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* NBME FORM 19 question
  cherryhemangioma - 03/05/17 05:21
  (1) A 58 yr old woman comes to the physician bcos of 3 month history of fatigue, weakness, loss of appetite, & weight loss. her serum parathyroid hormone conc are increased. Xrays of the skeletal system show generalized osteopenia, with subperiosteal resorption of bone within the phalanges. which of the following mechanisms is most likely cause of skeletal changes observed in this patient?
a)impaired calcification of preformed osteoid
b)paracrine stimulation of osteoclasts by osteoblasts
c)parathyroid hormone-mediated inducton of calcitonin
d)parathyroid hormone-mediated induction of interleukin-1 (IL-1)
e)parahyrod hormone-mediated production of transforming growth factor- β1

(2) Α 23 yr old comes into the student health center because of a 2 week hstory of vaginal sore. she has been sexually active with a new partner, and they use condoms inconsistently. pelvic examination shows a non tender ulcer on the vulva. dark-field examination of a scraping of the lesion is positive for spirochetes. which of the following histologic changes is most likely to be seen on a biopsy specimen of this lesion?
a)acute inflammation with abcess formation
b)granuloma with caseation and plasma cell infiltration
c)granuloma with suppuration
d)obliterative endarteritis with lymphocytes and plasma cells
e)pyogranulomatous inflammation with edema

(3) A 27 yr old woman has an episode of pneumococcal pneumonia that is treated with pencillin. after 2 days of therapy, she becomes jaundiced and has anemia charecterized by an increased reticulocyte count and an increased unconjugated bilirubin concentration. which of the following tests would most likely explain her present findings?
a)direct antiglobulin (coombs) test
b)serum antinuclear antibody assay
c)serum ferritin measurement]d)serum lactate dehydrogenase assay
e)urinary protoporphyrin measurement

(4) An investigator studying the function of voltage gated sodium channel develops a mutant from of the channel that inactivates more rapidly than normal. which of the following is the most likely effect of this mutation on the electrical properties of the neuron?
a)increases the amlitutde of the action potential
b)decreases the max freq of action potential production
c)increases the conduction velocity of the axon
d)increases the input resistance of the axon
e)increases the rate of depolarization of the action potential
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* Re:NBME FORM 19 question
  inclusions - 03/05/17 06:24
1 - b
2 - d
3 - a
4 - b
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* Re:NBME FORM 19 question
  cherryhemangioma - 03/05/17 10:49
  @ inclusions are u sure can u explain ur choices plz? Also 4 is not b that's what I choose and it wasn't correct  
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* Re:NBME FORM 19 question
  inclusions - 03/05/17 13:39
  sorry, my bad. b is not right of Q4. i misread the question. i read voltage-gated 'calcium' channel instead of sodium. and if it was calcium channel, b would be the right choice.

i think the answer is D. i think they r talking about refractory period, and not cable properties of axon, such as time and length constant because i don't see how they would be affected.

A is not right because they r talking about neuron action potential, not receptor potential. action potential in a cell (including neurons) is all or none response, so amplitude doesn't change.

B would be the case if it was calcium channel

it is not C because conduction velocity depends on the size of current and if Na channels get inactivated sooner, that is gonna decrease current.

i don't think it is not E either because dV/dT also depends on the size of current and in this case the size would be decreased.

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* Re:NBME FORM 19 question
  inclusions - 03/05/17 13:50
  Q1 is b, because it describes how PTH acts on the bone to cause reposition. it acts on osteoblasts to produce RANKL which then binds to RANK receptor on osteoclasts to cause resorption.

Q2 is d. remember how tertiary syphilis produces inflammation of the vasa vasorum of aorta and causes obliterative endarteritis? well, Goljan in his lecture says that treponema palladium acts by the exact same mechanism in all stages. painless chancre is produced because syph kills vasa nervorum surrounding the ulcer, hence painless chancre.

Q3 describes the case in which Tx w penicillin produces hemolytic anemia. hemolytic anemia was caused by antibodies directed to penicillin bound to red blood cells. Direct Coombs detects antibodies bound to blood cells, so right answer is A. indirect coombs detects antibodies just hanging out in the serum. but in this case antibodies were actually directed to RBCs, so direct coombs.
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* Re:NBME FORM 19 question
  inclusions - 03/05/17 13:58
  if anyone has any other idea on Q4, please, post ur thoughts. thanks.  
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* Re:NBME FORM 19 question
  cherryhemangioma - 03/05/17 23:53
  @inclusions : thanks for all the help.... okay so if they ask specifically about gummas it's granulomatous lesion?  
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* Re:NBME FORM 19 question
  inclusions - 03/06/17 00:57
  no problem. yes, if it asked about gummas then i would choose granulomatous lesion as an answer.  
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* Re:NBME FORM 19 question
  destinyia - 06/20/17 13:34
  Q4 the answer is definitely not C. I chose C and on my extended version it was marked wrong.  
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* Re:NBME FORM 19 question
  tchops - 06/20/17 17:55
  i chose e and it was wrong....!?  
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* Re:NBME FORM 19 question
  tchops - 06/20/17 18:14
  should it be d..!?  
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