A human virus normally harmless in laboratory mice mutated into a
heart-damaging pathogen when the animals were raised on a diet devoid of the
essential element selenium. And, once mutated, the virus continued to damage
hearts--even in mice that got ample selenium in their feed. The findings are
the first indication that a nutritional deficiency can cause a virus to mutate
to a more virulent form. And its importance is not limited to
nutritionally-deprived populations, say researchers with the University of
North Carolina and ARS who collaborated on the studies. In theory, one
selenium-deficient person or animal could produce a new family of virus mutants
that could cross species and spread worldwide, causing disease even in
wellnourished people.
ARS researchers supplied the nutritional expertise and diets. UNC
researchers found six sites on the coxsackie B3 virus genome that were
permanently altered after it had spent time in selenium-deficient mice.
Coxsackie viruses, as a group, infect more than 20 million people in this
country annually, producing a range of maladies from sore throat and cold
symptoms to inflammation of the heart muscle. About 10 percent of infected
people develop serious diseases, including heart muscle inflammation.
Other nutritional deficiencies can also cause viral mutations, it appears.
UNC researchers are now analyzing the genes of coxsackie B3 virus that damaged
hearts in vitamin-E-deficient mice. They expect to find the same alterations as
with selenium deficiency. Both nutrients serve as antioxidants in the body. If
such mutations occur in other RNA viruses, they may help explain the many new
strains of influenza virus arising in China, which has widespread
selenium-deficient areas.
For more information, contact Melinda A. Beck, (919) 966-6809, Frank
Porter Graham Child Development Center, University of North Carolina, Chapel
Hill, NC; or Orville A. Levander, (301) 504- 8504, Beltsville Human Nutrition
Research Center, Beltsville, MD.
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Large oral doses of vitamin E or beta carotene do not appear to prevent
sunburn or damage to skin cells that can lead to photoaging and skin cancer.
But preliminary evidence suggests that lycopene--a relative of beta
carotene--might help reduce the damage caused by the sun's ultraviolet (UV)
rays. That's the finding in two separate studies. Researchers wanted to resolve
conflicting evidence that antioxidant vitamins taken by mouth protect the skin
against oxidizing agents generated by the sun's rays.
In one study of 12 men and women, small areas of skin were exposed to a
burning dose of UV radiation after the volunteers had taken either 400
International Units (IU) of vitamin E or a placebo daily for six months. The
supplement did not significantly increase skin levels of vitamin E. And it did
not reduce skin redness or cell damage compared to volunteers who didn't get
the real thing.
In another study of 16 women, half of whom took beta carotene supplements,
skin levels increased. But this did not prevent sunburn. They were similarly
exposed to UV radiation after taking one 120-milligram beta carotene
supplement--10 times the amount in most supplements--and again after taking a
90-mg supplement daily for three weeks. Skin levels of beta carotene didn't
decrease after UV radiation, indicating the nutrient was not being used to
protect against sun damage.
By contrast, skin levels of lycopene dropped significantly after UV
radiation. Researchers could not test the effects of giving extra lycopene,
however, because supplements were not available when the study was done.
Lycopene is the red pigment that colors tomatoes, watermelons and pink
grapefruit.
For more information, contact Judy D. Ribaya-Mercado, (617) 556-3128,
about the beta carotene/lycopene study; or Mohsen Meydani, (617) 556-3126,
about the vitamin E study, USDA Jean Mayer Human Nutrition Research Center on
Aging at Tufts, Boston, MA.
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Selenium--the essential trace element known for its antioxidant
prowess--also appears to lift the spirits, according to a study of mood changes
under high and low intakes. During the 15-week study, 30 men reported
significant changes in two of six moods, as measured by a standard
questionnaire. The 15 men who consumed nearly 3.5 times the daily recommended
selenium intake felt significantly more clearheaded and elated toward the end
of the study than they did at the outset.
Another 15 men consumed only 40 percent of the recommended intake. Within
that group, researchers found differences in all six moods based on the
activity of a selenium-containing enzyme in the men's blood platelets. This is
one indicator of how much selenium is available in the body. The men with the
more active enzymes felt more agreeable than hostile, more clearheaded than
confused, more composed than anxious, more confident than unsure, more elated
than depressed and more energic than tired. That's even though enzyme activity
was within the "normal" range for all the volunteers.
The findings agree with another ARS study in which the amount of selenium
in men's red blood cells correlated with two of the mood states. A note of
caution: Large doses of selenium can be highly toxic. The World Health
Organization recommends a daily limit of 400 micrograms--that's millionths of a
gram. Good food sources include animal flesh--meat and poultry--seafood and
grain products--breads and cereals.
For more information, contact James G. Penland, (701) 795-8471, Grand
Forks Human Nutrition Research Center, Grand Forks, ND.
Meals rich in selenium may alter thyroid hormone activity and result in
weight gains, according to ARS findings. That effect might help patients with
wasting diseases such as cancer or AIDS. Adding pounds, or at least preventing
unwanted weight loss, may be a side benefit of the experimental selenium
treatments that some medical researchers have already suggested for both types
of patients. Dosages would have to be carefully specified, however, because
selenium in amounts 10 times higher than the Recommend Dietary Allowance (RDA)
can be toxic.
Working with 11 male volunteers, researchers found that a regimen which
safely provided five times the RDA for selenium caused the men to gain about
1.5 pounds over a 14-week period, despite scientists' efforts to keep
everyone's weight stable. The highselenium stint lowered the body's levels of
the T3 thyroid hormone, which controls the body's calorie-burning rate.
Volunteers on the low-selenium program received only about onefifth the RDA.
They increased their levels of T3 and lost about one pound over the same
period.
Researchers already knew that the body needs selenium for converting the
precursor compound--T4--to T3. But they were surprised that their results
disagreed with studies, done elsewhere, in which selenium-deficient diets had
the opposite effect in lab animals.
For more information, contact Chris Hawkes or Nancy L. Keim, (415)
556-1377, Western Human Nutrition Research Center, San Francisco, CA.
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A newly discovered lipid may join the ranks of drugs that fight
inflammation. Such nonsteroidal drugs that are now available-- including
aspirin, acetaminophen and ibuprofen--inhibit two biochemical pathways in the
body. But the new lipid, which could be indirectly produced from agricultural
products, inhibits only one--the lipoxin biosynthetic pathway. A drug with
these properties would work especially well on inflammatory conditions
associated with asthma and atherosclerosis. Pharmaceutical companies have been
searching for such a compound. Another plus for the new lipid: It tested
negative for fungicidal, herbicidal and insecticidal properties and was
nontoxic to several types of cancer and HIV-infected cells. Scientists have
applied for a patent.
For more information, contact Robert A. Moreau, (215) 233-6428, Plant
Science and Technology Research, Philadelphia, PA.
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Women who carry a genetic marker for low bone density already have less
dense bones in their twenties and thirties than women without the marker.
That's the finding of a study of 155 black and white women age 20 to 40, and it
agrees with what has been seen in women past menopause. Because low bone
density can lead to osteoporosis, the finding points to the need to identify
girls with this marker early in life so that steps can be taken to help them
reach their maximal bone density.
The marker, discovered last year by Australian scientists, results from a
mutation in a gene that makes a protein which regulates the way the body uses
calcium. Women with two copies of the marker (one from each parent) had between
eight and nine percent less bone density in the hip and 6.4 percent less in the
spine than those with only one or no mutation.
The study also dispelled the notion that this trait might explain why
blacks generally have denser bones than whites. The percentage of black and
white women with the genetic marker was about equal. Researchers are now
testing to see if people with the genetic marker are unable to adapt to low
calcium intakes-- which are common in the United States. This could help
explain their low bone density.
For more information, contact James C. Fleet, (617) 556-3186, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
Black girls absorb calcium more efficiently and form new bone at a faster
rate than their white counterparts. This difference in calcium absorption
during childhood and adolescence may explain why black women tend to have lower
rates of osteoporosis later in life: They begin with stronger bones. In the
study of 89 girls between the ages of 5 and 16, researchers found the greatest
difference in absorption rates after the onset of puberty. But black girls
consistently demonstrated more bone-forming activity throughout childhood and
adolescence. The finding suggests that recommended intakes of calcium may need
to be tailored to particular groups.
However, while the black girls absorbed more calcium, none of the girls in
the study met the recommended intakes. Current recommendations based on a
recent National Institutes of Health panel specify three to four servings of
calcium-rich foods for children ages 6 to 10, increasing to four to five
servings at age 11. A serving could be one cup of milk, an eight-ounce
container of yogurt or 1-1/2 ounces of natural cheese.
For more information, contact Steven Abrams, (713) 798-7000, Children's
Nutrition Research Center, Houston, TX.
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Women shaped more like an apple than a pear may have more difficulty losing
weight. In studies of 22 women, those with more fat around the waist than the
hips and thighs--the apple shape--lost about eight percent of their body
weight. That compared to an 18 percent loss in those with larger hips and
thighs compared to the waist--the pear shape.
Using sophisticated x-ray equipment, the researchers also corroborated what
others have observed in larger studies using simpler equipment: Weight loss did
not change the waist-to-hip ratio. The women's basic shape remained the same.
Since numerous studies have associated the apple shape with a higher risk of
cardiovascular disease, diabetes and even cancer, the findings question whether
a weight-loss regimen alone will substantially reduce risk. This study combined
regular aerobic exercise with a 50-percent calorie cut for optimal weight
reduction. Nearly all the weight lost by the women in both groups was in body
fat, not in muscle.
For more information, contact William A. Siders, (701) 795-8430, or Henry
C. Lukaski, (701) 795-8429, Grand Forks Human Nutrition Research Center, Grand
Forks, ND.
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Is 200 International Units (IU) of vitamin D--the current Recommended
Dietary Allowance (RDA)--enough to minimize bone loss in older women? The
latest study suggests that more is better for protecting the hip--at least in
the Northeast where sunshine is sparse during the colder months. Sunlight
prompts the skin to manufacture its own vitamin D. During the two-year study of
261 women living in the Boston area, half of the volunteers consumed 200 IU of
vitamin D daily, while the other half got 800 IU. And all were given extra
calcium during the study to ensure optimal intake.
The group on the higher vitamin D intake lost one percent less bone at the
hip during the first year and 0.5 percent less in the second compared to those
getting the RDA. Seventy percent of the benefit occurred in the winter-spring
months when the sun's rays are weakest and exposure is infrequent. Trouble is,
the women's average vitamin D intake was only half the RDA before the study
began.
Slowing bone loss at the hip--actually, the top of the thigh bone where it
fits into the pelvic girdle--could spare many elderly people from a painful
disability. The hip is the leading site of fractures in the elderly. Good
sources of vitamin D include fatty fish, egg yolks, milk--because it is
fortified with the vitamin--and fortified breads and cereals.
For more information, contact Bess Dawson-Hughes, (617) 556-3066, USDA
Jean Mayer Human Nutrition Research Center on Aging at Tufts, Boston, MA.
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Older women had a significant drop in lean body mass, in muscle function
and in the ability to fight off infection when their protein intake was only
about half the Recommended Dietary Allowance (RDA). For a 140-pound woman, the
RDA is 50 grams per day. While most Americans consume more than enough protein,
some 10 to 20 percent of women over age 55 get less than 30 grams daily. That's
about the amount in half a chicken breast, in a three-ounce can of tuna or in
two cups of dried beans.
Researchers wanted to see if such a low-protein intake would compromise a
woman's immune response as well as her ability to get around and perform normal
tasks, even if the women got enough calories. Six volunteers over age 66 ate
about half the RDA for protein for nine weeks, while six others got a little
more than the RDA. The women getting half the RDA lost an average eight percent
of lean tissue, most of which was muscle. The amount of weight they could push
in a chest press exercise dropped by 12 percent. And one measure of immune
response--a hypersensitivity skin test--was 50 percent lower by the end of the
study.
By contrast, the six women getting ample protein had no changes in muscle
mass. Moreover, several measurements of muscle function and immune response
improved significantly as did several blood protein measurements, suggesting
that their diet prior to the study may have been a little low in protein.
For more information, contact Carmen Castaneda, (617) 556-3142, or
Marilyn C. Crim, (617) 556-3095, Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts, Boston, MA.
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Obstetricians who want to measure water weight gains of pregnant women may
someday do so without having to take a blood sample. A study by University of
California at Berkeley and ARS scientists may be the first to explore this
specialized use of a technique known as bioimpedance spectroscopy, or BIS.
Water is the biggest portion of pregnancy weight gain. Buildup of water outside
cells can lead to edema, a sometimes painful swelling that can elevate blood
pressure and cause other complications.
In tests of 10 pregnant women, ages 20 to 37, BIS proved to be faster and
easier than another option, the sodium bromide technique, to estimate the water
outside and inside cells. And it was just as accurate. BIS measurements take
only two minutes and--unlike the sodium bromide technique--require no blood
samples.
The bioimpedance instrument sends a harmless sweep of currents through
electrodes at the hand and foot. The device distinguishes differences in
resistance as the electricity travels easily through water or is impeded by
cell membranes. Via computer link, bioimpedance measurements are turned into
estimates, on a printout, of the total amount of water in the body, plus the
amounts outside and inside cells.
For more information, contact Marta D. Van Loan, (415) 556-5729, Western
Human Nutrition Research Center, San Francisco, CA; or William W. Wong, (713)
798-7168, Children's Nutrition Research Center, Houston, TX.
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A virus that causes sterility in corn earworms could give farmers an
environmentally safe weapon against this scourge of corn, cotton and other
crops. Also, the virus may have potential to knock down related pests, such as
the legume podborer, tobacco budworm and fall armyworm. Together, these pests
cause an estimated $5 billion in damage to various crops throughout the world.
The virus, called gonad specific virus (GSV), attacks the corn earworm in its
moth stage and infects only the moth's reproductive system, deforming either
ovaries or testes. Most infected moths lack reproductive organs altogether.
Based on lab studies, scientists estimate that low levels of the virus
cause sterility in 70 to 80 percent of infected moths. The rest become
carriers, passing the virus along to the next generation through mating. Field
tests of the virus are planned for later this year. ARS has filed a patent
application on the virus.
For more information, contact Ashok Raina, (301) 504- 9396, Insect
Neurobiology and Hormone Lab, Beltsville, MD.
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High-quality apples now reach consumers sooner because of advances in
storage techniques. ARS scientists proved to Washington state officials that
Gala and Jonagold apples need be kept only 45 days in controlled atmosphere
(CA) storage to meet state requirements. Previously, 90-day storage was
required. CA storage means low levels of oxygen, high levels of carbon dioxide
and cool temperatures. This slows an apple's natural "breathing"
rate. CA apples stay firmer, crisper and tastier than apples stored in
traditional cold rooms. Now the researchers are studying ways to improve the
keeping quality of apricots, which can't be stored for more than a few weeks.
For more information, contact Stephen R. Drake, (509) 664-2280, Tree
Fruit Research Laboratory, Wenatchee, WA.
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Prepeeled oranges and other citrus could soon be making their debut in
restaurants and school lunch programs. Prepeeled Fruit, Inc., of Groveland, FL,
has been licensed to use ARS-patented technology to remove citrus peels with
commercially available food-grade enzymes. That eliminates hand peeling and
allows more precise portion control. Also, the process removes the bitter white
portion of grapefruit peel. Prepeeled Fruit, Inc., incorporated the technique
in a new processing plant in central Florida. The plant can process about
50,000 pounds--about 100,000 pieces--of fresh fruit each eight-hour shift.
For more information, contact Robert A. Baker, (813) 293-4133, Citrus and
Subtropical Products Laboratory, Winter Haven, FL.
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Microorganisms are key ingredients in two new commerical products
registered by the Environmental Protection Agency as the first postharvest
biofungicides. Cooperative research and development agreements between ARS and
two companies resulted in these natural components being used to control rot in
stored fruit. ECOGEN of Langhorne, PA, made ASPIRE from the yeast Candida
oleophila, found on tomatoes. Patented by ARS and Israeli scientists, the yeast
combats postharvest rot on citrus and apples.
EcoScience of Worcester, MA, developed BIO-SAVE 11 from Pseudomonas
syringae, a bacterium that fights rot on apples, pears and citrus. This
organism was isolated from the surface of apples and is being patented by ARS.
California's Environmental Protection Agency concurrently registered BIO-SAVE
11 as a biofungicide. The current worldwide market for citrus postharvest
treatments is about $18 million a year, and $8 million for apples.
For more information, contact Charles L. Wilson or Wojciech J.
Janisiewicz, (304) 725-3451, Appalachian Fruit Research Laboratory,
Kearneysville, WV.
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A new gene has been successfully inserted into Thompson seedless grapes--a
scientific first. ARS scientists and collaborating university researchers hope
the gene will give built-in protection against a common grape virus. This
genetic engineering advance could decrease economic losses to grape crops and
reduce the amount of chemicals put into the environment. It paves the way for
plant breeders to improve disease and insect resistance of all major grape
varieties. Healthy, genetically transformed Thompson seedless grapevines are
growing in ARS greenhouses in Kearneysville, WV. Scientists from the University
of Florida and Cornell participated in the research.
For more information contact Ralph Scorza, (304) 725-3451, Appalchian
Fruit Research Station, Kearneysville, WV; or David W. Ramming or Richard L.
Emershad, (209) 453-3160, Horticultural Crops Research Laboratory, Fresno,
CA.
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