Uworld19

Question 1

What is the major virulence factor of Strep pyogenes?

Answer 1

M protein, an alpha-helical coiled protein that shares structural homology with tropomyosin and myosin.

It extends from the cell wall and prevents phagocytosis, inhibits complement binding, and mediates bacterial adherence.

Antibodies against M protein form shortly after acute infection and may cross react with epitopes on myosin, leading to rheumatic carditis

Question 2

Chronic lithium toxicity (eg, confusion, ataxia, neuromuscular excitability) can be precipitated by?

Answer 2

volume depletion and drug interactions with thiazide diuretics, ACE inhibitors, and nonsteroidal anti-inflammatory drugs

Question 3

What is cyclic neutropenia?

Answer 3

Cyclic neutropenia occurs as a result of a mutation in the gene encoding neutrophil elastase.

This leads to accelerated apoptosis of neutrophil precursors with characteristic bone marrow findings of nuclear fragmentation and membrane blebbing.

Cyclic neutropenia is characterized by episodic (every 3 weeks), severe neutropenia that causes recurrent fever and mucositis

Question 4

Why does Pseudomonas cause persistent infection in cystic fibrosis?

Answer 4

Patients with cystic fibrosis have thick, viscous mucus that accumulates in the airways and promotes colonization of bacteria, particularly Pseudomonas.

This gram-negative rod can produce biofilms, which act as a protective matrix that allows bacterial macrocolonies to develop, causing persistent infection.

Question 5

What is the pathogenesis of Mallory-Weiss tears?

Answer 5

Mallory Weiss teats accounts for about 10% of cases of upper GI hemorrhage.

They occur due to increased intraluminal gastric pressure due to retching, vomiting, or other abdominal straining

Question 6

What is dystonia?

Answer 6

a neurologic movement disorder characterized by sustained, involuntary muscle contractions that often result in abnormal, sometimes painful posturing.

Many patients can have temporary relief with the use of a sensory trick (eg, touching the face)

Question 7

In the adenoma to carcinoma sequence, which gene mutation develops to malignant transformation?

Answer 7

The adenoma to carcinoma sequence is a series of gene mutations that leads to the development of colon adenocarincoma.

TP53 tumor suppressor gene mutation is part of the final step in the sequence and leads to malignant transformation of preexisting large adenomatous polyps.

Question 8

Hypocalcemia causes?

Answer 8

Hypocalcemia can cause muscle cramps, perioral paresthesias, hypotension, and neuromuscular hyperexcitability.

Injury to the parathyroid glands during thyroid surgery is a common cause of hypoparathyroidism and acute hypocalcemia

Question 9

What is anaphylaxis? Treatment?

Answer 9

type 1 (immediate) HSR involving IgE mediated mast cell and basophil degranulation.

Epinephrine is the primary treatment for anaphylaxis because it decreases further mast cell release of inflammatory mediators and counteracts existing systemic inflammatory effects (eg, shock, bronchoconstriction)

Question 10

What is Ehrlichia chaffeensis?

Answer 10

harbored in white tailed deer and transmitted to humans by tick bite

It replicates in vacuoles within monocytes and forms mulberry-shaped, intraleukocytic inclusions (morale).

Manifestations: nonspecific symptoms (eg, fever, chills, myalgia, maculopapular rash, and significant laboratory abnormalities, particularly lymphopenia

Question 11

Steady state concentration is reached in how many half lives?

Answer 11

During continous infusion of a drug metabolized by first order kinetics, the steady state concentration is reached in 4 to 5 half lives

Question 12

Which cytokines is associated with chronic inflammation?

Answer 12

Chronic inflammation is associated with increased circulating pro-inflammatory cytokines (eg, IL-1, IL-6, tumor necrosis fator-alpha), which stimulates the liver to release acute phase reactants (eg, C-reactive protein, fibrinogen)

The presence of acute phase reactants increase the erythrocyte sedimentation rate, a nonspecific marker for inflammation

Question 13

How are the pneumoconiosis cleared from the lungs?

Answer 13

The pneumoconioses are diseases resulting from the inhalation of fine dust particles that reach the respiratory bronchioles and alveoli.

Particles that lodge in this region are normally cleared by alveolar macrophages.

High particulate burden can cause the excessive release of cytokines from macrophages, resulting in progressive pulmonary fibrosis

Question 14

What is illness anxiety disorder?

Answer 14

excessive concern about having a serious, undiagnosed disease, despite few or no symptoms and negative medical workup

Question 15

5-HT3 receptor antagonists are useful for the treatment of?

Answer 15

visceral nausea due to gastrointestinal insults, such as gastroenteritis, chemotherapy, and general anesthesia

Question 16

Antihistamines and anticholinergics are recommended for what kind of nausea?

Answer 16

vestibular nausea

Question 17

Dopamine antagonists are useful for what kind of nausea?

Answer 17

nausea associated with migraine

Question 18

The upper midbrain contains?

Answer 18

the neural structures (eg, optic nerve, pretectal nuclei, Edinger-Westphal nuclei, oculomotor nerve) that mediate the direct and consensual pupillary light reflex

Question 19

What is pulmonary arterial hypertension?

Answer 19

a vascular complication of systemic sclerosis.

also involves fibroproliferative remodeling of the vessel wall, leading to increased pulmonary vascular resistance and right sided heart failure

Question 20

Transport of glucose into the cell of most tissues occurs by the means of?

Answer 20

facilitated diffusion.

Glucose moves from areas of high concentration to areas of low concentration with the help of transmembrane glucose transporter proteins (GLUT). These carrier proteins are stereoselective and have preference for D-glucose.

Question 21

What is reciprocal induction?

Answer 21

a type of signaling that occurs between two tissues that requires both be present to induce normal development.

Reciprocal induction occurs in development of the kidney (ie, between metanephric blastema and ureteric bud) and the eye (ie, between optic vesicle and surface ectoderm)

Question 22

Patients with a long history of asbestos exposure are at risk for developing?

Answer 22

asbestosis, pleural disease and malignancies such as bronchogenic carcinoma and mesothelioma.

Bronchogenic carcinoma is the most common malignancy in this population, although mesothelioma is more specific for asbestos exposure

Question 23

What is the treatment for cyanide poisoning?

Answer 23

Cyanide is a potent mitochondrial toxin that binds to the ferric ion in the heme center of cytochrome c oxidase.

This blocks the electron transport chain and uncouples oxidative phorsphorylation.

Hydroxocobalamin, an antidote for cyanide poisoning, rapidly binds to cyanide and forms the nontoxic metabolite cyanocobalamin, which is excreted in the urine

Question 24

What is accumulation effect?

Answer 24

The concept of accumulation effect can be applied to disease pathogenesis and exposure to risk modifiers.

Cumulative exposure to a risk factor or risk reducer must sometimes occur for prolonged periods before a clinically significant effect is detected

Question 25

What is metemoglobinemia?

Answer 25

Acquired methomoglobinemia can be precipitated by benzocaine and result in the conversion of Fe2+ to Fe3+, which results in functional anemia and a left shift of the oxygen-dissociation curve. Patients have cyanosis that does not improve with supplemental oxygen.

Question 26

Approximately 25% of patients with active TB have false negative tuberculin skin testing (anergy) due to?

Answer 26

an impaired cell mediated immune response. These individuals are at greater risk for severe, disseminated disease and death. False negative TST can also be seen with immunocompromise, improper injection technique, and recent infection

Question 27

What is paroxysmal nocturnal hemoglobinuria?

Answer 27

due to a gene defect that leads to uncontrolled complement-mediated hemolysis. The classic triad: hemolytic anemia (hemoglobinuria), pancytopenia, and thrombosis at atypical site Chronic hemolysis can cause iron deposition in the kidney (hemosiderosis)

Question 28

What is tetralogy of Fallot?

Answer 28

Severe tetralogy of Fallot is a ductal-dependent lesion that requires blood flow through the ductus arteriosus (from the aorta to the pulmonary artery) for adequate oxygenation. Prostaglandin E1 prevents closure of the ductus arteriosus and should be immediately administered to all cyanotic neonates with suspected ductal-dependent lesions

Question 29

What is pneumocystis pneumonia? treatment?

Answer 29

Pneumocystitis pneumonia is common in patients with advanced HIV and usually presents with slowly worsening cough and dyspnea, hypoxia, and bilateral interstital infiltrates. Diagnosis requires visualizing the organism in respiratory secretions using special stains (eg, methenamine silver stain). First line treatment is trimethoprim-sulfamethoxazole

Question 30

Sickle cell disease and its relation with the spleen

Answer 30

Sickle cell disease is characterized by repeated splenic infarctions that ultimately result in splenic atrophy and fibrosis, a process that is typically complete by late childhood/adolescence. After autosplenectomy, patients are predisposed to infections with encapsulated bacterial organisms

Question 31

an MCV>110 is highly suggestive of?

Answer 31

megaloblastic anemia, such as that caused by folic acid or vitamin B12 def. Patients with chronic hemolytic anemia have increased folic acid requirements due to increased erythrocyte turnover and are predisposed to developing macrocytosis

Question 32

What are the electrolyte abnormalities in primary adrenal insufficiency?

Answer 32

Patients with type 1 diabetes are at increased risk for other autoimmune endocrinopathies, including primary adrenal insufficiency (Addison disease). Electrolyte abnormalities in primary adrenal insufficiency include hyponatremia, hyperkalemia, hyperchloremia, and nonanion gap metabolic acidosis

Question 33

What is decreased during exercise?

Answer 33

Exercising muscles can receive up to 85% of the total cardiac output during periods of strenuous activity. Although sympathetic discharge during exercise causes increased cardiac output and splanchnic vasoconstriction, there is only a modest increase in mean blood pressure as vasodilation within active skeletal muscles significantly decreases the total systemic vascular resistance.

Question 34

Perianal sensation is carried by which nerve roots?

Answer 34

S2-S4

Question 35

Compressive lesions (eg, disk herniation, tumors) affecting the L1-L5 vertebral levels can impinge upon the conus medullaris and/or T12-S4 nerve toots, causing?

Answer 35

radicular low back pain, changes in bowel/bladder function, saddle/perianal anesthesia (eg loss of anocutaneous reflex), and lower extremity weakness

Question 36

Patients who require stem cell transplantation due to a congenital genomic disease typically receive donor cells from?

Answer 36

matched unrelated donor cells because they will have matched human leukocyte antigen alleles but will not have the genomic mutation that caused the condition

Question 37

Thyrotoxicosis can cause?

Answer 37

Thyrotoxicosis, whether due to endogenous hyperthyroidism or over-replacement with thyroid hormone in patients with hypothyroidism, causes a hyperadrenergic state that can lead to atrial fibrillation, high output heart failure, and worsening of angina pectoris

Question 38

The accuracy of screening or diagnostic tests is quantified by?

Answer 38

the area under the ROC curve (AUC). The more accurate the test is (ie, higher sensitivity and specificity), the closer the AUC value is to 1. Tests with higher AUCs are more accurate than tests with lower AUCs.

Question 39

The primary mechanism underlying cytotoxic (early) edema following cerebral ischemia is?

Answer 39

the accumulation of intracellular Na+ and water due to the failure of ATP-dependent ion transporters in hypoxic cells. Cerebral edema causes progressive neurologic decline by raising intracranial pressure, which can directly damage neural tissue or result in mechanical damage due to brain herniation

Question 40

What is the most common outcome of hep C infection without antiviral treatment?

Answer 40

lifelong persistent infection (ie, chronic hep C) Of those with chronic hep C, approximately 20% develop cirrhosis, and only a minority experiences complications (eg, ascites, variceal bleeding, hepatocellular carcinoma)

Question 41

What happens in patients with long-standing hypertension?

Answer 41

A chronic autoregulatory shift in blood pressure flow relationship occurs, affording less perfusion (flow) at any given pressure. Therefore, excessively rapid correction of blood pressure toward normal may induce relative ischemia.

Question 42

First generation antipsychotics can be classified according to high or low potency and have characteristic side effect profiles. What are they?

Answer 42

Low potency antipsychotics are more likely to cause sedation, anticholinergic side effects, and orthostatic hypotension. High potency antipsychotics are more likely to cause extrapyramidal symptoms (eg, dystonia, akathisia, parkinsonism)

Question 43

Pancoast tumor can lead to?

Answer 43

A tumor of the lung apex (Pancoast tumor) can compress both the brachial plexus and the stellate ganglion of the sympathetic chain, leading to lower motor neuron arm weakness and ipsilateral Horner syndrome

Question 44

What is D-xylose?

Answer 44

Polysaccharides must be degraded to monosaccharides by pancreatic and brush border amylases before they can be absorbed. Monosaccharides can be absorbed directly. D-xylose is a monosaccharide whos absorption is not affected by exocrine pancreatic insufficiency, and can be used to differentiate between pancreatic versus mucosal causes of malabsorption

Question 45

What is hypovolemic shock?

Answer 45

Results from markedly decreased blood volume, which reduces central venous pressure and cardiac output and leads to increased systemic vascular resistance (peripheral vasoconstriction). Shock causes reduced organ and tissue perfusion, which leads to lactic acidosis (metabolic acidosis) and a compensatory increase in ventilation (ie, compensatory respiratory alkalosis)

Question 46

What are xanthelasmas?

Answer 46

a type of xanthoma, are yellowish macules/papules found on the medial eyelids. They are dermal accumulations of macrophages containing cholesterol and triglycerides, and are generally associated with a primary or secondary hyperlipidemia or dyslipidemia. An LDL receptor abnormality is the most common cause

Question 47

what is delusional disorder?

Answer 47

>1 delusions for >1 months in the absence of other psychotic symptoms. Behavior is not obviously bizarre, and functioning is not significantly impaired apart from the direct impact of the delusions.

Question 48

Amiodarone relationship with thyroid?

Answer 48

Amiodarone is 40% iodine by weight. It can cause hypothyroidism due to decreased production of thyroid hormone. Amiodarone can also cause hyperthyroidism due to increased thyroid hormone synthesis or destructive thyroiditis with release of preformed thyroid hormone.

Question 49

What is sarcoidosis?

Answer 49

systemic inflammatory disorder characterized by noncaseating granulomas in a variety of tissues. Most patients develop liver involvement, which typically manifests as asymptomatic hepatomegaly with mild liver function test abnormalities. Liver biopsy frequently demonstrates scattered noncaseating granulomas.

Question 50

What is randomization?

Answer 50

refers to the process of using random methods to assign subjects to experimental groups. Its purpose is to make experimental groups as similar as possible (except for the treatment assignment) to ensure that any difference observed between the groups is due exclusively to the treatment and not to other underlying factors.

Question 51

The sequence of amino acids in a growing polypeptide chain is dictated by mRNA codons, which bind to?

Answer 51

the complementary anticodon on tRNA that has the corresponding amino acid attached. tRNA that is mischarged with an incorrect amino acid will incorporate it into the growing polypeptide chain in place of the correct amino acid.

Question 52

Atrial fibrillation occurs due to?

Answer 52

irregular, chaotic electrical activity within the atria and presents with absent P waves, irregularly irregular R-R intervals, and narrow QRS complexes. The atrioventricular node refractory period regulates the number of atrial impulses that reach the ventricles and determines the ventricular contraction rate in conditions where the atria undergo rapid depolarization.

Question 53

Why do immunotherapy medications often utilize fragments of a monoclonal immunoglobin rather than the full immunoglobulin?

Answer 53

because fragments are smaller, they typically have better tissue penetration and pharmocokinetics. Fab fragments contain a variable domain and the first constant region from a heavy and light chain; because they do not contain an Fc receptors, Fab fragments cannot trigger cell killing via complement or phagocytosis

Question 54

What is prevalence?

Answer 54

Prevalence = incidence rate x average disease duration. Changing disease prevalence in a steady-state population with a constant incidence rate means that there is an additional factor affecting the duration of the condition. A factor that prolongs disease duration (eg, improved quality of care) will increase disease prevalence, as affected patients survive longer.

Question 55

What is obsessive-compulsive disorder?

Answer 55

persistent, unwanted thoughts (obsessions) and repetitive time consuming rituals (complusions) that the individual feels driven to perform to alleviate anxiety.

Question 56

What is L5 radiculopathy?

Answer 56

Spinal nerves in the lumbosacral spine exit through the neural foramina that is below the corrsesponding vertebral body level (eg, L5 nerve root exits between L5 and S1 vertebral bodies) and can be compressed at the neural foramina due to osteophyte formation. In addition to back pain, L5 radiculopathy often presents with sensory loss over the lateral thigh, calf, and dorsal foot and weakness of great toe extension and foot dorsiflexion, inversion,and eversion.

Question 57

Patients with alcohol use disorder are at increased risk for lung abscess due to the aspiration of oral flora during periods of unconsciousness. Most cases involve which organisms?

Answer 57

Most cases involve a mixture of upper respiratory aerobes and oral cavity anaerobes (eg, Bacteroides, Prevotella, Fusobacterium, Peptostreptococcus). Manifestations include subacute fever, cough, and foul smelling sputum

Question 58

When does angiogenesis occur in wound healing?

Answer 58

Angiogenesis is the process by which new blood vessels are formed. It primarily occurs during the proliferation phase of wound healing and is stimulated by growth factors such as fibroblast growth factor and vascular endothelial growth factor

Question 59

What is seen in autism spectrum disorder?

Answer 59

Patients with milder forms of autism spectrum disorder frequently have normal language and cognitive development. Characteristic features include deficits in social communication and reciprocal social interactions, restricted interests, and behavioral rigidity that become more apparent as social and academic demands increase

Question 60

What is the most common cause of acute pericarditis?

Answer 60

Viral infection; it causes a fibrinous or serofibrinous pericarditis that is often characterized by pleuritic chest pain, a friction rub on cardiac auscultation, diffuse ST elevation on ECG, and mild to moderate sized pericardial effusion

Question 61

What is seen in acute pulmonary edema?

Answer 61

Acute pulmonary edema is a common consequence of acute myocardial infarction affecting the left ventricule. Elevated hydrostatic pressure in the pulmonary venous system leads to engorged alveolar capillaries with transudation of fluid into the alveoli, appearing as acellular pink material on microscopy. Hemosiderin-laden macrophages are indicative of CHRONIC lung congestion and are not present acutely.

Question 62

Dopamine agonist medications used to treat Parkinson disease have been associated with?

Answer 62

the abrupt onset of impulse control disorders, including pathological gambling, complusive buying, and compulsive sexual behavior. The behavior is thought to be mediated by stimulation of central dopamine receptors.

Question 63

What is cardiac tamponade?

Answer 63

involves increased pericardial pressure that restricts diastolic filling of the right sided heart chambers, leading to obstructive shock with increased central venous pressure and decreased stroke volume and cardiac output. As tamponade progresses, diastolic pressures in all 4 cardiac chambers increase and equalize with pericardial pressure (and with one another), stagnating blood flow within the heart

Question 64

Which nerves are at risk for injury during gynecologic laparoscopic surgery?

Answer 64

the ilioinguinal and iliohypogastric nerves; patients with an ilioinguinal nerve injury typically have paresthesia to the upper medial thigh, mons pubis, and labia majora.

Question 65

Patients with advanced HIV and low CD4 counts are at risk for opportunistic infections and require antimicrobial prophylaxis. What can be seen with CD4 <200?

Answer 65

Pneumocystic jiroveci pneumonia prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX)

Question 66

Risk factors for ectopic pregnancy?

Answer 66

Ectopic pregnancy occurs when the embryo implants in an extrauterine location, most commonly the fallopian tube. Risk factors: tubal scarring (eg, prior pelvic surgery, pelvic inflammatory disease), tobacco use, and in vitro fertilization

Question 67

What is Klinefelter syndrome?

Answer 67

Pathologic gynecomastia should be suspected in patients who also have signs of hypogonadism (eg, small/firm testes, absent pubic hair) Klinefelter syndrome (47, XXY) is the most common cause of primary hypogonadism, and patients have low testosterone, elevated gonadotropin (FSH,LH) and relatively increased estradiol levels

Question 68

What is a cavernous hemangioma?

Answer 68

the most common benign liver tumor. Microscopically, these tumors consists of cavernous, blood filled vascular spaces of variable size lined by a single epithelial layer. The biopsy of a suspected hemangioma is not advisable, as the procedure has been known to cause fatal hemorrhage and is of low diagnostic yield.

Question 69

Diabetic autonomic neuropathy can cause?

Answer 69

Diabetic autonomic neuropathy is common in type 1 diabetics and can cause overflow incontinence due to inability to sense a full bladder and incomplete emptying. Postvoid residual (PVR) testing with ultrasound or catheterization can confirm inadequate bladder emptying

Question 70

What is olecranon bursitis?

Answer 70

Presents with localized swelling at the olecranon process. Pain and erythema are typically minimal or absent unless significant inflammation is present. A bursa is not an intraarticular structure; therefore, range of motion of the associated joint is typically preserved and pain free.

Question 71

Unilateral renal artery stenosis causes?

Answer 71

hypoperfusion and activation of the renin-angiotensin-aldosterone system. Angiotensin II causes arteriolar vasoconstriction and increases aldosterone and antidiuretic hormone synthesis. The resultant hypertension helps reduce the decline in glomerular filtration rate in the affected kidney, but causes a pressure natriuresis with increased sodium excretion in the unaffected kidney/

Question 72

Why is the hep C virus genetically unstable?

Answer 72

because it lacks proofreading 3'-5' exonuclease activity in its RNA polymerase. Its envelope glycoprotein sequences also contain a hypervariable region prone to frequent genetic mutation

Question 73

S4 is caused by?

Answer 73

An S4 is a low frequency, late diastolic sound that immediately precedes S1. It is caused by blood striking a stiffened ventricular wall during atrial contraction; concentric left ventricular hypertrophy due to chronic hypertension (or less commonly due to aortic stenosis) is a common cause of an S4

Question 74

What are the hemoglobin pattern in homozygous sickle cell disease?

Answer 74

Homozygous sickle cell disease is marked by a point mutation in both beta globin genes. This leads to the generation of a new predominant hemoglobin called hemoglobin S (HbS), which polymerizes when deoxygenated. Because hemoglobin F (HbF) prevents HbS polymerization, hydroxyurea is often administered to increase HbF levels and reduce complications of the disease

Question 75

Cortisol increases the conversion of norepinephrine to epinephrine in the adrenal medulla by?

Answer 75

increasing the expression of phenyethanolamine-N-methyltransferase

Question 76

What is seen in a Strongyloides stercoralis infection?

Answer 76

involves filariform (infective) larvae penetrating human skin, traveling to the lungs, and then being swallowed. The parasites mature in the small intestine, laying eggs in the mucosa that hatch into rhabditiform (noninfective) larvae. Rhabditiform larvae can be detected on stool microscopy, which is diagnostic of active infection.

Question 77

What is tetralogy of Fallot?

Answer 77

a congenital heart defect characterized by right ventricular outflow tract (RVOT) obstruction, a large ventricular septal defect, an overriding aorta, and right ventricular hypertrophy. The degree of RVOT obstruction is is the greatest determinant of symptom severity because it regulates pulmonary arterial blood flow and the magnitude and direction of shunting through the VSD

Question 78

What is horseshoe kidney?

Answer 78

congenital anomaly in which the inferior poles of the developing kidney fuse in utero. Most patients remain asymptomatic but are at increased risk for recurrent nephroliths and urinary tract infections due to the abnormal orientation and positioning of the kidney Restricted by inferior mesenteric artery

Question 79

What is recombination?

Answer 79

gene exchange through the crossing over of 2 double stranded DNA molecules

Question 80

What is reassortment?

Answer 80

the mixing of genome segments in segmented viruses that infect the same host cell

Question 81

What is vasospastic angina?

Answer 81

the result of intermittent coronary vasospasm caused by endothelial dysfunction and autonomic imbalance. Although acetylcholine normally stimulates vasodilation, it triggers coronary vasospasm in affected patients due to a deficiency of vasodilatory endothelial nitric oxide

Question 82

Aflatoxin B1 increases the risk for?

Answer 82

Aflatoxin B1 is a carcinogen produced by Aspergillus that contaminates food (corn) in hot, humid environments (eg, southeast Asia). Chronic alfatoxin B1 ingestion is associated with inactivating p53 mutations that increases the risk for hepatocellular carcinoma

Question 83

Deficiency in Vitamin E

Answer 83

Vitamin E is a fat soluble vitamin, and deficiency can occur in individuals with fat malabsorption due to recurrent pancreatitis. Vitamin E def is associated with increased susceptibility of the neuronal and erythrocyte membranes to oxidative stress. Clinical manifestations include decreased proprioception, ataxia, peripheral neuropathy (eg, hyporeflexia), and hemolytic anemia.

Question 84

What is Huntington disease?

Answer 84

AD neurodegenerative disease that leads to the accumulation of abnormal, toxic huntingtin protein in neural cells. Inhibitory GABAergic neurons in the caudate nuclei are most susceptible, and their loss is responsible for the characteristic manifestations of Huntington disease (chorea, behavioral abnormalities)

Question 85

MOA of sotalol and side effects

Answer 85

Sotalol has both beta adrenergic blocking and class III antiarrhythmic (K+ channel blocking) properties and is occasionally used in the treatment of atrial fibrillation. Major side effects of sotalol: bradycardia, proarrhythmia, and torsades de pointes due to QT interval prolongation

Question 86

What is ghrelin?

Answer 86

produced in the stomach in response to fasting; levels surge leading up to meals and fall after eating. Ghrelin stimulates appetite and promotes weight gain. Patients who have undergone gastrectomy have reduced ghrelin levels, leading to weight loss

Question 87

Disrupted development of the third pharyngeal pouch (eg, DiGeorge Syndrome) leads to?

Answer 87

Derivatives of the third pharyngeal pouch include the thymus and inferior parathyroid glands. Disrupted development of the third pharyngeal pouch leads to thymic hypoplasia/aplasia with impaired T-cell development and immunodeficiency

Question 88

What increases the risk for developing early-onset Alzheimer disease?

Answer 88

Patients with trisomy 21 (Down Syndrome) have 3 copies of the amyloid precursor protein gene located on chromosome 21. This increases amyloid-beta accumulation in the brain, placing these patients at high risk for developing early-onset Alzheimer disease

Question 89

Describe the 3 types of population pyramids: expansive, stationary, and constrictive

Answer 89

expansive: young and growing population; high birth and mortality rates stationary: stable population; declining birth rates and low mortality rates constrictive: shrinking population; significantly low birth and mortality rates

Question 90

What type of meds can be used to treat cerebral palsy?

Answer 90

Cerebral palsy results in spasticity (eg, hypertonia, hyperreflexia) due to a loss of descending inhibitory control. Meds used to enhance the activity of GABA, the primary inhibitory neurotransmitter of the CNS, can improve spasticity.

Question 91

What increases the risk for EBV?

Answer 91

Patients with HIV have much higher rates of lymphoma than the general population. Many cases are due to underlying Epstein-Barr virus infection, which acts synergistically with HIV to promote uncontrolled B lymphocyte proliferation

Question 92

What causes vascular calcifications?

Answer 92

Vascular calcifications occur more commonly in patients with CKD due to electrolyte abnormaities (eg, hyperphosphatemia, hypercalcemia) and chronic inflammation (secondary to atherosclerosis and/or uremia) These changes promote calcification and suppress calcification inhibitors, which can result in extensive vascular calcifications

Question 93

What is gallstone ileus?

Answer 93

Gallstone ileus results from passage of a large gallstone through a cholecystenteric fistula into the small bowel, where it ultimately causes obstruction at the ileum. Patients typically present with symptoms/signs of small bowel obstruction. abdominal x ray: gas within the gallbladder and biliary tree

Question 94

What are cytochrome P450 enzymes?

Answer 94

Cytochrome P450 enzymes found in the liver are responsible for the majority of drug metabolism. Polymorphisms occuring in the genes coding for these enzymes result in various phenotypes that differ in their rates of metabolism; individual differences in phenotype alter treatment efficacy and drug toxicity

Question 95

Acute extrapyramidal symptoms (eg, dystonia, akathisia, parkinsonism) are due to?

Answer 95

D2 blockade in the nigrostriatal pathway. First generation, high potency antipsychotics (eg, haloperidol, fluphenazine) strongly block D2 receptors and are most likely to cause extrapyramidal symptoms

Question 96

What is hemolytic uremic syndrome?

Answer 96

a common cause of acute renal failure in children. It is characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Most cases develop following a diarrheal illness caused by Shiga toxin-producing organisms (eg, Escherichia coli O157:H7, Shigella dystenteriae)

Question 97

What catalyzes the rate limiting step in glycolysis?

Answer 97

Phosphofructokinase-1 (PFK-1) The most potent stimulator of PFK-1 is fructose 2,6-bisphosphate. Insulin increases production of fructose 2,6-bisphosphate by phosphofructokinase-2 (PFK-2), thereby stimulating glycolysis

Question 98

What is henoch-schonlein purpura, or IgA vasculitis?

Answer 98

classically presents with palpable purpura, with or without abdominl pain, athralgias, and renal involvement. Histopath of skin lesions: damaged small vessels with fibrinoid necrosis, perivascular neutrophilic inflammation, and nuclear debris (ie, leukocytoclastic vasculitis) IF: deposition of IgA and C3

Question 99

What is seen in osteoporsis?

Answer 99

Initially in osteoporosis, bone loss predominantly affects trabecular bone, leading to trabecular thinning and perforation with loss of interconnecting bridges. Over time, cortical bone, which composes most of the appendicular skeleton, also becomes involved.