bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing a role for enhancer‐blocking activity in gene regulation within the murine T‐cell receptor α/δ locus
Authors: Sleckman Barry P. , Carabana Juan , Zhong Xiaoping , Krangel Michael S. 
Published: March 2003

SummaryAlthough situated close together within the T‐cell receptor (TCR) α/δ locus, TCR δ and TCR α gene segments are controlled by two developmental stage‐specific enhancers and are activated according to distinct developmental programmes. We previously used a stable transfection colony assay to identify an enhancer‐blocking element, blocking element alpha/delta‐1 (BEAD‐1), between the TCR δ and α gene segments of the human TCR α/δ locus. We hypothesized that enhancer‐blocking by BEAD‐1 might be required to prevent the TCR δ enhancer from activating TCR α gene segment transcription and rearrangement at the double negative stage of thymocyte development. Here, we used a transfection approach to define partial enhancer‐blocking activity in an analogous position of the murine TCR α/δ locus. To test the functional significance of this activity in vivo, we used gene targeting to delete the region from the endogenous locus. We found no perturbation of TCR δ and TCR α gene expression and rearrangement on targeted alleles, indicating that enhancer‐blocking activity in this region is not required to maintain the developmentally distinct activation profiles of the two genes. We suggest that appropriate regulation may be achieved as a result of intrinsic biases in enhancer–promoter interactions or a developmental stage specificity to promoter function that is distinct from any additional specificity imposed by the enhancers themselves.
Crucial Fas–Fas ligand interaction in spontaneous acceptance of hepatic allografts in mice
Authors: Uchiyama Hideaki , Kishihara Kenji , Minagawa Ryosuke , Hashimoto Koji , Sugimachi Keizo , Nomoto Kikuo 
Published: March 2003

SummaryThe Fas/Fas ligand (FasL) system plays important roles in the immune system, including host immunoregulation and cytotoxicity. In this study, we investigated the involvement of Fas–FasL interactions in spontaneous acceptance of hepatic allografts in murine orthotopic liver transplantation. Liver transplantation between the C57BL/6 (B6, H‐2b) donor and the MRL/Mp (MRL, H‐2k) recipient was performed in various combinations of donor and recipient mice with wild type (+/+), Fas‐mutant (lpr) or FasL‐mutant (gld) genotypes. The prolongation and spontaneous acceptance of the fully allogeneic grafts in recipients was not observed in either MRL‐lpr recipients with B6+/+ livers or MRL+/+ recipients with B6‐gld livers. Moreover, the serum alanine aminotransferase (ALT) levels and the degree of cell infiltration into hepatic allografts on day 7 after transplantation were inversely correlated with the recipient survival time (in days). The donor‐specific cytotoxic T‐lymphocyte (CTL) activities of the graft‐infiltrating cells (GICs) from MRL‐gld recipients with B6+/+ livers were much lower than those from MRL+/+ or ‐lpr recipients on days 5 and 10 after transplantation. However, the CTL activities of the GICs from MRL+/+ and ‐gld recipients predominately disappeared by day 15 after transplantation. Furthermore, the anti‐donor CTL activities induced in MRL+/+ recipients were ascribed to CD8+ cells, and were not mediated by Fas–FasL interactions. These results strongly suggest that the Fas/FasL system plays a critical role for recipient immunoregulation, enabling recipients in accepting hepatic allografts by deletion of the donor‐specific T cells, but not for CTL/target cell interaction in MRL+/+ recipients.
Intranasal administration of a synthetic lipopeptide without adjuvant induces systemic immune responses
Authors: BenMohamed Lbachir , Krishnan Radhika , Auge Catherine , Primus James F. , Diamond Don J. 
Published: March 2003

SummaryParenteral injection of a lipopeptide containing a human leucocyte antigen (HLA)‐A*0201‐restricted cytotoxic T‐lymphocyte (CTL) epitope from the human cytomegalovirus (HCMV) immunodominant matrix protein pp65 efficiently induces systemic CTL responses in HLA‐A*0201 transgenic mice. In this study, we demonstrate that intranasal (i.n.) administration of this lipopeptide, covalently linked to a universal T helper (Th) epitope (PADRE), also induces potent systemic CTL responses. Immune responses were substantially reduced when the unlipidated peptide analogue was used (P<0·01). The induced CTL were CD8+, major histocompatibility complex (MHC) class I‐restricted and CMV specific. Moreover, i.n. administration of this lipidated peptide elicited both systemic and local mucosal CD4+ T‐cell proliferative responses, as well as antigen‐specific delayed type hypersensitivity (DTH) immune responses. In contrast, mice receiving the unlipidated peptide analogue developed substantially reduced Th or DTH responses (P<0·05). These results highlight the usefulness and potential of lipopeptides delivered via mucosal routes as painless, safe, and non‐invasive vaccines.
Role of antiretroviral regimes in HIV‐1 patients in reducing immune activation
Authors: Jiménez Antonio , Molero Laura , Jiménez Ana , Castañón Susana , Subirá Dolores , De Górgolas Miguel , Fedz‐Guerrero Manuel , García Rosa 
Published: March 2003

SummaryWe assessed whether antiretroviral regimes are able to diminish apoptosis and markers of lymphocyte activation and restore lymphocyte proliferation. T‐cell subset, spontaneous and induced apoptosis, CD95 and soluble Fas antigen and cell proliferation were analysed in 41 human immunodeficiency virus type 1‐positive patients. Twenty‐five were in asymptomatic stage A and 16 were in stage B/C. Thirty‐five received antiretroviral treatment: 18 received two inhibitors of reverse transcriptase and one protease inhibitor and 17 received three inhibitors of reverse transcriptase. Six patients did not receive treatment, for different reasons, but continued to participate in the study. Studies were performed at baseline, 3, 6 and 12 months. Levels of CD4 increased slightly until 6 months of antiretroviral treatment, as a whole, in all the patients treated. Naïve CD4 lymphocytes, as well as memory CD4 lymphocytes, remained constant. Spontaneous apoptosis of lymphocytes, after 72 hr of culture, decreased in all patients treated, but to a much smaller extent than phytohaemagglutinin‐induced apoptosis. In both groups treated, levels of soluble Fas decreased until 6 months of treatment and then increased again. Lymphocyte proliferation reached normal levels after 1 year of treatment. In patients without treatment CD4 cells decreased slowly and no modification in activation markers was found. Antiretroviral regimes decrease immune activation as well as viral load and this deactivation restores lymphocyte proliferation.
Antibody to Cryptococcus neoformans capsular glucuronoxylomannan promotes expression of interleukin‐12Rβ2 subunit on human T cells in vitro through effects mediated by antigen‐presenting cells
Authors: Vecchiarelli Anna , Pietrella Donatella , Bistoni Francesco , Kozel Thomas R. , Casadevall Arturo 
Published: March 2003

SummaryThe results reported herein show that T cells responding to encapsulated Cryptococcus neoformans cells had reduced expression of interleukin‐12 receptor β2 (IL‐12Rβ2) in comparison to those responding to non‐encapsulated cells. This suggested that encapsulation with glucuronoxylomannan (GXM), the principal constituent of the C. neoformans polysaccharide antiphagocytic capsule, inhibited expression of the IL‐12Rβ2 subunit on T cells responding to cryptococcal antigens. Addition of GXM‐binding monoclonal antibody (mAb) overcame this effect by promoting IL‐12Rβ2 expression and by decreasing IL‐1R expression on T cells. This effect may be a consequence of mAb‐induced changes on antigen‐presenting cells (APC) that are closely related to increased phagocytosis. Blocking of phagocytosis with monoiodacetic acid (MIA) precluded up‐regulation of B7 expression on APC and was associated with diminished IL‐12Rβ2 expression on T cells. The observed effects on T cells were interpreted as a consequence of increased APC function due to enhanced phagocytosis. These findings suggest a mechanism by which specific antibody can promote the polarization of the cellular immune response towards a Th1‐like response and thus contribute to an enhanced cellular immune response against C. neoformans.
The strict regulation of lymphocyte migration to splenic white pulp does not involve common homing receptors
Authors: Nolte Martijn A. , Hamann Alf , Kraal Georg , Mebius Reina E. 
Published: March 2003

SummaryAlthough the spleen is the largest secondary lymphoid organ, little is known about the regulation of lymphocyte migration towards its different compartments of red and white pulp, in contrast to the well‐studied mechanisms of lymphocyte homing to lymph nodes. Here we show that short‐term trypsin treatment of lymphocytes cleaved off molecules involved in entry into lymph nodes, while homing to the splenic white pulp was unaltered. Prolonged trypsin treatment also abolished the ability of lymphocytes to enter the white pulp. Analysis of affected cell surface molecules and adoptive transfer studies in combination with blocking antibodies revealed that l‐selectin, CD44, PSGL‐1 and the α4 integrins are not required for migration to the white pulp. Although lymphocyte function‐associated antigen‐1 (LFA‐1) is critical for entry into lymph nodes, we show here that in the absence of functional LFA‐1 molecules, lymphocytes can still enter the white pulp, in spite of the high expression of intercellular adhesion molecule‐1 on sinus lining cells in the marginal zone. The data indicate that adhesion molecules involved in lymphocyte homing to lymph nodes are not essential for migration towards the splenic white pulp, but that additional, trypsin‐sensitive, and so far unidentified, molecules are required.
The modulatory effects of prostaglandin‐E on cytokine production by human peripheral blood mononuclear cells are independent of the prostaglandin subtype
Authors: Dooper Maaike M. B. W. , Wassink Lianne , M'Rabet Laura , Graus Yvo M. F. 
Published: March 2003

SummaryThe production of inflammatory mediators, relevant to (auto)immune diseases and chronic inflammatory conditions, can be modulated by dietary intake of n‐3 and n‐6 long chain polyunsaturated fatty acids (PUFAs). It was suggested that these effects are related to the formation of different series of eicosanoids, in particular prostaglandin‐E (PGE). In this study we investigated whether prostaglandin subtypes metabolized from arachidonic acid (PGE2), dihomo‐γ‐linolenic acid (PGE1) or eicosapentaenoic acid (PGE3) have different effects on T‐cell proliferation and cytokine production in vitro. Freshly isolated human peripheral blood mononuclear cells (PBMC) were stimulated with concanavalin A (ConA) or lipopolysaccharide (LPS) in the presence or absence of exogenous PGE1, PGE2 or PGE3. We found that tumour necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ) and to a lesser extent interleukin (IL)‐10 production was inhibited by all PGE‐subtypes in ConA‐stimulated PBMC concomitant with unaffected IL‐2 levels. The modulated cytokine production of ConA stimulated cells was independent of T‐cell proliferation. PGE2 and PGE1 moderately stimulated proliferation, while PGE3 inhibited the proliferative response to some extent. In LPS‐stimulated PBMC, TNF‐α production was inhibited by all PGE‐subtypes, whereas IL‐6 remained unaffected and IL‐10 production was increased. Time course experiments on the effects of PGE‐subtypes on cytokine production after ConA or LPS stimulation showed these effects to be time dependent, but indifferent of the prostaglandin subtype added. Overall, the modulatory effects of PGE on cytokine production were irrespective of the subtype. This may implicate that the immunomodulatory effects of PUFAs, with respect to cytokine production, are not caused by a shift in the subtype of PGE.
C‐reactive protein‐mediated phagocytosis and phospholipase D signalling through the high‐affinity receptor for immunoglobulin G (FcγRI)
Authors: Bodman‐Smith Katherine B. , Melendez Alirio J. , Campbell Ian , Harrison Patrick T. , Allen Janet M. , Raynes John G. 
Published: March 2003

SummaryC‐reactive protein (CRP) is the prototypic acute‐phase protein in man which performs innate immune functions. CRP‐mediated phagocytosis may be indirect, through activation of complement and complement receptors, or direct, through receptors for the Fc portion of immunoglobulin G (IgG; FcγRs) or even a putative CRP‐specific receptor. No strong evidence has been shown to indicate which receptors may be responsible for phagocytosis or signalling responses. Using BIAcore technology, we confirm that CRP binds directly to the extracellular portion of FcγRI with a threefold higher affinity than IgG (KD = 0·81 × 10−9 m). Binding is Ca2+ dependent and is inhibited by IgG1 but not by phosphorylcholine (PC). CRP opsonization (using CRP concentrations within the normal human serum range) of PC‐conjugated sheep erythrocytes increased phagocytosis of these particles by COS‐7 cells transfected with FcγRI‐II chimaera or FcγRI/γ‐chain. Interferon‐γ‐treated U937 cells, which signal through FcγRI to activate phospholipase D (PLD) in response to cross‐linked IgG, were also activated by CRP without any requirement for further cross‐linking. These studies indicate that CRP is capable of binding to and cross‐linking FcγRI thereby resulting in PLD activation and increased phagocytosis. Uptake by FcγRI has been reported to promote various acquired immune responses suggesting that CRP could act in a similar way.
CD20‐mediated apoptosis: signalling through lipid rafts
Authors: Deans Julie P. , Li Haidong , Polyak Maria J. 
Published: March 2003

SummaryCD20 is an effective target for therapeutic B‐cell depletion with monoclonal antibodies. One proposed mechanism of action is direct cytotoxicity mediated via tyrosine kinase‐dependent signalling pathways activated upon CD20 cross‐linking. The association of CD20 with membrane microdomains known as lipid rafts, enriched in src‐family tyrosine kinases and other signalling effectors, suggests an indirect mechanism of anti‐CD20‐induced apoptosis in which activation of src‐family kinases occurs as a consequence of lipid raft clustering.
Complete analysis of the B‐cell response to a protein antigen, from in vivo germinal centre formation to 3‐D modelling of affinity maturation
Authors: Adams Claire L. , Macleod Megan K. L. , James Milner‐White E. , Aitken Robert , Garside Paul , Stott David I. 
Published: March 2003

SummarySomatic hypermutation of immunoglobulin variable region genes occurs within germinal centres (GCs) and is the process responsible for affinity maturation of antibodies during an immune response. Previous studies have focused almost exclusively on the immune response to haptens, which may be unrepresentative of epitopes on protein antigens. In this study, we have exploited a model system that uses transgenic B and CD4+ T cells specific for hen egg lysozyme (HEL) and a chicken ovalbumin peptide, respectively, to investigate a tightly synchronized immune response to protein antigens of widely differing affinities, thus allowing us to track many facets of the development of an antibody response at the antigen‐specific B cell level in an integrated system in vivo. Somatic hypermutation of immunoglobulin variable genes was analysed in clones of transgenic B cells proliferating in individual GCs in response to HEL or the cross‐reactive low‐affinity antigen, duck egg lysozyme (DEL). Molecular modelling of the antibody–antigen interface demonstrates that recurring mutations in the antigen‐binding site, selected in GCs, enhance interactions of the antibody with DEL. The effects of these mutations on affinity maturation are demonstrated by a shift of transgenic serum antibodies towards higher affinity for DEL in DEL‐cOVA immunized mice. The results show that B cells with high affinity antigen receptors can revise their specificity by somatic hypermutation and antigen selection in response to a low‐affinity, cross‐reactive antigen. These observations shed further light on the nature of the immune response to pathogens and autoimmunity and demonstrate the utility of this novel model for studies of the mechanisms of somatic hypermutation.
An empirical examination of the role of social integration in system development projects
Authors: Aladwani Adel M 
Published: March 2003

Abstract.In spite of the apparent importance of social integration for work collectives within organizations, information systems researchers have so far paid little, if any, attention to evaluating its role in system development projects. The present study tries to contribute to the literature by proposing and testing a model that examines some of the antecedents and consequences of social integration in system development projects. Data collected from system development project leaders working in 84 US organizations were used to test the model. The findings suggest that higher social integration and, consequently, higher system development project performance is best attained when management provides basic support for the work of the project. The results also reveal that the nature of the relationship between social integration and project performance may be contingent upon some other factors. The implications of the findings of this research are discussed.
The Bactrocera tryoni homologue of the Drosophila melanogaster sex‐determination gene doublesex
Authors: Shearman D. C. A. , Frommer M. 
Published: March 2003

AbstractA homologue of the bifunctional sex‐determining gene, doublesex (dsx), has been identified in the tephritid fruit fly, Bactrocera tryoni, and has been found to be expressed in a sex‐specific manner in adult flies. The male‐ and female‐specific cDNAs are identical at their 5′ ends but differ at their 3′ ends and appear to be the products of alternate splicing. The level of identity of the sex‐specific DSX proteins of B. tryoni with the D. melanogaster DSX proteins, across the region corresponding to the DNA binding domain and the oligomerization domains, is greater than 85%. Four sequence motifs which are ten to thirteen bases identical to the TRA/TRA‐2 binding sites (thirteen‐nucleotide repeat sequences) are present in the female‐specific exon of the B. tryoni dsx gene.
Mitochondrial DNA sequence variation among populations and host races of Lambdina fiscellaria (Gn.) (Lepidoptera: Geometridae)
Authors: Sperling F.A.H. , Raske A. G. , Otvos I. S. 
Published: March 2003

AbstractThe hemlock looper, Lambdina fiscellaria (Gn.), is a recurring major forest pest that is widely distributed in North America. Three subspecies (L. f. fiscellaria, L. f. lugubrosa (Hulst) and L. f. somniaria (Hulst)) have been recognized based on larval host or adult pheromone differences, but no consistent morphological differences have been reported. To clarify their taxonomic status, we surveyed mitochondrial DNA (mtDNA) sequence and restriction site variation in two protein coding genes, cytochrome oxidase I and II (COI and COII), in populations across the range of L. fiscellaria. In addition to variation in COI and COII, we found an intergenic spacer region of 20–23 bp located between the tRNA tyrosine gene and the start of COI. Of the 141 speciments of L. fiscellaria assayed, 137 were grouped into two distinct mtDNA lineages, one of which was disproportionately associated with eastern populations and one with western populations. However, single specimens and two populations in eastern Canada had mtDNA resembling that of western populations. Three divergent and rare haplotypes had basal affinities to the two common lineages. The two major lineages of L. fiscellaria were diverged by approximately 2% from each other, as well as from the mtDNA of two outgroup species, L. athasaria (Walker) and L. pellucidaria (G. & R.). The two outgroup species had essentially the same mtDNA and may be conspecific. We interpret the pattern of mtDNA variation within L. fiscellaria as indicating genetic polymorphism within a single species without clear subspecific divisions, rather than evidence of multiple cryptic species.
cDNA sequence, mRNA expression and genomic DNA of trypsinogen from the Indianmeal moth, Plodia interpunctella
Authors: Zhu Y. C. , Oppert B. , Kramer K. J. , McGaughey W. H. , Dowdy A. K. 
Published: March 2003

AbstractTrypsin‐like enzymes are major insect gut enzymes that digest dietary proteins and proteolytically activate insecticidal proteins produced by the bacterium Bacillus thuringiensis (Bt). Resistance to Bt in a strain of the Indianmeal moth, Plodia interpunctella, was linked to the absence of a major trypsin‐like proteinase (Oppert et al., 1997). In this study, trypsin‐like proteinases, cDNA sequences, mRNA expression levels and genomic DNAs from Bt‐susceptible and ‐resistant strains of the Indianmeal moth were compared. Proteinase activity blots of gut extracts indicated that the susceptible strain had two major trypsin‐like proteinases, whereas the resistant strain had only one. Several trypsinogen‐like cDNA clones were isolated and sequenced from cDNA libraries of both strains using a probe deduced from a conserved sequence for a serine proteinase active site. cDNAs of 852 nucleotides from the susceptible strain and 848 nucleotides from the resistant strain contained an open reading frame of 783 nucleotides which encoded a 261‐amino acid trypsinogen‐like protein. There was a single silent nucleotide difference between the two cDNAs in the open reading frame and the predicted amino acid sequence from the cDNA clones was most similar to sequences of trypsin‐like proteinases from the spruce budworm, Choristoneura fumiferana, and the tobacco hornworm, Manduca sexta. The encoded protein included amino acid sequence motifs of serine proteinase active sites, conserved cysteine residues, and both zymogen activation and signal peptides. Northern blotting analysis showed no major difference between the two strains in mRNA expression in fourth‐instar larvae, indicating that transcription was similar in the strains. Southern blotting analysis revealed that the restriction sites for the trypsinogen genes from the susceptible and resistant strains were different. Based on an enzyme size comparison, the cDNA isolated in this study corresponded to the gene for the smaller of two trypsin‐like proteinases, which is found in both the Bt‐susceptible and ‐resistant strains of the Indianmeal moth. The sequences reported in this paper have been deposited in the GenBank database (accession numbers AF064525 for the RC688 strain and AF064526 for HD198).