NBME 21

Block 1/Question#1
A 24-year-old woman with sickle cell disease comes to the ...
Serum parvovirus B19 IgM antibody test

Block 1/Question#2
A 6-month-old girl is brought to the physician because her ...
GM2

Block 1/Question#3
An investigator is studying the efficacy of distinct vaccine ...
Flagellin

Block 1/Question#4
A 67-year-old man comes to the emergency department because ...
Translation

Block 1/Question#5
A 45-year-old woman is brought to the emergency department 45 ...
Absorption atelectasis

Block 1/Question#6
A normal-appearing 17-year-old girl has never had a menstrual ...
Androgen insensitivity syndrome

Block 1/Question#7
A 30-year-old primigravid woman at 22 weeks' gestation comes ...
Listeria monocytogenes

Block 1/Question#8
A 52-year-old woman is admitted to the hospital because of ...
Speak with the two gynecologists to attempt to coordinate care

Block 1/Question#9
A 53-year-old woman who underwent an operation for breast ...
Breast: antagonist; Uterus: partial agonist

Block 1/Question#10
A 34-year-old woman is brought to the emergency department 30 ...
Primary metabolic acidosis with increased anion gap

Block 1/Question#11
A 27-year-old primigravid woman at 34 weeks' gestation is ...
Schistocytes

Block 1/Question#12
A 25-year-old nulligravid woman comes to the physician ...
Endometrial hyperplasia

Block 1/Question#13
A 25-year-old man develops shortness of breath after moving ...
Decreased alveolar Po2

Block 1/Question#14
A 21-year-old man is brought to the emergency department 45 ...
Streptococcus pneumoniae

Block 1/Question#15
A 35-year-old man comes to the physician because of a 1-day ...
Increased vascular permeability

Block 1/Question#16
A 43-year-old man comes to the physician for a follow-up ...
Aortic

Block 1/Question#17
A 7-year-old girl is brought to a clinic in a developing ...
Methionine

Block 1/Question#18
A 61-year-old woman is brought to the physician by her ...
Donepezil

Block 1/Question#19
A 22-year-old man has had frequent episodes of cutaneous ...
C1 esterase inhibitor (binds activated C1r, C1s)

Block 1/Question#20
A 10-year-old girl develops fever, malaise, and loss of ...
Retrograde transport through nerves

Block 1/Question#21
A 40-year-old man with type 2 diabetes mellitus comes to the ...
Stimulation of the peroxisome proliferator-activated receptor γ

Block 1/Question#22
A 36-year-old man with AIDS elects to participate in a ...
Chemokine

Block 1/Question#23
A 59-year-old man comes to the physician because of a 3-month ...
Foci of keratinization

Block 1/Question#24
A 23-year-old man drinks alcohol heavily on a weekend. Which ...
Fatty change

Block 1/Question#25
A 28-year-old man is brought to the emergency department 30 ...
Dissecting aneurysm

Block 1/Question#26
A 62-year-old man who is a farmer comes to the physician ...
Actinic keratosis

Block 1/Question#27
A 60-year-old man is brought to the emergency department ...
Urethral disruption

Block 1/Question#28
A 47-year-old man is brought to the emergency department by ...
Mixed venous oxygen tension

Block 1/Question#29
A 34-year-old man comes to the physician because of a 2-week ...
Cluster headache

Block 1/Question#30
A newborn has female external genitalia and a 46,XY ...
Dihydrotestosterone

Block 1/Question#31
A 30-year-old woman comes to the office for a follow-up ...
Linoleic acid

Block 1/Question#32
A 50-year-old man has had progressive dyspnea on exertion ...
Usual interstitial pneumonitis

Block 1/Question#33
A 30-year-old man comes to the physician because of a ...
Varicella-zoster virus infection

Block 1/Question#34
A 30-year-old man develops urinary incontinence 2 weeks after ...
Pelvic nerves

Block 1/Question#35
A 7-year-old boy is brought to the physician by his mother ...
Increased blood lead

Block 1/Question#36
A 51-year-old woman comes to the physician because of a ...
Area labeled 'B' (Parietal cell)

Block 1/Question#37
A 35-year-old man with diabetic ketoacidosis has a decrease ...
Serum potassium concentration

Block 1/Question#38
A 47-year-old woman with aplastic anemia is being treated for ...
Amphotericin B

Block 1/Question#39
A 33-year-old woman comes to the physician because of fever, ...
Genital herpes

Block 1/Question#40
A physician prescribes a recently marketed drug for 20 ...
Phase 4

Block 1/Question#41
A 35-year-old woman comes to the physician because of a 2-day ...
Uroporphyrinogen decarboxylase

Block 1/Question#42
A 36-year-old woman undergoes a total hysterectomy and ...
Hyperplasia

Block 1/Question#43
A 52-year-old man is brought to the emergency department 30 ...
Histamine

Block 1/Question#44
A test has been developed to screen for human papillomavirus ...
Predictive value of a positive test

Block 1/Question#45
An 18-year-old man comes to the physician because of a 2-week ...
Pyruvate kinase

Block 1/Question#46
A 66-year-old man is brought to the emergency department ...
Lipopolysaccharide stimulation of toll-like receptor

Block 1/Question#47
A 26-year-old woman (III-2) comes to the physician for ...
50% in females but near 0 in males

Block 1/Question#48
A 44-year-old man is admitted to the hospital because of ...
Increasing cGMP

Block 1/Question#49
An 80-year-old woman comes to the emergency department ...
Hydrochlorothiazide

Block 1/Question#50
A photograph is shown of a myelin-stained cross section of a ...
Loss of sensation to vibration over both feet

Block 2/Question#1
A 27-year-old man comes to the physician for an examination ...
Schizoid

Block 2/Question#2
A 4-year-old girl is conscious but unable to breathe ...
Pseudocholinesterase deficiency

Block 2/Question#3
A 17-year-old boy returns to the locker room after football ...
Apocrine

Block 2/Question#4
An 18-year-old woman comes to the office because of a 2-week ...
Extensor carpi radialis brevis

Block 2/Question#5
A 2-week-old male newborn has a patent ductus arteriosus. ...
Higher than normal left ventricular cardiac output

Block 2/Question#6
A 38-year-old woman comes to the physician because of a ...
Serum calcium concentration

Block 2/Question#7
A 50-year-old man with rheumatoid arthritis comes to the ...
Anemia of chronic disease

Block 2/Question#8
A 55-year-old man is diagnosed with renal artery stenosis. ...
Cortex

Block 2/Question#9
A 40-year-old man is brought to the emergency department 45 ...
Metabolic acidosis and respiratory acidosis

Block 2/Question#10
A 42-year-old woman comes to the physician because of a ...
Rosacea

Block 2/Question#11
A 22-year-old woman, gravida 1, para 1, is brought to the ...
Internal iliac

Block 2/Question#12
A 66-year-old woman comes to the physician because of fever, ...
Diverticulitis

Block 2/Question#13
A 53-year-old woman with gastroesophageal reflux disease ...
Omeprazole

Block 2/Question#14
A 30-year-old woman comes to the office because she is ...
Abnormal brain development

Block 2/Question#15
A 48-year-old man is brought to the emergency department ...
Splenic and left renal

Block 2/Question#16
A 34-year-old woman comes to the physician because of a ...
Atrioventricular bundle

Block 2/Question#17
Scientists have identified the flawed gene that causes about ...
Mismatch repair

Block 2/Question#18
A 34-year-old woman comes to the physician because she has ...
“I’m concerned about how bad you’ve been feeling lately. Have you had any thoughts about death or wanting to be dead?”

Block 2/Question#19
A 3-year-old boy who recently immigrated to the USA is ...
Increased proportions of osteoid

Block 2/Question#20
A 14-year-old girl is brought to the physician by her mother ...
Trichotillomania

Block 2/Question#21
A 35-year-old woman undergoes flexible nasopharyngoscopy ...
Superior to the superior concha

Block 2/Question#22
A 33-year-old woman, gravida 4, para 4, is admitted to the ...
Transfusion-related acute lung injury

Block 2/Question#23
A 4-year-old boy with chronic granulomatous disease is ...
Macrophages producing interleukin-1 (IL-1)

Block 2/Question#24
A 65-year-old man dies in a motor vehicle collision. A ...
Squamous cell carcinoma

Block 2/Question#25
A 54-year-old man comes to the physician for a routine health ...
Area labeled 'F' (Efferent arteriole)

Block 2/Question#26
A healthy 32-year-old woman at 35 weeks' gestation is ...
Birth canal reflex

Block 2/Question#27
A 47-year-old woman with psoriasis comes to the physician for ...
“Most people find it difficult to stick to a routine. How did you do?”

Block 2/Question#28
A 64-year-old woman with type 2 diabetes mellitus and ...
Gemfibrozil

Block 2/Question#29
A healthy 25-year-old man is participating in a study of ...
Alanine

Block 2/Question#30
A 44-year-old man comes to the physician because of ...
Leukotriene C4: increased;
Arachidonic acid: increased;
Prostaglandin H2: decreased;
Prostaglandin E2: decreased


Block 2/Question#31
A 37-year-old man is brought to the emergency department 45 ...
Intercostal

Block 2/Question#32
A 17-year-old boy has the acute onset of lethargy, sore ...
Lymphocytes

Block 2/Question#33
A 68-year-old man comes to the physician because of a 1-month ...
Libido: normal; Nocturnal erections: normal

Block 2/Question#34
A 28-year-old man is brought to the emergency department ...
Inferior rectus and inferior oblique

Block 2/Question#35
A 4-month-old female infant is brought to the emergency ...
Hyponatremia

Block 2/Question#36
An investigator is conducting a study of antiretroviral ...
Enfuvirtide

Block 2/Question#37
A 17-year-old boy is evaluated for constitutional delay in ...
Craniopharyngioma

Block 2/Question#38
A 63-year-old man with bladder cancer starts treatment with ...
Tubulin polymerization stabilization

Block 2/Question#39
A 64-year-old man with bronchospastic pulmonary disease ...
Enhanced action of the agonist at β-adrenergic receptors

Block 2/Question#40
Acetaminophen and nonsteroidal antiinflammatory agents reduce ...
Prostaglandin E2

Block 2/Question#41
A 75-year-old woman has the sudden onset of Horner syndrome ...
Posterior inferior cerebellar

Block 2/Question#42
A 26-year-old man with HIV infection comes to the physician ...
Penicillin

Block 2/Question#43
A 78-year-old woman is brought to the emergency department by ...
Embolectomy

Block 2/Question#44
A 75-year-old man has the sudden onset of partial loss of ...
Parietal lobe, left

Block 2/Question#45
A 3-year-old boy is brought to the emergency department ...
Synthesis of factor X (Stuart factor)

Block 2/Question#46
An 8-year-old girl is brought to the physician for a ...
“Your daughter’s development is normal.”

Block 2/Question#47
A 55-year-old woman comes to the physician because of a ...
Increased parathyroid hormone

Block 2/Question#48
A 75-year-old man has fever, back pain, and pain on ...
Enterococcus faecalis

Block 2/Question#49
A 6-year-old girl is brought to the physician by her mother ...
Poxvirus

Block 2/Question#50
A 65-year-old woman comes to the emergency department because ...
Lung and common carotid artery

Block 3/Question#1
A 30-year-old woman develops dimness of vision
Ethambutol

Block 3/Question#2
A 40-year-old man with interstitial pulmonary fibrosis has a ...
Increased radial traction on airways

Block 3/Question#3
A 55-year-old African American man with hypertension is asked ...
Tell the patient that he can change his mind about participating

Block 3/Question#4
A clinical trial is conducted to compare the efficacy of a ...
Surgical procedure group: 400; Medical management group: 400

Block 3/Question#5
A 70-year-old woman is found to have persistent fever despite ...
Candida albicans

Block 3/Question#6
A 40-year-old African American woman comes to the physician ...
1,25-Dihydroxycholecalciferol

Block 3/Question#7
A 65-year-old man comes to the physician because of a 1-month ...
DNA fragmentation

Block 3/Question#8
A 55-year-old woman is brought to the emergency department by ...
Mammillary bodies

Block 3/Question#9
A 75-year-old woman is brought to the emergency department ...
Shrunken eosinophilic (red) neurons

Block 3/Question#10
A 30-year-old man has had intermittent severe lower abdominal ...
Cysteine

Block 3/Question#11
A 50-year-old man is found dead in bed at home. His family ...
Arrhythmia

Block 3/Question#12
A 55-year-old man with hypertension comes to the physician ...
Left renal artery atherosclerosis

Block 3/Question#13
A 40-year-old woman comes to the physician for an initial ...
Antagonizes VLDL-cholesterol secretion

Block 3/Question#14
A 35-year-old man is brought to the emergency department ...
Activation of adenylyl cyclase

Block 3/Question#15
A 47-year-old man has jaundice. Laboratory findings include ...
Obstruction of the bile duct

Block 3/Question#16
A 16-year-old boy is brought to the physician because of a ...
Exercise-induced asthma

Block 3/Question#17
A 66-year-old woman with pancreatic cancer comes to the ...
Short gastric

Block 3/Question#18
An 83-year-old man comes to the physician because of a 3-day ...
Bullous pemphigoid antigen

Block 3/Question#19
A 25-year-old woman develops increasing shortness of breath ...
Four-chamber dilation

Block 3/Question#20
A 68-year-old woman has had a fever and shortness of breath ...
Reactive granulocytosis

Block 3/Question#21
A screening program is instituted for detection of vaginal ...
10%

Block 3/Question#22
A 9-year-old boy has mild mental retardation and a 4-year ...
Rhabdomyoma

Block 3/Question#23
A 43-year-old woman dies after a 10-year illness ...
Area labeled ‘C’ (Caudate nucleus)

Block 3/Question#24
Diastolic blood pressures are obtained in two groups of 100 ...
Median of group Y: higher; Mode of group Y: higher

Block 3/Question#25
A 32-year-old woman comes to the physician because her sister ...
Dysplastic nevi

Block 3/Question#26
A 19-year-old woman comes to the office because of a 1-month ...
Descending colon

Block 3/Question#27
A 55-year-old woman with a benign nodule in the left lobe of ...
External carotid

Block 3/Question#28
A 1-year-old girl is admitted to the hospital because of a ...
Disruption of the secondary structure of collagen molecules

Block 3/Question#29
A 34-year-old man is evaluated after becoming light-headed ...
Number of impulses from carotid baroreceptor: decreased;
Sympathetic efferent activity: increased;
Parasympathetic efferent activity: decreased


Block 3/Question#30
A 41-year-old man comes to the physician because of a 6-week ...
Abduction of the upper extremity

Block 3/Question#31
A 28-year-old woman at 18 weeks' gestation has palpitations. ...
Free T4

Block 3/Question#32
A 72-year-old man comes to the physician because of a 2-week ...
Bleomycin

Block 3/Question#33
Left radial arterial and venous blood samples are drawn from ...
HCO3 transported in the plasma

Block 3/Question#34
A 39-year-old woman with rheumatoid arthritis develops ...
Membranous glomerulonephritis

Block 3/Question#35
A 63-year-old woman comes to the physician because of a 5-day ...
Increased resting cardiac output

Block 3/Question#36
Which of the following best explains why the use of an ...
Myeloma cells do not have membrane-bound surface immunoglobulin

Block 3/Question#37
A 5-year-old boy who has homocystinuria improves with ...
The line on the graph labeled ‘B’

Block 3/Question#38
A 28-year-old man develops a temperature of 39.9°C (103.8°F) ...
Granulocyte colony-stimulating factor

Block 3/Question#39
A 74-year-old woman with mild dementia is admitted to the ...
Inability to understand the severity and prognosis of her medical condition

Block 3/Question#40
A 65-year-old woman undergoes surgical repair of an aneurysm ...
Area labeled ‘A’ (Cranial nerve 3)

Block 3/Question#41
A 75-year-old woman comes to the physician's office because ...
Major depressive disorder

Block 3/Question#42
A 27-year-old primigravid woman at 39 weeks' gestation is ...
Shoulder dystocia

Block 3/Question#43
An undernourished 70-year-old man has fever, night sweats, ...
Interferon-γ

Block 3/Question#44
A 23-year-old woman develops persistent sneezing each year in ...
Stabilization of mast cell membranes

Block 3/Question#45
A 28-year-old man comes to the physician for evaluation of ...
Fructose

Block 3/Question#46
A 38-year-old woman comes to the physician because of a ...
Patent foramen ovale

Block 3/Question#47
A 48-year-old man comes to the physician because of ...
Increased intestinal iron absorption

Block 3/Question#48
A 29-year-old woman comes to the physician because of a ...
Baclofen

Block 3/Question#49
The gene that codes for a protein normally found in the ...
Deletion of a hydrophobic amino acid sequence from the N terminus

Block 3/Question#50
A 32-year-old woman comes to the emergency department because ...
Arthropod vector

Block 4/Question#1
A 50-year-old woman has azotemia. Renal ultrasonography shows ...
Uterine cervix

Block 4/Question#2
A 23-year-old woman comes to the student health center ...
Obliterative endarteritis with lymphocytes and plasma cells

Block 4/Question#3
A study was performed that evaluated the relationship between ...
Odds ratio

Block 4/Question#4
The FOXO transcription factor responds to insulin signaling ...
Nuclear/cytoplasmic shuttling: yes;
Serine phosphorylation: yes
Ubiquitin-mediated proteolysis: no


Block 4/Question#5
An 11-year-old boy has had persistent pain in his right knee ...
Lung

Block 4/Question#6
A 55-year-old man comes to the physician because of a 2-month ...
Cortisol

Block 4/Question#7
A 14-year-old boy is brought to the physician by his mother ...
Inhaled glue

Block 4/Question#8
A 70-year-old woman has had recurrent pneumonia, fatigue, and ...
Euthyroid sick syndrome

Block 4/Question#9
A 60-year-old woman with psoriasis comes to the physician ...
Porphyria cutanea tarda

Block 4/Question#10
A 64-year-old man is evaluated for cough, dyspnea, and chest ...
Hyponatremia

Block 4/Question#11
A study is conducted on patients with asthma to compare a new ...
If the treatment really changes the mean asthma score by 0.4, there is an 80% chance that a study of this size will find a p-value < 0.05

Block 4/Question#12
A 24-year-old man with a history of drug abuse has nausea, ...
Heroin

Block 4/Question#13
A 4-month-old boy is diagnosed with a rare autosomal ...
Dilated rough endoplasmic reticulum

Block 4/Question#14
A 25-year-old woman has a 3-week history of bleeding gums ...
Autoantibodies against platelet glycoproteins

Block 4/Question#15
A 5-year-old boy is brought to the physician for a well-child ...
Lack of choroidal pigment deposition in the macula

Block 4/Question#16
A 40-year-old woman who had pneumonia due to Streptococcus ...
Surfactant

Block 4/Question#17
A 48-year old man is referred for evaluation of possible ...
Increase in width

Block 4/Question#18
A previously healthy 4-week-old male newborn is brought to ...
Pyloric stenosis

Block 4/Question#19
A 45-year-old woman comes to the emergency department because ...
Hepatopancreatic ampulla

Block 4/Question#20
A 7-month-old boy is brought to the physician 2 days after ...
46,XY

Block 4/Question#21
A 47-year-old man is treated with colchicine for acute gouty ...
Tubulin polymerization

Block 4/Question#22
A 57-year-old woman is brought to the emergency department ...
Ninth

Block 4/Question#23
An investigator is studying the regulation of pulmonary ...
Intravenous infusion of 0.9% saline for 5 minutes

Block 4/Question#24
A 56-year-old man undergoes a renal transplant. Five minutes ...
IgG plus complement

Block 4/Question#25
An 80-year-old woman cannot concentrate her urine above 450 ...
2.0

Block 4/Question#26
The immunosuppressive agent cyclosporin A (CsA) is a potent ...
Interleukin-2 (IL-2) gene transcription

Block 4/Question#27
A 65-year-old woman is being treated in the hospital for ...
“The two of you seem to have a very important relationship. Of course you may stay together.”

Block 4/Question#28
A 56-year-old man undergoes surgical resection of the ...
Release of cholecystokinin

Block 4/Question#29
A 22-year-old man comes to the physician because of a 2-month ...
Formation of destructive free radicals

Block 4/Question#30
A 5-year-old boy is admitted to the hospital because of ...
ApoC-II

Block 4/Question#31
A 48-year-old woman comes to the physician because of a ...
Paracrine stimulation of osteoclasts by osteoblasts

Block 4/Question#32
A 19-year-old college student says he hears voices." He was ...
Risperidone

Block 4/Question#33
A female newborn delivered at 26 weeks' gestation is found to ...
Retina

Block 4/Question#34
A healthy 8-year-old boy is brought to the physician by his ...
Stimulation of the release of biogenic amine neurotransmitters

Block 4/Question#35
A 50-year-old woman is admitted to the hospital because of a ...
Didanosine (ddI)

Block 4/Question#36
A 45-year-old man comes to the physician because of ...
Chondrosarcoma

Block 4/Question#37
A 66-year-old right-handed woman develops the acute onset of ...
Area labeled 'B' (Internal capsule)

Block 4/Question#38
A 62-year-old woman is brought to the physician by her ...
Instruct the patient to keep notes and lists to help her memory

Block 4/Question#39
A 46-year-old man comes to the physician because of a 2-month ...
1/15

Block 4/Question#40
A study is conducted to assess the normal mean serum urea ...
500 Men from a list of patients scheduled to be examined by a urologist

Block 4/Question#41
A 66-year-old man with stage IV colon cancer comes to the ...
Loperamide

Block 4/Question#42
A 20-year-old primigravid woman at 12 weeks' gestation comes ...
Multifactorial

Block 4/Question#43
A 4-year-old boy falls and lacerates his lower leg to the ...
Formation of fibrin clot

Block 4/Question#44
A 28-year-old woman with chronic renal failure (creatinine ...
Furosemide

Block 4/Question#45
During an experiment, an investigator observes that glutamate ...
NMDA receptors are blocked by Mg2+ at the resting membrane potential

Block 4/Question#46
A 14-year-old girl is brought to the physician for a ...
TP53

Block 4/Question#47
While lifting weights, a 24-year-old man develops a painful ...
Strangulation

Block 4/Question#48
A 75-year-old man with dementia, Alzheimer type, is brought ...
Encourage the family to come to a consensus based on their perception of the patient's wishes

Block 4/Question#49
A 76-year-old man comes to the physician because of a 2-week ...
Left thalamus

Block 4/Question#50
A 19-year-old woman is brought to the emergency department 30 ...
Scaphoid

Recent comments ...

... mcl made a comment on nbme21/block1/q#2 (A 6-month-old girl is brought to the physician...)
 +0  upvote downvote
submitted by mcl(0)

Patient most likely has Tay-Sachs disease. This figure nicely shows the biochemical pathway. Recall that both Tay-Sachs and Neimann Pick disease present with a cherry red spot on fundoscopy, but Tay Sachs lacks the hepatosplenomegaly seen in NP.

... cantaloupe5 made a comment on nbme21/block1/q#3 (An investigator is studying the efficacy of distinct...)
 +0  upvote downvote
submitted by cantaloupe5(5)

Capsular polysaccharide vaccines are often conjugated to proteins to improve immunogenicity. Flagellin is the only answer choice that's a protein.

... wasabilateral made a comment on nbme21/block1/q#3 (An investigator is studying the efficacy of distinct...)
 +0  upvote downvote
submitted by wasabilateral(0)

I think they want you to think about how conjugate vaccine is made: polysaccharide + protein fragment (to induce T dependent immune response). Only flagellin is a protein (or at least sounds like one) in the option list.

... haliburton made a comment on nbme21/block1/q#4 (A 67-year-old man comes to the emergency department...)
 +0  upvote downvote
submitted by haliburton(0)

EF2 is translational elogation factor 2, which is necessary for protein synthesis.

... haliburton made a comment on nbme21/block1/q#5 (A 45-year-old woman is brought to the emergency...)
 +0  upvote downvote
submitted by haliburton(0)

wikipedia (apologies): The atmosphere is composed of 78% nitrogen and 21% oxygen. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis.

I chose cardiogenic edema, but I believe this is incorrect because there is no heart failure risk at this time, so the purpose of the PEEP is certainly not to push out fluid.

... hayayah made a comment on nbme21/block1/q#11 (A 27-year-old primigravid woman at 34 weeks'...)
 +0  upvote downvote
submitted by hayayah(54)

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.

... mcl made a comment on nbme21/block1/q#12 (A 25-year-old nulligravid woman comes to the...)
 +0  upvote downvote
submitted by mcl(0)

PCOS is associated with abnormal production of sex steroids, including dysfunction of estrogen production and progesterone. Chronically elevated levels of estrogen can cause endometrial hyperplasia.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3917599/

... haliburton made a comment on nbme21/block1/q#13 (A 25-year-old man develops shortness of breath after...)
 +0  upvote downvote
submitted by haliburton(0)

FA 2017: Chronic hypoxic pulmonary vasoconstriction results in pulmonary hypertension and RVH.

... mcl made a comment on nbme21/block1/q#16 (A 43-year-old man comes to the physician for a...)
... mcl made a comment on nbme21/block1/q#17 (A 7-year-old girl is brought to a clinic in a...)
 +0  upvote downvote
submitted by mcl(0)

Methionine is an essential amino acid. All others listed are not.

scalpelofthenorth  Pg 81 Tyrosine is listed as an essential AA. Should be tryptophan for those who got this wrong like me.
... mcl made a comment on nbme21/block1/q#19 (A 22-year-old man has had frequent episodes of...)
 +0  upvote downvote
submitted by mcl(0)

Patient may have hereditary angioedema, which is associated with "recurrent attacks of intense, massive, localized subcutaneous edema involving the extremities, genitalia, face, or trunk, or submucosal edema of upper airway or bowels". The article goes on to say "C1-esterase inhibitor works directly on the complement and contact plasma cascades to reduce bradykinin release" which is also probably good to know.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3666183/

... est88 made a comment on nbme21/block1/q#20 (A 10-year-old girl develops fever, malaise, and loss...)
 +1  upvote downvote
submitted by est88(4)

Rabies Virus (rhabdoviridae)

Fever, encephalitis, drooling

... haliburton made a comment on nbme21/block1/q#20 (A 10-year-old girl develops fever, malaise, and loss...)
 +0  upvote downvote
submitted by haliburton(0)

Rabies attacks the nicotinic Acetylcholine receptor, and travels retrograde via dynein motors after binding AChR, according to FA.

... hayayah made a comment on nbme21/block1/q#22 (A 36-year-old man with AIDS elects to participate in...)
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submitted by hayayah(54)

Cysteine-cysteine chemokine receptor 5 (CCR5) is a protein found on the surface of CD4 cells.

... thechurchofbobbyhill made a comment on nbme21/block1/q#23 (A 59-year-old man comes to the physician because of...)
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submitted by thechurchofbobbyhill(0)

Hi- I don't have an explanation for this but I am also curious as to why this was the answer.

... est88 made a comment on nbme21/block1/q#23 (A 59-year-old man comes to the physician because of...)
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submitted by est88(4)

I believe its Squamous cell carcinoma. Its centrally located, smoker, and its a hilar mass. Keratin pearls.

... vonhippelindau made a comment on nbme21/block1/q#24 (A 23-year-old man drinks alcohol heavily on a...)
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submitted by vonhippelindau(0)

It’s acute alcohol consumption so fatty change more likely. Cellular swelling indicates alcoholic hepatitis which requires chronic alcohol consumption (See FA 2019 pg 385). At least that’s the logic I used to pick fatty change.

... hayayah made a comment on nbme21/block1/q#28 (A 47-year-old man is brought to the emergency...)
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submitted by hayayah(54)

Mixed venous oxygen saturation (SvO2) is measured in the pulmonary artery. SvO2 samples the true mixed venous blood leaving the right heart. Measurement of mixed venous oxygen saturation (SvO2) from the pulmonary artery has been advocated as an indirect index of tissue oxygenation.

In cardiogenic shock you have decreased CO --> decreased O2 delivery --> decreased SvO2.

... mcl made a comment on nbme21/block1/q#30 (A newborn has female external genitalia and a 46,XY...)
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submitted by mcl(0)

Per p608 in FA 2019, SRY on Y chromosome results in development of testes. DHT results in development of male external genitalia (and the prostate).

... haliburton made a comment on nbme21/block1/q#31 (A 30-year-old woman comes to the office for a...)
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submitted by haliburton(0)

there are two essential fatty acids: linoleic = omega 6, and alpha-linoleic = omega 3.

... mcl made a comment on nbme21/block1/q#36 (A 51-year-old woman comes to the physician because...)
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submitted by mcl(0)

This image is very helpful.

... halux made a comment on nbme21/block1/q#42 (A 36-year-old woman undergoes a total hysterectomy...)
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submitted by halux(1)

can some one please explain why is the hyperplasia?

beeip  Loss of negative feedback from resected ovaries leads to gonadotroph hyperplasia.
halux  so, the explanation is that in the absence of Estrogen negative feedback inhibition to LH and FSH, this leads to Gonadotrophs Hyperplasia at the Pituitary resulting in elevated LH and FSH secretion levels? I get busted by this one :/ Thanks in advance!
... beeip made a comment on nbme21/block1/q#42 (A 36-year-old woman undergoes a total hysterectomy...)
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submitted by beeip(7)

[moved to subcomment]

... halux made a comment on nbme21/block1/q#42 (A 36-year-old woman undergoes a total hysterectomy...)
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submitted by halux(1)

[moved to subcomment]

... cantaloupe5 made a comment on nbme21/block1/q#45 (An 18-year-old man comes to the physician because of...)
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submitted by cantaloupe5(5)

For this one you just had to know the glycolysis pathway. Stem told you 2,3-BPG is elevated, which is upstream of pyruvate kinase.

... est88 made a comment on nbme21/block1/q#45 (An 18-year-old man comes to the physician because of...)
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submitted by est88(4)

Pyruvate Kinase defect leads to decreased ATP leading to rigid RBCs and extra vascular hydrolysis. Increased levels of 2,3-BPG decreases hemoglobin affinity for O2.

... drmantistoboggan4 made a comment on nbme21/block1/q#47 (A 26-year-old woman (III-2) comes to the physician...)
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submitted by drmantistoboggan4(1)

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.

... haliburton made a comment on nbme21/block1/q#50 (A photograph is shown of a myelin-stained cross...)
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submitted by haliburton(0)

this is a cervical spinal cord section. the cuneate fasciculus is intact (UE) vibration and proprioception, but the white section is the gracile fasciculus (LE) and is damaged. I think the lateral portion that is uneven is just natural/artifact.

... haliburton made a comment on nbme21/block2/q#2 (A 4-year-old girl is conscious but unable to breathe...)
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submitted by haliburton(0)

https://ghr.nlm.nih.gov/condition/pseudocholinesterase-deficiency

"People with pseudocholinesterase deficiency may not be able to move or breathe on their own for a few hours after [fast-acting drugs, such as succinylcholine and mivacurium] are administered.

... lnsetick made a comment on nbme21/block2/q#3 (A 17-year-old boy returns to the locker room after...)
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submitted by lnsetick(1)
  • 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
... moneysacs made a comment on nbme21/block2/q#5 (A 2-week-old male newborn has a patent ductus...)
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submitted by moneysacs(0)

Why is does a PDA after birth result in "higher than normal left ventricular cardiac output" over increased "right ventricular PO2"? Does the pulm artery --> aorta shunt become reversed after birth, so higher oxygen aorta blood would flow back into the right ventricle? I get that more blood would be pumped to the left ventricle, resulting in RVH/LVH, but don't understand the O2 bit.

... heavy_neighborhood made a comment on nbme21/block2/q#5 (A 2-week-old male newborn has a patent ductus...)
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submitted by heavy_neighborhood(1)

PDA flows from the Aorta ==> Pulmonary arteries, by passing the RV so there is no change in O2 in the RV.

... jotajota94 made a comment on nbme21/block2/q#5 (A 2-week-old male newborn has a patent ductus...)
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submitted by jotajota94(0)

PDA flows from aorta to pulmonary artery decreasing afterload. Therefore cardiac output increases

... cantaloupe5 made a comment on nbme21/block2/q#6 (A 38-year-old woman comes to the physician because...)
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submitted by cantaloupe5(5)

Recurrent kidney stones should include hyperparathyroidism on your differential, couple that with gastrinoma and you’re looking at MEN 1. Lipomas are also associated with MEN 1.

... _pusheen_ made a comment on nbme21/block2/q#8 (A 55-year-old man is diagnosed with renal artery...)
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submitted by _pusheen_(0)

I think this one is literally just asking what part of the kidney will be the most poorly perfused. That part would have the most renin. Also, the medulla doesn’t have JG cells so I guess that’s another reason why it couldn’t have the most renin.

sklawpirt  Exactly, it has to do with where in the kidney renin is released and requires a bit of knowledge of the artery branches that give rise to the afferent arteriole in the first place and where this branch point is located. http://anatomyforme.blogspot.com/2008/05/histology-of-kidney-lot-to-process.html Where renin production occurs in JGA cells, EPO production occurs in the renal peritubular interstitium (especially the proximal renal tubule, corext and some of the outer medulla.) Thus with the same questions stem it might ask where is concentration of EPO the highest? [And it would still be the cortex, with lower concentrations in the outer medulla, lowest concentration in the inner medulla, and none found in the papilla or renal pelvis.
hayayah  Actually, the renal medulla receives significantly less blood flow than renal cortex. So the medulla is the one that's very sensitive to hypoxia and vulnerable to ischemic damage. I don't think this question is related to "what area is the most poorly perfused." It's just knowing that renal artery stenosis is going to decrease blood flow to the kidney. JG cells sense the decrease in perfusion pressure and secrete renin. Knowing that renin is produced by the JG cells and that JG cells are in the cortex should be enough to answer this question.
... hayayah made a comment on nbme21/block2/q#8 (A 55-year-old man is diagnosed with renal artery...)
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submitted by hayayah(54)

Renal artery stenosis is going to decrease blood flow to the kidney. JG cells sense the decrease in perfusion pressure and secrete renin.

Renin is produced by the JG cells, JG cells are in the cortex (they are modified smooth muscle of the afferent arteriole).

... mcl made a comment on nbme21/block2/q#9 (A 40-year-old man is brought to the emergency...)
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submitted by mcl(0)

When working on acid/base disorders, it helps to look systematically at the following: (1) pH (which sadly was not given in this problem), (2) figure out which problem is primary by looking at PaCO2 and bicarb, and (3) look for any compensation (which the question doesn't ask but still).

Here, we see that the CO2 is high on the ABG. This means that patient is hypoventilating since levels of CO2 are ventilation dependent, and also that patient has respiratory acidosis. Also, bicarb is low, which implies that it's being "soaked up" by metabolic acidosis.

... porky_pork_chop made a comment on nbme21/block2/q#12 (A 66-year-old woman comes to the physician because...)
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submitted by porky_pork_chop(0)

My reasoning was that it’d be diverticulitis due to the more acute history of presentation: “fever, chills, LLQ pain for 1 day.” Crohn’s should have a longer timeline of presentation; although the skip lesions made this one really tricky. Not sure how the gross pathology photograph plays in though ...

... nuts4med made a comment on nbme21/block2/q#12 (A 66-year-old woman comes to the physician because...)
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submitted by nuts4med(0)

I was thinking Chron’s because of the narrowing of the lumen and the picture seemed like there was creeping fat. Now that I think about it though, the LLQ and constipation should have led towards diverticulitis pretty quickly.

... logical_champion made a comment on nbme21/block2/q#12 (A 66-year-old woman comes to the physician because...)
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submitted by logical_champion(0)

I think it is good to note the demographics. The patient is female and old. That, along with the constipation, made me lean more towards diverticulitis. IBD usually develops in younger persons.

... vonhippelindau made a comment on nbme21/block2/q#12 (A 66-year-old woman comes to the physician because...)
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submitted by vonhippelindau(0)

I picked Crohn’s too. I think the severe constipation over 5 years distracted me.

haliburton  i think it is critical to remember that constipation is what caused the diverticulosis.
... hayayah made a comment on nbme21/block2/q#14 (A 30-year-old woman comes to the office because she...)
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submitted by hayayah(54)

Cretinism (congenital hypothyroidism) is the most common cause of treatable mental disability. Causes poor brain development.

... hayayah made a comment on nbme21/block2/q#16 (A 34-year-old woman comes to the physician because...)
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submitted by hayayah(54)

This pt has an ASD which is a "hole" between the LA and RA. Fixing it could damage the AV bundles.

... hayayah made a comment on nbme21/block2/q#19 (A 3-year-old boy who recently immigrated to the USA...)
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submitted by hayayah(54)

This pt has osteomalacia / rickets (since he's a kiddo). Caused by defective mineralization of osteoid (osteomalacia) or cartilaginous growth plates (rickets, only in children).

Most commonly d/t Vitamin D deficiency.

Children with rickets have pathologic bow legs (genu varum), bead-like costochondral junctions (rachitic rosary), craniotabes (soft skull).

  • Dec. Vitamin D (normal function is to reabsorb Ca2+ and PO4)

  • Dec. serum Ca2+

  • Dec.  serum PO4

  • Inc. PTH

... mattfoley_govtcheese made a comment on nbme21/block2/q#20 (A 14-year-old girl is brought to the physician by...)
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submitted by mattfoley_govtcheese(1)

The clues for trichotillomania were the death of her grandmother suddenly, since trichotillomania is often stress-induced. I also narrowed it down by it saying the hair was in different growth stages in the patchy areas, which makes sense if she’s plucking them out at different times.

Telogen effluvium is most common in middle-aged women, so she doesn’t fit the profile (but you’re right about it being caused by stress).

... haliburton made a comment on nbme21/block2/q#21 (A 35-year-old woman undergoes flexible...)
... mattfoley_govtcheese made a comment on nbme21/block2/q#24 (A 65-year-old man dies in a motor vehicle collision....)
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submitted by mattfoley_govtcheese(1)

My choice for Squamous Cell Carcinoma was guided by the central location of the tumor. To me, that didn’t look like the cavity you’d get with abscess but a huge tumor.

... lnsetick made a comment on nbme21/block2/q#24 (A 65-year-old man dies in a motor vehicle collision....)
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submitted by lnsetick(1)

I don’t think it was cavitary; I think that was just the bronchus. I think abscesses tend to be smaller, and wouldn’t affect the surrounding parenchyma much. I wasn’t super confident in picking squamous cell carcinoma, but I did know that squamous cell carcinoma tends to be a centrally-located lung tumor.

... hayayah made a comment on nbme21/block2/q#26 (A healthy 32-year-old woman at 35 weeks' gestation...)
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submitted by hayayah(54)

Stretch or dilation of the cervix and vagina are strong stimuli for oxytocin secretion, mediated by neural pathways called the Ferguson reflex.

Article: https://www.sciencedirect.com/topics/neuroscience/ferguson-reflex

... haliburton made a comment on nbme21/block2/q#28 (A 64-year-old woman with type 2 diabetes mellitus...)
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submitted by haliburton(0)

FA 2017: Fibrate ADRs include myopathy increased risk with statins, cholesterol gallstones

... frimmy_11 made a comment on nbme21/block2/q#29 (A healthy 25-year-old man is participating in a...)
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submitted by frimmy_11(-2)

Muscle protein breaks down into the amino acid alanine which enters Cahill Cycle to form glucose ...

... volcanobuns made a comment on nbme21/block2/q#29 (A healthy 25-year-old man is participating in a...)
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submitted by volcanobuns(0)

@frimmy_11 Why would protein break down after only 20 hours? Shouldn’t fat be the major contributor now? Also if protein is being used, then why isn’t valine the choice? It’s also glucogenic.

... assoplasty made a comment on nbme21/block2/q#29 (A healthy 25-year-old man is participating in a...)
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submitted by assoplasty(3)

Fats are ketogenic (except odd chain FA), so they produce ketones for energy production (Acetyl-CoA) rather than glucose. If the question asked what the primary source of energy production was, it would still be glycogen (and not ketones), because this is within 24 hours. However after 24 hours the answer could be ketone bodies. Regardless, the question specifically said the pt had a serum glucose of 100, indicating that we are looking for something that provides a substrate for gluconeogenesis.

During periods of starvation, substrates for gluconeogenesis come from two sources: (1) breakdown of existing muscle, or (2) via odd-chain FA through propionyl-CoA. (*Valine also feeds into propionyl CoA, but is not involved during starvation --> see below)

(1) The alanine-pyruvate cycle provides this (glutamine in muscle + pyruvate --> alanine --> goes to liver --> transamination to alpha-ketoglutorate --> pyruvate is separated from glutamine --> glutamine goes to urea cycle, pyruvate goes on to gluconeogenesis). Lactate can also be used (this could have been a right answer if it were listed).

(2) Odd chain FAs are also glucogenic, but stearic acid (provided in the answer choice) isn’t odd chain, so it is only ketogenic and can be ruled out.

Although valine (and other branched a.a.) feed into Propionyl-CoA, they are not used in starvation because starvation strictly relies on hepatic gluconeogenesis. These a.a. are not metabolized in the liver because the liver lacks branched-chain a.a. transferase enzyme. In First Aid, Biochem section, under Fasting/Starvation, in both the “fasting state” (which is within the time frame of this question), or the “starvation state,” both utilize hepatic gluconeogenesis. My assumption is that valine is used during regular metabolism, and not during periods of starvation.

... hayayah made a comment on nbme21/block2/q#29 (A healthy 25-year-old man is participating in a...)
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submitted by hayayah(54)

P. 91 of FA has a quick explanation for this!

Basically once you're in a starving state there's still hepatic gluconeogenesis going on (as well as using FFA) but the gluconeogenesis is coming from peripheral tissue lactate and alanine.

... mcl made a comment on nbme21/block2/q#30 (A 44-year-old man comes to the physician because of...)
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submitted by mcl(0)

This is a pretty good figure showing the conversion of membrane phospholipids to arachidonic acid/leukotrienes etc.

Blockade of COX enzyme by ibuprofen results in decreased production of prostaglandins H2 and E2, while causing the precursors to "back up" (increased arachidonic acid). This, in turn, results in increased production of leukotrienes.

... vlodkadrinker made a comment on nbme21/block2/q#31 (A 37-year-old man is brought to the emergency...)
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submitted by vlodkadrinker(1)

why? like does my med school suck or am I just that dumb cuz we never learned anything like this

sklawpirt  I think its just that the patient is CONSCIOUSLY experiencing chest pain. Because he is consciously feeling the pain and would be able to directly point to it (and that it is not referred visceral pain) it has to be a somatic afferent nerve fiber. This narrows it down exclusively to the intercostal nerve exc;usively. https://en.wikipedia.org/wiki/Intercostal_nerves IMportant to the patients "right sided chest pain" is his history of MVA and x-ray confirming multiple rib fractures. I think this is correct? Does that make sense ? All of the other choices do not carry SA fibers in that area
... hayayah made a comment on nbme21/block2/q#31 (A 37-year-old man is brought to the emergency...)
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submitted by hayayah(54)

With this question, I think they want you to recognize that the patient isn't having chest pain related to the heart. They emphasize several rib fractures and a pneumothorax but don't indicate any heart damage (lack of adventitious sounds = no pulmonary edema indicated or a lung issue related to heart problem).

The pericarditis is what's innervated by the phrenic n. Seeing as how his heart is fine, the fractured ribs are probably what are causing him pain via the intercostal nerves.

... haliburton made a comment on nbme21/block2/q#33 (A 68-year-old man comes to the physician because of...)
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submitted by haliburton(0)

from AAFP ED of mixed organic and psychogenic origin is common. Psychogenic causes are more likely when the patient has normal erections with masturbation or when nocturnal penile tumescence is normal.

... haliburton made a comment on nbme21/block2/q#35 (A 4-month-old female infant is brought to the...)
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submitted by haliburton(0)

This is water intoxication. https://www.ncbi.nlm.nih.gov/pubmed/1877579

... wasabilateral made a comment on nbme21/block2/q#39 (A 64-year-old man with bronchospastic pulmonary...)
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submitted by wasabilateral(0)

This is what I thought but not sure if it’s correct. There is a UWorld q where it describes co-administration of cortisol and epinephrine. Cortisol significantly enhances the effect of epi because cortisol has a permissive effect on maintaining the adrenergic receptors.

... 5thgencephalosporin made a comment on nbme21/block2/q#39 (A 64-year-old man with bronchospastic pulmonary...)
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submitted by 5thgencephalosporin(0)

“The combination of a long-acting beta 2 agonist (LABA) and an inhaled corticosteroid is more efficacious in asthma and [COPD] than [...] either alone. Corticosteroids may regulate beta 2 receptor function by increasing expression of the receptor, restoring G-protein/beta 2 receptor coupling, and inhibiting beta 2 receptor downregulation.”

https://www.ncbi.nlm.nih.gov/pubmed/16113435

... hayayah made a comment on nbme21/block2/q#44 (A 75-year-old man has the sudden onset of partial...)
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submitted by hayayah(54)

lower quadrantanopia: parietal lesion

vs upper quadrantanopia = temporal lesion

mcl  also, to differentiate whether it is the left or right parietal lobe, recall that stimuli from the left visual field hits the nasal side of the left retina and the temporal side of the right retina, then goes to the right side of the brain. [This figure](https://operativeneurosurgery.com/lib/exe/fetch.php?w=600&tok=856a37&media=optictract.jpg) is helpful.
... mcl made a comment on nbme21/block2/q#45 (A 3-year-old boy is brought to the emergency...)
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submitted by mcl(0)

Not sure if this is the right way to think about it, but if PT and PTT are both prolonged, this most likely means there is a problem with the common pathway (aka factor X).

... hayayah made a comment on nbme21/block2/q#47 (A 55-year-old woman comes to the physician because...)
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submitted by hayayah(54)

Secondary hyperparathyroidism (usually d/t chronic renal failure).

Lab findings include ↑ PTH (response to low calcium), ↓ serum calcium (renal failure), ↑ serum phosphate (renal failure), and ↑ alkaline phosphatase (PTH activating osteoBlasts).

haliburton  also remember that in renal failure, 1-alpha-hydroxylase activity is down, so there will be less activation of 25-hydroxycholecalciferol to 1,25-hydroxycholecalciferol, which is a key mechanism causing hypocalcemia.
... hayayah made a comment on nbme21/block2/q#50 (A 65-year-old woman comes to the emergency...)
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submitted by hayayah(54)

Catheter placement:

https://aneskey.com/wp-content/uploads/2016/08/image00804.jpeg

Recall that the lung apex extends above the first rib.

... mcl made a comment on nbme21/block3/q#1 (A 30-year-old woman develops dimness of vision)
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submitted by mcl(0)

Page 250 FA - Ethambutol is associated with visual disturbances (changes in color vision).

... beeip made a comment on nbme21/block3/q#4 (A clinical trial is conducted to compare the...)
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submitted by beeip(7)

I might be the only person on earth who got this one wrong, but regardless:

"ITT analysis includes every subject who is randomized according to randomized treatment assignment. It ignores noncompliance, protocol deviations, withdrawal, and anything that happens after randomization."[1]

... feronie made a comment on nbme21/block3/q#7 (A 65-year-old man comes to the physician because of...)
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submitted by feronie(1)

Orchiectomy = ↓ testosterone production = ↓ DHT => prostate cells undergo apoptosis. (This mechanism is similar to using 5α-reductase blockers to treat BPH.)

Apoptosis is characterized by DNA fragmentation (pyknosis, karyorrhexis, karyolysis).

... _pusheen_ made a comment on nbme21/block3/q#7 (A 65-year-old man comes to the physician because of...)
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submitted by _pusheen_(0)

Alternatively, all the other options pointed to things that would actually increase testosterone production and its effects; orchiectomy would obviously not do that.

... cytocoins made a comment on nbme21/block3/q#7 (A 65-year-old man comes to the physician because of...)
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submitted by cytocoins(0)

With the drop in testosterone (and therefore DHT), some of the prostate cells will undergo apoptosis. Apoptosis = DNA fragmentation (180 bp segments).

... hayayah made a comment on nbme21/block3/q#8 (A 55-year-old woman is brought to the emergency...)
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submitted by hayayah(54)

Wernicke-Korsakoff syndrome. Don't have to be an alcoholic to get this, just usually is related to alcoholism / thiamine deficiency.

... haliburton made a comment on nbme21/block3/q#10 (A 30-year-old man has had intermittent severe lower...)
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submitted by haliburton(0)

FA 2017: Urinary cyanide-nitroprusside test is diagnostic. not sure how to know that it was a red color, but maybe just the fact that red seemed like a positive test result.

link to more background but not necessarily helpful for this question

... cantaloupe5 made a comment on nbme21/block3/q#11 (A 50-year-old man is found dead in bed at home. His...)
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submitted by cantaloupe5(5)

Histology showed coagulative necrosis (preserved architecture of myocardial fibers) with neutrophil infiltration which hinted that the MI was within 24 hours. Most likely cause of death within first 24 hours of MI is arrhythmia. Myocardial rupture would also be visible on gross appearance of the heart, which they described in the stem.

... frimmy_11 made a comment on nbme21/block3/q#11 (A 50-year-old man is found dead in bed at home. His...)
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submitted by frimmy_11(-2)

Mottling and softening of anterior wall on autopsy suggests it was not older than 24 hrs. Death from fatal arrhythmia like V-fib most commonly occurs within one day of the MI. That said, once scar has formed in myocardial tissue it, too, can cause arrhythmia.

... volcanobuns made a comment on nbme21/block3/q#11 (A 50-year-old man is found dead in bed at home. His...)
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submitted by volcanobuns(0)

MI sudden death -> arrhythmia. The order of commonness is arrhythmia > cardiogenic shock > rupture.

... mcl made a comment on nbme21/block3/q#13 (A 40-year-old woman comes to the physician for an...)
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submitted by mcl(0)

Niacin (vitamin B3) antagonizes VLDL cholesterol secretion

... mcl made a comment on nbme21/block3/q#14 (A 35-year-old man is brought to the emergency...)
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submitted by mcl(0)

Vibrio cholerae is a gram-negative, comma shaped bacteria that can cause watery diarrhea. Cholera toxin functions by activating the Gs proteins --> increasing activity of adenylyl cyclase --> increased cAMP --> increased Na+ and Cl- efflux --> diarrhea.

... haliburton made a comment on nbme21/block3/q#15 (A 47-year-old man has jaundice. Laboratory findings...)
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submitted by haliburton(0)

i think this is because bilirubin is a soluble liver breakdown product of heme, but has not entered the intestine/colon for gut bacteria conversion to stercobilin or urobilin. urobilin in urine is normal.

... lnsetick made a comment on nbme21/block3/q#16 (A 16-year-old boy is brought to the physician...)
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submitted by lnsetick(1)

I just remember Sattar saying MVP tends to be asymptomatic. Also, I think the kid complained specifically of coughing, and that made me really lean away from MVP.

... liltr made a comment on nbme21/block3/q#16 (A 16-year-old boy is brought to the physician...)
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submitted by liltr(0)

I choose MVP too, but this patient’s main symptom is cough only during exercise. This is more indicative of exercised associated asthma. You could see shortness of breath in MVP during exercise, but choosing MVP leaves the cough unaccounted for.

... haliburton made a comment on nbme21/block3/q#18 (An 83-year-old man comes to the physician because of...)
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submitted by haliburton(0)

Bullous pemphigoid antigen must be hemidesmosome. FA: bulla are "bullow" the dermis (subepidermal blister). BP also yield "tense" bulla.

... haliburton made a comment on nbme21/block3/q#19 (A 25-year-old woman develops increasing shortness of...)
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submitted by haliburton(0)

Peri- or postpartum cardiomyopathy (PPCM) is a rare, life-threatening heart disease of unclear origin and is characterized by heart failure of sudden onset between the final weeks of pregnancy and 6 months after delivery. link to pubmed The clinical picture of PPCM corresponds to a dilated cardiomyopathy (DCM) with signs of severe heart failure.

... drdoom made a comment on nbme21/block3/q#21 (A screening program is instituted for detection of...)
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submitted by drdoom(15)

2,500 students ... but you find out during your initial screen that 500 already have the disease. So, strikeout those people. That leaves 2,000 students who don’t have the disease.

Over the course of 1 year, you discover 200 students developed the infection. Thus:

200 new cases / 2,000 people who didn’t have the disease when you started your study = 10 percent

Tricky, tricky NBME ...

... drdoom made a comment on nbme21/block3/q#21 (A screening program is instituted for detection of...)
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submitted by drdoom(15)

Don’t forget that incidence is the number of new cases which emerge in an unaffected population. Incidence is trying to get at the question -> “In a given year, how many new people develop this disease?”

In other words, you cannot count people who already have the disease. You have to exclude those people from your calculation. You want to know, among all the people out there who DO NOT have the disease, how many times this year was someone (newly) diagnosed?

Said differently still, you don’t want to “double-count” people who developed the disease before your study. As an epidemiologist, that would screw up your sense of how infective or transmissible a disease is. You want to know, “from time1 to time2 how many new cases emerged?”

... drdoom made a comment on nbme21/block3/q#21 (A screening program is instituted for detection of...)
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submitted by drdoom(15)

Also consider this great description from the NIH’s MeSH database:

INCIDENCE: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.

https://meshb.nlm.nih.gov/record/ui?ui=D015994

... est88 made a comment on nbme21/block3/q#26 (A 19-year-old woman comes to the office because of a...)
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submitted by est88(4)

Retroperitoneal structures: SAD PUCKER.

Only the descending colon is part of this.

... hayayah made a comment on nbme21/block3/q#27 (A 55-year-old woman with a benign nodule in the left...)
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submitted by hayayah(54)

The thyroid is supplied with arterial blood from the superior thyroid artery, a branch of the external carotid artery, and the inferior thyroid artery, a branch of the thyrocervical trunk.

... porky_pork_chop made a comment on nbme21/block3/q#28 (A 1-year-old girl is admitted to the hospital...)
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submitted by porky_pork_chop(0)

Why would it be a disruption of the secondary structure of collagen molecules? I thought to form the tropocollagen triple helix hydrogen bonds are needed; and FA says failure of formation of the triple helix results in Osteogenesis Imperfecta.

... wasabilateral made a comment on nbme21/block3/q#28 (A 1-year-old girl is admitted to the hospital...)
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submitted by wasabilateral(0)

I think it has something to do with glycine (due to its small size it can fit in many places where other amino acids can not and hence it provides “structural compactness” to the collagen, i.e. put a kink in the alpha helix). If glycine is misplaced by something else, I don’t think pro-collagen can form its correct secondary structure.

jotajota94  True! also, glycine is 1/3 of collagen alfa chains, so it makes sense that substitution with alanine (which is much bigger) would lead to disruption in the alpha helix formation.
jotajota94  True! also, glycine is 1/3 of collagen alfa chains, so it makes sense that substitution with alanine (which is much bigger) would lead to disruption in the alpha helix formation.
... drdoom made a comment on nbme21/block3/q#28 (A 1-year-old girl is admitted to the hospital...)
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submitted by drdoom(15)

Here’s one way to process-of-eliminate “decreased hydrogen-bond formation”: I’m not a big fan of this line of reasoning, but technically alanine as a side group has more hydrogens* for potential hydrogen bonding than glycine:

alanine: —CH3
glycine: —H

So, “technically,” alanine would permit more hydrogen-bond formation, which might allow you to eliminate that choice.

That said, it seems almost impossible to rule out (without very technical knowledge or some provided experimental data) that the slightly larger alanine does not impair hydrogen bonding between collagen molecules via steric (spatial) interference. In simpler terms, since alanine is larger, you would think that it must somehow interfere with the hydrogen-bonding that occurs with the wild-type glycine.

---
*Strictly speaking, it’s not the number of hydrogens but also the strength of the dipole that facilitates hydrogen bonding: a hydrogen bound to a strongly electronegative molecule like fluorine will “appear” more positive and, thus, hydrogen-bond more strongly with a nearby oxygen (compared with a hydrogen connected to carbon, for example).

Further reading:

  1. https://www.chem.purdue.edu/gchelp/liquids/hbond.html
... cellgamesgojan made a comment on nbme21/block3/q#28 (A 1-year-old girl is admitted to the hospital...)
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submitted by cellgamesgojan(3)

I figured, glycine-X-Y is technically considered a “primary amino acid structure of a protein” since the definition of a Primary structure of a protein is “a linear chain of amino acids.” If you mess with the Primary structure, as in the question stem, you cannot form the Secondary structure of the protein, which is determined by the hydrogen-bonding which occurs between the peptide backbone, independent of the R groups. I hope this made sense.

From wikipedia: “Secondary structure is formally defined by the pattern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide backbone.” (emphasis mine)

... mcl made a comment on nbme21/block3/q#30 (A 41-year-old man comes to the physician because of...)
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submitted by mcl(0)

Deltoid is innervated by axillary nerve, which comes from roots C5/C6. Actions of the deltoid include abduction of the upper extremity.

... cantaloupe5 made a comment on nbme21/block3/q#31 (A 28-year-old woman at 18 weeks' gestation has...)
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submitted by cantaloupe5(5)

Hypo/hyperthyroidism is diagnosed with TSH w/ reflex to T4 (this just tells the lab if TSH is normal don’t check T4 but if TSH is abnormal, check T4 too). TSH wasn’t an option so T4 is the best answer.

... assoplasty made a comment on nbme21/block3/q#31 (A 28-year-old woman at 18 weeks' gestation has...)
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submitted by assoplasty(3)

I think the concept they’re testing is the increased TBG levels in pregnancy, and not just hyperthyroidism in general.

When screening for hypo/hyperthyroidism, TSH levels are ALWAYS preferentially checked because they are more sensitive to minute differences in T3/T4. Often times TSH levels can demonstrate a change even when T3/T4 levels are in the subclinical range. The only exception to this would be in pregnancy (and I guess maybe liver failure? I doubt they would ask this though). High estrogen levels prevents the liver from breaking down TBG, leading to increased TBG levels in the serum. This binds to free T4, decreasing the amount of available free T4. As a compensatory mechanism, TSH levels are transiently increased and the RATE of T4 production is increased to replenish baseline free T4 levels. However the TOTAL amount of T4 is increased.

The question is asking how to confirm hyperthyroidism in a pregnant woman --> you need to check FREE T4 levels (because they should be normal due to compensatory response). You cannot check TSH (usually elevated in pregnancy to compensate for increased TBG), and you cannot check total T4 levels (will be increased). You got the answer right either way but I think this is a different reasoning worth considering, because they can ask this concept in other contexts of hyper-estrogenism, and if they listed “TSH” as an answer choice that would be incorrect.

... infundibidum6 made a comment on nbme21/block3/q#32 (A 72-year-old man comes to the physician because of...)
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submitted by infundibidum6(0)

I got it down to bleomycin & chlorambucil and went with chlorambucil (sounded like “bu”sulfan ... lol) because I thought bleomycin was for testicular cancer/Hodgkins lymphoma. I later found out that chlorambucil is actually a preferred treatment for CLL! Is it because chlorambucil causes severe immunosuppression? So you wouldn’t be giving it to a 72 yo man in the first place?

... danger_rave made a comment on nbme21/block3/q#32 (A 72-year-old man comes to the physician because of...)
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submitted by danger_rave(1)

@infundibidum6 So, I got to bleomycin due to SketchyMicro. Bleomycin can cause hyperpigmentation and pulmonary fibrosis, and I didn’t have any connections to chlorambucil. Anthracyclines can be used for all sorts of malignancies (free radicals kill lots of stuff), so the exact indications did less for me to get to the answer than it might have with another category. n=1, but it’s not a magic memorization answer at least.

... hayayah made a comment on nbme21/block3/q#33 (Left radial arterial and venous blood samples are...)
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submitted by hayayah(54)

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.

... mcl made a comment on nbme21/block3/q#34 (A 39-year-old woman with rheumatoid arthritis...)
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submitted by mcl(0)

Membranous glomerulopephritis (aka membranous nephropathy, p 584 FA 2019) may occur secondary to drugs such as penicillamine. Immunofluorescence shows granular deposits due to immune complex deposition. Will also see diffuse capillary and GBM thickening, and SEM will show spike and dome appearance due to subepithelial deposits.

... cellgamesgojan made a comment on nbme21/block3/q#35 (A 63-year-old woman comes to the physician because...)
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submitted by cellgamesgojan(3)

AV Fistulas re-rout blood from the arterial system to the venous system, by-passing the Arterioles = Increase PL ---> INCREASE VR. All in all = Increase CO.

According to UWorld, the arterioles are a major source of resistance ... so bypassing the arterioles results in a decrease in Total Peripheral Resistance ... causing an increase in the rate and volume of blood returning to the heart. I am pretty sure there is more to the physiology behind this, but I hope this explained a little.

big92  "Immediately following creation, arteriovenous fistula (AVF) is associated with an increase in cardiac output (CO), achieved predominantly through a reduction in systemic vascular resistance, increased myocardial contractility, and an increase in stroke volume (SV) and heart rate. Over the following week, circulating blood volume increases in conjunction with increases in atrial and brain natriuretic peptides. These alterations are associated with early increases in left ventricular (LV) filling pressure with the potential for resultant impact on atrial and ventricular chamber dimensions and function." (PMID: 25258554) There's also another study by Epstein from the 1950s looking at the effects of AVF's effect on CO in men (PMID: 13052718). Apparently, the increase in resting CO is a big problem because it can lead to high-output cardiac failure (LVH).
... nuts4med made a comment on nbme21/block3/q#35 (A 63-year-old woman comes to the physician because...)
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submitted by nuts4med(0)

Anyone have an idea why the decreased arterial O2 saturation is incorrect? Assuming she has pulm edema since she has LE edema, wouldn't a lower O2 sat be expected too?

haliburton  I believe there would be no decrease in O2 saturation because oxygenated blood (high pressure) is shunted into deoxygenated circuit. As long as the lungs can keep up, this should increase venous oxygenation on average.
... danger_rave made a comment on nbme21/block3/q#36 (Which of the following best explains why the use of...)
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submitted by danger_rave(1)

Multiple myeloma is an neoplastic proliferation of plasma cells, and since plasma cells don’t have surface Ig bound innately, that was the only “true” option.

... navevan3 made a comment on nbme21/block3/q#37 (A 5-year-old boy who has homocystinuria improves...)
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submitted by navevan3(0)

For this question, I was thinking that they asked you compare to a “normal” person, so the Vmax wouldn’t change since they state that his activity returns to a normal level. Only the x-axis would since it would be at increased concentrations in comparison.

... stapes2big made a comment on nbme21/block3/q#37 (A 5-year-old boy who has homocystinuria improves...)
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submitted by stapes2big(0)

The question is basically setting up a situation similar to that of a competitive inhibitor. They say that higher concentrations of pyridoxal phosphate increases the activity of the enzyme to normal levels. Similarly, when you have a competitive inhibitor and increase the concentration of substrate, the enzyme can achieve the same Vmax as if without the inhibitor.

... haliburton made a comment on nbme21/block3/q#38 (A 28-year-old man develops a temperature of 39.9°C...)
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submitted by haliburton(0)

I chose G-CSF because the granulocytes seemed to me more of a risk than the moderate anemia. Erythropoietin seems like an appropriate choice as well but G-CSF more critical.

... vlodkadrinker made a comment on nbme21/block3/q#39 (A 74-year-old woman with mild dementia is admitted...)
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submitted by vlodkadrinker(1)

I obviously thought that the main thing for capacity is to understand the severity and prognosis of her medical condition BUT I thought this was a trick question because they asked "if the mental examination finding showed..." and the stem failed to mention anything about her orientation to place or time. dumb

drdoom  Stem actually states, “On questioning, the patient does not know the date [time], the name of the hospital [place], or the name of her nurse who had just introduced himself [person].” So, pt *is* actually disoriented to time and place (Choice A). That is definitely concerning -- as would be depressed mood (Choice E) and the other choices -- but “inability to understand severity and prognosis” is **the most concerning** since that is the very definition of capacity. Inability to understand = lack of capacity.
... drdoom made a comment on nbme21/block3/q#39 (A 74-year-old woman with mild dementia is admitted...)
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submitted by drdoom(15)

Stem actually states, “On questioning, the patient does not know the date [time], the name of the hospital [place], or the name of her nurse who had just introduced himself [person].” So, pt is disoriented to time and place (Choice A); that is definitely concerning -- as would be depressed mood (Choice E) and the other choices -- but “inability to understand severity and prognosis” is the most concerning since that is the very definition of capacity. Inability to understand = lack of capacity.

... hayayah made a comment on nbme21/block3/q#40 (A 65-year-old woman undergoes surgical repair of an...)
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submitted by hayayah(54)

Note: The abducens n. is actually the nerve most likely to be damaged by an expanding internal carotid aneurysm in the cavernous sinus but they give you specific CN3 function in this question.

... jotajota94 made a comment on nbme21/block3/q#42 (A 27-year-old primigravid woman at 39 weeks'...)
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submitted by jotajota94(0)

High glucose leads to more insulin production in the fetus (recall that the hormone insulin is anabolic) ---> large fetus (9lb,1oz)---> problems in labor.

... mcl made a comment on nbme21/block3/q#44 (A 23-year-old woman develops persistent sneezing...)
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submitted by mcl(0)

While antihistamines with action at H1 receptors are used for allergies, H2 antihistamines are typically used for ulcers. Therefore the best answer is stabilization of mast cell membranes. These drugs (cromolyn) prevent vesicles of histamine from fusing with the membrane.

... jejunumjedi made a comment on nbme21/block3/q#49 (The gene that codes for a protein normally found in...)
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submitted by jejunumjedi(0)

I think this is describing a signal peptide (hydrophobic at N-terminus). Without signal peptide => can’t be transported into endoplasmic reticulum.

... drdoom made a comment on nbme21/block3/q#49 (The gene that codes for a protein normally found in...)
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submitted by drdoom(15)

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.

... haliburton made a comment on nbme21/block3/q#50 (A 32-year-old woman comes to the emergency...)
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submitted by haliburton(0)

my notes from UWORLD: andes aegypti mosquito = dengue south, southeast asia, pacific islands, carribean, americas HA, retro=orbital pain, joint pain, muscle ache. petechiae, purpura, epistaxis, melena, throbocytopenia leukpoenia, hemoconcentration

... hayayah made a comment on nbme21/block4/q#1 (A 50-year-old woman has azotemia. Renal...)
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submitted by hayayah(54)

Invasive cervical carcinoma is associated with hydronephrosis and renal failure d/t CA spreading through uterine wall and into the bladder.

... liltr made a comment on nbme21/block4/q#2 (A 23-year-old woman comes to the student health...)
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submitted by liltr(0)

It is syphilis. Syphilis is an endarteritis! :)

“The pathologic changes associated with syphilis are characterized by obliterative endarteritis that is found in all stages of the disease.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2811633/

... wasabilateral made a comment on nbme21/block4/q#2 (A 23-year-old woman comes to the student health...)
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submitted by wasabilateral(0)

Syphilis pathogenesis is the inflammation and obliteration of the vasa vasorum (small blood vessels) that feeds bigger blood vessels like aorta, arteries, arterioles. It does not matter what the stage is, T. pallidum infects the vasa vasorum and, in the process, obliterates the nerves and blood vessels. This kills blood supply to those areas = ischemia but no pain (painless chancre). More localized in earlier stages, and in later stage, the spirochetes disseminate, so you have the aorta and spinal cord involvement but same pathogenesis. (Edit: Goljan explained this somewhere.)

... calcium196 made a comment on nbme21/block4/q#4 (The FOXO transcription factor responds to insulin...)
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submitted by calcium196(2)

Ubiquitin-mediated proteolysis is not reversibly affected by insulin. The question asks for reversible ways that insulin affects it, and ubiquitination would lead to degradation via proteases, which is not reversible. Nuclear/cytoplasmic shunting makes sense because FOXO is a transcription factor, so it can’t do its job if it is in the cytoplasm!

... jambo2222 made a comment on nbme21/block4/q#5 (An 11-year-old boy has had persistent pain in his...)
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submitted by jambo2222(1)

It’s an osteosarcoma. Sarcoma = hematogenous mets. It’s in the legs so think how a DVT goes to lung. Same idea.

... cellgamesgojan made a comment on nbme21/block4/q#5 (An 11-year-old boy has had persistent pain in his...)
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submitted by cellgamesgojan(3)

Jambo is right. I was reading through Goljan Rapid Review and he states that the lungs are the most common site of metastasis for osteosarcoma.

... beeip made a comment on nbme21/block4/q#6 (A 55-year-old man comes to the physician because of...)
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submitted by beeip(7)

This has been a tough concept for me to get, but I think I'm finally there:

The stem is describing primary adrenal insufficiency, or Addison's.

  • ACTH is being over-produced to stimulate the adrenals to produce cortisol, but they can't respond, either due to atrophy or destruction (TB, autoimmune: DR4, etc.)
  • The first 13 amino acids of ACTH can be cleaved to form α-MSH, which stimulates melanocytes, causing hyperpigmentation
jotajota94  Good job! Also, cortisol is involved in maintaining blood pressure. which was decreased in the patient.
... mcl made a comment on nbme21/block4/q#7 (A 14-year-old boy is brought to the physician by his...)
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submitted by mcl(0)

Gait problems raises suspicion for alcohol abuse or inhaled glue. However, onset of gait problems is relatively rapid (couple of months) and gait disturbance with regards to alcohol is either due to intoxication or chronic abuse. Alternative explanation available on SDN. Also see toluene toxicity on medscape.

... haliburton made a comment on nbme21/block4/q#10 (A 64-year-old man is evaluated for cough, dyspnea,...)
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submitted by haliburton(0)

Small cell lung cancer causes SIADH. Location + exclusionary clues.

mcl  To expand, SIADH may also result in euvolemic hyponatremia. This is because, as we know, ADH increases absorption of water and therefore initially results in an increased circulating volume. However, this results in increased stretch of the atria and subsequent secretion of ANP. ANP (atrial natriuretic peptide) then results in loss of sodium and water.
... sklawpirt made a comment on nbme21/block4/q#13 (A 4-month-old boy is diagnosed with a rare autosomal...)
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submitted by sklawpirt(0)

I think the idea here is simply that one should think about where vesicles are coming from on their way to the golgi complex.

"Two steps forward and one step back." Specfically the question may be referring to a rare craniofacial disorder. an awarenesss of that disease is not necessary. What is necessary is understanding the origin from where vesicles are traficked to the Golgi apparatus.

COPI protein is needed to coat vescles from the RER to send to golgi. Thus, with a mutation in that protein, the packaged proteins that should bleb off and be sent to the golgi, instead accumulate in the RER and dilate it. Thus the answer.

https://www.cell.com/ajhg/pdf/S0002-9297(16)30214-2.pdf

hayayah  pg. 47 on FA got the good visuals!
... cellgamesgojan made a comment on nbme21/block4/q#14 (A 25-year-old woman has a 3-week history of bleeding...)
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submitted by cellgamesgojan(3)

The patient suffered from Immune Thrombocytopenia. autoantibodies against the glycoproteins GP2B/3A.

On labs, you’ll see: increase in megakaryocytes; on the question stem they’re described as “rare but large.” Megakaryocytes are not suppressed.

... krazyglue5 made a comment on nbme21/block4/q#14 (A 25-year-old woman has a 3-week history of bleeding...)
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submitted by krazyglue5(1)

She has ITP/immune thrombocytopenia, so she has autoantibodies against her platelets, specifically GPIIb/IIIa. She has the large megakaryocytes because her bone marrow is trying to churn out platelets. She’s a woman of child-bearing age with increased bleeding time but no other neurologic abnormalities/renal issues/fever, so think ITP.

... cantaloupe5 made a comment on nbme21/block4/q#15 (A 5-year-old boy is brought to the physician for a...)
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submitted by cantaloupe5(5)

Proccess of elimination for this one. Two you can eliminate immediately just from looking at the biochemical pathway chart. The other two required knowledge that eumelanin is more protective than pheomelanin (this is why redheads burn more easily). Because pheomelanin is less protective, there would be more not less ROS from sunlight.

... haliburton made a comment on nbme21/block4/q#16 (A 40-year-old woman who had pneumonia due to...)
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submitted by haliburton(0)

FA 2017: Secrete surfactant from lamellar bodies. Also serve as precursors to type I cells and other type II cells. Proliferate during lung damage.

... assoplasty made a comment on nbme21/block4/q#23 (An investigator is studying the regulation of...)
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submitted by assoplasty(3)

Vasoconstriction decreases blood flow and thus decreases hydrostatic pressure. Seems counter intuitive but I had to look this up after I got it wrong, too.

... drdoom made a comment on nbme21/block4/q#23 (An investigator is studying the regulation of...)
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submitted by drdoom(15)

Vasoconstriction (narrowing of a tube) will cause the flow rate to increase through that tube, which decreases radial/outward pressure. The faster a fluid moves through a tube, the less “outward” force it exerts. (This is known as the Venturi effect.)

... hayayah made a comment on nbme21/block4/q#23 (An investigator is studying the regulation of...)
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submitted by hayayah(54)

Lymph flow rate is usually low. It is influenced primarily by the rate of lymph formation. For example, if blood capillary pressure is increased by arterial vasodilation or venous constriction, the flow rate of lymph increases. Also, the flow rate is affected by compression of lymphatics by contraction of neighboring musculature and by negative intrathoracic pressure (breathing).

Interstitial pressure (so pressure in the ECF, which would increase if given IV saline) and lymph flow are positively related. A small increase in interstitial volume greatly increases its pressure, promoting lymph flow that acts to restore the interstitial volume to normal.

more on this topic: https://www.ncbi.nlm.nih.gov/books/NBK53448/

... hayayah made a comment on nbme21/block4/q#24 (A 56-year-old man undergoes a renal transplant. Five...)
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submitted by hayayah(54)

Hyperacute transplant rejection occurs within minutes d/t pre-existing recipient antibodies that react to donor antigen (type II hypersensitivity reaction), activate complement.

mcl  [Useful figures illustrating transplant rejection](https://www.stomponstep1.com/transplant-rejection-hyperacute-acute-chronic-graft-versus-host/)
... madeforupvoting2 made a comment on nbme21/block4/q#25 (An 80-year-old woman cannot concentrate her urine...)
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submitted by madeforupvoting2(0)

To maintain plasma osmolality -> Need to exactly replace all the fluids lost in the day

She cannot concentrate urine above 450 mOsm/kg , so the minimum amount of water required to be excreted by kidneys is 1 (to excrete the 450 mOsm she accumulates per day). The minimum excretion water required is necessarily at max concentration; if you were to say produce diluter urine, say 225mOsm/kg, this would require 2 L of water. The question wants the minimum possible water volume, so we assume she’s concentrating to the max.

1 L losses from kidney + 900 mL insensible + 100 mL in sweat and feces = 2L losses -> need to ingest 2 L of water to replace.

... cantaloupe5 made a comment on nbme21/block4/q#25 (An 80-year-old woman cannot concentrate her urine...)
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submitted by cantaloupe5(5)

She’s intaking 450 mOsm per day so she needs to excrete 450 mOsm per day to maintain equilibrium. You can’t just excrete mOsm’s by themselves -- they have to be dissolved in some amount of water.

Let’s say you excrete 450 mOsm with 500 mL of water -- that means your kidneys are concentrating urine to:

450 mOsm ÷ 500 mL = 900 mOsm/L

But the maximum this lady’s kidneys can concentrate urine to is 450 mOsm/L, so she has to excrete more water to get it that dilute. That amount of water is 1 L, because 450 mOsm/1 L = 450 mOsm/L.

Now there’s nothing stopping her from excreting the 450 mOsms in an even more dilute urine -- for example if she drank an extra L of water one day, the kidneys could get rid of that extra L with the same amount of 450 mOsm by diluting the urine to 450 mOsm ÷ 2 L = 225 mOsm/L. But the question asks for the minimum amount of water -- which is 1 L by the kidneys (+ 1 L from the other stuff for a total of 2 L).

... flashvoyger made a comment on nbme21/block4/q#25 (An 80-year-old woman cannot concentrate her urine...)
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submitted by flashvoyger(3)

The question is asking you how much water must the woman take in to maintain the same osmolality. This woman takes in 450 mOsm of solute per day. This is a unit of measurement -- think of it like grams.

For her to keep the same osmolality she must excrete 450 mOsm per day. The only way for her to excrete the solute is via the kidneys. The only way for her kidneys to excrete 450 mOsm is if they excrete 1 liter of water also. This is the max concentration that her kidneys can produce. (Her kidneys are not “powerful enough” to make her urine any more concentrated than that.)

This woman is also losing another liter of water to feces, sweating and respiration. This is the “insensible water loss”. That means if she losing 1 liter of water to sweat, respiration and feces per day plus 1 liter of water to urine (because she needs to dissolve her solute in something!), for her blood to stay the same osmolality, she must replace the water she lost thus must, at minimum, drink 2 liters of water per day.

... hayayah made a comment on nbme21/block4/q#28 (A 56-year-old man undergoes surgical resection of...)
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submitted by hayayah(54)

Although half these hormones can actually also be secreted from the duodenum, the duodenum is associated the most with CCK release.

... vlodkadrinker made a comment on nbme21/block4/q#29 (A 22-year-old man comes to the physician because of...)
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submitted by vlodkadrinker(1)

tinidazole preferred due to single dose

... mcl made a comment on nbme21/block4/q#33 (A female newborn delivered at 26 weeks' gestation is...)
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submitted by mcl(0)

"chronic high oxygen saturations can adversely affect lung and eye outcomes of preterm infants." link

... beeip made a comment on nbme21/block4/q#34 (A healthy 8-year-old boy is brought to the physician...)
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submitted by beeip(7)

"Excitatory amino acids" refers to glutamate, while "Biogenic" apparently refers to tyrosine, the precursor AA to dopamine and norepi.

... beeip made a comment on nbme21/block4/q#36 (A 45-year-old man comes to the physician because of...)
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submitted by beeip(7)

This review suggests that enchondroma and chondrosarcoma are unable to be differentiated on histology alone. According to Orthobullets:

"unlike enchondroma, most chondrosarcomas have non-mechanical pain (rest pain and nocturnal pain)"

Guess this diagnosis is made on history.

... mcl made a comment on nbme21/block4/q#44 (A 28-year-old woman with chronic renal failure...)
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submitted by mcl(0)

Furosemide and other loop diuretics are indicated for use in volume overload secondary to renal failure. Recall loop diuretics inhibit the Na+/K+/Cl- pump at the thick ascending loop of Henle, which messes with the hypertonicity of the medulla and therefore prevents urine from being concentrated. This results in increased fluid loss to urine, and is helpful in treating symptoms of edema.

... cantaloupe5 made a comment on nbme21/block4/q#45 (During an experiment, an investigator observes that...)
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submitted by cantaloupe5(5)

This one was tricky but I think you could’ve done this one without knowledge of NMDA receptors. Stem told you that glutamate activates both non-NMDA and NMDA receptors but it activated only non-NMDA receptors in the early phase. That means NMDA receptors activate after non-NMDA receptors. That means something was delaying NMDA receptor activating and the only answer that made sense as the Mg inhibiting NMDA at resting potential. Once the cell is depolarized by non-NMDA receptors, NMDA receptors can be activated.

... vlodkadrinker made a comment on nbme21/block4/q#45 (During an experiment, an investigator observes that...)
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submitted by vlodkadrinker(1)

don't forget about the Mg block! . . . . . .

... hayayah made a comment on nbme21/block4/q#46 (A 14-year-old girl is brought to the physician for a...)
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submitted by hayayah(54)

Most human cancers are d/t a loss of function of TP53 gene.

... mcl made a comment on nbme21/block4/q#46 (A 14-year-old girl is brought to the physician for a...)
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submitted by mcl(0)

Other way to get this question is by eliminating other options -- this figure is useful in listing some mutations and associated cancers.