Uworld14

Question 1

Beta-2 receptors can be found?

Answer 1

Although beta-2 receptors are predominany in the lungs and vasculature, they are also found on all cell membreanes, including those of the uterus.

Stimulation of uterine receptors results in smooth muscle relaxation (tocolysis), while stimulation of sodium-potassium ATPase pumps can result in hypokalemia

Question 2

MOA of nonbenzodiazepine meds (zolpidem, zaleplon, eszopiclone)

Answer 2

stimulate specific subtypes of GABAa receptors.

As a result, nonbenzodiazepines are primarily hypnotics and do not produce the anxiolytic, muscle relaxant, or anticonvulsant effects associated with benzodiazepines

Question 3

Histopath for melanoma

Answer 3

Melanoma is a highly aggressive malignancy that often metastasizes early in the disease course.

Patients may be asymptomatic for years prior to onset of metastatic manifestations.

Diagnosis is generally made when a histopathologic sample shows cellular atypia with cells containing brown pigment (melanin granules); immunostaining for melanocytic markers (S-100, HMB-45) is generally positive

Question 4

What is neonatal abstinence syndrome due to?

Answer 4

maternal opioid use causes neurologic, gastrointestinal, and autonomic symptoms; irritability, tremors, diarrhea, and sneezing are classic findings.

Patients with symptoms refractory to nonpharmacologic therapy warrant opioid replacement (morphine)

Question 5

What is seen in patients with severe iron def anemia?

Answer 5

typically have evidence of hypochromic, microcytic erythrocytes on peripheral blood smear with poikilocytosis.

Labs reveal low red blood cell count, low hepcidin, and high transferrin.

Although erythropoietin is markedly elevated in iron def anemia, there is not enough iron to efficiently generate erythrocytes; therefore reticulocyte count is low

Question 6

mineralocorticoid receptor antagonists (spironolactone, eplerenone) improve survival in patients with?

Answer 6

congestive heart failure and reduced left ventricular ejection fraction.

They should not be used in patients with hyperkalemia or renal failure

Question 7

What is seen in radial nerve injury?

Answer 7

Radial nerve injury can occur with repetitive pressure/trauma at the axilla (eg, improperly fitted crutches)

Findings: weakness of the forearm, hand, and fingers extensors (wrist drop, absent triceps reflex) and sensory loss over the posterior arm and forearm, dorsolateral hand, and dorsal thumb. More distal lesions spare the triceps brachii

Question 8

What is diabetic autonomic neuropathy?

Answer 8

Prolonged hyperglycemia in diabetes mellitus can injure the parasympathetic and sympathetic nervous system, resulting in diabetic autonomic neuropathy.

This can lead to disordered small bowel and colonic motility and increased intestinal secretions, resulting in secretory-like diarrhea (eg, fasting bowel movements)

Question 9

Stapedius muscle is innervated by?

Answer 9

the stapedius nerve (a branch of the facial nerve).

Paralysis of the stapedius muscle results in hyperacusis (increased sensitivity to sound)

Question 10

What causes hypokalemia resulting from the intracellular shift of potassium?

Answer 10

Betaa-adrenergic hyperactivity (beta-2 agonists, endogenous epinephrine release), increase insulin levels, elevated extracellular pH, or increased cell production (eg, acute leukemia)

Question 11

Functions of glucagon

Answer 11

Glucagon increases glucose by increasing hepatic glycogenolysis and gluconeogenesis.

Stimulates insulin secretion from the pancreas.

Unlike epinephrine, glucagon has an insignificant effect on glucose homeostasis in the skeletal muscle, adipose tissue, and renal cortex.

Question 12

What are the most common findings with posterior cerebral artery stroke?

Answer 12

Contralateral homonymous hemianopia with macular sparing due to damage to the occipital cortex and contralateral hemisensory loss due to damage to the thalamus

Question 13

Chronic kidney diseases causes disordered mineralization and bone metabolism that usually presents with?

Answer 13

Hyperphosphatemia, secondary hyperparathyroidism, and decreased calcitriol levels.

Patients can be asymptomatic or develop weakness, bone pain, and fractures.

Question 14

How does estrogen effect thyroid?

Answer 14

An increase in estrogen activity (pregnancy, postmenopausal estrogen replacement therapy), increases the level of thyroxine-binding globulin.

This leads to an increase in total thyroid hormone levels, but feedback control maintains normal levels of free (biologically active) thyroid hormone

Question 15

What is Campylobacter gastroenteritis?

Answer 15

Typically acquire from contaminated poultry or domesticated animals (eg, dogs), causes an inflammatory diarrhea characterized by fecal leukocytes and red blood cells.

Manifestations include fever, abdomina pain, and diarrhea that may be grossly bloody

Question 16

What happens when carbon monoxide binds heme?

Answer 16

Carbon monoxide binds heme iron in hemoglobin with an affinity much greater than oxygen, generating carboxyhemoglobin.

Remaining binding sites on carboxyhemoglobin have an increased affinity for oxygen that causes the oxygen dissociation curve to shift to the left, impeding oxygen delivery to tissues

Question 17

In a young Caucasian patient, the combo of recurrent respiratory infections with Pseudomonas aeruginosa, diarrhea, and failure to thrive suggests a diagnosis of?

Answer 17

Cystic fibrosis.CF causes steatorrhea and failure to thrive due to malabsorption secondary to pancreatic insufficiency, which can be corrected by pancreatic enzyme supplementation.

Question 18

Gastroesophageal reflex disease is caused primarily by?

Answer 18

gastroesophageal junction incompetence and can be associated with extraesophageal symptoms (eg, nocturnal cough) in the absence of heartburn (“silent GERD”).

Acidic gastric contents irritate the esophageal mucosa, leading to characteristics histologic findings that include basal zone hyperplasia, elongation of the lamina propria papillae, and scattered eosinophils

Question 19

DiGeorge syndrome results from?

Answer 19

Maldevelopment of the 3rd (inferior parathyroid and thymus) and 4th (superior parathyroid) pharyneal/branchial pouches.

Subsequent parathyroid and thymic hypoplasia results in hypocalcemia and T cell deficiency

Question 20

What is X-linked agammaglobinemia?

Answer 20

an immunodeficiency characterized by low circulating B lymphocytes and immunoglobins, should be suspected in an infant with severe, life-threatening enteroviral infection.

Question 21

Impaired tetrahydrobiopterin (BH4) synthesis inhibits?

Answer 21

conversion of phenylalanine to tyrosin because BH4 is an essential cofactor of phenylalanine hydroxylase.

BH4 is also a cofactor for hydroxylase enzymes in the synthesis of essential neurotransmitters (dopamine, serotonin)

Question 22

Preparation stage in the stages of change model

Answer 22

In the transtherorectical stages of change model, the preparation stage represents the stage in which the individual has committed to behavioral change and is considering change strategies but has not determined or instituted a specific course of action.

Individuals at this stage may be weighing options and seeking additional support.

Question 23

Acute benzodiazepine (eg alprazolam, lorazepam) overdose causes what to the respiratory system?

Answer 23

causes central respiratory depression with hypoventilation.

The hypoventilation leads to CO2 retention and acute respiratory acidosis.

It also decreases the PAO2, leading directly to hypoxemia (PaO2 <75mmHg). The efficiency of gas transfer between the lungs and the circulation is intact; therefore, a normal alveolar-arterial O2 gradient (eg <15mmHg) is expected.

Question 24

What is at the 3’ end of tRNA?

Answer 24

Transfer RNA (tRNA) is a small, noncoding form of RNA that contains chemically modified bases (eg dihydrouridine, ribothymidine, pseudouridine)

tRNA has a CCA sequence at its 3’end that is used as a recognition sequence by proteins. The 3’terminal hydroxyl group of the CCA tail serves as the amino binding site.

Question 25

Elevated cholesterol concentrations increase the likelihood of?

Answer 25

cholesterol precipitation and gallstone formation. High levels of bile salts and phosphatidylcholine increase cholesterol solubility and decrease the risk of gallstones

Question 26

How does radiation damage DNA?

Answer 26

Exposure to ionizing radiation, including therapeutic and palliative radiation therapy, induces DNA damage through DNA double strand fractures and the formation of oxygen free radicals.

Question 27

Metformin MOA

Answer 27

lowers blood glucose by reducing hepatic gluconeogenesis and increasing insulin-dependent peripheral glucose uptake. Lactic acidosis is a rare complicaton of metformin therapy; the risk is increased in patients with underlying renal insufficiency.

Question 28

What is the most important risk factor for catheter-associated urinary tract infection?

Answer 28

Duration of catheterization (esp >48 hour). Prevention strategies include avoiding inappropriate catheterization (eg, placing catheter solely due to incontinence) and promptly removing the catheter when it is no longer needed.

Question 29

What are signs of bulimia nervosa?

Answer 29

Characterized by episodes of binge eating and compensatory weight reduction behaviors. Signs of self induced vomitting include hypokalemia, metabolic alkalosis, parotid gland enlargement, dorsal hand calluses, and dental erosion

Question 30

Function of posterior cruciate ligament

Answer 30

Prevents posterior displacement of the tibia relative to the femur It originates from the anterolateral surface of the medial femoral condyle and inserts into the posterior intercondylar area of the tibia. Its integrity can be tested in the clinical setting by using the posterior drawer test

Question 31

What is placenta percreta?

Answer 31

placental invasion through the myometrium and uterine serosa and into extrauterine structures. An anterior placenta percreta is most likely to invade structures anterior to the uterus such as the bladder.

Question 32

Function of IgA protease

Answer 32

IgA protease is produced by Neisseria meningitidis, N gonorrhoeae, Strep pneumoniae, and Haemophilus influenza This enzyme cleaves secretory IgA at its hinge region, rendering it ineffective. Secretory IgA exists on mucosal surfaces and in secretions and acts to bind and inhibit the action of pili as well as other cell surface antigens that normally mediate mucosal adherence and subsequent penetration

Question 33

Side effect of isoniazid

Answer 33

Isoniazid is structurally similar to pyridoxine (vitamin B6) and competes for binding sites on pyridoxine-dependent enzymes. This leads to decreased synthesis of certain neurotransmitters, which may result in peripheral neuropathy. Management involves pyridoxine supplementation

Question 34

MOA of dobutamine

Answer 34

beta adrenergic agonist with predominant activity on beta-1 receptors It causes an increase in heart rate and cardiac contractility, leading to an increase in myocardial oxygen consumption

Question 35

What is the cause of recurrent respiratory papillomatosis?

Answer 35

Vertical direct transmission of human papillomavirus subtypes 6 and 11 can cause recurrent respiratory papillomatosis, which results in wart like growths most commonly on the true vocal cords

Question 36

MOA of phenylephrine

Answer 36

Increases blood pressure via an alpha-1 receptor mediated increased in inositol triphosphate in vascular smooth muscle cells. The abrupt increase in blood pressure triggers a reflexive increase in parasympathetic activity while decreasing sympathetic outflow. This leads to decreased cyclic AMP activity in the heart (mediated by beta-1 adrenergic and muscarinic-2 receptors), which decreases heart rate and myocardial contractility. The reduction in heart rate is driven in part by decreased inward calcium current in sinoatrial cells

Question 37

What species requires a low infectious dose to cause gastrointestinal disease?

Answer 37

Shigella. The mechanism primarily involves their ability to survive in the acidic (low pH) gastric environment

Question 38

Function of nuclear factor kappa B/RANK-ligand interaction

Answer 38

Essential for the formation and differentiation of osteoclasts.

Question 39

What is osteoprotegerin?

Answer 39

Osteoprotegerin blocks binding of RANK-L to RANK and reduces formation of mature osteoclasts, leading to decreased bone resorption. Denosumab is a monoclonal antibody used in the treatment of postmenopausal osteoporosis that works in a manner similar to OPG.

Question 40

Chimeric antigen receptor (CAR) T cell therapy involves?

Answer 40

Extracting T cells from a patient with a malignancy, inserting a CAR gene against a protein overexpressed by the malignancy, and then reinfusing the modified T cells back into the patient. CAR T cell therapy against CD19 is used to treat B cell malignancy because CD19 is expressed only by B cells

Question 41

What is seen in Fanconi syndrome?

Answer 41

Defects in either the proximal or distal convoluted tubule (eg, bicarbonate loss, acid retention) can result in a normal anion gap metabolic acidosis. However, the proximal tubule is responsible for resorption of glucose, amino acids, and phosphate in addition to bicarbonate; therefore, generalized proximal tubular dysfunction (Fanconi syndrome) can also cause failure to thrive, glucosuria, and rickets.

Question 42

Common side effects of ACE inhibitors (-pril)

Answer 42

decreased glomerular filtration rate (GFR), hyperkalemia, and cough, Angioedema is a rare, but life threatening side effect

Question 43

Renal cell carcinoma tends to invade?

Answer 43

the renal vein; inferior vena cava obstruction can occur by intraluminal extension of the tumor. Obstruction of the IVC produces symmetric bilateral lower extremity edema, often associated with prominent development of venous collaterals in the abdominal wall.

Question 44

Renal cell carcinoma causes a variety of paraneoplastic syndromes including?

Answer 44

erythrocytosis (due to excessive erythropoietin production) and hypercalcemia (due to parathyroid hormone-related peptide)

Question 45

How does positive end expiratory pressure help treat acute respiratory distress syndrome?

Answer 45

By opening collapsed alveoli to reduce intrapulmonary shunting and increase functional residual capacity. The increased FRC decreased ventilation-perfusion mismatching and increases the oxygen reserves in the lungs

Question 46

What are the causes of acute pancreatitis?

Answer 46

80%: gallstone and chronic alcoholism some other less common causes are: inhertied or acquired hypertriglyceridemia if the serum level of triglycerides exceeds 1000 mg/dL

Question 47

What is hypertrophic osteoarthropathy?

Answer 47

Characterized by abnormal growth of new bone and presents with digital clubbing, painful arthropathy, periostosis of long bones, and joint effusions. It commonly occurs in the setting of pulmonary malignancy, primarily adenocarcinoma, other lung disorders (eg, cystic fibrosis, bronchiectasis) and cyanotic heart disease

Question 48

Tetralogy of Fallot results from?

Answer 48

anterior and cephalic deviation of the infundibular septum during embryologic development, resulting in a malaligned ventricular septal defect (VSD) wtih an overriding aorta. As a result, the patient has right ventricular outflow obstruction (resulting in a systolic murmur) and squats to increase the peripheral systemic vascular resistance (afterload) and decrease right to left shunting across the VSD

Question 49

Moderate to heavy alcohol consumption increases the risk of gout due to?

Answer 49

increased production and decreased excretion of uric acid. Beer in particular can trigger a gout flare, as many beers contain significant quantities of absorbable purines that lead to increased blood uric acid levels

Question 50

Which drugs inhibit dihydrofolate reductase?

Answer 50

Trimethoprim, methotrexate, and pyrimethamine. ; Trimethoprim restricts bacterial growth through this process, and works particularly well in conjunction with sulfonamide, which inhibits an earlier step in the bacterial folic acid pathway

Question 51

There is an accumulation of what in Niemann-Pick disease?

Answer 51

shingomyelinase deficiency causes accumulation of the lipid sphingomyelin CF: hepatosplenomegaly, neurologic regression, and a cherry-red macular spot in infancy

Question 52

What is projection?

Answer 52

an immature defense mechanism involving the misattribution of one's unacceptable feelings or thoughts to another person who does not actually have them

Question 53

The Haemophilus influenzae serotype b vaccine consists of a capsular polysaccharide conjugated to a carrier protein (tetanus toxoid) protein or outer membrane protein of Neisseria meningitidis). Protein conjugation causes?

Answer 53

a T cell mediated immune response leading to long term immunity through production of memory B-lymphocytes

Question 54

What is the primary virulence factor of uropathogenic E coli?

Answer 54

E coli is the most common cause of UTIs. Primary virulence factor of uropathogenic E coli are P fimbriae (pili) which allow the bacteria to adhere to uroepithelial cells and infect the bladder, ureters, and kidneys

Question 55

Restrictive lung disease values on pulmonary function testing

Answer 55

Pulmonary function testing involves having the patient inhale completely and then forcefully exhale as much air as possible as quickly as possible. Restrictive lung disease causes reduced total volume of air expelled (ie, reduced forced vital capacity (FCV), reduced volume of air expelled in 1 second (ie, reduced forced expiratory volume in 1 second (FEV1), and a normal or sometimes increased FEV1/FVC ratio

Question 56

What is acne caused by?

Answer 56

characterized by the obstruction of pilosebaceous follicles (ie, comedones) due to hyperkeratinization and excessive sebum accumulation. Androgens stimulate production of sebum, which serves as a nutrient source for Cutibacterium acnes. Within the follicles, C acnes proliferation triggers an inflammatory response, resulting in formation of red papules and pustules.

Question 57

MOA of nitrates

Answer 57

Nitrates (via conversion to nitric oxide) activate guanylate cyclase and increase intracellular levels of cyclic guanosine monophosphate (cGMP) Increased levels of cGMP lead to myosin light chain dephosphorylation, resulting in vascular smooth muscle relaxation

Question 58

Antibody-drug conjugates improve drug efficacy and minimize toxicity by?

Answer 58

allowing conventional chemotherapeutic agents (eg, cisplatin) to selectively target and kill cancer cells while sparing healthy cells (ie, targeted delivery)

Question 59

With maternal blood types A or B, hemolytic disease of the fetus and newborn very rarely occurs because?

Answer 59

maternal antibodies (anti-A or anti-B) are of the IgM type and cannot cross the placenta. In contrast, mothers with blood type O also produce IgG antibodies (anti-A and anti-B), which can cross the placenta and cause fetal hemolysis

Question 60

What hormones use this pathway: protein kinase A is responsible for the intracellular effects of the G protein mediated adenylate cyclase second messenger system?

Answer 60

TSH, glucagon, and PTH receptors

Question 61

Excessive activation of the glutamate NMDA receptor causes?

Answer 61

excitotoxic neuronal death through uncontrolled calcium influx. At the hyperpolarized resting membrane potential, the NMDA receptor is blocked by a magnesium plug, which is released by non-NMDA-mediated depolarization.

Question 62

Which DNA polymerase has 5'-3' exonuclease activity?

Answer 62

Only DNA pol I has 5'-3' exonuclease activity, which is used to remove the RNA primer synthesized by RNA primase

Question 63

Function of 3'-5' exonuclease activity?

Answer 63

All prokaryotic DNA pol (I, II, III) remove mismatched nucleotides via their 3'-5' exonuclease (proofreading) activity

Question 64

What is seen in tibial nerve injury at the level of the popliteal fossa?

Answer 64

The tibial nerve may be injured at the level of the popliteal fossa due to deep penetrating trauma or knee surgery. Patients typically have weakness on foot plantarflexion, foot inversion, and toe flexion, with sensory loss over the sole

Question 65

How is Parkinson disease typically treated?

Answer 65

Parkinson disease is typically treated with levodopa (immediate precursor of dopamine), which crosses the blood-brain barrier. Levodopa is adminstered with DOPA decarboxylase inhibitors (eg carbidopa) and sometimes catechol O-methyltransferase inhibitors (eg, entacapone) to reduce the peripheral metabolism of levodopa, resulting in increased levodopa bioavailability within the brain

Question 66

Legionella pneumophila contaminates what?

Answer 66

commonly contaminates natural bodies of water, municipal water supplies, and water based cooling systems. The organism is inhaled in aerosolized water and establishes infection via the pulmonary route. Diagnosis is generally made by urine antigen testing, silver stain, or culture on buffered charcoal yeast extract agar supplemented with L-cysteine and iron

Question 67

What causes autosplenectomy in sickle cell patients ?

Answer 67

In patients with sickle cell disease, repetitive splenic infarctions caused by microvessel occlusion result in a small, firm splenic remnant (ie. autosplenectomy)

Question 68

Cocaine withdrawal is characterized by?

Answer 68

the development of acute depression accompanied by fatigue, hypersomnia, hyperphagia, and vivid dreams

Question 69

Changes in membrane potential occur in response to?

Answer 69

changes in neuronal permeability to various cellular ions. The more permeable the membrane becomes for a cellular ion, the more that ion's equilibrium potential contributes to the total membrane potential

Question 70

What is an interscalene nerve block?

Answer 70

An interscalene nerve block is used to provide anesthesia for the shoulder and upper arm by anesthetizing the upper brachial plexus (C5-C7) as it passes between the anterior and middle scalene muscles. Anesthetic also transverses along the interscalene sheath, frequently resulting in transient ipsilateral diaphragmatic paralysis due to involvement of the phrenic nerve roots (C3-C5)

Question 71

What can botulinum toxin be used for?

Answer 71

Clostridium botulinum is a spore forming, G+, anaerobic bacillus that synthesizes botulinum toxin, which prevents the presynaptic release of acetylcholine from the nerve terminal at the neuromuscular junction. Botulinum toxin can be used to treat focal dystonia and other disorders of abnormal muscle contraction

Question 72

Brachiocephalic vein drains which veins?

Answer 72

The brachiocephalic vein drains the ipsilateral jugular and subclavian veins. The bilateral brachiocephalic veins combine to form the superior vena cava. Brachiocephalic vein obstruction causes symptoms similar to those seen in SVC syndrome, but only on one side of the body.

Question 73

Antipsychotic meds block which pathway in the brain?

Answer 73

blocking dopamine-2 receptors in the mesolimbic dopamine pathway.

Question 74

Blocking which pathway can cause galactorrhea and amenorrhea?

Answer 74

Dopamine-2 receptor blockade in the tuberoinfundibular pathway

Question 75

What is seen in minimal change disease?

Answer 75

Minimal change disease is the most common cause of nephrotic syndrome in children. Classic manifestations incluce proteinuria, hypoalbuminemia, and edema that are usually reversible with corticosteroids. The principal lesion is a diffuse foot process effacement that can be seen on EM. light and immunofluorescence microscopy are normal.

Question 76

What is the hallmark of pulmonary fibrosis?

Answer 76

Reduced pulmonary parenchymal compliance

Question 77

What is the major virulence for E coli that causes neonatal meningitis?

Answer 77

E coli, a G- rod, is a common cause of neonatal meningitis. The major virulence factor for E coli strains that cause neonatal meningitis is the K1 capsular antigen, which allows bacteria to survive in the bloodstream and invade the meninges

Question 78

What is seen in Tetralogy of Fallot

Answer 78

can present in infancy with episodic cyanosis and poor weight gain. Right ventricular outflow tract obstruction (reduced perfusion of the pulmonary arteries) results in chronic hypoxemia, leading to secondary polycythemia

Question 79

MOA of angiotensin-converting enzyme (ACE) inhibitors

Answer 79

ACE inhibitors block the effect of ACE, decreasing angiotensin II and aldosterone levels. By decreasing angiotensin II levels, ACE inhibitors directly interrupt negative feedback loops, thereby increasing renin and angiotensin I levels. ACE is also responsible for the breakdown of bradykinin; ACE inhibitors therefore increase bradykinin levels

Question 80

What is the function of matrix metalloproteinases in wound healing?

Answer 80

During the remodeling phase of wound healing, matrix metalloproteinases facilitate the degradation of collagen and other proteins in the extracellular matrix, using the replacement of type III, disorganized collagen with type I, well organized and cross linked collagen. This leads to both increased tensile strength and flattening of the scar

Question 81

Multiple endocrine neoplasia type 2 is caused by?

Answer 81

germline activating mutations in the RET proto-oncogene and frequently results in both medullary thyroid cancer and pheochromocytoma. In patients with undiagnosed pheochromocytoma, induction of anesthesia (eg, preparation for thyroidectomy) can precipitate a catecholamine surge, leading to hypertensive crisis, flash pulmonary edema and atrial fibrillation

Question 82

What is rheumatic mitral stenosis?

Answer 82

Diffuse fibrous thickening and distortion of the mitral valve leaflets along the commissural fusion at the leaflet edges. Patients often present with a diastolic murmur, dyspnea, and fatigue and are at increased risk of atrial fibrillation and thromboembolism (eg, stroke)

Question 83

Amyloid light chain amyloidosis is a/w?

Answer 83

multiple myeloma and other monoclonal plasma cell dyscrasias due to the depositions of insoluble immunoglobulin light chain fibrils in major organs (kidneys, heart, neurologic system). A bone marrow sample with >10% plasma cells is strongly suggestive of multiple myeloma

Question 84

What is the cause of myasthenia gravis?

Answer 84

An autoimmune disease that causes a decreased number of functional acetylcholine receptors within the neuromuscular junction. This reduces the number of postsynaptic cation channels that can open in response to acetylcholine, which reduces the amplitude of motor end plate potential and prevents muscle fiber depolarization.

Question 85

The treatment of myasthenia gravis involves the use of acetylcholinesterase inhibitors. Adverse effects are related to muscarinic overstimulation, which can be ameliorated by?

Answer 85

the use of an antimuscarinic agent such as glycopyrrolate

Question 86

What is human epidermal growth factor receptor 2 (HER2)?

Answer 86

A receptor tyrosine kinase that is overexpressed in 20% of breast cancer patients. In such patients, HER2 blockade with the monoclonal antibody trastuzumab downregulates cellular proliferation and promotes apoptosis

Question 87

What is seen in patients with alpha-1 antitrypsin deficiency?

Answer 87

The major serum inhibitor of extracellular elastase is alpha 1 antitrpysin. Patients with AAT def typically develop early onset panacinar emphysema due to unchecked elastase activity. Exposure to tobacco smoke dramatically accelerates the development of emphysema in patients with AAT def and should be avoided.

Question 88

Function of natural killer cells

Answer 88

NK cells recognize and kill cells with decreased MHC class I antigen cell surface expression, such as virus-infected cells and tumor cells. They are large lymphocytes that contain perforins and granzymes in cytoplasmic granules. NK cells kill target cells by inducing apoptosis.

Question 89

What is acne vulgaris?

Answer 89

an inflammatory disorder of pilosebaceous follicles. Contributing factors include hyperkeratinization and obstruction of follicles; sebaceous gland enlargement with increased secretion of sebum; colonization and proliferation in the gland by Propionibacterium (Cutibacterium) acnes; and follicular and perifollicular inflammation

Question 90

What occurs during the transmigration stage in inflammation?

Answer 90

After crawling to the endothelial cell periphery, neutrophils eventually migrate out of the vasculature by squeezing in between the cells via integrin attachments and adherence to platelet endothelial cell adhesion molecule 1 (PECAM-1). This protein is found primarily at the peripheral intercellular junctions of endothelial cells

Question 91

Function of glutamate

Answer 91

Glutamate is released from injured neurons, causing pathologic hyperactivation of NMDA receptors and leading to depolarization, calcium overload, and death of neighboring cells. This cascade of excitotoxicity contributes to neurodegeneration and propagation of neuron death after focal injury

Question 92

What is the most common cause of congenital bilateral absence of the vas deferens?

Answer 92

CFTR gene mutations. Patients with congenital bilateral absence of the vas deferens have azoospermia and infertility but normal levels of FSH, LH and testosterone. Elevated sweat chloride levels are diagnostic of cystic fibrosis.

Question 93

What is West Nile virus?

Answer 93

West Nile virus is harbored in birds and transmitted to humans by mosquitoes. Most patients are asymptomatic, but the virus can cause an influenza-like illness or neuroinvasive disease with meningitis, encephalitis, and flaccid paralysis.

Question 94

Where should you give intragluteal injections?

Answer 94

The superolateral quadrant of the buttock is a relatively safe site for intragluteal injections, although the anterolateral gluteal region is preferred. Injections given in the superomedial quadrant of the buttock have a high risk of injuring the superior gluteal nerve, resulting in gluteus medius weakness and Trendelenburg gait

Question 95

What is seen in acute promyelocytic leukemia?

Answer 95

Can present with persistent infection and coagulopathy, causing hemorrhagic signs and symptoms. Bone marrow examination classically reveals abnormal promyelocytes with intracytoplasmic Auer rods.

Question 96

Translocation for acute promyelocytic leukemia

Answer 96

t(15;17) chromosomal translocation that fuses the retinoic acid receptor-alpha and promyelocytic leukemia genes

Question 97

What is panic disorder

Answer 97

characterized by recurrent anxiety attacks a/w prominent somatic symptoms. Abrupt onset of characteristic physical symptoms that resolve within minutes and a negative medical workup should raise suspicion for panic disorder.

Question 98

What occurs in renal artery stenosis?

Answer 98

In renal artery stenosis, increased production of angiotensin II causes increased systemic blood pressure (to increase renal perfusion) and preferential constriction of the glomerular efferent arteriole (to increase glomerular filtration). Patients with bilateral renal artery stenosis are dependent on this response to maintain renal function; initiation of ACE inhibitors or angiotensin II receptor blockers can precipitate acute renal failure. However, urinalysis is typically unremarkable (ie, no hematuria, proteinuria, or casts.)

Question 99

What is the Jarisch-Herxheimer reaction?

Answer 99

an acute inflammatory reaction that occurs within hours of treatment for spirochetal infections (eg, syphilis). The rapid lysis of spirochetes releases inflammatory bacterial lipoproteins into the circulation and causes acute fever, rigors, and myalgias

Question 100

What is deficient in hereditary fructose intolerance?

Answer 100

aldolase B deficiency