Potpourri UWorld Flashcards
5 factors that affect molecular rate of diffusion across a semipermeable membrane
Inversely proportional to molecular weight and membrane thickness. Proportional to particle concentration, surface area and solubility of the substance.
A patient presents with fever, lymphadenopathy, a skin rash and facial edema a few weeks after starting a new medication. What medications can cause this condition?
The patient has DRESS syndrome (drug reaction with eosinophilia and systemic symptoms). Common drugs that cause this are allopurinol, anticonvulsants, sulfonamides and antibiotics.
Target organs affected by alpha-1 stimulation?
Peripheral vasculature (vasoconstriction), bladder (contraction of internal urethral sphincter) and eye (mydriasis from pupillary dilator contraction)
Target organs affected by beta-1 stimulation?
Heart (increased contractility, chronotropy and conductance) and juxtaglomerular cells
Target organs affected by beta-2 stimulation?
Peripheral vasculature (vasodilation), bronchodilation and uterine relaxation.
Cytogenic results in a patient with fragile X syndrome.
X-linked mutation of the FMR1 gene results in CGG trinucleotide repeats. This results in cytogenic studies showing a gap at the end of the long arm of chromosome X because the CGG expanded region does not stain when cultured in folate deficient media.
A newborn child of a mother with IV drug use presents with tachypnea, crying, sneezing and diarrhea 2 days after birth. How do you treat this child?
The child has neonatal abstinence syndrome, best treated with opiate replacement and gradual weaning.
How does IgA protease help out bacteria like N. meningitides, N. gonorrhoeae, S. pneumo and H. influenzae?
IgA typically binds to capsular antigens like fimbriae that typically allow for bacterial adherence. IgA protease cleaves IgA and allows for increased adherence to mucosal surfaces.
A 7 year old boy presents with facial hair, paralysis of upward gaze and convergence. MRI shows obstructive hydrocephalus. What is likely causing his condition?
A beta-hCG-secreting pineal germinoma.
Lateral medullary syndrome
Contralateral loss of pain and temperature sensation with ipsilateral loss of CN V, IX, X and XI function.
Medial medullary syndrome
Contralateral spastic paralysis and ipsilateral flaccid paralysis of the tongue (CN XII)
Consequence of common peroneal nerve injury?
Foot drop due to paralysis of peroneus longus, peroneus brevus, tibialis anterior and extrinsic toe extensors. There is also numbness along the anterolateral leg and dorsal foot.
Consequence of superficial peroneal nerve injury?
Poor eversion due to paralysis of peroneus longus and peroneus brevis and loss of sensation along the distal anterolateral leg. However, dorsiflexion is preserved because the deep peroneal nerve innervates the tibialis anterior.
What diseases result in metabolic impairments in glycogenolysis?
Type I (von Gierke disease): deficiency in the conversion of Glc-6-P to Glc by Glc-6-Phosphatase. This results in fasting hypoglycemia, lactic acidosis, hyperuricemia, hyperlipidemia, STEATOSIS and hepatomegaly.
Type II (Pompe disease): deficiency in acid maltase, resulting in inability to degrade glycogen in lysosomes. This results in normal blood glucose, severe cardiomegaly and GLYCOGEN ACCUMULATION IN LYSOSOMES.
Type III (Cori disease): deficiency in debranching enzyme resulting in accumulation of abnormal glycogen with short outer chains (limit dextrins), WEAKNESS AND HYPOTONIA, ketotic hypoglycemia and hepatomegaly.
Type V (McArdle disease): deficiency in muscle phosphorylase resulting in inability to phosphorylate glycogen causing weakness with exercise and LOW POST-EXERCISE BLOOD LACTATE and MYOGLOBINURIA.
Mechanism of opioid-induced hyperalgesia
Chronic mu receptor stimulation causes increased turnover of inhibitory opioid receptors, decoupling of receptors from second messenger system and upregulation of NMDA receptors.
Type of orbital fracture that may impair corneal reflex
Those affecting the superior orbital fissure because CNs III, IV, V and VI pass through here and the corneal reflex involves V1 sensation and VII motor action.
Physical exam findings suggestive of an orbital floor fracture?
Limited superior gaze due to inferior rectors entrapment and numbness of the upper cheek, lip and gingiva due to damage to the infraorbital nerve that normally runs along the floor of the orbit (V2).
1st line treatment of patients with disorders involving the urea cycle?
Protein restrict so the patient gets the AAs they need while minimizing ammonia production.
A 17 year old baseball player presents with upper extremity numbness, tingling and weakness in his right hand. He also complains of pain in exertion only in his right arm and right arm swelling. What is most likely causing his condition?
Thoracic outlet syndrome. The thoracic outlet is the space behind the clavicle and above the first rib and compression of the brachial plexus, subclavian vein and subclavian artery can occur with anterior or middle scalene muscle abnormalities, anomalous cervical rib or repeat overhead injuries.
What test has PYR-positivity replaced
Bacitracin resistance test to determine S. pyogenes (sensitive) from S. agalactiae (resistant)
What is the microbial differential for patients with necrotizing fasciitis?
S. pyogenes, S. aureus and C. perfringens.
What 3 cell types are contained in the juxtaglomerular apparatus?
Macula densa: tall narrow cells in the distal tubule that monitor flow rate and [Na] and send signals to juxtaglomerular cells.
Juxtaglomerular cells: modified smooth muscle cells in the afferent arteriolar wall that secrete zymogen granules in response to macula densa stimulation.
Extra-glomerular mesangial cells
Lymph nodes that receive lymphatic drainage from testes
Para-aortic
Lymph nodes that receive lymphatic drainage from glans of penis and superficial inguinal nodes
Deep inguinal nodes
Lymph nodes that receive lymphatic drainage from the scrotum
Superficial inguinal nodes
An immunocompromised patient presents with sinusitis and fungal hyphae that branch at acute angles with septations.
Aspergillus
An immunocompromised patient presents with sinusitis and fungal hyphae that branch at wide angles without septations.
Rhizopus species -> mucormycoses
What is the main virulence factor involved in E. coli-related meningitis
K1 capsular polysaccharide. It prevents phagocytosis and complement-mediated lysis.
Mechanisms of LPS-induced shock
Widespread cytokine release of IL-1, IL-6 and TNF-alpha
Main virulence factor involved in E. coli related blood diarrhea
Verotoxin (shiva-like) -> 60S inactivation -> cell death due to decreased protein synthesis
Main virulence factor involved in E. coli related watery diarrhea
Heat stable/labile enterotoxins promote fluid and electrolyte secretion from intestinal epithelium.
Main virulence factor involved in E. coli related UTI
P. fimbria allow for adherence to urogenital epithelium
Gram-positive, catalase-negative, alpha-hemolytic, optichin-sensitive and bile soluble.
S. pneumoniae
Gram-positive, catalase-negative, alpha-hemolytic, optichin-resistant and bile insoluble
S. viridans
Gram-positive, catalase-negative, beta-hemolytic, PYR-positive and bacitracin sensitive.
S. pyogenes
Gram-positive, catalase-negative, beta-hemolytic PYR-negative and bacitracin resistant.
S. agalactiae (GBS)
Gram-positive, catalase-negative, gamma-hemolytic, PYR positive, grows in bile and 6.5% NaCl.
Enterococci
Gram-positive, catalase-negative, gamma-hemolytic, PYR negative, grows in bile but not in 6.5% NaCl.
S. bovis
Why do patients with phenylketonuria have a mousy odor and poor pigmentation?
Excess Phe inhibits synthesis of melanin, causing poor pigmentation. Accumulation of abnormal Phe metabolites contributes to the mousy odor.
Enzyme deficiency in maple syrup urine disease
Branched chain ketoacid dehydrogenase deficiency results in an inability to decarboxylate the alpha-ketoacid derivatives of Leu, Ile and Val.
Enzyme deficiency that may result in ptosis, orthostasis, hypoglycemia and hypothermia.
Dopamine hydroxylase deficiency results in poor conversion of dopamine to norepinephrine and dysautonomia.
Enzyme deficiency resulting in excess accumulation of homogentistic acid, connective tissue hyper pigmentation and degenerative joint disease
Homogentistic acid dioxygenase -> poor tyrosine degradation -> Alkaptonuria
Enzyme deficiency that commonly causes albinism
Tyrosinase inactivity leads to poor conversion of tyrosine to DOPA and dopaquinone in the synthesis of melanin.
Histopathology of gynecomastia
Ductal epithelial hyperplasia surrounded by dense stromal fibrosis.
Mechanisms of gynecomastia
Increased aromatase activity: obesity & cirrhosis
Increased LH secretion: hyperthyroidism
Decreased testosterone production: CKD, androgen deprivation therapy, spironolactone
Decreased estrogen clearance: cirrhosis
Hormonal sequence resulting from water deprivation
ADH release -> V2 stimulation on principal cells in collecting duct -> aquaporin-2 insertion into apical membrane -> increased H2O reabsorption at collecting duct
Region of the nephron with the lowest osmolarity
Distal convoluted tubule, it is relatively impermeable to water and immediately follows NaCl loss from the ascending loop of Henle. Osmolarity in this region is typically ~ 100.
G-protein coupled receptors associated with the different adrenergic receptors? Cholinergic receptors? Dopaminergic receptors?
Alpha-1 = Gq -> activation of phospholipase C -> DAG & IP3 formed from membrane degradation -> PKC activated by DAG, Ca release from sarcoplasmic reticulum from IP3 Alpha-2 = Gi -> inhibition of adenylyl cyclase Beta-1 = Gs -> activation of adenylyl cyclase -> increased cAMP -> PKA Beta-2 = Gs
M1 = Gq M2 = Gi M3 = Gq
DA1= Gs -> increased cAMP DA2 = Gi
What infections can result in brown-pigmented gallstones?
Infections in the biliary tract that release beta-glucuronidase from injury of hepatocytes and bacterial secretion. The beta-glucuronidase hydrolyzes bili glucuronides and leads to elevated levels of unconjugated bilirubin. Infections that can do this include E. coli, ascaris and opisthorchis.
Most effective medication for reducing triglycerides
Fibrates. They activate PPAR-alpha -> increased lipoprotein lipase activity
How do corticosteroids affect the WBC?
Increased PMNs (mobilization of marginated pool) and reduction of lymphs (T > B reduced within minutes), monos, basos and eos.
Cause of ataxia-telangectaisa
AR mutation in the ATM gene, which is responsible for DNA breakdown and repair. Common manifestation of disease is recurrent pulmonary infections and IgA deficiency.
Cause of Niemann-Pick disease
AR mutation in sphingomyelinase that causes accumulation of sphingomyelin in monocytes leading to HSM, anemia, areflexia, a macular cherry red spot and early death in childhood.
When is beta-hCG first detectable in maternal serum?
8 days. Around days 4-5 the blastocyst forms. Day 6 it implants and differentiates into the cytotrophoblast and syncytiotrophoblast. The syncytiotrophoblast is what invades the endometrium and starts secreting beta-hCG, levels will rise to detectable levels by day 8.
Side effects to be aware of when prescribing a diabetic canagliflozin?
SGLT-2 inhibits increase urinary [glucose] significantly. Urinary mycotic infections and symptomatic hypotension from osmotic diuresis are the most significant side effects. SGLT-2 inhibitors are contraindicated in patients with moderate to severe renal insufficiency.
How do the insulin secretagogues work?
Sulfonylureas and metaglinides inhibit the K+ ATP channels in beta cells to increase insulin secretion.
How do the biguanides work?
They simulate AMPK activity and reduce peripheral tolerance and glucose production.
Mechanism of and side effects to watch out for with pioglitazone.
Thiazolidinediones work by activating PPAR-gamma and reduce insulin resistance, but can cause worsening of heart failure due to fluid retention.
Mechanism of and side effects to watch out for with exenatide and liraglutide.
GLP-1 agonists delay gastric emptying, increase glucose-dependent insulin secretion and decrease glucagon secretion. Look out for pancreatitis.
Mechanism of and side effects to watch out for with sitagliptin and saxagliptin.
DPP4 inhibitors increase endogenous GLP and GIP levels. Look out for nasopharyngitis.
Mechanism of and side effects to watch out for with acarbose and miglitol?
Alpha-glucosidase inhibitors reduce intestinal absorption of carbohydrates. Look out for diarrhea and flatulence.
Endoderm gives rise to…
Respiratory epithelium, biliary tree, pancreas, GI epithelium and bladder epithelium.
Mesoderm gives rise to…
Dermis, bone, muscle, blood vessels and most visceral tissue.
Neurectoderm gives rise to…
CNS, pre-ganglionic autonomic neurons, retina and posterior pituitary.
Ectoderm gives rise to…
Skin, lens of the eye, anterior pituitary and mammary glands.
Stains used to diagnose cryptococcal meningitis
Mucicarmine and methenamine silver staining
Where on IgG do antigen and complement bind?
Antigen binds to the Fab “Y” region. C1 binds to Fc region near the hinge point after Ig binds antigen.
Why is IgM so much better at activating complement than IgG if they have the same complement binding site?
IgM circulates in its pentameric form and IgG circulates in its monomeric form.
Renal plasma flow calculation? How do you get the renal blood flow calculation?
Renal plasma flow = (urine[PAH] x urine flow rate) / plasma[PAH]
Renal blood flow = renal plasma flow / (1 - Hct)
What is the filtration fraction
GFR:Renal plasma flow. i.e. the amount of plasma filtered by the glomerulus relative to the amount of plasma that comes through the capillaries.
ACL attachment on the tibia
Anterior intercondylar fossa
Biceps femoris insertion site
Styloid process of head of the fibula
5 types of DCIS
Comedocarcinoma: solid sheets of highly pleomorphic cells with central necrosis. Solid Cribriform Papillary Micro papillary
p53 gene function
Tumor suppressor gene that causes G1 arrest if there are molecular abnormalities detected in the genome. If the damage is irreparable, p53 induces apoptosis
Result of chromosome 9;22 translocation
Bcr-abl fusion results in constitutively active tyrosine kinase, cellular proliferation and inhibition of apoptosis resulting in CML.
Ras gene function
Ras is a proto-oncogene in the MAP-kinase pathway that increases cellular sensitivity to mitogenic stimuli.
Obturator innervations
MOTOR: obturator externus, the posterior branches innervate the thigh adductors (magnus, longus and brevis)
SENSORY: the anterior division provides sensation for the distal medial thigh
Nerve that mediates thigh abduction? Thigh extension?
Superior gluteal nerve, it innervates gluteus medius, gluteus minimus and tensor fascia lata. Thigh extension = inferior gluteal nerve’s innervation of gluteus maximus.
Most common subtype of primary CNS lymphoma in patients who are immunocompromised
Diffuse large B-cell lymphoma, CD20+ and CD79a+
Mutations that increase the risk of developing a pheochromocytoma
VHL, RET and NF1
Pheochromocytoma rule of 10’s
10% extra-adrenal (paraganglioma), 10% bilateral and 10% malignant
How do oral contraceptives minimize hirsutism in patients with PCOS?
They suppress LH release from the pituitary, decreasing ovarian androgen production. They also increase SHBG production by the liver.
Why does H+ increase O2 dissociation from hemoglobin?
They hang around the histidine residues on Hgb, stabilizing Hgb in the taut state and facilitating unloading of O2 (Bohr effect)
Haldane effect
Increasing pO2 results in unloading of CO2 and H+.
Hawthorne effect
Changing one’s behavior as a result of knowing you are being observed
Post-strep GN cause of glomerular injury and biopsy characteristics.
Anti-strep abs cross react with glomerular basement membrane.
IF = granular C3 staining along GBM
EM = subEPIthelial humps
Anti-GBM cause of glomerular injury and biopsy characteristics
Anti-type IV collagen abs attack GBM.
IF = linear IgG and C3 staining along GBM
LM = glomerular crescents
Rapidly progressive glomerulonephritis cause of glomerular injury and biopsy characteristics
Severe immunologic injury (anti-GBM, immune complex depositions)
IF = fibrinogen in crescents
LM = glomerular crescents
IgA glomerulonephropathy cause of glomerular injury and biopsy characteristics
IgA complex deposition
IF = IgA in mesangium
LM = mesangial hypercellularity
Alport syndrome cause of glomerular injury and biopsy characteristics
Defective congenital type IV collagen -> BM splitting
EM = lamellated appearance of GBM
Biopsy characteristics of membranoproliferative glomerulonephritis
LM = lobular glomeruli with increased mesangial matrix, BM splitting with silver or PAS stain IF = granular deposits
Focal segmental glomerulosclerosis biopsy results
IgM and C3 deposits in sclerotic regions of glomerulus
Enzyme needed to break down lactose into glucose and galactose.
The intestinal brush border enzyme disaccharidase
Drug used for treatment of wet macular degeneration?
Ranibizumab or bevacizumab (VEGF inhibitors). Patients with dry MD should receive zinc as an antioxidant to prevent drussen accumulation, ischemia, increased VEGF release and progression to wet MD.
Speed of hemoglobin movement in gel electrophoresis
HgbA (most negatively charged) > HgbS > HgbC (least negatively charged due to lysine substitution for glutamate)
HbS mutation
Non-polar valine amino acid replaces a negatively charged glutamate in the beta chain.
How do Na, K, Cl and Ca equilibrate when their respective channels are opened at physiologic conditions (membrane potential -70mV)
SODIUM: extracellular gradient flows into cell with starting equilibration potential of +60mV.
POTASSIUM: intracellular gradient flows out of cell with starting equilibration potential of -90mV.
CHLORIDE: extracellular gradient drives Cl- into the cell with starting equilibration potential of -75mV.
CALCIUM: extracellular gradient drives Ca2+ into the cell with a starting equilibrium potential of +125mV.
Colchicine mechanism of action
Inhibition of PMN microtubules prevents their translocation to the site of infection
Pathophysiology of Duchenne muscular dystrophy
X-linked recessive mutation in dystrophin gene resulting in myonecrosis and replacement with fibrofatty connective tissue.
How does cortisol exert its action on target cells?
It diffuses through the plasma membrane, binds to the cortisol receptor that is attached to a heat shock protein, the heat shock protein dissociates, two cortisol receptors bound by cortisol dimerize, the dimer translocates to the nucleus and modifies gene transcription.
How does glucagon exert its action on target cells?
G-protein coupled receptor
How does growth hormone exert its action on target cells?
Membrane bound receptors that result in activation of the JAK-STAT pathway
Ribavirin mechanism of action
1) It is phosphorylated and incorporated into RNA-dependent RNA replication and pairs with U and C
2) Ribavirin triphosphate directly inhibits HCV RNA polymerase
3) Ribavirin monophosphate inhibits intracellular inosine monophosphate dehydrogenase, depleting intracellular cGMP
4) Prevents viral RNA translation by inhibiting RNA guanylyl transferase and methyltransferase from forming an effective 5’ cap on mRNA
5) Enhances Th1 cell-mediated immunity and inhibits Th2 cytokine production
Raltegravir mechanism of action
HIV integrase inhibition, preventing integration of viral genes into host DNA
Indinavir mechanism of action
HIV protease inhibition
Amantadine mechanism of action
Prevents uncoating of influenza A virion after endocytosis
Enfuvirtide mechanism of action
HIV fusion inhibitor
Neurons that mediate the stretch reflex
Intrafusal fiber -> 1a sensory axon -> synapses on spinal cord alpha motor neuron -> contraction
Neurons that prevent muscular damage when too much force is exerted in a muscle
Golgi tendon oran -> 1b sensory axon -> synapses on inhibitory spinal interneuron -> inhibits spinal cord alpha-motor neuron -> sudden relaxation
A-delta sensory fibers communicate what stimuli?
Sharp pain and temperature. Myelinated fibers transmit touch, proprioception and vibration from Pacinian and Ruffini corpuscles.
Pacinian corpuscles communicate what stimuli?
Rapidly adapting mechanoreceptors (touch, proprioception and vibration), located in subcutaneous tissue, mesentery, peritoneum and joint capsules.
Ruffini corpuscles communicate what stimuli?
Slowly adapting mechanoreceptors (touch, proprioception and vibration), located in subcutaneous tissue and joints.
Giant cell arteritis histology
Granulomatous inflammation of media and fragmented internal elastic lamina in arteries of the head and neck.
How can you differentiate acute precursor T-cell ALL from acute precursor B-cell ALL?
Precursor B-ALL: TdT+, CD10 and almost always CD19
Precursor T-ALL: TdT+, +/- CD1a, CD2, CD3, CD4, CD5, CD7 or CD8
Diagnosis in a patient with enlarged, non-tender cervical lymph node that showed cells with abundant cytoplasm, bilobed nuclei and inclusion-like eosinophilic nucleoli
Reed-Sternberg cells -> Hodgkin lymphoma
What is responsible for the atypical lymphocytes seen in EBV infection?
EBV binds CD21 on B-cells and infects them. The atypical cells are T-cells that underwent clonal expansion and kill infected B-cells.
What makes up the class I and II MHC molecules
MHC I: Beta-2 micro globulin and a heavy chain
MHC II: alpha and beta polypeptide chains
Lab findings associated with post-strep glomerulonephritis
Elevated ASO titers, anti-DNase antibodies, presence of cryoglobulins and decreased C3 and total complement levels (C4 is typically normal).
Most common visual change in a PCA stroke
Contralateral hemianopia with macular sparing due to collateral circulation from MCA
Consequence of a stroke in the artery of Percheron
Bilateral thalamic or dorsal midbrain strokes
Pathophysiology behind maple syrup urine disease
Defective breakdown of branched chain amino acids (leucine, isoleucine, valine) due to non-functioning branched chain alpha-keto acid dehydrogenase.
Differences between enhancers/repressors and promotors of DNA transcription?
Promotors: TATA box is 25 nucleotides upstream from the start codon and facilitates RNA polymerase II and transcription factor binding. The CAAT box has a similar function and is 70 base pairs upstream.
Enhancers/repressors: can be located anywhere and increase or decrease the rate of transcription initiation
Power of a study
Probability of seeing a difference in your study when there truly is one present:
1 - probability of making a type II error (concluding there is no difference when there truly is one)
Type I error
Probability that you would see a difference when there really is not a difference…correlates with the p-value
Phases of acute tubular necrosis
Initiation: ~36 hours, mild drop in urine production as renal tubules begin to be damaged.
Maintenance: 1- 2 weeks, oliguria, reduced GFR, biopsy shows epithelial necrosis, tubular BM, casts with debris
Recovery: GFR recovers as the tubules re-epithelialize, tubules are slower to start recovering solutes, resulting in polyuric phase
Blood supply to the heart
LAD: anterior 2/3 of inter ventricular septum, anterior LV wall and anterior papillary muscle
LCX: lateral and posterior superior walls of LV
RCA: posterior (via acute marginal branches) and inferior heart (via posterior descending artery)
Bioavailability
Fraction of drug that reaches systemic circulation unchanged
Area under oral curve x IV dose)/(area under IV curve x oral dose
Disaccharide breakdown
Sucrose: fructose + glucose
Lactose: galactose + glucose by brush border enzyme lactase (beta-galactosidase)
Maltose: glucose + glucose
Pathophysiology of hereditary fructose intolerance
Aldolase B deficiency results in decreased conversion of fructose-1-P to DHAP and glyceraldehyde. Excess fructose-1-P results in intracellular phosphate depletion, inactivation of hepatic phosphorylase and reduced gluconeogenesis.
Impaired gluconeogenesis results in severe hypoglycemia after eating sucrose or fructose (fruit or formula). Infants are typically find while breastfeeding because breast milk contains mostly maltose and lactose.
Babies that present in the first few days of life with vomiting, jaundice, poor feeding and hepatomegaly may have what problem?
Galactosemia with reduced galactose metabolism.
How does leucovorin have a different effect when paired with methotrexate vs. 5-FU?
With methotrexate, it results in rescue of cellular replication because it is a tetrahydrofolate derivative and replenishes depleted tetrahydrofolate from MTX inhibition of tetrahydrofolate reductase.
With 5-FU, thymidylate synthase requires tetrahydrofolate in order to bind 5-FU and leucovorin potentiates the effects of 5-FU, reducing cellular replication.
Strep pyogenes major virulence factor
Protein M: inhibits phagocytosis and complement activation. It is also cytotoxic to PMNs and promotes bacterial aggregation.
Hormone levels seen in patients with Klinefelter’s
These patients typically have absent Sertoli cells, resulting in no production of inhibin and increased FSH levels.
They also have reduced Leydig cell function, resulting in reduced testosterone production and increased LH and GnRH levels.
Why do patients who use steroids develop small testes?
Exogenous testosterone levels inhibit LH release from the pituitary. This results in decreased testosterone production by Leydig cells and atrophy of local seminiferous tubules.
Treatment of restless leg syndrome
Limit exposure to aggravating factors (SSRIs, Li, glucocorticoids), supplement iron if anemic and dopamine agonists if needed (ropinirole or pramipexole)
Causes of splenomegaly
Increased white pulp mass from increased antibody production, B-cell affinity maturation or removal of opsonized material.
Increased red pulp mass from increased removal of RBCs or sinusoidal dilation from portal hypertension
Why would someone with pyruvate kinase deficiency have an enlarged spleen?
RBCs do not have mitochondria and any deficiency in glycolysis results in insufficient ATP generation for the RBC and inability to maintain the RBC membrane. This results in splenic sequestration of damaged RBCs.
Why give diuretics and beta blockers when prescribing hydralazine or minoxidil?
They prevent the reflex sympathetic activation resulting in tachycardia, increased contractility and renin activation leading to Na+ retention and edema.
How do glucocorticoids increase blood sugar levels?
They increase formation of gluconeogenic enzymes PEP carboxylase and glc-6 phosphatase. They increase glycogenesis by increasing formation of glycogen synthase. Finally, they inhibit insulin’s peripheral effect on muscle and fat, resulting in catabolism of these tissues to generate substrates for glycogenesis and gluconeogenesis.
A patient presents with acute, painless monocular vision loss and a cherry red macula. What is causing his condition?
Central retinal artery occlusion
Calculate PAO2. Normal A-a gradient?
150 - (PaCO2 / 0.8). PAO2 - PaO2 is normally 10-15
What is the difference between true and false diverticula?
True: all layers of wall to include mucosa, muscular and serosa.
False: mucosa, submucosa and serosa, but no muscular wall herniation
Major manifestations of acute rheumatic fever
Joint pain Heart murmur Nodules under skin Erythema marginaum Sydenham chorea
Phases of lyme disease
Early localized: flu-like symptoms + erythema migrans
Early disseminated: facial palsy, nodal block
Late disseminated: arthritis, subacute encephalopathy
2nd line treatment for lime disease
Beta-lactams like ceftriaxone
Colchicine mechanism of action
Binds intracellular tubulin and inhibits microtubule polymerization. This prevents PMN phagocytosis of crystals and chemotaxis to the site of inflammation.
Test to diagnose someone with Prinzmetals angina
Ergonovine (alpha-1 and 5-HT agonist) stimulation test will cause coronary vasospasm and chest pain at very low doses in these patients.
Why treat heart failure patients with neurolypsin inhibitors?
Neurolypsin is a MMP that degrades ANP and BNP. Inhibiting neurolypsin increases the activity of ANP and BNP resulting in vasodilation, renin inhibition and natriuresis.
How does brown fat generate heat?
It is rich in mitochondria that contain the uncoupling protein thermogenin.
Location of foregut, midgut and hindgut structures and blood supply?
Foregut: mouth to 3rd part of duodenum (celiac)
Midgut: 3rd part of duodenum to proximal 2/3 of transverse colon (SMA)
Hindgut: distal 2/3 of transverse colon to anus (IMA)
Lab that could diagnose someone with Wernicke encephalopathy (not imaging)?
B1 deficiency results in poor glucose metabolism because B1 is required for pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and transketolase to function. Measuring erythrocyte transketolase can be diagnostic for Wernicke encephalopathy.
Causes of galactosemia
Type I) GALT deficiency
Type II) galactokinase deficiency
Type III) UDP-galactose-4-epipermase deficiency
Most common cause of hypoketotic hypoglycemia
Acyl CoA dehydrogenase deficiency the prevents progression of beta-oxidation of the respective VL chain, long chain, medium chain or short chain fatty acids metabolized by the enzyme.
Pathophysiology of Huntington’s disease
CAG repeats result in increased cell death in the striatum (caudate and putamen) due to increased glutamate binding to NMDA receptors.
Pathogens most likely responsible for secondary bacterial pneumonia
S. pneumo > S. aureus > H. influenza
Types of Arnold-Chiari malformations
I) tonsils extend into foramen magnum and cause headaches and ataxia as an adult
II) cerebellar vermis and medulla extend into foramen magnum causing aqueduct stenosis, hydrocephalus and meningomyelocele as a neonate
How can you prevent TPN-induced gallstone formation?
Administer cholecystokinin to increased biliary motility
Treatment of cryptococcal meningitis
Amphotericin B and flucytosine during initial period. Long-term maintenance therapy with fluconazole.
HPV strains responsible for disease
1-4: verrucas vulgaris (skin warts)
6, 11: condyloma acuminatum (genital warts)
16, 18, 31: over expression of viral oncogenes E6 (degrades p53) and E7 (inhibits RB1 tumor suppression) leading to cervical, vaginal, vulvar and anal cancer
Diphenoxylate mechanism of action
Opioid analogue similar to meperidine and used to treat diarrhea. It is complexed with atropine to prevent abuse.
Drug helpful for secretory diarrhea
Bismuth subsalicylate, octreotide and probiotics
Mechanism and side effects of pioglitazone and rosiglitazone
It is a thiazolidinedione, which means it binds PPAR-gamma, which complexes with RXR and results in increased insulin sensitivity in muscle and liver, decreased leptin production, increased fatty acid uptake, increased adiponectin production and decreased TNF-alpha production.
Side effects are weight gain and fluid retention.
PCN vs. vancomycin mechanism of action
Covalently binds and inhibits bacterial transpeptidase. This prevents the enzyme from cross linking an amino acid of the 3rd peptidoglycan molecule to the terminal D-ala-D-ala of another peptidoglycan molecule.
Vancomycin directly binds the D-ala-D-ala and inhibits incorporation of new subunits into the bacterial wall
What type of virus is parvovirus? EBV? adenovirus? HCV? HEV? HIV? orthomyxoviruses (influenza)? paramyxoviruses (parainfluenza, RSV, measles and mumps)? rhinovirus? reoviruses (rotavirus)?
Parvovirus: non-enveloped single-stranded DNA EBV: enveloped ds-DNA Adenovirus: non-enveloped ds-DNA HCV: enveloped +ssRNA HEV: non-enveloped +ssRNA HIV: enveloped +ssRNA Influenza: enveloped -ssRNA Paramyxovirus: enveloped -ssRNA Rhinovirus: non-enveloped +ssRNA Rotavirus: dsRNA
Major functions of the hypothalamic nuclei
Ventromedial: satiety, destruction = ventral & medial waist growth
Lateral: hunger, destruction = anorexia
Anterior: A/C, destruction = hyperthermia
Posterior: heater, destruction = hypothermia
Arcuate: secretes DA, GhRH and GnRH
Paraventricular: secretes ADH, CRH, oxytocin and TRH
Supraoptic: secretes ADH & oxytocin
Suprachiasmatic: regulates circadian rhythm and regulation of the pineal gland (responsible for elevated melatonin at night and elevated cortisol in morning)
Malignancies associated with paraneoplastic dermatomyositis
Ovarian, lung, colon and non-Hodgkin lymphoma
Brain tumor biopsy shows….
A) psammoma bodies
B) nests of palisading squamous epithelium and areas of wet keratin
C) perivascular rosettes
D) small blue cells that surround neuropil, forming Homer-Wright rosettes
E) pseudopalisading atypical astrocytes bordering areas of necrosis
F) fried-egg appearance
G) eosinophilic granular bodies with elongated hairlike processes (Rosenthal bodies)
H) spindle cells with palisading nuclei around Verocay bodies composed of eosinophilic cores (Antoni A pattern)
A) meningioma B) craniopharyngioma C) ependymoma D) medulloblastoma E) glioblastoma F) oligodendrocytoma G) pilocytic astrocytoma H) Schwannoma
Bacteriology of gardnerella vaginalis
Anaerobic gram variable rod
Gastric parietal cells secrete HCl in response to…
1) enterochromaffin-like cells release histamine that binds H2 receptors on parietal cells
2) vagal stimulation results in ACh binding M3 receptors, causing direct HCl release. It also causes release of gastrin releasing peptide, which stimulates gastrin release from G cells
3) protein-rich material causes gastrin release from G-cells. Gastrin binds to CCKa receptor on enterochromaffin-like cells and increases histamine release.
Lung met with clear cells and elevated Hct vs. clear cells with no change in Hct and early satiety?
Elevated Hct = renal clear cell carcinoma
Early satiety = stomach signet cell carcinoma
Oseltamivir vs. amantadine
Oseltamivir: neuraminidase inhibitor, prevents virion release from the infected cell
Amantadine: prevents viral disassembly after endocytosis
Method of hepatic metabolism for INH, hydralazine, dapsone and procainamide. People with decreased metabolism of this type are at risk for what condition?
Hepatic microsomal acetylation by N-acetyl-transferase that make them more soluble and able to be excreted in the urine. Patients who are slow acetylators are at increased risk for drug-induced Lupus.
Method of hepatic metabolism for 6-MP and azathioprine
Methylation
Molecular activation that occurs when EPI binds to its alpha-1 receptor?
GDP -> GTP on the alpha-subunit of the G-protein -> alpha-subunit dissociates and exposes its catalytic subunit for PLC -> IP3 + DAG release from plasma membrane -> Ca release from sarcoplasmic reticulum (IP3) and protein kinase C activation (DAG + Ca) -> protein phosphorylation
Post-transcription processing of RNA in eukaryotes prior to translation
5’ cap: guanine triphosphate is added to 5’ end by guanylyltransferase -> guanine triphosphate is methylated by guanine-7-methyltransferase -> mRNA is protected from exonucleases and can exit nucleus
Poly-A tail: polyadenlyate polymerase complex recognizes AAUAAA sequence at the end of mRNA, cleaves the mRNA after this sequence and then adds 20-250 adenosine residues in the nucleus. This tail is gradually shortened in the cytosol, leading to mRNA degradation.
Intron splicing occurs before leaving the nucleus.
In the cytosol, some mRNAs associate with ribosomes immediately and others are bound by P proteins for later use
Viruses that acquire their envelopes by budding through the nuclear membrane
Herpesviruses
Why vitamin K deficiency increases propensity to bleed
It is needed for the enzyme gamma-glutamyl carboxylase, which creates a Ca2+ binding site on factors II, VII, IX and X that is necessary to bind Ca2+ to bind to negatively charged phospholipids and platelets on damaged endothelial cells.
Value that indicates fetal lung maturity
Lethicin (phosphatidylcholine) : sphingomyelin ratio > 2
How are sound waves transmitted into nervous impulses that can be interpreted by the brain?
TM vibration -> ossicles transmit vibration to oval window -> basilar membrane vibrates -> hair cell cilia bend against tectorial membrane in the organ of Corti -> oscillating hyper polarization and depolarization of the auditory nerve
Acoustic reflex to loud sound
The stapedius and tensor tympani contract to decrease vibration transmitted from the ossicles.
Class I antiarrhythmics with most prominent use-dependent effects?
IC (slow dissociation from Na-channel leads to cumulative effect) > IA (intermediate) > IB (rapid dissociation from Na-channel leads to negligible cumulative effect)
Rasburicase mechanism of action
Recombinant urate oxidase, which is not typically present in humans. It converts uric acid to allantoin, which is more soluble and useful in treatment of tumor lysis syndrome.
Denosumab mechanism of action
Monoclonal antibody that prevents RANK-L from activating osteoclasts in treatment of osteoporosis.
Contraindication to administration of cholestyramine for high cholesterol
It increases liver production of VLDL and triglycerides, so don’t give to a patient with hypertriglyceridemia. It also increases cholesterol content of bile, so don’t give to a patient with gallstones.
Pathophysiology of Eisenmenger syndrome
Elevated right atrial pressure from L -> R shunting results in laminar medial hypertrophy of the muscular pulmonary arteries -> elevated pulmonary vascular resistance > systemic vascular resistance -> R->L shunting of blood. At this time, the shunt is permanent and can no longer be closed.
Extra-skeletal manifestations of ankylosing spondylitis
Hypoventilation from limited chest wall expansion
Ascending aortitis -> AI
Anterior uveitis
3 mechanisms of bacterial gene transfer
1) Transformation: direct uptake of naked DNA, typically by S. pneumo, H. influenzae and Neisseria
2) Conjugation: donor bacteria has DNA F-factor that codes for sex pilus to transfer DNA to recipient bacteria
3) Transduction: random bacterial genes are accidentally packaged into viral capsid during lytic stage, then the virus (bacteriophage) infects another bacteria and integrates the donor DNA into the recipients DNA
Pathophysiology of TTP. Treatment?
Low ADAMTS13 results in large vWF multimers that cause formation of diffuse, platelet-rich thrombi to form in microvasculature. This can be inherited or acquired and results in microangiopathic hemolytic anemia with schistocytes and thrombocytopenia with increased bleeding time and normal PT/aPTT. Treat with plasma exchange.
Regions most prone to developing atherosclerotic lesions
Coronary arteries and abdominal aorta
Virulence factors associated with traveler’s diarrhea
ETEC has heat labile (LT) and heat stable (ST) enterotoxins. On colonization of the small intestine by pili adherence, LT activates Gs protein -> increased cAMP. ST binds guanylate cyclase on apical membranes and increases cGMP. cAMP and cGMP increase gut mucosa secretion of water and electrolytes into the lumen resulting in a secretory diarrhea.
An infant has persistent diarrhea. Small intestine biopsy shows gram negative rods in a stacked brick appearance. What is the bug?
EAEC
Areas of the brain most prone to infarction in sustained periods of hypotension
Purkinje cells of the cerebellum and pyramidal cells of the hippocampus. Watershed areas are also susceptible.
A new child is born with cleft lip, cleft palate, polydactyly, rocker-bottom feet and holoprosencephaly. What is the chromosomal abnormality?
Patau syndrome is due to non-disjunction of chromosome 13 during the maternal phase of meiosis I.
A new child is born with a small jaw, prominent occiput, low set ears, rocker-bottom feet and a small mouth. Exam reveals clenched hands with the index finger overriding the middle finger and the pinky overriding the ring finger. What is the chromosomal abnormality?
Edwards syndrome.
Innervation, lymphatics and blood supply above and below the dentate line
Above: inferior hypogastric plexus (autonomic, only sensitive to stretch and pressure), drains to inferior mesenteric and internal iliac lymph nodes, blood supply from superior rectal and middle rectal arteries.
Below: inferior rectal nerve, a branch of the pudendal and is exquisitely sensitive to pain, temperature and light touch. Lymph drainage is to superficial inguinal nodes.
Mechanism of alpha and beta interferon in treatment of hepatitis C and other viral infections?
They bind to type I interferon receptors on infected and neighboring cells. This results in transcription of antiviral enzymes RNase L (endonuclease that degrades RNA) and protein kinase R (inactivates eIF-2, preventing translation of viral RNA). As a result normal metabolism occurs in uninfected cells and translation is inhibited in infected and proximal cells.
They also increase MHC I expression on all cells, increase NK and cytotoxic T-cell activity
Treatment of severe hypoglycemia out of the hospital setting
IM glucagon will return the patient to consciousness within 10-15 minutes. In the hospital you give IV 50% dextrose.
Viral phenotypic mixing
A cell is coinfected with virus A and virus B resulting in expression of glycoproteins on the capsid or envelope from both viruses allowing them to infect cells they would not otherwise infect. This is phenotypic because there is no exchange of genetic material and the next generation will have the original envelope or capsid again if it is the only virus infecting the cell. Contrast this to reassortment and recombination where the next generation of virions remains changed.
Self-limited pharyngoconjuntival fever in military recruits
Adenovirus
Febrile aseptic meningoencephalitis in patients exposed to hamsters or mice?
LCMV, an arenavirus
Prerequisite for hospice care
Prognosis
Test to distinguish tuberculoid from lepromatous leprosy
Lepromin skin test will be + in patients with tuberculoid leprosy because the generate a robust Th1 cytokine profile that activates macrophages and Th1 cells.
Vincristine and vinblastine mechanism of action
Bind B-tubulin and inhibit microtubule polymerization
Patient on chemo gets flagellated skin discoloration and pulmonary fibrosis
Bleomycin
What do 99% and 95% confidence intervals mean?
They represent standard error which is the corresponding z-score divided by the square root of “n”…i.e. people in the study.
99% = mean +/- (2.58 x SD) / square root of n 95% = mean +/- (1.96 x SD) / square root of n
Why are patients with SIADH euvolemic?
The mild initial increase in volume promotes natriuresis and normalization of volume status with continued dilutional hyponatremia.
Cytokines with anti-inflammatory properties
IL-10: it reduces Th1 cytokine production (IL-2 and IFN-gamma), inhibits activated dendritic cells and macrophages and reduces MHC II expression on antigen presenting cells.
Bortezomid mechanism of action
Boronic acid-containing dipeptide proteosome inhibitor that is good for treating high protein output conditions like multiple myeloma because it results in accumulation of pro-apoptotic misfolded and damaged proteins within the neoplastic plasma cells.
Most common cause of unexpected mortality after cardiac catheterization?
Retroperitoneal hemorrhage that occurs secondary to cannulation of the femoral artery above the inguinal ligament
Mnemonic for class I antiarrhythmics
IA) “Double quarter pounder: disopyramide, quinidine and procainamide
IB) “Lettuce, tomato, mayo”: lidocaine, tocainide, mexilitine
IC) “More fries please”: moricizine, flecainide, propafenone
Different effects of class I anti-arrhythmics on the cardiac action potential? Class II?
IA: slowed phase 0 and prolonged phase 3
IB: minimal change in phase 0 and shortened phase 3
IC: drastic phase 0 slowing and minimal change in phase 3
II: slowed phase 4 depolarization
III: drastic prolongation of phase 3
IV: minimal effect on action potential
HIV mechanism of cell entry
HIV envelope glycoprotein gp120 binds CCR5 and CXCR4 -> endocytosis by membrane fusion
Calculating half-life of a drug after administration of a single dose
t1/2 = (0.7 x Vd) / CL
Conditions associated with microangiopathic hemolytic anemia
HUS, TTP and DIC due to widespread thrombosis that destroys RBCs
Aplastic anemia vs. myelofibrosis
Aplastic anemia: no splenomegaly and fatty marrow infiltrated
Myelofibrosis: splenomegaly and collagenous deposition for megakaryocyte platelet activation in marrow
Why give Nimodipine to a patient who presents with subarachnoid hemorrhage.
In addition to communicating hydrocephalus and rebelled, these patients are at risk for vasospasm and subsequent neurological sequelae. CCBs help reduce incidence of vasospasm.
Ortner syndrome
LA enlargement significant enough to cause horseness and recurrent laryngeal nerve impingement
Common anaerobic gram-negative bacillus isolated from intra-abdominal infections
Bacteroides
t(14;18)
Follicular lymphoma due to Bcl-2 activation and subsequent inhibition of apoptosis.
How do macrophages enhance their immune response when encountering bacteria?
Secrete IL-12 -> CD4 cells differentiate into Th1 cells and secrete IFN-gamma -> enhanced macrophage killing ability. Macrophages also secrete TNF-alpha to recruit other monocytes to the site of infection.
In the lung where is:
A) arterial pressure > alveolar pressure > venous pressure
B) arterial pressure > venous pressure > alveolar pressure
C) alveolar pressure > arterial pressure > venous pressure
A) Zone II, pulmonary capillaries open in pulsatile fashion
B) Zone III, pulmonary capillaries are open
C) Zone I, pulmonary capillaries are collapsed
Pulmonary clearance of particles:
A) 10-15 micrometers in size
B)
A) Trapped in upper respiratory tract
B) Cleared by alveolar macrophages
C) Mucociliary clearance (primary method of clearance)
Why do pneumoconioses result in pulmonary fibrosis
Macrophage phagocytosis of small particles results in release of PDGF and IGF that attract fibroblasts and causes collagen deposition.
Episodic vertigo with unilateral hearing loss and ear pain
Meniere’s disease: increased endolymph pressure and volume
Pathogenesis of pancreatitis
Acinar injury -> trypsin activation -> protease (autodigestion), elastase (vascular erosion), lipase and phospholipase (fat necrosis) activation.
Why do lactose intolerant patient develop decreased pH in the gut?
Bacteria ferment lactose to short chain fatty acids (acetate, butyrate and propionate)
Patient has bone pain. Biopsy shows haphazardly organized segments of lamellar bone with prominent cement lines in a mosaic pattern.
Paget’s disease of the bone.
Tommy John surgery repairs what ligament
Ulnar collateral
Patient with new holosystolic murmur and cardiac biopsy showing interstitial fibrosis, scattered macrophages and multinucleated giant cells forming an interstitial myocardial granuloma (Aschoff body). What other special cell types might you see?
Aschoff bodies are pathognomonic for acute rheumatic fever. You may also see macrophages with plump cytoplasm and central slender chromatin ribbons called Antischkow cells. These Aschoff bodies are significant because they eventual fibrose and cause mitral stenosis.
Complications of diphtheria infection
Suffocation from pseudomembrane expansion, myocarditis and neurotoxicity.
Non-motile gram-positive rods that clump in V and Y configurations and intracytoplasmic granules that stain with analine dye.
C. diphtheriae
Why does diphtheria have such a high affinity for cardiac cells?
The B part of the AB toxin binds the heparin-binding EGF-receptor on neurons and myocytes.
Why does our body have a difficult time generating an immune response against HCV?
Due to lack of 3’ -> 5’ RNA-dependent RNA polymerase proofreading activity, there is significant antigenic variability in envelope glycoproteins with each replication of the virus.
Drugs that inhibit dihyrofolate reductase
MTX, TMP and pyrimethamine (good for toxo)
Why use cilastin with imipenem?
It inhibit renal metabolism of imipenem by competitively inhibiting dihydropeptidase on the tubular brush border.
Bacitracin mechanism of action
Inhibits cell wall synthesis by blocking mucopeptide transfer to the cell wall
How can the pancreas cause bleeding fundic varices?
Pancreatitis and inflammation can cause splenic vein thrombosis as the splenic vein lies posterior to the pancreas. The short gastric arteries normally drain to the splenic vein and blockage of the splenic vein results in increased venous pressure and fundic varices.
Vein that drains esophageal blood into the vena cava
Azygos
Cause of cleft lip vs. cleft palate
Cleft lip: failure of maxillary prominence to fuse with intermaxillary segment
Cleft palate: palatine shelves fail to fuse with one another or with the primary palate.
Motile gram-negative rod, non-fermenter that is oxidase positive and produces pyocyanin
Pseudomonas
Function of splenic red pulp
Destroys aged RBCs, stores blood cells and platelets for when excess are needed and macrophages clear circulating bacteria and present them to B and T cells in the white pulp. ***B cells in the spleen produce 50% of all the body’s opsinizing immunoglobulin.
Antifungals that block synthesis of glucan
Caspofungin and other echinocandins block synthesis of 1,3-beta-D-glucan and prevent formation of new fungi. It is most active against aspergillus and candida
Antifungal that binds ergosterol and puts holes in the fungal membrane. Major side effect?
AmphoB. Good for cryptococcal meningitis. Watch out for renal toxicity because it can cause renovascular constriction and direct tubular toxicity leading to electrolyte abnormalities and anemia due to decreased EPO release. Also patients can get an acute reaction immediately after infusion.
Augmenting agent to amphoB for cryptococcal meningitis that inhibits fungal DNA and RNA synthesis in fungi
Flucytosine
Antifungal that accumulates in keratin-containing tissue and inhibits microtubule function
Griseofulvin
Antifungal that inhibits the enzyme 14alpha-demethylases’s conversion of lanosterol to ergosterol necessary to make fungal plasma membranes. Side effects?
Itraconazole. These are potent inhibitors of CYP450, so care should be taken when prescribing them to patients on warfarin, tacrolimus, cyclosporine or oral hypoglycemics. Also if patients are on CYP450 inducers (rifampin, phenytoin, carbamazepine, phenobarbital), the azole may not be as effective.
Antifungal that accumulates in the skin and nails and inhibits squalene epoxidase, leading to decreased ergosterol synthesis
Terbinafine
Morphologic progression of pneumonia
Colonization: 1st 24 hours, lobe is red, boggy and alveolar exudate contains mostly bacteria
Red hepatization: days 2-3, lobe is red, firm and alveolar exudate contains mostly RBCs, PMNs and fibrin
Gray hepatization: days 4-6, lobe is gray, firm and alveolar exudate contains mostly PMNs, fibrin and disintegrating RBCs
Resolution: enzymatic digestion of exudate restores normal architecture.
Mechanism and key side effect of chloramphenicol
This peptidyl transferase inhibitor (which binds to the 50S subunit) can cause reversible and irreversible aplastic anemia. It can also cause gray baby syndrome.
How does shigella invade GI mucosal tissue?
Initial uptake into the M-cells allows it to lyse the M-cell and spread along the basal surface of the GI mucosa from cell to cell via actin polymerization (like listeria)
Enteric bugs that can infiltrate the mesenteric lymph nodes and cause pseudoappendicitis from LN inflammation
Yersinia and salmonella
Serotonin syndrome vs. neuroleptic malignant syndrome
Serotonin syndrome = muscular hyperactivity + hyperreflexia
NMS = diffuse muscular hyperrigidity + bradyreflexia
Sacubitril MOA
Inhibits neprilysin to prevent the degradation of ANP and enhancing its effects on natriuresis (dilates afferent arteriole, reduces Na+ reabsorption and limits aldosterone secretion from adrenals) and vasodilation.
Main blood supply of the femoral head
Medial circumflex femoral arteries
Why should you never treat a patient with strongyloides with corticosteroids
After infection through the skin by filariaform larvae and migration through the lungs and down the esophagus to the GI tract, they develop into adult worms. These adult worms produce rhabtidiform (non-infectious) larvae that can be excreted in the stool or molt into filariaform larvae, causing autoinfection. The ability to autoinfect the host results in super infection. Giving the patient corticosteroids will inhibit their Th2 response (same with patients with HTLV-1) and superinfection will result in shock due to poor parasitic control by basophils and eosinophils.
Treatment of strongyloides
Ivermectin
Markers that stain small cell lung cancer
Chromogranin, neuron-specific enolase and synaptophysin.
Why are patients with N. meningitides at risk for septic shock?
The bacteria has the LOS (similar to LPS) on its membrane, which binds to TLR-4 and induces release of TNF-alpha, IL-1, IL6 and IL-8.
Patient has asymmetric, multifocal neuropathy with skin nodules, migratory pulmonary infiltrates, sinus abnormalities and p-ANCA anti-MPO antibodies.
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss). The neuropathy occurs due to vasculitis involving the epineural blood supply.
Aspiration pneumonia vs. pneumonitis
Pneumonia: due to aspiration of oropharyngeal bacteria, fever onset days after, may progress to form an abscess (most common cause of lung abscess), needs clindamycin or beta-lactam + beta-lactamase.
Pneumonitis: due to aspiration of gastric content, respiratory distress occurs within hours, infiltrates may be bilateral, will resolve on its own
Why is spironolactone good for patients with heart failure?
Blocks aldosterone binding leading to K+ sparing diuresis and blockage of cardiac remodeling.
Patients at high risk for drug-induced lupus
Procainamide (especially slow-acetylators), isoniazid and hydralazine.
Differentiating drug-induced lupus from SLE
Drug induced lupus commonly has anti-histone bodies, which are present in ~50% of patients with SLE.
Anti ds-DNA antibodies are common in SLE, but rare in drug-induced lupus.
Use of folinic acid with MTX vs. 5-FU
With MTX = reversal of effects due to bypassing of dihydrofolate reductase, which is inhibited by MTX
With 5-FU = potentiates effects due to increased binding of thymidylate synthase
Medication used to decrease toxicity of platinum-containing and alkylating chemotherapy drugs?
Amifostine is a free radical scavenger and reduces nephrotoxicity and xerostomia caused by these drugs.
Drug used to mitigate anthracycline-related cardiotoxicity
Dexrazoxane, an iron-chelating agnet
Bronchiolitis obliterans in a lung transplant patient
Signifies chronic rejection due to lymphocytic infiltration, inflammation and fibrosis of the bronchial wall
Areas of the brain at highest risk for global cerebral ischemia
1) Pyramidal cells of the hippocampus
2) Purkinje cells of the cerebellum
How does the body hurt itself when metabolizing CCl4?
The P450 microsomal system creates free radicals when oxidizing CCl4. These cause lipid peroxidation and damage to cellular membranes.
CD4 count when you worry about CMV retinitis and MAI
