BILLW@SRI-AI.ARPA (12/19/83)
From: William "Chops" Westfield <BILLW@SRI-AI.ARPA>
a544 13-Dec-83 03:42
BC-SPACEHEALTH-12-13
EDITORS: If you are interested in obtaining a drawing to accompany
the following story, please call (312) 321-2034 between 9 a.m. and 5
p.m. Central Time, weekdays.
By Brent Staples
(c) 1983 Chicago Sun-Times (Independent Press Service)
A U.S. space station by 1990, moon colonies by the middle 1990s, and
a manned expedition to Mars by the year 2000. This is the timetable
NASA would like to follow. As ready as technology is for these
ventures, it's clear the human body is not.
Though the flight of Space Shuttle 9 presented no threat to the
astronauts' health, National Aeronautic and Space Administration
biomedical researchers say an extended space flight would leave the
traveler's body in terrible condition. He would develop kidney
stones. Calcium deposits would line his blood vessels, raising the
specter of stroke, heart disease and other complications. The
traveler's bones would be so severely weakened that upon returning to
Earth, even minor stress could precipitate fractures of the feet,
legs, hips and spinal column.
All these complications would arise from severe calcium loss, a
problem caused by the effect of weightlessness on bone-manufacturing
cells. The first hint of the calcium loss came in 1965 with the
relatively brief flight of Gemini VII. Though Alan Lovell and Frank
Borman were in orbit for only two weeks, post-flight analysis of
their body wastes showed that the vital mineral had begun to leave
their bodies.
In 1974, the 84-day mission of Skylab IV furnished the first
estimates of the calcium loss that could be expected after an
extended stay in space. Two of the three astronauts showed
significant losses - one of them lost 7 percent of his total body
calcium. On the basis of the Skylab figures, NASA's biomedical
researchers estimated that in 1 1/2 years - the time needed for a
round-trip to Mars - the body could be robbed of up to 40 percent of
one of its most vital minerals, causing a serious decrease in bone
density.
NASA has been groping for a solution to the calcium-loss problem for
the better part of two decades. Dr. Victor Schneider, chief research
scientist for NASA's bed-rest project, says NASA has kept subjects in
bed as long as 36 weeks in search of a means for preventing calcium
loss.
Schneider's experiments have included treating subjects with a
half-dozen calcium and phosphorous-related compounds - with no
success. Calcium and calcium-luring hormones were ineffective and
massive doses of phosphorous caused leukemia in some patients. It has
been demonstrated elsewhere that estrogen forestalls bone loss in
post-menopausal women, but there is no equivalent hormonal treatment
for men. Schneider is optimistic about an ongoing study in which
osteoporotic women are being given fluoride, a mineral known to
induce bone growth in adults. But results of that study may not be
known for five years.
Comparisons of bed-rest subjects and astronauts in space indicate
that exercise may be a slight hedge against calcium loss. The
greatest calcium loss among the Skylab IV crew was 7 percent, but
earthbound bed-rest subjects who remained in bed for the same period
lost 11 percent of their total body calcium.
Don Young, a senior researcher with NASA's biomedical research team,
suspects that the space crew's isometric exercises, bike rides and
rigorous research schedule made the difference.
Treatment with electrical impulses has induced growth of bone cells
in children afflicted by non-union bone, a disease in which breaks
and fractures are extremely slow in healing. This suggests that
electrical current might help in treating calcium loss in astronauts,
but Young is skeptical.
''Those studies were done on young people who have a lot of growth
potential,'' Young said. ''But we at NASA are working with men and
women, many of whom will be in their 40s and older. It is unlikely
that the procedure would work with them.
''We don't know whether bone loss would reach a plateau and stop,
or whether it would continue throughout the duration of an extended
flight,'' said Young. ''If we use the 7 percent bone-loss figure from
Skylab missions and extrapolate forward to six or seven months or a
year in space, we begin to see that the astronauts would lose enough
bone to be at serious risk of fractures and breaks. Assuming that the
loss continued, eventually the men would risk injury from undergoing
even non-traumatic activities.''
Even if replacing lost calcium was a viable alternative - which it
is not - there are other effects to be considered.
''When that much calcium is mobilized in the body, other
complications arise. The kidneys develop stones from trying to pass
the calcium out of the body, and the calcium would deposit itself in
places throughout the body, most likely in the veins and arteries,
presenting another series of problems,'' said Young.
Nor do possibilities seem hopeful for recovery after return to
Earth. The Skylab IV crew had not regained its pre-flight calcium
levels after 95 days on Earth, at which time NASA ceased to keep
records on the crew members. Animal studies have compounded concern
about whether the effect is permanent. Animals still show diminished
levels of the mineral three to four years after calcium loss was
experimentally induced.
Thus, astronauts who took off now on an extended space voyage almost
certainly would develop problems like osteoporosis.
END
nyt-12-13-83 0633est
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