Vaccination Strategy May Hold Key to Ridding HIV Infection from Immune System
May 10, 2012
Using human immune system cells in the lab, AIDS experts at Johns Hopkins have figured out a way to kill off latent forms of HIV that hide in infected T cells long after antiretroviral therapy has successfully stalled viral replication to undetectable levels in blood tests.
In a report to be published in the journal Immunity online March 8, the Johns Hopkins team describes a vaccination strategy that boosts other immune system T cells and prepares them to attack HIV, before readying the virus for eradication by reactivating it.
HIV has long been known to persist in a dormant, inactive state inside immune system T cells even long after potent drugs have stopped the virus from making copies of itself to infect other cells. But once treatment is stopped or interrupted, the latent virus quickly reactivates, HIV disease progresses, and researchers say it has proven all but impossible to wipe out these pockets of infection.
Johns Hopkins senior study investigator and infectious disease specialist Robert Siliciano, M.D., Ph.D., who in 1995 first showed that reservoirs of dormant virus survived, says the resulting need for lifelong drug treatment has raised concerns about the adverse effects of decades of therapy, the growing risk of drug resistance, and the rising cost of care.
Siliciano and other AIDS scientists say the best hope for ultimately curing the disease is to force latent viruses to "turn back on," making them "visible" to the immune system's so-called cytolytic "killer" T cells and then, with the likely aid of drugs, eliminate the infected cells from the body.
In his new study, Siliciano showed that infected T cells survived after latent virus was reactivated, and were only killed off when other immune system T cells were primed before reactivation.
"Our study results strongly suggest that a vaccination to boost the immune response immediately prior to reactivating latent virus may be essential for totally eradicating HIV infection," says Siliciano, a professor at the Johns Hopkins University School of Medicine and a Howard Hughes Medical Institute investigator.
In their journal report, Siliciano and his colleagues describe their vaccination strategy and how short pieces of HIV proteins were introduced to stimulate the anti-HIV T-cell response just before reactivation of the latent virus. The incomplete viral proteins and subsequent immune system vaccination led to production of enough cytolytic T cells to attack and kill the latently infected cells.
Siliciano and his team next plans to test different methods for boosting the immune response before latent virus reactivation and compare their effectiveness in clearing all HIV- infected cells.
Currently, there are more than 34 million people in the world living with HIV, including an estimated 1,178,000 in the United States.
New plastics 'bleed' when cut or scratched -- and then heal like human skin
May 09, 2012
A new genre of plastics that mimic the human skin's ability to heal scratches and cuts offers the promise of endowing cell phones, laptops, cars and other products with self-repairing surfaces, scientists reported March 27. The team's lead researcher described the plastics, which change color to warn of wounds and heal themselves when exposed to light, in San Diego at the 243rd National Meeting & Exposition of the American Chemical Society (ACS).
"Mother Nature has endowed all kinds of biological systems with the ability to repair themselves," explained Professor Marek W. Urban, Ph.D., who reported on the research. "Some we can see, like the skin healing and new bark forming in cuts on a tree trunk. Some are invisible, but help keep us alive and healthy, like the self-repair system that DNA uses to fix genetic damage to genes. Our new plastic tries to mimic nature, issuing a red signal when damaged and then renewing itself when exposed to visible light, temperature or pH changes."
Urban, who is with the University of Southern Mississippi in Hattiesburg foresees a wide range of potential applications for plastic with warn-and-self-repair capabilities. Scratches in automobile fenders, for instance, might be repaired by simply exposing the fender to intense light. Critical structural parts in aircraft might warn of damage by turning red along cracks so that engineers could decide whether to shine the light and heal the damage or undertake a complete replacement of the component. And there could be a range of applications in battlefield weapons systems.
Plastics have become so common, replacing steel, aluminum, glass, paper and other traditional materials because they combine desirable properties such as strength, light weight and corrosion resistance. Hundreds of scientists around the world have been working, however, to remedy one of the downsides of these ubiquitous materials: Once many plastics get scratched or cracked, repairs can be difficult or impossible.
Self-healing plastics have become a Holy Grail of materials science. One approach to that goal involves seeding plastics with capsules that break open when cracked or scratched and release repairing compounds that heal scratches or cuts. Another is to make plastics that respond to an outside stimulus -- like light, heat or a chemical agent -- by repairing themselves.
Urban's group developed plastics with small molecular links or "bridges" that span the long chains of chemicals that compose plastic. When plastic is scratched or cracked, these links break and change shape. Urban tweaked them so that changes in shape produce a visible color change -- a red splotch that forms around the defect. In the presence of ordinary sunlight or visible light from a light bulb, pH changes or temperature, the bridges reform, healing the damage and erasing the red mark.
Urban cited other advantages of the new plastic. Unlike self-healing plastics that rely on embedded healing compounds that can self-repair only once, this plastic can heal itself over and over again. The material also is more environmentally friendly than many other plastics, with the process for producing the plastic water-based, rather than relying on potentially toxic ingredients. And his team now is working on incorporating the technology into plastics that can withstand high temperatures.
Size Matters: Large Marine Protected Areas Work for Dolphins
May 09, 2012
Ecologists in New Zealand have shown for the first time that Marine Protected Areas -- long advocated as a way of protecting threatened marine mammals -- actually work. Their study, based on 21 years' monitoring and published March 27 in the British Ecological Society's Journal of Applied Ecology, reveals that a marine sanctuary off the coast of Christchurch has significantly improved survival of Hector's dolphins -- one of the rarest dolphins in the world.
overing 1170 km2 of sea off New Zealand's South Island, Banks Peninsula Marine Mammal Sanctuary was designated in 1988 to prevent the dolphins being killed by gillnet and trawl fisheries.
Over 21 years between 1986 and 2006, researchers conducted regular photo-identification surveys of Hector's dolphins, photographically capturing 462 reliably-marked individuals, whose survival they studied.
According to one of the team, Dr Liz Slooten of the University of Otago: "We can identify individual dolphins from their battle scars -- which range from small nicks out of the dorsal fin to major scarring following shark attacks."
The team analysed the photographic re-sightings using a so-called Bayesian mark-recapture technique and then used a population model to assess the impact of the Marine Protected Area (MPA) on Hector's dolphins.
The results showed that since the MPA was designated, the dolphin's survival has increased by 5.4%. According to Dr Slooten: "This study provides the first empirical evidence that Marine Protected Areas are effective in protecting threatened marine mammals."
But she warns that while survival has improved significantly, it is not yet high enough to prevent the population from continuing to decline.
MPAs, in which certain fishing methods are banned or restricted, are often used to help conserve marine mammals. Until now, there has been little if any empirical evidence of their effectiveness, so measuring their impact is crucial to justify setting up MPAs.
As well as providing the first hard evidence that MPAs work, the study illustrates the importance of long-term ecological monitoring, as Dr Slooten explains: "Estimating population changes in marine mammals is challenging, often requiring many years of research to produce data accurate enough to detect these kinds of biological changes."
The study also shows that to be effective, MPAs need to be sufficiently large. "The take home message is that size matters. Marine Protected Areas work, but they have to be large enough in order to be effective," she concludes.
Satellite are seeing changes in land surfaces in high detail at northern latitudes, indicating thawing permafrost. This releases greenhouse gases into parts of the Arctic, exacerbating the effects of climate change.
Permafrost is ground that remains at or below 0°C for at least two consecutive years and usually appears in areas at high latitudes such as Alaska, Siberia and Northern Scandinavia, or at high altitudes like the Andes, Himalayas and the Alps.
About half of the world’s underground organic carbon is found in northern permafrost regions. This is more than double the amount of carbon in the atmosphere in the form of the greenhouse gases carbon dioxide and methane.
The effects of climate change are most severe and rapid in the Arctic, causing the permafrost to thaw. When it does, it releases greenhouse gases into the atmosphere, exacerbating the effects of climate change.
Although permafrost cannot be directly measured from space, factors such as surface temperature, land cover and snow parameters, soil moisture and terrain changes can be captured by satellites.
The use of satellite data like from ESA’s Envisat, along with other Earth-observing satellites and intensive field measurements, allows the permafrost research community to get a panoptic view of permafrost phenomena from a local to a Circum-Arctic dimension.
“Combining field measurements with remote sensing and climate models can advance our understanding of the complex processes in the permafrost region and improve projections of the future climate,” said Dr Hans-Wolfgang Hubberten, head of the Alfred Wegner Institute Research Unit (Germany) and President of the International Permafrost Association.
Last month, more than 60 permafrost scientists and Earth observation specialists came together for the Third Permafrost User Workshop at the Alfred Wegener Institute in Potsdam, Germany, to discuss their latest findings.
“The already available Permafrost products provide researchers with valuable datasets which can be used in addition to other observational data for climate and hydrological modelling,” said Dr Leonid Bobylev, the director of the Nansen Centre in St. Petersburg.
“However, for climate change studies – and in particular for evaluation of the climate models’ performance – it is essential to get a longer time series of satellite observational data.
“Therefore, the Permafrost related measurements should be continued in the future and extended consistently in the past.”
ESA will continue to monitor the permafrost region with its Envisat satellite and the upcoming Sentinel satellite series for Europe’s Global Monitoring for Environment and Security (GMES) programme.
Popcorn-Shaped Gold Particles Gang Up On Salmonella
May 09, 2012
Take an ounce of lettuce, test it for 17 hours, and the results show whether that mainstay ingredient in green salads is contaminated with Salmonella, the food poisoning bacteria that sickens millions of people each year. Another traditional test takes 72 hours to complete. How about a test that identifies Salmonella in five minutes, so that shipments of lettuce can be confiscated before they reach the table?
Scientists have just described development and successful testing of just such a test in a presentation in San Diego at the 243rd National Meeting & Exposition of the American Chemical Society (ACS).
Paresh C. Ray, Ph.D., who led the research, explained that the test fulfills an urgent need for a faster way to detect Salmonella, especially the multiple-drug resistant (MDR) strains that cause the most serious disease in both food and drinking water. In the U.S., Salmonella-contaminated food causes at least 1.6 million cases of food poisoning annually. Elsewhere in the developing world, drinking water contaminated with MDR Salmonella causes terrible outbreaks of typhoid fever, which strikes at least 17 million people annually.
"The test for lettuce requires just a tiny sample of lettuce leaf," Ray explained. "It doesn't take a trained laboratory technician to perform the test or read the results. If the color changes from pink to bluish, that signals the presence of Salmonella. The test is suitable for use in farm fields and in remote areas of the developing world. We believe it may have enormous potential for rapid, on-site pathogen detection to avoid the distribution of contaminated foods."
To find the bacteria faster, Ray and colleagues at Jackson State University in Mississippi enlisted gold nanoparticles, vanishingly small bits of gold so tiny that more than 25,000 would fit across the width of a human hair. The researchers attached antibodies, molecules similar to the ones that help the immune system find and fight infections with Salmonella, to the nanoparticles. Viewed under a powerful microscope, the gold nanoparticles look somewhat like individual pieces of popcorn.
When these antibodies encounter Salmonella bacteria, they attach to the outer surface of the bacteria, carrying along their cargo of gold popcorn-shaped nanoparticles. The nanoparticle-antibody package is much smaller than an individual Salmonella bacterium, and several attach to each bacterium. The test, with its pink-to-blue color change, detects those gold nanoparticle-antibody-Salmonella structures, which Ray calls "aggregates."
The approach also has potential for killing MDR Salmonella, Ray said.
"When you shine the right wavelength of light into contaminated water, for instance, the gold nanoparticles absorb that light and heat up," he explained. "Those hot particles burn through the outer membrane of the Salmonella bacteria, killing the bacteria."
Ray and colleagues first developed the popcorn-shaped particles to find and fight cancer. The shape was chosen because it boosts the signal for detection using something called Raman spectroscopy, which looks at the light given off after atoms or molecules absorb energy. Ray explained that this detection method is useful in other applications of the particles. "In science, we call that the lightning rod effect," said Ray, describing how the splayed "tips" of the popcorn shape enhance the signal and make it easier to see. The group has also used the nanoparticles to detect other microbes, like E. coli.
Despite gold's stature as a precious and very costly metal, only tiny amounts are needed, Ray noted. About $90 worth of gold is enough to make gallons of the solution containing the nanoparticles. And only a few drops of the solution are needed seek out Salmonella bacteria.
Ray said the technology can be commercialized, and a patent is pending. With concerns about the potential health and environmental effects of many kinds of nanoparticles, Ray's team is investigating the effects of gold nanoparticles remaining in purified water, for instance. So far, they have found no short-term toxicity and will be checking on any potential long-term toxicity.
The scientists acknowledged funding from National Science Foundation.
Air Pollution from Trucks and Low-Quality Heating Oil May Explain Childhood Asthma Hot Spots
May 09, 2012
Where a child lives can greatly affect his or her risk for asthma. According to a new study by scientists at Columbia University, neighborhood differences in rates of childhood asthma may be explained by varying levels of air pollution from trucks and residential heating oil.
In New York City, where the study was conducted, asthma among school-age children ranges from a low of 3% to a high of 19% depending on the neighborhood, and even children growing up within walking distance of each other can have 2- to 3-fold differences in risk for asthma. Helping explain these disparities, the researchers found that levels of airborne black carbon, which mostly comes from incomplete combustion sources like diesel trucks and oil furnaces, were high in homes of children with asthma. They also reported elevated levels of black carbon within homes in neighborhoods with high asthma prevalence and high densities of truck routes and homes burning low-grade or "dirty" heating oil.
"This study adds to the evidence that further public health interventions on oil and truck emissions standards and the use of dirty oil may be warranted. This is especially timely as New York City considers regulations to further reduce the burning of low-grade oil for domestic heating," says the study's senior author, Matthew Perzanowski, PhD, associate professor of Environmental Health Sciences.
The study may be the first to show an association between airborne black carbon in the home and proximity to buildings burning dirty oil (low-grade, types 4 and 6). "Because of its history as a shipping and oil refining center, New York City burns more dirty oil for residential and commercial heating than any other city in the country," says study co-author Steven Chillrud, PhD, Lamont Research Professor at Columbia's Lamont-Doherty Earth Observatory . "These fuels produce more byproducts of incomplete combustion than cleaner oil or natural gas and contribute substantially to air pollution. Buildings that burn dirty oil are unevenly distributed throughout the city, which could help explain disparities in health."
The research team collected air samples from inside the homes of 240 7- and 8-year-old children from middle-income neighborhoods throughout New York City. These children also took breathing tests to measure exhaled nitric oxide, an indicator of lung inflammation.
"Airway inflammation plays an important role in the development of asthma and can contribute to more frequent symptoms among children with the disease," says study lead author Alexandra Cornell, MD, assistant professor in pediatrics at Dartmouth Medical School and previously a pediatric pulmonology fellow at Columbia University Medical Center/NewYork-Presbyterian Hospital. "Children in this study with higher black carbon in the air of their homes had higher exhaled nitric oxide, suggesting that they were at greater risk for asthma exacerbations. That this increased risk comes from air pollution lends weight to New York City's efforts to improve air quality, including phasing out the use of dirty oil, which is a large contributor to local air pollution. "
Evidence Stacks Up That Monolith at Gardom's Edge Is Astronomically Aligned
May 09, 2012
Researchers at the Nottingham Trent University have gathered new evidence that a 4000-year-old monolith was aligned to be an astronomical marker. The 2.2 meter high monument, located in the Peak District National Park, has a striking, right-angled triangular shape that slants up towards geographic south. The orientation and inclination of the slope is aligned to the altitude of the Sun at mid-summer. The researchers believe that the monolith was set in place to give symbolic meaning to the location through the changing seasonal illuminations.
Dr Daniel Brown presented the findings on the 27th of March at the National Astronomy Meeting in Manchester.
The rare example of a monolith is located at Gardom's Edge, a striking millstone grit ridge less than an hour's drive from Manchester. The researchers have carried out a microtopography survey of the surface surrounding the monolith. Their findings indicate the presence of packing stones around the base of the monolith, evidence that it was placed carefully in position. They have also carried out 3-D modelling of illumination of the stone through the seasons, adapting for changes in Earth's tilt to the ecliptic plane over four millennia.
The landscape surrounding the stone harbors many ancient monuments such as Bronze Age roundhouses, a late Neolithic enclosure, and other traces of a long lasting human occupation. The researchers believe that the stone is also late Neolithic, set in place around 2000 BC.
"Given the sensitivity of the site, we can't probe under the surface of the soil. However, through our survey, we have found a higher density of packing stones on one side, supporting the case that the stone has been orientated intentionally," said Dr Brown.
The 3-D modelling shows that during the winter half-year, the slanted side of the stone would remain in permanent shadow; during most of the summer half-year it would only be illuminated during the morning and afternoon; close to midsummer it would be illuminated all day. The researchers are currently backing up the model by gathering contemporary photographic evidence of the stone.
"The stone would have been an ideal marker for a social arena for seasonal gatherings," said Dr Brown. "It's not a sundial in the sense that people would have used it to determine an exact time. We think that it was set in position to give a symbolic meaning to its location, a bit like the way that some religious buildings are aligned in a specific direction for symbolic reasons."
The researchers hope that the new evidence will support the case for a wider archaeological survey of the site.
"The use of shadow casting in monuments of this period is quite rare in the British Isles," said Dr Brown. "But there are some examples including New Grange, Ireland, and some Clava cairns in the north-east of Scotland that have been proposed to include the intentional use of shadows. Both are associated to burial sites using the symbolism of a cyclic light and shadow display to represent eternity. Given the proximity of the Neolithic enclosure and possible ritual importance of this site, the Gardom's Edge monolith could be another such example."
Jupiter Helps Halley’s Comet Give Us More Spectacular Meteor Displays
May 09, 2012
The dramatic appearance of Halley's comet in the night sky has been observed and recorded by astronomers since 240 BC. Now a study shows that the orbital influences of Jupiter on the comet and the debris it leaves in its wake are responsible for periodic outbursts of activity in the Orionid meteor showers. The results will be presented by Aswin Sekhar at the National Astronomy Meeting in Manchester on the 27th of March.
Halley's comet orbits the Sun every 75-76 years on average. As its nucleus approaches the Sun, it heats up and releases gas and dust that form the spectacular tail. This outgassing leaves a trail of debris around the orbit.
When Earth crosses Halley's path, twice per orbit, dust particles (meteoroids) burn up in Earth's atmosphere and we see meteor showers: the Orionids in October and the Eta Aquariids in May. Previous research has suggested that Orionid meteoroids have at times fallen into 'resonances' with Jupiter's orbit -- a numerical relationship that influences orbital behaviour. Sekhar's new study suggests that Halley itself has been in resonances with Jupiter in the past, which in turn would increase the chances of populating resonant meteoroids in the stream. The particles ejected during those times experience a tendency to clump together due to periodic effects from Jupiter.
"This resonant behaviour of meteoroids means that Halley's debris is not uniformly distributed along its orbital path. When the Earth encounters one of these clumps, it experiences a much more spectacular meteor shower than usual," said Sekhar, of Armagh Observatory.
Sekhar has modelled Halley's orbital evolution over more than 12 000 years into the past and 15 000 years into the future. The model suggests that from 1404 BC to 690 BC, Halley was trapped in a 1:6 resonance with Jupiter (in which Halley completed one orbit for every six orbits of Jupiter around the Sun). Later, from 240 BC to 1700 AD, the comet's orbit had a 2:13 relationship with Jupiter's orbit. Debris deposited during these two periods can be directly attributed to heightened activity in the Orionid meteor showers in some years. Sekhar's work suggests that the unusual Orionid outburst observed in 1993 was due to 2:13 resonant meteoroids ejected from Halley around 240 BC. He predicts that the next similar display of meteors from this 2:13 resonance will be in 2070 AD.
"The real beauty of this area of science lies in the convergence of cometary physics and orbital dynamics. The close correlation between historical records from ancient civilisations and the predictions using modern science make it even more elegant," said Sekhar. He added, "There are enough unsolved problems pertaining to Halley and its meteor streams to keep us occupied till the next apparition of the comet in 2061!"
Use It or Lose It: Mind Games Help Healthy Older People Too
May 09, 2012
Cognitive training including puzzles, handicrafts and life skills are known to reduce the risk, and help slow down the progress, of dementia amongst the elderly. A new study published in BioMed Central's open access journal BMC Medicine showed that cognitive training was able to improve reasoning, memory, language and hand eye co-ordination of healthy, older adults.
It is estimated that by 2050 the number of people over 65 years old will have increased to 1.1 billion worldwide, and that 37 million of these will suffer from dementia. Research has already shown that mental activity can reduce a person's risk of dementia but the effect of mental training on healthy people is less well understood. To address this researchers from China have investigated the use of cognitive training as a defence against mental decline for healthy older adults who live independently.
To be recruited onto the trial participants had to be between 65 and 75 years old, and have good enough eyesight, hearing, and communication skills, to be able to complete all parts of the training. The hour long training sessions occurred twice a week, for 12 weeks, and the subjects were provided with homework. Training included a multi-approach system tackling memory, reasoning, problem solving, map reading, handicrafts, health education and exercise, or focussing on reasoning only. The effect of booster training, provided six months later, was also tested.
The results of the study were positive. Profs Chunbo Li and Wenyuan Wu who led the research explained, "Compared to the control group, who received no training, both levels of cognitive training improved mental ability, although the multifaceted training had more of a long term effect. The more detailed training also improved memory, even when measured a year later and booster training had an additional improvement on mental ability scores."
This study shows that cognitive training therapy may prevent mental decline amongst healthy older people and help them to continue independent living longer in their advancing years.
Some of the flame retardants added to carpets, furniture upholstery, plastics, crib mattresses, car and airline seats and other products to suppress the visible flames in fires are actually increasing the danger of invisible toxic gases that are the No. 1 cause of death in fires. That was the finding of a new study presented in San Diego on March 27 at the 243rd National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society. Anna A. Stec, Ph.D., led the research, which focused on the most widely-used category of flame retardants, which contain the chemical element bromine. Scientists term these "halogen-based" flame retardants because bromine is in a group of elements called halogens.
"Halogen-based flame retardants are effective in reducing the ignitability of materials," Stec said. "We found, however, that flame retardants have the undesirable effect of increasing the amounts of carbon monoxide and hydrogen cyanide released during combustion. These gases, not the thermal effects of burns on the body, are the No. 1 cause of fire deaths." Stec, who is with the University of Central Lancashire, Centre for Fire and Hazards Science, Lancashire, U.K., spoke at an ACS symposium on "Fire and Polymers," which included 60 presentations.
Almost 10,000 deaths from fires occur in industrialized countries worldwide each year, including about 3,500 in the U.S. Contrary to popular belief, inhalation of toxic gases released by burning materials -- not burns -- causes the most deaths and most of the serious injuries. Stec's team set out to determine the effects of flame retardants on the production of those gases. The scientists tested brominated flame retardants with antimony synergists, mineral-based flame retardants and so-called intumescent agents, which swell when heated, forming a barrier that flames cannot penetrate.
New Twist On 1930s Technology May Become a 21st Century Weapon Against Global Warming
Far from being a pipe dream years away from reality, practical technology for capturing carbon dioxide -- the main greenhouse gas -- from smokestacks is aiming for deployment at coal-fired electric power generating stations and other sources, scientists saidin San Diego March 27. Their presentation at the 243rd National Meeting of the American Chem...
May 10, 2012
Transparent, Flexible '3-D' Memory Chips May Be the Next Big Thing in Small Memory Devices
New memory chips that are transparent, flexible enough to be folded like a sheet of paper, shrug off 1,000-degree Fahrenheit temperatures -- twice as hot as the max in a kitchen oven -- and survive other hostile conditions could usher in the development of next-generation flash-competitive memory for tomorrow's keychain drives, cell phones and comp...
May 10, 2012
Researchers Discover a New Path for Light Through Metal
Helping bridge the gap between photonics and electronics, researchers from Purdue University have coaxed a thin film of titanium nitride into transporting plasmons, tiny electron excitations coupled to light that can direct and manipulate optical signals on the nanoscale. Titanium nitride's addition to the short list of surface-plasmon-supporting m...