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

biophysics

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

Strength tests for platelets

Bleeding disorders could one day be diagnosed by putting platelets through strength tests, researchers have proposed.

Biomedical engineers from Emory and Georgia Tech have devised a microfluidic testing ground where platelets can demonstrate their strength by squeezing two protein dots together. Imagine rows and rows of strength testing machines from a carnival, but very tiny. Platelets are capable of exerting forces that are several times larger, in relation to their size, in comparison with muscle cells.

After a blood clot forms, it contracts, promoting wound closure and restoration of normal blood flow. This process can be deficient in a variety of blood clotting disorders. Previously, it was difficult to measure individual platelet’s contributions to contraction, because clots’ various components got in the way.

The prototype diagnostic tools are described in Nature Materials.

platelet_strength_test

Top: platelets exert their strength. Bottom left: red = platelets, green = fibrinogen dots. Bottom right: size of actual device.

“We discovered that platelets from some patients with bleeding disorders are ‘wimpier’ than platelets from healthy people,” says Wilbur Lam, MD, PhD, assistant professor in the Department of Pediatrics at Emory University School of Medicine and in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “Our device may function as a new physics-based method to test for bleeding disorders, complementary to current methods.”

The first author of the paper is instructor David Myers, PhD. Lam is also a physician in the Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta. Collaborators at North Carolina State University led by Ashley Brown, PhD, contributed to testing the device.

The scientists infer how strong or wimpy someone’s platelets are by measuring how far the protein dots move, taking a picture of the rows of dots, and then analyzing the picture on a computer. The dots are made of fibrinogen, a sticky protein that is the precursor for fibrin, which forms a mesh of insoluble strands in a blood clot.

In addition to detecting problems with platelet contraction in patients with known inherited disorders such as Wiskott Aldrich syndrome, Myers, Lam and colleagues could also see differences in some patients who had bleeding symptoms, but who performed normally on standard diagnostic tests. Read more

Posted on by Quinn Eastman in Heart, Uncategorized Leave a comment