Urine and diagnosis

Question 1

What else is present in urine?

Answer 1

hormones and toxins

with disease, new substances will show up

Question 2

What is prescence of glucose in urine the sign of

Answer 2

diabetes

Question 3

What happens six days after conception?

Answer 3

• the site of the developing placenta begins to preduce a chemical called human chorionic gonadotrophin (hCG)
• some is found in blood and urine of the mother

Question 4

What was the most reliable available pregnancy test until the 1960s?

Answer 4

• inject the urine from a pregnant woman into an African clawed toad
• if she was pregnant, the hCG tirggered egg production in the toad wthin 8-12 hours of the inkect
• it could not be used until the woman was several weeks pregnant

Question 5

What do modern pregnancy tests use?

Answer 5

• still test for hCG in urine
• rely on monoclonal antibodies
• some are so sensitive that pregnancy can be detected within hours of implantation

Question 6

What are monoclonal antibodies?

Answer 6

• monoclonal antiboides are antiboides from a single clone of cells that are produced to target particlar cells or chemicals in the body
  *

Question 7

How are monoclonal antibodies made?

Answer 7

• a mouse is injected with hCG so it makes the appropriate antibody
• the B-cells that make the required antibody are then removed from the spleen of the mouse and are fused with a myeloma, a type of cancer cells which divides rapidly
• this new fused cells is known as a hybridoma
• each hybridoma reproducing rapidly, resulting in a clone of millions of ‘living factories’ making the desired antibodies
• these monoclonal antibodies are collected, purified and used in a variety of ways

Question 8

How is the hCG/monoclonal antibody complex formed in a pregnancy test?

Answer 8

• the wich is soaked in the first urine passed in the morning
  
  • this will have the highest levels of hCG as it has built up over night
• the test contains mobile monoclonal antibodies that have small coloured beads attach to them
  
  • they will only bind to hCG
• if the woman is pregant the hCG in her urine binds to the mobile monclonal antibodies
  
  • forms a hCG/antibody complex

Question 9

How does a positive test happen?

Answer 9

• the urine carries on along the test structure until it reaches a window
• here there are immobilised monoclonals antibodies arranged in a pattern (e.g. + sign)
  
  • only bind to the hCG/antibody complex
  • if the woman is pregnant, a coloured line or pattern appears in the first window

Question 10

What happens in the second window?

Answer 10

• the urine continutes up through the test to a second window
• here there is usually a line of immobilised monclonal antibodies that only bind to the mobile antibodies
• regardless of whether they are bound to hCG or not
• the coloured line forms regardless of whether the woman is pregant
  
  • indicates that the test is working
• if she is not pregant only one line will appear