IN THIS ISSUE .
August 20, 2008
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When we walk, muscles and nerves interact in intricate ways to let us take a step. This simulation, based on movement data from a 6-foot-tall man and generated using computational modeling, shows what happens. Red indicates that a muscle has received a signal from the nervous system to contract, and blue shows that the muscle is relaxed and receiving no signal. The simulation and the software behind it one day could aid athletic coaches and doctors in understanding how injuries that disrupt motor signals can cause movement disorders. Courtesy of computational biomechanists Chand John and Eran Guendelman, Stanford University.
The NIH Roadmap for Medical Research supports this work.
About 4,000 children in the United States die each year from septic shock, which results from uncontrolled infection. As the infection spirals out of control, the immune system secretes the protein IL-8 to serve as a signal for the recruitment of more infection-fighting cells. Pediatric critical care specialist Hector Wong at Cincinnati Children's Hospital Medical Center has now found that blood levels of IL-8 can be used to predict survival of children with septic shock. By using IL-8 levels as a diagnostic tool, doctors may be able to screen patients to guide treatment and the development of new therapies.
Many animal species prefer living in a limited range of temperatures and can detect subtle changes within that range. Biologist Craig Montell and collaborators at Johns Hopkins School of Medicine have found that fruit fly larvae use a protein called the TRPA1 channel to detect single degree changes within their comfort range of 64 to 75 degrees Fahrenheit. TRPA1 seems to work by amplifying the physiological effect of small changes, allowing larvae to sense and adapt to slightly different temperatures. Montell's work also raises the possibility that a similar process may exist in mammals, enabling them to notice small changes in internal temperature.
NIH's National Eye Institute also supported this work.
Montell home page (no longer available)
Article abstract (from the July 27 online issue of Nature Neuroscience)
A system of biological clocks, called circadian rhythms, keeps our bodies ticking. Disrupting these rhythms can lead to serious health problems, including obesity and cancer. Scientists know that an essential component of the circadian machinery is the protein CLOCK. Paolo Sassone-Corsi and his colleagues at the University of California, Irvine, now have found that CLOCK is counterbalanced by a metabolic protein called SIRT1, which senses how much energy cells use. The research suggests that proper sleep and diet may help maintain the equilibrium of these two proteins and could explain why lack of sleep has been shown to increase hunger.
The enzyme lactase allows mammals to digest milk, but it's usually shut down after weaning. University of Pennsylvania geneticist Sarah Tishkoff is tracing the genetic mutation that allows adult humans to continue processing milk. Her research on lactose tolerance led her to Africa, where she has worked with more than 40 different ethnic groups. Tishkoff found that the emergence of domesticating cattle occurred around the same time that a mutation allowing for the persistence of lactase arose. This co-evolution allowed dairying cultures to digest milk and gave them a selective advantage.