Saturday, June 25, 2011

"Me no like carrots"/Protein fragment could be target for treatment of eczema itch

Saturday--double swimming lessons again. We're getting dried off afterward, me and the two kids, and in the men's changing room they're getting some lessons in anatomy as a number of hirsute and moderately obese men shower. One of them lathers himself head to toe with soap. I kid you not, I have never seen someone so completely covered with suds, as if he'd been dipped like a sheep. What must it be like to be able to use soap like that without consequences? For me and Voov soap is something to be used sparingly if at all.

Voov, as you may know, has been on a restricted diet. For about a year or so she has eaten about eight things (others are allowed but not always available as organic produce--e.g. asparagus). So three weeks ago we were given the green light to start trying a small roster of new foods. The first candidate was carrots, which we chose for their nutritional punch. We were excited as we placed the first plate of chopped, boiled carrots in front of Voov. She picked up a piece and stuck it in her mouth.

"Me no like them. Me not eat them," she said.

And so it proved, after we offered them every day for two weeks: she doesn't like carrots. Fortunately she liked the next two items, apple and pork; we are on week two of pork and next week on to something else.

Hidden B went away last week to a veterinary conference and chose the opportunity to wean Voov off breastfeeding. That's two and a quarter years Voov has been breastfed (Hidden B is ecstatic to be able to eat dairy again) and I hope that her eczema and potential asthma are less severe because of it. I myself was fed on formula pretty much from birth. My mother says that that was what mothers were told to do in those days. I suspect but cannot prove that my food-related eczema has been nastier because of the formula--Hidden B tells me the opinion of doctors at her vet practice (now there's authority for you) is that it's better for kids to be exposed to tiny amounts of allergens through their mothers' milk, rather than be completely deprived of exposure and then hit all at once when they eat real food.
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I thought I would write a bit about a recent paper in the Journal of Neuroscience. Scientists at Yale and Johns Hopkins have found, in experiments with human volunteers, that BAM8-22, a common protein fragment found in the body can produce itch by a neural pathway independent of histamine.

Histamine is a small molecule that some foods (pickles, aged cheese, red wine) contain a lot of; it is also stored in white blood cells called mast cells that release it in response to food allergies. There are neurons with receptors for histamine, and these neurons send itch impulses to the central nervous system. This is why I scratch like a demented monkey after I eat Parmigiano-Reggiano.

But it is also known that there are other neural pathways for itch; researchers don't know many details yet. For this new paper, the scientists showed that when they poked volunteers' forearms with little plant spines coated with BAM8-22, the forearms got itchy, even if they had been rubbed with antihistamine cream beforehand.

The plant spines are called "cowhage spicules." Cowhage is famous for making people itchy, and it has tiny spines covered with an enzyme that triggers itch. A group of scientists has decided that cowhage spicules are the perfect instruments for applying chemicals that induce itch. Is that weird or what? Apparently if you autoclave (treat at high temperature & pressure) the spicules for an hour, the original enzyme is destroyed and the spicules don't make you itchy.

So the upshot of this new research is that BAM8-22 and the receptor it interacts with (its identity is known too) could be a major pathway by which chronic itch signals, like those that operate in eczema, are sent to the central nervous system. It's possible that pharmacologists may now search for drugs that inactivate the BAM8-22 receptor, and conduct clinical trials to find out whether the drugs relieve chronic itch. My guess is that such drugs could emerge in a decade or so, if a pharma company--or startup--decides that the pathway could be profitable.

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