Scientists seeking to learn how to grow teeth
Humans naturally come with only two sets of teeth — baby and adult — so most of us work pretty hard to hang onto the latter. Alligators, on the other hand, can be reasonably assured of a toothy grin throughout life. They may replace each of their 80 teeth as many as 50 times in a lifespan.
Scientists at the University of Southern California are trying to tap into that admirable regenerative ability. They report identifying unique cellular and molecular mechanisms underlying the gator's tooth renewal and hope to use the knowledge to help regrow teeth in adult humans.
"Ultimately, we want to identify stem cells that can be used as a resource to stimulate tooth renewal in adult humans who have lost teeth," said study author Cheng-Ming Chuong. "But, to do that, we must first understand how they renew in other animals and why they stop in people."
Using microscopic imaging techniques, the researchers found that each alligator tooth is a complex unit of three components — a functional tooth, a replacement tooth and the dental lamina — in different developmental stages.
The researchers found that the dental laminae contain what appear to be stem cells from which new replacement teeth develop. Researchers plan to isolate them to see if it's possible to use the stem cells to regenerate teeth in the lab. Not to worry. The idea isn't necessarily to grow alligator teeth for humans, but to extrapolate the learned principles of regeneration to people.
Body of knowledge
The middle part of the back is the least sensitive surface of the body.
Get me that stat!
Children born to women exposed to the flu during pregnancy were associated with a nearly fourfold increased risk of developing bipolar disorder in adulthood, according to the National Institutes of Health. The findings add to evidence that suggests a link between prenatal influenza exposure and some forms of mental illness, including schizophrenia.
Life in Big Macs
One hour of massaging someone while standing burns 272 calories (based on a 150-pound person) or the equivalent of 0.4 Big Macs.
Stories for the waiting room
Sunscreen is an effective way to ward off the harmful effects of the sun, but only if you use it correctly, which according to the American Academy of Dermatology, appears to be something of a challenge for some people. The Academy offers these five timely tips:
1. Choose a sunscreen with an SPF of 30 or higher, that's water resistant and provides both UVA and UVB protection.
2. Apply generously, at least 15 minutes before sun exposure to allow absorption by skin. Rub thoroughly into skin.
3. Don't skimp. Most adults require at least one ounce of sunscreen per application — enough to fill a shot glass — to cover all exposed parts.
4. Apply to all bare skin. Wear a hat if you have thinning hair. Apply lip balm with SPF of 15 or greater.
5. Reapply sunscreen at least every two hours and immediately after swimming or excessive sweating.
Hemiasomatognosia: A term describing a person who has had a stroke or other brain injury and, as a result, forgets about half of their body. In severe cases, they lose all concept of one side of the universe, so that "left" or "right" no longer exists.
Phobia of the week
Climacophobia: Fear of stairs
Never say diet
The Major League Eating record for burritos (long form) is 11.81 pounds in 10 minutes, held by Tim "Eater X" Janus. Warning: Most of these records are held by professional eaters; the rest by people who really should find something better to do.
Two psychiatrists are riding bikes. One loses balance in some loose gravel and falls. He's hurt badly, bruised and bloody. The other psychiatrist races back, hops off his bike, his face a mask of concern and asks: "Do you want to talk about it?"
"One of the signs of an approaching nervous breakdown is the belief that one's work is terribly important."
— Bertrand Russell (1872-1970), British philosopher
— American writer Henry David Thoreau (1817-1862)
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