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submitted by hungrybox(431),

Great video I used to learn this material.

  1. There are 3 major types of drugs: uppers (stimulants), downers (depressants), and hallucinogens.
  2. Heroin is an opioid. Opioids are downers.*
  3. Downers do what it sounds like. They cause "down" symptoms: sedation/decreased anxiety (and thus behavorial disinhibition), respiratory depression.
  4. Thus withdrawal will cause the opposite: hypertension/tachycardia, anxiety.
hungrybox  *other downers: alcohol, benzodiazepines, barbiturates +  
nwinkelmann  THANK YOU! for the link to the video. this is one thing I've ALWAYS struggled with. +  
qball  I get that this is a good rule of thumb to help narrow down between alcohol and heroin, BUT is still not enough to answer this question. Some key features for depressants (downer) is alcohol (if we are talking mild withdraw) - tremors , diaphoresis and delirium (heavy withdraw) . For Heroin - Dilated pupils, yawning and lacrimation are key exam findings. +  


submitted by soscrying(4),

at my uni, we learnt that at lower GFR, loop diuretics still work. That's why you should use them in renal failure. Thiazides would not work with a GFR of <30.

qball  Dang, you actually learned something at your school? Lucky. +1  
lowyield  At our med school they teach us that Thiazide anti-HTN function is primarily from it's direct effects on vasculature rather than it's diuretic effects. Somehow directly affects the vasculature which is not well understood but this is linked to why Thiazides have greater efficacy in African American Populations. That's kinda why i figured it wouldn't be the best diuretic in this case. +  


This is a picture of Giardia lamblia… caused by drinking contaminated water with cysts.

Multinucleated trophozoites

Rx -- Metronidazole -- forms toxic free radical metabolites in the bacterial cell that damage DNA = BACTERICIDAL

qball  This is testing our knowledge in a FAIR way. Why cant there be more questions like this instead of them trying to trick us, have poorly worded questions or have us pick the least shitty answer. End of rant. +  


submitted by sahusema(72),

The Didanosine guy in the NRTI sketch is holding a pancreas sponge.

qball  Sir Dan, my boi. +  


Membranous Glomerulonephritis is Nephrotic; ONLY PROTEINURIA is in the vignette

It can't be MPGN because MPGN is Nephritic with possible Nephrotic

Other choices are eliminated by Renal Biopsy

hungrybox  agreed "granular deposits" rules out MCD (the only other nephrotic syndrome) because MCD is IF (-) +2  
cooldudeboy1  could someone explain why the other choices are ruled out by biopsy? +  
arlenieeweenie  @cooldudeboy1 PSGN does have a granular immunofluorescence, but there is no previous illness or hematuria mentioned so you can rule that out. Goodpasture is classically linear IF since they're antibodies against the GBM. IgA nephropathy is mesangial IF so it would deposit more in the middle. Minimal change wouldn't show anything on IF +1  
qball  I know First Aid states MPGN as a nephritic disease but I think it can present as nephritic or nephrotic syndrome. https://emedicine.medscape.com/article/240056-clinical. Of course, the renal biopsy helps give it away but I wouldn't be so quick as to rule out MPGN +  


submitted by drdoom(354),

The synthesis of virtually all proteins (mRNA->peptide) occurs in the cytoplasm.[1] That’s where all ribosomes reside, after all. Ribosomes, which are mostly just rRNA (~2/3 rRNA + 1/3 protein*, by weight), are assembled in the nucleus but only do their stuff once they get to the cytoplasm.

For a protein to leave its original hometown of the cytosol and become a resident of the nucleus or, sayyyyyy, the endoplasmic reticulum, it needs to have a little string of amino acids which shout “I belong in the nucleus!” or “I belong in the endoplasmic reticulum!”

Proteins ultimately destined for the ER contain an unimaginatively named string of amino acids known as “signal sequence,” which, for the purposes of the Step 1, is always at the N-terminus. The signal sequence tells other cytosolic proteins, “Hey! Take me (and the rest of the peptide of which I am part) to the ER!”

In the absence of this signal, a protein will remain in its “default” home of the cytosol.

Here’s a nice schematic showing the flow of proteins from initial synthesis to final destinations:


Endnotes

  1. “The synthesis of virtually all proteins in the cell begins on ribosomes in the cytosol.” (Essential Cell Biology, Alberts et al., 2014, p. 492)

*If you really want your mind blown, consider that even the protein subunits that make up that 1/3 of a ribosome are themselves initially synthesized in the cytosol; later, they are transported back into the nucleus via the nuclear pore.

qball  Awesome explanation. Now explain it to me like I'm 5. +  


submitted by hayayah(599),

the majority of carbon dioxide molecules are carried as part of the bicarbonate buffer system. In this system, carbon dioxide diffuses into the RBCs. Carbonic anhydrase (CA) within RBCs quickly converts the carbon dioxide into carbonic acid (H2CO3). Carbonic acid is an unstable intermediate molecule that immediately dissociates into bicarbonate ions (HCO3-) and hydrogen (H+) ions.

The newly synthesized bicarbonate ion is transported out of the RBC into the plasma in exchange for a chloride ion (Cl−); this is called the chloride shift. When the blood reaches the lungs, the bicarbonate ion is transported back into the RBC in exchange for the chloride ion. The H+ ion dissociates from the hemoglobin and binds to the bicarbonate ion. This produces the carbonic acid intermediate, which is converted back into carbon dioxide through the enzymatic action of CA. The carbon dioxide produced is expelled through the lungs during exhalation.

hungrybox  Amazing explanation. Thank you!! +  
namira  in case anyone wants to visualize things... https://o.quizlet.com/V6hf-2fgWeaWYu1u23fryQ.png +3  
ergogenic22  CO2 is carried in the blood is bound to hemoglobin, known as carbaminohemoglobin (HbCO2) (5%), dissolved CO2 (5%), bicarb is 90% +3  
pg32  Nice explanation, but can anyone clarify how we know from the question that we are measuring HCO3 rather than dissolved CO2? +1  
qball  @pg32 This question is asking about what accounts for the LARGER amount of co2 and the HCO3 buffer is about 85% of this transport and dissolved C02 is about 5-7%. https://courses.lumenlearning.com/wm-biology2/chapter/transport-of-carbon-dioxide-in-the-blood/ +  


It said it was fatal to males in utero, and the question asked about live born offspring. Since the males aren’t being born in the first place, I said 50% females and 0% males.

hungrybox  fuck i got baited +19  
jcrll  "live-born offspring" ← baited +8  
sympathetikey  Same :/ +  
arkmoses  smh +  
niboonsh  why is it 50% females tho? +2  
imgdoc  felt like an idiot after i figured out why i got this wrong. +1  
temmy  oh shit! +  
suckitnbme  This isn't exactly right as males can still be born as evidenced by individuals III 6,9,11. This basically an x-linked recessive disease. A carrier mother can still pass her normal X chromosome to a son (50% chance). It's just that the other 50% chance of passing an affected X chromosome results in death of the fetus in utero. Thus all males actually born will not be affected. +2  
makinallkindzofgainz  @suckitnbme, Correct, but if you're a live-born male, you 100% for sure do NOT have the disease, so the chance of a live-born male "being affected" is 0. +1  
spow  @suckitnbme it's not X-linked recessive, otherwise every single son would be affected and therefore have died in utero. It's X-linked dominant +  
qball  Jail-baited +  


submitted by est88(10),

Rabies Virus (rhabdoviridae)

Fever, encephalitis, drooling



submitted by hayayah(599),

HELLP syndrome: Hemolysis Elevated Liver enzymes Low Platelets.

A manifestation of severe preeclampsia. Blood smear shows schistocytes. Can lead to DIC and hepatic subcapsular hematomas Ž rupture Ž severe hypotension.

mambaforstep  FA 2019 pg 629 +  
qball  One thing I find odd with this question is HELLP is a manifestation of severe preeclampsia but she has had an otherwise unremarkable pregnancy. Shouldn't she have hypertension/edema in regards to her pregnancy beforehand? +  


drdoom  great schematic. +  
qball  Just to add, the ovarian artery branches from the aorta as well. +  


submitted by lnsetick(61),
  • APocrine = your armpits smell like an APE
  • ceRUMen = there’s no ROOM in your ears since they’re full of wax
  • EC-CRYne = when you ECercise, your pores are CRYing
  • SEBaceous = SEBum is SEEPing out of your pores
hungrybox  as an ape i'm offended +13  
dr.xx  stop being an ape. evolutionize! +6  
dbg  as a creationist i'm offended +1  
maxillarythirdmolar  Also, Tarsal/Meibomian glands are found along the rims of the eyelid and produce meibum +  
snripper  So why is it apocrine? The dude is EXERCISING when playing football. +  
qball  The question asks about "the characteristic odor" i.e. body odor coming from the APEocrine glands. The Eccrine glands secrete water and electrolytes. +  


submitted by sahusema(72),

Rosacea. An inflammatory facial skin disorder characterized by erythematous papules and pustule but no comedones. May be associated with facial flushing in response to external stimuli (eg, alcohol, heat).

qball  https://en.wikipedia.org/wiki/Rosacea#/media/File:Rosacea.jpg for that quick picture. +  


submitted by gabeb71(26),

The puborectalis muscle, which is one of the muscles that comprise the pelvic floor and plays an important role in both fecal continence and defecation, is tonically contracted and maintains the anorectal angle at rest.

here is a picture: https://www.123rf.com/photo_46940875_stock-vector-the-rectum-and-anus-showing-the-puborectalis-muscle-part-of-the-levator-ani-used-for-the-control-of-.html

gh889  How do you differentiate this from hypertonicity of the internal anal sphincter? +  
gh889  nvm. im dumb lol +  
qball  Uworld Q ID 17004 +  


submitted by sajaqua1(346),

In an elderly patient with isolated elevated alkaline phosphatase (normal serum calcium and phosphate) Paget's disease of bone should be at the top of the differential. This disease is due to dysregulation of osteoclastic and osteoblastic activity; first an initial osteoclast hyperactivity phase, then increased osteoblast activity for a mixture, then osteoclasts "burnout" leading to over-mineralization and sclerotic bone plaques. In addition, this can create arteriovenous shunts in the bones which decreases resistance, leading to high output cardiac failure (a similar problem can arise in arteriovenous fistulas from blood dialysis). On histology it will have a "mosaic" pattern.

A)- Aneurysmal bone cyst- largely a product of hyperactivity of osteoclasts, this occurs more often in the limbs, and shows a cystic space with balloon-like dilation. B) Angiosarcoma- angiosarcoma of the bone is n almost purely lytic lesion. They occur more frequently in younger people. C) Niacin deficiency- I can find nothing about vitaminb B3 deficiency involving bones. B3 deficienct results in pellagra, with the classic Three D's- dermatitis (rash necklace on C3/C4 dermatome), dementia, and diarrhea. E) Osteosarcoma- Found almost exclusively in younger people, this bone growth occurs at the growth plate, particularly at the proximal end of the tibia, distal end of the femur, or proximal end of the humerus (in the long bones around your knees or at your shoulders). It shows a large, solid growing mass that may raise the periosteum in a sunburst pattern/Codman's triangle. F) Prostatic carcinoma- rare for being one of, if not the only metastatic bone cancer that is purely osteoblastic.

alexb  Great explanation, except that there was a question in NBME 22 in which the prostatic carcinoma was osteolytic. One of the commenters here looked it up and apparently it's like that 30% of the time or something. So I guess you would have to use the high output HF, normal Ca, high ALP, and mosaic pattern to "play odds" as Goljan would say. +1  
qball  At least they were nice enough to put Paget disease because I had no idea what osteitis deformans is. +1  
drzed  USMLE seems to be moving away from using eponymous names... so it's a good idea to see if there is a descriptive name for diseases. For example, they don't use the word "Wegener" anymore if you have noticed, since it turns out that guy was a nazi. So now they call it by what it is -- granulomatosis with polyangitis. +2  


"His friends believe there may have been drugs at the party", period. lmao...

aisel1787  ahahaha +  
qball  What a snitch +1  
bend_nbme_over  Good thing they were at the ED cause that friend is gonna need some stitches +  


submitted by yotsubato(519),

So for Candida we can use

Azoles (fluconazole) (inhibit CYP450 demethylation)

Amphotercin B (pore formation in fungal cell membrane)

Caspofungin (prevent crosslinking of beta glucans in cell wall)

or Nysatin for oral or esophageal cases (pore formation)

This question is saying that she is taking an ORAL drug to treat candida vaginitis.

Amphotercin is IV

Caspofungin is also IV

so we're left with azoles

Azoles inhibit synthesis of ergosterol by inhibiting CYP 450 that converts lanosterol to ergosterol.

qball  Nystatin does treat vaginal candidiasis but is TOPICAL. +  
thotcandy  Nystatin is NOT for esophageal candidiasis, Swish and spit, not swallow. +1  
staghorn  Me - picks Metronidazole -_- +  
alexxxx30  @thotcandy...actually you can swish and swallow nystatin for esophageal infections (per Sketchy micro candida sketch) +  
turtlepenlight  I have seen that on the wards so I hope it works! +  


submitted by wired-in(46),

Maintenance dose formula is (CssCltau)/F where Css is steady-state target plasma conc. of drug, Cl is clearance, tau is dosage interval & F is bioavailability.

Neither dosage interval nor bioavailability is given, so ignoring those & plugging in the numbers (careful to convert units to mg/kg/day): (12 ug/mL * 1 mg/1000 ug) * (0.09 L/hr/kg * 1000 mL/1 L * 24 hr/1 day) = 25.92 mg/kg/day

...which isn't any of the answer choices listed. They must have rounded 0.09 L/hr/kg to 0.1 L/hr/kg, and doing so gives exactly 28.8 mg/kg/day (choice C)

lispectedwumbologist  That's so infuriating I stared at this question for 20 minutes thinking I did something wrong +35  
hyoid  ^^^^^ +5  
seagull  lol..my math never worked either. I also just chose the closest number. also, screw this question author for doing that. +4  
praderwilli  Big mad +4  
ht3  this is why you never waste 7 minutes on a question.... because of shit like this +7  
yotsubato  Why the FUCK did they not just give us a clearance of 0.1 if they're going to fuckin round it anyways... +10  
bigjimbo  JOKES +  
cr  in ur maths, why did u put 24h/1day and not 1day/24h? if the given Cl was 0.09L/hr/kg. I know it just is a math question, but i´d appreciate if someone could explain it. +  
d_holles  LMAO games NBME plays +1  
hyperfukus  magic math!!!!! how TF r we supposed to know when they round and when they don't like wtf im so pissed someone please tell me step isn't like this...with such precise decimal answers and a calculator fxn you would assume they wanted an actual answer! +1  
jean_young2019  OMG, I've got the 25.92 mg/kg/day, which isn't any of the answer choices listed. So I chose the D 51.8, because 51.8 is double of 25.9......I thought I must have make a mistake during the calculation ...... +2  
atbangura  They purposely did that so if you made a mistake with your conversion like I did, you might end up with 2.5 which was one of the answer choices. SMH +1  
titanesxvi  I did well, but I thought that my mistake was something to do with the conversion and end up choosing 2.5 because it is similar to 25.92 +1  
makinallkindzofgainz  The fact that we pay these people 60 dollars a pop for poorly formatted and written exams boggles my mind, and yet here I am, about to buy Form 24 +2  
qball  Me after plugging in the right numbers and not rounding down : https://i.kym-cdn.com/entries/icons/original/000/028/539/DyqSKoaX4AATc2G.jpg +1  


submitted by sympathetikey(608),

Believe this question is referring to Visceral Leishmaniasis.

gabeb71  The give away is the Fever, Pancytopenia, and Hepatosplenomegaly after being bitten by an insect and developing the sore. +2  
tallerthanmymom  I got this question directly after the other visceral leishmania question and it made me second guess everything I thought I knew. +  
qball  Don't forget they like to infect macrophages. +  


submitted by welpdedelp(137),

It was a type IV HSN reaction, which deals with T cells and that was the only answer that had t cells involved.

yogi  Poison Ivy/ oak /Sumak +  
qball  Uworld Q ID 1133 +  


A normoblast is an immature RBC, so it's elevated in states of increased hematopoiesis.

sympathetikey  Don't mind me. Just sippin my dumb ass soda over here. +25  
someduck3  The term "Normoblast" isn't even in first aid. +17  
link981  NBME testing your knowledge of synonyms. Have to know 15 descriptive words of the same thing I guess. +7  
tinydoc  I wish they would stop making it so every other question I know the answer and I can't find it among the answer choices because they decided to use some medical thesaurus on us. +9  
qball  Metamyelocytes = Precursor to neutrophils Siderophages = hemosiderin-containing macrophage aka heart failure cells +3  
llamastep1  Theres a UWorld question about Parvovirus B19 that mentions "giant pronormoblasts" that helped me make the connection +  


submitted by lfsuarez(114),

This patient presents with a small cell carcinoma which is very common for para neoplastic syndromes. In this case the cancer is causing SIADH. Demeclocyline is a tetracycline antibiotic that is also used to treat SIADH

gabeb71  To add to ^ It is widely used (though off-label in many countries including the United States) in the treatment of hyponatremia (low blood sodium concentration) due to the syndrome of inappropriate antidiuretic hormone (SIADH) when fluid restriction alone has been ineffective. Physiologically, this works by reducing the responsiveness of the collecting tubule cells to ADH. The use in SIADH actually relies on a side effect; demeclocycline induces nephrogenic diabetes insipidus (dehydration due to the inability to concentrate urine). +12  
qball  And for you Sketchy people Demeclocycline is in GI/Endocrine ADH one with the bicycle and that "vaptans" are first line. +  


submitted by rainlad(7),

my approach to this question was to eliminate all the answer choices that mentioned specificity or sensitivity, since the data here did not provide information about any sort of screening test.

that left me with two possible answer choices: I eliminated the one about consistency of other studies, since no other studies were mentioned in the question stem.

not sure if I oversimplified things, but it led me to the right answer!

makinallkindzofgainz  this is exactly how I reasoned through it. Were we correct in our line of thinking? We'll never knooooow +  
qball  But will you ever know on the real thing? +1  


submitted by guillo12(31),

"PV is a neoplastic (clonal) blood disorder with autonomous (EPO-independent) erythroid proliferation. Because of the existence of a negative feedback mechanism, the erthrocytosis in PV down-regulates EPO production and results in below normal serum EPO levels. In contrast, an EPO-driven erythrocytosis characterizes secondary erythrocytosis, and this condition may be associated with either high or normal serum EPO levels."

https://www.mayoclinicproceedings.org/article/S0025-6196(11)63840-8/fulltext

qball  For those that want to know what total red cell mass means in polycythemia and PV read the first paragraph in this article. The hemoglobin and hematocrit do NOT inform you of the total red cell mass. +  


submitted by mousie(126),

Cholera = Fecal oral /Legionnaires = Legonalla pneumo = NO person to person only by inhalation of bacteria contaminated water /Lyme = tick bite /Meningiococcal = sharing respiratory and throat secretions (saliva or spit). Generally, it takes close (for example, coughing or kissing) or lengthy contact to spread these bacteria (CDC) /RMSF = tick bite

smc213  Also, when Meningococcal meningitis is treated ... close contacts are also treated prophylactically whereas the others typically are not. There's also a subunit vaccine for n. meningitis due to high infectivity rate especially in crowded establishments. +4  
dentist  So, Cholera is also p2p but Mening is more likely? +1  
usmlecharserssss  in cholera people to water => water to people +  
qball  Remember the fire sprinklers from Sketchy for M. Meningitis. as respiratory droplets are the easiest to transmit from person to person. +  
drschmoctor  but the poop water comes from people so.... +  
llamastep1  Respiratory dropplets is easier than fecal-oral tho +