Uworld33

Question 1

What is Dubin Johnson syndrome?

Answer 1

a benign disorder characterized by defective hepatic excretion of bilirubin glucuronides across the canalicular membrane, resulting in direct hyperbilirubinemia and jaundice.

Grossly, the liver appears black due to impaired excretion of epinephrine metabolites, which histologically appear as dense pigments within lysosomes.

Question 2

What is pheochromocytoma?

Answer 2

a tumor arising from the chromaffin cells of the adrenal medulla characterized by excess production of catecholamines.

Clinical features: episodic hypertension, diaphoresis, and palpitations.

Microscopic exam: electron dense, membrane bound secretory granules

Immunohistochem: positive for synaptophysin, chromogranin, and neuron specific enolase

Question 3

What is psoriasis?

Answer 3

a common inflammatory skin disorder characterized by hyperkeratosis (overgrowth of the stratum corneum) and epidermal hyperplasia.

Plaque psoriasis is the most common form and presents with chronic well demarcated, erythematous plaques with a thick, silver scale

Question 4

How does corticosteroids treat asthma?

Answer 4

Corticosteroids (fluticasone, budesonide) have multiple beneficial effects in the treatment of asthma.

In addition to their anti-inflammatory effect, corticosteroids upregulate beta-2 receptors on bronchial smooth muscle to increase cellular responsiveness to adrenergic stimuli and potentiate the bronchodilatory response to inhaled beta-2 agonists (albuterol)

Question 5

Histopath for meningomas

Answer 5

Meningiomas are slow growing, well circumscribed, benign intracranial tumors typically found at the cerebral convexities in adults.

Characteristics histopath: syncytial nests and a whorled pattern of cellular growth, which may calcify into round, laminar structures called psammoma bodies.

Question 6

What is the primary virulence factor of neiserria?

Answer 6

Pili are the primary virulence factor that allow Neisseria meningitidis to initially attach to and colonize the nasopharyngeal epithelial surface.

Pili undergo significant antigenic variation, which makes them a difficult vaccination target.

Question 7

What is seen on a left shift on the hemoglobin oxygen dissociation curve?

Answer 7

A left shift of the hemoglobin oxygen dissociation curve indicates increased hemoglobin O2 affinity and can be caused by increased pH, decreased 2,3-bisphosphoglycerate, and decreased temp.

Leftward shifts of the curve inhibit the release of O2 within peripheral tissues

Question 8

Treatment of septic arthritis

Answer 8

A high synovial fluid leukocyte count (>100,000)and absent crystals on microscopic exam strongly suggest bacterial joint infection.

Septic arthritis requires antibiotic treatment to prevent joint destruction, osteomyelitis, and sepsis

Question 9

What is Creutzfeldt-Jakob disease?

Answer 9

a prion disease characterized by rapidly progressive dementia, myoclonus, and death within a year of symptom onset.

It is caused by the accumulation of an abnormally folded (ie, beta pleated sheet) protein that is resistant to proteases and can trigger similar conformational changes in other normally folded proteins.

Question 10

Multiple sclerosis results from?

Answer 10

an autoimmune demyelinating disease that results from oligodendrocyte depletion.

Within the lesions, inflammatory infiltrates of lymphocytes and macrophages are seen surrounding oligodendrocytes and myelin sheaths.

Oligoclonal bands are highly sensitive but nonspecific in patients with MS.

Question 11

Function of transforming growth factor beta

Answer 11

critical for fibroblast migration, proliferation, and connective tissue synthesis.

Increased TGF-beta activity is responsible for the hypertrophic/keloid scarring and fibrosis of the lung, liver, and kidney that occur with chronic inflammation

Question 12

Why does S3 develop in severe mitral regurg?

Answer 12

Patients with severe mitral regurg develop left sided volume overload with an S3 gallop due to the large volume of regurgitant flow reentering the ventricle during mid-diastole.

The absence of an S3 gallop excludes severe chronic MR.

Question 13

What is effect modification?

Answer 13

present when the effect of the main exposure on the outcome is modified by the presence of another variable. Effect modification is not a bias.

Question 14

What are the labs for Down syndrome?

Answer 14

Down syndrome is the most common chromosomal anomaly.

It is associated with low levels of maternal serum alpha-fetoprotein (AFP) and estriol, while b-hCG and inhibin A levels are increased.

Elevated AFP levels are seen in multiple gestation, open neural tube defects, and abdominal wall defects.

Question 15

What is immunosenescense?

Answer 15

the normal age-related decline that impairs most aspects of immune function, including the production of naive B and T cells.

This results in a diminished antibody-based immune response to novel antigens (eg, infections, vaccinations). The immune response to previously experienced pathogens is typically intact due to normal or increased levels of memory B and T cells and preserved antibody quality.

Question 16

What is hemoglobin S (HbS)?

Answer 16

HbS aggregates in the deoxygenated state.

HbS polymers form fibrous strands that reduce red blood cell membrane flexibility and promote sickling.

Sickling occurs under conditions associated with anoxia including low pH and high levels of 2,3-bisphosphoglycerate.

These inflexible erythrocytes predispose to microvascular occlusion and microinfarcts.

Question 17

Mechanism of diphtheria toxin

Answer 17

an AB exotoxin that ribosylates and inactivates elongation factor-2. This action inhibits protein synthesis and ultimately leads to cell death

Question 18

What can cause central diabetes insipidus?

Answer 18

Injury to hypothalamus or posterior pituitary (eg, head trauma, transsphenoidal neurosurgery, suprasellar masses) can result in central diabetes insipidus.

Damage to the posterior pituitary gland typically causes transient DI, whereas damage to the hypothalamic nuclei often causes permanent DI.

Question 19

What is the main purpose of binding in a clinical trial?

Answer 19

to prevent patient or researcher expectancy from interfering with an outcome.

Question 20

Patients who have overdosed on beta blockers should be treated with?

Answer 20

glucagon, which increases heart rate and contractility independent of adrenergic receptors. Glucagon activates G-protein-coupled receptors on cardiac myocytes, causing activation of adenylate cyclase and raising intracellular cAMP. The result is calcium release from intracellular stores and increased sinoatrial node firing.

Question 21

Function of the cysteinyl-containing leukotrienes (ie, leukotriene C4, D4, and E4)

Answer 21

are inflammatory mediators that stimulate bronchoconstriction, bronchial mucus secretion, and bronchial edema to contribute to the pathogenesis of asthma.

Leukotriene receptor antagonists (eg, montelukast, zafirlukast) treat asthma by binding to leukotriene receptors on bronchial smooth muscle cells and blocking these effects.

Question 22

Function of carcinoembryonic antigen (CEA)

Answer 22

levels are increased in colon cancer but are also elevated in a number of other conditions (eg, pancreatic cancer, COPD, cirrhosis)

CEA cannot be used to diagnose colon cancer, but it is helpful for detecting residual disease and recurrence.

Question 23

What is parvovirus B19 infection?

Answer 23

can cause transient aplastic crisis, particularly in those with underlying hemoglobin disorders such as sickle cell anemia.

Patients develop symptomatic anemia (eg, exertional dyspnea, fatigue, low hematocrit) due to inhibition of erythropoiesis by the virus. Bone marrow examination will show giant pronormoblasts with glassy, intranuclear viral inclusions.

Question 24

What type of agglutinins does mycoplasma pneumoniae have?

Answer 24

Mycoplasma pneumoniae binds an oligosaccharide on the respiratory epithelium that is also present on erythrocytes, leading to the generation of cross-reacting IgM antibodies (cold agglutinins).

Patients with M pneumoniae infections often develop mild, transient hemolytic anemia that resolves as IgM antibody titers decline (6-8 weeks after infection begins).

Question 25

The inferior epigastric artery branches off?

Answer 25

the external iliac artery immediately proximal to the inguinal ligament. It provides blood supply to the lower anterior abdominal wall as it runs superiorly and medially up the abdomen.

Question 26

Translocation of follicular lymphoma?

Answer 26

Follicular lymphoma is a common, indolent non-Hodgkin lymphoma. It is characterized by a translocation involving BCL2 on chromosome 18, which becomes positioned near the immunoglobulin heavy chain gene on chromosome 14, resulting in overexpression of BCL2 (an antiapoptotic protein).

Question 27

What is a compound nevi?

Answer 27

benign proliferations of melanocytes that involve both the dermis and the epidermis. The lesions appear as slightly raised papules with uniform pigmentation and symmetric sharp borders.

Question 28

What is seen in chronic aortic regurgitation?

Answer 28

In chronic aortic regurgitation, persistent left ventricular volume overload triggers eccentric hypertrophy, which causes a compensatory increase in stroke volume to maintain cardiac output. This compensatory mechanism allows for a relatively long asymptomatic period in most patients; however, left ventricular dysfunction eventually occurs, leading to heart failure.

Question 29

Function of beta-lactamase inhibitors (eg, clavulanic acid, sulbactam, tazobactam)

Answer 29

prevent beta-lactamase from inactivating penicillin class drugs, which extends the spectrum of their activity

Question 30

What is pemphigus vulgaris?

Answer 30

an autoimmune bullous disease characterized by autoantibodies directed against desmosomal proteins (eg, desmogleins). It presents with painful, flaccid bullae and erosions affecting the skin and mucosal membranes. The bullae spread laterally with pressure, and new blisters may form with gentle rubbing.

Question 31

A stroke in the medial medulla often results in?

Answer 31

Crossed signs (ie, ipsilateral cranial nerve dysfunction with contralateral limb weakness) are typical of a brainstem stroke. A stroke in the medial medulla often results in contralateral limb weakness with ipsilateral tongue weakness, which causes tongue deviation to the weak side.

Question 32

Typically features of congenital toxoplasmosis

Answer 32

Pregnant women should avoid consumption of undercooked meat to prevent infection with Toxoplasma gondii, an intracellular, cresent-shaped parasite that can cross the placenta to the fetus. Typical features of congenital toxoplasmosis include chorioretinitis, hydrocephalus, and diffuse intracranial calcifications.

Question 33

What is a central retinal artery occlusion?

Answer 33

presents with sudden, painless, and permanent monocular blindness. Funduscopic examination reveals a pale retina and a "cherry red" macula.

Question 34

What is placenta accreta?

Answer 34

occurs due to abnormal attachement of the placenta directly onto the uterine myometrium. This condition most often develops because the endometrial decidua basalis is absent or defective due to previous uterine scarring (eg, prior cesarean delivery). The classic presentation is a morbidly adherent placenta that does not detach after fetal delivery.

Question 35

What is dermatomyositis?

Answer 35

characterized by proximal muscle weakness resembling polymyositis, with additional inflammatory features involving the skin (heliotrope rash, Gottron papules). Both dermatomyositis and polymyositis may occur alone or as a paraneoplastic syndrome associated with an underlying adenocarcinoma (eg, ovary, lung, pancreas)

Question 36

What markers does small cell carcinoma of the lung have?

Answer 36

Small cell carcinoma of the lung is the most aggressive type of lung cancer and is commonly associated with paraneoplastic syndromes (eg, SIADH, Cushing syndrome). It is thought to have a neuroendocrine origin; tumor cells express neuroendocrine markers (eg, neural cell adhesion molecule, chromogranin, synaptophysin) and contain neurosecretory granules in the cytoplasm.

Question 37

What is seen in hypertrophic cardiomyopathy?

Answer 37

Hypertrophic cardiomyopathy typically involves asymmetric left ventricular hypertrophy that is most prominent in the interventricular septum and commonly causes left ventricular outflow tract obstruction. The left ventricular hypertrophy also impairs diastolic LV filling, with an S4 commonly heard as blood strikes the thick, stiffened LV wall.

Question 38

The risk of venous thromboembolism (ie, pulmonary embolism or deep vein thrombosis) in hospitalized patients can be greatly reduced with the adminstration of?

Answer 38

prophylactic anticoagulation, usually with low-molecular-weight heparin

Question 39

Inferior wall myocardial infarction commonly involves the right ventricle. MI primarily involving the right ventricle is marked by?

Answer 39

elevated central venous pressure, low pulmonary capillary wedge pressure (due to reduced blood glow through the lungs to the left atrium), and low cardiac output. This contrasts with classic cardiogenic shock, which results from the left ventricular failure and leads to elevated pulmonary capillary wedge pressure with pulmonary edema

Question 40

What is Goodpasture syndrome?

Answer 40

caused by autoantibodies against the alpha 3 chain of type IV collagen in glomerular and alveolar basement membranes (anti-GBM antibodies). Patients typically present with rapidly progressive glomerulonephritis (nephritic syndrome) and alveolar hemorrhage (shortness of breath, hemoptysis)

Question 41

The phrenic nerve arises from?

Answer 41

the C3-C5 segments of the spinal cord and innervates the ipsilateral hemodiaphragm. Intrathoracic spread of lung cancer may affect the phrenic nerve, causing hiccups and diaphragmatic paralysis with dyspnea. Brachial plexus involvement can cause pain the distribution of the C8, T1, and t2 nerve roots. Involvement of the recurrent laryngeal nerve may cause hoarseness

Question 42

What is a complete hydatidiform mole?

Answer 42

composed of multiple cystic edematous hydropic villi resulting from trophoblast proliferation. Serial measurements of b-hCG should be performed following evacuation of a hydatidiform mole. Persistently elevated or rising levels may signify the development of an invasive mole or choriocarcinoma.

Question 43

What is a craniopharyngiomas?

Answer 43

The anterior pituitary is formed from an out-pouching of the pharyngeal roof and is called Rathke's pouch. The posterior pituitary gland arises from an extension of the hypothalamic neurons. Craniopharyngiomas are tumors arising from Rathke's pouch remnants in the anterior pituitary. They characteristically have three components; solid, cystic, and calcified. They present during childhood, usually, with mass effect and visual deficits.

Question 44

Most inhaled particles that lodge in the bronchial tree are removed via?

Answer 44

proximal transport by ciliated epithelial cells (mucociliary clearance). Mucos-secreting cells are present to the level of the larger bronchioles, after which club cells become the prominent secretory cell type.

Question 45

Treatment of tinea pedis

Answer 45

Tinea pedis is a superficial infection of the epidermis caused by dermatophytes (eg, Trichophyton rubrum). It most often presents as a pruritic, erythematous rash between the toes that frequently extends along the sole. Microscopy of skin scraping shows branching hyphae. Treatment options include a variety of topical antifungals (eg, clotrimazole), but not nystatin.

Question 46

What is seen in renal clear cell carcinoma?

Answer 46

The most common renal malignancy is clear cell carcinoma, which arises from renal proximal tubular cells. Rounded or polyglonal cells with abundant clear cytoplasm are seen on light microscopy. The cells contain large amounts of glycogen and lipids that dissolve during routine tissue preparation, leaving clear spaces within the cytoplasm.

Question 47

What is epidermolysis bullosa?

Answer 47

is a group of inherited disorders characterized by epithelial fragility (eg, bullae, erosions, ulcers) triggered by minor trauma. It is caused by mutations affecting proteins in the intraepidermal and dermoepidermal adhesion complexes; keratin mutations are responsible for the most common form (EB simplex).

Question 48

What is follicular lymphoma?

Answer 48

the most common indolent non-Hodgkin lymphoma in adults. It is of B-cell origin and presents with painless waxing and waning (ie,fluctuating) lymphadenopathy. The cytogenetic change t(14;18) is characteristic and results in overexpression of the BCL2 oncogene.

Question 49

Treatment of duodenal peptic ulcers

Answer 49

Most duodenal peptic ulcers are caused by Helicobacter pylori infection. Treatment and prevention of disease recurrence focus on eradicating the infection with antibiotics (eg, tetracycline, metronidazole), typically in combination with proton pump inhibitors (eg, omeprazole) and often, bismuth subsalicylate (quadruple therapy)

Question 50

What is succinylcholine?

Answer 50

can cause significant potassium release and life threatening arrhythmias in patients at high risk for hyperkalemia, including those with burns, myopathies, crush injuries, and denervating injuries or disease.

Question 51

What is anorexia nervosa?

Answer 51

characterized by a distorted body image and fear of weight gain despite significantly low body weight. Patients may restrict their food intake and/or binge and purge. The key in distinguishing anorexia nervosa from bulimia nervosa is abnormally low body weight.

Question 52

Magnesium salts and aluminum hydroxide are basic mineral salts used to?

Answer 52

neutralize gastric acid and relieve gastroesophageal reflux symptoms. Side effects include diarrhea and constipation, respectively. Therefore, these medications are often combined to offset the adverse effects of the individual medications.

Question 53

Thiamine deficiency causes what?

Answer 53

beriberi and Wernicke-Korsakoff syndrome. Dry beriberi is characterized by symmetrical peripheral neuropathy; wet beriberi includes the addition of high-output congestive heart failure.

Question 54

What is thromboangiitis obliterans (Buerger disease)?

Answer 54

a segmental, inflammatory vasculitis that affects the small and medium sized arteries and veins of the distal extremities with inflammatory, intraluminal thrombi and sparing of the vessel wall. It is usually seen in young, heavy smokers, and can present with digital ischemia and ulceration, extremity claudication, Raynaud phenomenon, and superficial thrombophlebitis.

Question 55

What is congenital hypothyroidism?

Answer 55

Congenital hypothyroidism, most commonly caused by abnormal thyroid gland development or location (ie, ectopy), is identified by elevated TSH and decreased thyroxine (T4) levels. Clinical manifestations of hypothyroidism are not present at birth due to the transplacental transfer of small amounts of maternal T4.

Question 56

Ionizing radiation induces DNA damage (eg, double stranded breakage, free radical generation) that predominantly affects which cells?

Answer 56

affects highly proliferative cells (eg, skin stem cells, hematogenous progenitors, intestinal crypt cells). These rapidly dividing cells are the first to be lost following significant radiation exposure, resulting in hair loss, pancytopenia, diarrhea, and nausea/vomiting.

Question 57

What is osteitis fibrosa cystica?

Answer 57

a form of renal osteodystrophy characterized by abnormally high bone turnover caused by chronic parathyroid hormone stimulation of osteoclasts to a greater degree than that of osteoblasts. Bone biopsy would show an increased number of both osteoclasts and osteoblasts

Question 58

Nigrostriatal degeneration in Parkinson disease impairs?

Answer 58

thalamic stimulation of the motor cortex, resulting in bradykinesia, rigidity, and resting tremor. Patients with medically intractable symptoms may benefit from surgery to decrease output of the globus pallidus interna or subthalamic nucleus, promoting thalamocortical disinhibition with improvement in Parkinson symptoms

Question 59

Isolated mitral stenosis causes?

Answer 59

elevated upstream pressures in the left atrium and pulmonary veins and arteries. Left ventricular end diastolic pressure (LVEDP) is normal or decreased due to obstruction of blood flow through the stenotic valve. An elevated LVEDP suggests additional downstream pathology (eg, aortic valve disease, left ventricular failure)

Question 60

What is oral thrush?

Answer 60

Oral thrush is caused by candida albicans infection and usually presents as white, plaque-like oropharyngeal lesions that are easily scraped off with a tongue depressor. Affected patients typically have disruption to local microbial flora (eg, antibiotic use) or impairment in cell-mediated immunity (eg, corticosteroids, HIV). Young, otherwise healthy patients with thrush should be tested for HIV

Question 61

What is Charcot-Marie-Tooth?

Answer 61

a group of hereditary peripheral neuropathies characterized by mutations in genes coding for peripheral nerve axonal or myelin proteins. Manifestations typically include progressive, symmetric distal muscle atrophy and weakness most prominent in the feet and calf musculature, with sensory loss, areflexia, pes cavus (ie, high arches) and hammer toes.

Question 62

What is anemia of chronic disease?

Answer 62

caused by elevated inflammatory cytokine levels (eg, hepcidin), which increase sequestration of iron within the reticuloendothelial system and reduced circulating iron levels. Many patients have improvement in anemia with treatment of the underlying condition that caused the inflammation.

Question 63

Postoperative hypocalcemia is common after thyroid surgery, due to?

Answer 63

inadvertent removal or damage to the parathyroid glands. The acute drop in parathyroid hormone level results in decreased calcium and phosphate resorption from bone and decreased calcium reabsorption by the kidneys

Question 64

A moderately elevated alkaline phosphatase of unclear etiology should be followed up with?

Answer 64

gamma-glutamyl transpeptidase

Question 65

What nerves are at risk for injury during axillary lymph node dissection?

Answer 65

Multiple nerves are at risk for injury during axillary lymph node dissection. Intercostobrachial nerve injury results in sensory dysfunction (eg, burning, numbness) to the skin of the axilla and medial upper arm. Injury to the long thoracic (serratus anterior), thoracodorsal (latissimus dorsi), medial pectoral (pectoralis minor and major), or lateral pectoral (pectoralis major) nerves results in motor deficits to corresponding muscles.

Question 66

What is reactive arthritis?

Answer 66

a spondyloarthropathy associated with HLA-B27 that can occur following infection with Chlamydia, campylobacter, salmonella, shigella, or yersinia. It presents with sterile arthritis due to deposition of immune complexes.

Question 67

Serotonin-releasing neurons in the central nervous system are located in?

Answer 67

the raphe nuclei. These neurons disseminate widely to synapse on numerous structures in the CNS. Antidepressants such as selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and tricyclic antidepressants inhibit serotonin reuptake at these synapses.

Question 68

MOA of amiloride and triamterene (potassium-sparing diuretics)

Answer 68

Potassium-sparing diuretics are often added to loop or thiazide diuretics to prevent hypokalemia. Amiloride and triamterene directly inhibit the epithelial sodium channel, preventing sodium from entering the principal cell, which reduces the electrochemical gradient (ie, negative luminal charge) that helps drive potassium secretion.

Question 69

Function of lamellar bodies of type II pneumocytes?

Answer 69

store and release surfactant, which decreases alveolar surface tension and facilitates lung expansion. A low lamellar body count reflects surfactant deficiency and lung immaturity, as in neonatal respiratory distress syndrome, which results in alveolar collapse and diffuse atelectasis.

Question 70

Bacterial vaginosis is caused by?

Answer 70

a disruption of the vaginal bacterial flora and is characterized by a thin, gray white, malodorous vaginal discharge. Clue cells (squamous epithelial cells with adherent bacteria) are seen on wet mount microscopy.

Question 71

What is primary myelofibrosis?

Answer 71

a myeloproliferative disorder associated with the clonal expansion of megakaryocytes. Bone marrow fibrosis accounts for most of the major manifestations, including hepatosplenomegaly, cytopenias, and blood smear evidence of dacrocytes. Bone marrow aspiration is usually dry, but bone marrow biopsy will show marked fibrosis with occasional clusters of atypical megakaryocytes.

Question 72

What is seen in adults with ADHD?

Answer 72

Attention-deficit hyperactivity disorder often persists into adulthood. Adults with ADHD are less overtly hyperactive but experience chronic problems with distractibility, disorganization, and impulsivity that cause significant social and occupational impairment.

Question 73

Pancreatic islet amyloid deposition is characteristic of?

Answer 73

type 2 diabetes mellitus. A strong linkage with HLA class II gene makeup, pancreatic islet infiltration with leukocytes (insulitis), and antibodies against islet antigens are frequently seen in type 1 diabetes.

Question 74

X-chromosome inactivation occurs in?

Answer 74

genotypic females and results in conversion of the chromosomal DNA into condensed heterochromatin (ie, Barr body). Heterochromatin is located at the periphery of the nucleus and composed of heavily methylated DNA and deacetylated histones, causing it to have a low level of transcriptional activity.

Question 75

What is seen in theophylline intoxication?

Answer 75

Seizures are the major cause of morbidity and mortality from theophylline intoxication. Tachyarrhythmias are the other major concern.

Question 76

What is 6-mercaptopurine (6-MP)?

Answer 76

an immunosuppression drug that is inactivated by 2 enzymes, xanthine oxidase and thiopurine methyltransferase. Reduced function of either enzyme causes increased levels of the active metabolites of 6-MP, leading to increased immunosuppression and risk of toxicity.

Question 77

What is hypoxic pulmonary vasoconstriction?

Answer 77

limits perfusion to nonventilated alveoli, shunting blood toward better-ventilated ones, preserving ventilation-perfusion matching to maintain oxygenation. HPVC can be impaired by inflammatory vasodilation (eg, pneumonia or sepsis), and restoration of HPVC optimizes oxygenation despite minimal improvement in ventilation of consolidated alveoli

Question 78

The side effects of first-generation antihistamines (hydroxyzine, promethazine, chlorpheniramine, diphenhydramine) are due to?

Answer 78

blockade of cholinergic, alpha-adrenergic, and serotonergic pathways. They should be avoided in older patients with cognitive or functional impairments.

Question 79

Pathogenesis of tetanospasmin (tetanus toxoid)

Answer 79

Tetanus is caused by infection with toxigenic strains of anaerobic bacterium Clostridium tetani. Transmission typically occurs when spores are inoculated into the skin via a puncture wound. The bacteria germinate, replicate locally, and elaborate tetanospasmin (tetanus toxoid). The toxin spreads in a retrograde fashion through the lower motor neurons to the spinal cord, where it blocks inhibitory interneurons and causes spasmodic muscle contraction (eg, trismus, risus sardonicus)

Question 80

What is cytomegalovirus esophagitis?

Answer 80

can occur in transplant patients and usually presents with odynophagia or dysphagia that can be accompanied by fever or burning chest pain. Endoscopy typically shows linear and shallow ulcerations in the lower esophagus, and histology usually shows enlarged cells with intranuclear inclusions.

Question 81

Herpes zoster (shingles) develops due to reactivation of varicella zoster virus in?

Answer 81

the dorsal root ganglial (sensory neurons). It presents with a painful vesicular rash in a dermatomal distribution. Intranuclear inclusions in keratinocytes and multinucleated giant cells are seen on light microscopy.

Question 82

Intention to treat analysis includes?

Answer 82

each subject in their initial randomization group even if subjects stop the intervention or shift to a different intervention. This approach tends to provide a conservative but more valid estimate of the intervention effect in real world scenarios (ie, clinical settings)

Question 83

What is a pilocytic astrocytoma?

Answer 83

the most common pediatric brain tumor and is typically found in the cerebellum. Histopath: a well differentiated neoplasm composed of cells with hair like processes that stain positively for glial fibrillary acidic protein. Eosinophilic corkscrew shaped (Rosenthal) fibers and eosinophilic granular bodies are frequently present.

Question 84

Name the 4 chemotactic agents for neutrophils

Answer 84

IL-8, leukotriene B4, 5-HETE (the leukotriene precursor) and complement C5a.

Question 85

What is autosomal dominant polycystic kidney disease?

Answer 85

typically manifests in patients age 40-50 with enlarged kidneys, flank pain, and hypertension. In newborns, the kidneys are of normal size, and the cysts are too small to be detected on abdominal ultrasound. As the cysts enlarge, they compress the renal parenchyma and cause symptoms

Question 86

What is Sjogren syndrome?

Answer 86

autoimmune inflammation of exocrine glands (salivary, lacrimal, vaginal). Patients typically have severe dry mouth (xerostomia) due to reduced saliva production, which can lead to an increased rate of dental caries and other oral infections (eg, thrush) because of the loss of protective factors in saliva. Biopsy of the salivary glands show a lymphocytic infiltrate, often with germinal centers.

Question 87

MOA of nitrates (nitroglycerin, isosorbide mononitrate, isosorbide dinitrate)

Answer 87

Nitrates are metabolized to nitric oxide and S-nitrothiols in vascular smooth muscle cells, leading to an increase in cyclic guanosine monophosphate (cGMP) that stimulates vasodilation. Large veins are predominantly affected, leading to increased venous capacitance and reduced venous return (preload), which decreases left ventricular wall stress and myocardial oxygen demand to relieve anginal symptoms

Question 88

A chest tube for drainage of pleural effusion is place through?

Answer 88

the skin and subcutaneous fat into the 4th or 5th intercostal space in the anterior axillary or midaxillary line. The tube traverses through the serratus anterior muscle, intercostal muscles, and parietal pleura.

Question 89

Keloids are due to overexpression of?

Answer 89

Keloids result from excessive collagen formation during the remodeling phase of wound healing, which occurs due to overexpression of transformation growth factor beta and excessive fibroblast proliferation. They typically present as raised, painful, and pruritic lesions that grow beyond the original wound borders

Question 90

What is fragile X syndrome?

Answer 90

a common cause of intellectual disability. It results from unstable expansion of trinucleotide repeats (CGG) in the fragile X messenger ribonucleoprotein 1 (FMR1) gene. Classical physical findings: dysmorphic facial features (long face, prominent jaw, protruding ears) and macroorchidism.

Question 91

What is X-linked (Bruton) agammaglobulinemia?

Answer 91

caused by a defect in B cell maturation, resulting in absent mature B cells and severely low immunoglobulin levels. T cell numbers and function remain intact. Due to the absence of B cells, primary lymphoid follicles and germinal centers do not form within lymph nodes.

Question 92

Difference between right and left sided colon cancers

Answer 92

Right sided colon cancers usually grow as exophytic masses and present with occult bleeding and symptoms of iron deficiency anemia. Left sided colon cancers tend to infiltrate the intestinal wall and encircle the lumen, causing constipation and symptoms of intestinal obstruction. Rectosignmoid involvement often causes hematochezia.

Question 93

LH stimulates what in females?

Answer 93

LH stimulates the theca interna cells of the ovarian follicle to produce androgens. Aromatase within the follicle's granulosa cells subsequently converts these androgens to estradiol under FSH stimulation. The theca externa cells serve as a connective tissue support structure for the follicle.

Question 94

The unit of analysis in ecological studies is?

Answer 94

populations rather than individuals

Question 95

What is a pancreatic pseudocyst?

Answer 95

a common complication of acute pancreatitis. It is a collection of fluid rich in enzymes and inflammatory debris. Its wall consist of granulation tissue and fibrosis. Unlike true cysts, pseudocytes are not lined by epithelium.

Question 96

Infection triggers increased circulating neutrophils by?

Answer 96

stimulating the release of neutrophils, bands, and late granulocyte precursors from the bone marrow. This is mediated by increased cytokines (TNF-alpha) and complement activation. Demarginalization of neutrophils from endothelial attachment also contributes to leukocytosis

Question 97

What is seen in multiple myeloma?

Answer 97

Multiple myeloma should be suspected in elderly patients who have any combination of osteolytic lesions, hypercalcemia, anemia, or acute kidney injury. Renal disease is most commonly caused by light chain cast nephropathy, in which free light chains form obstructive casts in the renal tubules. Monoclonal paraproteins are not detected by urine dipstick (which detects only albumin) but both spot and 24-hour protein concentrations will be elevated

Question 98

UMN signs and LMN signs

Answer 98

UMN: abnormal plantar flexion (babinski sign), spastic paralysis, increased muscle tone, clasp-knife rigidity, hyperreflexia, pronator drift, and pyramidal weakness (weakness more pronouced in lower extremity flexors and upper extremity extensors). LMN: flaccid paralysis, weakness with hypotonia and muscle atrophy, fasciculations, and suppressed or absent reflexes.

Question 99

What is the metaplasia seen in Barrett esophagus?

Answer 99

Squamous bronchial metaplasia is a reversible, adaptive response to chronic irritation, such as smoking. The normal columnar epithelium is replaced by squamous epithelium, which is more resistant to irritation but has reduced mucociliary clearance. Metaplasia also occurs with Barret esophagus, in which esophageal squamous epithelium is replaced by intestinal columnar epithelium with goblet cells in response to chronic acid exposure

Question 100

Pleural effusions results from?

Answer 100

an increased rate of fluid inflow from the nearby vasculature or a decreased rate of fluid outflow through the parietal pleural lymphatics. Decompensated heart failure causes pleural effusion primarily due to increased fluid inflow from increased pulmonary capillary hydrostatic pressure; lymphatic outflow increases but is unable to keep up with increased inflow