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ASU Radiation Test Uses Genes To Triage Nuclear Attack Victims

Published: Monday, October 31, 2016 - 7:29am
Updated: Monday, October 31, 2016 - 11:34am
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(Diagram by Jason Drees - ASU Biodesign Institute)
The ARad workflow.

Seventy-plus years into the Atomic Age, the United States still lacks a good radiation-dosage test.

But a device being developed by Arizona State University’s Biodesign Institute could soon help doctors triage victims of a nuclear attack by gauging their exposure to ionizing radiation via changes in gene expression.

“There’s going to be this burst of gamma radiation that spreads far and wide from the explosion, and people — even people who are not physically near the explosion site, who do not come into physical contact with the explosion site — will still be exposed to that radiation,” said Joshua LaBaer, interim director of the Biodesign Institute and principal investigator on the project.

The university spent six years developing the ASU Radiation Biodosimetry Test (ARad), which it is now readying for evaluation by the U.S. Food and Drug Administration.

ARad is one of only a few tests under development that can detect radiation exposure levels.

Other current tests gauge contamination — radioactive matter consumed or breathed in, as happened after the Fukushima disaster, or as might occur after a dirty bomb blast. But they cannot judge exposure to ionizing radiation, such as gamma rays from a nuclear bomb.

Each system can process 2,000 blood samples in 24 hours. Plans call for the tests to be made available to several qualified clinics.

“The goal is to be able to do hundreds of thousands of samples per event, in this high-throughput fashion, and to be able to deliver those results to the clinical caregivers about each individual,” LaBaer said. “We’ll have a barcoded sample to tell them, ‘This is the dose that you have.’”

ARad uses equipment already found in many medical centers to look at 13 key genes — 12 known to undergo changes in expression under radiation exposure and one “housekeeping” gene that serves as a control.

Expression is the process that converts genetic information into proteins and other useful products. It involves two steps: transcription, which makes RNA from DNA, and translation, which uses RNA to make the product.

Certain environmental factors, including radiation, can change how some genes are expressed. ARad is based on a subset of these genes, whose expression changes are proportional to exposure levels and timing.

“We can predict the dose of radiation that persons received over a fairly broad range — from 0 to 8 or 9 gray — and from the moment of the exposure to seven days after the exposure,” LaBaer said.

A “gray” (Gy) is the international unit for ionizing radiation dosage, equivalent to 1 Joule/kilogram or 100 rad. Roughly speaking, 2-plus Gy is worrying, whereas 4-6 Gy can be lethal.