Uworld24 Flashcards
Chronic hyperglycemia in patients with diabetes can lead to?
increased permeability and arteriolar obstruction in retinal vessels.
The resulting ischemia stimulates production of vascular endothelial growth factor and other angiogenic factors, leading to neovascularization (proliferative diabetic retinopathy).
Complications include retinal hemorrhage, retinal detachment, and vision loss.
Side effect of tenofovir
Tenofovir is a nucleotide reverse transcriptase inhibitor that is a common component of HIV therapy.
This drug is generally well tolerated by may occasionally cause damage to the proximal tubule of the kidney, leading to acute kidney injury and/or proximal tubule impairment (eg, phosphoruria, glucosuria, proteinuria, water retention).
Biopsy typically reveals a normal glomerulus and renal interstitium but damage to the proximal tubule.
What is the most common cause of syndrome of inappropiate antidiuretic hormone (SIADH)?
Small cell lung cancer is a neuroendocrine malignancy associated with several paraneoplastic syndromes.
It is the most common cause of SIADH due to ectopic secretion of antidiuretic hormone. SIADH is characterized by hyponatremia, decreased serum osmolality, and urine osmolality >100 mOsm/kg H2O)
Which tests is used to monitor warfarin?
Prothrombin time (PT) or International normalized ratio should be monitored regularly during treatment with warfarin.
Warfarin is an oral anticoagulant that inhibits the carboxylation of vitamin K dependent coagulation factors II, VII, IX, and X.
It is used in atrial fibrillation, deep venous thrombosis, and pulmonary thromboembolism.
What is used to monitor unfractionated heparin?
activated partial thromboplastin time (aPTT).
What is erythema multiforme?
target shaped, inflammatory skin lesion that typically arises in the setting of infection, particularly with herpes simplex virus or Mycoplasma pneumoniae.
It is caused by the deposition of infectious antigens in keratinocytes, leading to a strong cell mediated (eg, cytotoxic T-cell) immune response.
What is renal artery stenosis?
Renal artery stenosis is most often due to atherosclerosis.
It can cause severe, refractory hypertension due to activation of the renin-angiotensin-aldosterone system.
Over time, renal atrophy may occur due to chronic oxygen and nutrient deprivation.
Histologic examination may show crowded glomeruli, tubulointerstitial atrophy and fibrosis, and focal inflammatory infilrates.
Where is the most highly oxygenated blood in the fetus?
the umbilical vein, which empties directly into the inferior vena cava via the ductus venosus.
What is REM sleep behavior disorder?
a parasomnia characterized by dream-enactment behaviors due to a loss of atonia during REM sleep.
Patients can usually be awakened fairly easily, are alert and oriented, and can immediately recall their dreams.
Inherited defects involving the interferon-gamma signaling pathway result in?
disseminated mycobacterial disease in infancy or early childhood. Patients require lifelong treatment with antimycobacterial agents.
What is the only manifestation of galactokinase deficiency?
Lenticular accumulation of galactitol in the lenses of patients with galactosemia can cause osmotic damage and development of cataracts.
Cataracts are frequently the only manifestation of galactokinase deficiency.
What is an important adverse effect of nitroprusside?
Cyanide toxicity; blockage of mitochondrial electron transport leads to impaired oxygen utilization, causing lactic acidosis, neurologic dysfunction, and cardiovascular collapse.
What causes schistocytes (helmet cells)?
Schistocytes (helmet cells) are fragmented erythrocytes. They occur secondary to mechanical trauma from microangiopathic hemolytic anemias or prosthetic cardiac valves (macroangiopathic).
Intravascular hemolytic anemias are characterized by decreased serum haptoglobin levels as well as increased LDH and bilirubin.
Diastolic dysfunction typically results from?
Diastolic dysfunction is a common cause of heart failure with preserved ejection fraction.
It typically results from concentric left ventricular hypertrophy in response to prolonged systemic hypertension (ie, increased afterload)
What is the treatment for cryptococcal meningitis?
Patients with suspected cryptococcal meningitis can be diagnosed using India ink staining of the CSF.
Treatment with amphotericin B and flucytosine is required at first, followed by long term fluconazole maintenance therapy.
The chronic myeloproliferative disorders (polycythemia vera, essential thrombocytosis, and primary myelofibrosis) often have a mutation in?
Janus kinase 2 (JAK2), a cytoplasmic tyrosine kinase.
This results in constitutive tyrosine kinase activity, and consequently, in the cytokine-independent activation of signal transducers and activators of transcription (STAT) proteins (JAK-STAT signaling pathway).
What are local adverse effects of chronic topical corticosteroid therapy?
cutaneous atrophy, telangiectasias, and corticosteroid induced acne.
Effects are more pronouced with high-potency corticosteroids and in areas of thin skin (eg, flexural areas)
What is benign neonatal hyperbilirubinemia?
presents with jaundice and elevated indirect bilirubin levels that peak at age 2-5 days.
Pathophysiology includes bilirubin clearance by the liver due to decreased hepatic UDP glucuronosyltransferase, an enzyme responsible for bilirubin conjugation.
What is the role of the Fc fragment of IgG?
Immunoglobulin contains a Fab fragment that binds to antigen and an Fc fragment that activates complement and/or interacts with immune cells.
The Fc fragment of IgG activates the classical complement cascade (constant heavy chain region 2) and serves as a ligand for the Fc receptor on phagocytes (constant heavy chain region 3).
What is schizoid personality disorder?
consists of a persistent pattern of social detachment, preference for solitary activities, and constricted range of affect in social interactions.
What is atrial flutter?
demonstrates rapid and regular atrial activity in a saw-toothed pattern (flutter or F waves) on ECG.
Typically atrial flutter is caused by a large reentrant circuit that traverses the cavotricuspid isthmus of the right atrium, which is the target site for radiofrequency ablation.
What is cavernous sinus thrombosis?
Infection of the medial face, sinuses (ethmoidal or sphenoidal), or teeth may spread through the valveless facial venous system into the cavernous sinus, resulting in cavernous sinus thrombosis.
Patients typically present with headache, fever, proptosis, and ipsilateral deficits in cranial nerves III, IV, VI, and V (ophthalmic and maxillary branches)
What can lower the minimum infectious dose of V cholerae?
Vibrio cholerae must survive the acidic environemnt of the stomach to reach the small intestine and cause disease.
Because the organism is easily destroyed by acid, a high burden of organisms must be ingested to caused infection.
However, condition that decrease gastric acidity (eg, antacid use) lower the minimum infectious dose of V cholerae by multiple orders of magnitude.
What are signs of a patella fracture?
Patella fractures are most commonly due to a direct impact to the anterior aspect of the knee.
Signs include an acutely swollen knee, focal patella tenderness, inability to extend the knee against gravity, and a palpable gap in the extensor mechanism.
What are the steps of base excision repair?
Base excision repair is used to correct single-base DNA defects induced spontaneously or by exogenous chemicals.
In this process, glycosylases remove the defective base, and the corresponding empty sugar phosphate site is cleaved and removed by the action of endonuclease and lyase.
DNA polymerase then replaces the missing nucleotide, and ligase seals the final remaining nick.
How is prostate adenocarcinoma diagnosed?
Prostate adenocarcinoma is generally diagnosed with transrectal prostate biopsy, which often reveals atypical cells with enlarged nuclei and prominent nucleoli forming crowded, infiltrative glands.
What is the hallmark of peroxisomal disorders?
The buildup of very long chain and branched chain (eg, phytanic) fatty acids due to impaired oxidation is the hallmark of peroxisomal disorders (eg, Zellweger syndrome, adrenoleukodystrophy).
Accumulation of these fatty acids in the brain results in permanent neurologic dysfunction.
What are the renal changes during pregnancy?
Pregnancy results in significant plasma expansion and widespread vasodilation, leading to increased renal plasma flow and glomerular filtration rates.
Serum creatinine is reduced by approximately 0.4 mg/dL in this population; therefore, a rise in serum creatinine, even to levels that are normal in nonpregnant patients, represents significant renal dysfunction
Function of sertoli cells?
Sertoli cells produce inhibin in response to FSH from the anterior pituitary. Inhibin suppresses FSH production in the pituitary.
Sertoli cells also facilitate spermatogenesis within the seminiferous tubules.
Impaired Sertoli cell function would lead to decreased production of inhibin, increased FSH levels, and impaired fertility.
What is the relationship with thiazide diuretics (hydrochlorothiazide, chlorthalidone) and calcium?
Thiazide diuretics increase calcium absorption in the distal convoluted tubules within the nephron.
Thiazides are associated with increased bone mineral density and are recommended for treatment of hypertension in patients at risk for osteoporosis.
What is the relationship with calcium and loop diuretics?
Loop diuretics increase urinary calcium loss.
Pulmonary function testing in cystic fibrosis reveals what kind of pattern?
obstructive pattern, characterized by a decrease FEV1/FVC ratio and an increased total lung capacity and residual volume.
Anaphylaxis can cause distributive shock due to?
widespread release of inflammatory mediators (eg, histamine) that leads to massive peripheral vasodilation.
Arteriolar vasodilation decreases systemic vascular resistance to cause hypotension, and venular vasodilation decreases central venous pressure and pulmonary capillary wedge pressure.
Cardiac output is often increased in early distributive shock due to reduced SVR and a baroreceptor reflex-mediated increase in heart rate.
Vesicoureteral reflex typically occurs due to?
due to a congenitally shortened intravesical ureter length, which prevents complete closure of the ureterovesical junction and allows retrograde urine flow into the ureter during micturition.
Most cases resolve spontaneously as the length of the intravesical ureter increases with patient growth.
Thoracentesis should be performed where?
below the 6th rib in the midclavicular line, the 8th rib along the midaxillary line, or the 10th rib along the paravertebral line in order to minimize the risk of lung injury.
Insertion of a needle lower than the 9th rib increases the risk of penetrating abdominal structures.
The needle should also be inserted along the upper border of the rib to prevent injury to the intercostal vessels.
In patients with HIV, the presence of multiple ring-enhancing lesions with mass effect is most often indicative of what?
toxoplasmosis, followed by primary central nervous system lymphoma.
Treatment of toxoplasmosis: pyrimethamine and sulfadiazine
Primary central nervous system lymphoma is typically composed of?
B-lymphocytes
Chronic pancreatitis may cause vitamin B12 deficiency due to?
decreased production of pancreatic proteolytic enzymes (eg, exocrine insufficiency), which are needed to release vitamin B12 from R protein.
Other manifestations of chronic pancreatitis include chronic epigastric pain, weight loss, and steatorrhea.
How is a highly lipophilic drug be distributed within the body?
Following intravenous administration, a highly lipophilic drug will be rapidly distributed to organs with high blood flow (eg, brain, liver, kidneys, lungs).
The drug is then redistributed to tissues with relatively lower blood flow (eg, skeletal muscle, fat, bone). This accounts for the short duration of action of many commonly used anesthetics, such as propofol.
