bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulation of the F-actin cytoskeleton by c-Abl tyrosine kinase in cell spreading and neurite extension
Authors: Woodring Pamela J. , Litwack E. David , O'Leary Dennis D.M. , Lucero Ginger R. , Wang Jean Y.J. , Hunter Tony
Published: July 2002

The nonreceptor tyrosine kinase encoded by the c-Abl gene has the unique feature of an F-actin binding domain (FABD). Purified c-Abl tyrosine kinase is inhibited by F-actin, and this inhibition can be relieved through mutation of its FABD. The c-Abl kinase is activated by physiological signals that also regulate the actin cytoskeleton. We show here that c-Abl stimulated the formation of actin microspikes in fibroblasts spreading on fibronectin. This function of c-Abl is dependent on kinase activity and is not shared by c-Src tyrosine kinase. The Abl-dependent F-actin microspikes occurred under conditions where the Rho-family GTPases were inhibited. The FABD-mutated c-Abl, which is active in detached fibroblasts, stimulated F-actin microspikes independent of cell attachment. Moreover, FABD-mutated c-Abl stimulated the formation of F-actin branches in neurites of rat embryonic cortical neurons. The reciprocal regulation between F-actin and the c-Abl tyrosine kinase may provide a self-limiting mechanism in the control of actin cytoskeleton dynamics.
Mice Genetically Hyporesponsive to Lipopolysaccharide (LPS) Exhibit a Defect in Endocytic Uptake of LPS and Ceramide
Authors: Thiéblemont Nathalie , Wright Samuel D.
Published: July 2002

We have recently shown that monomeric bacterial LPS is rapidly delivered from the plasma membrane to an intracellular site and that agents that block vesicular transport block responses of neutrophils to lipopolysaccharide (LPS) (Detmers, P.A., N. Thiéblemont, T. Vasselon, R. Pironkova, D.S. Miller, and S.D. Wright. 1996. J. Immunol. 157:5589–5596). To examine further the connection between intracellular transport of LPS and signaling, we observed internalization of fluorescently labeled LPS in cells from LPS-hyporesponsive (Lpsd) mice. Binding of fluorescent LPS from LPS–soluble CD14 (sCD14) complexes by peritoneal macrophages from Lpsd and control (Lpsn) mice was quantitatively similar, and confocal images obtained from these cells exhibited an identical appearance immediately after labeling. Incubation of labeled Lpsn macrophages at 37°C caused movement of the fluorescence from the cell perimeter in one or two spots in the perinuclear region. However, in Lpsd cells the fluorescence remained dispersed, suggesting a defect in vesicular transport. LPS resembles ceramide, and Lpsd mice fail to respond to ceramide. As with LPS, we found that binding of fluorescent ceramide by Lpsd and Lpsn macrophages was quantitatively similar, and the label moved rapidly to one to two spots in the perinuclear region in Lpsn mice. However, in Lpsd macrophages the fluorescence remained dispersed. These results show that cells deficient in responses to LPS exhibit defective vesicular transport of LPS and ceramide and point to a role for vesicular transport in responses to these mediators.
Interleukin (IL)-6 Directs the Differentiation of IL-4–producing CD4+ T Cells
Authors: Rincón Mercedes , Anguita Juan , Nakamura Tetsuo , Fikrig Erol , Flavell Richard A.
Published: July 2002

Interleukin (IL)-4 is the most potent factor that causes naive CD4+ T cells to differentiate to the T helper cell (Th) 2 phenotype, while IL-12 and interferon γ trigger the differentiation of Th1 cells. However, the source of the initial polarizing IL-4 remains unclear. Here, we show that IL-6, probably secreted by antigen-presenting cells, is able to polarize naive CD4+ T cells to effector Th2 cells by inducing the initial production of IL-4 in CD4+ T cells. These results show that the nature of the cytokine (IL-12 or IL-6), which is produced by antigen-presenting cells in response to a particular pathogen, is a key factor in determining the nature of the immune response.
Interferon γ Gene Expression in Sensory Neurons: Evidence for Autocrine Gene Regulation
Authors: Neumann Harald , Schmidt Hannes , Wilharm Elke , Behrens Lüder , Wekerle Hartmut
Published: July 2002

We explored expression and possible function of interferon-γ (IFN-γ) in cultured fetal (E15) rat dorsal root ganglion neurons combining whole cell patch-clamp electrophysiology with single cell reverse transcriptase polymerase chain reaction and confocal laser immunocytochemistry. Morphologically, we located IFN-γ protein in the cytoplasm of the neurons in culture as well as in situ during peri- and postnatal development. Transcripts for classic IFN-γ and for its receptor were determined in probes of cytoplasm sampled from individual cultured neurons, which had been identified by patch clamp electrophysiology. In addition, the cultured neurons expressed both chains of the IFN-γ receptor.

Locally produced IFN-γ acts back on its cellular source. Phosphorylation and nuclear translocation of the IFN-inducible transcriptional factor STAT1 as well as IFN-γ–dependent expression of major histocompatibility complex class I molecules on the neuronal membrane were noted in untreated cultures. However, both processes were substantially blocked in the presence of antibodies neutralizing IFN-γ. Our findings indicate a role of IFN-γ in autocrine regulation of sensory neurons.
Requirements for Both Rac1 and Cdc42 in Membrane Ruffling and Phagocytosis in Leukocytes
Authors: Cox Dianne , Chang Peter , Zhang Qing , Reddy P. Gopal , Bokoch Gary M. , Greenberg Steven
Published: July 2002

Specific pathways linking heterotrimeric G proteins and Fcγ receptors to the actin-based cytoskeleton are poorly understood. To test a requirement for Rho family members in cytoskeletal events mediated by structurally diverse receptors in leukocytes, we transfected the full-length human chemotactic peptide receptor in RAW 264.7 cells and examined cytoskeletal alterations in response to the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP), colony stimulating factor–1 (CSF-1), IgG-coated particles, and phorbol 12-myristate 13-acetate (PMA). Expression of Rac1 N17, Cdc42 N17, or the GAP domain of n-chimaerin inhibited cytoskeletal responses to FMLP and CSF-1, and blocked phagocytosis. Accumulation of F-actin– rich “phagocytic cups” was partially inhibited by expression of Rac1 N17 or Cdc42 N17. In contrast, PMA-induced ruffling was not inhibited by expression of Rac1 N17, but was blocked by expression of Cdc42 N17, indicating that cytoskeletal inhibition by these constructs was nonoverlapping. These results demonstrate differential requirements for Rho family GTPases in leukocyte motility, and indicate that both Rac1 and Cdc42 are required for Fcγ receptor– mediated phagocytosis and for membrane ruffling mediated by structurally distinct receptors in macrophages.
Flexible Programs of Chemokine Receptor Expression on Human Polarized T Helper 1 and 2 Lymphocytes
Authors: Sallusto Federica , Lenig Danielle , Mackay Charles R. , Lanzavecchia Antonio
Published: July 2002

Chemokines and their receptors are important elements for the selective attraction of various subsets of leukocytes. To better understand the selective migration of functional subsets of T cells, chemokine receptor expression was analyzed using monoclonal antibodies, RNase protection assays, and the response to distinct chemokines. Naive T cells expressed only CXC chemokine receptor (CXCR)4, whereas the majority of memory/activated T cells expressed CXCR3, and a small proportion expressed CC chemokine receptor (CCR)3 and CCR5. When polarized T cell lines were analyzed, CXCR3 was found to be expressed at high levels on T helper cell (Th)0s and Th1s and at low levels on Th2s. In contrast, CCR3 and CCR4 were found on Th2s. This was confirmed by functional responses: only Th2s responded with an increase in [Ca2+]i to the CCR3 and CCR4 agonists eotaxin and thymus and activation regulated chemokine (TARC), whereas only Th0s and Th1s responded to low concentrations of the CXCR3 agonists IFN-γ–inducible protein 10 (IP-10) and monokine induced by IFN-γ (Mig). Although CCR5 was expressed on both Th1 and Th2 lines, it was absent in several Th2 clones and its expression was markedly influenced by interleukin 2. Chemokine receptor expression and association with Th1 and Th2 phenotypes was affected by other cytokines present during polarization. Transforming growth factor β inhibited CCR3, but enhanced CCR4 and CCR7 expression, whereas interferon α inhibited CCR3 but upregulated CXCR3 and CCR1. These results demonstrate that chemokine receptors are markers of naive and polarized T cell subsets and suggest that flexible programs of chemokine receptor gene expression may control tissue-specific migration of effector T cells.
Binding of Complement Factor H to Loop 5 of Porin Protein 1A: A Molecular Mechanism of Serum Resistance of Nonsialylated Neisseria gonorrhoeae
Authors: Ram Sanjay , McQuillen Daniel P. , Gulati Sunita , Elkins Christopher , Pangburn Michael K. , Rice Peter A.
Published: July 2002

Neisseria gonorrhoeae isolated from patients with disseminated infection are often of the porin (Por1A) serotype and resist killing by nonimmune normal human serum. The molecular basis of this resistance (termed stable serum resistance) in these strains has not been fully defined but is not related to sialylation of lipooligosaccharide. Here we demonstrate that Por1A bearing gonococcal strains bind more factor H, a critical downregulator of the alternative complement pathway, than their Por1B counterparts. This results in a sevenfold reduction in C3b, which is >75% converted to iC3b. Factor H binding to isogenic gonococcal strains that differed only in their porin serotype, confirmed that Por1A was the acceptor molecule for factor H. We identified a surface exposed region on the Por1A molecule that served as the binding site for factor H. We used gonococcal strains with hybrid Por1A/B molecules that differed in their surface exposed domains to localize the factor H binding site to loop 5 of Por1A. This was confirmed by inhibition of factor H binding using synthetic peptides corresponding to the putative exposed regions of the porin loops. The addition of Por1A loop 5 peptide in a serum bactericidal assay, which inhibited binding of factor H to the bacterial surface, permitted 50% killing of an otherwise completely serum resistant gonococcal strain. Collectively, these data provide a molecular basis to explain serum resistance of Por1A strains of N. gonorrhoeae.
Qa-1b Binds Conserved Class I Leader Peptides Derived from Several Mammalian Species
Authors: Kurepa Zoran , Hasemann Charles A. , Forman James
Published: July 2002

Qa-1b binds a peptide (AMAPRTLLL), referred to as Qdm (for Qa-1 determinant modifier), derived from the signal sequence of murine class Ia molecules. This peptide binds with high affinity and accounts for almost all of the peptides associated with this molecule. Human histocompatibility leukocyte antigen (HLA)-E, a homologue of Qa-1b, binds similar peptides derived from human class Ia molecules and interacts with CD94/NKG2 receptors on natural killer cells. We used surface plasmon resonance to determine the ability of Qa-1b to bind related ligands representing peptides derived from the leaders of class I molecules from several mammalian species. All of the peptides reported to bind HLA-E bound readily to Qa-1b. In addition, peptides derived from leader segments of different mammals also bound to Qa-1b, indicating a conservation of this “Qdm-like” epitope throughout mammalian evolution. We have attempted to define a minimal peptide on a polyglycine backbone that binds Qa-1b. Our previous findings showed that P2 and P9 are important but not sufficient for binding to Qa-1b. Although a minimum peptide (GMGGGGLLL) bound Qa-1b, its interaction was relatively weak, as were peptides sharing five or six residues with Qdm, indicating that multiple native residues are required for a strong interaction. This finding is consistent with the observation that this molecule preferentially binds this single ligand.
Peripheral Autoantigen Induces Regulatory T Cells that Prevent Autoimmunity
Authors: Seddon Benedict , Mason Don
Published: July 2002

Previous studies have shown that autoimmune thyroiditis can be induced in normal laboratory rats after thymectomy and split dose γ-irradiation. Development of disease can be prevented by reconstitution of PVG rats shortly after their final irradiation with either peripheral CD4+CD45RC− T cells or CD4+CD8− thymocytes from syngeneic donors. Although the activity of both populations is known to depend on the activities of endogenously produced interleukin 4 and transforming growth factor β, implying a common mechanism, the issue of antigen specificity of the cells involved has not yet been addressed. In this study, we show that the regulatory T cells that prevent autoimmune thyroiditis are generated in vivo only when the relevant autoantigen is also present. Peripheral CD4+ T cells, from rats whose thyroids were ablated in utero by treatment with 131I, were unable to prevent disease development upon adoptive transfer into thymectomized and irradiated recipients. This regulatory deficit is specific for thyroid autoimmunity, since CD4+ T cells from 131I-treated PVG.RT1u rats were as effective as those from normal donors at preventing diabetes in thymectomized and irradiated PVG.RT1u rats. Significantly, in contrast to the peripheral CD4+ T cells, CD4+CD8− thymocytes from 131I-treated PVG donors were still able to prevent thyroiditis upon adoptive transfer. Taken together, these data indicate that it is the peripheral autoantigen itself that stimulates the generation of the appropriate regulatory cells from thymic emigrant precursors.
Dynamic Interactions of Macrophages with T Cells during Antigen Presentation
Authors: Underhill David M. , Bassetti Michael , Rudensky Alexander , Aderem Alan
Published: July 2002

We have established a method for real-time video analysis of the interaction of antigen-presenting cells (APCs) with T cells. Green fluorescent protein expression controlled by a nuclear factor of activated T cells (NFAT)-responsive promoter permits the visualization of productive antigen presentation in single T cells. The readout is rapid (within 2 h) and semiquantitative and allows analysis by video microscopy and flow cytometry. Using this approach, we demonstrate that macrophages have the capacity to simultaneously activate multiple T cells. In addition, the interaction of T cells with macrophages is extraordinarily dynamic: after initial stable contact, the T cells migrate continuously on the surface of the macrophage and from APC to APC during productive antigen presentation. Thus, T cells sum up signals from multiple interactions with macrophages during stimulation.
Vascular Endothelial Growth Factor Can Substitute for Macrophage Colony-Stimulating Factor in the Support of Osteoclastic Bone Resorption
Authors: Niida Shumpei , Kaku Masato , Amano Hitoshi , Yoshida Hisahiro , Kataoka Hiroshi , Nishikawa Satomi , Tanne Kazuo , Maeda Norihiko , Nishikawa Shin-Ichi , Kodama Hiroaki
Published: July 2002

We demonstrated previously that a single injection of recombinant human macrophage colony-stimulating factor (rhM-CSF) is sufficient for osteoclast recruitment and survival in osteopetrotic (op/op) mice with a deficiency in osteoclasts resulting from a mutation in M-CSF gene. In this study, we show that a single injection of recombinant human vascular endothelial growth factor (rhVEGF) can similarly induce osteoclast recruitment in op/op mice. Osteoclasts predominantly expressed VEGF receptor 1 (VEGFR-1), and activity of recombinant human placenta growth factor 1 on osteoclast recruitment was comparable to that of rhVEGF, showing that the VEGF signal is mediated through VEGFR-1. The rhM-CSF–induced osteoclasts died after injections of VEGFR-1/Fc chimeric protein, and its effect was abrogated by concomitant injections of rhM-CSF. Osteoclasts supported by rhM-CSF or endogenous VEGF showed no significant difference in the bone-resorbing activity. op/op mice undergo an age-related resolution of osteopetrosis accompanied by an increase in osteoclast number. Most of the osteoclasts disappeared after injections of anti-VEGF antibody, demonstrating that endogenously produced VEGF is responsible for the appearance of osteoclasts in the mutant mice. In addition, rhVEGF replaced rhM-CSF in the support of in vitro osteoclast differentiation. These results demonstrate that M-CSF and VEGF have overlapping functions in the support of osteoclastic bone resorption.
Identification and Molecular Cloning of P75/Airm1, a Novel Member of the Sialoadhesin Family That Functions as an Inhibitory Receptor in Human Natural Killer Cells
Authors: Falco Michela , Biassoni Roberto , Bottino Cristina , Vitale Massimo , Sivori Simona , Augugliaro Raffaella , Moretta Lorenzo , Moretta Alessandro
Published: July 2002

In this study, by the generation of a specific monoclonal antibody, we identified p75/AIRM1 (for adhesion inhibitory receptor molecule 1), a novel inhibitory receptor that is mostly confined to human natural killer cells. p75/AIRM1 is a 75-kD glycoprotein that, upon sodium pervanadate treatment, becomes tyrosine phosphorylated and associates to src homology 2 domain–bearing protein tyrosine phosphatase (SHP)-1. The p75/AIRM1 gene is located on human chromosome 19 and encodes a novel member of the sialoadhesin family characterized by three immunoglobulin-like extracellular domains (one NH2-terminal V-type and two C2-type) and a classical immunoreceptor tyrosine–based inhibitory motif (ITIM) in the cytoplasmic portion. The highest amino acid sequence similarity has been found with the myeloid-specific CD33 molecule and the placental CD33L1 protein. Similar to other sialoadhesin molecules, p75/AIRM1 appears to mediate sialic acid–dependent ligand recognition.
Human Dendritic Cells Mediate Cellular Apoptosis via Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand (Trail)
Authors: Fanger Neil A. , Maliszewski Charles R. , Schooley Ken , Griffith Thomas S.
Published: July 2002

TRAIL (TNF-related apoptosis-inducing ligand) is a member of the TNF family that induces apoptosis in a variety of cancer cells. In this study, we demonstrate that human CD11c+ blood dendritic cells (DCs) express TRAIL after stimulation with either interferon (IFN)-γ or -α and acquire the ability to kill TRAIL-sensitive tumor cell targets but not TRAIL-resistant tumor cells or normal cell types. The DC-mediated apoptosis was TRAIL specific, as soluble TRAIL receptor blocked target cell death. Moreover, IFN-stimulated interleukin (IL)-3 receptor (R)α+ blood precursor (pre-)DCs displayed minimal cytotoxicity toward the same target cells, demonstrating a clear functional difference between the CD11c+ DC and IL-3Rα+ pre-DC subsets. These results indicate that TRAIL may serve as an innate effector molecule on CD11c+ DCs for the elimination of spontaneously arising tumor cells and suggest a means by which TRAIL-expressing DCs may regulate or eliminate T cells responding to antigen presented by the DCs.
T1/St2-Deficient Mice Demonstrate the Importance of T1/St2 in Developing Primary T Helper Cell Type 2 Responses
Authors: Townsend Michael J. , Fallon Padraic G. , Matthews David J. , Jolin Helen E. , McKenzie Andrew N.J.
Published: July 2002

We have generated mice with a deficiency in T1/ST2 expression to clarify the roles of T1/ST2 in T helper cell type 2 (Th2) responses. Using immunological challenges normally characterized by a Th2-like response, we have compared the responses of T1/ST2-deficient mice with those generated by wild-type mice. Using a primary pulmonary granuloma model, induced with Schistosoma mansoni eggs, we demonstrate that granuloma formation, characterized by eosinophil infiltration, is abrogated in T1/ST2-deficient mice. Furthermore, we clearly demonstrate that in the absence of T1/ST2 expression, the levels of Th2 cytokine production are severely impaired after immunization. Thus, in a secondary pulmonary granuloma model, draining lymph node cells from the T1/ST2-deficient animals produced significantly reduced levels of IL-4 and IL-5, despite developing granulomas of a magnitude similar to those of wild-type mice and comparable antigen-specific immunoglobulin isotype production. These data clearly demonstrate that T1/ST2 expression plays a role in the development of Th2-like cytokine responses and indicate that effector functions are inhibited in its absence.
Negative Regulation of T Cell Proliferation and Interleukin 2 Production by the Serine Threonine Kinase Gsk-3
Authors: Ohteki Toshiaki , Parsons Michael , Zakarian Arsen , Jones Russell G. , Nguyen Linh T. , Woodgett James R. , Ohashi Pamela S.
Published: July 2002

Glycogen synthase kinase (GSK)-3 is a protein serine/threonine kinase that regulates differentiation and cell fate in a variety of organisms. This study examined the role of GSK-3 in antigen-specific T cell responses. Using resting T cells from P14 T cell receptor (TCR)-transgenic mice (specific for the lymphocytic choriomeningitis virus and H-2Db), we demonstrated that GSK-3β was inactivated by serine phosphorylation after viral peptide–specific stimulation in vitro. To further investigate the role of GSK-3, we have generated a retroviral vector that expresses a constitutively active form of GSK-3β that has an alanine substitution at the regulatory amino acid, serine 9 (GSK-3βA9). Retroviral transduction of P14 TCR–transgenic bone marrow stem cells, followed by reconstitution, led to the expression of GSK-3βA9 in bone marrow chimeric mice. T cells from chimeric mice demonstrate a reduction in proliferation and interleukin (IL)-2 production. In contrast, in vitro assays done in the presence of the GSK-3 inhibitor lithium led to dramatically prolonged T cell proliferation and increased IL-2 production. Furthermore, in the presence of lithium, we show that nuclear factor of activated T cells (NF-AT)c remains in the nucleus after antigen-specific stimulation of T cells. Together, these data demonstrate that GSK-3 negatively regulates the duration of T cell responses.
Naive T Cells Transiently Acquire a Memory-like Phenotype during Homeostasis-Driven Proliferation
Authors: Goldrath Ananda W. , Bogatzki Lisa Y. , Bevan Michael J.
Published: July 2002

In a depleted lymphoid compartment, naive T cells begin a slow proliferation that is independent of cognate antigen yet requires recognition of major histocompatibility complex–bound self-peptides. We have followed the phenotypic and functional changes that occur when naive CD8+ T cells undergo this type of expansion in a lymphopenic environment. Naive T cells undergoing homeostasis-driven proliferation convert to a phenotypic and functional state similar to that of memory T cells, yet distinct from antigen-activated effector T cells. Naive T cells dividing in a lymphopenic host upregulate CD44, CD122 (interleukin 2 receptor β) and Ly6C expression, acquire the ability to rapidly secrete interferon γ, and become cytotoxic effectors when stimulated with cognate antigen. The conversion of naive T cells to cells masquerading as memory cells in response to a homeostatic signal does not represent an irreversible differentiation. Once the cellularity of the lymphoid compartment is restored and the T cells cease their division, they regain the functional and phenotypic characteristics of naive T cells. Thus, homeostasis-driven proliferation provides a thymus-independent mechanism for restoration of the naive compartment after a loss of T cells.
B7-Dc, a New Dendritic Cell Molecule with Potent Costimulatory Properties for T Cells
Authors: Tseng Su-Yi , Otsuji Mizuto , Gorski Kevin , Huang Xin , Slansky Jill E. , Pai Sara I. , Shalabi Ahmed , Shin Tahiro , Pardoll Drew M. , Tsuchiya Haruo
Published: July 2002

Dendritic cells (DCs), unique antigen-presenting cells (APCs) with potent T cell stimulatory capacity, direct the activation and differentiation of T cells by providing costimulatory signals. As such, they are critical regulators of both natural and vaccine-induced immune responses. A new B7 family member, B7-DC, whose expression is highly restricted to DCs, was identified among a library of genes differentially expressed between DCs and activated macrophages. B7-DC fails to bind the B7.1/2 receptors CD28 and cytotoxic T lymphocyte–associated antigen (CTLA)-4, but does bind PD-1, a receptor for B7-H1/PD-L1. B7-DC costimulates T cell proliferation more efficiently than B7.1 and induces a distinct pattern of lymphokine secretion. In particular, B7-DC strongly costimulates interferon γ but not interleukin (IL)-4 or IL-10 production from isolated naive T cells. These properties of B7-DC may account for some of the unique activity of DCs, such as their ability to initiate potent T helper cell type 1 responses.
Toward a Defined Anti-Leishmania Vaccine Targeting Vector Antigens
Authors: Valenzuela Jesus G. , Belkaid Yasmine , Garfield Mark K. , Mendez Susana , Kamhawi Shaden , Rowton Edgar D. , Sacks David L. , Ribeiro José M.C.
Published: July 2002

Leishmania parasites are transmitted to their vertebrate hosts by infected phlebotomine sand fly bites. Sand fly saliva is known to enhance Leishmania infection, while immunity to the saliva protects against infection as determined by coinoculation of parasites with vector salivary gland homogenates (SGHs) or by infected sand fly bites (Kamhawi, S., Y. Belkaid, G. Modi, E. Rowton, and D. Sacks. 2000. Science. 290:1351–1354). We have now characterized nine salivary proteins of Phlebotomus papatasi, the vector of Leishmania major. One of these salivary proteins, extracted from SDS gels and having an apparent mol wt of 15 kD, was able to protect vaccinated mice challenged with parasites plus SGH. A DNA vaccine containing the cDNA for the predominant 15-kD protein (named SP15) provided this same protection. Protection lasted at least 3 mo after immunization. The vaccine produced both intense humoral and delayed-type hypersensitivity (DTH) reactions. B cell–deficient mice immunized with the SP15 plasmid vaccine successfully controlled Leishmania infection when injected with Leishmania plus SGH. These results indicate that DTH response against saliva provides most or all of the protective effects of this vaccine and that salivary gland proteins or their cDNAs are viable vaccine targets against leishmaniasis.
Cd11c+B220+Gr-1+ Cells in Mouse Lymph Nodes and Spleen Display Characteristics of Plasmacytoid Dendritic Cells
Authors: Nakano Hideki , Yanagita Manabu , Gunn Michael Dee
Published: July 2002

Human plasmacytoid dendritic cells (pDCs) are major producers of IFNα, are activated by CpG motifs, and are believed to enter lymph nodes (LNs) via L-selectin dependent extravasation across high endothelial venules. To identify a similar murine DC type, CD11c+ cells in the LNs of L-selectin–deficient and control BALB/c mice were compared, revealing a population of CD11c+CD11b− cells that is reduced 85% in the LNs of L-selectin–deficient mice. These cells are Gr-1+B220+CD19−, either CD4+ or CD8+, and localize within T cell zones of LNs. Freshly isolated CD11c+Gr-1+ cells express major histocompatibility complex class II at low levels, display a plasmacytoid morphology, and survive poorly in culture. Their survival is increased and they develop a DC-like morphology in interleukin 3 and CpG. Like human pDCs, CD11c+Gr-1+ cells stimulate T cell proliferation after activation with CpG and produce IFNα after stimulation with influenza virus. These cells also display a strain-specific variation in frequency, being fivefold increased in the LNs of BALB/c relative to C57BL/6 mice. These CD11c+CD11b−B220+Gr-1+ cells appear to be the murine equivalent of human pDCs.
Epidermal Transglutaminase (TGase 3) Is the Autoantigen of Dermatitis Herpetiformis
Authors: Sárdy Miklós , Kárpáti Sarolta , Merkl Barbara , Paulsson Mats , Smyth Neil
Published: July 2002

Gluten sensitivity typically presents as celiac disease, a common chronic small intestinal disorder. However, in certain individuals it is associated with dermatitis herpetiformis, a blistering skin disease characterized by granular IgA deposits in the papillary dermis. While tissue transglutaminase has been implicated as the major autoantigen of gluten sensitive disease, there has been no explanation as to why this condition appears in two distinct forms. Here we show that while sera from patients with either form of gluten sensitive disease react both with tissue transglutaminase and the related enzyme epidermal (type 3) transglutaminase, antibodies in patients having dermatitis herpetiformis show a markedly higher avidity for epidermal transglutaminase. Further, these patients have an antibody population specific for this enzyme. We also show that the IgA precipitates in the papillary dermis of patients with dermatitis herpetiformis, the defining signs of the disease, contain epidermal transglutaminase, but not tissue transglutaminase or keratinocyte transglutaminase. These findings demonstrate that epidermal transglutaminase, rather than tissue transglutaminase, is the dominant autoantigen in dermatitis herpetiformis and explain why skin symptoms appear in a proportion of patients having gluten sensitive disease.
Functionally Distinct Subsets of CD1d-restricted Natural Killer T Cells Revealed by CD1d Tetramer Staining
Authors: Gumperz Jenny E. , Miyake Sachiko , Yamamura Takashi , Brenner Michael B.
Published: July 2002

CD1d-restricted natural killer (NK)T cells are known to potently secrete T helper (Th)1 and Th2 cytokines and to mediate cytolysis, but it is unclear how these contrasting functional activities are regulated. Using lipid antigen–loaded CD1d tetramers, we have distinguished two subsets of CD1d-restricted T cells in fresh peripheral blood that differ in cytokine production and cytotoxic activation. One subset, which was CD4−, selectively produced the Th1 cytokines interferon γ and tumor necrosis factor α, and expressed NKG2d, a marker associated with cytolysis of microbially infected and neoplastic cells. This subset up-regulated perforin after exposure to interleukin (IL)-2 or IL-12. In contrast, CD4+ CD1d-restricted NKT cells potently produced both Th1 and Th2 cytokines, up-regulated perforin in response to stimulation by phorbol myristate acetate and ionomycin but not IL-2 or IL-12, and could be induced to express CD95L. Further, for both CD1d-restricted NKT cell subsets, we found that antigenic stimulation induced cytokine production but not perforin expression, whereas exposure to inflammatory factors enhanced perforin expression but did not stimulate cytokine production. These results show that the various activities of CD1d-restricted T cells in tumor rejection, autoimmune disease, and microbial infections could result from activation of functionally distinct subsets, and that inflammatory and antigenic stimuli may influence different effector functions.
The Effect of Ionic Strength and Specific Anions on Substrate Binding and Hydrolytic Activities of Na,K-ATPase
Authors: Nørby Jens G. , Esmann Mikael
Published: July 2002

The physiological ligands for Na,K-ATPase (the Na,K-pump) are ions, and electrostatic forces, that could be revealed by their ionic strength dependence, are therefore expected to be important for their reaction with the enzyme. We found that the affinities for ADP3−, eosin2−, p-nitrophenylphosphate, and Vmax for Na,K-ATPase and K+-activated p-nitrophenylphosphatase activity, were all decreased by increasing salt concentration and by specific anions. Equilibrium binding of ADP was measured at 0–0.5 M of NaCl, Na2SO4, and NaNO3 and in 0.1 M Na-acetate, NaSCN, and NaClO4. The apparent affinity for ADP decreased up to 30 times. At equal ionic strength, I, the ranking of the salt effect was NaCl ≈ Na2SO4 ≈ Na-acetate < NaNO3 < NaSCN < NaClO4. We treated the influence of NaCl and Na2SO4 on Kdiss for E·ADP as a “pure” ionic strength effect. It is quantitatively simulated by a model where the binding site and ADP are point charges, and where their activity coefficients are related to I by the limiting law of Debye and Hückel. The estimated net charge at the binding site of the enzyme was about +1. Eosin binding followed the same model. The NO3− effect was compatible with competitive binding of NO3− and ADP in addition to the general I-effect. Kdiss for E·NO3 was ∼32 mM. Analysis of Vmax/Km for Na,K-ATPase and K+-p-nitrophenylphosphatase activity shows that electrostatic forces are important for the binding of p-nitrophenylphosphate but not for the catalytic effect of ATP on the low affinity site. The net charge at the p-nitrophenylphosphate-binding site was also about +1. The results reported here indicate that the reversible interactions between ions and Na,K-ATPase can be grouped according to either simple Debye-Hückel behavior or to specific anion or cation interactions with the enzyme.
Local Control Models of Cardiac Excitation–Contraction Coupling
Authors: Stern Michael D. , Song Long-Sheng , Cheng Heping , Sham James S.K. , Yang Huang Tian , Boheler Kenneth R. , Ríos Eduardo
Published: July 2002

In cardiac muscle, release of activator calcium from the sarcoplasmic reticulum occurs by calcium- induced calcium release through ryanodine receptors (RyRs), which are clustered in a dense, regular, two-dimensional lattice array at the diad junction. We simulated numerically the stochastic dynamics of RyRs and L-type sarcolemmal calcium channels interacting via calcium nano-domains in the junctional cleft. Four putative RyR gating schemes based on single-channel measurements in lipid bilayers all failed to give stable excitation–contraction coupling, due either to insufficiently strong inactivation to terminate locally regenerative calcium-induced calcium release or insufficient cooperativity to discriminate against RyR activation by background calcium. If the ryanodine receptor was represented, instead, by a phenomenological four-state gating scheme, with channel opening resulting from simultaneous binding of two Ca2+ ions, and either calcium-dependent or activation-linked inactivation, the simulations gave a good semiquantitative accounting for the macroscopic features of excitation–contraction coupling. It was possible to restore stability to a model based on a bilayer-derived gating scheme, by introducing allosteric interactions between nearest-neighbor RyRs so as to stabilize the inactivated state and produce cooperativity among calcium binding sites on different RyRs. Such allosteric coupling between RyRs may be a function of the foot process and lattice array, explaining their conservation during evolution.
Calcium Wave Propagation in Pancreatic Acinar Cells
Authors: Straub Stephen V. , Giovannucci David R. , Yule David I.
Published: July 2002

In pancreatic acinar cells, inositol 1,4,5-trisphosphate (InsP3)–dependent cytosolic calcium ([Ca2+]i) increases resulting from agonist stimulation are initiated in an apical “trigger zone,” where the vast majority of InsP3 receptors (InsP3R) are localized. At threshold stimulation, [Ca2+]i signals are confined to this region, whereas at concentrations of agonists that optimally evoke secretion, a global Ca2+ wave results. Simple diffusion of Ca2+ from the trigger zone is unlikely to account for a global [Ca2+]i elevation. Furthermore, mitochondrial import has been reported to limit Ca2+ diffusion from the trigger zone. As such, there is no consensus as to how local [Ca2+]i signals become global responses. This study therefore investigated the mechanism responsible for these events. Agonist-evoked [Ca2+]i oscillations were converted to sustained [Ca2+]i increases after inhibition of mitochondrial Ca2+ import. These [Ca2+]i increases were dependent on Ca2+ release from the endoplasmic reticulum and were blocked by 100 μM ryanodine. Similarly, “uncaging” of physiological [Ca2+]i levels in whole-cell patch-clamped cells resulted in rapid activation of a Ca2+-activated current, the recovery of which was prolonged by inhibition of mitochondrial import. This effect was also abolished by ryanodine receptor (RyR) blockade. Photolysis of d-myo InsP3 P4(5)-1-(2-nitrophenyl)-ethyl ester (caged InsP3) produced either apically localized or global [Ca2+]i increases in a dose-dependent manner, as visualized by digital imaging. Mitochondrial inhibition permitted apically localized increases to propagate throughout the cell as a wave, but this propagation was inhibited by ryanodine and was not seen for minimal control responses resembling [Ca2+]i puffs. Global [Ca2+]i rises initiated by InsP3 were also reduced by ryanodine, limiting the increase to a region slightly larger than the trigger zone. These data suggest that, while Ca2+ release is initially triggered through InsP3R, release by RyRs is the dominant mechanism for propagating global waves. In addition, mitochondrial Ca2+ import controls the spread of Ca2+ throughout acinar cells by modulating RyR activation.
Gating and Conductance Properties of Bk Channels Are Modulated by the S9–S10 Tail Domain of the α Subunit
Authors: Moss Brenda L. , Magleby Karl L.
Published: July 2002

The COOH-terminal S9–S10 tail domain of large conductance Ca2+-activated K+ (BK) channels is a major determinant of Ca2+ sensitivity (Schreiber, M., A. Wei, A. Yuan, J. Gaut, M. Saito, and L. Salkoff. 1999. Nat. Neurosci. 2:416–421). To investigate whether the tail domain also modulates Ca2+-independent properties of BK channels, we explored the functional differences between the BK channel mSlo1 and another member of the Slo family, mSlo3 (Schreiber, M., A. Yuan, and L. Salkoff. 1998. J. Biol. Chem. 273:3509–3516). Compared with mSlo1 channels, mSlo3 channels showed little Ca2+ sensitivity, and the mean open time, burst duration, gaps between bursts, and single-channel conductance of mSlo3 channels were only 32, 22, 41, and 37% of that for mSlo1 channels, respectively. To examine which channel properties arise from the tail domain, we coexpressed the core of mSlo1 with either the tail domain of mSlo1 or the tail domain of mSlo3 channels, and studied the single-channel currents. Replacing the mSlo1 tail with the mSlo3 tail resulted in the following: increased open probability in the absence of Ca2+; reduced the Ca2+ sensitivity greatly by allowing only partial activation by Ca2+ and by reducing the Hill coefficient for Ca2+ activation; decreased the voltage dependence ∼28%; decreased the mean open time two- to threefold; decreased the mean burst duration three- to ninefold; decreased the single-channel conductance ∼14%; decreased the Kd for block by TEAi ∼30%; did not change the minimal numbers of three to four open and five to seven closed states entered during gating; and did not change the major features of the dependency between adjacent interval durations. These observations support a modular construction of the BK channel in which the tail domain modulates the gating kinetics and conductance properties of the voltage-dependent core domain, in addition to determining most of the high affinity Ca2+ sensitivity.
Conjoint Analysis in Consumer Research: Issues and Outlook
Authors: Green Paul E. , Srinivasan V.
Published: July 2002

Since 1971 conjoint analysis has been applied to a wide variety of problems in consumer research. This paper discusses various issues involved in implementing conjoint analysis and describes some new technical developments and application areas for the methodology.
The Costs and Benefits of Consuming
Authors: Csikszentmihalyi Mihaly
Published: July 2002

Consuming is defined as behavior whereby entropy is increased in exchange for existential or experiential rewards. Existential rewards are well known—for example, the satisfaction of Maslowian needs. But experiential rewards are perhaps just as important: these refer to the temporary improvement in positive mood people experience when they are acting in goal-directed, purposeful ways. Consuming is one way for obtaining such experiences. It is suggested that in order to evaluate the impact of consuming it is necessary to measure the entropy costs of the behavior balanced against the psychic benefits it provides.
2𝑘-regular maps on smooth manifolds
Authors: Handel David
Published: July 2002

A continuous map

f
:
X
→

R

N

f:X\to \mathbb {R} ^{N}

is said to be

k
k

-regular if whenever

x

1

,
…
,

x

k

x_{1},\dots , x_{k}

are distinct points of

X
X

, then

f
(

x

1

)
,
…
,
f
(

x

k

)

f(x_{1}),\dots , f(x_{k})

are linearly independent over

R

\mathbb {R}

. For smooth manifolds

M
M

we obtain new lower bounds on the minimum

N
N

for which a

2
k

2k

-regular map

M
→

R

N

M \to \mathbb {R} ^{N}

can exist in terms of the dual Stiefel-Whitney classes of

M
M

.
Multidimensional analogues of Bohr’s theorem on power series
Authors: Aizenberg Lev
Published: July 2002

Generalizing the classical result of Bohr, we show that if an

n
n

-variable power series converges in

n
n

-circular bounded complete domain

D
D

and its sum has modulus less than 1, then the sum of the maximum of the modulii of the terms is less than 1 in the homothetic domain

r
⋅
D

r \cdot D

, where

r
=
1
−

2

/

3

n

r = 1- \sqrt [n]{2/3}

. This constant is near to the best one for the domain

D
=
{
z
:

|

z
1

|

+
…
+

|

z
n

|

D = \{z: |z_1 |+ \ldots + |z_n |

>
1
}
.

> 1 \} .
Herz-Schur multipliers and weakly almost periodic functions on locally compact groups
Authors: Xu Guangwu
Published: July 2002

For a locally compact group

G
G

and

1
>
p
>
∞

1>p>\infty

, let

A

p

(
G
)

A_{p}(G)

be the Herz–Figà-Talamanca algebra and

B

p

(
G
)

B_{p}(G)

the Herz-Schur multipliers of

G
G

, and

M

A

p

(
G
)

MA_{p}(G)

the multipliers of

A

p

(
G
)

A_{p}(G)

. Let

W
(
G
)

W(G)

be the algebra of continuous weakly almost periodic functions on

G
G

. In this paper, we show that (1), if

G
G

is a noncompact nilpotent group or a noncompact [IN]-group, then

W
(
G
)

/

B

p

(
G

)

−

W(G)/B_{p}(G)^{-}

contains a linear isometric copy of

l

∞

(

N

)

l^{\infty }({\mathbb {N}})

; (2), for a noncommutative free group

F
,

B

p

(
F
)

F, B_{p}(F)

is a proper subset of

M

A

p

(
F
)
∩

W
(
F
)

{MA_{p}(F)\cap {W(F)}}

.
Divisor spaces on punctured Riemann surfaces
Authors: Kallel Sadok
Published: July 2002

In this paper, we study the topology of spaces of

n
n

-tuples of positive divisors on (punctured) Riemann surfaces which have no points in common (the divisor spaces). These spaces arise in connection with spaces of based holomorphic maps from Riemann surfaces to complex projective spaces. We find that there are Eilenberg-Moore type spectral sequences converging to their homology. These spectral sequences collapse at the

E
2

E^2

term, and we essentially obtain complete homology calculations. We recover for instance results of F. Cohen, R. Cohen, B. Mann and J. Milgram, The topology of rational functions and divisors of surfaces, Acta Math. 166 (1991), 163–221. We also study the homotopy type of certain mapping spaces obtained as a suitable direct limit of the divisor spaces. These mapping spaces, first considered by G. Segal, were studied in a special case by F. Cohen, R. Cohen, B. Mann and J. Milgram, who conjectured that they split. In this paper, we show that the splitting does occur provided we invert the prime two.
Convergence of a splitting method of high order for reaction-diffusion systems
Authors: Descombes Stéphane
Published: July 2002

In this article, we prove the convergence of a splitting scheme of high order for a reaction-diffusion system of the form

u
t

−
M
Δ
u
+
F
(
u
)
=
0

u_t-M\Delta u +F(u)=0

where

M
M

is an

m
×
m

m \times m

matrix whose spectrum is included in

{

R

z
>
0
}

\{{\mathfrak {R}} z > 0 \}

. This scheme is obtained by applying a Richardson extrapolation to a Strang formula.
A priori error estimates for numerical methods for scalar conservation laws. Part I: The general approach
Authors: Cockburn Bernardo , Gremaud Pierre-Alain
Published: July 2002

In this paper, we construct a general theory of a priori error estimates for scalar conservation laws by suitably modifying the original Kuznetsov approximation theory. As a first application of this general technique, we show that error estimates for conservation laws can be obtained without having to use explicitly any regularity properties of the approximate solution. Thus, we obtain optimal error estimates for the Engquist-Osher scheme without using the fact (i) that the solution is uniformly bounded, (ii) that the scheme is total variation diminishing, and (iii) that the discrete semigroup associated with the scheme has the L

1

^{1}

-contraction property, which guarantees an upper bound for the modulus of continuity in time of the approximate solution.
Analysis of a class of nonconforming finite elements for crystalline microstructures
Authors: Kloucek Petr , Li Bo , Luskin Mitchell
Published: July 2002

An analysis is given for a class of nonconforming Lagrange-type finite elements which have been successfully utilized to approximate the solution of a variational problem modeling the deformation of martensitic crystals with microstructure. These elements were first proposed and analyzed in 1992 by Rannacher and Turek for the Stokes equation. Our analysis highlights the features of these elements which make them effective for the computation of microstructure. New results for superconvergence and numerical quadrature are also given.
A generalized discrepancy and quadrature error bound
Authors: Hickernell Fred
Published: July 2002

An error bound for multidimensional quadrature is derived that includes the Koksma-Hlawka inequality as a special case. This error bound takes the form of a product of two terms. One term, which depends only on the integrand, is defined as a generalized variation. The other term, which depends only on the quadrature rule, is defined as a generalized discrepancy. The generalized discrepancy is a figure of merit for quadrature rules and includes as special cases theLp{\mathcal L}^p-star discrepancy andPαP_\alphathat arises in the study of lattice rules.
Pointwise error estimates and asymptotic error expansion inequalities for the finite element method on irregular grids: Part I. Global estimates
Authors: Schatz Alfred
Published: July 2002

This part contains new pointwise error estimates for the finite element method for second order elliptic boundary value problems on smooth bounded domains in

R

N

\mathbb {R}^{N}

. In a sense to be discussed below these sharpen known quasi–optimal

L

∞

L_{\infty }

and

W

∞

1

W^{1}_{\infty }

estimates for the error on irregular quasi–uniform meshes in that they indicate a more local dependence of the error at a point on the derivatives of the solution

u
u

. We note that in general the higher order finite element spaces exhibit more local behavior than lower order spaces. As a consequence of these estimates new types of error expansions will be derived which are in the form of inequalities. These expansion inequalities are valid for large classes of finite elements defined on irregular grids in

R

N

\mathbb {R}^{N}

and have applications to superconvergence and extrapolation and a posteriori estimates. Part II of this series will contain local estimates applicable to non–smooth problems.
An adaptive strategy for elliptic problems including a posteriori controlled boundary approximation
Authors: Dörfler W. , Rumpf M.
Published: July 2002

We derive a posteriori error estimates for the approximation of linear elliptic problems on domains with piecewise smooth boundary. The numerical solution is assumed to be defined on a Finite Element mesh, whose boundary vertices are located on the boundary of the continuous problem. No assumption is made on a geometrically fitting shape. A posteriori error estimates are given in the energy norm and the

L
2

L^2

-norm, and efficiency of the adaptive algorithm is proved in the case of a saturated boundary approximation. Furthermore, a strategy is presented to compute the effect of the non-discretized part of the domain on the error starting from a coarse mesh. This especially implies that parts of the domain, where the measured error is small, stay non-discretized. The presented algorithm includes a stable path following to supply a sufficient polygonal approximation of the boundary, the reliable computation of the a posteriori estimates and a mesh adaptation based on Delaunay techniques. Numerical examples illustrate that errors outside the initial discretization will be detected.