It seems a kind of hearsay (hair-say?), but researchers at the Keck School of Medicine at the University of Southern California have found that by tweezing out 200 hairs in a specific pattern and density, they can induce up to 1,200 replacement hairs to grow in a mouse.

It was already well-known that injury to a hair follicle affects its neighbors. The USC scientists wondered whether the loss of a hair might stimulate surrounding follicles to become more active. (At any given time, only a percentage of follicles are actively growing hair; the rest lie temporarily dormant.)

To test their hypothesis, they plucked 200 hair follicles, one by one, from the backs of mice in different configurations. When plucking was conducted in a low-density pattern over a larger region, no hairs regenerated. However, higher-density plucking in a smaller area triggered the regeneration of between 450 and 1,200 hairs, including ones outside the plucked region.

The researchers discovered that the plucked follicles release inflammatory proteins signaling distress, which recruit immune cells to the site. The immune cells secrete molecules that inform both plucked and unplucked follicles that it's time to grow hair.

Body of Knowledge

In the brain, serotonin is a neurotransmitter critical to regulating mood, appetite and sleep. It also has a role in cognitive functions such as memory and learning. But most of the serotonin in your body — 90 percent — resides in your gut, where it is used to regulate intestinal movements. And according to new animal studies, serotonin production relies not so much on you as it does certain bacteria interacting with the body's enterochromaffin cells.

Number Cruncher

A Starbucks low-fat turkey bacon breakfast sandwich (100 grams) contains 230 calories, 54 from fat. It has 6 grams of total fat, or 9 percent of the recommended total fat intake for a 2,000-calorie daily diet, according to the Calorie Count database.

It also contains 20 milligrams of cholesterol (7 percent), 820 milligrams of sodium (34 percent), 28 grams of total carbohydrates (9 percent), 4 grams of dietary fiber (16 percent), 5 grams of sugar and 13 grams of protein.

Mania of the Week

Theomania: belief that one is a god.

Never Say Diet

The speed-eating record for chicken tamales is 47 (2.6 ounces each) in eight minutes, held by Stephanie "Xanadu" Torres. Our advice: Xanadon't try this at home.

Observation

"Hospitals should be arranged in such a way as to make being sick an interesting experience. One learns a great deal sometimes from being sick." — British philosopher Alan W. Watts (1915-73)

Medical History

This week in 1887, George Thomas Morton performed the first American operation to remove an appendix — an appendectomy — saving the life of a 26-year-old man with appendicitis. Interestingly, Morton was the son of William Thomas Green Morton — who gave the first successful public demonstration of surgical anesthesia, in 1846.

Curtain Calls

John Bowen, a 20-year-old from New Hampshire, attended a New York Jets football game at Shea Stadium in 1979. The halftime show featured a display of custom-made remote control flying machines. One of the machines — a 40-pound model plane shaped like a lawn mower — went out of control, dived into the stands and struck Bowen and another spectator, causing severe head injuries. Bowen died of his injuries four days later.

To find out more about Scott LaFee and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.