bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temporal Expression of Type III Secretion Genes ofChlamydia pneumoniae
Authors: Slepenkin Anatoly , Motin Vladimir , de la Maza Luis M. , Peterson Ellena M. 
Published: April 2003

ABSTRACTChlamydia pneumoniaehas been shown to possess at least 13 genes that are homologous with other known type III secretion (TTS) systems. Upon infection of HEp-2 cells withC. pneumoniae, the expression of these genes was followed by reverse transcriptase PCR throughout the developmental cycle of this obligate intracellular pathogen. In addition, expression was analyzed whenC. pneumoniaewas grown in the presence of human gamma interferon (IFN-γ). ThegroEL-1,ompA, andomcBgenes were used as markers for the early, middle, and late stages of the developmental cycle, respectively, and the inhibition of expression of thefstKgene was used as a marker for the effect of IFN-γ on the maturation ofC. pneumoniae. In the absence of IFN-γ, the TTS genes were expressed as follows: early stage (1.5 to 8 h),yscC,yscS,yscL,yscJandlcrH-2; middle stage (by 12 to 18 h),lcrD,yscN, andyscR; and late stage (by 24 h),lcrE,sycE,lcrH-1, andyscT. Of the genes expressed early, thelcrH-2gene was detected the earliest, at 1.5 h. Expression of theyscUgene was not detected at any of the time points examined. Under the influence of IFN-γ, the cluster of TTS genes that were normally not expressed until the middle to late stages of the developmental cycle, namely,lcrD,lcrE, andsycE, as well aslcrH-1, were down-regulated, and expression could not be detected up to 48 h. In contrast, the expression of the other TTS genes appeared to be unchanged in the presence of IFN-γ. ThelcrH-1andlcrH-2genes differed from one another in both their temporal expression and response to IFN-γ. In other TTS systems, these genes code for proteins that function in regulation of effector protein synthesis as well as serve as chaperones for proteins that provide for the translocation of the effector proteins into the host cell. In summary, the expression pattern of the TTS genes ofC. pneumoniaeexamined suggests that they are temporally regulated throughout the developmental cycle. Furthermore, paralleling the inhibition of the maturation of the reticulate body to the elementary body, TTS genes expressed in the later stages of the cycle appear to be down-regulated when the organism is grown in the presence of IFN-γ.
Unexpected Similarities betweenBordetella aviumand Other Pathogenic Bordetellae
Authors: Spears Patricia A. , Temple Louise M. , Miyamoto David M. , Maskell Duncan J. , Orndorff Paul E. 
Published: April 2003

ABSTRACTBordetella aviumcauses an upper respiratory tract disease (bordetellosis) in avian species. Commercially raised turkeys are particularly susceptible. Like other pathogenic members of the genusBordetella(B. pertussisandB. bronchiseptica) that infect mammals,B. aviumbinds preferentially to ciliated tracheal epithelial cells and produces similar signs of disease. These similarities prompted us to study bordetellosis in turkeys as a possible nonmammalian model for whooping cough, the exclusively human childhood disease caused byB. pertussis. One impediment to accepting such a host-pathogen model as relevant to the human situation is evidence suggesting thatB. aviumdoes not express a number of the factors known to be associated with virulence in the other twoBordetellaspecies. Nevertheless, with signature-tagged mutagenesis, four avirulent mutants that had lesions in genes orthologous to those associated with virulence inB. pertussisandB. bronchiseptica(bvgS,fhaB,fhaC, andfimC) were identified. None of the fourB. aviumgenes had been previously identified as encoding factors associated with virulence, and three of the insertions (infhaB,bvgS, andfimC) were in genes or gene clusters inferred as being absent or incomplete inB. avium, based upon the lack of DNA sequence similarities in hybridization studies and/or the lack of immunological cross-reactivity of the putative products. We further found that the genotypic arrangements of most of theB. aviumorthologues were very similar in all threeBordetellaspecies. In vitro tests, including hemagglutination, tracheal ring binding, and serum sensitivity, helped further define the phenotypes conferred by the mutations. Our findings strengthen the connection between the causative agents and the pathogenesis of bordetellosis in all hosts and may help explain the striking similarities of the histopathologic characteristics of this upper airway disease in avian and mammalian species.
RegR, a Global LacI/GalR Family Regulator, Modulates Virulence and Competence in
Streptococcus pneumoniae
Authors: Chapuy-Regaud Sabine , Ogunniyi A. David , Diallo Nicole , Huet Yvette , Desnottes Jean-François , Paton James C. , Escaich Sonia , Trombe Marie-Claude 
Published: April 2003

ABSTRACT

The homolactic and catalase-deficient pathogen
Streptococcus pneumoniae
is not only tolerant to oxygen but requires the activity of its NADH oxidase, Nox, to develop optimal virulence and competence for genetic transformation. In this work, we show that the global regulator RegR is also involved in these traits. Genetic dissection revealed that RegR regulates competence and the expression of virulence factors, including hyaluronidase. In bacteria grown in vitro, RegR represses hyaluronidase. At neutral pH, it increases adherence to A549 epithelial cells, and at alkaline pH, it acts upstream of the CiaRH two-component signaling system to activate competence. These phenotypes are not associated with changes in antibiotic resistance, central metabolism, and carbohydrate utilization. Although the RegR
0
(where 0 indicates the loss of the protein) mutation is sufficient to attenuate experimental virulence of strain 23477 in mice, the introduction of an additional

hyl
0

(where 0 indicates the loss of function) mutation in the RegR
0
strain 23302 dramatically reduces its virulence. This indicates that residual virulence of the RegR
0
Hyl
+
derivative is due to hyaluronidase and supports the dual role of RegR in virulence. This LacI/GalR regulator, not essential for in vitro growth in rich media, is indeed involved in the adaptive response of the pneumococcus via its control of competence, adherence, and virulence.
Apoptotic Response of Chang Cells to Infection withPseudomonas aeruginosaStrains PAK and PAO-I: Molecular Ordering of the Apoptosis Signaling Cascade and Role of Type IV Pili
Authors: Jendrossek Verena , Fillon Sophie , Belka Claus , Müller Ilka , Puttkammer Beatrice , Lang Florian 
Published: April 2003

ABSTRACTPseudomonas aeruginosais a gram-negative facultative opportunistic pathogen associated with severe infections in immunocompromised hosts and in patients with cystic fibrosis.P. aeruginosastrains show divergent pathogenicity in vivo and trigger apoptosis of and/or are internalized into human host cells. In the present study, we studied the molecular ordering of apoptosis signaling upon infection of human conjunctiva epithelial Chang cells withP. aeruginosaPAK as well as the role of bacterial pili in the response to the infection. Our results show that CD95 up-regulation is followed by early activation of caspase-8 and -3 and cleavage of the caspase-3 substrate poly(ADP-ribose) polymerase. The data also demonstrate release of apoptosis inducing factor into the cytosol of infected cells. Induction of mitochondrial alterations, i.e., mitochondrial depolarization and release of cytochrome c, as well as cleavage of caspase-9, -7, and -1 occurred only at later time points. In addition, our results demonstrate that pili are required forP. aeruginosa-induced apoptosis of human epithelial cells. While the two piliatedP. aeruginosastrains, PAO-I and PAK, induced apoptosis of Chang cells within 3 h of infection, the pilus-deficientP. aeruginosamutants PAKΔpilAand PAKΔpilAΔallwere without effect. The pilus-deficient mutants failed to induce a significant up-regulation of CD95 on the cell surface and to trigger mitochondrial alterations or activation of caspase-8, -3, and -7. In addition, only the piliated wild-type strains induced caspase-1-mediated activation of interleukin-1β. Thus, pili are necessary for distinct infection-induced cellular responses of human epithelial cells.
The Levels and Patterns of Cytokines Produced by CD4 T Lymphocytes of BALB/c Mice Infected withLeishmania majorby Inoculation into the Ear Dermis Depend on the Infectiousness and Size of the Inoculum
Authors: Lang Thierry , Courret Nathalie , Colle Jean-Hervé , Milon Geneviève , Antoine Jean-Claude 
Published: April 2003

ABSTRACTThe production of cytokines by CD4 lymph node T lymphocytes derived from BALB/c mice recently infected in the ear dermis with high (106parasites) or low (103parasites) doses ofLeishmania majormetacyclic promastigotes (MP) was examined over a 3-week period following inoculation. Results were compared with those obtained when mice were injected with less infectious parasite populations, namely, stationary-phase or log-phase promastigotes (LP). Cells were purified 16 h and 3, 8, and 19 days after inoculation, and the amounts of gamma interferon (IFN-γ) and interleukin-4 (IL-4) released in response to LACK (Leishmaniahomolog of receptors for activated C kinase) or totalL. majorantigens were assessed. We found that LACK-reactive T cells from mice inoculated with a high dose of parasites first produced IFN-γ and later on IL-4; the level of IFN-γ produced early by these cells was dependent upon the stage of the promastigotes inoculated, the highest level being reached with cells recovered from mice inoculated with the least infectious parasites, LP; sequential production of IFN-γ and then of IL-4 also characterizedL. majorantigen-reactive CD4 T cells, suggesting that the early production of IFN-γ does not impede the subsequent rise of IL-4 and finally the expansion of the parasites; after low-dose inoculation of MP, cutaneous lesions developed with kinetics similar to that of lesions induced after inoculation of 106LP, but in this case CD4 T lymphocytes did not release IFN-γ or IL-4 in the presence of LACK and neither cytokine was produced in response toL. majorantigens before the onset of lesion signs. These results suggest the existence of a discreet phase in terms of CD4 T-cell reactivity for at least the first 8 days following inoculation, a time period during which parasites are able to grow moderately. In conclusion, the levels and profiles of cytokines produced byLeishmania-specific CD4 T lymphocytes clearly depend on both the stage of differentiation and number of parasites used for inoculation.
Quantitative Evaluation of Inflammatory and Immune Responses in the Early Stages of ChronicHelicobacter pyloriInfection
Authors: Straubinger Reinhard K. , Greiter Andrea , McDonough Sean P. , Gerold Alexander , Scanziani Eugenio , Soldati Sabina , Dailidiene Daiva , Dailide Giedrius , Berg Douglas E. , Simpson Kenneth W. 
Published: April 2003

ABSTRACTThe early consequences ofHelicobacter pyloriinfection and the role of bacterial virulence determinants in disease outcome remain to be established. The present study sought to measure the development of host inflammatory and immune responses and their relationship to the putative bacterial virulence factorscagpathogenicity island (cagPAI),vacAallele, andoipAin combination with bacterial colonization density in a feline model of the early stages ofH. pyloriinfection. Gastric tissues obtained from infected and uninfected cats were evaluated forH. pylori ureB,cagPAI,vacAallele, andoipAand colonization density (urease, histology, and real-time PCR). Inflammation was assessed by measuring mRNA upregulation of gamma interferon (IFN-γ), interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-10, and IL-12 p40 and histopathology. The mucosal immune response was characterized by morphometric analysis of lymphoid follicles and by differentiating lymphocyte populations with antibodies against surface markers. InfectingH. pyloristrains were positive forvacAs1but lackedcagPAI and an activeoipAgene. Colonization density was uniform throughout the stomach. Upregulation of IFN-γ, IL-1α, IL-1β, and IL-8 and increased severity of inflammatory infiltrates and fibrosis were observed in infected cats. The median number and total area of lymphoid aggregates were 5 and 10 times greater, respectively, in the stomachs of infected than uninfected cats. Secondary lymphoid follicles in uninfected cats were rare and positive for BLA.36 and B220 but negative for CD3 and CD79α, whereas in infected cats they were frequent and positive for BLA.36, CD79α, and CD3 but negative for B220. Upregulation of IFN-γ, IL-1α, IL-1β, and IL-8 and marked hyperplasia of secondary lymphoid follicles are early consequences ofH. pyloriinfection in cats. The response appears to be similar to that of infected people, particularly children, can develop independently of the pathogenicity factorscagPAI andoipA, and is not correlated with the degree of colonization density or urease activity.
Bacterial Spores as Vaccine Vehicles
Authors: Duc Le H. , Hong Huynh A. , Fairweather Neil , Ricca Ezio , Cutting Simon M. 
Published: April 2003

ABSTRACT

For the first time, bacterial spores have been evaluated as vaccine vehicles.
Bacillus subtilis
spores displaying the tetanus toxin fragment C (TTFC) antigen were used for oral and intranasal immunization and were shown to generate mucosal and systemic responses in a murine model. TTFC-specific immunoglobulin G titers in serum (determined by enzyme-linked immunosorbent assay) reached significant levels 33 days after oral dosing, while responses against the spore coat proteins were relatively low. Tetanus antitoxin levels were sufficient to protect against an otherwise lethal challenge of tetanus toxin (20 50% lethal doses). The robustness and long-term storage properties of bacterial spores, coupled with simplified genetic manipulation and cost-effective manufacturing, make them particularly attractive vehicles for oral and intranasal vaccination.
Antigenic and Biological Characteristics of Mutant Strains ofCryptococcus neoformansLacking Capsular O Acetylation or Xylosyl Side Chains
Authors: Kozel Thomas R. , Levitz Stuart M. , Dromer Françoise , Gates Marcellene A. , Thorkildson Peter , Janbon Guilhem 
Published: April 2003

ABSTRACTCryptococcus neoformansis surrounded by an antiphagocytic polysaccharide capsule whose primary constituent is glucuronoxylomannan (GXM). Three prominent structural features of GXM are single xylosyl and glucuronosyl side chains and O acetylation of the mannose backbone. Isogenic pairs ofO-acetyl-positive andO-acetyl-negative strains (cas1Δ) as well as xylose-positive and xylose-negative strains (uxs1Δ) of serotype D have been reported. Thecas1Δstrains were hypervirulent, and theuxs1Δstrains were avirulent. The goal of this study was to examine the effects of thecas1Δanduxs1Δmutations on the following: (i) binding of anti-GXM monoclonal antibodies (MAbs) in capsular quellung reactions, (ii) activation of the complement system and binding of C3, (iii) phagocytosis by neutrophils, and (iv) clearance of GXM in vivo. The results showed that loss of O acetylation produced dramatic changes in the reactivities of five of seven anti-GXM MAbs. In contrast, loss of xylosylation produced a substantive alteration in the binding behavior of only one MAb.O-acetyl-negative strains showed no alteration in activation and binding of C3 from normal serum. Xylose-negative strains exhibited accelerated kinetics for C3 deposition. Loss of O acetylation or xylosylation had no effect on phagocytosis of serum-opsonized yeast cells by human neutrophils. Finally, loss of O acetylation or xylosylation altered the kinetics for clearance of GXM from serum and accumulation of GXM in the liver and spleen. These results show that O acetylation and/or xylosylation are important for binding of anti-GXM MAbs, for complement activation, and for tissue accumulation of GXM but do not impact phagocytosis by neutrophils.
Histidine and Aspartic Acid Residues Important for Immunoglobulin G Endopeptidase Activity of the Group AStreptococcusOpsonophagocytosis-Inhibiting Mac Protein
Authors: Lei Benfang , Liu Mengyao , Meyers Elishia G. , Manning Heather M. , Nagiec Michael J. , Musser James M. 
Published: April 2003

ABSTRACTThe secreted Mac protein made by serotype M1 group AStreptococcus(GAS) (designated Mac5005) inhibits opsonophagocytosis and killing of GAS by human polymorphonuclear neutrophils. This protein also has cysteine endopeptidase activity against human immunoglobulin G (IgG). Site-directed mutagenesis was used to identify histidine and aspartic acid residues important for Mac IgG endopeptidase activity. Replacement of His262 with Ala abolished Mac5005 IgG endopeptidase activity. Asp284Ala and Asp286Ala mutant proteins had compromised enzymatic activity, whereas 21 other Asp-to-Ala mutant proteins cleaved human IgG at the apparent wild-type level. The results suggest that His262 is an active-site residue and that Asp284 and Asp286 are important for the enzymatic activity or structure of Mac protein. These Mac mutants provide new information about structure-activity relationships in this protein and will assist study of the mechanism of inhibition of opsonophagocytosis and killing of GAS by Mac.
BARYON SELF-ENERGY WITH qqq BETHE–SALPETER DYNAMICS IN THE NONPERTURBATIVE QCD REGIME: n-p MASS DIFFERENCE
Authors: SHARMA ANJU , MITRA A. N. 
Published: April 2003

A qqq BSE formalism based on DBχS of an input four-fermion Lagrangian of "current" u, d quarks interacting pairwise via gluon-exchange-propagator in its nonperturbative regime, is employed for the calculation of baryon self-energy via quark-loop integrals. To that end the baryon-qqq vertex function is derived under Covariant Instantaneity Ansatz (CIA), using Green function techniques. This is a three-body extension of an earlier [Formula: see text] (two-body) result on the exact 3D–4D interconnection for the respective BS wave functions under 3D kernel support. The nonperturbative QCD feature of this approach (vis-a-vis chiral perturbation theory — see text for comparison) is preserved through the gluon exchange propagator in the infrared regime (characterized by two parameters C0, ω0), precalibrated to both [Formula: see text] and qqq spectra plus other observables, together with a DBχ S mechanism to generate the dynamical mass m(p). The quark-loop integrals for the neutron (n) – proton (p) mass difference receive contributions from two sources: (i) the strong SU(2) effect arising from the d-u mass difference (4 MeV); (ii) the e.m. effect of the respective quark charges. The resultant n-p difference comes dominantly from the d-u effect (+1.71 MeV ), which is mildly offset by e.m. effect (-0.44), subject to gauge corrections. For an estimate of the latter a general method for QED gauge corrections to an arbitrary momentum dependent vertex function is outlined (in App. C), and a calculation made for the (two-body) kaon as a test case, indicates an increase by 0.612 MeV in the earlier kaon e.m. value (1.032 MeV). This result is taken as a rough indication of the percentage gauge correction expected for the n-p case. A critical comparison is given with the results from QCD sum rules.
DYNAMIC COOPERATIVE GAMES
Authors: FILAR JERZY A. , PETROSJAN LEON A. 
Published: April 2003

We consider dynamic cooperative games in characteristic function form in the sense that the characteristic function evolves over time in accordance with a difference or differential equation that is influenced not only by the current ("instantaneous") characteristic function but also by the solution concept used to allocate the benefits of cooperation among the players. The latter solution concept can be any one of a number of now standard solution concepts of cooperative game theory but, for demonstration purposes, we focus on the core and the Shapley value. In the process, we introduce some new mechanisms by which players may regard the evolution of cooperative game over time and analyse them with respect to the goal of attaining time consistency either in discrete or in continuous time setting. In discrete time, we illustrate the phenomena that can arise when an allocation according to a given solution concept is used to adapt the values of coalitions at successive time points. In continuous time, we introduce the notion of an "instantaneous" game and its integration over time.
Considerations for manufacture of irrigation pipe
Authors: Tock Richard Wm. , A'hern Daniel W. 
Published: April 2003

AbstractOn January 18, 1977 the United States Patent Office granted James E. Turner the rights to Patent Number 4,003,408 entitled “Underground Irrigation Porous Pipe.” The porous pipe was claimed to be made entirely from reclaimed rubber and recycled plastic binder. The weight percent of binder materials ranged from 10% to 40%. The wall of the porous pipe was reported to contain labyrinthine apertures of such size and number so as to provide a leak rate of 12 to 20 gallons per hour of water per one hundred feet of length of 1/2 inch pipe when subjected to internal pressures of 5 to 10 psig. The pores were claimed to have been blown into the walls by venting vapors and water associated with the rubber during the extrusion process.This paper reports on an analysis of such a “leaky pipe” as described by Patent Number 4,003,408. The leakage phenomenon is shown to be a natural occurrence which arises from the adhesion of rubber particles with insufficient binder to fill the voids between particles. This observation means that the reclaimed rubber must have a very narrow size range if the leak rate is to be predictable. In addition, the binder material may be restricted to virgin LLDPE feed stock if a reproducible product is to be continuously extruded. Finally, using technology developed for sintered‐porous metal objects, it was demonstrated that the leak rate can be predicted a priori. This evidence suggests that the occurrence of the porosity as claimed in U.S. Patent Number 4,003,408 is not confirmed by practical experience. Moreover, although a leaky pipe can be produced in accordance with the teachings of the patent, the properties and performance of that pipe will probably not meet the specification of potential users.
Some factors influencing filling of multiple cavities during injection molding
Authors: Throne J. L. 
Published: April 2003

AbstractThe rate of filling of multiple cavities positioned along a runner is of significant importance to injection molders. Unevenness in filling can lead to unfilled cavities near the end of the runners or to long cycle times. The effects of gate dimension and shape, cavity capacity and injection rate on injection pressure for an isothermal Newtonian fluid are discussed in detail. Extension to power‐law fluids and nonisothermal viscosity is outlined.
The twin‐screw extruder—a versatile tool for reactions and polymerizations
Authors: Wielgolinski Lee , Nangeroni Jim 
Published: April 2003

AbstractCo‐rotating, self‐wiping, twin‐screw extruders are being recognized as efficient horizontal mixers for performing continuous reactions and polymerizations. Many processes which previously required large batch type tanks for sufficient residence times can achieve similar yields and be replaced with much smaller equipment due to the greater efficiency of mixing. The use of co‐rotating, self‐wiping, twin‐screw extruders for continuous polymerization processes, especially on a laboratory development scale, will play a more important role in the future as their versatility in these processes is recognized.