Linked Life Data

1867645

Source:http://linkedlifedata.com/resource/pubmed/id/1867645

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1991-9-9
pubmed:abstractText
Chronic exposure of H9 cells to 25 microM zidovudine (H9-AZT cells) causes a 2- to 3-fold increase in thymidine kinase (TK) activity (Agarwal RP, Int J Purines Pyrimidine Res, in press). The present study compared thymidine (TdR) and AZT anabolism in H9 and H9-AZT cells. After a 3.5-hr incubation with 10 microM TdR or AZT, the total intracellular accumulations of AZT (48.7 microM in H9 cells and 32.8 microM in H9-AZT cells) were 46.4% of TdR accumulation. Other major differences between TdR and AZT anabolism were: (i) the majority of TdR (84-87%) was incorporated into DNA compared to less than 1% of AZT; and (ii) whereas distribution of TdR in the nucleotides was TTP greater than TMP greater than TDP, zidovudine distributed was AZT-MP much greater than AZT-TP much greater than AZT-DP. Because of the poor substrate activity of AZT-MP for thymidylate kinase (TMP-kinase), most of the AZT (95-98%) remained as AZT-MP. TMP-kinase activities with TMP as substrate were 47.6 +/- 20.3 and 91.4 +/- 28.8 pmol/mg protein/min in H9 and H9-AZT cells, respectively. 5'-Nucleotidase activities with TMP as substrate were 428.9 +/- 37.8 and 255.9 +/- 28.7 pmol/mg protein/min in H9 and H9-AZT cells, respectively. Activities of these enzymes with AZT-MP as a substrate were very low. Despite an increase in TK and TMP-kinase, and a decrease in 5'-nucleotidase activities, the total intracellular accumulations of TdR and AZT were reduced significantly (P less than 0.05) to 67.5% in H9-AZT cells. Thymidine transport (0.66 to 0.68 pmol/sec/10(6) cells) was similar in both the cell lines. The severe reductions of TdR salvage caused by chronic exposure of cells to AZT, if it occurs in AIDS patients on AZT chemotherapy, may explain some of the long-term clinical toxicities of the drug.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2952
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
42
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
905-11
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Thymidine and zidovudine metabolism in chronically zidovudine-exposed cells in vitro.
pubmed:affiliation
Department of Oncology, University of Miami School of Medicine, FL 33136.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.