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NBME 19 Answers

Block 1/Question#1
53 yo woman w/GERD. Diet change, stress reduction do not ...
Omeprazole

Block 1/Question#4
66 yo man, 2 months of not being able to maintain an ...
Libido: decreased; Noctural erections: normal

Block 1/Question#7
48 yo woman, 2 weeks of fever and stool with mucus; recent ...
Entamoeba histolytica

Block 1/Question#13
What mechanism of action do tumor-suppressor genes have that ...
Inhibition of cell-cycle regulation

Block 1/Question#16
60 yo man, 2 week history of flank pain and blood in urine. ...
Metastatic renal cell carcinoma

Block 1/Question#17
29 yo man with untreated HIV infection; what explains ...
CD8+ T lymphocyte–mediated killing

Block 1/Question#24
62 yo woman with sudden weakness of left leg; infarct in ...
Right anterior cerebral artery

Block 1/Question#26
Niemann-Pick disease is characterized by which of the following?
Decreased lysosomal hydrolase activity

Block 1/Question#28
13 yo girl with mother for routine visit; physician wants to ...
Ask mother to leave the room before asking the patient any questions.

Block 1/Question#31
32 yo man given primaquine for malaria prophylaxis; develops ...
Enzyme deficiency in the erythrocytes

Block 1/Question#34
12 yo girl unable to walk for 5 days but is unconcerned about ...
Conversion disorder

Block 1/Question#35
5 yo boy, R eye pain for 1 week; retinal exam shows a mass. ...
Retinal cells

Block 1/Question#36
36 yo woman presents to ED after believing she suffered a ...
Panic disorder

Block 1/Question#42
What advantage does randomized controlled study have over ...
Better control for confounding variables

Block 1/Question#44
Three tests are developed to identify rotavirus in children ...
Test 3 followed by test 1 if test 3 is positive

Block 1/Question#48
62 yo man, right-handed, suffers decreased speech fluency ...
Area labeled by letter 'A'

Block 2/Question#5
38 yo woman, 6 months depressed mood, joint pain, weakness, memory problems + erythema migrans
Lyme disease

Block 2/Question#6
24 yo man, generalized tonic-clonic seizure; somnolent, hyponatremia; drinks 6 liters of water in 24 hours but says he's not thirsty
Psychogenic polydipsia

Block 2/Question#8
Retinoic acid receptors and HOX gene products bind specific DNA sequences; what is the function of these molecules?
Transcription factors

Block 2/Question#9
Lab findings expected after administration of insulin and saline
Potassium decreased; Bicarbonate increased; BUN decreased; Arterial pH increased; blood CO2 increased

Block 2/Question#13
25 yo man, exercise test. Most likely physiologic changes
Arteriolar diameter increased; Tissue adenosine concentration increased; Vascular conductance increased

Block 2/Question#16
40 yo woman, chorionic villus sampling
Confined placental mosaicism

Block 2/Question#17
Scurvy symptoms associated with decreased activity of which enzyme?
Prolyl hydroxylase

Block 2/Question#23
10 yo girl, slightly painful 2 mm subcutaneous nodule on chin
Granuloma

Block 2/Question#25
48 yo woman, 3 months fatigue; X-rays reveal generalized osteopenia
Paracrine stimulation of osteoclasts by osteoblasts

Block 2/Question#27
Case-control study; 95 percent confidence interval was [reported range]. Most appropriate interpretation?
The likelihood is 95% that the true value for the odds ratio is between [the reported range]

Block 2/Question#34
Mechanism by which action potentials permit currents to flow deep within skeletal muscle fibers
Transmission along T tubules

Block 2/Question#36
75 yo man with dementia; no advanced directives
Encourage the family to come to a consensus based on their perception of the patient's wishes

Block 2/Question#37
2 day old newborn with jaundice
Conjugation of bilirubin to glucuronic acid

Block 2/Question#43
45 yo woman undergoing vinblastine chemotherapy
Decreased number of neutrophils

Block 2/Question#45
Pathway of the transepithelial transport of water
Pathway denoted by letter 'C'

Block 2/Question#46
Decreased pulmonary artery pressure facilitated by increase in the intracellular concentration of which molecule?
cGMP

Block 3/Question#5
30 yo woman, 1 week of visual difficulty
Right optic nerve

Block 3/Question#9
Cells most responsible for graft rejection?
T lymphocytes

Block 3/Question#12
23 yo woman engages in 30 minutes of strenuous exercise
Increased, as a result of distention and recruitment of microvessels

Block 3/Question#16
13 yo girl grows over the summer; what accounts for increased intestinal absorption of calcium?
Hormones derived from 7-dehydrocholesterol

Block 3/Question#17
45 yo patient, chronic alcohol dependence, foul-smelling brownish sputum
Chest radiograph labeled 'D'

Block 3/Question#19
30 yo man and 24 yo woman; best estimate that child will have oculocutaneous albinism?
1 in 600

Block 3/Question#22
Blood gas values: arterial O2 pressure: 96 mm Hg; Arterial O2 content: 12.0 vol%
Anemia

Block 3/Question#27
74 yo man; continuous systolic-diastolic bruit over R posterior flank
Renal artery stenosis

Block 3/Question#28
40 yo man, 1 month increasing malaise, nausea, abdominal pain; CD8+ T lymphocytes resulting in liver injury
Hepatocytes

Block 3/Question#29
15 yo girl receives bone marrow transplant; karyotype reveals 46,XY
Nonautologous donor

Block 3/Question#33
19 yo man stabbed in abdomen; has been incarcerated for armed robbery
Antisocial personality disorder

Block 3/Question#34
52 yo man, 4 hours of severe headache, anxiety, sweating, palpitations; what happens after injection with propranolol?
Increased total peripheral resistance and decreased cardiac output

Block 3/Question#39
45 yo man, lost outdoors in the Rocky Mountains for 10 days
Kidney

Block 3/Question#40
25 yo woman requests prenatal diagnosis at 12 weeks gestation
Chorionic villi sampling

Block 3/Question#41
41 yo woman, 34 weeks gestation; amniocentesis shows lecithin-to-sphingomyelin ratio of 1.5:1
Decreased functional residual capacity

Block 3/Question#42
Study conducted to determine effects of drug X on respiratory function
Tubocurarine

Block 3/Question#46
52 yo man, sudden onset of substernal chest pain
Histamine

Block 3/Question#49
Schematic representation of eukaryotic translation
Binding of aminoacyl-tRNA to the A site

Block 3/Question#50
39 yo man, 6 months of headache, muscle aches, fatigue; distal motor weakness of extremities
Basophilic stippling

Block 4/Question#13
26 yo woman after jejunoileal bypass for morbid obesity; most likely deficiency?
Vitamin A

Block 4/Question#14
11 yo boy, right mid-thigh pain for 2 weeks; femur X-ray reveals single osteolytic lesion in mid-diaphysis
Ewing sarcoma

Block 4/Question#15
60 yo woman, 1 year of episodic involuntary rhythmic jerking of R leg and foot; brain MRI reveals 2 cm round enhancing lesion within interhemispheric fissure
Meningioma

Block 4/Question#17
60 yo man, 20-year history of hypertension; shortness of breath and fatigue for 3 months
Cardiac output: decreased; CVP: increased

Block 4/Question#23
30 yo woman with Marfan syndrome, sudden onset of tearing chest pain
Cardiac index: 2.0;
Right atrial pressure: 18;
Pulmonary capillary wedge pressure: 18;
Pulmonary diastolic arterial pressure: 20;
Systemic vascular resistance: 2,000


Block 4/Question#26
54 yo man, routine exam; given an angiotensin converting enzyme (ACE) inhibitor
Area labeled by letter 'F' (efferent arteriole)

Block 4/Question#27
52 yo woman prescribed cisplatin for non-small cell carcinoma of the lung
Odansetron

Block 4/Question#33
Oral fluid therapy for diarrhea caused by Vibrio cholerae
Membrane transport mechanism denoted by letter 'C' (Sodium-Glucose cotransporter)

Block 4/Question#46
24 yo woman; renal oxygen consumption found to be 20 mL per minute; which process consumes the most oxygen?
Tubular reabsorption

Block 4/Question#49
30 yo woman with high-grade intraepithelial lesion
Superficial to the basement membrane

Block 0/Question#0
A 27-year-old woman has an episode of pneumococcal pneumonia ...
Direct antiglobulin (Coombs) test

Block 0/Question#0
During an experiment, an isolated skeletal muscle is placed ...
pH

Recent comments ...

... ajguard26 made a comment on nbme19/block1/q#1 (53 yo woman with GERD.)
 +2  upvote downvote
submitted by ajguard26(8)

So although Misoprostol DOES increase mucus production and is gastro-protective (and in FA does state that it decreases acid production), thereby decreasing symptoms and aiding in healing, omeprazole is the "more correct" choice. This is because omeprazole is a proton-pump inhibitor, which will act directly on the proton pumps of the stomach and decrease the offending agent more than the misoprostol will. Therefore, it is the first line drug for GERD.

... drdoom made a comment on nbme19/block1/q#4 (66 yo man, 2 months no erection)
 +13  upvote downvote
submitted by drdoom(74)

Inability to maintain an erection = erectile dysfunction. So now the question is "Why?"

Fatigue, difficulty sleeping, difficulty concentrating is starting to sound like depression. "Difficulty concentrating" might be interpreted as impaired executive function or the beginnings of vascular-related dementia (dementia related to small but numerous cerebral infarcts), but on Step 1 dementia will be blatant (i.e., "lost his way home," "wandering," etc.).

Depression is actually common after a debilitating event like stroke, as you might expect. With depression comes a loss of sexual interest and desire—that is decreased libido.

One can make the argument that a "vascular patient" might have some issues with his "pipes" (arteriosclerosis, parasympathetic/sympathetic dysfunction) and, for this reason, nocturnal erection should be decreased; but note that nothing is mentioned about long-standing vascular disease (no hx of hypertension).

As a result, the best answer choice here is C. (Libido decreased but nocturnal erections normal.) The big question I have is, how the heck does this guy know he's hard when he's asleep!!? :p

... shadowbox made a comment on nbme19/block1/q#4 (66 yo man, 2 months no erection)
 +0  upvote downvote
submitted by shadowbox(0)

The amount of nocturnal erections is decreased, I think (atherosclerotic problem); but I thought that it was a typical case of a patient suffering from depression after a serious illness, therefore => decreased libido.

... quackster made a comment on nbme19/block1/q#4 (66 yo man, 2 months no erection)
 +0  upvote downvote
submitted by quackster(0)

This is a controversial one, but it seems the consensus is that pt had sxs of major depression, and thus his libido was most likely down. But structurally/blood flow–wise, he was fine, so nocturnal erections were normal. So, concept NBME wants us to realize is that we should screen for depression in pts who complain of sexual dysfunction? Or ask about sex in pts who display sxs of depression, like that patient had in the stem of the Q.

... picodemolar made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
 +0  upvote downvote
submitted by picodemolar(0)

Oncogenes with gain of function mutation lead to increased transcription, etc., whereas tumor suppressor genes block G1-->S phase. NF1 gene product has RAS GTPase activity which works by phosphorylating and activating protein (neurofibromin). So there is at least 1 tumor suppressor gene that works through phosphorylation.

... drdoom made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
 +0  upvote downvote
submitted by drdoom(74)

This is essentially a formal logic question. Logically speaking, the question asks us to identify a mechanism that tumor suppressors have which proto-oncogenes do not. In other words, what is a mechanism shared by all known tumor suppressors but not shared by any known proto-oncogenes? For that reason, it can’t be phosphorylation; sure, phosphorylation is a mechanism of tumor suppressors but it’s also a mechanism of many known proto-oncogenes.

... aliyah made a comment on nbme19/block1/q#17 (29 yo man untreated HIV)
 +0  upvote downvote
submitted by aliyah(4)

After the CD4+ cells become infected, the CD8+ cells kill them.

... ajguard26 made a comment on nbme19/block1/q#24 (62 yo woman sudden weakness of left leg)
 +2  upvote downvote
submitted by ajguard26(8)

This patient presents with classic upper motor neuron lesion symptoms: weakness, hyperreflexia, and decreased sensation. However, the question states she "cannot tell whether her left great toe is raised or depressed" when her eyes are closed, which may make you reconsider and think there may be some proprioceptive issues they are trying to hint at. This is not the case. Especially once they mention there are no other abnormalities (i.e., no upper limb abnormalities or right sided abnormalities). If this is the case, there is no damage to the tracts at all (which are still considered UMN).

Therefore, the damage is purely motor and sensory in the left leg, which is on the medial aspect of the frontal and parietal lobes respectively. This area is supplied by the anterior cerebral artery.

... doofusmd made a comment on nbme19/block1/q#35 (5 yo boy, right eye pain 1 week)
 +5  upvote downvote
submitted by doofusmd(6)

This is what is known as a somatic mutation: a mutation that occurs in non-germline cells and, therefore, only effects daughter cells derived from the parent cell with the mutation. So, a mutation occurred in a differentiated parent cell that gave rise to a set of daughter cells (which, in this case, were destined to become retinal tissue).

... aliyah made a comment on nbme19/block1/q#35 (5 yo boy, right eye pain 1 week)
 +2  upvote downvote
submitted by aliyah(4)

If a germ cell or somatic cell had the original mutation, then there's an increased risk for cancer in other parts of the body too. If only retinal cells in one eye is mutated, only that one eye is at risk for cancer.

... ajguard26 made a comment on nbme19/block1/q#42 (Advantage of randomized controlled studies)
 +1  upvote downvote
submitted by ajguard26(8)

"Confounding variables" here means "confounding bias," essentially. And this is true because a prospective cohort looks at a specific exposure to a substance (environmental toxin, drug, etc.), and asks "Who will develop this disease if exposed?" PCS's look attempt to find a relative risk associated with an exposure. They do not take into account the affects other exposures. This is your confounding bias. FA gives the example of confounding bias as "Pulmonary disease is more common in workers in a coal mine; however, miners are more likely to smoke," and since smoking can also lead to pulmonary disease, you can't really say whether the smoking (first or second hand) or the coal dust causes the problem. A clinical trial, on the other hand, contains a test group and a control group, so variables such as the confounding variable mentioned above are limited.

... ajguard26 made a comment on nbme19/block1/q#48 (62 yo man, decreased speech fluency after cerebral infarct)
 +1  upvote downvote
submitted by ajguard26(8)

Obviously no picture here, but "A" in the picture represents Broca's area, which would cause the expressive aphasia this patient is experiencing.

However, the question also states the patient has weakness of the lower two-thirds of his face. This may cause you to think there is maybe a lesion in the pre-central motor area (thinking humonculus), but realize that the motor area travels all the way down to the bottom of the frontal lobe, RIGHT BEHIND THE BROCA'S AREA. In fact, Broca's area encompasses that part of the humonculus. And since the upper part of the face is controlled by the upper part of the facial motor cortex, and the lower part is controlled by the lower part of the facial motor cortex, you can have paralysis of the lower part of the face and have expressive aphasia if the lesion is in that specific area (does not need to be a lower motor lesion to spare the upper face/forehead).

... ajguard26 made a comment on nbme19/block2/q#13 (25 yo man, exercise test. Most likely physiologic changes)
 +1  upvote downvote
submitted by ajguard26(8)

As the muscle works and breaks down ATP, adenosine is produced, leading to an increase in the tissues. This increased adenosine causes vasodilation, which in turn increases vascular conductance (the flow of a volume of blood through the vasculature).

Although you may think muscle contraction may lead to a decrease in flow through the vessel(s) by squeezing down on them, this mechanism is overcome by the increased cardiac output from the heart.

... ajguard26 made a comment on nbme19/block2/q#16 (40 yo woman, chorionic villus sampling)
 +1  upvote downvote
submitted by ajguard26(8)

Chorionic villi sampling is the taking of genetic material within in the chorionic villi of the placenta. Chorionic sampling is done when a patient is at high risk for chromosomal abnormalities (previous pos. tests, 35yo or older, family hx.) during the 10-13 weeks of pregnancy.

Confined placental mosaicism results when the C.V.S. testing comes back back showing a trisomy, but all subsequent testing (and the fetus itself) have normal chromosomal counts. This may be due to either a trophoblastic mutation, or by "trisomic rescue," in which trisomic cells that were supposed to be in the fetus are confined to the placenta to prevent an abnormal fetus.

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