Scholarship & Creative WorkA step toward better brain implants using conducting polymer nanotubes
Brain implants that can more clearly record signals from surrounding neurons in rats have been created at U-M. The findings eventually could lead to more effective treatment of neurological disorders such as Parkinson's disease and paralysis.
Neural electrodes must work for time periods ranging from hours to years. When the electrodes are implanted, the brain first reacts to the acute injury with an inflammatory response. Then the brain settles into a wound-healing, or chronic, response.
It's during this secondary response that brain tissue starts to encapsulate the electrode, cutting it off from communication with surrounding neurons.
The new brain implants developed at U-M are coated with nanotubes made of poly(3,4-ethylenedioxythiophene) (PEDOT), a biocompatible and electrically conductive polymer that has been shown to record neural signals better than conventional metal electrodes.
Researchers found that PEDOT nanotubes enhanced high-quality unit activity (signal-to-noise ratio >4) about 30 percent more than the uncoated sites. They also found that based on in vivo impedance data, PEDOT nanotubes might be used as a novel method for biosensing to indicate the transition between acute and chronic responses in brain tissue.
The results are featured in the cover article of the Oct. 5 issue of the journal Advanced Materials. The paper is titled, "Interfacing Conducting Polymer Nanotubes with the Central Nervous System: Chronic Neural Recording using Poly(3-4-ethylenedioxythiophene) Nanotubes."
"Microelectrodes implanted in the brain are increasingly being used to treat neurological disorders," says Mohammad Reza Abidian, a post-doctoral researcher working with Professor Daryl Kipke in the Neural Engineering Laboratory at the Department of Biomedical Engineering.
Less than half of graduating medical students in the United States say they received adequate training in understanding health care systems and the economics of practicing medicine, according to a study conducted by the Medical School.
The national survey of more than 58,000 medical students from 2003-07 showed an overwhelming majority were confident about their clinical training. But when it came to understanding health economics, the health care system, managed care, managing a practice or medical record-keeping, 40 percent to 50 percent of students reported feeling inadequately prepared.
The findings were published in the September issue of Academic Medicine.
"Our patients expect us to understand the system," says Dr. Matthew Davis, associate professor of pediatrics and internal medicine in the Child Health Evaluation and Research Unit at the Medical School. "If we don't, that can result in poor patient care.
"And if we don't expect doctors to understand the health care system, who is going to?" asks Davis, who co-authored the research with Dr. Monica Lypson, assistant dean of graduate medical education at the Medical School, and Dr. Mitesh Patel, a Medical School graduate now at the University of Pennsylvania.
Davis explains researchers wanted to assess what medical students are learning about health care systems, especially as the nation struggles with health care reform. It's important, Davis says, that physicians can contribute to the national dialogue.
Davis says he hopes the survey will prompt medical schools to stress the importance not only of physicians' ability to heal, but also to help guide their patients through a complex health care system. A higher-intensity curriculum in medical economics appears to work, he says.
U-M physicists have made the first atomic-scale maps of quantum dots, a major step toward the goal of producing "designer dots" that can be tailored for specific applications.
Quantum dots often called artificial atoms or nanoparticles are tiny semiconductor crystals with wide-ranging potential applications in computing, photovoltaic cells, light-emitting devices and other technologies. Each dot is a well-ordered cluster of atoms, 10 to 50 atoms in diameter.
Engineers are gaining the ability to manipulate the atoms in quantum dots to control their properties and behavior, through a process called directed assembly. But progress has been slowed, until now, by the lack of atomic-scale information about the structure and chemical makeup of quantum dots.
The new atomic-scale maps will help fill that knowledge gap, clearing the path to more rapid progress in the field of quantum-dot directed assembly, says Roy Clarke, professor of physics and corresponding author of a paper on the topic published online Sept. 27 in the journal Nature Nanotechnology.
Lead author of the paper is Divine Kumah of U-M's Applied Physics Program, who conducted the research for his doctoral dissertation.
To create the maps, Clarke's team illuminated the dots with a brilliant X-ray photon beam at Argonne National Laboratory's Advanced Photon Source. The beam acts like an X-ray microscope to reveal details about the quantum dot's structure. Because X-rays have very short wavelengths, they can be used to create super-high-resolution maps.
"We're measuring the position and the chemical makeup of individual pieces of a quantum dot at a resolution of one-hundredth of a nanometer," Clarke says. "So it's incredibly high resolution."
A nanometer is one-billionth of a meter.
Worldwide, thousands of workers die every year from mining accidents, and instantaneous coal outbursts in underground mines are among the major killers. Although scientists have been investigating coal outbursts for more than 150 years, the precise mechanism still is unknown.
New research by scientists at U-M and Peking University in Beijing, China, suggests that the outbursts occur through a process very similar to what happens during explosive volcanic eruptions. The research is described in a paper in the October issue of the journal Geology.
"Just as magma can fragment when pressure on it is reduced, triggering an explosive eruption, gas-rich coal can also erupt when suddenly decompressed, as happens when excavation exposes a new layer of coal," says Youxue Zhang, professor of geology, whose previous work on volcanic eruptions, Africa's "exploding lakes" and theorized methane-driven ocean eruptions set the stage for the current research.
Zhang did much of the work on the coal outburst project in 2006 and 2007, during a part-time professorship at Peking University. Around that time, a number of deadly coal mine accidents in China, Russia and the United States had made headlines, and just before leaving for China in 2006, Zhang had printed out articles about the disasters to read during his flight.
"While reading a paper describing coal outbursts as violent ejection of pulverized coal particles and gas, the similarity of coal outbursts to magma fragmentation suddenly occurred to me," Zhang says.
When he arrived at Peking University, he discussed the idea with colleague Ping Guan, and the two decided to collaborate on experiments simulating coal outbursts. Their experiments verified that coal outbursts are driven by high gas pressure inside coal and occur through a mechanism similar to magma fragmentation.
An early laboratory success is taking U-M researchers a step closer to parathyroid gland transplants that could one day prevent a currently untreatable form of bone loss associated with thyroid surgery.
The scientists were able to induce embryonic stem cells to differentiate into parathyroid cells that produced a hormone essential to maintaining bone density. The laboratory results in live cell cultures, published in Stem Cells and Development, need to be tested in further pre-clinical studies.
Parathyroid glands, four glands each the size of a rice grain that lie next to the thyroid in the neck, are easily damaged when surgeons operate on patients with cancerous or benign thyroid tumors. Without their calcium-regulating hormone, patients can develop osteomalacia, a severe form of bone loss similar to rickets that affects tens of thousands of people in the United States with muscle cramps and numbness in the hands and feet.
"We used human embryonic stem cells as a model for ways to work out the recipe to make parathyroid cells," says Dr. Gerard Doherty, chief of endocrine surgery and Norman W. Thompson Professor of Endocrine Surgery at the Medical School.
The research illustrates the payoff of rapidly increasing knowledge about how embryonic stem cells give rise to other kinds of cells. That knowledge can be the springboard for influencing other cells to regenerate damaged parts of the body.
Doherty's team used embryonic stem cells from a Bush administration-approved embryonic stem cell line to test a way to produce functioning, differentiated parathyroid cells to transplant into a patient and restore function.
With the recipe worked out, Doherty's team anticipates developing a treatment that doesn't use embryonic stem cells.
Additional U-M authors are Eve Bingham, Shih-Ping Cheng and Kathleen Woods Ignatoski.