bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neisseria meningitidis
RTX Proteins Are Not Required for Virulence in Infant Rats
Authors: Forman Stanislav , Linhartova Irena , Osicka Radim , Nassif Xavier , Sebo Peter , Pelicic Vladimir 
Published: March 2003

ABSTRACT

RTX cytotoxins play an important role in virulence of numerous gram-negative pathogens. Unexpectedly, however, we show here that the RTX proteins of
Neisseria meningitidis
are dispensable for virulence in the infant rat model of infection.
Vector Priming Reduces the Immunogenicity ofSalmonella-Based Vaccines inNramp1+/+Mice
Authors: Vindurampulle Christofer J. , Attridge Stephen R. 
Published: March 2003

ABSTRACTThe present studies inNramp1−/−BALB/c andNramp1+/+CBA mice question the significance of this genotype as a determinant of the level of gut colonization following oral administration of naturally attenuated or highly virulentSalmonellastrains. In line with previous results in BALB/c hosts, vector priming of CBA mice withSalmonella entericaserovar Stanley was found to significantly compromise the immunogenicity of a recombinant construct expressing a foreign pilus protein.
Polymorphisms within EspA Filaments of Enteropathogenic and Enterohemorrhagic
Escherichia coli
Authors: Neves Bianca C. , Shaw Robert K. , Frankel Gad , Knutton Stuart 
Published: March 2003

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) and enterohemorrhagic
E
.
coli
(EHEC) possess a filamentous type III secretion system (TTSS) employed to deliver effector proteins into host cells. EspA is a type III secreted protein which forms the filamentous extension to the TTSS and which interacts with host cells during early stages of attaching and effacing (A/E) lesion formation. By immunofluorescence, a polyclonal antibody previously raised to EspA from EPEC strain E2348/69 (O127:H6) stained ∼12-nm-diameter EspA filaments produced by this strain but did not stain similar filaments produced by EHEC serotype O157:H7. Similarly, an antibody that we subsequently raised to EHEC strain 85-170 (O157:H7) EspA stained ∼12-nm-diameter EspA filaments produced by strain 85-170 but did not stain E2348/69 EspA filaments. Given such heterogeneity between EPEC and EHEC EspA filaments, we examined polymorphisms of functional EspA filaments among different EPEC and EHEC serotypes. With use of the EPEC EspA antiserum, EspA filaments were observed only with EPEC serotypes O127:H6 and O55:H6, serotypes which encode an identical EspA protein. When stained with the EHEC EspA antiserum, EspA filaments were detected only on EHEC strains belonging to serotype O157:H7; the EHEC antiserum did, however, stain EspA filaments produced by the closely related EPEC serotype O55:H7 but not filaments of any other EPEC serotype tested. Such polymorphisms among functional EspA filaments of EPEC and EHEC would be expected to have important implications for the development of broad-range EspA-based vaccines.
Expression of
Helicobacter pylori
Vacuolating Toxin in
Escherichia coli
Authors: McClain Mark S. , Cover Timothy L. 
Published: March 2003

ABSTRACT

VacA is a secreted toxin that plays a role in
Helicobacter pylori
colonization of the stomach and that contributes to the pathogenesis of peptic ulcer disease. Studies of VacA structure and function have been hindered by the lack of an efficient system for expression and genetic manipulation of this toxin. In this study, we developed methodology for expression of a functionally active VacA toxin in
Escherichia coli
. We then used a high-throughput screen to analyze a library of mutant toxins with pentapeptide insertions and identified six mutants that lacked the capacity to induce vacuolation of HeLa cells. The capacity to analyze VacA in this heterologous-expression system should greatly facilitate efforts to elucidate the structure and function of this toxin.
Mucosal Immunization with a Genetically Engineered Pertussis Toxin S1 Fragment-Cholera Toxin Subunit B Chimeric Protein
Authors: Lee Song F. , Halperin Scott A. , Salloum Danny F. , MacMillan Ann , Morris Annette 
Published: March 2003

ABSTRACTA chimeric protein consisting of a divalent pertussis toxin (PT) S1 fragment linked to the cholera toxin (Ctx) A2B fragment was constructed. The chimera induced a mucosal immunoglobulin A (IgA) and a serum IgG immune response to PT and CtxB in BALB/c mice following intranasal immunization. The immune sera neutralized PT in vitro. In the mouse model ofBordetella pertussisrespiratory infection, the chimera-immunized animals showed a significant reduction in bacterial lung counts (P= 0.01) from that of the sham control group. Thus, a divalent S1 fragment CtxA2B chimera is an immunogenic antigen and can elicit a protective immunity.
Interleukin-10 Negatively Regulates Local Cytokine and Chemokine Production but Does Not Influence Antibacterial Host Defense during Murine Pneumococcal Meningitis
Authors: Zwijnenburg Petra J. G. , van der Poll Tom , Florquin Sandrine , Roord John J. , van Furth A. Marceline 
Published: March 2003

ABSTRACTTo determine the role of endogenous interleukin-10 (IL-10) in local host defense during pneumococcal meningitis, the inflammatory responses of IL-10-gene-deficient and wild-type mice after the induction of meningitis were compared. The absence of IL-10 was associated with higher cytokine and chemokine concentrations and a more pronounced infiltrate, but antibacterial defense or survival was not influenced.
Flagellum-Mediated Adhesion byBurkholderia pseudomalleiPrecedes Invasion ofAcanthamoeba astronyxis
Authors: Inglis Timothy J. J. , Robertson Terry , Woods Donald E. , Dutton Nichole , Chang Barbara J. 
Published: March 2003

ABSTRACTIn this study we investigated the role of the bacterial flagellum inBurkholderia pseudomalleientry toAcanthamoeba astronyxistrophozoites.B. pseudomalleicells were tethered to the external amoebic surface via their flagella. MM35, the flagellum-lackingfliCknockout derivative ofB. pseudomalleiNCTC 1026b did not demonstrate flagellum-mediated endocytosis in timed coculture, confirming that an intact flagellar apparatus assistsB. pseudomalleientry intoA. astronyxis.
Immunization withPorphyromonas gingivalisCapsular Polysaccharide PreventsP. gingivalis-Elicited Oral Bone Loss in a Murine Model
Authors: Gonzalez Dario , Tzianabos Arthur O. , Genco Caroline A. , Gibson Frank C. 
Published: March 2003

ABSTRACTThe capsular polysaccharide (CPS) of the periodontal pathogenPorphyromonas gingivalisis an important virulence factor for this organism. We purifiedP. gingivalisCPS, immunized mice with this antigen, and assessed the vaccine potential ofP. gingivalisCPS by using the murine oral challenge model. Animals immunized withP. gingivalisCPS developed elevated levels of immunoglobulin M (IgM) and IgG in serum that reacted with wholeP. gingivalisorganisms. The mice immunized withP. gingivalisCPS were protected fromP. gingivalis-elicited oral bone loss. These data demonstrate thatP. gingivalisCPS is a vaccine candidate for prevention ofP. gingivalis-elicited oral bone loss.
Bidirectional Concentration-Dependent Effects of Tumor Necrosis Factor Alpha in
Shigella dysenteriae
-Related Seizures
Authors: Yuhas Yael , Weizman Abraham , Ashkenazi Shai 
Published: March 2003

ABSTRACT

We have previously demonstrated that pretreatment of mice with
Shigella dysenteriae
sonicate enhanced their susceptibility to pentylenetetrazole-induced seizures and that tumor necrosis factor alpha (TNF-α) was proconvulsive in this respect. The present study shows that TNF-α, at high concentrations, may also exert a suppressive effect on
Shigella
-mediated seizures. This implies that high levels of TNF-α may play a protective role in neurologic complications of
S
.
dysenteriae
infection.
The Fibronectin-Binding Proteins of
Staphylococcus aureus
May Promote Mammary Gland Colonization in a Lactating Mouse Model of Mastitis
Authors: Brouillette Eric , Talbot Brian G. , Malouin François 
Published: March 2003

ABSTRACT

The fibronectin-binding proteins (FnBPs) of
Staphylococcus aureus
are believed to be implicated in the pathogen's adherence to and colonization of bovine mammary glands, thus leading to infectious mastitis. In vitro studies have shown that FnBPs help the adhesion of the pathogen to bovine mammary epithelial cells. However, the importance of FnBPs for the infection of mammary glands has never been directly established in vivo. In this study with a mouse model of mastitis, the presence of FnBPs on the surface of
S. aureus
increased the capacity of the bacterium to colonize mammary glands under suckling pressure compared to that of a mutant lacking FnBPs.
THE TREND TOWARD OUTSOURCING IN NEW PRODUCT DEVELOPMENT: CASE STUDIES IN SIX FIRMS
Authors: ZHAO YUSHAN , CALANTONE ROGER J. 
Published: March 2003

In the constant drive for higher quality, lower cost, and faster-to-market products, many firms have begun to learn "how not to make things" — how to give some tasks to other firms who could make more efficiently. Examples from industries highlight the trend. Case studies were conducted in six firms and many insightful comments from prominent managers are incorporated. The case studies reveal a trend toward outsourcing some tasks in new product development. We use the transaction cost theory and the resource-based theory to explain the trend of outsourcing. This kind of outsourcing allows the firm to focus on core tasks and access resources and capabilities not available or not easily developed internally. NPD program performance can be greatly enhanced, and the R&D department can move away from routine administration toward a more strategic role. Many implications for managers are offered, and theoretical contributions are discussed.
A 6-month versus a 12-month surveillance for hepatocellular carcinoma in 559 hemophiliacs infected with the hepatitis C virus
Authors: Santagostino Elena , Colombo Massimo , Rivi Monica , Rumi Maria Grazia , Rocino Angiola , Linari Silvia , Mannucci Pier Mannuccio ,   for the the Study Group of the Association of Italian Hemophilia Centers
Published: March 2003

Abstract
Hepatocellular carcinoma (HCC) is an increasingly frequent cause of mortality in hemophiliacs with chronic viral hepatitis. Early diagnosis of the tumor at an initial stage is known to improve the outcome of HCC treatment. Because all HCC cases detected in a previous study based upon annual ultrasound (US) surveillance of hemophiliacs with elevated alanine aminotransferase levels were multinodular, this study was designed to evaluate if a more intense surveillance with US and alphafetoprotein (AFP) serum levels of all the patients infected with the hepatitis C virus (HCV) improved the identification of single nodule tumors. A multicenter cohort of 559 HCV-infected hemophiliacs was divided into 2 arms, one followed up at 6-month intervals and one at 12-month intervals depending on the choice and available facilities of each treatment center. During a 6-year surveillance period, HCC was diagnosed in 5 (2.4%) of 210 patients in the 6-month group and in 3 (0.9%) of 349 patients in the 12-month group. The overall incidence rate of HCC was 239 per 100 000 per year (397 per 100 000 per year in the 6-month group and 143 per 100 000 per year in the 12-month group; differences not statistically significant). By multivariate analysis, HCC risk was increased 12.9-fold with alcohol intake more than 80 g/d and 15.2-fold with AFP levels higher than 11 ng/mL. Liver-related death occurred in 8 cases (1.4%), including 3 with HCC. Still alive and tumor free after 24 to 34 months from diagnosis are 3 patients with multinodular tumors treated with repeat chemoembolization followed by orthotopic liver transplantation. In conclusion, 6-month surveillance with US did not increase the chances of detection of single nodule tumors, but it is reasonable to assume that successful treatment of multinodular tumors based upon debulking with chemoembolization and liver transplantation was facilitated by this approach. (Blood. 2003;102:78-82)
NMDA receptor–mediated regulation of human megakaryocytopoiesis
Authors: Hitchcock Ian S. , Skerry Timothy M. , Howard Martin R. , Genever Paul G. 
Published: March 2003

Abstract
Identification of the regulatory inputs that direct megakaryocytopoiesis and platelet production is essential for the development of novel therapeutic strategies for the treatment of thrombosis and related hematologic disorders. We have previously shown that primary human megakaryocytes express the N-methyl-d-aspartate acid (NMDA) receptor 1 (NR1) subunit of NMDA-type glutamate receptors, which appear to be pharmacologically similar to those identified at neuronal synapses, responsible for mediating excitatory neurotransmission in the central nervous system. However, the functional role of NMDA receptor signaling in megakaryocytopoiesis remains unclear. Here we provide evidence that demonstrates the fundamental importance of this signaling pathway during human megakaryocyte maturation in vitro. Reverse transcriptase–polymerase chain reaction (RT-PCR) analysis of RNA extracted from CD34+-derived megakaryocytes identified expression of NR2A and NR2D receptor subunits in these cells, as well as the NMDA receptor accessory proteins, Yotiao and postsynaptic density protein 95 (PSD-95). In functional studies, addition of a selective NMDA receptor antagonist, MK-801 inhibited proplatelet formation, without affecting proliferation or apoptosis. Exposure of CD34+ cells to MK-801 cultured for 14 days in the presence of thrombopoietin induced a decrease in expression of the megakaryocyte cell surface markers CD61, CD41a, and CD42a compared with controls. At an ultrastructural level, MK-801–treated cells lacked α-granules, demarcated membranes, and multilobed nuclei, which were prominent in untreated mature megakaryocyte controls. Using immunohistochemistry on sections of whole tibiae from c-Mpl knockout mice we demonstrated that megakaryocytic NMDA receptor expression was maintained following c-Mpl ablation. These data support a fundamental role for glutamate signaling in megakaryocytopoiesis and platelet production, which is likely to be independent of thrombopoietin-mediated effects.
Founder von Willebrand factor haplotype associated with type 1 von Willebrand disease
Authors: O'Brien Lee A. , James Paula D. , Othman Maha , Berber Ergul , Cameron Cherie , Notley Colleen R. P. , Hegadorn Carol A. , Sutherland Jeffrey J. , Hough Christine , Rivard Georges E. , O'Shaunessey Denise , Lillicrap David ,   the Association of Hemophilia Clinic Directors of Canada
Published: March 2003

AbstractTo date, no dominant mutation has been identified in a significant proportion of patients with type 1 von Willebrand disease (VWD). In this study, we examined 70 families as part of the Canadian Type 1 VWD Study. The entire VWF gene was sequenced for 1 index case, revealing 2 sequence variations: intron 30 (5312—19A&gt;C) and exon 28 at Tyr1584Cys (4751A&gt;G). The Tyr1584Cys variation was identified in 14.3% (10 of 70) of the families and was in phase with the 5312—19A&gt;C variation in 7 (10.0%) families. Both variants were observed in 2 of 10 UK families with type 1 VWD, but neither variant was found in 200 and 100 healthy, unrelated persons, respectively. Mean von Willebrand factor antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCo), and factor VIII coagulant activity (FVIII:C) for the index cases in these families are 0.4 U/mL, 0.36 U/mL, and 0.54 U/mL, respectively, and VWF multimer patterns show no qualitative abnormalities. Aberrant VWF splicing was not observed in these patients, and both alleles of the VWF gene are expressed as RNA. Molecular dynamic simulation was performed on a homology model of the VWF-A2 domain containing the Tyr1584Cys mutation. This showed that no significant structural changes occur as a result of the substitution but that a new solvent-exposed reactive thiol group is apparent. Expression studies revealed that the Tyr1584Cys mutation results in increased intracellular retention of the VWF protein. We demonstrate that all the families with the Tyr1584Cys mutation share a common, evolved VWF haplotype, suggesting that this mutation is ancient. This is the first report of a mutation that segregates in a significant proportion of patients with type 1 VWD.
The telomerase-associated protein p43 is involved in anchoring telomerase in the nucleus
Authors: Möllenbeck Matthias , Postberg Jan , Paeschke Katrin , Rossbach Michael , Jönsson Franziska , Lipps Hans J. 
Published: March 2003

Telomere replication of eukaryotic chromosomes is achieved by a specialized enzyme, the telomerase. Although the biochemistry of end-replication is well understood, little is known about the organization of the end-replication machinery, its regulation throughout the cell cycle or the biological function of the telomerase-associated proteins. Here we investigate the function of the telomerase-associated protein p43 within the macronucleus of the ciliated protozoa Euplotes. It has been shown that p43 binds in vitro to the RNA subunit of telomerase and shares homology with the La autoantigen family. It therefore has been suggested that it is involved in the assembly and/or nuclear retention of telomerase. We show that the p43-telomerase complex is bound to a subnuclear structure in vivo and is resistant to electroelution. Upon inhibition of p43 or telomerase expression by RNAi, which in this study was used for the first time in spirotrichs, this complex is no longer retained in the nucleus.
Further analysis revealed that the p43-telomerase complex is bound to the nuclear matrix in vivo and that after inhibition of p43 expression, telomerase is released from this structure, strongly suggesting that p43 is involved in anchoring of telomerase in the nucleus. This is the first in vivo demonstration of the biological function of this telomerase-associated component involved in telomere replication and allows us to propose a model for the organization of the end-replication machinery in the eukaryotic cell.
Localization of myoinhibitory peptide immunoreactivity inManduca sextaandBombyx mori, with indications that the peptide has a role in molting and ecdysis
Authors: Davis Norman T. , Blackburn Michael B. , Golubeva Elena G. , Hildebrand John G. 
Published: March 2003

SUMMARYFor normal development of Manduca sexta larvae, the ecdysteroid titer must drop following its sudden rise at the start of the molting cycle;this sudden decline in titer may be due to myoinhibitory peptide I (MIP I),which has an inhibitory effect on the release of ecdysone by the prothoracic glands of Bombyx mori in vitro. Using an antiserum to MIP, we have demonstrated secretion of an MIP-like peptide by the epiproctodeal glands of Manduca sexta, which are located on each proctodeal nerve, just anterior to the rectum. These MIP-immunoreactive glands are also present in B. mori. In fourth-instar larvae of M. sexta, the epiproctodeal glands show a distinct cycle of synthesis and sudden release of MIP that coincides with the time of the rapid decline in ecdysteroid titer. The function of the epiproctodeal glands appears to be the timely release of MIP during the molting cycle, so as to inhibit the prothoracic glands and thus to facilitate the sudden decline in ecdysteroid titer. In addition, we have found that MIP immunoreactivity is co-localized with that of crustacean cardioactive peptide (CCAP) in the 704 interneurons; these peptides appear to be co-released at the time of ecdysis. It is known that CCAP can initiate the ecdysis motor program; our results suggest that MIP may also be involved in activating ecdysis behavior.
A second glutamine synthetase gene with expression in the gills of the gulf toadfish (Opsanus beta)
Authors: Walsh Patrick J. , Mayer Gregory D. , Medina Mónica , Bernstein Matthew L. , Barimo John F. , Mommsen Thomas P. 
Published: March 2003

SUMMARYWe characterized the expression of the nitrogen metabolism enzyme glutamine synthetase [GSase; L-glutamate: ammonia ligase (ADP-forming), E.C. 6.3.1.2] in tissues of the gulf toadfish Opsanus beta subjected to unconfined(ammonotelic) and confined (ureotelic) conditions. Enzymological results demonstrate that mass-specific GSase activities rank in the order of brain&gt; liver &gt; stomach ≈ kidney &gt; intestine &gt; gill &gt; heart/spleen&gt; muscle. When tissue mass is used to calculate a glutamine synthetic potential, the liver has the greatest, followed by muscle &gt; stomach and intestine, with minor contributions from the remaining tissues. Additionally,during confinement stress, GSase activity increases significantly only in liver (fivefold) and muscle (twofold), tissues that previously showed significant expression of the other enzymes of urea synthesis. Western analyses of samples on SDS gels demonstrated that GSase-specific protein content reflected enzyme activity, and all tissues except muscle had a single,similarly sized GSase subunit of 49.4 kDa; muscle showed staining of two bands of 36.8 and 98.9 kDa, which may possibly result from another gene product or post-translational modification.RT-PCR and RACE-PCR revealed the presence of a second GSase cDNA from gill tissue that shares only 73% nucleotide and amino acid sequence similarity with the GSase cDNA previously cloned from liver, and that lacks a mitochondrial leader-targeting sequence. RT-PCR and restriction digestion experiments demonstrated that mRNA from the original `liver' GSase is expressed in all tissues examined (liver, gill, stomach, intestine, kidney, brain and muscle),whereas the new `gill' form shows expression primarily in the gill. Gill GSase activity shows apparently exclusive expression in the soluble compartment,while other tissues expressing the `liver' form show both cytoplasmic and mitochondrial activities.Phylogenetic analysis of a number of GSases demonstrates that the toadfish gill GSase has a greater affinity for a clade that includes the Xenopus GSase genes and one of two Fugu GSase genes, than it has for a clade containing the toadfish liver GSase and other described teleost GSase genes. The results are discussed in the context of a prior hypothesis on an ammonia-trapping mechanism in the gill of the toadfish.
Factors affecting stroking patterns and body angle in diving Weddell seals under natural conditions
Authors: Sato Katsufumi , Mitani Yoko , Cameron Michael F. , Siniff Donald B. , Naito Yasuhiko 
Published: March 2003

SUMMARYAquatic animals use a variety of strategies to reduce the energetic cost of locomotion. Efficient locomotion is particularly important for breath-holding divers because high levels of exercise may quickly deplete oxygen reserves,leading to the termination of a dive. We investigated the swimming behavior of eight adult Weddell seals, which are proficient divers, in McMurdo Sound,Antarctica. A newly developed data logger was attached to free-ranging females at their own breeding sites to record swimming speed, depth, two-dimensional accelerations (stroke frequency and body angle) and temperature. All seals conducted multiple deep dives (the mean dive depth range for each animal was 223.3±66.5–297.9±164.7 m). Prolonged gliding while descending was observed with thinner females (N=5 seals). But the fatter females (N=3 seals) exhibited only swim-and-glide swimming,characterized by intermittent stroking and fluctuating swim speed, throughout their descent and ascent. The body angles of four of the seals were restricted to less than 30° by the location of breathing holes in the ice and the slope of local bathymetric features. Of these four, the three fatter seals adopted the stroke-and-glide method while the other thinner seal descended with prolonged periods of gliding. Prolonged gliding seems to be a more efficient method for locomotion because the surface time between dives of gliding seals was significantly less than that of stroking animals, despite their same stroke frequencies.