3/23 - UWorld

Question 1

Possible causes of sensory ataxia (positive Romberg test with eyes closed - testing for proprioception)

Answer 1

Tabes dorsalis (Syphilis) Vitamin B12 deficiency (results in subacute combined degeneration due to abnormal myelin)

Question 2

What are the hormonal effects of functional hypothalamic amenorrhea (e.g. amenorrhea in response to stress, weight loss, or illness)

Answer 2

Underlying cause is decreased Leptin levels (leptin is usually secreted by fat cells in order to decrease appetite; decreased Leptin inhibits pulsatile GnRH release) Decreased GnRH from hypothalamus Decreased LH and FSH Decreased estrogen

Question 3

Immune response of hyperacute transplant rejection (min-hours)

Answer 3

Preformed antibodies (type II hypersensitivity reaction)

Question 4

Immune response of acute transplant rejection (<6 months)

Answer 4

Cellular response: CD8+ T cells activated against donor MHCs (type IV hypersensitivity) Humoral response: Similar to hyperacute except antibodies develop after transplant

Question 5

Immune response of chronic transplant rejection (months-years)

Answer 5

CD4+ T cells respond to APCs presenting donor peptides Both cellular and humoral components (type II and IV hypersensitivity)

Question 6

What structure is best used to identify the appendix during surgery?

Answer 6

Teniae coli The 3 distinct longitiduinal bands converge at the root of the appendix

Question 7

Treatment options for C. Diff

Answer 7

Metronidazole Oral Vancomycin Fidaxomicin (macrocyclic antibiotic that inhibits RNA polymerase) - It inhibits the sigma subunit of RNA pol, which is needed for RNA pol to bind to its promoter - Useful for recurrent C. Diff

Question 8

What type of elimination occurs when the rate of elimination is constant regardless of drug concentration (e.g. constant amount of drug eliminated per unit time, regardless of concentration; e.g. enzymes have been maxed out)

Answer 8

Zero-order elimination

Question 9

What type of elimination occurs when the rate of elimination is directly proportional to drug concentration (e.g. a fixed proportion of the drug is eliminated per unit time)

Answer 9

First-order elimination

Question 10

What is the Hawthorne effect?

Answer 10

Aka observer effect Tendency of study subjects to change their behavior as a result of their awareness that they are being studied Think: Hawthorne = hawk, observing from above

Question 11

What is Berkson’s bias?

Answer 11

Selection bias created by choosing hospitalized patients as the control group Think: Dr. Burk = picked from within the hospital (Burk and Christina fo lyfe)

Question 12

Pygmalion effect?

Answer 12

Researcher’s belief in the efficacy of treatment can change the outcome Aka self-fulfilling prophecy

Question 13

Drugs that are substrates of CYP450

Answer 13

Always Think When Outdoors Anti-epileptics Theophylline Warfarin OCPs

Question 14

Drugs that are CYP450 inducers

Answer 14

Chronic alcoholics Steal Phen-Phen and Never Refuse Greasy Carbs

Chronic alcohol use

St. John’s wort

Phenytoin

Phenobarbital

Nevirapine

Rifampin

Griseofulvin

Carbamazepine

Guiness, Coronas, ‘n PBRS, induce chronic alcoholism

Griseofulvin

Carbamazepine

Nevirapine

Phenytoin

Barbiturates

Rifampin

St. John wort

Chronic alcoholism

Question 15

Drugs that are CYP450 inhibitors

Answer 15

SICKFACES.COM Sodium valproate Isoniazid Cimetidine Ketoconazole Fluconazole Acute alcohol abuse Chloramphenicol Erythromycin (macrolides) Sulfonamides Ciprofloxacin Omeprazole Metronidazole

Question 16

Structures of the female pelvis

Answer 16

Question 17

How does dexamethasone suppression test help in the diagnosis of Cushing’s

Answer 17

Dexamethasone (corticosteroid) will exert negative feedback and cause decreased ACTH in Cushing’s disease (ACTH-secreting pituitary adenoma) Dexamethasone will have no effect with ectopic ACTH production (e.g. small cell lung cancer)

Question 18

How does CRH stimulation test help in the diagnosis of Cushing’s

Answer 18

CRH will cause increased ACTH and cortisol in Cushing’s disease (ACTH-secreting pituitary adenoma) CRH will have no effect on ACTH and cortisol in ectopic source of ACTH

Question 19

What is the difference between Cushing’s Syndrome and Cushing’s disease?

Answer 19

Syndrome - increased cortisol due to a variety of causes Disease - ACTH-secreting pituitary adenoma

Question 20

How do nitrites cause poisoning?

Answer 20

Nitrites induce the conversion of Fe2+ to Fe3+, creating methemoglobin which binds tightly to cyanide but cannot carry oxygen Methemoglobinemia does not change pO2 (this is a measure of O2 dissolved in plasma and unrelated to Hb function)

Question 21

What is the protein-targeting mechanism that marks proteins destined for lysosomes

Answer 21

Proteins destined for the lysosome require phosphorylation of specific mannose residues to ensure proper transit through the golgi apparatus

Question 22

What is the term that describes presence of both normal and mutated mitochondrial DNA, resulting in variable expression in mitochondrially inhereted disease

Answer 22

Heteroplasmy

Question 23

What is the term that described phenotypes that vary among individuals with the same genotype

Answer 23

variable expressivity

Question 24

What is it called when mutations at different loci can produce a similar phenotype

Answer 24

Locus heterogeneity

Question 25

What is it called when different mutations at the same locus can produce the same phenotype

Answer 25

allelic heterogeneity

Question 26

What is Ebstein’s anomaly and what drug is it caused by?

Answer 26

Ebstein’s anomaly: -Apical displacement of the tricuspid valve leaflets (down into the R ventricle) -Atrialization of R ventricle -Decreased volume of R ventricle Caused by lithium exposure

Question 27

Describe renal handling of Creatinine

Answer 27

Similar to inulin, except a small amount is also secreted Can also approximate GFR but is a slight overestimate due to secretion

Question 28

Describe the renal handling of Cystatin C

Answer 28

Filtered with no active reabsorption Is metabolized within the renal tubular cells so there is variable urinary excretion

Question 29

Describe the renal handling of urea

Answer 29

Filtered and reabsorbed (less clearance than inulin)

Question 30

What disease causes koilocytes, and what are they

Answer 30

HPV

Koilocyte is an immature squamous cell with dense, irregularly staining cytoplasm and perinuclear clearing

Also has enlarged pyknotic nucleus where chromatin has condensed as part of the apoptosis process, giving it a “raisinoid” appearance

Question 31

What maternal serum tests can be done to test for neural tube defects

Answer 31

Alpha-fetoprotein and acetylcholinesterase

Both are results of incomplete neuropore closure, allowing them to leak from the neural tube into the amniotic cavity and then crossing the placenta

Question 32

What is another name for the infundibulopelvic ligament?

Answer 32

Suspensory ligament

Question 33

What does two structures does the suspensory ligament connect?

Answer 33

Ovaries to lateral pelvic wall

Question 34

What structures does the suspensory ligament contain?

Answer 34

Ovarian vessels

Question 35

What structure is at risk of injury during an oophorectomy?

Answer 35

Ureter

During an oopherectomy you should ligate the ovarian vessels (within the infundibulopelvic ligamant aka suspensory ligament), which lie near the ureter

Question 36

What 2 structures does the cardinal ligament connect? And what structures does it contain?

Answer 36

Connects the cervix to side wall of the pelvis

Contains uterine vessels

Question 37

What structures does the round ligament connect?

Answer 37

Uterine fundus to labia majora

Question 38

What is the broad ligament and what structures does it connect?

Answer 38

Fold of peritoneum that comprises the mesosalpinx, mesometrium, and mexovarium

Connects the uterus, fallopian tubes, and ovaries to the pelvic side wall

Question 39

What two structures does the ovarian ligament connect?

Answer 39

Ovary to the lateral uterus