Astrocytes are the primary source of tissue factor in the murine central nervous system. A role for astrocytes in cerebral hemostasis.

Hemostasis in the brain is of paramount importance because bleeding into the neural parenchyma can result in paralysis, coma, and death. Consistent with this sensitivity to hemorrhage, the brain contains large amounts of tissue factor (TF), the major cellular initiator of the coagulation protease cascades. However, to date, the cellular source for TF in the central nervous system has not been identified. In this study, analysis of murine brain sections by in situ hybridization demonstrated high levels of TF mRNA in cells that expressed glial fibrillary acidic protein, a specific marker for astrocytes. Furthermore, primary mouse astrocyte cultures and astrocyte cell lines from mouse, rat, and human constitutively expressed TF mRNA and functional protein. These data indicated that astrocytes are the primary source of TF in the central nervous system. We propose that astrocytes forming the glia limitans around the neural vasculature and deep to the meninges are intimately involved in controlling hemorrhage in the brain. Finally, we observed an increase in TF mRNA expression in the brains of scrapie-infected mice. This modulation of TF expression in the absence of hemorrhage suggested that TF may function in processes other than hemostasis by altering protease generation in normal and diseased brain.     

Activation of coagulation and angiogenesis in cancer: immunohistochemical localization in situ of clotting proteins and vascular endothelial growth factor in human cancer.

Thrombin-catalyzed, cross-linked fibrin (XLF) formation is a characteristic histopathological finding in many human and experimental tumors and is thought to be of importance in the local host defense response. Although the pathogenesis of tumor-associated fibrin deposition is not entirely clear, several tumor procoagulants have been described as likely primary stimuli for the generation of thrombin (and XLF) in the tumor microenvironment (TME). In a previous study of a variety of human tumors we have shown that tissue factor (TF) is the major procoagulant. However, the relative contribution to fibrin deposition in the TME of tumor cell TF and host cell TF (eg, macrophage-derived) was not established. In addition, recent evidence has implicated TF in the regulation of the synthesis of the pro-angiogenic factor vascular endothelial growth factor (VEGF) by tumor cells. In the current study we used in situ techniques to determine the cellular localization of XLF, TF, VEGF, and an alternative tumor procoagulant, so-called cancer procoagulant (CP), a cysteine protease that activates clotting factor X. In lung cancer we have found XLF localized predominantly to the surface of tumor-associated macrophages, as well as to some endothelial cells and perivascular fibroblasts in the stromal area of the tumors co-distributed with TF at the interface of the tumor and host cells. Cancer pro-coagulant was localized to tumor cells in several cases but not in conjunction with the deposition of XLF. TF and VEGF were co-localized in both lung cancer and breast cancer cells by in situ hybridization and immunohistochemical staining. Furthermore, a strong relationship was found between the synthesis of TF and VEGF levels in human breast cancer cell lines (r2 = 0.84; P < 0.0001). Taken together, these data are consistent with a highly complex interaction between tumor cells, macrophages, and endothelial cells in the TME leading to fibrin formation and tumor angiogenesis.     

A discourse on the nature of dental hygiene knowledge and knowing

Abstract: Objective: Historically, dental hygiene has adopted theory and research from other health disciplines, without adequately modifying these concepts to reflect the unique dental hygiene practice context, leaving dental hygiene’s research and theory base underdeveloped. Dental hygiene has yet to articulate its epistemological assumptions – the nature, scope and object of dental hygiene knowledge – or to fully describe the patterns of knowing that are brought to practice. Methods: This paper uses a method of inquiry from philosophy to begin the discourse about dental hygiene ways of knowing. In nursing, Carper identified four fundamental patterns of knowing: empirics or the science of nursing; aesthetics or the art of nursing; personal knowledge and ethical or moral knowledge. These patterns were used to explore this concept within dental hygiene. Results: There is more to the nature of dental hygiene knowledge and knowing than rote application of technique‐related or research‐based information in practice, including judgements about when and how to use different types of information that are used. Currently, empirical forms of knowledge seem to be disproportionately valued, yet evidence was found for all of Carper’s four patterns of knowing. Conclusions: Carper’s work on patterns of knowing in nursing provided a useful framework to initiate the discourse on ways of knowing in dental hygiene. These results are submitted for others to challenge, refine and extend, for continuing the discussion. Dental hygiene leaders and scholars need to engage in discourse about extending the epistemological assumptions to reflect reality.     

Moving research knowledge into dental hygiene practice

Dental hygiene, as an emerging profession, needs to increase the number of intervention studies that identify improvements in oral health outcomes for clients. Historically, dental hygiene studies have typically been atheoretical, but the use of theoretical frameworks to guide these studies will increase their meaningfulness. Rogers' theory of diffusion of innovations has been used to study research utilization across many disciplines, and may offer insights to the study of research use in dental hygiene. Research use is an important component of evidence-based practice (EBP), and diffusion of research knowledge is an important process in implementing EBP. The purpose of this paper is to use diffusion of innovations theory to examine knowledge movement in dental hygiene, specifically through the example of the preventive practice of oral cancer screening by dental hygienists, considered as an innovation. Diffusion is considered to be the process by which an innovation moves through communication channels over time among a social network. We suggest diffusion theory holds promise for the study of knowledge movement in dental hygiene, but there are limitations including access to and understanding research studies as innovations. Nevertheless, using a theoretical framework such as Rogers' diffusion of innovations will strengthen the quality of intervention research in dental hygiene, and subsequently, health outcomes for clients.     

The extrinsic coagulation cascade and tissue factor pathway inhibitor in macrophages: A potential therapeutic opportunity for atherosclerotic thrombosis

Objectives

The coagulation protease cascade plays the central requisite role in initiation of arterial atherothrombosis. However, the relative participation of the extrinsic as compared to the intrinsic pathway is incompletely resolved. We have investigated in vivo the relative importance of the extrinsic and intrinsic pathways to define which is more essential to atherothrombosis and therefore the preferable prophylactic therapeutic target. We further addressed which type of plaque associated macrophage population is associated with the thrombotic propensity of atherosclerotic plaques.

Methods

Both photochemical injury and ferric chloride vascular injury models demonstrated arterial thrombosis formation in ApoE deficient mice. We found that direct interference with the extrinsic pathway, but not the intrinsic pathway, markedly diminished the rate of thrombus formation and occlusion of atherosclerotic carotid arteries following experimental challenge. To explore which plaque macrophage subtype may participate in plaque thrombosis in regard to expression tissue factor pathway inhibitor (TFPI), bone marrow derived macrophages of both M and GM phenotypes expressed tissue factor (TF), but the level of TFPI was much greater in M- type macrophages, which exhibited diminished thrombogenic activity, compared to type GM-macrophages.

Results and conclusions

Our works support the hypothesis that the TF-initiated and direct extrinsic pathway provides the more significant contribution to arterial plaque thrombogenesis. Activation of the TF driven extrinsic pathway can be influenced by differing colony-stimulating factor influenced macrophage TFPI-1 expression. These results advance our understanding of atherothrombosis and identify potential therapeutic targets associated with the extrinsic pathway and with macrophages populating arterial atherosclerotic plaques.     

The structural biology of expression and function of tissue factor.

Analysis of the structural biology of TF provides insights into the both the expression of the gene and the function of this cell surface receptor in the initiation of the coagulation protease cascades. The advance of information may permit inferential hypotheses for the structural biology of other cofactor regulated catalytic steps in blood coagulation.     

Isolation and characterization of a homogeneous isomeric species of carcinoembryonic antigen: cea-s.

A single homogeneous isomeric species of carcinoembryonic antigen was isolated by reference to solubility in 0.9 M perchloric acid, isoelectric focusing, molecular exclusion chromatography, ion exchange chromatography, passage through immuno-absorbants, and isopyknic density gradient ultracentrifugation. The final product, representing approximately 1.8% of the perchloric acid soluble glycoprotein of the tumor, is homogeneous and devoid of other proteins by polyacrylamide gel electrophoresis. This single species of carcinoembryonic antigen, CEA-S, has a sedimentation velocity of 6.6, a diffusion constant of 3.05 times 10-minus 7 cm-2/sec, a mean Stokes radius of 65 A, a density of 1.41 ml/g in cesium chloride and an estimated molecular weight of 181,000, and it is devoid of detectable A or B blood-group antigens. Immunochemical studies demonstrate qualitative similarities between CEA-S and conventional carcinoembryonic antigens; however, competitive inhibition analyses demonstrate significant quantitative immunochemical differences between CEA-S and preparations of carcinoembryonic antigen. These results are consistent with the concept that CEA-S is an immunochemical isomer of carcinoembryonic antigen.     

Ultramicro assay of anti-erythrocyte antibodies and erythrocyte antigens

Abstract. An ultramicro assay has been developed for the rapid qualitative and semi-quantitative characterization of anti-erythrocyte antibodies and antigens. Sensitivity is comparable to, or greater than, standard tube and microtiter assays; and the method requires as little as 1 μl of antibody and 2,000 red cells. Utilizing microliter quantities of eluted anti-erythrocyte auto-antibody, sub-populations of auto-antibodies, differing in antigenic specificity, can be identified and semi-quantitatively assayed.     

Targeting cell-impermeable prodrug activation to tumor microenvironment eradicates multiple drug-resistant neoplasms

The tumor microenvironment is notably enriched with a broad spectrum of proteases. The proteolytic specificities of peptide substrates provide modular chemical tools for the rational design of cell-impermeable prodrugs that are specifically activated by proteases extracellularly in the tumor microenvironment. Targeting cell-impermeable prodrug activation to tumor microenvironment will significantly reduce drug toxicity to normal tissues. The activated prodrug attacks both tumor and stroma cells through a "bystander effect" without selectively deleting target-producing cells, therefore further minimizing resistance and toxicity. Here, we showed that legumain, the only asparaginyl endopeptidase of the mammalian genome, is highly expressed by neoplastic, stromal, and endothelial cells in solid tumors. Legumain is present extracellularly in the tumor microenvironment, associated with matrix as well as cell surfaces and functional locally in the reduced pH of the tumor microenvironment. A novel legumain-activated, cell-impermeable doxorubicin prodrug LEG-3 was designed to be activated exclusively in the tumor microenvironment. Upon administration, there is a profound increase of the end-product doxorubicin in nuclei of cells in tumors but little in other tissues. This tumor microenvironment-activated prodrug completely arrested growth of a variety of neoplasms, including multidrug-resistant tumor in vivo and significantly extended survival without evidence of myelosuppression or cardiac toxicity. The tumor microenvironment-activated prodrug design can be extended to other proteases and chemotherapeutic compounds and provides new potentials for the rational development of more effective functionally targeted cancer therapeutics.     

Drug-Injecting Street Youth: A Comparison of HIV-Risk Injection Behaviors Between Needle Exchange Users and Nonusers

Injection drug use, the second most common risk factor associated with HIV infection in the United States after sexual transmission, is especially prevalent among street youth, many of whom routinely share their drug injection equipment. To prevent sharing behavior among street youth, a needle exchange program for youth was established in Hollywood, California. This study compared the drug use and needle-sharing behaviors of youth who were users of the needle exchange with those of youth who were not. Results indicate that while demographic characteristics and drug injection frequency were similar in the two groups, needle exchange users were significantly less likely to share needles, share other injection equipment, use other drugs to help them come down, use unsterile needles when high or craving drugs, and report difficult access to sterile needles. These findings suggest that needle exchange programs may reduce needle-sharing behavior among street youth.