cobra venom (naja species) matthew mcbride. taxonomy and identity the common name “cobra” is...

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  • Slide 1
  • COBRA VENOM (Naja species) MATTHEW MCBRIDE
  • Slide 2
  • TAXONOMY AND IDENTITY The common name cobra is applied to about 30 species of snake in 7 genera (Aspidelaps, Boulengerina, Hemachatus, Ophiophagus, Pseudohaje, Walterinnesia and Naja) The taxonomy of some species is unclear The term cobra is abbreviated from the Portuguese cobra de capello, which means snake with hood Hence, cobra refers to any species within the family Elapidae that can produce a hood when threatened. Cobras generally possess long and slender bodies with smooth scales Cobras vary in size from 2 meters in the Naja species to the King Cobra that can reach an average of 4 meters but can reach 5.5 meters (worlds largest venomous snake) Hollow fangs at the front of the maxilla (spitting cobras fangs modified)
  • Slide 3
  • FOCUS WILL BE ON THE NAJA SPECIES The genus Naja represents the typical cobra, which are perhaps what are commonly thought of as the archetypal cobras Naja comprises approximately 25 species (roughly) and is the most widespread This species has undergone several taxonomic revisions in recent years so sources vary in terms of actual number of species The Naja species range throughout Africa, Southern Asia All species in the genus Naja are capable of delivering a fatal bite in humans The Naja species typically have strong neurotoxic venom but may also have cytotoxic and cardiotoxic components as well Several Naja species are referred to as spitting cobras because of their ability to propel venom out their fangs and towards the eyes of predators
  • Slide 4
  • WHY FOCUS ON THE NAJA SPECIES? Wide geographic distribution in Africa and Southern Asia Large range in LD50s (quantity of venom delivered ranges from 150mg to 350mg) Species contains some of the most venomous snakes worldwide Contain a unique spitting species Are one of if not the most recognized species of snake in the world (because of their characteristic hood) All species are able to raise up and appear large to predators Some surveys indicate fatalities around 25% of all bites (species identification leads to inaccuracies) Pictures (top to bottom): Naja kaouthia, Naja nigricollis and Naja naja
  • Slide 5
  • WHAT IS VENOM Venom is a poison produced by glands a various snakes and injected through fangs into a victims flesh The composition of venom varies with different species In general snake venoms are largely a complex mixture of biologically active proteins and peptides Venoms contain a spectrum of biological activities: neurotoxic, myotoxic, cardiotoxic, coagulant, hemostatic, edema inducing, hemorrhagic and possible direct action on vital organs Highly efficient in immobilizing, killing and digesting its prey
  • Slide 6
  • FANGS AND VENOM GLAND (ELAPIDS) Cobras are Proteroglyphous: meaning front fanged The fangs are in the front part of the maxilla that is immobile The maxilla is typically short and have few teeth The fangs themselves are are up front and pointing downward with a hallow needle like structure The fangs acquire their venom from a venom gland behind the eyes in the temporal region The lumen of the gland is relatively small and the secretions are stored in cytoplasmic granules before reaching the lumen The expulsion of venom is by the contraction of specialized mandibular and temporal muscles
  • Slide 7
  • MAIN COMPONENTS/FUNCTIONS IN NAJA VENOM Neurotoxins (damage of nervous system and /or brain) Cardiotoxins (damage to the heart) Cytotoxic effects (cell destroying) Hemotoxins (destroy RBCs/disrupt blood clotting) Cobratoxin (binds to acetylcholine receptors on muscle cells) Phospholipases (hydrolyzes phospholipids) Phosphoesterases (cutting oxygen loose from ribose or desoxyribose) Acetylcholinesterase (hydrolyzes acetylcholine) L-amino-acid-oxidase (changes amino acids) Hyaluronidase (enhances diffusion of venom by breaking down connective tissue)
  • Slide 8
  • NEUROTOXIN MECHANISM (COMMON MECHANISM AMONG NAJA SPECIES) Alpha-cobratoxin is a nicotinic acetylcholine receptor antagonist (short chain alpha-neurotoxin) The cobratoxin binds to ligand-binding subunits in the postsynaptic membrane receptor (red v on diagram) Thus, preventing the binding of acetylcholine and prohibiting it from turning its chemical signal into an electric one The site of this mechanism is taking place at the synaptic cleft of the neuromuscular junction Final result of this can lead to death by respiratory paralysis
  • Slide 9
  • NEUROTOXIN MECHANISM CONTINUED (MORE SPECIFICALLY) Alpha-neurotoxins are largely found in the Elapidae family (cobra examples Naja atra and Naja siamensis) There are short and long alpha-neurotoxins The alpha-neurotoxin mechanism specifically is a muscular-type nicotinic acetylcholine receptor (nAChR), its a ligand-gated ion channel on the postsynaptic fold of the neuromuscular junction with specialized subunits Upon binding to the nAChR, the neurotoxin prevents binding the normal ligand acetylcholine and ion flow This leads to paralysis and ultimately death
  • Slide 10
  • PHOSPHOLIPASE (A2) The majority of snake venom contains phospholipase Hydrolyze free phospholipids and those bound to membranes (into fatty acids and lysophospholipids) Phospholipase A2 is the most common Phospholipase A2 affects several physiological systems depending on the type of hydrolyzed phospholipids, haemostasis, neuromuscular transmission, and inflammatory reaction
  • Slide 11
  • PHOSPHOESTERASES (PHOSPHODIESTERASE) The endonucleases hydrolyze the nucleic acids (DNA/RNA) at the bonds between the base pairs The exonucleases attack the base at the end of the nucleic chain The phosphodiesterases cut the link removing the oxygen from position 3 of the ribose or the deoxyribose, separating them from the phosphorus The 5 nucleotidase produces a similar cut but at the level of the bond 5 between the ribose or the desoxyribose and the phosphor Functions to interfere with preys cardiac system by mainly lowering the preys blood pressure
  • Slide 12
  • L-AMINO-ACID-OXIDASE The enzyme causes the des-amination and then the oxidation of the amino acids, which are transformed into alpha-cetonic acid The clinical and toxicological effects are negligible, it represents less than 1% of the total toxicity of the venom (which explains its low concentration in the venom) The interesting fact about this enzyme is that flavin-adenin-dinucleotide group that is attached to the enzyme is what gives the venom its yellow color This component also has a anticoagulant, apoptotic-inducing, platelet aggregation- inducing and inhibiting properties Interestingly, this component is of biomedical interest because of its antimicrobial and anti-HIV activities
  • Slide 13
  • HYALURONIDASE This component of venom is valuable because it is responsible for disrupting the cohesion of connective tissue that allows venom to spread after a bite has occurred This enzyme hydrolyzes hyaluronic acid or the sulfate chondroitin Diffusion of toxins from bite site into blood is for successful envenomation and hyaluronidase allows this to occur Degradation of hyaluronic acid in the extracellular matrix is key to diffusion Increases potency of other toxins and destruction of local tissue Contributes to inflammation, tissue damage and spreading
  • Slide 14
  • UNIQUE NAJA SPECIES (SPITTING COBRAS) Some examples of spitting cobras: Naja pallida, Naja mossambica, Naja nigrcollis and Naja siamensis These species are able to eject venom out of their fangs as a defense response The muscles of the venom sac contract and force the venom out A combination of venom sac muscles and air exhaled from lungs provides the force These snakes are able to spray up to 10ft. Irrigation with water to venom from eyes prevents any permanent damage Venom in the eyes of victims without irrigation will result in chemosis and eventually blindness Picture: Naja nigrcollis
  • Slide 15
  • COMPARISON OF VENOM STRENGTH (INTRAVENOUS LD-50S) 4 highly ranked dangerous snakes LD-50 (mg/kg)---0.01---Eastern brown snake LD-50 (mg/kg)---0.071---Boomslang snake LD-50 (mg/kg)---0.25---Black mamba LD-50 (mg/kg)---1.5---Eastern green mamba
  • Slide 16
  • COMPARISON OF VENOM STRENGTH (INTRAVENOUS LD50S) 5 species of Naja cobra LD-50 (mg/kg)---0.28---Black forest cobra (Naja melanoleuca) LD-50 (mg/kg)---0.34---Chinese cobra (Naja atra) LD-50 (mg/kg)---0.35---Spectacled cobra (Naja naja) LD-50 (mg/kg)---0.37---Monocled cobra (Naja kaouthia) LD-50 (mg/kg)---0.42)---Egyptian cobra (Naja haje)
  • Slide 17
  • WHAT TO DO WHEN A BITE OCCURS (BEST CASE SCENARIO) 1) Note the snakes appearance -Be ready to describe the snake to emergency staff 2) Protect the person (While waiting for medical help) -Move the person beyond striking distance -Have the person lie down with wound below the heart -Keep the person still to keep the venom from spreading -Cover the wound with loose, sterile bandage Dont: -cut a bite wound -attempt to suck out venom -apply tourniquet, ice, water -give alcohol or caffeine
  • Slide 18
  • TREATMENT: ANTI-VENOM Venom composition and its corresponding toxicity can vary among among cobras from the same species and even from the same litter. (even over its lifetime) This makes cobra venom truly unique and correct treatment is needed to ensure a successful recovery Ant-venom is created using venom from specific species of snake depending on the bite encountered and is then diluted to be injected into horses, sheep or goats After the injecti

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