Scientists have developed a test that can tell if a person is in dire need of undergoing treatment for radiation poisoning.
Duke University researchers led by John Chute, suggest that drawing a blood sample and then using gene-chip technology to scan thousands of genes in the DNA of lymphocytes could determine quickly, whether someone requires treatment for radiation poisoning.
Says Chute: "The goal would be to develop a test that's practical and can be applied to thousands of people in a mass casualty situation." This would include events like 'dirty bombings' and nuclear incidents.
Methods currently used for making such diagnoses involve culturing bone marrow cells drawn from the hip to search for chromosomal damage, or else, repeatedly drawing blood over several days to measure accumulating damage to lymphocytes.
Yet, both these processes take longer than the critical 48-to-72-hour period during which treatment to reverse cell damage in the immune system would be most beneficial or, when infection, bone marrow failure and heightened cancer risk can be prevented.
The researchers developed an animal model for their radiation test, exposing mice to either low-level radiation that is normally harmless, levels that typically weaken the immune system or a lethal dose of radiation.
Six hours later, the scientists took blood samples. After analyzing thousands of genes in each group, the researchers focused on signature patterns of roughly 100 gene changes that each radiation level created in the mice.
"There's a complex molecular biological response to radiation that seems very unique at different dose levels," Chute says.
"The classes of genes that respond are unpredictable and not generally overlapping", he added.
The report was publishd in the journal PLoS Medicine.
In addition to this, the team also did human trials in leukemia and lymphoma patients who were receiving large doses of radiation prior to undergoing bone marrow stem cell transplants.
In this case, patients tested just prior to irradiation and six hours later were compared with healthy subjects. The gene profiles discriminated between those who had and had not been exposed, with 90 percent accuracy.
Chute speculates the false positives and missed exposures were caused by exposure to radiation during previous cancer treatments.
Chute believes that with current gene-chip technology the test will take three days to complete. Yet the group is in the process of refining its method by homing in on a set of 25 genes that could be reliably checked to determine within 12 to 24 hours not only whether exposure took place, but also the relative dosage received.