UPI NewsTrack Health and Science News

Earth's major rivers have low water levels

BOULDER, Colo., April 22 (UPI) -- A U.S. study shows rivers in some of the world's most populous regions are losing water, with some losses attributed to climate change.

The study by the National Center for Atmospheric Research suggests the reduced stream flow potentially threatens future supplies of food and water.

The scientists, examining stream flow from 1948 to 2004, said they found significant downward changes in about one-third of the world's largest rivers, including the Yellow River in northern China, the Ganges in India, the Niger in West Africa and the Colorado in the southwestern United States.

In contrast, the scientists reported greater stream flow over sparsely populated areas near the Arctic Ocean, where snow and ice are rapidly melting.

"Reduced runoff is increasing the pressure on freshwater resources in much of the world, especially with more demand for water as population increases," said NCAR scientist Aiguo Dai, who led the study. "Freshwater being a vital resource, the downward trends are a great concern."

Although many factors can affect stream flow, the scientists said reduced flows in many cases appear linked with global climate change, which is altering precipitation patterns and increasing evaporation.

The research will appear in the May 15 issue of the American Meteorological Society's Journal of Climate.

Stem cells can help heal diabetic ulcers

BRISTOL, England, April 22 (UPI) -- British medical scientists say they've discovered human fetal stem cells can effectively heal back leg ischemic ulcers in a model of type 1 diabetes.

The University of Bristol researchers said they also found the culture in which the stem cells had been grown mimicked the wound-healing ability of the cells. That, they said, suggests the culture could be used as a "factory" of wound-healing substances or the active ingredients in the culture could be used instead, thereby avoiding the ethical concerns of using human fetal stem cells.

The scientists said diabetic patients with ischemic foot ulcers have the worst outcome of all chronic skin wounds. Ischemia occurs when blood supply is greatly reduced or stopped.

The researchers led by Professor Paolo Madeddu found fetal stem cells accelerate the closure of ischemic diabetic ulcers, while stem cells from blood of adult donors are ineffective.

"This is the first study to demonstrate the healing capacity of local therapy with … stem cells in a model of diabetic ischemic foot ulcer," said Madeddu. "The fetus-derived cells would be difficult to obtain for therapeutic applications. However, the finding that conditioned culture is also effective in stimulating wound healing may have important implications for the cure of the ischemic complications of diabetes."

The study appeared ahead of print in the April 2 online issue of the journal Circulation Research.

Scientists develop self-healing concrete

ANN ARBOR, Mich., April 22 (UPI) -- U.S. scientists say they have developed a concrete material that can heal itself when it cracks with only water and carbon dioxide needed.

University of Michigan researchers said all that is necessary to mend a damaged bridge would be a few drizzly days. They said the self-healing is possible because the concrete material is designed to bend and crack in narrow hairlines, rather than break and split in wide gaps, as does traditional concrete.

Professor Victor Li, who led the research, said self-healed specimens recovered most, if not all, of their original strength after researchers subjected them to a 3 percent tensile strain. That means they stretched the specimens to 3 percent beyond their initial size -- the equivalent of stretching a 100-foot piece an extra three feet -- enough strain to severely deform metal or catastrophically fracture traditional concrete.

"We found, to our happy surprise, that when we load it again after it heals, it behaves just like new, with practically the same stiffness and strength," Li said. "The material can be damaged and still remain safe to load."

The research is available online, ahead of print, in the journal Cement and Concrete Research. Li will also present the research in Chicago during June's International Conference on Self-Healing Materials.

Med imaging possible using smartphones

ST. LOUIS, April 22 (UPI) -- U.S. engineers say they have created a USB-based ultrasound probe technology that enables a smart phone to become a medical imaging device.

The Washington University in St. Louis scientists, led by Associate Professor William Richard and researcher David Zar, said the technology makes commercial USB ultrasound probes compatible with Microsoft Windows mobile-based smartphones. That allows the use of smartphones for imaging kidneys, liver, bladder and eyes, prostate and uterine screenings and biopsies, as well as using vascular probes for imaging veins and arteries for starting IVs and central lines.

"You can carry around a probe and cell phone and image on the fly now," said Richard. "Imagine having these smart phones in ambulances and emergency rooms. On a larger scale, this kind of cell phone is a complete computer that runs Windows."

Zar said the vision is to train people in remote areas of the developing world on the basics of gathering data with the phones and sending the data to a centralized unit perhaps half a world away where specialists can analyze the images and make a diagnosis.

Zar presented the technology last week in Washington during the 2009 meeting of the World Health Care Congress.