Uworld33 Flashcards
What is Dubin Johnson syndrome?
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.
What is pheochromocytoma?
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
What is psoriasis?
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
How does corticosteroids treat asthma?
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)
Histopath for meningomas
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.
What is the primary virulence factor of neiserria?
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.
What is seen on a left shift on the hemoglobin oxygen dissociation curve?
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
Treatment of septic arthritis
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
What is Creutzfeldt-Jakob disease?
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.
Multiple sclerosis results from?
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.
Function of transforming growth factor beta
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
Why does S3 develop in severe mitral regurg?
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.
What is effect modification?
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.
What are the labs for Down syndrome?
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.
What is immunosenescense?
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.
What is hemoglobin S (HbS)?
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.
Mechanism of diphtheria toxin
an AB exotoxin that ribosylates and inactivates elongation factor-2. This action inhibits protein synthesis and ultimately leads to cell death
What can cause central diabetes insipidus?
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.
What is the main purpose of binding in a clinical trial?
to prevent patient or researcher expectancy from interfering with an outcome.
Patients who have overdosed on beta blockers should be treated with?
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.
Function of the cysteinyl-containing leukotrienes (ie, leukotriene C4, D4, and E4)
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.
Function of carcinoembryonic antigen (CEA)
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.
What is parvovirus B19 infection?
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.
What type of agglutinins does mycoplasma pneumoniae have?
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).
The inferior epigastric artery branches off?
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.
Translocation of follicular lymphoma?
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).
What is a compound nevi?
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.
What is seen in chronic aortic regurgitation?
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.
Function of beta-lactamase inhibitors (eg, clavulanic acid, sulbactam, tazobactam)
prevent beta-lactamase from inactivating penicillin class drugs, which extends the spectrum of their activity
What is pemphigus vulgaris?
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.
A stroke in the medial medulla often results in?
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.
Typically features of congenital toxoplasmosis
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.
What is a central retinal artery occlusion?
presents with sudden, painless, and permanent monocular blindness.
Funduscopic examination reveals a pale retina and a “cherry red” macula.
What is placenta accreta?
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.
What is dermatomyositis?
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)
What markers does small cell carcinoma of the lung have?
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.
What is seen in hypertrophic cardiomyopathy?
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.
The risk of venous thromboembolism (ie, pulmonary embolism or deep vein thrombosis) in hospitalized patients can be greatly reduced with the adminstration of?
prophylactic anticoagulation, usually with low-molecular-weight heparin
Inferior wall myocardial infarction commonly involves the right ventricle. MI primarily involving the right ventricle is marked by?
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
What is Goodpasture syndrome?
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)
