NBME 26 Flashcards
To assess ulnar nerve function, what action would be most indicative?
Abduction of the index, middle, ring, and small finger
An 18-month-old child with HIV is exposed to a child who has an erythematous, maculopapular rash. Three weeks later, the child develops giant cell pneumonia with no rash. What is the causative organism?
Measles
__________ and _________ activate the two primary cells responsible for granuloma formation in TB?
IL-12 & INF-y
IL-12 is an inflammatory cytokine secreted by macrophages that are infected w/TB, an intracellular pathogen. IL-12 acts on both natural killer cells (NK cells) and cytotoxic T lymphocytes, causing them to release interferon-gamma, which has several roles including the promotion of Th1 T-cell differentiation, the augmentation of antigen
presentation by macrophages, & the differentiation of macrophages into multinucleated giant cells.
Collectively, this activating pathway of IL-12 and interferon-gamma allow for granuloma formation, a histologic hallmark of infection w/TB, isolating the invasive pathogen.
Contrary to other diseases that result in granuloma formation, MTB infection often results in caseating (necrotic) granulomas.
PKU can result from a homozygous point mutation (GT->AT) in intron 12 causing the skipping of exon 12. Why does this occur?
RNA splice error
To differentiate ascites caused by constrictive pericarditis vs cirrhosis, what physical finding could confirm the former?
Increased JVP
Which mechanism of the cell cycle best explains increased potential for growth and resistance to chemotherapy in late stage colon carcinoma?
Genomic instability during S, G2, and M phases
After mannitol administration, how will serum osmolality and ADH levels change?
Both increase
In patients with glucagonoma, what process is most likely occurring in the liver?
Partial oxidation of fatty acids
Glucagon ENHANCES ketogenesis
Point mutations in HIV in the long terminal repeat region would result in decreased viral replication due to a defect in what process?
Integration of the provirus into the host cell genome
The most common cause of anemia in CLL (smudge cells) patients is what?
Autoimmune hemolysis
In a GI imaging study, the feathery appearance of some portions of the bowel as compared to others is due to what characteristic?
Greater mucosal surface area
What is the function of LFA in neutrophils?
Adhesion to endothelium
In a healthy person, what substance has the greatest fraction excreted in urine?
Urea
PGE2 administration to smooth muscle cells results in decreased tension (relaxation) due to what intracellular effect?
Increased cAMP
Histone acetyltransferase catalyzes acetylation of lysine residues in amino-terminal tails of histones which has what effect on histones/DNA?
Decreases affinity of histones to DNA
In premature infants, lungs have increased what?
Elastic recoil due to deficient surfactant
Surfactant is critical for reducing alveolar surface tension & collapsing pressure; without it, alveolar collapse results in (3)
- impaired gas exchange
- decreased lung compliance
- increased lung elastic recoil
A fast-acting anesthetic would have what characteristic?
Low blood solubility
What is the difference between simple partial & simple complex seizures?
Complex have altered consciousness, partial has retained awareness and patients may even speak
Prior to ovulation, oocytes are arrested in what stage of cell division? How about after ovulation?
Prophase of meiosis I; metaphase of meiosis II
What organism causes tinea versicolor?
Malassezia furfur
A patient presenting with shortness of breath, hypokinesis of the posterior left ventricular with increasing activity levels whose father died at 52 from MI likely has what cause of SOB?
Stenosis of the right coronary artery
A mutation in the gene encoding for what predisposes patients to malignant hyperthermia?
Ryanodine receptor
Malignant hyperthermia—rare, life-threatening condition in which inhaled anesthetics or succinylcholine induce severe muscle contractions & hyperthermia.
AD Inheritance with variable penetrance.
Mutations in ryanodine receptor (RYR1) cause ↑ Ca2+ release from sarcoplasmic reticulum.
Treatment: dantrolene (a ryanodine receptor antagonist).
What are characteristic signs/symptoms of Measles?
prodromal fever (low grade fever)
cough
coryza
conjunctivitis
Koplik spots (white spots on buccal mucosa/mouth)
erythematous, maculopapular rash that starts at the head/neck & spreads to the trunk
Rash does NOT include the palms & soles
Pneumonia (immunocompromised pts)
After a cerebral infarction (6months later in Q), neurons undergo liquefactive necrosis & are replaced by a glial scar consisting of proliferated _________
Astrocytes (Glial Cells)
In peripheral tissues, fibroblasts migrate to the area of injury to participate in tissue repair.
However, in the CNS, repair is instead performed by astrocytes that migrate to the area of necrosis within 2 wks of injury to begin forming a glial scar.
Premature closure of which suture results in narrow, elongated cranium?
which suture results in short, broad flattened cranium?
increased AP dimension: sagittal suture
short broad (arrests the AP dimension): coronal
_________ addition to PRP (platelet-rich plasma) will result in rapid and irreversible aggregation
ADP (adenosine diphosphate) & Thromboxane A2
- critical in normal hemostasis
Acts via the receptors P2Y1 and P2Y2 on the surface of platelets. Binding to these receptors results in G-protein coupled receptor signaling, with concurrent alteration of platelet shape and activation of GPllb/IIIa via the PI3K signaling pathway, which results in rapid platelet aggregation
What are main distinguishing factors between RA and OA?
❥ Osteoarthritis→ DIP, PIP, spine & the large weight-bearing joints of the lower extremities (knees, hips). Morning stiffness < 30min. Hard, bony enlargement of joints. OA worsens through the day
❥Rheumatoid arthritis→ Morning stiffness that lasts hrs & pt has systemic sxs like fever, wt loss, ANEMIA! Worse in morning, improves w/activity.
-metacarpophalangeal, PIP, & other joints, but DIP joint involvement is less common.
-involved joints in RA have active synovitis, w/warmth & soft/spongy swelling.
-“synovial hyperplasia”
-Rheumatoid factor (an IgM against the Fc region of IgG); anti-cyclic citrullinated peptide (CCP); anti-CCP is more specific than rheumatoid factor
12M + lethargy, hip pain, fever (103) has been hospitalized several other times bc of PNA. Neonatal period normal. CBC counts wnl, HIV negative. Blood cultures grow Staph aureus. Serum electrophoresis is likely to show which?
D: deficiency in immunoglobulins
first peak = albumin
alpha = alpha 1 antitrypsin, thyroid-binding globulin, transcortin
beta: transferrin and B-lipoproteins, complement
y: immunoglobulins
A: narrow monoclonal spike in the gamma region
- multiple myeloma
- Waldenstrom macroglobulinemia
- monoclonal gammopathy of undetermined significance
- amyloidosis
B: blurring of the beta-2 and gamma regions (beta/gamma fusion)
- increased CRP or increased IgA
(severe respiratory infections, RA, cirrhosis)
C: large but wide gamma region consistent with hypergammaglobulinemia
- nonspecific hypergammaglobulinemia (chronic liver dz, CT dz, inflammatory conditions)
E: normal
Which of the following labeled depolarizations is associated with the smallest stroke volume?
B
Stroke volume is the difference between the ventricular end-diastolic volume and the end-systolic volume. premature ventricular contraction (PVC) shorten diastolic filling times leading to lower diastolic volumes with a consequent reduction in stroke volume during ventricular
systole.
Pt w/hx of rheumatic valvular disease + EKG shows MI + systolic murmur on exam + Pressure tracings from the aorta, LV & LA shown. Whats the dx & what could cause this?
Dx is Mitral Regurgitation
Rupture of the chordae tendineae & papillary muscle is a potential complication of myocardial infarction & results in acute mitral regurgitation.
On a pressure-time graph, this manifests as an increased left atrial pressure during ventricular systole from regurgitant blood.
When you hear mitral obstruction you should be thinking Mitral ______
Mitral Stenosis
Mitral Stenosis results in an abnormally increased LA pressure due to the impaired flow of blood from the LA into the LV. Additionally, the LV stroke volume may also be reduced from impaired diastolic filling.
Note: MS you hear Opening Snap!
Midsystolic click followed by late systolic murmur
What murmur?
Mitral Valve Prolapse
Know that MR can be primary & secondary (ex. decompensated HF)
Image of Secondary Mitral Valve Regurgitation
What are the two primary forms of genomic instability in the pathogenesis of colon cancer?
- microsatellite (15%)
- failure of mismatch repair pathway (MMR) from mutations in MLH1, MSH2, APC, and other genes, results in the propagation of aberrant DNA and accumulation of mutations that predispose to malignant transformation
- seen in familial syndromes: Lynch, FAP - chromosome instability (85%)
- specific activating mutations of oncogenes (i.e. KRAS) or LOF mutations of tumor suppressor genes (i.e. p53) results in aberrant entry into the cell cycle (and oncogenic potential)
- genomic instability occurs during chromosomal replication (S), fidelity checks of the chromosomes (G2) and during separation of the chromosomes (M phase) during cell cycle
- sporadic colon cancers
