November 15, 2006, 9:33 PM CT

New Way To Manipulate DNA

Polymers, large molecules comprised of chains of repeating structures, are used in everything from the coatings on walls of ships and pipes to reduce flow drag to gene therapy.

But long polymer chains are subject to breakage, called scission, and a new study by the University of Michigan shows that as it turns out, much of what scientists previously thought about why polymers break when subjected to strong flows, such as waves crashing against a ship's bow, was wrong.

This is important for a few reasons, said Michael Solomon, associate professor in the Department of Chemical Engineering, Macromolecular Science and Engineering Program. Broken polymers don't function as intended, and if scientists don't know what causes them to break, they can't keep them from breaking, nor can they design them to break in specific places.

For the past 40 years, scientists have not understood exactly which forces caused scission, said Solomon, who is the co-author on a paper published last week in the Proceedings of the National Academy of Sciences. The paper, "Universal scaling for polymer chain scission in turbulence," defines which flow forces and at what levels those forces cause polymers to break in turbulence.

"This paper understands how they are breaking in a new way that resolves some issues that have been present for 40 years," Solomon said.........

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November 15, 2006, 5:02 AM CT

Obesity An Advantage In Hemodialysis Patients

Despite significant improvements in dialysis treatments, currently over 20% of the 350,000 maintenance hemodialysis (MHD) patients in the United States die each year. A study published in Hemodialysis International finds that this high mortality rate may be attributed to malnutrition.

MHD patients experience what has been termed the "obesity paradox," wherein obesity is associated with increased chance of survival. "A larger body fat mass as seen in obesity probably represents protective reserves that may mitigate the adverse effects of malnutrition in patients," according to Kamyar Kalantar-Zadeh M.D., author of the study.

MHD patients tend to have a high degree of protein-energy malnutrition and inflammation. The combination of these two conditions, termed Kidney Disease Wasting (KDW), leads to increased risk of death. Conversely, it has been shown that an increase in protein intake yields the greatest survival in patients.

The study suggests that improved diet as well as appetite-stimulating agents may be a way to improve nutrition and, consequently, outcome in MHD patients. Understanding the factors that lead to KDW will be the key to improving survival in MHD patients, as well as in the 20 to 40 million Americans who exhibit similar risk-factor paradoxes such as those with chronic heart failure, AIDS, rheumatoid arthritis and malignancy.........

Posted by: Beverly      Permalink         Source

November 15, 2006, 4:58 AM CT

New Angioplasty Procedure More Effective

Over the last several years angioplasty has exceeded coronary bypass surgery as the preferred way to treat coronary artery disease. The stents (narrow tubes inserted into the artery to facilitate blood flow) commonly used in the procedure are less invasive than open-heart surgery and offer greater convenience to the patient and the ability to perform more complex procedures.

However, they are also more likely to lead to restenosis, a recurrence of artery clogging. According to findings in Journal of Cardiac Surgery, newly developed drug-eluting stents (DES) that release a drug directly to the injured blood vessels are less likely to lead to restenosis than traditionally used bare-metal stents (BMS). Controversy exists regarding the role of stents in the treatment of complex multi-vessel coronary artery disease and the potential for late complications.

While studies have found that DES procedures limit restenosis and, consequently, improve quality of life, the associated medical care would cost patients an average of $900 more during the two-year period following the procedure than with BMS. This cost is expected to decrease within five years, however, rendering DES cost-neutral or cost-saving when compared to BMS.

Despite the positive outcomes associated with DES, the procedure should not be viewed as a replacement for surgery. DES have proven to be safe and effective over the short and medium term, but long term effects have not been sufficiently explored.........

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November 15, 2006, 4:44 AM CT

Nanoparticles To Target Brain Cancer

Tiny particles one-billionth of a meter in size can be loaded with high concentrations of drugs designed to kill brain cancer. What's more, these nanoparticles can be used to image and track tumors as well as destroy them, as per scientists at the University of Michigan Comprehensive Cancer Center.

Scientists incorporated a drug called Photofrin along with iron oxide into nanoparticles that would target malignant brain tumors. Photofrin is a type of photodynamic treatment, in which the drug is drawn through the blood stream to tumor cells; a special type of laser light activates the drug to attack the tumor. Iron oxide is a contrast agent used to enhance magnetic resonance imaging, or MRI.

"Photofrin goes into tumor blood vessels and collapses the vasculature, which then starves the tumor of the blood flow needed to survive. The problem with free photofrin treatment is that it can cause damage to healthy tissue. In our study, the nanoparticle becomes a vehicle to deliver the drug directly to the tumor," says study author Brian Ross, Ph.D., professor of radiology at the U-M Medical School and co-director of Molecular Imaging at the U-M Comprehensive Cancer Center.

Photofrin has been used to treat several types of cancer, including esophageal, bladder and skin cancers. It works by traveling through blood vessels until it reaches the vessels supplying blood to the tumor. When activated by light, the Photofrin collapses these blood vessels, starving the tumor of the blood it needs to survive.........

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November 14, 2006, 5:07 AM CT

SimCity for real

Social policy makers and town planners will soon be able to play 'SimCity' for real using grid computing and e-Science techniques to test the consequences of their policies on a real, but anonymous, model of the UK population. Dr Mark Birkin and his colleagues, who are in the process of developing the model at the University of Leeds, will be demonstrating its potential at the UK e-Science stand at SC06, the world's largest supercomputing conference in Florida, this week.

They are using data recorded at the 2001 census to build a model of the whole UK population, but with personal details omitted so no individual or household can be identified. Their project, Modelling and Simulation for e-Social Science is funded by the UK Economic and Social Research Council National Centre for e-Social Science. "We're building a core model which represents the whole of the UK at the level of (synthetic) individuals and households with a number of attributes and behaviours," says Dr Birkin.

Data about these attributes - such as car ownership, house prices and use of health, education, transport and leisure facilities - are held by different agencies in different locations and often in different formats. "Historically, people have assembled data on a single PC or workstation. E-Science provides exciting opportunities to access multiple databases from remote, virtual locations, making it possible to develop highly generic simulation models which are easy to update," says Dr Birkin.........

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November 14, 2006, 5:04 AM CT

Ice-breaker Polarstern to explore uncharted seafloor

Huge areas of sea floor (around 3,250 km²) have been freed up by the collapse 4 years ago of the Larsen B platform along the Antarctic Peninsula - leaving a blank spot on Antarctic maps. Polarstern, the research flagship of the Alfred Wegener Institute for Polar and Marine Research, will shortly conduct there the first major biological research, studying living communities, from microbes to whales, including bottom fish and squids.

THE ITINERARY

DEPARTURE - NOVEMBER 23, 2006: CAPE TOWN.

The Polarstern leaves Cape Town, South Africa, heading towards the Weddell Sea.

DECEMBER 4/5 TO DECEMBER 14, 2006: NEUMAYER STATION.

The Polarstern stops in the Atka Bay in order to supply the German Neumayer Research Station.

DECEMBER 14 TO JANUARY 26, 2006: ANTARCTIC PENINSULA.

The first investigations, on living resources (CCAMLR), take place on the western side of the Antarctic Peninsula, around the South Shetland Islands (3). The subsequent ecological work (CAML) is located around the Larsen A/B area. If the sea ice is not penetrable, an alternative area around Joinville Island will be used instead (4).

ARRIVAL - JANUARY 30, 2007: PUNTA ARENAS.

The Polarstern will end its expedition in Punta Arenas, Chile on January 30, 2007 (5).........

Posted by: Ethen      Permalink         Source

November 13, 2006, 9:08 PM CT

Where Chimp And Human Brains Diverge

Six million years ago, chimpanzees and humans diverged from a common ancestor and evolved into unique species. Now UCLA researchers have identified a new way to pinpoint the genes that separate us from our closest living relative and make us uniquely human. The Proceedings of the National Academy of Sciences reports the study in its Nov. 13 online edition.

"We share more than 95 percent of our genetic blueprint with chimps," explained Dr. Daniel Geschwind, principal investigator and Gordon and Virginia MacDonald Distinguished Professor of Human Genetics at the David Geffen School of Medicine. "What sets us apart from chimps are our brains: homo sapiens means 'the knowing man.'.

"During evolution, changes in some genes altered how the human brain functions," he added. "Our research has identified an entirely new way to identify those genes in the small portion of our DNA that differs from the chimpanzee's".

By evaluating the correlated activity of thousands of genes, the UCLA team identified not just individual genes, but entire networks of interconnected genes whose expression patterns within the brains of humans varied from those in the chimpanzee.

"Genes don't operate in isolation each functions within a system of related genes," said first author Michael Oldham, UCLA genetics researcher. "If we examined each gene individually, it would be similar to reading every fifth word in a paragraph you don't get to see how each word relates to the other. So instead we used a systems biology approach to study each gene within its context".........

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November 13, 2006, 9:03 PM CT

Phosphorus Another Culprit

Nitrogen is flowing down the Mississippi River and into the Gulf of Mexico faster than it can be consumed by floating microscopic plants called phytoplankton, increasing the size of the "dead zone" off the Louisiana coast. The findings, based on analysis of data gathered in 2001, are published online this week in the journal Environmental Science and Technology.

Because of the increased nitrogen levels, phytoplankton blooms are growing, and the Gulf's hypoxia zone -- an area lacking enough oxygen to sustain most life -- is getting bigger.

"In a pristine system, nutrients would flow down the river and into the Gulf, and there would be limited phytoplankton growth and no hypoxia," said James Ammerman, co-author of the paper and a biological oceanographer at Rutgers. "Heavy use of fertilizers containing nitrogen and phosphorus in the agriculture of the Mississippi Valley has thrown the system out of balance".

According to Ammerman, phytoplankton need both nitrogen and phosphorus to grow. Because they require a 16-to-1 ratio of nitrogen to phosphorus, phytoplankton usually run out of nitrogen first; most coastal surface waters have ratios lower than 16-to-1.

"There is now so much nitrogen in the Gulf that even though phytoplankton consume it faster than they consume phosphorus, they can't get rid of it fast enough, and it's the phosphorus, instead of nitrogen, that runs out first and becomes the limiting nutrient," Ammerman said.........

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November 13, 2006, 8:06 AM CT

Detecting Heart Trouble Early

Working with dogs and using the latest in imaging software and machinery, also known as a 64-slice CT scanner, Johns Hopkins heart specialists have developed a fast and accurate means of tracking blood that has been slowed down by narrowing of the coronary arteries. Researchers say it took them less than half the time of exercise stress tests and echocardiograms currently used to find early warning of vessels more likely to become blocked and cause heart attack.

The Hopkins team will present their initial findings Nov. 12 at the American Heart Association's annual Scientific Sessions in Chicago. Already, the Hopkins technique, in which patients are given a drug to stress their heart during the scan, is undergoing clinical testing. Results among 60 patients are expected within a year.

If the human trials prove equally successful, senior investigator Albert C. Lardo, Ph.D., an assistant professor at The Johns Hopkins University of School of Medicine and its Heart Institute, says the new scanner "could dramatically change the way we diagnose coronary disease in patients with initial symptoms of chest pain, by providing a safe, non-invasive and fast method to detect blood-flow problems in heart tissue.

"Because it takes less than 15 minutes to perform and does not require patients to be stabilized ahead of scanning, it could replace most other more time-consuming tests that help find blockages, including not only exercise stress testing and echocardiograms, but also positron electron tomography (PET) imaging or magnetic resonance imaging," he says.........

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November 10, 2006, 4:55 AM CT

Eye Of A Monster Storm On Saturn

NASA's Cassini spacecraft has seen something never before seen on another planet -- a hurricane-like storm at Saturn's south pole with a well-developed eye, ringed by towering clouds.

The "hurricane" spans a dark area inside a thick, brighter ring of clouds. It is approximately 8,000 kilometers (5,000 miles) across, or two thirds the diameter of Earth.

"It looks like a hurricane, but it doesn't behave like a hurricane," said Dr. Andrew Ingersoll, a member of Cassini's imaging team at the California Institute of Technology, Pasadena. "Whatever it is, we're going to focus on the eye of this storm and find out why it's there".

A movie taken by Cassini's camera over a three-hour period reveals winds around Saturn's south pole blowing clockwise at 550 kilometers (350 miles) per hour. The camera also saw the shadow cast by a ring of towering clouds surrounding the pole, and two spiral arms of clouds extending from the central ring. These ring clouds, 30 to 75 kilometers (20 to 45 miles) above those in the center of the storm, are two to five times taller than the clouds of thunderstorms and hurricanes on Earth.

Eye-wall clouds are a distinguishing feature of hurricanes on Earth. They form where moist air flows inward across the ocean's surface, rising vertically and releasing a heavy rain around an interior circle of descending air that is the eye of the storm itself. Though it is uncertain whether such moist convection is driving Saturn's storm, the dark "eye" at the pole, the eye-wall clouds and the spiral arms together indicate a hurricane-like system.........

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