Friday, July 31, 2009

EXPERIMENTS SHOW 'ARTIFICIAL GRAVITY' CAN PREVENT MUSCLE LOSS IN SPACE

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When the Apollo 11 crew got back from the moon, 40 years ago, they showed no ill effects from seven days spent in weightlessness. But as American astronauts and Soviet cosmonauts began conducting longer-duration space flights, scientists noticed a disturbing trend: the longer humans stay in zero gravity, the more muscle they lose. Space travelers exposed to weightlessness for a year or more — such as those on a mission to Mars, for example — could wind up crippled on their return to Earth, unable to walk or even sit up.

Now, researchers at the University of Texas Medical Branch at Galveston have conducted the first human experiments using a device intended to counteract this effect — a NASA centrifuge that spins a test subject with his or her feet outward 30 times a minute, creating an effect similar to standing against a force two and half times that of gravity. Working with volunteers kept in bed for three weeks to simulate zero-gravity conditions, they found that just one hour a day on the centrifuge was sufficient to restore muscle synthesis.

"This gives us a potential countermeasure that we might be able to use on extended space flights and solve a lot of the problems with muscle wasting," said UTMB associate professor Douglas Paddon-Jones, senior author of a paper on the centrifuge research in the July issue of the Journal of Applied Physiology. "This small amount of loading, one hour a day of essentially standing up, maintained the potential for muscle growth."

Fifteen healthy male volunteers participated in the study, carried out in UTMB's General Clinical Research Center. All spent 21 days lying in a slightly head-down position that previous investigations have shown produces effects on muscles like those of weightlessness. Eight rode the centrifuge daily. Measurements of protein synthesis and breakdown in thigh and calf muscle were taken at the beginning and end of the investigation, using muscle biopsies and blood samples. The results showed that members of the centrifuge group continued to make thigh muscle protein at a normal rate, while the control group's muscle synthesis rate dropped by almost half.

Paddon-Jones cautioned that the rate of muscle protein synthesis alone does not necessarily predict changes in muscle function. But, he pointed out, it was still a strong indicator that a relatively brief intervention could have a positive effect in preventing zero-gravity muscle loss — one that might also be applied on Earth.

"We've studied elderly inpatients here at UTMB — 95 percent of the time they're completely inactive, and in three days they lose more than a kilogram of muscle," Paddon-Jones said. "A human centrifuge may not be the answer, but we are interested in seeing if something as simple as increasing the amount of time our patients spend standing and moving can slow down this process. This NASA research is one of a series of important studies that we hope to ultimately translate to a clinical population."

University of Texas Medical Branch

NEW DISCOVERY SUGGESTS TREES EVOLVED CAMOUFLAGE DEFENSE AGAINST LONG EXTINCT PREDATOR

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Many animal species such as snakes, insects and fish have evolved camouflage defences to deter attack from their predators. However research published in New Phytologist has discovered that trees in New Zealand have evolved a similar defence to protect themselves from extinct giant birds, providing the first evidence of this strategy in plant life.

"Plants are attacked by a bewildering array of herbivores and in response they have evolved a variety of defences to deter predators such as thorns and noxious chemicals," said lead researcher Dr Kevin Burns from Victoria University of Wellington, New Zealand. "In contrast animals often use colours to hide from predators or advertise defences, but until now there has been little evidence of colour based defences in plants."

Dr Burns' team studied the leaves of the Araliaceae tree (P. crassifolius) a heteroblastic species which is native to New Zealand. This species goes through several strange colour transitions during the process from germination to maturity and the reason for these changes is now thought to be a defence strategy from an extinct predator, the moa.

Before the arrival of humans New Zealand had no native land mammals, but was home to moa, giant flightless birds, closely related to the modern ostrich and the top herbivore predator in the food chain. However moa were hunted to extinction 750 years ago.

The Araliaceae tree has several defences which the team suggest are linked to the historic presence of moa. Seedlings produce small narrow leaves, which appear mottled to the human eye. Saplings meanwhile produce larger, more elongated leaves with thorn-like dentitions.

The mottled colours of seedling leaves are similar to the appearance of leaf litter, which would have made them difficult for a moa to distinguish. The unusual colouring may also reduce the probability of leaf outlines and help camouflage leaves against the sunlight-draped forest floor.

Moa also lacked teeth and swallowed leaves by placing them in their bills and snapping their head forward. The long rigid leaves produced by P. crassifolius would have been difficult for a moa to swallow. The maximum browsing height of the largest known moa was approximately 300cm and once P. crassifolius grow above this height they produce leaves that are ordinary in size, shape and colour, lacking any defence.

To prove that these defences were linked to the presence of moa the team compared Araliaceae leaves to samples from a similar species of tree, P chathamicus, from the Chatham Islands, which are 800 kilometres east of New Zealand. Unlike New Zealand the islands lacked large browsers such as Moa and so the plant life did not evolve a defence against them.

"The Chatham island species displays less morphological changes between adults and juveniles," said Burns. "If these colouring changes developed in response to the presence of moa in New Zealand they are reduced when they have evolved in the absence of moa."

Wiley InterScience

CHIMPS, LIKE HUMANS, FOCUS ON FACES

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A chimp's attention is captured by faces more effectively than by bananas. A series of experiments described in BioMed Central's open access journal Frontiers in Zoology suggests that the apes are wired to respond to faces in a similar manner to humans.

Masaki Tomonaga and Tomoko Imura from the Primate Research Institute at Kyoto University, Japan, tested the effects of a series of different images on chimps' reaction times. Tomonaga said, "It is well known that faces are processed in a different manner from other types of complex visual stimuli. Recent studies of face perception in humans clarified that faces represent special stimuli with regard to visuospatial attention as well. That is, they are able to capture our attention. We've shown that chimps share this tendency to notice and pay attention to faces in preference to other objects."

The researchers gave chimps the option of playing a game for food. If the chimps chose to, they could approach a computer screen where an image would be displayed, followed by a target. If the chimps pressed the target, they would receive a reward. In one set of experiments, the image was displayed on one side of the screen followed by the target either on the same side or the previously blank side. Reaction times were shown to improve when the target appeared behind the image. The chimps were then presented with two images side by side, one of which was a chimpanzee face. When the target appeared behind the face, reaction times were better than when it appeared behind the other object – showing that attention had indeed been drawn to the face-side of the screen.

Chimpanzee faces were shown to attract attention more effectively than bananas and other objects such as flowers, houses or trains. This effect was reduced when the faces were inverted, suggesting that it is the specific configuration of an upright face that catches the eye. According to Tomonaga, "This attentional capture was also observed when upright human faces were presented, indicating that this effect is not limited to their own species".

(Photo: Tomonaga et al., Frontiers in Zoology)

Frontiers in Zoology

ANCIENT HUMANS LEFT EVIDENCE FROM THE PARTY THAT ENDED 4,000 YEARS AGO

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The party was over more than 4,000 years ago, but the remnants still remain in the gourds and squashes that served as dishware. For the first time, University of Missouri researchers have studied the residues from gourds and squash artifacts that date back to 2200 B.C. and recovered starch grains from manioc, potato, chili pepper, arrowroot and algarrobo. The starches provide clues about the foods consumed at feasts and document the earliest evidence of the consumption of algarrobo and arrowroot in Peru.

"Archaeological starch grain research allows us to gain a better understanding of how ancient humans used plants, the types of food they ate, and how that food was prepared," said Neil Duncan, doctoral student of anthropology in the MU College of Arts and Science and lead author of the study that was published in the Proceedings of the National Academy of Science (PNAS). "This is the first study to analyze residue from bottle gourd or squash artifacts. Squash and bottle gourds had a variety of uses 4,000 years ago, including being used as dishes, net floats and symbolic containers. Residue analysis can help determine the specific use."

In the study, researchers recovered starch grains from squash and gourd artifacts by a method that currently is used to recover microfossils from stone tools and ceramics. First, the artifact was placed in a special water bath to loosen and remove adhering residue. Then the artifact's interior surface was lightly brushed to remove any remaining residue. The residues were collected, and starch grains were isolated from each of these sediments.

"The starch residues of edible plants found on the artifacts and the special archaeological context from which these artifacts were recovered suggest that the artifacts were used in a ritual setting for the serving and production of food," Duncan said. "The method used in this study could be used in other areas and time periods in which gourds and squash rinds are preserved."

Scientists believe the Buena Vista site, where the starch grains were recovered, served as a small ceremonial center in the central Chillon Valley. The social and ritual use of food is not well understood during this time period in Peru, but this research will enhance the potential for understanding, Duncan said.

The study, "Gourd and squash artifacts yield starch grains of feasting foods from preceramic Peru," is coauthored by Duncan; Deborah Pearsall, professor of anthropology; and Robert Benfer, emeritus professor of anthropology.

(Photo: U. Missouri)

University of Missouri

UCLA SCIENTISTS PRESENT FIRST GENETIC EVIDENCE FOR WHY PLACEBOS WORK

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Placebos are a sham — usually mere sugar pills designed to represent "no treatment" in a clinical treatment study. The effectiveness of the actual medication is compared with the placebo to determine if the medication works.

And yet, for some people, the placebo works nearly as well as the medication. How well placebos work varies widely among individuals. Why that is so, and why they work at all, remains a mystery, thought to be based on some combination of biological and psychological factors.

Now, researchers at UCLA have found a new explanation: genetics. Dr. Andrew Leuchter, a professor of psychiatry at the UCLA Semel Institute for Neuroscience and Human Behavior, and colleagues report that in people suffering from major depressive disorder, or MDD, genes that influence the brain's reward pathways may modulate the response to placebos. The research appears in the August edition of the Journal of Clinical Psychopharmacology.

Placebos are thought to act by stimulating the brain's central reward pathways by releasing a class of neurotransmitters called monoamines, specifically dopamine and norepinephrine. These are the brain chemicals that make us "feel good." Because the chemical signaling done by monoamines is under strong genetic control, the scientists reasoned that common genetic variations between individuals — called genetic polymorphisms — could influence the placebo response.

Researchers took blood samples from 84 people diagnosed with MDD; 32 were given medication and 52 a placebo. The researchers looked at the polymorphisms in genes that coded for two enzymes that regulate monoamine levels: catechol-O-methyltransferase (COMT) and monoamine oxidase A (MAO-A). Subjects with the highest enzyme activity within the MAO-A polymorphism had a significantly lower placebo response than those with other genotypes. With respect to COMT, those with lower enzyme activity within this polymorphism had a lower placebo response.

"Our findings suggest that patients with MDD who have specific MAO-A and COMT genotypes may be biologically advantaged or disadvantaged in mounting a placebo response, because of the activity of these two enzymes," said Leuchter, who directs the Laboratory of Brain, Behavior and Pharmacology at the UCLA Semel Institute.

"To our knowledge, this is the first study to examine the association between MAO-A and COMT polymorphisms and a response to placebo in people who suffer from major depressive disorder," he said.

Leuchter noted that this is not the sole explanation for a response to a placebo, which is likely to be caused by many factors, both biological and psychosocial. "But the data suggests that individual differences in response to placebo are significantly influenced by individual genotypes," he said.

Including the influence of genotype in the design of clinical trials could facilitate more powerful testing of future treatments, Leuchter said.

UCLA

NEW FINDINGS ON THE BIRTH OF THE SOLAR SYSTEM

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A team of international astrophysicists, including Dr Maria Lugaro from Monash University, has discovered a new explanation for the early composition of our solar system.

The team has found that radioactive nuclei found in the earliest meteorites, dating back billions of years, could have been delivered by a nearby dying giant star of six times the mass of the sun.

Dr Lugaro said the findings could change our current ideas on the origin of the solar system.

"We have known about the early presence of these radioactive nuclei in meteorites since the 1960s, but we do not know where they originated from. The presence of the radioactive nuclei has been previously linked to a nearby supernova explosion, but we are showing now that these nuclei are more compatible with an origin from the winds coming from a large dying star," Dr Lugaro said.

The conclusion was reached by combining stellar observations from telescopes with recently developed theoretical models reproduced on powerful computers of how stars evolve and which nuclear reaction occurs within their interiors.

"We need to know if the presence of radioactive nuclei in young planetary systems is a common or a special event in our galaxy because their presence affected the evolution of the first large rocks (the parent bodies of asteroids and meteorites) in the solar system. These are believed to be the source of much of earth's water, which is essential for life," Dr Lugaro said.

"Within one million years of the formation of the solar system the radioactive nuclei decayed inside the rocks where they were trapped, releasing high-energy photons, which caused the rocks to heat. Since much of earth's water is believed to have originated from these first rocks, the possibility of life on earth depends on their heating history and, in turn, on the presence of radioactive nuclei." Dr Lugaro said.

"What we need to do now is investigate the probability that a dying giant star could have actually been nearby our then young solar system and polluted it with radioactive nuclei. This will inform us on the place where the solar system was born, on the probability that other young planetary system also are polluted with radioactive nuclei, and, eventually, on the probability of having water on terrestrial planets in other planetary systems."

(Photo: Gabriel Perez Diaz)

Monash University

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