Adolescent male chimps in large community strive to be alphas

ScienceDaily (Sep. 19, 2012) — An Ohio University anthropologist reports the first observation of dominance relationships among adolescent male chimpanzees, which he attributes to the composition of their community. Hogan Sherrow spent eight years studying the Ngogo community of chimpanzees in Kibale National Park in western Uganda. Ngogo is the biggest chimpanzee community on record, with more than 150 members and about twice as many males as found in other chimp communities across Africa.

Unlike their adult male counterparts, which have a well-documented dominance hierarchy, adolescent males have not been known to establish dominance relationships. During four field seasons between 2000 and 2004, however, Sherrow found that some adolescent males pant grunted to other adolescent males on a consistent basis. Research by Jane Goodall established that pant grunts are made by subordinate individuals to dominant ones, Sherrow explained.

"It calms hostilities. It means, 'I know that you're stronger than me, so don't beat me up.' It's like they're sending up the white flag," said Sherrow, an assistant professor of anthropology who published his recent findings in the journal Folia Primatologica.

After ranking the 17 adolescent males in order of dominance, Sherrow concluded that the biggest and oldest animals were at the top of the hierarchy. There were only two exceptions, males that appeared to act in a subordinate manner due to physical injuries.

Sherrow suggests that he observed dominance relationships in the adolescent males of this chimpanzee community due to its size and heightened competition for females. Each male in Ngogo must contend with 35 to 40 others, whereas most communities contain 10 to 15 competitors for mating. Adolescent male chimps also may vie for access to high-ranking adult males as a competitive strategy.

Adult male chimpanzees have clear and defined dominance relationships that depend on size, strength and the ability to form alliances in the community. The most dominant males have priority access to resources and potential mates and usually father more offspring.

"We should not be surprised that adolescent males can form these dominance relationships. Adults males form them, and adolescent males need to learn them at some point," Sherrow said.

Studies of other immature males in primate, mammal and even human communities with intense competition for resources also have found adolescent dominance hierarchies, he added.

Because the Ngogo community is unusually large, Sherrow noted that scientists should seek to observe this behavior in another neighboring community of this size to determine if a similar hierarchy can be documented. The Ngogo study site, located in the Ugandan rain forest, was established in 1995 and has been observed daily by researchers.

The recent study not only offers a new view of chimpanzee behavior, but could shed light on human power and dominance as well, Sherrow suggested.

"Because chimpanzees, along with bonobos, are our closest living relatives, understanding things like how and why they form dominance relationships helps us understand the drive for status and prestige in humans," he said.

The L.S.B. Leakey Foundation, the American Society of Primatologists, the Sigma Xi Foundation, the John F. Enders Foundation and Yale University provided support for the research.

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Journal Reference:

1. Hogan M. Sherrow. Adolescent Male Chimpanzees at Ngogo, Kibale National Park, Uganda, Have Decided Dominance Relationships. Folia Primatologica, 2012; 83 (2): 67 DOI: 10.1159/000341168

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20 Sep, 2012

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Antibiotic use aids MRSA spread in hospital and infection control measures do little to prevent it, says hospital study

ScienceDaily (Sep. 20, 2012) — The use of a commonly prescribed antibiotic is a major contributor to the spread of infection in hospitals by the 'superbug' MRSA, according to new research. The study also found that increasing measures to prevent infection -- such as improved hygiene and hand washing -- appeared to have only a small effect on reducing MRSA infection rates during the period studied.

MRSA -- methicillin-resistant Staphylococcus aureus -- is a bacteria that causes hospital-acquired infection and is resistant to all of the penicillin-type antibiotics frequently used in hospitals to prevent and treat infection. It can cause serious infections of the skin, blood, lungs and bones.

The researchers -- led by St George's, University of London -- tracked MRSA infection over 10 years from 1999 to 2009 at St George's Hospital, looking at how it has adapted to survive in a hospital environment and at factors that affected its prevalence. They found that a significant drop in MRSA rates coincided with a reduction in hospital prescriptions of ciprofloxacin, the most commonly prescribed antibiotic of the fluoroquinolone family.

Over a short period of the study, ciprofloxacin prescriptions fell from 70-100 daily doses for every thousand occupied beds to about 30 doses. In the same period, the number of patients identified by the laboratory to be infected with MRSA fell by half, from an average of about 120 a month to about 60. Following this, over the last two years of the study both the drug prescription level and MRSA rates remained at these reduced levels. Symptoms of MRSA infection can range from very mild to severe, but it is not known how many of the cases examined in the study were serious.

The study -- published in the Journal of Antimicrobial Chemotherapy -- looked at whether other factors such as improved infection control measures may have contributed to this decrease in infection. However, during a four-year period when more stringent infection control policies were introduced -- including improved cleaning and hand washing, and screening patients for MRSA on arrival at hospital -- the only major reduction in MRSA infection rates coincided with the reduction in ciprofloxacin prescriptions.

Lead author Dr Jodi Lindsay, a reader in microbial pathogenesis at St George's, University of London, said: "Surprisingly, it wasn't hygiene and hand washing that were the main factors responsible for the decrease in MRSA in the hospital. Rather, it seemed to be a change in the use of a particular group of antibiotics. Hand washing and infection control are important, but they were not enough to cause the decrease in MRSA we saw."

Dr Lindsay said the study suggested that MRSA relies on ciprofloxacin -- and fluoroquinolones in general -- to thrive in hospitals, as well as penicillin-type drugs, which was already assumed. The fluoroquinolone group of antibiotics have a similar enough mechanism of action to assume that the effect would be the same for them all.

She added that the findings suggest the most effective way to control MRSA and other hospital-based superbugs is to continue finding alternative ways to use antibiotics, rather than simply focusing on infection control techniques.

As well as identifying factors that influenced prevalence, the researchers identified the strain of MRSA that has become dominant. This strain -- CC22 -- has thrived by developing and maintaining multi-drug resistance, and becoming more fit to survive on hospital surfaces than other strains.

Dr Tim Planche, consultant microbiologist at St George's Healthcare NHS Trust and one of the co-authors of the study, said: "The Trust currently has infection rates among the lowest in London, having successfully driven acquisitions down over the past five or six years using a combination of both tough hygiene regimes and careful selective use of antibiotics. These findings, however, provide valuable insight and certainly warrant further investigation, which could lead to the development of even more effective infection control strategies in future."

Dr Lindsay said that studying the dynamic of how MRSA bacteria strains continue to evolve in hospitals in response to changing practice and interventions, such as infection control and antibiotic prescribing, will be essential to determine which interventions work, which are cost effective, and which are likely to have the best long-term outcomes.

She added: "But it seems that we now have an excellent opportunity to control superbugs in hospitals by re-examining how we prescribe antibiotics and ensuring we're using them in the most effective way possible."

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Journal Reference:

1. G. M. Knight, E. L. Budd, L. Whitney, A. Thornley, H. Al-Ghusein, T. Planche, J. A. Lindsay. Shift in dominant hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) clones over time. Journal of Antimicrobial Chemotherapy, 2012; 67 (10): 2514 DOI: 10.1093/jac/dks245

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20 Sep, 2012

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Landing pads being designed for extraterrestrial missions

ScienceDaily (Sep. 20, 2012) — When the Mars Science Laboratory's Curiosity rover landed on Aug. 6, it was another step forward in the effort to eventually send humans to the Red Planet. Using the lessons of the Apollo era and robotic missions to Mars, NASA scientists and engineers are studying the challenges and hazards involved in any extraterrestrial landing.

The technology is known as "vertical takeoff-vertical landing." According to a group working in NASA's Engineering and Technology Directorate at the Kennedy Space Center in Florida, the best approach requires a landing pad already be in place.

"One of the greatest challenges to Apollo astronauts landing on the moon was dust, rocks and debris obscuring their vision during the final part of the descent," said Rob Mueller, a senior technologist in Kennedy's Surface Systems Office and Lunar Destination co-lead for NASA's Human Spaceflight Architecture Team. "When the Apollo lunar modules reached the 30-meter point (about 100 feet), the dust was like a fog making it difficult to see their landing site. Similarly, photographs show there were some rocks and dust kicked up by the rocket engines on the sky-crane lowering the Curiosity lander onto the Martian surface."

As the Mars Science Laboratory's descent stage used rocket engines to hover, its sky crane lowered the Curiosity rover with a 25-foot tether to a soft landing on the surface.

Mueller and others are working on ways to develop landing pads that could be robotically constructed in advance of future human expeditions to destinations such as the moon or Mars. These specially constructed landing sites could greatly reduce the potential for blowing debris and improve safety for astronauts who make the trip to Mars or another destination.

"Our best estimates indicate that descent engines of the Apollo landers were ejecting up to one-and-a-half tons of rocks and soil," said Dr. Phil Metzger, a research physicist in Kennedy's Granular Mechanics and Regolith Operations Laboratory. "It will be even more challenging when we land humans on Mars. The rocket exhaust will dig a deep hole under the lander and fluidize the soil. We don't know any way to make this safe without landing pads."

Building a landing site in advance of human arrival is part of the plan.

"Robotic landers would go to a location on Mars and excavate a site, clearing rocks, leveling and grading an area and then stabilizing the regolith to withstand impact forces of the rocket plume," Mueller said. "Another option is to excavate down to bedrock to give a firm foundation. Fabric or other geo-textile material could also be used to stabilize the soil and ensure there is a good landing site."

Metzger explained that one of the ways to ensure an on-target landing would be to have robotic rovers place homing beacons around the site.

"Tracking and homing beacons would help a spacecraft reach the specific spot where the landing pad had been constructed," he said.

Landing pad technology may be perfected on Earth well in advance of its use elsewhere in the solar system.

"Several commercial space companies are already discussing returning rocket stages to Kennedy or Cape Canaveral saving on the cost of sending payloads to low Earth orbit," Mueller said. "Rather than the first stage simply falling into the ocean, the rocket would land vertically back here at the Cape to be reused."

While landing pads will provide a smooth touchdown location, they will also require advanced technology design and decisions on how large the landing pad should be.

"One of the factors we have to consider is the atmosphere where a landing will take place," Metzger said. "The Earth has a dense atmosphere that focuses the rocket exhaust onto the ground, but also reduces how far the ejected material is dispersed. Mars, on the other hand, has an atmospheric density that is 1 percent that of Earth. It still focuses the plume into a narrow jet that digs into the soil, but it provides less drag so the ejected soil will actually travel farther.

"Then compare that to the moon with no atmosphere," he said. "The plume won't be focused so it won't dig a deep hole in the soil, but the ejected material will travel vast distances at high velocity. It is like a sandblaster on steroids. So the requirements for a landing pad are determined by the destination we're landing on."

Metzger envisions circular landing pads from about 50 to 100 meters (about 165 to 330 feet) in diameter.

"The specialized material taking the heat of the engine plume would be in the middle," he said. "The area surrounding the center would be designed to hold up support equipment."

Another issue is what substances to use in building the landing pads.

"Tests with prototype landers show that while pads are safer than touching down on natural surfaces, certain pad materials can produce debris of their own," Metzger said. "A supersonic rocket exhaust becomes extremely hot when it impacts a surface. Asphalt or concrete are out of the question because the temperature causes those materials to break apart, throwing chunks of material in all directions."

During investigations of prototype landers, various materials have been examined on the pads from which the vehicles have vertically taken off and landed.

"We've tested several types of materials and it seems that basalt regolith mixed with polymer binders hold up well," Metzger said.

However, the one substance for landing pads that shows the most promise is the material used on spacecraft heat shields.

"Of all the substances we studied, ablative materials seem to work best," Metzger said.

Ablative substances were used on the heat shields for spacecraft during Mercury, Gemini and Apollo. The heat of re-entry was dissipated by burning off successive layers.

"While ablative materials seem to work well, the layers will eventually all burn away," Mueller said. "So next we may try reusable thermal protection material similar to that used on the space shuttle tiles or the Orion capsules."

A human expedition to Mars is still many years away, but Mueller says now is the time to start planning for how to land on another planet.

"The technology we envision will take 10 to 15 years to develop," he said. "We need to begin verifying that these concepts will work, and that's why we are already involved in the research."

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20 Sep, 2012

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Sudden cardiac death is associated with a thin placenta at birth, researchers find

ScienceDaily (Sep. 19, 2012) — Researchers studying the origins of sudden cardiac death have found that in both men and women a thin placenta at birth was associated with sudden cardiac death. A thin placenta may result in a reduced flow of nutrients from the mother to the fetus. The authors suggest that sudden cardiac death may be initiated by impaired development of the autonomic nervous system in the womb, as a result of fetal malnutrition.

The new study, published today in the International Journal of Epidemiology, also found that sudden death was associated independently with poor educational attainment. However, sudden cardiac death was not associated with maternal body size, fetal size at birth, or the length of gestation.

Professor David Barker and colleagues examined sudden death within the Helsinki Birth Cohort, which consists of 6075 men and 6370 women who were born in the city during 1934-1944 and attended child welfare clinics. Detailed information was recorded on the birth records of the group including the placental weight and the length and breadth of the placental surface as well as the child's weight, head circumference, and length.

Professor Barker, of the University of Southampton, comments that 'There is currently a growing body of research that shows that coronary heart disease is associated with alterations in prenatal growth and this has led to the hypothesis that coronary heart disease originates in the womb as a consequence of fetal malnutrition. In research recently carried out by myself and colleagues, we found that coronary heart disease among men was associated with altered shape and size of the placenta.'

'Our new research published today continues the investigation of the relationship between cardiac death and development within the womb. Our new findings suggest that sudden death may be initiated by the impaired development of the autonomic nervous system in the womb, due to placental thinness. A thin placenta may result in fetal malnutrition, due to a shallow invasion of the spiral arteries in the placenta which provide nutrients and blood to the baby. There is evidence that people who experience fetal malnutrition and who are small at birth have an increased sympopathoadrenal response to acute stress, which is known to be linked to death from cardiac arrest.'

Among women, sudden death was associated with a large placental area in comparison to the baby's weight. Placenta expansion in sheep is well documented and the findings in this study suggest that the placenta attempted to compensate for a thin surface by expanding the area of the surface. Professor Barker notes that 'there is evidence that compensatory placental expansion occurs in human and that this expansion may be beneficial in some circumstances. However, if the compensation is inadequate and the fetus continues to be under nourished then the need to share its nutrients with an enlarged placenta may become a metabolic burden and the quality of fetal development may be harmed. We believe that the female foetuses in our study compensated for placental thinness by expanding the placental surface.

Professor Barker and his team also found that sudden cardiac death was strongly associated with low socio-economic status and with low education attainment. He suggests that 'poor educational results may be due to a poor cognitive ability or other issues such as the inability to concentrate or maintain attention. We suggest that the association we have found between sudden death and poor educational attainment results from impaired prenatal development of the autonomic nervous system. These findings build upon a body of research that has consistently reported associations between sudden cardiac death and low socio-economic status.'

In the study, a total of one hundred and eighty-seven men (2.7%) and forty seven women (0.7%) suffered from sudden unexplained cardiac death outside of the hospital. The rate of sudden cardiac death among men and women increased with placental thinness, with a hazard ratio of 1.47. The authors restricted their analysis to deaths that occurred outside of hospital and were certified as coronary heart disease, with men and women who had never been admitted to hospital with coronary heart disease.

Professor Barker and his team do acknowledge that there are some limitations to the study. The placental measurements were made during routing obstetric practice 70 years ago and the quality of these measurements was not routinely checked and neither were other clinical measurements, such as blood pressure. The mean placental weight in this study was also more than the median recorded in a recent series of deliveries in Europe.

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The above story is reprinted from materials provided by Oxford University Press, via EurekAlert!, a service of AAAS.

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Journal Reference:

1. David JP Barker, Gail Larsen, Clive Osmond, Kent L Thornburg, Eero Kajantie, and Johan G Eriksson. The placental origins of sudden cardiac death. International Journal of Epidemiology, 2012; DOI: 10.1093/ije/dys116

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20 Sep, 2012

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Humans were already recycling 13,000 years ago, burnt artifacts show

ScienceDaily (Sep. 20, 2012) — A study at the Universitat Rovira i Virgili and the Catalan Institute of Human Paleoecology and Social Evolution (IPHES) reveals that humans from the Upper Palaeolithic Age recycled their stone artefacts to be put to other uses. The study is based on burnt artefacts found in the Molí del Salt site in Tarragona, Spain.

The recycling of stone tools during Prehistoric times has hardly been dealt with due to the difficulties in verifying such practices in archaeological records. Nonetheless, it is possible to find some evidence, as demonstrated in a study published in the 'Journal of Archaeological Science'.

"In order to identify the recycling, it is necessary to differentiate the two stages of the manipulation sequence of an object: the moment before it is altered and the moment after. The two are separated by an interval in which the artefact has undergone some form of alteration. This is the first time a systematic study of this type has been performed," as explained to SINC by Manuel Vaquero, researcher at the Universitat Rovira i Virgili.

The archaeologists found a high percentage of burnt remains in the Molí del Salt site (Tarragona), which date back to the end of the Upper Palaeolithic Age some 13,000 years ago. The expert ensures that "we chose these burnt artefacts because they can tell us in a very simple way whether they have been modified after being exposed to fire."

The results indicate that the recycling of tools was normal during the Upper Palaeolithic Age. However, this practice is not documented in the same way as other types of artefacts. The use of recycled tools was more common for domestic activities and seems to be associated with immediate needs.

Recycling domestic tools

Recycling is linked to expedited behaviour, which means simply shaped and quickly available tools as and when the need arises. Tools used for hunting, like projectile points for instance, were almost never made from recycled artefacts. In contrast, double artefacts (those that combine two tools within the same item) were recycled more often.

"This indicates that a large part of these tools were not conceived from the outset as double artefacts but a single tool was made first and a second was added later when the artefact was recycled," outlines the researcher. The history of the artefacts and the sequence of changes that they have undergone over time are fundamental in understanding their final morphology.

According to Vaquero, "in terms of the objects, this is mostly important from a cultural value point of view, especially in periods like the Upper Palaeolithic Age, in which it is thought that the sharper the object the sharper the mind."

Sustainable practices with natural resources

Recycling could have been determinant in hunter-gatherer populations during the Palaeolithic Age if we consider the behaviour of current indigenous populations nowadays.

"It bears economic importance too, since it would have increased the availability of lithic resources, especially during times of scarcity. In addition, it is a relevant factor for interpreting sites because they become not just places to live but also places of resource provision," states the researcher.

Reusing resources meant that these humans did not have to move around to find raw materials to make their tools, a task that could have taken them far away from camp. "They would simply take an artefact abandoned by those groups who previously inhabited the site."

Vaquero and the team believe that this practice needs to be borne in mind when analysing the site. "Those populating these areas could have moved objects from where they were originally located. They even could have dug up or removed sediments in search of tools," highlights the researcher.

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The above story is reprinted from materials provided by Plataforma SINC, via AlphaGalileo.

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Journal Reference:

1. Manuel Vaquero, Susana Alonso, Sergio García-Catalán, Angélica García-Hernández, Bruno Gómez de Soler, David Rettig, María Soto. Temporal nature and recycling of Upper Paleolithic artifacts: the burned tools from the Molí del Salt site (Vimbodí i Poblet, northeastern Spain). Journal of Archaeological Science, 2012; 39 (8): 2785 DOI: 10.1016/j.jas.2012.04.024

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20 Sep, 2012

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Invisible plastic particles in seawater damaging to sea animals

ScienceDaily (Sep. 20, 2012) — Plastic nanoparticles in seawater can have an adverse effect on sea organisms. Particles measuring about a thirty millionth of a millimetre, and therefore invisible to the naked eye, are responsible. Mussels that have been exposed to such particles eat less, and thus grow less well, according to research carried out by scientists and students at Wageningen University and IMARES, both part of Wageningen UR. They wrote about their research in the most recent issue of Environmental Toxicology and Chemistry.

The presence of 'plastic soup' in the oceans is regarded as a big problem. Tiny plastic particles enter the sea when plastic debris decomposes. Such particles are probably also released from cosmetics and from clothes in the wash, subsequently entering the sewage system and surface waters and eventually reaching the sea.

The EU and the Dutch government recognise the problem and the need to monitor the existence of plastics in the seas in order to learn more about present and future concentrations of plastic micro- and nanoparticles in marine environments. Very little is known about the effects plastic nanoparticles have on sea life. The effects now discovered do not yet prove that plastic in the North Sea is a big problem, but they do suggest that further research is extremely important, the researchers remark.

Professor Bart Koelmans' research team, from Wageningen University and IMARES, exposed mussels to various concentrations of nanoplastic in order to discover the concentration at which an effect was noticeable. The team also varied the quantity of algae -- the normal food source for mussels. By giving the plastic nanoparticles colour, and by measuring them using dynamic light scattering, it was possible to determine the particle concentration that exerted an effect. The researchers described in their publication that the extent to which the tiny plastic particles clump together is also extremely important for understanding particle uptake and the resulting effects in marine organisms. "It means that those effects are not easy to predict because the biological availability of the particles can differ enormously from one organism to another, and because variation in water quality also plays a role," says Prof. Koelmans.

Four research studies

This publication is the first of four by Wageningen University and IMARES into the effects of plastic in the North Sea. The other studies will be published in the near future. The first of these is research into the effect of plastic on lugworms, which lose weight due to uptake of plastic particles. The worms, as a result, take in more toxic substances such as polychlorinated biphenyls (PCBs), which bind to plastics.

The researchers believe this indicates the need for good research into other toxic substances that bind to plastic -- an additional consequence of the presence of microplastics. In order to analyse the interaction of plastic and other toxic substances in the food web, Koelmans' group has made a detailed computer model. This type of model is crucial for estimating the risks plastics impose in the sea. The last piece of research is into plastic debris in the stomachs of fish. An analysis of hundreds of fish has shown that 12% of them have debris in their stomachs. Around half of that debris is plastic.

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1. A. Wegner, E. Besseling, E.M. Foekema, P. Kamermans, A.A. Koelmans. Effects of nanopolystyrene on the feeding behavior of the blue mussel (Mytilus edulis L.). Environmental Toxicology and Chemistry, 2012; DOI: 10.1002/etc.1984

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20 Sep, 2012

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Invasive 'Rasberry Crazy Ant' in Texas now identified species

ScienceDaily (Sep. 19, 2012) — The Rasberry Crazy Ant is an invasive ant that was first noticed infesting areas around Houston, Texas ten years ago, but its species identity has remained undetermined until now.

In a paper published Sept. 19 in the open access journal PLOS ONE, a research team led by John LaPolla from Towson University in Maryland identifies the species as Nylanderia fulva. Identifying the species should help control this emerging pest, the authors write.

They also conclude that the species, whose common name comes from exterminator Tom Rasberry who first noticed the ants, is distributed more widely than previously thought and has likely invaded all Gulf Coast states.

"This study demonstrates the invaluable role that taxonomy, an often underappreciated discipline, plays in our understanding of emerging pests. Now that we know just what species the Rasberry Crazy Ant really is, we can better understand its biology to improve control of this invasive species," says LaPolla.

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1. Dietrich Gotzek, Seán G. Brady, Robert J. Kallal, John S. LaPolla. The Importance of Using Multiple Approaches for Identifying Emerging Invasive Species: The Case of the Rasberry Crazy Ant in the United States. PLoS ONE, 2012; 7 (9): e45314 DOI: 10.1371/journal.pone.0045314

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20 Sep, 2012

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Obese children have less sensitive taste-buds than those of normal weight

ScienceDaily (Sep. 19, 2012) — Obese kids have less sensitive taste-buds than kids of normal weight, indicates research published online in the Archives of Disease in Childhood.

This blunted ability to distinguish all five tastes of bitter, sweet, salty, sour, and umami (savoury) may prompt them to eat larger quantities of food in a bid to register the same taste sensation, suggest the authors.

They base their findings on 94 normal weight and 99 obese children aged between 6 and 18, who were in good health and not taking any medications known to affect taste and smell.

The taste sensitivity of every child was tested using 22 "taste strips" placed on the tongue, to include each of the five taste sensations, at four different levels of intensity, plus two blank strips.

Each child was asked to refrain from eating or drinking anything other than water and not to chew gum for at least an hour before they took the two tests, which involved identifying the different tastes and their intensity.

The sum of all five taste sensations at the four different intensities allowed for a maximum score of 20, with scores ranging from two to 19.

Girls and older children were better at picking out the right tastes.

Overall, the children were best able to differentiate between sweet and salty, but found it hardest to distinguish between salty and sour, and between salty and umami.

And obese children found it significantly more difficult to identify the different taste sensations, scoring an average of 12.6 compared with an average of just over 14 clocked up by children of normal weight.

Obese children were significantly less likely to identify the individual taste sensations correctly, particularly salty, umami, and bitter.

And while both obese and normal weight children correctly identified all the differing levels of sweetness, obese kids rated three out of the four intensity levels lower than kids of normal weight.

Similarly, children of normal weight were better able to distinguish the different taste sensations, the older they were, but this trend was not seen among the obese children.

Exactly why people have differing taste perceptions is unclear, but genes, hormones, acculturation and exposure to different tastes early in life are all thought to play a part, say the authors.

But previous research indicates that heightened sensitivity to different taste sensations may help to reduce the amount of food eaten as less is required to get the same "taste hit."

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Journal Reference:

1. Johanna Overberg, Thomas Hummel, Heiko Krude, Susanna Wiegand. Differences in taste sensitivity between obese and non-obese children and adolescents. Archives of Disease in Childhood, 2012; DOI: 10.1136/archdischild-2011-301189

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

20 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/DN4CU5hoO7Q/120919190924.htm
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NASA Mars rover targets unusual rock enroute to first destination

ScienceDaily (Sep. 19, 2012) — NASA's Mars rover Curiosity has driven up to a football-size rock that will be the first for the rover's arm to examine.

Curiosity is about 8 feet (2.5 meters) from the rock. It lies about halfway from the rover's landing site, Bradbury Landing, to a location called Glenelg. In coming days, the team plans to touch the rock with a spectrometer to determine its elemental composition and use an arm-mounted camera to take close-up photographs.

Both the arm-mounted Alpha Particle X-Ray Spectrometer and the mast-mounted, laser-zapping Chemistry and Camera Instrument will be used for identifying elements in the rock. This will allow cross-checking of the two instruments.

The rock has been named "Jake Matijevic." Jacob Matijevic (mah-TEE-uh-vik) was the surface operations systems chief engineer for Mars Science Laboratory and the project's Curiosity rover. He passed away Aug. 20, at age 64. Matijevic also was a leading engineer for all of the previous NASA Mars rovers: Sojourner, Spirit and Opportunity.

Curiosity now has driven six days in a row. Daily distances range from 72 feet to 121 feet (22 meters to 37 meters).

"This robot was built to rove, and the team is really getting a good rhythm of driving day after day when that's the priority," said Mars Science Laboratory Project Manager Richard Cook of NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The team plans to choose a rock in the Glenelg area for the rover's first use of its capability to analyze powder drilled from interiors of rocks. Three types of terrain intersect in the Glenelg area -- one lighter-toned and another more cratered than the terrain Curiosity currently is crossing. The light-toned area is of special interest because it retains daytime heat long into the night, suggesting an unusual composition.

"As we're getting closer to the light-toned area, we see thin, dark bands of unknown origin," said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology, Pasadena. "The smaller-scale diversity is becoming more evident as we get closer, providing more potential targets for investigation."

Researchers are using Curiosity's Mast Camera (Mastcam) to find potential targets on the ground. Recent new images from the rover's camera reveal dark streaks on rocks in the Glenelg area that have increased researchers' interest in the area. In addition to taking ground images, the camera also has been busy looking upward.

On two recent days, Curiosity pointed the Mastcam at the sun and recorded images of Mars' two moons, Phobos and Deimos, passing in front of the sun from the rover's point of view. Results of these transit observations are part of a long-term study of changes in the moons' orbits. NASA's twin Mars Exploration Rovers, Spirit and Opportunity, which arrived at Mars in 2004, also have observed solar transits by Mars' moons. Opportunity is doing so again this week.

"Phobos is in an orbit very slowly getting closer to Mars, and Deimos is in an orbit very slowly getting farther from Mars," said Curiosity's science team co-investigator Mark Lemmon of Texas A&M University, College Station. "These observations help us reduce uncertainty in calculations of the changes."

In Curiosity's observations of Phobos this week, the time when the edge of the moon began overlapping the disc of the sun was predictable to within a few seconds. Uncertainty in timing is because Mars' interior structure isn't fully understood.

Phobos causes small changes to the shape of Mars in the same way Earth's moon raises tides. The changes to Mars' shape depend on the Martian interior which, in turn, cause Phobos' orbit to decay. Timing the orbital change more precisely provides information about Mars' interior structure.

During Curiosity's two-year prime mission, researchers will use the rover's 10 science instruments to assess whether the selected field site inside Gale Crater ever has offered environmental conditions favorable for microbial life.

For more about Curiosity, visit: http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl. You can follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity.

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The above story is reprinted from materials provided by NASA/Jet Propulsion Laboratory.

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20 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/y4WTxiUu07w/120919201958.htm
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Promise of cell therapy for bowel disease

ScienceDaily (Sep. 19, 2012) — New research shows that a special population of stem cells found in cord blood has the innate ability to migrate to the intestine and contribute to the cell population there, suggesting the cells' potential to treat inflammatory bowel disease (IBD).

"These cells are involved in the formation of blood vessels and may prove to be a tool for improving the vessel abnormalities found in IBD," said lead author Graca Almeida-Porada, M.D., Ph.D., a professor at Wake Forest Baptist Medical Center's Institute for Regenerative Medicine. The research is published in the current print issue of the journal Hepatology.

Up to 1 million Americans have IBD, which is characterized by frequent diarrhea and abdominal pain. IBD actually refers to two conditions -- ulcerative colitis and Crohn's disease -- in which the intestines become red and swollen and develop ulcers. With IBD, blood vessels in the intestine leak and contribute to inflammation.

While there is currently no cure for IBD, there are drug therapies aimed at reducing inflammation and preventing the immune response. However, these therapies aren't always effective. The long-term aim of the research is to develop an injectable cell therapy to induce tissue recovery.

The work, performed while Almeida-Porada was at the University of Nevada, also involved colleagues from Indiana University School of Medicine. The researchers studied a special population of cells, known as endothelial colony-forming cells, found in cord blood, bone marrow and circulating blood. The finding in 1997 that the cells can contribute to blood vessel formation in adults, not just embryos, initiated the notion of using them for therapy. Studies in humans have validated the ability of these cells to improve reduced blood flow to the limbs and to treat heart diseases.

However, there have been few studies to explore the inherent biologic ability of these cells to home to different organs and contribute to tissue-specific cell populations. Evaluating their potential to migrate to the intestine was an obvious choice, said Almeida-Porada, because dysfunctional blood vessels are a hallmark of IBD. Not only are circulating levels of vessel-forming cells reduced in patients with IBD, but a key factor in IBD progression is the development of abnormal or immature blood vessels, which leads to chronic inflammation.

The cells were injected into fetal sheep at 59 to 65 days gestation. About 11 weeks later, intestinal tissue was analyzed to detect the presence of the human cells. The researchers found that the human cells had migrated to the intestine and contributed significantly to the cell population there.

"This study shows that the cells can migrate to and survive in a healthy intestine and have the potential to support vascular health," said Almeida-Porada. "Our next step will be to determine whether the cells can survive in the 'war' environment of an inflamed intestine."

The researchers also evaluated the ability of the cells to home to the liver. Smaller numbers of cells reached the liver than the intestine, suggesting that new strategies would be needed to enhance the therapeutic potential for this organ.

The research was supported by the National Heart, Lung, and Blood Institute grants HL097623 and HL073737.

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Story Source:

The above story is reprinted from materials provided by Wake Forest Baptist Medical Center, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Joshua A. Wood, Evan Colletti, Laura E. Mead, David Ingram, Christopher D. Porada, Esmail D. Zanjani, Mervin C. Yoder, Graça Almeida-Porada. Distinct contribution of human cord blood-derived endothelial colony forming cells to liver and gut in a fetal sheep model. Hepatology, 2012; 56 (3): 1086 DOI: 10.1002/hep.25753

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Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

20 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/~3/tFXiL2WUFPg/120919190110.htm
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