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How to Put Bull's-Eyes on Cancer Cells


To cancer patients, nothing is scarier than metastasis--the spread of malignant cells, often signaling that the cancer can't be cured. But a strategy conceived by Philip S. Low, a Purdue University chemist, and Endocyte of West Lafayette, Ind., has cured more than 200 mice with advanced metastatic lung cancer. The approach will be tested in people this fall.

The trick is to tag cancer cells, wherever they are, so they can be spotted by the immune system or targeted by drugs. For tags, Low and the Endocyte team use a dye called fluorescein. Injected into a mouse, it prompts the animal to produce antibodies that can recognize the dye. Next, the team attaches fluorescein molecules to folate, a form of vitamin B that certain types of cancer cells--lung, ovarian, and kidney tumors, for example--capture and display on their surfaces.

When the same mouse is injected with the combined molecules, the tumor cells that capture the folate also end up wearing the immunogenic dye. That means the immune system can spot and destroy the tumors. With forest fires raging in Colorado, California, and Arizona, scenes of helicopters dumping big, 150-gallon buckets of water on blazing trees have become a staple of TV news. A team of aerospace engineers led by Ralph E. Pope Jr. thinks there's a better way to fight fires: artificial thunder clouds in the form of gigantic airships, or dirigibles.

Pope's startup, Wetzone Engineering in Huntington Beach, Calif., was formed by a group of airship engineers who left Lockheed Martin Corp. and Boeing Co. They envision a 1,000-foot-long airship that carries nearly a quarter-million gallons of water and discharges it through big showerhead nozzles at up to 60,000 gallons an hour. The ship could provide a steady downpour for four hours--longer, if copters replenished its reservoir.

Pope figures the first model "will cost a godawful amount, maybe $80 million." But he hopes to attract investors because both World SkyCat in Oxford, England, and CargoLifter in Brand, Germany, are gearing up to build a new generation of mammoth airships designed to haul loads weighing up to 1,000 tons. SkyCat expects to launch its first dirigible later this year, while CargoLifter's launch is not likely before 2005. SkyCat and Wetzone are collaborating on a family of airships, at varying price points, for different terrains and various sizes of forest fires. Recent scientific studies continue to warn that humanity's demands on natural resources are reaching, or have already hit, unsustainable levels. Perhaps the most dire analysis comes from an international group of scholars led by Mathis Wackernagel, a researcher at the Redefining Progress think tank in Oakland, Calif.

Published on the Web site of the Proceedings of the National Academy of Sciences, the study measured mankind's "ecological footprint" over the past 40 years. The researchers calculated the globe's total resources for growing crops, raising feedstock, harvesting timber, burning fuels, and fishing. Their preliminary findings: Demand on the biosphere now outstrips what it can supply. Humanity was using 70% of the earth's regenerative capacity in 1961, reached parity in the mid-1970s, and demand has exceeded the biosphere's ability to replenish its resources by at least 25% since 1999.

Meanwhile, environmental scientist Richard Gill at Washington State University is focusing on the ability of soil to absorb excess carbon dioxide. As reported in the June 6 issue of Nature, his work at an Agriculture Dept. field lab near Temple, Tex., isn't encouraging. Greenhouse gas levels haven't been rising as fast as CO2 emissions because the soil has been soaking up the CO2. However, the soil seems to be approaching saturation, which would mean that global warming may soon begin to accelerate. Cruise missiles fly at a relatively leisurely speed of about 550 mph. That's slow enough to be shot down by advanced air-defense systems. But a new breed of hypersonic cruise missile is meant to zip past any foreseeable defense and smack transient targets almost instantly from hundreds of miles away.

The engine for these futuristic speed demons was developed by Johns Hopkins University's Applied Physics Laboratory (APL) in Laurel, Md. It was ground-tested by NASA on May 30 and performed flawlessly under simulated conditions at 90,000 feet and a speed of Mach 6.5. That's 6.5 times the speed of sound, or roughly 4,250 mph. Thus, even a target at the missile's maximum range of 700 miles can be reached in only 10 minutes.

The new powerplant is a so-called ramjet. Unlike ordinary jet engines, ramjets don't have a turbofan to suck in air. Instead, they rely on hypersonic speed to force air into special intake scoops. A rocket would launch the missile, and the ramjet would kick in at Mach 3.5. The new engine is next slated to begin a series of flight tests that will run until 2005. APL's two industrial partners--Boeing and GenCorp's Aerojet unit, which built the engine--are handling this phase of the HyFly program.


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