Qbank Week 7.1

Question 1

What is the pathogenesis of acute hemolytic transfusion reaction?

Answer 1

Type II hypersensitivity. Presents as fever and chills, hypotension, dyspnea, chest and back pain, hemoglobinuria. Can develop DIC and renal failure. Acute hemolytic reactions happen in minutes to hours of blood transfuion. Usually due to ABO incompatibility. Anti-ABO antibodies (IgM) in recipient bind the corresponding antigens on transfused donor erythrocytes –> complementation. C3a and C5a are anaphylatoxins –> vasodilation and shock.

Question 2

What are the features of hyperacute rejection?

Answer 2

Type 2 hypersensitivity, complement, widespread thrombosis of grafe vessels, ischemia and necrosis

Question 3

What are the features of acute rejection?

Answer 3

CD8+ T cells against donor MHC. Vasculitits of graft vessels with dense interstitial lymphocytic infiltrate. Need immunosuppressants.

Question 4

What are the features of chronic rejection?

Answer 4

CD4+ T ccells respond to recipient APCs presenting donor peptides, including allogeneic MHC. Recipient T cells react and secrete cytokines – proliferation of vascular smooth muscle, parenchymal fibrosis. Arteriosclerosis.

Question 5

What are the features of GVH disease?

Answer 5

Grafted T cells proliferate and reject host with foreign proteins. Rash, jaundice, diarrhea, hepatosplenomegaly.

Question 6

If labs show elevated alkphos, what enzyme should you check next?

Answer 6

g-glutamyl transpeptidase (GGTP) is an enzyme predominately in hepatocytes and biliary epithelia, but not bone. This helps determine if elevated ALP is due to hepatic of bony origin.

Question 7

What is the role of ATP in skeletal and cardiac muscle contraction?

Answer 7

ATP releases the myosin head from its acting binding site and then energizes a conformational change that resets myosin head to contract again the next time it binds to actin. If there is no ATP, the cross-bridge between myosin and acting will persist (rigor mortis).

Question 8

How does body clear a dust particle <2um?

Answer 8

Taken up by MO and stimulate connective tissue growth. The pneumoconioses are diseases that result from the inhalation of fine dust particles.

Particles 10-15 um are trapped in mucociliary transport. The finest ones reach terminal bronchioli and alvoli and are phagocytosed by MO.

Question 9

Treatment for MRSA and their SE? Which one causes myopathy?

Answer 9

1. Vancomycin (block glycopeptide polymerization): red man syndrome, nephrotoxicity
2. Daptomycin (depol of cellular membrane): myopathy and CPK elevation, inactivated by pulmonary surfactant.
3. Linezolid (inhibit bacterial protein synth, binds 50S): thrombocytopenia, optic neuritis, high risk for serotonin syndrome.

Question 10

What conditions are strongly a/w papillary necrosis?

Answer 10

1. Sickle cell disease/trait
2. Analgesic nephropathy: phenacetin, NSAIDs (inhibit RBF by decr PGs)
3. DM: NEG (glycos)
4. Acute pyelonephritis and UTI: edematous interstitium compresses medullary vasculature

Question 11

What does papillary necrosis look like microscopically?

Answer 11

Coagulative infarct necrosis with preserved tubule outlines. After acute phase, scars can be seen on cortical surface as fibrous depressions replace the inflammatory foci.

Question 12

What is first line treatment for nausea due to GI upset (gastroenteritis, chemo, general anesthesia)?

Answer 12

5HT3 receptor antagonists are used for visceral nausea d/t GI insults. Antihistamines and anticholinergics (scopolamine) are used for vestibular nausea. Dopamine antagonists are used for N a/w migraine.

Question 13

IL-2 is used in which cancers?

Answer 13

RCC and melanoma. IL-2 regulates activation and differentiation of T cells to aid in tumor cell destruction.

Question 14

Immigrant from cambodia has exertional dyspnea and PMH of bilateral knee swelling as child. Murmur heart over apex. What is the cause?

Answer 14

Mitral regurgitation secondary to rheumatic fever. MR is a blowing, holosystolic murmur best heard over apex.

Question 15

What causes hypoglycemia in a neonate of mother with gestational DM?

Answer 15

Diffuse hyperplasia of islets. If BG is poorly controlled during pregnancy, the high glucose level causes beta cell hyperplasia in the fetus. Once delivered, the baby continues to produce insulin and then experiences hypoglycemia.

Question 16

How does lamotrigine work and what sx do you need to watch out for?

Answer 16

Lamotrigine is an anticonvulvant, blocks voltage gated sodium channels, partial and generalized seizures. Must watch for SJS or TEN (toxic epidermal necrolysis, >30% skin). Presents as flu-like sx followed by extensive cutaneous and mucosal lesions (epidermal necrosis and subepidermal bullae).

Question 17

Patient had stroke and dies. Autopsy shows pale wedge-shaped lesion in right kidney. Patient died from what?

Answer 17

Stroke and renal infarc at the same time is most likely from a systemic emobli. These arise from LA or LV after MI, ventricular aneursym, afib, aortic aneurysm, and infective endocarditis.

Question 18

How is the palate formed?

Answer 18

From the intermaxillary segment (primary palate) and maxillary prominences (secondary palate). If the palantine shelves fail to fuse with primary palate –> cleft lip.

Question 19

What results in cleft lip?

Answer 19

Maxillary prominances fail to fuse with intermaxillary segment during early embryonic development.

Question 20

What is absolute risk reduction? ARR

Answer 20

Control rate - treatment rate.
NNT: 1/ARR

Question 21

Clinical associations wth Chediak-Higashi syndrome?

Answer 21

Oculocutaenous albinism, peripheral neuropathy, immunodef related to dysfunction of phagocyte phagosome-lysosome fusion.

Question 22

What is the MCC of hydatid cysts in humans and how do you treat it?

Answer 22

Echinococcus granulosus (tapeworm). Usually liver is affected. It demonstrates characterstic encapsulated and calcified cyst (eggshell calcification) that contains fluid and budding cells that will become daughter cysts. Other cyst wall is made of layers of delicate, gelatinous sheets surrounded by thick fibrous capsule.

Surgery + mebendazole or albendazole. NO aspiration as spilling of cysts would cause anaphylactic shock.

Question 23

Without ADH, where is the tubular fluid most concentrated?

Answer 23

Between the descending and ascending limbs of the loop of Henle. It would be most dilute in the collecting ducts.

Question 24

What are some causes of lactic acidosis?

Answer 24

• Enhanced metabolic rate (seizure and exercise)
• Reduced oxygen delivery (cardiac or pulmonary failure, shock, tissue infarction)
• Diminished lactate catabolism due to hepatic failure or hypoperfusion, decreased oxygen utilization (cyanide)
• Enzymatic defects in glycogenolysis or gluconeogenesis.

Question 25

In fragile X syndrome, what is the cause of the clinical syndromes?

Answer 25

Gene methylation. The syndrome is caused by mutation of FMR1 gene on long arm of X chromosome. Increased CGG repeads leads to transcriptional instability which promotes more repeat expansion. The increased number of trinucleotide repeats causes hypermethylation of FMR1 gene –> gene inactivation.

Question 26

What nerve is at risk of getting damaged in thyroidectomy?

Answer 26

The external branch of the superior laryngeal nerve is at risk of injury during thyroidectomy due to its proximity to the superior thyroid artery and vein. It innervates the cricothyroid muscle.

Question 27

What does this myocardial biopsy show?

Answer 27

Anitschkow cells (catepillar cells): plump MO with abudant cytoplasm. Aschoff giant cells: large MO become multinucleated. Surrounded by lymphocytes and plasma cells.
***Acute rhematic fever

Question 28

How does exercise affect blood sugar? What happens in diabetics?

Answer 28

Exercise increases glucose uptake by muscle cells by:

1. Sensitization of muscle cells to action of insulin and
2. Increased insulin-independent glucose uptake into the exercising muscles.

In diabetics, hypoglycemia can be precipitated after vigorous exercise due to increased glucose uptake by muscles and rapid SQ insulin absorption when the injection occurs in a limb that is subsequently exercised.

Question 29

Which enzyme is missing in alkaptonuria?

Answer 29

• Homogentisic acid oxidase
• Alkaptonuria is benign in childhood and matures to arthritis in adult life.
• Homogentisic acid causes pigment deposits in connective tissues–sclera, ear cartilage, large joints and spine (ankylosis).
• Urine turns black when exposed to air (oxidized).

Question 30

What is the embryonic origin of the SVC?

Answer 30

Common cardinal veins

Question 31

What does hyaluronidase do and which bacteria produce it?

Answer 31

Hyaluronidase digests extracellular ground substance and enhances ability to spread.

Made by staphylococci, group A streptococci, and C. difficile.

Question 32

Where are the leads placed in a biventricular pacemaker?

Answer 32

If 3 leads are used for a biventricular pacemaker, the first 2 are place into the right atrium and right ventricle. The third is used to pace the left ventricle.

RA/V leads: traverse the L subclavian vein and SVC.

The 3rd has to go from RA to coronary sinus, which resides in the atrioventricular groove on the posterior aspect of the heart. It is then advanced into one of the lateral venous tributaries in order to optimize LV pacing.

Question 33

How do inhaled anesthetics affect cerebral blood flow?

Answer 33

Almost all volatile anesthetics increase cerebral blood flow (undesirable, increases ICP).

Other side effects include:

• Myocardial depression
• Hypotension
• Respiratory depression (except NO)
• Decreased renal function

Question 34

What are the two ways that leptin works?

Answer 34

1. Decreases neuropeptide Y, which is a potent appetite stimulator in the arcuate nucleus of the hypothalamus.
2. Increases POMC in arcuate nucleus. The cleavage of POMC –> a-MSH, which inhibits food intake.

Question 35

After applying a clip to the right renal artery (hypoperfusion), which cell type would most likely undergo hyperplasia and hypertorphy?

Answer 35

Significant renal artery stenosis causes renal hypoperfusion and activation of RAA. Modified smooth muscle (JG) cells of the afferent glomerular arterioles make renin –> cascade of effects that include systemic vasoconstriction (ATII) and sodium and water retention (aldosterone and ATII). Chronic renal hypoperfusion –> hypertrophy and hyperplasia of JG cells.

Question 36

What is the Hawthorne effect?

Answer 36

The hawthorn (observer) effect is the tendency of study subjects to change their behavior as a result of their awareness that they are being studied.

***Hawk’s observe!

Question 37

What is the Berkson’s bias?

Answer 37

Berkson’s bias refers to selection bias created by choosing hospitalized patients as the control group.

Question 38

What is the pygmalion effect?

Answer 38

The pygmalion effect describes the fact that a researcher’s beliefs in the efficacy of treatment can potentially affect the outcome.

Students that are randomly assigned a high IQ would perform better as a result of unconscious behavior that faciliate their success.

Question 39

What is pure red cell aplasia associated with?

Answer 39

Thymoma (IgG autoantibodes or cytotoxic T lymphocytes), lymphocytic leukemias, and parvovirus B19 (destroys proerythroblasts).

Question 40

How does N. meningitidis gain access to CNS?

Answer 40

First it colonizes nasopharynx, then invades mucosal epithelium and gains access to bloodstream. Then it spreads to the choroid plexus, gains access to CNS through BBB and initiates an inflammatory process.

Question 41

What is the haldane effect?

Answer 41

In the lungs, the binding of oxygen to Hb drives the release of H+ and CO2 from Hb.

In the peripheral tissues, high concentrations of CO2 and H+ facilitate oxygen unloading from Hb (Bohr).

Question 42

What causes the high susceptibility of patients with silicosis of TB infection?

Answer 42

Silicosis impairs the macrophage effector arm of cell mediated immunity (CMI). MO are the main effectors of CMI against intracellular mycobacteria. MO phagolysosomes may be disrupted by internalized silica particles, causing release of silica and still-viable mycobacteria and possibly MO autolysis. The extracellular release of lysosomal enzymes is thought to contribute to alveolar and interstitial lung injury in silicosis.

Question 43

CFTR is what kind of ion transporter? Voltage gated, ATP gated, G protein acitvated, Ca gated, or cGMP gated?

Answer 43

CFTR is a transmembrane ATP-gated chloride channel.

• Voltage-gated ion channels: neurons
• Hormone receptors (other than steroid and thyroid hormone): G-protein activated receptors
• Ca2+ gated K+ channels: one of four main types of K+ channels, everywhere
• cGMP-gated sodium channels: vision

Question 44

PAS+ cells in a liver biopsy would indicate what pathology?

Answer 44

A1AT deficiency is associated with reddish-pink, PAS+ granules of unsecreted, polymerized A1AT in the peripheral hepatocytes.

A1AT is a serum protein that reduces tissue damage caused by inflammation through inhibition of neutrophil elastase.

Question 45

These suffixes indicate what kind of biological agents?

• mab
• cept
• nib

Answer 45

• mab: monoclonal antibody
• cept: receptor molecule
• nib: kinase inhibitor

Question 46

How does H. influenzae spread to the meninges?

Answer 46

Pharynx –> lymphatics –> meninges

Question 47

Where is the chemoreceptor trigger zone (CTZ)?

Answer 47

CTZ is in the area postrema of the dorsal medulla near 4th ventricle. Acute nausea following chemo is d/t stimulation here.

Question 48

Newborn with lethargy, vomiting, and hypotonia in first few days has metabolic acidosis with large anion gap, ketosis, and hypoglycemia. Propionic acid is increased in plasma and urine. What is the deficiency?

Answer 48

Propionyl CoA is derived from AA (Val, Ile, Met, Thr), odd-numbered FAs, and cholesterol side chains.

Congenital deficiency of propionyl CoA carboxylase (converts propionyl CoA to methylmalonyl CoA) –> propionic acidemia.