Prekallikrein-Kallikrein conversion rate as a predictor of contrast material catastrophies

An in vitro is described that attempts to detect patients with a potential for adverse systemic reactions to contrast material. This test involves measuring the rate of conversion of prekallikrein to kallikrein under certain standard conditions. In a preliminary retrospective study, the test could be used to identify such patients with a sensitivity of 88%, a specificity of 82%, and a predictive value of 79%.     

A behavioral window on the mind of the market: an application of the response time paradigm

This article focuses on the role of implicit knowledge consumers have about particular brands, products or names. The major findings of several studies, conducted at the Mind of the Market Laboratory at Harvard Business School, are presented with specific emphasis on studies in which response time measurements were the core method. The results revealed that implicit measures provide a rich understanding of the meaning conveyed by a product or brand. Moreover, there is also considerable evidence that implicit measures may be better than traditional explicit measures as predictors of consumer behavior. We discuss the implications for the study of consumer behavior and the importance of combining several methods including neuroimaging, which has received recent attention by marketers, economists and social scientists.     

In vitro flow evaluation of recombinant tissue factor pathway inhibitor immobilized on collagen impregnated Dacron

Recombinant tissue factor pathway inhibitor (rTFPI) was immobilized on collagen impregnated (CI) knitted Dacron surfaces and its resistance to fibrin deposition evaluated following exposure to nonanticoagulated whole blood. Recombinant TFPI readily adsorbed to the CI Dacron surface and maintained its inhibitory activity. Under static conditions, rTFPI treated CI Dacron showed little fibrin deposition when compared with untreated surfaces. Treated samples exposed to flowing native blood at wall shear rates of 100 or 200 sec(-1) also demonstrated reduced fibrin deposition (up to 56%) compared with untreated samples. To assess the relative roles of the contact and tissue factor pathways in fibrin formation on artificial grafts, flow studies were performed with whole blood containing corn trypsin inhibitor, a potent inhibitor of FXIIa and contact activation. Corn trypsin inhibitor reduced fibrin deposition on untreated CI Dacron by 40%. Immobilized rTFPI alone, or corn trypsin inhibitor in combination with immobilized rTFPI, reduced fibrin deposition by 58% and 61%, respectively. These data suggest that immobilized rTFPI slows fibrin deposition on the vascular graft material by inhibiting both the contact pathway and blood borne tissue factor procoagulant activity arising from either the alternatively spliced form of tissue factor or from tissue factor containing microparticles.     

Localization of tissue factor pathway inhibitor to lipid rafts is not required for inhibition of factor VIIa/tissue factor activity

Tissue factor pathway inhibitor (TFPI) abrogates coagulation initiated by the factor VIIa/tissue factor catalytic complex. While the gene structure of TFPI suggests that it is a secreted protein, a large pool of TFPI is associated with the vascular endothelium through its affinity for a glycosylphosphati-dylinositol (GPI)-linked membrane protein. Inhibition of tissue factor by TFPI coincides with the translocation of quaternary complexes containing tissue factor, factor VIIa, factor Xa, and TFPI to detergent-insoluble plasma membrane domains rich in cholesterol, sphingomyelin, and GPI-linked proteins known as lipid rafts and caveolae. It is not known if localization of TFPI to these membrane domains is required for its inhibition of tissue factor procoagulant activity. We generated chimeric TFPI molecules linked directly to the plasma membrane via a GPI anchor or hydrophobic transmembrane domain and expressed these in HEK293 cells that produce tissue factor but not endogenous TFPI. The GPI-anchored chimera was exclusively enriched in detergent-insoluble membrane fractions while the transmembrane molecule was not. Transfectants expressing equal levels of the GPI-linked or transmembrane TFPI displayed equal anticoagulant potency as assessed by tissue factor-mediated conversion of factor X to factor Xa. Disruption of lipid rafts with cyclodextrin likewise had no effect on the inhibitory activity of the transmembrane or GPI-linked TFPI chimeras in HEK293 cells, nor on endogenous TFPI expressed by ECV304 cells. Thus, we conclude that the GPI anchor and membrane localization to lipid rafts does not enhance inhibition of factor VIIa/tissue factor by cell-surface associated TFPI.     

Effective screening for Alzheimer's disease among older African Americans

Relatively little data exist concerning the utility of brief cognitive measures to detect dementia among African Americans. The current study evaluated the clinical utility of the Mini-Mental Status Exam (MMSE) and the Fuld Object Memory Evaluation (FOME) in detecting Alzheimer's disease (AD) among both African American and European American older adults. One hundred and forty geriatric patients from a large urban academic medical center were examined. Overall, the FOME appeared to be more effective in detecting AD than was the MMSE (93% sensitivity vs. 75% sensitivity, respectively), although both measures suffered from relatively low specificity (63.5) in the full sample. The FOME demonstrated exceptional clinical utility among African American patients (sensitivity 98.3%; specificity = 64.5; positive predictive power 83.8%; negative predictive power 95.2%). The results of this study support the use of the FOME among older African Americans to detect dementia.