2008年1月31日星期四
Juniper Makes The Switch
2008年1月27日星期日
Microsoft: We're Open (Source) For Business
Microsoft Breaks Earnings Records, Again
VIA Launches Low-Power, 64-Bit Chip
2008年1月26日星期六
Technical Analysis: Stocks Snap Back
IBM Adds AptSoft to SOA Portfolio
IBM's Web 2.0 Platform Mashes Up Business, Social
2008年1月25日星期五
Hurt an Organ, Help a Disease?
By Jennifer Couzin
ScienceNOW Daily News
24 January 2008
In people with diabetes, insulin-producing cells in the pancreas, called beta cells, have been destroyed or may behave sluggishly. This leaves the body unable to regulate its blood sugar. Coaxing the pancreas to make new beta cells is one of the great goals of diabetes research. Scientists debated for years whether the pancreas holds stem cells that could replenish beta cells, but in 2004, biologists led by Douglas Melton at Harvard looked for these stem cells in the pancreas of mice and failed to find them. His team instead reported that existing beta cells could multiply to form new ones (ScienceNOW, 5 May 2004).
Harry Heimberg of Vrije Universiteit in Brussels, Belgium, wondered whether there were additional sources of new beta cells. Earlier experiments in rats had found that clamping a pancreatic duct and stopping digestive enzymes from entering the small intestine roughly doubles the mass of beta cells in the pancreas. But which cells in the pancreas were generating these extra beta cells?
Heimberg and his colleagues caused the same severe injury in mice. Then they searched for pancreatic cells that might somehow turn into beta cells. To do this, they focused on the genetic marker neurogenin 3, which appears in cells slated to become beta cells when they're just beginning to develop in an embryo. Within 3 days of injury, the scientists found cells with this gene. Furthermore, preventing the gene's expression reduced beta-cell proliferation, the group reports in the 25 January issue of Cell. When these neurogenin 3 cells were taken from an adult mouse and injected into a pancreas removed from a mouse embryo, they developed into beta cells and produced insulin, suggesting that the cells were developing into new beta cells in the injured animal. Further studies found that the neurogenin 3 cells weren't making insulin before the injury. That means beta cells hadn't bolstered the beta-cell supply by themselves, as Melton had shown was possible in normal animals.
Many questions remain. Where do the cells come from, for example? The cells sit along the ducts of the organ, so they could originate as mature ductal cells that revert to an embryonic state after the injury and then become beta cells. Or, says Heimberg, they could be progenitor cells, which unlike stem cells cannot self-replenish. Other big questions are whether the neurogenin 3 cells can be coaxed to come forward in the normal human pancreas without damaging the organ, and whether they can be turned into insulin producers.
Melton suspects the cells began as mature pancreatic cells, likely from the ducts, as they don't have many characteristics of stem cells. The study, he says, shows that there's another mechanism to keep beta cells coming, which might offer a new cell source to consider in the hunt for ways to replenish beta cells.
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Scientists Synthesize a Genome From Scratch
By Elizabeth Pennisi
ScienceNOW Daily News
24 January 2008
Ever since his group decoded the genome of Mycoplasma genitalium, a parasitic bacterium that lives in the human urogenital tract, sequencing maverick J. Craig Venter has wanted to remake the bug's genome in the lab. At just under 600,000 bases, M. genitalium sports the smallest known genome for a free-living organism, and Venter hoped that an artificial genome could be modified to turn the bacterium into a living chemical-manufacturing plant.
Last year, Venter and his colleagues developed a technique for replacing M. genitalium's genome with another natural genome from a different species (Science, 3 August 2007, p. 632). But synthesizing the M. genitalium genome from the ground up proved challenging, in part because long strands of DNA are quite fragile.
Japanese researchers have built a large genome from two existing bacterial chromosomes. But Venter, Hamilton Smith, and their colleagues at the J. Craig Venter Institute in Rockville, Maryland, started with short pieces of DNA that a company had manufactured base by base. About 6000 bases long, these pieces represented overlapping bits of the microbe's only chromosome. Some of the pieces also contained "watermarks": a few extra or different bases here and there that distinguish an artificial chromosome from a natural one.
To link the pieces, Smith and Venter's team used enzymes that allowed them to join longer and longer DNA strands until they had just four, each representing one-quarter of the genome. Finally, the team inserted these quarters into yeast, which copied and combined them into a complete chromosome. The researchers sequenced their newly constructed genome and, except for the watermarks, it matched M. genitalium's exactly. The work is "a technical tour de force" and a "monumental effort," says yeast biologist Jef Boeke of Johns Hopkins University School of Medicine in Baltimore, Maryland. However, to be sure this genome works as it should, the researchers must still put it into a DNA-less M. genitalium, notes Eckard Wimmer, a molecular virologist at Stony Brook University in New York state: "Proof is biological function, and that's missing in this paper."
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2008年1月24日星期四
Internet Explorer 8 Tries New Compatibility Solution
2008年1月23日星期三
Health Drives iMedix
Publishing Company Settles Software Suit With SIIA
Dell Back to Strong Growth
2008年1月20日星期日
IBM Skips Past 4Q Estimates
ATI Write-Down Costs AMD $1.68 Billion
2008年1月18日星期五
New Office For Mac Finally Sees Daylight
2008年1月17日星期四
Sun to Nab MySQL For $1 Billion
Stocks Follow Intel Lower
2008年1月16日星期三
A Particularly Nasty Week For Malware
Oracle Digs Deep to Snare BEA
2008年1月15日星期二
Transformers: Scanner to Communications Hub
2008年1月14日星期一
High Prices Just Feel Good
By Yudhijit Bhattacharjee
ScienceNOW Daily News
14 January 2008
Previous studies have shown that savvy marketing can change how we feel about a product. For example, branding a perfume as classy somehow makes it smell more appealing. Curious about how such marketing affects the brain, researchers led by Antonio Rangel, an economist at the California Institute of Technology in Pasadena, and Baba Shiv, a marketing professor at Stanford University in Palo Alto, California, conducted functional magnetic resonance imaging scans of 20 volunteers as they sipped what they thought were five kinds of Cabernet Sauvignon. In reality, the researchers gave the subjects three wines with retail prices of $5, $35, and $90. The cheapest wine was served twice but disguised in one of the servings as a different label costing $45. The $90 vintage also made two appearances, once with its real price and once with a price of $10.
The faux marketing worked. Volunteers reported liking the cheap wine better when it had a higher price attached to it and the expensive wine less when it was marked cheaper. What's more, when sipping wines tagged with a higher price, the volunteers showed greater activity in their medial orbitofrontal cortex--a part of the brain believed to be responsible for judging pleasantness of experiences--than when they sipped the cheaply marked wines. The findings, published online this week in the Proceedings of the National Academy of Sciences, suggest that marketing actions such as pricing can have a placebo effect on the brain in the same way that dummy pills have been shown to relieve pain.
"We think that the effect is driven by expectations," says Rangel. "Subjects believe that more expensive wines are likely to taste better. These expectations end up influencing their actual experience." The findings raise questions about the ability of consumers to make sound choices amid the dizzying whirl of marketing campaigns that characterize today's economy, he says.
Rajneesh Suri, a marketing professor at Drexel University in Philadelphia, Pennsylvania, calls the study an example of how consumers use pricing information as a proxy for quality. "Price can serve as a quality cue that guides enjoyment of a product, especially when one does not know enough about it," he says.
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