Season 4, Episode 2: La Consecuencia
David returns to Mexico to look for Carlos and to continue helping fight the TB outbreak in Chiapas. Rachel and Mayko are trying to find an antibiotic that will kill the XDR-TB bacteria, and are also still working on the case of Hudson Point, Illinois, where many people have lost the ability to feel pain. They discover that everyone in Hudson Point - a farming community - has a fungus growing in their nose that produces a compound that blocks pain sensation.
 Image provided courtesy of Shaftesbury Films. |
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Rachel explains the mice/human Hudson fungus ratio to David. |
CAN A FUNGUS TRIGGER INSENSITIVITY TO PAIN?
What is pain sensation?
As Rachel and Mayko explained in the previous episode, our ability to feel pain is a protective mechanism that makes us pull back from the source of pain before we even realize what's happening. Pain sensation, or "nociception", is transmitted by nerve cells (neurons) called nociceptors. The nociceptors detect potential causes of pain, such as tissue damage or extreme temperatures, and very quickly send an electrical current to the spinal cord, which provokes a response in the affected area of the body.
How is the pain signal transmitted to the spinal cord?
If you burn yourself on a hot stove, for example, the heat triggers a pain signal in the tip of a nerve cell close to the skin that is touching the stove. This causes a change in electric current to be created in the cell and then passed along the length of the cell towards the spinal cord.
This electric current is created by the opening and closing of tiny gates in the cell membrane called ion channels. Ions are atoms or molecules with a small electrical charge. When ions flow in and out of cells through ion channels, they create a change in electric potential at that location in the cell. This is the start of an electric message that is then transferred along the neuron to the spinal cord.
What is the pain reflex?
At the spinal cord, the electrical pain message is then transferred directly to another type of neuron: the motor neuron. These neurons control muscles, and make you quickly pull back from the source of the pain. The message is also sent to the brain, which controls slower responses, such as the release of pain relieving endorphins, but it takes longer for this second signal to reach the brain than the initial reflex. This is why you pull your hand away from the stove before you even realize that you're in pain.
Is it possible to not feel any pain?
Yes. If the neurons that detect pain don't work properly, the pain message is not passed on to the spinal cord. There is no reflex to pull back, and no pain signal is sent to the brain. This can happen when the ion channels don't open and close properly: the electric signal is never passed on.
In the previous episode, Mayko reads about a family in Pakistan who don't experience pain. This family - which is a real family - has a mutation that prevents a certain type of ion channel from working; no ion channel, no pain. That ion channel is only present on nerve cells related to pain detection, so no other neurological pathways are affected.
 Image provided courtesy of Shaftesbury Films. |
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The team brainstorms about why the fungus is producing more pain-reducing agents in Mayko than in Rachel. |
What is Eupenicillium shearii?
The NorBAC team finds a fungus called Eupenicillium shearii growing in the noses of everyone in Hudson Point. They discover that it secretes a pain-blocking compound. While E. shearii hasn't been extensively studied, it is known that it does indeed produce several chemicals that are able to interact with ion channels on nerve cells. One of these compounds blocks ion channels involved in certain types of pain sensation in rats, but this does not block all feelings of pain and also has effects on other cells of the nervous system.
What is oil of wintergreen?
Oil of wintergreen, or methyl salicylate, is a chemical released by several plants as a natural defense mechanism. It releases its unique minty smell from plants that are infected by various pests, and the smell recruits beneficial insects to the infected plants. Methyl salicylate is also able to kill several types of fungi, but the effect on E. shearii is not known.
A lot of consumer products contain methyl salicylate in very low concentrations as a fragrance or flavour component, or in higher concentrations as active ingredient in muscle rub creams.
So?
While it's possible to be insensitive to pain if one of the pain-specific ion channels is not working, it's unlikely that the combination of methyl salicylate and Eupenicillium shearii would produce a compound that inhibits only these ion channels. Methyl salicylate is more likely to kill a fungus than to activate it to produce more chemicals. Even if it was possible for a low amount of methyl salicylate to trigger E. shearii to suddenly produce and secrete more nerve-interacting compounds, it would probably produce several chemicals with a range of different effects and not just block pain.
DID YOU KNOW?
After his disappearance and brain surgery, Bob has been put into a chemically induced coma. This is a common medical procedure to relieve swelling of the brain. The coma is brought on by administering drugs called barbiturates, which limit blood flow to the brain. This reduces swelling and protects the brain, but it also slows down brain activity. In this state, the cerebrum - the part of the brain that deals with memories and dreaming - is not functioning. Reliving memories in dreams like Bob does in his coma is generally considered impossible.
-- Eva Amsen
Want to read and learn more?
To learn about pain detection, visit:
http://www.ctv.ca/servlet/ArticleNews/story/CTVNews/20070324/pain_study_070324/20070324?hub=Health
Here is a site with information about different types of fungi:
http://io.uwinnipeg.ca/~simmons/16cm05/1116/16fungi.htm
Find out more about methyl salicylate on Wikipedia:
http://en.wikipedia.org/wiki/Methyl_salicylate
Read about barbiturate induced comas:
http://www.healthatoz.com/healthatoz/Atoz/ency/barbiturate-induced_coma.jsp
