bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimycin A–induced killing of HL‐60 cells: Apoptosis initiated from within mitochondria does not necessarily proceed via caspase 9
Authors: King Malcolm Anthony 
Published: January 2005

AbstractBackgroundAntimycin A (AMA) inhibits mitochondrial electron transport, collapses the mitochondrial membrane potential, and causes the production of reactive oxygen species. Previous work by me and my colleagues has demonstrated that AMA causes an array of typical apoptotic phenomena in HL‐60 cells. The hypothesis that AMA causes HL‐60 apoptosis by the intrinsic apoptotic pathway has now been tested.MethodsZ‐LEHD‐FMK and Z‐IETD‐FMK were used as specific inhibitors of the initiator caspases 9 and 8, respectively. Caspase 3 activation, DNA fragmentation, and cellular disintegration were measured by flow cytometry. Cytochrome c release, chromatin condensation, and nuclear fragmentation were measured by microscopy.ResultsAMA caused mitochondrial cytochrome c release and neither Z‐LEHD‐FMK nor Z‐IETD‐FMK inhibited that. In the absence of caspase inhibition there was a very close correlation between cytochrome c release and caspase 3 activation. Z‐LEHD‐FMK blocked caspase 3 activation but enhanced DNA fragmentation and failed to stop nuclear or cellular disintegration. Z‐IETD‐FMK also blocked caspase 3 activation but, in contrast to Z‐LEHD‐FMK, delayed DNA fragmentation and disintegration of the nucleus and the cell.ConclusionsThe hypothesis to explain AMA‐induced HL‐60 apoptosis was clearly inadequate because: (a) caspase 9 inhibition did not prevent DNA fragmentation or cell death, (b) apoptosis proceeded in the absence of caspase‐3 activation, (c) the main pathway leading to activation of the executioner caspases was by caspase‐8 activation, but caspase 8 inhibition only delayed apoptosis, and (d) activation of caspases 8 and 9 may be necessary for caspase‐3 activation. Thus, in this cell model, apoptosis triggered from within the mitochondria does not necessarily proceed by caspase 9, and caspase 3 is not critical to apoptosis. The results provide further evidence that, when parts of the apoptotic network are blocked, a cell is able to complete the program of cell death by alternate pathways. © 2005 Wiley‐Liss, Inc.
Characterization of the proximal enhancer element and transcriptional regulatory factors for murine recombination activating gene‐2
Authors: Wei Xing‐Cheng , Dohkan Jun‐ichi , Kishi Hiroyuki , Wu Chun‐Xiao , Kondo Sachiko , Muraguchi Atsushi 
Published: January 2005

AbstractRecombination‐activating gene (RAG)‐1 and RAG‐2 are essential for V(D)J recombination and are expressed specifically in lymphoid cells. We previously identified two putative enhancer elements, the proximal and distal enhancers, located at –2.6 and –8 kb, respectively, 5′ upstream of mouse RAG‐2, and characterized the distal enhancer element in detail. In this study, to characterize the proximal enhancer in vitro as well as in vivo, we first defined a 170‐bp core enhancer element within the proximal enhancer (Ep) and determined its activity in various cells. Ep conferred enhancer activity only in B‐lymphoid cell lines, but not in T‐ or non‐lymphoid cell lines. Analysis of the transgenic mice carrying an EGFP reporter gene linked with Ep revealed that Ep activated the transcription of the reporter gene in bone marrow and spleen, but not in thymus or non‐lymphoid tissues. Ep was active in both B220+IgM– and B220+IgM+ subpopulations in the bone marrow and in the B220+ subpopulation in the spleen. Using electrophoretic mobility shift assays and mutational assays, we found that Ikaros and CCAAT/enhancer binding protein cooperatively bind Ep and function as the transcription factors responsible for B cell‐specific enhancer activity. These results demonstrate the role of Ep as a cis‐regulatory enhancer element for RAG‐2‐specific expression in B‐lymphoid lineages.
The immunomodulator FTY720 interferes with effector functions of human monocyte‐derived dendritic cells
Authors: Müller Hansgeorg , Hofer Susanne , Kaneider Nicole , Neuwirt Hannes , Mosheimer Birgit , Mayer Gert , Konwalinka Günther , Heufler Christine , Tiefenthaler Martin 
Published: January 2005

AbstractThe potent immunomodulator FTY720 elicits immunosuppression via acting on sphingosine 1‐phosphate receptors (S1PR), thereby leading to an entrapment of lymphocytes in the secondary lymphoid tissue. To elucidate the potential in vitro effects of this drug on human monocyte‐derived DC, we used low nanomolar therapeutic concentrations of FTY720 and phosphorylated FTY720 (FTY720‐P) and investigated their influence on DC surface marker expression, protein levels of S1PR and DC effector functions: antigen uptake, chemotaxis, cytokine production, allostimulatory and Th‐priming capacity. We report that both FTY720 and FTY720‐P reduce chemotaxis of immature and mature DC. Mature DC generated in the presence of FTY720 or FTY720‐P showed an impaired immunostimmulatory capacity and reduced IL‐12 but increased IL‐10 production. T cells cultured in the presence of FTY720‐ or FTY720‐P‐treated DC showed an altered cytokine production profile indicating a shift from Th1 toward Th2 differentiation. In treated immature and mature DC, expression levels for two S1PR proteins, S1P1 and S1P4, were reduced. We conclude that in vitro treatment with FTY720 affects DC features that are essential for serving their role as antigen‐presenting cells. This might represent a new aspect of the overall immunosuppressive action of FTY720 and makes DC potential targets of further sphingolipid‐derived drugs.
Poxvirus semaphorin A39R inhibits phagocytosis by dendritic cells and neutrophils
Authors: Walzer Thierry , Galibert Laurent , Smedt Thibaut De 
Published: January 2005

AbstractThe poxvirus A39R protein is a member of the semaphorin family that binds to Plexin C1, a molecule expressed on neutrophils and dendritic cells (DC). We previously showed that binding of A39R to Plexin C1 induces local rearrangement of the actin cytoskeleton and inhibits integrin‐mediated adhesion, leading to cell retraction. As phagocytosis is dependent on both cytoskeleton integrity and integrin function, we tested the effect of A39R on DC and neutrophil phagocytosis. We found that A39R treatment strongly inhibits phagocytosis by DC and neutrophils in vitro in a Plexin C1‐dependent fashion. Moreover, A39R treatment inhibited the capacity of CD8α+ DC to take up apoptotic bodies in vivo. As a consequence, A39R impaired the ability of CD8α+ DC to cross‐prime CD8+ T cells ex vivo. In contrast, A39R had no effect on direct priming of CD8+ T cells by peptide‐pulsed CD8α+ DC in vitro. These results suggest that poxviruses may use semaphorin homologs as a means to evade the immune system.
Crystal structures and KIR3DL1 recognition of three immunodominant viral peptides complexed to HLA‐B*2705
Authors: Stewart‐Jones Guillame B. E. , di Gleria Kati , Kollnberger Simon , McMichael Andrew J. , Jones E. Yvonne , Bowness Paul 
Published: January 2005

AbstractWe have solved the crystal structures of three HLA‐B*2705–peptide complexes with the immunodominant viral peptides: EBV EBNA3C 258–266 (RRIYDLIEL), influenza (flu) nucleoprotein NP383–391 (SRYWAIRTR), and HIV gag 264–273 (KRWIILGLNK). Long‐term non‐progression during HIV infection has been associated with presentation by HLA‐B*2705, and T cell recognition, of the highly immunodominant KRWIILGLNK peptide. The tight hydrogen‐bonding network observed between the HLA‐B*2705 B‐pocket and the peptide P2 arginine guanadinium anchor explains why mutation of this residue during HIV infection results in loss of peptide binding, immune escape and progression to AIDS. Prominent, solvent‐exposed structures within these peptides may participate in generating T cell responses to these immunodominant epitopes. In the HLA‐B*2705 complex with flu NP383–391, the amino acid side chains of residues 4, 7 and 8 are solvent‐exposed whilst in the HIV decamer, the main‐chain bulges into the solvent around P7. Thus, HLA‐B*2705 presents viral peptides in a range of conformations. Tetrameric complexes of HLA‐B*2705 with the HIV and flu but not EBV peptides bound strongly to the killer‐Ig‐like receptor (KIR)3DL1. Substitution of EBV P8 glutamate to threonine allowed recognition by KIR3DL1. In the HLA‐B*2705–EBV structure the P8 glutamate side chain is solvent‐exposed and may inhibit KIR3DL1 binding through electrostatic forces.See accompanying Commentary: http://dx.doi.org/10.1002/eji.200425875
HLA‐B27: portraying immunodominant viral epitopes
Authors: López de Castro José A. 
Published: January 2005

AbstractAlthough the crystal structure of HLA‐B27 has been known for a long time, only recently have X‐ray diffraction studies of this molecule in complex with individual peptides become available. The report of three such structures involving viral epitopes that are immunodominant in HLA‐B27‐restricted T cell responses against influenza, Epstein‐Barr and HIV viruses significantly improves our perception of critical aspects of the immunological and pathogenetic roles of HLA‐B27, including (1) the molecular basis of its peptide‐binding specificity and how this is modulated by subtype polymorphism, (2) the relationship between the structural and the antigenic features of immunodominant viral epitopes, (3) the basis for long term non‐progression to AIDS of HIV‐infected HLA‐B27+ individuals, and (4) the structural features of microbial peptides influencing NK receptor engagement. Here, I discuss the implications of this and related studies for the relevance of HLA‐B27 in host defense and as a pathogenetic molecule in spondyloarthritis.See accompanying article: http://dx.doi.org/10.1002/eji.200425724
Persistence of chromosome aberrations following acute radiation: II, Does it matter how translocations are scored?
Authors: Tucker James D. , Cofield Jackie , Matsumoto Kyomu , Ramsey Marilyn J. , Freeman D. Carl 
Published: January 2005

AbstractChromosome breaks and rearrangements resulting from ionizing radiation can be much more complicated than many investigators thought possible some years ago. The realization that not all translocations are reciprocal, that multiway exchanges occur, and that some double‐strand breaks are not repaired prior to mitosis have all contributed to the difficulty of knowing how best to identify, record, evaluate, and report chromosome translocations. Here we describe the results of a series of experiments in which blood from two normal healthy subjects was obtained, irradiated with 137Cs γ‐rays in vitro at doses ranging from 0 (controls) to 4 Gy, and cultured. Cells from each dose group and donor were harvested at days 2, 2.5, 3, 4, 5, and 7 and evaluated for chromosome damage by simultaneously painting chromosomes 1, 2, and 4 in red and 3, 5, and 6 in green. The persistence of dicentrics, fragments, rings, insertions, and PAINT translocations are reported separately by us in this issue. In this article, we focus on translocations, characterizing the various types in detail and comparing and contrasting their persistence across all dose groups for both donors. The results indicate that the persistence of all translocation types was sufficient to be used for retrospective dosimetry, although nonreciprocal translocations exhibited diminished persistence compared to the other types. We also characterize the kinetics of the radiation dose responses of the two donors who exhibited significant differences in the induction as well as the persistence of translocations. Based on the evidence presented here, we hypothesize that these individuals differ in the recognition and repair of radiation‐induced damage as well as in cell cycle checkpoint control. Despite these differences, the temporal frequency of translocation losses at both the high and low doses was similar for both subjects. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Persistence of chromosome aberrations following acute radiation: I, PAINT translocations, dicentrics, rings, fragments, and insertions
Authors: Tucker James D. , Cofield Jackie , Matsumoto Kyomu , Ramsey Marilyn J. , Freeman D. Carl 
Published: January 2005

AbstractChromosome translocations are used to estimate the doses of radiation received following occupational or accidental exposure. Biodosimetry relies on the assumption that translocations are not cell‐lethal and persist with little or no loss over time. While translocations do exhibit substantially greater persistence than other aberration types (e.g., dicentrics), there is evidence that translocation frequencies also decline over time, at least following acute doses above 1 Gy. To the extent that translocation frequencies decline, the predicted absorbed doses will be underestimated. Yet unknown is whether translocations induced by ionizing radiation at doses below 1 Gy also show significant declines. Here we report on the persistence of translocations induced by 137Cs γ‐rays at acute doses ranging from 0.2 to 4 Gy using peripheral blood lymphocytes from two unrelated healthy male donors. Chromosome aberrations were evaluated by simultaneously painting chromosomes 1, 2, and 4 in red and 3, 5, and 6 in green in cells harvested 2–7 days following exposure and were scored using the PAINT system. Translocations were also enumerated using several other methods and these results are reported separately by us in this issue. For comparison, the persistence of dicentrics, rings, acentric fragments, and color junctions was also evaluated and showed rapid losses with time. The results from both donors provide evidence that translocation frequencies decline with time in a statistically significant manner at doses as low as 0.2–0.3 Gy. The frequency of translocations for all dose groups declined from day 2 to 7 by averages of 39% and 26% for donors 1 and 2, respectively. These data emphasize the importance of considering translocation loss in biological dosimetry long times after exposure. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Alterations in gene expression profiles and the DNA‐damage response in ionizing radiation‐exposed TK6 cells
Authors: Akerman Gregory S. , Rosenzweig Barry A. , Domon Olen E. , Tsai Chen‐An , Bishop Michelle E. , McGarrity Lynda J. , MacGregor James T. , Sistare Frank D. , Chen James J. , Morris Suzanne M. 
Published: January 2005

AbstractIdentifying genes that are differentially expressed in response to DNA damage may help elucidate markers for genetic damage and provide insight into the cellular responses to specific genotoxic agents. We utilized cDNA microarrays to develop gene expression profiles for ionizing radiation‐exposed human lymphoblastoid TK6 cells. In order to relate changes in the expression profiles to biological responses, the effects of ionizing radiation on cell viability, cloning efficiency, and micronucleus formation were measured. TK6 cells were exposed to 0.5, 1, 5, 10, and 20 Gy ionizing radiation and cultured for 4 or 24 hr. A significant (P < 0.0001) decrease in cloning efficiency was observed at all doses at 4 and 24 hr after exposure. Flow cytometry revealed significant decreases in cell viability at 24 hr in cells exposed to 5 (P < 0.001), 10 (P < 0.0001), and 20 Gy (P < 0.0001). An increase in micronucleus frequency occurred at both 4 and 24 hr at 0.5 and 1 Gy; however, insufficient binucleated cells were present for analysis at the higher doses. Gene expression profiles were developed from mRNA isolated from cells exposed to 5, 10, and 20 Gy using a 350 gene human cDNA array platform. Overall, more genes were differentially expressed at 24‐hr than at the 4‐hr time point. The genes upregulated (> 1.5‐fold) or downregulated (< 0.67‐fold) at 4 hr were those primarily involved in the cessation of the cell cycle, cellular detoxification pathways, DNA repair, and apoptosis. At 24 hr, glutathione‐associated genes were induced in addition to genes involved in apoptosis. Genes involved in cell cycle progression and mitosis were downregulated at 24 hr. Real‐time quantitative PCR was used to confirm the microarray results and to evaluate expression levels of selected genes at the low doses (0.5 and 1.0 Gy). The expression profiles reflect the cellular and molecular responses to ionizing radiation related to the recognition of DNA damage, a halt in progression through the cell cycle, activation of DNA‐repair pathways, and the promotion of apoptosis. Environ. Mol. Mutagen., 2005. Published 2005 Wiley‐Liss, Inc.
Stability and accuracy analysis of the central difference method for real‐time substructure testing
Authors: Wu B. , Bao H. , Ou J. , Tian S. 
Published: January 2005

AbstractThe central difference method (CDM) that is explicit for pseudo‐dynamic testing is also believed to be explicit for real‐time substructure testing (RST). However, to obtain the correct velocity dependent restoring force of the physical substructure being tested, the target velocity is required to be calculated as well as the displacement. The standard CDM provides only explicit target displacement but not explicit target velocity. This paper investigates the required modification of the standard central difference method when applied to RST and analyzes the stability and accuracy of the modified CDM for RST. Copyright © 2005 John Wiley & Sons, Ltd.
Dynamic structure subgrid‐scale models for large eddy simulation
Authors: Chumakov Sergei G. , Rutland Christopher J. 
Published: January 2005

AbstractLarge eddy simulation (LES) is based on separation of variable of interest into two parts—resolved and subgrid. The resolved part is obtained numerically using modified transport equation while the effect of the subgrid part is modelled using subgrid‐scale (SGS) models. In this paper we present and discuss new one‐equation LES models for SGS scalar flux, SGS scalar dissipation and SGS energy dissipation. The proposed models belong to a new family of SGS models—dynamic structure (DS) models. The DS models borrow the structure of the modelled term from the corresponding Leonard term, and a special scaling factor is then used which does not contain user‐specified constants. The models are evaluated a priori using available DNS data for a non‐reacting mixing layer and decaying isotropic turbulence; the evaluation results compare well with viscosity and similarity models. During the a priori tests, the DS models were found to perform better than dynamic viscosity and similarity models for various test‐to‐base filter size ratios and non‐symmetric filters. For a posteriori evaluation, the models are implemented into a high‐order finite‐difference code and an LES of decaying isotropic turbulence is performed. The results match the data available from the literature and DNS simulations. Copyright © 2005 John Wiley & Sons, Ltd.
Presence of neuroglobin in cultured astrocytes
Authors: Chen Xiao Qian , Qin Lu Ye , Zhang Chen Gang , Yang Li Tao , Gao Zhen , Liu Shuang , Lau Lok Ting , Fung Yin‐Wan Wendy , Greenberg David A. , Yu Albert Cheung‐Hoi 
Published: January 2005

AbstractNeuroglobin (Ngb), a recently discovered intracellular respiratory globin in neurons, may play a crucial role in oxygen homeostasis in the brain. We report preliminary findings indicating the presence of functional neuroglobin in primary cultures of cerebral cortical astrocytes. Reverse transcription real‐time polymerase chain reaction (RRT–PCR) and immunostaining confirmed such presence in cultured astrocytes isolated from newborn mouse brain. Ngb antisense treatment increased apoptosis in ischemic astrocytes. The discovery of Ngb in astrocytes may provide some insight into how oxygen homeostasis is regulated in the brain. © 2005 Wiley‐Liss, Inc.
Intermediate filament protein synemin is present in human reactive and malignant astrocytes and associates with ruffled membranes in astrocytoma cells
Authors: Jing Runfeng , Pizzolato Gianpaolo , Robson Richard M. , Gabbiani Giulio , Skalli Omar 
Published: January 2005

AbstractSynemin, a very unique type VI intermediate filament (IF) protein, exhibits alternative splice variants termed α and β. Unlike other IF proteins, synemin binds to actin‐associated proteins, including α‐actinin, vinculin, and α‐dystrobrevin. Our previous work has demonstrated the presence of synemin in differentiating astrocytes. In this study, we have examined the presence of synemin in human astrocytes under pathological conditions, using rabbit antibodies raised against the C‐terminal domain of human synemin produced in bacteria. Western blotting shows that astrocytic tumors contain greater amounts of α‐synemin than do normal brain tissues. These tumors also contain β‐synemin, which is not detectable in normal brain. Immunohistochemistry demonstrates that, while synemin is present in normal adult brain only in vascular smooth muscle cells, it is newly synthesized by reactive and neoplastic astrocytes. α‐ and β‐Synemins have also been detected by Western blotting and polymerase chain reaction in several human glioblastoma cell lines. In these cell lines, surprisingly, synemin is associated with ruffled membranes in addition to being distributed along the IF network. In ruffled membranes, synemin was found to co‐localize with α‐actinin. This unusual cellular localization for an IF protein is maintained after nocodazole‐induced perinuclear coiling of the vimentin IF network. In addition, immunoprecipitation experiments demonstrate that synemin forms a complex with α‐actinin in glioblastoma cells. Taken together with synemin localization within ruffled membranes, this finding suggests that synemin plays a role in motility of glioblastoma cells. © 2005 Wiley‐Liss, Inc.
Metabotropic P2 receptor activation regulates oligodendrocyte progenitor migration and development
Authors: Agresti C. , Meomartini M.E. , Amadio S. , Ambrosini E. , Serafini B. , Franchini L. , Volonté C. , Aloisi F. , Visentin S. 
Published: January 2005

AbstractTo gain insights into the role of purinergic receptors in oligodendrocyte development, we characterized the expression and functional activity of P2 receptors in cultured rat oligodendrocyte progenitors and investigated the effects of ATP and its breakdown products on the migration and proliferation of this immature glial cell population. Using Western blot analysis, we show that oligodendrocyte progenitors express several P2X (P2X1,2,3,4,7) and P2Y (P2Y1,2,4) receptors. Intracellular Ca2+ recording by Fura‐2 video imaging allowed to determine the rank potency order of the P2 agonists tested: ADPβS = ADP = Benzoyl ATP > ATP > ATPγS > UTP, α,β‐meATP ineffective. Based on the above findings, on pharmacological inhibition by the antagonists oxATP and MRS2179, and on the absence of α,βmeATP‐induced inward current in whole‐cell recording, P2X7 and P2Y1 were identified as the main ionotropic and metabotropic P2 receptors active in OPs. As a functional correlate of these findings, we show that ATP and, among metabotropic agonists, ADP and the P2Y1‐specific agonist ADPβS, but not UTP, induce oligodendrocyte progenitor migration. Moreover, ATP and ADP inhibited the proliferation of oligodendrocyte progenitors induced by platelet‐derived growth factor, both in purified cultures and in cerebellar tissue slices. The effects of ATP and ADP on cell migration and proliferation were prevented by the P2Y1 antagonist MRS2179. By confocal laser scanning microscopy, P2Y1 receptors were localized in NG2‐labeled oligodendrocyte progenitors in the developing rat brain. These data indicate that ATP and ADP may regulate oligodendrocyte progenitor functions by a mechanism that involves mainly activation of P2Y1 receptors. © 2005 Wiley‐Liss, Inc.