Linked Life Data

7150485

Source:http://linkedlifedata.com/resource/pubmed/id/7150485

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1983-3-11
pubmed:abstractText
The cytotoxicity of 3 electron-affinic radiosensitizers has been studied in Chinese hamster V-79 cells as a function of pH and modest hyperthermia. When equitoxic concentrations were used and temperature was increased from 34 to 41 degrees C metronidazole, the compound with the lowest electron affinity showed the greatest enhancement of hypoxic-cell toxicity, and nitrofurantoin, the compound with the highest electron affinity, the least. The results can be explained if the mechanisms of toxicity involves a redox reaction, since it would be expected that the least toxic compound (lowest electron affinity) would have the largest activation energy and hence the greatest temperature effect. This appears to hold for these 3 compounds. Experiments also showed that nitrofurantoin which exhibits no increase in toxicity when the temperature was increased from 37 to 41 degrees C at pH 7.4, showed an increase in toxicity for the same temperature change at the pH of 7.0 and 6.6. Under aerobic conditions only metronidazole showed significant toxicity at 41 degrees C, where the differential between aerobic and hypoxic cell toxicity was minimal, both at pH 7.4, and at the low pH values of 7.0 and 6.6. In the clinical setting there is evidence that tumour cells are at a lower pH than their surrounding normal tissues. Hypoxic-cell cytotoxicity is enhanced at low pH, and even further enhanced at low pH in combination with a temperature of 41 degrees C. However, this finding correlates conversely with electron affinity. Thus, the radiosensitizer (and trichomonicide) metronidazole is most influenced by low pH and high temperature with the nitroimidazole, misonidazole, demonstrating a smaller enhancement due to higher temperatures.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0007-0920
pubmed:author
pubmed:issnType
Print
pubmed:volume
46
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
912-7
pubmed:dateRevised
2009-11-18
pubmed:meshHeading
pubmed:year
1982
pubmed:articleTitle
Enhancement of the cytotoxicity of radiosensitizers by modest hyperthermia: the electron-affinity relationship.
pubmed:publicationType
Journal Article