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Some Confusing Questions about Nitropresside and Framshift mutations

3106 Views 7 Replies 3 Participants Last post by  step1an
I have some questions/differentials that are confusing me. I hope somebody could shed some light on them.

  1. Nitroprusside infusion can cause cyanide toxicity (ttt is Na thiosulfate). It can also cause methemoglobinemia (ttt is IV methylene blue and cyanide(?). Is this correct? Can somebody explain this.
  2. In frameshift mutation, there's deletion of a number not divisible by 3 of bases or nucleotides?
  3. How to differentiate between Fibroadenoma and Fibroadensosis (clinically, and by biopsy)?
Thanks in advance.
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I figured out point 1.

Nitrites can cause methemoglobinemia by oxidation of Fe2+ to Fe3+. MetHb is treated with methylene blue.

Surprisingly, this toxicity can also be used as a treatment in cyanide poisoning. MetHb loves CN more than oxygen. So, providing MetHb in CN poisoning will lead to formation of MetHb-CN complexes. At this point, Na thiosulfate is given to bind these complexes and excrete them in the kidneys.
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In med school I was taught that Fibroadenosis is ANDI, the most common breast disease in young women, and that it presents with tender breasts with or without lumps, and the tenderness varies according to the menstrual cycle. On the other hand, Fibroadenoma is a discrete localized firm mass, which is movable "mouse in breast", and is not tender.

First Aid and UW mentions that fibroadenoma is also tender and the tenderness varies with the menstrual cycle. The pathology for both is the same: sclerosing adenosis and ductal epitheliosis.

I got a couple of questions wrong because I thought it was fibroadenosis, and it was not.

I noticed the question-writers favor fibroadenoma. According to First Aid, fibroadenoma is the most common breast lesion in women < 25 yrs old, while fibroadenosis (ANDI) is most common in those > 25 years.

Still kinda confused. :rolleyes:
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