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Archive - 07 - 2014

UT Southwestern Researchers Uncover New Brain Pathways for Understanding Type 2 Diabetes and Obesity

Posted by dlife on Mon, Jul 28, 14, 11:59 AM 0 Comment

July 28, 2014 (Newswise) - Researchers at UT Southwestern Medical Center have identified neural pathways that increase understanding of how the brain regulates body weight, energy expenditure, and blood glucose levels – a discovery that can lead to new therapies for treating Type 2 diabetes and obesity. The study, published in Nature Neuroscience, found that melanocortin 4 receptors (MC4Rs) expressed by neurons that control the autonomic nervous system are key in regulating glucose metabolism and energy expenditure, said senior author Dr. Joel Elmquist, Director of the Division of Hypothalamic Research, and Professor of Internal Medicine, Pharmacology, and Psychiatry. "A number of previous studies have demonstrated that MC4Rs are key regulators of energy expenditure and glucose homeostasis, but the key neurons required to regulate these responses were unclear," said Dr. Elmquist, who holds the Carl H. Westcott Distinguished Chair in Medical Research, and the Maclin Family Distinguished Professorship in Medical Science, in Honor of Dr. Roy A. Brinkley. "In the current study, we found that expression of these receptors by neurons that control the sympathetic nervous system, seem to be key regulators of metabolism. In particular, these cells regulate blood glucose levels and the ability of white fat to become ‘brown or beige' fat." Using mouse models, the team of researchers, including co-first authors Dr. Eric Berglund, Assistant Professor in the Advanced Imaging Research Center and Pharmacology, and Dr. Tiemin Liu, a postdoctoral research fellow in Internal Medicine, deleted MC4Rs in neurons controlling the sympathetic nervous system. This manipulation lowered energy expenditure and subsequently caused obesity and diabetes in the mice. The finding demonstrates that MC4Rs are required to regulate glucose metabolism, energy expenditure, and body weight, including thermogenic responses to diet and exposure to cold. Understanding this pathway in greater detail may be a key to identifying the exact processes in which type 2 diabetes and obesity are developed independently of each other. In 2006, Dr. Elmquist collaborated with Dr. Brad Lowell and his team at Harvard Medical School to discover that MC4Rs in other brain regions control food intake but not energy expenditure. The American Diabetes Association lists Type 2 diabetes as the most common form of diabetes. The disease is characterized by high blood glucose levels caused by the body's lack of insulin or inability to use insulin efficiently, and obesity is one of the most common causes. Future studies by Dr. Elmquist's team will examine how melanocortin receptors may lead to the "beiging" of white adipose tissue, a process that converts white adipose to energy-burning brown adipose tissue.

Unhealthy Habits More Than Double Risk of Metabolic Syndrome in Childhood Cancer Survivors

Posted by dlife on Mon, Jul 28, 14, 11:54 AM 0 Comment

July 28, 2014 (Newswise) - A St. Jude Children's Research Hospital study found that 73 percent of adult survivors of childhood cancer more than doubled their risk of developing metabolic syndrome and related health problems by failing to follow a heart-healthy lifestyle. The results appear in the current issue of the journal Cancer. Almost 32 percent of the 1,598 adult survivors of childhood cancer in the study had metabolic syndrome, an umbrella term for health risk factors like high blood pressure, abdominal obesity, elevated triglyceride and other abnormalities that often occur together. The prevalence was similar to rates reported for much older adults in the general public. Metabolic syndrome is associated with greater odds of developing heart disease, diabetes, stroke and other potentially fatal health problems. Researchers reported that adult survivors of childhood cancer who failed to adopt a lifestyle that included regular exercise and a healthy diet were more than twice as likely to develop metabolic syndrome as survivors who did. The risk was 2.4 times higher in women and 2.2 times greater in men. Lifestyle had a greater impact on the likelihood of developing metabolic syndrome than risk factors associated with childhood cancer treatment, including cranial irradiation. "This is good news for the nation's growing population of adult survivors of childhood cancer," said corresponding author Kirsten Ness, Ph.D., an associate member of the St. Jude Department of Epidemiology and Cancer Control. "This suggests that if you maintain a healthy lifestyle by staying active and eating a diet that is low in fat, sugar and salt and rich in fruit and vegetables you should be able to influence whether or not you develop metabolic syndrome." The United States is home to more than 360,000 childhood cancer survivors. With childhood cancer survival rates now better than 80 percent, the survivor population is expected to grow. Previous research from St. Jude and others found that many survivors face significant challenges, including chronic health problems, and may be at risk for premature aging. Survivors whose cancer treatment included chest and cranial irradiation or chemotherapy with anthracylcine are known to be at an increased risk for cardiomyopathy or metabolic syndrome. A previous St. Jude-led study found that lifestyle and risk factors related to cancer treatment were a particularly toxic mix for aging childhood cancer survivors. This study was the largest yet to evaluate how lifestyle impacts the risk of metabolic syndrome in a diverse group of pediatric cancer survivors. The participants were enrolled in the St. Jude Lifetime Cohort Study (St. Jude LIFE), which brings childhood cancer survivors treated at St. Jude back to the hospital for several days of health screenings and other tests. Participants are at least 18 years old and 10 years from their diagnosis. Survivors in this study ranged in age from 19 to 60 years old. Half were less than 33 years old. Previous studies of metabolic syndrome in pediatric cancer survivors focused primarily on survivors of acute lymphoblastic leukemia (ALL), but this study included survivors of various cancers, including lymphoma, sarcoma, neuroblastoma, brain and other tumors. The prevalence of metabolic syndrome among survivors, 22 percent of whom were older than age 40, was 31.5 percent. That was greater than rates reported in small studies of young pediatric cancer survivors, but comparable to the 34 percent reported in the general population, 68 percent of whom were older than 40. Health screenings and survivor self-reports found that 27 percent of study participants met at least four of seven requirements for a healthy lifestyle as defined by the World Cancer Research Fund/American Institute for Cancer Research. The list included maintaining a healthy weight, moderate intake of alcohol and red meat, being physically active and eating a diet low in sodium and high in complex carbohydrates, fruits and vegetables. About two-thirds of survivors in this study were overweight or obese, three-quarters reported eating less than five servings of fruits and vegetables daily and more than half reported inadequate exercise or complex carbohydrates. In addition, 90 percent reported eating too much red meat and nearly 70 percent too much sodium. Healthier habits are proven to reduce the risk of metabolic syndrome in the general public. St. Jude is planning interventions to determine if the same is true for childhood cancer survivors and to help survivors of all ages make changes to benefit their long-term health.

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