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dc.contributor.authorChwalinski, S
dc.contributor.authorPotten, Christopher S
dc.date.accessioned2010-11-30T18:16:40Z
dc.date.available2010-11-30T18:16:40Z
dc.date.issued1986-11
dc.identifier.citationCell position dependence of labelling thymidine nucleotides using the de novo and salvage pathways in the crypt of small intestine. 1986, 19 (6):647-59 Cell Tissue Kineten
dc.identifier.issn0008-8730
dc.identifier.pmid3802186
dc.identifier.urihttp://hdl.handle.net/10541/116790
dc.description.abstractAbout twice as much tritiated thymidine ([3H]TdR) is taken up by cells at the bottom of the crypt of the small intestine as by the rapidly cycling mid-crypt cells. However, the uptake of tritiated deoxyuridine ([3H]UdR) is even throughout the crypt. Exogenous thymidine is incorporated about four times and eight times more efficiently than deoxyuridine by the cells in the mid-crypt and cells at the bottom of the crypt, respectively. However all S phase cells in the crypt appear to be capable of using either precursors, i.e. either the de novo or salvage pathway. Since methotrexate (1 or 5 mg/kg) inhibits (at 5 mg/kg completely) the uptake of [3H]UdR, but has no effect on [3H]TdR uptake, the de novo and salvage pathways appear to be independent. Within the precision of the methods used in the experiments the 3 hr inhibition of the de novo pathway of deoxythymidylic acid (dTMP) synthesis by methotrexate does not produce any increase in utilization of the salvage pathway measured by incorporation of [3H]TdR into DNA. The increased efficiency of thymidine utilization by crypt base cells is not attributable to differences in accessibility of thymidine; differences in the rate of DNA synthesis or the size of the nuclei. It appears that crypt base cells (which include the putative stem cells) are efficient scavengers of [3H]TdR, and this might be related to the level of thymidine kinase activity within the cells, and/or to changes in the availability of endogenous thymidine (break-down products) which compete with exogenous [3H]TdR.(ABSTRACT TRUNCATED AT 250 WORDS)
dc.language.isoenen
dc.subject.meshAnimals
dc.subject.meshDeoxyuracil Nucleotides
dc.subject.meshIntestinal Mucosa
dc.subject.meshIntestine, Small
dc.subject.meshMale
dc.subject.meshMethotrexate
dc.subject.meshMice
dc.subject.meshThymidine
dc.subject.meshThymidine Kinase
dc.subject.meshThymidine Phosphorylase
dc.titleCell position dependence of labelling thymidine nucleotides using the de novo and salvage pathways in the crypt of small intestine.en
dc.typeArticleen
dc.contributor.departmentPaterson Institute Laboratories, Manchester, M20 9BX. UK.en
dc.identifier.journalCell and Tissue Kineticsen
html.description.abstractAbout twice as much tritiated thymidine ([3H]TdR) is taken up by cells at the bottom of the crypt of the small intestine as by the rapidly cycling mid-crypt cells. However, the uptake of tritiated deoxyuridine ([3H]UdR) is even throughout the crypt. Exogenous thymidine is incorporated about four times and eight times more efficiently than deoxyuridine by the cells in the mid-crypt and cells at the bottom of the crypt, respectively. However all S phase cells in the crypt appear to be capable of using either precursors, i.e. either the de novo or salvage pathway. Since methotrexate (1 or 5 mg/kg) inhibits (at 5 mg/kg completely) the uptake of [3H]UdR, but has no effect on [3H]TdR uptake, the de novo and salvage pathways appear to be independent. Within the precision of the methods used in the experiments the 3 hr inhibition of the de novo pathway of deoxythymidylic acid (dTMP) synthesis by methotrexate does not produce any increase in utilization of the salvage pathway measured by incorporation of [3H]TdR into DNA. The increased efficiency of thymidine utilization by crypt base cells is not attributable to differences in accessibility of thymidine; differences in the rate of DNA synthesis or the size of the nuclei. It appears that crypt base cells (which include the putative stem cells) are efficient scavengers of [3H]TdR, and this might be related to the level of thymidine kinase activity within the cells, and/or to changes in the availability of endogenous thymidine (break-down products) which compete with exogenous [3H]TdR.(ABSTRACT TRUNCATED AT 250 WORDS)


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