Previous Page 3 of 4 Next

Continued: Can dormant bears help us heal?

  • Article by: BILL MCAULIFFE , Star Tribune
  • Last update: December 26, 2009 - 11:26 PM

CAMP RIPLEY, MINN. - For two winters now, a mother bear has been denning on George Vilinski's land. A few tracks last spring are the only signs he has seen.

"She's like a ghost," he said.

But researchers are hoping this bear and others around the state will reveal some mysteries about hibernation -- and how it might be used to help humans.

"It could have a lot of positive benefits if we find out what these bears are doing," said Paul Iaizzo, a surgery professor and principal investigator at the University of Minnesota's Visible Heart lab.

Recently Iaizzo and a team of researchers from the University of Minnesota, Medtronic and the Department of Natural Resources visited the bear on Vilinski's land, and others in northern and northwestern Minnesota, to see what they might be able to detect from small heart monitors they implanted last spring.

Hauling nearly $150,000 worth of computers, electrocardiographic recording devices, infrared cameras and ultrasound equipment (not to mention surgical equipment and 40 pounds of batteries) through the woods, the team set up a makeshift physiology lab on the snow only yards downhill from the snow-covered den in a knot of tree roots next to a small pond. For the next few hours they would use it to paint one of the most detailed pictures to date of a bear's inner workings.

It's already known that bears in hibernation don't eat, drink, urinate or defecate for five months. Yet they don't starve. By recycling their own waste, they avoid buildups of toxins. They don't exercise, yet they lose only a fraction of the muscle strength humans would if they were idle that long. Their hearts might slow to five beats per minute, yet they maintain heart strength and structure.

Unlike other animals such as squirrels, whose hibernation temperatures can drop to near freezing, bears' body temperatures drop only a few degrees. With predators (and researchers) combing the woods, they also remain alert and able to spring into action, contrary to the popular understanding of hibernation as a long snooze.

If humans someday could be made to perform the same tricks as bears, they might use them not to get through winter, but to recover from injury, surgery or long periods of bed rest. Iaizzo's lab has shown that substances that cause a bear to go into hibernation may have applications in humans to protect organs from damage from oxygen deprivation.

The National Aeronautics and Space Administration also has funded some research on bears in the belief that their retention of muscle strength could be adapted to help astronauts reduce atrophy during long periods in space.

"There are numerous things about bears that are miraculous, based on what we know about human physiology, and what we believe mammals can tolerate," Iaizzo said. "But the more work we do, the more questions that arise."

Little laboratory in the woods

Answers to some of those questions came in their north woods laboratory.

The team already knew that a hibernating bear might slow its heart and breathing to rates that would cause a human to faint, yet with a single breath could boost its heart's blood and oxygen-pumping capacity eightfold. They also knew that the mother bear they were testing was known for a high level of vigilance in hibernation.

"She's the angry female," said Brian Dirks, Camp Ripley animal survey coordinator. "She doesn't sleep very sound."

Tim Laske, an adjunct professor of surgery at the University of Minnesota and engineering director at Medtronic, learned that when he slipped a camera attached to a long stick into her den as she seemed to be slipping under the effects of a tranquilizer. In a flash she was lunging teeth-first at the lens.

More than an hour later, confident that the 251-pound mother bear was tranquilized, the team dragged her onto plastic yoga mats, where Laske would try to find the implanted heart monitor. It's a titanium device about the size of a computer flash drive, and Laske didn't have much hope. Bears have strong immune systems that have rejected devices in the past, and nine months in the brush can be tough on high-tech electronics.

Laske patted the bear's chest. "Here it is!" he shouted. Within minutes, Iaizzo had attached electrodes to the bear's chest and to a computer, and measurements of the bear's heart rate, stored since March 7, poured into a database.

It was, Iaizzo said, "data no one else really has from an animal that's been out in the wild for nine months."

Laske noted that the bear had experienced 60,126 episodes of bradycardia -- periods with extremely low heart rate, sometimes stopping altogether for as long as nine seconds. (One of the other bears reported pauses of more than 14 seconds.) Second assessment: She'd gone into hibernation in late November.

After the first data download, Iaizzo brought up some ultrasound images on a small screen of the interior of the bear's heart as it beat -- similar to those used to check development of fetuses. An electrocardiographic monitor measured the heart's electrical and mechanical activity.

After two hours of body measurements, blood tests and other exams by Dirks and DNR bear biologist Dave Garshelis, the mother and cub were shoved back into the den.

They won't remember a thing

The bears, Iaizzo said, wouldn't recall the encounter. But the researchers expect to be replaying it quite a bit, through the piles of data they downloaded.

Lynn Rogers, director of the North American Bear Center in Ely and a world-renowned bear researcher, said the implanted devices seem to corroborate research done several decades ago. "That's a good thing," he said. Rogers uses time and trust to approach bears and measure their heartbeats by hand; he said he would never use an implant. But he said he'll be interested in further results from the devices.

Laske and Iaizzo said researchers have their fingers crossed that some features of hibernation might someday be induced in humans. Conservation of the heart's energy, particularly, might help injured people's bodies focus on healing. Substances that induce hibernation might be used to preserve donor hearts for longer periods before they are transplanted, as well as to protect heart muscles from further damage after an attack.

"I think where we owe the bears a debt of gratitude is in learning things we previously didn't think were possible, and opening the minds of scientists to other possibilities of human therapies," Laske said.

At his home near the bear's den, Vilinski said he's looking forward to spring when the researchers return to check on the bear and her cub.

"Having [the bears] out here like this, I enjoy it," he said. "It's interesting. I just wish a guy could see her once in a while."

Bill McAuliffe • 612-673-7646

  • get related content delivered to your inbox

  • manage my email subscriptions

Click here to send us your hunting or fishing photos – and to see what others are showing off from around the region.

ADVERTISEMENT

Tennessee 13 FINAL
Jacksonville 21
Philadelphia 12/20/14 3:30 PM
Washington
San Diego 12/20/14 7:25 PM
San Francisco
Minnesota 12/21/14 12:00 PM
Miami
Baltimore 12/21/14 12:00 PM
Houston
Detroit 12/21/14 12:00 PM
Chicago
Cleveland 12/21/14 12:00 PM
Carolina
Atlanta 12/21/14 12:00 PM
New Orleans
Green Bay 12/21/14 12:00 PM
Tampa Bay
Kansas City 12/21/14 12:00 PM
Pittsburgh
New England 12/21/14 12:00 PM
NY Jets
NY Giants 12/21/14 3:05 PM
St. Louis
Buffalo 12/21/14 3:25 PM
Oakland
Indianapolis 12/21/14 3:25 PM
Dallas
Seattle 12/21/14 7:30 PM
Arizona
Denver 12/22/14 7:30 PM
Cincinnati
New York 97 FINAL
Chicago 103
New Orleans 99 FINAL
Houston 90
Milwaukee 108 FINAL
Sacramento 107
Oklahoma City 109 FINAL
Golden State 114
Florida 2 FINAL(SO)
Philadelphia 1
Colorado 0 FINAL(OT)
Pittsburgh 1
Toronto 1 FINAL
Carolina 4
Washington 5 FINAL(OT)
Columbus 4
Anaheim 2 FINAL
Montreal 1
St. Louis 4 FINAL
Los Angeles 6
Edmonton 3 FINAL
San Jose 4
St Thomas (TX) 61 FINAL
Rice 72
Stony Brook 59 FINAL
Canisius 60
Temple 82 FINAL
Delaware 62
FIU 58 FINAL
Long Island 69
Lehigh 65 FINAL
Quinnipiac 80
South Alabama 54 FINAL
Richmond 65
Seton Hall 89 FINAL
South Florida 69
Ga Southern 76 FINAL
Stetson 67
Yale 57 FINAL
Vermont 56
Cleveland State 54 FINAL
Virginia 70
Wright State 69 FINAL
Western Carolina 56
Nicholls 54 FINAL
Louisiana Tech 79
Morgan State 48 FINAL
Rider 62
Idaho State 72 FINAL
South Dakota St 75
Oakland City 52 FINAL
Austin Peay 76
Eureka 38 FINAL
Bradley 80
Appalachian St 65 FINAL
Charlotte 75
Connecticut 56 FINAL
Duke 66
Southern Miss 46 FINAL
Jackson State 66
Coastal Carolina 68 FINAL
Ole Miss 71
Montana State 53 FINAL
South Dakota 55
LSU 79 FINAL
UAB 70
Ohio 69 FINAL
Evansville 81
CS-Dominguez 50 FINAL
Cal State Fullerton 72
Walla Walla 39 FINAL
Idaho 86
DePaul 59 FINAL
Oregon State 90
Nevada 65 FINAL
Pacific 69
Portland State 40 FINAL
San Francisco 77
CS-Bakersfield 56 FINAL
Utah State 57
Nevada 12/20/14 10:00 AM
Louisiana
Utah State 12/20/14 1:20 PM
Texas-El Paso
(23) Utah 12/20/14 2:30 PM
Colorado State
Western Mich 12/20/14 4:45 PM
Air Force
South Alabama 12/20/14 8:15 PM
Bowling Green
BYU 12/22/14 1:00 PM
Memphis
Marshall 12/23/14 5:00 PM
Northern Ill
Navy 12/23/14 8:30 PM
San Diego St
Central Mich 12/24/14 11:00 AM
Western Ky
Fresno State 12/24/14 7:00 PM
Rice
Niagara 76 FINAL
Cleveland State 58
High Point 59 FINAL
VA Commonwealth 81
Towson 64 FINAL
Wake Forest 74
Presbyterian 50 FINAL
Charlotte 66
Chicago State 62 FINAL
Bradley 59
Northwestern Coll 58 FINAL
Drake 102
Vanderbilt 67 FINAL
Marquette 80
Temple 78 FINAL
Howard 48
Southern Miss 66 FINAL
Ole Miss 68
UMBC 55 FINAL
Rider 67
Miami-Florida 74 FINAL
UCLA 67
St Mary-KS 51 FINAL
South Dakota 115
William & Mary 71 FINAL
Wofford 51
Troy 82 FINAL
Evansville 94
Loyola Marymount 54 FINAL
USC 96
St Francis-PA 52 FINAL
Duquesne 92
Indiana-Southeast 45 FINAL
IUPUI 95
Delaware State 52 FINAL
Detroit 74
Tenn Temple 48 FINAL
Gardner-Webb 68
West Virginia St 58 FINAL
Radford 52
Fairfield 47 FINAL
Seton Hall 79
Dartmouth 44 FINAL
New Hampshire 60
Ball State 47 FINAL
Pittsburgh 59
Jacksonville 61 FINAL
Tennessee St 64
Trine 45 FINAL
Western Mich 81
Tenn Tech 53 FINAL
Lipscomb 72
Samford 56 FINAL
Tulane 57
New Orleans 55 FINAL
Tulsa 78
Incarnate Word 61 FINAL
TX-Pan American 65
Ark-Little Rock 42 FINAL
South Dakota St 67
CS-Northridge 77 FINAL
Northern Ariz 71
Santa Clara 88 FINAL
Oregon 92
(19) Oklahoma St 55 FINAL
Weber State 49
Washington 69 FINAL
San Diego State 48
Cal Poly 68 FINAL
New Mexico 84
(10) Louisville 65 FINAL
Grand Canyon 51
Connect with twitterConnect with facebookConnect with Google+Connect with PinterestConnect with PinterestConnect with RssfeedConnect with email newsletters

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

question of the day

Poll: Should the lake where the albino muskie was caught remain a mystery?

Weekly Question

ADVERTISEMENT

 
Close