Lecture 9 - Manipulation of endocrine function Flashcards

1
Q

Discuss the advantages and disadvantages of different methods for delivering hormones.

A
Feed additives
Advantages
- Works for small molecules
Disadvantages
- Not good for protein – digested
- Potential contamination of equipment 
Single or multiple injection
Advantages
- Bypasses digestive system
- Gives a burst of hormone (in one shot)
- Can use ultiple injections to mimic physiological levels

Sustained release devices
Advantages
- Ideal for long lasting hormone treatment
- Less time consuming than multiple injections
Disadvantages
- Dose can be a problem – super-optimal can desensitize system
- Formation of abscesses, infections, immune response
- Stability, solubility of hormone?
- Many hormones need to be pulsatile to have a biological effect (implant delivers continuous hormone)

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2
Q

Describe potential approaches to produce pulsatile hormone release from implants.

A

Mechanical pump
- Electric pump strapped on patient and connected to IV

Eroding systems
- Bulk eroding

Surface eroding
- Multiple layer of surface polymer

Osmotic device

  • Surface layer made of 2 layers
  • Water soluble polymer
  • Water soluble pore former
  • Ratio insoluble to soluble dictates rupture time
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3
Q

Describe the potential use of encapsulated cells for hormone replacement

A

“Living implant”

- immune cells can’t get in but nutrients can

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4
Q

Outline the method and application of immunoneutralization of hormones.

A

Active immunization

  • Immunizae animal against hormone (using hormone as antigen)
  • Ab produced by animal will block endogenous hormone production
  • Works great if animal responds to antigen and produces antibody

Passive Immunization

  • Infuse purified Ab against hormone into animal
  • Use Ab that binds the receptor to block hormone action -

Problems

  • Removal of negative feedback = increase in hormone secretion
  • Immune response isn’t always effective
  • Transfer of immunoglobulins to offsprings via eggs, colostrum, placenta
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5
Q

Discuss the use of anti-idiotypic antibodies to mimic hormone action.

A

Idiotype = part of an antibody that recognizes hormone

Anti-idiotypic antibodies

  • Production of secondary antibodies directed against primary antibodies to a hormone will produce some antibodies that are specific for the idiotypic region
  • These can have hormonal activity

Disadvantages

  • Must first generate, test, purify primary Ab
  • Anti-idiotypic Ab may not have hormonal activity
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6
Q

How are transgenic animals made and how can they be used to affect endocrine function.

A

Produced by inserting new gene(s) or by modifying the expression of existing gene – gene knockouts can be made by interrupting the expression of particular genes

  • New genes can be used to modify hormone function to
    1. Improve growth
    2. Improve heath
    3. Improve productivity
  • Can be ussed as model systems to study hormone fuction
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