bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colonization of C57BL/6J and BALB/c Wild-Type and Knockout Mice withHelicobacter pylori: Effect of Vaccination and Implications for Innate and Acquired Immunity
Authors: Panthel Klaus , Faller Gerhard , Haas Rainer 
Published: January 2003

ABSTRACTThe gram-negative bacterial pathogenHelicobacter pyloriis a major cause of peptic ulcer disease and a risk factor for gastric cancer in humans. AdaptedH. pyloristrains, such as strain SS1, are able to infect mice and are a useful model for gastric colonization and vaccination studies. In this study we used a streptomycin-resistant derivative ofH. pyloriSS1 to analyze the colonization behavior and the success of vaccination in wild-type (wt) and various knockout mice of the BALB/c and C57BL/6J genetic backgrounds. We here report that BALB/c interleukin-4 knockout (IL-4−/−) mice are weakly overcolonized compared to the wt strain but that the IL-12−/−knockout results in a strong overcolonization (500%). Unexpectedly, in the C57BL/6J background the same knockouts behaved in diametrically opposed manners. The IL-4−/−mutation caused a 50% reduction and the IL-12−/−knockout caused a 95% reduction compared to the wt colonization rate. For C57BL/6J mice we further analyzed the IL-18−/−and Toll-like receptor 2 knockout mutations, which showed reductions to 66 and 57%, respectively, whereas mice with the IL-10−/−phenotype were hardly infected at all (5%). In contrast, the tumor necrosis factor receptor knockout (p55−/−and p55/75−/−) mice showed an overcolonization compared to the C57BL/6J wt strain. With exception of the low-level infected C57BL/6J IL-10−/−and IL-12−/−knockout mice, all knockout mutants were accessible to a prophylactic vaccination and their vaccination behavior was comparable to that of the wt strains.
Does Host Complement KillBorrelia burgdorferiwithin Ticks?
Authors: Rathinavelu Sivaprakash , Broadwater Anne , de Silva Aravinda M. 
Published: January 2003

ABSTRACTThe Lyme disease spirochete,Borrelia burgdorferi, inhabits the gut lumen of the tick vector. At this location the spirochete is exposed to host blood when a tick feeds. We report here on studies that were done with normal and complement-deficient (C3-knockout) mice to determine if the host complement system killed spirochetes within the vector. We found that spirochete numbers within feeding nymphs were not influenced by complement, most likely because host complement was inactivated within the vector. The Lyme disease outer surface protein A (OspA) vaccine is a transmission-blocking vaccine that targets spirochetes in the vector. In experiments with mice hyperimmunized with OspA, complement was not required to kill spirochetes within nymphs and to block transmission from nymphs to the vaccinated host. However, host complement did enhance the ability of OspA antibody to block larvae from acquiring spirochetes. Thus, the effects of OspA antibody on nymphal transmission and larval acquisition appear to be based on different mechanisms.
Effect of Inhibition of Extracellular Signal-Regulated Kinase 1 and 2 Pathway on Apoptosis andbcl-2Expression inHelicobacter pylori-Infected AGS Cells
Authors: Choi Il Ju , Kim Joo Sung , Kim Jung Mogg , Jung Hyun Chae , Song In Sung 
Published: January 2003

ABSTRACTHelicobacter pyloriinduces activation of mitogen-activated protein kinases (MAPKs). However, its effect onH. pylori-induced apoptosis has not been evaluated. Thus, we examined whetherH. pylori-induced extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38 MAPK activation affects gastric epithelial cell apoptosis andbcl-2family gene expression, especially in relation to thecagAstatus of anH. pyloristrain. In flow cytometric and oligonucleosome-bound DNA enzyme-linked immunosorbent assay analyses, infection withcagA+H. pyloristrains induced gastric cancer cell apoptosis in AGS cells more prominently than infection withcagAmutants. Activation of ERK1/2 and p38 MAPKs was also more prominent incagA+strains. Pretreatment with a MEK inhibitor (PD98059) inhibited ERK1/2 activation and increasedH. pylori-induced apoptosis significantly. This increased apoptosis was accompanied by decreased antiapoptoticbcl-2mRNA expression amongbcl-2-related genes (bcl-2,bax,bak,mcl-1, andbcl-XL/S), and the effect was also more prominent in thecagA+strains. However, the alteration ofbcl-2gene expression was not accompanied by protein level changes. Inhibition of p38 using specific inhibitor SB203580 decreasedH. pylori-induced apoptosis but resulted in little alteration ofbcl-2-related gene expression. In conclusion,H. pylori-induced ERK1/2 activation, especially by thecagA+H. pyloristrain, may play a protective role against gastric epithelial cell apoptosis partially through maintenance ofbcl-2gene expression.
Entamoeba histolytica
Cysteine Proteinases Disrupt the Polymeric Structure of Colonic Mucin and Alter Its Protective Function
Authors: Moncada Darcy , Keller Kathy , Chadee Kris 
Published: January 2003

ABSTRACT

The adherent mucous gel layer lining the colonic epithelium is the first line of host defense against invasive pathogens, such as
Entamoeba histolytica
. The mucous layer prevents the attachment of amoeba to the colonic epithelium by trapping and aiding in the expulsion of the parasite. Disruption of the mucous layer is thought to occur in invasive amebiasis, and the mechanism by which the parasite overcomes this barrier is not known. The aim of this study was to characterize the specific interactions occurring between
E. histolytica
secreted cysteine proteinases and colonic mucin as a model to examine the initial events of invasive amebiasis.
E. histolytica
secreted products were examined for mucinase activity utilizing mucin metabolically labeled with [
35
S]cysteine as a substrate. Cysteine proteinases degraded mucin in a time- and dose-dependent manner. A significant reduction (>50%) in high-molecular-weight mucin with altered buoyant density was observed when degraded mucin was analyzed by Sepharose 4B column chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography, and CsCl density gradient centrifugation. Mucinase activity was eliminated by the specific cysteine protease inhibitor
trans
-epoxysuccinyl-
l
-leucylamido-(4-guanidino)butane and was independent of glycosidase activity. Moreover, the degraded mucin was 38% less effective than native mucin at inhibiting amebic adherence to target epithelial cells. These results are the first to show that
E. histolytica
cysteine proteinases alter the protective function of the mucous barrier by disrupting the structure of the MUC2 polymer. Mechanistically, the parasite achieves this via proteolytic degradation of the terminal cysteine-rich domains.
DNA from Periodontopathogenic Bacteria Is Immunostimulatory for Mouse and Human Immune Cells
Authors: Nonnenmacher Claudia , Dalpke Alexander , Zimmermann Stefan , Flores-de-Jacoby Lavin , Mutters Reinier , Heeg Klaus 
Published: January 2003

ABSTRACTAlthough bacterial DNA (bDNA) containing unmethylated CpG motifs stimulates innate immune cells through Toll-like receptor 9 (TLR-9), its precise role in the pathophysiology of diseases is still equivocal. Here we examined the immunostimulatory effects of DNA extracted from periodontopathogenic bacteria. A major role in the etiology of periodontal diseases has been attributed toActinobacillus actinomycetemcomitans,Porphyromonas gingivalis, andPeptostreptococcus micros.We therefore isolated DNA from these bacteria and stimulated murine macrophages and human gingival fibroblasts (HGF) in vitro. Furthermore, HEK 293 cells transfected with human TLR-9 were also stimulated with these DNA preparations. We observed that DNA from these pathogens stimulates macrophages and gingival fibroblasts to produce tumor necrosis factor alpha and interleukin-6 in a dose-dependent manner. Methylation of the CpG motifs abolished the observed effects. Activation of HEK 293 cells expressing TLR-9 which were responsive to bDNA but not to lipopolysaccharide confirmed that immunostimulation was achieved by bDNA. In addition, the examined bDNA differed in the ability to stimulate murine macrophages, HGF, and TLR-9-transfected cells. DNA fromA. actinomycetemcomitanselicited a potent cytokine response, while DNA fromP. gingivalisandP. microsshowed lower immunostimulatory activity. Taken together, the results strongly suggest that DNA fromA. actinomycetemcomitans,P. gingivalis, andP. microspossesses immunostimulatory properties in regard to cytokine secretion by macrophages and fibroblasts. These stimulatory effects are due to unmethylated CpG motifs within bDNA and differ between distinct periodontopathogenic bacteria strains. Hence, immunostimulation by DNA fromA. actinomycetemcomitans,P. gingivalis, andP. microscould contribute to the pathogenesis of periodontal diseases.
Immunopathogenesis of Pulmonary Granulomas in the Guinea Pig after Infection withMycobacterium tuberculosis
Authors: Turner Oliver C. , Basaraba Randall J. , Orme Ian M. 
Published: January 2003

ABSTRACTPulmonary tuberculosis in guinea pigs is similar to the disease in humans and is accordingly widely used as a model to test tuberculosis vaccines. The primary site of expression of acquired immunity and the hallmark of tuberculosis is the granuloma. Granuloma morphology is well described, but there is limited information regarding T-cell subset influx. We monitored the course of pulmonary tuberculosis in guinea pigs and observed four distinct immunohistopathological stages. In all stages there were similar numbers and arrangement of CD4 and CD8 T cells. There were only small numbers of apoptotic lymphocytes, scattered around and within the necrotic core, and acid-fast bacilli were visible both within macrophages and free within airway debris. A key finding of the study was the observation that the development of the necrotic core was an early event and almost certainly preceded the emergence of the acquired immune response. This in turn suggests that innate mechanisms are the basis of the early lesions and that subsequent acquired responses are unable to moderate them. This hypothesis differs from the current dogma that excessive activity of T cells mediates delayed-type hypersensitivity and that cellular cytolysis is the root cause of the necrosis.
Phagocytosis and Intracellular Fate ofAspergillus fumigatusConidia in Alveolar Macrophages
Authors: Ibrahim-Granet O. , Philippe B. , Boleti H. , Boisvieux-Ulrich E. , Grenet D. , Stern M. , Latgé J. P. 
Published: January 2003

ABSTRACTAspergillus fumigatusis the most prevalent airborne fungal pathogen responsible for fatal invasive aspergillosis in immunocompromised patients. Upon arrival in the lung alveolus, conidia ofA. fumigatusare phagocytosed by alveolar macrophages, the major phagocytic cells of the lung. Engulfment and intracellular trafficking ofA. fumigatusconidia in alveolar macrophages of two different origins, the murine cell line MH-S and human pulmonary alveolar macrophages, were analyzed by electron microscopy and immunofluorescence. Phagocytosis ofA. fumigatusconidia required actin polymerization and phosphatidylinositol 3-kinase activity. Fusion ofA. fumigatusphagosomes with early and late endosomes was shown by immunolabeling with specific markers for the transferrin receptor, early endosome antigen, and Rab7. Maturation ofA. fumigatusphagolysosomes was monitored by using a fixable acidotropic probe, LysoTracker Red DND-99, and an anti-cathepsin D antibody. Bafilomycin A-induced inhibition of lysosomal acidification abolished the conidial killing by the macrophages. These data suggest that the maturation ofA. fumigatusphagosomes results from fusion with the compartments of the endocytic pathway and that the killing of conidia depends on phagolysosome acidification. A model for the phagocytosis ofA. fumigatusconidia by alveolar macrophages is proposed on the basis of these results.
Transposon Mutagenesis ofMycobacterium marinumIdentifies a Locus Linking Pigmentation and Intracellular Survival
Authors: Gao Lian-Yong , Groger Richard , Cox Jeffery S. , Beverley Stephen M. , Lawson Elise H. , Brown Eric J. 
Published: January 2003

ABSTRACTPathogenic mycobacteria survive and replicate within host macrophages, but the molecular mechanisms involved in this necessary step in the pathogenesis of infection are not completely understood.Mycobacterium marinumhas recently been used as a model for aspects of the pathogenesis of tuberculosis because of its close genetic relationship toMycobacterium tuberculosisand because of similarities in the pathology and course of infection caused by this organism in its natural hosts, fish and frogs, with tuberculosis in humans. In order to advance the utility of theM. marinummodel, we have developed efficient transposon mutagenesis of the organism by using aDrosophila melanogaster mariner-based transposon. To determine the efficiency of transposition, we have analyzed pigmentation mutants from the transposon mutant library. In addition to insertions in four known genes in the pathway of pigment biosynthesis, two insertions in novel genes were identified in our mutant library. One of these is in a putative inhibitor of the carotenoid biosynthesis pathway. The second unexpected insertion is in an intergenic region between two genes homologous toRv2603candRv2604cofM. tuberculosis. In addition to a pigmentation defect, this mutant showed increased susceptibility to singlet oxygen and grew poorly in murine macrophages. Complementation withM. tuberculosisgenomic DNA encompassingRv2603ctoRv2606ccorrected the pigmentation and growth defects of the mutant. These data demonstrate the utility ofmariner-based transposon mutagenesis ofM. marinumand thatM. marinumcan be used to study the function ofM. tuberculosisgenes involved in intracellular survival and replication.
Restricted Expression of Shiga Toxin Binding Sites on Mucosal Epithelium of Mouse Distal Colon
Authors: Imai Yasuyuki , Fukui Takashi , Kurohane Kohta , Miyamoto Daisei , Suzuki Yasuo , Ishikawa Tomoyuki , Ono Yousuke , Miyake Masaki 
Published: January 2003

ABSTRACTShiga toxins (Stx) are some of the major virulence factors of enterohemorrhagicEscherichia colistrains such as serotype O157:H7. To explore how Stx might initially gain access to the bloodstream from sites of infection, frozen sections of mouse colon were immunohistochemically examined for binding sites for recombinant binding subunits (Stx1B). Binding sites were selectively expressed on the epithelium in the distal half of the mouse colon, whereas the proximal half did not exhibit any binding sites. In agreement with this observation, we also demonstrated the distal-part-restricted distribution of glycolipids that bind to Stx1B in the mouse colon. For comparison, the binding sites of several control lectins were also examined. Selective binding to the distal part of the colon was not seen with any other control lectins, includingGriffonia simplicifolialectin-I isolectin B4 (GS-I-B4), which shares α-galactose specificity with Stx1B. Partial overlapping of the specificities of Stx1B and GS-I-B4 was seen by assay with globotriose-conjugated multivalent ligands. The results indicate that Stx1B is stricter in the recognition of carbohydrate determinants than GS-I-B4 when examined with biological ligands.
Epithelial Cell Surface Sites Involved in the Polyvalent Adherence of
Porphyromonas gingivalis
: a Convincing Role for Neuraminic Acid and Glucuronic Acid
Authors: Agnani G. , Tricot-Doleux S. , Houalet S. , Bonnaure-Mallet M. 
Published: January 2003

ABSTRACT

We investigated the target structures of the epithelial cells responsible for the attachment of
Porphyromonas gingivalis
by immunocytofluorimetry, enzyme-linked immunosorbent assay, and confocal microscopy. Integrins (β1, β3, and αV) and E-cadherin played no significant role. Carbohydrates (such as α
-d-
methylglucoside,
l-
fucose,
d-
and
l-
mannose,
N-
acetylglucosamine, and
N-
acetylgalactosamine) had little inhibitory effect on bacterial binding. Enzymatic treatments of the epithelial membranes and sugar competition studies showed that
N-
acetylneuraminic acid and glucuronic acid were involved in binding.
A NEW ROBUST TWO DIMENSIONAL SPECTRAL ESTIMATION BASED ON AN AR MODEL EXCITED BY A t DISTRIBUTION PROCESS AND ITS QR-DECOMPOSITION RECURSIVE ALGORITHM
Authors: SANUBARI JUNIBAKTI , TOKUDA KEIICHI 
Published: January 2003

In this paper a novel robust two dimensional spectral estimation based on an AR model is proposed. The robustness of the method is obtained by assuming that the output or the residual signals are independently and identically distributed (IID) t-processes with small; α degrees of freedom. By doing so, the effect of large amplitude residuals is reduced. To reduce the calculation burden, the optimal solution is recursively calculated by incorporating the QR-decomposition method. The optimal solution is updated each time the number of input samples grows. Simulation results show that when the excitation is Gaussian, the obtained estimate by using large and small α are comparable. On the other hand, when the excitation is impulsive, the obtained estimate after 100 by 100 pixels iterations by using small α ; i.e. α = 3; is more accurate than that obtained by using α = ∞ which is applied in the conventional least square approach. The plots of the mean square error (MSE) show that by using small α we can achieve smaller MSE's than that by using large α.
Microvoids Present in Anisotropic Mesophase Pitch, Their As-spun and Annealed Fibers
Authors: Yang Hojung , Yoon Seong-Ho , Korai Yozo , Mochida Isao , Katou Osamu 
Published: January 2003

Abstract
The sizes of free volumes in the mesophase pitches, as-spun and annealed fibers were measured by positron annihilation lifetime spectroscopy (PALS). The size of free volume increased with increasing of methyl groups in the mesogen molecules. Spinning increased the free volume while annealing after the spinning decreased it to similar value of the starting pitch.
Unusual Oxidation of Dichalcogenido Complexes of Platinum
Authors: Nagata Kazuto , Takeda Nobuhiro , Tokitoh Norihiro 
Published: January 2003

Abstract
Novel platinum complexes having an oxochalcogenido ligand such as S2O, Se2O, S2O3, and SeO3 were synthesized by the oxidation reactions of the overcrowded dichalcogenido platinum complexes [(BbtMe2P)2PtX2] (Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl; X = S, Se).
Nanoscale Palladium Cluster Immobilized on a TiO2 Surface as an Efficient Catalyst for Liquid-phase Wacker Oxidation of Higher Terminal Olefins
Authors: Choi Kwang-Min , Mizugaki Tomoo , Ebitani Kohki , Kaneda Kiyotomi 
Published: January 2003

Abstract
A Pd nanocluster immobilized on a TiO2 surface acted as an efficient catalyst for the liquid-phase Wacker oxidation of higher terminal olefins in the presence of water and CuCl2 under an O2 atmosphere.
Liquid-Liquid Micro Batch Extraction System for Rapid Separation
Authors: Sasaki Takayuki , Takamiya Koichi 
Published: January 2003

Abstract
The liquid-liquid micro batch extraction system, LMES, was developed for rapid separation of a trace amount of metal ions. The equipment is composed of three simple extraction cells for phase mixing, phase separation, and solvent collection. Separation could be completed in a single operation lasting only a minute, from solvent extraction to preparation for alpha-ray spectrometry.
Silica Gel Fabrication of [60]Fullerene Aggregates Utilizing Poly(N-vinylpyrrolidone) as a “Glue”
Authors: Asai Masayoshi , Fujita Norifumi , Shinkai Seiji 
Published: January 2003

Abstract
Sol-gel polycondensation of tetraethoxysilane in the presence of [60]fullerene/poly(N-vinylpyrrolidone) (PVP) complex yielded novel silica particles composed of [60]fullerene, PVP and thin silica layer.
The New and Efficient Synthesis of a Heptose Moiety of Spicamycin
Authors: Suzuki Tamotsu , Chida Noritaka 
Published: January 2003

Abstract
The new and efficient synthesis of 7-O-acetyl-4-azido-2,3,6-tri-O-benzyl-4-deoxy-l-glycero-α-l-manno-heptopyranosyl acetate (5), a key intermediate for the synthesis of novel anti-cancer antibiotic, spicamycin (1), starting from d-ribose is described.
Cationic Silver Nanoparticles Dispersed in Water Prepared from Insoluble Salts
Authors: Yonezawa Tetsu , Genda Hideo , Koumoto Kunihito 
Published: January 2003

Abstract
Homogeneous and uniform-sized silver nanoparticles were obtained by reduction of insoluble silver halides. As the stabilizing reagent, a small cationic thiol, thiocholine bromide, was used. Even from large crystals of silver halides, nanosized particles were obtained. Under the optimum conditions, highly monodispersed nanoparticles with relative standard deviation of less than 7% were obtained.
Recycling of ethylene propylene diene monomer (EPDM) waste. III. Processability of EPDM rubber compound containing ground EPDM vulcanizates
Authors: Jacob Ceni , Bhattacharya A. K. , Bhowmick A. K. , De P. P. , De S. K. 
Published: January 2003

AbstractThe rheological behavior of ethylene propylene diene monomer (EPDM) compounds containing ground EPDM waste (W‐EPDM) of known composition was studied by using a Monsanto processability tester in a temperature range of 90–110°C and a shear rate range of 306.7–1533.24 s−1. It is found that the shear viscosity decreases slightly with increasing W‐EPDM loading because of wall slip that results from the migration of lubricants from the W‐EPDM. The addition of W‐EPDM to raw EPDM results in a decreased die swell at all temperatures and shear rates. SEM photomicrographs of the EPDM extrudate surface show improved surface smoothness and reduced extrudate distortion when EPDM is blended with W‐EPDM. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2204–2215, 2003
Rubber–clay nanocomposite by solution blending
Authors: Pramanik Monoj , Srivastava Suneel Kumar , Samantaray Biswas Kumar , Bhowmick Anil Kumar 
Published: January 2003

AbstractEthylene vinyl acetate rubber (45% vinyl acetate content, EVA‐45) and organomodified clay (12Me‐MMT) composites were prepared by solution blending of the rubber and the clay. A combination of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy studies showed that the composites obtained are on the nanometer scale. The measurements of the dynamic mechanical properties for different compositions over a temperature range (−100 to +100°C) showed that the storage moduli of these rubber–clay nanocomposites are higher above the glass to rubber transition temperature compared to the neat rubber. The tensile strength of the nanocomposites is about 1.6 times higher than that of the EVA‐45. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2216–2220, 2003