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Comments ...

 +2  (nbme17#2)

The patient is clearly showing that he understands the procedure (information) and that he's willing to go through with the procedure (voluntariness).

The 2nd choice should be capacity because competence is the legally declared one (from a court). Honestly bad ? because of this.

But, family agreement (which technically wasn't achieved yet) and cost are not necessary factors for informed consent.

According to FA '19 p. 264, you need: disclosure, understanding, capacity, and voluntariness.

j44n  tf are you downvoting this for? +2

 +2  (nbme17#36)

Although they had statistical significance with a p=0.001, it doesn't matter to the subjects. They're only falling asleep 5 minutes faster, and are personally not reporting an improvement in quality of life. So, clinically, this medication doesn't matter to the subjects because 5 minutes faster might not be that big of a deal.

It's not attrition bias because the threshold there is 5%. Here, 20/2000 subjects (1%) are lost, having little effect on attrition. Additionally, the acceptable range for bias is between 5-20%, which this doesn't approach. https://catalogofbias.org/biases/attrition-bias/

topgunber  The study has statistical significance. The study has no clinical significance because a) no improvement in QOL and b) 5 minutes faster than people with insomnia. +

 +0  (nbme17#33)

Flipping a coin = randomization. You're also testing a new drug, which is the point of a randomized clinical trial.

j44n  it also cant be case series because they have a control group +

 +0  (nbme17#29)

N= 300 (100 households * 3 per household) If 45 individuals are detected, then prevalence is 45/300 = 0.15 (15%).

Prevalence is the amount at ANY GIVEN POINT IN TIME with the disease.


 +2  (nbme17#44)

Albuterol, a short-acting beta agonist (SABA) is used for immediate relief in asthmatics by activating the B2 receptor and causing bronchodilation.


 +2  (nbme17#33)

For any questions regarding teens, know that peer influence is the strongest factor in influencing behavior.


 +1  (nbme17#48)

Activation of the mu-opioid receptor in the colon can slow gut motility. There are two opioid agonists that can treat diarrhea. The first, loperamide, does not cross the BBB and cannot lead to addiction or CNS adverse effects. The second, diphenoxylate, has some addictive potential by crossing the BBB (thus, you have to give atropine to prevent addiction).


 +1  (nbme17#12)

To slow diabetic nephropathy, you can give an ACE inhibitor (i.e., lisinopril) or an ARB. This would to increased dilation of the efferent arteriole and prevent the hyperfiltration injury caused by diabetic nephropathy.


 +1  (nbme17#42)

Ezetimibe is the dyslipidemia drug that blocks 1st step in cholesteral metabolism - absorption. It prevents cholesterol absorption at small intestine brush border.

Cholestyramine: prevents bile acid reabsorption, forcing new cholesterol synthesis Fibrates (gemfibrozil): activates LPL, PPARa Niacin: inhibits lipolysis Statins (simvastatin): inhibits Hmg-coA reducatse to reduce cholesterol synthesis.


 +1  (nbme17#37)

The patient is presenting with hydronephrosis and a UTI. Remember, patients are prone to UTIs when urine is stagnant, so if there's an obstruction, there's an increased chance of UTI.

Being that it's a boy, there's a chance this is a posterior urethral valve that is obstructing the ureter.

cheesetouch  posterior urethral valve obstructs the ureTHRA, so the bladder would be effected (dilated, thick walled) and I feel like both ureTERs would be blocked. FA18 563. I think he's a bit too old, but hard to know. +2
kbizzitt  Yea posterior urethral valve is typically picked up prenatally on ultrasound. The other finding would be oligohydramnios, so Potter sequence would likely be involved. FA20 579 +

 +2  (nbme17#0)

The key for this being dissecting aneurysm is that it's a widened aortic arch. Also, there's uneven pulses ("diminished pulses in the left upper extremity") meaning that blood is not passing from the aortic arch to the left subclavian artery (it's not passing the aortic arch).

kevintkim4  only thing I would add is the acute nature (30 minutes) and hx of cocaine use helps point towards dissecting aneurysm +

 +1  (nbme17#0)

The patient is coming from South America, where T. cruzi is endemic. This parasite causes Chagas disease, leading to BIG organs: cardiomegaly, mega-colon, mega-esophagus.


 +3  (nbme17#0)

The stem describes a middle-aged woman hitting a lot of the ABCDEs of a melanoma. Assymetry: "irregular" Borders: "ill-defined margins" Color: "variegated black-tan pigmentation" Diameter: "increased size" (though they could also give you >6 mm Evolution over time: "past 6 months"

Additionally, the "pleomorphic, hyperchromatic" cells indicate it's malignant. Invasion into the papillary dermis is also a poor prognostic factor for melanoma.


 +0  (nbme17#0)

A newly admitted elderly patient presents with agitation, fever, and confusion = DELIRIUM. Delirium is the most common disease/disorder in a newly hospitalized patient. Reversible, unlike dementia. Rapid onset, too.


 +0  (nbme17#10)

There are a lot of hints in the stem to suggest ectopic pregnancy:

-Severely increased B-hCG (meaning there is a pregnancy of some type, versus none in normal women) -lower quadrant pain (either side; why appendicitis is on the differential diagnosis if it's right side) (probably the strongest hint here) -Empty uterus on ultrasound -Sudden onset abdominal pain

passplease  ectopic pregnancy presents with a lower-than expected rise in hcg (as seen in this question) +2
passplease  the empty uterus is what helped me differentiate. A molar pregnancy should have an enlarged uterus. +2

 +7  (nbme17#0)

The classic triad of a renal cell carcinoma is: 1) hematuria; 2) flank pain; and 3) a palpable flank mass. The classic RCC comes from a VHL mutation. No VHL means you can't inhibit HIF (hypoxia inducible factor). This leads to uncontrolled activation of VEGF, leading to the hypervascular mass.

cheesetouch  FA2018 P583 +1

 +0  (nbme17#4)

Leptin is released from adipose tissue to induce satiety. It's a popular target in pharma as a possible anti-obesity drug. In obese patients, the increase adipose = increased leptin. They become leptin insensitive, reducing their ability to feel satiety.

Ghrelin, on the other hand, is released by the stomach mucosa in response to food stimulation to induce hunger.


 +4  (nbme17#26)

A premature infant does not have mature surfactant levels until week 35. Being born at 28 weeks, his type II pneumocytes are not fully mature yet/haven't produced enough yet.

Type I and II pneumocytes line the basement membrane. Type I (C) are squamous, and type II (D) are cuboidal.

E: alveolar macrophage B: RBCs A: capillary endothelial cell?

jj375  Here is a labeled diagram that may help! A) Capillary endothelium B) RBCs C) Type I pneumocyte D) Type II pneumocyte E) I kinda think these are alveolar macrophages https://ib.bioninja.com.au/_Media/lung-tissue-diagram_med.jpeg +2
j44n  did anyone else think D was trying to show a lamellar body that ID's a type II pneumoyte +
j44n  my bad i meant B**** +
i_hate_it_here  I sure did +
prostar  Lamellar bodies are not visible in this magnification. They are viewed in Electron microscopy. +1

 +2  (nbme17#0)

The vagus nerve is responsible for soft palate elevation and the midline uvula. This is a right-sided lesion, which causes uvula to deviate toward the CONTRALATERAL side. This is because the vagus is still intact on the opposite side; you can lift the palate; uvula goes that way.

Side note: Monster House is such an underrated movie; that uvula joke is gold.


 +1  (nbme17#38)

https://imgur.com/RQGrWLw

G represents the primary somatosensory area of the parietal lobe. The stem describes a 69 (nice) year old woman with sensory issues on the left side. She presents w/ a Babinski sign on the left, decreased somatic sensation in the left foot, agraphesthesia (when you "draw" a number on someone's skin and they can't interpret it) on the plantar surfaces of the toes, decreased position sense in the toes. The question says there is an edematous area in the cerebral cortex of the right hemisphere.

I had trouble with this, but I think it's describing somatosensory because of the sensory problems. Don't understand the UMN lesion (Babinski). Here's what Wikipedia says: "Lesions affecting the primary somatosensory cortex produce characteristic symptoms including: agraphesthesia, astereognosia, hemihypesthesia, and loss of vibration, proprioception and fine touch (because the third-order neuron of the medial-lemniscal pathway cannot synapse in the cortex). It can also produce hemineglect, if it affects the non-dominant hemisphere. Destruction of brodmann area 3, 1, and 2 results in contralateral hemihypesthesia and astereognosis."

mittelschmerz  The Babinski tripped me up too, here's what I found: "Sixty percent of the CST fibers originate from the primary motor cortex, premotor areas, and supplementary motor areas. The remainder originates from primary sensory areas, the parietal cortex, and the operculum. Damage anywhere along the CST can result in the presence of a Babinski sign." from https://www.ncbi.nlm.nih.gov/books/NBK519009/ +9
yourmomsbartholincyst  I think this question is more simply about the topographical arrangement of the homunculus (which I once again somehow managed to flip backwards during the exam). Lower extremity is topographically mapped to more medial portions of the somatosensory cortex, hence letter G and why ACA strokes tend to affect the LE more. Homunculus, our favorite hunk, FA2020 pg 502 +9
j44n  youre occluding the MCA blow flow from the MCA flows front to back so if you occlude the section that provides blood flow to the precentral gyrus you will also occlude the section that supplies the sensory portion http://what-when-how.com/neuroscience/blood-supply-of-the-central-nervous-system-gross-anatomy-of-the-brain-part-1/ +
j44n  excuse me i miss spoke its the ACA because its her legs, look at figure 4-2 in the link on my previous comment +
j44n  so if you have motor and sensory the infarct is in the portion that belongs to the motor portion, if you have sensory only youve occluded the artery more distally +
jy1544  I thought G was indicating the primary motor cortex in the frontal lobe from a medial view (anterior to the central sulcus), hence the weakness - and the sensory disturbances were due to edema affecting the adjacent somatosensory cortex https://web.duke.edu/brain/siteParts/images/fig1-5_2018.jpg +

 +1  (nbme17#36)

Umbilicated is the biggest buzzword for poxvirus molluscum contagiosum. They appear in clusters and are all the same age. It's contagious (she got it from the pool party), and is most commonly seen in kiddos. Can also be seen in adults as a sexually-transmitted disease.

The only other option could be herpesvirus (varicella-zoster), but it would be described as "dew drops on a rose" or "vesicles on an erythematous base" rather then umbilicated.


 +3  (nbme17#23)

Not in First Aid, but Drs. Sattar and Goljaan emphasize this point

In B-cell neoplasms (lymphoma, MM), the ratio of immunoglobulins is thrown off. Kappa and lambda refer to the Ig light chain genotypes, and is normally 2-3:1 for kappa to lambda. Here, it's almost 16:1, and this is a huge sign that there is a monoclonal proliferation of one cell type.

The other answer choices could refer to polyclonal proliferations, but a (mono)clonal neoplasm would be reflected in the surface k:l ratio as well as the G6PD isoforms for androgen receptors.


 +3  (nbme17#19)

The different E. coli strains:

-P pili/fimbriae (specifically, **mannose-binding type I fimbria): cystitis and pyelonephritis (UTIs) -K capsule (composed of sialic acid): pneumonia, neonatal meingitis -LPS endotoxin (O157:H7 strain): septic shock (EHEC specifically) -Heat labile toxin, heat stable toxin: increases cAMP & cGMP, respectively (watery diarrhea; ETEC specifically)

I don't think E. coli has a pyrogenic superantigen toxin; this might just be S. aureus thrown in here.


 +1  (nbme17#44)

2 things to help with this one: 1) LA is the most posterior heart chamber. 2) You use a transesophageal echo to visualize the left atrium

So, whenever it gets larger, it's got a propensity to displace the esophagus and/or trachea.


 +4  (nbme17#16)

Changes that happen in aging:

Stays the same: TLC (very important to know this)

Increased: lung compliance, residual volume, V/Q mismatch, A-a gradient

Decreased: chest wall compliance, FVC, FEV1, respiratory muscle strength, ventilatory response to hypoxia/hypoxemia

AKA don't get old

gooooose  FA 2020 p665 +1
sschulz2013  Exception: severe kyphosis can cause decrease in TLC! +
ownersucks  Even though lung compliance increases there is stiffening of chest wall which balance out increased lung compliance. Thus TLC remains unchanged RV increase and FEV decreases because there’s collapse of out flow tract which weakens with age +1

 +0  (nbme17#27)

There's 3 alleles present - 1, 2, and 3. The question asks what the child of a 1,3 x 2,2 pairing would be. Thus, it'd have to be either 1,2, or 2,3 because they have to inherit one of the #2 alleles from momma. From there, we see that all males with the 1,3 genotype are affected - don't get distracted by the 1,3 female! Since the question is asking for an unaffected male, the answer can't be 1,2, making his genotype 2,3. But silly question imo ¯_(ツ)_/¯

bingcentipede  Oh wait nvm, I thought through this wrong. Basically still think that 1 seems to be a bad allele and that's what I went with +1

 +1  (nbme16#26)

This is happening at one point in time. The investigators are testing employees in the present w/ no mention of follow-up. Best answer is cross-sectional


 +1  (nbme16#12)

Drugs that cause interstitial nephritis include the 5 Ps: Pee (diuretics), pain-free (NSAIDs), penicillins (and cephalosporins, PPIs, and rifamPin. She's likely taking a penicillin or cephalosporin for her UTI. These drugs act as induce hypersensitivity reactions in the interstitium. The huge tip-off that it's interstitial nephritis is the increased eosinophils on the urinalysis, almost pathognomonic for this.

yhm17  I was thinking the drug they were referring to was TMP-SMX which is more first line for UTIs and also causes AIN. +2
feochromocytoma  AIN would not explain the rash and high eosinophil count though. +
feochromocytoma  Never mind... I thought you referred to ATN, my bad +

 +6  (nbme16#49)

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.


 +3  (nbme16#17)

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. +2

 +0  (nbme16#31)

This is a woman with sarcoidosis, as suggested by her hypercalcemia and noncaseating granulomas. The normal demographic for this is an older African-American woman.

In sarcoidosis, there is increased 1,25-(OH)2-vitamin D (active form), leading to increased calcium resorption in the intestine (leading to hypercalcemia). This increased calcium has negative feedback on PTH hormone release, leading to decreased PTH levels as well.


 -1  (nbme16#41)

This is a man with some depressive symptoms who does not meet the criteria for MDD. The important takeaway here is that he's been experiencing this grief for less than 1 year, which is when this usually resolves by.

After 12 months, or if there is severe functional impairment, then you have to consider treatment for MDD if he meets the criteria.

surfergirl  No, MDD is recurrent episodes lasting more than 2 weeks characterized by 5/9 diagnostic criteria, must include depressed mood or anhedonia. The grandpa only has sleep disturbances and depressed mood (2/9) and maybe psychomotor problem for following the lady (3/9). FA 2020 p561. +
m0niagui  Persistent complex bereavement disorder involves obsessive preoccupation with the deceased and causes functional impairment, lasting at least 12 months (6 months in children). Can also meet criteria for major depressive episode.FA2020 pg 562 +

 -2  (nbme16#39)

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.


 +1  (nbme16#39)

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.


 +0  (nbme16#24)

Puberty (Tanner stage II) begins at its EARLIEST at... -8 years old for a girl (thelarche) -9 years old for a boy


 +3  (nbme16#49)

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 +2
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. +2

 +0  (nbme16#8)

Dextromethorphan is an OTC opiate analog that works as an anti-tussive. Common side effects of all opiates is constipation and pinpoint pupils.


 +5  (nbme16#25)

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 +
drdoom  very nice +

 +6  (nbme16#24)

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 +10
jsanmiguel415  I only got it because I did the opposite - assumed that going to a wet pool could cause her to slip and fall +4

 +1  (nbme16#32)

The patient has a brain cancer, which is 50/50 between primary cancer and metastasis (lung most common; also breast, colon).

The answer is small cell carcinoma of the lung versus a primary brain cancer because there are cells staining positive for carcinoma marker (cytokeratin) and neuroendocrine markers (chromogranin and synaptophysin), which is what SCLC is.

cassdawg  Another reason this is small cell lung cancer is the weakness of the proximal upper and lower extremities while also having augmentation (increasing) of strength with repetitive stimulation. This is characteristic of Lambert-Eaton myasthenic syndrome [where strength increases with stimulation; opposite of myasthenia gravis]. Lambert-Eaton can be caused by a paraneoplastic syndrome of small cell lung cancer (FA2020 p228 and 472) +7
passplease  What about the fact that it is a single well-demarcated mass. Wouldnt metastatic cancer present as multiple masses? This made me think primary brain cancer. +6
jaeyphf  @passplease I originally thought this way too and it fucked me. I think the easiest way is elimination + staining. Pt is an adult - eliminate neuroblastoma, ependymoma as both are more common in kids Pt is not immunocompromised - eliminate CNS lymphoma GBM does not stain positive for cytokeratin, chromogranin, synaptophysin - eliminate GBM Left with Small cell carcinoma +1

 +1  (nbme16#45)

Patient has PCOS, characterized by -Increased insulin resistance (likely due to obesity - this is the inciting imbalance) -Increased testosterone (because of aromatase in adipose tissue converting estrogen to androgens) -Increased LH (characteristically, there is an increased LH:FSH ratio; according to FA, the increased insulin affects hypothalamic-hormonal feedback response to the pituitary)

2059nyc  Doesn't aromatase convert testosterone INTO estrogen? +
2059nyc  From what it looks like, and correct me if I'm wrong, testosterone is converted to estrogen (via aromatase), that increases inhibin, which causes less FSH production. Thus the increased LH:FSH ratio. And then the insulin resistance is an unexplained part of the syndrome. +

 +0  (nbme16#27)

If it's happening for less than 1 month, it's likely brief psychotic disorder. FA also mentions having an acute stressor, which isn't mentioned in the stem unfortunately. But this all about knowing the time frame w/ the positive symptom of hallucination.


 +1  (nbme16#46)

This is an older woman with sarcoidosis. This commonly happens in this demographic (usually African-American women) and presents with hypercalcemia and noncaseating granulomas.

Sarcoidosis is caused by uncontrolled active vitamin D synthesis by macrophages, leading to increased 1a-hydroxylase activity in the kidneys, leading to more vitamin D.

This increased vitamin D leads to... -Increased Ca by increased intestinal absorption w/ no negative feedback on vitamin D -PTH is decreased because of the negative feedback from calcium


 +1  (nbme16#15)

In congenital diaphragmatic hernia, there is a herniation of the intestines through the diaphragm (usually on the LEFT SIDE - more common side). You'll hear bowel sounds in the thorax and the "cystic-appearing areas" are the bowels.

okokok1  yes. and the the reason you most often wont see it on the right is from the protection of the liver. +

 +0  (nbme16#3)

This is a peri-menopausal woman experiencing the typical symptoms of hot flashes and irregular periods. Decreased estrogen/progesterone production leads to vaginal atrophy and negative feedback onto the anterior pituitary, leading to increased FSH and LH hormones.

baja_blast  Menopause on FA2019 p. 622 +

 +1  (nbme16#47)

From FA '19 p. 468: "Foreign body inflammatory facial skin disorder characterized by firm, hyperpigmented papules and pustules that are painful and pruritic. Located on cheeks, jawline, and neck. Commonly occurs as a result of shaving (“razor bumps”), primarily affects African-American males."

Big hints is that... -He's African-American -It's happening in areas where he's shaving (face, jaw, neck)


 +5  (nbme16#7)

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)


 +0  (nbme16#9)

Alocholics can get aspiration pneumonia, which involves aspiration of the normal oral flora (Klebsiella and anaerobes like Peptostreptococcus, Fusobacterium, Prevotella, Bacteroides). So this is normally part of the flora and can be aspirated in alcoholics.

iury_r1beiro  Hello, i think it is Streptococcus viridans; coccus in chains and normal oral flora. Alcoholics can get aspiration pneumonia, which can evolve to a pulmonary abscess. FA2020 p146. https://www.atsjournals.org/doi/pdf/10.1164/ajrccm.156.5.97-03006 +1

 +3  (nbme16#40)

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? +4

 +3  (nbme16#3)

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 +

 +3  (nbme16#38)

2 things:

1) if there was an embolus in any of the other arteries, there would be more severe symptoms outside of the vision loss

2) Ophthalmic artery (a branch of the internal carotid artery) also supplies the retinal artery and blood to the eye most directly


 +2  (nbme16#50)

This is hereditary spherocytosis. The image stinks, but the cells are not super pale in the middle and they're round. Her dad also had a splenectomy (HS is autosomal dominant), which is the definitive treatment for HS.

Pt is also normocytic (90.2 um^3), so a lot of the other answer choices can be eliminated based off this.

In the end, screw this picture because it's not clear and you can't zoom in.

motherhen  Sad picture... I definitely thought this was B-thalessemia since the image looked like different size and shaped RBCs (anisopoikilocytosis). But if I squint my eyes real hard and turn sideways I guess I can also see those spheres +1
furqanka  beta thal, iron def and inadequate epo would have low reticulocyte count. impaired oxidative enzyme aka g6pd deficiency affects mostly males and would have bite cells +

 +5  (nbme16#17)

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

 +2  (nbme16#5)

This is describing hemochromatosis. Happens in men more often than women (menses is a protective factor for women in this iron-overload state), and he's also over the 40 year-old barrier between Wilson and hemochromatosis.

He's got bronze diabetes: hyperpigmentation and high resting glucose. Also has cirrhosis.

According to FA '19 (p. 389): classic heart issue is restrictive CM, but it also causes a dilated cardiomyopathy as seen in this vignette.


 +4  (nbme16#35)

Good explanation on reddit: https://www.reddit.com/r/step1/comments/d8aqj5/spoiler_nbme_16_hey_can_anybody_advice_how_to_get/

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 +6
deberawr  it's better than redownloading tiktok and getting distracted for 3 hours lol (don't do what i did its embarrassing) +

 +2  (nbme16#50)

Since she has regular 28-day cycles, ovulation will happen on day 14. In the follicular phase before ovulation, estrogen rises to the point of the LH surge while progesterone stays low. After ovulation on day 14, progesterone rises and estrogen will gradually rise as well.

nbmeanswersownersucks  I feel like Day 6 is correct as well because estradiol levels would be elevated and progesterone decreased too. +9
feochromocytoma  Nice username, and I agree +2
djeffs1  @nbmeanswesownersucks thats what I chose too, but apparently the first 7 days of cycle everything is kinda uniformly low... https://womeninbalance.org/files/2012/10/HormoneCycle.jpg +

 +5  (nbme16#32)

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." https://www.quora.com/Why-does-a-yeast-cell-give-Gram-positive-reaction

melanoma  Also we can recognize Staph aureus for the beta hemolysis in a blood agar +1

 +2  (nbme16#49)

The patient has bloody diarrhea, which basically eliminates all the other answers. Additionally she's from an area with poor water sanitation

In stool O&P, there will be trophozoites with engulfed RBCs (fancy word is erythrophagocytosis).

Finally, the distention and tenderness implies the liver/RUQ issues


 +1  (nbme16#12)

This is a patient with RA not responding to steroids or MTX. Next line of therapy is a TNF-a inhibitor like adalimumab, an anti-TNF alpha antibody.

feochromocytoma  I think we can also use Etanercept +1

 +3  (nbme16#12)

This is a patient with RA not responding to steroids or MTX. Next line of therapy is a TNF-a inhibitor like adalimumab, an anti-TNF alpha antibody.


 +8  (nbme16#26)

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. +

 +0  (nbme16#26)

Talking about a boy who lost voluntary movement in his extremities. Thus, his corticospinal tract is injured. It decussates in the medulla, so contralateral limbs are affected. Cross out anything on the left side.

The FA picture is really good with this. Just gotta know E (and F) are the lateral corticospinal tracts.

cassdawg  Tracts are FA2020 p508. +1
wonkyhonky69  Right, but it said he is unable to move his right side, while the answer was right corticospinal tract. I think we had to realize that this slice was below the level of the pyramidal deccusation. +6

 +2  (nbme16#14)

FA 2019, p. 57: "The frequency of an X-linked recessive disease in males = q and in females = q^2" Found this on USMLEforum: "X-linked recessive: Prevalence = allele frequency q square = q Carrier state for females = 2q"

Additionally, from Reddit: https://www.reddit.com/r/step1/comments/d492nm/nbme_16_leschnyhan_hardy_weinberg/

If q=1/100,000, p~1. So 2pq~2q=1/50,000. Hard to do with the NBME calculator unfortunately.


 +6  (nbme16#16)

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. +3
the_enigma28  Ribosomal disaggregation (detachment) does occur in reversible cellular injury, but that is not the mechanism of cellular swelling! +1
topgunber  this last comment is extremely important to recognize when asking about reversible injury +

 +2  (nbme16#5)

Phenylephrine is an a1>a2 agonist, given as a nasal decongestant. Thanks Sketchy Pharm

md_caffeiner  I thought exactly the same,thoe brothers in sketchy, but then thought "spring?Sneezing? This is an asthym q and the answer shoud be b agonist" Too much thinking... +1

 +12  (nbme16#30)

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

https://step1.medbullets.com/gastrointestinal/107080/hepatic-encephalopathy


 +2  (nbme16#39)

It's a little bit of anatomy, a little bit of knowing what the question wants us to know.

Here's a nice pic of the ureter under the ovary: https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary-alt:20180930192054-59433-mediumThumb-66713fig4_6.jpg?pub-status=live

Specifically, you want to protect the ureter during surgery. "Bridge over water" kind of applies here, knowing that uterine artery is also being ligated during ovary removal. It's so important for surgeons to be able to differentiate the arteries (which are ok to be sacrificed if you're doing a hysterectomy/oophorectomy) but the ureter must be kept intact.

i_hate_it_here  Isn't the round ligament of the uterus inferior to the ovary? Why would that not want to be preserved as well? +1
flvent2120  It is inferior, but I think it comes down to what the question is trying to ask. To me I was stuck on that fact as well, but it came down to "what has a significant function and therefore needs to be protected?". The round ligament doesn't have any arteries and whatnot, whereas damaging the ureter has significant consequences. With that, the question seemed to be hinting at "ureter" +

 +2  (nbme16#34)

T1DM, she's getting hypoglycemia. The most appropriate medication is glucagon, which would stimulate hepatic (not skeletal muscle) glucose production


 +2  (nbme16#43)

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.


 -3  (nbme16#48)

Sounds like a negative feedback question. If T4 crosses the placenta, it basically inhibits TSH release. Then the newborn won't be making TSH, so this could be like a transient hypothyroidism


 +2  (nbme16#24)

The stem is describing myasthenia gravis: ptosis, fatigue with continuing exercise, slurred speech, etc.

So, there will be autoantibodies to the ACh receptor

In contrast, LES gets better with activity. There are autoantibodies to the presynaptic calcium channel and decreased ACh release


 +7  (nbme16#25)

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 +

 +2  (nbme16#26)

Fish oil, from FA 2019: "Believed to decrease FFA delivery to liver and decrease activity of TG synthesizing enzymes" God this Sketchy was awful

Increases catabolism of LDL cholesterol - statins (I think? I found this article https://www.medscape.com/viewarticle/412688_2) Inhibits cholesterol uptake - ezetimibe Activates PPAR alpha - fibrates Inhibits HMG CoA - statins

feochromocytoma  This is all true, but the question was asking about a vitamin supplement given along the fish oil, which is Niacin (B3). It works by inhibiting lipolysis and reducing hepatic VLDL synthesis +




Subcomments ...

submitted by cassdawg(931),

FA2020 p258

Odds ratio = (250/250) / (50/150) = 3

cheesetouch  FA 2018 P254 +1  
bingcentipede  For OR = ad/bc (from a/c divided by b/d) +  


submitted by cassdawg(931),

The big hint here is EXTREME respiratory depression which is characteristic of opioid overdose, so he should be given naloxone. [FA2020 p570 has drug intoxication and withdrawal syndromes]

bingcentipede  And he was also taking codeine, a mu opiod agonist. So naloxone would be able to reverse the codeine specifically. +1  
schep  Flumazenil-GABA antagonist, used to treat benzodiazepine OD Fomepizole-competitive inhibitor of alcohol dehydrogenase, used to treat ethylene glycol and methanol OD hemodialysis-can be used for severe lithium ODs, not sure what else propranolol-nonselective beta blocker; not sure if it treats any ODs in particular +1  
deadbeet  The HR made me waste way too much time on this question. Don't think tachycardia is the norm for opoid OD. +1  
prostar  the reason for increase HR is hypotension(and the reason for hypotension is opioid induced mast cell release- histamine-vasodilation) +  


submitted by cassdawg(931),

The question is essentially asking which of the following would be associated with Bulemia with purging (the woman's condition). The best answer is parotid gland enlargement (FA2020 p567)

bingcentipede  The other symptoms of bradycardia, sluggish DTRs, and sparse secondary hair would be suggestive of ANOREXIA NERVOSA. However, the patient does not have a BMI <18.5, eliminating all these answers. +  
feochromocytoma  hmmm, I feel these symptoms combined are more likely to be seen in hypothyroidism though +  


According to FA2019:

MDD is episodes characterized by >/= 5 of the following for >/= 2 weeks (must include patient-reported depressed mood or anhedonia):

(symptoms that our patient has had for 6-weeks in bold below)

+ depressed mood + sleep disturbance + loss of interest (anhedonia) + guilt or feelings of worthlessness + energy loss and fatigue + concentration problems + appetite/weight changes + psychomotor retardation or agitation + suicidal ideation

bingcentipede  I was between MDD and menopause for this one. However, in addition to hitting the SIGECAPS criteria, the patient is taking estrogen replacement therapy which can reduce the symptoms of menopause. (I think - correct me if I'm wrong!). +  


submitted by cassdawg(931),

Total gastrectomy = absence of parietal cells

Parietal cells are necessary to secrete intrinsic factor which binds vitamin B12 to allow absorption.

Also his symptoms (which fit the description of subacute combined degeneration) are characteristic of B12 deficiency.

FA2020 p69 (insert sunglasses emoji here)

bingcentipede  The gastrectomy was also 10 years ago; it takes 3-4 years to deplete your hepatic B12 stores. +1  
baja_blast  Nice +  


submitted by flapjacks(52),

Haemophilus ducreyi (chancroid) - deep, purulent, painful ulcers with suppurative lymphadenitis (no mention in stem), grayish necrotic base

HSV - multiple, shallow, painful ulcers with erythematous base

NSFW (obviously) link to example of chancroid with gray necrotic base

bingcentipede  If you also look at the lesions, they like the "dew drops on a rose" appearance. Multiple vesicles that hurt when burst +3  


submitted by cassdawg(931),

Atrial myxomas are the most common cardiac tumor in adults, and they may cause embolus complications hence our lady's painless loss of vision, likely due to central retinal artery occlusion [FA2020 p316]

The histology is characteristic of a myxoma with gelatinous material and cells immersed in glycosaminoglycans.

According to Daddy Goljan, basically for primary heart tumors if its an adult its a myxoma, if its a kid its a rhabdomyoma.

cheesetouch  FA20118 P309 +  
bingcentipede  It's also in the LEFT ATRIUM! +1  


submitted by cassdawg(931),

The patient's history of 2 years decreased force of urinary stream and increased need to urinate throughout the night combined with his age is suggestive of benign prostatic hypertrophy causing obstriction of the urethra. He subsequently developed renal failure characterized by bilateral hydronephrosis and dilated ureters, suggesting "backup" of urine likely due to obstruction from prostatic hypertrophy. This "backup" puts back pressure into the kidney tubules and ultimately bowman's space, and thus causes increased hydrostatic pressure in Bowman's space leading to decreased GFR and renal failure.

bingcentipede  Normally, Bowman's space has hydrostatic pressure of 0 mmHg. Knowing that there's backflow pressure is also important to know how it affects GFR +2  


Inhalant intoxication= slurred speech, disturbed gait, drowsiness

Inhalant withdrawal= headaches and irritability

usually will present with rash around nose and mouth too

FA2020 pg 570

mittelschmerz  So mad I second-guessed myself on this. Its always PCP or huffing glue smh +1  
bingcentipede  Think I had UWorld question on this. Apparently in this age group (teens), inhalants like glue are the first drugs they try. Only ever seen this on It's Always Sunny but w/e +3  
i_hate_it_here  <- +  


submitted by cassdawg(931),

Mycobacterium leprae likes cool temperatures (FA2020 p141)

Mycobacterium leprae is an acid-fast bacteria which can cause two skin manifestations:

  • Lepromatous presents diffusely over the skin and with leonine facies and is more serious with a largely Th2 response and high bacteria load
  • Tuberculoid (what our patient has) presents with a few hypoesthetic hairless skin plaques with a largely Th1 response and low bacteria load

Leprosy likes cool temperatures so it infects skin and superficial nerves. Even without knowing the organism, the link could also be potentially inferred!

bingcentipede  In addition, the only other acid-fast bacterium is Nocardia; they would have to describe it as branching/filamentous (NOT a bacillus!). +2  


submitted by cassdawg(931),

The description of symptoms (right blown pupil, difficulty in eye movement) coorespond with damage to the oculomotor nerve. In this section, letter A is labelling the oculomorot nerve.

Here is a diagram of the middle cranial fossa coronal section labelled. Here is another diagram.

bingcentipede  Also helps to memorize the order! It's (from top to bottom) CN III, IV, V1, V2, and then VI is next to the internal carotid (C) +  


submitted by bingcentipede(208),

A premature infant does not have mature surfactant levels until week 35. Being born at 28 weeks, his type II pneumocytes are not fully mature yet/haven't produced enough yet.

Type I and II pneumocytes line the basement membrane. Type I (C) are squamous, and type II (D) are cuboidal.

E: alveolar macrophage B: RBCs A: capillary endothelial cell?

jj375  Here is a labeled diagram that may help! A) Capillary endothelium B) RBCs C) Type I pneumocyte D) Type II pneumocyte E) I kinda think these are alveolar macrophages https://ib.bioninja.com.au/_Media/lung-tissue-diagram_med.jpeg +2  
j44n  did anyone else think D was trying to show a lamellar body that ID's a type II pneumoyte +  
j44n  my bad i meant B**** +  
i_hate_it_here  I sure did +  
prostar  Lamellar bodies are not visible in this magnification. They are viewed in Electron microscopy. +1  


Gram positive rod + pregnant woman = Listeria monocytogenes

bingcentipede  GBS doesn't infect the mom, it infects the baby +1  


FA 2020 pg 425

Porphyria cutanea tarda-- defect in UROD in the heme synthesis pathway that causes photosensitivity and blistering

bingcentipede  Most common porphyria, too +2  
brise  The thing that got me screwed was the "increases synthesis of compounds"; like what compounds? +  
i_hate_it_here  I swear they just love to say shit to throw us off smh +  


submitted by cassdawg(931),

Fat, fourties, female is at increased risk for gallstones because of her liver increasing cholesterol synthesis. (FA2020 p396)

bingcentipede  Cholesterol gallstones happen when there is increased cholesterol or decreased bile salts, decreased phospholipids. +3  


late onset CAH w/ 21 hydroxylase defiency--> excess androgens (increased facial hair and irregular menses, etc), salt wasting (low BP), increased 17-hydroxyprogesterone is key

11B problem= HTN and excess androgens 17a problem= HTN and decreased androgens 5a reductase converts testosterone to DHT 3B-hydroxysteroid dehydrogenase is involved in steroid synthesis earlier in the pathway

bingcentipede  If you see HYPOtension in a CAH question, it's gotta be 21-hydroxylase! +2  
bingcentipede  My special friend just gave me a mnemonic for this that I did not know. If the 1 is the 1st digit (11, 17) = hypertension. If there is a 1 in the 2nd digit (11, 21) = virilization. +1  


late onset CAH w/ 21 hydroxylase defiency--> excess androgens (increased facial hair and irregular menses, etc), salt wasting (low BP), increased 17-hydroxyprogesterone is key

11B problem= HTN and excess androgens 17a problem= HTN and decreased androgens 5a reductase converts testosterone to DHT 3B-hydroxysteroid dehydrogenase is involved in steroid synthesis earlier in the pathway

bingcentipede  If you see HYPOtension in a CAH question, it's gotta be 21-hydroxylase! +2  
bingcentipede  My special friend just gave me a mnemonic for this that I did not know. If the 1 is the 1st digit (11, 17) = hypertension. If there is a 1 in the 2nd digit (11, 21) = virilization. +1  


submitted by bingcentipede(208),

There's 3 alleles present - 1, 2, and 3. The question asks what the child of a 1,3 x 2,2 pairing would be. Thus, it'd have to be either 1,2, or 2,3 because they have to inherit one of the #2 alleles from momma. From there, we see that all males with the 1,3 genotype are affected - don't get distracted by the 1,3 female! Since the question is asking for an unaffected male, the answer can't be 1,2, making his genotype 2,3. But silly question imo ¯_(ツ)_/¯

bingcentipede  Oh wait nvm, I thought through this wrong. Basically still think that 1 seems to be a bad allele and that's what I went with +1  


submitted by medstudent(11),

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 +  


submitted by medstudent(11),

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 +  


submitted by zincy7(13),
unscramble the site ⋅ remove ads ⋅ become a member ($39/month)
  • Bguinnr mAdnoalib Pain rusoh tfare naiget = rGciats reluc
  • kBlca olstso ofr 2 yasd = ???
  • yarfecRtor ot COT ndAistca dan 2H slreockB
  • tnawiSge and owL BP
  • citrnePcaa Mssa = osmt klieyl MGIOTNRAAS
GI LCO

hnIcsouimmotialcemh lblgenia uses sinbtdaeio sa krsmrea ofr whta eyth twna ot f.ndi In isht sa,ce eewr' itgcpsunes tingras vgien het osspmytm

t:eNo uYo hlousd erivse eht ofnucitn, ut,insmtoail nda etis of aelsere rof chea fo the orsmohne edonetnim sa llwe

NEEFEE:R RColEng-eilZnsilorl ndreoySm

bingcentipede  Black stool because blood in the GI tract? +1  
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 +  


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tucsSep nbalednauc onlnroscitaat ewnh eehrt era ltpilmue rthib sesslo dna oesm shtibr urselt ni rteis.osim

ebReremm ti usaesc 4 % of wDon myedorsn

bingcentipede  "Unbalanced chromosome rearrangement" is also a description of trisomy in and of itself +  
bingcentipede  "Unbalanced chromosome rearrangement" is also a description of trisomy in and of itself +  


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Ssupcte ndulbaeacn tociosntrnala enwh heetr era ltpleium thibr loesss and oems thbisr lertus in ess.rtmiio

emembeRr ti auecss 4 % of wnDo yrsnmedo

bingcentipede  "Unbalanced chromosome rearrangement" is also a description of trisomy in and of itself +  
bingcentipede  "Unbalanced chromosome rearrangement" is also a description of trisomy in and of itself +  


submitted by andro(170),

Graft Vs Host disease

Look out for Skin involvement - maculopapular rash
Enteric involvement - diarrhea and or cramping , abdominal pain .. nausea/vomiting
Hepatic dysfunction - jaundice

*** The skin , liver and intestines are the most involved affected organs

drdoom  basic science of GVHD https://youtu.be/he2vfNZDfbY?t=522 +3  
bingcentipede  Graft vs. Host disease - type IV hypersensitivity response, but this is the only one where the graft (T cells) are attacking the recipient (cells). Additionally, GvH dz is very common (at least in questions) in BONE MARROW TRANSPLANTS (also liver, but BMTs seems to pop up a lot) +  


submitted by medninja(15),

McArdle disease --> Characterized by a flat venous lactate curve with normal rise in ammonia levels during exercise. FA2020

bingcentipede  Going off that, if there's a stem with a patient getting tired quickly during exercise, McArdle should be on the differential. It's an older dude who APPARENTLY never experienced this before but w/e. McArdle is associated w/ glycogen phosphorylase (AKA myophosphorylase) problems +2  
biochemgirl22  The question stem also mentions that there is no rise in lactic acid. This could be because if we cannot even break down glycogen to glucose to get pyruvate, we can't even turn pyruvate to lactate via lactate dehydrogenase. And also, without anaerobic metabolism, you fatigue quickly. FA 2020 pg. 87 also says there is a normal rise in ammonia levels during exercise in McArdle patients. They also suffer from arrhythmias from electrolyte abnormalities. There is also a "second wind phenomenon" where they are able to tolerate exercise better after getting more blood flow to their muscles. This could be due to glucose in bloodstream bringing glucose to muscles? +2  


submitted by medninja(15),
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Tihs unsqeito dosunde lkie sbimlu,to oybydna swkno yhw is ttuesna?

bingcentipede  I think it's because of the last sentence - asks about a defect in an inhibitory neurotransmitter, with glycine being the only possibility. I think it's one of those "here's a stem, but just look at the last sentence" questions. +5  
cassdawg  This actually is not tetanus or botulism. The deficit has been present since birth. He has glycine encephalopathy, a rare disorder (https://en.wikipedia.org/wiki/Glycine_encephalopathy). Definitely could be tricked into thinking botulism but defect in "inhibitory neurotransmitter" points to glycine deficit as glycine is the only inhibitory neurotransmitter listed! +1  
cassdawg  (Disclaimer that I am assuming his deficit is just a weird kind of glycine encephalopathy because normally its a disease of metabolism not receptor; but it presents with the hiccups and seizures like seen in this baby. Big thing is the last sentence as was already said) +1  


submitted by hungrybox(968),

Excess pattern repeats lead to strand slippage/errors due to an unstable region (in this case, excess Cytidine bases).

It could be a repeated pattern as well (ie the trinucleotide repeat CAG in Huntington's).


here's a more in depth explanation (from wikipedia article on Slipped-strand mispairing):

A slippage event normally occurs when a sequence of repetitive nucleotides (tandem repeats) are found at the site of replication. Tandem repeats are unstable regions of the genome where frequent insertions and deletions of nucleotides can take place, resulting in genome rearrangements.

hungrybox  Anyone know why it's not Transposon insertion? I was thinking maybe because transposons have to be longer than one nucleotide, but I'm not sure. +3  
bingcentipede  @hungrybox I think it's because transposons are usually gene segments rather than a single nucleotide insertion - plus w/ what you said about the repeated pattern, I think slipped-strand mispairing (which is a concept the NBME loves) more likely. +19  
i_hate_it_here  cool so why do I need to know this +