Deirdre Budd’s Blog

Archive for June 2010

The body’s primary circadian clock resides deep in the brain, but local biological clocks also are found in tissues throughout the body, including the pancreas, lungs, liver, heart and skeletal muscles. These clocks operate on a 24-hour, circadian (Latin for “about a day”) cycle that governs functions such as sleeping and waking, rest and activity, fluid balance, body temperature, cardiac output, oxygen consumption, metabolism and endocrine gland secretion.

As part of this system, our fundamental body systems such as sleep wake cycles and when we feel hunger are also regulated. Recent research, led by Bass and Biliana Marcheva,  first author of the paper, involving key collaborators Louis H. Philipson of the University of Chicago, Joseph S. Takahashi of the University of Texas Southwestern Medical Center and Seth D. Crosby of the Washington University School of Medicine. Looked at the development of diabetes and the links between insulin production and the circadian rhythm.

In their study, the researchers knocked out the clock genes in islet beta-cells in mice, and found the animals developed impaired glucose tolerance, and abnormally low levels of insulin. They went on to develop diabetes. The clock of the beta-cell coordinates glucose management, and the loss of the clock inhibited the cells from secreting insulin.

These findings will help in working out the causes of glucose abnormalities, but there is still a lot to learn. The researchers showed that insulin-secreting islet cells in the pancreas, called beta-cells, have their own dedicated clock. The clock governs the rhythmic behavior of proteins and genes involved in insulin secretion, with oscillations over a 24-hour cycle. “This is the first evidence of how the circadian clock may affect the development of diabetes,” said Joe Bass, M.D. “The biological programs in animals for harvesting energy, are under control of this clock.”

 “The variation we see in insulin secretion in humans, and susceptibility to diabetes, is likely related to this clock mechanism,” said Bass, an endocrinologist trained in molecular genetics. “There is an association in the changes of the cycling of the clock within the pancreas itself and disease. The question is, can we can modulate this?”

Diabetes is the seventh most common cause of death in America and costs every country a huge amount in health care and disablilty. Anything which can reduce the impact or the number of people who suffer from the effects of diabetes should be welcomed.

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Doctors from the University of Auckland, New Zealand, recently did a randomised control trial of positioning treatments for infants with plagiocephaly and brachycepahly. In this study head shape was measured digitally and neck function was assessed. Children were followed up at 3,6 nad 12 months. One group were treated using positional strategies and one with positioning strategies and a SafeT sleep.  The results of this study showed  that there was no difference in head shape outcomes for the two treatment groups after 12 months of follow up, with 42% of infants having head shapes in the normal range by that time. Eighty percent of children showed good improvement. Those that had poor improvement were more likely to have both plagiocephaly and brachycephaly and to have presented later to clinic.

 Most infants improved over the 12-month study period, although the use of a sleep positioning wrap did not increase the rate of improvement.