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SCIENCE UPDATE
Stem cell source found in human brain
Researchers have discovered a cell-producing region in the human brain that resembles one found in rodent brains — but with a basic difference that has profound implications for research aimed at repairing damage by growing new cells.
In rodents, a region called the subventricular zone (SVZ), roughly in the middle of the brain, constantly produces cells that migrate to the olfactory bulb, which governs smell. The rodent SVZ produces stem cells, which have the ability to be transformed into many different kinds of cells. Most end up as nerve cells.
Until now, no such cell-producing region has been identified in the human brain. But researchers at the University of California at San Francisco, studying tissue samples taken from patients undergoing brain surgery and post-mortem brain donors, report in the Feb 19 issue of the journal Nature that they have found one.
It is a ribbon of astrocytes, which make up the great majority of brain cells, the report says. It is also something that has not been seen in any animal brain and that has its own unusual characteristics.
New cholesterol drugs
Researchers claim they had figured out how to prevent the body from absorbing cholesterol in the gut and said it may lead to the development of new cholesterol-lowering drugs.
Their experiment, published in the journal Science, also may explain how the anti-cholesterol drug Zetia works. The drug, made by Schering-Plough, had been known to lower “bad” cholesterol but no one understood quite how it worked. It seems to affect a protein called NPC1L1, Scott Altman, Michael Graziano and colleagues at Schering’s research labs reported.
Mice genetically engineered to lack this protein absorbed 70 percent less cholesterol from their diets than did normal mice, they found. When these genetically engineered mice were given Zetia, known chemically as ezetimibe, they did not absorb any less cholesterol, which suggests the drug may work by blocking NPC1L1.
The researchers said additional tests on their mice suggest that NPC1L1 does not work on its own, but they will continue to try to find out how the process works.
Gluten and schizophrenia
Schizophrenia could be linked to an allergy to gluten, a protein found in wheat and other grains, scientists said.
Gluten intolerance, known as coeliac disease, can erupt at any age but mostly affects people between the ages of 30 and 45, often causing weight loss, diarrhea and fatigue.
“A history of coeliac disease is a risk factor for schizophrenia,” the researchers wrote in an article for the British Medical Journal.
The scientists recommended a gluten-free diet to treat coeliac disease, and said some clinical trials had shown that cutting out cereals also alleviated symptoms of schizophrenia. The study, a collaboration between Johns Hopkins medical institutions in the United States and Denmark’s Aarhus Universities and Aarhus Psychiatric Hospital, tested 7,997 schizophrenic patients in a Danish psychiatric unit.
Kidney cancer vaccine
An experimental vaccine against kidney cancer has shown promising results in reducing the recurrence of the disease, according to German researchers.
In a trial of 379 kidney cancer patients, scientists showed that the vaccine made by German biotechnology company LipoNova improved disease-free survival of patients.
“For the first time ever it has been shown that additional therapy after surgery for kidney tumors is effective,” said Dr Christian Doehn of the University of Lubeck Medical School in Germany.
Five-year survival rates were 77 percent for patients who were given six injections of the customized vaccine, compared with 68 percent in patients who did not receive the vaccine.
Doehn and his colleagues, who reported their findings in The Lancet medical journal, said the results were even better for patients with large tumors who have a higher risk of recurring cancer.
The patients were given six injections of the customized vaccine, made using material from their tumor, over four weeks. Twelve people reported side effects. The scientists said the vaccine should be considered for patients whose cancer has not spread beyond the kidney and who have had surgery to remove a tumor that was larger than 2.5cm.
Rovers explore salty water
Nasa’s Opportunity rover sent back new images from Mars showing that small spheres previously found on the surface also exist below, in a trench the rover dug. Hints of salty water were also found in the trench, but much more analysis is needed to learn the true composition.
In a press conference, officials said the soil at both locations could contain small amounts of water mixed with salt in a brine that can exist in liquid form at very low temperatures.
The scientists stressed that only miniscule amounts of water would be needed to create the brine.Water is the main thing scientists are searching for at Mars, because all life as we know it requires liquid water.
Black hole destroys star
Observations from three space-based X-ray telescopes over about a decade provide the first solid evidence of a star being torn apart and partly swallowed by a black hole. Astronomers already have plenty of evidence for black holes consuming gas that swirls inward and is superheated, generating radiation in many wavelengths from radio to visible light and X-rays. They have long assumed that whole stars could be torn apart by the gravitational tug of a black hole, but proof has been elusive. The new evidence confirms other suggestive observations that such dramatic events do occur.
In a close interaction with another star, the ill-fated star was gravitationally booted onto a fateful trajectory near the center of a distant galaxy, astronomers said today. As it approached a supermassive black hole that packs as much mass as 100 million suns, the star was stretched by tidal forces similar to those that raise the oceans on Earth. “Stars can survive being stretched a small amount,” said study leader Stefanie Komossa, a postdoctoral researcher at the Max Planck Institute for Extraterrestrial Physics in Germany. “But this star was stretched beyond its breaking point.” The supermassive black hole anchors a galaxy called RX J1242-11. It is about 700 million light-years away. The star was about the size of our Sun and was ripped to shreds over hours.
New object found
Astronomers said they have found a frozen object 4.4 billion miles from Earth that appears to be more than half the size of Pluto and larger than the planet’s moon.
Preliminary observations say the frozen celestial body is 10 per cent larger than Quaoar, an 800-mile-diameter object found in 2002.
“Right now it looks like it could be bigger than Quaoar, which would put it bigger than anything since Pluto,” said Mike Brown, a California Institute of Technology astronomer. Brown and colleagues Chad Trujillo, of the Gemini Observatory in Hawaii, and David Rabinowitz, of Yale University, discovered the object with a telescope at the Palomar Observatory outside San Diego.
The object, dubbed 2004DW, lies at the outer fringes of the Kuiper Belt, a swarm of frozen rock and ice beyond the orbit of Neptune. The newfound frozen world is the 15th object larger than 300 miles in diameter found in the region. Preliminary measurements suggest the object follows an elliptical orbit that takes it as close as 2.7 billion miles to the sun and as far out as 4.7 billion miles, Brown said. It takes the object an estimated 252 years to orbit the sun. — Sci-tech World Report
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