Blood, sweat and no tears heal wounds

Humans have evolved a sweaty way to repair skin wounds.

It was thought the body repairs wounds such as bed sores and burns by generating new skin cells from hair follicles or the skin at the edges of the wound, the same way that other animals do.

But Laure Rittie of the University of Michigan Medical School and colleagues have shown a type of sweat gland not found in animals also plays a role.

The team used a laser to create minor wounds in 31 volunteers. Over the following week they took skin biopsies of the wound to identify where new skin cells had grown. Before wounding, there were few new cells in the eccrine glands, which help regulate temperature, but four days later there were plenty.

This suggests the glands contain a reservoir of adult stem cells that can be recruited to repair wounds. Humans have three times more eccrine glands than hair follicles, making them the major contributor to new skin cells.

The finding is "unexpected and against current dogma," says Elaine Fuchs from the Howard Hughes Medical Institute in Maryland. Rittie says the work has "taken the first step to identifying new therapies in wound healing."

Grapefruit pumps up drug effects

A healthy breakfast of half a grapefruit? Not advisable if you're taking certain prescription drugs. The interaction with the fruit could result in an inadvertent overdose.

To find out the extent of the effect, David Bailey, of the University of Western Ontario in London, Canada, reviewed the literature and prescribing information of various drugs for any mention of a reaction. He found of the 85 drugs known to interact with grapefruit, 43 can result in severe adverse effects. The number has increased by 24 percent since 2008 because new drugs have come onto the market.

Chemicals in the fruit destroy an enzyme in the body that normally breaks down substances such as drugs. That means the drug keeps circulating in the body, which can lead to overdose. A glass of the juice is enough, even if drunk hours before taking a drug, says Bailey.

The most serious adverse effect is a condition known as torsade de pointes, which can cause cardiac arrest and death. It can occur if you mix grapefruit and anticancer drugs.

"Care should definitely be taken with certain drugs," says Bill Widmer of the U.S. Horticultural Research Laboratory in Fort Pierce, Fla., but he adds there are people who "believe the problem is overstated."