Hydroxyurea attenuates activated neutrophil-mediated sickle erythrocyte membrane phosphatidylserine exposure and adhesion to pulmonary vascular endothelium.

Activated neutrophils increase erythrocyte phosphatidylserine (PS) exposure. PS-exposed sickle red blood cells (SSRBCs) are more adhesive to vascular endothelium than non-PS-exposed cells. An increase in SSRBC fetal hemoglobin (HbF) concentration has been associated with improved rheology and decreased numbers of vasoocclusive episodes.

Activated neutrophil-mediated sickle red blood cell adhesion to lung vascular endothelium: role of phosphatidylserine-exposed sickle red blood cells.

Activated neutrophils (ANs) increase sickle red blood cell (SRBC) retention/adhesion in the pulmonary circulation. This study investigates the role of neutrophil activation and SRBC retention/adhesion in the pulmonary circulation through a mechanism that involves increasing phosphatidylserine (PS) exposure on the external membrane surface of the SRBCs (PS-exposed). With the use of flow cytometry, double-labeling studies were performed with a calcium-dependent phospholipid-binding protein, annexin V-fluorescein isothiocyanate fluorescence, and the erythroid-specific marker glycophorin A to assess for the percentage of PS-exposed normal and SRBCs at baseline and after coincubation with ANs.

Chondrocyte viability in refrigerated osteochondral allografts used for transplantation within the knee.

Purpose: To evaluate cell viability and matrix characteristics of refrigerated osteochondral allografts implanted up to 44 days after harvest.

Methods: Sixteen refrigerated allografts underwent histologic and ultrastructural examination and fluorescence excitation analysis prior to implantation. The average size of the graft implanted was 6.