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Another way to approach it is to think about MHC class I processing. Basically, if you inhibit the proteasome, peptides will not be generated and nothing is available to be loaded onto MHC I (remember MHC I has to be loaded before it's transported to the cell surface). Cells that don't express MHC I get killed by the natural killers.
"In conclusion, we have demonstrated that the proteasome inhibitor bortezomib down-regulates class I and enhances the sensitivity of myeloma to NK cell–mediated lysis" from the conclusion of the NIH paper
another mechanism is by blocking proteosome u even decrease degration of proapoptotic proteins...so it enchances apoptosis(from uworld)
But CD8+ and NK cells kill via perforin! Why is this answer wrong? Is it because it's not the primary effect?
"The proteasome is the major source of proteolytic activity involved in the generation of peptides for presentation by major histocompatibility complex class I molecules. We report the new observation that bortezomib down-regulates HLA class I on MM cells, resulting in increased NK cell–mediated lysis."
thanks for this explanation!
can any one explain to me why not lens ?
@macrophage95 Lens are an interal part of the refractive power of the eye. Without the lens the image would not be formed on the retina, thus leading to visual loss
Do anyone know why not choroid?
@qfever, no choroid would also be more detrimental to vision since it supplies blood to the retina
That random zanki card with colobomas associated with a failure of the choroid fissure to close messed me up
Seems like the key to this question is in what is omitted from the question stem: there is no mention of vision loss. If we assume there is no vision loss, then we can eliminate things associated with visual acuity (weird to think of in 2 week old but whatever): C, D, E, F. Also, by @hayayah 's reasoning, we eliminate E & F. If you reconsider the "asymmetric left pupil" then the only likely answer between A & B is B, Iris because the iris' central opening forms the pupil. I mistakenly put A because I was thinking of the choroid fissure and I read the question incorrectly - but it's a poorly worded question IMO.
Key here is that it doesn't affect vision- the only thing would be the iris. All others are used in vision. Don't have to know what a coloboma actually is.
The extra section of that Zanki card specifically says that a coloboma "can be seen in the iris, retina, choroid, or optic disc." Don't you dare talk trash about Zanki!