bluuebunny/crossref_metadata_2025 huggingface dataset:
Neogenesis of cerebellar Purkinje neurons from gene-marked bone marrow cells in vivo
Authors: Priller Josef , Persons Derek A. , Klett Francisco F. , Kempermann Gerd , Kreutzberg Georg W. , Dirnagl Ulrich
Published: July 2002

The versatility of stem cells has only recently been fully recognized. There is evidence that upon adoptive bone marrow (BM) transplantation (BMT), donor-derived cells can give rise to neuronal phenotypes in the brains of recipient mice. Yet only few cells with the characteristic shape of neurons were detected 1–6 mo post-BMT using transgenic or newborn mutant mice. To evaluate the potential of BM to generate mature neurons in adult C57BL/6 mice, we transferred the enhanced green fluorescent protein (GFP) gene into BM cells using a murine stem cell virus-based retroviral vector. Stable and high level long-term GFP expression was observed in mice transplanted with the transduced BM. Engraftment of GFP-expressing cells in the brain was monitored by intravital microscopy. In a long-term follow up of 15 mo post-BMT, fully developed Purkinje neurons were found to express GFP in both cerebellar hemispheres and in all chimeric mice. GFP-positive Purkinje cells were also detected in BM chimeras from transgenic mice that ubiquitously express GFP. Based on morphologic criteria and the expression of glutamic acid decarboxylase, the newly generated Purkinje cells were functional.
Selective cytotoxicity of intracellular amyloid β peptide1–42 through p53 and Bax in cultured primary human neurons
Authors: Zhang Yan , McLaughlin Richard , Goodyer Cynthia , LeBlanc Andréa
Published: July 2002

Extracellular amyloid β peptides (Aβs) have long been thought to be a primary cause of Alzheimer's disease (AD). Now, detection of intracellular neuronal Aβ1–42 accumulation before extracellular Aβ deposits questions the relevance of intracellular peptides in AD. In the present study, we directly address whether intracellular Aβ is toxic to human neurons. Microinjections of Aβ1–42 peptide or a cDNA-expressing cytosolic Aβ1–42 rapidly induces cell death of primary human neurons. In contrast, Aβ1–40, Aβ40–1, or Aβ42–1 peptides, and cDNAs expressing cytosolic Aβ1–40 or secreted Aβ1–42 and Aβ1–40, are not toxic. As little as a 1-pM concentration or 1500 molecules/cell of Aβ1–42 peptides is neurotoxic. The nonfibrillized and fibrillized Aβ1–42 peptides are equally toxic. In contrast, Aβ1–42 peptides are not toxic to human primary astrocytes, neuronal, and nonneuronal cell lines. Inhibition of de novo protein synthesis protects against Aβ1–42 toxicity, indicating that programmed cell death is involved. Bcl-2, Bax-neutralizing antibodies, cDNA expression of a p53R273H dominant negative mutant, and caspase inhibitors prevent Aβ1–42-mediated human neuronal cell death. Taken together, our data directly demonstrate that intracellular Aβ1–42 is selectively cytotoxic to human neurons through the p53–Bax cell death pathway.
The Single Positive T Cells Found in CD3-ζ/η−/− Mice Overtly React with Self–Major Histocompatibility Complex Molecules upon Restoration of Normal Surface Density of T Cell Receptor–CD3 Complex
Authors: Lin Shih-Yao , Ardouin Laurence , Gillet Anne , Malissen Marie , Malissen Bernard
Published: July 2002

CD3-ζ/η–deficient mice have small thymuses containing cells that show a profound reduction in the surface levels of T cell receptors and terminate their differentiation at the CD4+CD8+ stage. Rather unexpectedly, CD3− or very low single positive T cells accumulate over time in the spleen and lymph nodes of CD3-ζ/η–deficient mice after a process dependent on MHC expression. Fusion of these peripheral T cells with a CD3-ζ–positive derivative of the BW5147 TCR-α−/β− thymoma resulted in hybridomas that do express an heterogeneous set of T cell receptor α/β dimers at their surface and at density comparable to those found in hybridomas derived from wild-type peripheral T cells. We have investigated the specificities of these T cell receptors using spleen cells from congenic and mutant mouse strains, and showed that the majority of them readily recognized self-MHC class I or class II molecules. These results demonstrate that by increasing the density and/or output of the T cell receptors expressed in peripheral T cells, one can confer them with the capacity to respond to normal density of self-MHC molecules.
Crucial Role of Interferon Consensus Sequence Binding Protein, but neither of Interferon Regulatory Factor 1 nor of Nitric Oxide Synthesis for Protection Against Murine Listeriosis
Authors: Fehr Thomas , Schoedon Gabriele , Odermatt Bernhard , Holtschke Thomas , Schneemann Markus , Bachmann Martin F. , Mak Tak W. , Horak Ivan , Zinkernagel Rolf M.
Published: July 2002

Listeria monocytogenes is widely used as a model to study immune responses against intracellular bacteria. It has been shown that neutrophils and macrophages play an important role to restrict bacterial replication in the early phase of primary infection in mice, and that the cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) are essential for protection. However, the involved signaling pathways and effector mechanisms are still poorly understood. This study investigated mouse strains deficient for the IFN-dependent transcription factors interferon consensus sequence binding protein (ICSBP), interferon regulatory factor (IRF)1 or 2 for their capacity to eliminate Listeria in vivo and in vitro and for production of inducible reactive nitrogen intermediates (RNI) or reactive oxygen intermediates (ROI) in macrophages. ICSBP−/− and to a lesser degree also IRF2−/− mice were highly susceptible to Listeria infection. This correlated with impaired elimination of Listeria from infected peritoneal macrophage (PEM) cultures stimulated with IFN-γ in vitro; in addition these cultures showed reduced and delayed oxidative burst upon IFN-γ stimulation, whereas nitric oxide production was normal. In contrast, mice deficient for IRF1 were not able to produce nitric oxide, but they efficiently controlled Listeria in vivo and in vitro. These results indicate that (a) the ICSBP/IRF2 complex is essential for IFN-γ–mediated protection against Listeria and that (b) ROI together with additional still unknown effector mechanisms may be responsible for the anti-Listeria activity of macrophages, whereas IRF1-induced RNI are not limiting.
RAFTK, a Novel Member of the Focal Adhesion Kinase Family, Is Phosphorylated and Associates with Signaling Molecules upon Activation of Mature T Lymphocytes
Authors: Ganju Ramesh K. , Hatch William C. , Avraham Hava , Ona Mel A. , Druker Brian , Avraham Shalom , Groopman Jerome E.
Published: July 2002

The related adhesion focal tyrosine kinase (RAFTK), a recently discovered member of the focal adhesion kinase family, has previously been reported to participate in signal transduction in neuronal cells, megakaryocytes, and B lymphocytes. We have found that RAFTK is constitutively expressed in human T cells and is rapidly phosphorylated upon the activation of the T cell receptor (TCR). This activation also results in an increase in the autophosphorylation and kinase activity of RAFTK. After its stimulation, there was an increase in the association of the src cytoplasmic tyrosine kinase Fyn and the adapter protein Grb2. This association was mediated through the SH2 domains of Fyn and Grb2. RAFTK also co-immunoprecipitates with the SH2 domain of Lck and with the cytoskeletal protein paxillin through its COOH-terminal proline-rich domain. The tyrosine phosphorylation of RAFTK after T cell receptor-mediated stimulation was reduced by the pretreatment of cells with cytochalasin D, suggesting the role of the cytoskeleton in this process. These observations indicate that RAFTK participates in T cell receptor signaling and may act to link signals from the cell surface to the cytoskeleton and thereby affect the host immune response.
The Cytolytically Inactive Terminal Complement Complex Activates Endothelial Cells to Express Adhesion Molecules and Tissue Factor Procoagulant Activity
Authors: Tedesco Francesco , Pausa Mario , Nardon Ermanno , Introna Martino , Mantovani Alberto , Dobrina Aldo
Published: July 2002

The membrane attack complex of complement (C) in sublytic concentrations stimulates endothelial cells (EC) to express adhesion molecules and to release biologically active products. We have examined the ability of a cytolytically inactive form of this complex, which is incapable of inserting into the cell membrane, to upregulate the expression of adhesion molecules and of tissue factor (TF) procoagulant activity. The inactive terminal C complex (iTCC) was prepared by mixing C5b6, C7, C8, and C9 and was purified by fast protein liquid chromatography on a Superose 12 column. Binding of this complex to EC was found to be dose dependent and was inhibited by anti-C9 antibodies, as assessed both by ELISA using an mAb anti-C9 neoantigen and by measuring cell-bound 125I-labeled iTCC. Exposure of EC to iTCC resulted in a dose- and time-dependent expression of endothelial leukocyte adhesion molecule 1, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1 accompanied by increased levels of the corresponding mRNA, but not in the rapid expression of P-selectin. Inactive TCC also induced increased TF activity evaluated by a chromogenic assay that measures the formation of factor Xa. These effects were inhibited by anti-C9 antibodies. The data support the conclusion that iTCC may induce proinflammatory and procoagulant activities on EC.
Tolerance Induction and Autoimmune Encephalomyelitis Amelioration After Administration of Myelin Basic Protein–derived Peptide
Authors: Marusic Suzana , Tonegawa Susumu
Published: July 2002

Experimental autoimmune encephalomyelitis (EAE), a demyelinating disease of the central nervous system, is an animal model of paralyzing human disease, multiple sclerosis. EAE is readily induced by immunization with myelin basic protein (MBP) in mice transgenic for an αβ T cell receptor (TCR) that is specific for MBP. Subcutaneous injection of p17 (a peptide consisting of 17 NH2-terminal aminoacids of MBP) in complete Freund's adjuvant (CFA) causes paralysis. Induction of paralysis is inhibited by prior intraperitoneal injection of the same peptide in incomplete Freund's adjuvant (IFA). In addition, ongoing paralysis is ameliorated by subsequent intraperitoneal injection of p17 in IFA. Tolerance induction is equally efficient in Fas-deficient and IL-4–deficient TCR-transgenic mice, suggesting that neither activation-induced cell death nor differentiation into Th2 type cells plays a role in the tolerance induction. Tolerance induction by p17 seems to be based on reduction in the responsiveness of anti-MBP T cells, as documented by lower overall antigen-induced lymphokine production and proliferation, as well as diminished upregulation of early activation marker CD69 by tolerized T cells. We propose that continuous encounters of MBP-specific T cells with p17 play a critical role in the induction and maintenance of tolerance.
Peripheral Selection of  T Cell Repertoires: The Role of Continuous Thymus Output
Authors: Tanchot Corinne , Rocha Benedita
Published: July 2002

We investigated the role of continuous thymus output in the shaping of mature T cell repertoires by studying in vivo the survival of a single clone of mature Rag2-deficient T cell receptor (TCR) transgenic cells at different stages of activation in the absence or presence of thymus export. In the absence of thymus export, TCR-transgenic lymphocytes survived indefinitely in the peripheral pools. When new lymphocytes were produced in the thymus and migrated to the periphery, resident memory T cells were maintained in constant numbers, whereas naive and self-reactive T cells were replaced by recent thymus migrants.

This T cell renewal ensured both the efficiency of recall responses to antigens as memory T cells persisted independently of thymus output, and the capacity of the immune system to respond to new antigen stimulation as the naive T cell pool was continuously renewed. Our results also indicate that thymus export is required to control the number of self-reactive peripheral T cells that may invade the peripheral pools if thymus output fails.
Activated Complement Component 3 (C3) Is Required for Ultraviolet Induction of Immunosuppression and Antigenic Tolerance
Authors: Hammerberg Craig , Katiyar Santosh K. , Carroll Michael C. , Cooper Kevin D.
Published: July 2002

Complement component 3 (C3), a critical regulator of innate immunity, may also play a role in the regulation of cognate immunity, such as contact sensitivity responses. Because ultraviolet (UV) radiation also activates C3 in the skin, we determined whether the immunosuppressed state that results when a contact sensitizer is applied through UVB-exposed skin requires the presence and activation of C3. This question was addressed through the use of C3-deficient mice, blockade of C3 cleavage to C3b, and accelerated degradation of iC3b by soluble complement receptor 1 (sCR1). Both C3-modulated systems totally reversed the failure to induce a contact sensitivity response to dinitrofluorobenzene (DNFB) upon primary sensitization at the UV-exposed site, as well as immunologic tolerance to a second DNFB immunization through normal skin. Treatment with sCR1 reduced the infiltration of CD11b+ leukocytes into the epidermis and dermis of UV-irradiated skin but did not reverse the UV-induced depletion of epidermal class II MHC+CD11blo Langerhans cells. These data, taken together with previous results showing abrogation of locally induced UV immunosuppression by in vivo anti-CD11b treatment, suggest a novel mechanism by which ligation of the leukocyte β2 integrin, CD11b, by iC3b molecules formed from C3 activation in UV-exposed skin, modifies cutaneous CD11b+ cells such that skin antigen-presenting cells are unable to sensitize in a primary immune response, but actively induce antigenic tolerance.
Role of Dimerization of the Membrane-associated Growth Factor Kit Ligand in Juxtacrine Signaling: The Sl17H Mutation Affects Dimerization and Stability—Phenotypes in Hematopoiesis
Authors: Tajima Youichi , Huang Eric J. , Vosseller Keith , Ono Masao , Moore Malcolm A.S. , Besmer Peter
Published: July 2002

The Kit ligand (KL)/Kit receptor pair functions in hematopoiesis, gametogenesis, and melanogenesis. KL is encoded at the murine steel (Sl) locus and encodes a membrane growth factor which may be proteolytically processed to produce soluble KL. The membrane-associated form of KL is critical in mediating Kit function in vivo. Evidence for a role of cytoplasmic domain sequences of KL comes from the Sl17H mutation, a splice site mutation that replaces the cytoplasmic domain with extraneous amino acids. Using deletion mutants and the Sl17H allele, we have investigated the role of the cytoplasmic domain sequences of KL in biosynthetic processing and cell surface presentation. The normal KL protein products are processed for cell surface expression, where they form dimers. Both Sl17H and the cytoplasmic deletion mutants of KL were processed to the cell surface; however, the rate of transport and protein stability were affected by the mutations. Deletion of cytoplasmic domain sequences of KL did not affect dimerization of KL. In contrast, dimerization of the Sl17H protein was reduced substantially. In addition, we have characterized the hematopoietic cell compartment in Sl17H mutant mice. The Sl17H mutation has only minor effects on hematopoiesis. Tissue and peritoneal mast cell numbers were reduced in mutant mice as well as in myeloid progenitors. Interestingly, long-term bone marrow cultures from Sl17H mice did not sustain the long-term production of hematopoietic cells. In addition, homing of normal hematopoietic progenitors to the spleen of irradiated Sl17H/Sl17H recipient mice was diminished in transplantation experiments, providing evidence for a role of Kit in homing or lodging. These results demonstrate that the membrane forms of KL exist as homodimers on the cell surface and that dimerization may play an important role in KL/Kit-mediated juxtacrine signaling.
STAT3 Is Required for the gp130-mediated Full Activation of the c-myc Gene
Authors: Kiuchi Nobuo , Nakajima Koichi , Ichiba Makoto , Fukada Toshiyuki , Narimatsu Masahiro , Mizuno Katsunori , Hibi Masahiko , Hirano Toshio
Published: July 2002

The signal transducers and activators of transcription (STAT) family members have been implicated in regulating the growth, differentiation, and death of normal and transformed cells in response to either extracellular stimuli, including cytokines and growth factors, or intracellular tyrosine kinases. c-myc expression is coordinately regulated by multiple signals in these diverse cellular responses. We show that STAT3 mostly mediates the rapid activation of the c-myc gene upon stimulation of the interleukin (IL)-6 receptor or gp130, a signal transducing subunit of the receptor complexes for the IL-6 cytokine family. STAT3 does so most likely by binding to cis-regulatory region(s) of the c-myc gene. We show that STAT3 binds to a region overlapping with the E2F site in the c-myc promoter and this site is critical for the c-myc gene promoter– driven transcriptional activation by IL-6 or gp130 signals. This is the first identification of the linkage between a member of the STAT family and the c-myc gene activation, and also explains how the IL-6 family of cytokines is capable of inducing the expression of the c-myc gene.
Targeted Disruption of Migration Inhibitory Factor Gene Reveals Its Critical Role in Sepsis
Authors: Bozza Marcelo , Satoskar Abhay R. , Lin Guosheng , Lu Bao , Humbles Alison A. , Gerard Craig , David John R.
Published: July 2002

To study the biologic role of migration inhibitory factor (MIF), a pleiotropic cytokine, we generated a mouse strain lacking MIF by gene targeting in embryonic stem cells. Analysis of the role of MIF during sepsis showed that MIF−/− mice were resistant to the lethal effects of high dose bacterial lipopolysaccharide (LPS), or Staphylococcus aureus enterotoxin B (SEB) with d-galactosamine and had lower plasma levels of tumor necrosis factor α (TNF-α) than did wild-type mice, but normal levels of interleukin (IL)-6 and IL-10. When stimulated with LPS and interferon γ, macrophages from MIF−/− mice showed diminished production of TNF-α, normal IL-6 and IL-12, and increased production of nitric oxide. MIF−/− animals cleared gram-negative bacteria Pseudomonas aeruginosa instilled into the trachea better than did wild-type mice and had diminished neutrophil accumulation in their bronchoalveolar fluid compared to the wild-type mice. Thioglycollate elicited peritoneal exudates in uninfected MIF−/− mice, but showed normal neutrophil accumulation. Finally, the findings of enhanced resistance to P. aeruginosa and resistance to endotoxin-induced lethal shock suggest that the counteraction or neutralization of MIF may serve as an adjunct therapy in sepsis.
Targeted Gene Disruption Demonstrates That P-Selectin Glycoprotein Ligand 1 (Psgl-1) Is Required for P-Selectin–Mediated but Not E-Selectin–Mediated Neutrophil Rolling and Migration
Authors: Yang Jing , Hirata Takako , Croce Kevin , Merrill-Skoloff Glenn , Tchernychev Boris , Williams Eric , Flaumenhaft Robert , Furie Barbara C. , Furie Bruce
Published: July 2002

P-selectin glycoprotein ligand 1 (PSGL-1) is a mucin-like selectin counterreceptor that binds to P-selectin, E-selectin, and L-selectin. To determine its physiological role in cell adhesion as a mediator of leukocyte rolling and migration during inflammation, we prepared mice genetically deficient in PSGL-1 by targeted disruption of the PSGL-1 gene. The homozygous PSGL-1–deficient mouse was viable and fertile. The blood neutrophil count was modestly elevated. There was no evidence of spontaneous development of skin ulcerations or infections. Leukocyte infiltration in the chemical peritonitis model was significantly delayed. Leukocyte rolling in vivo, studied by intravital microscopy in postcapillary venules of the cremaster muscle, was markedly decreased 30 min after trauma in the PSGL-1–deficient mouse. In contrast, leukocyte rolling 2 h after tumor necrosis factor α stimulation was only modestly reduced, but blocking antibodies to E-selectin infused into the PSGL-1–deficient mouse almost completely eliminated leukocyte rolling. These results indicate that PSGL-1 is required for the early inflammatory responses but not for E-selectin–mediated responses. These kinetics are consistent with a model in which PSGL-1 is the predominant neutrophil P-selectin ligand but is not a required counterreceptor for E-selectin under in vivo physiological conditions.
Proline Residues in Cd28 and the Src Homology (Sh)3 Domain of Lck Are Required for T Cell Costimulation
Authors: Holdorf Amy D. , Green Jonathan M. , Levin Steven D. , Denny Michael F. , Straus David B. , Link Vinzenz , Changelian Paul S. , Allen Paul M. , Shaw Andrey S.
Published: July 2002

The Src family tyrosine kinases Lck and Fyn are critical for signaling via the T cell receptor. However, the exact mechanism of their activation is unknown. Recent crystal structures of Src kinases suggest that an important mechanism of kinase activation is via engagement of the Src homology (SH)3 domain by proline-containing sequences. To test this hypothesis, we identified several T cell membrane proteins that contain potential SH3 ligands. Here we demonstrate that Lck and Fyn can be activated by proline motifs in the CD28 and CD2 proteins, respectively. Supporting a role for Lck in CD28 signaling, we demonstrate that CD28 signaling in both transformed and primary T cells requires Lck as well as proline residues in CD28. These data suggest that Lck plays an essential role in CD28 costimulation.
Deficiency of the Stress Kinase P38α Results in Embryonic Lethality
Authors: Allen Melanie , Svensson Linne , Roach Marsha , Hambor John , McNeish John , Gabel Christopher A.
Published: July 2002

The mitogen-activated protein (MAP) kinase p38 is a key component of stress response pathways and the target of cytokine-suppressing antiinflammatory drugs (CSAIDs). A genetic approach was employed to inactivate the gene encoding one p38 isoform, p38α. Mice null for the p38α allele die during embryonic development. p38α1/− embryonic stem (ES) cells grown in the presence of high neomycin concentrations demonstrated conversion of the wild-type allele to a targeted allele. p38α−/− ES cells lacked p38α protein and failed to activate MAP kinase–activated protein (MAPKAP) kinase 2 in response to chemical stress inducers. In contrast, p38α1/+ ES cells and primary embryonic fibroblasts responded to stress stimuli and phosphorylated p38α, and activated MAPKAP kinase 2. After in vitro differentiation, both wild-type and p38α−/− ES cells yielded cells that expressed the interleukin 1 receptor (IL-1R). p38α1/+ but not p38α−/− IL-1R–positive cells responded to IL-1 activation to produce IL-6. Comparison of chemical-induced apoptosis processes revealed no significant difference between the p38α1/+ and p38α−/− ES cells. Therefore, these studies demonstrate that p38α is a major upstream activator of MAPKAP kinase 2 and a key component of the IL-1 signaling pathway. However, p38α does not serve an indispensable role in apoptosis.
The Role of Virus-Specific Cd8+ Cells in Liver Damage and Viral Control during Persistent Hepatitis B Virus Infection
Authors: Maini Mala K. , Boni Carolina , Lee Chun Kyon , Larrubia Juan R. , Reignat Stephanie , Ogg Graham S. , King Abigail S. , Herberg Jethro , Gilson Richard , Alisa Akeem , Williams Roger , Vergani Diego , Naoumov Nikolai V. , Ferrari Carlo , Bertoletti Antonio
Published: July 2002

Hepatitis B virus (HBV) is a noncytopathic virus, and the recognition of infected hepatocytes by HBV-specific CD8 cells has been assumed to be the central mechanism causing both liver damage and virus control. To understand the role of cytotoxic T cells in the pathogenesis of HBV infection, we used functional assays that require T cell expansion in vitro and human histocompatibility leukocyte antigen (HLA)-peptide tetramers that allow direct ex vivo quantification of circulating and liver-infiltrating HBV-specific CD8 cells. Two groups of patients with persistent HBV infection were studied: one without liver inflammation and HBV replication, the other with liver inflammation and a high level of HBV replication. Contrary to expectation, a high frequency of intrahepatic HBV-specific CD8 cells was found in the absence of hepatic immunopathology. In contrast, virus-specific T cells were more diluted among liver infiltrates in viremic patients, but their absolute number was similar because of the massive cellular infiltration. Furthermore, inhibition of HBV replication was associated with the presence of a circulating reservoir of CD8+ cells able to expand after specific virus recognition that was not detectable in highly viremic patients with liver inflammation.

These results show that in the presence of an effective HBV-specific CD8 response, inhibition of virus replication can be independent of liver damage. When the HBV-specific CD8 response is unable to control virus replication, it may contribute to liver pathology not only directly but by causing the recruitment of nonvirus-specific T cells.
Short Telomeres Result in Organismal Hypersensitivity to Ionizing Radiation in Mammals
Authors: Goytisolo Fermín A. , Samper Enrique , Martín-Caballero Juan , Finnon Paul , Herrera Eloísa , Flores Juana M. , Bouffler Simon D. , Blasco María A.
Published: July 2002

Here we show a correlation between telomere length and organismal sensitivity to ionizing radiation (IR) in mammals. In particular, fifth generation (G5) mouse telomerase RNA (mTR)−/− mice, with telomeres 40% shorter than in wild-type mice, are hypersensitive to cumulative doses of gamma rays. 60% of the irradiated G5 mTR−/− mice die of acute radiation toxicity in the gastrointestinal tract, lymphoid organs, and kidney. The affected G5 mTR−/− mice show higher chromosomal damage and greater apoptosis than similarly irradiated wild-type controls. Furthermore, we show that G5 mTR−/− mice show normal frequencies of sister chromatid exchange and normal V(D)J recombination, suggesting that short telomeres do not significantly affect the efficiency of DNA double strand break repair in mammals. The IR-sensitive phenotype of G5 mTR−/− mice suggests that telomere function is one of the determinants of radiation sensitivity of whole animals.
Natural Killer T Cell Activation Protects Mice Against Experimental Autoimmune Encephalomyelitis
Authors: Singh Avneesh K. , Wilson Michael T. , Hong Seokmann , Olivares-Villagómez Danyvid , Du Caigan , Stanic Aleksandar K. , Joyce Sebastian , Sriram Subramaniam , Koezuka Yasuhiko , Van Kaer Luc
Published: July 2002

Experimental autoimmune encephalomyelitis (EAE) serves as a prototypic model for T cell–mediated autoimmunity. Vα14 natural killer T (NKT) cells are a subset of T lymphocytes that recognize glycolipid antigens presented by the nonpolymorphic major histocompatibility complex (MHC) class I–like protein CD1d. Here, we show that activation of Vα14 NKT cells by the glycosphingolipid α-galactosylceramide (α-GalCer) protects susceptible mice against EAE. β-GalCer, which binds CD1d but is not recognized by NKT cells, failed to protect mice against EAE. Furthermore, α-GalCer was unable to protect CD1d knockout (KO) mice against EAE, indicating the requirement for an intact CD1d antigen presentation pathway. Protection of disease conferred by α-GalCer correlated with its ability to suppress myelin antigen-specific Th1 responses and/or to promote myelin antigen-specific Th2 cell responses. α-GalCer was unable to protect IL-4 KO and IL-10 KO mice against EAE, indicating a critical role for both of these cytokines. Because recognition of α-GalCer by NKT cells is phylogenetically conserved, our findings have identified NKT cells as novel target cells for treatment of inflammatory diseases of the central nervous system.
Hyper Immunoglobulin E Response in Mice with Monoclonal Populations of B and T Lymphocytes✪
Authors: de Lafaille Maria A. Curotto , Muriglan Stephanie , Sunshine Mary-Jean , Lei Ying , Kutchukhidze Nino , Furtado Gláucia C. , Wensky Allen K. , Olivares-Villagómez Danyvid , Lafaille Juan J.
Published: July 2002

A key event in the pathogenesis of allergies is the production of antibodies of the immunoglobulin (Ig)E class. In normal individuals the levels of IgE are tightly regulated, as illustrated by the low serum IgE concentration. In addition, multiple immunizations are usually required to generate detectable IgE responses in normal experimental animals. To define the parameters that regulate IgE production in vivo, we generated mice bearing monoclonal populations of B and T lymphocytes specific for influenza virus hemagglutinin (HA) and chicken ovalbumin (OVA), respectively. A single immunization of the monoclonal mice with the cross-linked OVA-HA antigen led to serum IgE levels that reached 30–200 μg/ml. This unusually high IgE response was prevented by the infusion of regulatory α/β CD4+ T cells belonging to both CD25+ and CD25− subpopulations. The regulation by the infused T cells impeded the development of fully competent OVA-specific effector/memory Th2 lymphocytes without inhibiting the initial proliferative response of T cells or promoting activation-induced cell death. Our results indicate that hyper IgE responses do not occur in normal individuals due to the presence of regulatory T cells, and imply that the induction of regulatory CD4+ T cells could be used for the prevention of atopy.
Volume-Dependent Atp-Conductive Large-Conductance Anion Channel as a Pathway for Swelling-Induced Atp Release
Authors: Sabirov Ravshan Z. , Dutta Amal K. , Okada Yasunobu
Published: July 2002

In mouse mammary C127i cells, during whole-cell clamp, osmotic cell swelling activated an anion channel current, when the phloretin-sensitive, volume-activated outwardly rectifying Cl− channel was eliminated. This current exhibited time-dependent inactivation at positive and negative voltages greater than around ±25 mV. The whole-cell current was selective for anions and sensitive to Gd3+. In on-cell patches, single-channel events appeared with a lag period of ∼15 min after a hypotonic challenge. Under isotonic conditions, cell-attached patches were silent, but patch excision led to activation of currents that consisted of multiple large-conductance unitary steps. The current displayed voltage- and time-dependent inactivation similar to that of whole-cell current. Voltage-dependent activation profile was bell-shaped with the maximum open probability at −20 to 0 mV. The channel in inside-out patches had the unitary conductance of ∼400 pS, a linear current-voltage relationship, and anion selectivity. The outward (but not inward) single-channel conductance was suppressed by extracellular ATP with an IC50 of 12.3 mM and an electric distance (δ) of 0.47, whereas the inward (but not outward) conductance was inhibited by intracellular ATP with an IC50 of 12.9 mM and δ of 0.40. Despite the open channel block by ATP, the channel was ATP-conductive with PATP/PCl of 0.09. The single-channel activity was sensitive to Gd3+, SITS, and NPPB, but insensitive to phloretin, niflumic acid, and glibenclamide. The same pharmacological pattern was found in swelling-induced ATP release. Thus, it is concluded that the volume- and voltage-dependent ATP-conductive large-conductance anion channel serves as a conductive pathway for the swelling-induced ATP release in C127i cells.
Whales and the universal completion
Authors: Buskes Gerard , van Rooij Arnoud
Published: July 2002

In this paper we introduce whales in the collection of subsets of the Boolean algebra of bands in a Dedekind complete Riesz space and employ them to give a short (and constructive) proof of the existence of universal completions for Archimedean Riesz spaces.
Essential embedding of cyclic modules in projectives
Authors: Pardo José , Asensio Pedro
Published: July 2002

Let

R
R

be a ring and

E
=
E
(

R
R

)

E = E(R_R)

its injective envelope. We show that if every simple right

R
R

-module embeds in

R
R

R_R

and every cyclic submodule of

E
R

E_R

is essentially embeddable in a projective module, then

R
R

R_R

has finite essential socle. As a consequence, we prove that if each finitely generated right

R
R

-module is essentially embeddable in a projective module, then

R
R

is a quasi-Frobenius ring. We also obtain several other applications and, among them: a) we answer affirmatively a question of Al-Huzali, Jain, and López-Permouth, by showing that a right CEP ring (i.e., a ring

R
R

such that every cyclic right module is essentially embeddable in a projective module) is always right artinian; b) we prove that if

R
R

is right FGF (i.e., any finitely generated right

R
R

-module embeds in a free module) and right CS, then

R
R

is quasi-Frobenius.
Convergence behaviour of inexact Newton methods
Authors: Morini Benedetta
Published: July 2002

In this paper we investigate local convergence properties of inexact Newton and Newton-like methods for systems of nonlinear equations. Processes with modified relative residual control are considered, and new sufficient conditions for linear convergence in an arbitrary vector norm are provided. For a special case the results are affine invariant.
Nucleosomal DNA property database.
Authors: Levitsky V G , Ponomarenko M P , Ponomarenko J V , Frolov A S , Kolchanov N A
Published: July 2002

MOTIVATION: Chromatin structure plays the crucial role in proper gene functioning. Therefore, it is very important to investigate nucleosomal DNA properties and recognize genome nucleosome positioning sequences. Nevertheless, applying different sequence analysis methods separately is insufficient for complete nucleosomal DNA description. One of the most probable reasons for that is the weakness of nucleosome positioning signals. The present paper offers a set of methods to reveal the most important nucleosomal DNA characteristics and to show a common pattern of nucleosome site properties. RESULTS: A complex approach was used to determine conformational and physicochemical properties that are most significant for nucleosome binding site description. The integrated database of nucleosomal DNA properties is compiled. This database comprises different sections for description of DNA characteristics. Revealing significant DNA characteristics allows the classification of various samples of site sequences and the generation of programs for site recognition. AVAILABILITY: The current version of the database is available at http://wwwmgs.bionet.nsc. ru/system/BDNAvideo/. C-code of the recognition program may be found in the section FEATURE. WWW-available programs for testing arbitrary sequences are accessible at http://wwwmgs.bionet.nsc. ru/Programs/bDNA/NA_bDNA.htm/. The links to the mirror site(s) can be found at http://wwwmgs.bionet.nsc.ru/mgs/links/mirrors.html+ ++.
Sequence type analysis and recombinational tests (START)
Authors: Jolley K. A. , Feil E. J. , Chan M.-S. , Maiden M. C. J.
Published: July 2002

Summary: The 32-bit Windows application START is implemented using Visual Basic and C++ and performs analyses to aid in the investigation of bacterial population structure using multilocus sequence data. These analyses include data summary, lineage assignment, and tests for recombination and selection.

Availability: START is available at http://outbreak.ceid.ox.ac.uk/software.htm.

Contact: keith.jolley@ceid.ox.ac.uk

* To whom correspondence should be addressed.
Predicting protein–protein interactions from primary

structure
Authors: Bock Joel R. , Gough David A.
Published: July 2002

Motivation: An ambitious goal of proteomics is to elucidate the structure, interactions and functions of all proteins within cells and organisms. The expectation is that this will provide a fuller appreciation of cellular processes and networks at the protein level, ultimately leading to a better understanding of disease mechanisms and suggesting new means for intervention. This paper addresses the question: can protein–protein interactions be predicted directly from primary structure and associated data? Using a diverse database of known protein interactions, a Support Vector Machine (SVM) learning system was trained to recognize and predict interactions based solely on primary structure and associated physicochemical properties.

Results: Inductive accuracy of the trained system, defined here as the percentage of correct protein interaction predictions for previously unseen test sets, averaged 80% for the ensemble of statistical experiments. Future proteomics studies may benefit from this research by proceeding directly from the automated identification of a cell’s gene products to prediction of protein interaction pairs.

Contact: dgough@bioeng.ucsd.edu

* To whom correspondence should be addressed.
A matter of bacterial life and death
Authors: Bogosian Gregg , Bourneuf Edward V
Published: July 2002

Over 50 years ago, standard microbiological methods were established for determining whether bacterial cells were dead or alive. Recently there has been a flurry of reports suggesting that bacteria may exist in an eclipsed state, escaping detection by standard methods. Whether there really is such a state is of more than academic interest, considering the implications for public health. The ensuing debate has been unusually energetic for the normally cultured community of microbiologists.
Histones H3/H4 form a tight complex with the inner nuclear membrane protein LBR and heterochromatin protein 1
Authors: Polioudaki Hara , Kourmouli Niki , Drosou Victoria , Bakou Alexandra , Theodoropoulos Panayiotis A , Singh Prim B , Giannakouros Thomas , Georgatos Spyros D
Published: July 2002

We have recently shown that heterochromatin protein 1 (HP1) interacts with the nuclear envelope in an acetylation‐dependent manner. Using purified components and in vitro assays, we now demonstrate that HP1 forms a quaternary complex with the inner nuclear membrane protein LBR and a sub‐set of core histones. This complex involves histone H3/H4 oligomers, which mediate binding of LBR to HP1 and cross‐link these two proteins that do not interact directly with each other. Consistent with previous observations, HP1 and LBR binding to core histones is strongly inhibited when H3/H4 are modified by recombinant CREB‐binding protein, revealing a new mechanism for anchoring domains of under‐acetylated chromatin to the inner nuclear membrane.
Diatom succession trends in recent sediments from Lake Baikal and their relation to atmospheric pollution and to climate change
Authors: Mackay A. W. , Flower R. J. , Kuzmina A. E. , Granina L. Z. , Rose N. L. , Appleby P. G. , Boyle J. F. , Battarbee R. W.
Published: July 2002

Recent environmental change in Lake Baikal has been attributed to anthropogenic influences on the ecosystem, especially through pollution and cultural eutrophication. These hypotheses are tested in this paper principally by diatom analyses in 20 short sediment cores. Most of the cores were collected with a new type of box corer specifically designed for use on Lake Baikal. Most cores contain a good sediment record but turbidites occur in some sediment profiles which may be best recognized using a combination of techniques, such as radiometric dating and percentage dry weight analyses. The most recent sediments, especially those in the southern basin and in the very north of Baikal, contain a record of anthropogenic contamination in the form of lead and spheroidal carbonaceous particles, which confirms that the southern basin of Baikal is most affected by atmospheric sources of pollution. However, there is no sedimentary diatom evidence indicating offshore water quality deterioration in Baikal owing to air pollution or eutrophication. Small increases in diatoms which indicate nutrient enrichment (e.g.
Stephanodiscus minutulus
,
Synedra acus
v.
radians
and
Synedra acus
v.
acus
) may reflect local eutrophication of the shallow waters close to the Selenga Delta and certain coastal sites in the southern basin near to the Baikalsk paper and pulp mill.

By using numerical techniques, Lake Baikal can be split into at least four regions on the basis of its surface sediment flora: the south, middle and north basins, and the shallow waters surrounding the Selenga Delta region. Diatom analyses reveal that the endemic flora of Lake Baikal has been constantly changing over at least the last 2000 years and that these fluctuations are probably responses to natural climatic variability. Recent sediments of Baikal may be affected by taphanomic processes (e.g. dissolution) and turbidite deposition, and these must be taken into account when interpreting the sedimentary diatom record.

The diatom flora of the lake is currently dominated by several species, such as
Aulacoseira baicalensis
,
A. islandica
,
Cyclotella minuta
and
Stephanodiscus binderanus
v.
baicalensis
. All these species, except for
C. minuta
, have become more common in the lake in approximately the last 130 years, and we hypothesize that these changes may be attributed to a number of different processes linked to an ameliorating climate after the end of the Little Ice Age. The results presented here have important implications for this recently designated World Heritage Site, with regard to future pollution controls and catchment management policies.
The pathology of multiple sclerosis and its evolution
Authors: Lassmann H.
Published: July 2002

The pathology of multiple sclerosis (MS) was defined more than a century ago as a chronic inflammatory process which is associated with widespread primary demyelination and glial scarring. In this short review we discuss controversial issues on (i) the relationship between inflammation and demyelination, (ii) the various possible mechanisms of myelin destruction, and (iii) axonal involvement in this disease. We suggest that the disease process of MS is more complex that previously believed.
Problems with primate sex ratios
Authors: Packer Craig , Collins D. Anthony , Eberly Lynn E.
Published: July 2002

Birth sex ratios of baboons in Gombe National Park, Tanzania, show an overall male bias ofca. 20%, but there is no obvious explanation for this trend. Individual females did not alter their sex ratios according to persistent levels of local resource competition. Sex ratios showed an unexpected relationship between age and rank: subordinate females had more sons when they were young; dominant females had more sons when they were old. The sex ratio of low–ranking females also varied with the severity of environmental conditions during pregnancy. Our findings suggest that mammalian sex ratios might be the product of more complex processes than is generally recognized or that sex–determining mechanisms impose sufficient constraints to prevent adaptive variation in all contexts.
Zonal organization of the mammalian main and accessory olfactory systems
Authors: Mori Kensaku , Campenhausen Harald von , Yoshihara Yoshihiro
Published: July 2002

Zonal organization is one of the characteristic features observed in both main and accessory olfactory systems. In the main olfactory system, most of the odorant receptors are classified into four groups according to their zonal expression patterns in the olfactory epithelium. Each group of odorant receptors is expressed by sensory neurons distributed within one of four circumscribed zones. Olfactory sensory neurons in a given zone of the epithelium project their axons to the glomeruli in a corresponding zone of the main olfactory bulb. Glomeruli in the same zone tend to represent similar odorant receptors having similar tuning specificity to odorants. Vomeronasal receptors (or pheromone receptors) are classified into two groups in the accessory olfactory system. Each group of receptors is expressed by vomeronasal sensory neurons in either the apical or basal zone of the vomeronasal epithelium. Sensory neurons in the apical zone project their axons to the rostral zone of the accessory olfactory bulb and form synaptic connections with mitral–tufted cells belonging to the rostral zone. Signals originated from basal zone sensory neurons are sent to mitral–tufted cells in the caudal zone of the accessory olfactory bulb. We discuss functional implications of the zonal organization in both main and accessory olfactory systems.
Genetic and environmental risks for specific language impairment in children
Authors: Bishop D. V. M.
Published: July 2002

Specific language impairment (SLI) is the term used to refer to unexplained difficulties in language acquisition in children. Over the past decade, there has been rapid growth of evidence indicating that genes play an important part in the aetiology of SLI. However, further progress in elucidating the role of genes in causing SLI is limited by our lack of understanding of the phenotype. Studies to date have been hampered by the fact that we do not know whether SLI should be treated as a discrete disorder or a continuous variable, let alone which measures should be used to identify cases, or how many subtypes there are. Recent research suggests that theoretically motivated measures of underlying processes may be better than conventional clinical diagnoses for identifying aetiologically distinct types of language impairment. There has been a tendency for researchers to embrace parsimony and look for a single cause of SLI—or in any event, to identify different subtypes, each with a different single cause. Research is reviewed that suggests that may not be a fruitful approach to SLI, and that an approach in terms of multiple risk and protective factors, which is widely adopted in medicine, is more realistic.
Ligand-dependent interaction of the glucocorticoid receptor with p53 enhances their degradation by Hdm2
Authors: Sengupta Sagar , Wasylyk Bohdan
Published: July 2002

The glucocorticoid receptor (GR) and the tumor supressor p53 mediate different stress responses. We have studied the mechanism of their mutual inhibition in normal endothelial cells (HUVEC) in response to hypoxia, a physiological stress, and mitomycin C, which damages DNA. Dexamethasone (Dex) stimulates the degradation of endogenous GR and p53 by the proteasome pathway in HUVEC under hypoxia and mitomycin C treatments, and also in hepatoma cells (HepG2) under normoxia. Dex inhibits the functions of p53 (apoptosis, Bax, and p21WAF1/CIP1 expression) and GR (PEPCK and G-6-Pase expression). Endogenous p53 and GR form a ligand-dependent trimeric complex with Hdm2 in the cytoplasm. Disruption of the p53–HDM2 interaction prevents Dex-induced ubiquitylation of GR and p53. The ubiquitylation of GR requires p53, the interaction of p53 with Hdm2, and E3 ligase activity of Hdm2. These results provide a mechanistic basis for GR and p53 acting as opposing forces in the decision between cell death and survival.