Identification of human thrombin-activatable fibrinolysis inhibitor in vascular and inflammatory cells.

TAFI (thrombin-activatable fibrinolysis inhibitor) is a carboxypeptidase zymogen originally identified in plasma. The TAFI pathway helps to regulate the balance between the coagulation and fibrinolytic cascades. Activated TAFI (TAFIa) can also inactivate certain pro-inflammatory mediators, suggesting that the TAFI pathway may also regulate communication between coagulation and inflammation. Expression in the liver is considered to be the source of plasma TAFI. TAFI has also been identified in platelets and CPB2 (the gene encoding TAFI) mRNA has been detected in megakaryocytic cell lines as well as in endothelial cells. We have undertaken a quantitative analysis of CPB2 mRNA and TAFI protein in extrahepatic cell types relevant to vascular disease. Using RT-PCR and quantitative RT-PCR, we detected CPB2 mRNA in the human megakaryoblastic cell lines MEG-01 and Dami, the human monocytoid cell line THP-1 as well as THP-1 cells differentiated into a macrophage-like phenotype, and in primary human umbilical vein and coronary artery endothelial cells. CPB2 mRNA abundance in MEG-01, Dami, and THP-1 cells was modulated by the state of differentiation of these cells. Using a recently developed TAFIa assay, we detected TAFI protein in the lysates of the human hepatocellular carcinoma cell line HepG2 as well as in MEG-01 and Dami cells and in the conditioned medium of HepG2 cells, differentiated Dami cells, and THP-1 macrophages. We have obtained clear evidence for extrahepatic expression of TAFI, which has clear implications for the physiological and pathophysiological functions of the TAFI pathway.

Secretion and antifibrinolytic function of thrombin-activatable fibrinolysis inhibitor from human platelets.

BACKGROUND: The thrombin-activatable fibrinolysis inhibitor (TAFI) is a zymogen first characterized in human plasma that is activated through proteolytic cleavage by thrombin, thrombin in complex with thrombomodulin, or plasmin. Active TAFI attenuates fibrinolysis by removing C-terminal lysine residues from partially degraded fibrin, thereby inhibiting a potent positive feedback loop in the fibrinolytic cascade. The existence of a separate pool of TAFI within platelets has been described. OBJECTIVES AND METHODS: We aimed to confirm the presence of TAFI in the medium of washed, thrombin-stimulated platelets and to evaluate the characteristics of platelet TAFI by western blot analysis and with a quantitative assay for activated TAFI. We also assessed the ability of platelet TAFI to inhibit fibrinolysis in vitro, using a platelet-rich thrombus lysis assay. RESULTS: Our data are consistent with the presence of TAFI in the α-granules of resting platelets. In contrast to previous reports, platelet TAFI is very similar in electrophoretic mobility to plasma-derived TAFI. We also show, for the first time, that platelet-derived TAFI is capable of attenuating platelet-rich thrombus lysis in vitro independently of plasma TAFI. Moreover, we demonstrate additive effects on thrombolysis of platelet-derived TAFI and TAFI present in plasma. CONCLUSIONS: Taken together, these observations indicate that the secretion of platelet-derived TAFI can augment the concentrations of TAFI already present in plasma to enhance attenuation of the fibrinolytic cascade. This could be significant in regions of vascular damage or pathologic thrombosis, where activated platelets are known to accumulate.

Computer technology in institutional foodservice.

A survey research study profiled foodservices and foodservice managers in health care and educational institutions that applied computer technology to their operations. The survey also examined the extent to which computers were applied to management and client service functions. Both the size and the type of institution were found to be significantly related to computer usage. The larger the institution, the greater the extent of indicated usage. Educational institutions used computers more than all types of health care institutions. Mainframe systems (time shared internally or externally) were the predominant computers used. Internal mainframe systems and minicomputers were used significantly more by educational institutions than by health care institutions. The manager most likely to use computers was a man of any age with at least a bachelor's degree who was employed full-time within the institution. He had taken at least six business management courses and had at least some understanding of and ability to apply systems management concepts to his daily management practices. Applications were categorized into five functional areas: menu, purchasing/storage, production, client service, and managerial information. Managerial information applications were most frequently reported by all respondents, with large institutions and elementary/secondary schools reporting the greatest usage for those applications. Several purchase/storage and production applications were significantly related to type or to size or to both, with large institutions and college/university foodservices reporting the greatest usage. Menu precosting was the only significant menu function, and that was significant only relative to institutional type. No client service functions were significantly related to either type or size.