MEPP

[Miracoli]

---

Members don't see this ad.

A 55-yrs-old man sees a neurologist because of weakness in his legs that improves over the course of
the day or with exercise. Extracellular electrical recordings from a single skeletal muscle fiber reveal normal miniature end-plate potentials. Low-frequency electrical stimulation of the motor neuron, however, elicits an abnormally small depolarization of the muscle fibers. The amplitude of the depolarization is increased after exercise.The molecular mechanism underlying these symptoms is most similar to which of the following?
A) Acetylcholine
B) Botulinum toxin
C) Curare
D) Neostigmine
E) Tetrodotoxin

 

[ulikedaggers]

A

 

[ABQ9988]

B. Lambert Eaton's

 

[BlueArc]

B?

In ELS the auto antibodies prevent the release of the vesicles
The botulinum toxin cleaves the synaptobrevins and syntaxins preventing the vesicles to fuse with the neuronal membrane blocking release of neurotransmitter.
Am i thinking right?

 

[ABQ9988]

There was a similar question on NBME 13 (maybe wrong form) and the answer was botulinum toxin.

 

[sarah65]

It was NBME 15, and the answer indeed was botulinum toxin.

 

[Fatalis]

LES
should be B.
@Miracoli is Miracoli's world having a special sale/ promo discount anytime soon 😀

 

[Miracoli]

LES
should be B.
@Miracoli is Miracoli's world having a special sale/ promo discount anytime soon 😀

There was Valentine day promotion, you missed it🙂 Next time i will notify you, please leave your contact🙂

 

[Miracoli]

BB is correct
-Lambert-Eaton myasthenic syndrome(LEMS) and botulism cause Dysfunction in quantal Ca-mediated synaptic vesicle release mechanism to produce EPP but no effect on MEPP (because a synaptic vesicle can be releases SPONTANEOUSLY, without Calcium mediated, and produce MEPP)
- Botulinum toxin inhibits muscle contraction presynaptically by decreasing the amount of ACh
released into the neuromuscular junction. In contrast, curare acts post-synaptically, blocking the
nicotinic ACh receptors and preventing the excitation of the muscle cell membrane.
-Tetrodotoxin blocks voltage-sensitive Na+ channels, impacting both the initiation and the propagation of action
potentials in the motor neuron. Both ACh and neostigmine stimulate muscle contraction.


Thank you for participation
For more explanation about membrane potential check here
http://www.usmleforum.com/files/forum/2014/1/767949.php

 

[BlueArc]

A 55-yrs-old man sees a neurologist because of weakness in his legs that improves over the course of
the day or with exercise. Extracellular electrical recordings from a single skeletal muscle fiber reveal normal miniature end-plate potentials. Low-frequency electrical stimulation of the motor neuron, however, elicits an abnormally small depolarization of the muscle fibers. The amplitude of the depolarization is increased after exercise.The molecular mechanism underlying these symptoms is most similar to which of the following?
A) Acetylcholine
B) Botulinum toxin
C) Curare
D) Neostigmine
E) Tetrodotoxin

If you are putting up NBME questions for discussion please write that along with the question, seeing and solving these questions is going to mess up the predictability of the score for those of us who have yet to give them.

 

[Miracoli]

If you are putting up NBME questions for discussion please write that along with the question, seeing and solving these questions is going to mess up the predictability of the score for those of us who have yet to give them.

This is not NBME Q, this is from Miracoli world🙂