UWorld SA 2 Flashcards
What is the function of probenecid? Which other antimicrobial drugs function this way?
Inhibits renal tubular secretion of penicillins, cephalosporins and other weak organic acids -> prolongs action of drugs by slowing elimination
Cilastatin also has no antimicrobial activity but prevents PCT brush border hydrolysis of Imipenem, prolonging imipenem’s activity
What are hallmarks of congenital adrenal hyperplasia w/ excessive mineralocorticoid activity?
17 alpha-hydroxylase deficiency -> deficient production of Cortisol and androgens w/ increased mineralocorticoid (corticosterone) -> HTN and Hypokalemia will result from excess mineralocorticoid, low urine cortisol excretion, and blood pressure normalizes w/ exogenous cortisol
Which type of patient usually suffers from cough syncope? What is the cause for this?
Overweight male patients w/ COPD -> increased intrathoracic pressure during a coughing fit -> decreased venous return to the heart -> decreased cardiac activity and cerebral perfusion (can also be observed during valsalva maneuver via same mechanism)
What is the composition of the skin nodules in neurofibromatosis type 1 (von Recklinghausen disease)?
Loose and disorganized proliferations of Schwann cells, fibroblasts and neurites
What is visualized on sigmoidoscopy in someone w/ ulcerative colitis and what would biopsy reveal?
Scope = friable, inflamed mucosa in rectum and sigmoid colon
Biopsy = Collections of PMNs in crypt lumina
What is visualized w/ kaposi sarcoma involving GI tract?
Hemorrhagic nodules (biopsies not taken since lesions are submucosal and not restricted to sigmoid/rectum)
What occurs if a latex beta-hCG test is negative (i.e. not pregnant)?
Urine added to glass w/ anti-hCG antibodies -> when latex particles coated w/ beta-hCG are then added, they will agglutinate, because there are few urine beta-hCG molecules for the antibodies to bind (if urine beta-hCG levels were high, as in preggo, then all of the antibodies would get bound to them, and latex would not agglutinate)
What is the function of Paclitaxel? How can this be utilized outside of its normal function?
Antineoplastic drug that binds b-tubulin and prevents microtubule breakdown -> arrests cells in M phase of cell cycle
Can coat blood vessel stents w/ this drug to prevent intimal hyperplasia which would have caused stent restenosis
Which muscles attach to the acromial (lateral) end of the clavicle and what is the direction of force from these muscles?
Deltoid - pulls inferolaterally
Trapezius - pulls superomedially
What is the attachment and purpose of the pectoralis minor muscle?
Spans from coracoid process of scapula to ribs 3-5 -> holds scapula against thoracic wall
What is the most common urea cycle defect and what compounds accumulate?
Ornithine transcarbamoylase (OTC) in the mitochondrial matrix -> accumulation of carbamoyl phosphate which gets converted to OROTIC ACID (via pyrimidine biosynthetic pathway) and of course congenital HYPERAMMONEMIA (carbamoyl phosphate deficiency would NOT have orotic acid - think OTC w/ Orotic)
What is necessary for proper collagen triple helix formation?
Hydroxylation of proline and lysine residues on PRO-alpha-COLLAGEN, a process requiring vitamin C to form PRO-ALPHA CHAINS -> any problems -> abnormal triple helix formation in collagen molecules
What will result from excessive mineralocorticoid action? How would this affect renin levels?
Hypertension, hypokalemia, and metabolic acidosis
Renin would decrease because of HTN
What are the risk factors increasing the chance for developing herpes zoster? What should be indicated in a younger person presenting w/ zoster?
Advanced age and/or immunosuppression
Check young patients w. Zoster for HIV (immunosuppression)
What is the cause of particular human leukocyte antigen haplotypes that do not mount an effective IgG antibody response to a particular antigen?
HLA haplotypes that do not bind (recognize) a particular viral antigen are UNABLE TO PRESENT the antigen to T cells -> Impaired isotype switching to IgG antibody production
What is the purpose of HLA or MHC genes?
Human leukocyte antigen or major histocompatibility complex -> critical in the process of ANTIGEN PRESENTATION
What is the cause for respiratory acidosis and hypoxemia in a patient w/ pneumonia who is being kept on a respirator?
Inadequate ventilation from Worsening infection w/ increased dead space formation (since a machine is ventilating them the only possibility is a pathophysiological problem in the lung space)
What are opportunistic causes of diarrhea in HIV patients?
CMV, cryptosporidium, microsporidium, Mycobacterium avium complex
What would most likely be seen in an HIV patient w/ CMV diarrhea?
Multiple ulcers & mucosal erosions -> biopsy = large epithelial cells w/ basophilic intranuclear and intracytoplasmic inclusions (OWL EYE NUCLEI)
What is the most prominent CMV biopsy feature in all types of presentations?
OWL EYE NUCLEI -> Giant cells w/ large ovoid nuclei containing CENTRALIZED INTRANUCLEAR INCLUSIONS
What are the features of IVC obsturction? What is a likely cause of this?
Prominent abdominal wall collateral veins (especially if upper IVC segment is affected) and new unexplained severe lower extremity edema
could be from renal mass (especially if patient is middle aged smoker)
Which cell lines are increased in myeloproliferatie disorders?
Typically across all cell lines (including polycythemia vera) -> leukocytosis, thrombocytosis and erythrocytosis would be seen
What is the difference between conversion disorder and somatic symptoms disorder?
Conversion (functional neurological symptoms disorder) involves NEURO symptoms (not linked to actual neuro disease) and caused by ACUTE STRESSOR
SSD = chronic distress w/ multiple symptoms not linked to any pathological causes
What is pseudodementia?
Compromised cognitive fxn in patients w/ psych illness (e.g. severe depression)
What are the cytological features of a liposarcoma?
Round cells w/ multiple mitoses, and cells have round clear cytoplasmic vacuoles scalloping the nucleus
What murmur may be heard w/ Hypertrophic cardiac myopathy? What activities would alter the sound?
Systolic crescendo-decrescendo murmur between apex and left sternal border, radiating to suprasternal notch (murmur as a result of LV outflow obstruction)
Quieter w/ increases in preload or afterload (clenching fist) and louder w/ decreased in preload or afterload (e.g. standing up)
At what point on the pressure cardiac cath curve do the Aortic/Pulm valves close? When do the AV valves open?
S2 = just after the peak LV systolic pressure
AVs = open at the lowest point of LV systolic pressure
What may elevated CA 125 be a sign of, and what are some presenting signs for this condition?
Ovarian cancer -> vague Ab discomfort and distension, poor appetite and nausea, physical exam = right or left sided adnexal mass, free fluid possible in peritoneal cavity (note: CA 125 primarily for monitoring not diagnosis)
What ion changes will occur w/in cells affected by ischemia?
Ischemia -> decreasing intracellular ATP stores -> dysfxn of Na/K ATPase pump -> K+ leaks OUT of cell (down its electrochemical gradient) and Na+ leaks INTO cell
What is the reason behind Heparin’s greater safety over Warfarin in pregnant patients?
Heparin has a HIGH water solubility -> water soluble materials (e.g. conjugated BR) do not readily cross placenta) while lipophilic materials (e.g. Warfarin or unconjugated BR) cross placenta more readily
What are the effects of smoking cessation on pulmonary function?
Quitting will slow down the rate of pulmonary function loss but it will not improve function
What is recidivism?
Resumption of harmful activity after a period of abstince/rehab (i.e falling off the wagon)
What is genetic reassortment (in regards to Influenza virus)?
ANTIGENIC SHIFT - Two distinct influenza A viruses (1 HUMAN + 1 ANIMAL) infect the same cell -> Hemagglutinin (HA) from one + Neuraminidase (NA) from another get packaged together in a new viron -> potential to create new viral strains to which there is no immunologic resistance
What is antigenic drift?
Point mutations in HA and NA genes that slightly alter product proteins -> possibly will increase virus’ infectivity
What is represented by the initial peak of a jugular venous pressure curve?
a = Right atrial contraction (this collapse would cause the greatest back pressure onto jugular veins)
What do all the peaks in the JVP curve represent?
a = right atria contracts (largest peak) c = RV contracts (systole; smaller peak) x = Tricuspid closure, all blood starts to flow in (valley) v = maximal atrial filling (second large peak) y = Passive emptying of RA into RV (smaller valley, before RA contracts again)
What is the characteristic group of symptoms that may arise from pineal region tumors?
Lesion to the dorsal midbrain in region of superior colliculus -> PARINAUD SYNDROME -> Upward gaze palsy (dmg to CN 3/4), absent pupillary light relfex (dmg to Edinger-Westphal nucleus), failure of convergence, and Wide-based gait
What lesions will lead to lateral gaze palsies?
Pointine lesions affecting abducens nerve (CN VI) and possibly frontal lobe infarct
What is the purpose of the CAAT and TATA box?
TRANSCRIPTION INITIATORS
What is the earliest EKG change evident in patients with hyperkalemia? Other changes?
Peaked T-waves
-Loss of P wave, prolonged PR interval, widening of QRS complex and slowed heart rate can also occur.
What would happen to the urine pH in someone who is having forced hyperventilation while on a respirator?
Hypervent -> CO2 blown off -> respiratory alkalosis -> serum bicarb decreased in attempt to compensate by the kidneys = increased bicarb excretion and H+ retention in renal tubules => INCREASED pH (more alkaline)
How do you generate NE and epi from Tyrosine?
TYROSINE– tyrosine hydroxylase –> DOPA – L-amino acid decarboxylase –> DOPAMINE – dopamine hydroxylase –> NE –PNMT –> EPINEPHRINE
What can ddevelop from dopamine hydroxylase deficiency?
Impaired conversion of dopamine into Norepinephrine -> lack of NE leads to SANS problems -> Postural (orthostatic) hypotension, ptosis, nasal congestion and ejaculatory difficulties
What is the difference between the Sabin and Salk vaccines and what are the risks associated?
Sabin = “savin A life” -> Live attenuated vaccine administered orally -> provides IgA mucosal immunity but risk of progression to live form -> vaccine associated paralytic poliomyelitis
Salk = “sulky emo kid” -> Injected inactivated (killed) polio vaccine -> less risk of progression to live form (and enhanced version is now more immunogenic)
What can result from damage to the main branch of the posterior cord of the brachial plexus?
Radial nerve damage -> paralyze muscles of the extensor compartment of arm (triceps) AND forearm AND hands/digits -> difficulty extending hand at wrist and forearm at elbow
What happens to the filtration fraction as renal perfusion decreases (e.g. renal artery stenosis), and why?
Decreased perfusion stimulates JGA to release renin (tubuloglmoerular feedback mechanism) -> this will dilate afferent arteriole (increases GFR) and constrict efferent arteriole (increase GFR and decrease RPF) –> INCREASED FF
How does the CNS respond to venous blood pooling and decreased preload that occurs upon sudden standing?
Decreased preload -> decrease stroke volume, pulse pressure and CO -> carotid baroreceptor firing rate decreases -> CNS decreases vagal tone and increases sympathetic tone to SA node (beta 1) and blood vessels (alpha1) –> increased HR and total vascular resistance minimizing orthostatic changes (alpha1 most important)
What is a major risk factor responsible for orthostatic hypertension?
Under stimulation of sympathetic vascular alpha1-adrenergic receptors
What is the only FDA approved pharm treatment for obesity and its MoA?
Orlistat -> inhibiting intestinal lipase -> inhibits fat absorption in the gut (fenfluramine and epherine were withdrawn from market)
How may mumps infection present in an adult male? What is the patient at increased risk for, and what may improve symptoms?
Fever, malaise, headache, myalgias, anorexia, parotitis and ORCHITIS (pain tenderness and significant swelling of testes) => Seminiferous tubule atrophy (infertility) and Leydig cell atrophy (low testosterone) –> sexual deficiency can occur from this -> treat w/ Testosterone
What is danazol and what is it used for?
Androgen used to suppress FSH and LH release by pituitary –> used for many disorders including endometriosis, hemophilia, immune thrombocytopenic purpura and others
What are key features/presenting signs for infection with entamoeba histolytica?
Homosexual male w/ ab pain and diarrhea, guaiac positive and stool may reveal trophozoites w/ phagocytosed RBCs (“fag-ocytosed)
What are incretins and what are some examples of them?
GI hormones produced by gut mucosa -> stimulate pancreatic insulin secretion in response to sugar containing meals (e.g. Glucagon-like peptide-1 or GLP1 and gastric inhibitor peptide/glucose-dependent insulinotropic peptide or GIP) => these are the reason for a greater insulin response to oral glucose vs. IV glucose
What are cystic hygromas? What patients are prone to get them?
Cystic lymphatic malformations (lymphangiomas) usually involving loose areolar tissue of head/neck and present as -> Painless compressible “doughy” masses that transilluminate
Common w/ chromosomal abnormalities (Turner syndrome and trisomies 13, 18, 21)
Where do Kayser-Fleischer rings form?
Cornea of the eye
What are lisch nodules?
Hamartomas on the iris (associated w/ NF type 1
What is chromosomal mutation of 9p21 associated with?
CDKN2A (cyclin dependent kinase inhibitor 2A) gene mutation -> this protein encodes for negative regulator of cell cycle progression at G1/S checkpoint -> mutation interferes w/ CDK4 inhibition -> cells inappropriately advance in cell cycle –> high chance of developing melanomas
Which chromosome is involved in NF type 1? type 2?
NF1 = chromosome 17 NF2 = chromosome 21
What is seen on biopsy of NF1 nodules?
Spindle cells with wavy nuclei in an intense pink stroma
What is seen on biopsy of a dysplastic nevus?
Nests of nevomelanocytes with angulated, hyperchromatic nuclei and bridging with nests in neighboring rete pegs (dermoepidermal junction aggregates of large cells that fuse with adjacent nests, irregular nuclear contours w/ hyperchromasia)
What structures form nucleic acid-binding domains that allow for binding to specific DNA sites (e.g. for transcription factor purposes)?
- Zinc finger motif
- Helix loop helix
- Leucine zipper (short alpha-helix fragment w/ leucine residues at every 7th position)
Where does de novo synthesis of pyrimidine and purine nucleotides occur and what compounds are involved in the first step of the reaction?
Pyrimidine occurs in Cytosol -> glutamine, CO2 and 2 ATP -> Carbamoyl phosphate (rxn catalyzed by CPSynthetase 2)
Purine also in cytosol -> CO2 + carboxylase rxn
What are the presenting signs of a parathyroid adenoma? What may be found on surgical exploration and why?
“Painful bones, renal stones, abdominal groans, and psychic moans (depression, fatigue etc.)
a single enlarged parathyroid gland (the other PT glands are smaller from negative feedback inhibition b/c of high Ca levels)
What are the features of von Gierke disease? What is the treatment?
Type 1 glycogen storage disorder -> deficiency of glucose 6 phosphatas -> Hepatomegaly/steatosis, severe fasting hypoglycemia, lactic acidosis (b/c impaired gluconeogenesis), hyperuricemia/hyperlipidemia
PE: Poor growth w/ enlarged abdomen and renal enlargment
Tx = frequent oral glucose (uncooked cornstarch) and avoidance of fructose and galactose (cannot be converted to free glucose
What neurological signs would be present in patients w/ HTN who suffer from a HTN induced pontine intracerebral hemorrhage?
- Pinpoint pupils
- Loss of horizontal gaze
- Quadriparesis (rigid extended upper/lower extremities)
- Rapidly evolving coma -> death w/in hours
What signs would be present in thalamic intracranial hemorrhage?
Contralateral sensory loss, aphasia and temporary homonymous hemianopia
Also unilateral abducent nerve palsy, pupil assymmetry/nonreactivity and downward gaze may be present
How can intracerebral neoplasms raise the ICP?
2 major mechanisms:
- Obstruction of normal CSF flow
- Disruption of blood brain barrier -> increased vascular permeability -> plasma filtration into cerebral interstitium -> vasogenic edema
What is a classic finding in tetanus and one of the first locations affected?
Severe muscle spasms in the jaw –> LOCK JAW (from exotoxin of C. tetani)
How may severe hypercalcemia lead to dehydration? What disease may this be a result of?
Down-regulation of aquaporins in the collecting tubules –> impedes water reabsorption and resistance to action of vasopressin –> i.e. Nephrogenic diabetes insipidus (polyuria and polydipsia)
Squamous cell carcinoma of the lung may produce PTHrP which would lead to hypercalcemia
What is necessary for Clopidogrel to function in the body?
Administered as a prodrug that must be activated by hepatic cytochome P450 enzyme system (coadministration w/ CP450 inhibitor would decrease conversion of inactive prodrug into active metabolite)
What is the primary mechanism of resistance to penicillin/amoxicillin type anti-microbials? Cephalosporins?
Penicillinase in bacteria -> a beta-lactamase which cleaves beta-lactam rings
Cephalosporin resistance usually from structural changes in penicillin binding proteins (transpeptidases)
A drug is given to a patient with urinary retention following surgery. This drug increases phosphoinositide turnover in smooth muscle cells of bladder w/ no effect on nicotinic synapses, which drug is it and what is its MoA?
Bethanechol -> is a common drug given post-op for urinary retention and it is a cholinomimetic drug –> acts on M3 receptors (Gq coupled -> Phospholipase C cleaves PIP2 into DAG and IP3) to increase bladder contractions
What occurs in neonatal respiratory distress syndrome?
Surfactant deficiency –> increased surface tension –> alveolar COLLAPSE –> diffuse atelectasis
What are Kerley B lines?
Sign of pulmonary edema (CHF) on chest XRay
What is aortic insufficiency?
Aortic regurgitation
What is S3 most often associated with?
Increased filling pressures (mitral regurg, heart failure) and more common in DILATED ventricles
What are the features of a partial hydaditiform mole?
69 chromosomes (normal ovum + 2 sperm) ; FETAL tissue and partial fetal parts present; chorionic villi present w/ focal edema and trophoblastic proliferation
What is the complication of placenta accreta?
Placenta attaches to myometrium without penetrating it –> no separation of placenta after delivery –> postpartum bleeding that can cause Sheehan syndrome (increta is in myometrium and percreta penetrates/perforates through myometrium)
What does cocaine use in the mother put the fetus at increased risk for?
Abnormal fetal growth (prematurity) and fetal addiction
Placental abruption may also occur
What are some helpful methods of symptom relief for H. pylori associated peptic ulcer disease?
- Quit smoking
- Limit alcohol
- Antacids
Which large gram + rods are known to cause myonecrosis?
Clostridium Perfringens
What is the function of glycine in the nervous system?
Inhibitory NT in CNS, especially in spinal cord, brainstem and retina
Activation of glycine receptors -> chloride entry –> IPSP
What is the function of glutamate in the nervous system?
Glutamate is the most prominent NT in the body and is the main EXCITATORY NT (present in 50% of nervous tissue)
Also used to make GABA, the main inhibitory NT
What is the function of tetanus toxin?
Cleaves SNARE proteins preventing release of inhibitory NTs GABA and Glycine
What characteristic finding may develop from aneurysm of the posterior communicating artery?
Compression of parasympathetic output of CN III –> Diminished/absent pupillary light relex, “blown pupil” (dilated) often in “down and out” position
What is the inheritance pattern for cystic fibrosis?
Autosomal recessive
What are the X-linked recessive disorders?
“Be Wise, Fool’s GOLD Heeds Silly HOpe”
Bruton agammaglobulinemia, Wiskott aldrich syndrome, Fabry disease, G6PD deficiency, Ocular albinism, Lesch-nyhan syndrome, Duchenne and beckker muscular dystrophy, Hunter Syndrome, Hemophilia a and b, Ornithine transcarbamylase def
What are the autosomal recessive diseases?
Albinism, ARPKD, CF, glycogen storage diseases, hemochromatosis, Kartagener syndrome, mucopolysaccharidoses (except Hunter), PKU, sickle cell, sphingolipidoses (except Fabry), thalassemias, Wilson disease
What lab findings are elevated in alcoholic hepatitis?
increased AST, increased PT, mixed increase of conjugated & unconjugated BR (glucoronide)
What are the differences between Schizoid, Schizotypal and avoidant personality disorder?
Schizoid = distant; VOLUNTARY social withdrawal, content Schizotypal = magical thinking, eccentric appearance and odd beliefs Avoidant = Hypersensitive to rejection, socially inhibited/timid, but desires relationships w/ others (vs. Schizoid who are content w/ social isolation)
How can you differentiate cardiogenic vs. hypovolemic shock?
Hypovolemic has major reduction in preload vs. Cardiogenic (and obstructive) where preload and afterload are increased -> therefor they have increased CVP and would present w/ JVD, and pulmonary edema
What are the signs of external hemorrhoid?
Severe rectal pain, no bleeding, w/ a dark purplish round smooth bulge coming out of the anus
What agent is most helpful following abnormal uterine bleeding (e.g. following delivery of placenta)?
Progestins (progesteron) -> binds progesteron receptors and decreases growth and increases vascularization of endometrium
What are the symptoms associated w/ Prader wili and Angelman syndrome?
PW (paternal gene deleted) = Hyperphagia, obesity, intellectual disability, hypogonadism, hypotonia
Angelman (maternal gene deleted) = Inappropriate laughter (“happy puppet”) Seizures, ataxia and severe intellectual disability
What symptoms are associated w/ Fragile X syndrome?
Fragile X = eXtra large testes, jaw and ears; w/ long face, autism and mitral valve prolapse
Which enzymes would have increased activity in the liver w/ insulin administration?
Glycogen synthase and Glucokinase (present in liver, pancreas, gut and brain)
What is primarily affected in diffusion limited gas exchange?
Primarily O2 exchange, therefore alveolar CO2 levels will stay closer to normal (low CO2 and high O2 indicates perfusion defect)
What are the main side effects of Isoniazid therapy?
Neurotoxicity and Hepatotoxicity
What is the difference between lung compliance and recoil?
Compliance = ability to stretch during inhalation
Recoil = Ability to return to pre-stretch size during exhalation
What is necessary for pyruvate to be converted to phosphoenolpyruvate?
Must first be converted into oxaloacetate by pyruvate carboxylase w/ acetyl CoA as an allosteric activator
What is Rasburicase used for?
Reduce uric acid levels by converting UA into allantoin which is excreted in urine. Helpful for excess UA that occurs during the breakdown of tumor cells (which can lead to tumor lysis syndrome)
What is Probenecid?
Uricosuric agent (only use if renal fxn is good)
What is transpeptidase?
Penicillin binding protein that cross link peptidoglycan in the bacterial cell wall -> gets bound by beta-lactams
Which anti-hypertensive is the preferred agent to prevent cardiac remodeling?
ACE Inhibitors
What results from parainfluenza viruses (paramyxovirus)? Measles virus?
Parinfluenza = Seal-like barking cough and inspiratory stridor + Steeple sign on CXR
Measles (rubeola) (in paramyxo family) -> but causes cough, coryza, conjunctivitis and koplik spots followed by maculopapular rash (encephalitis and giant cell pneumonia can happen)
What is the cause for edema during an inflammatory response or anaphylaxis?
Histamine released -> separates endothelial cells –> fluid leaks into interstitial space via post capillary venules
