Coronaviruses derive their name from the corona visible in
images such as this 1975 transmission electron micrograph
of infectious bronchitis viruses
When a 49-year-old Qatari man fell ill in England this month, doctors realized that his respiratory problems and kidney failure were due to a previously unknown virus. Earlier this year, a nearly identical virus, 99.5 percent genetically identical to be exact, killed a middle-aged Saudi man. While a new disease is always cause for caution, there have been only two confirmed cases thus far. So what’s the worry? The problem is that this new virus belongs to a family called coronaviruses, a family that includes the common cold…and the deadly and fast-spreading Severe Acute Respiratory Syndrome, or SARS.
Coughing in the brain
For something so mundane, we know surprisingly little about coughing. Most of us just cough when we’re sick, but patients with habit and psychogenic coughs don’t seem to have any sort of physical trigger. Recent cough research, highlighted in a feature at ScienceNews, suggests that the neural circuitry of coughing also involves temperature perception and higher brain areas.
The same cellular receptors that sense temperature and pain also control coughing. The cool relief of a cough drop is no coincidence, as the menthol receptor both suppresses coughs and produces the cool feeling in your throat. There’s a molecular on-switch for coughing, too: a receptor called TRPV1. Unfortunately for researchers looking for a cough cure, inactivating TRPV1 also makes it dangerously difficult to feel heat. Mundane tasks like eating a hot meal or running a bath become hazardous if you don’t reflexively shrink away from scalding heat.
Other scientists are looking inside the brain, studying whether habitual and psychogenic coughs are the result of some suppression mechanism gone haywire. Stuart Mazzone has been putting people in fMRI machines along with a capsule of capsaicin to eat. Since capsaicin is the molecule that makes chilis fiery, it’s not so surprising that it also causes coughs. As Mazzone puts it, your throat is constantly irritated when you’re sick, but you aren’t coughing the entire time. That means you have some ability to voluntarily control coughs. And, as ScienceNews reports, brain activity patterns seem to agree: