Uworld2 Flashcards
How does carotid sinus hypersensititivity result in syncope?
Carotid sinus hypersensitivity is a common cause of syncope associated with tactile stimulation of the carotid sinus (eg, shaving).
The syncope results from an exaggerated vagal response stimulated by the carotid baroreceptors, which leads to slowed heart rate and marked peripheral vasodilation with a resulting transient loss of cerebral perfusion.
What is congenital toxoplasmosis treated with?
Sulfadiazine plus pyrimethamine.
These medications work synergistically to inhibit formation of tetrahydrofolate, a necessary cofactor for purine nucleotide synthesis
Prerenal acute kidney injury results from what? What are the lab findings?
Results from renal hypoperfusion (eg, dehydration due to poor oral intake).
Labs: elevated blood urea nitrogen/creatinine ratio (>20:1), low urine sodium (<20 mEq/L), low fractional excretion of sodium (<1%), high urine osmolality and specific gravity, and unremarkable urinalysis.
Vitamin D def in children causes what?
This causes rickets characterized by excessive unmineralized osteoid matrix at the epiphyseal cartilage.
What happens with vitamin D deficiency?
Vitamin D deficiency decreases intestinal absorption of calcium.
Parathyroid hormone secretion increases to maintain plasma calcium, which causes renal phosphate wasting and impaired bone mineralization.
What is the most effective agents for the treatment of hypertriglyceridemia?
Fibrates (eg, fenofibrate)
In patients with severe hypertriglyceridemia, pancreatic lipases can cause toxic levels of free fatty acids to be released within the pancreatic tissue, leading to acute pancreatitis.
What is the MOA of bisacodyl?
Bisacodyl is a commonly used stimulant laxative that stimulates the enteric neurons within the colonic myenteric plexus, thereby increasing peristaltic activity and enhancing colonic motility.
What is focal dystonia?
Focal dystonia is a neurologic movement disorder characterized by sustained, involuntary muscle contraction.
What is seen on muscle biopsy with focal dystonia?
Because these contractions are neurologically mediated, muscle biopsy may not show significant histologic changes, although muscle fiber hypertrophy is often present due to repetitive contractions.
What is the criteria for hospice?
Patients with advanced metastatic cancers or other terminal illnesses and a life expectancy of less than or equal to 6 months should be evaluated for hospice care.
What is leukocyte adhesion deficiency is due to what?
It due to the absence of CD18 antigens, which are necessary for the formation of integrins.
Failure of leukocyte adhesion and migration results in recurrent skin and mucosal infections without purulence, delayed umbilical cord separation, and peripheral leukocytosis.
What does Vitamin A def cause?
It causes night blindness and hyperkeratosis.
Deficiency of this lipid-soluble vitamin can develop in patients with fat malabsorption due to chronic biliary obstruction, exocrine pancreatic insufficiency, or small-bowel resection.
What can cause a traumatic pneumothorax?
Traumatic pneumothorax can involve puncture of either the chest wall (eg, penetrating chest trauma) or the lung (eg, by fractured ribs), allowing air to enter the pleural space.
What are the symptoms from traumatic pneumothorax?
Patients usually experience chest pain and diffuculty breathing. Crepitus, caused by air in the subcutaneous tissues of the chest wall, is often present on PE.
Where is the esophagus located on a CT?
The esophagus is located between the trachea and the vertebral bodies in the superior thorax.
It is typically collapsed with no visible lumen on CT images of the chest.
What is the leading cause of acute exacerbations of chronic obstructive pulmonary disease?
Viral and bacterial respiratory infections. The most common viral pathogens are: rhinovirus, influenza, and respirartory syncytial virus.
An aneurysm of the internal carotid artery can laterally impinge on the optic chiasm. This can cause what?
This can cause ipsilateral nasal hemianopia by damaging uncrossed optic nerve fibers from the temporal portion of the retina.
Hyper-IgM syndrome is usually caused by?
It is usually caused by a defect in CD40 ligand, which prevents B cells from undergoing class-switch recombination.
What are the clinical features of hyper-IgM syndrome?
Clinical features include recurrent sinopulmonary, gastrointestinal (eg, Giardia), and opportunistic infections,
Lab findings include elevated IgM and low/absent IgG, IgA, and IgE.
What is indicative of extramedullary hematopoiesis?
The presence of erythroid precursors in the liver and spleen.
What is extramedullary hematpoiesis?
A condition characterized by erythropoietin-stimulated formation and maturation of blood cells outside of the bone marrow.
It occurs in response to severe chronic hemolytic anemia (eg, beta thalassemia).
Patients with T1DM are increased risk of hypoglycemia because?
Because exogenous insulin will continue to be absorbed from the injection site despite falling glucose levels.
Those with long-standing diabetes may also have decreased glucagon secretion and therefore have an even greater risk of rapid hypoglycemia.
Infective endocarditis in IV drug users commonly affects what heart valve?
Commonly affects the tricuspid valve, often leading to septic pulmonary emboli.
Patietns can have an early- or holo-systolic murmur or tricupsid regurgitation, which is best ausculated in the 4th or 5th intercostal space at the left lower sternal border.
What is the MOA of nitroglycerin?
A venodilator that increases venous capacitance to reduce venous return and shift the vascular function curve to the left.
Alcoholic hepatitis presents how on histo?
Histopathology is characterized by marked intrahepatic neutrophil infilration, hepatocellular ballooning, Mallory bodies, and steatosis.
Typical labs of alcoholic hepatitis?
Elevated aminotransferases with an AST/ALT ratio >2:1
What is the presentation of congenital toxoplasmosis?
It is an infection acquired in utero that can present with hydrocephalus, intracranial calcifications, and chorioretinitis due to prolonged CNS inflammation.
What is the main pacemaker of the heart?
The sinoatrial node is the main pacemaker of the cardiac conduction system, typically initiating electrical impulses at a rate of 60-100/min.
What are the other pacemakers in the heart?
Other parts of the conduction system (eg, atriventricular node, His bundle) have their own intrinsic pacemakers, and they initiate impulses at a slower rate when impulses from the sinoatrial node are blocked.
What is MOA abciximab?
Abciximab is a blocker of glycoprotein (GP) IIb/IIIa receptor, which normally promotes platelet binding to fibrinogen.
What is defective in Glanzmann thrombasthemia?
GP IIb/IIIa.
What is hand-foot-and-mouth disease?
Hand-foot-and-mouth disease is a common childhood illness characterized by painful, vesicular mouth lesions; ulcers on the extremities; and low-grade fever.
It is caused by the ingestion and subsequent dissemination of an enterovirus (eg, Coxsackievirus)
Antidepressants monotherapy should be avoided in what patients?
Patients with bipolar disorder due to the risk precipitating mania.
Supine patients aspirate into which lung lobes?
Due to gravity, supine patients typically aspirate into the posterior segments of the upper lobes and superior segments of the lower lobes.
Patients who are upright will aspirate into what lung lobes?
Patients who are upright tend to aspirate into the basilar segments of the lower lobes.
Aspirated material will travel down which bronchus?
Aspirated material is more likely to travel down the right main bronchus.
Biliary atresia (obstruction of extrahepatic bile ducts) presents with what and on biopsy?
Presents with jaundice, dark urine, and acholic stools in the first 2 months of life due to conjugated hyperbilirubinemia.
Biopsy reveals intrahepatic bile duct proliferation, portal tract edema, and fibrosis.
Traits of enterococcus
Gram+, cocci in pairs and chains and when grown on blood agar, they do not cause hemolysis (gamma-hemolytic)
It is an important cause urinary tract infections.
Patients with cirrhosis complicated by abdominal ascites may develop what?
Hepatic hydrothorax, which is a transudative, usually right-sided pleural effusion that results from passage of intraabdominal fluid into chest cavity through small fenestrations in the diaphragm.
First generations antihistamines will have what kind of effects?
First generation antihistamines are nonspecific and interact with multiple receptors, including the muscarinic receptor. This leads to anticholinergic effects (eg, fever, flushing, mydriasis, urinary retention, tachycardia, altered mental status)
Antibiotics disrupt the normal intestinal flora and can allow for overgrowth of what?
Clostridioides difficile, an anaerobic, gram+, spore forming bacillus.
C. difficile produces 2 toxins that penetrate colonic epithelial cells leading to watery diarrhea, abdominal cramping, and colitis.
What is highly suggestive of a C difficile infection?
The presence of a pseudomembrane (exudate on colonic mucosa consisting of fibrin and inflammatory cells).
Listeria monocytogenes traits
Gram+ rod associated with outbreaks of gastroenteritis via ingestion of contaminated foods (eg, unpasteurized milk, deli meats).
It can cause sepsis in susceptible patients, including neonates, older adults, pregnant women, and immunocompromised individuals.
A drug that binds to and activates GABA-A receptors (or enhances their activity) will do what?
It will increase the conductance of chloride ions, leading to increased passive transport of chloride into the cell interior.
This causes the membrane potential to become hyperpolarized (more negative than the resting membrane potential) by approaching or reaching the equilibrium potential for chloride.
Presentation of tension headache
They are characterized by an achy or pressure-like pain that is often bilateral and associated with pericranial muscle tenderness.
How is leuprolide used to treat prostate cancer?
It is a GnRH agonist. It initially stimulates pituitary LH secretion, which leads to a rise in androgen levels.
However, the GnRH receptor is subsequently down-regulated, which dramatically drops LH release and leads to a long-term decrease in androgen production.
What is naloxone?
Naloxone is a short-acting opiod antagonist used for the treatment of opioid overdose (eg, respiratory depression, decreased level of consciousness, miosis, decreased bowel sounds.)
Naloxone frequently requires redosing to prevent recurrent overdose symptoms due to its short half life (<1 hr).
What is the most common place for an anal fissure?
Anal fissures are longitudinal tears in the mucosa. They are usually due to passage of hard stool in patients with chronic constipation.
Most fissures occur at the posterior midline, likely due to decreased blood flow in this area.
How does primary varicella zoster virus infection present?
Primary varicella zoster virus infection presents with a prodromal illness (eg, fever, malaise) followed by pruritic, vesicular lesions that appear in successive crops in different stages.
When is ADHD diagnosed?
Not until age >4
What is the first line treatment for localized psoriasis?
First-line treatment options for localized psoriasis include high-potency topical corticosteroids and vitamin D analogs.
Vitamin D analogs inhibit T-cell and keratinocyte proliferation and stimulate keratinocyte differentiation.
Corticosteriods also have anti-inflammatory and antiproliferative properties; their MOA is complementary to the vitamin D analogs.
What are the derivatives of the endoderm?
GI tract, liver, and pancreas.
What are nicotinic receptors?
Nicotinic receptors are ligand-gated ion channels that open after binding acetylcholine.
This results in an immediate influx of Na+ and Ca2+ into the cell and an outflux of K+ from the cell.
Membranoproliferative glomerulonephritis typically caused by?
Immune complex deposition within the glomerular capillary walls and mesangium and can be associated with chronic infections (eg. hep B)
Characterized by large, hypercellular glomeruli with thickened capillary walls.
What is on EM and IF for membranoproliferative glomerulonephritis?
IF: granular pattern of IgG and C3
EM: subendothelial and mesangial deposits
What is a branchial cleft cyst? location and result
Branchial cleft cyst are most often located anterior to the sternocleidomastoid muscle and result from incomplete obliteration of a pharyngeal cleft (or groove).
Patients typically have a tender, fluctuant mass (due to secondary infection) with or without purulent drainage.
What are the features of chronic bronchitis?
Thickened bronchial walls, lymphocytic infiltration, mucous gland enlargement, and patchy squamous metaplasia of the bronchial mucosa.
Tobacco smoking is the leading cause.
What is severe combined immunodeficiency?
Caused by a genetic defect in T cell development, leading to loss of both cellular and humoral immunity.
Patients present in infancy with recurrent bacterial, viral, fungal, and opportunisitic infections as well as failure to thrive and chronic diarrhea.
What does the candida antigen skin test assess?
The Candida antigen skin test assesses the activity of cell-mediated immunity because it requires an intact CD4 cell response.
Failure to respond to candida antigen testing is typical in patients with severe combined immunodeficiency.
DNA-binding proteins include what?
-transcription factors (Myc, CREB)
-steroid receptors (cortisol, aldosterone, progesterone)
-Thyroid hormone receptor
-fat soluble vitamin receptors (vit D, retinoid acid)
-DNA transcription and replication proteins
What are gap junctions?
Gap junctions facilitate communication and coordination between cells and play an important role in labor contractions.
Gap junctions are composed of connexin proteins, which are upregulated in the uterus in response to rising estrogen levels.
Ulnar nerve injury most commonly occurs where and presents how?
Ulnar nerve injury most commonly occurs at the elbow (eg, compression due to resting arm on a hard surface for prolonged periods) and usually presents with discomfort and sensory loss and/or paresthesia in the 5th digit, medial half of the 4th, and the hypothenar eminence.
In severe injury, patients can also have impaired wrist flexion and adduction along with finger weakness or clumsiness.
Atopic dermatitis is caused by what?
Atopic dermatitis presents with dry, erythematous patches or papules that are caused in part of a Th2-skewed immune response.
Th2 cytokines (eg IL-4, IL-13) stimulate IgE prodution, suppress epidermal barrier component expression, and impair host immune responses against secondary microbial infections.
What is the Km and Vmax for competitive inhibitors?
Competitive inhibitors compete with substrate for active binding sites on enzymes.
Additional substrate is required to achieve the same rate of reaction, increasing the measured value of the Michaelis constant (Km).
Competitive inhibitors do not affect enzyme function; therefore, maximal velocity (Vmax) is unchanged in their presence.
Herpes zoster ophthalmicus is caused by viral reactivation within what nucleus?
The trigeminal nucleus.
It affects the ophthalmic branch of the trigeminal nerve (CNV1) and can lead to blindness due to acute keratitis because V1 conveys sensory information from the cornea.
MOA of fenoldopam
Selective peripheral dopamine-1 receptor agonist.
It causes vasodilation of systemic and renal arterioles to lower blood pressure while also increasing renal perfusion, urine output, and natriuresis, making it useful in the treatment of hypertensive emergency patients with renal insufficiency.
What is myopia (nearsightedness)?
A refractive error in which the focal point of an image falls anterior to the retina due to an increased anterior-posterior diameter of the eyes.
Patients have difficulty seeing objects at a distance and have normal near vision.
Arginase deficiency results in what?
Arginase is a urea cycle enzyme that produces urea and ornithine from arginine.
Arginase deficiency results in progressive spastic diplegia, growth delay, and abnormal movements.
Treatment: arginine-free, low protein diet
What is neonatal abstinence syndrome?
Caused by infant withdrawal to opiates (eg, heroin) and usually presents in the first few days of life.
Characterized by irritability, a high pitched cry, poor sleeping, tremors, seizures, sweating, sneezing, tachypnea, poor feeding, vomitting, and diarrhea.
What are beta-lactamase inhibitors? Concurrent administration does what?
Clavulanic acid, sulbactam and tazobactam.
Concurrent administration of clavulanate with amoxicillin expands amoxicillin’s spectrum of activity to include strains of B-lactamase synthesizing bacteria that are resistant to amoxicillin alone.
In the HIV replication cycle, polyprotein precursors are encoded by the structural genes gag, pol, and env. Which one is glycosylated?
Only the env gene polyprotein product (gp160) is glycosylated. This polyprotein is subsequently cleaved in the Golgi apparatus to form the envelope glycoproteins gp120 and gp41
Paramesonephric (Mullerian) ducts form what in females?
In females, the paramesonephric (Mullerian) ducts fuse to form the fallopian tubes, uterus, cervix, and upper vagina.
Disruptions in this process can lead to various Mullerian duct anomaloes (eg bicornuate uterus, uterine didelphys).
Renal anomalies are a common comorbidity.
What are the types of strep pneumo vaccines?
Strep pneumo vaccination reduces the risk of invasive disease and is recommended for young patients and the elderly.
The pneumococcal polysaccharide vaccine is an unconjugated vaccine that induces a T-cell independent humoral immune response
The pneumococcal conjugate vaccine contains polysaccharide material attached to a protein antigen, which creates a robust T cell mediated humoral immune response.
Congenital goiter in the setting of hypothyroidism (ie, increase TSH, low thyroxine) is caused by?
Caused by transplacental passage of maternal antithryoid medications (eg, propylthiouracil), which inhibit thyroid peroxidase and are used to treat maternal hyperthroidism.
Renal artery stenosis causing significant renal hypoperfusion will result in what?
A decreased glomerular filtration rate and activation of the renin-angiotensin-aldosterone system.
This leads to increased renin release by modified smooth muscle (juxtaglomerular) cells in the walls of afferent glomerular arterioles.
Chronic renal hypoperfusion can cause hyperplasia of the juxtaglomerular appartus.
Biopsy of polymyositis shows what?
Patchy endomysial inflammatory infiltrate (ie, direct invasion of individual muscle fibers)
-symmetrical proximal muscle weakness and associated with antinuclear and anti-tRNA synthetase (anti-Jo-1) autoantibodies
Biopsy of dermatomyositis shows what?
Perifascicular inflammation (ie, localized around blood vessels and the septa between muscle fascicles)
-symmetrical proximal muscle weakness and associated with antinuclear and anti-tRNA synthetase (anti-Jo-1) autoantibodies
What is used to treat prolactinomas?
Dopamine agonists (eg, cabergoline) are used in patients with prolactin-secreting pituitary adenomas (prolactinomas) to suppress prolactin production and reduce tumor size.
Prolactin is under negative regulation by dopaminergic neurons via the pituitary stalk.
Gross pathology of Crohn disease
Skip lesions, cobblestoning of mucosa, bowel wall thickening and creeping fat.
Type IV hypersensitivity reactions are mediated by what?
T lymphocytes mediate the inflammation in these reactions through cytokine release, CD8+ cytotoxicity, and macrophage recruitment.
How does testicular germ cell tumors cause gynecomastia?
Secretion of hCG by testicular germ cell tumors impairs testosterone production in Leydig cells while increasing aromatase activity and conversion of androgens to estrogens.
The resulting increase in the estrogen/androgen ratio can cause gynecomastia.
What is Jervell and Lange-Nielsen syndrome?
AR disorder; profound bilateral sensorineural hearing loss and congenital long QT syndrome, which predisposes to ventricular arrhythmias and sudden cardiac death.
This condition occurs secondary to mutations in genes that encode voltage-gated potassium channels
What are the pulmonary volumes for COPD?
COPD causes air trapping and hyperinflation; these patients breathe at higher baseline lung volumes (higher functional residual capacity).
The absolute volume of air in the lungs that is not respired (residual volume) increases substantially, as does the fraction of air in the lungs that is not involved in respiration (residual volume/total lung capacity ratio)
Where does Herpes lie latent?
Primary genital herpes (herpes simplex virus type 1 or 2 infx) presents as multiple, grouped vesicles on the genitals that progress to ulcers.
Primary infections can cause systemic symptoms (eg, fever, malaise) and painful inguinal lymphadenopathy.
Because HSV can invade and lie latent in the sacral dorsal root ganglia, patients are at risk for viral reactivation and recurrent genital lesions.
What is progressive multifocal leukoencephalopathy?
Patients with advances AIDS can have reactivation of JC virus, which causes progressive multifocal leukoencephalopathy.
This condition usually presents with progressive confusion, ataxia, and motor deficits.
Brain MRI reveals multifocal areas of white matter demyelination with no mass effect or enhancement.
What are some comorbitites of prolactinomas?
In patients with prolactinoma, high levels of circulating prolatin suppress GnRH secretion from the hypothalamus, leading to reduced secretion of LH and subsequent hypogonadism, anovulation, and amenorrhea.
The resulting estrogen def can cause osteoporosis with an increased risk for fragility fractures, and lead to vaginal dryness and atrophy.
MOA of colchicine and AE
Colchicine inhibits tubulin polymerization into microtubules and can be used for acute treatment and prophylaxis of gout.
Important side effects: nausea, abdominal pain, and diarrhea.
What is adrenal crisis? And the treatment
Patients with adrenal insufficiency are not able to increase glucocorticoid productin in response to acute stress (eg, illness, surgery).
Adrenal crisis: severe hypotension, abdominal pain, vomitting, weakness, and fever.
In addition to aggressive fluid resuscitation, treatment requires immediate glucocorticord supplementation.
What is adenomyosis?
Adenomyosis typically presents with regular (ie, cyclic), heavy, painful menses.
Gross path: uniformly enlarged, globular uterus with the abnormal presence of endometrial glands and stroma in the myometrium.
What is the MOA of budesonide?
Budesonida, like other glucocorticords, reduces inflammation by binding to a cytosolic receptor, translocating into the nucleus, and inhibiting proinflammatory transcription factors such as nuclear factor kappa-B (NF-kB).
It is especially useful in reducting transmural bowel inflammation in patients with Crohn disease because it has high topical potency and limited systemic adverse effects due to its high first pass metabolism.
What is atrial fibrillation? ECG?
Most common cause of an irregulary irregular rhythm.
It often presents with palpitations and is confirmed by ECG showing an absence of organized P waves and irregulary irregular R-R intervals.
What are the changes of pulmonary vascular resistance and systemic vascular resistance after birth?
After birth, pulmonary vascular resistance progressively decreases as systemic vascular resistance progressively increases.
As the relative pressures in the pulmonary artery and aorta change, the murmur associated with ductus arterioles evolves from systolic only to continous before the duct closes, at which time the murmur disappears.
Traits of Actinomyces and treatment
Actinomyces: anaerobic, G+ bacillus with acute angle branching.
It can colonize intrauterine devices (IUDs) and may cause pelvic inflammatory disease (eg, fever, abdominal pain, mucopurulent cervical discharge)
Treatment: IUD removal and Penicillin
What is Neurofibromatosis type 1 due to?
Neurofibromatosis type 1 is a single-gene AD disorder that occurs due to mutation of the NF1 gene located on chromosome 17.
What are the most common manifestations of neurofibromatosis type 1?
Cutaneous neurofibromas, cafe au lait spots, skinfold freckling, and Lisch nodules
What is the most common pineal gland tumor?
Germinomas
How do germinomas present?
Germinomas present with obstructive hydrocephalus and dorsal midbrain (Parinaud) syndrome.
If in the suprasellar region: causes endocrinopathies due to pituitary/hypothalamic dysfunction.
Dactylitis (painful swelling of the hands and feet) is a common presentation of what disease?
Sickle cell disease in young children.
Sickling episodes result in hemolysis, which leads to increased indirect bilirubin and lactate dehydrogenase and decreased levels of haptoglobin.
What antibodies are found in rheumatoid arthritis?
Rheumatoid arthritis results from an immune response directed against autoantigens in the joints.
Infiltrating CD4+T cells secrete cytokines that promote inflammatory synovitis.
They also stimulate B cells to produce rheumatoid factor (IgM antibody specific for Fc component of IgG) and anti-citrullinated protein antibodies that contribute to chronic inflammation and joint destruction.
Graves ophthalmopathy is caused by?
Graves ophthalmopathy is caused by stimulation of orbital fibroblasts by thyrotropin receptor antibodies and cytokines released by activated T cells.
Excess deposition of extracellular glycosaminoglycans and inflammatory infiltration lead to expansion of extraocular muscles and retro-orbital tissues.
