|
Research
Roundup
BIOCHEMICAL
PATHWAY DETOXIFIES HEAVY METALS | FUEL
CELL USING LIQUID DIESEL | GENE CARRIES
MESSAGES FROM CIRCADIAN CLOCK | 'HEART
SENSE' GAME PASSES EARLY TEST
Biochemical
Pathway Detoxifies Heavy Metals
Biologists
at Penn have discovered the first biochemical pathway in animals
responsible for the detoxification of heavy metals such as
arsenic, mercury and cadmium. They have established that the
enzyme phytochelatin synthase, which had previously been found
only in plants and some fungi, is also present in some animals.
The team
led by Dr. Philip A. Rea, professor of biology, and including
plant scientist Dr. Olena K. Vatamaniuk and animal cell and
developmental biologists Dr. Elizabeth A. Bucher and Dr. James
T. Ward made the discovery in work with the nematode worm
Caenorhabditis elegans. They reported their results in the
Journal of Biological Chemistry.
"Despite
two decades of research into the biochemical basis of heavy
metal detoxification in animals, never before had the involvement
of phytochelatins been even cursorily mentioned or speculated,"
said Dr. Rea, a member of Penn's Plant Science Institute.
"Discovery of this pathway in C. elegans establishes
a firm basis for determining its ubiquity in other animals
and for clarifying how animals eliminate, sequester and metabolize
heavy metals."
Because preliminary
work suggests that genes encoding PC synthase may also be
found in parasitic invertebrates, the findings of Dr. Rea's
group could help guard against growing resistance to certain
heavy metal-based drugs. Diseases caused by these parasites,
which include elephantitis and lymphatic filariasis, kill
millions of people worldwide each year, but physicians have
noted with some alarm that traditional treatments are waning
in effectiveness.
C. elegans
is the third organism in which a gene for PC synthase has
been found, following the plant Arabidopsis thaliana and the
yeast Schizosaccharomyces pombe. The three metals processed
by PC synthase-arsenic, mercury and cadmium -all rank among
the 10 most common contaminants at EPA Superfund sites, and
increasing emissions pose an acute problem for all organisms.
These metals harm organisms, including humans, by displacing
essential heavy metals such as copper and zinc from their
cellular binding sites, by undergoing aberrant reactions with
proteins and enzymes, and by promoting the formation of destructive
active oxygen species.
This work
was funded by the National Science Foundation.
|
BIOCHEMICAL
PATHWAY DETOXIFIES HEAVY METALS | FUEL
CELL USING LIQUID DIESEL | GENE CARRIES
MESSAGES FROM CIRCADIAN CLOCK | 'HEART
SENSE' GAME PASSES EARLY TEST
Engineers
Develop Fuel Cell Using Liquid Diesel
Chemical
engineers at Penn have developed a prototype fuel cell that's
the first to run on a readily available liquid fuel source,
in this case ordinary diesel fuel. The work nudges fuel cells
closer to viability, offering the promise of compact, portable
power sources that offer much more bang for the buck than
combustion engines or existing batteries.
Dr. Raymond
J. Gorte, professor of chemical engineering, and colleague
Dr. John M. Vohs, professor and chair of chemical engineering,
shook the fuel cell world in March 2000 with the publication
of a Nature paper in which they reported developing
a fuel cell that could run on butane, the first fuel cell
to operate on a fuel other than hydrogen. With the development
of a fuel cell that runs directly on liquid diesel of the
type sold at gas stations, the team has sidestepped the thorny
problem of "reforming" fuels to hydrogen to run
fuel cells.
"In
our earlier work, we were unable to feed liquid diesel to
the fuel cell because we did not have a means for vaporizing
fuels that have a low vapor pressure at room temperature,"
Dr. Gorte said. "This paper demonstrated that we could
feed these liquids to a fuel cell using a method analogous
to a fuel injector in an internal combustion engine and still
get stable operation of the fuel cell."
Smaller than
a penny, the prototype fuel cell developed by Dr. Gorte, Dr.
Vohs, graduate student Hyuk Kim and postdoctoral researcher
Seungdoo Park, operates in a furnace set at 700 degrees Celsius.
A commercial, self-contained fuel cell would ideally generate
that heat itself using the fuel placed in it.
Although
unlikely to replace household batteries for small appliances
and portable electronics, researchers have suggested that
fuel cells might be appropriate for powering cars and laptop
computers. Fuel cells could also make possible electric generators
that operate on propane or butane.
Dr. Gorte,
Dr. Vohs, Mr. Kim and Dr. Park's work with solid oxide
fuel cells was funded by the Office of Naval Research and
published in the July issue of Journal of the Electrochemical
Society.
|
BIOCHEMICAL
PATHWAY DETOXIFIES HEAVY METALS | FUEL
CELL USING LIQUID DIESEL | GENE CARRIES
MESSAGES FROM CIRCADIAN CLOCK | 'HEART
SENSE' GAME PASSES EARLY TEST
Gene Carries
Messages From Circadian Clock
Scientists
have long known that the gene Nf1 is so important to development
that when it is missing the condition known as Neurofibromatosis
results, causing tumors and sometimes leading to cancer before
the patient reaches adulthood.
Now researchers
have discovered that the Nf1 gene serves a second major purpose:
It is also necessary for circadian rhythm. The body can't
maintain its rest-activity cycle without it. "There have
been a lot of anecdotal reports by physicians that many patients
suffering from neurofibromatosis also suffer from sleep disturbances.
But this is the first time someone has definitively linked
Nf1 to the circadian system," said Dr. Julie Williams,
first author of the study by scientists at Penn's School
of Medicine. Their finding, was published September 21, in
the journal Science, represents a major advance in
understanding the body's complex circadian mechanism.
It moves the research beyond the question of what constitutes
our biological clock, and how it responds to light, to the
more specific question: How does it actually regulate changes
within the body? Dr. Williams and her colleagues found that
in the absence of the Nf1 protein, the body is unable to keep
time. Although their research relied on the Drosophila fly
model, the Penn scientists were also able to establish that
the signaling pathway triggered by Nf1 in the fly is directly
analogous to the Nf1 pathway in mammals.
"Our
work shows that when Nf1 affects circadian rhythm in flies,
it uses the same mechanism that is present in humans, which
is the Ras/Mapk pathway. This validates the fly as the model
to study this illness," said Dr. Amita Sehgal, who directed
the study.
"We've
found that Nf1 affects the circadian rhythm of the rest'
phase in the cycle, but it doesn't affect the clock itself,"
said Dr. Sehgal. "The clock is keeping time-but it can't
send the message affecting rest' without NF1,"
Dr. Sehgal said.
The research
was funded by the Howard Hughes Medical Institute, NIH, Neurofibromatosis
Foundation, American Cancer Society, and U.S. Army Medical
Research command.
Others who
participated in this study are: Dr. Henry S. Su; Dr. Jeffrey
Michael Field, both Penn scientists, and Dr. Andre Bernards,
of Massachusetts General Hospital Cancer Center in Boston.
|
BIOCHEMICAL
PATHWAY DETOXIFIES HEAVY METALS | FUEL
CELL USING LIQUID DIESEL | GENE CARRIES
MESSAGES FROM CIRCADIAN CLOCK | 'HEART
SENSE' GAME PASSES EARLY TEST
'Heart-Sense'
Game Passes Early Test
A computer
game developed at Penn to encourage prompt medical attention
in the wake of a heart attack appears to have passed its first
test: a preliminary study has shown that the game rendered
its players more likely to respond to symptoms by calling
911 or reporting to the emergency room in a timely manner.
Dr. Barry
G. Silverman, the creator of the Heart-Sense game, reported
the finding in the September issue of the INFORMS Journal
of Health Care Management Science.
Players of
the game, which can be used on most personal computers equipped
with CD-ROMs, find themselves encouraging citizens of an imaginary
village to seek medical treatment for their heart attack symptoms.
"It's
believed that people learn best by teaching others,"
said Dr. Silverman, a professor of systems engineering in
the schools of SEAS and Medicine and the Wharton School. "This
study indicates that even the most rudimentary version of
the Heart-Sense game improves the likelihood that patients
will seek medical attention for symptoms of a haeat attack."
"Initial
results show that users of the game exhibit a significant
shift in intention to call 911 and avoid delay ... as well
as a better understanding of both symptoms and of the need
to manage time during a heart attack," wrote Dr. Silverman
and co-authors Dr. Ransom Weaver of SEAS and Dr. John Holmes,
Dr. Stephen Kimmel, Dr. Charles Branas and Dr. Doug Ivins
of the Center for Clinical Epidemiology and Biostatistics
at the School of Medicine.
Cardiology
researchers have documented that inaction in the face of heart
attacks is a serious problem, with different studies placing
the average delay at anywhere from two to 12 hours. It has
been estimated that 26 to 44 percent of the 1.25 million Americans
who suffer heart attacks annually delay more than four hours
in seeking care.
Dr. Silverman's team
has been developing the game for roughly two years, funded
by the National Heart Attack Alert Program of the National
Institutes of Health and the National Library of Medicine.
|
BIOCHEMICAL
PATHWAY DETOXIFIES HEAVY METALS | FUEL CELL USING
LIQUID DIESEL | GENE CARRIES MESSAGES FROM CIRCADIAN
CLOCK | 'HEART SENSE' GAME PASSES EARLY TEST
Almanac, Vol. 48, No. 7, October 9, 2001
|
ISSUE HIGHLIGHTS:
Tuesday,
October 9, 2001
Volume 48 Number 7
www.upenn.edu/almanac/
|