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Repeated USMLE Questions Step 1- 367



Q- Which of the following is the main role of hydroxyurea in treatment of sickle cell anemia?

A- Decrease levels of HbF in red blood cells

B- Decrease oxygen affinity to HbS

C- Increase levels of HbF in red blood cells

D- Increase ability of HbS to bind 2.3-bisphosphoglycerate

C- Increase levels of HbF in red blood cells-This mechanism is not fully understood but hydroxyurea, by this action, leads to decreasing levels of HbS in RBCs.



Q- Which of the following methods is the most likely to demonstrate spores?

A- Acid-fast stain

B- Gram stain

C- India ink stain

D- Malachite green stain

D- Malachite green stain- Spores are observed by staining with malachite green and then alcohol treatment prevents decolorization and they will be counterstained.



Q- Paget disease of bone is characterized by which one of the following features?

A- Increase osteoblastic activity only

B- Increase osteoclastic activity only

C- Increase both osteoblastic and osteoclastic activity

D- Decrease osteoclastic activity

C- Increase both osteoblastic and osteoclastic activity- Paget disease of the bone is the only disease that combined both these features together. It is characterized by bone enlargement and arthritis



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