Author
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NELSON, T - UNIV OF MARYLAND |
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Paape, Max |
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WORKU, M - UNIV OF MARYLAND |
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DOUGLASS, L - UNIV OF MARYLAND |
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Submitted to: International Congress on Free Radicals in Health and Disease
Publication Type: Abstract Only Publication Acceptance Date: 10/22/1997 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Inflammation of the mammary gland, mastitis, results in production of superoxide anion and nitric oxide by activated neutrophils. Interactions between the radicals results in formation of peroxynitrite. Peroxynitrite is a powerful radical that peroxidizes lipids, oxidizes DNA and sulfhydryl groups, nitrates tyrosine residues and permeabilizes membranes. In this study we examined production of peroxynitrite during acute bovine mastitis as measured by the presence of nitrated tyrosine residues in neutrophils and milk whey proteins. Clinical mastitis was induced by the infusion of 50 æg of Escherichia coli endotoxin into the mammary glands of three cows. Blood and milk were collected before and 12 h after infusion for the isolation of neutrophils and preparation of whey. Cows were then injected in the tail vein with 10 IU oxytocin. Milk neutrophils were isolated and whey was prepared from the residual milk collected after oxytocin injection. Neutrophils and milk samples were analyzed for nitrotyrosine residues by ELISA and/or immunoblotting. For all cows, both blood and milk neutrophils had moderate levels of nitrotyrosine before endotoxin infusion. Blood neutrophils had reduced levels of nitrotyrosine 12 h after infusion, while nitrotyrosine levels in milk neutrophils either increased or remained at the pre-infusion level. Nitrotyrosine levels were also reduced in neutrophils obtained from residual milk. Both nitrotyrosines and phosphotyrosines were detected in whey proteins before LPS infusion. Tyrosine nitration and phosphorylation increased dramatically 12 h after infusion and remained elevated in the residual milk. The increase in whey protein |
