Type-2 insulin resistance studied

NEW HAVEN, Conn., -- Yale scientists say they've uncovered new clues about development of insulin resistance in type-2 diabetics and why such patients easily gain weight. Nearly all patients with type-2 diabetes -- the most frequently encountered metabolic disorder in the world, -- have insulin resistance, or IR. But how IR develops and why it leads to diabetes is not well understood. Yale scientists Kitt Petersen, Sylvie Dufour, and Gerald Shulman studied children of diabetic parents, some of whom are insulin-resistant, while they are still young and lean. They compared seven such individuals with lean, healthy, non-smoking control participants who were matched for age and weight. They found while insulin increases energy production in the muscles of the control participants by approximately 90 percent, it had very little effect in the insulin-resistant individuals. They also found in control individuals, insulin results in an increase of muscle cell phosphate, and that's also much reduced in insulin-resistant individuals. The researchers said the results provide more support for the idea that insulin resistance compromises proper functioning of energy generation in the mitochondria of muscle cells.
The study appears in the open access international medical journal PLoS Medicine.

Protein may increase risk of tumor

ST. LOUIS, -- A protein that protects the body from tissue damage also increases the risk of tumors, according to St. Louis researchers. Researchers of the Washington University School of Medicine say moderate reduction of the protein level protects against tumor formation but increases susceptibility to tissue injury. Because of its protective function in the body, the protein potentially could be used to selectively shield cells from toxic therapies, according to senior author Dr. Steven J. Weintraub, an investigator with the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital. "We earlier found that Bcl-xL helps the body's healthy cells survive the effects of toxic chemotherapeutic agents," says Weintraub. "This new study clearly demonstrates a tradeoff by showing that normal levels of Bcl-xL encourage the growth of tumors in mice exposed to a carcinogen." The study is published in Oncogene's advance online publication.