NBME Answers : 69_nbme

davidw This is directly from Goljan I) Hypovolemic shock may occur due to loss of plasma from the burn surface (refer to Chapter 5). • Loss of protein from the plasma loss may result in generalized pitting edema. II) Infection of the wound site and sepsis may occur. (a) Sepsis due to Pseudomonas aeruginosa is the most common cause of infection in burn patients. (b) Other pathogens include methicillin-resistant S. aureus and Candida species. (3) Curling ulcers may occur in the proximal duodenum (refer to Chapter 18). (4) Hypermetabolic syndrome may occur if >40% of the body surface is burned. +16

yex Can someone explain why is it not increased ECF? +26

charcot_bouchard i picked same. Increased ECF but cant remember why. Can you explain WHY it is increased ECF? what was ur reasoning +3

isotopes Burns would lead to a decrease in ECF because the protection from fluid loss is absent; it can lead to shock. :) +4

tinydoc My reasoning behind picking ↑ ECV was that your losing fluid but not electrolytes with the burn ⇒ the ecv would have increased osmolarity, so the fluid from the ICV would be pushed the the ECV. It made sense to me at the time. I guess technically its wrong because the loss of fluids and the gain of fluids would amount to pretty much the same thing. But the insulation and heat loss thing makes sense I guess. +

yex Increased ECF, bc I was thinking about the edema formation.... :-/ +3

atbangura I picked increased ECF because burns increase the capillary permeability coefficient, but now that I am going over it I realized that increasing the permeability would only transfer plasma volume to the interstitial volume, which are both a part of the ECF so therefore ECF would not change. SMH +10

aisel1787 thanks +

69_nbme_420 Burns (and Diarrhea) cause ISOsmotic volume contraction; Costanzo BRS Physio +

tiagob in severe burned patient, also has increased fluid in third spacing or interstitial (leading EDEMA). Different extracellular space is interstitial and vascular +1

peridot I also wanted to add, another huge job of the skin is to prevent loss of fluid. Burn patients are easily dehydrated because they've lost that barrier. This helped me lean away from increased ECV - despite the edema (from one compartment to another) as others have mentioned above, there is a loss in overall ECV due to evaporation from body. +

chaosawaits So I'm the only idiot who thought "loss of B vitamins" sounded like a good answer. Nice. +

almondbreeze info about ferruginous bodies being mf can't be found on FA/UW :'( they just say it's 'material' +

taediggity FA 2020 677, FA 2019 659... mf?? mofos?? +3

69_nbme_420 Just to add: The question asks what cell type initiated the Fibrosis → Alveolar macrophages engulf the particles and induce fibrosis (same pathophys for all Pneumoconiosis). Pathoma 2019 Pg 92 +10

alexv0815 "A small (< 3 μm), golden-brown, dumbbell-shaped particle that contains iron. Most often seen in the alveolar septum in conditions such as asbestosis." amboss +

eacv omg YES!! thanks Uworld I got it correct! exactly this qx asked the exact opposite thing! Hahaha I loved it !! +9

pg32 Even after reading the UWorld explanation, I am still not sure how the answer that reads, "Protein Y expresses all of the epitopes expressed by protein X, but protein X does not..." is incorrect. Based on the graph, I don't see a way we can rule out that answer choice and it sounds more likely than both X and Y having the EXACT SAME epitopes. Can anyone explain? What would the graph look like if the quoted answer choice was correct? +3

69_nbme_420 If you make up an example with numbers, it really helps! “Protein Y expresses all of the epitopes expressed by X, but protein X does not express all of epitopes expressed by Protein Y.” If we say protein Y has epitopes 1, 2, and 3. Then Protein X has epitopes 1 and 3. Then we can clearly see the relationship the AMOUNT of Y added relative to X bound would NOT be linear. Stated another way – we need an exponentially more amount of Y to COMPLETELY unbind X and therefore there would not be a one to one depiction in the graph Similar logic applies for the answer choice that states "protein X expresses all of the epitopes expressed by protein Y, but protein Y does not express all of the epitopes expressed by protein X. E.g. If protein Y has epitopes 1 and 2. And protein X has epitopes 1, 2, and 3. Here again, we have satisfied the answer choices condition, and no matter how much we increase protein Y, protein X will still have epitope 3 bound in this case. +5

69_nbme_420 Just to clarify for the first scenario: We have 3 epitopes on Y, and 2 epitopes on X. That means, assuming the epitopes are all present in equal amounts, if I add 300 grams of protein Y to the solution - only 200 grams will bind protein X. AND ONLY 200 grams of protein X can be unbound. Hope the numbers help! +1

fruitkebabs For anybody still stuck on "Protein Y expresses all of the epitopes expressed by protein X, but protein X does not," although this statement may be true, there is not enough information in the question to prove this. We know for fact that because the Amount of labeled X bound reaches 0, at the very least, protein X and Y express the same epitopes since at a certain concentration, Y is able to completely displace all X from the system. This doesn't exclude the possibility that there may be extra epitopes on Y, but it doesn't prove it either. +4

eacv omg YES!! thanks Uworld I got it correct! exactly this qx asked the exact opposite thing! Hahaha I loved it !! +9

pg32 Even after reading the UWorld explanation, I am still not sure how the answer that reads, "Protein Y expresses all of the epitopes expressed by protein X, but protein X does not..." is incorrect. Based on the graph, I don't see a way we can rule out that answer choice and it sounds more likely than both X and Y having the EXACT SAME epitopes. Can anyone explain? What would the graph look like if the quoted answer choice was correct? +3

69_nbme_420 If you make up an example with numbers, it really helps! “Protein Y expresses all of the epitopes expressed by X, but protein X does not express all of epitopes expressed by Protein Y.” If we say protein Y has epitopes 1, 2, and 3. Then Protein X has epitopes 1 and 3. Then we can clearly see the relationship the AMOUNT of Y added relative to X bound would NOT be linear. Stated another way – we need an exponentially more amount of Y to COMPLETELY unbind X and therefore there would not be a one to one depiction in the graph Similar logic applies for the answer choice that states "protein X expresses all of the epitopes expressed by protein Y, but protein Y does not express all of the epitopes expressed by protein X. E.g. If protein Y has epitopes 1 and 2. And protein X has epitopes 1, 2, and 3. Here again, we have satisfied the answer choices condition, and no matter how much we increase protein Y, protein X will still have epitope 3 bound in this case. +5

69_nbme_420 Just to clarify for the first scenario: We have 3 epitopes on Y, and 2 epitopes on X. That means, assuming the epitopes are all present in equal amounts, if I add 300 grams of protein Y to the solution - only 200 grams will bind protein X. AND ONLY 200 grams of protein X can be unbound. Hope the numbers help! +1

fruitkebabs For anybody still stuck on "Protein Y expresses all of the epitopes expressed by protein X, but protein X does not," although this statement may be true, there is not enough information in the question to prove this. We know for fact that because the Amount of labeled X bound reaches 0, at the very least, protein X and Y express the same epitopes since at a certain concentration, Y is able to completely displace all X from the system. This doesn't exclude the possibility that there may be extra epitopes on Y, but it doesn't prove it either. +4

69_nbme_420 Cyclosporine can also be used to treat Psoriasis (NOT cyclophosphamide - ans B) +11

len49 Drugs that can be used for psoriasis include cyclosporine, MTX, TNF-alpha inhibitors including Etanercept, lnfliximab, adalimumab, certolizumab, golimumab according to FA +2

medstudent Kinda summed up in the index - p 791 2nd row halfway down +2

lovebug as We all know, 1st line therapy of psoriasis is topical corticosteroid, Vit.D analog (Vit.D inhibits keratinocyte proliferation and stimulates keratinocyte differentiation. +1

shakakaka What page if Fa says that these drugs can be used in psoriasis?) +

srmtn FA 2019 p 476 +