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Binge eating and crash diets could shorten your life |
Published: Wednesday, 30-Apr-2008
Medical Science News
According to scientists in Britain binge eating and crash dieting
may significantly reduce life expectancy.
The scientists from Glasgow University in Scotland arrived at this
conclusion based on the results of an animal study.
The study which compared the growth rate, success of reproduction
and life span of stickleback fish, found that fish given a "binge
then diet" food regime had a reduced life span of up to 25%.
The scientists believe their findings could have implications for
teenagers and children who follow extreme patterns of dieting while
they are still growing.
They say uneven growth, due to the fluctuation in the amount eaten
per day, is responsible for the increase in the risk of sudden
death. Professor Metcalfe says the difference in life span was not a
consequence of more rapid
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ageing but an increase in the risk of sudden death, possibly
because the body tissues are more likely to have imperfections due
to growth spurts.
The findings are published in the journal, Proceedings of the Royal
Society B.
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New findings challenge conventional ideas on evolution of human
diet, natural selection |
Published: Tuesday, 29-Apr-2008
Medical Science News
New findings suggest that the ancient human "cousin" known as the
"Nutcracker Man" wasn't regularly eating anything like nuts after
all.
The researchers examined the teeth of Paranthropus boisei, an
ancient hominin that lived between 2.3 million and 1.2 million years
ago and is known popularly as the "Nutcracker Man" because it has
the biggest, flattest cheek teeth and the thickest enamel of any
known hominin. Since the first specimen was reported by Mary and
Louis
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Leakey in
1959, scientists have believed that P. boisei fed on nuts and seeds or
roots and tubers found on the savannas throughout eastern Africa because
the teeth, cranium and mandible appear to be built for chewing and
crunching hard objects.
"The morphology suggests what P. boisei could eat, but not necessarily
what it did eat," Ungar said.
Anthropologists have traditionally inferred the diet of this and other
ancient human ancestors by looking at the size and shape of the teeth
and jaws. However, by looking at the patterns of microscopic wear on a
tooth, scientists can get direct evidence for what these species
actually ate.
Ungar and his colleagues used a combination of a scanning confocal
microscope, engineering software and scale-sensitive fractal analysis to
create a microwear texture analysis of the molars of seven specimens of
P. boisei. The specimens spanned a time frame of almost a million years
and were found in Kenya, Tanzania and Ethiopia. Using these techniques,
they were able to create three-dimensional |
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"point clouds" that showed the pits and scratches on the
teeth.
The researchers looked at complexity and directionality of wear
textures in the teeth they examined. Since food interacts with
teeth, it leaves behind telltale signs that can be measured. Hard,
brittle foods like nuts and seeds tend to lead to more complex tooth
profiles, while tough foods like leaves lead to more parallel
scratches, which corresponds with directionality.
They compared the dental microwear profiles of P. boisei to the
microwear profiles of modern-day primates that eat different types
of diets - grey-cheeked mangabeys and brown capuchins, which eat
mostly soft items but fall back on hard nuts or palm fronds, and the
mantled howling monkey and silvered leaf monkey, which eat mostly
leaves and other tough foods. They also compared the microwear
analysis to analyses of teeth from some of the fossil's more
contemporary counterparts -- Australopithecus africanus, which lived
between 3.3 million and 2.3 million years ago, and Paranthropus
robustus, which lived between 2 million and 1.5 million years ago.
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The P. boisei teeth had light
wear, suggesting that none of the individuals ate extremely hard or
tough foods in the days leading up to death. It's a pattern more
consistent with modern-day fruit-eating animals than with most
modern-day primates.
"It looks more like they were eating Jell-o," Ungar said.
This finding, while contradictory to previous speculation on the diet of
P. boisei, is in line with a paradox that has been documented in fish.
Liem's Paradox states that animals may actively avoid eating the very
foods they have developed adaptations for when they can find other food
sources.
It appears that this paradox may hold true for P. boisei and for some
modern-day primates as well.
"If you give a gorilla a choice of eating a sugary fruit or a leaf, it
will take the fruit every time," Ungar said. "But if you look at a
gorilla's skull, its sharp teeth are adapted to consuming tough leaves.
They don't eat the leaves unless they have to."
This finding represents a fundamental shift in the way researchers look
at the diets of |
these
hominins.
"This challenges the fundamental assumptions of why such specializations
occur in nature," Ungar said. "It shows that animals can develop an
extreme degree of specialization without the specialized object becoming
a preferred resource."
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Silver nanoparticles may kill beneficial bacteria |
Published: Tuesday, 29-Apr-2008
Medical Science News
For years, scientists have known about silver's ability to kill harmful
bacteria and, recently, have used this knowledge to create consumer
products containing silver nanoparticles.
Now, a University of Missouri researcher has found that silver
nanoparticles also may destroy benign bacteria that are used to remove
ammonia from wastewater treatment systems.
Several products containing silver nanoparticles already are on the
market, including socks containing silver nanoparticles designed to
inhibit odor-causing |
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bacteria and high-tech,
energy-efficient washing machines that disinfect clothes by
generating the tiny particles. The positive effects of that
technology may be overshadowed by the potential negative
environmental impact.
"We found that silver nanoparticles are extremely toxic. The
nanoparticles destroy the benign species of bacteria that are used
for wastewater treatment. It basically halts the reproduction
activity of the good bacteria."
Hu said silver nanoparticles generate more unique chemicals, known
as highly reactive oxygen species, than do larger forms of silver.
These oxygen species chemicals likely inhibit bacterial growth. For
example, the use of wastewater treatment "sludge" as
land-application fertilizer is a common practice, according to Hu.
If high levels of silver nanoparticles are present in the sludge,
soil used to grow food crops may be harmed.
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Tomato paste helps fight sunburn and wrinkles |
Medical Science News
Published: Tuesday, 29-Apr-2008
Scientists in Britain are suggesting |
that a
tomato product may help fight sunburn and wrinkles. A study by
researchers at Manchester and Newcastle Universities has found that
adding five tablespoons of tomato paste to the daily diet of 10
volunteers, their skin's ability to protect against harmful UV rays
improved.
Damage from UV rays can lead to premature ageing and even skin cancer
and the scientists say it is the antioxidant lycopene found in tomatoes
which provided the benefit.
The lycopene in tomatoes is at its highest concentration when the
vegetable has been cooked - a link has already been established between
lycopene and a reduction in the risk of prostate cancer.
The researchers gave 10 volunteers around 55g of standard tomato paste
which contains high levels of cooked tomatoes and 10g of olive oil daily
while another 10 participants received just the olive oil.
Tests after three months using UV lamps showed the tomato-eaters were a
third better protected against sunburn at the end of the study than at
the start, and other tests suggested the tomato-based diet had boosted |
the production of collagen the protein
that keeps skin supple.
The skin samples from the tomato group showed they had 33% more
protection against sunburn, the equivalent of a very low factor sun
cream and much higher levels of pro-collagen, a molecule which gives the
skin its structure and keeps its firm.
Professor Lesley Rhodes, a dermatologist at the University of Manchester
says the tomato diet boosted the level of pro-collagen in the skin
significantly which suggests a potential for the reversal of the skin
ageing process.
The team warn however that tomatoes should be viewed as a "helpful
addition" rather than an alternative to suncream and are now conducting
research into the benefits of lycopene for the skin.
Other research has shown lycopene may protect against prostate cancer,
as well as the lung, bladder, cervical and pancreatic forms of the
disease; it may also boost heart health by combating artery-clogging
cholesterol.
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