Small specific peptides of the cyanobacterium Microcystis aeruginosa cause thrombocytopenia and pulmonary thrombosis without activation of the coagulation cascade. The pulmonary thrombosis apparently leads to pulmonary occlusion, right heart failure, hepatomegaly and death in mammals. Long range goals are to determine: 1) mechanism of peptide activation, 2) processes responsible for thrombocytopenia, 3) relationship between thrombocytopenia and pulmonary thrombosis, 4) role of pulmonary endothelium and leukocytes in pulmonary thrombus formation, 5) relationship between pulmonary thrombosis, cardiac failure and hepatomegaly, and 6) the correlations between composition, structure, and activity of the peptides. The severe peptide-induced thrombocytopenia (less than 5% of baseline value) begins approximately 30 minutes after peptide injection, is apparently complete in a few minutes, and is sparing of leukocytes. Initial specific aims are to determine the kinetics of thrombocytopenia, pulmonary thrombosis and hepatomegaly using sequential platelet counts and histopathological examination. Then the site and kinetics of activation and clearance of the peptide or its metabolic product(s) will be followed in vivo and in liver cell cultures. The time courses and the sites of platelet aggregation, sequestration, or destruction will be evaluated by histopathology, isotopic and fluorescence labeling of platelets, platelet aggregometry and electron microscopy. The role of the arachidonic acid cascade, in particular the lipoxygenase sequence, will be studied by pharmacological manipulation and biochemical analysis using radioimmunoassay and HPLC. The contribution of pulmonary endothelium and leukocytes to thrombocytopenia and pulmonary thrombosis will be evaluated with endothelial cell cultures, platelet aggregometry and isotope-labeled platelets. The chemical and structural features of the peptides responsible for their specificity and action will be assessed with a series of naturally-occurring peptides of varied composition.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES003302-03
Application #
3250502
Study Section
Toxicology Study Section (TOX)
Project Start
1984-12-01
Project End
1988-11-30
Budget Start
1986-12-01
Budget End
1988-11-30
Support Year
3
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Associated University-Brookhaven National Lab
Department
Type
DUNS #
City
Upton
State
NY
Country
United States
Zip Code
11973
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Stoner, R D; Adams, W H; Slatkin, D N et al. (1989) The effects of single L-amino acid substitutions on the lethal potencies of the microcystins. Toxicon 27:825-8
Adams, W H; Stone, J P; Sylvester, B et al. (1988) Pathophysiology of cyanoginosin-LR: in vivo and in vitro studies. Toxicol Appl Pharmacol 96:248-57
Hughes, W L (1987) A simple fast micromethod for measuring enzyme activities which release tritium as tritium water. Anal Biochem 161:529-32
Adams, W H; Stoner, R D; Adams, D G et al. (1985) Pathophysiologic effects of a toxic peptide from Microcystis aeruginosa. Toxicon 23:441-7