Download Neurotoxins

• Clostridium bacteria are grampositive rod-shaped bacteria
that form spores that allow the
bacteria to survive in a dormant
state until exposed to conditions
that can support growth.
• There are seven types of
botulism neurotoxin designated
by the letters A through G. Only
types A, B, E, and F cause illness
in humans.
• The Clostridium bacteria are
considered to be anaerobic,
which means these organisms
grow best in low or absent
oxygen levels.
• Botulism is a rare but serious
paralytic illness caused by a
nerve toxin that is produced
by the bacterium Clostridium
botulinum.
• It is a serious illness that
causes flaccid paralysis of
muscles.
• The classic symptoms of botulism
include:
• Double vision
• Blurred vision
• Drooping eyelids
• Slurred speech
• Difficulty swallowing
• Dry mouth
• Muscle weakness
• Constipation may occur.
• The doctor's examination may
reveal that the gag reflex and the
deep tendon reflexes like the
knee-jerk reflex are decreased or
absent.
• Infants with botulism appear
lethargic, weak, and floppy,
feed poorly, become
constipated, and have a
weak cry and poor muscle
tone. In infants, constipation is
often the first symptom to
occur.
• These are all symptoms of
the muscle paralysis that is
caused by the bacterial
neurotoxin
There are three main
kinds of botulism:
• 1. Foodborne botulism
• 2. Wound botulism
• 3. Infant botulism
• The neurotoxin actually
paralyzes the nerves so
that the muscles cannot
contract.
• This happens when the
neurotoxin enters the
nerve cells and
eventually interferes with
the release of
acetylcholine.
• Unless the nerve can
regenerate a new axon
that has no exposure to
the neurotoxin, the
interference at the
neuromuscular junction is
permanent.
• Sarin gas is a human-made
chemical warfare agent
classified as a nerve agent.
• Sarin gas , or GB, is an
organophosphorus compound.
• Organophosphorus compounds
are degradable organic
compounds containing carbon–
phosphorus bonds, used
primarily in pest control as an
alternative to chlorinated
hydrocarbons that persist in the
environment.
• It has been classified as a
weapon of mass destruction in
the UN Resolution 687.
• It is a colorless, odorless liquid
and it is used as a chemical
weapon owing to its extreme
potency as a nerve agent.
• Like other nerve agents,
sarin gas attacks
the nervous system by
stopping nerve endings at
the muscles from switching
off.
• Death will usually occur as
a result of asphyxia due to
the inability to control the
muscles involved in
breathing function.
• Specifically, sarin gas is
a potent inhibitor of
acetylcholinesterase.
• Acetylcholine is the
neurotransmitter used at
the neuromuscular
junction.
• Normally, acetylcholine
is released from the
neuron to stimulate the
muscle, after which it is
degraded by
acetylcholinesterase,
allowing the muscle to
relax.
• Owing to the ubiquity of
the trade name Novocain,
in some regions procaine is
referred to generically as
novocaine.
• Procaine is a local
anesthetic drug of the
amino ester group.
• It is used primarily to
reduce the pain of
intramuscular injection of
penicillin, and it is also
used in dentistry.
• It acts mainly by being a
sodium channel blocker.
• Local anesthetics like
novocaine (procaine) are
agents that prevent
transmission of nerve
impulses without causing
unconsciousness.
• They act by binding to
fast sodium channels
from within (in an open
state).
• In dentistry it works by
producing a trigeminal
nerve conduction block, in
the mandibular (3rd)
branch, decreasing the
permeability of the axon
cell membrane to (Na+)
sodium ions.
• This mechanism prevents
the entry of Na+ ions into
the axon to propagate an
action potential in both
slow and fast pain fibers.
• Unmyelinated axons are
the first to be affected.
• Myelinated motor nerves
are only affected at the
nodes of Ranvier.
• Lidocaine is a common
local anesthetic and
antiarrhythmic drug.
• Lidocaine is usually used to
relieve itching, burning and
pain from skin
inflammations.
• It is also injected as a
dental anesthetic or as a
local anesthetic for minor
surgery.
• Lidocaine is a type of
medicine called a local
anesthetic.
• It is used to numb areas
that would otherwise feel
pain.
• The stimulation causes
sodium to enter the nerve.
• Lidocaine works by
temporarily blocking this
pathway of pain signals
along nerves.
• It does this by stopping
the sodium entering the
nerve ending at the site of
the pain. This prevents an
electrical signal building
up and passing along the
nerve fibers to the brain.