Week of March 30 Flashcards

Question

Presence of capillary hemangioblastomas in teh retina and/or cerebellum, as well as congenital cysts and/or neoplasms in kidney, liver and pancreas

Answer 1

VHL disease. Also at increased risk of RCC, which cna be bilateral

Answer 2

Cutaneous facial angiomas as well as leptomeningeal angiomas. Skin involvement overlies the opthalmic (V1) and maxillary (V2) distributions of the trigeminal nerve. Associated with mental retardation, seizures, hemiplegia, and skull radiopacities. Skull radiographs may show characteristic "tram-track" calcifications.

Answer 3

AD. Kidney, liver, and pancreatic cysts. CNS involvment includes cortical and subepedymal hamartomas. Cutaneous angiofibromas (Adenoma sebaceum), visceral cysts, and a vairety of other hamartomas, as well as renal angiomyolipomas and cardiac rhabdomyomas. Seizures are a major complication.

Answer 4

Cisplatin: forms ROS that can form DNA crosslinks. SE is nephrotoxicity --\> prevent with **amifostine** and establishment of a chloride diuresis (via IV saline) to keep cisplatin in a nonreactive state. ## Footnote NOTE: Leucovorin (folinic acid) used in treament of MTX overdose. Dexrazoxane is an iron-chelating agent that can help prevent anthracycline-induced (i.e. doxorubicin) cardiotoxicity.

Answer 5

Thymidine is a nucleotide used for DNA synthesis; therefore nucleotide uptake occurs in the S phase of the cell cycle. Reflects the high number of tumor cells in the S phase (preparing to divide) that are present in a tumor. A high proliferation rate suggests a **high tumor grade** and, therefore, a poor prognosis. 616

Answer 6

SCC: PTHrP and hypercalcemia Small Cell: Cushing Syndrome and SIADH

Answer 7

During first week after an acute stroke, CT will show ischemic area to be **hypodense**. Microscopically, neurons display signs of irreversible damage during first 48h (**"red neurons"**). **Neutrophils** initially move into the area, followed by **microglia 3-5d** after onset of ischemia. As the neurons disintegrate, there is extensive phagocytosis of myelin degradation products by microglia, causing an **abundance of lipids** to be seen in the cytoplasm. 20

Answer 8

Patients have functional asplenia as a result of multiple infarctions of the spleen --\> prone to infection by encapsulated organisms. Both Staph aureus and **Salmonella** (high fever, exquisite thigh pain, bacteremia d/t nonlactose-fermenting, oxidase-negative organism) are common causes of osteomyelitis. 1137

Answer 9

**Delayed-type HSR,** where antigen is taken up by dendritic cells and presented to **CD4+ T-lymphocytes** on MHC class II. These stimulates TH-lymphocytes (usually of the TH1 lineage) then release release IFN-y to cause recruitment and stimulation of macrophages. Take days to reach their peak activity. 544

Answer 10

part of a **normal grief reaction** and may not be indicative of major psychiatric illness. 10465

Answer 11

Slowly progressive symmetric postural and/or kinetic tremor that most commonly affects upper extremities. First-line treatment is the nonspecific beta-adrenergic antagonist **propranolol**. 1946

Answer 12

**Proper hand washing**, full barrier precautions during insertion of central line, chlorhexidine for skin disinfection, avoidance of femoral insertion site, removal of cath when no longer needed. 8282

Answer 13

The concentrations of PAH, creatinine, inulin, and urea increase as fluid runs along the proximal tubule, while the concentrations of bicarbonate (actively reabsorbed d/t activity of carbonic anhydrase), glucose, and AAs decrease. 1617

Answer 14

HCC which is strongly associated with HBV infection and often preceded by HBV-induced cirrhosis. **Integration of viral DNA into the genome of host hepatocytes** triggers neoplasic changes. Other risk factors for HCC include HCV, alcoholic cirrhosis, aflatoxins, and hemochromatosis. 822

Answer 15

Inhaled anesthetics (e.g. **halothane**) can be associated with a highly lethal fulminant hepatitis that cannot be distinguished from acute viral hepatitis. In severe cases, extensive HCC damage causes liver to rapidly atrophy and appear **shrunken; **widspread **centrilobular** **necrosis** and inflammation of protal tracts. Patients have **significally elevated aminotransferase levels** d/t massive hpatocellular injury and **prolonged prothrombin time** (factor VII has shortest half-life) d/t failure of hepatic synthetic function. 369

Answer 16

PCR requires **primers that are complementary to the regions of DNA flanking the segment to be amplified** (note that while PCR does not require that the sequence of target DNA be known, the flanking sequences must be known in order to make the primers). 2043 Thermostable DNA polymerase, deoxynucleotide triphosphates, and the target DNA template strand are also necessary.

Answer 17

Generally affects young children and is classically preceeded by an URI. This IgA-mediated hypersensitivity (leukocytoclastic) vasculitis commonly causes abdominal pain, joint pain, lower extremity palpable purpra and hematuria.

Answer 18

Pancreatic amylases, along with salivary and brush border amylases, are required for degradation of polysacchraides into monosaccharides, as polysaccharides cannot be absorbed by the intestinal mucosa. **D-xylose is a monosaccharide**; thus, its absorption does not require pancreatic enzymes and is not affected by pancreatic insufficinecy. Oral administration of a fixed dose of D-xylose can be used to differentiate between malabosprtion of pancreatic vs. GI mucosal etiology. 1907

Answer 19

Used to detect **DNA-binding proteins** such as transcription factors, nucleases, and histones. The target protein binds to a labeled, dsDNA probe that is homolgous to the protein's regulatory sequence. **c-Jun** and **c-Fos** are nuclear transcription factors that directly bind DNA via a leucine zipper motif; the genes that code for these are protooncogenes. 2044

Answer 20

* Ensure privacy (ask others to leave for interview) * Nonjudgmental, empathic, open-ended questioning * No pressure to disclose, report, press charges, leave partner * Ask patient if she feels safe * **Determine if patient has an emergency safety plan**/provide referrals for shelts, domestic violence agency, mental health as needed. 10659

Answer 21

Patients older than 65 are particuarly prone to developing secondary bacteria PN after influenza infection d/t virally induced damage to the mucocillary clearence mechanisms of the respiratory eptihelium. In order, the pathogens most often responsible for secondary bacteiral pneumonia are Strep pneumoniae, Staph aureus, and H. influenzae.

Answer 22

Bacteiral endocarditis. Acute, diffuse, proliferative glomerulonephritis secodnary to circulating immune complexes may complicate BE and can result in acute renal insufficency. 229

Answer 23

If seperated, the monomeric subunits will demonstrate a **hyperbolic oxygen-dissociation** (compared to the normal sigmoid shape) curve simmilar to that of **myoglobin**. The partial pressure of oxygen at which 50% of myoglobin molecules are oxygen saturated (P50) is only 1mmHg, which is much lower than the P50 of hemoglobin (26 mmHg). 1413

Answer 24

**Type 3 RPGN** ("pauci immune"): most patients have ANCA in thier serum. This condition is associated with Wegner's, but it can also be idiopathic. Patients present with renal failure, pulm sx (cough, dyspnea, hemoptysis), and URT sx (epistaxis, mucosal ulceration, chronic sinusitis). 13 ## Footnote Remember: Type I is characterized by anti-GBM antibodies with linear deposits of IgG and C3 on IM; foudn in association wtih Goodpasture syndrome. Type II is immune-complex mediated with a "lumpy bumpy"" granular pattern of staining on IM; can be a complication of poststrep glomerulonephritis, SLE, IgA nephropathy, or HSP.

Answer 25

Form of allergic contact dermatitis, which is a type IV HSR mediated primarily by **T lymphocytes**. Poison ivy/oak/sumac all produce urushiol which causes an immune response when attached to proteins (i.e. a hapten). In urushiol-induced contact dermatitis, **CD8 T cells** are the primary effector cells and directly destroy keratinocytes expresseing haptenated proteins. It manifests as intesnely pruritic erythematous papules, vesicles or bullae that often form linear patterns. 1133

Answer 26

**Nystatin**: polyene antifungal; acts by binding to ergosterol in the fungal cell membrane, cuasing the formation of pores and leakage of fungal cell contents. Not absorbd from GI tract and is adminsterd as an oral "swish and swallow" agent.

Answer 27

**Pentazocine**, which produces analgesic effects with little to no abuse potential. When used in combo with morphine or other opioids that are selective mu receptor agonists, it can competively inhibit mu receptors and produce antagonistic effects reducing opioid analgesic effects. When given to patients dependent on morphine, withdrawal sx can occur secondary to its antagonistic effect at mu receptors. 774

Answer 28

**Syringomyelia**: formation of a cavity (Syrinx) in the cervical region of the spinal cord which damages the **ventral white commissure** (area of decussation for fibers of the lateral spinothalamic tract), leading ot **bilateral loss of pain and temp sensation that is limited to the affected levels** (typcially arms and hnds); distal sensation is preserved. Destruction of the motor neurons in the ventral horsn (due to extension of the syrinx) causes flaccid paralysis and atrophy of the intrinsic muscles of the hand. 503

Answer 29

**AL amyloidosis**; amyloid protein is derived from monoclonal immunoglobulin light chaisn, and oftne forms deposits in teh kidneys, heart, tonuge, and nervous system. AL amyloidosis contributes to the developmetn of renal failure in MM. 872

Answer 30

Exert their glucose-lowering effect by reducing insulin ressitance by bindign to PPAR-gamma. F**luid retention, with resultant weight gain and edema**. This excess fluid can exacerbate underlying CHF. ## Footnote Remember: hypoglycemia can occur with the use of sulfonylureas and insulin.

Answer 31

Include positive inotropes such as digoxin, beta-adrenegic blockers, ACE-I, and diuretics (loop and potassium sparing). Potassium-sparing diurectics act primarily by antagonizing the effects of aldosterone on the late distal tubule and cortical collecting ducts. 2005

Answer 32

Children that most frequently affects the long bones. Staph aureus is implicated in most cases secondary to a bacteremic event. Strep pyogenes (GAS) is the second most common cause. 646

Answer 33

_Hashimoto's thyroiditis_: **mononuclear, parenchymal infiltration wtih well-developed germinal centers** is a characteristic histiologic finding. Presence of hypothyroidism (elevated TSH and low T4/T3) and elevated antithyroid peroxidase antibody. 769

Answer 34

Genetic variation has led to the developmetn of a hypervariable region of the envelope glycoprotein that is especially prone to frequent mutation. There is also no proofreading 3' --\> 5' exonuclease in the RNA polymerase. Becuase of the **variety in the antigenic structure of HCV envelope proteins**, the productio of host antibodies lags behind the production of new mutant strains of HCV and effective immunity against infection is not conferred. 44

Answer 35

This is simply excessive (pathologic) water drinking. **Significant increase in urine osmolality during water depriviation study** and **\<10% change to vasopressin administration** (perhaps d/t deficency in aquaporin channels). Patients will have low serum sodium levels and osmolality. Restriction of water intake normalizes urine output in patients. 212

Answer 36

Small, noncoding form of RNA that contains unusal nucleosides suchas pseudouridine and thymidine. tRNA has a CCA sequence at its 3' end that is used as a recognition sequence by proteins, and the 3' terminal hydorxyl group of the CCA tail is used as the bindign site for the amino acid. 2037

Answer 37

**Protein M**: **inhibits phagocytosis** and complement activation, cytotoxic for neutrophils in the serum, mediates bacterial adherence, and is the target of type-specific humoral immunity tto S. pyogenes. 723

Answer 38

Oral contraceptives. Multiparity and breast-feeding also decrease the risk of ovarian cancer.

Answer 39

* P. jiroveci (CD4 \<200): TMP-SMX * Toxoplasma gondii (CD4 \<100): TM-SMX * M. avium and M. intracellulare (CD4 \<50): Azithromycin. Marked anemia, HSM, and elevated ALP and LDH levels are more common with MAC than extrapulm TB d/t widespread involvemetn of the RES. In contrast to MTB, MAC grows well at high temps and will exhibit optimum growth at 41C. * Histoplasma capsulatum (CD4 \<150): Itraconazole 1312

Answer 40

**Lipofuscin** is the product of **lipid peroxidation,** accumulation in aging cells (espeically in the heart and liver of aging or cachetic, malnourished patients)

Answer 41

**B**e **W**ise **F**ools **GOLD H**eeds **S**illy **HO**pe * Bruton aggamaglobulinemia * Wiskott-Aldrich * Fabry Disease * G6PD Deficeincy * Ocular Albinism * Lesch-Nyhan * Duchenne (and Becker) MD * **H**unter **S**yndrome * Hemophilia A and B * Ornithine Transcarbamylase

Answer 42

**X-G**irlfriends **F**irst **A**id **H**elped **A**ce **M**y **T**est Fragile **X** = C**G**G **F**riedrich ataxia = G**A**A **H**untington = C**A**G **M**yotonic dystrophy = C**T**G

Answer 43

**Ataxia-telangiectasia**: AR; results from defect in DNA-repair genes. Sx: cerebellar ataxia (occurs in first years of life d/t cerebellar atrophy), oculocutaenous telangiectasias, repeated sinopulmonary infections, and increased incidence of malignancy. 673

Answer 44

* _Ataxia-telangiectasia_: DNA hypersensitivity to ionizing radiation. **Nonhomologous end joining** (brings together 2 ends of DNA fragments to repair double-strandd breaks) is mutated * _Xeroderma pigmentosum_: Defective **nucleotide excision repair** which prevents repair of pyrimidine dimers b/c of UV light exposure. Causes premature skin aging and increased risk of malignant melanoma and SCC * _Fanconi Anemia_: hypersensitivty of DNA to cross-linking agents * _Bloom Syndrome:_ generalized chromosomal instability. Increased susceptibility to neoplasms. * _HNPCC_: defect in **DNA mismatch-repair enzymes**. Leads to increased susceptibility to colon cancer.

Answer 45

Elevated amniotic fluid levels (polyhydramnios) can either be d/t to... * _Decreased fetal swallowing_: GI obstruction (e.g. d/t duodenal, esophageal, or intestinal atresia) and **anencephaly** * _Increased fetal urination_: high cardiac output d/t anemia or twin-to-twin transfusion syndrome

Answer 46

Vascular lesion of the **thalamus** (e.g. ischemic or hemorrhagic stroke) results in damage to thalamic VPL and VPM nuclei causing **complete contralateral sensory loss**. Although there are no motor deficits, **proprioception** is often profoundly affected and may lead to **difficulty ambulating and falls**. 2076

Answer 47

**_Lacunar Infarcts_**: results from occlusion of small penetrating arteries that supply these structures, most comonly d/t **chronic uncontrolled HTN** or **diabetes**. ## Footnote Causes (2077) * **Lipohyalinosis**: destructive vessel lesion with loss of normal arterial architecture, mural foam cells, and, in acute cases, evidence of fibrinoid vessel wall necrosis. * **Microatheromas**: accumulation of lipid-laden macrophages within the intimal layer of a vessel. In lacunar infarcts, they cause occlusion of a penetrating artery at or near it origin off parent vessel.

Answer 48

Decreased lung volumes and increased expiratory flow rates at the corresponding lung volumes. Expiratory flow is increasd d/t **decreased lung compliance** (increased elastic recoil; compliane is the change in lung volume for a given change in pressure) and **increased radial traction** exerted on the conducting airways by the fibrotic lung. 1543 ## Footnote Airflow rate is inversely related to airway resistance. Airway resistance (like vascular) is inversely related to the radius of the conduncting vessel to the fourth power. Thus, as radius of airway increases, the resistance of that airway decreases exponentially. In normal individual, high lung volumes are associated with decreased airway resistance d/t increased radial traction (outward pulling) on conducting airways exerted by the inflated and stretched pulmonary interstitium.

Answer 49

The **duodenum** is the main site of *digestion* of dietary lipids, while the **jejunum** is the main site of lipid **absorption**. 1018 ## Footnote Fatty acids, cholesterol and monoacylglycerol diffuse through the brush border membrane of the intesitnal cells without the asistance of transporter proteins. Inside the cell, TGs and cholesteryl esters are reconstructed and combined with proteins to form chylomicrons. Bile acids are necessary for lipid absorption. Cholecystectomy has little effect on lipid digestion and absorption though patients may find it difficulty to eat a large fatty meal b/c they do not have ability to release a large amount of stored bile into the gut.

Answer 50

* Anti-pseudomonal penicillins: ticeracillin, piperacillin * Cephalosporins: ceftazidime (3rd gen), cefepime (4th gen) * Aminoglycosides: amikacin, gentamicin, tobramycin * Fluoroquinolones: cipro, levo * Monobactams: aztreonam * Carbapenems: imipenem, meropenem

Answer 51

Promoter region that binds **transcription factors** and RNA polymerase II during the initiation of transcritpion. It is located 25 bases upstream from the beginning of the coding region.

Answer 52

Granulomatous inflammation of the media. Takayasu and temporal involve arterial vessels of different sizes and locations (aorta and proximal aortic arterial branch involvement vs. more distal carotid artery branch involvment, respectively)

Answer 53

**_Acetazolamide_**: inhibits carbonic anhydrase in the proximal tubule, which is responsible for catalyzing rxns necessary for NaHCO₃ reabsorption. Inhibting CA results in enahanced HCO₃^- and water excretion. SE include somnolence, parasthesias, and *urine alkalinization*; rarely metabolic acidosis, dehydration, hypokalemia and hyponatremia. 682 CA is also found in eyes, pancreas, GI tract, CNS and RBC. In eyes, inhibtion of CA will decrease HCO₃^- and acqueous humor formation

Answer 54

**Parenteral administration of vitamin B12. ** Parietal cells in the body and fundus of the stomach secrete IF (in adition to HCl) which binds to vitamin B12. This complex is then absorbed by enterocytes in the terminal ileum.

Answer 55

**Aminoglycoside** that **inhibits protein synthesis** by inactivating the small **30S RSU**. _Mutations_ that result in **altered structure of bacterial ribosomal proteins** are responsible for aminoglycoside resistance because they modify the ribosomal binding sites for these drugs. ## Footnote Other mechanisms of resistance to MTB drugs include decreased activity of bacterial catalase-peroxidase (resistance to **isoniazid**) and structural alterations of enzymes involved in RNA synthesis such as DNA-dependent RNA polymerase (resistance to **rifampin**)

Answer 56

**PBC**: autoimmune destruction of **intrahepatic bile ducts and cholestasis**. In the pre-cirrhotic stage, interlobular bile ducts are destroyed by **granulomatous inflammation** ("florid duct lesion") and **heavy lymphocyte-predominant portal tract infiltrate**. The simmilarity of these findings to those of **graft vs. host disease** suggest that immunolgoic injury is responsbile for disease manifestations. 402

Answer 57

**Catecholamine-secreting tumors** (e.g. pheochromocytoma of adrenal medulla). Differential shoudl also include autonimc dysfunction, cocaine abuse, withdrawal from clonidine and beta-blockers, and panic attacks. 933

Answer 58

**Cross-sectional study** (also known as a prevalence study). In other study designs, a certain time period seperates the exposure from the outcome. The major limitation of cross-sectional design is that a temporal relationship between exposure and outcome is not always clear. 1276

Answer 59

Many asthmatics frequently have allergies as a trigger d/t a high IgE response in the body. Anti-IgE antibodies given as a SC injection (i.e., omalizumab) have been shown to be effective in patients with moderate-to-severe allergic asthma. **Omalizumab** is a recombinant humanized IgG1 monoclonal antibody that binds with IgE to **inhibit the action of IgE with its receptor** on mast cells, basophils, and other cell types and descrease the allergic response. 2128

Answer 60

Giardia lamblia causes injury to duodenal and jejunal mucosa by adhering to the intestinal bursh border and releasing molecules that induce a mucosal inflammatory response. **Secretory IgA**, which binds to trophozoites and impairs adherence, is the major component of adaptive immunity against infection. Conditions causign IgA deficeincy predipose patients to chronic giardiasis. 1596

Answer 61

Produced by the **epithelial cells of the ciliary body** --\> excreted into posterior chamber and transferred through the pupil into anterior chamber --\> trabecular meshwork through which aqueous humor diffuses into Schlemm's canal --\> episcleral and conjunctival veins. 1363

Answer 62

Chronic eye disease characterized by increased IOP. Both narrow-angle and open-angle can ultimately lead to blindness. Drugs used to treat either **decrease production of aqueous humor** or **increase its outflow**. 1363 * **Timolol** (non-selective BBs): diminish secretion of aqueous humor by ciliary epithleium. * **Acetazolamide**: CA inhibitor; decreases aqueous humor secretion by ciliary epithleium * **PGF2a** (latanoprost, unoprostone, tavoprost) and **cholinomimetics** (pilocarpine, carbachol) decrease IOP by increasing outflow of aqueous humor.

Answer 63

**Vertical diplopia**: most noticeable when the affected eye looks toward the nose, as occurs when reading teh newspaper or walking downstairs.

Answer 64

**Lysosmal enzyme release** from neutrophils and macrophages. 302

Answer 65

* _Primary_: sequence of AAs linked by covalent peptide bonds. * _Secondary_: alpha-helix or beta-sheet; d/t **hydrogen bonding** * _Tertiary_: compact folding of secondary structure; ionic bonds, hydrophobic interactions, H-bonds, and disulfide bonds. Disulfide bonds enhance a proteins ability to withstand denaturation.

Answer 66

Necrotizing vasculitis of the upper and lower respiratory tract (causing **nasal ulcerations**, sinusitis, hemoptysis) and rapidly progressive glomerulonephritis - producing a varaible degree of renal failure - is characteristic of granulomatosis with polyangitis (**Wegners**). 459

Answer 67

**Fasting blood glucose** (NOT oral glucose tolerance test, which is usually reserved for screenign pregnat women for gestational diabetes)

Answer 68

* _Silicosis_: produces **eggshell calcifications** of hilar nodes and birefringent particles surrounded by fibrous tissues * _Asbestosis_: calcified pleural plaques and ferruginous bodies. Interstital pattern of involvement, more prominent in lower lobes. * _Berylliosis_ and _hypersenstiivty pneumonitis:_ noncaseating granulomas * _Coal miners lung_: perilymphatic accumulations of coal dust-laden macrophages

Answer 69

1. _Alveolar hypoventiliation_ or inspiration of air with low pO2 (e.g. at high altitude). 2. _Ventilation-perfusion mismatch:_ poor ventilation of a well-perfused alveoli results in physiologic shunting, leading to an increased A-a gradient (e.g. pneumonia, obstructive pulm disease, pulm embolism) 3. _Diffusion impairment_: diseases that cuase thickening of the alveolar capillary membranes (E.g. alveolar hyaline membrane diseases). Increased A-a as there is a normal concentration fo O2 in alveoli that cannot be transported into blood. 4. _Right-to-left shunting:_ cyanotic congential heart defects; venous blood bypasses lung and enters arterial circulation, thus decreasing PaO2. ## Footnote The A-a gradient is normal with alveolar hypoventilation and helps to distinguish it from other forms of hypoxemia. Hypoventilation is common in patients with suppressed central respiratory drive (eg sedative overdose, sleep apnea) or those with disease that decrease the inspiratory capacity (eg myasthenia gravis, obesity). 1582

Answer 70

Branches of the renal arter. For this reason, this portion of the donor ureter is typically viable after renal transplantation. 1680

Answer 71

* G1: cells prepare the building blocks for DNA synthesis * S: DNA replication. Topo I and II inhibitors as well as hydroxyurea and some antimetabolites function during this phase. * G2: DNA is checked for errors; if corrections cannot be made, then apoptosis results unless loss-of-function mutatiosn to the genes controllign this process are present * M: Division; vinca alkaloids and taxanes are specific for this phase (replicated chromosomes are unablet o align and subsequently unable to segregate into daughter cells), 1893

Answer 72

**Isoniazid**: only active against mycobacteria; inhibits mycolic acid synthesis (mycolic acids are essential for proper cell wall structure as well as the synthesis of virulence factors) --\> mycobacteria lose thier acid-fastness and become unable to s ynthesize new cell walls or multiply.

Answer 73

* **Androgenic alopecia** (1725) * Epilepsy * Ischemic heart disease * SCZ * Gluacoma * HTN * Malignancy * Type II DM

Answer 74

Classically presents with **acute onset diplopia**. On exam, the affected eye assumes a **"down and out" position** due to unopposed pull by the superior oblique (CN IV) and lateral rectus (CN VI). **Ptosis** also occurs d/t to paralysis of the levator palpebrae. Caused by **ischemic nerve damage**, which predominately involves the core of CN III with relative sparing of the peripheral part. Thus, becuase the component responsible for pupillary constriction and accomodation is located in peripheral aspect of nerve, **pupillary size and reactivey is normal**. 1060

Answer 75

Can be the first manifestation of **hypothyroidism**; esp. if patient presents wtih fatigability, weight gain, **proximal muscle weakness,** and **myoedema** (focal mounding of muscle following percusion; d/t slow reabsorption of calcium by the SR). _Other causes_ include autoimmune diseases (e.g. polymyositis, dermatomyositis), muscular dystrophies, and medications such as HMG-CoA reductase inhibitors.

Answer 76

While **DNA synthesis always occurs in 5' to 3' direction** on both strands, the leading and lagging strands are *constructed* in both the 5' to 3' and 3' to 5' directions, respectively (i.e. constructed in opposite directions). The laggign strand is synthesized discontinuosuly and is composed of short stretches of RNA primer plus newly synthesized DNA segments (Okazaki fragments). Thus, the lagging strand requires the repetitive action of DNA primase and DNA ligase. 1419

Answer 77

**Loss of melanocytes** and complete abscence of melanin pigment. 1110 ## Footnote NOTE: individuals with albinism have melanocytes that do not produce melanin becuase of absent or defective tyrosinase.

Answer 78

Primary oocytes are completely developed in female embryos by the 5th month of gestation, at which point they are arrested in prophase of meiosis I. Ovarian cycle hormones stimulate the primary oocyte to resume differentation. Prior to fertilization, secondary oocytes are arrested in metaphase of meiosis II.

Answer 79

_Early-onset familial_: both APP and presenilin gene mutations are thought to promote the production of A B-amyloid. * Amyloid precursor protein (APP) on ch. 21 * Presenilin 1 gene on ch. 14 * Presenilin 2 gene on ch. 1 _Late-onset familial_: **E4 on Apolipoprotein E**.

Answer 80

Pus consists of a thin, protein-rich fluid, known as liquor puris, and dead keratinocytes, primarily neutrophils. During infection, macrophages and surrounding endothelial cells release cytokines such as **IL-8** that trigger neutrophils to enter the site of infection via chemotaxis, and induces phagocytosis in neutrophils. Other chemotatic agents include n-formylated peptides, LTB4, 5-HETE (leukotriene precursor) and C5a. 8539

Answer 81

D/t debranching enzyme deficeincy, which leads to incomplete glycogen degradation. Alpha-1,6-glucosidic branch points cannot be degraded, so small chain dextrin-like material accumulates wtihin the cytosol of hepatocytes. Patients with this illness present with nonspecific findigns of hypoglycemia, hypertriglyceridemia, ketoacidosis, and hepatomegaly. 1030

Answer 82

_Efficacy_: measure of the maximum pharmacodynamic effect achievable wtih a drug. 1707 _Potency_: dose of drug that is required to produce a given effect. Drugs that bind their receptors with a higher affinity or are better able to gain access to their target tissues will have greater potency (lower ED50) Example: among the thiazides, 25mg of HCTZ and 5mg chlorthalidone produce simmilar drops in BP (simmilar efficacy), but chlorthalidone requires a lower dose, or a lower ED50, than HCTZ to cause simmilar effect (higher potency).

Answer 83

In contrast to femoral hernias, inguinal hernias are located above the inguinal ligament. The inferior epigastric vessels serve as an anatomic landmark that can be used to distinguish between direct and indirect. _Indirect_: located **lateral to inferior epigastric vessels.** Can protrude into the scrotum. Occur d/t **failure of processus vaginalis to obliterate**, allwoing abdominal contents to protrude through the deep inguinal ring. _Direct_: located **medially to the inferior epigastric vessels**. They do not protrude into the scrotum. Protrude through Hasselbach's triangle, a weak spot of the anterior abdoinal wall. 418

Answer 84

Low-grade fever, maculopapular rash with cephalocaudal progression, and posteior auricular and suboccipital LAD. Most adult women patients develop **polyarthritis** and polyarthralgia as sequelae. _Congential rubella syndrome_ is associated with **sensorineural deafness**, **cataracts**, and cardiac malformations (**PDA**).

Answer 85

Lowest osmolarity occurs in the **DCT**. Dehydration stimulates ADH secretion, which acts on teh collecting ducts to increase their permeability to water. In the presence of ADH, the collecting ducts contain the most concentrated fluid in the nephron, while the TALH and DCT contain the most dilute fluid.

Answer 86

**Nitroglycerin**: acts primarily as a venodilator. Cardiac workload is decreased b/c blood collects in teh venous system (redistrubiton) thereby decreasing preload --\> decreased ventricular wall stress and decreased cardiac oxygen demand; thus treats angina! 137

Answer 87

Suspect in a patient with ecchymoses, petechiae, and mucosal bleeding without s/sx of TTP/HUS, pancytopenia, marrow failure, or splenomegaly. 1954

Answer 88

Repeated splenic infarctions eventually lead to significant scarring, fibrosis, and arophy of the spleen (asplenia). This is typically completed by young adulthood.

Answer 89

Patients with SCD or other hemolytic anemias are predisposed to develop folic acid deficiency becuase of increased erythrocyte turnover. Low folic acid levels impair DNA synthesis, while leaving RNA synthesis unaffected. Cytoplsmic components then accumulate within the slowly dividng erythrocytes, producing cells that are larger than normal (macrocytes).

Answer 90

Inhibit the chronic angiotensin II-mediated LV hypertrophy and remodeling that occurs in association wtih myocardial failure. Over time, such remodeling diminishes contractile function. NOTE: BBs have been shown to improve mortality both in patients with systolic CHF and in patients with MI.

Answer 91

Neutropenia; presents wtih fever an dmouth ulcers.

Answer 92

Seen in malnourished, alcoholics, poor, and elderly Gingival bleeding, petechaie, ecchymoses, and poor wound healing. **Perifollciular hemorrhage and coiled (corkscrew) hairs** are commonly seen. Hydroxylation of proline and lysine residues in collgen occurs in RER and requires vitamin C as a cofactor.

Answer 93

Epinephrine increases systolic BP (a1 + b1), increases HR (b1), and either increases (high-dose; a1) or decreases (low-dose; b2) diastolic BP depending on the dose. Pretreatmetn with propranolol eliminates the beta effects of epinephrine (vasodilation and tachycardia), leaving only the alpha effect (vasoconstriction).

Answer 94

Germinomas are found in children and adolescents and show a strong male predominance. Histologically they are simmilar to testicular seminomas. 1261 * **Precocious puberty** may occur in males and is caused by b-hCG production * Aqueductal compression by the tumor may lead to **obstructive hydrocephalus** * **Parinaud sydrome** includes *paralysis of upward gaze and of convergence* - these sx occur d/t compression of the tectal area of the midbrain

Answer 95

Causes erythema infectiosum (fifth disease) in children and arthritis in adults. Parvovirus arthritis can mimic RA, but is unique in that it is self-resolving. 1896

Answer 96

Increased activity of **NFkB**, which is responsible for cytokine production. Proposed that the NOD2 mutation linked with Crohn's disease increases the activity of NFkB, allowing inflammation-inducing intracellular microbes to persist. 135

Answer 97

CN III, CN V1 (opthalmic nerve) branches, CN IV, CN VI, and superior opthalmic vein. ## Footnote NOTE: the sensory limb of the corneal reflex is mediated by the nasociliary branch of the first division of the trigeminal nerve (CN V1). The motor component of the corneal reflex is carried by the temporal branch of the facial nerve (CN VII).

Answer 98

Central diabetes insipidus which arises when the posterior pituitary gland fails to release vasopressin in sufficient quanitites. ## Footnote Normally, vasopressin porduces a V2 receptor-mediated increase in permeability to water and urea at the luminal membrane of the inner medullary collecting duct. The increase in urea reabosprtion corresponds toa decrease in the fractial excretion of urea and a decrease in renal clearence of urea from plasma.

Answer 99

Produces beta-endorphins, ACTH, and MSH

Answer 100

**Hyperkeratosis** (hyperplasia of stratum corneum), **parakeratosis** (retention of nuclei in the stratum corenum), and **atypical keratinocytes** with pleomorphic nuclei and multiple mitoses. They do not invade the dermis and are considered to be premalignatn.

Answer 101

Predilection for **temporal lobe;** results from reactivation of latent virus "living" in trigeminal ganglion and the virus' spread along this nerve into cranial vault. Restricted sx include **aphasia** (damage of speech areas), **olfactory hallucinations** (olfactory cortex), and **personality changes** (amygdala). **Edema and hemorrhagic necrosis of temporal lobes**. Eosinophilic intranuclear inclusions (**Cowdry type A**) are present in glial cells and neurons. Multinucleated giant cells may also be found.

Answer 102

Administration of drugs that act like FSH and LH. Treatmetn with menotropin acts like FSH and leads to formation of a dominant ovarian follicle. Ovulation is then induced by administration of a large dose of hCG, which stimulates the LH surge.

Answer 103

* 0-4h: minimal change * 4-12h: early coagulation necrosis, edema, hemorrhage, wavy fibers * 12-24h: coagulation necrosis, marginal contraction band necrosis * 1-5d: coagulation necrosis and neutrophilic infiltrate * 5-10d: macrophage phagocytosis of dead cells * 10-14d: granulation tissue + neovascularization * 2w-2m: collagen deposition/scar formation

Answer 104

_Anorexia nervosa_ * BMI \< 18.5. 2 subtypes: restrictring and binge eating/purging * Medical complications including **osteoporosis**, amenorrhea, **lanugo** or hair loss, **enlarged partoid glands** (if binge/purge type), hypotension, hypothermia, bradycardia, **cardiac atrophy**, **cardiomyopathy**, arrhythmias. _Bulimia nervosa_: recurrent binge eating with compensatory behaviors to prevent weight gain; both behaviors must occur at least 2X/week for 3m. Compensatory behaviors are subdivided into **purging types** (e.g. lax, diuretics, enemas, vomitting) and **nonpurging types** (excessive excercise, dieting, fasting). Usually of **normal weight**

Answer 105

**Ampicillin**, which should always be added to the empiric treatment of meningitis in infants and in immunocompromised adults. It is not sensitive to cephalosporins.

Answer 106

_Acute MR_: **near-normal LA compliance**. Therefore they tend to develop marked pulm HTN and pulm edema. May be d/t rupture of chordae, infective nedocarditis with destruction of valve leaflets, ischemia/rupture of papillary muscle, or failure of prosthetic valve. _Chronic MR_: valvular dysfxn occurs over time, permitting adaptive dilaatation of LA, thinning of its wall, and an **increase in LA compliance** --\> buffers the regurgitant volume from LV and results inlower elevation of LA pressures as compard to acute MR. Thus, they are less prone to pulm HTN/edema but are more prone to AFib and mural thromboembolism. Can be d/t myxomatous degeneration or MVP. 946

Answer 107

* RA: 0-8mmHg * RV: 4-25mmHg * Pulm artery: 9-25mmHg * LA: 2-12mmHg * LV: 9-130mmHg * Aorta: 70-130mmHg

Answer 108

Subjects are randomly allocated to a sequence of 2 or more treatments given consecutively. A washout (no treatment) period is often added between treatmetn intervals to limit the confuding effects of prior treatment.

Answer 109

GP6D deficiency is a defect in the HMP shunt that impairs glutathione reduction d/t failure to produce NADPH. **Glutathione reductase deficeincy** causes a similar clinical picture and is pathophysiologically simmilar --\> hydrogen peroxide is detoxified by glutathione peroxidase in RBC and glutathione is oxidized in this rxn; regeneration fo reduced glutathione is carried out by glutathione reductase using NADPH as electron donor. 1037

Answer 110

All have same _presentation_ (**pruritus, jaundice, dark urine, light stools, hepatosplenomegaly**) and _labs_ (**increased conjugated bilirubin**, increase cholesterol, increase ALP) _Secondary Biliary Cirrhosis_: extrahepatic biliary obstruction (gallstone, biliary stricture, chronic pancreatitis, carcinoma of pancreatic head) --\> increased pressure in intrahepatic ducts --\> injury/fibrosis and bile stasis. Complicated by ascending cholangitis. _Primary Biliary Cirrhosis_: AI rxn (more common in middle aged white females)--\> lymphocytic infiltrate + granulomas --\> destruction of intralobular bile ducts. Increase serum mitochondrial antibodies, including IgM. Associated with other AI conditiosn. Tx: ursodeoxycholic acid. _Primary Sclerosing Cholangitis_: concentric "onion-skin" bile duct fibrosis --\> "beading" of intra- and extrahepatic bile ducts on ERCP. Hypergammaglobulinemia (IgM). Associated with UC (p-ANCA). Can lead to secondary biliary cirrhosis and cholangiocarcinoma.

Answer 111

B. fragilis (expresses unique surface polysaccharides that have been shown to favor abscess formation) and E. coli are the most common.

Answer 112

Tremor, sedation, edema, heart block, **hypothyroidism** (weight gain, dry skin, hair loss, constipation, bradycardia) polyuria (ADH antagonist causing **nephrogenic diabetes insipidus**), teratogenesis (Ebstein anomaly. Excreted almost exclusively by the kidney; most is reabsorbed at the PCT following Na+ reabsorption. Need to **monitor renal fxn** (BUN + Cr).

Answer 113

**Mitral Regurgiation** as a result of **rheumatic heart disease**. Rheumatic valve disease typically presents as MR within the first few decades of life. Mtiral stenosis can also occur in rheumatic heart disease, and patients prsenting with such are generally middle aged. 2096 with audio

Answer 114

Enterococci produce aminoglycoside-modifying enzymes that transfer different chemical groups (Acetyl, adenyl or phopshate) to the aminoglycoside molecule and therefore impair ABX binding to ribosomal subunits. Acquired resistance mediated by plasmids or transposons. 1000

Answer 115

Most likely a **pilocytic astrocytoma** or **medulloblastoma**. These two tumors can be differentiated on brain imaging: pilocytic astrocytomas have both cystic and solid components (cystic with a tumor nodule protruding from wall), while medulloblastomas are always solid. ## Footnote _Pilocytic astrocytomas_: **Rosenthal fibers** (eosinophilic corkscrew fibers); GFAP+ _Medulloblastomas_: **Homer-Wright rosettes** (cells around center of fibrils; vs. _ependymoma_ forming **perivascular rosette**); small blue cells with hyperchromatic nuclei and scant cytoplasm

Answer 116

Glucose induced decreased AC activity leads to low intracellular concentration of cAMP --\> poor binding of CAP to CAP-DNA binding domain (high cAMP levesl activate CAP which binds cAMP and this complex then binds to a region upstream from the promoter and acts as a positive regulator of lac operon) --\> decreased expression of teh structural genes of the lac operon. 1478 ## Footnote NOTE: in lactose containing media --\> lactose binds to repressor protein --\> repressor protein cant bind to operator region --\> increased transcriptoin of lac operon structural genes --\> increased utilization of lactose for energy.

Answer 117

**pCO2** - it decreases cerebral vascular resistance leading to increased cerebral perfusion adn increased ICP. Patients with COPD usually have low pO2 (hypoxia) and high pCO2 (hypercapnia). Thus, thier cerebral circulation is most likely to be increased.

Answer 118

Polyethylene glycol is an **osmotic laxative**. Diarrhea associated wtih **lactase deficeincy** is also osmotic and occurs d/t acumultion of nonabsorbable lactose in teh intestinal lumen. Magnesium hydroxide (and other magnesium-containing compounds, such as magnesium citrate) is another osmotic lax that is often used.

Answer 119

Nonnucleoside reverse transcriptase inhibitors (**NNRTIs**) including **Efavirenz, Nevirapine, Delavirdine.** Bind to reverse transcriptase at site different from NRTIs; do not require phosprylation to be active or compete wtih nucleotides. _SE_: severe hepatotoxic reactions and life-threatening skin rxns (e.g. SJS, TEN). Remember: retroviral reverse transcriptase inhibitors prevent synthesis of viral DNA from RNA template.

Answer 120

cAMP, IP3, and ion channels. Nicotinic receptors are ligand-gated ion channels that open after bidning ACh. This results in an immediate influx of Na+ and Ca2+ into the cell and an outflux of K+ from the cell.

Answer 121

Results form inaccurate recall of past exposures by people in the study and applies mostly to retrospective studies such as case-control studies. People who have suffered an adverse event are more likely to recall risk factors than those without advere experiencies.

Answer 122

Results from genetic defect in NADPH oxidase, which noramlly participates in the killing of microbes within neutrophil and macrophage phagolysosomes. Patients develop recurrent bacterial/fungal infections caused by catalase positive organisms: "You need **PLACESS** for your **cat**s" - Pseudomonas, Listeria, Aspergillus, Candida, E.coli, S. aureus, Serratia. ALSO **Burkholderia cepacia**

Answer 123

**High-dose glucocroticoids** (e.g. prednisone), which are helpful in *decreasing the severity of inflammation* and decreasing extraocular volume. ## Footnote Infiltrative opthalmopathy is d/t edema and infiltration of lymphocytes into the EOM and CT. Retro-orbital fibroblats are stimulates by cytokines released from TH1 cells to produce excessive amounts of GAGs --\> increased volume of the retro-orbital tissues.

Answer 124

**Suspensory ligament of the ovary** (i.e. infundibulopelvic ligament): connects ovaries to lateral pelvic wall and contains the ovarian vessels. Ligate vessels during **oophorectomy** to avoid bleeding. **Ureter** courses retroperitoneally, close to gonadal vessels; at risk of injury during ligation. * _Cardinal ligament_: cervix to side wall of pelvis. Contains uterine vessels. * _Round ligament:_ uterine fundus to labia majora; travels through round inguinal canal. * _Broad ligament_: uterus, fallopian tubes, and ovaries to pelvic wall. Contains ovarian, fallopain, and round ligaments of uterus. Mesosalpinx, mesometrium and mesovarium are components. * _Ovarian ligament_: medial pole of ovary to lateral uterus. "Ovarian Ligametn Latches to Lateral uterus"

Answer 125

* Ovary: simple cuboidal * Fallopian Tubes: simple columnar * Uterus: simple (pseudostratified) columnar * Cervix: simple columnar (endocervix), stratified squamous (ectocervix) * Vagina: stratified squamous non-keratinized

Answer 126

Unconscious manifestation of neurologic symptoms when pathophysiological explanations for the symtoms cannot be found. Symptoms must be neurologic in nature and include blindness, aphonia, weakness, pseudoseizure, anesthesia, gait distrubance, diplopia, adn paralysis. It occurs more commonly in women and often occurs after significant life stress.

Answer 127

NPV: varies with the pretest probability of a disease; a patient with a high probability of having a disease will have a low NPV with a negative test but a patient with a low probability of having a disease wil have a high NPV with a negative test. The prevalence of disease is directly related to the pre-test probaiblity of having the disease and, thus, also affects NPV.

Answer 128

Shares antigens with human erythrocytes, and when teh body mounts a response against these antigens it also lyses RBCs leading to anemia. The antibodies causing the RBC destruction are **cold agglutinins**. After the infection has been eliminated and the immune ssytem is not longer activated against M. pneumoniae, the concentration of these antibodies decreases and the anemia spontaneously resolves.

Answer 129

_UCG (indirect) Hyperbilirubinemia_ 1. **Increased bilibrubin production**: hemolytic anemia, sickle cell disease, hematoma breakdown 2. **Impaired bilirubin uptake and storage**: viral hepatitis, drugs (e.g. Rifampin) 3. **Decreased UDP-glucuronosyltransferase activity**: Gilbert, Crigler-Najjar, neonatal physiologic jaundice _Conjugated (direct) Hyperbilirubinemia_ 1. **Excretion Defect**: Dubin-Johnson, Rotor Syndrome 2. **Biliary epithelial damage**: hepatitis, cirhosis, liver failure 3. **Intrahepatic biliary obstruction**: primary biliary cirrhosis, sclerosing cholangitis, drugs (chlorpromazine, arsenic), liver fluke 4. **Extrahepatic biliary obstruction**: pancreatic neoplasms, pancreatitis, cholangiocarcinoma, choledocholithiasis.

Answer 130

Some Risky Meds Can Prolong QT Sotalol, Risperidone, Macrolides, Chloroquine, Protease inhibitors (-navirs), Quinidine (class Ia and III), Thiazides

Answer 131

Immature defense mechanism involving misattribution of one's unacceptible feelings or impulses to another person who does not actually have them. Seen in patients who lack insight and acknowledgemetn of thier own motivtions and feelings. 1429

Answer 132

Ribosyl and Ribitol phopshate polymer called **polyribitol phosphate (PRP)**. It is the only serotype that contains pentose monosaccharides rather than hexose sugars as the carbohydrate component of the capsule. The PRP capsule prevents phagocytosis and intracellular killing by neutrophils, allowing the organism to invade the vasculature, persist in the blodostream, and spread hematogenously.

Answer 133

The **power** of a study is the ability of a study to detect a difference between groups when such a difference truely exists. Power is related to **type II error** (**beta**), which is the probability of concluding there is no difference betwen groups when one truly exists. The formula for **power = 1 - beta**.

Answer 134

Act on neighboring cells (paracrine signaling), stimulating them to synthesize antiviral proteins and degrade intracellular mRNA and impair protein synthesis. **RNase L** is an endonuclease which degrades both viral and cellular mRNA. **Protein Kinase R** functions to phosphorylase and inactivate eIF-2, thereby inhibiting translation initiation. These enzymes become **active only in the presence of dsRNA in virally infected cells --\> decreased protein synthesis by infected cells.** 1468

Answer 135

**Fully obstructive thrombus superimposed on a ruptured atherosclerotic coronary artery plaque. ** * S/Sx of an acute transmural MI include severe chest pain not relieved by rest or nitroglycerin, diaphoresis, dyspnea, nausea, lightheadness, and/or palpitations. * Peaked T waves are the first ECG sign (reflecting localized hyperkalemia), and ST-segement elevation follows within minutes to hours. Within hours to days, Q waves appear in involved leads. A lesser degree of occlusion by a thrombus superimposed on an acute plaque change would more likely cause _unstable angina_. A stable atheromatous lesion without an overlying thrombus, but obstructing \>75% of the coronary artery lumen, would likely cause only _stable angina_.

Answer 136

**Recurrent laryngeal nerve** is a branch of the vagus that loops below the aortic arch on left and below subclavian artery on rigth to provide motor innervation to larynx (all except cricothyroid muscle). This nerve travels with **inferior thyroid artery** (arises from thyrocervical trunk, a branch of the subclavian artery) and can be injured in surgical procedures of anterior neck (e.g., thyroidectomy). The **superior laryngeal nerve** is a branch of vagus that gives off internal and external branches. The **superior thyroid artery (**branches of the external carotid arteries) course with the external branch of this nerve;

Answer 137

Carbonic anhydrase activity within erythrocytes forms bicarbonate from CO2 and water. Many of the bicarbonate ions diffuse out of the RBC into the plasma. To maintain the electrical neutrality, chloride ions diffuse into RBC to take their place --\> "chloride shift," which is the principal cause of high RBC chloride content in venous blood.

Answer 138

Result of a decrease in diastolic LV compliance (=dV/dP). **Restrictive cardiomyopathy**, as can be caused by **amyloidosis**, may cause diastolic dysfunction. 93 NOTE: Infectious myocarditis and cardiotoxic agents including alcohol and doxorubin tend to produce a dilated cardiomyopathy with predominately systolic dysfunction.

Answer 139

**Neutrophils**: phagocytosis of urate crystals (*negatively birefringent; i.e. monosodium urate crystals*) by neutrophils causes the release of various cytokines and inflammatory mediators that lead to further neutrophil activation and chemotaxis. ## Footnote **NSAIDs** are first-line for treating acute gouty arthritis, which inhibit prostanoid biosynthesis (e.g. postaglandins, prostacyclin, thromboxanes), exerting a braod anti-inflammatory effect that includes inhibtion of neutrophils. If CI (PUD, renal impairment) treat wtih **colchicine**, which impairs neutrophil migration and phagocytosis by interfering with MT formation AND decreases tyorsine phopshorylation in response to MSU crystals, resulting in decreased neutrophil activation.

Answer 140

Chlamydia trachomatis serotypes L1-L3, which cause lymphogranuloma venereum (LGV). Histologically characterized by vhlamydial inclusion bodies in cellular cytoplasm. Tx is doxycycline. If untreated, causes fibrosis, lymphatic obstruction, and anogental stricutres and fistulas.

Answer 141

"Some Girls Love Licorice, Fellas Hate Candy" **S**yphils, **G**ranuloma inguinale (K. inguinale), **L**ymphogranuloma vernerum (C. trachomatis) = pain**L**ess pain**F**ul = **H**erpes simplex, **C**hancroid (H. ducreyi)

Answer 142

Chancroid (Haemophilus ducreyi) * Multiple and deep ulcers * Base may have gray to yellow exudate * Organism often clump in long parallel strands ("school of fish") Genital Herpes (HSV 1/2) * Multiple, small, grouped uclers * Shallow with erythematous base * Multinucleated giatn cells and intranuclear inclusions (Cowdry type A)

Answer 143

_Granuloma inguinale_ (donovanosis; Klebsiella inguinale): extensive and progressive, base may have granulation-like tissue; deeply staining gram-negative intracytoplasmic cysts (Donovan bodies) are diagnostic _Syphilis_: single, indurated, well-circumscribed ulcer with a clean base; thin, delicate, corkscrew-shaped organisms on darkfield microscopy _Lymphogranuloma venereum_ (Chlamydia trachomatis): small and shallow ulcers that heal rapidly; intracytoplasmic chlamydial inclusion bodies present in epithelial cells and leukocytes.

Answer 144

Folate deficeincy inhibits the formation of dTMP, which limits DNA synthesis and promotes megaloblastosis and erythroid precursor cell apoptosis. Becuase **thymidine** supplementation can moderately increase dTMP levels, it can reduce erythroid precursor cell apoptosis. _Remember_: thymidylate synthetase catalyzes the methylation of dUMP to dTMP while converting the folate derivative 5,10-methylene THF to DHF.

Answer 145

**Gallstone ileus**: results from passage of a large gallstone through a **cholecystenteric fistula** into the small bowel; the resulting communication between the gallbladder and small bowel d/t the fistula allows intestinal gas to enter the gallbladder and biliary tree. There is obstruction of the small bowel at the **ileocecal valve** whihch leads to s/sx of SBO (abd pain and distention, vomitting, tenderness to palpation, tinkling bowel sounds).

Answer 146

CF can lead to pancreatic insuffiency, fat malabsorption, and deficeincy of vitamins KADE. Vitamin A maintains orderly differentiation of specialized epithelia, including the mucus-secreting columnar epithelia of teh ocular conjunctiva, respiratory and urinary tracts, and pancreatic adn other exocrine ducts. **Avitaminosis A** can cause squamous metaplasia of such epithelia to a keratinizing epithelium.

Answer 147

Risk factor for the developmetn of **chronic lymphedema** involving the ipsilateral arm. Chronic lymphadema prediposes to the developmetn of **angiosarcoma** (Stewart-Treves syndrome) which is characterized by infiltration of the dermis with slit-like abnomral vascular spaces.

Answer 148

b-hCG becomes detectable in maternal serum only after the blastocyst successfuly implants. Implanation generally occurs on day 6 after ovulation. Generally, b-hCG is detectable in maternal serum about **8 days after ovulation** but can take up to 11 days.

Answer 149

Bacterial **DNA polymerase I** has 5' to 3' exonuclease activity, which is used to excise RNA primers (can also function as an excision-repair enzyme). The gaps created after RNA excision are then replaced with DNA in the 5' to 3' direction by DNA polymerase I.

Answer 150

The rate of effective erythropoiesis increases immediately and immature erythrocytes are released from the bone marow into the bloodstream. The **reticulocyte response peaks early** during replacement. **Hemoglobin and erythrocyte counts rise more gradually**.

Answer 151

TZDs activate PPAR-gamma, which is the nuclear receptor that alters the transcription of genes responsible for glucose and lipid metabolism. TZDs exert their glucose-lowering effect by **decreasing insulin resistance**. Important genes that are altered by PPAR-gamma include: **increased adiponectin**, increased fatty acid transport protein, increased insulin receptor substrate, increased GLUT-4

Answer 152

Radial nerve arises from posterior cord of brachial plexus and innervates muscles of posterior (extensor) compartment of arm. At the lateral epicondyle of humerus (where humerus articulates with radius), radial N. divdes into superficial (sensory to radial half of dorsal hand) and deep branches. **Radial head subluxation** can damage the **deep branch of the Radial N**, causing wrist drop, weakness of the FA and hand extensors, but no sensory deficits.

Answer 153

Mu opioid analgesics can cause contraction of **smooth muscles in the sphincter of Oddi** leading to increased pressures in the bile duct and gallbladder --\> biliary colic. Present with severe pain and cramping in the RUQ.

Answer 154

At the functional residual capacity. Increased lung volumes increase PVR due to longitudinal stretching of alvolar capillaries by expanding alveoli. Decreased lung volumes also increase PVR due to decreased radial traction from adjacent tissues on the large extra-alveolar vessels. 1620

Answer 155

The **internal iliac artery **1804 ## Footnote The gonadal artery and vein cross over the anterior surface of the ureter. The ureters gain access to the pelvis by crossing over teh anterior surface of the common iliac artery near its bifurcation into internal and external. At this point, the ureter lies medial to the gonadal vessels and anterolateral to internal iliac artery. In females the ureter than courses along uterosacral ligament just deep to uterine vessels (water under bridge) before entering bladder.

Answer 156

Opiate anti-diarrheal structurally related to meperidine that binds to mu opiate receptors in the GI tract and **slows motility**. This drug is combined with atropine at therapeutic doses to discourage abuse. NOTE that octreotide is helpful for secretory diarrhea.

Answer 157

Valsalva (straining phase), abrupt standing (from sitting or supine position), nitroglycerin administration. All fxn to decrease preload. 85 Mechanisms that decrease preload (i.e. venous return) or afterload reduce LV chamber size, which decreases the seperation between the mitral valve and the IVS, increasing obstruction. Manuevers that increase preload or aferload will decrease murmur intesity by increasing LVEDV and lessening the outflow tract obstruction.

Answer 158

One of the MCC of infections associated with foreign bodies d/t ability to form **biofilms**, which fxns as a barrier to ABX penetration and interferes with host defeneses. ## Footnote _MOA_: Foreign bodies become coated with host proteins (including fibringoen adn fibronectin) which serve as binding sites for bacteria. After attachment, bacteria multiply and communicate with e/o to induce synthesis of an extracellular polysaccharide matrix that encases the bacteria. Biofilms can disperse individual pathogen "seeds" into bloodstream, which further disseminates infection.

Answer 159

* **Staph epidermidis**: prosthetic devices, IV caths * **Strep mutans & sanguinis**: dental plaques * **Pseudomonas aeruginosa**: cystic fibrosis pneumonia, contact lenses * **Viridans group strep**: endocarditis * **Nontypable H. influenza**: otitis media

Answer 160

Leads to a decrease in RPF and a decrease in GFR. Compensatory activation of the RAAS in response to hypotension leads to constriction of the efferent arteriole to matinain GFR. The FF (GF/RPF) increases in hypovolemia as RPF drops proportionately more than GFR d/t the above compensatory mechanism.

Answer 161

Prolonged, burning substernal pain and ST segment elevation in leads I and V3-V6 is strongly suggestive of anterolateral LV infarction. Consequences of LV infarction include LV failure, cardiogenic acute pulmonary edema, pulm venous HTN (congestion), and transudate of plasma into the lung interstitum and alveoli.

Answer 162

Produce contralateral homonymous hemianopia and a relative afferent pupillary defect (Marcus Gunn pupil) in the contralateral eye.

Answer 163

The afferent limb of the light reflex pathway is the optic nerve; the efferent limb is the parasympathetic fibers of the oculomoter nerve. When an optic nerve is damaged, light in that eye will cause neither pupil to constrict (the nerve can't sense the light). However, light in the contralateral eye will cause both pupils to constrict (becuase the motor pathways are intact). This a common AE of multiple sclerosis.

Answer 164

Acute intermittent porphyria: AD, caused by porphobilinogen deaminase deficeincy. May present wtih abd pain and vomitting, peripheral neuropahty, neuropsychological sx, and reddish-brown urine (NO photosensitity). Treatmetn consists of IV glucose or heme preparations, which downregulate ALA synthetase activity (rate-limiting enzyme of heme synthesis).

Answer 165

Coccidioides immitis: dimorphic fungus; spherules are the tissue form, but exists in teh enviornment in the form of mold (hyphae). Can cause lung disease in immunocompetent and disseminated disease in immunocompromised.

Answer 166

***Blastomycosis dermatitidis***: may be asymptomatic in an immunocompotent person, but it can also cause a flu-like illness, or cough with sputum production, hemoptysis, dyspnea, and pleuritic chest pain. Pulmonary blasto is characterized by **granuloma** formation. KOH sputum stain shows round yeast (with single **broud-based bud**) with **thick, double refractive walls**. Tx: itraconazole.

Answer 167

All block D2 receptors (increased cAMP) _Low-potency_: more likely to cause non-neurologic side effects such as sedation (histaminergic blockade), orthostatic hypotension (alpha-1 blockade), and anticholinergic SE (cholinergic blockade) **C**hlorpromazine, **Th**ioridazine (**C**heating **Th**ieves are **low**) _High potency_: extrapyramidal sx. **T**rifluoperazine, **F**luphenazine, **H**aloperidol (**T**ry to **F**ly **High**) Remember the atypicals include: "It's **atypical** for **o**ld **clos**ets to **quiet**ly **risper **from **A **to **Z**" **Ol**anzapine, **Cloz**apine, **Queti**apine, **Risper**idone, **A**ripiprazole, **Z**iprasidone.

Answer 168

**RNA polymerase 1** which forms rRNA. In addition to transcribing rRNA, the nucleolus is also involved in maturation adn assembly of ribosomal subunits.

Answer 169

Excessive bleeding is d/t accumulation of **uremic toxins** in circulation which impair platelet aggregation and adhesion, resulting in a **qualitative platelet disroder** characterized by **prolonged bleeding** with normal platelet count, PT and PTT. Can be improved with dialysis.

Answer 170

There is an optimal breathing rate at which teh total work of breathing is minimized. For patients wtih stiff lungs (increased elastic resistance), the work of breathing is minimzed when the RR is high and TV is low. Therefore, rapid and shallow breaths are favored in diseases that increase elastic resistance (e.g. pulmonary fibrosis, pulm edema, ARDS). In contrast, in diseases that cause high airflow resistance (e.g. asthma, COPD), patients breathe at a lower rate (slow, deep breaths) in order to minimize the work of breathing. 8260

Answer 171

_Cherry_: small, red, cutaneous papules common in aging adults. They do not regres spontaneously and typically increase in number with age. LM shows proliferation of capillaries and post-capillary venules in the papillary dermis. _Superficial (infantile, capillary, strawberry)_: appear in first few weeks of life. They initally grow rapidly and then freuqently regress spontaneously by late childhood.

Answer 172

Immunocompetent T-cells within the donor tissue recognize host MHC antigens as foreign and attack them. Both donor CD4+ and CD8+ cells participate in destroying host cells. Skin, liver and GI tract are generally affected more severely. Acute GVHD develosp within 1 week of the transplant. Liver damage manifests with jaundice and increaed levels of ALT, AST, ALP, and bilirubin. GI tract involvement causes diarrhea, intestinal bleeding, abdominal cramping and/or ileus. In severe cases, there may be skin desquamation.

Answer 173

Occur b/w an AA and an alpha-keto acid (e.g. oxaloacetate). The amino group from the amino acid is tranffered to the alpha-keto acid, and the alpha-keto acid in turn becomes an amino acid. **Pyridoxal phopshate (Vitamin B6)** serves as a cofactor in AA transamination and in decarboxylation reactions.

Answer 174

Described as "serum sickness-like" during the prodromal period, with patients experiencing malaise, fever, skin rash, pruritus, LAD, and joint pain. Anorexia, nausea, jaundice, and RUQ pain may ensue. Labs: ALT \> AST, followed by rises in bilirubin and ALP.

Answer 175

**Virchow's node** (metastasis to left supraclavicular sentinel node), **Sister Mary Joseph nodule** (metastasis to periumbilical region), or as **Krukenberg tumor of the ovary** (mucin-producing, signet-ring neoplastic cells in the ovarian stroma)

Answer 176

Pompe Disease (i.e. glycogen storage disease type II), which is due to deficeincy of the enzyme **alpha 1,4-glucosidase (acid maltase)**

Answer 177

As opposed to serotonin syndrome, the NMS is distinguished by an abscence of myoclonus and by the presence of rigidity. Dopamine agonists (bromocriptine) and/or direct muscle relaxants (dantrolene) have been used to decrease mortality associated wtih NMS. For NMS think **FEVER**: **F**ever, **E**ncephalopathy, **V**itals unstable, **E**nzymes increased, **R**igidity of muscles

Answer 178

Phenelzine (MAOI)

Answer 179

"Pease Note All Drugs that Can Possibly Scar Renals" Penicillin derivatives, NSAIDs, Allopurinol, sulfa-derived Diuretics, Cephalosporins, PPIs, Sulfonamide antibiotics, Sulfasalazine, Rifampin Sx: fever, maculopapular rash and sx of acute renal failure 1-3w after beginning treatment with a b-lactam ABX are highly suggestive of AIN. Peripheral eosinophilia, eosinophiluria, IgE are important clues; granuloma formation may be observed.

Answer 180

Midgut returns to the abdominal cavity at 10th week of fetal life, simultaneosuly completing a 270 degree turn counterclockwise around the SMA. If this process is abnormal --\> intestinal malrotation; cecum is found in the RUQ, fixed with fibrous bands to the second portion of the duodenum. The entire midgut is fixed to the SMA. **Intestinal obstruction** (d/t compression of the duodenum by the adhesive bands; bilious vomitting during first days of life) and **migut volvulus** (intestinal ischemia d/t twisting around the blood vessels)

Answer 181

Decreased levels of ACh in the nucleus basalis of Meynert (participates in memory and cognition) and hippocampus (formation of new memories). Diminished activity of choline acetyltransferase in these cerebral structures is the cuase.

Answer 182

S. pyogenes

Answer 183

HSV-1 (enveloped, dsDNA virus)

Answer 184

The growth of thick, ropelike cords of mycobacterial organisms in a twisted, "serpentine" pattern is consistent with the presence of **cord factor**, which is a mycoside. The presence of cord factor correlates with **virulence**; mycobacteria that do not possess cord factor are not able to cause disease. More specifically, cord factor is responsible for inactivating neutrophils, damaging mitochondria, and inducing release of TNF.

Answer 185

Bone-specific alkaline phosphatase reflects osteoblastic activity. Tartate-resistant acid phosphatase, urinary hydroxyproline, and urinary deoxypridinoline reflect osteoclastic activity; urinary deoxypyridinoline is hte most reliable of the three.

Answer 186

Pancreatic glucagonoma

Answer 187

Signs of NE extravasation and resulting vasoconstriction. Tissue necrosis is best prevented by local injection of an alpha1 blocking drug, such as **phentolamine **--\> lead to vasodilation, thus counteracting the alpha1 receptor mediated vasoconstriction of NE.

Answer 188

Clinical manifestations: arise from enterochromaffin (endocrine) cells of the intestinal mucosa, which produce vasoactive substances such as serotonin (5-HT), bradykinin, and prostaglandins. * Skin: **flushing**, telangiectasias, cyanosis * GI: **watery diarrhea**, cramping * Pulm: **bronchospasm**, dyspnea, wheezing * Cardiac: valvular fibrous plaques (right \> left) Diagnosis: elevated 24hh urinary 5-HIAA. Treatment: Ocreotide

Answer 189

The minimal infectious dose for cholera infection is usually quite high, given that its very sensitive to gastric acidity. Any condition that decreases acidity (or increases gastric pH), such as antacid use (e.g. long-term PPI therapy with **omeprazole**) or other conditions causing **achlorhydria** (e.g. **gastritis**), will lower the minimum infectious dose of V. cholerae. ## Footnote NOTE: can be isolated from stool specimens by growing on highly alkaline selective media. It is a comma-shaped, oxidase-positive, gram-negative bacillus

Answer 190

Non-glucose monosacchardies (e.g. galactose, mannose, fructose) enter the glycolytic pathway at different points as intermediates of glycolysis. Dietary **fructuose** is phosphorylated in the liver to F1P and is rapidly metabolized because it **bypasses phosphofructokinase (PFK1)**, the *major rate-limiting enzyme of glycolysis*. Other sugars (e.g. glucose, galactose, mannose) enter glycolysis prior to PFK1 and as a result are metabolized more slowly.

Answer 191

The lepromin skin test will be **positive** in patients with **tuberculoid leprosy** as they exhibit a strong **CD4+ TH1 cell-mediated immune response** (IL-2, IFNy, and IL-12) to M. leprae. Patients with **lepromatous leprosy** will test **negative** due to thier **weak TH1 cell-medaited immune response**. Patients with lepromatous leprosy show extensive accumulation of acid-fast bacilli within macrophages of affected tissues and often a TH2 cytokine profile. NOTE: In TL, macrophages are activated and kill M leprae organisms, thereby limiting disease extent. However, this localized inflammation damages the skin and cutaneous nerves leading to developmetn of a small number of hypopigmented, well-demarcated plaques with decreased sensation. In comparison, LL is disseminated, with more numerous poorly demarcated plaques, leonine facies and degeneration/loss of nose adn digits.

Answer 192

Atropine, TCA (e.g. amitriptyline), H1 receptor antagonists (e.g. diphenhydramine), neuroleptics, and antiparkinsonian drugs.

Answer 193

Vascular endothelium plays an important role in vasodilation mediated by ACh, bradyinin, serotonin, substance P, and shear force. These stimuli activate specific membrane receptors on endothelial cells, leading to an increase in cytoplasmic calcium levels. This causes activation of endothelial nitric oxide synthase (eNOS), which synthesizes nitric oxide from **arginine**, NADPH, and O2. Nitric oxxide then diffuses into adjacent smooth muscle cells, where it activates GC and increases cGMP --\> activate PKG --\> reduction in cytosolic calcium levels and relaxation of vascular smooth muscle cells.

Answer 194

Both ventricular hypetrophy and volume overload cause release of both ANP and BNP from the ventricular myocyte to facilitate natriuresis and diuresis. BNP can also be used for the diagnosis of CHF (both systolic and diastolic)

Answer 195

Gout occurs with increased frequency in patients wtih activating mutations involving PPRP synthetase due to increased production and degradation of purines. This enzyme is responsible for the production of activated ribose necessary for de novo synthesis of purine and pyrimidine nucleotides.

Answer 196

**Clear cell carcinoma** is the most common subtype and is composed of large, rounded or polygonal cells with clear cytoplasm; nuclei can be either eccentric or central. Appears clear d/t high glycogen adn lipid content of the tumor; appears golden-yellow on macroscopic exam. The classic triad of **hematuria, flank pain, and palpable mass** occurs in a minority of patients. Non-specific symptoms and **paraneoplastic syndromes** (erythrocytosis and polycythemia d/t secretion of EPO --\> elevated hematocrit; PTHrP --\> hypercalcemia) are more common. These tumors are often detected incidently at an advanced stage, and the lung is the most common site for mets.

Answer 197

**_Klinefelter_**: 47, XXY is characterized by primary hypogonadism (elevated FSH and LH, low testosterone); long lower extremities; small, firm testes; and azoospermia. ## Footnote Progressive destruction and hyalinization of seminiferous tubles cause testes to be small and firm. **Serum inhibin levels are decreased** d/t sertolic cell damage; leydig cells are usually dysfunction as well casuing **reduced testosterone levels**. Loss of feedback inhibition leads to **elevated FSH and LH**. Can also develop high estrogen levesl and gynecomastia d/t increased aromatase (stimulated by gonadotropin excess)

Answer 198

Irritability, poor feeding, increased head circumference and enlarged ventricles on CT. Long-term sequelae include lower extremity spasticity due to stretching of the periventricular pyramidal tracts, visual distrubances, and learnign disabilities. The cause is usually imapired CSF outflow d/t congenital abnormalities like Type II Arnold-Chiari malformations, hereditary aqueductal stenosis, and prenatal infections (e.g. toxo).

Answer 199

Although resistance within the trachea and mainstem bronchi is realtively high, it increases in the medium-sized bronchi b/c of highly turbulent airflow. Resistance drops in small bronchi and bronchioles becuase the summated cross-sectional area massively increases. This slows airflow velocity, allowing low-resistance laminar airflow to predominate in airways \<2mm in diameter. Resistance: Medium sized bronchi \> Trachea \> Bronchioles \> Terminal bronchioles

Answer 200

**Mean corpuscular hemoglobin concentration (MCHC) is increased** d/t mild dehydration of the RBC. Markers of hemolysis are often evident and include elevated LDH, reticulocytosis, and decreased haptoglobin. Will show **increase osmotic fragility on acidified glycerol lysis test** and **abnormal eosin-5-maleimide binding test. **

Answer 201

**Amiodarone** (and other class III and class IA antiarrhythmic agents) cause lengthening of the cardiac action potential, which manifests as QT interaval prolongation on ECG. In contrast to other drugs, QT prolongation caused by amiodarone is associated wtih very low risk of TDP and other proarrhythmias.

Answer 202

Several mitochondrial enzymes including **PDH** (decreased function of PDH will increase conversion of pyruvate to lactate by enzyme lactate dehydrogenase in an effort to regenerate NAD+, and this will eventually lead to **lactic acidosis**), **alpha-ketoglutarate DH** and **branched-chain ketoacid DH** (Deficeincy results in maple syrup urine disease)

Answer 203

**BALSA**: Bromocriptine, Amantadine, Levodopa (with carbidopa), Selegiline (and COMT inhibitors), Antimuscarinics. ## Footnote _Dopamine agonits_: Bromocriptine and pergolide (ergot compounds) pramipexole and ropinirole (nonergot) _Increase dopamine_: Amantadine (may increase DA release); also used as an antiviral against influenza A and rubella; toxicity = ataxia. L-dopa/carbidopa (converted to dopamine in CNS; carbidopopa is a peripheral dopa decarboxylase inhibitior) _Prevent DA breakdown_: Selegiline (selective MAO type B inhibitor); entacapone, tolcapone (COMT inhibitors; prevent L-dopa degradation and increase DA availbility; only used in combination with levodopa). _Curb excess cholinergic activitiy_: Benzotropine (Antimuscrinic; improves tremor and rigidity but has little effect on bradykinesia).

Answer 204

Suggestive of wet beriberi (thiamine deficeincy). NOTE: Dry beriberi describes a symmetrical peripheral neruopathy accompanied by sensory and motor impairements, especially of the distal extremtieis. Wet beriberi includes this neruopathy + cardiac involvement.

Answer 205

Atheroembolic renal disease. LM shows cholesterol emboli obstructing renal arteiroles. During this procedure, cholesterol-containing debris gets pushed form larger arteries and lodges in smaller vesels, causing ischemia of hte correspondign organs and tissues.

Answer 206

DRESS syndrome typically occurs 2-8 weeks after exposure to high-risk drugs such as **anticonvulsants** (eg phenytoin, carbamazepine), **allopurinol**, **sulfonamides** (eg sulfasalazine), and **ABX** (eg minocycline, vancomycin). Patients develop fever, generalized LAD, facial edema, diffuse skin rash, eosinophilia, and internal organ dysfucntionn. _Labs_: **eosinophilia**, atypical lymphocytosis, and elevated serum alanine transaminase

Answer 207

LAD can represent inflammatory changes within teh lymph node (reactive hyperplasia) or malignatn transformation. Benign lymph node enlargement in response to antigen stimulation is associated with a polyclonal proliferation of lymphocytes. A **monoclonal lymphocytic proliferation is strong evidence of malignancy.** When examining the **rearrangemetn of TCR genes,** if a single allele for the V region of the TCR predominatnes in a lymphcotyic population than monoclonal proliferation is suspected.

Answer 208

Propionyl CoA is derived from **branched chain AAs (valine, isoleucine)**, **methionine**, **threonine**, **odd-numbered FAs,** and **cholesterol side chains**. Congential deficieincy of **propionyl CoA carboxylase,** the enzyme responsible for conversion of propionyl CoA to methylmalonyl CoA, leads to developmetn of propionic acidemia. Propionic acidemia is characterized by poor feeding, vomitting, hypotonia, lethary, dehydration and anion gap acidosis.

Answer 209

To ensure that all pregnant women have been vacinated with the tetanus toxoid, to allow transfer of protective IgG antitoxin antibodies across the placenta to the fetus.