UWorld_2.25

Question 1

Biostats:

type I error =

type II error =

power =

Answer 1

• type 1 (a) = probablity of seeing a difference when there is no diffence in realtiy
  
  • a = p-value
• type 2 (B) = probablity of concluding that there is no difference between the groups when one truly exists
• power = ability of study to differentiate between two groups
  
  • power = 1 - B

Question 2

Drug effects:

tachyphylaxis =

additive =

synergistic =

permissive =

Answer 2

• tachy = decreased drug response w/repeated administration
• additive/synergistic = two drugs with similar actions
  
  • additive = admin of both is equal to the sum of the effects
  • synergistic = admin of both leads to effects exceeding the sum of the drugs individually
• permissive = admin of a different type of drug (without its own action @ desired site) leads to increased action of an effective drug if given together

Question 3

Klinefelter presentation

Answer 3

• 47 XXY
• hypogonadism
  
  • seminferous tubules destroyed and hyalinized ==> small, firm testes
  • leydig cells damaged ==> low T + erectile dysfxn
  • low T + low inhibin ==> elevated FSH/LH
  • ==> infertility
• long limbs (delayed epiphyseal fusion)

Question 4

Immune rxn to live polio vaccine vs. killed polio vaccine

Answer 4

• both ==> IgG immunity against polio
• live = oral admin ==> production of oropharyngeal and duodenal IgA
• killed = no IgA response

Question 5

AChE in amniotic fluid ==> dx?

Answer 5

• Neural tube defects = failure of fusion of neural tube during 4th week of fetal development
• ==> leakage of fetal CSF ==>
  
  • elevated alpha-fetoprotein
    
    • crosses placenta ==> elevated alpha-fetoprotein @ mother serum
  • acetylcholinesterase

Question 6

Congenital disease due to:

embryonic migration abnormality

failed apoptosis

Answer 6

• migration ==> hirschsprung’s disease
  
  • intenstinal wall lacks nerves
• apoptosis ==> duodenal atresia = failure of recaalization during fetal development

Question 7

Iodine transport @ thyroid

Answer 7

• sodium-iodide symporter brings iodine into thyroid against concentration gradient
• NIS is also responsible for transporting perchlorate and pertechnetate into thyroid
  
  • if potassium perchlorate is present ==> competitive inhibition

Question 8

Drugs that interfere with iodine uptake

Answer 8

• antithyroid thionamides
  
  • methimazole ==I thyroid peroxidase ==> blocked conversion of iodide to iodine
  • propylthiouracil
• usually stopped 7-10 days before tx w/radioactive iodine for hyperthyroidism

Question 9

EBV associated with….

Answer 9

• Hodgkin’s and Non-Hodgkin’s lymphoma
• EBV Burkitt’s lymphoma
• nasopharyngeal carcinoma

Question 10

Prolonged exposure to loud noise ==>

Answer 10

• hearing loss due damage of the sterociliated hair cells @ Organ of Corti
• noises > 85dB ==> distortion/fracture of sterocilia due to shearing forces against tectorial membrane