NEWS OF THE WEEK REGULATION
FDA BANS VETERINARY DRUG Baytril antibiotic, used in poultry, causes resistant bacteria to emerge HE FOOD & DRUG ADMIN-
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istration has banned the use of the antibiotic Baytril in poultry because it causes resistance to emerge in Campy lobacter bacteria. Campylobacter in poultry is one of the most common caus es of severe bacteri al food poisoning in humans. Baytril, a fluoro quinolone, is the first veterinary drug to be banned because it
leads to the emergence of resist ant bacteria. It is chemically sim ilar to the antibiotic Cipro, which is widely prescribed to treat foodborne illness in people. Use of Baytril in poultry FDA says, re duces the effectiveness of Cipro in treating Campylobacter in hu mans. Baytril's manufacturer, Bayer, has 60 days to appeal FDA's decision. The Baytril given to poultry is used for therapeutic, not growth promotion, purposes. W h e n a respiratory infection shows up in a few birds, Baytril is commonly given to the entire flock.
N A N O T E C H N O L O G Y
COOKING' CANCER Carbon nanotubes and near-infrared radiation kill cancer cells by heating
c
ARBON NANOTUBES
CAN
be used to kill cancer cells. Researchers at Stanford
TOO HOT Kam(left) and Dai "cook" cancer cells using nanotubes and near-IR radiation. 16
C&EN
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8,
University led by chemistry pro fessor Hongjie Dai and graduate student Nadine Wong Shi Kam have shown that carbon nano 2005
tubes can be selectively directed to cancer cells to kill them with near-infrared radiation (Proc. Natl. Acad. Sci. USA, published online, www.pnas.org/cgi/doi/ 10.1073/pnas.0502680102). The nanotubes find their way to the cancer cells via folate at tached to the nanotube surfaces. These cancer cells' surfaces have a large number of folate recep tors, a marker for some kinds of cancer. T h e cells take up the nanotubes through receptormediated endocytosis. When near-IR light is applied to the nanotube-penetrated cells, the nanotubes heat up as they ab sorb the radiation, killing the cells, Dai says. Because biological systems are transparent to near-
"This is a precedent-setting decision," says Margaret Mellon, director of the Food & Envi ronment Program at the Union of Concerned Scientists. "My ex pectation is that FDA will fol low up by taking steps to cancel some of the nontherapeutic us es of human-use antibiotics in agriculture." "Cipro is an essential antibiot ic, and we cannot allow its effec tiveness to be compromised by squandering it on poultry," says David Wallinga, a senior scientist and director of the Antibiotic Re sistance Project at the Institute for Agriculture & Trade Policy "The loss of this product leaves poultry producers without an im portant tool to treat sick poultry, and it will reduce animal health and welfare while increasing ani mal death and suffering," says a statement from the Animal Health Institute, which repre sents the manufacturers of animal health products. —BETTE HILEMAN
IR radiation, only cells contain ing the nanotubes are harmed. "The authors have shown a very elegant and innovative way to kill cancer cells," says Maurizio Prato, a professor in the depart ment of pharmaceutical science at the University of Trieste, in Italy, who also studies carbon nanotubes for therapeutic uses. The method does have po tential challenges, though. Un der culture conditions, the cells eventually disintegrate, and the nanotubes aggregate, "giving rise to insoluble material," Prato says. "For biological uses, covalently functionalized and fully soluble carbon nanotubes would proba bly be more tolerated." Any therapeutic application is still a long way off. So far, Dai has tested the nanotubes only in cell culture. He is now collaborating with researchers at Stanford Medical School to do animal test ing. They hope to learn the fate of the nanotubes after the cells d i e . —CELIA HENRY
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