L8: Venoms & Toxins (Martyniuk) Flashcards
Venom vs. poison
- venom is ACTIVELY injected toxin; used for hunting/defense
- poison is PASSIVELY secreted; defense mech.
3 classes of venom compounds
1) LMW substances
2) Peptides
3) Enzymes
LMW substances ex.
prostaglandins
HA
EP
-cause pain, inflammation, hypotension
Ex. of peptide venomes
- mellitin (acts as detergent; allows things to go in and out of cells)
- bungarotoxin (has CNS effects)
- in general cause many direct toxic effects and allergy
Ex. of enzyme venoms
Hyaluronidase (disrupts cell membranes, collagen)
Collagenase (breaks down capillary walls)
Protease (breaks down proteins –> necrosis)
Hymenoptera contain what insects
bees
wasps
hornets
fire ants
fire ants can spray what compound?
formic acid
3 main components of bee venom
1) Mellitin (acts as detergent -> hemolytic, hypotensive, pain, HA release, cortisol release)
2) Phospholipase A2 (destroys membranes)
3) Hyaluronidase (disrupts cell membranes, collagen)
primary pain-inducing substance of wasp venom
kinins
ant/bee/wasp venom primarily composed of
alkaloids (i.e. Piperidine**)
ant/bee/wasp venom MOA
Piperidine causes dermal necrosis
animals most likely to be severely affected by ant/bee/wasp venom
those with limited mobility
Symptoms of bee/wasp/hornet venom
- Local: swollen/edematous, erythematous plaque
- Anaphylaxis (most common cause of death)
- Systemic toxicity: uncommon, delayed hypersensitivity causing shock, hemolysis, rhabdomyolysis, hepatic/renal injury
T/F: anaphylaxis occurs in cows. Dogs?
Cows-no
dogs-yes
Tx of bee/wasp/hornet venom
- remove stinger
- cold compress
- antihistamines, corticosteroids
- monitor for anaphylaxis (tx with EP, fluids)
Does anaphylaxis occur with fire ant stings?
Not reported
Holocyclotoxin
- produced in salivary glands of Dermacentor/Ixodes ticks
- decreases Ach release at NMJ –> weakness/paralysis
- Dermacentor toxin may also act on Na channels*
Symptoms of holocyclotoxin
(6-14d later)
- loss of appetite/voice
- incoordination, paralysis
- salivation, vomiting
- resp. distress
- death
Dx of holocyclotoxin
- no definitive dx
- hx, presence of ticks
- ascending paralysis and loss of voice
Tx of holocyclotoxin
- atropine
- antiemetics
- fluds, oxygen, supportive tx
- good prognosis if treated
toad poisoning chars.
- Bufo species (B. marinus (Cane/Giant Toad) in Florida**)
- eggs/tadpoles toxic too
- dogs most commonly involved
Toad poisoning MOA
- secretions contain BIOGENIC AMINES (histamine,etc.) which cause vasoconstriction, hypotension, hallucination, GI effects and BUFOGENINS (Bufotalin) which inhibit Na/K ATPase –> cardiac arrhythmias
- 2 major systems affects: cardiac and CNS
Bufogenins have similar toxic effects as what plant?
foxglove
Dx of toad poisoning
based on CS (hypersalivation, head shaking, CNS signs, arrhythmia), hyperkalemia
differentials for toad poisoning-like symptoms
pesticides
Rhododendron spp.
Oleander
Foxglove
Tx of toad poisoning
- immediate oral decon with water lavage
- act. charc. if no seizures
- diazepam/barbiturates if seizures
- atropine for bradycardia
- propranolol or esmolol (beta blockers) for arrhythmia
- fluids
- digoxin for severe hyperkalemi/CNS signs
Black Widow males toxic?
NO (only females)
Black widow venom MOA
contains alpha-latrotoxin, which creates pores in membranes allowing Ca++ entry and releasing massive amts. of NT –> sustained muscle spasm
symptoms of black widow venom
muscle spasm rapid weight loss restless hypertension tachycardia v/d resp. collapse
tx of black widow venom
- control m. spasms/pain
- Ca gluconate for m. cramps
- anti-venom
- supportive care
