***EMBARGOED***Please do not report on the results mentioned in this press release before 12:00 noon eastern time on March 10, 2008.
ADVANCES IN PROTON THERAPY,4-D CANCER THERAPY,BIOCOMPATIBILITY,STEM CELL HYDROGELS,LIVING LENSES,NANOPARTICLES,AND MUCH MORE.
Newswise — Many of the leading scientists working at the interface of physics and medicine will present their latest research at next month's March Meeting of American Physical Society (APS) in New Orleans, from March 10-14, 2008.
For more than a century, some of the greatest advances in medicine have been born at the intersection of biology and physics. Some of the most interesting discoveries of tomorrow are being investigated at this crossroads today, designing advanced imaging and therapeutic techniques for confronting cancer and other diseases deep within the body, inventing advanced materials that help alleviate the suffering of people with chronic disease, creating new materials with useful biomedical properties, and discovering ways of delivering lifesaving drugs to where they are needed in the body.
Reporters are invited to cover this meeting in person, by filling out the registration form at the bottom of this page; or remotely, by contacting the presenters directly. A full list of presentations can be accessed at: http://meetings.aps.org/Meeting/MAR08/Content/1017.
A few highlights of some of the newsworthy medical physics results to be presented in New Orleans:
************************************************************************PROTON THERAPY -- YESTERDAY AND TOMORROWDespite the fact that doctors in this country have used protons effectively for more than half a century to bombard and destroy tumors, proton therapy is still a relatively rare technology for treating cancer. X rays account for more than 99 percent of the radiology sessions in this country, and only 25,000 people worldwide have ever gotten high-energy proton therapy.
Part of the reason for the limited use of proton therapy is the massive investment required to build and equip the facility. There are only five operating proton therapy clinics in the United States -- one each in Boston, Loma Linda, Bloomington, Houston, and Jacksonville. According to James McDonough (University of Pennsylvania), who is helping to open a new proton therapy clinic in downtown Philadelphia, advances in proton therapy have not always kept pace with advances in X-ray therapy because it has been difficult to develop technology for so few users.
Advances in imaging technology (CT, MRI, and PET) have revolutionized the imaging of tumors, enabling doctors to better guide treatment and increasing interest in very conformal delivery methods, including proton therapy. In his talk, McDonough will discuss the latest advances in proton therapy and discuss how proton technology might catch up with conventional X-ray therapy. Talk S16.3, "Technological Advances in Proton Therapy," will begin at 3:42 p.m. on Wednesday, March 12, 2008 in Room 208 of the Morial Convention Center. See:http://meetings.aps.org/Meeting/MAR08/Event/79614.
************************************************************************TREATING CANCER IN FOUR-DIMENSIONSTreating cancer with ionizing radiation beams requires both precision and caution. The effectiveness of the therapy is determined by the doctors' ability to balance two often-conflicting goals: deliver a high enough radiation dose to kill the cancer cells inside a tumor but spare the healthy cells in critical organs surrounding the tumor.
In conventional treatment, this challenge is usually met by obtaining a high-resolution 3-D image of the tumor with a CT scan prior to treatment. Then a multi-beam strategy is designed to precisely target the tumor and deliver a high dose treatment that maximally conforms to the tumor shape. However, treatment typically lasts several weeks, and during this time, the shape of the tumor may change as its cells die off, as the surrounding organs shift slightly from day to day, and as fatty tissue disappears as people lose weight -- a common side effect. In current practice, weekly X rays are used to monitor potential three-dimensional changes as treatment progresses.
Jeffrey Williamson (Virginia Commonwealth University) says that optimizing radiation therapy is not a three-dimensional problem at all, but rather a four-dimensional one. His talk at the APS March meeting will focus on new methods in image-guided radiation therapy (IGRT), such as using cone-beam CT scans to obtain 3-D images of the patient in treatment position throughout the treatment course. These improve the margins of error in calculating the tumor volume and increase the targeting precision. In his talk, Williamson will discuss the current state-of-the-art and future directions of IGRT and outline the scientific and technical problems that need to be solved to improve the technology in the future. An important future challenge is developing methods for incorporating feedback from images that depict not only anatomy but biological responses to the treatment (for example, PET and functional MRI), into adaptive 4-D radiation therapy and other imaging modalities.
Talk U16.1, "Image-Guided Radiation Therapy: the potential for imaging science research to improve cancer treatment outcomes" will begin at 8:00 a.m. on Thursday, March 13, 2008 in Room 208 of the Morial Convention Center. See:http://meetings.aps.org/Meeting/MAR08/Event/80080.
************************************************************************GETTING THE MOST OUT OF BIOCOMPATIBILITYFrom hips to lenses to valves to electrodes on the brain, there are millions of manmade devices implanted into people every year. All the stuff doctors worldwide implant into their patients amounts to a $100 billion industry, and like any industry, there are lots of opportunities to improve the devices-lowering cost, improving performance, and increasing efficacy, for instance.
One of the biggest ways to improve implantable devices would be to solve the "foreign body reaction" that often occurs within days of implantation. The body basically deals with the presence of foreign bodies like the glass, metal, silicone, or rubber components of a medical implant device by isolating them behind a wall of collagen fibers. Buddy Ratner (University of Washington) and his colleagues are designing a sleeve to fit around implantable devices. Covered with uniform, spherical microscopic pores, these sleeves can minimize the foreign body reaction by controlling the cells (called macrophages) that come to coat the implanted devices with collagen. They are now testing these sleeves on glucose sensors, which generally fail after a week or so. Talk A38.1, "The quantification of biocompatibility: toward a new definition" will begin at 8:00 a.m. on Monday, March 10, 2008 in Room 230 of the Morial Convention Center. See: http://meetings.aps.org/Meeting/MAR08/Event/75140.
************************************************************************BIOCOMPATIBILITY-WHAT ARE THE QUESTIONS?The three largest hurdles faced by makers of implantable medical devices are the same as those faced by restaurant owners-location, location, location. In the case of implantable medical devices, the majority of problems come down to the fact that these devices have to operate for months or years in the human body, an environment that can be downright hostile. They face surface fouling, blood clotting, infection, fibrosis, blood clotting, and calcification, which can all affect the functioning of the devices. Cells of the immune system release chemicals that cause inflammation in the area of medical implants. Other cells cover the devices with proteins and other materials. And these reactions also depend on a host of factors, such as age, general health, and genetic background.
SuPing Lyu (Medtronic, Inc.) and his colleagues have been looking at the interactions between the human biology and implantable medical devices made to treat chronic diseases (e.g., pacemakers, heart valves, and neurostimulators). He will assess the biological processes involved in biocompatibility and will examine whether these processes can be treated more quantitatively. He will also discuss what physicists can contribute. Talk A38.2, "Biocompatibility of implantable biomedical devices" will begin at 8:36 a.m. on Monday, March 10, 2008 in Room 230 of the Morial Convention Center. See: http://meetings.aps.org/Meeting/MAR08/Event/75141.
************************************************************************HYDROGELS MAY ENABLE STEM CELL DELIVERYThe human liver is something of a regenerative marvel. You can cut off a large part of it and have the healthy remainder grow back into a new, fully functional whole organ. Not everyone's liver is healthy enough for this, however, and most of the body's other tissues no ability to regenerate as quickly as the liver.
One potential application of stem cells in medicine is to transplant them at the site of a tissue wound and allow the biochemistry of that tissue to guide the stem cells into proliferating, differentiating, and ultimately regrowing the organ. There are many technological (and regulatory) hurdles that must be overcome before this sort of application is realized, and one of these is how to retain the stem cells in the tissue. Simply depositing in the tissue them is not enough -- they must be anchored in a sticky, non-toxic material or else they will leak away.
Joel Schneider (University of Delaware) and his colleague Darrin Pochan design biological materials for use in tissue regeneration, and they recently invented a peptide-based hydrogel that can encapsulate stem cells for transplantation. Recently, he and his colleagues showed that the stem cells stay viable for weeks in the hydrogel after shear-thin delivery. The hydrogel acts as scaffolding for the stem cells involved in tissue regeneration. Talk W25.1, "Design of Responsive Peptide-based Hydrogels as Therapeutics" will begin at 2:30 p.m. on Thursday, March 13, 2008 in Room 217 of the Morial Convention Center. See: http://meetings.aps.org/Meeting/MAR08/Event/78346.
************************************************************************SYNTHETIC SURFACES: THROUGH A LIVING LENS The promise of using living cells to construct new materials is that these materials may allow us to examine biological properties that may not be obvious by looking at the cells in their native tissues. These observations may be useful in applications such as modeling various diseases and testing how the cells respond to drugs to treat those diseases.
Graduate student Jessica Zimberlin and her advisor Alfred Crosby (University of Massachusetts) are growing various types of biological cells on a silicon and polystyrene surface. On top of the polystyrene, the cells naturally contract forming dynamic surfaces of microlenses. By chemically controlling how much the cells are able to contract, Zimberlin and Crosby can force hundreds of cells at a time to collectively change the curvature of the microlenses. They can then quantify the material properties of these sheets, and they can compare how different sheets have different properties depending on the type of cell involved. These synthetic surfaces also allow them to test the effect of chemicals and other stimuli on those material properties.
Potentially, cell sheets could be grown from an individual's cells. The would have the same DNA as that individual, and determining how the cells react to various drugs might illuminate how that person would react and respond to the same drugs. Talk P16.10, "Living Microlens Arrays" will begin at 10:12 a.m. on Wednesday, March 12, 2008 in Room 208 of the Morial Convention Center. See: http://meetings.aps.org/Meeting/MAR08/Event/78346.
************************************************************************NANOPARTICLES KILL TUMORS IN RATSThe ability to deliver drugs specifically to one part of the brain or some other specific tissue in the body is highly desirable in diseases like cancer, where the drugs may have widespread toxicity to healthy cells throughout the body. One nanotechnology-based approach to solving this problem was designed about 10 years ago by Raoul Kopelman (University of Michigan). Kopelman found a way of making tiny polyacrylamide particles about 60 nanometers in diameter that can be imbedded with drugs or other compounds and safely ferried to a location inside the body. Moreover, antibodies or other "targeting" molecules can be attached to the outside of the particles so that they can guide this payload though the bloodstream towards where the drugs are needed.
In his talk, Kopelman describes one experiment where he and his colleagues decorated these particles with short amino acid sequences-peptides-that help guide them into the nuclei of cancer cells in the brain. By loading these particles with an MRI contrast agent, he can reveal the outline of the cancer cells. He can also load the nanoparticles with therapeutics that can be released at the desired location. As one example, he and his colleagues loaded the particles with a chemical that produces singlet oxygen when exposed to a light source.
Singlet oxygen is a highly reactive molecule that will quickly react with other nearby molecules. Inside a cancer cell, it is deadly, as Kopelman and his colleagues showed. With one 5-minute illumination with a red laser, they cured a few rats of glioblastoma, one particularly nasty form of brain cancer. Talk X15.2, "Targeted Multifunctional Nanoparticles cure and image Brain Tumors: Selective MRI Contrast Enhancement and Photodynamic Therapy" will begin at 8:36 a.m. on Friday, March 14, 2008 in Room 207 of the Morial Convention Center. See: http://meetings.aps.org/Meeting/MAR08/Event/81498.
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WEBSITE AND PRESSROOM INFORMATIONThe main meeting website is http://www.aps.org/meetings/march/index.cfm. Complimentary press registration will allow journalists and public information officers to attend all scientific sessions and exhibits. The meeting pressroom will be located in exhibit hall area B2-2. The phone number there is 564-670-6800.
ABOUT APSThe American Physical Society is the world's leading professional body of physicists, representing over 46,000 physicists in academia and industry in the US and internationally. The APS has offices in College Park, MD; Ridge, NY; and Washington, DC.
ABOUT AIPHeadquartered in College Park, Md., the American Institute of Physics is a not-for-profit membership corporation chartered in New York State in 1931 for the purpose of promoting the advancement and diffusion of the knowledge of physics and its application to human welfare.
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