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News Release
Office of News and Information
212 Whitehead Hall / 3400 N. Charles Street
Baltimore, Maryland 21218-2692
Phone: (410) 516-7160 / Fax (410) 516-5251
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July 6, 1995
FOR IMMEDIATE RELEASE
CONTACT: Ken Keatley
jkk@resource.ca.jhu.edu
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Hopkins Researchers Find Polymers Can Control
Medication, Strengthen Bones
Researchers in the School of Engineering at The Johns
Hopkins University are creating polymers -- complex chemical
compounds formed from a number of simpler molecules -- that
may help to revolutionize medical treatment. Here are two
examples:
1. It's All in the Timing
Cancer patients often require treatment in one isolated
area of the body. Targeting the delivery of medication to that
area, without hurting surrounding healthy tissue, is a problem
Mark Saltzman, professor of chemical engineering at Hopkins,
is working to solve.
He is developing biocompatible polymers that release
drugs, proteins, antibodies, antigens and other molecules into
a targeted area of the body at precisely controlled rates over
a period of weeks or months.
For instance, as Saltzman and Hopkins neurosurgeon Henry
Brem are learning, polymeric delivery may make it possible to
introduce therapeutic drugs directly into solid masses, like
brain tumors, that are difficult to treat. Eventually, these
polymeric drug delivery systems could be applied to the
treatment of other diseases, including AIDS and Alzheimer's.
"A device that releases agents at a controlled rate has
many advantages," said Saltzman, who has a joint appointment
in biomedical engineering. "It doesn't need to flood the
entire body with agents to protect one area. And the agents
are non-toxic and don't cause hormonal changes."
He has also discovered, in collaboration with Hopkins
biophysics professor Richard Cone, that polymer systems can
provide long-term female contraceptive and prophylactic
protection. They are combining the system's contraceptive
function with prevention against sexually transmitted
diseases, by using a vaginal ring made of an ethylene
vinyl-acetate copolymer. Preliminary testing on mice has
generated encouraging results.
2. Breakthrough for Better Bones
Kam Leong, associate professor of biomedical engineering
at Hopkins, is developing synthetic polymers to speed and
improve the healing of broken or brittle bones.
Leong, who holds a joint appointment in the Department
of Materials Science and Engineering, is perfecting a
biodegradable polymer for use in bone grafts that would
eliminate the need for metal plates, pins and screws used in
treatment now. Unlike metal, the polymers -- based on a foam
fabrication technique -- contain pores into which bone tissue
grow; these pores can also be filled with bone growth
enhancers.
As the bone solidifies, the polymer implants -- which are
both biodegradable and biocompatible -- dissolve, gradually
allowing the bone to support more weight. This is an
improvement over the use of metal plates, which support all
the weight normally carried by the bone; when the metal is
removed, the still-weak bone must suddenly carry all of the
weight, increasing the likelihood of reinjury. Also, metal
implants require two operations (one to insert them, one to
remove them), and, as foreign substances, carry the long-term
risk of infection.
"Polymeric prosthesis devices enjoy the advantage of
having tailor-made properties," explained Leong, who is
working in collaboration with Hari Reddi and Edmund Chao in
the Hopkins School of Medicine. "The structural support
function of a polymer device can be integrated with the
drug-carrier function to enhance bone union."
He added that biodegradable polymers also have the
potential for a number of environmental applications.
Johns Hopkins University news releases can be found on the
World Wide Web at
http://www.jhu.edu/news_info/news/
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of science and medical news releases is available at the
same address.
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