Paul West

Publications

• 3.36

  Impact points

  Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics.

  N C Kleinstreuer, A M Smith, P R West, K R Conard, B R Fontaine, A M Weir-Hauptman, J A Palmer, T B Knudsen, D J Dix, E L R Donley, G G Cezar

  Toxicology and applied pharmacology. 09/2011; 257(1):111-21.

  Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast™ chemical screening and prioritization research project. Metabolites from hES cultures were evaluated... [more] Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast™ chemical screening and prioritization research project. Metabolites from hES cultures were evaluated for known and novel signatures that may be indicative of developmental toxicity. Significant fold changes in endogenous metabolites were detected for 83 putatively annotated mass features in response to the subset of ToxCast chemicals. The annotations were mapped to specific human metabolic pathways. This revealed strong effects on pathways for nicotinate and nicotinamide metabolism, pantothenate and CoA biosynthesis, glutathione metabolism, and arginine and proline metabolism pathways. Predictivity for adverse outcomes in mammalian prenatal developmental toxicity studies used ToxRefDB and other sources of information, including Stemina Biomarker Discovery's predictive DevTox® model trained on 23 pharmaceutical agents of known developmental toxicity and differing potency. The model initially predicted developmental toxicity from the blinded ToxCast compounds in concordance with animal data with 73% accuracy. Retraining the model with data from the unblinded test compounds at one concentration level increased the predictive accuracy for the remaining concentrations to 83%. These preliminary results on a 11-chemical subset of the ToxCast chemical library indicate that metabolomics analysis of the hES secretome provides information valuable for predictive modeling and mechanistic understanding of mammalian developmental toxicity.
• 3.36

  Impact points

  Predicting human developmental toxicity of pharmaceuticals using human embryonic stem cells and metabolomics.

  Paul R West, April M Weir, Alan M Smith, Elizabeth L R Donley, Gabriela G Cezar

  Toxicology and applied pharmacology. 08/2010; 247(1):18-27.

  Teratogens, substances that may cause fetal abnormalities during development, are responsible for a significant number of birth defects. Animal models used to predict teratogenicity often do not faithfully correlate to human response. Here, we seek to develop a more predictive developmental toxicity... [more] Teratogens, substances that may cause fetal abnormalities during development, are responsible for a significant number of birth defects. Animal models used to predict teratogenicity often do not faithfully correlate to human response. Here, we seek to develop a more predictive developmental toxicity model based on an in vitro method that utilizes both human embryonic stem (hES) cells and metabolomics to discover biomarkers of developmental toxicity. We developed a method where hES cells were dosed with several drugs of known teratogenicity then LC-MS analysis was performed to measure changes in abundance levels of small molecules in response to drug dosing. Statistical analysis was employed to select for specific mass features that can provide a prediction of the developmental toxicity of a substance. These molecules can serve as biomarkers of developmental toxicity, leading to better prediction of teratogenicity. In particular, our work shows a correlation between teratogenicity and changes of greater than 10% in the ratio of arginine to asymmetric dimethylarginine levels. In addition, this study resulted in the establishment of a predictive model based on the most informative mass features. This model was subsequently tested for its predictive accuracy in two blinded studies using eight drugs of known teratogenicity, where it correctly predicted the teratogenicity for seven of the eight drugs. Thus, our initial data shows that this platform is a robust alternative to animal and other in vitro models for the prediction of the developmental toxicity of chemicals that may also provide invaluable information about the underlying biochemical pathways.
• 2.91

  Impact points

  Identification of a yellow impurity in aged samples of aqueous butamben suspension: evidence for the oxidative degradation of poly(ethylene glycol).

  E J Ginsburg, D A Stephens, P R West, A M Buko, D H Robinson, L C Li, A R Bommireddi

  Journal of pharmaceutical sciences. 07/2000; 89(6):766-70.

  Butamben (butyl p-aminobenzoate) has been formulated to provide long-acting treatment for chronic pain. The suspension, which contains poly(ethylene glycol) and polysorbate 80, was found to yellow under ambient conditions if not adequately protected from oxygen. The impurity responsible for the colo... [more] Butamben (butyl p-aminobenzoate) has been formulated to provide long-acting treatment for chronic pain. The suspension, which contains poly(ethylene glycol) and polysorbate 80, was found to yellow under ambient conditions if not adequately protected from oxygen. The impurity responsible for the color was isolated and identified on the basis of nuclear magnetic resonance spectroscopy and mass spectrometry. The compound is an oxalamidine, which is formally the condensation product of oxalic acid with four equivalents of butamben, and may be formed by the reaction of butamben with an oxidation product of poly(ethylene glycol).
• 1.63

  Impact points

  The identification of 1,6'- and 1,3"-di-N-(L-4-amino-2-hydroxybutyryl) derivatives of kanamycin as synthetic byproducts of amikacin.

  G Gunawardana, C Childress, M Tripp, X Zhang, P West

  The Journal of antibiotics. 11/1997; 50(10):887-9.
• 1.63

  Impact points

  Corynecandin: a novel antifungal glycolipid from Coryneum modonium.

  G Gunawardana, R R Rasmussen, M Scherr, D Frost, K D Brandt, W Choi, M Jackson, J P Karwowski, G Sunga, L H Malmberg, P West, R H Chen, S Kadam, J J Clement, J B McAlpine

  The Journal of antibiotics. 11/1997; 50(10):884-6.
• 1.63

  Impact points

  Discovery of saricandin, a novel papulacandin, from a Fusarium species.

  R H Chen, S Tennant, D Frost, M J O'Beirne, J P Karwowski, P E Humphrey, L H Malmberg, W Choi, K D Brandt, P West, S K Kadam, J J Clement, J B McAlpine

  The Journal of antibiotics. 07/1996; 49(6):596-8.
• 6.24

  Impact points

  Solubilization and partial characterization of extensin fragments from cell walls of cotton suspension cultures. Evidence for a covalent cross-link between extensin and pectin.

  X Qi, B X Behrens, P R West, A J Mort

  Plant physiology. 09/1995; 108(4):1691-701.

  Extensin, a major hydroxyproline (Hyp)-rich glycoprotein in walls of cultured cells of dicotyledonous plants, is very difficult to solubilize. To learn about the nature of the insolubilization, we have tested the ability of a variety of selective hydrolytic methods, and combinations of them, to libe... [more] Extensin, a major hydroxyproline (Hyp)-rich glycoprotein in walls of cultured cells of dicotyledonous plants, is very difficult to solubilize. To learn about the nature of the insolubilization, we have tested the ability of a variety of selective hydrolytic methods, and combinations of them, to liberate extensin or fragments of extensin from suspension-culture cell walls. After the complete deglycosylation of cotton (Gossypium hirsutum L.) walls, trypsinization solubilized 80% of the Hyp. The sequences of three abundant peptides were: (a) serine-Hyp-Hyp-Hyp-Hyp-Hyp-Hyp-serine-Hyp-Hyp-lysine, (b) serine-Hyp-Hyp-Hyp-Hyp-valine-lysine, and (c) serine-Hyp-Hyp-serine-alanine-Hyp-lysine. After a sequential treatment of walls with endopolygalacturonase, cellulase, -73 degrees C anhydrous hydrogen fluoride solvolysis, and ammonium bicarbonate extraction, only sugars indicative of rhamnogalacturonan I and protein remained insoluble. Trypsin treatment of this residue liberated 50% of the Hyp. A significant proportion of rhamnogalacturonan-associated sugars co-solubilized and co-purified along with the extensin fragments following the trypsinization. By sodium dodecyl sulfate gel electrophoresis and gel filtration, the glycopeptides fell into two classes. One class contained distinctly sized molecules with relative molecular weights in the range of 4,000 to 24,000. The other class did not enter the resolving gel and was hetero-disperse. After complete deglycosylation by a 0 degrees C anhydrous hydrogen fluoride treatment, the first class was little affected in its electrophoretic mobility, whereas the larger heterogeneous material mostly entered the separating gel. After further trypsinization of the deglycosylated peptides and analysis by capillary zone electrophoresis, the peptides in both size classes were shown to contain the sequences described above. From our observations we suggest that cotton extensin becomes insolubilized into cell walls in part by pectin-protein cross-links in addition to the protein-protein (or protein-phenolic-protein) cross-links that have been repeatedly suggested.
• 2.13

  Impact points

  Arthropod venom citrate inhibits phospholipase A2.

  A W Fenton, P R West, G V Odell, S M Hudiburg, C L Ownby, J N Mills, B T Scroggins, S B Shannon

  Toxicon : official journal of the International Society on Toxinology. 07/1995; 33(6):763-70.

  Citrate has been identified as a major component of honey bee (Apis mellifera) venom by gas liquid chromatography-mass spectrometry. A citrate concentration of 9% was found for dried bee venom by a coupled enzyme assay, aconitase-isocitric dehydrogenase. A liquid honey bee venom would contain 140 mM... [more] Citrate has been identified as a major component of honey bee (Apis mellifera) venom by gas liquid chromatography-mass spectrometry. A citrate concentration of 9% was found for dried bee venom by a coupled enzyme assay, aconitase-isocitric dehydrogenase. A liquid honey bee venom would contain 140 mM citrate concentration (if the solids content were 30%). Bee venom phospholipase was inhibited at a 43% level with a citrate concentration of 20 mM and calcium ion at 3 mM with the enzyme assay. Citrate was also found in the venoms of bumble bee, Bombus fervidus, 7%; yellow jacket, Vespula maculifrons, 4%; scorpion, Centruroides sculpturatus, 8%; tarantula, Grammastola cala, 8% and brown recluse spider venom gland extract, Loxoceles reclusa, 1.5% based on dried venom solids. Citrate may serve as an endogenous inhibitor of divalent metal ion-dependent enzymes in arthropod venoms as described by Francis et al. (1992, Toxicon 30, 1239-1246). Many arthropod venoms contain calcium-dependent phospholipases. A direct effect of citrate as a venom component may be possible. The presence of citrate in venoms must be considered in research on receptors, ion channels and divalent ion-dependent toxins.

• "SpectraGraph" and "SpectraSort": mass spectral display and interpretation software for the Macintosh.

  P R West, A J Mort

  Journal of chemical information and computer sciences. 33(2):234-9.

  Two computer programs entitled "SpectraGraph" and "SpectraSort" have been written for te Apple Macintosh. SpectraGraph allows graphical display, manipulation, storage, and printing of an input mass spectrum list that has been imported from a mass spectrometer or entered manually.... [more] Two computer programs entitled "SpectraGraph" and "SpectraSort" have been written for te Apple Macintosh. SpectraGraph allows graphical display, manipulation, storage, and printing of an input mass spectrum list that has been imported from a mass spectrometer or entered manually. SpectraGraph gives the user the ability to display, normalize, and multiply different mass ranges, annotate peaks, and perform various other operations on the spectral display. Also the mass spectrum and other graphics may be copied to and from other Macintosh application documents. SpectraSort has been developed to aid in the interpretation of mass spectra, particularly those of biopolymers, by calculating the mass differences between peaks in a mass spectrum. The user then has the option of matching the mass differences with masses of fragments or residues stored in several user-definable look-up tables.