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Research Briefs

Looking for a coffee break
Epidemiological studies have suggested that long-term caffeine consumption reduces the risk of developing type 2 diabetes. But a small study in Metabolism by Todd MacKenzie, Ph.D., and other Dartmouth investigators showed that if healthy young adults consume 200 milligrams of caffeine (about a mug of coffee) twice a day for a week, it reduces insulin sensitivity—and thus increases the risk for type 2 diabetes. Further research is needed "to study longer-term effects," the authors noted, "and to clarify the differences between interventional studies such as ours" and epidemiological studies.

Some skin in the game
Melanoma, which now accounts for 4% of all cancer cases, is on the rise worldwide. A team of DMS biochemists led by Constance Brinckerhoff, Ph.D., set out to explore the genetic underpinnings of metastatic melanoma, which is almost totally resistant to known therapies. In Cancer Research, they wrote that a gene called interstitial collagenase matrix metalloproteinase-1 (MMP-1), while not involved in primary tumor growth, "enhances tumor cell collegenase activity and tumor-induced angiogenesis," which are vital for the metastatic capability of melanoma cells. So "MMP-1 may be a therapeutic target in treating this disease."

A raft of results
Ta-Yuan Chang, Ph.D., reported in the Journal of Biochemistry that plasma membrane (PM) lipid rafts, cholesterol-rich areas of cell membranes, play a key role in cholesterol metabolism. Scientists knew that mammalian cells synthesize sterols, as well as cholesterol, in the endoplasmic reticulum (ER). Sterols move to the PM, then back to the ER, for processing to cholesterol. But no one understood how. Chang's lab determined that rafts complete cholesterol biosynthesis "by participating in the retrogrademovement of precursor sterols back to the ER."

Coverage for veterans
Medicare data helps VA planners analyze older veterans' use of health-care services, but it's harder to determine where younger VA enrollees get their care or how it's funded. A DMS team used three hospitalization datasets to compare payers for younger and older enrollees and found that most younger vets use private insurance more often than the VA or other coverage. "Veterans of the current Middle East conflict are likely to need extensive care, which will challenge the VA system," the team wrote in Medical Care. "Understanding younger veterans' health-care needs, service utilization, and payment options may require synthesizing data from multiple sources."

A hearty endorsement
A DMS team led by cardiologist Michael Simons, M.D., has genetically engineered adult mice to grow new blood vessels around their hearts.Within three weeks, the animals' vasculature had grown 50% percent, and by six weeks their hearts were 50% larger. "This study demonstrates that an increase in the size of the vascular bed in the normal heart leads to increased cardiac mass and myocardial hypertrophy paralleled by increased cardiac performance," the researchers wrote in the Journal of Clinical Investigation. The findings may lead to new approaches for treating heart disease.

Looking to stem leukemia
A blood formation gene called mixed lineage leukemia (MLL)—which is essential for the development of embryonic blood stem cells and is involved in a type of childhood leukemia—also plays an unexpected role in the adult blood-forming system, according to a recent study in Cell Stem Cell. DMS geneticist Patricia Ernst, Ph.D, and colleagues found that in mice, MLL acts on bone marrow stem cells and controls key aspects of their growth to generate mature blood cells. If it's disrupted, it cannot work properly and leukemia can ensue. The researchers hope that their discovery may one day lead to new anticancer treatments.

A Dartmouth study found that functional MRIs of patients with obsessive-compulsive disorder and of a control group show different patterns of brain activity during response inhibition tasks.

Teens shown evidence of skin damage from sun exposure, found DMS's Ardis Olson, M.D., were more likely than a control group (59% versus 35%) to say they'd use sunscreen in the future.

DMS's James Sargent, M.D., recently showed that exposure to smoking in movies is more likely not only to make teens take up smoking but also to make them established smokers

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