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Archive for Saturday, October 27, 2001

Health briefs

October 27, 2001

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Live-virus vaccines offer promise, risk

Using live virus in vaccines is a double-edged sword, according to the Higuchi Biosciences Center and the Drug Information Center at Kansas University.

Vaccination is a trick on the immune system. A batch of a germ either live or dead is injected into the body. In response, the body manufactures defenders to fight it. If the germ then enters the body for real, the system's ready.

In the dead-germ approach, the germ is first killed. But that can change it in subtle ways so the immune system isn't well-prepared for the real thing.

A live but weak germ can create a lasting immune response. But there's a risk. It might run amok, causing the disease it's supposed to prevent.

About two dozen AIDS vaccines are under study. Only one contains live virus. The idea of a live-virus flu vaccine also stirs anxiety in some quarters.

Because the live-germ approach is potentially so effective, scientists are starting to tinker with the genes of live germs. Their aim is to mess up the disease-causing part of the germs but leave the rest intact.

The result would be an agent that could keep the immune system alert for a given germ at all times and do no harm.

Caffeinated sodas promote calcium loss

Several studies have linked soft drinks with weakened bones and an increased risk of fractures. The theory was that these popular drinks leached calcium from bones.

But the latest findings from osteoporosis researcher Robert P. Heaney's lab at Creighton University in Nebraska suggest that only soft drinks with caffeine actively promote calcium loss. Even then, the loss is minimal and quickly reverses itself within a few hours, Heaney reports in the upcoming American Journal of Clinical Nutrition.

So what gives? Earlier findings, suggests Heaney, likely reflected the fact that soft-drink buyers are less likely to drink milk. In other words, he says, soft drinks earn a bad bone reputation not by robbing bones of calcium but by displacing calcium-rich foods in the diet.

"My message to consumers is: If you are drinking colas, fine, just be sure that you get some calcium-rich foods during the day," he said. "Don't let the current puritan streak stop you from having a soft drink. But don't forget that this country has a calcium crisis, either."

For the sake of full disclosure: This study received partial industry sponsorship from not soft-drink makers or sugar processors, as you might think, but the Dairy Council.

Study: Brief exercise helps boost moods

Exercising for even a short while each day may improve mood, found a pilot study of female college students.

Just 10 minutes of moderate work on an exercise bicycle was enough to improve overall mood when compared with sitting quietly for 30 minutes, say researchers at Northern Arizona University.

Cycling longer 20 or 30 minutes didn't improve mood further.

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