Test 213

1. Vancomycin:

a. is an aminoglycoside.

b. is recommended for intracameral use at the end of 
    cataract surgery to prevent endophthalmitis.

c. targets the RNA of bacteria.

d. is effective against MRSA.

e. is used intravitreally against Gram positive bacteria.

Answer
a.F   b.F   c.F   d.T   e.T
Although ending with -cin, it is not an aminoglycoside.
Vancomycin acts on the bacterial cell wall through 
interference with glycopeptide polymerization. It is 
effective against Gram positive bacteria and can be given intravitreally in endophthalmitis. It is effective against Gram positive bacteria. It is not recommended 
for routine intracameral use due to the emergence of resistant bacteria.

2. Sodium fluorescein:

a. has a higher affinity for plasma protein than indocyanine 
    green.

b. does not leak from the choroidal vasculature.

c. does not leak from normal retinal vasculature.

d. emits light of longer wavelengths than the one it 
    absorbs.

e. is excreted by the liver and kidneys.

Answer
a. F   b.F   c.T   d.T   e.T
Sodium fluorescein is about 75% bound to the plasma protein whereas indocyanine green about 90%. The non-bound fluorescein leaks out of the choroidal vasculature readily due to the presence of fenestrations. The retina vessels do not leak fluorescein in the absence of diseases due to the presence of blood-retina barrier. Fluorescein absorbs blue light and emits green light which has longer wavelengths. It is excreted by liver and kidneys.

 

3. Direct light reflex of the pupil is absent in:

a. lesion of the ipsilateral ciliary ganglion.

b. transaction of the ipsilateral optic nerve.

c. bilateral occipital lobe lesion.

d. topical application of phenylepherine.

e. complete ipsilateral third nerve palsy.

Answer
a.T   b.T   c.F   d.F   e.T
The occipital lobe is not involved in the pupillary light reflex. Phenylepherine dilate the pupil by stimulating the dilator muscle but dilator muscle can be overcome by strong sphincter constriction to bright light.
 

4. The following conditions give rise to red blood cells with increased 
     mean cell volume:

a. anaemia of chronic disease.

b. pernicious anaemia.

c. anaemia due to renal failure.

d. haemolytic anaemia.

e. thalassaemia.

Answer
a.F   b.T   c.F   d.T   e.F
Increased MCV in the presence of anaemia is seen in pernicious anaemia (or any anaemia due to folate or vitamin B12 deficiency). Haemolytic anaemia also gives a high MCV because of an increased 
number of reticulocytes which have a higher MCV than normal red blood cells. Anaemia of chronic disease and that due to renal failure are normochromic 
anaemia. Thalassaemia has red blood cells which are reduced in size.
 

5. Berry aneurysm:

a. is a congenital disorder.

b. is found most commonly in the posterior portion of 
    the circle of Willis.

c. is symptomatic in majority of patients.

d. has absent intima elastica.

e. are associated with polycystic kidneys.

Answer
a.T   b.F   c.F   d.T   e.T
Berry aneurysm is a common cause of subarachnoid haemorrhage. It is asymptomatic in the majority
of patients. More than 80% of berry aneurysms are found in the anterior anterior portion of the circle of Willis. Histologically, there is absent of intima elastica.
The condition is associated with polycystic kidneys, Marfan's syndrome, Ehler-Danlos' syndrome and type III collagen deficiency.

 

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