Uworld 4 Flashcards
Vasovagal syncope results from what?
Vasovagal syncope typically involves a trigger (eg, prolonged standing), a prodrome (eg, warmth, light headedness) and rapid recovery (eg within 1-2 min).
It results from a transient, autonomic nervous system-mediated cardioinhibitory and vasodepressor response.
What is a trait of adenosine deaminase (ADA) inhibition/absence?
It is highly lymphocytotoxic.
Meds that block ADA are used to treat lymphocyte-derived cancers, like hairy cell.
Inherited gene mutations in adenosine deaminase leads to?
the autosomal recessive disease of severe combined immunodeficiency
What does the anterior cerebral artery supply?
The medial aspects of the frontal and parietal lobes, which contain the upper motor neurons responsible for contralateral lower extremity motor control.
Thromoboembolic occulsion of the anterior cerebral artery results in?
Contralateral lower extremity weakness with hyperreflexia
What is the pathogenesis of rheumatoid arthritis?
Early activation of CD4+T cells (especially Th1 and Th17) with release of cytokines such as tumor necrosis factor-alpha and IL-1 that cause destruction of cartilage and bone.
Monoclonal antibodies that inhibit tumor necrosis factor-alpha or IL-1 receptors can slow progression of the disease.
What can happen if you use lithium during pregnancy?
Lithium is commonly used to treat bipolar disorder.
Its use during pregnancy is associated with Ebstein’s anomaly, which is characterized by apical displacement of the tricuspid valve leaflets, decreased right ventricular volume, and atrialization of the right ventricle.
What is S1 radiculopathy in sciatica?
Resulting in pain/sensory loss down the posterior thigh and calf to the lateral aspect of the foot.
Patients may also have weakness on thigh extenson, knee flexion, and foot plantarflexion with an absent Achilles reflex
What is seen on histo for aortic root disease with patients who have Marfan?
Marfan syndrome involves a deleterious mutation in fibrillin that mainly affects the structural integrity of the cardiovascular and musculoskeletal systems.
Aortic root disease predisposes to aortic dissection, which can present with sudden-onset chest or back pain, acute aortic regurgitation and heart failure.
Histo: fragmentation and loss of the elastic lamellae with fibrosis and cystic medial degeneration
What is stress hyperglycemia?
Transiently elevated blood glucose levels in the context of severe illness (eg, sepsis, burns, major hemorrhage) in patients without preexisting diabetes mellitus.
Cortisol and catecholamines released in response to severe metabolic stress act on the liver to increase glycogenolysis and gluconeogenesis.
Pulmonary embolism typically presents with hypoxemia due to?
ventilation/perfusion mismatch and acute resp alkalosis (hypocapnia) due to hyperventilation
Chronic alcohol use will act on what receptors?
Downregulates inhibitory GABA receptors and upregulates excitatory NMDA glutamate receptors.
Sudden cessation of alcohol leads to what?
decreased GABA activity and increased glutamate activity, resulting in CNS overexcitation (eg, agitation, disorientation, tremulousness, autonomic hyperactivity)
What is seen on MRI for vascular dementia?
Multiple small infarcts, microbleeds, and areas of hyperintensity in the white matter that represent demyelination or axon loss
What is primary hyperaldosteronism cause by? Clinical findings?
Caused by excessive aldosterone secretion, typically due to an aldosterone-producing adrenal adenoma or bilateral nodular hyperplasia of the zona glomerulosa.
CF: hypertension, low plasma renin, hypokalemia, and metabolic alkalosis.
What is severe combined immune deficiency? Labs?
Characterized by combined T and B cell dysfunction.
Bacterial and viral infections, mucocutaneous candidiasis, persistent diarrhea, and failure to thrive.
Labs: absent T cells and hypogammaglobulinemia
The thymic shadow is not present due to severe T cell def
Cervical spine trauma can lead to dissection of the vertebral artery, resulting in?
Resulting in infarction of the lateral medulla and causing vertigo/nystagmus, ataxia, loss of pain/temp sensation in the ipsilateral face and contralateral body, bulbar weakness, and ipsilateral Horner syndrome.
MOA of aminoglycosides (like gentamicin)
They inhibit genetic code reading and protein synthesis by binding to the prokaryotic 30S ribosomal subunit.
How does clonidine cause orthostatic syncope?
Clonidine, an antihypertensive agent. stimulates central alpha 2 adrenergic receptors, causing a decrease in presynaptic release of norepinephrine and a decrease in sympathetic outflow.
This prevents the normal baroceptor-mediated increase in peripheral vascular resistance and heart rate during standing and can cause orthostatic syncope.
What are the traits of Actinomyces?
G+ branching, filamentous bacteria that may cause cervicofacial infections when introduced to the submucosa during mechanical trauma (eg tooth extraction).
Manifestations: slowly enlarging, non painful, chronic mandibular mass that evolves into multiple abscesses and sinus tracts draining yellow-orange sulfur granules
What is Henoch-Schonlein purpura?
IgA mediated, leukocytoclastic vasculitis that presents with palpable purport, arthralgia/arthritis, abdominal pain, and/or hematuria
Renal involvement is due to mesangial deposition of IgA immune complexes with subsequent mesangial cell proliferation, neutrophilic infiltration, and glomerular damage
How is Helicobacter pylori associated with gastric MALT?
Helicobacter pylori is associated with gastric MALT lymphoma due to chronic stimulation of the immune response; the continuous cell dvision predisposes to accumulation of mutations that result in aberrant B-cell proliferation.
Treatment of H pylori can induce remission in the majority of cases of early stage gastric MALT lymphomas
Patients with profound and prolonged neutropenia are at especially high risk for fungal infections. What are the common ones?
Aspergillus and Candida
What is the treatment of malignant hyperthermia?
Dantrolene, which blocks ryanodine receptors to prevent the release of calcium from the sarcoplasmic reticulum into the cytoplasm of skeletal muscle fibers
What is malignant hyperthermia?
Widespread muscle rigidity after administration of inhalation anesthetics and/or succinylcholine to genetically susceptible individuals.
What anticoagulant can inactivate thrombin?
Unfractionated heparin is able to bind to both antithrombin and thrombin to allow antithrombin to inactivate thrombin
Gustatory (taste) innervation of the anterior 2/3 tongue is provided by?
chorda tympani branch of the facial nerve
Why is Pierre Robin characterized as a sequence?
Because the primary defect (hypoplasia of the mandibular prominence) leads to a cascade of further malformations (ie, micrognathia, posteriorly displaced tongue, U shaped cleft palate)
Secretin is produced by which cells?
By S cells in the duodenal mucosa in response to stimulation by intraluminal acidity.
What is the action of secretin?
Secretin stimulates the release of bicarbonate-rich secretions from the exocrine pancreas, which is the major source of acid-neutralizing bicarbonate entering the duodenum
Chronic granulomatous disease is due to?
Chronic granulomatous disease is a primary immunodeficiency due to impaired NADPH oxidase, an enzyme that generates reactive oxygen species in phagolysosomes.
Chronic granulomatous disease has recurrent infections with what?
Diminished intracellular killing within neutrophils leads to susceptibility to recurrent infection with catalase producing bacteria (eg Staph aureus, Nocardia, Burkholderia, Serratia) and fungi (eg Aspergillus)
Pulmonary arterial hypertension typically affects young women and can be familial. It is characterized by what?
By luminal narrowing of the pulmonary arteries and arterioles, with medial hypertrophy, intimal fibrosis, and the eventual development of plexiform lesions.
What is the MOA of Bosentan?
Competitive antagonist of endothelin receptors used for the treatment of pulmonary arterial hypertension
What is celiac disease?
An immune-mediated disorder triggered by dietary gluten that causes small-bowel malabsorption. Because the proximal small bowel is primarily affected, iron deficiency leading to microcytic anemia is common.
What is seen on histo for celiac disease?
Intraepithelial lymphocytosis, loss of intestinal villi, and mucosal atrophy
What is the MOA of protease inhibitors (atazanavir, darunavir, indinavir, ritonavir: -navir)?
HIV antiretroviral meds that inhibit cleavage of the polypeptide precursor into mature viral proteins
What is the side effects of protease inhibitors (atazanavir, darunavir, indinavir, ritonavir: -navir)?
Hyperglycemia, lipodystrophy, and drug-drug interactions due to inhibition of cytochrome P450
What can Clostridium perfringens cause?
Causes late-onset food poisoning and clostridial myonecrosis (gas gangrene).
The food poisoning is toxin-mediated, late onset, and causes transient watery diarrhea.
The jaw jerk reflex afferent and efferent pathways are mediated by what nerves?
The jaw jerk reflex is a pathological cranial nerve reflex present in patients with bilateral upper motor neuron lesions, such as amyotrophic lateral sclerosis.
Both the afferent and efferent pathways are mediated by the mandibular division of the trigeminal nerve (CN V3)
Acid maltase (alpha-glucosidase) deficiency presents how?
Presents in early infancy with cardiomegaly, macroglossia, and profound muscular hypotonia.
Abnormal glycogen accumulation within lysosomal vesicles is seen on muscle biopsy.
What are the traits for Strep pyogenes?
PYR-positive, beta-hemolytic, G+ coccus that grows in chains
Monomicrobial cases of necrotizing fasciitis is due to?
Necrotizing fasciitis is a severe infection of the subcutaneous tissue and deep fascia and is a surgical emergency,
Often polymicrobial, but monomicrobial cases due to Strep pyogenes (group A strep)
What is nephrogenic diabetes insipidus?
Polyuria, dilute urine (low urine specific gravity), hypernatremia, and high antidiuretic hormone
What is the treatment for nephrogenic diabetes insipidus?
Thiazide diuretics and replacement of water losses.
Benzodiazepine withdrawal is characterized by?
Anxiety, tremor, insomnia, and sympathetic hyperactivity (eg, diaphoresis, palpitations). Severe withdrawal may also include psychosis, seizures or death.
Intestinal type of gastric adenocarcinoma presents how?
Forms a solid mass that projects into the stomach lumen and is composed of gland-forming cuboidal or columnar cells
Diffuse type gastric adenocarcinoma presents how?
Infiltrates the stomach wall (linitis plastica) and displays signet ring cells on light microscopy
Elderly patients are at increased risk of developing heat-related illness due to several features of normal aging that impair normal thermoregulatory mechanisms, including what?
-tonic contraction of the peripheral vasculature
-reduced sweat gland density
-reduced effective epidermal area available for heat transfer
What genes are mutated in hypertrophic cardiomyopathy?
AD inherited condition resulting from mutations affecting genes that encode for myocardial contractile proteins of the sarcomere; myosin-binding protein C and beta-myosin heavy chain are the most commonly affected proteins.
HCM is characterized by asymmetic septal hypertrophy and increased risk of sudden cardiac death
Administration of metyrapone will cause what?
A decrease in cortisol synthesis via inhibition of 11-b-hydroxylase.
In patients with an intact hypothalamic-pituitary-adrenal axis, this will cause a reactive increase in ACTH, 11-deoxycortisol, and urinary 17-hydroxycorticosteroid levels
Sensitization to aeroallergens occurs when inhaled antigens induce what cells?
Induce T-helper (Th) cells to differentiate into Th2 cells.
Th2 cells then promote B-cell maturation and isotype class switching to IgE
Which carcinomas are the exception to lymphatic spread and instead will spread via hematogenous?
Renal cell carcinoma and hepatocellular carcinoma
What changes to the heart occur with age?
Cardiomyocyte hypertrophy (ie, concentric left ventricular hypertrophy) occurs with age to allow for maintenance of left ventricular contractility and ejection fraction despite cardiomyocyte dropout and increased left ventricular after load (due to reduced aortic compliance)
How is binge eating differentiated from bulimia nervosa?
By the absence of compensatory behaviors (eg self-induced vomiting, excessive exercise, fasting, misuse of laxatives)
Immune glomerular injury results from what?
Results from immune complexes or neutrophil activation.
Immune complex formation in the kidney typically produces renal-limited disease (except anti-glomerular basement membrane disease).
Preformed circulating immune complex deposition is usually associated with small vessel vasculitis and hypocomplementemia.
What is the most common symptomatic presentation of Cryptococcus neoformans infection?
Meningoencephalitis, typically in immunocompromised patients
What is the histo for Cryptococcus neoformans?
Budding yeasts with thick polysaccharide capsules, which stain using mucicarmine or India ink
Where is the nuclei of the vestibulocochlear nerve (CN VIII) located?
In the pons.
Damage to the nuclei of vestibulocochlear nerve (CN VIII) can lead to what?
The vestibular portion of CN VIII conveys information about head position and movement and helps to stabilize the gaze during head movement; damage can lead to nystagmus.
What can reverse warfarin? Which is quicker?
Both Vitamin K and fresh frozen plasma are used for reversing warfarin-induced anticoagulation
Fresh frozen plasma rapidly reverses warfarin’s effects whereas vitamin K requires time for clotting factor re-synthesis.
What is the most common childhood nephrotic syndrome?
Minimal change disease
What is the pathogenesis of minimal change disease?
Increased glomerular capillary permeability causes massive protein (eg, albumin) loss in the urine.
Hypoalbuminemia reduces plasma oncotic pressure, which causes a fluid shift into the interstitial space, resulting in edema.
Low oncotic pressure also triggers increased lipoprotein production in the liver (ie, hyperlipidemia).
Glucose-6-phosphate dehydrogenase deficiency presents how?
By periods of acute hemolysis after oxidative stress (eg dapsone expsoure). It presents with anemia and hemolysis.
Glucose-6-phosphate dehydrogenase deficiency presents how on peripheral smear?
Denaturated hemoglobin inclusions called Heinz bodies
How does the Haemophilis influenza type B vaccine work?
The Hib vaccine induces anticapsular antibodies that facilitate complement-mediated phagocytosis of the bacterium.
The vaccination series has drastically reduced the incidence of invasive disease caused by Hib, such as meningitis, bacteremia, pneumonia, and epiglottis.
Malignant mesothelioma is associated with?
Malignanat mesothelioma is a rare neoplasm typically arising from the pleura.
It is strongly associated with asbestos exposure and presents with progressive dyspnea, cough, and chest pain.
What is seen on imaging and histo for malignant mesothelioma?
Unilateral pleural thickening or plaque formation is seen on imaging; pleural effusions are also common and may be hemorrhagic.
Microscopic examination reveals tumor cells with numerous long, slender microvilli and abundant tonofilaments.
Why is intermittent anovulatory cycles common in the first few years after menarche?
It is due to an immature hypothalamic-pituitary-ovarian axis producing low and irregular GnRH pulses.
As a result, adolescent girls may have menstrual cycle variability with intermenstrual spotting and heavier menstrual bleeding.
What meds cause constipation?
-Non-dihydropyridine calcium channel blockers (eg diltiazem, verapamil)
-opiates
-5-HT3 antagonists
-iron tablets
-aluminum containing antacids
-meds with anticholinergic properties
Lactic acidosis in septic shock results from what?
From tissue hypoxia, which impairs oxidative phosphorylation and causes shunting of pyruvate to lactate following glycolysis.
Hepatic hypoperfusion also contributes to the buildup of lactic acid as the liver is the primary site of lactate clearance.
Who is at risk for aspiration pneumonia?
Patients with dementia or hemiparesis may have dysphagia, which is a risk factor for aspiration pneumonia.
Dependent lung consolidation is commonly seen in aspiration pneumonia.
What is the MOA of foscarnet
Pyrophosphate analog that does not require intracellular activation by viral or cellular kinases.
It directly inhibits both DNA polymerase in herpesvirus and reverse transcriptase in HIV.
Intestinal atresia involving bowel distal to the duodenum occurs due to?
Due to vascular occulsion in utero.
Superior mesenteric artery occlusion results in ischemia of the jejunum and ileum, resulting in a blind-ending proximal jejunum and a distal ileum that spirals around the ileocolic vessel that perfuses it (apple peel atresia)
Chemotherapy-associated neutropenic fever is most often caused by?
Endogenous commensal bacteria that have translocated across damaged mucosal sites.
Infective endocarditis (eg constitutional symptoms, fever, new cardiac murmur) can affect multiple organs, including the kidneys. Which kidney disease?
Glomerulonephritis typically occurs due to injury caused by circulating immune complex-mediated injury (type III HSR), which is characterized by acute kidney injury and hematuria with red blood cell casts.
What happens in chronic thiamine (B1) deficiency?
Impairs glucose use, particularly in mammillary bodies, as seen in Wernicke encephalopathy.
This occurs due to decreased activity of the enzyme that use thiamine as a cofactor (eg transketolase).
What is diagnostic of a chronic thiamine (B1) deficiency?
Low erythrocyte transketolase activity that increases after the addition of thiamine pyrophosphate.
What does angiotensin II do?
Angiotensin II preferentially constricts the efferent arteriole, resulting in an increased hydrostatic pressure gradient and an increased net filtration pressure.
The net filtration pressure is a result of pressure gradients formed by Starling forces and is calculated by?
Subtracting the oncotic pressure gradient from the hydrostatic pressure gradient
What is a major pathogen in burn patients?
Pseudomonas aeruginosa
What drugs treat Pseudomonas aeruginosa?
Penicillins (eg ticarcilin, piperacillin)
Cephalosporins (ceftazidime, cefepime)
Aminoglycosides
Fluroquinolones (ciprofloxacin, levofloxacin)
Carbapenems (imipenem, meropenem)
What is cataracts? What causes it?
Cataracts: progressive opacification of the lens with chronic loss of visual acuity
Aging and environmental (eg, UV light) contribute to cataract formation by inducing nuclear sclerosis, photooxidative damage to lens crystallins, and osmotic injury
What causes hemolytic disease of the newborn?
Occurs from maternal sensitization to Rh antigens during a prior pregnancy with an Rh(D)+ fetus.
In subsequent Rh(D)+ pregnancies, maternal anti-R(D) IgG antibodies cross the placenta and cause a severe autoimmune hemolytic anemia in the fetus and life-threatening hydros fetalis.
What is hemoglobin S (HbS)?
It contains valine in place of glutamic acid at the 6th amino acid position of the beta globin chain.
This promotes hydrophobic interaction among Hb molecules and results in HbS polymerization and erythrocyte sickling.
two functions of Type II pneumocytes
regeneration of the alveolar lining following injury and surfactant production
What is the cause of fragile X syndrome?
It is caused by a trinucleotide repeat expansion in the FMR1 gene on the X chromosome, which causes hypermethylation and inactivation.
How does fragile X syndrome present?
-Physical findings (eg, long, narrow face; large testes)
-intellectual disability
-neurobehavorial findings (eg, attention deficit hyperactivity disorder)
Where does Aspergillus fumigatus colonize?
Aspergillus fumigatus, a ubiquitous environmental mold, can chronically colonize old pulmonary cavities (eg, prior tuberculosis), forming a fungus ball (aspergilloma) that does not elicit a significant host immune response and is typically discovered incidentally.
What is the function of the primary somatosensory cortex (postcentral gyrus)?
the primary somatosensory cortex (postcentral gyrus) is responsible for processing all somatic sensory input from the contralateral side of the body
A focal onset seizure originating in the primary somatosensory cortex (postcentral gyrus) results in?
Contralateral sensory disturbance (eg, numbness, paresthesia)
What is the timeframe for separation anxiety?
more than 4 weeks in children
more than 6 months in adults
Reduced aldosterone production in primary adrenal insufficiency leads to what?
Leads to renal sodium wasting with consequent hypovolemia, orthostasis, and potassium retention (hyperkalemia).
Low cortisol stimulates increased antidiuretic hormone secretion, which leads to water retention and hyponatremia
Why do patients on warfarin develop a transient hypercoagulable state?
Patients on warfarin develop a transient hyper coagulable state due to the short half-life of protein C.
This hypercoagulability is further exaggerated by preexisting protein C deficiency and can result in thrombotic occulsion of the microvasculature with skin necrosis.
Strep pneumo infection is the leading cause of what diseases in adults?
-community-acquired pneumonia
-otitis media
-meningitis
How does strep pneumo appear on gram stain?
Lancet-shaped G+ cocci in pairs
Bacterial meningitis will show what in the cerebrospinal fluid?
Increase in CSF neutrophil count and protein concentrations
Decrease in CSF glucose
Clostridium tetani produces what kind of neurotoxin?
Produces the neurotoxin tetanospasmin, which blocks inhibitory neurotransmission in the spinal cord and leads to tonic muscular contraction
How is tetanus prevented?
By immunization with an inactivated toxoid that triggers the production of antitoxin antibodies (active immunity)
How does excessive acetaminophen cause toxicity?
Causes toxicity through its metabolite N-acetyl-p-benzoquinone imine, which disrupts hepatocyte mitochondrial function and induces oxidative injury throughout the liver.
The resulting hepatocellular liver injury markedly elevates aminotransferase, with levels sometimes exceeding 1,000 U/L.
MOA of dobutamine
b-adrenergic agonist with predominant activity on b1 receptors and weak activity on b2 and a1 receptors.
Stimulation of b1 receptors leads to an increased production of cAMP and increasaed cytosolic Ca2+ concentration.
This facilitates the interaction between actin and myosin, resulting in increased myocardial contractility.
Direct inguinal hernias occur due to?
Occur most commonly in older men due to weakness of the transversalis fascia
They protrude medial to the inferior epigastric vessels into the Hesselbach triangle and pass only through the superficial inguinal ring with no direct route to the scrotum
What is the cardiorespiratory response to exercise?
Increased heart rate, cardiac output, and respiratory rate in order to balance the increased total tissue oxygen consumption and carbon dioxide production.
These coordinated adaptions result in relatively constant arterial blood gas values whereas venous oxygen is decreased and venous carbon dioxide is increased
In 90% of individuals, occulusion of the right coronary artery can result in what?
transmural ischemia of the inferior wall of the left ventricle, producing ST elevation in leads II, III, and aVF as well as possible sinus node dysfunction
Occlusion of the proximal left anterior descending artery will result in?
anteroseptal transmural ischemia, with ST elevations in leads V1-V4
Occulusion of the left circumflex artery will produce?
transmural ischemia of the lateral wall of the left ventricle, with ST elevations mainly in V5 and V6, and possibly also in I and aVL
Simvastatin effect on cholesterol
decreases hepatic cholesterol production
Cholestyramine effect on cholesterol
Increases hepatic cholesterol and bile acid synthesis
