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Hibernating Bears Key to University's Medical Research - 2003-10-14

Next month, the snow begins to fly in the high country of the American northwest, sending the resident bears into their dens to hibernate. A few bruins will have their sleep rudely interrupted this winter - but it's all in the name of science. University researchers in the Midwest and the Far West believe sleepy grizzly and black bears could give up secrets for improving medical therapies and helping astronauts during long-distance space travel. Washington State University is the only place in the country that holds captive grizzlies purely for research.

Researcher Lynne Nelson gets cozier than most people would ever dare with a pair of grizzly bears. She offers her hand to the excited cubs. They rear up on their hind legs to lick through the cage wires.

"People think of grizzly bears as being these big ferocious animals," she said. "And they are big animals and they are quite powerful, but their natural intent isn't to be aggressive."

Luna and Mica were born in captivity here to parents who, at the moment, are hungry. They sound more like what you'd expect from the king of the North American food chain.

The adult grizzlies on the Washington State University campus are a mixture of rescued orphans and 'problem' bears caught raiding garbage cans or country stores in the Rocky Mountains. Researcher Nelson and her colleagues bottle-fed two of this year's cubs so they would be comfortable with human handlers. That familiarity opens the door for fascinating medical studies.

"That was our goal, is to have these bears that would be trained and adapted to people well enough to have ultrasounds, and EKGs, blood pressures, things like that done on a routine basis so we could study heart function [and] physiology, particularly during hibernation," she said.

Ms. Nelson says a bear's heart during hibernation resembles that of a human with coronary artery disease.

"But at the end of hibernation, they return to normal," she said. "So understanding those mechanisms and how they can look diseased but then return to normal may be important for human and animal health."

Once a month this winter, the groggy cubs will be placed on an exam table.

Lynne Nelson, who's already outweighed by the baby bears, will slather gel on their chests. Then she'll record ultrasound images of their slowly beating, sick-looking hearts. This sort of monitoring has been done with ground squirrels, but never before without anesthesia, on beasts as large as grizzlies.

Given the genetic similarity of heart muscles, Ms. Nelson says it's "not too far fetched" to imagine therapies for human coronary disease based on these ursine observations.

"The physiology amongst all the large mammals is very, very similar," she said. "If there is some adaptation that they can naturally do to preserve their heart function, we might be able to learn it."

Other scientists share this hope based on experiments with black bears in Colorado and Minnesota. Paul Iaizzo says his multi-university team is closing in on a drug combination that mimics the effects of hormones found in hibernating bears. The medical professor is most interested in using the drug therapy in hospital intensive care units but says the U.S. space agency is curious about its potential use by astronauts, too.

"That angle, if this is the case that you can give these factors - and you can slow down whole-body function and metabolism and maintain muscle mass, preserve all the vital organs, and do that in a state of starvation - that would be a chance for someone to extend space travel," he said.

Professor Iaizzo says he's visited "50 some" dens over the past five years to take muscle and blood measurements from their sleeping occupants. This winter, the professor plans to track down six to eight hibernating bears in Minnesota's North Woods who were previously fitted with radio-collars to help locate them.

"You slowly approach that den, not trying to arouse the animal, and then you anaesthetize that bear with what we call a jab pole which is about three feet (1-meter) long and at the end there is a hypodermic needle that administers an anaesthetic," he said.

Even in the dead of winter, hibernating bears will wake up and charge if someone enters their den. In Colorado, this sampling technique drew angry letters to the editor, complaining the researchers were "mean" to wake the slumbering bears and drag them outside for a battery of tests. Professor Iaizzo prefers to look at the long-term benefits. Roused from their peaceful slumbers, these bears are giving up secrets that could heal sick hearts, weak muscles and bones, and even send humans safely into deep space. And then, they can go back to sleep.