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17 Cards in this Set

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Anabaena circinalis

Anatoxin-a


Blocks neuromuscular nicotinic depolarisation


Muscles


Respiratory failure

Microcystis aeruginosa

Microcystin


Descreased phosphorylation of tubulin/other proteins in the liver --> disruption of cytoskeleton


Liver failure

Nodularia spumigena

Intracellular hepatoxin


Cellular swelling/degeneration/necrosis


Excessive peritoneal and plural fluid, haemorrhage on serosal surfaces, leucopoenia


Liver failure

Aphanizomenon flos-aquae

Saxitoxin


Blocks Na channels at NMJ (no effect on K)

Aspergillus flavus

Aflatoxin


Most important


Strong carcinogen


Binds DNA, RNA, protein --> Inhibits transcription --> no protein synthesis


Liver failure

Claviceps purpurea

Ergot Alkaloid


Initiate smooth muscle contraction (uterus, small arteries) --> gangrene / heat intolerance (less heat lost in periphery)


Mimic dopamine in CNS


Hallucinations

Diaporthe toxica

Phomopsin


Bind to tubulin --> inhibit assembly --> intracellular transport and mitosis hindered


Myopathy: decreased Se mobilization from damaged liver


Encephalopathy: hyperammonaemia


Liver --> muscle / brain

Pithomyces chartarum

Sporidesmin


Absorbed in SI --> excreted by liver into bile --> bile canalicular membranes become inflammed Cholangitis, jaundice, retention of phylloerythrin --> photosensitisation


Grows on dead leaf litter in autumn (rain+heat) -->spores carried upward by (perennial rye) grass growth


Mainly problem in sheep

Acremonium lolii

Lolitrems (Tremorgans/Indole akaloids)


GABA and glycine antagonist


Vasocontriction in cerebrum


Inhibition of monoamine oxidase (serotonin activity increases)


Tremors / gait abnormalities

Claviceps paspali

Paspalitrems


GABA and glycine antagonist


Vasocontriction in cerebrum


Inhibition of monoamine oxidase (serotonin activity increases)


Tremors / gait abnormalities

Penicillium spp.

Penitrems


GABA and glycine antagonist


Vasocontriction in cerebrum


Inhibition of monoamine oxidase (serotonin activity increases)


Tremors / gait abnormalities

ANNUAL RYEGRASS TOXICITY


(Anguina agrostis / Clavibacter toxicus / Lolium rigidum)

Corynetoxin


Bacteria on nematodes infect seeds


Inhibits transfer of pre-formed oligosaccharide to proteins --> reduced glycosylation of glycoproteins


Reduces integrity BBB --> large molecules pass into brain --> CNS dysfunction


Ataxia, tetany, convlusions, death


Worse with stress/exercise

Organochlorine

Fat soluble / stored


Slow metabolism / excretion


Mechanism not well understood


Nervous signs = tremors, seizures, hyperthermia, blindness, death

Organophosphate

Phosphates or thiophosphates


Synthetic


Irreversibly phosphorylate esteratic site


Acetylcholinesterase inhibitor


Short half life


Absorbed from all surfaces / rapid


Ach accumulates --> excess stimulation


Progression from Parasympathetic/Sympathetic signs (vomiting, diarrhoea, salivation, lacrimation, difficulty breathing, urination, bradycardia) (muscarinic) --> NM signs (muscle tremors, twitching, paralysis) (nicotinic) --> CNS signs (depression, hyperactivity, seizures, etc)


Atropine (blocks muscarinic receptors) and 2-PAM (reactivates AchE) to treat

Carbamate

First found in plant


Reversibly inhibit enzyme (recovers with time)


Acetylcholinesterase inhibitor


Short half life


Absorbed from all surfaces / rapid


Ach accumulates --> excess stimulation Progression from Parasympathetic/Sympathetic signs (vomiting, diarrhoea, salivation, lacrimation, difficulty breathing, urination, bradycardia) (muscarinic)


Atropine might treat or exacerbate

Metaldehyde

Polymer of acetaldehyde


Hydrolized to acetaldehyde and polymer components by stomach acid


Absorbed and hydrolyzed/oxidized in liver


Exceeds liver detox capacity --> accumulation --> fragments cross BBB


Decreases serotonin and GABA (anxiety, tachycardia, ataxia, convulsions, hyperthermia)

Methiocarb

Reversible inhibitor cholinesterase -->


Muscarinic/nicotinic overstimulation --> vomiting, diarrhoea, salivation, lacrimation, miosis, dyspnoea, micturation, bradycardia


Atropine to control neural overstimulation