We have shown previously that normal B cells share, with Epstein–Barr virus‐transformed and malignant B cells, the ability to activate the alternative pathway (AP) of complement in vitro, resulting ...in the deposition of C3 fragments on the cell surface. Complement receptor type 2 (CR2, CD21) has been implicated directly as the site for formation of an AP convertase, which provides nascent C3b for deposition at secondary sites on the B‐cell surface. In the present study, we have examined C3 fragment deposition in vitro in more detail by (1) assessing the importance of locally generated C3b for the deposition process, (2) investigating whether CR2 is the sole requirement for conferring AP activation capacity on a cell, and (3) determining whether CR2’s function, as an AP activator, has different structural requirements from ligand binding. Increasing the availability of native C3, by increasing the serum (NHS) concentration, resulted in enhanced C3 fragment deposition on the B cells, whereas use of factor I‐depleted NHS, which showed massive fluid phase C3 conversion during the incubation, diminished the deposition. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) and Western blotting of untreated and hydroxylamine‐treated lysates from B cells, after in vitro activation, revealed that the majority of C3 fragments (primarily iC3b and C3dg) had been covalently bound to the cell surface. Transfection of COS cells with wild‐type CR2 or a deletion mutant lacking 11 of the molecule’s 15 homologous domains, but retaining the ligand‐binding site, revealed that expression of intact CR2 conferred a 12‐fold increase in AP‐activating capacity on these cells, while no increase in AP activity was apparent on cells transfected with the mutant CR2.
Responding to demands that nursing leaders conduct business in creative, proactive ways, the authors of this department share the work of The Robert Wood Johnson Foundation's national program, ...Colleagues in Caring: Regional Collaboratives for Nursing Work Force Development. The purpose of this initiative is to enhance regional and state collaborative planning and implement actions and policies to address the rapid changes occurring in the United States nursing labor market. This department, edited by Mary Fry Rapson, PhD, RN, CS, National Program Director, and Rebecca B. Rice, EdD, RN, National Deputy Director, presents the ongoing work of the program, highlighting the work of the 20 individual collaboratives. Regional approaches to the expected program outcomes and specific challenges and opportunities that are unique to each region's environment are included. The Colleagues in Caring program is administered by the American Association of Colleges of Nursing. Current information on the Initiative can be found at http://www.aacn.edu/CaringProject/index.htm. The staff at the National Program Office can be reached at 202-496-1095 (fax 202-496-1093).
This article seeks to contribute to human becoming theory and to nursing by providing an international human becoming hermeneutic study of Thomas Hegg's A Cup of Christmas Tea. The human becoming ...hermeneutic method was used in this study to discover emergent meanings about human experiences. Guided by the method, the authors discovered three emergent meanings: honoring the cherished; communing with the was, is, and will be; and triumphing with new vision. These meanings were synthesized by the authors. A Cup of Christmas Tea is the story of the way triumphing with new vision arises with honoring the cherished in communing with the was, is, and will be. The conclusion for families and nurses is that by remaining open to all possibilities that exist in each now, moments of serendipitous togetherness can transform human trepidation and negative views of later life.
Contradictory reports regarding the ability of complement receptor type 2 (CR2,CD21) on normal B cells to activate complement (C′) via the alternative pathway (AP), prompted us to compare the ...performance of human peripheral blood B cells and the Epstein–Barr virus‐positive Burkitt's lymphoma cell line, Raji (a well characterized AP activator) by using flow cytometry. Measured in terms of the membrane deposition of C3 fragments per cell, Raji cells were significantly (6‐ to 26‐fold) more effective as complement activators than were normal B cells. Raji cells were also found to express approximately four to five times as many CR2 as normal B cells. In addition, they distinguished themselves by displaying a greater Ca2+‐dependent activation, with pooled normal human sera (NHS) as the complement source, and by degrading unprotected C3b fragments from iC3b to C3dg/C3d at a significantly lower rate than the B cells. The Ca2+ dependency of Raji cell activation was found to be partially a result of classical pathway (CP) triggering by specific antibodies in the NHS, although other triggering mechanisms may also be involved. If the influence of these variations between Raji cells and normal B cells was excluded, by relating deposition of anti‐C3d‐reactive fragments, during AP activation, to the number of CR2 expressed, the difference in performance between the two cell types was found to be insignificant.
Performance of the ring imaging Cherenkov detector of DELPHI Adam, W.; Albrecht, E.; Allen, D. ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
12/1995, Letnik:
367, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The general purpose particle detector DELPHI at the Large Electron Positron collider at CERN was built to give the complete information of each event. DELPHI uses ring imaging Cherenkov counters to ...provide hadron identification in most of the momentum range below 45 GeV/
c and over almost the full solid angle. Charged particles traversing gaseous and liquid fluorocarbon radiators create photons used for Cherenkov angle reconstruction. Some of the design features of the detector will be presented, with emphasis on the experience which was gained in the operation of these large systems. The hadron identification power of the ring imaging Cherenkov detector closely meets the main design values. Data processing and performance of the detector will be discussed using dimuon events collected during 1994. Pion rejection factors for kaon tagging will be shown.
One quarter of the Forward Ring Imaging Cherenkov (Forward RICH) detector has been installed and operated in the DELPHI experiment. The detector covers the forward-backward regions (15 degrees < ...theta <35 degrees ). Two radiator systems are used for particle identification in the momentum range up to 40 GeV/c, i.e., a liquid perfluorohexane and perfluorobutane gas. UV-photons with wavelengths from approximately 170 nm to approximately 200 nm (7.3-6.2 eV) are detected with high efficiency. The total active area of the photon detector is approximately 8 m/sup 2/.< >
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