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36 Cards in this Set
- Front
- Back
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Bioassay |
A measure of the specific response of an organ, tissue, or cell culture to hormone stimulation |
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Parameters used to assess the performance of an assay |
Sensitivity Accuracy Precision Specificity |
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Accuracy |
Comparison of the observed value with the true value |
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Precision |
The degree of scatter of the observed values about the mean |
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Specificity |
The degree to which an assay responds to substances other than that for which the assay was designed |
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Cross-reaction |
Extent to which a given compound can interfere with an assay |
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What is an advantage of radioimmunoassay (RIA)? |
High sensitivity |
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What are 3 disadvantages of RIA? |
Measures immunoactivity and not bioactivity Short half-life of reagents Inconvenience and health risk of using radioactive substances |
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Steps in performing an RIA |
1. Produce an antibody (Ab) that recognizes the hormone (antigen-Ag) 2. Produce a form of the hormone that is tagged with radioactivity--Ag* 3. In a series of test tubes mix a known amount of labeled hormone, a known amount of Ab, either a known amount of hormone (standard), or an unknown amount of hormone 4. Incubate the reagents for a specified amount of time at a specified temp 5. Separate the bound labeled Ag-Ab complex from the free Ag, the free Ag*, and the free Ab 6. Determine the radioactivity level in either the bound or free portion 7. Plot a standard curve of bound (or free) vs the standard concentration 8. Determine the unknown hormone concentration by reference to the standard curve |
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Hormone concentrations should be compared to normative values that are measured/controlled for: |
Age Gender Time of day Exercise Posture Emotional state Drug therapy |
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Determinations of hormone concentrations are _______________ |
"snapshots" |
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Hormones found in saliva are formed by _______________ and ________________ from the blood |
active transport passive diffusion |
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Hormones that are usefully measured (in saliva) are _____________ |
steroids |
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Saliva concentrations of __________ are highly correlated with plasma concentrations |
steroid hormones |
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______________ and _______________ hormones are not usefully measured in saliva |
Protein thyroid |
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Saliva concentrations of __________ are poorly correlated with plasma concentrations |
protein and thyroid hormones |
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4 advantages of salivary measurements |
Avoids the stress of venipuncture Reflects the free plasma fraction Samples may be collected at home Facilitates multiple sampling |
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Stress from venipuncture may raise __________ levels |
cortisol |
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3 procedures for collecting saliva |
Spitting Drooling Swab |
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Urine concentrations are a: |
"Summary" of the total amount of hormone excreted from the body |
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What method of determining hormone concentrations eliminates pulsatile fluctuation in the results? |
Urine concentrations |
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Urine concentrations are useful for ________ hormones but not for most __________ hormones |
steroid peptide |
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Plasma half-life (definition) |
The length of time required for the plasma concentration to decrease to one half of the initial concentration |
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Half life for hormones should be how long? |
Minutes to days |
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Information about dynamic function is obtained by: |
disturbing the system with suppression or stimulation tests |
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How are monoclonal antibodies produced? |
Spleen cells from an immunized mouse are hybridized with myeloma cells to produce antibody secreting hybridoma cells. The hybridomas are cloned and the monoclonal antibodies are isolated for cultivation. |
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Sensitivity |
The lowest concentration that can be distinguished from zero |
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What is used to quantify precision? |
Coefficient of variation (CV) |
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Coefficient of variation equation |
% CV = 100 * (SD/mean) |
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Competitive binding assay |
Partition of the hormone into two fractions (free and bound) by the reaction with a specific binding reagent (Ab for a RIA) of limited capacity |
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The 3 basic procedures for assays for biological materials |
Biological assays Binding assays Physiochemical assays |
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Binding assays may be directed at the measurement of the ____________ or ___________ |
binder ligand |
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The 3 types of binders in assays for ligands |
Antibody Circulating binding protein Cell receptors |
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The 6 types of tracers (any of which can be used with any of the 3 binders) |
None Isotope Enzyme Fluorescence Phage Particle |
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The final step of binding assays may result in one of three types of separation, including: |
Separation of bound and free ligand No separation Separation of bound and free binder |
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Percent bound is calculated by dividing _______________ by _________________ |
net CPM (of hormone of interest) net CPM (of max binding hormone) |
