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Biocomputers That Don't Need Human Help


Think of a DNA molecule as software. Think of enzymes that work on DNA as little bits of hardware. Put lots of DNA and enzymes in a test tube, and you have 1 trillion primitive computers, all working in parallel in a single drop of water at a billion operations per second with 99.8% accuracy.

In the Nov. 22 issue of Nature, Israeli scientists at the Weizmann Institute of Science and Technion Israel Institute of Technology say they have built such a biological computing machine. It takes bits of DNA as inputs and manipulates them to produce outputs. The scientists theorize that it can execute 765 different programs--although nothing as complex as, say, a spellchecker. For example, one program the team got to work looks at a string of zeroes and ones and determines if it contains an even number of ones.

DNA computing has been a hot research area since the mid-1990s. But Weizmann project leader Ehud Shapiro says his team has made an important advance in setting up the DNA "software" so that the computer works without human intervention. He sees the device as a step toward more sophisticated nanocomputers that could reside in the body, detect chemical abnormalities, then synthesize and release drugs to fix them. Angioplasty is a popular procedure for clearing clogged arteries and veins, but it can also be risky. When the balloon and catheter pass through the artery, they can dislodge bits of clotted blood and tissue, called emboli, that may enter the blood and clog another artery. To solve this problem, Johnson & Johnson (JNJ) subsidiary Cordis has developed a tiny trap for the emboli called AngioGuard.

The device consists of a porous metal basket with a polyurethane filter, which is threaded past the blockage by way of a catheter. When the catheter is pulled back, the device opens like an umbrella, trapping debris but letting blood flow through. After angioplasty is completed, the AngioGuard is closed and removed. A team of German and U.S. doctors reported in the journal Circulation that they've conducted the first tests of AngioGuard in 25 patients. The team said the device collected emboli in all the patients, indicating how dangerous it might have been if the debris had entered the blood stream. None of the patients suffered adverse effects during surgery. Last year, more than 2.5 million pounds of beef were recalled in the U.S. because of possible contamination by dangerous bacteria such as E. coli. To help squelch outbreaks of food-related illnesses, scientists at Iowa State University and the Agriculture Dept. have developed imaging technology able to scan beef carcasses and detect the most minute traces of fecal matter, which may harbor harmful pathogens.

eMerge Interactive (EMRG) of Sebastian, Fla., has licensed the technology and built a prototype scanner called VerifEYE for use by meatpackers. The system scans a slab of meat using light of varying wavelengths. An image of the beef is displayed on a monitor, with contaminated areas highlighted by a fluorescent glow. Meatpackers can then trim off those potentially harmful portions of beef. "This is a huge step in the right direction," says James E. Kennedy Jr., director of research microbiology at ABC Research, a food-testing lab that participated in a trial of the system.

Image scanning can also provide liability protection for meatpackers when they are accused of passing along bad beef. Meat scans can be archived and later examined if a product batch is called into question. VerifEYE is scheduled for commercial launch in late 2002. Researchers are working on similar technology for pork and poultry. -- Money may not buy happiness, but it could buy memories. Kristy Nielson, an assistant professor of psychology at Marquette University, reported at a recent neuroscience meeting that she had three groups of people memorize 30 words. The subjects were tested for recall immediately afterward, and all performed about the same. But before they left, the researchers praised one group, did nothing for the second, and gave each person in the third group a dollar. When the subjects returned a week later, those who had been paid did much better at recalling the words than the members of the other two groups. Those who were praised, however, did only slightly better than the group that received no reward at all. "Financial reward produces significantly better results than social reinforcement," Nielson concluded. That's something for employers to keep in mind when considering whether to give raises at annual review time.

-- Further incentive to eat your broccoli: An Agriculture Dept. lab has developed a strain of the vegetable enriched with an anti-cancer agent, selenium, that appears to do a better job of protecting rats from tumors than standard forms of the dietary supplement. Researchers at Roswell Park Cancer Institute in Buffalo said that broccoli seems to store selenium in a unique form that is easy for the body to metabolize. One group of rats injected with cancer cells was given the enriched broccoli--which is not commercially available--while another was given the equivalent amount of selenium in supplements. The rats given broccoli developed far fewer mammary and colon tumors and pre-cancerous lesions than the groups given supplements.


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