Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hibernating black bears shed light on treatments for osteoporosis

05.03.2003


Unlike humans, bears seem to recover from bone loss caused by inactivity


Wild black bears may hold some secrets to preserving bone in humans.


Researchers at Penn State Milton S. Hershey Medical Center and Michigan Technological University recently studied the animal’s unique ability to rebound from significant bone loss suffered each year during hibernation. Their study, published in the March 2003 issue of Clinical Orthopedics and Related Research, shows that wild black bears have a built-in coping mechanism that ensures that yearly hibernation doesn’t leave the bears’ bones too fragile.

"In humans, disuse or immobilization as a result of bed rest or injury causes rapid bone loss, which may not be completely recoverable and can lead to weakness and fractures," said Henry J. Donahue, Ph.D., professor of orthopedics and rehabilitation, Musculoskeletal Research Laboratory, Penn State Milton S. Hershey Medical Center. "With this study, our goal was to determine how bears recover from five to seven months of hibernation each year, which can cause them significant bone loss due to disuse."



Seth Donahue, Ph.D., a former post-doctoral fellow at Penn State College of Medicine, and an assistant professor of biomedical engineering, Michigan Technological University, added, "the black bear’s mechanism of bone recovery may even provide insight into other, more common bone diseases like age-related osteoporosis and provide a rationale for the development of new pharmacological therapies." In addition to the aging and those confined to bed, bone loss is also a problem for those with spinal cord injuries and astronauts exposed to microgravity during extended space flight.

In the study, blood samples were obtained from radio-collared wild black bears during winter denning and active summer periods. Blood samples were collected at Virginia Polytechnic Institute and State University following procedures approved by the Virginia Tech Animal Care Committee. A total of 17 bears were a part of the study: seven males ages one to seven years; six females ages one to 12 years with cubs; and four females ages one to 17 years without cubs. Bears went into hibernation in December and came out in mid-April. For the sample collected during hibernation, researchers confirmed that bears had denned from one to three months.

After collection, the blood was spun in a centrifuge to attain the blood serum, the liquid portion of the blood free of red cells and clotting agents. Then, radioimmunoassays were performed to determine serum concentrations of three substances: cortisol; the carboxy-terminal cross-linked telopeptide (ICTP) – a marker of bone loss; and the carboxy-terminal propeptide of type I procollagen (PICP) – a marker of bone formation.

Higher concentrations of ICTP or PICP in the serum indicate that a bear is losing bone or forming bone, respectively. Although its role is somewhat unclear, cortisol, a naturally-occurring steroid hormone, has been shown to have a negative effect on bone density in humans. The same serum markers of bone loss and formation measured in this study already have proven useful for assessing bone status in humans with osteoporosis.

In the study of bears, results showed that ICTP and serum cortisol significantly increased during hibernation for all bears. However, PICP was not significantly different during the denning period than in the active period. Females who gave birth in the den showed relative increases in bone loss and larger decreases in bone formation than other bear groups, but the differences were not significant when compared with the other bear groups. PICP, the bone formation marker, was four- to fivefold higher in an adolescent and 17-year-old bear early in the active period compared with later in the summer months.

The data suggests that bears, like other animals, lose bone during extended periods of disuse. However, humans and other animals tend also to decrease bone formation during sedentary periods.

"These findings raise the possibility that hibernating black bears may minimize bone loss during disuse by maintaining the same level of bone formation as when they’re active," Seth Donahue said. Because bears do not urinate or defecate during hibernation, it is likely that the calcium freed in the body due to bone loss is reused in bone formation.

With the yearly hibernation period roughly equal to the active period, and with bone formation taking longer than bone loss, how do bears maintain bone long term?

"They may be able to make more rapid and complete recoveries during remobilization than other animals," Seth Donahue said. "The bone formation marker was four- to fivefold higher in early remobilization months in two female bears.

One possible mechanism for complete recovery is that bone cells in bears are more sensitive to mechanical stimulation and circulating hormone levels during remobilization and therefore rebuild bone faster." Because the researchers were limited as to when they could collect samples, it’s unclear whether all the bears experienced elevated bone formation in the period immediately following hibernation.

"These findings lend support to the hypothesis that black bears have the ability to minimize bone loss during disuse by maintaining bone formation and completely recover lost bone by increasing bone formation during remobilization," Henry J. Donahue said.



###
This work was supported by a National Institute of Aging, National Institutes of Health, grant (R01-AG13087) awarded to Henry J. Donahue, Ph.D. Other research team members were: Michael Vaughan, Ph.D., U.S. Geological Survey, Virginia Cooperative Fish and Wildlife Research Unit, Virginia Polytechnic Institute and State University; and Laurence M. Demers, Ph.D., Departments of Pathology and Medicine, Penn State College of Medicine, Penn State Hershey Medical Center.

Valerie Gliem | EurekAlert!
Further information:
http://www.psu.edu/

More articles from Life Sciences:

nachricht The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences

nachricht Transforming plant cells from generalists to specialists
07.12.2016 | Duke University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>