Taking a shot at nuclear terrorism.

• Author: Jean, Grace V.
• Position: INSIDE SCIENCE + TECHNOLOGY

* If a one-kiloton nuclear device exploded in New York City, it would kill or sicken millions of people because there are no effective and non-toxic treatments for victims of acute radiation syndrome. But a new Pentagon-funded drug currently proceeding through human trials potentially could help save many of those lives.

Cleveland BioLabs Inc. of Buffalo, N.Y., has developed a radiation countermeasure, called Protectan CBLB502. When given as a single injection, as many as 80 percent of those exposed to total body irradiation could survive.

In experiments with monkeys, scientists could not find traces of radiation poisoning in more than half of the test animals after 40 days had elapsed from the time of irradiation and administration of the drug.

Protectan CBLB502 works by temporarily suppressing cell death so that the body can make the necessary repairs, says Michael Fonstein, president and chief executive officer of the company, whose studies of tumor protection mechanisms led to the discovery of the drug.

[ILLUSTRATION OMITTED]

When healthy tissues and cancerous tumors are exposed to radiation, cells in both cases die. But they perish for different reasons. When tumors are hit by radiation, their cells cannot find and repair the damage, so they go into remission and die, he explains. Healthy tissues can tolerate high doses of radiation. But some tissues, including hair follicles, elements of the intestinal tract and bone marrow, are hypersensitive to radiation and are more susceptible to a phenomenon called apoptosis, or suicidal death of cells. In these tissues, cells die off before healing can happen.

If given time to repair, scientists thought, the cells might survive.

Compounds in Protectan CBLB502 not only slow cell death, but they also appear to speed up revival by inducing molecules to destroy free radicals and by causing the proliferation of regenerating cytokines, or the proteins that serve as messengers between cells.

"There's a lot of hope and excitement about the possibility of having a drug like this," says John Parker, a science advisor to the lab. "502 is clearly distinct from anything that's in the arsenal today."

Radiation antidotes in the nation's stockpile target specific isotopes. Potassium iodine, for example, counters the effects of exposure to Iodine-131, an isotope that was released following the 1986 nuclear reactor accident at Chernobyl. When taken, potassium iodine travels to the thyroid to block the radioactive...