We continue from Ukraine: Nerve Agent Civil Defense Part 1.
Nota bene: This is not medical advice. It is an attempt to make accessible a few papers that are somewhat speculative, so that policymakers can ask intelligent questions of their CW defense establishments, (UK) Defence Science and Technology Laboratory and (U.S.) Edgewood Chemical Biological Center.
Basics. The nervous system contains cells called neurons. In various forms, neurons are the computing elements of the brain. Neurons in the peripheral nervous system connect all the functions of the body to the brain, for both conscious and involuntary control, by nerve impulses.
Within a single neuron fiber, which can be feet in length, a nerve impulse propagates in a way resembling an electric pulse aided by chemistry. It isn’t simple, but is simple compared to when it has to jump from one one neuron to another, across a watery gap called a synapse. The sending neuron spritzes a puff of molecules called neurotransmitters into the gap. In mere milliseconds they are sniffed by receptors on the receiving neuron, which causes a new nerve impulse to start up in the receptor. There are many neurotransmitters in the brain; the one of interest is acetylcholine.
The spritz of neurotransmitter has to go away before the next spritz, or the system locks up — spasms, convulsions, paralysis, death. The cleanup job is handled by a catalyst molecule that destroys neurotransmitters without damage to itself. In this case, AChE. Each molecule of AChE destroys about 25,000 acetylcholine molecules before it takes a hit, so the body replaces AChE very slowly..
A nerve agent binds to AChE, so that AChE can no longer remove acetylcholine from the synapse. The nervous system locks up; death ensues. This is the simple story, upon which orthodox treatment relies:
- Reduce the activity of the excess acetylcholine, with an anticholinergic medication, such as atropine, which fits into acetylcholine receptors, blocking them.
- Reactivate the AChE, by ripping off the nerve agent, with a class of medications known as oximes. A frequent choice is pralidoxime.
There is a challenge to this recipe, asserting that, while it is well motivated by theory, it is incompletely supported by evidence based medicine. It asserts that the simple story neglects other effects of nerve agents, which compete with the simple story for lethality. According to the challenge,
- Treating these other effects may be more important than reactivating AChE, which may not be possible, or which may happen anyway by mechanisms that are not currently understood.
- Some OTC medications may work better than atropine as anticholinergics.
- These OTC medications counteract another effect of nerve agents, which resembles a massive, lethal allergic reaction.
I take no position. This is an attempt to make the literature accessible.
This discussion has a lot of big words. Digest this; conclusion follows.