bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calmodulin protects cells from death under normal growth conditions and mitogenic starvation but plays a mediating role in cell death upon B‐cell receptor stimulation
Authors: Schmalzigaug Robert , Ye Qunrui , Berchtold Martin W. 
Published: March 2003

SummaryCalmodulin (CaM) is the main intracellular Ca2+ sensor protein responsible for mediating Ca2+ triggered processes. Chicken DT40 lymphoma B cells express CaM from the two genes, CaMI and CaMII. Here we report the phenotypes of DT40 cells with the CaMII gene knocked out. The disruption of the CaMII gene causes the intracellular CaM level to decrease by 60%. CaMII−/− cells grow more slowly and die more frequently as compared to wild type (wt) cells but do not exhibit significant differences in their cell cycle profile. Both phenotypes are more pronounced at reduced serum concentrations. Upon stimulation of the B‐cell receptor (BCR), the resting Ca2+ levels remain elevated after the initial transient in CaMII−/− cells. Despite higher Ca2+ resting levels, the CaMII−/− cells are partially protected from BCR induced apoptosis indicating that CaM plays a dual role in apoptotic processes.
The regulation of FasL expression during activation‐induced cell death (AICD)
Authors: Nguyen Thang , Russell John 
Published: March 2003

SummaryActivation‐induced cell death (AICD), a Fas ligand (FasL)‐dependent pathway, is important for maintaining T‐cell homeostasis. Interleukin‐2 (IL‐2), an enhancer of AICD, can also enhance FasL expression. However, we show that the level of FasL or FLIP protein did not correlate with the susceptibility to AICD. Some T cells expressed high levels of FasL yet failed to undergo AICD, while others expressed little FasL and were sensitive. AICD susceptibility did not correlate with the kinetics of FasL up‐regulation or down‐regulation. The down‐regulation of FasL can be mediated by a metalloprotease. However, we describe an alternative mechanism for the loss of FasL by endocytosis. Endocytosis inhibitors such as cytochalasins, sodium azide, deoxyglucose, or low temperatures prevented the loss of FasL. KB8301, a metalloprotease inhibitor had no effect on the loss of FasL or AICD in the T cells. Enhancing FasL expression was not crucial for AICD and the down‐regulation of FasL proceeded via endocytosis.
Enhanced maturation and functional capacity of monocyte‐derived immature dendritic cells by the synthetic immunomodulator Murabutide
Authors: Vidal Vincent , Dewulf Joelle , Bahr George M. 
Published: March 2003

SummaryMurabutide is a safe synthetic immunomodulator derived from muramyl dipeptide, the smallest bioactive unit of bacterial peptidoglycan. Although it is well known that muramyl peptides modulate the functions of monocytes/macrophages, their activity on dendritic cells is poorly documented. We thus investigated the effects of Murabutide on immunophenotype, endocytosis, T‐cell stimulatory capacity, and cytokine secretion of human monocyte‐derived immature dendritic cells (iDCs). We found that Murabutide triggers immunophenotypic changes as upon treatment, iDCs up‐regulate the surface expression of the major histocompatibility complex type II molecule human leucocyte antigen‐DR, the co‐stimulatory molecules CD80, CD86 and CD40 and the differentiation marker CD83, and down‐regulate the expression of the mannose receptor. These phenotypic changes are also mirrored by changes in their biological activity. Subsequent to treatment with the synthetic immunomodulator, DC have a decreased endocytic capacity but exhibit enhanced stimulatory capacity for both allogeneic and autologous T cells. In addition, Murabutide‐stimulated iDCs have a greater cytostatic activity toward the tumour cell line THP‐1. Furthermore, in the presence of Murabutide, DCs transiently increased the release of macrophage inhibitory protein‐1β, tumour necrosis factor‐α and interleukin‐10, whereas the enhanced production of macrophage‐colony stimulating factor was sustained over the 3‐day period analysed. In addition, Murabutide triggers the phosphorylation of the three classes of mitogen‐activated protein kinases in iDCs. Altogether our results demonstrate that Murabutide triggers the maturation and activation of monocyte‐derived iDCs. As this immunomodulator is approved for administration in humans, it could be a useful adjunct to boost the efficacy of DC‐based vaccines designed against tumours or virus‐infected cells.
Characterization of glycosylphosphatidylinositol‐anchored decay accelerating factor (GPI‐DAF) and transmembrane DAF gene expression in wild‐type and GPI‐DAF gene knockout mice using polyclonal and monoclonal antibodies with dual or single specificity
Authors: Miwa Takashi , Sun Xiujun , Ohta Rieko , Okada Noriko , Harris Claire L. , Morgan B. Paul , Song Wen‐Chao 
Published: March 2003

SummaryDecay‐accelerating factor (DAF, CD55) is a glycosylphosphatidylinositol (GPI)‐linked membrane inhibitor of complement activation. While human and other mammalian species contain only one DAF gene, two distinct DAF genes, referred to as GPI‐DAF and transmembrane (TM)‐DAF, respectively, have been identified in the mouse. Using several independently generated monoclonal and polyclonal antibodies, either with dual or single specificity for GPI‐DAF and TM‐DAF gene products, we have examined the expression of the two DAF genes in tissues of the wild‐type and a strain of knockout mouse whose GPI‐DAF gene has been inactivated. By fluorescence‐activated cell sorting (FACS) analysis, we found that DAF protein is present on the wild‐type mouse erythrocytes and lymphocytes but no signal was detectable on the same cells of GPI‐DAF gene knockout mice. Both T and B lymphocytes and splenic macrophages express the GPI‐DAF gene but the expression level is higher on B lymphocytes than on T lymphocytes. Within the T cell population, both CD4+ and CD8+ T cells are positive. DAF protein was detected by immunohistochemistry at high levels on wild‐type mouse spermatids and mature sperm. In contrast, only mature sperm stained positive in the GPI‐DAF gene knockout mouse testis, suggesting that GPI‐DAF but not the TM‐DAF gene is expressed on spermatids. Examination of the fetoplacental unit at the day 7·5 stage revealed that GPI‐DAF but not the TM‐DAF gene is expressed in the maternal decidua cells surrounding the trophoectoderm of the embryo. No DAF expression was detected on trophoblast or the embryo proper. These findings suggest that although the TM‐DAF gene is irrelevant on mouse blood cells, the two DAF genes may have different roles in germ cell development and/or mature sperm function. Because complement receptor 1‐related gene/protein y (Crry) has been shown to be expressed on early mouse embryos, the complete lack of GPI‐DAF and TM‐DAF gene expression in early mouse development may explain the observed sensitivity of Crry‐deficient embryos to maternal complement attack.
Enhancement of stromal cell‐derived factor‐1α‐induced chemotaxis for CD4/8 double‐positive thymocytes by fibronectin and laminin in mice
Authors: Yanagawa Yoshiki , Iwabuchi Kazuya , Onoé Kazunori 
Published: March 2003

SummaryStromal cell‐derived factor‐1α (SDF‐1α) is a chemokine abundantly expressed in the thymus. However, a potential role of SDF‐1α in the thymus has been under consideration, since no appreciable difference was detected in the migratory responsiveness to the SDF‐1α between cortical and medullary thymocytes. In the present study, we examined the effects of extracellular matrix (ECM) on the responsiveness of murine thymocytes to several chemokines including SDF‐1α. In the absence of ECM, chemotactic activity of SDF‐1α for cortical (CD4/8 double‐positive) thymocytes was almost same as that for medullary (CD4 or CD8 single‐positive) thymocytes. In contrast, the chemotactic activity of SDF‐1α for cortical thymocytes was considerably (more than 10‐fold) enhanced by laminin or fibronectin as compared with that for medullary thymocytes. Chemotactic activities of macrophage‐derived chemokine and macrophage inflammatory protein‐3β for both cortical and medullary thymocytes were only slightly enhanced by fibronectin or laminin. Thus, fibronectin and laminin appear to enhance the chemotactic activity of SDF‐1α for cortical thymocytes selectively. Addition of a monoclonal antibody against CD29 showed no inhibitory effect on the enhanced chemotactic activity of SDF‐1α, suggesting that the other unknown receptor(s) is involved in this enhancement. Our present data demonstrate that SDF‐1α in the presence of fibronectin or laminin is involved in the distribution of developing thymocytes.
Impaired germinal centre formation and humoral immune response in the absence of CD28 and interleukin‐4
Authors: Reiter Rudolph , Pfeffer Klaus 
Published: March 2003

SummaryThe generation of an optimal humoral immune response requires fully activated T‐cells. For complete activation at least two signals are needed. The first one is an antigen dependent one via the T cell receptor, the second one is a costimulatory signal which can be delivered by the CD28 molecule after binding to CD80 (B7.1) or CD86 (B7.2). Fully activated T helper cells are competent to deliver help to B‐cells by secreting cytokines (e.g. interleukin (IL)‐4) or up‐regulating CD40 ligand for proliferation and differentiation of B cells. These interactions mainly take place in germinal centres (GC) that arise after antigen stimulation in B cell‐follicles of peripheral lymphatic tissues and are the sites of massive B‐cell proliferation, affinity maturation and class switch. The roles of CD28 and IL‐4 were investigated in GC formation and antibody production. A markedly diminished humoral immune response was observed in IL‐4−/−×CD28−/− mice whereas in CD28−/− and IL‐4−/− mice the defect was less severe. Especially the formation of germinal centres was significantly reduced in CD28−/− or IL‐4−/− mice and almost undetectable in IL‐4−/−×CD28−/− mice. Taken together these data indicate that CD28 and IL‐4 are synergistically involved in GC formation and immunoglobulin production.
Limitations of HLA‐transgenic mice in presentation of HLA‐restricted cytotoxic T‐cell epitopes from endogenously processed human papillomavirus type 16 E7 protein
Authors: Street Michael D. , Doan Tracy , Herd Karen A. , Tindle Robert W. 
Published: March 2003

SummaryWe investigated the use of mice transgenic for human leucocyte antigen (HLA) A*0201 antigen‐binding domains to test vaccines composed of defined HLA A*0201‐restricted cytotoxic T‐lymphocyte (CTL) epitopes of human papillomavirus (HPV) type 16 E7 oncoprotein. HPV is detected in >90% of cervical carcinomas. HPV16 E7 oncoprotein transforms cells of the uterine cervix and functions as a tumour‐associated antigen to which immunotherapeutic strategies may be directed. We report that although the HLA A*0201 E7 epitope peptides function both to prime for E7 CTL responses, and to sensitize target cells for E7‐directed CTL killing in situations where antigen processing is not required, the epitopes are not processed out of either endogenously expressed or immunization‐introduced E7, by the mouse antigen‐processing and presentation machinery. Thus (1) CTL induced by HLA A*0201 peptide immunization killed E7 peptide‐pulsed target cells, but did not kill target cells expressing whole E7; (2) immunization with whole E7 protein did not elicit CTL directed to HLA A*0201‐restricted E7 CTL epitopes; (3) HLA A*0201‐restricted CTL epitopes expressed in the context of a DNA polytope vaccine did not activate E7‐specific T cells either in ‘conventional’ HLA A*0201 transgenic (A2.1Kb) mice, or in HHD transgenic mice in which expression of endogenous H‐2 class 1 is precluded; and (4) HLA A*0201 E7 peptide epitope immunization was incapable of preventing the growth of an HLA A*0201‐ and E7‐expressing tumour. There are generic implications for the universal applicability of HLA‐class 1 transgenic mice for studies of human CTL epitope presentation in murine models of human infectious disease where recognition of endogenously processed antigen is necessary. There are also specific implications for the use of HLA A2 transgenic mice for the development of E7‐based therapeutic vaccines for cervical cancer.
Interleukin‐6 promotes the production of interleukin‐4 and interleukin‐5 by interleukin‐2‐dependent and ‐independent mechanisms in freshly isolated human T cells
Authors: Heijink Irene H. , Vellenga Edo , Borger Peter , Postma Dirkje S. , De Monchy Jan G. R. , Kauffman Henk F. 
Published: March 2003

SummaryT helper 2 (Th2) cytokines [interleukin (IL)‐4 and IL‐5] play a central role in the development of allergic immune responses. After allergen provocation, the expression of Th2 cytokines is rapidly up‐regulated in atopy and asthma. IL‐6 is a multifunctional cytokine that is able to direct Th2 immune responses and is secreted by multiple tissue cell types. This study shows that IL‐6 induces up‐regulation of IL‐4 and IL‐5 after short (5 min) preincubation periods in freshly isolated, α‐CD3/α‐CD28‐stimulated T cells. After longer preincubation periods with IL‐6 (12 and 24 hr), the priming effect on IL‐4 production gradually disappears, whereas the effect on IL‐5 becomes more pronounced. In contrast, a small but significant inhibitory effect is found on the production of the Th1 cytokine interferon‐γ. Additional experiments indicate that the long‐term priming effect of IL‐6 on IL‐5 production is dependent on IL‐2 signalling. This is not the case for the short‐term IL‐6 effect on IL‐5 secretion, where the p38 mitogen‐activated protein kinase‐dependent induction of activator protein‐1 DNA‐binding activity is involved, independent of signal transducer and activator of transcription 3 phosphorylation. In summary, these data demonstrate that the short‐term and long‐term priming effects of IL‐6 on Th2 cytokine production are regulated by different mechanisms.
Tumour necrosis factor‐α but not lipopolysaccharide enhances preference of murine dendritic cells for Th2 differentiation
Authors: Kikuchi Kazuhiro , Yanagawa Yoshiki , Aranami Toshimasa , Iwabuchi Chikako , Iwabuchi Kazuya , Onoé Kazunori 
Published: March 2003

SummaryUsing murine spleen‐derived dendritic cells (DC) and DO11.10 T cells specific for ovalbumin (OVA), the influences of maturational condition and antigen dose on the capability of DC to induce helper T‐cell (Th) differentiation were analysed. Immature DC (iDC) with high‐ or low‐dose OVA323–339 predominantly induced Th1 or Th2 responses in DO11.10 T cells, respectively. DC matured by tumour necrosis factor‐α (TNF/DC) induced a significantly higher Th2 response in the presence of low‐dose OVA323–339 than iDC and DC matured by lipopolysaccharide (LPS) (LPS/DC). In the presence of high‐dose OVA323–339, LPS/DC induced significantly lower levels of Th1 response than iDC. Under these conditions no difference in the Th1 response was noted between TNF/DC and iDC. The enhanced capability of TNF/DC with a low‐dose antigen for Th2 polarization and the decreased preference of LPS/DC with a high‐dose antigen to Th1 polarization were not related to the amount of IL‐12 produced in these cultures. These results demonstrate for the first time that TNF/DC with a low‐dose antigen are potent inducers of Th2 differentiation.
A parallel signal‐transduction pathway for eotaxin‐ and interleukin‐5‐induced eosinophil shape change
Authors: Choi Eun Nam , Choi Moon Kyung , Park Choon‐Sik , Chung Il Yup 
Published: March 2003

SummaryInterleukin‐5 (IL‐5) and eotaxin are the most important cytokines/chemokines responsible for regulating eosinophil locomotion and are known to play a co‐operative role in the selective recruitment of eosinophils to inflamed tissues. Following exposure to chemoattractants, eosinophils undergo a series of events, including reorganization of actin filaments and subsequent rapid shape changes, culminating in chemotaxis. In this study we examined the signalling pathways for eosinophil shape change regulated by eotaxin and IL‐5, primarily using a gated autofluorescence/forward‐scatter assay. Eotaxin and IL‐5 were able to elicit shape change with peaks at 10 and 60 min, respectively, and IL‐5 triggered the shape change more efficiently than eotaxin. The pharmacological inhibitors of mitogen‐activated protein kinase (MAP kinase) and p38 blocked both eotaxin‐ and IL‐5‐induced eosinophil shape change in a dose‐dependent manner. In addition, depletion of intracellular Ca2+ and inhibition of protein kinase A (PKA) strongly reduced eosinophil shape change. In contrast, even when used at high concentrations, protein tyrosine kinase (PTK) inhibitors caused only a slight reduction in the ability to change shape. However, treatment with protein kinase C (PKC) inhibitors, such as GF109203X and staurosporine, resulted in a striking inhibition of eosinophil shape change by IL‐5, but not eotaxin. Data from the inhibition of activation and chemotaxis of the extracellular signal‐regulated kinases (ERK1/2) by the PKC inhibitors were also consistent with findings from the experiments on shape change. Collectively, two eosinophil‐selective cytokines/chemokines probably regulate eosinophil shape change via a largely overlapping signalling pathway, with involvement of PKC restricted to the IL‐5 signal alone.
A knowledge‐focused perspective on the diffusion and adoption of complex information technologies: the BPR example
Authors: Newell S. , Swan J. A. , Galliers R. D. 
Published: March 2003

Abstract.This paper presents a knowledge‐focused perspective for the development of a model to explain the diffusion and adoption of complex integrating technologies. Business process re‐engineering (BPR) is used as the example to illustrate the model. However, while BPR is used to illustrate our argument, the model that is developed is relevant to understanding the innovation processes surrounding any complex IT‐based innovation. It is argued that the strength of this diffusion model is that it focuses not on the spread of particular technological artifacts (whether it is BPR or any other IT‐based innovation), but on the spread of the ideas and knowledge underpinning the technology. In particular, the model draws attention to the ways in which technology suppliers commodify knowledge and present ‘packaged’ solutions. This creates problems for potential users who need to unpack this knowledge and integrate it with existing organizational knowledge. The diffusion and adoption of innovations is thus seen as a process of integrating knowledge across disparate communities. Such knowledge integration, however, is difficult. This can help to explain the apparent contradiction between the limited success rate of BPR and its widespread diffusion among western firms.
The mosquito dihydrofolate reductase amplicon contains a truncated synaptic vesicle protein gene
Authors: Wang Z. H. , Fallon A. M. 
Published: March 2003

AbstractWhen maintained under continuous selection with the folate inhibitor, methotrexate, cultured Aedes albopictus mosquito cells amplify an ∼200 kb region of DNA containing the dihydrofolate reductase gene. To determine whether the amplicon contained additional coding regions, Southern blots of cosmid clones containing amplicon DNA were probed separately with reverse‐transcribed mRNA from methotrexate‐sensitive and methotrexate‐resistant cells. Cosmid pWED118 contained five EcoRI fragments (A, B, C, F, G) ranging in size from 2 to 5 kb that hybridized with cDNA from resistant cells. Of these, fragments B and F also hybridized to probe representing mRNA from sensitive cells, and all but fragment G hybridized to repetitive DNA from wild‐type cells. Fragment G, which appeared to encode a low copy number gene in wild‐type cells that subsequently became part of the dihydrofolate reductase amplicon in methotrexate‐resistant cells, hybridized strongly to a 7 kb band and more weakly to bands measuring 9 and 3 kb on Northern blots containing RNA from resistant cells. Fragment G contained a 1203 bp open reading frame, encoding 401 amino acids homologous to synaptic vesicle protein SV2, a member of a transmembrane transporter family expressed in neural and endocrine cells. The region of homology included the six N‐terminal transmembrane domains, an internal cytoplasmic loop, a seventh transmembrane domain, and most of an intravesicular loop. This partial sequence, which appears to correspond to a truncated gene generated during formation of the dihydrofolate reductase amplicon, provides a useful basis for more extensive characterization of an important gene family that may be the target of novel insecticides.
Genetic variation within a parthenogenetic lineage
Authors: Lushai G. , De Barro P. J. , David O. , Sherratt T. N. , Maclean N. 
Published: March 2003

AbstractA clone of the grain aphid Sitobion avenae F. was maintained parthenogenetically over thirty‐two generations (n= 344) in a constant environment: a new generation being set up by a female selected at random from the preceding generation. Genomic DNA from individual aphids was screened for genetic stability using RAPD‐PCR with a previously tested ten‐mer primer. A putative germ‐line mutation was noted in generation 14 and somatic mutations were noted in generations 12, 25, 27 and 29. There were no differences in the RAPD‐PCR profiles of winged and wingless morphs and samples tested for symbiotic DNA. No endobiotic fungal organism was associated with the clone. Southern blotting and hybridization studies indicated that band additions were of aphid origin. However, the RAPD‐PCR profiles of the germ‐line and somatic mutation samples were unique from other aphid clones cultured during the experimental period. This paper documents discernible genetic changes occurring within an animal clonal lineage over time and impacts on the consequences this may have for clonal systems.
An estimate of phylogenetic relationships among culicine mosquitoes using a restriction map of the rDNA cistron
Authors: Kumar A. , Black W. C. , Rai K. S. 
Published: March 2003

AbstractRestriction maps of the rDNA cistron of twelve species of mosquitoes in six genera of the subfamily Culicinae were constructed using eight 6 bp recognition restriction enzymes. Anopheles albimanus was used as an outgroup. The size of the rDNA cistron ranged from 8.5 kb in Aedes katherinensis to 12.9 kb in Ae. polynesiensis. A total of twenty‐six sites were scored; eighteen were polymorphic among ingroup taxa. The proportion of polymorphic nucleotide sites (Pnuc) was 0.059 and the heterozygosity per nucleotide site (Hnuc) was 0.028. Wagner and Fitch Parsimony, Dollo Parsimony and Nei‐Li distance/neighbour‐joining methods were used to construct phylogenetic trees. The rDNA RFLP dataset did not provide a well‐supported phylogeny among culicine taxa. The RFLP phylogenies are incongruent with the morphology character based and molecular phylogenies and derived relationships did not correspond with current taxonomic classifications. The lack of resolution was due to homoplasy arising from frequent independent loss or gain of restriction sites among unrelated taxa.
The Queensland fruit fly, Bactrocera tryoni, contains multiple members of the hAT family of transposable elements
Authors: Pinkerton A. C. , Whyard S. , Mende H. A. , Coates C. J. , O’Brochta D. A. , Atkinson P. W. 
Published: March 2003

AbstractMembers of the hAT transposable element family are mobile in non‐host insect species and have been used as transformation vectors in some of these species. We report that the Queensland fruit fly, Bactrocera tryoni, contains at least two types of insect hAT elements called Homer and a Homer‐like element (HLE). The Homer element is 3789 bp in size and contains 12‐bp imperfect inverted terminal repeats. The Homer element contains a long open reading frame (ORF) that encodes a putative transposase. Three different copies of this long ORF were recovered from the B. tryoni genome and, upon transcription and translation in an in vitro system, all produced transposase. The HLE is an incomplete element since no 3′ inverted terminal repeat (ITR) was found. Homer and the HLE are as related to one another as either is to the other insect hAT elements such as Hermes, hobo, hermit and hopper. The structure and distribution of these two Homer elements is described.