Linked Life Data

6622648

Source:http://linkedlifedata.com/resource/pubmed/id/6622648

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1983-11-23
pubmed:abstractText
Overnight exposure of Chinese hamster cells (V. 79-753B) in vitro to 1 micrograms/ml dexamethasone increases the radiation resistance of the cells by about 20% both in air and in hypoxia, while having no appreciable effect on the oxygen enhancement ratio (OER). This is accompanied by substantially higher levels of glutathione. When dexamethasone-treated hypoxic cells are irradiated in the presence of nitroxyl biradicals there is no effect on the slope ratio of of the exponential portion of the survival curves. In the case of uncharged biradicals, Ro.03-6061 and RSU-4072. which have been shown to modify the shoulder region of the hypoxic cell survival curve, there is an increase in extrapolation number in dexamethasone-treated cells. When hypoxic cells are exposed to the charged biradical RSU-4073, which does not exhibit shoulder modification, there is no change in extrapolation number. Experiments to examine the effect of concentration of these compounds on radiosensitization show that lower concentrations of both RSU-4072 and RSU-4073 are required to mediate changes in the slope of the hypoxic cell survival curve than to mediate shoulder modification, in the case of RSU-4072. Quantitative ESR data comparing the uptake of RSU-4072 and RSU-4073 with the monoradical TMPN into cells suggest that the cell membrane may act as a barrier to the incorporation of biradicals, and that this is greater for charged than for uncharged compounds. Treatment of cells with dexamethasone does not affect the uptake of the compounds. The data suggest, however, that the cell membrane may be an important site for localization of uncharged biradicals and that this may be important in determining shoulder modification.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0033-7587
pubmed:author
pubmed:issnType
Print
pubmed:volume
96
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
160-72
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1983
pubmed:articleTitle
Polyfunctional Radiosensitizers. VI. Dexamethasone inhibits shoulder modification by uncharged nitroxyl biradicals in mammalian cells irradiated in vitro.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't