fpanscience

Earth Core is Melting and Freezing

2011-05-25T05:08:00.000-07:00

New findings could help us understand how the inner and outer core react as a geodynamo which create magnetic field. Dr Jon Mound from University of Leeds says that it's still hard to tell the origin of magnetic field as we can't go collect sample so we have to rely on surface measurement and computer models to tell us what's happening in the core.

Earth's inner core is a ball of solid iron that surrounded by a highly dynamic outer core of a liquid iron-nickel alloy (and some other, lighter elements), a highly viscous mantle and a solid crust that forms the surface where we live.

Over billions of years, Earth has cooled from the inside out causing the molten iron core to partly freeze and solidify. The inner core has subsequently been growing at the rate of around 1mm a year as iron crystals freeze and form a solid mass.
The heat given off as the core cools flows from the core to the mantle to Earth's crust through a process known as convection. Like a pan of water boiling on a stove, convection currents move warm mantle to the surface and send cool mantle back to the core. This escaping heat powers the geodynamo and coupled with the spinning of Earth generates the magnetic field.

Scientists have recently begun to realise that the inner core may be melting as well as freezing, but there has been much debate about how this is possible when overall the deep Earth is cooling. Now the research team believes they have solved the mystery.

Using a computer model of convection in the outer core, together with seismology data, they show that heat flow at the core-mantle boundary varies depending on the structure of the overlying mantle. In some regions, this variation is large enough to force heat from the mantle back into the core, causing localised melting.

The model shows that beneath the seismically active regions around the Pacific 'Ring of Fire', where tectonic plates are undergoing subduction, the cold remnants of oceanic plates at the bottom of the mantle draw a lot of heat from the core. This extra mantle cooling generates down-streams of cold material that cross the outer core and freeze onto the inner core.

Conversely, in two large regions under Africa and the Pacific where the lowermost mantle is hotter than average, less heat flows out from the core. The outer core below these regions can become warm enough that it will start melting back the solid inner core.

Dr Binod Sreenivasan from the Indian Institute of Technology said: "If Earth's inner core is melting in places, it can make the dynamics near the inner core-outer core boundary more complex than previously thought.

"On the one hand, we have blobs of light material being constantly released from the boundary where pure iron crystallizes. On the other hand, melting would produce a layer of dense liquid above the boundary. Therefore, the blobs of light elements will rise through this layer before they stir the overlying outer core.

"Interestingly, not all dynamo models produce heat going into the inner core. So the possibility of inner core melting can also place a powerful constraint on the regime in which the Earth's dynamo operates."

Dr Sebastian Rost from the University of Leeds added: "The standard view has been that the inner core is freezing all over and growing out progressively, but it appears that there are regions where the core is actually melting. The net flow of heat from core to mantle ensures that there's still overall freezing of outer core material and it's still growing over time, but by no means is this a uniform process.

"Our model allows us to explain some seismic measurements which have shown that there is a dense layer of liquid surrounding the inner core. The localised melting theory could also explain other seismic observations, for example why seismic waves from earthquakes travel faster through some parts of the core than others."

Artificial Tissue Develop Skin Growth in Wounds

2011-05-24T06:59:00.000-07:00

Victims of third-degree burns and other traumatic injuries endure pain, disfigurement, invasive surgeries and a long time waiting for skin to grow back. Improved tissue grafts designed by Cornell scientists that promote vascular growth could hasten healing, encourage healthy skin to invade the wounded area and reduce the need for surgeries.

These so-called dermal templates were engineered in the lab of Abraham Stroock, associate professor of chemical and biomolecular engineering at Cornell and member of the Kavli Institute at Cornell for Nanoscale Science, in collaboration with Dr. Jason A. Spector, assistant professor of surgery at Weill Cornell Medical College, and an interdisciplinary team of Ithaca and Weill scientists. The research was published online May 6 in the journal Biomaterials.

The biomaterials are composed of experimental tissue scaffolds that are about the size of a dime and have the consistency of tofu. They are made of a material called type 1 collagen, which is a well-regulated biomaterial used often in surgeries and other biomedical applications. The templates were fabricated with tools at the Cornell NanoScale Science and Technology Facility to contain networks of microchannels that promote and direct growth of healthy tissue into wound sites.

"The challenge was how to promote vascular growth and to keep this newly forming tissue alive and healthy as it heals and becomes integrated into the host," Stroock said.

The grafts promote the ingrowth of a vascular system -- the network of vessels that carry blood and circulate fluid through the body -- to the wounded area by providing a template for growth of both the tissue (dermis, the deepest layer of skin), and the vessels. Type I collagen is biocompatible and contains no living cells itself, reducing concerns about immune system response and rejection of the template.

A key finding of the study is that the healing process responds strongly to the geometry of the microchannels within the collagen. Healthy tissue and vessels can be guided to grow toward the wound in an organized and rapid manner.

Dermal templates are not new; the Johnson & Johnson product Integra, for example, is widely used for burns and other deep wounds, Spector said, but it falls short in its ability to encourage growth of healthy tissue because it lacks the microchannels designed by the Cornell researchers.

"They can take a long time to incorporate into the person you're putting them in," Spector said. "When you're putting a piece of material on a patient and the wound is acellular, it has a big risk for infection and requires lots of dressing changes and care. Ideally you want to have a product or material that gets vascularized very rapidly."

In the clinic, Spector continued, patients often need significant reconstructive surgery to repair injuries with exposed vital structures like bone, tendon or orthopedic hardware. The experimental templates are specifically designed to improve vascularization over these "barren" areas, perhaps one day eliminating the need for such invasive surgeries and reducing the patient's discomfort and healing time.

Eventually, the scientists may try to improve their tissue grafts by, for example, reinforcing them with polymer meshes that could also act as a wound covering, Spector said.

Other collaborators include first author Ying Zheng, a former postdoctoral associate in Stroock's lab; Dr. Peter W. Henderson, chief research fellow at Weill Cornell's Laboratory for Bioregenerative Medicine and Surgery; graduate student Nak Won Choi; and Lawrence J. Bonassar, associate professor of biomedical engineering.

The work was supported by the Morgan Fund for Tissue Engineering and the New York State Office of Science, Technology and Academic Research.

Japan Quake May Have Slightly Shortened Earth Days, Moved Axis, Theoretical Calculations Suggest

2011-03-27T08:31:00.000-07:00

The magnitude 9.0 earthquake that struck Japan March 11, 2011 may have slightly shortened the length of each Earth day and shifted its axis.

Using a United States Geological Survey estimate for how the fault responsible for the earthquake slipped, research scientist Richard Gross of NASA's Jet Propulsion Laboratory, Pasadena, Calif., applied a complex model to perform a preliminary theoretical calculation of how the Japan earthquake -- the fifth largest since 1900 -- affected Earth's rotation. His calculations indicate that by changing the distribution of Earth's mass, the Japanese earthquake should have caused Earth to rotate a bit faster, shortening the length of the day by about 1.8 microseconds (a microsecond is one millionth of a second).

The calculations also show the Japan quake should have shifted the position of Earth's figure axis (the axis about which Earth's mass is balanced) by about 17 centimeters (6.5 inches), towards 133 degrees east longitude. Earth's figure axis should not be confused with its north-south axis; they are offset by about 10 meters (about 33 feet). This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in space -- only external forces such as the gravitational attraction of the sun, moon and planets can do that.

Both calculations will likely change as data on the quake are further refined.

In comparison, following last year's magnitude 8.8 earthquake in Chile, Gross estimated the Chile quake should have shortened the length of day by about 1.26 microseconds and shifted Earth's figure axis by about 8 centimeters (3 inches). A similar calculation performed after the 2004 magnitude 9.1 Sumatran earthquake revealed it should have shortened the length of day by 6.8 microseconds and shifted Earth's figure axis by about 7 centimeters, or 2.76 inches. How an individual earthquake affects Earth's rotation depends on its size (magnitude), location and the details of how the fault slipped.

Gross said that, in theory, anything that redistributes Earth's mass will change Earth's rotation.

"Earth's rotation changes all the time as a result of not only earthquakes, but also the much larger effects of changes in atmospheric winds and oceanic currents," he said. "Over the course of a year, the length of the day increases and decreases by about a millisecond, or about 550 times larger than the change caused by the Japanese earthquake. The position of Earth's figure axis also changes all the time, by about 1 meter (3.3 feet) over the course of a year, or about six times more than the change that should have been caused by the Japan quake."

Gross said that while we can measure the effects of the atmosphere and ocean on Earth's rotation, the effects of earthquakes, at least up until now, have been too small to measure. The computed change in the length of day caused by earthquakes is much smaller than the accuracy with which scientists can currently measure changes in the length of the day. However, since the position of the figure axis can be measured to an accuracy of about 5 centimeters (2 inches), the estimated 17-centimeter shift in the figure axis from the Japan quake may actually be large enough to observe if scientists can adequately remove the larger effects of the atmosphere and ocean from the Earth rotation measurements. He and other scientists will be investigating this as more data become available.

Gross said the changes in Earth's rotation and figure axis caused by earthquakes should not have any impacts on our daily lives. "These changes in Earth's rotation are perfectly natural and happen all the time," he said. "People shouldn't worry about them."

Why Low Birth Weight Is Linked to Obesity Later in Life: Study Provides Explanation

2011-03-12T04:59:00.000-08:00

Providing further understanding of the link between low birth weights and obesity later in life, researchers found nutritionally deprived newborns are "programmed" to eat more because they develop less neurons in the region of the brain that controls food intake, according to an article published in the journal Brain Research.

The study by a team of researchers at Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center (LA BioMed) suggests that overeating is programmed at the level of stem cells before birth when the mother has poor or inadequate nutrition.

Using an animal model, the researchers found less division and differentiation of the neural stem cells of a newborn with low birth weight as compared to normal birth weight. Previous studies have found a small size at birth followed by accelerated "catch-up" growth is associated with an increased risk of adult obesity, cardiovascular disease, type 2 diabetes, hypertension and osteoporosis.

"This study demonstrates the importance of maternal nutrition and health in reducing obesity," said Dr. Mina Desai, an LA BioMed principal investigator and corresponding author of the new study. "Obesity and its related diseases are the leading cause of death in our society, yet we have few effective strategies for prevention or treatment. These studies suggest maternal nutrition could play a critical role in preventing obesity and related disease."

In addition to obesity, the findings of altered brain (neural stem cells) development suggest that fetal growth restriction may be associated with cognitive and/or behavioral alterations. Importantly, the study offers potential opportunities for prevention and treatment for obesity and other related disorders. In addition to Dr. Desai, LA BioMed investigators Tie Li and Michael G. Ross participated in the study.

More than 60% of American adults are overweight and more than 1 in 5 are obese. Obesity is a serious health concern for children and adolescents, as well. About 17 percent of children and adolescents ages 2-19 years are obese.

Is South Pole Ice Melting? Gravity Field Satellites Observe Antarctic Ice Mass Fluctuations Due to El Niño

2011-03-03T16:42:00.000-08:00

The change in the ice mass covering Antarctica is a critical factor in global climate events. Scientists at the GFZ German Research Centre for Geosciences have now found that the year by year mass variations in the western Antarctic are mainly attributable to fluctuations in precipitation, which are controlled significantly by the climate phenomenon El Niño. They examined the GFZ data of the German-American satellite mission GRACE (Gravity Recovery and Climate Experiment). The investigation showed significant regional differences in the western coastal area of the South Pole area.

Two areas in Antarctica are of particular interest because of their potential sensitivity to global climate change: the Antarctic Peninsula, which is currently experiencing a warming exceeding the global mean and the disappearance of large ice shelf areas, and the Amundsen Sector of West Antarctica, where currently the largest flow rates and mass loss of the Antarctic Ice Sheet is occurring. For some glaciers the ice thickness is decreasing rapidly, and glaciers and ice streams are notably retreating back into the interior. With 0.3 millimeters per year, both regions are currently contributing considerably to the global sea level change of about three millimeters per year.

In the study, the mass balance of both regions is reevaluated from gravity data of the satellite mission GRACE. As a result, the estimates were lower than those of conventional mass balance methods.

"With the GRACE time series, it was for the first time possible to observe how the large-scale ice mass varies in the two areas due to fluctuations in rainfall from year to year," said the GFZ scientists Ingo Sasgen. It has long been known that the Pacific El Niño climate phenomenon and the snowfall in Antarctica are linked.

The complementary piece to the warm phase El Niño, the cold phase known as La Nina, also affects the Antarctic climate: "The cooler La Nina years lead to a strong low pressure area over the Amundsen Sea, which favors heavy rainfall along the Antarctic Peninsula -- the ice mass is increasing there. In contrast, the Amundsen area is dominated by dry air from the interior during this time. El Niño years with their warm phase lead to precisely the opposite pattern: reduced rainfall and mass loss in the Antarctic Peninsula, and an increase in the Amundsen Sectorfield, respectively," explains Professor Maik Thomas, head of the section "Earth System Modelling" at the German Research Centre for Geosciences (Helmholtz Association).

The recording of the entire ice mass of the South Pole and its variations is a central task in climate research and still raises many unanswered questions. In principle, the study could show that the continuous gravity data of the GRACE satellite mission contain another important medium-term climate signal.

Human Ancestors Lived on Shaky Ground

2011-03-03T16:40:00.000-08:00

Our earliest ancestors preferred to settle in locations that have something in common with cities such as San Francisco, Naples and Istanbul -- they are often on active tectonic faults in areas that have an earthquake risk or volcanoes, or both.

An international team of scientists has established a link between the shape of the landscape and the habitats preferred by our earliest ancestors. The research, by scientists at the University of the Witwatersrand, South Africa, the University of York and the Institut de Physique du Globe Paris (IPGP), is published in the March 2011 issue of the Journal of Human Evolution.

The four-year study examines the geomorphology (literally the shape of the landscape) around ancient sites in southern Africa.

Lead author, South African Dr Sally Reynolds, a palaeoanthropologist at Witwatersrand who conducted the research during a postdoctoral fellowship at IPGP, says: "We were stunned when during a fieldwork trip in South Africa in 2007, Professor Geoffrey King and I discovered evidence that hominin sites such as Taung, Sterkfontein and Makapansgat, show landscape features in combinations that are not random, but result from tectonic motions, such as earthquakes."

Several lines of scientific evidence suggest thatAustralopithecus africanus (like the 'Mrs Ples' fossil from Sterkfontein) was adapted to mixed, or mosaic habitats -- landscapes with trees and open grassland, with some wetland marshy areas. The study suggests that it was the type of mosaic environment created by tectonic earth movements near rivers or lakes.

These features including cliffs, sedimented valleys, river gorges and drier plateau areas in close proximity of about 10 kilometres, are created when sections of Earth's crust move in response to pressure, then blocks of land are lifted up, while others are forced downwards. When this happens next to a river, the result is the creation of wetland, marshy areas close to drier plateaus and areas of erosion.

Professor Geoff Bailey, from the University of York, who is the lead author on an accompanying paper, also published in the same issue of the Journal of Human Evolution, confirms: "This link between earthquakes and human habitation is one we've long suspected was there. Regions vulnerable to earthquake and volcanic activity often create landscapes with long-term benefits for human settlement. But the tragic events in Christchurch are a graphic illustration of the attendant risk of these locations."

Professor King, a tectonic geomorphologist at the IPGP, adds: "The original idea was developed in Greece over a decade ago, with the surprising discovery that the sites there were clearly associated with ongoing tectonic activity.

"Even though South Africa appears to be tectonically stable, there are landscape features that indicate that modest levels of activity are preserved in the hard, southern African rocks. This means that the landscape model we developed in Greece is equally applicable to East Africa, and now also to the well-known fossil sites of the South Africa's Cradle of Humankind World Heritage Site."

Dr Reynolds, who is also an honorary research fellow at the School of Natural Sciences and Psychology at Liverpool John Moores University, explains "Our hominin ancestors would have been unaware of the tectonic influence on their habitats, but instead would have been attracted by the range of food and shelter offered."

The combination of drinking water, steep cliffs that provided shelter from predators, together with a range of feeding sources constitute the key ingredients for an ideal habitat for our ancestors.

Arctic Blooms Occurring Earlier: Phytoplankton Peak Arising 50 Days Early, With Unknown Impacts on Marine Food Chain and Carbon Cycling

2011-03-03T16:38:00.000-08:00

Phytoplankton peak arising up to 50 days early, with unknown impacts on marine food chain and carbon cycling

Warming temperatures and melting ice in the Arctic may be behind a progressively earlier bloom of a crucial annual marine event, and the shift could hold consequences for the entire food chain and carbon cycling in the region.

Scientists at Scripps Institution of Oceanography at UC San Diego, along with colleagues in Portugal and Mexico, plotted the yearly spring bloom of phytoplankton -- tiny plants at the base of the ocean food chain -- in the Arctic Ocean and found the peak timing of the event has been progressing earlier each year for more than a decade. The researchers analyzed satellite data depicting ocean color and phytoplankton production to determine that the spring bloom has come up to 50 days earlier in some areas in that time span.

The earlier Arctic blooms have roughly occurred in areas where ice concentrations have dwindled and created gaps that make early blooms possible, say the researchers, who publish their findings in the March 9 edition of the journal Global Change Biology.

During the one- to two-week spring bloom, which occurs in warm as well as cold regions, a major influx of new organic carbon enters the marine ecosystem through a massive peak in phytoplankton photosynthesis, which converts carbon dioxide into organic matter as part of the global carbon cycle. Phytoplankton blooms stimulate production of zooplankton, microscopic marine animals, which become a food source for fish.

Mati Kahru, lead author of the study and a research oceanographer in the Integrative Oceanography Division at Scripps, said it's not clear if the consumers of phytoplankton are able to match the earlier blooms and avoid disruptions of their critical life-cycle stages such as egg hatching and larvae development.

"The spring bloom provides a major source of food for zooplankton, fish and bottom-dwelling animals," he said. "The advancement of the bloom time may have consequences for the Arctic ecosystem."

Such a match or mismatch in timing could explain much of the annual variability of fish stocks in the region.

"The trend towards earlier phytoplankton blooms can expand into other areas of the Arctic Ocean and impact the whole food chain," say the authors, who used satellite data from 1997-2010 to create their bloom maps.

The NASA Ocean Biology and Biogeochemistry Program and the National Science Foundation provided financial support for the research. The satellite data were provided by the NASA Ocean Biology Processing Group, ESA GlobColour group, the National Snow and Ice Data Center and the Japan Aerospace Exploration Agency.

Kahru's coauthors include Greg Mitchell, a Scripps Oceanography research biologist, Vanda Brotas of the University of Lisbon in Portugal and Marlenne Manzano-Sarabia of Universidad Autónoma de Sinaloa in Mexico.

Mapping Human Vulnerability to Climate Change

2011-03-03T16:37:00.000-08:00

Researchers already study how various species of plants and animals migrate in response to climate change. Now, Jason Samson, a PhD candidate in McGill University's Department of Natural Resource Sciences, has taken the innovative step of using the same analytic tools to measure the impact of climate change on human populations. Samson and fellow researchers combined climate change data with censuses covering close to 97 per-cent of the world's population in order to forecast potential changes in local populations for 2050.

Samson's team found that if populations continue to increase at the expected rates, those who are likely to be the most vulnerable to climate change are the people living in low-latitude, hot regions of the world, places like central South America, the Arabian Peninsula and much of Africa. In these areas, a relatively small increase in temperature will have serious consequences on a region's ability to sustain a growing population."It makes sense that the low latitude tropical regions should be more vulnerable because the people there already experience extremely hot conditions which make agriculture challenging. An increase in temperature over the next few decades will only make their lives more difficult in a variety of ways," says Samson.

This contrasts with Samson's predictions about the impact of climate change on human populations in the high-latitude more temperate zones of the world, where the temperature change is expected to be greater. Because the spread of human populations along with their activities are already more constrained by the cooler conditions in these regions, the researchers expect that climate change will have less of an impact on people living in these areas.

The study also points to clear inequities in the causes and consequences of climate change: the countries that have contributed the least to climate change, based on their average per-capita carbon dioxide emissions, are nevertheless predicted to be the most vulnerable to its impacts. "Take Somalia for instance," suggests Samson."Because it's so hot there, it's already very difficult to grow things, and it will only become more difficult if the temperature rises. It's also clear that Somalia is not a big contributor of greenhouse gas to the atmosphere. Now thanks to this map, we have concrete quantitative evidence of the disparity between the causes and the consequences of climate change at a national level."

Samson anticipates this data could be useful for decision makers around the world in the ongoing international negotiations around climate change.

The research was funded by the Natural Sciences and Engineering Council of Canada (NSERC).

New Method for Accurate Diagnosis of Gall Bladder Cancer

2011-03-03T16:35:00.000-08:00

Researchers a the University of Granada and the Department of Nuclear Medicine, Hospital Virgen de las Nieves at Granada found that the metabolic imaging diagnosis technique -- based on the analysis of a structural analog of glucose labeled with a positron-emitting compound (18F) -- allows early diagnosis of gall bladder cancer, a relatively rare disease with high mortality rates among most patients suffering from it.

For the purpose of this study, 62 patients were subjected to this scanning method, which represents the largest sample of patients with gall bladder cancer ever studied by applying this type of technology -- called FDG positron emission tomography. The study reported excellent results, significantly better than other structural imaging methods, and enabled more accurate and appropriate diagnosis and treatment of patients, which allows to avoid unnecessary procedures.

This study was conducted by Sc.D Carlos Ramos Font and directed by professors Nicolás Olea Serrano (UGR), José Manuel Llamas Elvira (UGR and Department of Nuclear Medicine, Hospital Virgen de las Nieves and Manuel Gómez Río (Department of Nuclear Medicine, Hospital Virgen de las Nieves).

Early Diagnosis Is Essential

The high mortality rate among patients with gall bladder cancer depends heavily on the lack of clinical data enabling early diagnosis of this type of tumors. This fact determines the survival of this type of patients. At the moment of establishing a diagnosis, an accurate staging will allow to chose the most appropriate treatment, as well as to optimize the use of the resources available. Imaging diagnosis of this pathology is essentially based on morphological techniques (echography, X-ray computed tomography and magnetic resonance imaging).

This new imaging diagnosis method (tomography made by emission of positrons with ¹⁸F fluorodeoxyglucose) shows glucose metabolism in tissues. While the utility of this method has been proved in other types of tumors, its utility in gall bladder cancer had not been proved yet.

According to Granada University researchers, their study proves that positron emission tomography scanning wih FDG "is a valid and accurate method for precise staging of patients with suspected gall bladder cancer, which allows to determine the appropriate therapy and treatment, and to optimize the use of the resources available." Thus, they suggest that "each patient with suspected cancer should be subjected to this type of imaging diagnosis, to determine the nature of such process."

The results obtained from this study were partially published in the American Journal of Surgery (2004), the Journal of Surgical Oncology (2006) and the Revista Española de Medicina Nuclear (2009) [Spanish Journal of Nuclear Medicine].

Diet soda may be tied to heightened risk of stroke, study claims

2011-03-03T16:14:00.000-08:00

DIET soda drinkers are probably doing their waistlines a favor, but may also be boosting their risk of having a stroke, according to research released by researchers from the University of Miami Miller School of Medicine.

The study monitored the health of more than 2500 patients over nearly a decade.
They answered lengthy questionnaires about nutrition along the way and were monitored for several conditions.
In the time they were under evaluation, 559 of the test subjects experienced vascular events, including strokes caused by hemorrhage and those caused by clots.
Controlling for several factors, including age, smoking and alcohol intake, those who drank diet soda daily were 61 percent more likely than the rest to experience a stroke.
Even when taking into account people with existing vascular disease, the link still held. Study authors did not find any connection between regular soda and strokes.
Soft drinks of any kind, diet or sugary, are linked to several health problems.
People who drink one can of soda a day are more likely to have several risk factors for diabetes and cardiovascular disease including high blood pressure, elevated triglycerides, and high fasting blood sugar levels.
While the link is strong between diet soda and stroke risk, it does not prove cause and effect.
Study authors said further research should be done on the subject.
Stroke is the third leading cause of death in the US behind heart disease and cancer.

Mobile phones may help reverse Alzheimer's disease

2011-03-03T16:12:00.001-08:00

DESPITE the debate that radiation from mobile phones can cause brain cancer a new study has found a possible health benefit that the electromagnetic waves may protect against and even reverse Alzheimer's disease.

The debate has raged for years on the dangers of mobile phones and whether the radiation emitted from the devices cause brain tumours.
But researchers at the University of South Florida found mobile phones might be good for users after conducting a study that exposed 96 mice, most of whom had been genetically altered to develop the Alzheimer's disease as they aged, to electromagnetic waves generated by mobile phones.
The mice were zapped with 918MHz of frequency twice a day for one hour each time over a period of seven to nine months - the equivalent of several decades in humans.
In older mice with Alzheimer's, long-term exposure to the electromagnetic fields caused deposits in the brain of beta-amyloid, a protein fragment that accumulates in the brain of Alzheimer's sufferers to form the disease's signature plaques, to be erased.

Memory impairment in the older mice disappeared, too, the study showed.
Young adult mice with no apparent signs of memory impairment were protected against Alzheimer's disease after several months of exposure to the mobile phone waves, the study showed.
And the memory levels of normal mice with no genetic predisposition for Alzheimer's disease were boosted after exposure to the electromagnetic waves.
The study was the first to look at the long-term effects of mobile phone exposure in mice or humans and its findings took even the researchers by surprise.
"Frankly, I started this work a few years ago with a hypothesis that the electromagnetic fields from a mobile phone would be deleterious to Alzheimer's mice," lead author Gary Arendash, a professor at the University of Southern Florida, said.
Based on the findings in mice, the researchers hoped electromagnetic field exposure could be an effective, non-invasive and drug-free way to prevent and treat Alzheimer's disease in humans.

Researchers Assess Severity of Prostate Cancers Using Magnetic Resonance Imaging

2011-03-03T09:33:00.000-08:00

Rutgers researchers are developing methods that can accurately assess the severity of prostate cancer by analyzing magnetic resonance images and spectra of a patient's prostate gland. This may help physicians decide more confidently which patients need aggressive treatment and which are better served by "watchful waiting," and could even postpone or eliminate invasive biopsies in patients with low-grade tumors.

In a presentation next month at the world's premier medical image analysis conference, Rutgers biomedical engineers will report that they achieved over 90% accuracy in distinguishing low-grade from high-grade prostate cancers by running computer analyses of the images and spectra made on 19 patients in an early research study.

"The breakthrough we've had in the last few months is that we see image signatures that distinguish aggressive cancers from less aggressive ones," said Anant Madabhushi, associate professor of biomedical engineering at Rutgers and a member of The Cancer Institute of New Jersey (CINJ).

These studies build on earlier research at Rutgers and elsewhere to identify prostate cancer using powerful, high-resolution magnetic resonance imaging (MRI) technology.

"Now we're getting beyond merely identifying whether a person has cancer or not," he said. "This could lead to better patient management and cost savings."

Biomedical engineering graduate student Pallavi Tiwari will present research results and describe image analysis techniques at the Medical Image Computing and Computer Assisted Intervention (MICCAI) Conference in Bejing, China, on Sept. 22.

Tiwari and Madabhushi worked with John Kurhanewicz, professor of radiology and biomedical imaging at the University of California, San Francisco, to obtain prostate gland images from 19 patients who later had radical prostatectomies. They examined both traditional magnetic resonance (MR) images, which provide two-dimensional pictures of the gland's cellular structure, and MR spectroscopy, which maps concentrations of certain chemicals to locations in the prostate gland. Changes in concentrations of these chemical metabolites -- choline, creatine and citrate -- indicate the presence of cancer.

The researchers compared the MR images and spectra to digital images of the actual excised glands, which pathologists identified as having high-grade (aggressive) or low-grade (indolent) tumors using the established Gleason Grading System. They used pattern recognition techniques to recognize characteristics of areas in the MR images and spectra that corresponded to the cancerous tissue in the excised samples. This involved using computerized tools to align the MR views with digitized images of tissue slices, and to match the different resolutions of the images and spectra.

The objective is to "teach" the computer system to accurately and consistently recognize image patterns that correspond to various grades of cancerous tissue without having the tissue samples available to manually verify.

Madabhushi notes that the techniques will have to be evaluated on more people before they can be considered for clinical use. However, he is encouraged by the early results.

Each year, there are more than 27,000 deaths from prostate cancer in the United States and 190,000 new cases diagnosed. Most clinical diagnoses today are based on PSA levels in blood, physical examinations and needle biopsies. While one in six men might expect to get prostate cancer in their lifetimes, only one in 34 will die of it. Recent studies, including one at CINJ, suggest that men with low-risk cancers are receiving aggressive treatment. Improved diagnostic methods such as the Rutgers work could help patients with low-risk cancers and their physicians feel more confident with watchful waiting.

Also collaborating with the Rutgers researchers was Mark Rosen, associate professor of radiology at the Hospital of the University of Pennsylvania. Funding was provided by the Wallace H. Coulter Foundation, the National Cancer Institute, CINJ, the U.S. Department of Defense and Bioimagene, Inc.

Headgear, Mouth Guards Have Little or No Impact on Reducing Concussions in Rugby Players, Study Finds

2011-03-03T09:31:00.001-08:00

Existing headgear and mouth guards have limited or no benefit in reducing concussions in rugby players, according to Dr. Michael Cusimano, a neurosurgeon at St. Michael's Hospital.

However, educational injury prevention programs that promote proper playing techniques and enforcement of the rules do result in a significant reduction in concussions and head, neck and spinal injuries, Cusimano concluded after a review of existing studies on the topic.

Cusimano still recommends rugby players wear mouth guards and protective headgear because of the strong evidence they reduce mouth and face injuries and scalp lacerations and abrasions. He said equipment companies should be encouraged to develop more sophisticated headgear that could reduce injury risk. Current rugby headgear is soft-shelled, has thin padding and is primarily designed to protect the ears and the back of the head.

His findings were published in the November issue of the journal Neurosurgery, currently available on-line.

Professional rugby players suffer 91 injuries per 1,000 player hours, with each injury requiring an average of 18 days to recover and return to play. Concussion is the third most common match injury, accounting for 62 per cent of match head injuries. Cusimano said the number of concussions may be under-reported because of the International Rugby Board rule that athletes can't return to play for three weeks after suffering a concussion unless they are cleared by a neurologist.

Spinal injuries account for 9 per cent of time lost to match injuries by professional English players, occurring at a rate of up to 10.9 per 1,000 player hours.

"A large number of players, coaches and referees believe that equipment such as mouth guards and headgears may prevent brain injuries in rugby," Cusimano said. "Our study was the first to summarize what did and what did not work. Equipment such as headgear and mouth guards are ineffective at preventing neurological injuries, but other strategies, such as education and rule changes, have been shown to be effective. These sorts of strategies should be made available to all rugby players so that these athletes can spend more time playing on the field than recovering off of the field."

The New Zealand Rugby Union and the country's Accident Compensation Corp. developed a 10-point RugbySmart injury prevention program in 2001 that has resulted in a 13 per cent decrease in neck, back and spine injuries and a reduction in the mean number of days between an injury and a player seeking treatment (4.27 days, down from six). This also resulted in a savings of $609,690 (U.S.) from decreased compensation claims to the ACC.

Virus-Mimicking Nanoparticles Can Stimulate Long-Lasting Immunity

2011-03-03T09:00:00.000-08:00

Vaccine scientists say their "Holy Grail" is to stimulate immunity that lasts for a lifetime. Live viral vaccines such as the smallpox or yellow fever vaccines provide immune protection that lasts several decades, but despite their success, scientists have remained in the dark as to how they induce such long lasting immunity.

Scientists at the Emory Vaccine Center have designed tiny nanoparticles that resemble viruses in size and immunological composition and that induce lifelong immunity in mice. They designed the particles to mimic the immune‑stimulating effects of one of the most successful vaccines ever developed -- the yellow fever vaccine. The particles, made of biodegradable polymers, have components that activate two different parts of the innate immune system and can be used interchangeably with material from many different bacteria or viruses.

The results are described in this week's issue of Nature.

"These results address a long‑standing puzzle in vaccinology: how do successful vaccines induce long-lasting immunity?" says senior author Bali Pulendran, PhD, Charles Howard Candler professor of pathology and laboratory medicine at Emory University School of Medicine and a researcher at Yerkes National Primate Research Center.

"These particles could provide an instant way to stretch scarce supplies when access to viral material is limited, such as pandemic flu or during an emerging infection. In addition, there are many diseases, such as HIV, malaria, tuberculosis and dengue, that still lack effective vaccines, where we anticipate that this type of immunity enhancer could play a role."

One injection of the live viral yellow fever vaccine, developed in the 1930s by Nobel Prize winner Max Theiler, can protect against disease‑causing forms of the virus for decades. Pulendran and his colleagues have been investigating how humans respond to the yellow fever vaccine, in the hopes of imitating it.

Several years ago, they established that the yellow fever vaccine stimulated multiple Toll‑like receptors (TLRs) in the innate immune system. TLRs are present in insects as well as mammals, birds and fish. They are molecules expressed by cells that can sense bits of viruses, bacteria and parasites and can activate the immune system. Pulendran's group demonstrated that the immune system sensed the yellow fever vaccine via multiple TLRs, and that this was required for the immunity induced by the vaccine.

"TLRs are like the sixth sense in our bodies, because they have an exquisite capacity to sense viruses and bacteria, and convey this information to stimulate the immune response," Pulendran says. "We found that to get the best immune response, you need to hit more than one kind of Toll‑like receptor. Our aim was to create a synthetic particle that accomplishes this task."

Emory postdoctoral fellow Sudhir Pai Kasturi, PhD, created tiny particles studded with molecules thatturn on Toll‑like receptors. He worked with colleague Niren Murthy, PhD, associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

"We are very excited about building on this platform to design improved vaccines for existing and emerging infectious diseases" says Kasturi, the primary author working in Pulendran's lab at the Emory Vaccine Center. One of the particles' components is MPL (monophosphoryl lipid A), a component of bacterial cell walls, and the other is imiquimod, a chemical that mimics the effects of viral RNA. The particles are made of PLGA -- poly(lactic acid)‑co‑(glycolic acid) -- a synthetic polymer used for biodegradable grafts and sutures.

All three components are FDA‑approved for human use individually. For several decades, the only FDA‑approved vaccine additive was alum, until a cervical cancer vaccine containing MPL was approved in 2009. Because of immune system differences between mice and monkeys, the scientists replaced imiquimod with the related chemical resiquimod for monkey experiments.

In mice, the particles can stimulate production of antibodies to proteins from flu virus or anthrax bacteria several orders of magnitude more effectively than alum, the authors found. In addition, the immune cells persist in lymph nodes for at least 18months, almost the lifetime of a mouse. In experiments with monkeys, nanoparticles with viral protein could induce robust responses greater than five times the response induced by a dose of the same viral protein given by itself, without the nanoparticles.

The research was supported by the National Institutes of Health and the Bill and Melinda Gates Foundation.

Pomegranate Juice Components Could Stop Cancer from Spreading, Research Suggests

2011-03-03T08:57:00.000-08:00

Researchers at the University of California, Riverside have identified components in pomegranate juice that both inhibit the movement of cancer cells and weaken their attraction to a chemical signal that promotes the metastasis of prostate cancer to the bone. The research could lead to new therapies for preventing cancer metastasis.

Performed in the lab of Manuela Martins-Green, a professor of cell biology, the research was presented Dec. 12, 2010 at the 50th annual meeting of the American Society for Cell Biology taking place in Philadelphia.

Prostate cancer is the second-leading cause of cancer-related deaths in men in the United States. To date, there is no cure for it. If prostate cancer recurs after treatments of surgery and/or radiation, usually the next treatment is the suppression of the male hormone testosterone, which inhibits the growth of the cancer cells because they need this hormone to grow. But over time, the cancer develops ways to resist hormone suppression therapies, becomes very aggressive, and metastasizes to the bone marrow, lungs, and lymph nodes, usually resulting in the patient's death.

The Martins-Green lab applied pomegranate juice on laboratory-cultured prostate cancer cells that were resistant to testosterone (the more resistant a cancer cell is to testosterone, the more prone it is to metastasizing).

The researchers -- Martins-Green, graduate student Lei Wang and undergraduate students Andre Alcon and Jeffrey Ho -- found that the pomegranate juice-treated tumor cells that had not died with the treatment showed increased cell adhesion (meaning fewer cells breaking away) and decreased cell migration.

Next, the researchers identified the following active groups of ingredients in pomegranate juice that had a molecular impact on cell adhesion and migration in metastatic prostate cancer cells: phenylpropanoids, hydrobenzoic acids, flavones and conjugated fatty acids.

"Having identified them, we can now modify cancer-inhibiting components in pomegranate juice to improve their functions and make them more effective in preventing prostate cancer metastasis, leading to more effective drug therapies," Martins-Green said. "Because the genes and proteins involved in the movement of prostate cancer cells are essentially the same as those involved in the movement of other types of cancer cells, the same modified components of the juice could have a much broader impact in cancer treatment."

Martins-Green explained that an important protein produced in the bone marrow causes the cancer cells to move to the bone where they can then form new tumors.

"We show that pomegranate juice markedly inhibits the function of this protein, and thus this juice has the potential of preventing metastasis of the prostate cancer cells to the bone," Martins-Green said.

Next, her lab plans to do additional tests in an in vivo model for prostate cancer metastasis to determine whether the same cancer-inhibiting components that work in cultured cells can prevent metastasis without side effects.

Spinal Cord Injury: Human Cells Derived from Stem Cells Restore Movement in Animal Models

2011-03-03T08:54:00.000-08:00

For the first time, scientists discovered that a specific type of human cell, generated from stem cells and transplanted into spinal cord injured rats, provide tremendous benefit, not only repairing damage to the nervous system but helping the animals regain locomotor function as well.

The study, published March 2 in the journal PLoS ONE, focuses on human astrocytes -- the major support cells in the central nervous system -- and indicates that transplantation of these cells represents a potential new avenue for the treatment of spinal cord injuries and other central nervous system disorders.
Working together closely, research teams at the University of Colorado School of Medicine and University of Rochester Medical Center have made a major breakthrough in the use of human astrocytes for repairing injured spinal cords in rats.
"We've shown in previous research that the right types of rat astrocytes are beneficial, but this study brings it up to the human level, which is a huge step," said Chris Proschel, Ph.D., lead study author and assistant professor of Genetics at the University of Rochester Medical Center. "What's really striking is the robustness of the effect. Scientists have claimed repair of spinal cord injuries in rats before, but the benefits have been variable and rarely as strong as what we've seen with our transplants."
There is one caveat to the finding -- not just any old astrocyte will do. Using stem cells known as human fetal glial precursor cells, researchers generated two types of astrocytes by switching on or off different signals in the cells. Once implanted in the animals, they discovered that one type of human astrocyte promoted significant recovery following spinal cord injury, while another did not.
"Our study is unique in showing that different types of human astrocytes, derived from the exact same population of human precursor cells, have completely different effects when it comes to repairing the injured spinal cord," noted Stephen Davies, Ph.D., first author and associate professor in the Department of Neurosurgery at the University of Colorado School of Medicine. "Clearly, not all human astrocytes are equal when it comes to promoting repair of the injured central nervous system."
The research teams from Rochester and Colorado also found that transplanting the original stem cells directly into spinal cord injured rats did not aid recovery. Researchers believe this approach -- transplanting undifferentiated stem cells into the damaged area and hoping the injury will cause the stem cells to turn into the most useful cell types -- is probably not the best strategy for injury repair.
According to Mark Noble, director of the University of Rochester Stem Cell and Regenerative Medicine Institute, "This study is a critical step toward the development of improved therapies for spinal cord injury, both in providing very effective human astrocytes and in demonstrating that it is essential to first create the most beneficial cell type in tissue culture before transplantation. It is clear that we cannot rely on the injured tissue to induce the most useful differentiation of these precursor cells."
To create the different types of astrocytes used in the experiment, researchers isolated human glial precursor cells, first identified by Margot Mayer-Proschel, Ph.D., associate professor of Genetics at the University of Rochester Medical Center, and exposed these precursor cells to two different signaling molecules used to instruct different astrocytic cell fate -- BMP (bone morphogenetic protein) or CNTF (ciliary neurotrophic factor) .
Transplantation of the BMP human astrocytes provided extensive benefit, including up to a 70% increase in protection of injured spinal cord neurons, support for nerve fiber growth and recovery of locomotor function, as measured by a rat's ability to cross a ladder-like track.
In contrast, transplantation of the CNTF astrocytes, or of the stem cells themselves, failed to provide these benefits. Researchers are currently investigating why BMP astrocytes performed so much better than CNTF astrocytes, but believe multiple complex cellular mechanisms are probably involved.
"It is estimated that astrocytes make up the vast majority of all cell types in the human brain and spinal cord, and provide multiple different types of support to neurons and other cells of the central nervous system," said Jeannette Davies, Ph.D., assistant professor at the University of Colorado School of Medicine and co-lead author of the study. "These multiple functions are likely to all be contributing to the ability of the right human astrocytes to repair the injured spinal cord."
With these results, the Proschel and Davies teams are moving forward on the necessary next steps before they can implement the approach in humans, including testing the transplanted human astrocytes in different injury models that resemble severe, complex human spinal cord injuries at early and late stages after injury.
"Studies like this one bring increasing hope for our patients with spinal cord injuries," said Jason Huang, M.D., associate professor of Neurosurgery at the University of Rochester Medical Center and Chief of Neurosurgery at Highland Hospital. "Treating spinal cord injuries will require a multi-disciplinary approach, but this study is a promising one showing the importance of modifying human astrocytes prior to transplantation and has significant clinical implications."
In addition to Proschel and Noble, Davies and Davies, Mayer-Proschel and Chung-Hsuan Shih from the University of Rochester Medical Center contributed to the research. Portions of this research were funded by the New York State Spinal Cord Injury Research Program, the Carlson Stem Cell Fund and private donations by the international spinal cord injury community.