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2015-02-07 12:40:30
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  1. This microorganim contains metachromatic granules.
    • Cornyebacterium diptheriae
    • Blue and red granules
  2. This microorganism contains blue and red granules.
    • Corynebacterium diptheriae
    • Metachromatic (blue and red) granules
  3. This organism stains deeply with aniline dyes.
    • Corynebacterium diptheriae- metachromatic granules stain with aniline dyes
    • E.coli- methylene blue
  4. How does the AB exotoxin of Corynebacterium diptheriae work?
    • B- (binding) subunit binds specifically to the heparin-binding epidermal growth factor receptor found on cardiac and neural cells.
    • A- (active) subunit inhibits host cell protein synthesis by catalyzing the ADP ribosylation of protein elongation factor 2 (necessary for tRNA to insert new amino acids into the growing protein chain during translation).
  5. What is the importance of ADP ribosylation of protein elongation factor 2?
    Necessary for tRNA to insert new amino acids into the growing protein chain during translation.
  6. What are the superantigens causing shock? Describe their mechanism.
    • Staphylococcus aureus- Toxic shock syndrome toxin (TSST-1)
    • Streptococcus pyogenes- Exotoxin A
    • Bring MHC II and TCR in proximity to outside of antigen binding site to cause overwhelming release of IL-1, IL-2, IFN-γ and TNF-α →shock
  7. What is the mechanism of Clostridium tetani?
    • Tetanus toxin (and botulinum toxin) are proteases that cleave SNARE proteins for neurotransmitters. 
    • Blocks release of GABA and glycine.
  8. What is the toxin produced by clostridium perfringens?
    Alpha toxin or Phospholipase C that degrades tissue and cell membranes
  9. Which microorganism produces the alpha toxin?
    Clostridium perfringens
  10. Phospholipase C is produced by this microorganism.
    Clostridium perfringens
  11. This toxin degrades cell membranes.
    • Clostridium perfringens
    • Alpha toxin/ Phospholipase C (lecithinase)
  12. Describe the histology of the intestinal villi.
    • Component of lamina propria
    • Covered by simple columnar epithelium wth a brush boarder (surface absorptive cells), containing goblet cells and AUPD (amine precursor uptake and decarboxylation cells)
  13. What are the crypts of Lieberkün and where are they located?
    • Component of lamina propria.
    • Simple tubular glands that rest immediately above the muscular mucosae and deliver secretions into the intervillar spaces.
    • Duodenum, jejunum, ileum
  14. What are the brunners glands? Where are they located?
    • Located in the submucosa
    • Secrete bicarbonate/ alkaline mucous
    • Unique to the duodenum
  15. Glands located in the intestinal submucosal layer is characteristic of?
    • Brunners glands.
    • Unique to the duodenum
  16. What mode of inheritance is phenylketonuria?
    Autosomal recessive
  17. How does Phencyclidine work?
    Works primarily by antagonizing the NMDA (N-methyl D-aspartate) receptor leading to excessive release of excitatory neurotransmitters.
  18. Describe the distinguishing features of Phencyclidine intoxication.
    • Violent behaviour
    • Nystagmus
    • Homicidality
  19. What is the mechanism of action of Cocaine?
    Blocks the reuptake of dopamine, norepinephrine and serotonin at CNS synapses.
  20. What are the signs and symptoms of Cocaine abuse?
    • Tachycardia
    • Hypertension
    • Mydriasis (pupillary dilation)
    • Chest pain/ angina
    • Seizures
  21. What are the symptoms of Heroin intoxication?
    • CNS and Respiratory depression
    • Miosis (pupillary constriction)
    • Seizures (overdose)
    • ↓gag reflex
  22. Mydriasis (pupillary dilation) is a feature of which drug intoxication?
  23. Meiosis (pupillary constriction) is a feature of which drug intoxication?
    Opoids e.g Heroin
  24. Describe the clinical features of marijuana intoxication.
    • ↑appetite
    • Impaired time perception
    • Conjunctival injection
  25. What is the mechanism of action of Methamphetamine?
    ↑ catecholamines at the synaptic cleft, especially norepinephrine and epinephrine
  26. What are the clinical manifestations of Methamphetamine intoxicity?
    • Tachycardia
    • Hypertension
    • Agitation
    • Diaphoresis (excessive sweating)
    • Violent behavious
    • Act like NE
  27. What are the non-dihydropyridine Ca2+ channel blockers?
    • Verapamil
    • Diltiazem
  28. What does negative chronotropy mean?
    ↓Heart rate
  29. What are effects of non-dihydropyridine Ca2+ channel blockers on the heart?
    • Verapamil
    • Diltiazem
    • ↓Heart rate- Negative chronotropy
  30. Where are peripheral chemoreceptors located and what stimulates them?
    • Located in the carotid and aortic bodies
    • Stimulated by ↓PO2 (<60mmHg)
  31. Where are the central chemoreceptors located and what stimulates them?
    • Located in the medulla.
    • Stimulated by ↑PCO2
  32. What causes a negative transepithelial potential difference in patients with Cystic Fibrosis?
    ↑Na+ reabsorption
  33. Describe the pathogenesis of the  food poisoning caused by S.aureus.
    • Due to ingestion of preformed toxin short incubation period (2-6 hr) followed by non-bloody diarrhea.
    • Enterotoxin is heat stable → not destroyed by cooking
  34. This type of microorganism causes food poisoning by ingestion of preformed exotoxin.
    • S.aureus
    • Bacillus cereus
  35. Describe the pathogenesis of the food poisoning caused by Bacillus cereus.
    Caused by cereulide, a preformed toxin.
  36. Food poisoning resulting from exotoxin formed AFTER ingestion is caused by which organisms?
    • ETEC
    • EHEC
    • Shigella
    • Vibrio cholera
  37. How do we calculate Attributable risk?
    • AR= Event rate (treatment)- Event rate (placebo)
    • AR= [a/ (a+b)] - [c/ (c+d)]
  38. How do we calculate number needed to harm?
    • NNH= 1- AR
    • AREvent rate (treatment)- Event rate (placebo)
    • AR[a/ (a+b)] - [c/ (c+d)]
  39. Describe the presentation of a Cluster headache.
    • Location: Unilateral, behind one eye 
    • Onset: During sleep/ hrs after going to sleep
    • Features: Excruciating sharp and steady preriorbital pain with lacrimation and rhinorrhea
  40. Describe the presentation of a Tension headache.
    • Location: Bilateral, band-like pain around the head
    • Onset: Under stress
    • Features: Steady pain. Dull, tight, persistent pain. Muscle tenderness in head, neck and shoulders. NO PHOTOPHOBIA, AURA OR PHONOPHOBIA!
  41. What is the most common cause of a subarachnoid hemorrage?
    Berry aneurysm
  42. A severe, sudden-onset "thunderclap" headache is characteristic of?
    Subarachnoid hemorrage
  43. Describe the presentation of tic douloureux.
    • Trigeminal neuralgia (tic douloureux)
    • Sudden "electric" pain/ repetitive shooting pain in the distribution of the maxillary and mandibular division of the trigeminal nerve.
    • Episode lasts less than a minute.
  44. In gluconeogenesis, biotin is needed in the conversion of?
    • Pyruvate → Oxaloacetate 
    • By Pyruvate carboxylase in the mitochondria
  45. What causes traumatic aortic rupture and where is the most common site of injury?
    • Most often caused by the rapid deceleration that occurs in motor vehicle collisions. 
    • The most common site of injury is the aortic isthmus, which is tethered by the ligamentum arteriosum.
  46. Label the image below.
  47. What is the Haemophilus influenzae type b vaccine composed of?
    Poly-ribosyl-ribitol phosphate
  48. When does linear growth stop?
    When the epithelial growth plate closes, i.e when the epiphysis fuses with the metaphysis
  49. What are the effects of sex hormones on growth?
    • They increase linear growth but they also encourage closure of epithelial plates
    • Hence precocious puberty may result in a shorter stature, despite an initial growth spurt.
  50. What is the MOA and use of Benzodiazepine ?
    • ↑ the frequency and opening of Cl- channels
    • USE: Anxiety, Muscle relaxant, hypnotic (insomnia), anticonvulsant
  51. What is the MOA of Barbiturates?
    ↑ the duration of Cl- channel opening 
  52. The use of opoids can lead to the development of tolerance of a ↓ in opoid effectiveness. In which side effect does it not occur?
    Tolerance to miosis and constipation does not occur.
  53. Who typically presents with aspiration pneumonia/ lung abscess? What is the antibiotic of choice for treatment?
    • Alcoholics- poor oral hygeine
    • Clindamycin
  54. The highest oxygen content in the fetal circulation is in the?
    Umbilical vein
  55. The ligamentum teres hepatis is the remnant of the?
    Umbilical vein
  56. What role does the ductus arteriosus play in fetal circulation?
    Shunts blood from the pulmonary artery to the descending aorta.
  57. What role does the ductus venosus play in fetal circulation?
    Blood from the umbilical vein is delivered to the liver, where it bypasses the hepatic circulation via the ductus venosus and enters the inferior vena cava.
  58. Describe the fetal circulation.
    • 1. Blood entering the fetus through the umbilical vein is conducted via the ductus venosus into the IVC to bypass the hepatic circulation.
    • 2. Most highly oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out the aorta to the head and body.
    • 3. Deoxygenated blood entering the RA from the SVC goes: RA → ŽRV → Žmain Pulmonary Artery → Ž patent ductus arteriosus → Ždescending aorta; due to high fetal pulmonary artery resistance (due partly to low O2 tension)
  59. Where do the umbilical arteries originate from?
    Fetal internal iliac arteries
  60. Bounding femoral pulses and carotid pulsations that are accompanied by head bobbing are characteristic of which heart murmur?
    Aortic regurgitation
  61. What are the clinical findings of Aortic regurgitation?
    • Bounding femoral and carotid pulses marked by abrupt distention and quick collapse ("water-hammer" pulses).
    • Some patients exhibit head-bobbing with carotid pulsations (de Musset sign).
  62. What is pulsus parvus et tardus? It is characteristic of which heart murmur?
    • Delayed prolonged carotid pulses
    • Aortic stenosis
  63. What is de Musset sign?
    Head bobbing- Aortic regurgitaion
  64. What are the protease inhibitors in HIV therapy?
    • They all end with -navir
    • Atazanavir
    • Darunavir
    • Fosamprenavir
    • Idinavir
    • Lopinavir
    • Ritonavir
    • Saquinavir
  65. What are the side effects of protease inhibitors?
    • They all end with -navir
    • Hyperglycemia
    • Lipodystrophy- increased deposition of fat on the back and abdomen, and decreased adipose tissue on the extremeties
    • Inhibition of CYP450
    • GI intolerance (nausea, diarrhea)
  66. A side effect of this anti-HIV medication is hyperglycemia
    • Protease inhibitors
    • They all end with -navir
    • Atazanavir
    • Darunavir
    • Fosamprenavir
    • Idinavir
    • Lopinavir
    • Ritonavir
    • Saquinavir
  67. This anti-HIV medication causes increased deposition of fat on the back and abdomen, and decreased adipose tissue on the extremeties.
    • Protease inhibitors
    • They all end with -navir
    • Atazanavir
    • Darunavir
    • Fosamprenavir
    • Idinavir
    • Lopinavir
    • Ritonavir
    • Saquinavir
  68. This anti-HIV medication is an inhibitor of cytochrome P450
    • Protease inhibitors
    • They all end with -navir
    • Atazanavir
    • Darunavir
    • Fosamprenavir
    • Idinavir
    • Lopinavir
    • Ritonavir
    • Saquinavir
  69. What drug should not be administered with protease inhibitors and why?
    Rifampin increases the activity of CYP450 and will therefore decrease the serum levels of protease inhibitors.
  70. What is the MC side effect of Zidovudine?
    Bone marrow toxicity resulting in anemia.
  71. Antibiotic used in the prophylaxis and tx of Mycobacterium avium intracellulare?
  72. Following administration of warfarin, patient presents with this painful lesion below. What causes it? How do we treat?
    • Protein C and S deficiency- thrombotic occlusion of microvasculature and skin necrosis
    • Tx: Fresh frozen plasma
  73. A large study of serum folate levels in a sample of women age 16-45 revels that this parameter is normally distributed with a mean of 5.0 ng/mL and a standard deviation of 5.0 ng/mL. According to the study results, 95% of serum folate observations in these patients will lie approximately between which of the following limits?
    • STEP1: Use the 68/95/99 rule
    • 68% lie within 1 SD of the mean
    • 95% lie within 2 SD of the mean
    • 99% lie within 3 SD of the mean
    • STEP 2: So we are going to use the 95% observation (2SD of the mean)
    • STEP 3: (5.0-2*0.5) & (5.0+2*0.5)
    • = 4.0-6.0