nbme 3 - myod

[ArchivalUser]

A 10-month-old boy with hemoglobin SS disease is brought to the emergency department by his parents because of severe pain in his feet for 2 hours. He appears acutely ill and is crying. Vital signs are normal except for a pulse of 160/min. Physical examination shows splenomegaly and edematous, tender feet. Laboratory studies show a hemoglobin concentration of 7 g/dL and a reticulocyte count of 12%. A peripheral blood smear shows target cells, poikilocytes, and sickled erythrocytes. Which of the following processes most likely caused the sickled erythrocytes in this patient?

A. Decreased interaction of hemoglobin S with spectrin upon deoxygenation
B. Inability of abnormal beta-chains to form tetramers upon deoxygenation
C. Inability of abnormal beta-chains to form tetramers upon oxygenation
D. Increased interaction of hemoglobin S with spectrin upon oxygenation
E. Spontaneous polymerization of hemoglobin S upon deoxygenation
F. Spontaneous polymerization of hemoglobin S upon oxygenation

[ArchivalUser]

E??

[ArchivalUser]

B ???:-p

[ArchivalUser]

i think its E ..when oxygen concentration decreases spontaneous polymerizaton of the sickle hemoglobin accurs

[ArchivalUser]

yea i thought that since you had valine replacing glutamate that the hydrophobic interactions b/w the cells lead to polymerization in states of acidosis, dehydration, low O2...