| Column 1 |
Column 2 (memorize)
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| Wallerian degeneration |
Degeneration of the PNS cells that leaves a permissive environment for regeneration. 1) macrophages remove myelin debris 2) Schwann cells proliferate and provide guidance cues with bands of Bungner
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| What two factors inhibit axon regeneration in the CNS? |
1). myelin debris 2). the formation of astroglial scar by reactive astrocytes which enlarge and proliferate
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| What are two possible outcomes if a neuron extends axons to an injury site in the CNS? |
1) it stalls or undergoes secondary degeneration. It never succeeds in passing through the injury site.
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| What are the classes of inhibitory factors in regeneration in the CNS? |
1). Myelin associated inhibitory molecules (eg. Nogo, MAG) 2). Glial scar-derived factors (eg. CSPG, Tenascin) 3). Repulsive axon guidance cues (eg. Semaphorins, Slits, Netrins, Ephrins)
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| What strategies are there for promoting CNS axon regeneration? |
1). Enhance intrinsic growth ability; 2). Create permissive extrinsic environment; and 3). Use cell replacement therapy.
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| How would you go about creating a permissive environment for regeneration? |
- PNS grafts (eg. sciatic nerve)
- neutralization of inhibitory factors
- modulation of signal transduction of inhibitory factors
- providing guidance signals
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| How would you enhance the intrinsic growth ability of cells in the CNS? |
neurotrophins (NT3, BDNF), other neural growth factors (GDNF, CNTF), and mTOR. By knockouts of Bcl-2 and SOCS3 (recent).
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| What is the impact of BBB in regeneration? |
The blood brain barrier (BBB) prevents the entrance of serum opsonins and peripheral macrophages into distal white matter tracks of the CNS.
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| What is the impact of BNB in regeneration? |
The blood nerve barrier (BNB) allows the entrance of macrophages and serum opsonins, which stimulate macrophages to clear the myelin debris.
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| Give an example of a myelin associated inhibitory molecule? |
Nogo or MAG
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| Give an example of a glial scar-derived factor. |
CSPG or Tenascin
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| Give three examples of a repulsive axon guidance cue. |
Semaphorins, Slits, Netrins, or Ephrins.
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