Uworld17 Flashcards
What is pulsus paradoxus?
an exaggerated drop (>10mmHg) in systolic blood pressure during inspiration.
It is most commonly seen in patients with cardiac tamponade but can also occur in severe asthma, chronic obstructive pulmonary disease, or constrictive pericarditits
What is the most common cause of urinary tract infection?
E coli, a nitrate reductase producing bacterium.
Dipstick analysis should be significant for leukocyte esterase, nitrites, and a mildly acidic pH
Concentric left ventricular hypertrophy is a common complication of chronic hypertension, characterized by?
uniformly thickened ventricular walls and enlarged cardiomyocytes and nuclei.
The vasoconstrictors angiotensin II and endothelin likely have a prominent role in the development of concentric LVH independent of their effects on blood pressure.
Angiotensin II receptor blockers are more effective than other antihypertensive agents in reducing LVH.
MOA of patiromer
Patiromer is a nonabsorbable cation exchange resin used to treat hyperkalemia.
It binds colonic potassium in exchange for calcium, trapping potassium within the resin where it is then excreted in the feces.
AE: diarrhea, hypokalemia, hypercalcemia, and hypomagnesemia
Lesions of the glossopharyngeal nerve results in?
loss of the gag reflex (afferent limb), loss of sensation in the upper pharynx, posterior tongue, tonsils, and middle ear cavity, and loss of taste sensation on the posterior third of the tongue.
MOA of colchicine
Colchicine is a second line agent for treating acute gouty arthritis.
It inhibits tubulin polymerization and microtubule formation in leukocytes, reducing neutrophil chemotaxis and emigration to sites inflamed by tissue deposition of monosodium urate crystals.
Gastrointestinal mucosal function is also impaired by microtubules disruption, leading to diarrhea and less commonly nausea, vomitting, and abdominal pain
Morphine generates 2 major metabolites that are metabolically active and renally cleared. These metabolites can?
accumulate in the bloodstream of patients with renal dysfunction and lead to opioid toxicity, evidenced by miosis, respiratory depression, and CNS depression.
Which heart chamber composes most of the heart’s anterior surface?
right ventricle.
A deep, penetrating injury at the left sternal border in the 4th ICS would puncture the right ventricle
Infants who do not receive adeqate iron supplementation are at risk for developing iron deficiency, which progresses in stages as total body iron is depleted. The earliest stage involves?
loss of iron in storage (decreased serum ferritin), followed by iron-limited erythropoiesis with decreased serum iron and transferrin saturation.
Frank iron def anemia, involving the classic findings of low hemoglobin, microcytic/hypochromic erythrocytes, and a low reticulocyte, is a late finding.
What is pica?
Pica is the compulsive consumption of a nonfood substance.
It is often associated with iron def anemia, which is common during pregnancy, and other forms of nutritional def (eg zinc)
What is the relationship of nonselective beta blockers and hypoglycemia?
Nonselective beta blockers exacerbate hypoglycemia and mask hypoglycemic symptoms mediated by norepinephrine/epinephrine
What is neurofibromas?
benign nerve sheath tumors composed of cells normally found in peripheral nerves, including neoplastic Schwann cells, as well as non-neoplastic fibroblasts, perineural cells, and mast cells.
Cutaneous neurofibromas often arise from small nerves in the dermis.
What is leptospirosis?
a zoonotic infection caused by the motile spirochete Leptospira.
Transmission primarily occurs when humans come into contact with water contaminated with animal urine during outdoor recreational or occupational activities.
Patients classically have a mild, self limited flulike illness but may develop more serious complications such as renal or hepatic failure
What is anaphylaxis?
an IgE mediated response to an allergen that results in the release of histamine by mast cells and basophils.
Histamine causes widespread physiologic effects, including vasodilation and increased vascular permeability (eg, hypotension), increased catecholamine secretion (eg, tachycardia), and bronchoconstriction (eg wheezing)
What is pseudocholinesterase deficiency?
Succinylcholine is a depolarizing neuromuscular blocking agent used to induce skeletal muscle relaxation; it typically has a very short duration of action due to metabolism by plasma pseudocholinesterase.
Pseudocholinesterase deficiency is an AR disorder that results in the inability to metabolize succinylcholine, leading to prolonged neuromuscular paralysis after drug adminstration.
MOA of DPP-4 inhibitors (eg, sitagliptin)
Glucagon-like peptide 1 (GLP-1),degraded by dipeptidyl peptidase-4 (DPP-4), helps regulate blood glucose by slowing gastric emptying, suppressing glucagon secretion, and increasing glucose-dependent insulin release.
DPP-4 inhibitors (eg, sitagliptin) increase the effects of GLP-1 and improve glycemic control.
Because the effect on insulin is glucose dependent, there is minimal risk of hypoglycemia.
What is familial hypocalciuric hypercalcemia?
a benign autosomal dominant disorder caused by defective calcium sensing receptors in the parathyroid gland and kidneys
What are calcium sensing receptors?
G protein coupled receptors that regulate the secretion of parathyroid hormone in response to changes in circulating calcium levels
What is seen on blood smear for lead poisoning?
Coarse basophilic stippling (dark blue purple granules throughout red blood cells) and hypochromic, microcytic anemia are common peripheral blood smear findings in lead poisoning.
high risk groups: young children ingesting paint chips and industrial workers inhaling particulate lead
How does ascites develop in cirrhosis?
Ascites in cirrhosis develops from hemodynamic changes related to portal hypertension. Splanchnic vasodilation decreases the splanchnic vascular resistance and lowers the effective arterial blood volume, which causes activation of the renin-angiotensin-aldosterone system and promotes sodium and water retention.
Additionally, low oncotic pressure (ie, hypoalbuminemia due to impaired hepatic function) reduces fluid resorption from the interstitium.
Chronic valvular inflammation and scarring associated with rheumatic heart disease predispose to?
an increased risk of infective endocarditis: valvular vegetations with destruction of the underlying cardiac tissue
What are vegetations on the heart caused by?
Vegetations are caused by bacterial colonization and growth on a sterile fibrin platelet nidus that forms on the damaged/disrupted endothelial surface of the valvular apparatus.
What is ectopic pregnancy?
Ectopic pregnancy may present with unilateral lower abdominal pain, adnexal tenderness, and vaginal bleeding.
Patients with a ruptured ectopic pregnancy have severe intraabdominal bleeding, which causes diffuse abdominal pain with rebound/guarding and hemodynamic instability.
What is the definitive diagnosis of chronic myelogenous leukemia?
Chronic myelogenous leukemia and leukemoid reaction can have presentatons similar to leukocytosis; however, leukocyte (neutrophil) alkaline phosphatase level is normal or elevated in a leukemoid reaction but decreased in CML.
The definitive diagnosis of CML requires demonstration of the Philadelphia chromosome t(9;22) or BCR-ABL fusion gene or mRNA.
What is schistosomiasis?
a blood fluke infection that occurs when humans bathe or swim in freshwater that contains contaminated snails.
Adult worms mature in the liver, lodge in the mesenteric venules or vesicular venous plexus, and secrete eggs into feces or urine.
Eggs can trigger granulomatous inflammation, leading to symptoms in the gastrointesterinal, urinary, or periportal tract.
Diagnosis is typically made when round or oval eggs with a terminal or lateral spine are identified in urine, feces, or biospy.
What is a temporal lobe abscess?
A single brain abscess is usually caused by direct spread of a contiguous infection.
Temporal lobe abscess is usually a result of otitis media that has spread to the mastoid air cells, while frontal lobe abscess is usually dye to ethmoid or frontal sinusitis.
Multiple brain abscesses typically indicate hematogenous dissemination of a distant infection (eg endocarditis, empyema)
Hemoglobin is structurally similar to?
The individual subunits of the hemoglobin molecule are structurally analogous to myoglobin.
If separated, the monomeric subunits will demonstrate a hyperbolic oxygen-dissociation curve similar to that of myoglobin
What decreases the transmission rate of rapid impulses generated by the atrial myocardium (eg, atrial fibrillation/flutter)?
The slow inward calcium current within the atrioventricular node decreases the transmission rate of rapid impulses generated by the atrial myocardium (eg, atrial fibrillation/flutter), acting as a conduction rate buffer between the atria and the ventricles
What is factitious disorder?
the intentional falsification of symptoms or induction of illness.
The goal is to assume the patient role, and there is no obvious external reward.
What is reactive (atypical) lymphocytes?
activated, pathogen specific cytotoxic T cells or natural killer cells that form in response to certain intracellular infections.
In contrast to normal lymphocytes, reactive lymphocytes are large, scalloped, and have abundant cytoplasm.
Reactive lymphocytosis is a diagnostic feature of infectious mononucleosis.
What is the location of enhancers and silencers?
Enhancers or silencers may be located upstream, downstream, or within a transcribed gene; these gene sequences function to increase and decrease the rate of transcription, respectively.
In contrast, promoter regions are typically located 25 or 75 bases upstream from their associated genes and function to initiate transcription.
What is chronic hepatitis C virus infection treated with?
With direct-acting antiviral meds such as ledipsavir and sofosbuvir.
These meds target specific HCV enzymes (eg, protease, NS5A, RNA polymerase), which inhibits viral replication and assembly.
Treatment with DAAs results in cure in >97% of patients.
What is phase II clinical trials?
small to medium sized trials conducted with participants having the condition of interest to assess treatment efficacy, toxicity, adverse effects, and optimal dosing strategies; they are sometimes called pilot studies.
What is dextromethorphan?
a popular, OTC antitussive agent that acts on sigma receptors to suppress the medullary cough center.
DXM also has an off target action on serotonin transports and receptors in the CNS.
Overdose or accidental interaction with other serotonergic meds (eg SSRIs, antidepressants) can precipitate serotonin syndrome.
MOA of fusion inhibitors (enfuvirtide)
bind the HIV transmembrane glycoprotein gp41 and prevent it from approximating the viral and host cellular membranes, which prevents HIV penetration into new host cells
What is first line treatment for major depressive disorder with psychotic features?
Electroconvulsive therapy. It is appropriate for severely depressed patients who require rapid intervention (eg, suicidal)
What is negative predictive value?
the probability that an individual does not have a disease given a negative test result.
It is equal to the number of individuals who do not have the disease and who have a negative test result divided by the total number of individuals with a negative test result
NPV= TN / (TN+FN)
What is type 4 renal tubular acidosis?
results from a reduced aldosterone effect on the kidneys and is characterized by hyperkalemia (reduced potassium excretion) and nonanion gap metabolic acidosis (reduced hydrogen excretion in the form of ammonium).
Sodium reabsorption is decreased, leading to decreased total body sodium, but the serum sodium concentration is often unchanged due to the appropriate function of antidiuretic hormone.
Coronary autoregulation is mostly accomplished by?
Coronary autoregulation allows coronary blood flow to be primarily driven by myocardial oxygen demand over a wide range of perfusion pressures (60-140 mmHg).
It is mostly accomplished by alterations in vascular resistance via release of adenosine and nitric oxide in response to myocardial hypoxia.
What is a communicating hydrocele?
results when serious fluid accumulates within the tunica vaginalis in the setting of a patent processus vaginalis.
It presents as a painless swelling that transilluminates on exam
