Dual Engagement Research Articles

Commentary: Ways of asking and ways of living: reflections on the 50th anniversary of Morris' ever-useful Uses of Epidemiology

To be of use. To Jeremy Morris (b. 1910), writing a half-century ago in his now classic text, Uses of Epidemiology, the promise—and responsibility—of epidemiology was clear: to generate scientific knowledge about the ‘presence, nature and distribution of health and disease among the population’ (p. 96), ultimately in order to ‘abolish the clinical picture’(p. 98). Committed to improving the ‘health of the community’ (p. 96),Morris argued that ‘one of the most urgent social needs of the day’ that epidemiology could address was ‘identifying harmful ways of living’ and ‘rules of healthy living’ (p. 98). Uniquely equipping epidemiology to carry out this task was, in his view, its population and historical perspective and its dual engagement with studying ‘human biology’ and ‘the social aspects of health and disease’ (p. 97). Viewing epidemiology as a necessary complement to what he deemed equally vital clinical and laboratory research (p. 99), Morris affirmed that the discipline’s distinct uses ‘all stem from the fact that in epidemiology the group is studied and not merely particular individuals or cases in the group’ (p. 97). How might epidemiologists enhance their capacity to do useful research? Morris’ answer: by use of better methods. Only the sort of methods Morris had in mind were not the kinds of technical methods emphasized by the ‘modern epidemiology’ of recent years, as necessary as he knew them to be. Rather, Morris’ objective was to articulate a methodical approach for epidemiological thinking:

Class Switch Recombination and Somatic Hypermutation in Early Mouse B Cells Are Mediated by B Cell and Toll-like Receptors

Activation-induced cytidine deaminase (AID) is required for immunoglobulin (Ig) gene class switch recombination (CSR), somatic hypermutation (SHM), and somatic hyperconversion. In general, high AID expression is found in mature B cells that are responding to antigens. However, AID expression and SHM have also been detected in developing B cells from transgenic mice that have a limited Ig repertoire. Here we demonstrate that AID expression, ongoing CSR, and active SHM occur in developing B cells from wild-type mice. Further, our results suggest that somatic variants arising from developing B cells in the bone marrow further diversify in the spleen of unimmunized mice. AID expression in developing B cells is T cell independent but involves engagement of B cell receptors and Toll-like receptors. Early AID expression can increase the preimmune repertoire of developing B cells, may provide an innate population of IgG- and IgA-expressing cells, and could be involved in receptor editing of self-reactive immature B cells.

From Receptor to Ras Through Phosphatidic Acid

Phospholipase D (PLD) catalyzes the production of phosphatidic acid (PA) from phosphatidylcholine. Proteins with specific motifs recognize PA and may be recruited to the site of its production. In addition, PA may be further hydrolyzed to produce diacylglycerol (DAG), another lipid to which proteins may interact. Two reports find that PLD and PA are involved in the activation of Ras at the plasma membrane (see Hancock for discussion). Although SOS (son of sevenless), the protein that activates Ras in response to receptor tyrosine kinase activation, binds to the receptor-associated Grb2, this interaction is not required for recruitment of SOS to the membrane. Instead, Zhao et al . found that the pleckstrin homology (PH) domain of SOS bound specifically to PA with high affinity in vitro. Disruption of this interaction and the interaction with Grb2 in the same SOS construct (Sos ΔCHR/EE ) eliminated the recruitment of the transfected SOS to the membrane in response to the addition of PA or serum (to stimulate receptor tyrosine kinases). Furthermore, in response to epidermal growth factor (EGF), Ras activation occurred in cells expressing the Grb2-binding mutant Sos ΔC but did not occur if both the Grb2 and PA interactions were abolished. When PLD2, which interacts with EGF receptor-Grb2 complexes, was knocked down by RNA interference techniques, EGF-stimulated activation of Ras was blocked. Thus, Zhao et al . suggest that the interaction of SOS with PLD-produced PA is the critical step in recruiting SOS to the membrane to activate Ras and that Grb2 serves to recruit PLD2 to the activated receptors. Activation of the T cell receptor (TCR) alone or with its co-receptor activates Ras only at the Golgi, and this Ras activation involves the DAG- and calcium-regulated guanine nucleotide releasing protein RasGRP1. Mor et al . show that coactivation of the TCR and the integrin LFA-1 (lymphocyte function-associated antigen-1, also known as αLβ2) results in activation of Ras at the plasma membrane and Golgi and implicate PLD2 in the plasma membrane response. Live-cell imaging was performed with Jurkat T cells expressing green fluorescent protein (GFP)-tagged probes for activated Ras or DAG along with tagged versions of the three isoforms of Ras (N- and H-Ras, which cycle between the Golgi and plasma membrane, and K-Ras, which is recruited only to the plasma membrane). Only when both the TCR and LFA-1 were engaged was Ras activated at the plasma membrane. Endogenous K-Ras was only activated when both the TCR and LFA-1 were engaged. Cells deficient in phospholipase Cγ1 blocked Ras activation at the Golgi but did not inhibit Ras activation at the plasma membrane in response to dual TCR and LFA-1 engagement. In contrast, inhibition of PLD with low concentrations of n -butanol blocked recruitment of RasGRP1 to the plasma membrane and Ras activation at the plasma membrane; higher concentrations of n -butanol blocked Ras activation at the Golgi as well. Inhibition of phosphatidic acid phosphatase (PAP), which is the enzyme responsible for producing DAG from PA, also blocked Ras activation at the plasma membrane. A DAG fluorescent reporter showed that DAG concentrations increased at the plasma membrane in response to TCR and LFA-1 engagement. These results suggest that PLD may shape the pattern of the T cell response. C. Zhao, G. Du, K. Skowronek, M. A. Frohman, D. Bar-Sagi, Phospholipase D2-generated phosphatidic acid couples EGFR stimulation to Ras activation by Sos. Nat. Cell Biol. 9 , 706-712 (2007). [PubMed] A. Mor, G. Campi, G. Du, Y. Zheng, D. A. Foster, M. L. Dustin, M. R. Philips, The lymphocyte function-associated antigen-1 receptor costimulates plasma membrane Ras via phospholipase D2. Nat. Cell Biol. 9 , 713 -719 (2007). [PubMed] J. F. Hancock, PA promoted to manager. Nat. Cell Biol. 9 , 615 -617 (2007). [PubMed]

A Theory of Tailorable Technology Design

Tailorable technologies are a class of information systems designed with the intention that users modify and redesign the technology in the context of use. Tailorable technologies support user goals, intentions, metaphor, and use patterns in the selection and integration of technology functions in the creation of new and unique information systems. We propose a theory of tailorable technology design and identify principles necessary for the initial design. Following a Kantian style of inquiry, we identified four definitional characteristics of tailorable technology: a dual design perspective, user engagement, recognizable environments, and component architectures. From these characteristics, we propose nine design principles that will support the phenomenon of tailoring. Through a year-long case study, we refined and evidenced the principles, finding found that designers of tailorable technologies build environments in which users can both interact and engage with the technology, supporting the proposed design principles. The findings highlight a distinction between a reflective environment, where users recognize and imagine uses for the technology, and an active environment in which users tailor the technology in accordance with the imagined uses. This research contributes to the clarification of the role of theory in design science, expands the concept of "possibilities for action" to IS design, and proposes a design theory of a class of information systems for testing and refinement.

Photographs and accountability: cracking the codes of an NGO

PurposeThe purpose of this paper is to formulate an analytical model for interpreting photographs in accountability statements from Barthes' celebrated theoretical work on photography, La chambre claire; to offer a study of the communication of accountability by an NGO through the first detailed analysis, within accountability literature, of one photograph.Design/methodology/approachThe study establishes a conceptual framework for examining photography based on La chambre claire's contrast of rational codes (Studium) with intuitive elements (Punctum). An application of the framework is provided in considering the heterogeneity and accountability of NGOs through an examination of the Oxfam Annual Review 2003/2004 front cover photograph.FindingsThe framework is enlightening: the photograph's Studium reflects the complexity of Oxfam's dual engagement in the corporate and charitable sectors, and the developed and developing worlds; its Punctum arouses sentiment and compassion.Research limitations/implicationsThe study provides a model which may be applied to the wealth of photographs produced by contemporary organizations; the framework encompasses promotional images as well as photographic art, and is well suited to figurative photography. It is limited regarding photographs of a hybrid or abstract nature.Practical implicationsThe analysis is of interest to accounting researchers, practitioners, trainees, auditors and any user of accounting and accountability statements. It illuminates the way in which photographs highlight, complement and supplement information more traditionally communicated in numbers and words.Originality/valueThe paper adds to research into NGOs; augments theoretical work on photographs in accountability literature; and expands the empirical literature on the interpretation of photographs in accounting and accountability statements.

Exogenous and Endogenous TLR Ligands Activate Anti-Chromatin and Polyreactive B Cells

Autoreactive B cells may become activated in a T-independent manner via synergistic engagement of the BCR and TLRs. Using the VH3H9 Ig H chain transgene to track anti-chromatin B cells, we demonstrate that VH3H9/Vlambda1 anti-chromatin B cells proliferate in response to stimulatory oligodeoxynucleotides containing CpG motifs, suggesting that these autoreactive B cells are responsive to TLR9 signaling. Strikingly, some VH3H9 B cells, but not the well-characterized VH3H9/Vlambda1 B cells, proliferate spontaneously in culture medium. This proliferation is blocked by inhibitory CpG oligodeoxynucleotides, implicating the TLR9 (or possibly TLR7) pathway. Most hybridomas generated from the proliferating cells are polyreactive, and one exhibits binding to nuclear Ags but not to the other Ags tested. Thus, B cells carrying autoreactive and/or polyreactive specificities may be susceptible to T cell-independent activation via dual engagement of the BCR and TLRs.

The NAC's Organizational Practices and the Politics of Assisted Reproductive Technologies in Canada

As the formal carriers of the goals and agendas of social movements, social move ment organizations (SMOs) are committed to both institutional and identity politics. Given this dual engagement, SMOs must attempt to reconcile their intraorganizational strategies for rep resentation and mobilization with their intergroup strategies for instrumental action in the pol icy process. In this article, these tensions are explored in a case study of the National Action Committee on the Status of Women (NAC) and its involvement in the policy debate on repro ductive technologies over 15 years. The article reveals how the NAC's capacity to influence and participate in the formulation of policy on reproductive technologies was challenged by its inabil ity to resolve competing demands: those of institutional politics, which called for professional advocacy; and the internal demands emanating from its grassroots member groups, for deliber ation and participation. The article also attributes the NAC's diminished effectiveness in the policy process to broader changes in the relations between the Canadian state and social move

Dual Engagement Regulation of Protein Interactions with the AP-2 Adaptor α Appendage

Clathrin-mediated endocytosis depends upon the coordinated assembly of a large number of discrete clathrin coat components to couple cargo selection with rapid internalization from the cell surface. Accordingly, the heterotetrameric AP-2 adaptor complex binds not only to clathrin and select cargo molecules, but also to an extensive family of endocytic accessory factors and alternate sorting adaptors. Physical associations between accessory proteins and AP-2 occur primarily through DP(F/W) or FXDXF motifs, which engage an interaction surface positioned on the C-terminal platform subdomain of the independently folded alpha subunit appendage. Here, we find that the WXX(F/W)X(D/E) interaction motif found in several endocytic proteins, including synaptojanin 1, stonin 2, AAK1, GAK, and NECAP1, binds a second interaction site on the bilobal alpha appendage, located on the N-terminal beta sandwich subdomain. Both alpha appendage binding sites can be engaged synchronously, and our data reveal that varied assemblies of interaction motifs with different affinities for two sites upon the alpha appendage can provide a mechanism for temporal ordering of endocytic accessory proteins during clathrin-mediated endocytosis.

Toll-like receptor 9-dependent and -independent dendritic cell activation by chromatin-immunoglobulin G complexes.

Dendritic cell (DC) activation by nucleic acid–containing immunoglobulin (Ig)G complexes has been implicated in systemic lupus erythematosus (SLE) pathogenesis. However, the mechanisms responsible for activation and subsequent disease induction are not completely understood. Here we show that murine DCs are much more effectively activated by immune complexes that contain IgG bound to chromatin than by immune complexes that contain foreign protein. Activation by these chromatin immune complexes occurs by two distinct pathways. One pathway involves dual engagement of the Fc receptor FcγRIII and Toll-like receptor (TLR)9, whereas the other is TLR9 independent. Furthermore, there is a characteristic cytokine profile elicited by the chromatin immune complexes that distinguishes this response from that of conventional TLR ligands, notably the induction of BAFF and the lack of induction of interleukin 12. The data establish a critical role for self-antigen in DC activation and explain how the innate immune system might drive the adaptive immune response in SLE.

Multivalent Mechanism of Membrane Insertion by the FYVE Domain

Targeting of a wide variety of proteins to membranes involves specific recognition of phospholipid head groups and insertion into lipid bilayers. For example, proteins that contain FYVE domains are recruited to endosomes through interaction with phosphatidylinositol 3-phosphate (PtdIns(3)P). However, the structural mechanism of membrane docking and insertion by this domain remains unclear. Here, the depth and angle of micelle insertion and the lipid binding properties of the FYVE domain of early endosome antigen 1 are estimated by NMR spectroscopy. Spin label probes incorporated into micelles identify a hydrophobic protuberance that inserts into the micelle core and is surrounded by interfacially active polar residues. A novel proxyl PtdIns(3)P derivative is developed to map the position of the phosphoinositide acyl chains, which are found to align with the membrane insertion element. Dual engagement of the FYVE domain with PtdIns(3)P and dodecylphosphocholine micelles yields a 6-fold enhancement of affinity. The additional interaction of phosphatidylserine with a conserved basic site of the protein further amplifies the micelle binding affinity and dramatically alters the angle of insertion. Thus, the FYVE domain is targeted to endosomes through the synergistic action of stereospecific PtdIns(3)P head group ligation, hydrophobic insertion and electrostatic interactions with acidic phospholipids.

Toll is a Coreceptor

Autoimmune diseases result from inappropriate activation of B cells by self-antigens. One of these antigens is chromatin, which is recognized by imunnoglobulin G2a (IgG2a). Leadbetter et al. studied B cell proliferation in cells from a mouse model for rheumatoid arthritis and systemic lupus erythematosus. The stimulation of proliferation of these B cells by DNA antigens required the B cell receptor and the Toll-receptor adapter MyD88. In the presence of agents that impair lysosome and endosome acidification, the cellular response to the Toll receptor TLR9 is impaired. The B cells failed to respond to DNA antigens in the presence of chloroquine, an agent that impairs acidification, thus implicating the TLR9 receptor in the activation of B cells by DNA-based autoantigens. The implications of these results for autoimmune disease are discussed by Vinuesa and Goodnow. E. A. Leadbetter, I. R. Rifkin, A. M. Hohlbaum, B. C. Beaudette, M. J. Schlomchik, A. Marshak-Rothstein, Chromatin-IgG complexes activate B cells by dual engagement of IgM and Toll-like receptors. Nature 416 , 603-607 (2002). [Online Journal] C. G. Vinuesa, C. C. Goodnow, DNA drives autoimmunity. Nature 416 , 595-598 (2002). [Online Journal]

Chromatin-IgG complexes activate B cells by dual engagement of IgM and Toll-like receptors.

Autoreactive B cells are present in the lymphoid tissues of healthy individuals, but typically remain quiescent. When this homeostasis is perturbed, the formation of self-reactive antibodies can have serious pathological consequences. B cells expressing an antigen receptor specific for self-immunoglobulin-gamma (IgG) make a class of autoantibodies known as rheumatoid factor (RF). Here we show that effective activation of RF+ B cells is mediated by IgG2a-chromatin immune complexes and requires the synergistic engagement of the antigen receptor and a member of the MyD88-dependent Toll-like receptor (TLR) family. Inhibitor studies implicate TLR9. These data establish a critical link between the innate and adaptive immune systems in the development of systemic autoimmune disease and explain the preponderance of autoantibodies reactive with nucleic acid-protein particles. The unique features of this dual-engagement pathway should facilitate the development of therapies that specifically target autoreactive B cells.

Dual engagement: France and the Persian Gulf

With the end of the Cold War international relations began anew without the bipolar constraints of two ideologically opposed superpowers. The Iraqi invasion of Kuwait on 2 August 1990 represented the first challenge to the nascent post‐Cold War Persian Gulf security environment. Within the region, France is once again increasingly active in the economic, political and military fields. The re‐evaluation of Washington's ability to remain engaged at its current levels within the Gulf may be attributed in large part to a growing sensitivity in Riyadh and other Arab capitals to the visible US presence coupled with an American foreign policy which is, at times, inconsistent. The net future effect of contemporary trends may be one in which the Gulf Sheikhdoms welcome French ascendancy and US decline. France has experienced its own foreign policy transformation marked by the leadership of President Chirac. Where President Mitterrand sought the role of power broker in regional affairs, President Chirac seeks increased influence and importance.

Co-ligation of surface IgM and CD40 on naive B lymphocytes generates a blast population with an ambiguous extrafollicular/germinal centre cell phenotype.

We have previously shown that dual occupancy of sigM and CD40 - essential receptors in T-dependent B cell responses - by antibodies held on CD32-L cells results in the rapid proliferation of resting human B lymphocytes in a cytokine-independent manner. Here we report the detailed phenotype of the blast population emerging in such cultures. By 3 days the levels of CD19 and CD20 have increased 4- and 2-fold respectively: such high level expression of these two pan-B markers is characteristic of cells of germinal centre (GC) origin. B cells co-stimulated via sIgM and CD40 express low level CD23 and almost half become CD5(+); they also acquire CD38 and - importantly - CD77, both of these being selective markers of GC B cells. Expression of sigM and IgD is down-regulated on these cells and a minor, but significant, population of IgG+ cells appears. In marked contrast to GC B cells, the population proliferating in response to dual occupancy of sigM and CD40 has up-regulated and strongly expresses CD44. Morphologically, the cells are heterogeneous but there is a dominant blastic cell type with relatively scanty cytoplasm and having multiple nucleoli, both of which are characteristic of centroblasts; nevertheless, these cells remain morphologically distinct from freshly isolated GC B cells and do not show hallmark features of centrocytes. Although there is substantial cell death occurring by days 6-7 in these cultures, there is no morphological evidence for apoptosis. Thus, the proliferating population that emerges from the dual engagement of antigen receptor and CD40 on resting B cells appears to be bestowed with some features of GC B cells but has others which are incompatible with that particular stage of differentiation. The possibility that it might represent (i) a blast stage that is transitional between activation in T zones and entry into the follicle or (ii) a precursor population that colonizes the primary follicle prior to GC formation is discussed.

CD82, tetra-span-transmembrane protein, is a regulated transducing molecule on U937 monocytic cell line.

The mononuclear cell surface protein IA4, recently classified as CD82, was originally identified in our laboratory by the IA4 monoclonal antibody (mAb), because of its high expression on three lymphoblastoid, LAK-susceptible, variant cell lines. We have characterized CD82 as a new activation/differentiation marker of mononuclear cells. This protein belongs to the new family of TST proteins (tetra spans transmembrane), which includes CD9, CD37, CD53, CD63, and CD81 (TAPA-1). Here we demonstrate that cross-linking of IA4 mAbs induces an increase of intracellular free calcium in U937 cells and tyrosine phosphorylation of various proteins. Our data indicate that the intracellular calcium increase is initiated by a phospholipase C (PLC)-induced PtdIns(1,4,5)P3 second messenger followed by a more stable change, linked to extracellular calcium entry. This transducing signal was dependent on dual engagement of both CD82 and Fc receptors. Surface cross-linking of CD82 together with Fc receptors (FcRs) induces a specific long-lasting increase of intracellular calcium, whereas FcR cross-linking alone induces only a transient calcium mobilization. These results suggest that, upon cross-linking of CD82, a multimolecular complex including CD82 and FcR could be induced that is able to trigger signal transduction. We have previously shown that CD82 membrane expression is up-regulated during differentiation of human monocytes. Using U937 cells, we demonstrate here that several cytokines [interleukin-1 beta (IL-1 beta), IL-4, IL-6, IL-13, interferon-gamma, tumor necrosis factor alpha] could significantly up-regulate the surface expression of CD82 antigen, by contrast with FcR surface expression, which was up-regulated only after IFN-gamma treatments. Based on our finding of a strict dependence of CD82 activation on FcR stimulation, we suggest a putative role of CD82 in enhancing FcR-mediated activation of cells from the monocyte/macrophage lineage.