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NBME 16 Answers


Question#3 (reveal difficulty score)
A 38-year-old woman comes to the physician ...
Serum calcium concentrationπŸ”,πŸ“Ί

Question#5 (reveal difficulty score)
A 24-year-old man comes to the physician ...
Ξ±-Adrenergic agonistπŸ”,πŸ“Ί

Question#8 (reveal difficulty score)
A 55-year-old man comes to the physician ...

Question#14 (reveal difficulty score)
Lesch-Nyhan syndrome, an X-linked recessive ...

Question#18 (reveal difficulty score)
A screening program is instituted for ...

Question#26 (reveal difficulty score)
A 16-year-old boy is brought to the emergency ...
Area labeled by the letter 'E'πŸ”,πŸ“Ί

Question#30 (reveal difficulty score)
A 5-year-old boy is brought to the emergency ...
Cerebral edemaπŸ”,πŸ“Ί

Question#37 (reveal difficulty score)
A 54-year-old man has an aneurysm in the ...

Question#39 (reveal difficulty score)
A 28-year-old woman comes to the physician ...

Question#41 (reveal difficulty score)
An 18-year-old man with acute lymphoblastic ...
Amphotericin BπŸ”,πŸ“Ί

Question#47 (reveal difficulty score)
A 24-year-old African American man comes to ...
Pseudofolliculitis barbaeπŸ”,πŸ“Ί

Question#48 (reveal difficulty score)
A 12-year-old boy is brought to the physician ...
Abnormal myelin sheathsπŸ”,πŸ“Ί

Question#13 (reveal difficulty score)
A 5-year-old boy is brought to the physician ...

Question#37 (reveal difficulty score)
A 33-year-old man comes to the physician ...
Glycogen phosphorylaseπŸ”,πŸ“Ί

Question#49 (reveal difficulty score)
During an experimental study of oxygen ...
Proximal tubuleπŸ”,πŸ“Ί

Question#50 (reveal difficulty score)
A 35-year-old man comes to the physician ...
Adenylyl cyclaseπŸ”,πŸ“Ί

Question#3 (reveal difficulty score)
An 83-year-old man comes to the physician ...
Bullous pemphigoid antigenπŸ”,πŸ“Ί

Question#5 (reveal difficulty score)
A 45-year-old man is admitted to the hospital ...

Question#9 (reveal difficulty score)
A 53-year-old homeless man with alcoholism is ...
Normal oral floraπŸ”,πŸ“Ί

Question#12 (reveal difficulty score)
An 18-year-old woman comes to the physician ...
Interstitial nephritisπŸ”,πŸ“Ί

Question#17 (reveal difficulty score)
A Gram stain is performed on a sputum ...
Outer membraneπŸ”,πŸ“Ί

Question#20 (reveal difficulty score)
An investigator is studying strains of ...
Natural transformationπŸ”,πŸ“Ί

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A 27-year-old nulligravid woman comes to the ...

Question#26 (reveal difficulty score)
A study is designed to evaluate the ...

Question#30 (reveal difficulty score)
A 54-year-old woman who works as a nurse ...
Interferon gammaπŸ”,πŸ“Ί

Question#38 (reveal difficulty score)
A 68-year-old man comes to the physician ...
Right ophthalmicπŸ”,πŸ“Ί

Question#39 (reveal difficulty score)
A 27-year-old woman comes to the physician ...

Question#40 (reveal difficulty score)
A female newborn is delivered at term to a ...
Enlarged thyroid glandπŸ”,πŸ“Ί

Question#8 (reveal difficulty score)
A 24-year-old woman comes to the physician ...
Tuberous sclerosisπŸ”,πŸ“Ί

Question#11 (reveal difficulty score)
A 78-year-old man comes to the physician ...
Bacterial endocarditisπŸ”,πŸ“Ί

Question#12 (reveal difficulty score)
A 39-year-old woman with rheumatoid arthritis ...
Tumor necrosis factor-Ξ±πŸ”,πŸ“Ί

Question#24 (reveal difficulty score)
A 35-year-old man comes to the physician ...

Question#27 (reveal difficulty score)
A previously healthy 18-year-old man is ...
Brief psychotic disorderπŸ”,πŸ“Ί

Question#32 (reveal difficulty score)
A 70-year-old woman is found to have ...
Candida albicansπŸ”,πŸ“Ί

Question#40 (reveal difficulty score)
A new antiplatelet agent is developed for the ...

Question#49 (reveal difficulty score)
A 40-year-old woman comes to the emergency ...
Entamoeba histolyticaπŸ”,πŸ“Ί

Question#50 (reveal difficulty score)
A 35-year-old woman participates in a study ...
Day 12πŸ”,πŸ“Ί

Question#43 (reveal difficulty score)
A 15-year-old boy is brought to the physician ...

Question#48 (reveal difficulty score)
A newborn female is diagnosed with ...
Thyroxine (T4)πŸ”,πŸ“Ί

Question#7 (reveal difficulty score)
A 48-year-old man is referred for evaluation ...
Increase in widthπŸ”,πŸ“Ί

Question#1 (reveal difficulty score)
A 57-year-old man comes to the physician ...
Inferior mesentericπŸ”,πŸ“Ί

Question#2 (reveal difficulty score)
A 66-year-old man has a surgical excision of ...

Question#13 (reveal difficulty score)
A 30-year-old woman with Li-Fraumeni syndrome ...
Impaired regulation of apoptosisπŸ”,πŸ“Ί

Question#16 (reveal difficulty score)
A 53-year-old man is brought to the emergency ...
Microglial cellsπŸ”,πŸ“Ί

Question#18 (reveal difficulty score)
A 43-year-old man comes to the physician ...

Question#21 (reveal difficulty score)
A 50-year-old man comes to the physician ...

Question#23 (reveal difficulty score)
A 7-year-old girl is brought to the emergency ...
Right lowerπŸ”,πŸ“Ί

Question#24 (reveal difficulty score)
A 16-year-old girl with cystic fibrosis is ...
Vitamin EπŸ”,πŸ“Ί

Question#25 (reveal difficulty score)
A 1-year-old boy is brought to the physician ...
Inability to produce melaninπŸ”,πŸ“Ί

Question#27 (reveal difficulty score)
A 62-year-old man with unstable angina ...
Left coronaryπŸ”,πŸ“Ί

Question#30 (reveal difficulty score)
A 1400-g (3-lb 2-oz) female newborn is ...

Question#31 (reveal difficulty score)
A healthy 24-year-old woman participates in a ...
"B" point on the graphπŸ”,πŸ“Ί

Question#32 (reveal difficulty score)
A 31-year-old woman is diagnosed with ...
T lymphocytesπŸ”,πŸ“Ί

Question#35 (reveal difficulty score)
A 29-year-old woman comes to the physician ...
Follicular atrophyπŸ”,πŸ“Ί

Question#44 (reveal difficulty score)
A 2-year-old boy is brought to the physician ...

Question#47 (reveal difficulty score)
A 54-year-old man is scheduled for physical ...
Lateral (external) rotationπŸ”,πŸ“Ί

Question#1 (reveal difficulty score)
A previously healthy 59-year-old man comes to ...
DNA polymeraseπŸ”,πŸ“Ί

Question#4 (reveal difficulty score)
A 26-month-old boy is brought to the ...
Nocardia asteroidesπŸ”,πŸ“Ί

Question#5 (reveal difficulty score)
A 51-year-old man who is a farmer comes to ...
Leukemoid reactionπŸ”,πŸ“Ί

Question#6 (reveal difficulty score)
A 50-year-old man comes to the emergency ...
NADPH oxidaseπŸ”,πŸ“Ί

Question#7 (reveal difficulty score)
An 80-year-old woman who develops fever and ...
Pseudomonas aeruginosaπŸ”,πŸ“Ί

Question#10 (reveal difficulty score)
A 66-year-old man is brought to the emergency ...
Increasing cGMPπŸ”,πŸ“Ί

Question#15 (reveal difficulty score)
A 62-year-old man comes to the physician for ...

Question#16 (reveal difficulty score)
A 56-year-old man is scheduled for repair of ...
Ligamentum flavumπŸ”,πŸ“Ί

Question#19 (reveal difficulty score)
An otherwise healthy 60-year-old man comes to ...
Scattered shrunken cellsπŸ”,πŸ“Ί

Question#20 (reveal difficulty score)
A 28-year-old woman, gravida 2, para 1, comes ...
Venous hypertensionπŸ”,πŸ“Ί

Question#26 (reveal difficulty score)
A 35-year-old man with a longstanding history ...

Question#32 (reveal difficulty score)
A 35-year-old woman is given 500 mg of drug X ...
8 πŸ”,πŸ“Ί

Question#34 (reveal difficulty score)
A 30-year-old woman comes to the physician ...

Question#36 (reveal difficulty score)
A 55-year-old man comes to the physician ...
Volume depletionπŸ”,πŸ“Ί

Question#38 (reveal difficulty score)
A 3-year-old boy is brought to the physician ...
Feces-contaminated soilπŸ”,πŸ“Ί

erections libido
Question#43 (reveal difficulty score)
A 23-year-old man comes to the physician ...
Pudendal nervesπŸ”,πŸ“Ί

Question#44 (reveal difficulty score)
Two days after undergoing a right hip ...
Dead spaceπŸ”,πŸ“Ί

Question#46 (reveal difficulty score)
A 9-month-old boy is brought to the emergency ...
Ectodermal neural crest cellsπŸ”,πŸ“Ί

Question#1 (reveal difficulty score)
A 22-year-old man comes to the physician ...

Question#4 (reveal difficulty score)
A 6-month-old girl is brought to the ...

Question#9 (reveal difficulty score)
A 64-year-old man is evaluated for cough, ...

Question#19 (reveal difficulty score)
A healthy 25-year-old man lives at 10,000 ...

Question#12 (reveal difficulty score)
A 62-year-old man with chronic renal disease ...
Plasma hemoglobin concentrationπŸ”,πŸ“Ί

Question#25 (reveal difficulty score)
A 46-year-old man comes to the physician ...
Neuronal degenerationπŸ”,πŸ“Ί

Question#26 (reveal difficulty score)
A 65-year-old man with peripheral vascular ...

Question#27 (reveal difficulty score)
Two days after admission to the hospital ...
Renal papillary necrosisπŸ”,πŸ“Ί

pharm pharmacology
Question#31 (reveal difficulty score)
A 62-year-old woman with recurrent non-small ...

Question#34 (reveal difficulty score)
A 42-year-old man with hepatitis C undergoes ...
Chronic inflammationπŸ”,πŸ“Ί

Question#36 (reveal difficulty score)
A 43-year-old woman who has been diagnosed ...
"B" label on the CTπŸ”,πŸ“Ί

Question#38 (reveal difficulty score)
A 65-year-old woman with hypertension comes ...

Question#44 (reveal difficulty score)
A 9-year-old boy is brought to the physician ...
Protein structureπŸ”,πŸ“Ί

Question#1 (reveal difficulty score)
A previously healthy 7-year-old boy is ...
Bartonella henselaeπŸ”,πŸ“Ί

Question#3 (reveal difficulty score)
A couple seeks genetic counseling because of ...

Question#5 (reveal difficulty score)
A 60-year-old man with no history of bleeding ...
Kallikrein formationπŸ”,πŸ“Ί

Question#11 (reveal difficulty score)
An investigator is conducting a study of ...

Question#18 (reveal difficulty score)
An investigator is studying bacterial ...

Question#21 (reveal difficulty score)
A 3-year-old boy is brought to the emergency ...
Procollagen synthesisπŸ”,πŸ“Ί

Question#24 (reveal difficulty score)
A 6-month-old boy with a history of recurrent ...
T-lymphocyte deficiencyπŸ”,πŸ“Ί

Question#34 (reveal difficulty score)
An investigator is conducting a study of ...
P. vivax and P. ovaleπŸ”,πŸ“Ί

Question#35 (reveal difficulty score)
A 68-year-old woman comes to the physician ...
Superior mesentericπŸ”,πŸ“Ί

Question#41 (reveal difficulty score)
A 23-year-old woman, who was diagnosed with ...
Substance PπŸ”,πŸ“Ί

Question#4 (reveal difficulty score)
A 66-year-old man comes to the physician ...
Dilated cardiomyopathyπŸ”,πŸ“Ί

Question#6 (reveal difficulty score)
A 56-year-old man with a palpable hard nodule ...
Pelvic parasympathetic nervesπŸ”,πŸ“Ί

Question#11 (reveal difficulty score)
A 70-year-old African American woman comes to ...

Question#12 (reveal difficulty score)
A 20-year-old woman who works as a secretary ...

Question#22 (reveal difficulty score)
A 60-year-old man comes to the physician for ...
Aortic valve stenosisπŸ”,πŸ“Ί

Question#28 (reveal difficulty score)
A 35-year-old woman comes to the physician ...

Question#45 (reveal difficulty score)
A 38-year-old woman comes to the physician ...
Iron deficiency anemiaπŸ”,πŸ“Ί

Question#46 (reveal difficulty score)
A 28-year-old woman comes to the physician ...
Wegener granulomatosisπŸ”,πŸ“Ί

Question#50 (reveal difficulty score)
A 67-year-old man comes to the physician ...
Cigarette smokingπŸ”,πŸ“Ί

Question#2 (reveal difficulty score)
A 76-year-old man comes to the physician for ...
Drinking home-distilled liquorπŸ”,πŸ“Ί

Question#8 (reveal difficulty score)
A pale 62-year-old man has increasing fatigue ...
Hairy cell leukemiaπŸ”,πŸ“Ί

Question#27 (reveal difficulty score)
A 4-month-old boy is brought to the physician ...
Chediak-Higashi syndromeπŸ”,πŸ“Ί

Question#28 (reveal difficulty score)
A 62-year-old man comes to the physician ...

Question#49 (reveal difficulty score)
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A 75-year-old woman with osteopenia comes to ...
Normal agingπŸ”,πŸ“Ί

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Segmental ischemic necrosisπŸ”,πŸ“Ί

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Ulcerative colitisπŸ”,πŸ“Ί

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Dysthymic disorderπŸ”,πŸ“Ί

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Streptococcus pneumoniaeπŸ”,πŸ“Ί

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A 25-year-old man is brought to the emergency ...
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Hantavirus strain A grows poorly at a ...

Recent comments ...

... bingcentipede made a comment on nbme16/block1/q#30 (5 yo boy, presents to ER after 16 hours of severe vomiting, increased sleepiness)
submitted by bingcentipede(305)

Kid had a viral URI then took aspirn -> Reye syndrome, a hepatic encephalopathy. There is increased ammonia production because of the liver damage, leading to hyperammonemia. This gets to the brain, is ocnverted to glutamine (an osmolyte). This causes the brain swelling.

It's not E) viral encephalitis because it implies the virus is directly causing the encephalitis. Instead, the viral infection -> aspirin -> liver damage -> ammonia -> crosses BBB -> converted to glutamine -> draws in water -> cerebral edema

cheesetouch  FA18 p 384 +
... cassdawg made a comment on nbme16/block1/q#2 (A 66-year-old man has a surgical excision of a brain...)
submitted by cassdawg(1398)

This is metastatic renal cell carcinoma (FA2020 p605) for the following reasons:

  • Polycythemia - this is the primary clue, as it is associated with ectopic EPO (erythropoitin) secretion in paraneoplastic syndromes (FA2020 p228), which can be caused by pheochromocytoma, renal cell carcinoma, heptocellular carcinoma, hemangioblastoma and leiomyoma. Of these, only liver and kidney would be a choice given and hepatocellular carcinoma is incorrect because he did not have any associated finding of jaundice, hepatomegaly, ascites, or anorexia (FA2020 p392). Plus, the liver does not commonly metastasize to brain whereas kidney does (FA2020 p223)
  • Hypercalcemia - this is likely indicative of PTHrP secretion, and renal cell carcinoma is one of the cancers that can do this. However, this is fairly nonspecific as there are many cancers that can secrete PTHrP.
  • Heamaturia - suggestive of kidney/urinary tract involvement
  • Negative for carcinoembryonic antigen - this is a nonspecific marker mainly for colon and pancreatic cancers (FA2020 p226)
hungrybox  WOW. Amazing explanation. Great work!! +
nbmeanswersownersucks  Additionally the histo looks like the Clear cell type of RCC. The large white/clear spaces with "chicken-wire" vessels and stroma between them. +10
... zincy7 made a comment on nbme16/block4/q#24 (35 yo man, 6 months burning abdominal pain one to two hours after eating)
submitted by zincy7(23)
unscramble the site ⋅ remove ads ⋅ become a member ($39/month)
  • nBngriu bAomiadln Pnai hruos atrfe niaetg = acGrtis ecrul
  • Bclka tsloso rof 2 syad = ???
  • ocafeRtryr to OTC cinsAdta nda H2 lBrecsok
  • inSaegtw and owL PB
  • nicectaarP ssaM = stmo ylliek NGRTAIAMSO

hsIiaumencomtcmiolh gibanlle esus ednaobisit sa eakrsmr rof hwat heyt ntwa to ifdn. nI this as,ce e'ewr inscpgsetu trsniag evgni eth yspmtosm

t:eNo uoY oshdul srviee teh ,octfunin ia,suitontlm dna site of leesear for aech of hte ohsrnome ndeeiotnm as ewll

CEREF ERNE:siroe-EolZlinlgln rdnoeySm

bingcentipede  Black stool because blood in the GI tract? +2
passplease  I was tempted to pick insulin, because of the orthostatics and sweating that could resemble hypoglycemic episodes. Why are those present in a gastrinoma? +3
deberawr  @passplease it's possible that increased gastrin -> peptic ulcers -> perforation -> shock -> sympathetic nervous system overload -> sweating and hypotension +
jsanmiguel415  Black stool = melena = bleeding above the ligament of trietz from ulcers +
rina  @passplease according to amboss gastrinomas can cause steatorrhea and malabsorption, in addition to anemia from GI bleeding. that might explain the light headedness and low-ish bp. +
jj375  Zollinger Ellison Syndrome --> causes duodenal ulcers that are bleeding causing melena and the low blood volume (symptoms of light headed and low BP). I would guess that sweating is from what @deberawr said of the increased sympathetics from the low blood volume +4
cheesetouch  FA18 347 zollinger ellison +
... medninja made a comment on nbme16/block2/q#13 (5 yo boy, 8 months of recurrent middle ear and upper respiratory tract infection)
submitted by medninja(22)
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I lecl aeeissd dheβ€”ir inet soayolslm gastore drirdeso (oaauomtsl s)eersie;cv fteedc in ryeseola-tftspc-1lea-rhcnuhNosmpnaloaisgy &g-t;- fiuaerl fo eth Glgio to petlyoahsphor nosmnae eseirusd crseeade( o6seeh-sapt-pamh)onn on roytnosclgiep ;-t&g- eptsinorΒ  rae desceert axelaelrcltruyl haretr athn veiderled to sosylosem

iury_r1beiro  FA 2020 p 47 +1
an1  this is I-cell disease. we can tell because it's in a child (indicating AR as those occur in younger ages for the most part), he has recurrent infections, HSM (because the lipids, carbs, and proteins aren't broken down in the lysosome, they enter the blood and may deposit in the liver, spleen, heart, and bone resulting in enlargement), the presence of a NAG is right from FA. these proteins are not tagged with manose-6-phosphate and so don't go to the lysosome for degradation, lysosomal levels also increase in the blood. patients often present just like hurlers, + claw hand and kyphoscolosis. +
... andro made a comment on nbme16/block1/q#26 (A 40-year-old woman comes to the physician for an...)
submitted by andro(213)

Niacin( Vit B3)
- inhibits lipolysis ( hormone sensitive lipase ) and hepatic VLDL synthesis /secretion .

Side effects : Facial flushing , secondary to prostaglandin release . Pre treat with NSAIDS
- Also causes Hypergl;ycemia and Hyperuircemia , as such avoid in Gouty patients and Diabetics

... hungrybox made a comment on nbme16/block3/q#1 (20 yo man, 4 hours abdominal pain, nausea, vomiting)
submitted by hungrybox(1113)

ACUTE alcohol inhibits CYP β†’ Increased bioavailability of acetominophen

CHRONIC alcohol induces CYP β†’ Induction of cytochrome P450 enzymes that activate acetaminophen to a hepatotoxic metabolite

I got this wrong because I assumed chronic alcohol meant years and years. I guess a weekend will suffice?

Honestly, fuck this problem.

lfcdave182  Yeah fuck this question. 2-3 days of something would never be considered chronic in anything else. +5
pontiacfever  Drink a lot for a week makes you a chronic alcoholic? +1
pontiacfever  That means alcohol abuse = chronic alcoholism +2
skilledboyb  Why would increased bioavailability of acetaminophen place the patient at increased risk of liver injury? What's dangerous about that? +
i_hate_it_here  Metabolism of acetaminophen turns it into toxic metabolites (NAPQI) that inhibit glutathione in the liver forming toxic tissue products. FA2020 pg: 485 +3
... cassdawg made a comment on nbme16/block2/q#38 (A 3-year-old boy is brought to the physician by his...)
submitted by cassdawg(1398)

I think this is Strongyloides stercoralis (threadworm) is a roundworm whose larvae live in soil and who can cause pulmonary disease. It has the ability to penetrate skin from the soil but can also be obtained by ingesting feces contaminates soil (FA2020 p159)

Most intestinal roundworms are fecal-oral route except strongyloides which can also penetrate skin, hookworm (necator americanus) which only penetrates skin, and trichinella which can come from undercooked meats (especially pork) but whose symptoms do not match that of the patient. Trichinella larvae enter the blood stream and infect muscle and can also cause trichinosis with fever, nausea, vomiting, periorbital edema, and myalgia.

shervinbd  I think it is Ascaris, not Stringlyloides. The symptoms could be explained by Loeffler syndrome, caused by Ascaris larva migration. Ascaris is transmitted through fecal oral route, so ingestion of feces contaminated soil could cause the problem. Per FA, Strongylides is transmitted by larva penetrating skin. +22
drmifta  Its Ascaris. Fecal oral transmission -> Larvae penitrate GIT -> Blood Stream -> Lung {Maturation, Respiratory Symptom} -> Coughed up and swallowing -> Adult Warm in GIT -> Egg release -> Egg in stool. +1
i_hate_it_here  Didn't the stem mention that roundwarm larvae were found? I thought Ascaris is diagnosed by bile coated eggs in feces? +1
sexymexican888  I actually think @cassdawg is right. Its strongyloides. They found larvae in the feces (you find eggs in feces with ascaris) you can get pulmonary sx in both. Ascaris is also usually fecal oral transmission so its more likely to come from someone making food with contaminated hands. Strongyloides is transmitted through soil or sand and the larvae penetrate your feet so this makes more sense. +
sexymexican888  You can find this is FA 2020 Pg 159. Also if you look at the table strongyloides is assoc. with pulmonary sx. However I think its both cause according to sketchy micro ascaris presents with respiratory sx +
... cassdawg made a comment on nbme16/block3/q#1 (A 22-year-old man comes to the physician because of...)
submitted by cassdawg(1398)

This question can be answered by a process of elimination approach in my opinion: (FA2020 p638)

  • Because he has testes that formed, he has to have the SRY gene and thus the Y chromosome which eliminates 46,XX and 47,XXX.
  • This is not a normal-looking biopsy and the question asks about a chromosomal abnormality so you can eliminate 46,XY.
  • Mosaic karyotype 45,X/46,XY is associated with Turner's syndrome. These individuals present with female external genetalia and testes undescended or rarely descended into the labia majora. They would not have scrotal testes, and thus this eliminates this answer.

This leaves only 47,XXY which is Kleinfelter's syndrome and is associated with testicular atrophy and extensive fibrosis and hyalinization leading to infertility.

i_hate_it_here  Kleinfelter's = fibrosed testis = decreased leydig and sertoli cells Turner's = fibrosed ovaries = decreased theca and granulosa cells +5
... bingcentipede made a comment on nbme16/block1/q#16 (40 yo woman, gunshot wound to abdomen)
submitted by bingcentipede(305)

Dudes and dudettes, let me tell you how high yield Pathoma Ch. 1-3 are. Dr. Sattar is the freaking man.

Anyway, this is reversible cell injury because of swelling. If the Na/K ATPase is not working, Na is not leaving. Na follows water, so water is getting stuck in the cell, leading to swelling.

Most important is recognizing that it's reversible cell injury - everything else (except PFK lol) is talking about cell death

cassdawg  Love this explanation lol Dr. Sattar for president. FA2020 p207 for anyone who wants more details. +9
the_enigma28  Ribosomal disaggregation (detachment) does occur in reversible cellular injury, but that is not the mechanism of cellular swelling! +4
topgunber  this last comment is extremely important to recognize when asking about reversible injury +1
... bingcentipede made a comment on nbme16/block4/q#26 (42 yo woman, biopsy of suspicious calcifications on mammogram)
submitted by bingcentipede(305)

Grade refers to the differentiation, whereas stage refers to the TNM decriptions

This is high-grade because of the "poorly demarcated... cells growing in sheets" wit a high N:C ratio. Means it's got low differentiation.

This is low-stage because there is NO METASTASIS. Even though there is invasion (and thus, a cancer), M for the TNM is most important.

the_enigma28  Excellent explanation. For additional info, look up at Page 220, FA 2020. +
... zincy7 made a comment on nbme16/block4/q#39 (32 yo man, begins to laugh while eating dinner with friends)
submitted by zincy7(23)
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EHWLI ASLWGNILWO see( nreLlagay clorues omfr Sn)lwgwioal

ue.t..r olavc dfol suleroc htat si eth rapmiry anggaaelpoynhlryr tciteroevp chisamnem to entrpev srtaaipion nirdug lniwaloswg

  • gcoiL = aomrlN n;ocniutf pesvtner ofdo fmor ngiog tnoi acherta tesadin fo ohgsua.pes oYu otdn ntaw to raastpie fodo enhw yuo wslwal,o so oyu lceos uroy istgtlo nda CsV

LMIIEEYATMD TREFA IRNITTOARI e(es nighouCg - garpraahp taobu hte mhceisman of het gu,och setp 3)

..Th.e iltgsot lssoce c(msslue ednrveanit by reercrtun lnglaarey eerv)n and eth lcoav dsrco ttocacrn ot shut hte yar.xln

  • ogLci = EXRFLE to repnvet oartaipsni fo genifor ybdo from inogg frhtrue oitn hear.atc

ELHIW UIGGHOCN see( hoignCug - appaharrg touab the aemsicmnh of h,ugco ptes )5

e..Th. lvoca dsrco erxla nad hte ittlsog pe,nos leregasin ria at over 100

  • cLgio = oT lhep elepx the efrongi body t.ou


(oFmr lwolainwgS kiWi)

Scnei hte uert vcaol fdslo addtuc gdniru teh wolw,asl a etiinf edprio fo naepa lgion(slaww apnea) muts cyienssreal taek pcela ihtw ahce a.oslwlw hneW lgaeritn walgowlnis to raoti,resnpi it ash bnee tateesmodrdn ahtt wgalolniws csuroc omts eftno ugridn itnioa,pxer veen ta fllu inepxitoar a ifne ria tej si rpiedex blrboapy to eralc het ppure lanryx ormf dfoo sarntnem or dqilui. Teh niilcacl aceigincfnsi of sthi ginndfi si hatt nattpesi with a bsaienel of rmodmcpeosi nugl ictufnon wll,i vero a rpdeoi of time, edepovl apreitsyorr ssserdti sa a leam essgopersr

... ehT aorrerysipt enretc of hte delumal si lrtycdei ebiiihtnd by the slgnwaoilw etrenc rfo eht vyre frbei meti htat ti kstae ot iThs emsan atht it si lirfeby elpoibmsis ot heratbe ugirnd tish haspe of aiolwslgnw dan eht memnot ewehr bnethiagr is erptevden is wnnko as idtnlogtieu

alimd  Well he was eating and laughing at the same time, so it makes sense that his vocal cords were opened during swallowing, right?! +
meryen13  @alimd well i thought the same but remember its asking while swallowing not while chewing and laughing. I have to remind myself to don't overthink and answer what exactly they're looking for. sometimes they give you all these random info and they ask about something else... same as this q. +2
chaosawaits  The part that confused me was "immediately after laryngeal irritation." I essentially narrowed it down to that and then went with the 50:50 choice that seemed most reasonable. I still have no idea how you're supposed to know that. +
chaosawaits  Oh, I think I finally got it. You get the irritation, which makes you want to cough. Epiglottis closes to build pressure. While coughing, the epiglottis opens and the epiglottis closes during swallowing because the body doesn't like storing food in the lungs. +
... bingcentipede made a comment on nbme16/block1/q#25 (A 54-year-old woman is admitted to the hospital with...)
submitted by bingcentipede(305)

FA 2019, P. 304:

2-7 days following an MI, there can be a papillary muscle rupture, leading to mitral regurgitation. Thus the murmur in the answer, specifically the description of holosystolic and cardiac apex

baja_blast  A) describes Aortic Regurgitation. B) describes Mitral stenosis. C) describes Aortic stenosis. D) describes a PDA. +1
beto  Can be VSD rupture too +1
sexymexican888  ALSO remember that this is probably due to posteromedial papillary muscle because it only has 1 blood supply (PDA from RCA if right dominant, from LCX if left dominant) while the anterolateral papillary muscle has dual blood supply. This of course is in the left ventricle -> papillary muscle rupture -> mitral regurgitation +1
chaosawaits  At risk of sounding like a complete moron, why isn't A pulmonary regurgitation, B tricuspid stenosis, C pulmonary stenosis, D PDA, and E VSD? +
chaosawaits  Rephrase: why isn't A) aortic or pulmonary regurg, B) mitral stenosis, C) pulmonary stenosis, D) PDA, and E) VSD +
... cassdawg made a comment on nbme16/block1/q#5 (Poliovirus mRNA lacks a 5' m7G cap but is translated...)
submitted by cassdawg(1398)

In eukaryotes, the 5' methylguanosine (m7G) cap is important in the initiation of translation because eukaryotic initiation factors (eIFs) identify the cap and help assemble the ribosome at that site (FA2020 p45).

The absence of a 5' m7G cap would thus require a different sequence to allow translation initiation and ribosomal entry (i.e. an internal ribosomal entry site).

The 5' and 3' untranslated regions are more important in regulation of translation and termination of translation, respectively, and their absence would not aid translation of the viral mRNA. The 3' poly-A tail is important for protection of eukaryotic mRNA from degradation and aiding in exportation from the nucleus; its absence would not aid translation. A very short open reading frame would not make a significant difference in ability to be translated (the open reading frame is the part of the mRNA able to be translated).

... bingcentipede made a comment on nbme16/block1/q#24 (79 yo woman, right hip fracture after falling)
submitted by bingcentipede(305)

You want something that improves her osteoporosis, which is usually weight-bearing exercise. So avoid the swimming one, because that's just decreased gravity. The best answer is walking outside every day that could strengthen her over time.

ezzo  I overthought this and figured that the long walk would just make her fall and break her other hip UGH +20
jsanmiguel415  I only got it because I did the opposite - assumed that going to a wet pool could cause her to slip and fall +6
... andro made a comment on nbme16/block1/q#37 (54 yo man, aneurysm of distal abdominal aorta)
submitted by andro(213)

Flow rate ( Q) = V * A
V- velocity A - cross sectional area

Our velocity is given as 20cm/sec Convert this to cm/min 20cm/sec * 60seconds = 1200cm/min

Plugging in this value into our equation for flow rate we get 1200cm/min * 2 square cm = 2400 cubic cm /min

Note : 1000 cubic cm = 1 L and therefore we can convert our answer to L/min which are the required units by dividing by 1000

= 2.4 L/min

... bingcentipede made a comment on nbme16/block3/q#25 (27 yo nulligravid woman, 2 years inability to conceive)
submitted by bingcentipede(305)

Clomiphene is a SERM that antagonizes estrogen receptors in the hypothalamus.

If estrogen is antagonized there, there is decreased negative feedback to improve FSH and LH release to stimulate ovulation. This is very important in PCOS and other disorders with decreased fertility.

notyasupreme  I guess I wasn't sure because it said FSH and LH levels were normal, so I assumed the problem was with progesterone. But I thought too deep into it and should've just went with my gut. +1
feochromocytoma  Clopmiphene is usually the answer for infertility with NORMAL anatomy and NORMAL appearing labs +2
drdoom  very nice +
cheesetouch  FA18 p 637 +
sexymexican888  Yeah I made the same mistake by choosing progesterone BUT they are used for contraception (pill, IUD etc) and for the PROGESTIN challenge EXCLUDES (if +withdrawl bleed its hormonal PCOS etc) uterine bleeding due to anatomic defects (which will have no withdrawal bleeding i.e asherman) so as far I know its not used as fertility treatment +
... bingcentipede made a comment on nbme16/block4/q#32 (70 yo woman, persistent fever despite intravenous broad-spectrum antibiotic therapy)
submitted by bingcentipede(305)

Ugh this question. The Gram stain and purple made me thing Staph aureus, but it also mentions "budding" and "elliptical" (SA is a coccus). Additionally, SA is not a common UTI infection while Candida is.

Annoying because of the Gram stain and purple descriptor.

From quora: "when decolourizer is added, the crystal violet taken up by yeast cells is retained."

melanoma  Also we can recognize Staph aureus for the beta hemolysis in a blood agar +1
... cassdawg made a comment on nbme16/block2/q#32 (A 35-year-old woman is given 500 mg of drug X...)
submitted by cassdawg(1398)

First order elimination: a constant FRACTION of drug is metabolized per unit time (i.e. elimination rate is proportional to the drug concentration)

This differs from zero order elimination where a constant amount of drug is metabolized per unit time (i.e. rate stays constant)

In this question:

  • In two hours, 2.5 mg of 12.5 mg is metabolized, which is a fraction of 2.5/12.5 = 0.2 or 20%
  • Thus, in another two hours, another 20% will be metabolized since this is first-order elimination
  • 20% of 10 is 2 and 10-2 = 8

FA2020 p232

m0niagui  how will it work if this followed a zero order elimination? +
drdoom  @m0niagui Zero-order would like like this: 12.5mgβ€”10mgβ€”7.5mgβ€”5mgβ€”2.5mgβ€”0mg (this assumes 2.5mg is eliminated per unit time) +3
... daddyyikes made a comment on nbme16/block1/q#48 (12 yo boy, 6 months difficulty walking and leg pain)
submitted by daddyyikes(1)
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it si cchtrao ierma ootht esaidse as ti si ihdntiere dna hwti oanarbml mleiny tsaheh, toof dpor, rmmeha toe tce.

cheesetouch  fa18 p 508 +2
... bingcentipede made a comment on nbme16/block1/q#49 (In an experiment, glycolytic intermediates are measured in human endothelial cells)
submitted by bingcentipede(305)

First, notice that there's a drop in concentration after glyceraldehdye 3-phosphate to 1,3-bisphosphoglycerate. Thus, the conversion is impaired here.

Next, it's somehow remembering which freaking enzyme is involved. Which is glyceraldehyde-3-phosphate dehydrogenase in the glycolytic pathway. This is one where if you know the substrate name you know the enzyme name.

... ace9yak made a comment on nbme16/block2/q#18 (Animal study conducted to assess the effects of smoking on pulmonary defense)
submitted by ace9yak(7)

fa 2019 pg 662, Inhalation injury and sequelae. in the inhalation injury and sequelae part they say signed nasal hairs or soot in the oropharynx -> decreased activity of airway cilia as there is soot overlying them and cant function properly tobacco has silica (fa 2019 pg 663) - silica can disrupt phagolysosomes and impair macrophages -> decreased alveolar macrophage function as for the increased mucus production and secretion - idk i figured there is an irritant and your body will be trying to clear it some how, i guess think about COPD

meryen13  i was so confused by the "1 week" i was thinking is one week enough to decrease the macrophages? or are they gonna be hyper active to clean the smoke particles. smh +6
shieldmaiden  Acute cigarette smoking "behaves" differently than chronic. While acutely you would see decreased number and function (phagocytic and proinflammatory) of alveolar macrophages (AM), chronic smokers have shown an increased number of AMs, likely as an adaptive mechanism to offset the epithelial changes. +1
... bingcentipede made a comment on nbme16/block3/q#7 (15 yo girl, brought to ER 12 hours after ingesting 100 capsule vitamin D in suicide attempt)
submitted by bingcentipede(305)

Her calcium is only a little higher than normal (upper limit 10.2) due to the excess vitamin D supplements she took. According to FA '19 (p. 70), activated vitamin D:

-Increases intestinal absorption of calcium and phosphorus --This is what increase her calcium concentration in the serum -Increases bone mineralization (lower levels) -Increases bone resorption (higher levels)

bboucher  But what's the all point of talking about coming back one month later after she took the pills? +
... bingcentipede made a comment on nbme16/block3/q#17 (Gram stain performed on sputum specimen)
submitted by bingcentipede(305)

Pink rods is describing a Gram negative bacteria, which has two membranes an outer membrane and an inner membrane (whereas Gram positives have just one thicc membrane).

Both Gram + and - bacteria have an ER, can be inhibited fluoroquinolones (though negatives > positives), both have the peptidoglycan wall (positives thicker than negatives), and either can have polysaccharide capsules.

deathcap4qt  FA2019 pg 124 +1
... medstudent made a comment on nbme16/block4/q#8 (24 yo woman, follow-up examination; 8 years of seizure disorder refractory to treatment)
submitted by medstudent(15)

FA 2020 p. 525.

Ash-leaf spots are pretty pathognomonic for TSC. The subependymal nodules add further support for TSC

bingcentipede  Other symptoms of TSC: "Hamartomas in CNS and skin, Angiofibromas C , Mitral regurgitation, Ash-leaf spots D , cardiac Rhabdomyoma, (Tuberous sclerosis), autosomal dOminant; Mental retardation (intellectual disability), renal Angiomyolipoma E , Seizures, Shagreen patches." Most important is the seizure disorder and the ash-leaf spots, like you said +
bingcentipede  Other symptoms of TSC: "Hamartomas in CNS and skin, Angiofibromas C , Mitral regurgitation, Ash-leaf spots D , cardiac Rhabdomyoma, (Tuberous sclerosis), autosomal dOminant; Mental retardation (intellectual disability), renal Angiomyolipoma E , Seizures, Shagreen patches." Most important is the seizure disorder and the ash-leaf spots, like you said +
... maxillarythirdmolar made a comment on nbme16/block4/q#11 (78 yo man, 1 month fever, chills, fatigue, 5.4 kg weight loss)
submitted by maxillarythirdmolar(40)
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ouY udhlos be nhignikt fo ngihsmteo liek ccn.uestEcoro yTeh hda a UG rocreuepd adn etnuuqsesb accardi iessu.s

Wehn I hare tofs 1S, i hnikt ttah eht paenitt msut evah had a isseu twhi het csgioln fo ihreet eht rialmt or ciidurpst leav.vs linPgya d,dso hsti osdlhu be hte liatmr .avlve oYu saol hree an aryel soditalci umumr,r so oyu mtigh be ikgnnhit lemouv oldoearv S3).(

baja_blast  You're almost certainly right that it's mitral valve endocarditis. The murmur is accentuated by Expiration, consistent with lEft-sided murmurs. On the other hand, rIght-sided murmurs are accentuated by Inspiration. Note the capital letters for a handy trick. God Bless Dr. Jason Ryan. +8
rahmanu  But the murmur is auscultated at the 2nd left intercostal space, isn't that aortic regurgitation (vulvular)? still a left sided murmur yes. +1
mkayman  @rahmanu aortic valve regurgitation would be heard on the 2nd RIGHT intercostal space. +
chaosawaits  Actually, an AR is best heard at the third intercostal space on the left side. Be mindful when they want to get tricky! +
... feliperamirez made a comment on nbme16/block4/q#32 (70 yo woman, persistent fever despite intravenous broad-spectrum antibiotic therapy)
submitted by feliperamirez(31)
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nlgIwdlein IV tshcetrae si a onmcom easuc of imatisdeneds iidcdniasas adn ti si ude to dncaereeh of the setay ot teh a.retthecs

ebmmrRee that dmsteneaidsi cfinnoeti amy salo setlur in pattesni twhi tnunaoirpee

CMI ytsdniocufn ,IAD(S C)ISD orpessipesd to encoumusotcau NOT enietsimadds ninfoecsit

... notyasupreme made a comment on nbme16/block1/q#21 (A 50-year-old man comes to the physician because of...)
submitted by notyasupreme(35)

Just wondering if someone could explain the difference between collagen and elastin for this one? I thought either or could be used for tensile strength. Anyone have clarification, don't know why collagen is the best answer!

notyasupreme  Lol, never mind I realize, it's a scar and that's type III collagen! +6
meryen13  type III is whats usually present but then it gets replaced by collagen I in the scar tissue to add more strength. +1
i_hate_it_here  It is also the disulfide bonds that add to tensile strength of collagen, while the inter-chain fibril cross-linking that leads to elastins elasticity FA2020 pg: 51&52 +
xw1984  I think the Q emphasized postoperatiive. Maybe the production of elastin does not increase much comparing to collagen. +
topgunber  i think they would refer to elastin in cases of arteriolar compliance +
... barbados made a comment on nbme16/block1/q#31 (A healthy 24-year-old woman participates in a study...)
submitted by barbados(6)

Did anyone else feel like the question should have been more specific as in saying "just before the consumption of a meal"? As in saying she has high ghrelin = high hunger just before she eats so point B?

lee280  I agree, at the start, I got a bit confused because I felt like the question was probably less specific than it would have been, but NBME being NBME this is really expected. When you think about it more closely, once you consume the meal then ghrelin will peak and start dropping. +18
notyasupreme  I agree, I had B at first but then thought too deep into it. I thought if she ATE a meal, she'd be full and low ghrelin. Annoying to get a question wrong on something so simple. +1
radzio1  Also got this question wrong. A really bad explanation what they want from the curve... +1
shieldmaiden  Basically she is eating at peak ghrelin (B) its drops, then she likely eats a snack on E +
bboucher  They ask what point ''represent the consumption of a meal'' by mean there is no reason you're ghrelin would start dropping before you even started eating (point C which is I guess the other you might have guess) in contrast to B where it follows a natural physiologic cycle where it increase because you get hungry --> You eat because you're hungry --> Abdominal distention due to the food start decreasing ghrelin. +
ali_hassan  I get it now, but when I was doing the test it made absolutely no sense, I was stuck between B - C - D. Word your questions better NBME! +
chaosawaits  I'm reading the question now and I still think "the consumption of a meal" means that the meal has been consumed. I feel like this is really a black & blue dress and once again, I'm not in on the joke. +
chaosawaits  I think the question is actually worded properly because of the lag before ghrelin is released. As you consume the meal, ghrelin release slows down, such that the peak arises by the end of the meal. Therefore B is the right choice because at the end of consumption of the meal is the peak of amount of ghrelin. It's not like as soon as you take a bite of cream of wheat, the ghrelin levels immediately shoot down. Maybe? +
... the_enigma28 made a comment on nbme16/block3/q#10 (A 76-year-old man with a 1-month history of a pulsatile )
submitted by the_enigma28(55)

Copied from NBME 22 for completeness sake:

"A good pic showing anomalous arteries in horseshoe kidney"

chaosawaits  What is "friability of vascular tissue as a result of collagen synthesis abnormalities" referencing? +
chaosawaits  Nevermind, I'm a dumbass: Ehlers-Danlos syndrome +
... cassdawg made a comment on nbme16/block3/q#27 (Two days after admission to the hospital because of...)
submitted by cassdawg(1398)

Renal papillary necrosis is a common complication of sickle cell disease which would cause gross hematuria (FA2020 p602, p422).

Glomerulonephritis would be associated with RBC casts rather than gross hematuria (casts are present if they are released from the glomerulus or tubules). Nephrolithiasis (kidney stones) are not associated with sickle cell and would likely be associated with crystals of some sort on urinalysis. Prostatitis would likely present with more WBCs and does not commonly present with hematuria but rather urgency and dysuria. Transitional cell carcinoma is rare in the kidney and transitional cell carcinoma of the bladder is associated painless hematuria.

... cassdawg made a comment on nbme16/block3/q#49 (A 25-year-old man is brought to the emergency...)
submitted by cassdawg(1398)

Peutz-Jeghers syndrome is an autosomal dominant syndrome associated with hyperpigmented macules on the mouth, lips, hands, and genetalia as well as increased risk of breast and GI cancers. [FA2020 p387]

This patient presents with the characteristic hyperpigmented macules as well as positive occult blood test which could be indicative of an underlying GI malignancy. Peutz-Jeghers is also associated with numerous hamartomas throughout the GI tract which could be associated with the patient's general GI symptoms due to their ability to cause blockage.

Other answers:

  • Cowden disease - multiple hamartoma syndrome that increases risk of breast, thyroid, uterine, and other cancers; it is not associated with the hyperpigmented macules
  • Gardner syndrome - familial adenomatous polyposis + osseous and soft tissue tumors
  • Muir-Torre syndrome - rare hereditary autosomal dominant cancer syndrome thought to be a subtype of HNPCC (Lynch syndrome)
  • Neurofibromatosis - not associated with GI issues and typically have a very different presentation (FA2020 p525) - NF1 = cafe-au-lait spots, lisch nodules, pheochromocytoma, seizures, cutaneous neurofibromas, etc.; NF2 = bilateral vestibular schwannomas, juvenille cateracts, meningiomas, ependymomas
cheesetouch  FA18 p 381. Great answer cassdawg! +
... cassdawg made a comment on nbme16/block1/q#38 (A 58-year-old African American man with congestive...)
submitted by cassdawg(1398)

Sildenafil is a PDE5 inhibitor that runs the risk of causing hypotension in patients on nitrates due to the synergy of the mechanisms of action. [FA2020 p246]

Nitrates, like nitroglycerin, work by increasing NO production which in turn acts to increase cGMP in smooth muscle causing vasodilation. PDE5 inhibitors act by decreasing the breakdown of cGMP in smooth muscle, enhancing the action of NO to cause vasodilation. Thus, when combined there can be systemic vasodilation that leads to dangerous hypotension.

lee280  For some reason, I had two answers that I felt like both made absolute sense to me. As explained above, that totally came to my mind and I knew this was the case. When I thought about Metoprolol blocking B1 receptors in a patient with an ejection fraction of only 30%, I was thinking this could as well be a contraindication, not sure if it's an absolute one or relative. Now, am I right if I said that Beta-blockers are only contraindicated in acute decompensated HF? and can be used unless otherwise? Someone, please help me clarify this, so then this distinction can come clean in my thoughts. Thanks +2
notyasupreme  I thought the same thing as you, I think we're just overthinking the most important thing - never give antihypertensive with Viagra lmfao. I totally thought too deep into it. +4
topgunber  sildenafil does make sense, especially since hes on 2 vasodilators. I picked diltiazem because the pt has systolic heart failure. thought it was contra indicated to give CCB to systolic heart failure because you could further decrease contractility. Either way never give NTG and viagra +1
sexymexican888  Yeah @topgunber I also picked diltiazem.... I guess they were looking for "COMBINATION" rather than a specific contraindication +
pakimd  @lee280 you are right in saying that beta blockers are only contraindicated in acute decompensated heart failure. this is because beta blockers, which would normally prevent the deleterious effects of neurohormones like norepinephrine on cardiac remodeling that occurs in HFrEF, will further impair cardiac output in decompensation. hope this helps :) +1
... privatejoker made a comment on nbme16/block2/q#18 (Animal study conducted to assess the effects of smoking on pulmonary defense)
submitted by privatejoker(47)
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anC yaneon npexial hyw ogrecmahpa iacyvitt uldwo be aerecesdd ni th?si I twnade ot ikcp oen atht ahd othb cmuus esicnertg vtaticyi as iengb deanrscei gaoln twhi deicnsrae gpomareahc ititcyva thiw incmaoocntt eedasrec in alrciiy tctayivi utb stih w'tasn na npotio so I nwte htiw all eie.dcrnsa iSecn it's atlheeeli-slbwds ttha psomharaceg ueacs egdama in ypsmemeah peelsl(aicy in srkoems edu to tsontnca iaritnitor form hte m)eks,o how is ti peblssoi ttha raghompeca taiivcty lowud go ?WNDO

kard  Mucus hypersecretion --> Induce airflow limitation in COPD "potential risk factor for accelerated decline in lung function" Cigarette smoke impairs both the phagocytic and respiratory burst function of neutrophils! Macrophages-->activated by cigarette smoke extract to release inflammatory mediators COPD--> alveolar macrophages and neutrophils are defective in their antimicrobial functions. Macrophages from COPD patients--> show reduced phagocytic uptake of bacteria. "Streptococcus pneumoniae and nontypeable Haemophilus influenzae" I Hope This Helps... +24
... itsalwayslupus made a comment on nbme16/block3/q#20 (Investigator studying strains of Streptococcus pneumoniae)
submitted by itsalwayslupus(37)

Natural transformation is when bacteria take up naked bacterial chromosomal DNA in their environment (usually from cell lysis). A cell "lysate" is what remains of bacterial genes when the bacteria is dead (can be extracted from bacteria, as shown here). The SHiN bugs all can undergo transformation. You know it is transformation even without knowing which bugs can do so because it doesn't take up the DNA when DNase is added (it kills any free environmental DNA in the lysate)

topgunber  just wondering why is plasmid transfer not a good option??? +1
m0niagui  Transduction requires the presence of a bacteriophage virus. Plasmid transfer requires two different live bacteria, point mutations will not occur across colonies so uniformly and neither will strand mispairing. +1
shakakaka  @topgunber I think DNase wouldn't stop the process in case of plasmids +4
topgunber  you're right in that DNAse wouldn't be able plasmids in living cells because they are inside the bacteria (same with their nuclear dna). Since living cells use sex pilli to transfer plasmids yes, DNAse wouldn't stop plasmid transfer. Key there is they had to be living. I do think a dnase can break down a plasmid in extracellular solution though (its just another piece of dna). +
... bingcentipede made a comment on nbme16/block1/q#43 (A 15-year-old boy is brought to the physician for an...)
submitted by bingcentipede(305)

This is a case of Marfan syndrome. This is a tall kid (6'3", does well on Tinder). Leads to a FBN1 gene mutation, affecting fibrillin protein.

... cassdawg made a comment on nbme16/block2/q#12 (Two sets of patients (Groups X and Y) of similar...)
submitted by cassdawg(1398)

The blood:gas partition coefficient is the ratio of concentration of anesthetic in the blood vs. in the lungs when a steady state is reached. Blood/gas partition coefficient is an expression of solubility of the drug in plasma, and less soluble agents have a faster onset/offset.

MAC (minimum alveolar concentration) is the concentration of anesthetic in the lungs where 50% of the population does not move in response to a surgical srtandard stimulus. It is analogous to ED50 in other areas of pharmacology. MAC is increased with decreasing solubility (decreaseing blood/gas partition coefficients) and decreased potency. If you think about it this would make sense because if a drug is less soluble or not as potent, you have to administer more of the drug and thus would have to have a higher minimal alveolar concentration to see an effect. [FA2020 p549]

NOTE: MAC is additive so if you mix two gases at 0.75% of their MACs, you get a total 1.5% MAC. Thus for the question, you are essentially administering the same TOTAL MAC to each group, so it is not the difference in MAC that is causing the difference observed.

The brain:gas partition coefficient, more commonly called the oil:gas partition coefficient, is used as a surrogate for the amount of anesthetic in the brain and corresponds to lipid solubility. CNS drugs must be lipid soluble or actively transported. As these are inhlaed anesthetics, the lipid solubility actually does not greatly contribute to time of onset/offset; instead the plasma solubility is the limiting factor. Oil/gas partition coefficient would be associated with the drug potency.

... cassdawg made a comment on nbme16/block2/q#46 (A 9-month-old boy is brought to the emergency...)
submitted by cassdawg(1398)

Neural crest cells migrate to form the aorticopulmonary septum and abnormalities associated with neural crest migration in the heart include tetrology of fallot, transposition of the great arteries, and persistent truncus arteriosus. Fusion of the aorticopulmonary septum with the muscular ventricular septum is what forms the membranous septum, so patients with a persistent truncus arteriosus will have VSD as well. (FA2020 p280)

i_hate_it_here  Neural Crest derivatives: Melanocytes Odontoblasts Tracheal cartilage Enterochromaffin cells Leptomeningies (pia & arachnoid) PNS Adrenal medulla Schwaun cells S aorticopulmonary Septum Endocardial cushions (defects resulting in asd & vsd) Skull bones FA2020 pg 613 +
i_hate_it_here  MOTEL PASSES +3
cheesetouch  fa18 p 298 Persistent truncus arteriosus +
... andro made a comment on nbme16/block1/q#2 (18 month old boy, 3 hours lethargy, poor eating for past 24 hours)
submitted by andro(213)

Fatty Acid degradation
-Occurs in mitochondria or peroxisomes

First step - uptake of the fatty acids by the cell and addition of CoA to them

Second step - Uptake of the Fatty Acyl CoA molecule into the mitochondria by the Carnitine Shuttle *( which involves removal and then addition of the CoA molecule again to the fatty acid once inside the mitochondria)

Once in the mitochondria the fatty acid may undergo , Beta-oxidation ( a process in which a fatty acid is oxidized/cleaved at the Beta carbon to generate Acetyl CoA in several cycles )

An Acyl CoA dehydrogenase catalyzes the initial step .
Look out for Hypoketotic Hypoglycemia in defects of fatty acid degradation

The 2 main subtypes to be aware of are -a problem with the carnitine shuttle ( systemic carnitine deficiency) - or with an Acyl CoA dehydrogenase ( eg MCAD deficiency )

notyasupreme  It's actually funny because the question stem makes it seem like it's an MCAD deficiency (presence of dicarboxylic acid) and all the symptoms, but then treat it with MCAD. Whatever, I got it right but it just felt like a weird question to me. +3
nbmeanswersownersucks  yeah I was confused too but I also think the negative serum carnitine is supposed to help r/o MCAD deficiency since that usually has elevated serum carnitine. +
baja_blast  If Carnitine was an option here, how could we differentiate this from primary carnitine deficiency? Would it have been possible? +9
melanoma  the presence of dicarboxylic aciduria is more related to mcad/lcad deficiency. the patient receives medium chain tryglicerides because he has the enzyme to metabolize it. +6
melanoma  but no for the long chain +
topgunber  just a few things, sure it sounds like mcad but lcad would present similarly, except in MCAD, giving medium chain triglycerides would worsen symptoms as compared with LCAD. + Similarly when fatty acids cant undergo Beta oxidation they undergo omega oxidation- which is why there is increased dicarboxlic acids (i.e. dont just jump for MCAD when you see dicarboxilic acids). Last of all it would be difficult to differentiate but if the patient were deficient in carnitine the treatment with MCADs would not show improvement because carnitine is required to shuttle the fatty acid into the MTs. +2
topgunber  'a 'weird question' because my school never asked it' +1
sexymexican888  According to UWORLD: Primary carnitine deficiency elevated muscle triglycerides. MCAD, will not +2
... andro made a comment on nbme16/block1/q#7 (2 yo boy, increased thirst, urinary frequency, failure to thrive)
submitted by andro(213)

Fanconi Syndrome
Impaired reabsorption of Bicarbonate and other compounds in the Proximal convoluted Tubules ( eg amino acids , glucose phosphate )

Clinical Features : Vitamin D resistant Hypophosphatemic Rickets/osteomalacia

Fanconi syndrome presents with proximal Renal Tubular Acidosis ( normal anion gap metabolic acidosis )

... bingcentipede made a comment on nbme16/block1/q#17 (Investigator studying pulmonary lymphatic flow using animal model)
submitted by bingcentipede(305)

IV normal saline will increase hydrostatic pressure in the vasculature. This isotonic solution is freely filtered across the capillaries, which is collected by lymphatics and can be picked up in this experiment.

motherhen  Why does albumin solution not have this effect? +3
notyasupreme  I think it's because albumin in saline is hypertonic, which would cause the opposite effect of what the experiment was going for. Fluid would go across the capillaries into the vasculature, rather than vice versa. +3
... hungrybox made a comment on nbme16/block2/q#24 (85 yo woman, fracture of the right femur, begins treatment with morphine)
submitted by hungrybox(1113)

Morphine stimulates mu opioid receptors to provide the desired effect of analgesia, but in doing so can also precipitate many undesired effects.Β  This patient has multiple signs of opioid toxicity, including miosis (ie, pinpoint pupils), respiratory depression (evidenced by slow respiratory rate and respiratory acidosis), and CNS depression (eg, somnolence, coma).Β  Morphine is primarily metabolized by the liver via glucuronidation to form 2 major metabolites.Β  These metabolites, morphine-3-glucoronide and morphine-6-glucoronide, then undergo renal elimination via excretion in the urine.Β  Because the metabolites are metabolically active, renal dysfunction can lead to metabolite accumulation and opioid toxicity.Β  Morphine-6-glucoronide is particularly responsible for toxicity, acting as a more potent mu opioid receptor agonist than morphine itself.

Due to its metabolically active and renally cleared metabolites, morphine requires careful monitoring when used in patients with renal dysfunction.Β  When opioid pain control is needed in such patients, fentanyl or hydromorphone is often preferred as these drugs are predominantly hepatically cleared.

Source: UW18563

helppls  What drugs inhibit their own metabolism? +
letitb  Carbamazepine i think ^ +
... bingcentipede made a comment on nbme16/block2/q#49 (An experimental study of oxygen consumption in kidney)
submitted by bingcentipede(305)

The two sections of the nephron most susceptible to hypoxic conditions are the 1) proximal convoluted tubule and the 2) mTAL (medullary section of the thick ascending loop of Henle)

cassdawg  FA2020 p210 has the regions of specific organs most susceptible to hypoxic injury +4
biochemgirl22  Im thinking this is because the PCT does the most work as far as reabsorbing stuff, so probably needs the most ATP for those pumps. +3
... bingcentipede made a comment on nbme16/block3/q#3 (83 yo man, 3 days painful blisters on torso)
submitted by bingcentipede(305)

The stem is describing bullous pemphigoid, which produces IgG antibodies hemidesmosomes. (PV is IgG antibodies aginst desmoglein-1 and desmoglein-3, in the oral mucosa).

BP produces the tense blisters that have a negative Nikolsky sign (don't rupture with rubbing). This is because they're supepidermal. Surprised they didn't ask about hemidesmosomes, but I think that that the BP antigen is part of the hemidesmosomes and recruits the autoantibodies.

i_hate_it_here  New stem was describing Bullous pemphigoid, just never heard of BP antigen lol +2
taylor5479  Same here. I have literally never heard of "bullous pemphigoid antigen" lol +
chaosawaits  FA2019 page 465: it talks about "bullous pemphigoid antibodies." Antibodies have antigens. Plus, desmoplakin and plakoglobin are components of desmosomes, which is pemphigus vulgaris. I also almost got torn away by BP antigen though. +
... bingcentipede made a comment on nbme16/block3/q#39 (27 yo woman, concerned of sleep apnea)
submitted by bingcentipede(305)

The answer is reassurance because this is all normal behavior. She's only snored TWICE in the past year w/ no daytime sleepiness or other problems.

It wouldn't be a sleep journal because it could imply that something is wrong, but there isn't. She's 27 and if anything she should upgrade from her husband complaining about nothing important.

... bingcentipede made a comment on nbme16/block3/q#40 (Female newborn delivered at term to 35 yo primigravid woman)
submitted by bingcentipede(305)

IgG antibodies can cross the placenta, leading to thyroid enlargement. This can also explain the stridor and issues with respiration in the newborn. Essentially, this is causing neonatal Graves disease.

From UpToDate: "Neonatal Graves disease refers to the hyperthyroidism that is seen in a small percentage of infants born to mothers with Graves disease. Although neonatal Graves disease is usually self-limited, it can be severe, even life-threatening, and have deleterious effects on neural development"

nbmeanswersownersucks  Was anyone else thrown off because the neck mass was asymmetric and graves usually causes diffuse enlargement of the thyroid? +5
victorlt14  omg yes +
... bingcentipede made a comment on nbme16/block4/q#35 (51 yo woman, 6 months burning abdominal pain one to two hours after eating)
submitted by bingcentipede(305)

Good explanation on reddit:

Essentially, A = mucinous glands (foamy cytoplasm) B = parietal cells (stain eosinophilc, P ar I etal cells stain PInk w/ a fried egg appearance. Additionally, they're above chief cells C = chief cells (stain basophilic, super dark, and below parietal cells)

md_caffeiner  reddit: Its not about histology knowledge, you just need to know two things about parietal cells - they are eosinophilic on histo and they are located more superficially compared to chief cells (super basophilic, labeled as C). If you know chief cells are C, mucinous glands are A due to the foamy cytoplasm, the answer has to be B. +
md_caffeiner  reddit2#You're exactly right (although I would say it is histology knowledge). Gastrin stimulates both parietal and chief cells but only parietal cells release hydrogen ions (and chloride ions - to make HCl). ArtiomK is right about the staining and location of parietal cells being highly acidophilic (pink) and predominantly at the apical part of the gastric gland - they're often described as having a fried egg type of appearance (big, round cytoplasm [egg white] with a central, round [yolk] nucleus). Chief cells produce pepsinogen (enzyme) so display the basal basophilic (purple) staining and they're found predominantly at the base of the gastric gland. So, it's a mix of theory and practical understanding - knowing the structure and function of the gastric gland and then the practical histology of the gland (and its cellular composition). +1
md_caffeiner  dont go to reddit and get distracted for 15 minutes lol +11
deberawr  it's better than redownloading tiktok and getting distracted for 3 hours lol (don't do what i did its embarrassing) +
... cassdawg made a comment on nbme16/block1/q#13 (A 30-year-old woman with Li-Fraumeni syndrome is...)
submitted by cassdawg(1398)

Li Fraumeni syndrome is associated with a loss of function mutation in p53 (FA2020 p224, p46)

p53 is a modulator at the G1/S restriction point. p53 activation in the presence of DNA damage, misfolded protein, and hypoxia leads to activation of BAK/BAX and subsequent activation of the apoptotic pathway (p208). Thus, loss of function of p53 will lead to impaired regulation of apoptosis and uninhibited cell division in cancer cells.

Li Fraumeni syndrome is associated with multiple tumors at a young age (SBLA - sarcoma, breast, leukemia, adrenal)

cassdawg  ALSO REMEMBER: since it is a loss of function mutation that leads to cancer, p53 is a tumor suppressor gene NOT an oncogene. +5
... cassdawg made a comment on nbme16/block1/q#14 (A 30-year-old man develops hemoptysis, dyspnea,...)
submitted by cassdawg(1398)

This is goodpasture syndrome which has antibodies directed against alveolar and glomerular basement membranes (FA2020 p596)

The key hints are:

  • Lung involvement
  • Crescent formation (indicating rapidly progressive "crescentic" glomerulonephritis)
  • "Linear" deposits of IgG and C3 - this is characteristic of Goodpasture because the antibodies are to the glomerular basement membrane so they deposit all along the glomerulus basement membrane leading to linear immunofluorescence.
  • Remember that the other main lung/kidney combination, granulomatosis with polyangiitis, is Pauci immune with no immunofluorescence and they will usually mention ANCA
sexymexican888  Microscopic polyangitis also presents with lung/kidney problems except theres no nasopharyngeal involvement and also churg strauss but that presents w asthma and both are P-ANCA positive vs C-ANCA for granulomatosis for polyangitis (weCner's granulomatosis) +
... cassdawg made a comment on nbme16/block1/q#30 (A 1400-g (3-lb 2-oz) female newborn is delivered to...)
submitted by cassdawg(1398)

A continuous, machine-like murmur is characteristic of a patent ductus arteriosus (FA2020 p291, p298)

The patency of the ductus arteriosus is maintained by prostaglandins (hence why newborns who need to keep a patent ductus arteriosus due to other heart defects are put on prostaglandin drips).

In this newborn's case, the patent ductus arteriosus is not necessary (there are no signs of additional heart defect that would necessiate it) and thus we want to close it.

To close a PDA, we would want to inhibit prostaglandins somehow, and cyclooxygenase inhibitors (NSAIDs) inhibit the production of prostaglandins and thus would speed up closure of the ductus arteriosus. IV indomethacin or ibuprofen are most commonly used to close the PDA.

Though inhibition of phospholipase A2 by corticosteroids would also serve to inhibit production of prostaglandins, this is more nonspecific and could be associated with more unwanted side effects. Coritcosteroids in a newborn are more often used for neonatal respiratory distress syndrome to elicit production of surfactant.