UWorld Practice Questions #2 Flashcards
1
Q
What is omaluzimab and what is it used to treat?
A
It is anti-IgE antibody therapy that is approved for use in moderate to severe persistent asthma.
2
Q
What do the shigella, campylobacter, giardia, entamoeba histolytica have in common?
A
The have very low ID50s.
3
Q
Which two cells/tissues can’t use ketones for energy and why?
A
Erythrocytes can’t because they lack mitochondria which are required to convert ketones in acetyl CoA which is the process that generates energy.
Liver can’t utilize ketones for energy b/c they lack the enzyme thiophorase which is required to convert acetoacetate to acetyl CoA as part of the energy generation process.
4
Q
What is glycopyrrolate and what is it used to treat?
A
It is a selective muscaranic antagonist and can be used to treat the side effects of the cholinesterase inhibitors used to treat myasthenia gravis.
5
Q
What is the second line preventative therapy for gout and in what population is it contraindicated?
A
Uricosuric agents like probenecid are 2nd line preventive therapy and they work by increasing the excretion of uric acid in the kidneys. As such, they are contraindicated in pts w/ PMH of renal stones.
6
Q
What is the cell to cell connection (if any) of osteocytes?
A
They are connected via gap junctions. Important for sharing signals, waste products and nutrients.
7
Q
What is a cholesteatoma?
A
It is a collection of squamous cell debris that forms a round, pearly mass behind the tympanic membrane in the middle ear.
8
Q
Why does M. leprae tend to infect skin and outer surface body areas whereas TB causes visceral disease?
A
Because M. leprae grows best at temperatures below core body temperature.
9
Q
What is it meant by saying that two genetic loci are in linkage disequalibrium?
A
This means that the two alleles are inherited together more or less commonly than chance alone given their individual allele frequencies.
10
Q
Which drug inhibits host DNA synthesis more, acyclovir or gancyclovir?
A
Gancyclovir. This is why one of its side effects is neutropenia, which can be exacerbated when combined w/ other drugs that can cause bone marrow suppression like TMP-SMX.
11
Q
What sort of drugs are pramipexole and ropinirole? What can they be used to treat?
A
They are dopamine agonists and as such can be used to treat Parkinson’s disease.
12
Q
What sort of drugs are entacapone and tocapone? WHat do they treat?
A
They are catechol-O-methyltransferase (COMT) inhibitors and as such prevent the degradation of levodopa in the periphery. They treat Parkinson’s disease.
13
Q
What is the mechanism w/ which amantadine treats parkinson’s disease?
A
It increases dopamine release and decreases dopamine reuptake.
14
Q
What is one way to distinguish btwn prospective cohort study and cross-sectional study?
A
In a cross-sectional study you are looking at exposures and outcomes at the same time. Whereas in a prospective cohort study you look at exposures in the present and then way down the line you look at who develops your outcome.
15
Q
What is AngII’s effect at the kidney?
A
Causes efferent arteriolar vasoconstriction.
16
Q
The afferent limb of the pupillary reflex involves what?
A
The retina, optic nerve, optic chiasm, optic tract and the pretectal nucleus in the midbrain. Damage to these can produce a Marcus-Gunn pupil.
17
Q
Embryologically, what happens that results in hypospadias?
A
There is failure of fusion of the urethral folds.
18
Q
What sort of toxin causes staph scalded skin syndrome?
A
The exfoliatin exotoxin. Works by cleaving desmoglein in desmosomes.
19
Q
Being oxidase positive means you possess what enzyme?
A
Cytochrome oxidase
20
Q
Insulin lispro, aspart and glulisine are all what types of insulin?
A
Short acting insulins that are best for post-prandial glycemic control.
21
Q
What sort of insulin is NPH?
A
An intermediate acting insulin that has onset about 2 hours after admin, peaks in 4-12 hours and lasts about 18 hours.
22
Q
Is it bipolar I or II where the pt has hypomanic episodes and major depression episodes?
A
Bipolar II. Note that in hypomania it is less severe than mania and there is no psychosis (which can accompany manic periods in bipolar I).
23
Q
Repeated blocks of glycine-X-Y, with X and Y being proline, hydroxyproline, or hydroxylysine is characteristic of what protein?
A
Collagen
24
Q
What is dyschezia? What location of endometriosis does it suggest?
A
Pain with defecation. Suggests endometriosis in the rectouterine pouch (aka pouch of douglas aka posterior cul-de-sac).
25
What are the four muscles of mastication? Which one lowers the jaw while the other 3 close the jaw?
Muscles = masseter, medial pterygoid, lateral pterygoid and temporalis.
Lateral pterygoid is unique in that it lowers the jaw while the others close the jaw.
26
The most commonly torn ligament w/ ankle inversion sprains is the?
anterior talofibular ligament
27
The nodes of Ranvier are sites of _____ capacitance and ______ resistance?
High capacitance (thus rapid AP propagation) and low resistance.
28
What artery runs in the radial groove along with the radial nerve?
The radial collateral artery.
29
______ emphysema occurs in pts w/ alpha1-antitrypsin deficiency whereas _______ emphysema tends to be what is seen in chronic smokers?
alpha 1 --> panacinar emphysema
smokers --> centriacinar emphysema
30
In the presence of MIF, what do the paramesonephric ducts become?
The appendix testes (a vestigial remnant) and the prostatic utricle.
31
On physical exam how can you distinguish btwn bullous pemphigoid and pemphigus vulgaris?
In bullous pemphigoid the bullae do NOT rupture easily to touch (negative Nikolsky sign) whereas in pemphigus vulgaris they do.
32
Endomysial inflammation showing infiltrate of macrophages and CD8+ lymphs is characteristic of?
Polymyositis
33
Perimysial inflammation of CD4+ cells and atrophy of the muscle is characteristic of?
Dermatomyositis
34
What is the triad of scleroderma?
Autoimmunity, non-inflammatory vasculopathy, and collagen deposition w/ fibrosis.
*This is the disease that can present w/ taut skin or CREST syndrome.
35
What is the treatment of sclerodermal renal crisis
Short acting ACEIs like catopril.
36
What is the only tx that can be given in Measles infection?
Vitamin A. It can reduce morbidity and mortality.
37
What is a cherry hemangioma?
It is a benign capillary hemangioma that occurs in the elderly usually and can bleed a lot when ruptured. Basically looks like a red to purple to black lagoon of blood.
38
What is the characteristic triad of ataxia telangiectasia? What gene is mutated?
Triad = cerebellar ataxia, telangiectasias (superficial blanching nests of distended capillaries) and recurrent sinopulmonary infections.
ATM gene is mutated and it is responsible for DNA repair.
39
What are the common adverse effects of lithium?
Hypothyroidism, Ebstein anomaly, DI and tremor.
40
The transmembrane receptors for ANP and BNP are linked to what enzyme?
Guanylyl cyclase. Causes cGMP levels to rise and leads to vasodilation.
41
How is carotid sinus massage able to treat paroxysmal supraventricular tachycardia?
Massage increases barorecptor firing which is transmitted to the vagal nucleus (via CN9). This causes an increase in vagal parasympathetic tone which will slow conduction thru the AV node and prolong the AV refractory period.
42
What are two txs for nephrogenic DI
HCTZ and indomethacin
43
What makes up the splicesome that does mRNA processing?
snRNPs which are made up of snRNA and other proteins, as well as additional proteins.
44
what are anti-Smith (highly specific for SLE) antibodies targeting?
snRNPs for the splicesome (removes introns).
45
What is the RNA polymerase whose function is restricted to the nucleolus?
RNA pol I. It works to make most of the rRNA.
46
Which RNA polymerase makes the tRNA?
RNA pol III
47
True or false, insulin directly suppresses glucagon secretion by acting on alpha cells in the pancreas?
True!
48
Distinguish between agoraphobia and social anxiety disorder.
In agoraphobia pts fear public places, enclosed spaces, being in lines or crowds or leaving home. Conversely, in social anxiety disorder pts fear embarrassment or scrutiny from others and experience anticipation anxiety and social avoidance when it comes to things like parties.
49
Describe the pathogenesis of polyol pathway overactivity that occurs in uncontrolled hyperglycemia.
In uncontrolled hyperglycemia, aldose reductase converts glucose to sorbitol, which is later converted into fructose. However, this second conversion can get overwhelmed by the hyperglycemia and sorbitol can accumulate. This creates osmotic pressure in tissues and can lead to damage (cataracts, retinopathy, etc.). Additionally, aldose reductase consumes NADPH and so that deficiency can exacerbate damage as oxidate damage occurs (oxidative stress from the depletion of NADPH).
50
Absence of CD18 suggests what disorder?
Leukocyte adhesion deficiency.
51
Infants with hydrocephalus develop what if untreated?
Muscle hypertonicity, hyper-reflexia, macrocephaly and poor feeding. Can get developmental delay too.
52
How should you manage somatic symptom disorder?
Schedule regular visits with the patients primary care provider and avoid un-necessary dx testing and referrals to specialists.
53
What distinguishes schizoaffective disorder from major depressive disorder w/ psychotic features?
In MDD w/ psychotic features the psychotic features only occur during the depressed mood whereas schizoaffective disorder requires the presence of psychotic features in the absence of depression for at least 2 weeks.
54
What are Leptin's actions in the arcuate nucleus of the hypothalamus?
Decreases production of NPY which is a potent appetite stimulant, and increases production of POMC which will in turn reduce food intake.
55
Hyperplasia of the glomerular layer of the adrenal cortex is associated w/ what disease?
Conn syndrome
56
What is the flora the is generally causing UTIs?
It is generally flora that originate from fecal flora and includes gram negative rods and enterococcus. It is NOT generally the urethral flora (lactobacilli, non-pathogenic staph and strep) as these do not multiply readily in the urine and generally do NOT cause infection.
57
Name 5 common triggers for candida vaginitis
Antibiotic use, high levels of estrogen (i.e. pregnancy), systemic corticosteroid therapy, uncontrolled DM, and immunosuppression.
58
What is the most common neurologic complication of VZV infection (i.e. shingles)?
Post-herpetic neuralgia --> pain in the dermatomal area where the skin rash occurred. It persists after rash resolves.
59
What causes the dynamic left ventricular outflow tract obstruction (LVOT) to worsen in patients with HOCM?
Decreased L ventricular preload (or afterload) worsens LVOT obstruction.
60
What sorts of meds should be avoided in HOCM? Why?
Those that decrease L ventricular preload like systemic vasodilators (dihydropyridine CCBs, nitroglycerin and ACEIs) as well as diuretics. This is because they will worsen LVOT obstruction.
61
What sorts of meds help reduce LVOT obstruction in HOCM?
Negative inotropic agents like B blockers, non-dihydropyrimidine CCBs like verapamil, and disopyramide.
62
Which amino acid is a precursor for serotonin?
Tryptophan
63
What is cyproheptadine used to treat?
Serotonin syndrome (as the med has serotonin antagonist properties).
64
Which patients are most at risk for "first dose hypotension" when starting an ACEI?
Those w/ high renin activity like pts w/ HF or those taking a diuretic.
65
Where is acid phosphatase found and what does it do?
Found in the lysosome of most cells and it hydrolyzes organic phosphates.
66
What are caspases?
A family of proteases that are essential for apoptosis.
67
What is the most common location of blunt aortic trauma (traumatic aorta rupture caused by sudden deceleration that results in extreme stretching and torsional forces affecting the heart and aorta)?
The aortic isthmus as it is tethered by the ligamentum arteriosum so it is relatively immobile relative to the adjacent ascending and descending aorta.
68
What are 3 effects of DHT in a male?
Male pattern hair growth, external genitalia, growth of the prostate.
69
How does HBV infection initially present?
Like a serum sickness illness w/ fever, rash, arthralgias, etc as well as hepatomegaly and elevated transaminases.
70
What are the short acting benzos? Half live less than 6 hours
Triazolam, oxazepam, and midazolam.
71
What are the intermediate acting benzos? (half-life 6-24 hours)
lorazepam, alprazolam, and temazepam
72
What are the long acting benzos (half-life > 24 hours)
diazepam, chlordiazepoxide, and flurazepam.
73
Which group of benzos have a higher addictive potential?
Those with a shorter half-life.
74
Only the polyprotein of the _____ gene in HIV is glycosylated
env gene. These products become gp160 and are then cleaved to become gp41 and gp120.
75
How long can patients still have viable sperm after vasectomy?
Up to 3 months and for at least 20 ejaculations after the procedure.
76
Having the ApoE4 allele places someone at risk for what?
Alzheimer's disease
77
What three genes have been found to be associated w/ early onset familial Alzheimer's disease?
Amyloid precursor protein (chromosome 21), presenilin 1 (chromosome 14), and presenilin 2 (chromosome 1)
78
Why is propofol's onset of action and termination of anesthesia rapid?
Because it is highly lipophilic so it initially distributes to organs receiving a ton of blood flow (i.e. brain where it has its effect) but then is redistributed to less vascular tissue like bone and adipose and this redistribution is what causes its effect to terminate.
79
Name 8 CYP450 inducers
Carbamazepine, barbiturates, phenytoin, rifampin, griseofulvin, St. John's wort, modafinil, cyclophosphamide
80
Name 8 CYP450 inhibitors
Amiodarone, cimetidine, fluroquinalones, clarithromycin, azole antifungals, grapefruit juice, isoniazid, ritonavir
81
What sort of drug is ramelteon?
A melatonin agonist.
82
What drug is ideal for tx of insomnia in the elderly?
Ramelteon. This is b/c it doesn't have the bad side effects of other options like benzos (delirium and fall risk) or diphenhydramine (anticholinergic effects)
83
The vascular type of Ether-Danlos (associated w/ increased risk for aortic aneurysm) is due to a defect in what?
Defect in type III collagen. These pts also often demonstrate thin/translucent skin and increased varicosity.
84
The branchial arches are composed of what two types of embryologic tissue?
Neural crest cells and mesoderm.
85
How does mercury poisoning present?
Intention tremor, nephrotoxicity, and change in personality
86
How does iron toxicity present?
Vomiting, diarrhea, gastrointestinal bleeding, cyanosis, and metabolic acidosis.
87
How does Pompe disease present? What enzyme deficiency causes it?
By the sixth month of life, children with Pompe disease experience developmental delays, feeding problems, and eventual heart failure. Skeletal muscle and the liver are also affected. ECG shows short PR intervals with large QRS complexes signaling biventricular hypertrophy. Cardiomegaly is also evident on x-ray of the chest.
It is due to enzyme deficiency of α1,4-glucosidase (aka acid alpha glucosidase) which is necessary for hydrolysis of the outer branches of glycogen.
88
What does alpha galactosidase A deficiency cause? How does it present?
This causes Fabry's disease. Ceramide trihexoside accumulates, resulting in peripheral neuropathies of the hands and feet, angiokeratomas, and cardiovascular and renal disease.
89
What does beta-glucocerebrosidase deficiency cause and how does it present?
Causes Gaucher's disease. Presents w/ hepatosplenomegaly, aseptic necrosis of the femur, bone crises, and Gaucher cells
90
What does glucose-6-phosphatase deficiency cause? How does it present?
Causes type I glycogen storage disease (aka Von Gierke disease). Patients have severe fasting hypoglycemia with large stores of glycogen in the liver, hepatomegaly, and increased blood lactate levels.
91
What does skeletal muscle glycogen phosphorylase deficiency cause? How does it present?
Causes type V glycogen storage disease (aka McArdle's disease). Pts have cramping and myoglobinuria with strenuous exercise. This can lead to hypotonia.
92
What dictates the severity of disease in tetralogy of fallot?
The degree of pulmonic stenosis as this will dictate the degree of R --> L shunting and hypoxia.
93
What is a pneumonic to remember the causes of renal papillary necrosis? It manifests as gross hematuria and proteinuria.
Consider the mnemonic POSTCARDS for causes of papillary necrosis: Pyelonephritis, Obstruction of urinary tract, Sickle cell, TB, Cirrhosis/Chronic alcoholism, Analgesic abuse, Renal transplant rejection/Radiation, Diabetes, Systemic vasculitis
94
How does the drug ribavirin work?
It is a nucleoside antimetabolite that interferes with duplication of viral genetic material.
95
What happens to C-peptide of insulin?
It is cleaved from proinsulin by endopeptidases while in the actual secretory granules. As such, C peptide is released along w/ insulin.
96
Describe DRESS syndrome
DRESS = drug reaction w/ eosinophilia and systemic symptoms. It occurs 2-8 weeks after drug exposure and signs and sxs include fever, general lymphadenopathy, a morbiliform race and facial edema. Labs show eosinophilia, elevated transaminases, and atypical lymphocytosis.
97
Name some drugs that are common offenders in DRESS syndrome
Anticonvulsants (carbamazepine, phenytoin), allopurinol, sulfonamides and antibiotics.
98
What gene is mutated in spinal muscular atrophy? What are the consequences of said mutation?
The SMN1 gene which codes for a protein involved in the assemby of snRNPs. As such, the slicesome is dysfunctional and there is degeneration of anterior horn cells in the spinal cord.
99
What happens when the ribosome encounters a stop codon (UAA, UAG or UGA)?
A releasing factor binds to the ribosome stimulating release of the formed polypeptide and dissolution of the ribosome mRNA complex.
100
Narcolepsy is most commonly due to deficiency of what?
Hypocretin-1 (orexin-A) and hypocretin-2 (orexin-B). Low levels of hypocretin-1 in the CSF is suggestive of this disease.
101
How is digoxin cleared?
It is renally eliminated.
102
What is the best choice tx for VTE in pregancy?
Low molecular weight heparins like enoxaparin (especially during early stages of pregnancy).
103
Which cholesterol lowering medication increases the propensity to form gallstones? Why?
Fibrates like genfibrozil. It's because they inhibit the rate limiting enzyme in bile acid synthesis (cholesterol 7-alpha-hydroxylase) and this means less pile so greater propensity for cholesterol to precipitate in the gallbladder.
104
What does southwestern blot detect?
DNA-bound proteins.
105
Which sort of fat storage correlates most strongly with insulin resistance?
Excess visceral fat. Why measurement of waist circumference is important as this is an indirect measure of visceral fat.
106
What pattern of dyslipidemia characterized insulin resistance?
High triglycerides and low HDL.
107
Why is infarcted tissue rarely seen w/ PE?
Because of the collateral circulation including the bronchial system which will provide oxygen and nutrients to the occluded area such that no infarction occurs.
108
What are the three cardinal findings in Wiskott-Aldrich syndrome?
Eczema, recurrent infections, and thrombocytopenia. Note that this disorder is X-linked.
109
What is causing the autoimmunity seen in Chediak-Higashi syndrome?
Dysfunction of the phagocyte phagosome-lysosome fusion.
110
What does abciximab do?
It inhibits the GP IIb/IIIa receptor from binding to fibrinogen and thus inhibits formation of a platelet plug.
111
What are some findings or bacterial features that can clue you in to MAC infection?
Marked anemia, elevated alk phos, hepatosplenomegaly, elevated lactate dehydrogenase and the finding of an acid-fast bacterium that has optimal growth at 41 degrees C.
112
What is prophylactic tx against MAC?
Macrolide like azithromycin.
113
What does the copper reduction test detect?
It non-specifically detects the presence of a reducing sugar (which includes glucose, galactose and fructose)
114
What does fructokinase deficiency cause?
Essential fructosuria which is a benign autosomal recessive condition where pts can't metabolize fructose.
115
What does aldolase B deficiency cause?
Causes hereditary fructose intolerance which is a life-threatening disorder due to inability to metabolize fructose-1-P. It presents w/ hypoglycemia and vomiting after fructose ingestion as well as failure to thrive, liver and renal failure. Pts also have hypophosphatemia and hypermagenesemia.
116
What does galactose-1-P uridyl transferase deficiency cause and how does it present?
Causes galactosemia and presents w/ neonatal jaundice, vomiting, cataract formation, hepatomegaly and failure to thrive.
117
What is the most important defense against superficial candidiasis? And disseminated candidiasis?
T lymphs are most important defense against superficial. Neutrophils are most important defense against disseminated (why neutropenic pts are at risk).
118
What are the characteristics of atypical depression?
Mood reactivity, leaden paralysis (arms and legs feel extremely heavy), rejection sensitivity and increased sleep and appetite.
119
What are some possible triggers for Prinzmetal (vasospastic) angina)?
Cigarette smoking, cocaine/amphetamines, dihydroergotamine/triptans
120
How can Crohn's disease cause a coagulopathy?
Because it can lead to inflammation of the terminal ileum leading to bile acid malabsorption which in turn leads to fat malabsorption. Decreased fat absorption can cause decreased fat soluble vitamin intake including Vit K which is an important cofactor for carboxylation of many of the coagulation factors.
121
Defects in type I interferon release creates susceptibility to what?
Viral infections.
122
What type of gating does the CTFT channel have?
It is ATP gated
123
What is the drug of choice to tx trigeminal neuralgia?
Carbamazepine is first line. Second line agents include baclofen and valproic acid.
124
How do oral contraceptives decrease hirsutism in PCOS?
They decrease LH release from the anterior pituitary and thus decrease ovarian androgen production. They also increase sex-hormone binding globulin synthesis in the liver which will decrease free testosterone.
125
Where is airway resistance highest in the bronchial tree?
In the medium sized bronchi. Small diameter airways (toward the end of bronchial tree) contribute very little to total airway resistance.
126
What is the function of the polyA tail on mRNA?
It prevents the mRNA from being degraded when it exits the nucleus.
127
Splicesomes remove introns that contain _ _ at the 5' splice site and _ _ at the 3' splice site
GU at 5'
AG at 3'
128
What causes the majority of overdose deaths in the USA?
Opioid overdose.
129
Where in the thymus does the process of positive selection occur?
In the cortex. This is when T cells expressing TCRs capable of binding self-MHC on cortical epithelial cells survive.
130
Where in the thymus does the process of negative selection occur?
In the thymic medulla. T cells expressing TCRs with high affnity for self antigens undergo apoptosis. Recall that the AIRE gene is what causes expression of tissue-restricted self-antigens for this process.
131
How does cromyln work?
It inhibits mast cell degranulation.
132
Why must a nitrate free interval be provided to patients who are taking daily long acting nitrates?
Its necessary to prevent the development of tolerance as pts who take nitrates around the clock rapidly develop tolerance.
133
Studies with a larger sample size have a ______ level of power (B)
greater
134
Describe Berkson's bias
It is selection bias that can result from selecting hospitalized pts as the control group in a study.
135
True or false, bed rails and physical restraints have been shown to cause a decreased fall risk in nursing home facilities?
False!
136
When is anovulation part of normal physiology and what is the consequence?
It is normal in adolescence during the few years after menarche, as well as a few years before menopause. The result is menstrual cycle variability that can lead to spotting or heavy bleeding when menstruation does occur.
137
How are the ECG findings different for when the AV node is generating the electrical impulses (i.e. complete heart block) and when the purkinje system is generating the electrical impulses?
AV node --> narrow QRS complexes because ventricular depolarization proceeds normally. Also intrinsic rate of about 45-55bpm.
Purkinje system --> prolonged, abnormally shaped QRS complexes b/c conduction thru ventricles is abnormal. HR is roughly 20bpm.
138
Vagal stimulation w/ either carotid massage or valsalva maneuver can be used to treat what?
paroxysmal supraventricular tachycardia. If these fail, adenosine is administered.
139
How does activation of phospholipase C lead to increased intracellular Ca++?
PLC leads to IP3 and DAG and IP3 stimulates release of Ca++ from the endoplasmic reticulum.
140
What is the most common form of symptomatic cryptococcus infection?
Meningoencephalitis
141
What is the mechanism of action of stimulants like methylphenidate and amphetamines?
They increase the release of dopamine and norepi and block reuptake of these at synapses in the prefrontal cortex.
142
What are the broad-spectrum anticonvulsants (best for generalized type seizures)?
Lamotrigene, levitiracetam, topiramate and valproic acid
143
What are the narrow spectrum anti-convulsants (more favored for focal-onset seizures)?
Carbamazepine, phenytoin, gabapentin and phenobarbital.
144
Adverse effects of niacin include....
Flushing, hyperglycemia, hepatotoxicity and decreased renal excretion of uric acid (can cause gout flares).
145
Why can long term use of PPIs (i.e. omeprazole) lead to increased risk for osteoporosis?
Because insoluble Ca (i.e. calcium carbonate) needs an acidic environment in order to be absorbed and PPIs decrease stomach acidity.
146
Describe the screening and diagnostic algorithm for HIV (per Rx)?
Screen w/ ELISA, confirm + w/ Western blot, quantify viral load and CD4+ count, then you can begin therapy.
147
How does Fanconi anemia present?
Aplasic anemia causing pancytopenia, short stature, radial/thumb defects, cafe-au-lait spots, increased incidence of tumors and leukemia (it is a DNA repair defect that causes this).
148
What are pts w/ acondroplasia unable to do (leading to their physical defects)?
Affected individuals are unable to undergo endochondral ossification (means that they can't convert mesoderm into the cartilagenous model), particularly in the long bones of the limbs.
149
Where does iron absorption mainly occur and which form is absorbed better?
Absorbed in duodenum and upper jejunum and the ferrous (Fe++) is better absorbed than the ferric (Fe+++) form.
150
If 6 months of tx w/ oral contraceptives of hirsutism associated PCOS does not resolves sxs, what med can be added?
An anti-androgen like spironolactone.
151
What are alpha 2 receptors coupled to?
Gi
152
What are D1 and D2 receptors coupled to?
Gs and Gi respectively
153
What are H1 and H2 receptors coupled to?
Gq and Gs respectively
154
What are V1 and V2 receptors coupled to?
Gq and Gs respectively
155
What is unique about DNA polymerase I (in prokaryotes)
It is the only one of the 3 with 5' to 3' exonuclease activity (removes RNA primer and repairs damaged DNA). All three prokaryotic DNA polymerases have 3' to 5' exonuclease activity.
156
How do nitrites cause hypoxia?
The induce iron in hemoglobin to take the ferric (3+) state and this forms methemoglobin. Methemoglobin can't bind O2 and any remaining iron in the hemoglobin molecule in the ferrous state is left shifted so there is poorer delivery of O2 to tissues.
157
What do cytoplasmic P bodies do?
Play an important role in mRNA translation regulation and mRNA degradation.
158
Where does Ca++ released from the SR bind to cause muscle contraction? How does this occur?
Ca++ binds to troponin C which will cause displacement of tropomyosin. This will expose the myosin binding sites on actin.
159
What is colchicine used for?
Acute and chronic gout tx. It disrupts MTs and prevents neut inflammatory response.
160
What is leucovorin used for?
Can help prevent the myelosupression that can occur w/ methotrexate tx. Also used to enhance the effects of 5-FU.
161
Which part of LPS leads to septic shock?
Lipid A (it activates macrophages and granulocytes)
162
Which of the COX enzymes is inducible?
COX1 is constituitive whereas COX2 is inducible. It gets upregulated in inflammed tissues by cytokines like IL-1 and TNF-alpha.
163
What enzyme activates acylcovir? As such, for what viruses it it most effective?
Thymidine kinase so most effective against HSV and VZV. Viruses like CMV and EBV have a different thymidine kinase that can't activate the drug as easily so it's not as effective.
164
Lecithinase is the major virulence factor of what organism?
C. perfringens
165
What is enthesitis?
pain, tenderness and swelling at the sites of tendon insertion into bone. Pts w/ AS can get it.
166
What is the best may to monitor ankylosing spondylitis?
By monitoring the degree of chest wall expansion as disease progression can lead to thoracic spine involvement and enthesitis of the costovertebral and costosternal junctions that can restrict chest wall movement.
167
Is it ethical to accept gifts of significant monetary value?
Nope!
168
What is cutis aplasia? Name a condition where it is seen?
It is a focal skin defect of the scalp. It can be seen in Patau syndrome.
169
Why is the chloride content in RBC higher for venous blood vs. arterial blood?
Because Cl enters the cell in exchange for the increased of HCO3- forming in erythrocytes and and leaving the cell to be carried in the plasma of venous blood. This is done to maintain electrical neutrality.
170
Why is TSH the better test for making the initial dx of primary hypothyroidism?
B/c TSH levels will rise before the T4 levels fall so TSH is the more sensitive way to detect this disease.
171
How does rifampin work?
It inhibits bacteria's DNA dependent RNA polymerase.
172
How is flow of blood related to radius of vessel?
Flow is proportional to the radius ^4
173
What are the earliest lesions in atherosclerosis?
Intimal streaks.
174
Name 3 RF for molar pregnancy
extremes of maternal age, prior molar pregnancy, prior miscarriage.
175
Which form of trophoblastic disease has focally hyperplastic trophoblastic tissue?
Partial molar pregnancy. In stuff like complete molar pregnancy and invasive moles the tissue is diffusely hyperplastic.
176
Describe the extrinsic pathway of apoptosis
FAS ligand binds to cell --> this causes the FAS receptor to trimerize --> this allows their death domains to form a binding site for FADD --> receptor bound FADD stimulates the activation of initiator caspases (8 & 10) --> caspases 8 and 10 activate executioner caspases (3 &6) --> they initiate the terminal processes of apoptosis.
177
What are the terminal processes of apoptosis?
Cleavage of DNA, fragmentation of the nucleus, organelle autodigestion and plasma membrane blebbing.
178
What sort of drug is anastrozole?
An aromatase inhibitor.
179
What sort of drugs are goserelin, nafarelin, and histrelin?
They are GnRH agonists. Recall that leuprolide is also in this category!
180
What sort of drug is flutamide? What is it used for?
It is an anti-androgen and is used to treat prostate cancer.
181
What is first line treatment for acute status epilepticus?
IV benzo.
182
How does gabapentim work and why is this mechanism useful for treating seizures?
It blocks voltage gated Ca++ channels and this prevents the release of excitatory NTs, hence the tx benefit for seizures. It is attenuating the release of excitatory NTs.
183
How does phenytoin work?
It blocks pre-synaptic voltage gated Na+ channels.
184
What are some differences between drug induced lupus and regular SLE?
Drug induced form typically lacks the malar rash and is rarely associated w/ renal or neurological involvement. It also characteristically has auto-histone antibodies.
185
Drug induced lupus has been linked to what form of drug metabolism?
Drugs that are metabolized by phase II N-acetylation (isoniazid, procainamide, and hydralazine). --> slow acetylators are at greater risk.
186
How do you prevent maternal transmission of GBS for women how screen positive for it at 35-37 weeks gestation?
Intrapartum penicillin.
187
What sort of inheritance does androgenic alopecia (male-pattern baldness) demonstrate?
Polygenic inheritance w/ variable expressivity.
188
What are chromogranin A and synaptophysin markers for?
Neuroendocrine tumors.
189
What is vimentin and what is it used for?
It is an intermediate filament in mesenchymal tissue and it is used as a marker for detection of sarcomas.
190
Name 3 meds that can treat C. diff?
Metronidazole, vancomycin and fidaxomicin
191
What is the mechanism of action of fidaxomicin?
It is a macrocyclic antibiotic (related to macrolides) that inhibits the sigma subunit of RNA polymerase.
192
What does the prostate do?
It secretes an alkaline fluid containing proteolytic enzymes and prostate-specific antigen that is a component of semen. The pH of the fluid helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm.
193
Observing tactile fremitis on lung exam should make you think...
lung consolidation!
194
What does apoliporotein CII do?
It is tantamount to the function of lipoprotein lipase activation and deficiency causes hypertriglyceridemia.
195
What does apolipoprotein AII do?
It is the structural lipoprotein for HDL.
196
What age range do medulloblastomas preferentially affect?
Children in the first decade of life
197
Which brain tumor characteristically demonstrates pseudopalisading necrosis?
Glioblastoma multiforme.
198
What is the classic histological finding of a granulosa cell tumor of the ovary?
Call-Exner bodies, which are follicles with granulosa cells haphazardly arranged around a space containing eosinophilic secretions.
199
What receptor is "defective" in nephrogenic DI?
The V2 receptor.
200
How does Friedreich ataxia present?
Staggering gait, frequent falling, an abnormally high arch (known as pes cavus), muscle weakness and loss of DTRs, hammer toes, DM and hypertrophic cardiomyopathy.
201
What is the trinucleotide repeat in Friedreich ataxia? How does that produce disease?
GAA is the repeat. It leads to transcriptional silencing of the affected gene as the numerous repeats cause it to be like heterochromatin.
202
What is the trinucleotide repeat in Huntington's disease?
CAG
203
What is the trinucleotide repeat in fragile X?
CGG
204
What is the trinucleotide repeat in myotonic dystrophy?
CTG
205
Symphilis screening tests for antibodies that bind cardiolipin. Where is cardiolipin normally found?
On the inner mitochondrial membrane
206
Goodpasture syndrome is caused by autoantibodies to what?
Type IV collagen.
207
How does congenital hypothyroidism present?
Puffy face, developmental delay, coarse facies, hypokinesia, protruding tongue, and an umbilical hernia.
Findings can also include lethargy, hoarse cry, feeding problems, constipation, hypotonia, dry skin, hypothermia, and prolonged jaundice
208
Which familial breast cancer gene confers the greatest risk for ovarian cancer?
BRCA1
209
What is attrition bias? What form of bias is it?
Attrition bias is where the is disproportionate loss of subjects in the exposed and unexposed study groups. It is a form of selection bias.
210
Where are enhancer sequences located in eukaryotic genes?
The can be located upstream, downstream or in introns of the gene. They bind activators which bend DNA such that activators can interact w/ polymerase and TFs at the promoter.
211
What is the etiology of stress incontinence?
Decreased urethral sphincter tone or urethral hypermobility.
212
In what psychological condition do you see parotid gland enlargement?
Bulimia nervosa
213
What transmits Chikungunya?
The Aedes mosquito
214
How does Dengue classically present?
Acute febrile illness w/ fever, headache, retro-orbital pain, and joint and muscle pain. Can also include hemorrhage, (petichiae, purpura, etc.), thrombocytopenia and leukopenia.
215
What is one protocol to help prevent operation on the incorrect site?
Have at least 2 health care workers verify the site independently. Done independently b/c verifying together can lead to a replication error.
216
Later onset absence seizures is associated w/ an increased incidence of what?
Generalized tonic clonic or myoclonic seizures. If these occur you need to tx w/ a broad-spectrum anti-epileptic (can't just give ethosuximide).
217
What are the effects of inhaled anesthetics generally on the follows systems? CV, pulm, brain, kidneys, and liver?
- CV: decrease CO, hypotension and increased atrial and ventricular pressures
- Pulm: resp depression --> decreased TV and minute ventilation leading to hypercapnia.
- Brain: fluoronated ones increase cerebral blood flow
- Kidneys: decreased GFR and renal plasma flow
- Liver: decreased blood flow
218
What is the best way to assess severity of mitral stenosis on auscultation?
Time from A2 to the opening snap. Shorter = higher pressures and thus more severe.
219
How does hepatic encephalopathy disrupt excitatory neurotransmission in the brain?
Astrocytes normally take up extra glutamate from synapses, combine it w/ NH3 and transfer it back to neurons as glutamine so they can make more glutamate for future neurotransmission.
In hepatic encephalopathy there is excess NH3 so there is excess conversion to glutamine in the astrocytes. This causes them to swell and prevents them from transfering glutamine to the neurons. Neurons thus lack glutamine to convert to glutamate and this disrupts excitatory neurotransmission.
220
How does pyruvate kinase deficiency cause hemolysis and splenic red pulp hyperplasia?
Causes erythrocytes to have insufficient ATP production and so electrolyte gradient is disrupted, H20 and K+ loss occurs and there is hemolysis.
Splenic red pulp cells are involved in the removal of damaged RBCs so due to increased RBC damaged with this disorder, there is red pulp hyperplasia in response.
221
How can you grow C. diphtheriae?
Can be cultured in Loffler's media or can be grown on cysteine-tellurite agar (grows black colonies).
222
What is Bordet-Gengou medium used to grow?
Pertussis
223
Why can linezolid cause seratonin syndrome?
Because it has MAOI activity.
224
What enzyme activates trypsinogen?
Enteropepsidase
225
What binds to and thus regulates the K+ channels in pancreatic beta cells whose closure causes depolarization and insulin release?
ATP. This is b/c more glucose in the cells (enters thru GLUT-2) causes more ATP.
226
How is the dx of strongyloides made?
By seeing rhabditiform larvae in the stool.
227
Why can GI bleeding precipitate hepatic encephalopathy?
B/c GI bleeding represents increased delivery of nitrogen to the gut in the form of hemoglobin, which will be converted to ammonia and absorbed into the bloodstream.
228
Describe how osteoclasts originate from precursor cells
The come from the mononuclear phagocytic cell lineage and form when several precursor cells merge to form a multi-nucleated mature cell. M-CSF and RANK-L are important differentiation factors.
229
What is osteoprotegerin?
It is a decoy receptor for RANK-L that decreases osteoclast differentiation and survival and thus promotes increased bone density.
230
What is transference?
Unconscious shifting of emotions or desires associated with a person from the past to another person in the present.
231
What is projection (coping mechanism)?
It is where a person mis-attributes their own unacceptable feelings to another person.
232
What does damage to the hippocampus cause?
Anterograde amnesia.
233
What is the inciting pathogenesis in acute pancreatitis?
Toxic or ischemic injury to the acinar cells that leads to premature activating of trypsin inside the pancreatic acini.
234
What is the mechanism of action of valproic acid?
It blocks voltage gated Na++ channels and causes a rise in GABA concentration.
235
What is the mechanism of action of levetiracetam?
It binds to a synaptic vesicle protein (SV2A) to modulate the release of GABA and glutamate neurotransmitters.
236
How does Zileuton work?
It inhibits the formation of leukotrienes by blocking the 5-lipoxygenase enzyme.
237
What characterizes MEN1? What gene mutations is associated with it?
Pituitary tumors, pancreatic endocrine tumors, and parathyroid adenomas. Associated w/ MEN1 mutation
238
What characterizes MEN2A? What gene mutations is associated with it?
Parathyroid hyperplasia, medullary thyroid carcinoma, and pheochromocytoma. Associated w/ RET mutation.
239
What characterizes MEN2B? What gene mutations is associated with it?
Medullary thyroid cancer, pheochromocytoma and mucosal neuromas. Associated w/ RET mutation and marfanoid habitus.
240
Why are B-blockers useful for treatment of hyperthyroidism?
They counteract adrenergic effects (i.e. tachycardia) of hyperthyroidism, but lipid soluble ones also inhibit 5' deiodinase thus preventing peripheral conversion of T4 to T3.
241
What is the mechanism of action of PCP?
It works primarily as an NMDA antagonist. Secondarily it works to inhibit the re-uptake of dopamine, serotonin and norepi.
242
What accumulates in the lysosomes in Dubin-Johnsons syndrome?
Epinephrine metabolites. This is what gives the liver its grossly black appearance.
243
Some meds can cause IgE independent mast cell degranulation by activating protein kinase A and PI3 kinase. What are 3 examples of meds known to do this?
Opioids, radiocontrast agents, and some antibiotics (e.g. vancomycin).
244
What is the pathogenesis of Malloy-Weiss tears?
Lots of vomiting and retching that cause rapid increase in intrabdominal and intraluminal gastric pressure. This causes the tearing.
245
What is the auscultatory finding of a VSD?
Holosystolic murmur heard at the L upper sternal border. This is due to the turbulent flow of blood flowing from the L to R ventricle. As such, in pts w/ really big VSDs, a murmur might now be heard b/c flow is less turbulent and there is less of a transeptal gradient.
246
What sort of antagonist in phenoxybenzamine?
It is an irreversible a1 a2 antagonist.
247
What is another name for the "wet mount" that is used to dx trichamoniasis vaginalis?
saline microscopy
248
Which other lipid lowering agent most greatly increases the risk of statin-induced myopathy when given in combo with statins?
Fibrates like genfibrozil.
249
Which immune cell is responsible for the destruction of cells w/ decreased or absent MHC class I on its surface?
NK cells. This allows them to kill virus infected and tumor cells (as these are the ones that down-regulate MHC I).
250
Why can hypocapnia and hyperventilation (i.e. panic attack) cause neurologic sxs?
Because decreased CO2 can lead to cerebral vasoconstriction and this lack of perfusion can lead to neuro sxs.
