Linked Life Data

7693961

Source:http://linkedlifedata.com/resource/pubmed/id/7693961

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2-3
pubmed:dateCreated
1993-12-13
pubmed:abstractText
A number of lines of evidence suggest that serum paraoxonase is protective against poisoning by organophosphorus substrates of this enzyme. Birds that have very low levels of paraoxon hydrolyzing activity in their sera are very susceptible to parathion poisoning. Rabbits, which have a sevenfold higher enzyme level compared with rats, have a fourfold higher resistance to paraoxon poisoning than rats. Rabbit paraoxonase hydrolyzes chlorpyrifos-oxon with a much higher turnover number than does rat paraoxonase, resulting in a very high resistance of rabbits to chlorpyrifos toxicity. Direct tests of paraoxonase protection have been carried out by injecting purified rabbit enzyme into rats. The protection achieved was higher for chlorpyrifos-oxon than for paraoxon, probably due to the high hydrolytic activity of the rabbit enzyme for chlorpyrifos-oxon. In humans, a substrate-dependent polymorphism of serum paraoxonase is observed, where one isoform of paraoxonase has a high turnover number for paraoxon and the other a low turnover number. Both isoforms appear to hydrolyze chlorpyrifos-oxon and phenylacetate at the same rate. Cloning and sequencing of the human paraoxonase cDNAs has elucidated the molecular basis of the polymorphism. Arginine at position 192 determines high paraoxonase activity, and glutamine at this position, low paraoxonase activity. In addition to the polymorphism, a 13-fold variation in serum enzyme levels within a given genetic class is seen. The experiments reported here demonstrate that rabbit paraoxonase injected into mice provides protection against the parent insecticide chlorpyrifos as well as the toxic oxon. These results suggest that serum paraoxonase status may serve as a biomarker for insecticide susceptibility in humans.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0098-4108
pubmed:author
pubmed:issnType
Print
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
337-46
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:articleTitle
Serum paraoxonase status: a major factor in determining resistance to organophosphates.
pubmed:affiliation
Department of Environmental Health, University of Washington, Seattle 98195.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.