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the Battalion
Space travel may contribute to weakened bones
..
By Arun Arjunan
The Battalion
Astronauts spend much of their missions repairing
space stations and fixing broken satellites while pro
tecting them from wear and tear. At the same time, the
astronauts’ own biological machinery is susceptible to
damage.
Dr. Susan Bloomfield, associate professor of health
and kinesiology, has received a $697,000 grant from
the National Space Biomedical Research Institute to
study bone blood flow during simulated microgravity
to gain a better understanding of this problem.
Bloomfield and her research team said they suspect
that long-term space travel may lead to the deteriora
tion astronauts’ bones. The zero-gravity environment
of space decreases even blood flow to the bones, par
ticularly to the bones Ifi the legs, and may prevent es
sential nutrients from reaching the bones.
Bloomfield said there
need to be more efforts
toward finding some
W preventive measures.
“One of the main ar-
eas we need to look at is
how bones recover after
long period of weightlessness,” she said.
Bloomfield said she believes that her re-
imc
people who suffer from rapid deterioration of bone
mass.
“If we can find tiny solutions to the problems that
microgravity presents to astronauts, we may be able to
find a way to better treat patients with osteoporosis,”
she said.
Bloomfield published her research findings about
microgravity effects on bone loss in the 2000 issue of
the Journal of Applied Physiology. Her results show that
the decrease in blood How to bones occurs much quick
er than previously thought. —
The results were based on an experiment in which
Bloomfield’s team measured the bone formation or de
terioration that occurs in rats as a result of large in
creases or decreases of blood circulation directed to
ward the leg bones. The microgravity environment is
simulated by suspending the rat’s limbs so the legs are
not active. A shift in blood How occurs within ten min
utes of the microgravity simulation.
“The unweighted hind limbs in rats become weaker
with less blood flow to the femur (thigh bone),” Bloom
field said!
Harry Hogan, a research associate in mechanical en
gineering, measures the bone density of the removed fe
murs from the experimental rats.
/The actual weight-bearing strength of the bones are
measured by compression testing,” Hogan said.
These studies showed that the mineral density and
structural strength of the bones decreased significant
ly in a 28-day interval compared with a control group
of rats that were subjected to regular gravitational con
ditions.
Bloomfield said, under a greater load, bone cells re
produce rapidly to increase bone mass and consequent
ly increase bone strength.
“Normal weight-bearitfg activity stimulates the
growth of osteoblasts (bone cells), which means more
bone tissue to increase the overall structural strength,”
she said.
The research was conducted on the leg bones of rats
because the microgravity of space mainly affects the
lower body ofastronauts. Reduced blood flow to the
tibia and the femur may contribute to the decrease
of bone formation.
She said these conditions may cause the loss
of bone mass. The decline of blood circulation
means that the bones may receive fewer es
sential nutrients.
ip “Without the necessary minerals for
the bone and hormones to stimulate bone
growth, then bone density will definitely i% '
be affected, “she said.
The mineral density of the bones was
tested through a procedure known as pe
ripheral quantitative computed tomogra
phy (pQCT), a technique similar to CAT
scan in humans.
One particular area that Bloomfield’s
research tigun is investigating is Dobuta-
mine, a medication used to treat conges
tive heart failure. Dobutamine relaxes
smooth muscle and increases blood flow.
Bloomfield said she believes that
Dobutamine or a related medication
could be used to increase circulation to
the bones.
“A pharmaceutical that allows for
more blood to How towards the bones
may significantly slow down the deteri
oration,” she said.
She said the discovery of such a pre
vents ve measure would make long-term
space travel possible without the con- s .
cem of bone loss
ije
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