sealPurdue Science Tips

October 1994

New sources of Taxol offer promise for cancer patients

A Purdue University researcher has discovered Taxol and 20 similar substances in the needles of a common evergreen shrub, providing a possible new source for the anti-cancer drug and possible new starting materials for chemical synthesis of Taxol.

Because these agents come from the needles of the plant, they may provide a renewable, cheaper source of Taxol, says Ching-Jer Chang, professor of medicinal chemistry and pharmacognosy who isolated the compounds.

His research group also is working with Graham Cooks, professor of chemistry, to develop a new method for the detection of Taxol at the picogram level, roughly equivalent to detecting one drop of liquid in five gallons.

Taxol comes from the bark of the Pacific yew tree, Taxus brevifolia , which grows in forests in the western United States and Canada. Approved by the FDA for treatment of ovarian and breast cancer, it kills cancer cells by preventing cell division.

Scientists have been seeking new and different sources for the supply of Taxol because trees must be killed to harvest the bark and the process required to obtain it is time-consuming, low-yielding and expensive. The new substances, derived from a common ornamental plant in the yew family called Taxus media Hicksii (HICK-see-i), show a high level of anti-tumor activity in cell culture, Chang says. He presented details of the new compounds in August at the annual meeting of the American Chemical Society. CONTACT: Ching-Jer Chang, (765) 494-1373.

Research results cook up new information on nuclear matter

A watched pot may not boil, but nuclear matter apparently does. Purdue physicists have kept a very close watch on protons and neutrons, which make up nuclear material, to determine that they can absorb sufficient energy to pass into a gaseous phase, just as water can absorb enough heat to boil and turn into steam. Future experiments will explore the properties of nuclear matter at higher temperatures and greater densities in the hopes of discovering yet a new phase of nuclear matter in which protons and neutrons have "melted" into their constituent quarks and gluons. The research began with the knowledge that the distinction between liquid and gas phases disappears at a certain temperature and pressure, called the "critical point." The Purdue scientists were able for the first time to measure nuclear matter's "critical exponents," which mathematically describe the behavior of a system near its critical point. This measurement allowed them to determine that nuclear matter belongs to the same "universality class" as fluids and simple magnetic systems, which all have the same critical exponents. The High Energy Nuclear Physics Group at Purdue, comprised of researchers from chemistry and physics, performed the experiment at the Lawrence Berkeley Laboratory at the University of California. Collisions between large nuclei (gold) and light nuclei (carbon) produced nuclear fragments from which the scientists were able to deduce the behavior of the nuclear matter at its critical point. This process is analogous to deducing the properties of water by studying a droplet of only 200 molecules. The findings were published in the Sept. 19 issue of Physical Review Letters. CONTACT: Andrew S. Hirsch, professor of physics, (765) 494-5192.

Theoretical physicist -- 'Always the underdog in a contest with nature'

Some of his critics in the world of physics called him "Crazy Al" because of his controversial theories stemming from his discovery of dynamic nuclear polarization 41 years ago. Now those theories of Purdue's Albert W. Overhauser are scientific law and have translated into practical, daily lifesaving use in hospitals. In September Overhauser was named one of eight recipients of the National Medal of Science, the country's highest scientific honor, which he will receive in Washington, D.C. Oct. 25. Overhauser was recognized for a lifetime of contributions to science and the technological impact of his ideas, in fields ranging from condensed matter physics to structural biology to medicine.

Overhauser's personal story is as interesting as his science -- his brilliant ideas were not always accepted at first, even by the so-called "experts" in his field. Overhauser attributes this to "the politics of science," where, according to him, people are so entrenched in their own beliefs they refuse to accept new ideas, even in the face of overwhelming evidence.

He's a humorous man with many stories, from the high-school science teacher who influenced Overhauser to pursue physics rather than the saxophone, to the afternoon as a 26-year-old postgraduate when he was "playing around" in the lab and discovered the Overhauser effect, a technique now used pervasively in magnetic resonance imaging. "I knew all along I was right," Overhauser said of his theory. "The requirement of precision places a theorist at risk. A single experiment can prove him wrong. He is always the underdog in a contest with nature." CONTACT: Overhauser, (765) 494-3037. Photo, background information available from Amanda Siegfried, Purdue News Service, (765) 494-4709.

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