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17 Cards in this Set
- Front
- Back
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True or false. Most plants only contain one type of pyrrolizidine alkaloid.
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False, many plants contain 6-6 different alkaloids
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What are pyrrolizidine alkaloids?
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Cyclic alkaloids containing Nitrogen
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Some pyrrolizidine alkaloids need to be activated by what?
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MFOs in liver
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**How do pyrrolizidine alkaloids cause damage?
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Converted to pyrrols in liver--> pyrols are alkalating agents--->****cross link dDNA--> prevents mitosis, cell division
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What is the mechanism of action of pyrrolizidine alkaloids at high doses?
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Also inactivates enzymes causing necrosis
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True or false. Pyrrolizidine result in limited regeneration of the liver.
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True
**Limited regeneration |
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Explain the mechanism of action of how pyrrolizidine alkaloids cause liver damage?
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-Cross linked DNA prevents cell division
-As hepatocytes die they are not replaced -Scar tissue (fibrosis) replaces hepatocyte -Eventually enough hepatocytes are loss so liver can not function |
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True or false. Pyrrolizidine alkaloids result in acute toxicity.
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False, chronic delayed toxicity
-Higher doses may kill more acutely |
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When do signs begin to occur from a moderate dose of pyrrolizidine alkaloids?
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May not occur until a year after consumption stops
-As hepatocytes die and can't be replaced |
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How do you control tansy? (3)
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Destroy the plant, don't feed:
1) Biological -sheep, cinnabar moth -tansy flea beetle 2) Herbicides 3) Cultivation (biennial) |
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Where do you find fiddleneck?
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A weed of dry cultivated soil
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What animals have reduced toxicity to pyrrolizidine alkaloids compared to other animals?
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Sheep, goats, llamas
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Why do sheep, goats and llamas have reduced toxicity to pyrrolizidine alkaloids? (2)
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1) Rumen microbes
-bacteria in rumen inactivates PAs 2) Activation |
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What are 4 ways to diagnose pyrrolizidine alkaloid poisoning?
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1) Liver disease signs
2) Liver histopathology 3) Find plant in feed 4) Identify alkaloid in hay or pasture |
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What do you see on histopathology of pyrrolizidine alkaloid poisoning? (4)
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1) Periportal necrosis
2) Fibrosis 3) Bile duct proliferation 4) Megalocytosis****** |
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What is the prognosis of pyrrolizidine alkaloid poisoning?
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Not a good prognosis once signs develop
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What is the treatment for pyrrolizidine alkaloid poisoning? (2)
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1) Support liver by diet
2) Remove from feed -but may have eaten over a year ago |
