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USMLE Step 1 > High Yields Week 2 > Flashcards

High Yields Week 2 Flashcards

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USMLE® Step 1 flashcards
1
Q

Epithelial ovarian cancer is the most common type of ovarian neoplasm (serous and mucinous cystadenoma) What is the serum biomarker associated with epithelial ovarian cancers?

A

CA-125

not suitable for screening but good for measuring progress

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2
Q

Aflatoxins, toxins produced by Aspergillus flavus, are associated with peanuts and grain crops. What is a major adverse outcome of ingestion of high levels of aflatoxin?

A

Increased risk of developing hepatocellular carcinoma

via p53 mutation

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3
Q

What are characteristics of borderline personality disorder?

A

Pervasive pattern of unstable and intense relationships
Unstable mood
Impulsivity
Splitting (categorizing people good or bad)
Recurrent suicidal behavior or self-mutilation
Feelings of emptiness

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4
Q

A 25 yo female presents with telangiectasias on her face, arms, lips, and oral mucosa. She also reports frequent epistaxis (nosebleed) and blood in her stool. Disease/Dx?

A

Osler-Weber-Rendu syndrome (hereditary hemorrhagic telangiectasia)

Autosomal dominant

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5
Q

What area the most common causes of neonatal meningitis (0-3 months of age) in the US?

A
  1. Group B Strep
  2. E. Coli
  3. Listeria
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6
Q

What role do bacterial pili (fimbriae) typically play in bacterial virulence?

A

Pili (fimbriae) are important for bacterial attachment to epithelial surfaces; such as nasopharynx or uroepithelium

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7
Q

Bioavailability is defined as the fraction of administered drug that reaches the systemic circulation in a chemically unchanged form. What effect does the first pass effect have on bioavailability?

A

The first pass effect typically describes oral drugs that are absorbed in the GI tract which then must enter the hepatic portal circulation, exposing the drug to liver metabolism, before the drug can get to systemic circulation

Drugs that are metabolized extensively by the liver (high first pass metabolism) will have a low bioavailability because a low fraction of the drug will make it to systemic circulation unchanged

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8
Q

What is the mechanism of action of thiazolidinediones (TZDs) for use in diabetic patients?

A

TZDs decrease the serum glucose in diabetics by DECREASING INSULIN RESISTANCE

TZDs activate PPAR-y, a nuclear receptor that alters the transcription of genes involved in glucose and lipid metabolism (upregulating them)

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9
Q

What is renal papillary necrosis and what is it associated with?

A

Ischemic injury to renal pyramids causing necrosis of renal papillae leading to gross hematuria

Associated with decreased renal perfusion due to:

  • Sickle cell disease/trait
  • Acute pyelonephritis
  • Analgesics (NSAIDs)
  • Diabetes mellitus

SAAD papa with papillary necrosis (mneumonic)

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10
Q

What are the most common organisms that cause bacteriemia (septic shock) in sickle cell patients?

A

Strep pneumoniae and Hemophilus influenza

Sickle cell patients eventually become asplenic, increasing their risk of infection with ENCAPSULATED organisms

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11
Q

What is the pathophysiology of hereditary hemochromatosis?

A
  • Excessive intestinal iron absorption* and organ damage due to iron accumulation within parenchymal tissues
  • cirrhosis, diabetes mellitus, cardiomyopathy, arthropathy

Most commonly caused by a missense mutation in the HFE gene

Autosomal recessive

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12
Q

What is the typical karyotype of a complete molar pregnancy and what are diagnostic findings?

A

46, XX (one sperm, no ovum)

↑↑↑ B-hCG
NO fetus
Snowstorm appearance on ultrasound
Heavy vaginal bleeding and pelvic pain

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13
Q

What is a typical karyotype of an incomplete molar pregnancy?

A

69, XXX or 69, XXY

Will contain fetal tissue

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14
Q

Pt presents with tall, thin habitus with elongated limbs, dislocated lens in eye and developmental delay. Disease/Dx?

A

Homocystinuria (autosomal recessive)

Deficiency of cystathionine synthase deficiency
-responds well to treatment with pyridoxine (VitB6)

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15
Q

What are first line therapies for bipolar disorder?

A

Lithium

Valproate (the anticonvulsant)

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16
Q

Where do the posterior cruciate ligament and anterior cruciate ligament attach on the posterior side of the knee joint?

A

PCL - attaches to MEDIAL condyle of femur

ACL - attaches to LATERAL condyle of femur

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17
Q

In addition to increasing the absorption of water in the renal medullary collecting duct, vasopressin/ADH action on the renal V2 receptors also causes increased reabsorption of what other substance?

A

Urea

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18
Q

Patient presents with a 2 month history of difficulty hearing. The patient has recently found it more difficult to tolerate everyday sounds which now cause him ear pain. Injury to what nerve can cause this problem?

A

Facial nerve (CN VII)

This patient has hyperacusis (increased sensitivity to sound) caused by a deinnervated stapedius muscle

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19
Q

What nerve root does the achilles reflex test?

A

S1

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20
Q

What nerve root does the patella reflex test?

A

L4

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21
Q

What nerve root does the triceps reflex test?

A

C7

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22
Q

What nerve root does the biceps reflex test?

A

C5

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23
Q

What enzyme deficiency and subsequent amino acids accumulate in Maple Syrup Urine Disease?

A

MSUD results from defective a-keto acid dehydrogenase which leads to an inability to break down branched chain amino acids, which are:

Isoleucine
Leucine
Valine

“I Love Vermont maple syrup”

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24
Q

What metabolic pathway does ethanol inhibit?

A

Gluconeogenesis

Metabolism of ethanol reduces NAD+ to NADH, taking away NAD+ that is used to power gluconeogenesis

Seen in alcoholics on extended binges (18+ hrs) with little dietary intake

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25
Q

What is the pathogenesis of Type 1 diabetes mellitus?

A

Type 1 diabetes is caused by an autoimmune response against pancreatic beta cells

Manifestations of the disease occur once > 90% of pancreas beta cells have been destroyed (by self leukocytes)

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26
Q

Describe how nitric oxide (NO) causes vascular smooth muscle relaxation (vasodilation)

A

NO activates guanylate cyclase → ↑ cGMP

↑ cGMP → ↓ intracellular Ca2+ causing decreased activity of myosin light chain kinase

↑ cGMP → myosin light chain dephosphorylation

End result is vascular smooth muscle relaxation

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27
Q

Adenomatous polyps found on colonoscopy can signify a cancerous process occurring in the colon. Transition from adenoma to carcinoma follows a particular sequence in colorectal cancer. What is the first mutation in this pathway?

A

APC tumor suppressor gene

(found in most sporadic and ALL familial adenomatous polyposis patents)

Typical order from first to last:
APC → KRAS → DCC → p53

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28
Q

Describe the role of eosinophils in host defense during parasitic infection.

A

Eosinophils bind to the Fc receptor on IgG and IgE antibodies which have bound to the parasite

Binding antibodies stimulates eosinophils to destroy the parasite via antibody-dependent cell-mediated cytotoxicity with enzymes released from their cytoplasmic granules

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29
Q

Clear cell renal cell carcinoma (the most common type of kidney tumor) originate from which part of the kidney?

A

Epithelial cells of the proximal renal tubules

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30
Q

What are two ways to calculate cardiac output?

A

CO = Stroke Volume x Heart Rate

CO = O2 consumption / arteriovenous O2 difference

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31
Q

What do bone deformities, hepatosplenomegaly, and the presence of erythroid precursors in the spleen and liver signify?

A

Extramedullary hematopoiesis (RBC production outside the bones as well as bone deformities in the skull)

This is typically caused by severe chronic hemolytic anemias (due to blood loss)

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32
Q

A 6 month old girl is brought to the ER after recent onset of vomiting, irritability and jaundice. The mother had recently begun feeding the baby solid foods such as fruits and cereal. Disease/Dx?

A

Hereditary fructose intolerance

Results from an Aldolase B deficiency, an enzyme involved in fructose metabolism

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33
Q

What paraneoplastic syndrome is associated with small cell lung cancer?

A

SIADH

Small cell lung cancer is a tumor of neuroendocrine origin and *secretes ADH *

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34
Q

What nerve provides motor innervation to both the muscles of mastication and the tensor tympani in the middle ear?

A

Mandibular division of the trigeminal nerve (CN V)

Damage to this nerve can cause both jaw pain and otologic (ear) problems

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35
Q

What complication of cardiac output can result from a tension pneumothorax?

A

Hypotension

As pressure increases in the pleural space following a tension pneumo, the lungs and mediastinal structures deviate to the opposite side and the increased chest cavity pressure ↓ systemic venous return to the heart causing ↓ preload and thus ↓ CO

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36
Q

What immunologic process causes abscess formation?

A

Lysosomal enzyme release from neutrophils and macrophages

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37
Q

Is Streptococcus pyogenes pyrrolidonyl arylamidase positive or negative?

A

Pyrrolidonyl arylamidase POSITIVE

This helps differentiate Group A Strep (pyogenes) from Group B Strep as bacitracin tests are apparently not specific

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38
Q

Allopurinol, a xanthine oxidase inhibitor used to treat gout, increases the activity of what drug?

A

Azathioprine (immunosuppressive drug used in organ transplantation and autoimmune diseases)

Inhibition of xanthine oxidase results in increased conversion of azathioprine to its active metabolite

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39
Q

What are adverse effects associated with fibrates (Gemfibrozil)?

A

Cholesterol gallstones (caution when prescribing to patients with underlying gallbladder disease)

Myopathy (↑ risk when used with statins)

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40
Q

What effect does prevalence have on positive/negative predictive values?

A

PPV increases as the disease prevalence increases

NPV increases at the disease prevalence decreases

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41
Q

What is a common metabolic adverse effect associated with use of highly-active antiretroviral therapy for HIV?

A

Redistribution of fat

Typically results in loss of fat from the face and extremities (lipoatrophy) with redistribution to the trunk (central fat deposition)

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42
Q

Sarcoidosis and Tuberculosis can present clinically similar. Distinction can be made on biopsy by which type of granuloma associated with each disease?

A

Sarcoidosis → non-caseating granulomas

Tuberculosis → caseating granulomas (and acid fast bacilli)

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43
Q

What effect does inspiration have on systemic venous return?

A

Increases venous return, increasing blood volume in the heart → ↑ preload

(during inspiration, intrathoracic pressure drops)

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44
Q

What is the vector and geographic distribution for Babesia microti which causes babesiosis?

A

Spread by Ixodes tick in the Northeast United States

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45
Q

What anticoagulant therapy is considered safe to use in pregnancy to protect against the pregnancy-derived increased risk in venous thrombosis?

A

Low-molecular-weight heparins (Enoxaparin)

Warfarin is contraindicated in pregnancy (teratogenic)

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46
Q

Where inside the cell are ribosomes (non-coding RNA molcules / rRNA) synthesized and assembled?

A

nucleolus

dense round structure within the nucleus

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47
Q

What are basic pharmacologic targets in the treatment of asthma?

A

B2 adrenergic agonist - bronchodilation

M3 cholinergic antagonist - bronchodilation

Leuktotriene D4 antagonist - bronchodilation and anti-inflammatory

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48
Q

What are typical presentations of infection with Bartonella henselae

A

Cat scratch fever - fever + axillary lymphadenopathy

Bacillary angiomatosis - red-purple papular skin lesions; occurs in immunosuppressed

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49
Q

When prescribing linezolid for MRSA or VRE, what drug-drug interaction needs to be taken into consideration?

A

Patients with SSRIs, SNRIs, or tricyclic antidepressants

Linezolid can cause SEROTONIN SYNDROME in patients on serotonergic medication

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50
Q

How do CD8+ (cytotoxic T cells) kill infected/foreign antigen cells?

A

CD8+ CTLs kill cells by inducing apoptosis in those cells

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51
Q

What complications can arise from giving patients with Selective IgA deficiency a blood transfusion?

A

These patients can go into fatal anaphylactic shock

Patients with selective IgA deficiency often form IgG antibodies against IgA (since they never had any IgA)
→ when given a blood transfusion that contains IgA from the donor blood, the anti-IgA IgG causes an anaphylactic response

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52
Q

A 45 yo woman presents with progressively worsening retrostrenal chest pain, dysphagia and odynophagia. Esophageal scope shows linear and shallow ulcerations in the lower esophagus. The patient underwent kidney transplantation 5 months ago. What is likely causing this presentation?

A

Cytomegalovirus (CMV) esophagitis

CMV can be transmitted to transplant recipients from the donor organ causing pneumonia or esophagitis

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53
Q

In gas anesthetics, what does it mean for a drug to have a high blood/gas partition coefficient?

A

high blood/gas partition coefficient means the drug is more soluble in the blood

Since the blood is more soluble in blood, it will take longer for its partial pressure to build in the blood resulting in slower diffusion into the brain

TLDR - ↑ blood/gas coefficient → longer onset of action time

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54
Q

What is migratory thrombophlebitis (transient episodes of hypercoagulability) causing migratory redness and pain in the extremities associated with?

A

Pancreatic adenomacarcinoma (and other adenocarcinomas of the colon or lung)

AKA - Trousseau syndrome

Paraneoplastic syndrom of hypercoagulability

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55
Q

A newborn is delivered via induced vaginal delivery for fetal growth retardation. The infant has clenched hands with overlapping fingers, rocker bottom feet and a holosystolic murmur. What is the most likely chromosomal abnormality?

A

47, XX, +18

Edwards syndrome (Trisomy 18)

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56
Q

What cardiac complication is associated with syphilis (Treponema Pallidum infection)?

A

Ascending aortic aneurysm (which can cause aortic regurgitation by stretching out the aortic valve)

Results from infection and destruction of the vasa vasorum that supplies the aortic vascular tissue with blood → ischemic damage weakens the aortic adventitia

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57
Q

Is aspiration pneumonia with subsequent abscess formation (typically in the right lower lobe) more likely to be caused by oropharyngeal or stomach contents?

A

Oropharyngeal contents (anaerobic bacteria from mouth)

Aspiration of stomach contents is more likely to cause pneumonitis due to inhalation of gastric acid (not bacterial)

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58
Q

Describe the psychology concept of transference.

A

Transference is the unconscious shifting of emotions or desires associated with a person from the past to another person in the present

(like maybe someone with daddy problems)

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59
Q

What medication can be used to prevent hematuria (hemorrhagic cystitis) caused by some chemotherapy agents (like cyclophosphamide)?

A

Mesna

Mesna is a sulfhydryl compound that binds and inactivates the toxic metabolites of the chemotherapeutic agents in the urine

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60
Q

What effect does ischemic damage to the myocardium from a myocardial infarction have on cardiac output?

A

Decreases cardiac output due to a decrease in heart contractility

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61
Q

What genetic mutation causes Marfan syndrome?

A

Fibrillin-1 mutations (autosomal dominant)

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62
Q

What artery supplies most of the pubic organs (bladder, uterus, etc.)?

A

Internal pudendal

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63
Q

Essential fructosuria is a benign disorder of sugar metabolism in which patients are asymptomatic except for high fructose in the urine. What is the enzyme deficiency in essential fructosuria?

A

Fructokinase deficiency

Not as serious as hereditary fructose intolerance (Aldose B deficiency) because hexokinase can be used to metabolize fructose in essential fructosuria

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64
Q

What is the mechanism of action of phencyclidine (PCP)?

A

NMDA receptor antagonist

Causes agitation, hallucinations, violent behavior and vertical nystagmus at high doses

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65
Q

What class of drugs are used to treat hyperthyroidism and what is their mechanism of action?

A

Thionamides (methimazole and propylthiouracil)

These drugs decrease thyroid hormone synthesis via inhibition of thyroid peroxidase (in the colloid) causing:

  • ↓ iodine organification
  • ↓ coupling of iodotyrosines
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66
Q

What is a Dandy-Walker malformation and how does it present clinically?

A

Absence of cerebellar vermis with cystic enlargement of 4th ventricle

Typically presents in infancy as a child with poor coordination and unsteadiness (child may also have a large head)

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67
Q

Serum markers can be useful for monitoring cancer recurrence and response to therapy. What cancers do high a-fetoprotein levels associate with?

A

Hepatocellular carcinoma
Yolk sac tumor (testicular/ovarian)
Mixed germ cell tumors

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68
Q

Antiretroviral drugs used for HIV therapy that bind to the HIV gp41 protein inhibit which viral process?

A

Inhibits HIV fusion with target cell membrane, blocking the virus from penetrating into CD4+ T cells (fusion inhibitors)

EnFUvirtide is a FUsion inhibitor that binds HIV gp41 envelope protein

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69
Q

Serum markers can be useful for monitoring cancer recurrence and response to therapy. What cancers do high CA 19-9 levels associate with?

A

Pancreatic adenocarcinoma

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70
Q

Serum markers can be useful for monitoring cancer recurrence and response to therapy. What cancers do high CA 125 levels associate with?

A

Ovarian cancer

71
Q

Serum markers can be useful for monitoring cancer recurrence and response to therapy. What cancers do high B-hCG levels associate with?

A

Choriocarcinoma (ovarian or testicular tumors of placental origin)

72
Q

Serum markers can be useful for monitoring cancer recurrence and response to therapy. What cancers do high carcinoembryonic antigen (CEA) levels associate with?

A

Colorectal and pancreatic cancers

73
Q

Describe the psychologic defense mechanism of reaction formation.

A

Responding to a scenario/person in a manner opposite to one’s actual feelings

74
Q

Which main coronary artery supplies blood to the AV node?

A

Posterior descending artery (which feeds the AV nodal artery)

75
Q

Which coronary artery supplies the posterior descending artery in right/left coronary dominance?

A

Right coronary dominance - Right coronary artery supplies PDA

Left coronary dominance - Left circumflex artery supplies PDA

76
Q

In asthmatics treated with inhaled glucocorticoids, what infectious agent may result in recurrent transient infiltrates, eosinophilia and eventual bronchiectasis?

A

Aspergillus fumigatus

Can cause allergic bronchopulmonary aspergillosis in asthmatics using inhaled glucocorticoids

77
Q

How does Neisseria meningitidis gain access to the CNS to cause meningitis?

A

Neisseria meningitidis is spread via respiratory droplets

Pharynx → blood → choroid plexus (BBB) → meninges

78
Q

Why does Hepatitis C infection usually result in development of chronic disease?

A

Antigenic variation in HCV envelope proteins caused by the lack of proof reading in its RNA-dependent RNA polymerase

The production of host antibodies lags behind that of new mutant HCV strains, preventing clearance of the virus

79
Q

What are the serum calcium, phosphorous and parathyroid hormone levels in a patient that has primary osteoporosis (not caused by a medical disorder)?

A

Normal

80
Q

A mother brings her son into clinic due to problems at school due to poor grades and inattentiveness in class. She says her son had some developmental delay growing up. On examination, the 16 y/o boy has a long, narrow face, prominent chin and forehead and large testicles. Disease/Dx?

A

Fragile X syndrome

X-linked disorder caused by loss of function mutation in FMR1 gene on the X chromosome

81
Q

What drug therapy is used in the treatment of Graves’ ophthalmopathy (“popping out eyes”)?

A

High-dose glucocorticoids (prednisone) → decrease inflammation

Graves’ ophthalmopathy is due to an inflammatory process and so conventional antithyroid drugs do not work

82
Q

What is a serious side effect of administering succinylcholine (depolarizing NMJ nicotinic ACh receptor blocker) to patients with burns, myopathies, crush injuries or denervation?

A

Severe hyperkalemia which can lead to fatal arrhythmias

Succinylcholine causes continuous stimulation of the NMJ end plate which causes nonselective cation channels to remain open, allowing potassium release

83
Q

What is the effect of a high concentration of fructose-2,6-bisphosphate within a cell?

A

Increased glycolysis (inhibitory of gluconeogenesis)

Fructose-2,6-bisphosphate activates phosphofructokinase-1, increasing glycolysis action

84
Q

Tetrahydrobiopterin (BH4) is a cofactor in reactions that produce what type of molecules?

A

Neurotransmitters

Serotonin (from tryptophan)
Tyrosine/DOPA - the precursors to dopamine, norepinephrine and epinephrine

85
Q

What are major adverse effects of theophylline (methyxanthine drug used in COPD/astham) toxicity?

A

Seizures and tachyarrhythmias

86
Q

Ketone body synthesis is an energy source the body resorts to in times of significant fasting (24+ hours). What macromolecule are ketone bodies derived from?

A

Fatty acids

Fatty acid breakdown can yield ketone bodies

87
Q

Why are serum sodium levels typically normal in cases of hyperaldosteronism (↑ aldosterone release from adrenal cortex)?

A

↑ reactive atrial natriuretic peptide (ANP) release

Increased intravascular volume from excess Na+ absorption causes an increase in release of ANP

88
Q

Why should antidepressants be used with caution in patients with a family history of bipolar disorder?

A

ALL antidepressants can induce mania in susceptible patients (esp. pts with unrecognized bipolar disorder)

89
Q

The most common cause of rotator cuff syndrome (shoulder pain) is diagnosed by the “empty can” test in which pain is elicited by putting downward pressure on a patient’s outstretched arm as they push up. What tendon injury does this test and diagnosis involve?

A

Tendon of the supraspinatus muscle

90
Q

What does scapular winging indicate?

A

Paralysis/injury of the serratus anterior muscle

innervated by the long thoracic nerve

91
Q

In attherosclerosis pathogenesis, following endothelial injury, what are the cellular components promoting the ultimate formation of atherosclerotic plaque?

A

LDL entry into the intima

Macrophage entry in the intima to phagocytose the LDL, resulting in foam cells

Platelet adhesion to injured endothelium causing release of platelet-derived growth factor which promotes smooth muscle cell migration into intima

92
Q

What is the mechanism of action of edema factor, a component of the anthrax exotoxin (of Bacillus anthracis)?

A

Edema factor is an adenylate cyclase that causes a massive increase in intracellular cAMP

↑↑↑ cAMP leads to neutrophil/macrophage dysfunction and tissue edema

93
Q

Blood vessels and nerves that supply the ovary travel through what anatomical structure?

A

Infundibulopelvic ligament

AKA suspensory ligament of the ovary

94
Q

What is the most severe complication and primary cause of death from acute rheumatic fever (following GAS pharyngitis)?

A

Severe pancarditis can result in heart failure and death

95
Q

A 40 y/o caucasian male presents with a 3 year history of abdominal discomfort, greasy stools, weight loss and joint pain. An intestinal biopsy shows multiple macrophages loaded with PAS-positive granules. Disease/Dx?

A

Whipple disease via Tropheryma whippelii infection

Typically presents with small intestine malabsorption and discomfort, joint and central nervous system involvement

96
Q

A patient presents with acute urethritis, conjunctivitis and joint pain following a resolved Chlamydia infection 3 weeks prior. Disease/Dx?

A

Reactive arthritis (Reiter syndrome)

Reactive arthritis is an HLA-B27 associated arthropathy and can eventually result in sacroiliitis in some cases

97
Q

What neurotransmitters are inhibited from releasing in tetanus (Clostridium tetani infection)?

A

Glycine and GABA (inhibitory neurotransmitters)

By blocking inhibitory neurotransmitters, tetanus causes a SPASTIC paralysis

98
Q

What are the primary adverse effects of aminoglycosides (gentamicin)?

A

Ototoxicity (hearing loss, tinnitus) and Nephrotoxicity

99
Q

What conditions predispose to gallstone formation in the gall bladder?

A

↑ cholesterol concentration

↓ bile salts and phosphatidylcholine (these form miceles around cholesterol, making it ‘soluble’ in water for excretion)

100
Q

A 20 y/o male presents with difficulty performing fine finger movements with his right hand after a climbing injury a day ago in which he reached quickly upwards with his right arm. Which nerve is likely injured?

A

Lower trunk of the brachial plexus (which includes both median and ulnar nerves)

The lower trunk of the brachial plexus carries nerve fibers from C8 and T1 spinal nerves which innervate all the intrinsic muscles of the hand (via median and ulnar nerves)

101
Q

What is the primary vector for infection with Schistosoma haematobium causing urinary schistosomiasis?

A

Freshwater snails (in Africa and Middle East)

Urinary schistosomiasis can result in hematuria, hydronephrosis and squamous cell carcinoma of the bladder

102
Q

What nucleus of the hypothalamus controls satiety/feeling full?

A

Ventromedial nucleus

A lesion in the ventromedial nucleus would result in hyperphagia (insatiable appetite)

103
Q

What must be known about the DNA gene of interest in order to successfully perform a PCR amplification of the DNA of interest?

A

Primers that are complementary to the regions of DNA flanking the segment of interest

The exact nucleotide sequence of the target DNA region does NOT need to be known

104
Q

What serum marker is used to distinguish between a benign leukemoid reaction and chronic myelogenous leukemia? Is this marker high or low for these conditions?

A

Leukocyte alkaline phosphatase (LAP)

LAP is elevated in a leukemoid reaction

LAP is low in chronic myelogenous leukemia

105
Q

What cellular process results in liquefactive necrosis and where does it typically occur?

A

Injured ischemic cells and neutrophils release lysosomal enzymes that digest the tissue; later, phagocytic cells migrate into the area of necrosis and remove the necrotic tissue leaving a cavity

Liquefactive necrosis occurs in:

  • CNS ischemic injury (brain infarcts)
  • bacterial abscesses
106
Q

What is the function of the serum protein haptoglobin?

A

Haptoglobin binds free hemoglobin and promotes its uptake by the reticuloendothelial system

Free hemoglobin may be found in the blood when a hemolytic process is occurring

107
Q

What serum markers indicate an intravascular hemolytic anemia may be occurring?

A

Increased indirect bilirubin (jaundice)
Increased lactate dehydrogenase
Decreased haptoglobin (lost by binding all the free heme)

108
Q

What is the drug class thiazolidinediones (TZDs) used for and what is its mechanism of action?

A

TZDs increase insulin sensitivity in Type 2 Diabetics (who have insulin resistance)

TZDs bind to PPAR-y receptors in the cell nucleus and increases gene expression of adiponectin, a cytokine that enhances insulin sensitivity

109
Q

How is half-life calculated via the volume of distribution (Vd) and clearance rate?

A

t1/2 = (0.7 x Vd) / CL

110
Q

What is the most serious complication of Hepatitis E infection?

A

High mortality rate in infected pregnant women

fulminant hepatitis in pregnant women

111
Q

What would be seen on light microscopy of affected myocardium within 4 hours of a myocardial infarction?

A

Normal myocardium (minimal change under 4 hrs)

112
Q

How do patients present clinically with colon adenocarcinoma on the ascending (right) colon vs. the descending (left) colon?

A

Ascending colorectal cancers BLEED

  • exophytic mass (growth into the lumen)
  • iron deficiency
  • anemia
  • weight loss

Descending colorectal cancers OBSTRUCT

  • infiltrating mass of intestinal wall
  • partial obstruction
  • colicky pain
  • hematochezia
113
Q

What drugs can be used to prevent tumor lysis syndrome in patients receiving chemotherapy to treat cancers with rapid cell turnover, substantial tumor burden or high sensitivity to chemotherapy?

A

Allopurinol - xanthine oxidase inhibitor that prevents uric acid formation

Rasburicase - urate oxidase analog that metabolizes uric acid into allantoin, a more soluble form of uric acid/purine waste

114
Q

What does overdose of the potent vasodilator nitroprusside cause?

A

Cyanide toxicity

Cyanide inhibits the electron transport chain, halting aerobic respiration within cells

115
Q

What is used for treatment of cyanide overdose/poisoning?

A

nitrite + thiosulfate; hydroxocobalamin

116
Q

Organophosphates used as pesticides in agriculture have what pharmacologic effect?

A

Cholinesterase inhibitors (inhibits breakdown of acetylcholine)

High dose exposure to organophosphates can cause cholinergic overstimulation

117
Q

What is placenta accreta and what complications can it cause?

A

A placenta that is morbidly adherent to the myometrium (direct attachment/invasion into the myometrium)

Placenta accreta can cause postpartum bleeding because the placenta does not detach from the uterus

118
Q

What is a common neoplastic syndrome of renal cell carcinoma?

A

Erythrocytosis and polycythemia (↑ RBCs)

Tumor cells may secrete erythropoietin (EPO)

119
Q

What drug is used to treat treatment-resistant schizophrenia?

A

Clozapine (2nd gen antipsychotic)

Treatment requires monitoring of neutrophil count due to risk of agranulocytosis

120
Q

What is the best test to monitor the anticoagulation effect of warfarin?

A

Prothrombin time (PT)

121
Q

What is the best test to monitor the anticoagulation effect of heparin?

A

Activated partial thromboplastin time (aPTT)

122
Q

How can proton pump inhibitors (omeprazole) used for GERD increase the risk for osteoporosis?

A

Insoluble calcium requires an acidic environment for proper absorption

PPIs reduce gastric acid secretion in the stomach, creating a less acidic environment that can decrease calcium absorption and increase osteoporosis risk with long-term use

123
Q

On cardiac auscultation, a patient has a low-pitched holosystolic murmur that is best heard over the left sternal border. The murmur is accentuated during the handgrip exercise. What heart defect is present?

A

Ventricular septal defect

The handgrip exercise increases afterload which increases pressure in the LV causing more blood to flow from the LV to the RV

124
Q

What drug can be used to treat patients with a CMV viral infection (typically HIV pts) that is resistant to ganciclovir and does NOT require intracellular activation?

A

Foscarnet

Foscarnet is a viral DNA/RNA polymerase inhibitor and HIV reverse transcriptase inhibitor

It does not require activation by viral kinase

125
Q

Ornithine is a metabolite/intermediate in what metabolic pathway?

A

Urea cycle

The urea cycle converts ammonia generated from amino acid (protein) metabolism into uric acid for excretion from the body (↑ ammonia = neurotoxic)

126
Q

What are signs and symptoms of Vitamin A toxicity?

A

Nausea, vomiting, blurred vision, dry skin, alopecia, hepatotoxicity, hepatosplenomegaly, papilledema

127
Q

What type of tumor is classically associated with unilateral hearing loss and where does it occur?

A

Acoustic schwannoma arising from cranial nerve VIII

Location - Cerebellopontine angle (between cerebellum and pons)

128
Q

What drug can be used for treatment of mild hemophilia A?

A

Desmopressin

Desmopressin increases circulating factor VIII and vWF

129
Q

What is the most common predisposing condition for infective endocarditis (subacute endocarditis) in developed nations? developing nations?

A

Developed nations - Mitral valve prolapse

Developing nations - Rheumatic heart disease

Damaged/diseased heart valves exhibit endocardial injury with microscopic deposits of platelets and fibrin upon which bacteria can colonize, infecting the valve

130
Q

What bacterial organism is associated with septic shock, DIC and hemorrhagic destruction of the adrenal glands bilaterally (Waterhouse-Friderichsen syndrome)?

A

Neisseria meningitidis

N. meningitidis is a common cause of bacterial meningitis but can also cause sepsis

131
Q

What type of necrosis results from a pulmonary infarct?

A

Hemorrhagic necrosis (wedge shaped)

Pulmonary infarcts cause hemorrhagic necrosis due to the dual blood supply to the lungs (pulmonary and bronchial arteries)

132
Q

What drug commonly prescribed for parasitic infections and bacterial vaginosis can cause a disulfiram-like reaction when taken with alcohol?

A

Metronidazole

Can cause headache, nausea , vomiting and abdominal cramps when combined with alcohol (due to acetylaldehyde accumulation)

133
Q

What congenital defect is associated with the potentially teratogenic bipolar medication lithium?

A

Ebstein anomaly

Apical/’downward’ displacement of the tricuspid valve leaflets, decreasing right ventricular volume (and makes the right atrium larger)

134
Q

What substance is freely filtered at the glomerulus and is neither reabsorbed nor secreted by the renal tubules?

A

Inulin

Inulin clearance is commonly used to calculate GFR (amount in = amount out)

135
Q

What antibodies are associated with the two subtypes of scleroderma (systemic sclerosis); diffuse scleroderma and limited scleroderma (CREST syndrome)?

A

Diffuse scleroderma - anti-Scl-70 antibody (anti-DNA topoisomerase I antibody)

Limited scleroderma (CREST) - anti-centromere antibody

136
Q

What serologic marker of hepatitis B virus indicates active viral replication and increased infectivity?

A

HBeAg

Presence of HBeAg also greatly increases the risk of vertical transmission of the virus

137
Q

What is the most serious complication of digoxin toxicity?

A

Life-threatening arrhythmias

138
Q

What is the typical cause of painless, unilateral visual disturbances with flame-shaped retinal hemorrhage seen on funduscopic exam?

A

Hypertension

Severe hypertension can cause endothelial damage in the retinal arterioles leading to acute retinal hemorrhage

139
Q

A 55 yo woman presents with multiple, firm purple nodules on her upper right arm. The patient was diagnosed with right-sided breast cancer 12 yrs ago and was treated with radical mastectomy and axillary lymph node dissection at that time. What is the origin/diagnosis of the skin lesions?

A

Angiosarcoma (lymphangiosarcoma)

Chronic lymphedema (resulting from removal of axillary lymph nodes) predisposes to the development of angiosarcoma (very poor prognosis)

140
Q

What is the main mechanism of excess copper removal in the healthy human body?

A

Hepatic excretion into bile (and then the stool)

141
Q

What is the most common cause of sudden cardiac death within 48 hours of an acute myocardial infarction?

A

Ventricular fibrillation

142
Q

Describe the pathogenesis and clinical presentation of Friedreich ataxia

A

Friedreich ataxia is an autosomal recessive, trinucleotide repeat (GAA) mutation of the frataxin (FXN) gene

The mutation leads:

  • cerebellar ataxia (spinocerebellar tract degeneration)
  • loss of position/vibratory sensation (dorsal column/dorsal root ganglia degeneration)
  • kyphoscoliosis (crooked spine)
  • hypertrophic cardiomyopathy
143
Q

What is schizophreniform disorder?

A

Psychotic symptoms lasting between 1-6 months

TLDR - schizophrenia that lasts under 6 months (many progress to full blown schizophrenia)

144
Q

What are signs and symptoms of arsenic poisoning and what is the treatment/antidote?

A

Arsenic is found in pesticides/insecticides, contaminated water, pressure-treated wood, metallurgy, mining

Clinical features of arsenic poisoning are:

  • severe watery diarrhea
  • hypotension from dehydration (from diarrhea)
  • QTc prolongation (can cause torsades de pointes)
  • GARLIC ODOR on breath/stool

Treatment - Dimercaprol

145
Q

In genetics, what is the concept of heteroplasmy?

A

Heteroplasmy describes having different mitochondrial genomes within a single cell

For example - an inherited mitochondrial disorder from someone’s mother may only affect some of the mitochondria in their cells and other mitochondria may be completely normal

146
Q

What cofactor is required for transamination reactions which are essential for amino acid metabolism (for use in gluconeogenesis or nitrogenous waste disposal via the urea cycle)

A

Pyridoxine (vitamin B6) is a cofactor for amino acid transamination

147
Q

What are the two most common causes of acute pancreatitis?

A

Gallstones and alcoholism

148
Q

What are causes of acute pancreatitis included in the mnemonic GET SMASHED?

A 
Gallstones
Ethanol
Trauma
Steroids
Mumps
Autoimmune
Scorpion sting
Hypertriglyceridemia/Hypercalcemia
ERCP (endoscopic retrograde cholangiopancreatography)
Drugs (sulfa, NRTIs, protease inhibitors)
149
Q

What type of neurological dysfunction would arise from an infarction of the ventral posterior nucleus in the thalamus?

A

Complete contralateral sensory loss (pain, temperature, vibration, proprioception, touch, etc.)

Ventral Posterior Lateral Nucleus -spinothalamic + dorsal columns (upper/lower extremities)

Ventral Posterior Medial Nucleus - trigeminal sensory

150
Q

What nucleus in the brain secretes the vast majority of serotonin?

A

Raphe nuclei

151
Q

What are bilateral acoustic neuromas (of CN VIII found at the cerebellopontine angle) associated with?

A

Neurofibromatosis Type 2

NF-2 is an autosomal dominant disease caused by mutation of the merlin gene on chromosome 22

Bilateral acoustic neuromas are its only big association (do not confuse with NF-1 skin neurofibromas)

152
Q

A 35 yo woman goes into a protracted labor that eventually requires a cesarean delivery. Shortly after delivery, the patient develops chest pain and difficulty breathing, eventually going into cardiorespiratory arrest and dies. What is the likely cause of this complication from delivery?

A

Amniotic fluid embolism

Amniotic fluid enters the maternal circulation through sites of trauma (C-section) and causes an anaphylactic reaction as well as disseminated intravascular coagulation (DIC) resulting in cardiorespiratory arrest

153
Q

What type of arthritis is associated with activity-related join pain, slight to no morning stiffness, involvement of the DIPs and PIP and hard, bony enlargement in the joints?

A

Osteoarthritis

mechanical etiology from joint wear and tear

154
Q

What antibodies are associated with primary biliary cirrhosis?

A

Anti-mitochondrial antibodies

155
Q

What is the initiating event in the pathogenesis of acute appendicitis?

A

Obstruction of the lumen of the appendix

Obstruction is most commonly caused by fecaliths and causes a buildup of mucus in the appendix that eventually causes enlargement and ischemic injury

156
Q

In psychology, what is depersonalization/derealization disorder?

A

A dissociative disorder involving recurrent episodes of:

  • feeling detached from one’s body or an outside observer of one’s self
  • experiencing surroundings as unreal

This is not a psychotic disorder because these patient’s have intact reality testing (they know it isn’t real)

157
Q

What is the major stimulator of respiration in healthy people and where is this substance sensed?

A

PaCO2 is the major stimulator of respiration and is sensed by central chemoreceptors in the medulla

158
Q

What is the major stimulator of respiration in patients with chronic COPD or sleep apnea and where is this substance sensed?

A

PaO2 is the major stimulator of respiration in people who are chronically hypoxic (COPD) because of a blunted response to PaCO2

PaO2 is sensed by peripheral chemoreceptors (aortic and carotid bodies)

159
Q

What embryologic structure is the ductus arteriosus derived from?

A

Sixth aortic arch

Failure of the PDA to close at birth can cause a continuous “machine-like” murmur

160
Q

What is the best imaging modality for diagnosing osteomyelitis?

A

MRI

Suspect osteomyelitis in a patient that has new onset bone pain and a fever

161
Q

What nerve is damaged in a patient with wrist drop?

A

Radial nerve

radial innervates all of the extensor muscles of the arm

162
Q

How does chronic hyperglycemia in patients with long-standing diabetes mellitus cause formation of cataracts an peripheral neuropathy?

A

Excess plasma glucose is converted into sorbitol within the cells of the lens and peripheral Schwann cells

Sorbitol accumulates within these cells increase the osmotic pressure and stimulate influx of water leading to osmotic cellular injury

163
Q

What pH abnormality is seen in pulmonary embolism?

A

Respiratory alkalosis (PE causes physiologic hyperventilation response)

PE causes the development of a ventilation/perfusion (V/Q) mismatch → ensuing hypoxemia stimulates hyperventilation → hyperventilation causes large amounts of CO2 blown off → respiratory alkalosis

164
Q

Which fat soluble vitamin is essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells) and therefore prevents squamous metaplasia?

A

Vitamin A

165
Q

A 15 y/o boy presents complaining of poor exercise endurance and an inability to keep up with his peers while weightlifting during which his “arms feel like jelly after only a few reps”. His exercise intolerance greatly improves after drinking an oral glucose solution before exercising. Disease/Dx?

A

McArdle disease (glycogen storage disease V)

Deficiency of myophosphorylase causes failure of muscle glycogenolysis which causes early onset of fatigue, muscle cramps and rhabdomyolysis

166
Q

What organ is responsible for increased hematocrit in response to chronic hypoxia (low oxygen delivery)?

A

Kidney

Renal cortical cells sense hypoxia and respond by synthesizing and releasing erythropoietin (EPO) → stimulates RBC production → ↑ hematocrit

167
Q

What would be seen histologically in a biopsy from a patient with Hashimoto thyroiditis?

A

Lymphoid aggregate (mononuclear infiltration) with germinal centers, Hurthle cells may also be present

These findings coincide with the autoimmune destruction of the thyroid seen in Hashimoto thyroiditis

168
Q

What is Lynch syndrome (hereditary nonpolyposis colorectal cancer)?

A

Autosomal dominant disease causing mutation of DNA mismatch repair genes

Associated with colon (80% will get cancer of proximal colon), endometrial, ovarian and skin cancers (because of extensive DNA damage)

169
Q

In addition to blocking histamine receptors, what other receptors do first generation antihistamines (chlorpheniramine, diphenhydramine) effect?

A

anti-muscarinic
anti-alpha adrenergic
anti-serotonergic

170
Q

What cells do Shigella bacteria invade in the gut?

A

M cells (microfold cells)

M cells are located within Peyer patches in the ileum

171
Q

Which way does DNA synthesis occur in?

A

5’ → 3’ direction

172
Q

What causes ventricular enlargement in hydrocephalus ex vacuo?

A

Ventricular enlargement occurs secondary to brain atrophy

173
Q

What are the characteristic histological findings in Reye syndrome, a hepatic disease caused by treatment of febrile illness in children with aspirin?

A

Microvesicular steatosis of hepatocytes and mitochondrial abnormalities

174
Q

Is H. pylori infection of the stomach more likely to cause duodenal or gastric ulceration?

A

Duodenal ulceration (almost 100% of duodenal ulcers are due to H. pylori infection)

Increased gastric acid acidity (↓ pH) results from H. pylori induced inflammatory destruction of somatostatin-secreting cells in the gastric antrum

USMLE Step 1 (7 decks)

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