Scientific Frontline Communication Center

Call for Decade of Vaccines

SFL ORG. Educational News Network — Mon, 01 Feb 2010 16:14:37 +0000

Call for Decade of Vaccines

Monday, February 1, 2010

Bill and Melinda Gates announced that their foundation will commit $10 billion over the next 10 years to help research, develop and deliver vaccines for the world's poorest countries. The Gateses said that increased investment in vaccines by governments and the private sector could help developing countries dramatically reduce child mortality by the end of the decade, and they called for others to help fill critical financing gaps in both research funding and childhood immunization programs. Bill and Melinda Gates made their announcement at the World Economic Forum's Annual Meeting, where they were joined by Julian Lob-Levyt, CEO of the GAVI Alliance.

Source: Bill & Melinda Gates Foundation

Permalink: http://www.sflorg.com/comm_center/announcements/p988_23.html

Time Stamp: 2/1/2010 at 3:52:00 PM UTC

Researchers Discover a Way to Strengthen Proteins

SFL ORG. Educational News Network — Thu, 10 Dec 2009 17:36:58 +0000

Researchers Discover a Way to Strengthen Proteins

Thursday, December 10, 2009

Proteins, which perform such vital roles in our bodies as building and maintaining tissues and regulating cellular processes, are a finicky lot. In order to work properly, they must be folded just so, yet many proteins readily collapse into useless tangles when exposed to temperatures just a few degrees above normal body temperature.

This precarious stability leaves proteins and the living beings that depend upon them on the edge of a precipice, where a single destabilizing change in a key protein can lead to disease or death. It also greatly complicates the manufacture and use of proteins in research and medicine.

Finding a way to stabilize proteins could help prevent such dire consequences, reduce the very high cost of protein drugs and perhaps also help scientists understand why proteins are often so unstable in the first place. In a paper published in the Dec. 11 issue of the journal Molecular Cell, researchers at the University of Michigan and the University of Leeds describe a new strategy for stabilizing specific proteins by directly linking their stability to the antibiotic resistance of bacteria.

"The method we developed should provide an easy way to strengthen many proteins and by doing so increase their practical utility," said James Bardwell, a Howard Hughes Medical Institute investigator and professor of molecular, cellular and developmental biology at U-M.

In the new approach, the researchers found that when a protein is inserted into the middle of an antibiotic resistance marker, bacterial antibiotic resistance becomes dependent upon how stable the inserted protein is. This enabled the scientists to easily select for stabilizing mutations in proteins by using a simple life-or-death test for bacterial growth on antibiotics. The mutations the scientists identified rendered proteins more resistant to unfolding.

"This method also has allowed us to catch a glimpse of why proteins may need to be just barely stable," said Linda Foit, the graduate student at U-M who initiated the work. "The mutations that we found to enhance the stability of our model protein are mostly in key areas related to the protein's function, suggesting that this protein may need to be flexible and therefore marginally stable in order to work. It may be that, over the course of evolution, natural selection acts to optimize, rather than maximize protein stability."

The work was conducted in the laboratories of Bardwell at U-M and Sheena Radford at the University of Leeds and spearheaded by Foit in Bardwell's lab and postdoctoral fellow Gareth Morgan in the Radford lab. In addition to these researchers, the paper's authors are U-M undergraduate students Maximilian Kern, Lenz Steimer and Anne Kathrin von Hacht and Leeds technician James Titchmarsh and senior lecturer Stuart Warriner. The research was funded in part by the Howard Hughes Medical Institute, the National Institutes of Health, the Wellcome Trust and the University of Leeds.

Source: University of Michigan

Permalink: http://www.sflorg.com/comm_center/unv_science/987_255.html

Time Stamp: 12/10/2009 at 5:15:17 PM UTC

Aussie galaxy survey to lead to "new physics"

SFL ORG. Educational News Network — Thu, 10 Dec 2009 16:56:05 +0000

Aussie galaxy survey to lead to "new physics"

Thursday, December 10, 2009

Australian astronomers have released the first set of data from the first project to look at the effects of "dark energy" halfway back in the Universe's lifetime.

Called WiggleZ ("wiggles"), the project is being done with the Anglo-Australian Telescope in NSW and is led by Professor Michael Drinkwater of UQ's School of Mathematics and Physics.

Dark Energy is an unidentified component of the Universe that is causing the expansion of the Universe to speed up.

Determining its nature is one of the key problems of physics today, and will lead to a "new understanding of physics," Professor Drinkwater said.

WiggleZ will get a handle on Dark Energy by measuring "wiggles" in the distribution of distant galaxies.

Because light takes time to travel through the Universe, looking far out is equivalent to looking back in time, and WiggleZ is observing galaxies that existed when the Universe was half its present age.

"By observing the size of the pattern at different times in the Universe's history, we can track the history of the expansion of the Universe, and thus determine the effects of Dark Energy," Professor Warrick Couch of Swinburne University, a member of the WiggleZ team, said.

The "wiggles" pattern in galaxies in today's Universe was discovered in 2004 by two teams, one of which had used the Anglo-Australian Telescope for its galaxy survey.

WiggleZ will measure the redshifts (distances) of 240,000 galaxies, allowing astronomers to create a 3D map of galaxies stretching over a thousand square degrees on the sky and look for a pattern in the way they are clustered on large scales.

These galaxies are about halfway back in the Universe's history (4 to 8 billion years ago, corresponding to redshifts of between 0.2 and 1).

WiggleZ started in 2006 and, when finished in 2010, will be the largest galaxy redshift survey made to that time in terms of the volume of space it covers at such remote distances in the universe.

More than a dozen ground-based Dark Energy projects are proposed or under way, and at least four space-based missions, each of the order of a billion dollars, are at the design concept stage.

While the exact nature of Dark Energy is still unknown, there are only a few candidates.

A favored one is the energy of empty space itself. But it could also be that Einstein's general theory of relativity, our current theory of gravity, is wrong on large scales.

Another approach to tracking the effects of Dark Energy is to look at the brightness of distant supernovae (exploding stars), and compare them with the brightness predicted for that time in the Universe's history. This is how Dark Energy was discovered in the first place.

However, there are uncertainties associated with the supernova approach related to how close in brightness all the supernovae are.

"The galaxy clustering method also has uncertainties, but completely independent ones, so the two methods provide a powerful cross-check to each other," Dr Sarah Brough, a WiggleZ team member at the Anglo-Australian Observatory in Sydney, said.

The first WiggleZ data release, of 100,000 galaxies, is published in association with a paper in Monthly Notices of the Royal Astronomical Society.

Image Caption: Time goes from top to bottom. The "bullseyes" show where there have been two sources of pressure waves in the early universe, the waves traveling outwards like the ripples on a pond. Galaxies prefer to grow at the center and edge of the bullseye. Their preferred separation is the radius of the bullseye (the scale bar).

Image Credit: Sam Moorefield, Swinburne University

Source: University of Queensland

Permalink: http://www.sflorg.com/comm_center/unv_space/p986_40.html

Time Stamp: 12/10/2009 at 4:38:37 PM UTC

Flying Dinosaur Controversy Resolved

SFL ORG. Educational News Network — Thu, 10 Dec 2009 01:16:56 +0000

Flying Dinosaur Controversy Resolved

Thursday, December 10, 2009

New research appears to have ended a scientific debate that has vexed palaeontologists for almost 100 years.

Flying reptiles called pterosaurs ruled the Earth's skies for over 130 million years and died out 65 million years ago.

The aerodynamics of the membrane stretched over the huge 12-meter wing span would have influenced the way these animals could fly, but scientists have not been able to agree on the orientation of a particular wing-bone that controlled the shape of this membrane.

Since 1914, there have been two theories on the positioning of the pteriod, a unique wing-bone at the front of the pterosaur wing. One argues that it must have been positioned sideways, while the other suggests that it pointed forwards.

Using biomechanical analysis and testing aerodynamic efficiency, new findings by researchers from the University of Bristol, UK, and University College Dublin, Ireland, suggest that the only conceivable positioning of the wing bone is a sideways orientation.

"Based on existing fossil evidence, pterosaurs are believed to have had a wing span of up to 12 meters and a weight of between 80 and 250 kilograms," says Colin Palmer from the University of Bristol and lead author on the paper.

"In our analysis we show that a forward pointing pteriod would not have been able to withstand the stresses and strains involved in the take off and flight of such a large animal."

"The structure of the pterosaur wing must have afforded a high safety margin above what was required to support flight in such a massive animal, in order to prevent against any possible breakage or damage which would be catastrophic for the animal. And a forward pointing pteriod would not afford such a safety margin," explains Palmer.

"We were working to reconstruct how these enormous reptiles flew - how they took to the air, how they landed, and how they made their living in flight," says Dr Gareth Dyke from University College Dublin, the papers co-author.

"The direction of the pteriod bone has a major impact on the aerodynamics and performance of the pterosaur wing. A sideways orientation implies a faster flyer."

"It affects the speed at which they could fly, which could tell you about the type of life they led, where they lived, and possibly even what they ate. They are the biggest animals ever take to the skies," says Dyke.

The research is published online this week in the Proceedings of The Royal Society B.

Source: University of Bristol

Permalink: http://www.sflorg.com/comm_center/unv_science/p985_254.html

Time Stamp: 12/10/2009 at 12:57:48 AM UTC

Non-Invasive Technique Blocks a Conditioned Fear in Humans

SFL ORG. Educational News Network — Wed, 09 Dec 2009 19:19:34 +0000

Non-Invasive Technique Blocks a Conditioned Fear in Humans

Wednesday, December 9, 2009

Scientists have for the first time selectively blocked a conditioned fear memory in humans with a behavioral manipulation. Participants remained free of the fear memory for at least a year. The research builds on emerging evidence from animal studies that reactivating an emotional memory opens a 6-hour window of opportunity in which a training procedure can alter it.

"Our results suggest a non-pharmacological, naturalistic approach to more effectively manage emotional memories," said Elizabeth Phelps, Ph.D., of New York University, a grantee of the National Institutes of Health's National Institute of Mental Health (NIMH).

Phelps and NIMH grantee and NYU colleague Joseph LeDoux, Ph.D., led the research team that reports on their discovery online Dec. 9, 2009 in the journal Nature.

"Inspired by basic science studies in rodents, these new findings in humans hold promise for being translated into improved therapies for the treatment of anxiety disorders, such as post-traumatic stress disorder (PTSD)," said NIMH Director Thomas R. Insel, M.D.

The results add support to the hypothesis that emotional memories are reconsolidated -- rendered vulnerable to being modified -- each time they are retrieved. That is, reactivating a memory opens what researchers call "reconsolidation window," a time-limited period when it can be changed.

"This adaptive update mechanism appears to have evolved to allow new information available at the time of retrieval to be incorporated into the brain's original representation of the memory," explained Phelps.

Earlier this year, LeDoux and colleagues exploited this potentially clinically important insight to erase a fear memory in rats. They first conditioned rats to fear a tone by pairing it with intermittent shocks. A day later, the rats were re-exposed to the tone, reactivating the fear memory. They then underwent a process to rewrite the fear, called extinction training, in which the tone was repeatedly presented without shocks.

However, the timing of this extinction training proved critical. Fear of the stimulus was erased only in rats trained within a 6-hour reconsolidation window after re-exposure to the feared tone. Fear responses returned in animals trained after the window closed, when the memory had apparently already solidified.

Normally, extinction training suppresses but does not erase the original fear memory. By first reactivating it -- sounding the tone -- just prior to extinction training, LeDoux and colleagues permanently erased the fear memory. In the new study, Phelps and colleagues similarly conditioned human participants to fear colored squares by intermittently pairing them with mild wrist shocks.

As with the rats, a day later, the memory was first reactivated by re-exposing participants to the feared squares. A measure of nervous system arousal confirmed that they experienced a fear response. Extinction training -- repeated trials of exposure to the colored squares without shocks -- followed.

Again as in the rats, a day later, the fear response was banished only in human participants who underwent the extinction training soon after the fear reactivation. Those trained after the 6-hour consolidation window remained afraid of the squares -- as did a control group that received extinction training without first experiencing reactivation of the fear memory.

In a follow-up experiment to gauge long-term effects a year later, 19 of the original participants received a potent regimen to re-instate the fear: four shocks followed by presentations of the colored squares.

Remarkably, those who had undergone extinction training within the reconsolidation window were largely spared significant effects. By contrast, those whose training had been delayed 6 hours or who hadn't experienced fear memory reactivation prior to extinction training experienced significant reinstatement of the fear response.

In a similar experiment, the researchers also confirmed that the fear memory was blocked only for the specific colored square for which fear memory was reactivated prior to extinction training. The effect did not generalize to a differently colored square associated with the shocks. This indicated that memory re-writing during reconsolidation is highly specific and that prior reactivation with the specific stimuli is critical.

"Timing may have a more important role in the control of fear than previously appreciated," Phelps suggested. "Our memory reflects our last retrieval of it rather than an exact account of the original event."

Evidence suggests that the behavioral manipulation may work through the same molecular mechanisms as experimental medications under study for quelling traumatic emotional memories.

"Using a more natural intervention that captures the adaptive purpose of reconsolidation allows a safe and easily implemented way to prevent the return of fear," suggest the investigators.

The mission of the NIMH is to transform the understanding and treatment of mental illnesses through basic and clinical research, paving the way for prevention, recovery and cure.

More Information: Anxiety Disorders

More Information: Post-Traumatic Stress Disorder (PTSD)

Source: NIH

Permalink: http://www.sflorg.com/comm_center/medical/p984_100.html

Time Stamp: 12/9/2009 at 7:01:12 PM UTC

Lockheed Martin Cryostat To Fly On NASA's Wide-Field Infrared Survey Explorer Mission

SFL ORG. Educational News Network — Wed, 09 Dec 2009 18:45:37 +0000

Lockheed Martin Cryostat To Fly On NASA's Wide-Field Infrared Survey Explorer Mission

Wednesday, December 9, 2009

NASA's Wide-Field Infrared Survey Explorer (WISE) -- scheduled for launch on Dec. 11, 2009 from Vandenberg Air Force Base, Calif. -- will scan the entire sky in infrared light, picking up the glow of hundreds of millions of objects and producing millions of images. Two Thermos-like annular tanks filled with solid hydrogen, called a dual-stage cryostat, built by the Lockheed Martin Space Systems Company [NYSE: LMT] Advanced Technology Center (ATC) in Palo Alto, will keep the mission's sensitive infrared telescope and detectors chilled to near absolute zero. Expected to last about 10 months, the solid hydrogen cryostat will cool the WISE focal plane to 7.6 Kelvin (minus 446 Fahrenheit) and the optics to 12 Kelvin (minus 438 degrees Fahrenheit).

"After years of effort, it is very satisfying to finally reach the milestone of launch," said Iran Spradley, Senior Manager of the Thermal Sciences Department at the ATC. "We look forward with anticipation to the many discoveries that WISE is sure to make, and are enormously pleased to have played a role in this very important mission."

"Being a part of the WISE mission will always be a highlight in my career," said Larry Naes, recently retired Lockheed Martin WISE cryostat program manager. "From the very beginning of the program, our colleagues at the Jet Propulsion Laboratory assembled the best of the best to implement this mission, with a singular team focus to optimize the science and produce data that will contribute greatly to our understanding of the infrared universe."

The WISE mission will build on the heritage of NASA's very successful Infrared Astronomical Satellite (IRAS) launched in 1983. WISE, however, will have hundreds of times greater sensitivity and will uncover objects never before seen, including the coolest stars and the most luminous galaxies in the universe. The vast catalogs of infrared objects generated by WISE will help answer fundamental questions about the origins of planets, stars and galaxies, and provide astronomers a treasure trove of data that will be accessed for decades.

It is near-Earth objects, both asteroids and comets with orbits that come close to crossing Earth's path that will be the closest of WISE's discoveries. It is expected that WISE will find hundreds of these, and hundreds of thousands of additional asteroids in the main asteroid belt between Mars and Jupiter. By measuring the objects' infrared light, astronomers will get the first good estimate of the size distribution of the asteroid population. This information will reveal approximately how often Earth can expect an encounter with a potentially hazardous asteroid.

WISE will orbit Earth at an altitude of 326 miles, circling pole to pole about 15 times each day. A scan mirror within the WISE instrument will stabilize the line of sight so that snapshots can be taken every 11 seconds over the entire sky. Each position on the sky will be imaged a minimum of eight times, and some areas near the poles will be imaged more than 1,000 times. About 7,500 images will be taken every day at four different infrared wavelengths.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate. The mission's principal investigator, Edward L. (Ned) Wright, is at UCLA. The mission was competitively selected in 2002 under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp, Boulder, Colo. Science operations and data processing will take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. The mission's education and public outreach office is based at the University of California, Berkeley.

The ATC is the research and development organization of Lockheed Martin Space Systems Company (LMSSC). LMSSC, a major operating unit of Lockheed Martin Corporation, designs and develops, tests, manufactures and operates a full spectrum of advanced-technology systems for national security and military, civil government and commercial customers. Chief products include human space flight systems; a full range of remote sensing, navigation, meteorological and communications satellites and instruments; space observatories and interplanetary spacecraft; laser radar; ballistic missiles; missile defense systems; and nanotechnology research and development.

Headquartered in Bethesda, Md., Lockheed Martin is a global security company that employs about 140,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services. The corporation reported 2008 sales of $42.7 billion.

Source: Lockheed Martin

Permalink: http://www.sflorg.com/comm_center/lockheed_martin/p983_32.html

Time Stamp: 12/9/2009 at 6:23:02 PM UTC

Boeing Successfully Completes 747-8 Freighter Engine Runs

SFL ORG. Educational News Network — Wed, 09 Dec 2009 18:06:46 +0000

Boeing Successfully Completes 747-8 Freighter Engine Runs

Wednesday, December 9, 2009

Boeing (NYSE: BA) successfully completed the first engine runs for the 747-8 Freighter. The milestone marks another step in the 747 program's steady progress in preparing for flight test.

"We are very pleased with the engines' performance during this test," said Mo Yahyavi, vice president and general manager of the 747 program. "The engines and all the systems performed as expected."

Engine runs began slightly before 10 a.m. (PST) Tuesday. During initial engine runs, the engines are started and operated at various power settings to ensure all systems perform as expected. The engine run test began with the auxiliary power system providing power to start the first of four General Electric GEnx-2B engines. The remaining three engines were started using the cross-bleed function.

Basic systems checks continued throughout the test. The engines were powered down and inspected and will be restarted following a technical review. The team completed a vibration check and monitored the shutdown logic to ensure it functioned as expected.

"This milestone is an exciting one for the GEnx-2B team and we anticipate the engines will continue the same high performance that we have experienced in our ground and flight tests," said Tom Brisken, general manager of the GEnx Program at GE Aviation.

The GEnx-2B engine is optimized for the 747-8. It helps provide customers with improved fuel efficiency, reductions in emissions and noise and a lower cost of ownership.

Image Caption: General Electric GEnx-2B engines.

Image Credit: The Boeing Company

Source: The Boeing Company

Permalink: http://www.sflorg.com/comm_center/boeing/p982_35.html

Time Stamp: 12/9/2009 at 5:45:12 PM UTC

Lockheed Martin Receives Trident II D5 Missile System Production And Support Contract

SFL ORG. Educational News Network — Wed, 09 Dec 2009 05:40:20 +0000

Lockheed Martin Receives Trident II D5 Missile System Production And Support Contract

Wednesday, December 9, 2009

The U.S. Navy is awarding Lockheed Martin (NYSE: LMT) a contract with a value not to exceed $851 million for production and deployed system support for the Trident II D5 Fleet Ballistic Missile (FBM) program for fiscal year 2010.

Under the contract, Lockheed Martin is providing D5 missile hardware production support and reentry system hardware, as well as operations and maintenance to support the readiness and reliability of missile systems deployed aboard the Navy's Trident II OHIO-class submarines. The contract also continues the D5 Life Extension effort, which updates selected electronic components to support the extended service life of the Navy's OHIO-class submarines.

"Under the leadership of the Navy's Strategic Systems Program, the Fleet Ballistic Missile program sets the standard for partnership, disciplined performance and continual improvement," said Melanie A. Sloane, vice president of Fleet Ballistic Missile programs, Lockheed Martin Space Systems Company. "We are dedicated to supporting the Navy as it continues to raise the bar on this critically important program."

First deployed in 1990, the D5 missile is currently aboard OHIO-class submarines and British VANGUARD-class submarines. Lockheed Martin completed D5 missile deliveries for the U.S. inventory objective in 2007. The three-stage, solid-propellant, inertial-guided ballistic missile can travel a nominal range of 4,000 nautical miles and carries multiple independently targeted reentry vehicles.

Lockheed Martin Space Systems Company, Sunnyvale, Calif., is the prime contractor and program manager for the U.S. Navy's Trident missile. Approximately 2,400 Lockheed Martin Space Systems employees, principally in California, Georgia, Florida, Washington, Utah and Virginia, support the design, development, production, test and operation of the Trident Strategic Weapon System. Lockheed Martin Space Systems has been the Navy's prime strategic missile contractor since the inception of the program more than 50 years ago.

Source: Lockheed Martin

Permalink: http://www.sflorg.com/comm_center/lockheed_martin/p981_31.html

Time Stamp: 12/9/2009 at 5:27:15 AM UTC

H1N1 Influenza Adopted Novel Strategy to Move from Birds to Humans

SFL ORG. Educational News Network — Wed, 09 Dec 2009 05:10:15 +0000

H1N1 Influenza Adopted Novel Strategy to Move from Birds to Humans

Wednesday, December 9, 2009

The 2009 H1N1 influenza virus used a new strategy to cross from birds into humans, a warning that it has more than one trick up its sleeve to jump the species barrier and become virulent.

In a report in this week's early online edition of the journal Proceedings of the National Academy of Sciences, University of California, Berkeley, researchers show that the H1N1, or swine flu, virus adopted a new mutation in one of its genes distinct from the mutations found in previous flu viruses, including those responsible for the Spanish influenza pandemic of 1918, the "Asian" flu pandemic in 1957 and the "Hong Kong" pandemic of 1968.

Previous influenza strains that crossed from birds into people had a specific point mutation in the bird virus's polymerase gene that allowed the protein to operate efficiently inside humans as well. The polymerase transcribes the virus's RNA, allowing the host to express viral genes, and also copies the viral genome, needed to make new viruses.

The 2009 H1N1 virus retains the bird version of the polymerase, but has a second mutation that seems to suppress the ability of human cells to prevent the bird polymerase from working.

"We were quite shocked when we looked at the swine flu virus, which was clearly replicating in people and other mammalian systems, yet had a polymerase that looked like it was derived from a bird virus, which should not function too well in a human cell type," said UC Berkeley post-doctoral fellow Andrew Mehle of the Department of Molecular and Cell Biology. "The other mutation within the polymerase seems to compensate and allow the enzyme to function."

The researchers also discovered another strategy -- one not yet adopted by any known flu virus -- by which influenza virus can increase its virulence even more. When a particular human subunit is substituted for one of the three protein subunits that make up the bird polymerase, the new combination makes the polymerase more efficient in human cells.

"This is an extremely rare mutation and a rare combination, which suggests that there may be other ways that haven't emerged yet that these viruses are going to continue to evolve," said Jennifer Doudna, UC Berkeley professor of molecular and cell biology and an investigator in the Howard Hughes Medical Institute.

"As mechanistic biologists, we are hoping that by understanding how the virus works at the molecular level, we will be able to predict with more accuracy how it will evolve."

She suggested that those monitoring influenza outbreaks around the world in search of new variants be on the lookout for this recombination of polymerase subunits, which could herald an uptick in swine flu virulence. The findings also could help scientists develop better antiviral treatments, Mehle and Doudna said.

"The more we can understand the biochemistry and the particular structure of these polymerase complexes, the better we can make rational decisions about drug development," Mehle said.

H1N1, which appeared on the scene earlier this year, was dubbed swine flu because it emerged from pigs, in which human, bird and pig influenza viruses mixed, swapped genes and gave rise to a variant that could infect human cells and reproduce.

While mutations in the surface protein hemagglutinin -- indicated by the H in H1N1 -- are key to allowing the virus to enter human cells, mutations in the polymerase enzyme are key to the virus's ability to replicate inside human cells. All previous flu strains that entered and were transmitted in humans had a single mutation in the second subunit of the bird polymerase gene, which apparently allowed the enzyme to operate in human cells.

Last year, Mehle and Doudna showed that human cells apparently prevent the three subunits of bird virus polymerases from assembling into a functioning enzyme. A single amino acid switch at position 627 on the second subunit of the polymerase overcomes that inhibition and allows the virus to replicate. Apparently, Mehle said, when the amino acid glutamic acid -- typical of most bird virus polymerases -- is changed to a lysine, typical of human polymerases, the surface charge of the subunit changes from acidic (negatively charged) to basic (positively charged) and allows assembly of the subunits. Previous studies in mammals have shown that a lysine in that position enhances polymerase activity, increases viral replication and transmission, and in some cases, is associated with increased pathogenicity and death.

In their new study, Mehle and Doudna found that H1N1 has two rare mutations in the second subunit: a serine at position 590 and an arginine at position 591. This combination, which is most common in pigs, apparently has the same effect on surface charge as the mutation at position 627, allowing the polymerase complex to form and function in human cells.

Mehle noted that, in addition to such point mutations, flu viruses also mix and match the three subunits. Both the 1957 and 1968 viruses had polymerases composed of a first subunit from a bird and the other two subunits from humans. H1N1 has a human-like first subunit, while the second and third are bird-like -- hence the need for a mutation in the second subunit to make it more human-like.

To see which other combinations might make H1N1 more virulent, they mixed human, avian and pig subunits in culture, replicating the pig "mixing vessel," Mehle said. Several combinations with a human third subunit increased the activity of the polymerase enzyme when other mutations were not present in the second subunit. Viruses with this alteration are now being tested in human cell culture to see if they are more virulent.

"In addition to having individual amino acid changes affecting the ability of the virus to transmit across species and be more pathogenic, we need to think about these entire gene segments being exchanged back and forth," said Doudna, who also is a faculty affiliate of the California Institute for Quantitative Biosciences (QB3). "Those will affect the outcome of disease."

"We are very hopeful that the kind of basic science that we are doing here will have an impact on human health, either at the level of diagnostics or thinking forward to development of antiviral therapeutics," she added.

Mehle and Doudna continue to explore the polymerase to discover what in human cells prevents the assembly of the bird polymerase, and to determine the three-dimensional structure of the enzyme and its three subunits.

The work was supported by the National Institute of General Medical Sciences of the National Institutes of Health.

Image Caption: The sequence of the three subunits of the influenza virus polymerase (center) determines whether or not the enzyme works efficiently in birds, pigs or humans. A mutation in the PB2 subunit allows the bird virus to function in humans, as does switching out the bird PA subunit for a human PA subunit. Two mutations in the PB2 subunit of 2009 H1N1 allow the pig virus to work in humans. The background is a false-color electron micrograph image of influenza virions.

Image Credit: Andrew Mehle / University of California, Berkeley

Source: University of California, Berkeley

Permalink: http://www.sflorg.com/comm_center/unv_science/p980_253.html

Time Stamp: 12/9/2009 at 4:46:00 AM UTC

Umbilical Stem Cells May Help Recover Lost Vision for Those With Corneal Disease

SFL ORG. Educational News Network — Tue, 08 Dec 2009 18:54:07 +0000

Umbilical Stem Cells May Help Recover Lost Vision for Those With Corneal Disease

Tuesday, December 8, 2009

New research from the University of Cincinnati may help in the recovery of lost vision for patients with corneal scarring.

Winston Whei-Yang Kao, PhD, professor of ophthalmology, along with other researchers in UC's ophthalmology department found that transplanting human umbilical mesenchymal stem cells into mouse models that lack the protein lumican restored the transparency of cloudy and thin corneas.

Mesenchymal stem cells are "multi-potent" stem cells that can differentiate into a variety of cell types.

These findings are being presented Dec. 8 in San Diego at the 49th Annual Meeting of the American Society of Cell Biology.

"Corneal transplantation is currently the only true cure for restoration of eyesight that may have been lost due to corneal scarring caused by infection, mechanical and chemical wounds and congenital defects of genetic mutations," Kao says. "However, the number of donated corneas suitable for transplantation is decreasing as the number of individuals receiving refractive surgeries, like LASIK, increases."

"Worldwide, there is a shortage of suitable corneas for transplantation, and at the present time, there is no effective alternative procedure besides corneal transplantation to treat corneal blindness," he continues. "There is a large need to develop alternative treatment regimens, one of which may be the transplantation of mesenchymal stem cells."

Researchers used mouse models that did not have the lumican gene, also known as lumican knock-out models. Lumican is a protein that controls the formation and maintenance of transparent corneas.

"Lumican knock-out models manifested thin and cloudy corneas," he says. "Transplantation of the umbilical stem cells significantly improved transparency and increased corneal stromal thickness in these mice."

In addition, Kao says, the umbilical mesenchymal stem cells survived in the mouse stroma (connective tissue) for more than three months with minimal or no rejection and became corneal cells, repairing lost functions caused by mutations.

"Our results suggest a potential treatment regimen for congenital and/or acquired corneal diseases," he says, adding that the availability of human umbilical stem cells is almost unlimited. "These stem cells are easy to isolate and can be recovered quickly from storage when treating patients.

"These findings have the potential to create new and better treatments -- and an improved quality of life -- for patients with vision loss due to corneal injury."

This study was funded by grants from the National Eye Institute, Research to Prevent Blindness and the Ohio Lions Eye Research Foundation.

Image Caption: Winston Whei-Yang Kao, PhD

Image Credit: University of Cincinnati

Source: University of Cincinnati

Permalink: http://www.sflorg.com/comm_center/unv_medical/p979_240.html

Time Stamp: 12/8/2009 at 6:36:47 PM UTC

New molecule identified in DNA damage response

SFL ORG. Educational News Network — Tue, 08 Dec 2009 17:43:21 +0000

New molecule identified in DNA damage response

Tuesday, December 8, 2009

In the harsh judgment of natural selection, the ultimate measure of success is reproduction. So it's no surprise that life spends lavish resources on this feat, whether in the courtship behavior of birds and bees or replicating the cells that keep them alive. Now research has identified a new piece in an elaborate system to help guarantee fidelity in the reproduction of cells, preventing potentially lethal mutations in the process.

In experiments to be published in the December 18 issue of the Journal of Biological Chemistry, researchers at The Rockefeller University identified the molecule SMARCAL1 as part of cells' damage control response to malfunctioning

DNA replication. In typical cell division, many different molecules have roles in guaranteeing the daughter strands of DNA are as identical as possible to their parent. Some molecules check for errors or 'proofread' the offspring for typos, for instance; others, when alerted to a problem, arrest the replication process and conduct repairs.

Lisa Postow, a postdoctoral fellow in Hironori Funabiki's Laboratory of Chromosome and Cell Biology, used mass spectroscopy to identify SMARCAL1 as involved in this intricate quality control process. Working with Brian T. Chait's Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Postow found the protein in a proteomics screen for molecules that were drawn to a dangerous DNA repair problem called a double-strand break.

In both human cells and in cells from African clawed frog egg extract, Postow found that at double-strand breaks, SMARCAL1 gathered with another molecule called RPA, which is known to coat broken strands of DNA and protect them while damage is repaired. SMARCAL1 had an added interest, too: A mutation in the gene that produces it is involved in a rare but lethal disease called Schimke immuno-osseous dysplasia, a disorder that causes wide-ranging problems including kidney malfunction, immunodeficiency and growth inhibition.

To Postow's surprise, she found that removing SMARCAL1 had little effect on double-strand break repair. However, it did facilitate a different aspect of the DNA damage response called replication fork stabilization, a process that holds steady the junction between parental and daughter strands -- the replication fork -- when replication is stalled because a problem has been detected. "For a mutation that causes such wide-ranging and severe physiological effects, it is surprising that the protein has such a relatively small effect at the cellular level," Postow says.

Postow's findings were largely corroborated by independent new research into SMARCAL1, which was published this fall in four back-to-back papers in Genes & Development. The work reveals another piece of the complex safeguards the body has in place to protect against dangerous mutations.

"This study also proves that the proteomic approach that Lisa has developed with Dr. Chait can efficiently identify proteins involving the DNA-damage recognition and repair process," says Funabiki. "Many more excitements are ahead of us."

Image Caption: Researchers have identified the molecule SMARCAL1 as involved in cells' elaborate system for recognizing and repairing DNA damage during cell division. The protein is pictured above (green) in the presence of DNA (blue) as the chromosomes align along the mitotic spindle (red).

Image Credit: Rockefeller University

Source: Rockefeller University

Permalink: http://www.sflorg.com/comm_center/unv_science/p978_252.html

Time Stamp: 12/8/2009 at 5:25:08 PM UTC

Life on Mars theory boosted by new methane study

SFL ORG. Educational News Network — Tue, 08 Dec 2009 15:43:08 +0000

Life on Mars theory boosted by new methane study

Tuesday, December 8, 2009

Scientists have ruled out the possibility that methane is delivered to Mars by meteorites, raising fresh hopes that the gas might be generated by life on the red planet, in research published tomorrow (Wednesday 9 December 2009) in Earth and Planetary Science Letters.

Methane has a short lifetime of just a few hundred years on Mars because it is constantly being depleted by a chemical reaction in the planet's atmosphere, caused by sunlight. Scientists analyzing data from telescopic observations and unmanned space missions have discovered that methane on Mars is being constantly replenished by an unknown source and they are keen to uncover how the levels of methane are being topped up.

Researchers had thought that meteorites might be responsible for Martian methane levels because when the rocks enter the planet's atmosphere they are subjected to intense heat, causing a chemical reaction that releases methane and other gases into the atmosphere.

However, the new study, by researchers from Imperial College London, shows that the volumes of methane that could be released by the meteorites entering Mars' atmosphere are too low to maintain the current atmospheric levels of methane. Previous studies have also ruled out the possibility that the methane is delivered through volcanic activity.

This leaves only two plausible theories to explain the gas's presence, according to the researchers behind today's findings. Either there are microorganisms living in the Martian soil that are producing methane gas as a by-product of their metabolic processes, or methane is being produced as a by-product of reactions between volcanic rock and water.

Co-author of the study, Dr Richard Court, Department of Earth Science and Engineering at Imperial College London, says:

"Our experiments are helping to solve the mystery of methane on Mars. Meteorites vaporising in the atmosphere are a proposed methane source but when we recreate their fiery entry in the laboratory we get only small amounts of the gas. For Mars, meteorites fail the methane test."

The team say their study will help NASA and ESA scientists who are planning a joint mission to the red planet in 2018 to search for the source of methane. The researchers say now that they have discovered that meteorites are not a source of Methane on Mars, ESA and NASA scientists can focus their attention on the two last remaining options.

Co-author, Professor Mark Sephton, Department of Earth Science and Engineering at Imperial College London, adds:

"This work is a big step forward. As Sherlock Holmes said, eliminate all other factors and the one that remains must be the truth. The list of possible sources of methane gas is getting smaller and excitingly, extraterrestrial life still remains an option. Ultimately the final test may have to be on Mars."

The team used a technique called Quantitative Pyrolysis-Fourier Transform Infrared Spectroscopy to reproduce the same searing conditions experienced by meteorites as they enter the Martian atmosphere. The team heated the meteorite fragments to 1000 degrees Celsius and measured the gases that were released using an infrared beam.

When quantities of gas released by the laboratory experiments were combined with published calculations of meteorite in-fall rates on Mars, the scientists calculated that only 10 kilograms of meteorite methane was produced each year, far below the 100 to 300 tonnes required to replenish methane levels in the Martian atmosphere.

This research was funded by a grant from the Science Technology Facilities Council.

Source: Imperial College London
Permalink: http://www.sflorg.com/comm_center/unv_space/p977_39.html
Time Stamp: 12/8/2009 at 3:30:54 PM UTC

HIV-Related Memory Loss Linked to Alzheimer's Protein

SFL ORG. Educational News Network — Mon, 07 Dec 2009 20:59:24 +0000

Under Embargo Till: 21:00 UTC December 07, 2009
Posted: 21:00 UTC 12/07/2009

HIV-Related Memory Loss Linked to Alzheimer's Protein

Monday, December 7, 2009

More than half of HIV patients experience memory problems and other cognitive impairments as they age, and doctors know little about the underlying causes. New research from Washington University School of Medicine in St. Louis suggests HIV-related cognitive deficits share a common link with Alzheimer's-related dementia: low levels of the protein amyloid beta in the spinal fluid.

However, by analyzing biomarkers in the fluid surrounding the brain and spinal cord, the researchers report Dec. 8 in the journal Neurology, they could distinguish patients with HIV-related cognitive impairments from patients with mild Alzheimer's disease. This is important because as patients with HIV age, some will develop cognitive deficits related to HIV and others to Alzheimer's. New treatments in the pipeline to improve memory and thinking may not work for both conditions.

"HIV patients with cognitive dysfunction don't have early Alzheimer's - although some of the symptoms may be similar," says lead author David Clifford, M.D., an authority on the neurological complications of HIV and director of Washington University's AIDS Clinical Trials Unit. "The underlying biology of both conditions may be related to amyloid, and we think this clue can help us find the cause of cognitive impairment in HIV patients.

Cognitive dysfunction is a major problem among the estimated 1 million Americans living with HIV. The impairments are often mild but can affect a person's daily life, relationships and ability to hold a job. They include difficulties with memory, processing complex information and making decisions. These problems are expected to worsen as HIV patients live longer, due to potent drug cocktails that keep the virus in check.

In the new research, the scientists looked at the spinal fluid of 49 HIV patients with cognitive impairments, 21 HIV patients with normal cognitive function, 68 patients with mild Alzheimer's and 50 normal, healthy "controls." The Alzheimer's patients were older (average age 74) than the controls (average age 50), impaired HIV patients (average age 48) and cognitively normal HIV patients (average age 43).

They tested the spinal fluid for the presence of amyloid beta - the protein that folds and accumulates in the brains of Alzheimer's patients and is thought to play a key role in driving the brain damage that characterizes the disease. They also looked at other biomarkers associated with Alzheimer's, including tau, a protein found in tangled nerve fibers in Alzheimer's patients.

When amyloid beta accumulates in the brains of Alzheimer's patients, levels decrease in the spinal fluid, and Clifford and his colleagues expected to find low levels of the protein in samples of the Alzheimer's patients they studied.

But they were surprised to find the same low levels in the spinal fluid of HIV patients with cognitive dysfunction. Both groups of patients had significantly lower amyloid beta levels than HIV patients without cognitive impairments and the normal controls. The lower levels are an indicator that amyloid beta in the brain alters the normal turnover of the protein in the body.

Although Australian and European researchers had uncovered a link between HIV-related cognitive deficits and amyloid beta in 2005 in a smaller study, Clifford thought that finding was an artifact and embarked on the current study largely to disprove it.

"I really did not expect the biology of HIV cognitive dysfunction to be related to Alzheimer's," Clifford says. "If you look at the brains of HIV patients with cognitive impairments, they don't look like Alzheimer's brains - they don't have the same atrophy or a plethora of plaques and tangles characteristic of Alzheimer's."

But low amyloid beta is where the similarity to Alzheimer's disease ends. The researchers found that patients with mild Alzheimer's had significantly higher levels of tau than either group of HIV patients or normal controls - a finding that strongly suggests Alzheimer's and HIV cognitive dysfunction are not one and the same, Clifford says.

He suspects the HIV-related cognitive impairment may be due to low levels of the virus that hide out in the brain, beyond the reach of drugs that can't easily cross the blood-brain barrier. Another cause may be low-grade inflammation in the brain that is driven by the virus.

Almost all HIV patients in the study were taking anti-retroviral therapy. "I am almost certain the dementia in AIDS patients is linked to HIV and not to anti-retroviral drugs - we see it even in patients who haven't received HIV therapy," Clifford says. "However, the more subtle impairment may be in some way associated with a change in the way the body processes amyloid beta. This will certainly be an important area of future research."

The research is funded by grants from the National Institutes of Health.

Clifford DB, Fagan AM, Holtzman DM, Morris JC, Teshome M, Shah AR, Kauwe JSK. CSF biomarkers of Alzheimer disease in HIV-associated neurologic disease. Neurology. Dec. 8, 2009.

Source: Washington University in St. Louis

Permalink: http://www.sflorg.com/comm_center/unv_medical/p976_239.html

Time Stamp: 12/7/2009 at 21:00:00 UTC

Isolation, Stress May Contribute to Breast Cancer Risk

SFL ORG. Educational News Network — Mon, 07 Dec 2009 20:29:45 +0000

Isolation, Stress May Contribute to Breast Cancer Risk

Monday, December 7, 2009

Social isolation and related stress could contribute to human breast cancer susceptibility, research from a rat model designed at the University of Chicago to identify environmental mechanisms contributing to cancer risk shows.

The researchers found that isolation and stress result in a 3.3-fold increase in the risk of developing cancer among rats with naturally occurring mammary tumors.

The research establishes, for the first time, that isolation and stress could be a factor in human breast cancer risk, said Martha McClintock, a psychologist at the University of Chicago and an author of a paper in current issue of the Proceedings of the National Academy of Sciences. Researchers at the University have been studying social isolation in the context of breast cancer development after having found that that many women living in high-crime neighborhoods must deal with a variety of stressors, including social isolation. In particular, African American women have been noted to have an earlier onset of breast cancer, although total incidence is similar to women from other ancestries.

"We need to use these findings to identify potential targets for intervention to reduce cancer and other and its psychological and social risk factors," said McClintock, the David Lee Shillinglaw Distinguished Service Professor in Psychology and Comparative Human Development at the University. "In order to do that, we need to look at the problem from a variety of perspectives, including examining the sources of stress in neighborhoods as well as the biological aspects of cancer development."

The results of the study are published in a PNAS paper titled, "Social Isolation Dysregulates Endocrine and Behavioral Stress While Increasing Malignant Burden of Spontaneous Mammary Tumors." Gretchen Hermes, a former researcher at the University and now a resident in psychiatry at the Yale University School of Medicine, is lead author of the study.

The paper is part of a series of publications by University of Chicago researchers exploring the connection between social isolation and breast cancer biology, and part of an ongoing research program at Chicago where work is being done on cancer by researchers from a wide number of disciplines. That work was enabled by the University's Biopsychological Sciences Building, designed for such interdisciplinary research on behavior and biology and enhanced when the University received a $10 million grant from the National Institutes of Health to finance its Center for Interdisciplinary Health Disparities Research and is supported by the University of Chicago Cancer Research Center.

The study published in PNAS found that isolation led to a higher production of a stress hormone, corticosterone, among rats that were kept alone and subjected to the disturbances of colony life as well as stressful situations, such as the smell of a predator or being briefly constrained. Additionally, the isolated rats took longer to recover from a stressful situation than rats that lived together in small groups.

The study also suggests a causal relationship between social interaction and disease by showing that living alone first causes rats to have higher stress hormones, beginning in young adulthood, become fearful, anxious and vigilant and then prone to malignancy in late-middle age. The study further showed that the stress hormone receptor entered the nucleus of mammary tumor cells in isolated rats, where gene regulation occurs, something that happened less often in the cells of the non-isolated rats.

The researchers further found that rats living in isolation experienced a 135 percent increase in the number of tumors and a more than 8,000 percent increase in their size. The impact of isolation was much larger than the impact another environmental source of tumor formation -- the unlimited availability of high-energy food.

In natural situations, estrogen and progesterone produced from ovaries play a role in the majority of naturally occurring mammary and breast cancers tumors. In the rat study, tumors naturally developed in late middle age, while ovaries were no longer fully functioning, further suggesting the role of isolation and stress hormones in cancer development.

Joining McClintock and Hermes in preparing the PNAS paper were Bertha Delgado, researcher at Ben Gurion University, Israel; Maria Tretikova, Resident in Pathology at the University of Chicago Medical Center; Sonia Cavigelli, Assistant Professor of Biobehavioral Health at Penn State University; Thomas Krausz, Director of Anatomic Pathology at the University; and Suzanne Conzen, Associate Professor of Medicine at the University. The National Institute of Environmental Health Sciences/National Cancer Institute, the U.S. Department of Defense, and the State of Connecticut Department of Mental Health and Addictive Services supported the research.

The paper is part of a series published by McClintock and her colleagues using animal models to study the onset of cancer.

Rats provide an excellent model for studying human health. They are gregarious animals that are constantly interacting, with complex social relationships and shared care for their young. Additionally, isolation is a natural part of their social order, as a rat stands sentry at each colony and needs to be extremely vigilant to danger on behalf of the rest of the group.

A paper published by University researcher Jason Yee and colleagues showed that rats that developed reciprocal supportive relationships during stress, in which they both asked for help and gave assistance to others, were likely to live longer. That research was reported in "Reciprocal Affiliation Among Adolescent Rats During a Mild Group Stressor Predicts Mammary Tumors and Lifespan," in the journal Psychosomatic Medicine.

Hermes was lead researcher in a paper published in Developmental Psychobiology that isolation disrupts the development of puberty in rats by accelerating maturation of ovarian function while simultaneously delaying mammary tissue development. As a result, the rats are more likely to development mammary tumors. The work was in a paper, "Isolation and the Timing of Mammary Gland Development, Gonadarche and Ovarian Senescence: Implications for Mammary Tumor Burden."

In a paper in the American Journal of Physiology, Hermes and McClintock reported that isolation caused a more pronounced inflammatory disease response in females than in males. That work was published in the paper "Social isolation and the inflammatory response: Sex differences in the enduring effects of a stressor."

More recently, in a paper published in Cancer Prevention Research, Conzen and McClintock reported that social isolation of a genetic mouse model of human breast cancer resulted in larger mammary tumor growth. In a paper titled "A model of gene-environment interaction reveals altered mammary gland gene expression and increased tumor growth following social isolation," Conzen and McClintock showed that social isolation was associated with the increased expression of specific sets of genes involved in metabolism and inflammation.

Source: University of Chicago

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Time Stamp: 12/7/2009 at 8:15:38 PM UTC

With Amino Acid Diet, Mice Improve After Brain Injury

SFL ORG. Educational News Network — Mon, 07 Dec 2009 20:00:01 +0000

Under Embargo Till: 20:00 UTC December 07, 2009
Posted: 20:00 UTC 12/07/2009

With Amino Acid Diet, Mice Improve After Brain Injury

Monday, December 7, 2009

Neurology researchers have shown that feeding amino acids to brain-injured animals restores their cognitive abilities and may set the stage for the first effective treatment for cognitive impairments suffered by people with traumatic brain injuries.

"We have shown in an animal model that dietary intervention can restore a proper balance of neurochemicals in the injured part of the brain, and simultaneously improves cognitive performance," said study leader Akiva S. Cohen, Ph.D., a neuroscientist at The Children's Hospital of Philadelphia.

If these results in mice can be translated to human medicine, there would be a broad clinical benefit. Every 23 seconds, a man, woman or child in the United States suffers a traumatic brain injury (TBI). The primary cause of death and disability in children and young adults, TBI also accounts for permanent disabilities in more than 5 million Americans. The majority of those cases are from motor vehicle injuries, along with a rising incidence of battlefield casualties.

Although physicians can relieve the dangerous swelling that occurs after a TBI, there are currently no treatments for the underlying brain damage that brings in its wake cognitive losses in memory, learning and other functions.

The animals in the current study received a cocktail of three branched chain amino acids (BCAAs), specifically leucine, isoleucine and valine, in their drinking water. Previous researchers had shown that people with severe brain injuries showed mild functional improvements after receiving BCAAs through an intravenous line.

BCAAs are crucial precursors of two neurotransmitters -- glutamate and gamma-aminobutyric acid, or GABA, which function together to maintain an appropriate balance of brain activity. Glutamate excites neurons, stimulating them to fire, while GABA inhibits the firing. Too much excitement or, too little, and the brain doesn't work properly. A TBI upsets the balance.

In particular, a TBI frequently damages the hippocampus, a structure deep in the brain involved in higher learning and memory. In the current study, the researchers found that an injury to the hippocampus reduced levels of BCAAs. Although overall levels of glutamate and GABA were unchanged, the loss of BCAAs disturbed the critical balance of neurotransmitters in the hippocampus, making some localized regions more excitable and others less excitable. Cohen's team tested the hypothesis that providing dietary BCAAs would restore the balance in neural response.

In this study, Cohen's study team first created standardized brain injuries in mice, and one week later compared the animals' conditioned fear response to that of uninjured mice. A week after receiving a mild electric shock in a specific cage, normal mice tend to "freeze" when placed in the same cage, anticipating another shock. The brain-injured mice demonstrated fewer freezing responses -- a sign that they had partially lost that piece of learning.

On the other hand, brain-injured mice that received a diet of BCAAs showed the same normal response as the uninjured mice. The BCAA cocktail had restored their learning ability.

In addition to the behavioral results, the team conducted electrophysiological experiments in slices of hippocampus from brain-injured and non-injured mice, and showed that BCAA restored a normal balance of neural activity. "The electrophysiological results were consistent with what we saw in the animals' functional recovery," said Cohen.

If the results in mice can be reproduced in people, patients with traumatic brain injuries could receive the BCAAs in a drink. Cohen suggests that BCAAs as a dietary supplement could have a more sustained, measured benefit than that seen when patients receive BCAAs intravenously, in which the large IV dose may flood brain receptors and have more limited benefits.

Although much work remains to be done to translate the finding into a therapy, Cohen expects to collaborate over the next year with other researchers in an early-phase clinical trial of dietary BCAAs in patients with mild to moderate TBI.

The National Institutes of Health provided funding for this study. Cohen's co-authors were Jeffrey Cole, Ph.D., Christina M. Mitala, Ph.D., Suhali Kundu and Itzhak Nissim, Ph.D., all of Children's Hospital; Jaclynn A. Elkind of the University of Pennsylvania; and Ajay Verma, M.D., Ph.D., of the Uniformed Services University of the Health Sciences, Bethesda, Md. Cohen and Nissim are also on the faculty of the University of Pennsylvania School of Medicine.

The study appears today in the online issue of the Proceedings of the National Academy of Sciences.

Source: Children's Hospital of Philadelphia
Permalink: http://www.sflorg.com/comm_center/medical/p974_99.html
Time Stamp: 12/7/2009 at 20:00: UTC

A See-Through Surprise

SFL ORG. Educational News Network — Mon, 07 Dec 2009 18:35:20 +0000

A See-Through Surprise

Monday, December 7, 2009

Rice lab makes solid material transparent to terahertz waves

Very often in science, the unexpected discovery turns out to be the most significant. Rice University Professor Junichiro Kono and his team weren't looking for a breakthrough in the transmission of terahertz signals, but there it was: a plasmonic material that would, with adjustments to its temperature and/or magnetic field, either stop a terahertz beam cold or let it pass completely.

The finding by Kono, a professor in electrical and computer engineering and in physics and astronomy, former graduate student Xiangfeng Wang and their colleagues helps close a knowledge gap in the electromagnetic spectrum between the ranges that address electronic and photonic devices.

Their paper, "Interference-Induced Terahertz Transparency in a Magneto-Plasma in a Semiconductor," appears in today's online version of the journal Nature Physics and will be published in the Dec. 24 edition. Co-authors include Texas A&M theoretical physicist Alexey Belyanin, Los Alamos National Laboratory physicist Scott Crooker and Daniel Mittleman, a Rice professor in electrical and computer engineering.

Kono's team had been studying the conductivity of indium antimonide. "This is a classic material people started working on in the 1940s," he said. "It's a typical semiconductor, and if you dope it, it's highly conductive. But if you apply a magnetic field, it becomes an insulator, and that's what we planned to look at."

When Wang used terahertz spectroscopy to study the material, its unusual properties became apparent. "He started tuning various parameters -- the magnetic field, temperature and then the frequency -- and found that the terahertz transmission of the material changed drastically," Kono said. "It went from opaque to transparent."

They found that in a magnetic field, the doped indium antimonide, a solid-state plasma, transmitted circularly polarized waves that interfered with each other. This affected terahertz beams in much the same way polarized sunglasses interfere with visible light. To their surprise, at particular combinations of settings, the beams would pass right through.

"Terahertz is an exciting field right now," said Kono, a newly named fellow of the American Physical Society whose lab focuses on the physics and applications of semiconductor nanostructures and quantum devices. "This frequency range is considered to be the last frontier of the electromagnetic spectrum."

Kono said neither type of semiconductor device in common use today -- photonic and electronic -- works in the terahertz range. "Photonic devices work in the visible and near-infrared ranges and electronic devices work in the kilohertz, megahertz and gigahertz ranges. There's a clear gap where there's no mature solid-state technology. That's why a lot of people are working to fill it."

"I wouldn't say the terahertz region is unexplored, but it's less so," said Mittleman, who specializes in terahertz technologies and worked on the development of a terahertz version of Rice's famous single-pixel camera. "There are some open problems that people haven't thought about -- or have thought about, but haven't found good solutions for. The whole technology base is a lot less mature."

Kono said applications for terahertz technology include imaging, spectroscopy and communications, and having a device that can serve as a terahertz switch would be a step forward.

Still, there are hurdles to making the lab's discovery practical, one being the operating temperature. Wang worked with the indium antimonide at temperatures between 2 and 240 kelvins (approximately -456 to -27 degrees Fahrenheit).

"The temperature is certainly a concern," Mittleman said. "If it's going to have impact as a useful device for controlling terahertz beams, there is some work yet to do. I don't think that's impossible, but the route is not immediately clear.

"There's not a lot of shocking new physics here," he said, but the combination of techniques used to treat the indium antimonide made for interesting science. "People are going to think it's pretty cool.

"I think it's nice to find things like this, because it's a great example of an unexpected discovery that could turn out to be really useful."

The National Science Foundation and the Robert A. Welch Foundation supported the research.

Source: Rice University

Permalink: http://www.sflorg.com/comm_center/unv_science/p973_251.html

Time Stamp: 12/7/2009 at 6:22:53 PM UTC