Overcoming cardiac pacemaker "source-sink mismatch"

Instead of complication-prone electronic cardiac pacemakers, biomedical engineers at Georgia Tech and Emory envision the creation of “biological Read more

Hope Clinic part of push to optimize HIV vaccine components

Ten years ago, the results of the RV144 trial– conducted in Thailand with the help of the US Army -- re-energized the HIV vaccine field, which had been down in the Read more

Invasive cancer cells marked by distinctive mutations

What does it take to be a leader – of cancer cells? Adam Marcus and colleagues at Winship Cancer Institute are back, with an analysis of mutations that drive metastatic behavior among groups of lung cancer cells. The findings were published this week on the cover of Journal of Cell Science, and suggest pharmacological strategies to intervene against or prevent metastasis. Marcus and former graduate student Jessica Konen previously developed a technique for selectively labeling “leader” Read more

Department of Rehabilitation Medicine

A new term in biophysics: force/time = “yank”

Biologists and biomedical engineers are proposing to define the term “yank” for changes in force over time, something that our muscles cause and nerves can sense and respond to. Their ideas were published on September 12 in Journal of Experimental Biology.

Expressed mathematically, acceleration is the derivative of speed or velocity with respect to time. The term for the time derivative of acceleration is “jerk,” and additional time derivatives after jerk are called “snap,” “crackle” and “pop.”

The corresponding term for force – in physics, force is measured in units of mass times acceleration – has never been defined, the researchers say.

Scientists that study sports often use the term “rate of force development”, a measure of explosive strength. Scientists who study gait and balance — in animals and humans — also often analyze how quickly forces on the body change. It could be useful in understanding spasticity, a common neuromuscular reflex impairment in multiple sclerosis, spinal cord injury, stroke and cerebral palsy.

“Understanding how reflexes and sensory signals from the muscles are affected by neurological disorders is how we ended up needing to define the rate change in force,” says Lena Ting, PhD, professor of rehabilitation medicine at Emory University School of Medicine and the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Hypoxia is bad, except when it’s good

Randy Trumbower and his colleagues in Emory’s Department of Rehabilitation Medicine recently published a study showing that “daily intermittent hypoxia,” combined with walking exercise, can help patients with incomplete spinal cord injury walk for longer times. What is it about being deprived of oxygen for short periods that has a positive effect?

This research was puzzling at first (at least to your correspondent) because “daily intermittent hypoxia” is a good description of the gasping and snorting interruptions of sleep apnea.

Sleep apnea is a very common condition that increases the risk of high blood pressure, diabetes, heart attack and stroke. On the other side of the coin, many endurance athletes have been harnessing the body’s ability to adapt to low oxygen levels — so-called altitude training — to increase their performance for years.

So we have an apparent clash: hypoxia is bad, except when it’s good. Looking closely, there are some critical differences between sleep apnea and therapeutic hypoxia. The dose makes the poison, right? Read more

Posted on by Quinn Eastman in Neuro Leave a comment