Uworld 5 Flashcards
Combination therapy with simvastatin and cholestyramine results in?
synergistic reduction in plasma LDL levels
What is Henoch-Schonlien purpura?
IgA mediated small vessel vasculitis that manifests with palpable purpura on the lower extremities, abdominal pain, arthralgia/arthritis, and renal disease (hematuria +/- proteinuria)
Renal involvement is primarily due to IgA deposition in the mesangium
Timeframe for generalized anxiety disorder
equal/more than 6 months
excessive uncontrollable worry about multiple issues. Symptoms: restlessness, muscle tension, fatigue, sleep disturbance, irritability, and difficulty concentrating
What is primary biliary cholangitis?
Autoimmune disorder that most commonly affects middle-aged women and characterized by fatigue, pruritus, jaundice, cholestasis (eg elevated alkaline phosphatase, elevated gamma-glutamyl transferase, direct hyperbilirubinemia), and antimitochondrial antobodies
Histo finding for primary biliary cholangitis
dense lymphocytic portal tract inflammation with granulomatous destruction of interlobular bile ducts
Where is the most deoxygenated blood in the body?
Myocardial oxygen extraction exceeds that of any other tissue/organ; therefore, the cardiac venous blood in the coronary sinus is the most deoxygenated blood in the body.
Due to the high degree of oxygen extraction, increases in myocardial oxygen demand can only be met by an increase in coronary blood flow
The brachial artery can be injured when what nerve is injured?
Injury to the median nerve at the cubital fossa frequently injures the brachial artery
What is the course of the brachial artery?
The brachial artery runs alongside the median and ulnar nerves in the medial bicipital groove of the upper arm.
Proximal to the elbow, the median and ulnar nerves diverge, and the brachial artery continues with the median nerve through the cubital fossa.
Prolonged exposure to loud noises causes hearing loss due to damage of?
Due to damage to the stereociliated hair cells of the organ of Corti
What is mitochondrial encephalomyopathy?
Ragged red fibers on muscle biopsy and a maternal inheritance pattern
Why is the clinical presentation of mitochondrial encephalomyopathy varied in family members?
Clinical presentation in affected family members varies due to the degree of heteroplasmy, or proportion of mitochondria with normal and mutant genomes in the same cell or tissue
Pufferfish poisoning is caused by tetrodotoxin, a neurotoxin produced by microorganisms associated with the fish. Tetrodotoxin binds what?
Tetrodotoxin binds to voltage gated sodium channels in nerve and cardiac tissue, preventing sodium influx and depolarization
What is a cavernous hemangioma?
Cavernous hemangiomas are vascular malformation composed of abnormally dilated capillaries separated by thin connective tissue septa.
The lack of structural support gives them a tendency to bleed, and those that occur in the brain can present with neurological deficits and seizures
Rapid infusion of vancomycin can lead to what?
Can lead to the direct activation of mast cells, which results in a massive release of histamine. This causes vancomycin infusion reaction, a nonallergic reaction marked by flushing, erythema, and pruritus within seconds or minutes of vancomycin infusion.
Because this reaction is not IgE-mediated, vancomycin can be safely resumed at a slower rate once symptoms have resolved.
What is the first line treatment for obsessive-compulsive disorder?
Selective serotonin reuptake inhibitors
What do familial retinoblastoma patients have an increased risk for?
Familial retinoblastoma occurs as a result of mutations of each of the two Rb genes (“two hits”).
These patients have an increased risk of secondary tumors, especially osetosarcomas, later in life.
How does timolol (nonselective beta blocker) treat open-angle glaucoma?
Diminishing the secretion of aqueous humor by the ciliary epithelium
How does acetazolamide treat open angle glaucoma?
Acetazolamide, a carbonic anhydrase inhibitor) decreases aqueous humor secretion by the ciliary epithelium.
How does prostaglandin F2a (latanoprost, travoprost) and cholinomimetics (pilocarpine, carbachol) treat open angle glaucoma?
Decreases intraocular pressure by increasing the outflow of aqueous humor
What is open angle glaucoma?
Progressive loss of peripheral vision from elevated intraocular pressure
How does congenital syphilis present?
Acquired via transplacental transmission of the spirochete Treponema pallidum.
Present with pain and limited extremity movement due to long bone involvement (eg, metaphyseal erosions, periosteal inflammation).
Nonspecific: hepatosplenomegaly and lymphadenopathy
When do neural tube defects most often occur?
When the neural folds fail to fuse in the region of the anterior or posterior neuropores
An open neural tube defect allows leakage of what?
Leakage of alpha-fetoprotein and acetylcholinesterase into amniotic fluid.
Where is the left kidney in relation to the rib?
The left kidney lies immediately deep to the tip of the 12th rib.
What is a transient ischemic attack?
Transient episodes of focal neurologic impairment that occur due to local brain ischemia; tissue infarction does not occur and brain imaging is normal.
Patients with transient ischemic attacks are at increased risk for? Secondary preventions are?
Increased risk of future stroke.
Secondary preventions: antiplatelet agents (eg, aspirin, clopidogrel), statins, and lifestyle modifications (eg, tobacco cessation, exercise) to reduce future risk.
What is oppositional defiant disorder?
A behavioral disorder of childhood characterized by argumentative and defiant behavior toward authority figures.
It does not involve more severe violations of the basic rights of others seen in conduct disorder.
What is the role of biotin?
Biotin acts as a CO2 carrier on the surface of carboxylase enzymes and is an essential cofactor for numerous reactions, including the conversion of pyruvate to oxaloacetate and fatty acid metabolism.
How does biotin deficieny present?
Mental status changes, myalgias, anorexia, macular dermatitis, and lactic acidosis.
What is the major stimulator of respiration in healthy individuals?
Arterial partial pressure of carbon dioxide (PaCO2).
Even a slight increase in PaCO2 stimulates central chemoreceptors and triggers increased ventilation.
In patients with chronic obstructive pulmonary disease, what happens to the response to PaCO2?
The response to PaCO2 is blunted and hypoxemia can contribute to respiratory drive.
What is responsible for sensing arterial partial pressure of oxygen (PaO2)?
Peripheral chemoreceptors are primarily responsible for sensing arterial partial pressure of oxygen and can be suppressed with oxygen adminstration.
What are the symptoms of Bordetella pertussis?
mild cough and rhinorrhea followed by severe, paroxysmal cough that may be associated with an inspiratory whoop and vomitting.
Traits of bordetella pertussis
G- coccobacillus, most commonly infects unvaccinated/undervaccinated infants and children.
The bacterium is largely noninvasive and secretes several exotoxins that damage ciliated respiratory epithelium
Cancer cells alter expression of genes controlling survival and replication via what mechanisms?
By histone modification, transcription factor expression, and CpG methylation.
What makes tumor cells much more susceptible to alkylating chemotherapy?
Methylation of the CpG region adjacent to the MGMT gene, which produces an enzyme that repairs DNA, makes tumor cells much more susceptible to alkylating chemotherapy.
What is the relation of advanced age and bone marrow?
Patients of advanced age have increased bone marrow fat and reduced bone marrow mass, leading to impaired bone marrow reserve. This results in an inability to rapidly generate new blood cells in response to acute stress (eg, blood loss, hypoxia).
What is the most common inherited bleeding disorder?
Von willebrand disease; which is autosomal dominant
Easy bruising and mucosal bleeding
What are the labs for Von Willebrand disease?
normal platelets, normal PT, and either normal/prolonged PTT due to low levels of factor VIII
What is glucose-6-phosphate dehydrogenase deficiency?
X linked recessive disorder that causes acute hemolysis after exposure to oxidizing meds, foods, or acute infection.
Nearly all affected persons are male, but heterozygous females can become symptomatic due to skewed lyonization.
What is used to treat acute simple cystitis?
Empiric treatment with nitrofurantoin or trimethoprim-sulfamethoxazole
What is acute simple cystitis?
Often occurs in young, otherwise healthy women, particularly following sex.
Common manifestations: dysuria, urinary frequency/urgency, and UA evidence of pyuria/bacteriuria.
What cell is CD40-ligand (CD40L) expressed on?
Expressed primarily on activated T cells.
It binds to CD40 on antigen presenting cells, including B cells, leading to their full activation (costimulation). Therefore, CD40L plays a vital role in both the cell-mediated and humoral immune response.
What are the insulin-independent transporters?
GLUT-1,2,3 and 5 are always present on the plasma membrane and constitutively transport glucose in an insulin-independent manner.
What are the traits of GLUT-4?
Glucose transport protein-4 is an insulin-sensitive glucose transporter expressed in skeletal muscle cells and adipocytes that translocates to the plasma membrane in response to increasing insulin levels.
What is the filtration fraction?
the fraction of plasma flowing through the glomeruli that is filtered across the glomerular capillaries into Bowman’s space (FF=GFR/RPF).
Renal plasma flow can be determined from?
From renal blood flow by multiplying the renal blood flow by (1-hematocrit).
What is a complete hydatidiform mole?
Usually results when an empty ovum is fertilized by a haploid sperm.
Subsequent duplication of the paternal genetic complement (23X) results in the characteristic 46,XX genotype.
Why is pancreatic insufficiency common in cystic fibrosis?
Because thick, viscous secretions in the pancreas block digestive enzymes, leading to malabsorption (eg, steatorrhea, failure to thrive).
What can diagnose pancreatic insufficiency?
The presence of low fecal elastase is an accurate and noninvasive method for diagnosing pancreatic insufficiency
What is the MOA of polyene antifungals (amphotericin B, nystatin)?
They act by binding ergosterol in the fungal cell membrane.
Botulinum toxin blocks what?
Blocks presynaptic exocytosis of ACh vesicles, causing impaired muscarinic and nicotinic neurotransmission.
How does botulinum toxin present?
Symmetric descending paralysis that manifests with cranial nerve abnormalities, often following consumption of home-canned foods.
What is the MOA of glucagon-like peptide-1 agonists? (GLP-1) (exenatide, liraglutide)
slow gastric emptying, suppress glucagon secretion, and increase glucose-dependent insulin release.
These agents cause significant weight loss by suppressing the appetite and increasing satiety.
What are normal morphological changes in the aging heart?
-decrease in left ventricular chamber apex-to-base dimension
-development of a sigmoid-shaped ventricular septum
-myocardial atrophy with increased collagen deposition
-accumulation of lipofuscin pigment in cardiomyocytes.
How does chronic kidney disease cause hyperphosphatemia?
Due to impaired renal excretion of phosphorus. Elevated blood phosphate triggers the release of fibroblast growth factor 23, which lowers calcitriol production and intestinal calcium absorption. The resulting hypocalcemia, along with hyperphosphatemia, leads to secondary hyperparathyroidism.
What is Weber syndrome?
Midbrain infarction due to occlusion of the posterior cerebral artery results in Weber syndrome characterized by ipsilateral oculomotor nerve (CNIII) dysfunction accompanied by contralateral hemiparesis.
The blood testis barrier is formed by?
Tight junctions between Sertoli cells in the seminiferous tubules and prevents immune exposure to the developing spermatids.
During differentiation, spermatozoa pass through the barrier, which reforms behind them.
Disruption to the blood-testis barrier can lead to formation of antisperm antibodies, which can impair fertility.
How does acromegaly affect the joints?
Acromegaly can affect the joints in both the axial and the appendicular skeleton.
Excessive growth hormone and insulin-like growth factor-1 causes hyperplasia of articular chondrocytes and synovial hypertrophy, leading to later degeneration of articular cartilage and periarticular bone.
What is the treatment for rheumatoid arthritis?
The foundation of management for rheumatoid arthritis is disease-modifying antirheumatic drugs, which alleviate pain and inflammation and reduce long-term joint destruction.
However, the response to treatment may take several weeks. Nonsteroidal anti-inflammatory drugs and glucocorticoids can provide rapid symptom relief in the interim.
What is mitral valve prolapse caused by?
Most often caused by defects in connective tissue proteins that predispose to myxomatous degeneration of the mitral leaflets and chordae tenineae.
What is heard on cardiac ausculation for mitral valve prolapse?
Midsystolic click followed by a mitral regurgitation murmur; the click and murmur occur later in systole or disappear completely with maneuvers (eg squatting) that increase left ventricular end-diastolic volume.
What forms the majority of the posterior surface of the heart?
The left atrium and it resides adjacent to the esophagus.
Enlargement of the left atrium can cause what?
Can compress the esophagus and cause dysphagia.
Why lies posterior to the left atrium?
The descending thoracic aorta lies posterior to the esophagus and the left atrium.
This position permits clear visualization of the descending aorta by transesophageal echocardiography, allowing for the detection of abnormalities such as dissection or aneurysm.
What is the murmur for mitral regurgtation?
Blowing holosystolic murmur best heard at the cardiac apex and with radiation to the axilla.
Rheumatic heart disease causes which murmurs?
Mitral regurgitation and mitral stenosis. Commonly seen in patients who grew up in Latin America, Africa, or Asia.
Broca (motor, nonfluent) aphasia results from?
Damage to the inferior frontal gyrus of the dominant hemisphere.
Patients are often frustrated as they understand language but cannot properly formulate the motor commands to write or form words (eg, slow fragmented speech).
Aphasia may be associated with right upper limb and face weakness due to extension of the lesion into the primary motor cortex.
What is the immune cascade responsible for toxic shock syndrome?
Superantigens (eg, toxic shock syndrome toxin) interact with major histocompatibility complex molecules on antigen-presenting cells and the variable region of the T lymphocyte receptor to cause nonspecific, widespread activation of T cells. This results in the release of IL-2 from the T cells and IL-1 and tumor necrosis factor from macrophages.
Proteases (eg elastases) in alveolar fluid are derived from?
Alveolar fluid contains proteases (eg, elastases) that are derived from alveolar macrophages and infiltrating neutrophils. These proteases can cause destruction of terminal lung parenchyma (eg emphysema) when secreted in excess (or if left unchecked by deficient antiprotease activity).
MOA of 5-alpha reductase inhibitors (eg, finasteride, dutasteride)
used in txt of benign prostatic hyperplasia.
They block the conversion of testosterone to dihydrotestosterone; the excess testosterone is then available for conversion to estrogens (eg, estradiol) by aromatase, which can lead to gynecomastia.
What happens when PCSK9 binds to LDL-R?
Binding of proprotein convertase subtilisin kexin 9 to low-density lipoprotein receptor on the hepatocyte cell surface increases degradation of LDL-R, leading to decreased uptake of circulating LDL.
MOA of PCSK9 inhibitors (evolocumab, alirocumab)
Decrease LDL-R degradation, resulting in greater uptake of LDL in the liver and lower circulating LDL levels.
Where is a epidural hematoma?
Blood between the bone and dura mater.
What is injured in an epidural hematoma?
Middle meningeal artery associated with fracture of the pterion region of the skull (often involving the temporal bone).
Patients have transient loss of consciousness followed by a lucid interval before increasing intracranial pressure leads to neurologic deterioration
What is physiologic gynecomastia?
Benign condition caused by a transient proestrogenic hormonal imbalance during midpuberty; it presents in adolescent boys with unilateral or bilateral tender breast enlargement.
Typically self-resolves within a year.
What can reverse methotrexate toxicitity?
Folinic acid (leucovorin); serves as a reduced form of folic acid that does not require the action of dihydrofolate reductase.
What characterizes hyaline arteriolosclerosis?
Homogenous deposition of eosinophilic hyaline material in the intima and media of small arteries and arterioles.
Typically produced by untreated or poorly controlled hypertension and/or diabetes.
What are the distinguishing symptoms of phencyclidine abuse?
Ataxia, nystagmus, and memory loss.
PCP is a hallucinogen that causes dissociative symptoms, agitation, hallucination, and violent behavior.
What is seen on peripheral blood smear for malaria?
Intraerythrocytic, diamond ring-shaped parasites
The blood-brain barrier is formed by?
tight junctions between nonfenestrated capillary endothelial cells that prevent the paracellular passage of fluid and solutes.
The blood-brain barrier permits passage of what?
Only permits passage of substances from the blood to the brain via transcellular movement across the endothelial plasma membrane, which is limited by diffusion or carrier-mediated transport.
The transverse segment of the duodenum travels through a mesenteric fat pad that provides structural support for>
The superior mesenteric artery.
Conditions that deplete mesenteric fat (eg, hypermetabolic states, starvation) may allow the SMA to compress the transverse segment against the aorta, causing progressive abdominal distension and recurrent biliois vomitting (ie, superior mesenteric artery syndrome)
How does subacute (granulomatous, de Quervain) thyroiditis present?
fever, a painful tender goiter, and an elevated erythrocyte sedimentation rate.
Patients initially develop hyperthyroidism due to destruction of thyroid follicles and release of preformed thyroid hormone.
TSH is suppressed due to feedback inhibition on the pituitary; as a result, thyroid metabolic activity and organification of iodine are decreased, and radioactive iodine uptake is low.
What plays a large role in the deleterious cardiac remodeling that occur in heart failure with reduced ejection fraction?
Neurohormones (eg, norepinephrine, angiotensin II, and aldosterone).
ACE inhibitors, angiotensin-receptor blockers, mineralocorticoid receptor antagonists, beta blockers, and angiotensin receptor-neprilysin inhibitors reduce mortality in these patients by reducing neurohormonal-mediated cardiac remodeling.
Tamoxifen can cause?
Tamoxifen has an estrogenic effect on the uterus and can cause endometrial hyperplasia and cancer.
MOA of selective estrogen receptor modulators (eg, tamoxifen, raloxifene)
Competitive inhibitors of estrogen binding to estrogen receptors. They can have agonist or antagonist effects depending on the specific tissue.
What calcium level suggest underlying malignancy?
Serum calcium >13 mg/dL
secretion of parathyroid hormone-related protein (PTHrP), which closely resembles parathyroid hormone at the bioactive amino-terminal region, is a frequent cause of malignancy-related hypercalcemia and is commonly seen with squamous cell carcinomas (eg, lung neck)
What indicates recovery from acute hep B infection?
The presence of anti-Bc and anti-HBs antibodies in the serum without detectable viral antigens
Patients vaccinated against Hep B will have what antibodies?
Anti-HBs antibodies without detectable levels of anti-HBc
Chronic hep B has what antibodies?
persistent levels of HBsAg and HBV DNA in the serum
Epiglottitis causes what?
rapidly progressive respiratory distress and a swollen epiglottis (“thumbprint sign”) on lateral neck x-ray
What is the most common pathogen of epiglottitis?
Haemophilus influenzae (type b), G- coccobaccilus
What is the most common cause of hepatic metastases?
Colorectal cancer due to direct flow from the colon (and superior rectum) to the liver via the portal venous circulation.
What is the binding capacity of carbon monoxide compared to oxygen?
CO binds to hemoglobin with much higher affinity than oxygen, thereby preventing oxygen binding to hemoglobin. It also reduces oxygen unloading from hemoglobin in the tissues.
Carbon monoxide increases what?
Increases carboxyhemoglobin concentrations but does not affect the partial pressure of oxygen and does not precipitate methemoglobinemia
What is greater trochanteric pain syndrome?
An overuse tendinopathy of the gluteus medius and gluteus minimus at their insertion on the greater trochanter of the femur.
Exam shows tenderness over the greater trochanter; pain is reproduced by resisted hip abduction and internal rotation (when the hip is flexed).
The late phase of dermatologic type I hypersensitivity reactions manifests as what?
indurated skin lesion hours after exposure to the allergen due to local tissue damage caused by major basic protein released from eosinophils
Why do type IV hypersensitivity reactions develop over days?
Because of the time needed to produce a cell-mediated immune response
Posterior hip dislocation (ie, femoral head displaced posteriorly from the acetabulum) can occur in motor vehicle collisions in which the knee strikes the dashboard or from falls in elderly patients. On exam, the leg will appear?
Appears shortened and internally rotated, with the hip held in flexion and adduction. The sciatic nerve is vulnerable to injury in posterior hip dislocation.
