bluuebunny/crossref_metadata_2025_split huggingface dataset:
RdgB acts to avoid chromosome fragmentation in Escherichia coli
Authors: Bradshaw Jill S. , Kuzminov Andrei 
Published: June 2003

SummaryBacterial RecA protein is required for repair of two‐strand DNA lesions that disable whole chromosomes. recA mutants are viable, suggesting a considerable cellular capacity to avoid these chromosome‐disabling lesions. recA‐dependent mutants reveal chromosomal lesion avoidance pathways. Here we characterize one such mutant, rdgB/yggV, deficient in a putative inosine/xanthosine triphosphatase, conserved throughout kingdoms of life. The rdgB recA lethality is suppressed by inactivation of endonuclease V (gpnfi) specific for DNA‐hypoxanthines/xanthines, suggesting that RdgB either intercepts improper DNA precursors dITP/dXTP or works downstream of EndoV in excision repair of incorporated hypoxathines/xanthines. We find that DNA isolated from rdgB mutants contains EndoV‐recognizable modifications, whereas DNA from nfi mutants does not, substantiating the dITP/dXTP interception by RdgB. rdgB recBC cells are inviable, whereas rdgB recF cells are healthy, suggesting that chromosomes in rdgB mutants suffer double‐strand breaks. Chromosomal fragmentation is indeed observed in rdgB recBC mutants and is suppressed in rdgB recBC nfi mutants. Thus, one way to avoid chromosomal lesions is to prevent hypoxanthine/xanthine incorporation into DNA via interception of dITP/dXTP.
Central tumour necrosis factor‐α mediates the early gastrointestinal motor disturbances induced by lipopolysaccharide in sheep
Authors: Guerrero‐Lindner E. , Castro M. , MuÑoz J. M. , Arruebo M. P. , Murillo M.D. , Buéno L. , Plaza M.A. 
Published: June 2003

AbstractCytokines are involved in fever and other symptoms of the acute phase response induced by endotoxins. The aim of this work was to study the involvement of central tumour necrosis factor‐α (TNF‐α) in the changes induced by lipopolysaccharide (LPS) on gastrointestinal (GI) motility in sheep. Body temperature and myoelectric activity of the antrum, duodenum and jejunum was recorded continuously. Intravenous (i.v.) administration of LPS (0.1 μg kg−1)‐induced hyperthermia, decreased gastrointestinal myoelectric activity and increased the frequency of the migrating motor complex (MMC). These effects started 40–50 min after LPS and lasted for 6–7 h. TNF‐α (50 and 100 ng kg−1) mimicked these effects when injected intracerebroventricularly (i.c.v.) but not i.v. Pretreatment with soluble recombinant TNF receptor (TNFR:Fc, 10 μg kg−1, i.c.v.) abolished the TNF‐induced actions and reduced those evoked by LPS. Furthermore, the effects induced by either LPS or TNF were suppressed by prior i.c.v. injection of indomethacin (100 μg kg−1). In contrast, the i.v. injections of TNFR:Fc or indomethacin were ineffective. Our data suggest that LPS disturbs GI motility in sheep through a central pathway that involves TNF‐α and prostaglandins sequentially.
Human submucosal neurones regulate intestinal epithelial cell proliferation: evidence from a novel co‐culture model
Authors: Toumi F. , Neunlist M. , Cassagnau E. , Parois S. , Laboisse C. L. , Galmiche J.‐P. , Jarry A. 
Published: June 2003

AbstractThe role of the human enteric nervous system (ENS) in the control of the intestinal epithelium organization and proliferation is unknown. To address this issue, we developed a novel co‐culture model, consisting of human submucosa containing the submucosal plexus and a human colonic epithelial monolayer. After 3 days in basal conditions (i.e. in absence of neuronal activation) epithelium disorganization and proliferation occurred. In contrast, electrical activation of submucosal neurones maintained monolayer organization and decreased cell proliferation. These effects were blocked by tetrodotoxin and a vasoactive intestinal peptide (VIP) receptor antagonist, and reproduced by VIP. In conclusion, our study suggests that the human ENS is involved in the control of epithelial cell proliferation.
Morphological characteristics and immunohistochemical detection of nicotinic acetylcholine receptors on intestinofugal afferent neurones in guinea‐pig colon
Authors: Ermilov L. G. , Miller S. M. , Schmalz P. F. , Hanani M. , Lennon V. A. , Szurszewski J. H. 
Published: June 2003

Abstract Intestinofugal afferent neurones (IFANs) provide excitatory synaptic input to abdominal prevertebral ganglion neurones. Input is greatly reduced during blockade of nicotinic acetylcholine receptors (nAChRs) in the wall of the colon, suggesting two projection pathways: a direct pathway without synaptic interruption and an indirect pathway interrupted by at least one nicotinic cholinergic synapse. This study aimed to characterize the morphology of IFANs and examine the distribution of nAChRs on them. We identified IFANs in guinea‐pig colon by retrograde labelling with fluorescent tracer DiI placed either on the lumbar colonic nerves in vitro or inferior mesenteric ganglion in vivo. Confocal laser scanning microscopy and computerized image‐processing software were used for 3D image reconstruction. Approximately 70% of identified IFANs had Dogiel type I‐like morphology, the remainder were Dogiel type II‐like. In vivo labelled IFANs were injected with Lucifer Yellow and immunostained for nAChRs using monoclonal antibody MAb35. Approximately 3% of total plasma membrane surface of IFANs with Dogiel type I morphology had MAb35‐IR. In contrast, <1% of membrane surface of IFANs with Dogiel type II morphology had MAb35‐IR. The finding that IFANs displayed immunostaining for nAChRs suggests the presence of putative nicotinic synapses.
Motility in the isolated mouse colon: migrating motor complexes, myoelectric complexes and pressure waves
Authors: Powell A. K. , Fida R. , Bywater R. A. R. 
Published: June 2003

AbstractThis study has used mechanical, together with pressure/volume recordings or electrophysiological recordings, to investigate the spontaneous activity in isolated preparations of mouse colon. In the former preparations, when not distended with fluid, spontaneous colonic migrating motor complexes (CMMCs) were observed using isotonic transducers. When the colons were distended with fluid, CMMCs continued at an increased frequency and in addition were associated temporally, with rises in intraluminal pressure and pulses of distally ejected fluid. 5‐Hydroxytryptamine (1 μmol L−1) or NG‐nitro‐l‐arginine (100 μmol L−1) increased the frequency of propulsive activity and this activity was abolished by hexamethonium (500 μmol L−1). In a second preparation, myoelectric complexes recorded from circular muscle cells in colons using intracellular microelectrodes, were found to correlate in frequency and phase with CMMCs. The experiments indicate that CMMCs are intimately related to pressure waves in the fluid‐filled viscus and the muscle membrane potential changes that have been recorded during myoelectric complexes are likely to be analogous to those occurring during fluid‐filled propulsive activity.
Modulation of oesophago‐UOS contractile reflex: effect of proximal and distal esophageal distention and swallowing
Authors: Aslam M. , Kern M. , Shaker R. 
Published: June 2003

AbstractUpper oesophageal sphincter (UOS) tone is influenced by intraoesophageal pressure events. Our aim was to test the hypothesis that UOS tone is responsive to simultaneous inhibitory and stimulatory signals originating from the oesophagus and compare effect of proximal and distal oesophageal air distention on oesophageal balloon‐stimulated UOS contraction. We studied 16 healthy volunteers, ages 19–80 years in two stages. We induced UOS contraction by distending various size balloons intraoesophageally and studied response of contracted UOS to oesophageal air distentions and swallowing. Intraoesophageal injections of 60‐ml room air resulted in UOS pressure augmentation (31%), relaxation (64%) and no effect in the remaining 5% of instances. The majority of air injections into the oesophageal segment proximal to the distended balloon were followed by relaxation of the contracted UOS, whereas, the majority of oesophageal air distentions distal to the balloon resulted in augmentation of UOS contraction (P < 0.01). Swallowing resulted in complete relaxation of the UOS. In conclusion, UOS contractile response to oesophageal balloon distention is overridden by further augmentation or relaxation as a result of oesophageal air distention and swallowing. Contractile and inhibitory responses of the contracted UOS to generalized oesophageal distention is region‐specific.
Role of abscisic acid in cadmium tolerance of rice (Oryza sativa L.) seedlings
Authors: HSU Y. T. , KAO C. H. 
Published: June 2003

ABSTRACTChanges in abscisic acid (ABA) contents in Cd‐treated rice (Oryza sativa L.) seedlings of two cultivars were investigated. On treatment with CdCl2, the ABA content rapidly increased in the leaves and roots of Cd‐tolerant cultivar (cv. Tainung 67, TNG67) but not in the Cd‐sensitive cultivar (cv. Taichung Native 1, TN1). The reduction of transpiration rate of TN1 caused by Cd was less than that of TNG67. Exogenous application of ABA reduced transpiration rate, decreased Cd content, and enhanced Cd tolerance of TN1 seedlings. Exogenous application of the ABA biosynthesis inhibitor, fluridone, reduced ABA accumulation, increased transpiration rate and Cd content, and decreased Cd tolerance of TNG67 seedlings. Fluridone effect on Cd toxicity of TNG67 seedlings was reversed by the application of ABA. The roles of endogenous ABA in Cd tolerance of rice seedlings are discussed and suggested.
Three pathogen‐inducible genes encoding lipid transfer protein from pepper are differentially activated by pathogens, abiotic, and environmental stresses*
Authors: JUNG HO WON , KIM WOONBONG , HWANG BYUNG KOOK 
Published: June 2003

ABSTRACTThe three cDNA clones, CALTPI, CALTPII, and CALTPIII, corresponding to pepper lipid transfer protein (LTP) genes were isolated from a pepper (Capsicum annuum) cDNA library from hypersensitive response (HR) lesions of leaves infected with Xanthomonas campestris pv. vesicatoria. The CALTP genes are well conserved in their coding region with 57–72% identity at the amino acid level, but display 72–83% identity at the nucleotide sequence level. The transcripts of the three CALTP genes differentially accumulated in pepper leaf, stem, and fruit tissues infected by X. campestris pv. vesicatoria, Phytophthora capsici and Colletotrichum gloeosporioides. The CALTP genes were also strongly induced in the systemic, upper leaves after immunization on lower leaves by either pathogenic or non‐pathogenic bacteria. In situ hybridization results showed that the CALTPI mRNA was localized in phloem cells of vascular tissues in pepper leaf, stem and fruit tissues after pathogen infection. CALTPI and CALTPIII genes were predominantly expressed in various pepper tissues infected by pathogens, while infection by P. capsici and C. gloeosporioides did not induce the transcription of the CALTPII gene. Ethylene, methyl jasmonate and abscisic acid induced CALTPI and III gene expression in pepper leaves. Drought, high salinity, low temperature and wounding stresses also induced the expression of the CALTPI and CALTPIII genes in a similar manner. In contrast, only high salinity induced the CALTPII expression that was not generally affected by abiotic and other environmental stimuli. When compared with each other and with LTPs from other plants, CALTPI is more distantly related than CALTPII and CALTPIII sequences, indicating that the three pepper CALTP genes represent two different classes. These results thus show that CALTPI and CALTPIII genes, although different in sequence structure, are transcriptionally activated in pepper tissues by pathogen infection as well as abiotic and environmental stresses.
Expression and Modulation of the Human Immunoglobulin A Fc Receptor (CD89) and the FcR γ Chain on Myeloid Cells in Blood and Tissue
Authors: Hamre R. , Farstad I. N. , Brandtzaeg P. , Morton H. C. 
Published: June 2003

AbstractCD89, the human immunoglobulin A (IgA) Fc receptor (FcR), is a potential target for antibody‐based therapeutics, but little is known about its expression and modulation in vivo. In this study, we examined the expression pattern of CD89 and its signalling subunit, the FcR γ chain, on circulating myeloid cells and in various tissues. Our results showed a wide tissue distribution of CD89+ cells. Thus, CD89+ cells were evident as clusters in tonsils and appendix and scattered in varying numbers in lymph nodes, kidney, liver, intestinal mucosa, bronchoalveolar lavage and peritoneal fluid. Most CD89+ cells were identified as neutrophils with high levels of CD89. A few recently emigrated macrophages (CD14low), weakly positive for CD89, were occasionally found in the tissues and more often in the peritoneal fluid. The level of CD89 on neutrophils in tissues and peripheral blood was similar, whereas on monocytes it was much lower in the tissues than in blood, and it was absent on CD14–/CD68+ intestinal lamina propria macrophages. Conversely, we detected much higher levels of the FcR γ chain in monocytes than in neutrophils, but the FcR γ chain was also downregulated in tissue macrophages as well as in in vitro‐differentiated monocyte‐derived macrophages and dendritic cells. The implications of our current findings on the biological functioning of CD89 are discussed.
Increased Expression of Soluble Cytotoxic T‐Lymphocyte‐Associated Antigen‐4 Molecule in Patients with Systemic Lupus Erythematosus
Authors: Liu M.‐F. , Wang C.‐R. , Chen P.‐C. , Fung L.‐L. 
Published: June 2003

AbstractA soluble form of cytotoxic T‐lymphocyte‐associated antigen‐4 (sCTLA‐4) was recently found and shown to possess a downregulatory function as a membrane‐bound CTLA‐4 molecule. The purpose of the study was to investigate the expression of sCTLA‐4 molecule in patients with systemic lupus erythematosus (SLE). One hundred patients with SLE and 40 age‐ and sex‐matched healthy individuals were enrolled in the study. The results showed that patients with SLE have significantly higher levels of sCTLA‐4 in sera than healthy controls (21.6 ± 12.3 ng/ml versus 5.9 ± 5.4 ng/ml, P < 0.001). Increased expression of sCTLA‐4 mRNA in peripheral blood mononuclear cells (PBMCs) was also found in SLE patients. However, we could not find a statistically significant correlation between the serum levels of sCTLA‐4 and lupus disease activities. The reported CTLA‐4 gene polymorphism in promoter region at position −318 did not affect the levels of sCTLA‐4. To the best of our knowledge, this is the first report showing that patients with SLE have increased sCTLA‐4 expression. However, the mechanism and role of increased sCTLA‐4 in the pathogenesis of SLE remains elucidated.
Egg Yolk Anti‐BfpA Antibodies as a Tool for Recognizing and Identifying Enteropathogenic Escherichia coli
Authors: De Almeida C. M. C. , Quintana‐Flores V. M. , Medina‐Acosta E. , Schriefer A. , Barral‐Netto M. , Dias da Silva W. 
Published: June 2003

AbstractEnteropathogenic Escherichia coli (EPEC) is a major aetiological agent of childhood diarrhoea in developing countries. The structural repeating protein A subunit, BfpA, found in the bundle‐forming pilus, is one of the virulent factors for EPEC pathogenesis. Recombinant BfpA in laying hens elicited sustained and vigorous antibody production. Immunoglobulin Y (IgY) anti‐BfpA antibodies were recovered from egg yolk, purified and characterized. Immunoadsorption with whole extracts of the isogenic E. coli EPEC adherence factor (EAF) strain that lacks BfpA rendered the resulting IgY preparations capable of: (a) recognizing purified or recombinant BfpA proteins in a dose‐dependent fashion; (b) blocking the colonization of HeLa cells by EPEC EAF+, in vitro; (c) specifically identifying E. coli bearing EAF+; and (d) inhibiting the growth of E. coli EAF+ but not the EAF strain. IgY anti‐BfpA is potentially useful as a specific, low‐cost immunobiological reagent to screen human faecal specimens for the presence of EPEC.
Was It There All the Time?
Authors: Bennett M. , Leanderson T. 
Published: June 2003

AbstractThe complement system is old, yet it may still have something new to teach us. For many years, research has existed which shows that C3d, in addition to its established role as an adjuvant, could have an immunosuppressive activity. Being true, it suggests that a common mechanism may be used both by organisms and by their pathogens to prevent unwanted immune responses.
Probing the Specificity of Human Myeloma Proteins with a Random Peptide Phage Library
Authors: Dybwad A. , Lambin P. , Sioud M. , Zouali M. 
Published: June 2003

AbstractHuman myeloma proteins (HMPs) from 10 patients with multiple myeloma (MM) were used to affinity‐select peptides from a random phage‐display peptide library. Binding peptides were identified for the 10 analysed antibodies (eight, immunoglobulin G (IgG), and two, immunoglobulin A (IgA)). The specificity of the binding was confirmed by competitive experiments using phages and chemically synthesized peptides. Interestingly, some phage‐displayed peptides were immuno‐selected with HMPs isolated from different patients. Sequence alignments and homology searches revealed a significant homology with human proteins (e.g. neural cell adhesion proteins) and pathogen‐derived proteins (e.g. herpes simplex virus capsid proteins). The selected peptides could be useful as targeting agents for myeloma cells expressing surface immunoglobulins.
The Use of Fluorometric Assays to Assess the Immune Response to DNA in Murine Systemic Lupus Erythematosus
Authors: Björkman L. , Reich C. F. , Pisetsky D. S. 
Published: June 2003

AbstractAntibodies to DNA (anti‐DNA) play an important role in the pathogenesis of systemic lupus erythematosus (SLE). In blood, these antibodies may exist in a free, unbound state or as part of complexes with DNA. Furthermore, circulating DNA may be either complexed or free. Because of the central role of these immunoreactants (anti‐DNA and DNA) in the disease, monitoring of their levels could provide valuable information for both clinical and investigative purposes. In these studies, we have explored the use of a DNA‐binding dye, PicoGreen, for the detection of circulating DNA, either total or immune complex bound. In addition, we have used this dye for Farr‐type antibody assays. Using autoimmune MRL/lpr mice as a model, we have shown that, while the levels of free DNA in the plasma of these mice were comparable with those of normal BALB/c mice, the amounts in complexes precipitable by ammonium sulfate were significantly greater. Furthermore, we showed that Farr assays using PicoGreen reliably detect levels of free anti‐DNA, with values correlated with anti‐DNA levels by an enzyme‐linked immunosorbent assay. Together, our results suggest that a fluorometric dye can accurately monitor DNA and anti‐DNA antibody levels in SLE and may provide important information on immunopathogenesis.
Liver Metastasis of Cancer Facilitated by Chemokine Receptor CCR6
Authors: Dellacasagrande J. , Schreurs O. J. F. , Hofgaard P. O. , Omholt H. , Steinsvoll S. , Schenck K. , Bogen B. , Dembic Z. 
Published: June 2003

AbstractWhen injected subcutaneously, mouse plasmacytoma (MOPC315) grew rapidly in situ, and metastatic cells became detectable first in the lymph nodes (LNs) and bone marrow, and later in the liver and lungs. We studied MOPC315 cell migration by tracking metastatic cells labelled with green fluorescent protein (GFP). We measured the levels of their chemokine receptor mRNA (by semiquantitative and real‐time quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR), because chemokines can regulate organ predilection of metastasis. Freshly sorted metastatic cells and tumour cell lines derived from the liver of BALB/c mice overexpressed functional CCR6 and CCR7 molecules compared with primary tumour. Preincubation with the CCR6 ligand (CCL20) induced liver‐sorted tumour cells to preferentially colonize the liver, demonstrating an association between liver metastasis and CCR6 expression in the mouse. Because the liver is a common site for metastasis, second only to draining LNs, we wished to ascertain whether this finding could be generalized, i.e. whether other cancers can use the similar mechanism of metastasis to the liver, and whether it holds true for humans. We found that CCR6 is overexpressed in small liver metastases of colon, thyroid and ovarian carcinomas compared with normal liver. Because human liver constitutively expresses CCL20, it could attract and select CCR6+ cancer cells. We suggest that chemotaxis via CCR6 might be a common mechanism by which malignant cancers metastasize to the liver. As metastasis in patients with cancer poses the biggest peril for survival, inhibition of CCR6 signalling, either during or after medical or surgical treatment, might be useful in preventing liver metastasis.
Follicular Lymphoma Cell Lines, an In Vitro Model for Antigenic Selection and Cytokine‐Mediated Growth Regulation of Germinal Centre B Cells
Authors: Eray M. , Postila V. , Eeva J. , Ripatti A. , Karjalainen‐Lindsberg M.‐L. , Knuutila S. , Andersson L. C. , Pelkonen J. 
Published: June 2003

AbstractIn the periphery, B cells differentiate in germinal centres (GCs) of secondary lymphoid organs. Isolated GC cells die quickly in vitro by apoptosis. Therefore, cell lines originating from follicular lymphomas, which are the malignant counterparts of GC B cells, would provide a stable in vitro model to study the immunobiology of GC B cells. We have established three novel human follicular lymphoma cell lines that were characterized with special reference to immunophenotypic features, response to B‐cell receptor (BCR) triggering, response to cytokines and cytokine mRNA expression. One of the cell lines, HF‐1A3, has a phenotype of a centrocyte. It expresses surface immunoglobulin G (sIgG) and dies by apoptosis following BCR cross‐linking. Co‐stimulation with interleukin‐6 (IL‐6), IL‐15 or interferon‐γ (IFN‐γ) rescues HF‐1A3 cells from BCR‐induced apoptosis. The second cell line, HF‐28, also represents phenotypically an IgG+ centrocyte. Ligation of its BCR leads to the cell‐cycle arrest at G1 instead of apoptosis. HF‐28 cells express both CD45RA and RO isoforms, which is unusual in B lymphocytes apart from plasma cells, thus suggesting a transition to plasma cell phenotype. The third cell line, HF‐4.9, which phenotypically represents an sIgM+ centroblast, responds by proliferation to BCR cross‐linking. These cell lines offer a unique in vitro model to study antigenic selection and cytokine‐mediated growth regulation of human GC B cells.
Cytokines Affect Resistance of Human Renal Tumour Cells to Complement‐Mediated Injury
Authors: Blok V. T. , Gelderman K. A. , Tijsma O. H. M. , Daha M. R. , Gorter A. 
Published: June 2003

AbstractOverexpression of membrane‐bound complement regulatory proteins (mCRPs) on tumour cells may hamper the effect of immunotherapy with complement‐activating monoclonal antibody (MoAb). Therefore, it is important to investigate whether cytokines can downregulate the expression of mCRP on tumour cells. In this study, the effect of 10 cytokines on the expression of the mCRP CD46, CD55 and CD59 and the renal tumour‐associated antigen G250/MN/CAIX on four human renal tumour cell lines and proximal tubular epithelial cells was determined by flow cytometry. In addition, it was measured whether changes in the expression of the classical pathway regulatory proteins CD55 and CD59 had an effect on C3 deposition and lysis. Interleukin‐1β (IL‐1β) consistently downregulated the expression of CD46 and CD59; IL‐4 consistently downregulated the expression of CD46 and transforming growth factor‐β1, consistently downregulated the expression of both CD46 and CD55. However, treatment with IL‐1β and IL‐4 also decreased the expression of G250/MN/CAIX. Changes in the expression of CD55 and CD59 were associated with changes in the amount of C3 deposited and the extent of complement‐mediated lysis, respectively. This suggests that clinical immunotherapy, consisting of treatment with cytokines and MoAb, may induce either up‐ or downregulation of CD55 or CD59 and thus affect the effectiveness of immunotherapy with MoAb.