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Blood Test Measures
Scientists from UB report that they have developed and patented a simple blood test that can measure accumulated cell damage from ionizing radiation-one of the major causes of cancer-long before any physical signs are evident.
Results of research that led to the development of the test, described as a "life-long wide-range radiation biodosimeter," appear in the December issue of Health Physics.
Joseph K. Gong, associate professor emeritus of oral diagnostic sciences and chair of UB's Radioisotope Safety Committee, is lead author on the paper. Gong has spent a lifetime researching, lecturing and writing on the health effects of low-level radiation. His work has centered on seeking a predictable, accurate and practical cell marker of internal biological damage from radiation, using a rat model.
Gong's test, called the Transferrin Receptor Red Cell Assay, or E-Tr assay, measures the amount of radiation that has been absorbed by the body. Using a specific biomarker, it reveals the extent of stem-cell mutations due to exposure to X-ray, or to anything potentially carcinogenic that mimics X-ray damage, such as many chemicals used in the microchip industry.
"All cancers develop from a pool of mutated cells that are 'turned on' by one or more triggers," Gong said. "The larger the pool of mutated cells, the greater the risk. Cancer can take years to decades to develop, depending on the type.
"This test provides a way to measure the damage before the first sign of cancer appears," Gong said. "It also can determine if cell mutations from ionizing radiation are increasing over time. If so, the individual can take steps to stop the increase, perhaps through a change in job, diet or environment. It gives people more control over their health."
The method most widely used to determine radiation exposure in the workplace is a badge containing radiation-sensitive film, which the worker wears on the job. The badge measures external radiation exposure only.
Gong and his co-investigator, Chester A. Glomski, professor of anatomy and cell biology, were able to show that radiation exposure causes stem cells-the "mother" of all blood cells-to express an excess of erythrocytes (red-blood cells) bearing receptors for the protein transferrin on their surface membrane. Knowing this cause and effect, it then became possible to use the number of red blood cells with transferrin receptors as a biomarker for radiation exposure. Subsequent blood tests can monitor any increase or decrease in cell damage.
The test, which requires a drop of blood and about two hours for analysis, is capable of measuring the effects of radiation doses ranging from normal levels experienced in everyday life to amounts that would kill 50 percent of those exposed within 30 days, Gong said.
The test could allow individuals who work in jobs that expose them to radiation or chemicals that mimic radiation's effects to know how much cellular damage they've experienced from the exposure and to make appropriate, well-informed health decisions, Gong noted. It can be taken as often as desired.
Such a test also could be useful to the general public to determine exposure to ionizing radiation, such as X-rays and gamma rays used in cancer treatment, Gong said, and to tiny amounts of ionizing radiation emitted by such consumer products as cellular phones, microwave ovens and computer screens.
After decades of working with an animal model, Gong and Glomski used the E-Tr assay on blood samples of seven cancer patients who had received radiation treatment and blood samples from 10 healthy individuals who had been exposed to only a few dental and chest X-rays to determine the effectiveness of the test on humans. The assay produced similar results in human blood samples as in the animal studies, the researchers found.
Gong postulates that this dose-response relationship will allow patients to reconstruct their past radiation doses, as well as project the amount of residual injury from past exposure that will exist at various times in the future.
Gong received an Atomic Energy Commission (AEC) grant in 1964 to study the biomedical effect of low-dose radiation. In 1965, a 20-year follow-up report on the survivors of the atomic bomb lead to a consensus among experts that low-dose radiation was safe.
That finding was overturned in 1986 after advances in measuring radiation made a reassessment possible, but in the interim, very little research in low-dose radiation was conducted. Gong, however, carried on his work in the field at UB for 35 years, buoyed by results obtained through the early AEC funded research, and accumulated data on the effects of radiation exposure from background amounts to lethality.
His decades-worth of data led to the recognition of the specific bone marrow syndrome induced by radiation and to the discovery of the E-Tr assay.
Also participating in the research was Yuqing Guo, biophysicist and research scientists at Biomira USA, Inc., in Cranbury, N.J.