2007 Flight International Crew Management Conference. Biomarkers of Exposure to TCP Clement E. Furlong Departments of Medicine (Div. Medical Genetics) & Genome Sciences firstname.lastname@example.org.
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2007 Flight InternationalCrew ManagementConference
Biomarkers of Exposure to TCP
Clement E. Furlong
Departments of Medicine (Div. Medical Genetics) & Genome Sciences
Status ReportToday, I would like to present a progress report on research related to two of the issues that are important in exploring questions related to exposures in aircraft cabins and flight decks that result from engine seal failure.
- known effects of OP exposure on the immune system
- they possess an OP sensitive carboxyl esterase
- they are readily accessible with a blood draw
Discussions at two conferences on cabin air quality (London – 2005; Boeing, Everett, WA - 2004) pointed to the urgent need for developing a method to determine whether or not an individual had been exposed to toxic organo-phosphorus (OP) compounds (e.g. TCP) during a fume event
Tricresyl phosphate isomers are
present in jet engine lubricants
The methyl groups can be:
THE HISTOPATHOLOGY OF TRIORTHOCRESYL PHOSPHATE POISONING.
Smith, ML and Lillie RD.
Arch Neurol Pshchiat, Chicago 26:976 (1931)
“The histology of the nervous system in paralysis due to adulterated fluidextract of ginger in man has been studied and compared with the effects produced by triorthocresyl phosphate in experimental animals.
The results indicate that the multiple neuritis of this paralysis is essentially a degeneration of the myelin sheaths of the peripheral nerves, with a variable amount of relatively moderate central degenerative changes affecting the anterior horn cells throughout the spinal cord, but more often in the lumbar and cervical regions.Essentially similar lesions were observed in experimental animals in which partial paralysis was produced by means of triorthocresyl phosphate.”
Metabolism of triaryl phosphates in Rodents
DK Meyers, JBJ Rebel, C Derger, A Kemp, EGL Simmons
Nature, 176:259-260 (1955)
“Considerable interest is attached to the metabolism of the compound tri-o-cresyl phosphate, which has been shown to inhibit various esterases in vivo and which is capable of producing demyelination and paralysis in certain species of animals1. Pure tri-o-cresyl phosphate exhibits little inhibitory activity against esterases in vitro and the compound appears to be converted into an active inhibitor in the animal: this conversion can also be effected by incubation with liver slices in vitro.
This conversion requires the genetically and environmentally variable cytochrome P450 enzymes
This may explain some of the individual variability in sensitivity
Saligenin cresyl phosphate
Casida J et al. Nature191:1396 (1961)
Neuropathic target esterase (NTE)-Related References
Other important esterases are targets of PSP and CSP
Bottom Line: Many proteins and cellular functions are affected by OP exposures.
One way is to have data from continuous monitoring of the individual’s environment.While this would be very useful, it is seldom, if ever, done.
One Example of Analyzing a Protein Biomarker as Proof of Concept
Proof of concept:
Use multidimentional protein identification technology (MudPIT) to identify TCP modifications to carboxylesterase (CaE)
Digest with specific proteases
To mass spectrometer
~120 d ½ life
½ life unknown
~11 d ½ life
PSP is a very potent inhibitor of esterases
Expose Cells 48-h
10 ng/ml TCP
10 ng/ml TIPP
100 ng/ml TIPP
100 ng/ml TCP
Extract , label and process RNAs
Bind to microarray slides (Affymetrix Whole Genome Arrays )
2 color array
Increased expression = red dot
Decreased expression = green dot
1 color array
Example of data output from an OP exposure
p < 0.01; >2-fold (mouse brain cortex – CPO exposure)
Red signals = increased expression
Green signals = decreased expression
Highly Expressed Genes
Baseline is Average of Controls
Gene changes at both doses (10 ng/ml & 100 ng/ml) = 379
Gene changes at 10 ng/ml for TCP and TIPP = 177 (p value< .01)
11 annotated Genes
Research supported by: RAAF GCAQE Unions & othersSpecial thanks to: David Learmount Operations & Safety Editor Flight International
Primary Laboratory-Principal Investigator
Clement E. Furlong
Mass Spec Analyses Mike MacCoss
Cell cultures / Exposures / RNA preparation
Toby B. Cole
Chip Analysis Laboratories-UW
(RNA labeling / hybridization / scanning)
Deborah Nickerson laboratory
Joshua Smith (Illumina Chips)
Fred Farin (core facility)
Theo Bammler (Affymetrix chips) Richard Beyer(Statistics & Analysis)
Additional Data analysis (no charge to project)
Mette Peters (Rosetta Inpharmatics)