November 3, 2006, 5:04 AM CT

T-ray breakthrough

Scientists at the University of Bath, UK, and in Spain have said they have found a way to control the flow of terahertz radiation down a metal wire. Their findings are set out in a letter reported in the current journal Physical Review Letters.

Terahertz radiation, whose frequency is around one thousand billion cycles a second, bridges the gap between the microwave and infrared parts of the electromagnetic spectrum.

Materials interact with radiation at T-ray frequencies in different ways than with radiation in other parts of the spectrum, making T-rays potentially important in detecting and analysing chemicals by examining how they absorb T-rays fired at them.

This would allow quality control of prescribed drugs and detection of explosives to be carried out more easily, as a number of complex molecules have distinctive 'signatures' in this part of the electromagnetic spectrum.

T-ray applications are presently limited by the relatively poor ability to focus the rays, which is achieved using the conventional means of lenses and mirrors to focus the radiation. This limits the spot size of focused T-rays to a substantial fraction of a millimetre and this has made studies of small objects such as biological cells with high resolution are virtually impossible.........

Posted by: Kevin      Permalink         Source

November 3, 2006, 4:39 AM CT

Low Folate Diets Increase Risk Of Colorectal Cancer

A new study by scientists at the MUHC has revealed that a diet low in folate may increase the risk of developing colorectal cancer. Published in the scientific journal Cancer Research today, the study not only illustrates a way to prevent the disease but also provides further insight into the mechanisms of the disease, which could lead to novel therapies. Using animal models, the MUHC study is the first to demonstrate directly that diets low in folate cause colorectal cancer, and follows on the heels of earlier research by the same team that revealed how high folate diets can protect against heart disease.

"This research, which is consistent with previous epidemiological studies in humans, demonstrates a clear link between low dietary folate and the initiation of colorectal cancer in animal models," says Dr. Rima Rozen, Scientific Director of the Montreal Children's Hospital, Deputy Scientific Director of the MUHC, and lead investigator in the study. "None of the mice fed a control diet developed tumours whereas 1 in 4 mice on the folate-deficient diet developed at least one tumour".

Possible mechanisms of the disease were also investigated using molecular biological techniques. "The study shows that a low level of dietary folate may cause an increase in DNA damage, which plays a role in the development of tumours," noted Dr. Rozen. The study also reveals that folate deficiency causes genes which usually respond to DNA damage to behave abnormally, also contributing to the development of tumours. The results suggest that a diet containing sufficient folate may reduce the risk of developing colorectal cancer.........

Posted by: Sean      Permalink         Source

November 2, 2006, 9:14 PM CT

Computer with Brain Connections

Fundamental theories regarding consciousness, emotion and quality of life in sufferers of paralysis from Amyotrophic Lateral Sclerosis (ALS, also known as 'Lou Gerhig's disease') are being challenged based on new research on brain-computer interaction. ALS is a progressive disease that destroys neurons affecting movement. The study appears in the latest issue of Psychophysiology. The article reviews the usefulness of currently available brain-computer -interfaces (BCI), which use brain activity to communicate through external devices, such as computers.

The research focuses on a condition called the completely locked-in state (CLIS, a total lack of muscle control). In a CLIS situation, intentional thoughts and imagery can rarely be acted upon physically and, therefore, are rarely followed by a stimulus. The research suggests that as the disease progresses and the probability for an external event to function as a link between response and consequence becomes progressively smaller, it may eventually vanish altogether.

Researchers have found that by implementing a BCI before the CLIS state occurs, a patient can be taught to communicate through an electronic device with great regularity. The continued interaction between thought, response and consequence is believed to slow the destruction of the nervous system.........

Posted by: Kevin      Permalink         Source

November 2, 2006, 8:47 PM CT

Alzheimer's Drug Shows Promise

The only drugs currently available for Alzheimer's patients are those that alleviate symptoms, but a team of researchers led by Paul Aisen, MD, director of the Memory Disorders program at Georgetown University Medical Center, is testing a new class of drugs that actually target the molecule believed to cause the disease. Aisen and colleagues report that a compound called tramiprosate reduced levels of a marker for the progression of Alzheimer's disease in a Phase II clinical trial in the November 1 electronic version of Neurology.

"Everyone wants to figure out how to create an Alzheimer's therapy that attacks the amyloid peptide, which is considered to be the molecular cause of the disease," said Aisen. "This is the most advanced anti-amyloid therapy that exists-it has the potential for slowing down progression of the disease".

Aisen and his team are currently in the midst of Phase III clinical trials on tramiprosate (manufactured by Neurochem, for which Aisen is a scientific advisor, as ALZHEMED-) and hope to have results by early next summer. Media should call 202-687-5100 to schedule an interview with Aisen or to be connected with another Georgetown expert on the topic.........

Posted by: Sean      Permalink         Source

November 2, 2006, 8:38 PM CT

human-Neandertal mixing

A reexamination of ancient human bones from Romania reveals more evidence that humans and Neandertals interbred.

Erik Trinkaus, Ph.D., Washington University Mary Tileston Hemenway Professor in Arts & Sciences, and his colleagues radiocarbon-dated and analyzed the shapes of human bones from Romania's Pe?tera Muierii (Cave of the Old Woman). The fossils, discovered in 1952, add to the small number of early modern human remains from Europe known to be more than 28,000 years old.

Results were reported in the current issue of the Proceedings of the National Academy of Science.

The team observed that the fossils were 30,000 years old and principally have the diagnostic skeletal features of modern humans. They also observed that the remains had other features known, among potential ancestors, primarily among the preceding Neandertals, providing more evidence there was mixing of humans and Neandertals as modern humans dispersed across Europe about 35,000 years ago. Their analysis of one skeleton's shoulder blade also shows that these humans did not have the full set of anatomical adaptations for throwing projectiles, like spears, during hunting.

The team says that the mixture of human and Neandertal features indicates that there was a complicated reproductive scenario as humans and Neandertals mixed, and that the hypothesis that the Neandertals were simply replaced should be abandoned.........

Posted by: William      Permalink         Source

November 2, 2006, 5:23 AM CT

MRI Study To Prevent Brain Damage

A stroke victim arrives in the emergency room and, within minutes, the doctor must make a decision: Should drugs be administered to open up the blocked blood vessel and prevent further brain damage? Or is this patient at high risk for suffering a brain hemorrhage if the blocked vessel is opened?

Greg Albers, MD, director of the Stanford Stroke Center, and his team report in the recent issue of Annals of Neurology that new magnetic resonance imaging techniques can discriminate between stroke patients who are likely to benefit from a stroke medicine - even when administered beyond the currently approved three-hour time window - and those for whom treatment is unlikely to be beneficial and may cause harm.

For years, Albers, professor of neurology and neurological sciences at the Stanford University School of Medicine, has been using new MRI techniques to visualize the damage from stroke while it is actually happening. His goal is to differentiate brain tissue that is potentially salvageable from tissue that is already irreversibly injured by a stroke. As his group accumulated MRI scans of stroke patients, they noticed patterns that seemed to identify which patients were most likely to benefit from opening up blocked blood vessels.

"One of the criticisms was that these detailed brain images looked beautiful and interesting, but there was no proof that they should be used to influence treatment or that they would result in improved outcomes," said Albers. "How do you know that these MRI patterns can predict whether the therapy is likely to be beneficial?".........

Posted by: Sean      Permalink         Source

November 2, 2006, 5:03 AM CT

Serotonin Child Abuse Link

A research team found that when baby rhesus monkeys endured high rates of maternal rejection and mild abuse in their first month of life, their brains often produced less serotonin, a chemical that transmits impulses in the brain. Low levels of serotonin are associated with anxiety and depression and impulsive aggression in both humans and monkeys.

Abused females who became abusive mothers in adulthood had lower serotonin in their brains than abused females who did not become abusive parents, the research showed.

Because the biological make up of humans and monkeys is quite similar, the findings from the monkey research could be valuable in understanding human child abuse, said Dario Maestripieri, Associate Professor in Comparative Human Development at the University of Chicago.

"This research could have important implications for humans because we do not fully understand why some abused children become abusive parents and others don't," Maestripieri said. The research suggests that treatments with drugs that increase brain serotonin early in an abused child's life could reduce the likelihood that the child will grow up to become abusive, Maestripieri said.

Maestripieri is lead author of a paper reporting the research, "Early Maternal Rejection Affects the Development of Monoaminergic Systems and Adult Abusive Parenting in Rhesus Macaques" published in the current issue of Behavioral Neuroscience.........

Posted by: Sean      Permalink         Source

November 1, 2006, 8:03 PM CT

Climate Change Tops Environmental Concerns

As per a recent MIT survey, Americans now rank climate change as the country's most pressing environmental problem--a dramatic shift from three years ago, when they ranked climate change sixth out of 10 environmental concerns.

Almost three-quarters of the respondents felt the government should do more to deal with global warming, and individuals were willing to spend their own money to help.

"While terrorism and the war in Iraq are the main issues of national concern, there's been a remarkable increase in the American public's recognition of global warming and their willingness to do something about it," said Stephen Ansolabehere, MIT's Elting R. Morison Professor of Political Science.

The survey results were released Oct. 31 at the seventh annual Carbon Sequestration Forum, an international meeting held at MIT that focuses on methods of capturing and storing emissions of carbon dioxide--a major contributor to climate change.

Ansolabehere's colleagues on the work are Howard Herzog, principal research engineer in MIT's Laboratory for Energy and the Environment (LFEE), LFEE research associates Thomas E. Curry and Mark de Figueiredo, and Professor David M. Reiner of the University of Cambridge.

The findings are a result of two surveys, the first administered in September 2003 and the follow-up in September 2006. Each survey included about 20 questions focusing on the environment, global warming and a variety of climate-change-mitigation technologies.........

Posted by: Tyler      Permalink         Source

November 1, 2006, 7:48 PM CT

A Biomaterial Blend Library

From dental implants to hip replacements, biomaterials have become big business. But researchers pursuing this modern medical revolution share a basic challenge: biocompatibility. How will a biomaterial on the lab bench actually work inside the human body? Will a patient accept the new material or suffer an inflammatory response? And can that material survive in a human's complex system?

To tackle such questions, scientists at the National Institute of Standards and Technology (NIST) and the New Jersey Center for Biomaterials (NJCB) at Rutgers University have developed new methods to analyze the interactions between cells and biomaterials. Their work could lead to inexpensive techniques for building better biomaterials.

Polymers derived from the amino acid tyrosine make up a broad class of degradable biomaterials under investigation. Such materials provide a temporary scaffold for cells to grow and tissue to regenerate. In a 2006 study* presented at the national meeting of the American Chemical Society in September, the scientists analyzed how two types of model cells-immune cells known as macrophages and bone cells known as osteoblasts-responded to changes in the composition of thin films made of these tyrosine-derived polymers. In practice, a number of biomaterials are made from blends of polymers to achieve specific material properties. Optimizing the blend composition is often a difficult and time-consuming task. As the blends gained a higher or lower proportion of a respective material, the cells around them react by changing shape, ultimately increasing or decreasing contact with the films. In the body, such cell-material dynamics are critically important to the outcome-determining whether a biomaterial leads to inflammation or abnormal cell growth, for example.........

Posted by: Kevin      Permalink         Source

November 1, 2006, 4:18 PM CT

Old Leaves Need To Die In Time

In a study from the recent issue of The American Naturalist, scientists Alex Boonman and co-workers from the Netherlands show that it is beneficial for plants growing in a dense stand to shed their oldest, lower leaves once these become shaded. By using transgenic tobacco plants that do not shed their lower leaves, they were able to show that shaded old leaves become a burden to a plant because they no longer photosynthesize but still require energy to be maintained.

Moreover, the nutrients in these leaves can be more usefully employed by the plant when re-allocated to new leaves at the top of the canopy, where more light is available and higher photosynthetic rates can be attained. Previously, theoretical modeling has been extensively used to investigate how plants should distribute their leaf area and nutrients to maximize their photosynthesis and fitness. However, a direct experimental test was lacking till now.

"Keeping up with the neighbors is important for plants in leaf canopies" Alex Boonman states, "because failure to project enough leaf area at the top of the canopy means that some other plant will do it, with shading and therefore diminished photosynthesis as the consequence." The transgenics, which were originally developed by Susheng Gan and Richard Amasino at the University of Wisconsin, indeed produced less leaf area in the upper canopy layer than normal plants and performed less well in competition exeriments.........

Posted by: Jessica      Permalink         Source