nbme 18

Question 1

Alcohol denatures ______ and disrupts _________.

Answer 1

Alcohol denatures proteins and disrupts cell membranes

Question 2

Alcohol inactivates viruses with what characteristic?

Answer 2

Envelope.

Question 3

Contraction vs. Compression vs. Resporption Atelectasis

Answer 3

Contraction Atelectasis occurs when either local or generalized fibrotic changes in the lung or pleura hamper expansion and increase elastic recoil during expiration. Causes include granulomatous disease, necrotising pneumonia and radiation fibrosis

Compression atelectasis follows from filling of the pleural cavity with fluid, tumor, blood, or air (pneumothorax). It is most common in people with heart failure who develop pleural fluid. The mediastium shifts away from the affected lung.

Absorption atelectasis: 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

Question 4

What are dendritic cells of the skin called?

Answer 4

Langerhan’s cells.

Question 5

Berbeck granules are derived from what kind of cells?

Answer 5

Dendritic cells

Question 6

How does enterococcus acquire resistance against vancomycin?

Answer 6

Acquired resistance to the antibiotic vancomycin through
the uptake of a plasmid that has the resistance.
VRE can be resistant to not just vancomycin, it
can be resistant to other antibiotics commonly
used for Enterococcus infections such as
aminoglycosides, and ampicillin.

Question 7

What is injured in Guillain Barre?

Answer 7

Myelinated primary afferents

Ascending symmetric numbness and paralysis that begins in the lower extremities. Due to autoimmune destruction of schwann cells–> inflammation and demylination of peripheral nerves and motor fibers.

Question 8

What are some features of renal artery stenosis?

Answer 8

Renal artery stenosis: Auscultation of abdominal bruits on physical exam; increased plasma renin levels.

Bilateral renal artery stenosis is worsened when given ACEI. This causes a further increase in renin.

Question 9

What are the two targets of HAART therapy?

Answer 9

Reverse transcriptase and protease.

If therapy stops working, must be these two target proteins of virus mutated.

Question 10

What is LAD (type I)?

Answer 10

Defect in LFA-1 INTEGRIN (CD18) protein on phagocytes; impaired migration and chemotaxis; autosomal recessive.

Recurrent skin and mucosal bacterial infections, absent pus, impaired wound healing, delayed (> 30 days) separation of umbilical cord.

Question 11

Findings of LAD

Answer 11

Increased neutrophils in blood. Absence of neutrophils at infection sites.

Question 12

What is an integrin?

Answer 12

Integrins are proteins that function mechanically, by attaching the cell cytoskeleton to the extracellular matrix (ECM), and biochemically, by sensing whether adhesion has occurred.

Question 13

Vesicular lesions or vesiculoulcerative lesions. What should these be treated with?

Answer 13

HSV or VZV.

Treat with acyclovir.

Question 14

What change is seen at the cellular level in patients taking statins?

Answer 14

Statins competitively and reversibly inhibits HMG-CoA reductase which is the rate limiting enzyme of cholesterol synthesis. So transcription of enzyme would be upregulated to compete.

Question 15

Tonicity of each section of the kidney:

Answer 15

PCT = isotonic
Thin descending = hypertonic
Thick ascending = hypotonic
DCT = hypotonic
Collecting duct = hypertonic

Question 16

Subepidermal bullae

Answer 16

Bullous pemphigoid.

Less severe than pemphigus vulgaris. Type II hypersensitivity reaction: involves IgG antibody
against hemidesmosomes (epidermal basement membrane; antibodies are “bullow” the
epidermis).

Question 17

Chronic Gastritis

Answer 17

Continuous inflammation of the gastric mucosa leads to mucosal atrophy and epithelial metaplasia (hence “chronic” and “atrophic”). Based on the location of the injury and the causative agent, chronic gastritis is divided into types A and B.

Type A: Affects the fundus and body of the stomach and spares the antrum. Typically secondary to pernicious anemia (also known as autoimmune gastritis). It is associated with antibodies to parietal cells (specifically targeting the H+–K+ ATPase) and to the intrinsic factor (IF). It leads to achlorhydria with consequent hypergastrinemia.

Type B: Antral-predominant, sparing the fundus and body. Typically secondary to chronic Helicobacter pylori infection.

Question 18

c-jun

Answer 18

• transcription factor
• antiapoptotic
• Overexpression of c-jun in cells results in decreased level of p53 and p21, and exhibits accelerated cell proliferation

Question 19

How is c-jun and endothelin related to LV hypertrophy?

Answer 19

C-jun = Increase transcription –> Increased cell size and/or number of cells –> increase LV hypertrophy.

Endothelin is increased because it causes vasoconstriction.

Question 20

Nitrous oxide has ______ blood and lipid solubility, and thus fast induction and low potency.

Answer 20

Nitrous oxide has decreased blood and lipid solubility, and thus fast induction and low potency.

Question 21

Halothane, propofol, and thiopental have ____ lipid and blood solubility, and thus high potency and slow induction.

Answer 21

Halothane, propofol, and thiopental have increased lipid and blood solubility, and thus high potency and slow induction.

Question 22

Osteosarcoma x-ray & histo:

Answer 22

X-Ray = Codman triangle (from elevation of periosteum) or sunburst pattern on x-ray. Think of an osteocod (bone fish) swimming in the sun.

Histo: Pleomorphic osteoid-producing cells (malignant osteoblasts).

Question 23

What antineoplastic can be used to treat Hep B and C and Kaposi sarcoma?

Answer 23

IFN-alpha

Question 24

What is one common etiology that can lead to a chronic increase in hydrostatic pressure in bowman’s space?

Answer 24

BPH (obstruction —> increased hydrostatic pressure in BS due to back pressure of urine)

Question 25

What are granulomas composed of?

Answer 25

Epithelioid cells (macrophages with abundant pink cytoplasm) with surrounding multinucleated giant cells and lymphocytes.

Question 26

Cell types in acute vs. chronic inflammation

Answer 26

Acute: Characterized by neutrophils in tissue often with associated edema.

Chronic: Inflammation of prolonged duration characterized by infiltration of tissue by mononuclear cells (macrophages, lymphocytes, and plasma cells). Tissue destruction and repair (including angiogenesis and fibrosis) occur simultaneously. May or may not be preceded by acute inflammation.

Question 27

Homeobox (Hox) gene

Answer 27

Involved in segmental organization of embryo in a craniocaudal direction. Code for transcription
factors. Hox mutations Ž appendages in wrong locations.

Question 28

Risk Reduction Equation

Answer 28

RR= risk of developing dz in exposed group/risk of developing dz in unexposed group or standard treatment

Question 29

Antigenic Shift vs. Drift

Answer 29

SHIFT: Causes pandemics. Reassortment of viral genome segments, such as when segments of human flu A virus REASSORT with swine flu A virus.

DRIFT: Causes epidemics. Minor (antigenic drift) changes based on random mutation in hemagglutinin or neuraminidase genes.

Question 30

Porphoryia cutanea tardia

Answer 30

The most common type of porphyria is
porphyria cutanea tarda. The deficient or defective
enzyme is uroporphyrinogen decarboxylase. At the start
of heme synthesis, succinyl CoA and glycine combine to
form ALA (via ALA synthase), the very start of heme
synthesis.