of dihydrofolate reductase activity and their chromosomes. The intracellular level of dihydrofolate reductase activity increases with increasing resistance such that at the highest level of resistance PG19T3:MTXR10(-4)M cells contain approximately 1,000 fold more enzyme activity than the parental PG19T3 cells. It is shown that the enhanced activity is due to an increase in the amount of the enzyme rather than any structural change to the enzyme in resistant cells. Comparisons of pH activity profiles, profiles under different activating conditions and titrations with methotrexate suggest that the sensitive and resistant cells contain identical dihydrofolate reductases. Analysis of the chromosomes of resistant cells shows the presence of up to 5 large marker chromosomes which contain homogeneously staining regions after G-banding. These same regions stain intensely after C-banding and fluoresce brightly after staining with Hoechst 33258. The size of homogeneously staining regions increases throughout the process of selection. For one marker chromosome this increase may have been mediated via a ring chromosome.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0009-5915
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
153-77
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1979
pubmed:articleTitle
The development of resistance to methotrexate in a mouse melanoma cell line. I. Characterisation of the dihydrofolate reductases and chromosomes in sensitive and resistant cells.
pubmed:publicationType
Journal Article, Comparative Study