The red cell membrane in hemolytic anemia.
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Abetalipoproteinemia↗
Biomedical subjects
S J Shattil
Publications and source records attributed to S J Shattil.
The efficacy of intensive plasma exchange in acquired von Willebrand's disease.
This study describes the response to therapeutic plasma exchange in a 60-year-old man with Waldenström's macroglobulinemia who developed a clinically severe bleeding disorder with laboratory features characteristic of acquired von Willebrand's disease. The patient's plasma levels of factor VIII coagulant activity, von Willebrand's factor antigen, and ristocetin cofactor activity were all less than 15 percent of normal, and the bleeding time was more than 20 minutes. In vitro studies did not demonstrate an inhibitor to factor VIII/von Willebrand factor, nor was a precipitating antibody to von Willebrand's factor antigen found in the patient's plasma. Neither infusions of cryoprecipitate nor combination chemotherapy corrected the clinical or laboratory abnormalities. In contrast, plasma exchange corrected the in vitro coagulation abnormalities and was effective in preventing surgical hemorrhage and controlling severe mucosal bleeding on 11 separate occasions. The current case demonstrates that the clinical and laboratory abnormalities in a patient with acquired von Willebrand's disease can be corrected completely by plasma exchange; it is recommended therefore that plasma exchange be considered as a mode of therapy in symptomatic patients with this disorder.
Bleeding Time↗
Flow cytometric studies of platelet responses to shear stress in whole blood.
The objective of this work was to evaluate quantitatively the effects of flow on platelet reactions using a flow cytometric technique. Whole blood was exposed to well defined, laminar shear stress in a cone-and-plate viscometer in the absence of added agonists. Blood specimens were fixed with formaldehyde and incubated with two monoclonal antibodies. Antibody 6D1, specific for platelet membrane glycoprotein Ib (GPIb), was used to identify and enumerate platelets and platelet aggregates on the basis of their characteristic forward scatter and 6D1-FITC fluorescence profiles. Anti-CD62 antibody, specific for the granule membrane protein-140 (GMP-140), was used to measure platelet activation. Results showed platelet aggregation increasing with increasing shear stress with marked increase in this response for a pathophysiological stress level of 140 dyn/cm2 and higher. This stress level also was the apparent threshold for formation of large platelet aggregates ("large" refers to particles larger than 10 microns in equivalent sphere diameter). These platelet responses to shear stress were insensitive to aspirin, but strongly inhibited by agents that elevate platelet cyclic adenosine monophosphate (cAMP) levels. Moreover, pre-incubation of whole blood with monoclonal antibodies that inhibit von Willebrand factor binding to GPIb or von Willebrand factor and fibrinogen binding to GPIIb/IIIa inhibited platelet aggregation. Aggregation induced by shear at 37 degrees C was less in extent than at 23 degrees C. At physiological shear stresses, whole blood was more susceptible to shear-induced platelet aggregation than platelet-rich plasma. This study reaffirms that flow cytometric methods have several important advantages in studies of shear effects on platelets, and extends the methodology to whole blood unaltered by cell separation methods.
Adult↗