Uworld28 Flashcards
MOA of bisphosphonates (eg, alendronate, risedronate)
inhibit osteoclast-mediated bone resorption.
They have a chemical structure similar to that of pyrophosphate and attach to hydroxyapatite binding sites on bony surfaces.
Bisphosphonates decrease osteoclast recruitment, reduce bone resorption activity, and induce osteoclast apoptosis.
What is a S3?
low frequency sound occuring during early diastole, just after S2.
Left ventricular gallops (S3 and S4) are best heard with the bell of the stethoscope over the cardiac apex while the patient is in left lateral decubitus position at end expiration.
Niacin is a precursor for?
nicotinamine adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), two important cofactors for many dehydrogenase and reductase enzymes.
Niacin deficiency results in pellagra (ie, diarrhea, dementia, and dermatitis)
Urinalysis in patients with Chlamydia trachomatis infection classically shows?
sterile pyuria (positive urine WBCs, no bacteria on gram stain, no growth on culture) because the C trachomatis bacterium is an obilgate intracellular bacterium with minimal peptidoglycan in its cell wall.
The diagnostic test of choice is nucleic acid amplification testing.
What is an important predictor of insulin resistance?
Visceral obesity as measured by waist circumference or waist to hip ratio.
Which anticoagulants is ideal in pregnancy?
Heparins are ideal anticoagulants for most patients with thromboembolic disease in pregnancy as they do not cross the placenta and therefore the risk of fetal bleeding or teratogenicity is low.
Low molecular weight heparin (eg, enoxaparin) is the preferred therapy, with patients transitioned to unfractionated heparin at term.
Side effect of phenytoin?
Gingival hyperplasia is a common side effect of phenytoin and is sometimes reversible when phenytoin is withdrawn.
Phenytoin causes increased expression of platelet-derived growth factor (PDGF).
When gingival macrophages are exposed to increased amounts of PGDF, they stimulate proliferation of gingival cells and alveolar bone.
Phenytoin toxicity mainly affects the cerebellum and vestibular system, causing ataxia and nystagmus.
What is methadone?
a potent, long acting opioid agonist used in the maintenance treatment of opioid use disorder.
Its prolonged effects suppress withdrawal symptoms and cravings.
What is graves disease caused by?
an autoimmune disorder triggered by thyrotopin receptor antibodies (TRAb) that bind and activate the TSH receptor.
Serum TRAb immunoassays have a high sensitivity and specificity for Graves disease.
What is porcelain gallbladder?
a potential manifestation of chronic cholecystitis and is often found in assoication with multiple gallstones.
It is due to dystrophic intramural deposition of calcium salts in the setting of chronic inflammation.
Porcelain gallbladder is associated with an increased risk of adenocarcinoma of the gallbladder.
What is persistent depressive disorder (ie, dysthymia)?
characterized by chronic depressed mood and accompanying depressive symptoms lasting for >2 years.
It can often be differentiated from major depressive disorder by the number of concurrent depressive symptoms (eg, >5 needed for major depression)
What is osteosarcoma?
most common primary bone malignnacy in children and young adults.
It occurs most frequently at the metaphyses of long bones and presents with local pain and swelling.
Most cases are associated with sporadic or inherited mutations in RB1 (hereditary retinoblastoma) and TP53 (Li-Fraumeni syndrome).
MOA of colchicine
used for treatment of acute gouty arthritis in patients who cannot take nonsteroidal anti-inflammatory drugs.
It inhibits leukocyte migration and phagocytosis by blocking tubulin polymerization.
Significant side effects of colchicine include nausea and diarrhea.
What are the cardiovascular manifestations of lupus?
accelerated atherosclerosis, small vessel necrotizing vasculitis, pericarditis, and Libman-Sacks endocarditis (small, sterile vegetations on both sides of the valve)
What are the renal manifestations in lupus?
diffuse proliferative glomerulonephritis, which is characterized by diffuse thickening of the glomerular capillary walls with “wire loop” structures on light microscopy.
Viral bronchioliits is most commonly caused by?
respiratory syncytial virus and presents with low grade fever, cough, and respiratory distress (eg, tachypnea, retractions) in children age <2 years.
Examination typically shows diffuse wheezes and/or crackles.
Anal squamous cell carcinoma is stronly associated with?
human papillomavirus and typically presents with rectal bleeding, pruritus, and/or pain.
Examination demonstrates an ulcerated or nodular, exophytic anal lesion.
Histo: large, eosinophilic, hyperchromatic squamous cells arranged in islands with nuclear atypia and prominent keratinization
The primary anti-ischemic effect of nitrates is mediated by?
Sublingual nitroglycerin is used for rapid symptom relief in patients with stable angina.
The primary anti-ischemic effect of nitrates is mediated by venodilation causing a decrease in left ventricular end-diastolic volume and wall stress, resulting in decreased myocardial oxygen demand.
What is the criteria for Hardy-Weinberg equilibrium?
A population is in Hardy-Weinberg equilibrium when the frequency of alleles at a particular locus remains constant over successive generations within that population.
To satisfy all criteria for the equilibrium, there must be a large population size, random mating, no natural selection, no migration, and no spontaneous mutations.
Reduced ventricular compliance is seen with?
restrictive cardiomyopathy and other causes of diastolic dysfunction and heart failure with preserved ejection fraction (eg, hypertensive heart disease).
It involves ventricular wall thickening and/or stiffening that leads to increased diastolic filling pressure at any given ventricular volume.
Well-differentiated neuroendocrine tumors (ie, carcinoid tumors) arise from?
neuroendocrine cells and are composed of uniform tumor cells with round nuclei, salt and pepper chromatin, and eosinophilic cytoplasm.
Although most are found incidentally (ie, asymptomatic), some may obstruct the lumen, causing acute appendicitis.
What is acute tubular necrosis?
characterized by tubular injury due to renal ischemia or direct cytotoxicity.
The course of the disease takes place in 3 stages: initiation (initial insult), maintenance (oliguric renal failure), and recovery.
During the recovery stage, glomerular filtration rate improves prior to restoration of renal tubular resorptive capacity, so transient polyuria and electrolyte wasting (eg, hypokalemia) can occur.
Function of atrial natriuretic peptide and brain natriuretic peptide
Atrial natriuretic peptide and brain natriuretic peptide are released from the atria and ventricles, respectively, in response to myocardial wall stretch due to intravascular volume expansion.
These endogenous hormones promote increased glomerular filtration rate, natriuresis, and diuresis.
What is Whipple disease?
Whipple disease, caused by the gram+ actinomycete Tropheryma whipplei, is a rare systemic illness that often involves the small intestine, joints, and CNS.
Classic intestinal histo findings include foamy macrophages in the lamina propria with bacilli positive for periodic acid-Schiff stain.
Treatment is with antibiotics.
What are the traits for hep b virus
Hep B virus has a partially double-stranded DNA genome and contains a viral DNA polymerase with reverese transcriptase activity.
Reverse transcriptase serves as a crucial step in viral replication; it converts transcribed positive sense single stranged RNA into the partially dsDNA genome of viral progeny.
Pneumococcal meningitis is associated with?
massive cerebrospinal fluid inflammatory cytokine release in response to bacterial cell wall components.
Treatment with dexamethasone prior to antibiotic therapy has been shown to reduce inflammation and decrease the risk of adverse outcomes (eg, seizures, focal neurologic deficits) and death.
Other forms of bacterial meningitis do not seem to benefit from glucocorticoid treatment.
What is serum sickness?
type III HSR to nonhuman proteins characterized by vasculitis resulting from tissue deposition of circulating immune complexes.
Clinical findings: fever, pruritic skin rash, arthralgias, and low serum C3 and C4 complement levels.
What is seen in 5alpha reductase deficiency?
The enzyme 5-alpha reductase converts testosterone to dihydrotestosterone, which drives development of external male genitalia.
Genotypic males (XY) with 5-alpha reductase def develop female external genitatlia but have internal male genital ducts (eg, vas deferens) instead of internal female genital ducts (eg, uterus)
What is hereditary hemochromatosis?
characterized by excessive intestinal iron absorption with deposition of iron in parenchymal tissues.
Cardiac manifestations include diastolic dysfunction (initial), dilated cardiomyopathy (later) and conduction system disease (eg, sinus node dysfunction)
What is actinic keratoses?
small (usually <1cm), erythematous epidermal lesions with adherent scale that are the result of chronic sun exposure.
Histo: keratinocyte atypia, hyperkeratosis, and parakeratosis.
A small percentage of actinic keratoses progress to invasive squamous cell carcinoma, therefore, frequent monitoring is necessary
Function of small nuclear ribonucleoproteins (snRNPs)
snRNPs are important components of the spliceosome, a molecule which removes introns from pre-mRNA during processing within the nucleus.
Spinal muscular atrophy is a disorder caused by mutations in the SMN1 gene, resulting in impaired assembly of snRNPs in lower motor neurons. Infants often have flaccid paralysis due to degeneration of anterior horn cells in the spinal cord.
The best and most reliable auscultatory indicatory of the degree of mitral stenosis is?
the A2-OS interval. A shorter intercal indicates more severe stenosis.
Other findings can include a diastolic rumbling murmura with presystolic accentuation due to left-atrial contraction.
Sickle cell disease is due to?
the result of a missense mutation in which valine replaces glutamate in the hemoglobin beta-globin chain.
This occurs due to a single nucleotide substitution in DNA, specifically GAG –> GTG
What is the flow of pleural fluid?
Pleural fluid normally enters the pleural space via filtration from the systemic circulation, primarily from the intercostal microvessels of the parietal pleura, and exists the pleural space via stomata in the parietal pleura that drain into the parietal pleura lymphatics.
What causes black pigment stones?
Black pigment stones arise from conditions that increase the amount of unconjugated bilirubin in bile, which promotes calcium bilirubinate precipitation.
This may occur in the setting of chronic hemolysis (eg, sickle cell anemia, beta-thalassemia, hereditary spherocytosis) and increased enterohepatic cycling of bilirubin (eg, ileal disease)
What is conjugation?
Conjugation is a form of horizontal gene transfer that involves the formation of a pilus and the direct passing of genetic material from one bacterium to another.
It is a common source of antibiotic resistance and environmental adaptation.
The other forms of bacterial horizontal gene transfer are transduction (viral vector) and transformation (uptake of free DNA).
What is cytochrome c?
Cytochrome c is a mitochondiral enzyme that activates caspases and indirectly brings about cell death through intrinsic pathway apoptosis.
What is primary (psychogenic) polydipsia?
characterized by excessive intake of free water, leading to hyponatremia and production of larege volumes of dilute urine.
Water restriction normalizes serum sodium levels and increases urine osmolality.
Nonalcoholic fatty liver disease?
frequently develops in patients with metabolic syndrome (eg, obesity, dyslipidemia, insulin resistance) and can progress to cirrhosis due to chroic inflammation and hepatocyte injury.
