Psy137BasicsandMethods

Bioassays identifies the chemical processes in a

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Bioassays Identifies the chemical processes in a hormone’s actions and involves testing the hormone on a living animal or cell culture. Hormones tend to exist in very small quantities in the blood and can be quite transient so it is hard to measure and purify them Interestingly, the bioassay can often usefully be conducted on alternate species from which a hormone has been derived. The Rabbit Test” is perhaps the most famous example of a bioassay involving two different species. This was developed in 1929 and was used to detect human pregnancies until the late 1950s. It tested for the presence of human chorionic gonadotropin (hCG) which is made when the blastocyte implants in the uterine wall. Urine was injected into a rabbit. If hCG was present then the rabbit would develop a corpus lutea within 48 hours indicating a person was pregnant. To see the corpus lutea the rabbit had to be sacrificed leading to the joke “the rabbit died” to indicate you were pregnant
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Figure 1.11 A bioassay for prolactin
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The most famous form of an immunoassay is the radioimmunoassay (RIA) and it is a technique that was first able to measure hormones with good accuracy Rosalyn Yalow received the Nobel Prize in 1977 for her work on this technique—a woman Nobel Lauereate Competitive binding Antibodies are produced to any antigen and are sticky and specific Antigens can be radiolabeled (e.g. adding a radioactive carbon) and the antibody will stick to both the radiolabeled antigen (hot) and the non labeled antigen (cold) Create a curve using known amounts of hot and cold antigens with a known amount of antibody Called the standard curve
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Bioassays Identifies the chemical processes in a hormones...

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