The growth of fat cells and their metabolism depend on oxygen and blood-borne nutrients. A possible way to regulate the amount of body fat - in order, for instance, to combat obesity - can therefore be to affect the development of blood vessels in the adipose tissue.

A team of researchers at Karolinska Institutet have now demonstrated the rapid development of blood vessels in the adipose tissue of mice exposed to low temperatures. This is followed in its turn by a transformation of the adipose tissue from 'white' fat to 'brown' fat, which has higher metabolic activity and which breaks down more quickly.

"This is the first time it's been shown that blood vessel growth affects the metabolic activity of adipose tissue rather than vice versa," says Professor Yihai Cao, who led the study. "If we can learn how to regulate the development of blood vessels in humans, we'd open up new therapeutic avenues for obesity and metabolic diseases like diabetes."

Brown fat releases heat when it breaks down, and is mainly found in hibernating animals. In humans, it is found in newborn babies, but scientists believe by controlling blood vessel development that it might be possible to transform white fat to brown fat in adults as well.

Publication: "Cold triggers VEGF-dependent but hypoxia-independent angiogenesis in adipose tissues and anti-VEGF agents modulate adipose tissue metabolism", Yuan Xue, Natasa Petrovic, Renhai Cao, Ola Larsson, Sharon Lim, Shaohua Chen, Helena M Feldmann, Zicai Liang, Zhengping Zhu, Jan Nedergaard, Barbara Cannon, Yihai Cao, Cell Metabolism, 6 January 2009.

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"Health care transition is a complex set of tasks that are embedded within a complex developmental period and a complex heath care system," the authors note. "It is not surprising, then, than the development and evaluation of services to facilitate health care transition has been slow." However, a systematic approach to this problem can show results.

In the UK, for example, the British Society of Paediatric and Adolescent Rheumatology has developed a comprehensive health care transition program for youth with arthritis that appears to have a positive impact.

In the U.S., there seems to be much room for improvement is assisting adolescents with arthritis in achieving a successful health care transition into adulthood. "More research is needed to understand youth's perspectives regarding their health care transition needs that should include items related specifically to health care transition, as well as how health care transition needs intersect with social, educational, and vocational concerns," the authors conclude.

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