Presence in Adults
It was believed that after infants grow up, most of the mitochondria (which are responsible for the brown color) in brown adipose tissue disappear, and the tissue becomes similar in function and appearance to white fat. However, more recent research has shown that brown fat is related not to white fat, but to skeletal muscle.
Further, recent studies using Positron Emission Tomography scanning of adult humans have shown that it is still present in adults in the upper chest and neck. The remaining deposits become more visible (increasing tracer uptake, that is, more metabolically active) with cold exposure, and less visible if an adrenergic beta blocker is given before the scan. The recent study could lead to a new method of weight loss, since brown fat takes calories from normal fat and burns it. Scientists were able to stimulate brown fat growth in mice, but human trials have not yet begun.
In rare cases, brown fat continues to grow, rather than involuting; this leads to a tumour known as a hibernoma.
Read more about this topic: Brown Adipose Tissue
Famous quotes containing the words presence in, presence and/or adults:
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—Henry Brooks Adams (1838–1918)
“Human life is thus only a perpetual illusion; men deceive and flatter each other. No one speaks of us in our presence as he does of us in our absence. Human society is founded on mutual deceit; few friendships would endure if each knew what his friend said of him in his absence, although he then spoke in sincerity and without passion.”
—Blaise Pascal (1623–1662)
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—Zick Rubin (20th century)