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Collaborations of the Heart:Cardiology Research
research briefs
Think you know what the skeleton does?
A new study led by Gerard Karsenty, M.D., Ph.D., chairman of genetics and development, and Patricia Ducy, Ph.D., assistant professor of pathology, shows that bones have a surprising metabolic role, regulating blood glucose levels and fat deposition.
Bone cells accomplish this role, the researchers found, by releasing a hormone called osteocalcin into the bloodstream. Osteocalcin acts on several types of cells to increase insulin production, improve insulin sensitivity, increase the number of insulin-producing cells, and reduce fat stores.
”These previously unknown tasks of the skeleton could lead to new treatments for diabetes and obesity, but the research also demonstrates that many functions of our major organs are still unknown,” Dr. Karsenty says.
This work was supported in part, by the NIH and The American Diabetes Association.
Cell 130(3): 456-469
Exercise Paradox SolvedGym enthusiasts may be appalled to learn that exercise increases the amount of fat stored in their muscles, just as overeating increases fat in the muscles of more sedentary folk. Paradoxically, the fat in exercisers’ muscles has no ill effects, unlike the fat stored in muscles of sedentary people, which is associated with insulin resistance and diabetes.
A new study by Yi-Hao Yu, M.D., assistant professor of medicine in the Division of Preventive Medicine and Nutrition, explains this “exercise paradox.”
The difference between the athlete and the couch potato lies not in the fat, Dr. Yu and colleagues found, but in certain fatty acid metabolites (such as diacylglycerol and ceramide) also present in muscle. In sedentary animals, levels of the two go hand in hand: fatty acid metabolites increase as the amount of stored fat increases.
During exercise, fat storage also increases, but depletes the supply of metabolites. That suggests the real culprit behind insulin resistance in muscle is not the fat, but the large amount of harmful fatty acid metabolites.
Dr. Yu and colleagues confirmed this hypothesis in genetically engineered mice. By turning up the activity of a fat synthesis enzyme, Dr Yu created mice that stored lots of fat, but few fatty acid metabolites. Despite the fat stores, the mice remained insulin-sensitive without exercise.
The same enzyme that increased in mice – diacylglycerol acyltransferase-1 (DGAT1) – also seems to improve insulin-sensitivity in humans, according to a paper by University of Michigan researchers.
“The two studies suggest that a drug that can increase DGAT activity in muscle may offer an important benefit of exercise and provide a new way to treat insulin resistance and diabetes,” Dr. Yu says.
The research was supported by the NIH. Journal of Clinical Investigation 117(6): 1679-1689.
Illegal Cigarette Sales Undermine Effort to Reduce Smoking
Cigarette taxes imposed by the city and state in 2002 sharply increased the price of cigarettes in stores, but the easy availability of cheap, illegal packs in the city’s poorer neighborhoods has undermined the public health goals of the tax increase, according to a study from Mailman School of Public Health researchers.
The researchers interviewed 104 adult residents of Harlem and found that because bootleggers are so prevalent, smokers have little incentive to stop smoking. Only one smoker among the study participants attempted to quit because of the tax increase.
Because poor smokers are more price sensitive than affluent smokers, supporters of the tax believed that the price increase would cause many to reduce consumption or quit.
“Our research demonstrates a fault line in this argument,” says the study’s lead author, Donna Shelley, M.D., M.P.H., assistant professor of clinical sociomedical sciences. “Even smokers motivated to quit were lured by bootleggers selling low-price cigarettes.”
Though the tax was associated with an overall decline in smoking prevalence among the general population in New York City, the researchers say more awareness about free cessation services provided by the state and city is still needed in many neighborhoods. Only a handful of Harlem residents they interviewed knew about such programs.
The study was supported by the CDC and The American Legacy Foundation. Am J Public Health 97(8): 1-6.
¿Como se dice ‘wheeze’ en Español?
Asthma specialists in the Department of Medicine have found that local Spanish speakers do not have a single word for the English “wheeze,” possibly confounding asthma research in Spanish-speaking populations.
Medical histories taken by clinicians and written questionnaires used by researchers to identify asthma cases and quantify symptoms rely heavily on the word “wheeze.” These questionnaires are usually validated among English speakers and then translated into Spanish.
Rachel Miller, M.D., assistant professor of clinical medicine and public health, and Rafael Narvaez, Ph.D., project coordinator, asked two accredited translators, both experienced with medical translation and the Washington Heights Dominican population, to translate wheeze into Spanish. Both picked the word ”ronquido.”
But when the researchers asked about 40 local bilingual residents the same question, they got 12 different answers (including words for tight chest, whistle in the chest, congested breathing, hoarseness, asphyxiation, asthma, snoring and suffocation). Only two picked ”ronquido” and about a quarter couldn’t identify a single word at all.
“Ronquido” fared even worse among bilingual residents whose primary language is Spanish.
“‘Wheeze’ is a very ambiguous word even in English and it is difficult to translate into Spanish,” Dr. Narvaez says. “In the future, asthma researchers need to go out into the community to find the best word for ‘wheeze’ in their research population before distributing questionnaires.”
The research was funded by the NIH. Chest 131(4): 1271-1272
