SHIVERING TRIGGERS BROWN FAT TO PRODUCE HEAT AND BURN CALORIES
From FMS Global News Desk of Jeanne Hambleton February 24, 2014 NIH Research Matters National Institute of Health-Cell Metabolism.
Shivering, like exercise, triggers muscles to secrete a hormone that stimulates energy use in brown fat cells. The findings hint at new ways to alter the body’s energy balance and treat conditions such as obesity.
During exercise, contracting skeletal muscles release the hormone irisin into circulation. Irisin can induce energy-storing white fat cells to take on characteristics of brown fat (or adipose) cells, which burn energy by generating heat. This muscle-fat crosstalk has intrigued scientists because it is unclear why muscle tissue, which generates heat when active, would also stimulate fat cells to produce heat.
A team led by Dr. Francesco S. Celi, who is now at the Virginia Commonwealth University School of Medicine, wondered whether cold exposure could also trigger irisin secretion in order to prompt the body to produce heat. The study was conducted at NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), where Celi was staff clinician.
The researchers had 10 people (4 females, average age 27 years) ride a stationary bike. During a brief ride to maximal capacity, irisin levels tended to increase. During a 1-hour ride at an easier level, irisin levels rose about 3-fold, confirming the ability of exercise to increase irisin secretion in humans.
The team next looked at the impact of cold exposure on irisin levels. The participants rested in water-infused thermoblankets that were gradually cooled from 80 to 53°F. The participants’ energy expenditure increased 48%. While their core temperature was maintained, their skin temperature dropped. Measurement of muscle activity via electromyography showed an 88% increase in the 7 participants who shivered and a 13% increase in those who didn’t. Irisin secretion increased proportionally to shivering intensity. The increase was similar in magnitude to the exercise-stimulated secretion.
The team also found that the secretion of fibroblast growth factor 21 (FGF21), a hormone associated with brown fat activation, was affected by exposure to cold.
The researchers next tested human fat cells taken from biopsies of the neck area. This region is rich in “brown-like” or beige cells, which develop within white fat. Treatment with a chemical precursor of irisin and/or FGF21 caused the cells to burn energy, release heat, and adopt molecular characteristics of brown fat cells. These changes were not noted in fat cells taken from other regions of the body that tend to be rich in white fat.
“Cold-induced shivering, which is an energy-inefficient mechanism, stimulates the highly efficient brown adipose tissue to maintain the core temperature of the organism,” Celi says.
“From an evolutionary standpoint, this system assures the most efficient means of maintaining core temperature and minimizing the loss of energy stores compared to shivering alone.”
Although this was a small clinical study, the findings suggest that exercise-induced irisin secretion could have evolved from shivering-related muscle contraction. The results also suggest that since activation of these pathways results in greater energy expenditure, the pathways may serve as potential therapeutic targets for obesity and related conditions.—by Carol Torgan, Ph.D.
A WAY TO BURN MORE CALORIES?
From the FMS Global News Desk of Jeanne Hambleton July 18, 2011 NIH Research Matters National Institute of Health
Scientists have uncovered a pathway in mice that allows white fat—a contributor to obesity and type 2 diabetes—to burn calories as if it were brown fat or muscle.
The body uses white fat to store extra energy. Too much white fat (obesity) increases the risk of type 2 diabetes and other diseases. Brown fat, in contrast, generates heat to maintain body temperature and, like muscle, has lots of calorie-burning mitochondria.
Brown fat is found in small mammals like rodents throughout their lives. Humans have it at birth, but we lose it as we age. Researchers once thought that our brown fat was essentially nonexistent by adulthood. Recent studies found that not only do adults have brown fat but it also may play an important role in weight control. Boosting the activity of brown fat, or converting white fat to brown fat, could be potential strategies for fighting obesity.
A team of NIH researchers led by Dr. Sushil G. Rane of NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) were studying a protein called TGF-beta. TGF-beta and its related factors are known to control the development, growth and function of many different cell types. Blood levels of TGF-beta have been linked to obesity in both mice and humans. In previous work, the team found that the TGF-beta pathway plays an important role in regulating insulin genes. To further investigate, the researchers studied mice deficient in the protein Smad3, which regulates gene expression in response to TGF-beta signals.
The researchers reported in the July 6, 2011, edition of Cell Metabolism that Smad3-deficient mice developed significantly less fat mass. The mice also had enhanced glucose uptake in their white fat. This observation prompted the scientists to examine the mice’s white fat more closely. They discovered that, without the influence of TGF-beta, the white fat became browner with more mitochondria. The increased metabolic activity due to the mitochondria burned more calories, lessening obesity.
To test whether blocking TGF-beta might help combat obesity, the scientists tested an antibody that neutralizes TGF-beta. The antibody suppressed fat formation and weight gain in 2 well-characterized mouse models of obesity. Similar to the Smad3-deficient mice, the antibody-treated mice showed an increase in mitochondrial activity.
“We were not looking to have white fat acquire the properties of brown fat, but that is what we found, with the fat getting browner from increased mitochondria and displaying genes typically expressed in muscle. It was a striking difference,” Rane says.
These findings suggest a potential new approach to treating obesity and type 2 diabetes. However, this research is a long way from being applicable to people. A TGF-beta blocking antibody is currently being tested as a cancer treatment in a clinical trial at NIH’s National Cancer Institute (NCI). Due to the potential side effects of the antibody, it has not yet been tested for treatment of human obesity. The researchers are working to design a more targeted approach to transform the white fat of mice into a brown fat or muscle-like state.
“Efforts to reduce obesity by dieting are mostly unsuccessful in the long term, so finding ways to prevent excess fat storage is an urgent medical need,” Rane says.
“Our discovery that white fat can be reduced by partially transforming it to brown fat and muscle opens up new avenues to combat the obesity epidemic.”
IMPROVE DRIVING SKILLS NOW BEFORE THE SNOW FLIES
Save Money on Insurance With Driving Course Completion
From FMS Global News Desk of Jeanne Hambleton Released: 18-Aug-2014
Source: Loyola University Health System
Newswise — This last winter was extreme and put many drivers’ skills to the test. Now many seniors can take a driving refresher course that can increase their driving skills and also lower their insurance rates before the snow flies.
“Driving is a privilege that most adults value the most and view as key to their independence,” said Janette Johns, activity director, Transitional Care Unit, Gottlieb Memorial Hospital.
“Being a safe and competent driver not only safeguards the privilege of driving, but makes the roads safer for everyone.”
Gottlieb Memorial Hospital is just one of dozens of organizations to partner with the AARP to offer a two day driving course.
The cost is $15 for AARP members and $20 for nonmembers. The eight-hour course is taught in two consecutive four-hour sessions. To receive the completion certificate that potentially entitles the participant to an insurance discount, class must be attended both days.
Did You Know?
According to the National Highway Traffic Safety Administration (NHTSA), 35 percent of traffic violations for drivers older than age 55 are for a failure to yield the proper right of way.
Your hands should be placed in the 8 and 4 o’clock or 9 and 3 o’clock position on the steering wheel.
Vision starts to change at age 40 in ways that affect driving.
While driving, there should be 10 to 12 inches between your chest and the steering wheel.
You should remain three seconds or more behind the car you are following.
To earn an AARP course completion discount in Illinois, drivers have to be 55 to be eligible and it is up to the insurance company to determine the amount.
In 2013, 15,225 drivers participated in the course, which is offered in English and Spanish, throughout the U.S.
Approximately 80 percent of AARP course graduates report that taking the course has resulted in a positive change in their driving behavior.
Back home in the UK it might be worth looking at the Green Flag website http://www.greenflag.com/help/drivingguide-older-drivers.html
This makes sense and might be worth considering. The Green Flag site suggests: Drivers aged 70 or over were only involved in 10,465 out of the 212,685 reported accidents in Great Britain in 2010, according to Department for Transport statistics. The group with the most accidents was 40 to 49-year-olds. (Glad I am not one of those – so life begins at 50 if you are a driver).
Talking about driving if you need your spirits lifting you should spare five minutes to watch this video to the end. I had tears running down my cheeks with laughter. I do understand the frustration of the drivers. ENJOY. There is no catch – it is just a bit of fun. Share it if you enjoyed it. Back tomorrow Jeanne