From PBS on Line :
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What's Being Done in Parkinson's Research?
The recent explosion of biomedical research has introduced
several exciting
developments in the search for a cure for or treatment for
Parkinson's disease.
One of the most common diseases of old age, Parkinson's
disease is believed
to affect about 1 million Americans.
Parkinson's disease research focuses on many fronts. Some
investigators are
looking at the musculoskeletal system and how it is regulated
by the brain.
Others are trying to find a link between the disease and
environmental factors,
such as toxins that may trigger the disorder, or defective
genes. Meanwhile,
some scientists are trying to prevent or reverse the disease
with protective
drugs.
In INNOVATION: LIVE LONG AND PROSPER, Dr. Anthony Arthur, a
dental surgeon, was implanted with an electrode that would
stimulate cells
deep in the brain, in the area called the subthalamic
nucleus, to make them
more receptive to dopamine. In this cutting-edge therapy,
offered at Mount
Sinai Medical Center in New York City, the electrode is
connected to an
assistive device, similar to a heart pacemaker, that is
surgically implanted under
the collarbone. After some fine tuning, the device seemed to
produce enough
relief from tremors and other symptoms that the man could
lead a nearly
normal life.
More recently, the French researchers tried implanting the
electrodes
specifically into the subthalamic nucleus; this technique
seems to cause
improvement in a wide range of symptoms. In 1995, they
reported in the
medical journal LANCET that they had done the procedure on
three patients.
Three months later after surgery, they said, the patients'
motor abilities had
improved 42 to 84 percent, as measured on standard tests, and
their ability to
do the activities of daily life had improved 58 to 88
percent.
In August, 1997, the Food and Drug Administration (FDA)
approved the brain
implant, which previously had been used only experimentally.
At that time,
fewer than one hundred patients in the United States had
undergone deep brain
stimulation, and in only a fraction of those cases had the
implant been done in
the subthalamic nucleus. In granting approval, the FDA
required Medtronic
Inc. of Minneapolis, which makes the implant technology, to
study the
long-term effects of constant electrical stimulation on brain
tissue.
According to the National Institute of Neurological Disorders
and Stroke,
another promising treatment method involves using an
implanted pump or
implanting capsules containing dopamine-producing cells into
the brain. The
capsules are surrounded by a biologically inert membrane that
lets the drug
pass through at a timed rate.
At Columbia University, researchers are genetically
engineering dopamine
receptors in transgenic mice to better understand the
mechanisms of the
disease and develop novel therapies for Parkinson's. At the
University of
Virginia and the University of Colorado, rhesus monkeys have
been given a
growth factor called glial-cell-line-derived neurotrophic
factor, or GDNF, to
see if they can regrow damaged dopamine-producing nerve
cells. So far, the
results have been promising.
In Massachusetts, Genzyme Corp., Tissue Repair Division and
Diacrin, Inc.,
are working on the development of porcine transplants.
Researchers will
transplant healthy nerve cells from pigs into human brains to
restore damaged
neural circuits. This xenograft — or cross-species transplant
— therapy is
being tested at several major medical centers.
Neural transplantation is an experimental technique proposed
for treating the
disease. A federally-sponsored trial of neural transplants
using human fetal
tissue is being done at three research universities,
including Columbia
University. The goal is to replace lost or damaged
dopamine-producing
neurons with healthy, fetal neurons. Another promising
approach may be the
use of genetically engineered cells, such as skin cells, that
could carry neurons
to the affected site. These might even come from the
patient's own body and
be replicated in tissue culture.
The search for more effective medications for Parkinson's
disease is likely to
be aided by the recent isolation of at least five individual
brain receptors for
dopamine. And, in 1996, NIH scientists reported finding the
general location of
a gene that may be responsible for some cases of familial
Parkinson's disease.
This gene may not be responsible for all Parkinson's, but it
may help scientists
understand more about the nature of the disease.
-- ------------------
Cheers ,
+----| Joao Paulo de Carvalho |------ +
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+--------| Salvador-Bahia-Brazil |------+
