Drug may reduce harm of potentially lethal radiation

Exposure to nuclear radiation in the event of an incident has the potential to injure and

kill thousands of people. Emergency measures that can be given in the first 24 hours to limit the

damage to the body until better medical care is available can save lives, say researchers who

have found a drug that appears to fit this need.

Given 24 hours after potentially-lethal exposure to nuclear radiation, the drug appears to extend survival by lessening damage to the gut.

In the journal Laboratory Investigation, a team from the University of Texas Medical

Branch (UTMB) at Galveston describes how the experimental drug TP508 showed promising results in

tests on mice.

They note how a single injection of TP508, a regenerative peptide, significantly

increased survival in mice after exposure to nuclear radiation, even though it was given 24 hours

after the exposure occurred.

The drug works by limiting the damage to the gut, says lead author Dr. Carla Kantara, a

researcher in biochemistry and molecular biology.

Exposure to high doses of radiation can kill because of various serious effects on the body.

One of these effects is gastrointestinal (GI) toxicity syndrome, due to damage to the gut lining.

When the gut lining is damaged, its ability to absorb water during digestion is reduced,

increasing the likelihood of imbalances in electrolytes, bacterial infection, leakage from the

intestines, sepsis, and death, note the authors.

Senior author Darrell Carney, an adjunct professor in biochemistry and molecular biology, and

also CEO of Chrysalis BioTherapeutics, Inc., a company that develops branded

drugs like the one tested in the study, says:

“Because radiation-induced damage to the intestines plays such a key role in how well a person

recovers from radiation exposure, it’s crucial to develop novel medications capable of preventing

GI damage.”

Drug appears to activate stem cells and preserve crypt cell regeneration

GI toxicity syndrome results from radiation damage to the crypt cells in the small intestine

and colon. These cells have to constantly replenish themselves to maintain the health and

integrity of gut lining.

Crypt cells are very sensitive to radiation damage and their health is often used as an

indicator of a patient’s chances of survival following radiation exposure.

The study shows that TP508 appears to reduce the effects of GI toxicity by activating

radiation-resistant stem cells and preserving the ability of crypt cells to regenerate themselves to

maintain and restore the gut lining.

TP508 is a thrombin peptide developed to stimulate tissue repair following damage to

skin, bone and muscle. Previous studies have shown that the drug works by stimulating growth of new

blood vessels, restoring blood flow, curbing inflammation and reducing cell death.

Trials in human patients indicate that TP508 speeds up the healing of diabetic foot ulcers

and wrist fractures with no serious drug-related side effects. Dr. Kantara concludes:

“The current results suggest that the peptide may be an effective emergency

nuclear countermeasure that could be delivered within 24 hours after exposure to increase

survival and delay mortality, giving victims time to reach facilities for advanced medical

treatment.”

The Centers for Disease Control and Prevention (CDC) distinguish between radioactive

contamination and radiation exposure – both of which could occur if radioactive materials are

released into the environment as the result of a nuclear accident, a natural event, or an act of

terrorism.

Radioactive contamination is where radioactive material is deposited on or in an object or person. Radiation exposure occurs when radiation energy – in the form of waves or particles –

from radioactive materials penetrate the body. A person exposed to
radiation is not necessarily contaminated with radioactive material.

Radiation is all around us and our bodies have ways to deal with the low levels were are

exposed to every day. Techniques like X-rays and CT scans use controlled amounts of radiation

through the body to produce images. Exposure to small amounts of radiation over a long time can

raise a person’s risk of cancer. It can also cause mutations in genes that are passed on to

offspring.

Exposure to a lot of radiation over a short period – such as from a nuclear accident – causes

burns and severe damage to tissues and organs, which is the problem addressed by this study.

Meanwhile, Medical News Today recently learned from a series of articles published in

The Lancet, that nowadays, people are more likely to suffer mental illness following a nuclear accident than experience

physical effects.

Written by Catharine Paddock PhD

Copyright: Medical News Today