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Objective I: Develop diagnostic techniques and biomarkers to better identify animals
poisoned by pyrrolizidine alkaloids (PA's) and their subsequent metabolites.<P>
Objective II: Determine pyrrole toxzicity and carcinogenicity and compare pyrrole
toxicity with that of PA and PA-N-oxides. Characterize the risk to fetuses and
neonates that are exposed by maternal PA ingestion. <BR>
2.1 Determine pyrrole toxicity and carcinogenicity.<BR>
2.2 Characterize transplacental and transmammary toxicity of various PA's.<P>
Objective III: Describe the gross,histological and ultrastructural lesions of Rayless
goldenrod (Isocoma plurifora or Haplopappus heterophyllus) and white snakeroot
(Eupatorium rugosum) intoxication and determine the effect on fetal and neonatal
development.<BR> <BR>
Objective IV: Describe the clinical, morphological, and molecular alterations of
certain hepatotoxic and neurotoxic plant-induced toxicosis in animals. Develop
better techniques to monitor chlorophyll and phylloerythrin metabolism and correlate
them with photosensitivity in livestock.
Approach: Pyrrolizidine alkaloid (PA) metabolites (pyrrole) adducts such as pyrrole-thiamidine,
pyrrole-guanine, pyrrole-methionine or pyrrole-glutathione will be linked to an
immunogenic proteins and used as the immunogens to generate pyrrole specific
antibodies. These same pyrrole-specific antibodies will be used to develop
immunohistochemistry, ultrastructural immunochemistry and ELISA diagnostic
techniques. Cellular kinetic will be documented and described. Additional
biomarkers of poisoning will be developed using proteomic and genomic techniques.
<P>
Tissue bound pyrroles or adducts that are likely to contaminate animal products,
will be tested in mouse models for toxicity and carcinogenicity. The molecular
events of hepatic carcinogenesis including altered expression or activation of
various oncogenes, tumor suppressor genes and cell proliferation mediators will be
evaluated. Similar sensitive mouse models will be used to test the fetal and
neonatal effects of individual PA-toxicity. PA’s likely to cross the placenta or to
be excreted in milk will be identified and the risk of such poisoning described. The
toxicity of specific PA’s will be compared with PA chemical structure to identify
those functional groups that are likely to lead to transplacental and transmammary
transfer and poisoning. As rodent placentation is unique, these results
(transmammary and transplacental PA transfer) will be verified in livestock.
<P>
Rayless goldenrod and white snakeroot poisoning will be characterized by exposing
horses to varying plant doses. The clinical, physiologic and pathologic response to
poisoning will be monitored daily using clinical evaluations, exercise tolerance via
treadmill evaluation of physical strength and endurance, electrocardiograms,
echocardiography, hematology and serum biochemistry. The progression and lesions of
poisoning will be described using biopsy, post mortem examination, histologic and
ultrastructural evaluations. A dose response study using pregnant mares will be used
to characterize fetal and neonatal poisoning and to identify which lesions are
reversible.
<P>
Photosensitization will be studied using clinical surveys. Clinical findings,
histologic changes and hepatic function data will be collected, characterized and
correlated with the serum and dermal phylloerythrin concentrations. Risk models of
feed-related photosensitivity will be developed to predict susceptible populations
and risk.