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July 11, 2013

Research Notes

Better gait measures may improve movement

Older adults diagnosed with brain disorders such as Parkinson’s disease often feel a loss of independence because of their lack of mobility and difficulty walking. To better understand and improve these mobility issues — and detect them sooner — a research team from the Swanson School of Engineering, the School of Health and Rehabilitation Sciences (SHRS) and the School of Medicine is working toward building a more advanced motion test that addresses a wider range of walking patterns and movements.

The team proposed a mathematical model that can examine multiple walking, or gait-related, features. Previous studies typically have measured only one or two types of movement features in just one population.

Said lead author Ervin Sejdic of the Swanson school: “You can tell whether an older individual has difficulties walking by conducting a simple gait test. But can we quantify these changes and document them earlier?”

Thirty-five adults older than 65 were studied, including 14 healthy participants, 10 individuals with Parkinson’s disease, and 11 adults who had impaired feeling in their legs due to nerve damage. Walking trials were performed using a computer-controlled treadmill; participants wore an accelerometer and a set of reflective markers on their lower body that allowed for tracking of the participants’ movements through a camera-based, motion-analysis system.

Participants completed three walking trials on the treadmill — one at a usual walking pace, another while walking slowly and another that included working on a task while walking (pushing a button in response to a sound).

The accelerometer signals were used to examine three aspects of movement: participants moving forward and backward, side to side and up and down. The researchers then used advanced mathematical computations to extract data from these signals.

The results — integrated into the mathematical models — showed significant differences between the healthy and clinical populations. These metrics were able to discriminate among the three groups, identifying critical features in how the participants walked.

The team now is looking to conduct this study on a larger scale to evaluate the gait patterns of older adults residing within independent living facilities.

Members of the research team included Jennifer S. Brach, Department of Physical Therapy, SHRS; Mark S. Redfern, vice provost for research and William Kepler Whiteford Professor of Bioengineering; Kristin A. Lowry, a postdoctoral scholar in the School of Medicine’s geriatric fellowship training program; and Swanson alumnus Jennica Bellanca of the Office of Mine Safety and Health Research in the National Institute for Occupational Safety and Health.

The paper was published online in June in IEEE Transactions on Neural Systems and Rehabilitation Engineering.

The research was supported by the Pittsburgh Older Americans Independence Center.

Placental cells may keep viruses from baby

Cells of the placenta may have a unique ability to prevent viruses from crossing from an expectant mother to her growing fetus and can transfer that trait to other kinds of cells, according to researchers at the School of Medicine and Magee-Womens Research Institute (MWRI). Their findings shed new light on the workings of the placenta and could point to new approaches to combat viral infections during pregnancy.

It is imperative that the fetus be protected from infections of its mother in order to develop properly. But how the placenta, long thought to be just a passive barrier between mother and child, accomplishes this feat has not been clear.

Said co-senior investigator Yoel Sadovsky, Elsie Hilliard Hillman Chair of Women’s Health Research, faculty member in obstetrics, gynecology and reproductive medicine and MWRI director: “Our findings reveal some of the complex and elegant mechanisms human placental cells, called trophoblasts, have evolved to keep viruses from infecting cells.”

Led by Sadovsky and co-senior investigator Carolyn Coyne, faculty member in microbiology and molecular genetics, the research team studied human trophoblast cells in the lab, exposing them to a panel of viruses. Unlike non-placental cells, trophoblasts were resistant to viral infection, but that trait was not a result of an inability of viruses to bind or enter the cells.

The researchers noted that when the medium, or fluid environment, in which the trophoblasts were cultured was transferred to non-placental cells, such as those that line blood vessels, they became resistant to viral infection, too.

The team also noted that when the medium was subject to sonication, which involves exposure to sound waves, viral resistance no longer was transferred to non-placental cells. This finding led them to take a closer look at exosomes, which are tiny spheres called nanovesicles that are secreted by trophoblasts and are sensitive to sonication. They found that fragments of genetic material called microRNAs contained within the exosomes, as well as lab-synthesized mimics of them, were able to induce autophagy, a mechanism of prolonged cellular recycling and survival. Blocking autophagy at least partially restored the cells’ vulnerability to viral infections.

Said Coyne: “Our results suggest this pathway could be a powerful evolutionary adaptation to protect the fetus and mother from viral invaders.”

Co-authors included researchers from MWRI, the departments of obstetrics, gynecology and reproductive sciences, microbiology and molecular genetics, infectious diseases and microbiology, cell biology and physiology, and surgery, and the University of Pittsburgh Cancer Institute.

The research was published in the online version of the Proceedings of the National Academy of Sciences and funded by the Pennsylvania Department of Health Research, the National Institutes of Health (NIH) and the Burroughs Wellcome Fund.


The University Times Research Notes column reports on funding awarded to Pitt researchers as well as findings arising from University research.

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