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November 17, 2009

BehindTheMedspeak: Why does it feel so good to scratch that itch?

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Long story short: first, you need to know why something itches.

For that we turn to Benedict Carey's April 7, 2009 New York Times story to give us an overview of recent research which may have solved a longtime biological mystery.

Here's the article.

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Scratching Relieves Itch by Quieting Nerve Cells

As common as it is, scratching to relieve an itch has long been considered a biological mystery: Are cells at the surface of the skin somehow fatigued, in need of outside stimulation? Or is the impulse, and its relief, centered in the brain?

Perhaps neither one, a new study suggests. Neuroscientists at the University of Minnesota report that specialized cells in the spinal cord appear to be critically involved in producing the sensation of itch and the feeling of relief after the application of fingernails, at least in healthy individuals. The study appears in the current issue of the journal Nature Neuroscience.

“It’s as if there’s a little brain in there that creates this state in which scratching — which normally excites pain cells — instead inhibits them,” said Glenn J. Giesler, a co-author of the study. The same cells that register the itch also are sensitive to pain.

“It’s a very important study; itching is a major problem for millions of patients,” said Dr. Gil Yosipovitch, a dermatologist at the Wake Forest University School of Medicine and founder of the International Forum for the Study of Itch.

Dr. Yosipovitch cautioned that the findings may not apply to the sort of chronic itch that plagues people with atopic eczema, H.I.V. or chronic kidney problems. “But this is the kind of work that should help open this area up to more research.”

In the study, led a postdoctoral student, Steve Davidson, researchers isolated in monkeys cellular connections that run from the surface of the foot to the spinal cord and then to the thalamus, a clearinghouse for sensations in the brain, down through the spinal cord to the surface of the foot. They induced the sensation by injecting histamines under the skin.

The scientists took single-cell recordings in an area at the base of the spinal cord, in the lower back, in so-called spinothalamic neurons. These cells are sprinkled throughout the spinal cord. Most are sensitive to pain, and some to both pain and itch. The cells apparently detected the injection and began firing immediately afterward. And when the researchers scratched the itchy skin on the monkeys’ feet, it quieted the cells’ activity.

“It’s the first time I’ve ever seen a noxious stimulus — the scratching — stop the firing of cells,” Dr. Giesler said. His co-authors, along with Mr. Davidson, were Xijing Zhang, Sergey G. Khasabov and Donald A. Simone.

Scientists argue that itching is most likely related to grooming, and evolved to protect animals against some toxic plants, as well as insects, along with the diseases they can transmit, like malaria, yellow fever and river blindness. But the biology of itch has been a mystery, and neglected for years by researchers, who have been far more focused on pain.

Some 50 diseases leave people in a misery of itching which usually cannot be treated. Studies among kidney disease patients and psychiatric inpatients have found that itch is among the top complaints. And when it is severe it keeps people up at night, often worsening their condition.

The new study suggests that itch, like pain, may be a “gated” system in which signals from other nerve cells can interfere with or moderate the sensation. Scratching the skin near, but not directly on, the spot that itches often provides relief, just as rubbing an aching limb can reduce pain. Perceptions in the brain, too, probably moderate the urge to scratch: some chronic, compulsive cases of itching suggest that the brain is not properly reading the effect of outside signals at all but is instead acting on a mistaken internal representation of what is happening to the skin.

As with some kinds of pain, subtle reminders of an itching sensation can get people scratching, often without being entirely aware of it.

“I give lectures about itching,” Dr. Giesler said, “and I’ll stand up there in front of a whole roomful of people, show a few slides and pretty soon I’ll look out and 90 percent of the audience is scratching.”

Like yawning, itching also seems to be contagious, which suggests a significant top-down influence from the brain.

Dr. Yosipovitch said there was a long way to go before doctors could expect treatments. For one thing, the miserable, chronic itch common in many medical problems most likely involves other mechanisms in addition to those identified in the study. And the brain may be critically involved in escalating itch, in ways that are not yet understood. “But as a clinician, I feel excited about the finding,” he said. “It’s a sign that this field is really evolving.”

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Here's the abstract of the article published in Nature Neuroscience.

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Relief of itch by scratching: state-dependent inhibition of primate spinothalamic tract neurons

Itch is relieved by scratching, but the neural mechanisms that are responsible for this are unknown. Spinothalamic tract (STT) neurons respond to itch-producing agents and transmit pruritic information to the brain. We observed that scratching the cutaneous receptive field of primate STT neurons produced inhibition during histamine-evoked activity but not during spontaneous activity or activity evoked by a painful stimulus, suggesting that scratching inhibits the transmission of itch in the spinal cord in a state-dependent manner.

November 17, 2009 at 04:01 PM | Permalink | Comments (1) | TrackBack

Hot Breath Gloves

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Baby, it's getting cold outside.

From the website:

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Exhale Heated Gloves

These are gloves you breathe into to provide a warm blast of air for cold fingers without removing the gloves.

An aperture built into the back of each glove allows warm air to enter the glove's interior when you breathe into it; a Velcro flap covers the aperture when not in use.

Constructed from a nylon outer shell that repels water and wind, the palm patch and thumb are made of a polyurethane blend for a solid grip; the palms, lining, and 2-3/4-oz. insulation are made from polyester.

Patented conductive fabric pods built into the index finger and thumb allow you to operate most touch screen, MP3, and cellphone devices without removing your gloves.

Black.

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$49.95.

November 17, 2009 at 03:01 PM | Permalink | Comments (0) | TrackBack

TechnoDolt™ Not Chosen as 2009 Word of the Year

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I'm shocked. Shocked.

No, my name's not Michelle but thank you very much for asking.

Mebbe next year.

joehead Nation will be heard from.

Just wait and see.

Don't hold your breath, though.


November 17, 2009 at 02:01 PM | Permalink | Comments (0) | TrackBack

Limited Edition Sugar Cage

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Designed by Sofie Lachaert and Luc d'Hanis.

Edition of 20, in pure silver.

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Price on request.

November 17, 2009 at 01:01 PM | Permalink | Comments (0) | TrackBack

bookofjoe lite: me on Twitter

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That's how I'd characterize my Twitter postings to date.

On average five times a day, more often than not with a link to the topic of the tweet.

For those who find bookofjoe in its full glory too much of a muchness, as they say in Jamaica, the low-cal version might be just the ticket: 140 characters max/post, no graphics, no sound.

There's no overlap between the content of the two sites now that automatic blog posting to Twitter's broken (not to be restored).

Restful.

November 17, 2009 at 12:01 PM | Permalink | Comments (2) | TrackBack

Five Step Slimming Zipper Belt

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From the website:

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Five Step Belt

Five Step Zip Belt gives you a slimmer look in seconds.

Stretchable neoprene tightens trouble areas so you can comfortably fit into your favorite skirt or dress.

A great way to get ready for a wedding, reunion or other special event when your diet's not working fast enough.

Five zipper closures accommodate all stages of dieting.

Unisex for waists 22" to 43".

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"...favorite skirt or dress... unisex.

Am I missing something?

$19.98.

November 17, 2009 at 11:01 AM | Permalink | Comments (2) | TrackBack

Colorless Coke Can

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Cool.

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"A convex logo substitutes for a colorfully sprayed can. Naked can helps reduce air and water pollution occurring in the coloring process. It also reduces energy and effort required to separate toxic color paint from aluminum in the recycling process. Huge amounts of energy and paint required to manufacture colored cans will be saved. Instead of paint, manufacturers process aluminum with a pressing machine that indicates brand identity on the surface."

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Concept by Harc Lee.

[via The Dieline and m'appeal]

November 17, 2009 at 10:01 AM | Permalink | Comments (2) | TrackBack

Hermès 8 Days Spiral Boule Clock — Edition of 1


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Pictured above, it's a glass orb the size of a cricket ball (88mmØ) that winds by twisting the halves of the magnifying optical crystal sphere in opposite directions.

"The only protruding part is a push-button at 6 o'clock that is pressed to switch from winding to time-setting mode."

231 parts weighing 1,063 grams.

200-hour power reserve.

$560,000.

November 17, 2009 at 09:01 AM | Permalink | Comments (1) | TrackBack

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