15.7 Urine & Diagnosis

Question 1

Why is urine well-suited for diagnostic tests?

Answer 1

• Contains EXCRETED METABOLITES in high concentrations

* NON-INVASIVE

Question 2

What is immunoassay?

Answer 2

Tests which detect for aqueous molecules

using their properties as antigens/antibodies

Question 3

What are monoclonal antibodies?

Answer 3

ANTIBODIES produced from a CLONE of cells

made to TARGET SPECIFIC CELLS/CHEMICALS in the body.

Question 4

How are monoclonal antibodies produced?

Answer 4

1. Mouse is injected with hCG
   ◦ Triggers B-cells to produce appropriate antibody
2. B-CELLS removed + fused with MYELOMA (cancer) cells.
   ◦ Produces HYBRIDOMA: rapidly divides + produced specific antibody.
3. Antibodies (which are all of 1 type) PURIFIED + collected
   ◦ Usually by centrifuging

Question 5

Outline the process of how a pregnancy test works:

Answer 5

1. Wick soaked in urine
   ◦ Test contains mobile antibodies: complementary to + can bind to hCG
2. hCG in urine BINDS to MOBILE ANTIBODY ⟶ hCG/ANTIBODY COMPLEX
   ◦ carried along to 1st window, where immobilised antibodies present.
3. hCG/antibody COMPLEX BINDS to IMMOBILISED ANTIBODY, releasing dye.
   ◦ arranged in pattern, indicating positive test.
   ◦ urine solution carried to 2nd window.
4. EXCESS MOBILISED antibodies (from stick) BIND to IMMOBILISED antibodies, releasing dye, indicating VALID test.

Question 6

What hormone is present specifically in the urine of pregnant women, and where is it secreted?

Answer 6

hCG, human chorionic gonadotrophin

secreted by placenta into bloodstream after embryo implantation.

Therefore found in urine after ultrafiltration in the Bowman’s capsule.

Question 7

When testing for drugs using urine, why may the urine sample be split into 2?

Answer 7

• allows repeats for CONFIRMATION tests

* allows testing using different METHODS (mass spectrometry, gas chromatography)

Question 8

How is gas chromatography used to detect anabolic steriods in the urine?

Answer 8

1. Urine sample VAPORISED + passed along tube with solvent
2. Lining of tube ABSORBS gases
3. Gases analysed, forming chromatogram

Question 9

When a mouse is injected with hCG, it stimulates production of an _____ which is _____ to hCG hormone. Therefore, it is immobilised in pregnancy tests so it can _____ to the hCG in a pregnant woman’s urine.

Answer 9

antibody complementary bind

Question 10

What 3 methods can be used to test for substances within urine?

Answer 10

IMMUNOASSAY

GAS CHROMATOGRAPHY

MASS SPECTROMETRY