Testing for pregnancy/allergies

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Testing for pregnancy/allergies by Mind Map: Testing for pregnancy/allergies

1. Detection of pregnancy

1.1. Increase in blood and urine levels of

1.1.1. HCG

1.1.2. Oestrogen

1.1.3. Progesterone

1.2. Historically serum is taken from woman and injected into rabbit and if HCG is present rabbit ovulates

1.2.1. Not reliable

1.2.2. Ethical considerations

1.2.3. Lengthy

2. HCG cloned and Ab's raised to it allowing development of 3 immunoassays

2.1. Inhibition of latex agglutination

2.1.1. Rabbit anti-HCG mixed with urine or serum sample

2.1.1.1. If HCG is present it will bind, remvoing anti-HCG from reactions

2.1.1.2. If HCG is not present, mixture will contain free anti-HCG

2.1.1.3. Latex beads added to sample

2.1.1.3.1. Agglutination = NEGATIVE

2.1.1.3.2. No agglutination = POSITIVE

2.2. Radioimmunoassay

2.2.1. Rabbit anti-HCG is mixed with urine or serum sample

2.2.1.1. If HCG is present it will bind, removing anti-HCG from reactions

2.2.1.2. If HCG is not present, mixture will contain free anti-HCG

2.2.1.3. Radiolabelled HCG added to sample

2.2.1.3.1. Highly radioactive = NEGATIVE

2.2.1.3.2. Not radiocactive = POSITIVE

2.3. Dip-stick

2.3.1. Rabbit anti-HCG is bound to coloured latex beads and dried onto filter paper

2.3.1.1. Mixed with urine

2.3.1.1.1. If HCG is present it will be bound by Ab

2.3.1.1.2. If HCG is not present it is not bound

2.3.1.1.3. Latex beads travel up filter paper where they pass a line of immbolised anti-HCG

2.4. Advatnages and disadvantages of each test

2.4.1. ILA

2.4.1.1. Time consuming

2.4.1.2. RElies on visual interpretation

2.4.1.3. Not absolutely quantitative

2.4.2. RIA

2.4.2.1. Easily automated

2.4.2.2. Easily quantified

2.4.2.3. Produces radioactive waste

2.4.3. Dip-stick

2.4.3.1. Very simple

2.4.3.2. Not quantitative

3. Problems with measuring HCG

3.1. Can be rasied in tumours

3.2. Raised if incomplete abortion

3.3. Not present in ectopic pregnancy

4. Testing for allergies

4.1. Hayfever

4.2. Asthma

4.3. Insect saliva

4.4. Food allergy

4.5. Benifits of testing

4.5.1. Identify allergens so they can be avoided

4.5.2. Important in industrial setting

4.5.3. Moniter desensitisation treatment

5. Anaphylactic shock

5.1. Systemic response

5.2. Increased vascular permeability

5.3. Swelling of lips, tongue and larynx

5.4. Fall in BP

5.5. Possible death

6. Rist and Rast

6.1. Rist

6.1.1. Paper disk coated with IgG

6.1.1.1. IgG binds to disk

6.2. Rast

6.2.1. Paper disk coated with known allergen

6.2.1.1. Any IgE specific for any specific allergen binds to disk

7. Therapy

7.1. Antihistamines block release or action of histamines

7.2. increasing doses of antigen results in shift from IgE to IgG