Ultrastructural localization of human platelet thrombospondin, fibrinogen, fibronectin, and von Willebrand factor in frozen thin section

We have investigated the localization of thrombospondin (TSP), fibrinogen, fibronectin, and von Willebrand factor in human platelets by transmission electron microscopy of antibody-stained ultrathin frozen sections. In negatively stained thin sections, alpha granules were identified on the basis of their smooth, roughly spherical shape, size, single limiting electron-lucent 100 A membrane, and frequent presence of electron-dense nucleoid. In contrast, mitochondria exhibited characteristic double membranes and cristae. Sections were separately stained with affinity-purified polyclonal antibodies to these proteins as well as with three monoclonal anti-TSP antibodies. Antibody specificity was documented in radioimmunoassays, by immunofluorescent cross-blocking, and by staining of bands of appropriate mobility in Western blots of whole platelets. Bound antibody was visualized using a 5-nm colloidal gold-avidin conjugate. In resting cells, staining of virtually all alpha granules was observed for all four proteins. In contrast, consistent staining was absent from other organelles, including plasma membranes, mitochondria, and vacuolar structures that may represent the open canalicular system.     

Characterization and quantitation of the circulating forms of serum transferrin receptor using domain-specific antibodies

To characterize the nature of the immunoreactive transferrin receptor in human serum, antisera were developed to peptide sequences of the extracellular domain of human transferrin receptor between amino acids 107 and 120 and the intracellular domain between amino acids 40 and 54. Antisera against the extracellular domain exhibited reactivity against both purified intact receptor and immunopurified circulating receptor, whereas antisera against the intracellular domain reacted only with intact receptor. Using competitive binding enzyme-linked immunosorbent assays, transferrin receptor in ultracentrifuged sera from normal subjects and patients with sickle cell anemia could be detected with antisera against the extracellular but not the intracellular domain. When the pellet obtained by ultracentrifugation of these sera was assayed after solubilization in 1% teric (polyoxyethylene-9-lauryl ether), only 0.6% of total serum receptor was detected in normal subjects and 3.8% in subjects with sickle cell disease. Roughly equal amounts of this pelleted immunoactivity were detected with antibodies against the extracellular and intracellular domains. These results indicate that less than 1% of transferrin receptor in normal human sera is intact receptor consistent with an exosomal origin and that virtually all circulating transferrin receptor is in the form of a truncated extracellular domain.     

Trust in government and support for governmental regulation: the case of electronic health records

Background

This paper presents results from a public engagement effort in Nebraska, USA, which measured public opinions about governmental involvement in encouraging the use of electronic health records (EHRs).

Objective

We examine the role of trust in government in contributing to public support for government involvement in the development of EHR technologies. We hypothesize that trust in government will lead to support for federal and state governmental encouragement of the use of EHRs among doctors and insurance companies. Further, because individual experiences with health‐care professionals will reduce perceptions of risk, we expect that support for governmental involvement will be tempered by greater personal experience with the health‐care industry.

Design and Results

Examining a small survey of individuals on the issue, we find general support for both of our hypotheses. The findings suggest that trust in government does have a positive relationship with support for government involvement in the policy domain, but that the frequency of personal experiences with health‐care providers reduces the extent to which the public supports governmental involvement in the development of EHR technology.

Discussion and Conclusion

This inquiry contributes to our understanding of public attitudes towards government involvement in EHRs in the United States specifically and contributes to social science examining links between trust in government and support for governmental activity in the emerging policy domain regarding electronic health records systems.