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* NBME 13 Discussion Block 2 q1-50
 #756652  
  ae0704 - 11/03/13 08:38
 
  Hello All, since it seems there isn't an available thread discussing and explaining the answers like maryam2009 and sarim used to post of NBME 13, i'll be posting them following this order--->http://www.mediafire.com/?i9pp453yl0aas3i Posted by @larva.

Link to Block 1 Discussion: http://www.usmleforum.com/files/forum/2013/1/756580.php

Please feel free to add and help w/ the explanations.

Thank you.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998323
  ae0704 - 11/03/13 08:43
 
  Q:#1
Answer: D


Cephalosporin MoA: Inhibit cell wall synthesis
Cephalexin is a 1st generation Cephalosporin, Use: PEcK (Proteus, E. coli, Klebsiella) and G (+).
Tox:Hypersensitivity reactions, Increase nephrotoxicity w/ aminoglycosides, Disulfiram like reaction.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998326
  ae0704 - 11/03/13 08:58
 
  Q:#2
Answer:A

type 1 = no insulin
given insulin [dependent on dose] - > decrease cAMP - > PFK2 activated [storage]

hyperglycemia - > leads to glyogen synthesis in NORMAL conditions***

since diabetic no insulin - > glucagon is present again after "few hours" + Epinephrine - > increase cAMP - > glycogen phosphorylase activation - > HYPERGLYCEMIA

Via @Zen786
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998333
  ae0704 - 11/03/13 09:27
 
  Q:#3
Answer:B


Hemochromatosis: AR, Genetic mutation of hemochromatosis prevents the expression of the HFE protein in the basolateral surface of intestinal cell where it normally binds to the transferrin receptor nd regulates transferrin/iron complex endocytosis into cells. As a result there's uptake proteins and and excessive amount of Fe absorbed in GI.
Triad: 1) Cirrhosis (micronodular) 2) Diabetes Mellitus 3) Skin pigmentation: Bronze.
Results in CHF and Increase the risk of Hepatocellular Carcinoma.
A/w HLA-A3... Can be 2ndary to chronic transfusions therapy ( ex B-thal major ptes).
Labs: Increase Fe and Ferritin, Decrease TIBC--> Increase Transferrin saturation.
Tx: Phlebotomy, deferoxamine
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998335
  ae0704 - 11/03/13 09:30
 
  Q:#4
Answer:A

Pulmonary Embolus: problem lies with Perfusion, because blood flow to the lung is blocked by the embolus. Ventilation is not altered. V/Q ratio is infinite: Non-perfused but ventilated, the areas ventilated refered as "Dead Space"
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998338
  ae0704 - 11/03/13 09:34
 
  Q:#5
Answer:B


Cisplatin MoA: Cross-links DNA
Use: Testicular, bladder, ovary, and lung CA
Tox: Nephrotoxicity (Acute tubular injury preventable w/ Amiofistine (Thiol-based cytoprotective scavering agent, used to decrease cumulative nephrotoxicity)
Acoustic Nerve damage: Hair cells in cochlear membrane labyrinth specifically.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998340
  ae0704 - 11/03/13 09:37
 
  Q:#6
Answer: C


Abdominal Aortic Aneurysm (AAA): due to severe atherosclerosis. usually men >55 y/o. Located usually below renal orifices.
pulsatile abdominal mass. Complication--> Rupture, presents as Abdominal pain radiating to back, Tq and hypotension.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998341
  ae0704 - 11/03/13 09:38
 
  Q:#7
Answer: Missing question from file.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998343
  ae0704 - 11/03/13 09:42
 
  Q:#8
Answer:B

Winged Scapula: Caused by Injury to Long Thoracic nerve (C5-C7 ventral rami) results in paralysis of the serratus anterior muscle leading to weakness in the ability to protract the scapula and inability to aBduct shoulder past 90 degree..
Causes: Penetration trauma or iatrogenically during axillary lymph node dissection during mastectomy.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998346
  ae0704 - 11/03/13 09:59
 
  Q:#9
Answer: C

Multiple Myeloma: Neoplastic B-lymphocytes mature into plasma cell that synthesize abnormal typically large amounts of monoclonal immunoglobulins or immunoglobulin fragments (ex: Light chains). median age of dgx is 70y/o
Presents w/:
1)Normocytic Normochromic Anemia due to Bone marrow infiltration and replacement by malignant cells-->suppression of normal hematopoiesis and weakness.
2) Lytic Bone lesions: Secretion of IL-1 (osteoclast activating factor) and IL-6 activates osteoclast and lead to bone resorption leading to Osteopenia---> Presents w/ Pathologic fractures--> Bone pain and hypercalcemia due to the increase of bone destruction.
3)AL amyloid: due to accumulation of monoclonal IG light chains. Deposits seen on heart, tongue, CNS and kidney.
4) Renal failure: Infiltration of kidney by plasma cell, deposition of amyloid, bence-jones proteins in urine, hypercalcemia and increase uric acid.

LABS:
SPEP: Presence of M protein
UPEP: Bence-jones (light chain)
Increase ESR, Ca.
Bone marrow sample: >30% plasma cell.
 
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* Re:NBME 13 Discussion Block 2 q1-50
#2998348
  ae0704 - 11/03/13 10:01
 
  Q:#10
Answer: A

Cluster headaches: Unilateral headache + tearing and rhinorrhea + Ocular pain every day at the same time over period of years. Tx 100% O2 , sumatriptan.
 
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