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