Low-carbohydrate diets have helped some people lose weight quickly, but the diets’ long-term effects on cardiovascular health have been uncertain.
Cardiologist Dr. Anthony Rosenzweig of Beth Israel Deaconess Medical Center and his colleagues tested three diets in mice genetically engineered for studying human heart disease. The mice were fed standard high-carb mouse chow, a typical Western diet with moderate amounts of carbs and protein, and a low carb-high protein diet.
After 12 weeks, mice on the low carb-high protein diet gained weight, but less than the other mice. There were no differences in cholesterol levels among the mice, but the mice on the low carb-high protein diet accumulated more plaque in their coronary arteries, called atherosclerosis, than mice on the other two diets. They also had lower levels of cells needed to repair and regrow new blood vessels, which the authors say may be linked to their arteries’ plaque buildup.
BOTTOM LINE: Mice fed a low-carbohydrate, high-protein diet accumulated more plaque in their coronary arteries and had fewer cells needed for healthy blood vessels than mice fed other diets.
CAUTIONS: Similar changes might not occur in humans.
WHAT’S NEXT: Better ways to detect cells that repair blood vessels will help assess how they might be affected by diet.
WHERE TO FIND IT: Proceedings of the National Academy of Sciences, Aug. 24
Could fruit odors keep away mosquitoes?
When humans exhale or when fruit ripens, they both emit carbon dioxide. Mosquitoes are attracted to the gas, using it to find blood to feed on, but fruit flies avoid it - in fact, they send out carbon dioxide when they are under stress as a warning to other flies. That’s where the fruit fly paradox comes in: How can insects that get their name from fruit get past a danger signal so they can eat it?In experiments testing how carbon dioxide receptors in fruit flies’ nerve cells responded to different chemicals, Anandasankar Ray and Stephanie Lynn Turner of the University of California-Riverside, discovered that ripening fruit sends out two odors that shut down those nerve cells, acting as antidotes to the fear carbon dioxide normally causes.
Ray, who was infected with malaria as a child in India, saw the potential value in blocking carbon dioxide receptors in mosquitoes. He and Turner tested the two odor-producing chemicals in culex mosquitoes, known for carrying West Nile virus. The two odors also shut down carbon dioxide receptors in the mosquitoes, suggesting that the compounds could mask the presence of humans and the carbon dioxide they breathe out.
Ray hopes that someday people could disperse the odor around them, rather than slathering insecticide on their skin, to keep away mosquitoes and their diseases.
BOTTOM LINE: Odors that block carbon dioxide-sensing nerve cells in fruit flies and mosquitoes could potentially become repellents to protect people from insect-borne diseases.
CAUTIONS: Identifying the odor-causing chemicals is only a preliminary step on the way to producing insect repellents for human use.
WHAT’S NEXT: Other insects that transmit diseases to humans can be studied to see if they might also be affected by an odor that blocks their attraction to humans.
WHERE TO FIND IT: Nature, online Aug. 26
ELIZABETH COONEY
