The study, published online in the journal Radiology, found that obese people with higher levels of fat in their liver, muscle tissue and blood also have higher amounts of fat in their bone marrow, putting them at risk for osteoporosis.
"Obesity was once thought to be protective against bone loss," said study lead author Miriam A. Bredella, M.D., a radiologist at Massachusetts General Hospital and associate professor of radiology at Harvard Medical School in Boston. "We have found that this is not true."
While other studies have examined the relationship between visceral fat and bone mineral density, this study looked at fat inside bone marrow, the spongy tissue inside the bones of the body that produces stem cells.
"In our study, we focused on bone marrow fat because that is where our stem cells can develop into osteoblasts—the cells responsible for bone formation—or fat cells," Dr. Bredella said. "We also wanted to look at the relationship between bone marrow fat and other fat components, such as those in the liver and muscle."
Dr. Bredella and colleagues used proton magnetic resonance spectroscopy (MRS), a technique that allows for precise measurement of fat, to examine 106 men and women, ages 19 to 45 years, who were obese based on body mass index measurements, but otherwise healthy.
"MRS has no radiation, is quick to perform and can quantify the amount of fat within bone marrow, muscle and liver," Dr. Bredella said.
The MRS results showed that people with more liver and muscle fat had higher levels of fat in their bone marrow, independent of body mass index, age and exercise status. HDL cholesterol, the "good" type of cholesterol that is associated with a lower risk of heart disease, was inversely associated with bone marrow fat content.
Higher levels of bone marrow fat put people at increased risk of fracture, according to Dr. Bredella.
"Bone marrow fat makes bones weak," she said. "If you have a spine that's filled with fat, it's not going to be as strong."
Triglycerides, the type of fat found in the blood, also had a positive correlation with bone marrow fat, possibly because they stimulate osteoclasts, a type of cell that breaks up bone tissue.
More research is needed to further illuminate the mechanism behind this differentiation of stem cells. Dr. Bredella noted that cell-signaling molecules called cytokines are known to promote the conversion of stem cells into fat.
"Obesity can shift stem cell lineage, resulting in more bone marrow fat," she said.
"Ectopic and Serum Lipid levels Are Positively Associated with Bone Marrow Fat in Obesity." Collaborating with Dr. Bredella were Corey M. Gill, B.S., Anu V. Gerweck, N.P., Melissa G. Landa, B.A., Vidhya Kumar, M.A., Scott M. Daley, B.A., Martin Torriani, M.D., Karen K. Miller, M.D.
Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc.
RSNA is an association of more than 51,000 radiologists, radiation oncologists, medical physicists and related scientists promoting excellence in patient care and health care delivery through education, research and technologic innovation. The Society is based in Oak Brook, Ill. (RSNA.org)
For patient-friendly information on medical imaging, visit RadiologyInfo.org.
Linda Brooks | EurekAlert!
Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn
New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
27.04.2017 | Information Technology
26.04.2017 | Materials Sciences
26.04.2017 | Agricultural and Forestry Science