270 likes | 1.34k Views
Radioimmunoassay. Blood Testing. Nicole, Faviola, Mario, Michael, Jesus. What is it?. Radio- The transmission and reception of electromagnetic waves of radio frequency Immuno- Of or pertaining to the production of antibodies or lymphocytes that can react with a specific antigen
E N D
Radioimmunoassay Blood Testing Nicole, Faviola, Mario, Michael, Jesus
What is it? • Radio- The transmission and reception of electromagnetic waves of radio frequency • Immuno- Of or pertaining to the production of antibodies or lymphocytes that can react with a specific antigen • Assay- Determine the content or quality of
Radioimmunoassay (RIA) is a sensitive method for measuring very small amounts of a substance in the blood. • Radioactive versions of a substance, or isotopes of the substance, are mixed with antibodies and inserted in a sample of the patient's blood. • The same non-radioactive substance in the blood takes the place of the isotope in the antibodies, thus leaving the radioactive substance free. • The amount of free isotope is then measured to see how much of the original substance was in the blood.
Who Created it? • This isotopic measuring method was developed in 1959 by two Americans, biophysicist Rosalyn Yalow (1921-) and physician Solomon A. Berson (1918-1972). • Berson and Yallow of Albert Einstein School of Medicine initially described the method to determine insulin levels in human plasma in early sixties. • Yalow and Berson developed the first radioisotopic technique to study blood volume and iodine metabolism.
They later adapted the method to study how the body uses hormones, particularly insulin, which regulates sugar levels in the blood. • The researchers proved that Type II diabetes is caused by the inefficient use of insulin. • How it Works Example: Insulin • To measure insulin, the first step is to mix known amounts of radioisotope-tagged insulin and antibodies. These combine chemically. Next, a small amount of the patient's blood is added. The insulin contained in the blood displaces some of the tagged insulin. The free-tagged insulin is then measured with isotope detectors and the patient's insulin level is calculated.
In 1959 Yalow and Berson perfected their measurement technique and named it radioimmunoassay (RIA). • RIA is extremely sensitive. It can measure one trillionth of a gram of material per milliliter of blood. • Because of the small sample required for measurement, RIA quickly became a standard laboratory tool.
Uses • RIA has many uses, • These include narcotics (drug) detection, blood bank screening for the hepatitis virus, early cancer detection, measurement of growth hormone levels, tracking of the leukemia virus, diagnosis and treatment of peptic ulcers, and research with brain chemicals called neurotransmitters.
Disadvantages • The people being tested are exposed to radiation. • The equipment required to run the test, properly dispose of the radiation, and maintaining a license to work with the radiation can be very expensive. • The cost of disposing of the radioactive waste can be expensive. • Requires specially trained personnel.
Advantages • The test is highly sensitive and can detect very small amounts of antigens. • There is a quick reaction. • Despite the disadvantages, RIA testing is still widely used due to its accuracy in detecting antigens and its reaction time,
Case 1 • Christina Martin, also known as the Jell-O murderer, was convicted of killing her boyfriend by poisoning his Jell-O with LSD. Her defense attorney, Kevin Mahoney, was able to overturn her conviction by challenging the cause of death. • A pathologist testified that he had identified LSD in the boyfriend and had found this through RIA testing. • When tested using GCMS (gas chromatography mass spectrometry) there was a chance that there was no LSD in his system. • The judge concluded that RIA is a screening test that indicates the possible presence of a compound but needs a confirmatory test, such as GCMS, to substantiate its result. • The guilty verdict was overturned and Martin was released from prison.
Case 2 • Ninni Burgel and Frank Burgel had recently been divorced. • Frank wanted sole custody of the children because Ninni was on cocaine. • She claimed she was not any more but the judge ordered that she have her hair and blood tested with RIA in order to prove this.
Review Questions • What are the faults of radioimmunoassay testing? • Why is the test still used despite its faults? • What can radioimmunoassay be used for? • How much of a substance can RIA testing measure per milliliter of blood? • One trillionth of a gram • Does the RIA test require a confirmatory test along with it?
Sources • http://masscases.com/cases/sjc/427/427mass816.html • http://www.relentlessdefense.com/mahoney-in-the-media/in-the-news/christina-martin • http://www.authorstream.com/Presentation/prasanna_bsk-1177846-radioimmunoassay/ • http://www.millipore.com/bmia/files/images/$file/ria_diagram.jpg • http://www.nytimes.com/1988/10/28/nyregion/court-allows-testing-of-hair-for-cocaine.htmlp://w. • discoveriesinmedicine.com/Ni-Ra/Radioimmunoassay-RIA.html#b#ixzz2PKzjsH1k