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High yield notes for the USMLE step I
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Contents Biochem .................................................................................................................................................................................. 1
Musculo-Skeletal ..................................................................................................................................................................... 2
Pharmacology ......................................................................................................................................................................... 3
Gastrointestinal ....................................................................................................................................................................... 4
Endocrine ................................................................................................................................................................................ 5
Cardiovascular ......................................................................................................................................................................... 5
Repro ....................................................................................................................................................................................... 6
Renal ....................................................................................................................................................................................... 7
Neuro ...................................................................................................................................................................................... 7
Microbiology ........................................................................................................................................................................... 7
Bacteria ............................................................................................................................................................................... 7
Viruses ............................................................................................................................................................................... 11
Antibiotics ......................................................................................................................................................................... 12
Multiple ................................................................................................................................................................................. 13
Biochem Uric acid precipitates at acidic pHs
elevated urine galactose + bilateral lens opacities o Galactokinase deficiency
After 16-24 hours of starvation: o breakdown of TG in adipocytes -> release free FA -> liver mitochondria beta oxidize into ketone bodies
each round = 1 NADH, 1 FADH2, a acetyl-CoA acetyal-CoA enters TCA cycle => 3 NADH, 1 FADH2, 1 GTP, CO2
o Failure to produce ketone bodies during fasting (low plasma ketone level during fasting) is a problem of beta oxidation
often problem of acyl-CoA dehydrogenase defect FA synthesis
o During fed state, Acetyl-CoA carboxylase mediates rate-limiting step in fA synthesis
HMP Shunt = Pentose Phosphate Pathway o ALL reactions occur in the cytoplasm o nonoxidative reactions : reversible
enzymes: transketolase and transaldolase transketolase requires TPP
all cells use this portion of the shunt to make fructose-6-phosphate, which can subsequently be turned into ribose
or going the other way, fructose-6-phosphate can enter glycolysis o oxidative portion: glucose-6-phosphate -> ribulose-5-phosphate
produces 2 NADPH enzymes: glucose-6-phosphate DH (rate-limiting step), 6-phosphogluconate DH active in: liver, adrenal cortex, gonads, adipose tissue, RBCs
Musculo-Skeletal Muscle Relaxers
o succinylcholine like acetylcholine, binds nicotinic Ach receptors at neuromuscular junction, but unlike Ach, is not
degraded by Achesterase -> once Na channels depolarize and inactivate, cannot reactivate as long as membrane is depolarized (phase I block)
in phase II block, nicotinic Ach receptors eventually become desensitized to succinylcholine, and membrane repolarizes.
the nicotinic Ach receptor is a non-selective ion channel -> also permist potassium release
o can have life-threatening hyperkalemia and arrhythmias in patients with: crush or burn injuries, denervating injuries (quadrapeligia, Guillian-Barre), myopathies
in these patients, use non-depolarizing agents: vecuronium or rocuronium
o atracurium: non-depolarizing neuromuscular blocker releases histamine, can produce hypotension, flushing, bronchoconstriction metabolite laudanosine can produce seizures
o Baclofen: affects GABAB receptors at SC o Dantrolene: effective in malignant hyperthermia
acts on ryanodine receptors on SR and prevents release of Ca into muscle fiber cytoplasm Carpal Tunnel associations
o pregnancy -> fluid accumulation o hypothyroidism -> glycosaminoglycans build up o diabetes -> CT thickens o rheumatoid arthritis -> tendon inflammation o hemodialysis (long history) -> deposition of beta2- microglobulin (dialysis associated amyloidosis)
Auto-Antibodies and associated conditions o anti-cyclic citrullinated peptide (anti-CCP)
confirms RA clinical diagnosis, highly specific for RA o anti-centromere Ab
CREST syndrome o Rheumatoid factor = anti-Fc portion of IgG Ab
Rheumatoid Arthritis, 10% of healthy people, 30% of SLE pts, and many other inflammatory conditions
o Anti-Nuclear Ab = nuclear basic proteins many CT disorders, often I RA but less often than Rheumatoid factor
o Antiphospholipid Ab SLE, antiphospholipid Ab syndrome causes hypercoagulability, paradoxical PTT prolongation, recurrent miscarriages
Erythema Nodosum o extremely non-specifc, can be cused by:
Strep pyogenes pharyngitis Staph aureus, fungi, chlamydia Chrons, sarcoidosis, other inflammatory conditions
Endomysial inflammatory infiltrate is found on muscle biopsy in polymyositis o presents with proximal muscle weakness
Glomangioma o benign glomus tumor. has bluish tint o glomus = modified smooth muscle cells that control thermoregulatory functions of dermal glomus
bodies o one of 2 tumors that may appear under the nail bed, other being melanoma
Radial nerve
o Gives off posterior cutaneous nerve of the arm o Posterior cutaneous nerve of forearm arises in spiral groove o At lateral epicondyle of humerus (pt of articulation with Radius) splits into
Superficial branch cutaneous sensation on radial dorsal hand Deep branch extensor compartment
Injury -> wrist drop
Nursemaids elbow (pulling child up by arm) = radial head subluxation o Can damage deep branch of radial nerve
Median nerve o Carpal tunnel syndrome -> dysfx fine motor control of thumb
Ulnar nerve o passes between hook of hamate and psiform (Guyons canal)
pinched here -> dysesthesias of ulnar side of hand + weakness of intrinsic muscles of the hand Axillary nerve
o can be damaged with surgical neck humerus fx -> paralysis of deltoid and teres minor + lost sensation on lateral upper arm
Reactive arthritis: HLA-B27 positive, associated with Chlamydia, Shigella, Salmonella, Yersinia, Campylobacter o accompanied by urethritis and conjunctivits
Internal branch of Superior Laryngela nerve (CN X) is located in the piriform recess above the esophagus, only covered by thin mucosa. this nerve carries sensory and autonomic fibers.
o damaged -> afferent limb of cough reflex gone
Gag reflex -> afferent limb mediated by CN IX, efferent limb by CN X
Taste from anterior tongue CN VII
Taste from posterior tongue CN IX
Pharmacology Halothane = a halogenated inhalation anesthetic (enflurane, isofllurane, sevoflurane)
o rare complication: Massive hepatic necrosis appears two days to 4 weeks after exposure histology shows massive centrilobular hepatic necrosis
Nitrates -> transformed to NO at vascular smooth muscle cell membrane -> increased cGMP -> decreased intracellular Ca and myosin dephosphorylation
atypical antipsychotics o SE: hyperglycemia
potency of a gaseous anesthetic o determined by minimal alveolar concentration that produces desired effect in 50% of patients o potent anesthetics require lower partial pressures to be effective
Beta1 receptors are found on renal juxtaglomerular cells
taking lithium during pregnancy predisposes to Ebsteins anomaly
Cholinergics o facial flushing + mydriasis = common anticholinergic effects from meds o Cholinergic receptors:
Nicotinic neuronal ganglion (sympathethic and parasympathetic)
skeletal muscle neuromuscular junction Muscarinic
blockage -> flushed skin + mydriasis
most toxic effects of anticholinergis are from muscarianic blockade o inhibition of sweat glands -> fever + cutaneous vasodilation o inhibition of pupillary constrictor + ciliary muscles -> mydriasis
meds with antimuscarinnic effects: o atropine
o TCAs, ike amitriptyline o H1 receptor antagonists like diphenhydramine o neuroleptics o antiparkinson drugs
H1 receptor antagonists (anti-histamines) taken for allergic rhinitis, often cause anticholinergic effects
H2 receptor antagonists block gastric acid secretion from parietal cells
Thiazide diuretic adverse effects: HYPER o Hyperuricemia o Hypercalcemia decrease urine calcium concentration, so useful in treating nephrolithiasis 2o to
hypercalciuria o Hyperglycemia o Hyperlipidemia elevated cholesterol and LDL o HYPO
Hypokalemia Hypotension
Meds associated with osteoporotic fractures o Vitamin D catabolism
Anticonvulsants that induce CYP: phenobarbital, phenytoin, carbamazepin o Estrogen suppressors
Aromatase inhibitors Medroxyprogesterone
o Testosterone and Estrogen suppressors GnRH agonists
o Decrease Calcium absorption PPIs
o Decrease bone formation Glucocorticoids Unfractionated heparin Thiazolidinediones
5-HT3 receptor is ligand-gated cation chanel o all other 5-HT receptors are G protein coupled
MDR1 multi drug resistant gene found in cancer cells is an ATP-dependent pump that spits out chemo drugs o codes for p-glycoprotein, which is found normally in some cells in kidney, bbb o Drugs that inhibit the pump: verapamil, diltiazem, ketoconazole
NE extravasation o blanching of vein into which NE is being infused with pallor of surrounding tissue signifies NE
extravasation -> resulting vasoconstriction o treat with local injection of alpha1 blocker like phentolamine to prevent tissue necrosis
Isoproterenol activates beta2 receptors o -> vasodilation in striated muscle, renal, mesenteric vascular beds o not helpful in subcutaneous vessels
When giving statins, monitor LFTs o discontinue statins if liver enzymes exceed 3x upper limit of normal
Gastrointestinal VIPoma
o tumor of pancreatic islet (non-beta) cells o increases intestinal chloride loss into stool -> excess loss of water, Na, and K o inhibits gastric acid secretion -> chlorhydria o treat with octreotide (somatostatin)
CD21 is B cell receptor for C3d complement
C. diff o Common antibiotics that precede C diff:
clindamycin, fluoroquinolones, penicillins, cephalosporins o Toxins: bind intestinal mucosa receptors and are internalized
-> both inactivate Rho proteins involved in actin maintenance -> disrupt intercellular tight junctions
enterotoxin: toxin A cytotoxin: toxin B more virulent bind receptors
Endocrine Thyrotoxicosis Treatment
o Minimize thyroid hormone synthesis and release propylthiouracil inhibits thyroid peroxidase methimazole inhibits thyroid peroxidase Iodide inhibits secretion of T3 and T4 and inhibits import of iodide (?) Percholarate and Pertechnetate inhibit entry of iodide into thyroid cell
o Block peripheral conversion of T4 -> T3 propylthiouracil beta blockers Ipodate
o Minimize sympathetic outflow beta blockers
Klinefelter Syndrome o progressive destruction/hyalinization of seminiferous tubules -> small/firm testes, infertile o Sertoli cell damage -> decreased serum inhibin levels o dysfunctional Leydig cells -> decreased testosterone levels o loss of feedback inhibition -> elevated FSH/LH o gonadotropin excess -> increased aromatase activity -> high estrogen levels, gynecomastia
Cystic Fibrosis -> inspissated, obstructed pancreatic ducts -> pancreatic insufficiency
Cardiovascular Normal Pressures Min Max
Right Atrium 0 8
Right Ventricle 4 25
Pulmonary Artery 9 25
Left Atrium 2 12
Left Ventricle 9 130
Aorta 70 130
Drug Mechanism Major Lipid Effects
Side Effects
Statins inhib HMG-CoA reductase decrease LDL decrease TG increase HDL
hepatotoxicity muscle toxicity
Fibrates Gemofibrozil Fenofibrate
Activate PPAR decrease TG decrease LDL increase HDL
Muscle toxicity gallstones
Bile Acid Sequestrants Cholestyramine Colestipol Colesevelam
binds bile acids in intestine decrease LDL nausea, cramping impaired drug and fat soluble absorption
Niacin decrease FA release decrease VLDL synthesis decrease HDL clearance
increase HDL decrease HDL decrease TG
flushing and pruritis hepatotoxicity
Ezetimibe decrease intestinal cholesterol absorption
decrease LDL increase hepatotoxicity if given with statins
Omega 3 FA decrease TG synthesis decrease TG nausea
Effects of drugs on Cardiac Pacemakers o Adenosine activates K channels -> prolongs membrane in negative potetial
also inhibits L-type Ca channels o Acetylcholine opens K channels and decreases slow inward Na and Ca during phase 4 o Norepi faciliates opening of Ca channels and Na channels in phase 4
Mitral stenosis o a shorter interval between A2 (of s2) and Opening Snap of mitral valve means fluid overload in the left
atrium is raising LA pressure, and thus means more severe disease
a VSD with a loud murmur is less serious than a softer murmur. A soft murmur from a VSD reflects reduced interventricular pressure gradient because of the amount of blood that is able to flow through the VSD
Dilated cardiomyopathy o can be caused by Doxorubicin (or epirubicin, daunorubicin, idarubicin)
can present months after discontinuation of drug, early sign is SR swelling presentation: dyspnea on exertion, orthopnea, peripheral edema prevention method: dexrazoxane iron chelating agent prevents O2 free radicals
Repro Patau syndrome (trisomy 13)
o severe cleft lip/palate, microophthalmia, anophthalmia, coloboma, cyclops, malformed nose, deafness, scalp defecs
o CNS: severe mental retardation, microcephaly, holoprosencephaly, absent olfactory bulb, neural tube defects
o Extremities: polydactyly, rocker-bottom feet o Cardiac: PDA, ASD, VSD o Renal: PCKD o GI: abd wall defects, pyloric stenosis
Downs trisomy 21 o CNS: hearing impairment o Head/neck: upslanting palpebral fissures, epicanthal folds, speckled iris (Brushfield spots), flat nasal
bridge, open mouth with protruding tongue o msk: hypotonia, atlanto-axial instability, short hands w/single palmar crease o cardiac: endocardial cushion defects (AV septal defect), VSD, ASD, PDA, ToF o GI: duodenal atresia, TEF, annular pancreas, Hirschsprungs disease, omphalocele, imperforate anus o Immune: impaired cellular immunity, high incidence of infections, autoimmune disorders o Heme: 500x increased risk of AML-M7, 10-20x increased risk of ALL o Endocrine: hypo or hyper thyroidism, DMI, infertility in males
Edwards Syndrome trisomy 18 o prominent occiput, micrognathia, small mouth, low set malformed ears o rocker bottom feet, clenched hands with overriding index and fifth finger o Meckels diverticulum and malrotation
When treating for N. gonorrhoaea (with third gen cephalosporin), MUST treat with azithro or doxy also for possible Chlamydia co-infection
o if untreated -> can cause scarring in fallopian tubes, infertility, ectopic pregnancy
ToRCHES o Congenital Rubella infection is assoc with PDA
Endometriosis: presence of normal endometrial tissue in locations outside the uterus o cause cyclic pelvic pain due to local inflammation/fibrosis
Adenomyosis: presence of endometrial glandular tissue in the myometrium o symptoms: menorrhagia and dysmenorrhea, uniformly enlarged uterus on exam -> from uterine smooth
muscle hypertrophy and hyperplasia in response to the ectopic endometrial tissue
Estrone o made by peripheral tissue from adrenal and ovarian androstenedione by aromatase -> may be normal in
menopausal women
Measure serum FSH to confirm menopuase, should be > 30 U/L o serum LH will also rise, but it rises later and less prominently
Renal Filtration Fraction = GFR/ Renal Plasma Flow
o RPF = RBF x (1-hematocrit) o filtration fraction = fraction of plasma flowing through glomerulus that is filtered across the glomerular
capillaries
Kidney o PAH is completely secreted, clearance approximates renal plasma flow o Inulin is purely filtered, not reabsorbed nor secreted o Urea: 40-50% of filtered urea is reabsorbed by PT, variable further reabsorption or secretion
Neuro Lithium SE: Hypothyroidism (weight gain, dry skin, hair loss, constipation, bradycardia)
o constantly measure TSH, blood Lithium levels and renal function o Lithium is renally excreted, can ccause nephrogenic diabetes insipidus o teratogen -> Ebsteins anomaly
Carbamazepine -> aplastic anemia
Citalopram (SSRI)-> sexual dysfunction
Clozapine (atypical antipyschotic) -> agranulocytosis, seizures
Lamotrigine -> rash, even SJS
Risperidone (atypical antipsychotic) -> hyperprolactinemia
Trazadone -> priapism, orthostatic hypotension, sedation
Morphine o opioid agonist, selectively binds mu opioid receptors -> GPCR -> major pathway is potassium
conductance -> K efflux -> hyperpolarization of
Microbiology Bacteria
Microbe Toxin MOA, effects
B. anthracis Anthrax exotoxin
Edema: adenylate cyclase mimic -> elev cAMP -> edema + phag dysfx
lethal: zinc-dependent protease inhibits MAPK signaling -> apoptosis
B pertussis Pertussis Gi ADP-ribosylation -> elev cAMP -> edema +phag dysfx
Adenylate cyclase adenylate cyclase mimic -> elev cAMP -> edema + phag dysfx
C. botulinum Botulinum blocks presynaptic Ach release at neuromuscular junction
C. difficile Toxin A recruits/activates N -> cytokine release -> mucosal inflam, diarrhea
Toxin B depolymerizes actin -> mucosal cell death -> bowel wall necrosis
S. dysenteriae Shiga toxin disables 60s ribosome subunit -> intestinal epithelial cell death/diarrhea
S. pyogenes Pyrogenic exotoxin superantigen, assoc with scarlet fever and strep TSS
Streptolysin O, S damages RBC membranes -> beta hemolysis
Catalase Positive (aside from S. aureus)
o Pseudomonas G- rod o Listeria G+ rod o Aspergillus o Candida o E. coli G- rod o Serratia G- rod
Cold Agglutinins: Mycoplasma pneumoniae or EBV
Capsules o Bacillus anthracis glutamic acid capsule
Urease Positive (P SCHUNKS) o Proteus o S. epidermidis o S. saprophyticus o Cryptococcus o H. pylori o Ureaplasma o Nocardia o Klebsiella
Toxins o Protein A -> bound to Staph. aureus cell wall, binds IgG Fc near its hinges o Hemolysin -> secreted factor produced by Staph -> causes hemolysis, destruction of neutrophils,
macrophages, platelets o IgA proteases:
Strep pneumo Neisseria gonorrhoeae
o ETEC LT -> activates adenylate cyclase ST -> activates guanylate cyclase
so does Yersinia enterocolitica entertoxin
-> watery diarrhea + electrolyte loss o O157:H7 E. coli
do not ferment sorbitol, unlike 80% of other E. coli strains toxin is identica to the Shiga toxin (Shigella dysenteriae)
phage encoded
production enhanced by iron deficiency
inactivate 60s ribosomal subunit -> inhibit protein synthesis -> cell death o Corynebacterium diphtheriae
diphtheria toxin -> inactivate EF-2 o Pseudomonase aeruginosa
Exotoxin A -> inactivate EF-2 o C. diff
cytotoxin B -> disrupts cytoskeleton to treat recurrent cases: fidaxomicin
has less effect on normal GI flora than metronidazole or vanco, and has least systemic absorption
metronidazole for initial infection o greater systemic absorption, lower drug delivery to distal colon
oral vanco for severe C diff o Ecthyma gangrenosum: multiple skin patches with ulcerated appearance and occasional necrotic center
characteristic for P. aureginosa bacteremia possible in neutropenic patients neutropenic pts are more susceptible to bacteremia by Gram negatives
ulcerations caused by release of virulence factors that destroy tissue and -> insufficient blood flow
exotoxin A (inhibit protein synthesis)
elastase (degrades elastin in blood vessels)
phospholipase C (degrades cellular membranes)
pyocyanin (generates ROS)
CAP o Strep pneumo
polysaccharide capsule, IgA protease, adhesins, pneumolysin o Haemophilus influenzae o Moraxella catarrhalis o Klebsiella pneumo o Staph aureus
Atypical pneumonia o Mycoplasma pneumoniae o Chlamydophila pneumoniae o Legionella
Respiratory Pathogen G- rods: o Haemophilus o Legionella o Bordetella
Post-influenza Secondary Bacterial pneumonia, pathogens most often responsible: o Strep. pneumo o Staph. aureus o Haemophilus influenzae
Strep Pneumo o two vaccines available, very young and very old are at risk
Pneumococcal polysaccharide vaccine covers more strains
evokes T-cell independent B cell response to the capsule
this kind of vaccine also available for Neisseria meningitidis and Haemophilus influenzae Pneumococcal conjugate vaccine
more effective in elderly and children Staph
Coagulase positive Staph aureus
o coagulase positive (binds fibrinogen) o protein A binds Fc of IgG o exofoliatin is an exotoxin, causes SSSS by toxin, not by bacterial invasion
Coagulase neg Novobiocin sensitive
o S. epidermidis
Novobiocin resistant o S. saprophyticus
o Catalase negative -> Strep Alpha hemolytic
Optochin resistant, bile insoluble o Viridans strep
dental caries SBE after dentist
make insoluble extracellular polysaccharides (dextrans) from sucrose optochin sensitive, bile soluble
o Strep pneumo LANCET (sensitive about its chin, will hide in bile) shaped diplococci
pneumonia meningitis otitis media sinusitis
Beta hemolytic PYR pos, bacitracin sensitive
o Strep pyogenes (GAS) cellulitis pharyngitis erysipelas has M protein (antiphagocytic, binds fibrinogen)
PPYR neg, CAMP pos o Strep agalactiae (GBS)
neonatal sepsis pneumonia meningitis UTI
Gamma hemolytic Grow in bile and 6.5% NaCl, PYR pos
o Enterococci IE after GU procedure UTI wound infection
Grow in bile but not 6.5 NaCl, PYR neg o Strep bovis
bacteremia/IE in colon cancer Impetigo
o caused by Staph aureus, less frequently Strep pyogenes o Signs:
pustular skin lesions -> broke to form thick scabs in lower extremities facial puffiness + hematuria -> post-strep glomerulonephritis
this means it was Strep pyogenes (not staph) o another complication of pyogenes could be acute Rheumatic fever, but assoc.
with pharyngitis, not skin infection o cellulitis and erysipelas can also preceed post-strep GN
Haemophilus influenzae o type B -> has capsule made of polyribitol phosphate - pentose monosaccharides rest of H. i strains have
hexose sugar capsules PRP capsule prevents phagocytosis -> can invade vasculature and spread to distant sites vaccine is against type B
hyaluronidase o produced by: staphylococci, Group A strep, C. diff o digests extracellular substances -> enhanced ability to spread
Strep pyogenes o catalase negative, beta hemolytic, gram positive cocci in chains o unique among beta hemolytics in that it is susceptible to bacitracin
bacitracin test has been replaced by pyrrolidonyl arylamidase (PYR) test Strep pyogenes is pyrrolidonyl arylamidase positive
Bartonella henselae
o causes cat-scratch fever and o -> Bacillary angiomatosis in immunocompromised patients: red-purple papular skin lesions, can also find
vascular proliferations in the viscera fatal if untreated
o -> culture negative infective endocarditis
Viruses Parvovirus -> erythema infectiosum (fifth disease), slapped cheek rash
o after facial rash fades, lace like rash appears on trunk and extremities o replicates in bone marrow
aplastic crisis in sickle cell pts o hydrops fetalis in fetus o highly tropic for RBCs - to blood group P Ag (globoside) acts as parvovirus receptor and is found in high
concentrations on RBCs and erythrocyte progenitors
Pharyngo-conjunctival fever -> adenovirus
Epidemic viral gastroenteritis -> Norwalk virus (Calicivirus)
Paramyxoviruses: o Parainfluenzae -> croup (laryngotracheobronchitis) o RSV -> bronchiolitis in infants o Measles -> Rubeolla
Koplik spots: white spots on erythematous base on buccal mucosa Koplik spots accompanied by cough, coryza, conjunctivitis: measles virus very likely -> 1-2 days later: maculopapular rash
o Mumps -> parotitis
In a mono-like illness (lymphocytosis with 30% atypical lymphocytes): o EBV is most common cause: heterophile Ab, pharyngitis o CMV is second most common: more likely to have no assoc pharyngitis nor LAD, does not agglutinate
heterophile Ab
prevent placental transmission of HIV: o Zidovudine: a retroviral reverse transcriptase inhibitor o placental HIV transmission presets as oral thrush, interstitial pneumonia, and severe lymphopneia
during first year of life
Fungi o Histo = central/eastern US, along Ohio and Mississipi river valley o Blasto = east of Mississippi
Parasites o Treat toxoplasma gondii with pyrimethamine and sulfadiazine
or, if sulfa allergy, pyrimethamine and clindamycin AND leucovorin
o Schistosoma requires fresh water snails to incubate infectious larvae S. japonicum, S. mansoni -> intestinal (ulceration -> IDA) and hepatic schistosomiasis (portal
HTN)
japonicum: asia, china, philippines, japan
mansoni: sub-saharan africa, middle east, SA, caribbean S. haematobium -> urinary schistosomiases (dysuria, hydrnephrosis, squamos cell carcinoma of
bladder)
North africa, sub-saharan africa, middle east o Freshwater fish as incubater: Diphyllobothrium latum
Sx: B12 deficiency, megaloblastic anemia ingested as larvae
o Most common cause of hydatid cysts in humans: dog tapeworm Echinococcus granulosus
foods contaminated with dog feces sheep are intermediate host
Antibiotics MOA of disinfectants:
o alcohol disrupt cell membranes (+ denature proteins) o Chlorhexidine disrupt cell membranes (+coagulation of cytoplasm) o Hydrogen Peroxide free radical production
kills spores o Iodine halogenates proteins and nucleic acids
kills spores in parasitic infection, eosinophils bind Fc portion of IgG and IgE that are bound to parasite -> triggers
degranulation and release of major basic protein and ROS => Antibody-dependent cell-mediated cytotoxicity
Clindamycin is the antibiotic of choice for lung abscesses: o good activity against anaerobic oral flora good for pneumonia in alcoholics and ALSO covers Gram
positives like Strep pneumo o Bacteroides, Prebotella, Fusobacterium, Peptostreptococcus from increase in distal tubular membrane permeability
hypokalemia -> arrhythmias, T-wave flattenig, ST depression, prominent U waves, premature atrial or ventricular contractions
profound hypokalemia -> ventricular tachycardia, fibrillation Anti-fungals
o Azoles inhibit demethylation of lanosterol into ergosterol (membrane compon ent) o Amphotericin B binds erogsterol and creates a pore in the membrane o Terbinafine accumulates in skin and nails, inhibits fungal enzyme squalene-2,3-epoxidase -> decreases
synthesis of ergosterol o Griseofulvin binds and inhibits microtubules in fungal cells o Caspofungin blocks glucan synthesis -> 1,3-beta-D-glucan is a major polysaccharide component of fungal
cell wall o Flucytosine inhibits synthesis of DNA and RNA in fungal cells, often used synergistically with
amphotericin B, especially against cryptococcal meningitis
Multiple adult onset asthma, eosinophilia, p-ANCA (anti-myeloperoxidase) = Churg-Strauss
o + hx of allergy, mono/polyneuropathy, migratory/transient pulmonary infiltrates, paranasal sinus abnormalities
Goodpasture Syndrome o Ab against alpha3 chain of collagen IV
SLE o ANA are sensitive for SLE, but not specific o anti-dsDNA Ab are highly specific for SLE but not sensitive (only 60% of SLErs have it) o anti-Smith Ab are highly specific for SLE, but only found in 20-30% of cases of SLE
1. Cyclophosphamide MOA 2. rectal bleeding + ulcers -> tx? amoxicillin, bismuth subsalicylate, loperamide, sulfasalazine 3. cholesterol decreasing drug that inhibits transport of cholesterol through intestinal wall: cholestyramine,
ezetimibe, gemfibrozil, niacin, simvastatin 4. What is the MOA of drug for ADHD -> selective inhibition of uptake of serotonin at nerve terminals, increased
release of dopamine and norepi, NOT enhanced action of GABA at GABA receptor 5. Patient getting liposuction develops hyperthermia, tachycardia, muscle rigidity -> give drug with what
mechanism? a. decrease Ca release from SR b. NOT enhace renal tubular excretion of Ca c. increase plasma Ca concentration d. open cell membrane Ca and Na channels e. shift Ca from extracellular to intracellular
6. old guy with A fib, given IV ibutilide, what is his greatest risk in next 6 hours? a. NOT av block b. AV nodal reentry c. sinus arrest d. sinus tachycardia e. torsades de pointes
7. What can you give for allergies to a crane operator a. brompheniramine, hydroxyzine, loratadine
8. stage IV colon cancer, severe diarrhea with fluorouracil, leucovorin, irinotecan, Dr gives WHAT opioid antidiarrheal with no CNS effects?
a. Loperamide? 9. What binds 30 s ribosome to block protein synthe
a. amox, erythro, getamicin, sulfamethoxazole 10. Heparin induced thrombocytopenia 11. Prednisone suppresses: Ab binding, Mast cell degranulation, neutrophil function, t-lymph function 12. Alendronate for bone density MOA?
Microbiology 1. man with high fever, muscle aches, malaise, anorexia, nonproductive cough, same with his wife and two kids. x
ray and CBC normal. virus replicates in nucleus: a. influenza
2. round shiny bumps in area of eczema, smooth umbilicated papules a. adeno, flavi, paramyxo, pox (molluscum contagiosum
3. otherwise healthy 6 yo boy keeps getting Neisseria menin a. absolute neutrophil count b. CD4 count c. serum IgA d. total hemolytic complement conc
4. brazillian old edema of LE + SOB, myofiber necrosis + inflam infiltrate neutrophils, T, macophages, eosin a. toxocara canis, trichinella spiralis, trypan brucei , t. cruzi, wuchereria bancrofti
5. girl with bilateral interstitial infiltrate, blood aglutinates sontaneoulsy, why a. IgA, D, E, M COLD AGGLUTINATION
6. after africa trip -> fever abd discomfort, dot shit in RBCs a. babesiosis, malaria, toxoplasmosis, NOT trypanosomes
7. woman with fever, malaise, abd pain, vag discharge, ectopic preg 1 year ago. bilateral lower quadrant tenderness, bilateral adnexal tenderness, 18k leuks
a. appendicitis, NOT bacterial vag, chancroid, diverticulitis, gonorrhea, herpes, trichomoniasis 8. How does prednisone blocking T Lymph help in chrons 9. poorly controlled DMII, ESRD, HTN, subclavian cath below right clavicale -> nonhemolytic, catalase neg Gram +
cocci in pairs/chains a. Enterococcus faecalis
OTHERS
small cell lung carcinoma lamer-eaton
mallory hyaline in alcoholic liver
hypotensive old low BP cant up with IV fluids, high CO, low PCWP, low SVR o septic shock? o GI bleed? o hypothyroid? o massive PE? o
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