bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Opsonization and Gamma Interferon on Growth ofBrucella melitensis16M in Mouse Peritoneal Macrophages In Vitro
Authors: Eze Michael O. , Yuan Liang , Crawford Robert M. , Paranavitana Chrysanthi M. , Hadfield Ted L. , Bhattacharjee Apurba K. , Warren Richard L. , Hoover David L. 
Published: May 2009

ABSTRACTEntry of opsonized pathogens into phagocytes may benefit or, paradoxically, harm the host. Opsonization may trigger antimicrobial mechanisms such as reactive oxygen or nitric oxide (NO) production but may also provide a safe haven for intracellular replication. Brucellae are natural intramacrophage pathogens of rodents, ruminants, dogs, marine mammals, and humans. We evaluated the role of opsonins inBrucella-macrophage interactions by challenging cultured murine peritoneal macrophages withBrucella melitensis16M treated with complement- and/or antibody-rich serum. Mouse serum rich in antibody againstBrucellalipopolysaccharide (LPS) (aLPS) and human complement-rich serum (HCS) each enhanced the macrophage uptake of brucellae. Combinations of suboptimal levels of aLPS (0.01%) and HCS (2%) synergistically enhanced uptake. The intracellular fate of ingested bacteria was evaluated with an optimal concentration of gentamicin (2 μg/ml) to control extracellular growth but not kill intracellular bacteria. Bacteria opsonized with aLPS and/or HCS grew equally well inside macrophages in the absence of gamma interferon (IFN-γ). Macrophage activation with IFN-γ inhibited replication of both opsonized and nonopsonized brucellae but was less effective in inhibiting replication of nonopsonized bacteria. IFN-γ treatment of macrophages with opsonized or nonopsonized bacteria enhanced NO production, which was blocked byNG-monomethyll-arginine (MMLA), an NO synthesis inhibitor. MMLA also partially blocked IFN-γ-mediated bacterial growth inhibition. These studies suggest that primary murine macrophages have limited ability to control infection withB. melitensis, even when activated by IFN-γ in the presence of highly opsonic concentrations of antibody and complement. Additional cellular immune responses, e.g., those mediated by cytotoxic T cells, may play more important roles in the control of murine brucellosis.
Roles of Endogenous Gamma Interferon and Macrophage Microbicidal Mechanisms in Host Response to Chemotherapy in Experimental Visceral Leishmaniasis
Authors: Murray Henry W. , Delph-Etienne Sharmaine 
Published: May 2009

ABSTRACTIn experimental visceral leishmaniasis, in which the tissue macrophage is the target, in vivo responsiveness to conventional chemotherapy (pentavalent antimony [Sb]) requires a T-cell-dependent mechanism. To determine if this mechanism involves gamma interferon (IFN-γ)-induced activation and/or specific IFN-γ-regulated macrophage leishmanicidal mechanisms (generation of reactive nitrogen or oxygen intermediates, we treated gene-deficient mice infected withLeishmania donovani. In IFN-γ gene knockout (GKO) mice, Sb inhibited but did not kill intracellularL. donovani(2% killing versus 76% in controls). Sb was active (>94% killing), however, in both inducible nitric oxide synthase (iNOS) knockout (KO) and respiratory burst (phagocyte oxidase)-deficient chronic granulomatous disease (X-CGD) mice. Sb's efficacy was also maintained in doubly deficient animals (X-CGD mice treated with an iNOS inhibitor). In contrast to Sb, amphotericin B (AmB) induced high-level killing in GKO mice; AmB was also fully active in iNOS KO and X-CGD animals. Although resolution ofL. donovaniinfection requires iNOS, residual visceral infection remained largely suppressed in iNOS KO mice treated with Sb or AmB. These results indicate that endogenous IFN-γ regulates the leishmanicidal response to Sb and achieves this effect via a pathway unrelated to the macrophage's primary microbicidal mechanisms. The role of IFN-γ is selective, since it is not a cofactor in the response to AmB. Treatment with either Sb or AmB permits an iNOS-independent mechanism to emerge and control residual intracellularL. donovaniinfection.
M-Like Proteins ofStreptococcus dysgalactiae
Authors: Vasi József , Frykberg Lars , Carlsson Lena E. , Lindberg Martin , Guss Bengt 
Published: May 2009

ABSTRACTStreptococcus dysgalactiaeis one of the most important bacterial species isolated from bovine mastitis. To identify potential virulence factors of this species we prepared chromosomal DNA from strain 8215 and constructed a phage display library. By affinity selection of the library against fibrinogen (Fg), we isolated and characterized a gene, calleddemA, encoding a protein with the molecular mass of ∼58 kDa, called DemA, displaying both plasma protein binding properties and sequence similarities with the M and M-like proteins of other streptococcal species. Purified recombinant DemA protein was found to completely inhibit Fg-binding to cells ofS. dysgalactiae. A continued sequence analysis revealed that thedemAgene was preceded by an open reading frame (dmgA) coding for a putative protein, called DmgA, with high similarities to the Mga proteins ofStreptococcus pyogenes. By additional cloning, the correspondingdmgAanddemAgenes from another strain, called Epi9, were isolated and analyzed. These genes, calleddmgBanddemB, respectively, revealed a high degree of similarity to the corresponding genes in strain 8215. Increased binding of Fg by cells of strain Epi9, grown in an atmosphere with 10% CO2, was correlated to an enhanced transcription of thedemBgene as shown in a Northern blot. Strain 8215 did not respond to CO2, which could be explained by a nonfunctionaldmgAgene due to insertion of an insertion sequence element. Based on sequence similarities of the described proteins to Mga, M, and M-like proteins and the response to elevated level of CO2, we suggest that thedmganddemgenes are members of a regulon similar to the describedmgaregulon inS. pyogenes, which encodes several virulence factors in this species.
Seroreactivity toChlamydia trachomatisHsp10 Correlates with Severity of Human Genital Tract Disease
Authors: LaVerda David , Albanese Lisa N. , Ruther Paul E. , Morrison Sandra G. , Morrison Richard P. , Ault Kevin A. , Byrne Gerald I. 
Published: May 2009

ABSTRACTWe have identified the chlamydial heat shock protein Hsp10 as a potential correlate to the immunopathogenic process in women with tubal factor infertility (TFI). The human serologic response to chlamydial Hsp10, Hsp60, and major outer membrane protein (MOMP) was measured by enzyme-linked immunosorbent assay. Three populations of women were studied: uninfected controls (CU), acutely infected (AI) women, and women with TFI. Sera from women in the AI and TFI groups both recognized Hsp10 more frequently and at a higher overall level than sera from healthy uninfected controls. Moreover, the infertile women had significantly greater Hsp10 seroreactivity than acutely infected women, indicating a concomitant increase of Hsp10 recognition in populations with increasing levels of disease severity. Hsp60 reactivity showed a similar correlation in these populations, while MOMP reactivity peaked at the same level in both AI and TFI populations but did not increase with disease severity. Test populations were standardized by level of reactivity to formalin-fixedChlamydia trachomatiselementary bodies (EBs) to address whether these associations were reflections of increased overall chlamydial exposure rather than a property specific to Hsp10. Associations between Hsp10 seropositivity and TFI were greater in the EB+subgroup while associations among the EB−subgroup were diminished. When restricted to the EB+subgroups, Hsp60 and MOMP responses in the TFI population did not increase significantly over the level of AI group responses. Thus, among women with similar exposure to chlamydiae, the serologic response to Hsp10 exhibited a stronger correlation with TFI than did the response to Hsp60 or MOMP. These findings support the hypothesis that the serological response toC. trachomatisheat shock proteins is associated with the severity of disease and identifies Hsp10 as an antigen recognized by a significant proportion of women with TFI.
Clearance and Organ Distribution ofMycobacterium tuberculosisLipoarabinomannan (LAM) in the Presence and Absence of LAM-Binding Immunoglobulin M
Authors: Glatman-Freedman Aharona , Mednick Aron J. , Lendvai Nikoletta , Casadevall Arturo 
Published: May 2009

ABSTRACTLipoarabinomannan (LAM) is a component of the mycobacterial surface which has been associated with a variety of deleterious effects on immune system function. Despite the importance of LAM to the pathogenesis of mycobacterial infection, there is no information available on its fate in vivo. In this study, we determined the pharmacokinetics and tissue distribution of exogenously administered LAM in mice. For measurements of serum and tissue LAM concentrations, we developed an enzyme-linked immunosorbent assay which used monoclonal antibodies of different isotypes to capture and detect LAM at concentrations of ≥0.4 μg/ml. Intravenous administration of LAM to mice resulted in transient serum levels with organ deposition in the spleen and in the liver. Immunohistochemical studies localized LAM to the spleen marginal zone macrophages and, to a lesser degree, to liver macrophages. When LAM was administered to mice previously given a LAM-binding immunoglobulin M (IgM), LAM was very rapidly cleared from circulation. In those mice, deposition of LAM in the spleen was significantly reduced while LAM deposition in the liver increased. Administration of LAM-binding IgM resulted in significant levels of IgM to LAM in bile consistent with an increased hepatobiliary excretion of LAM in the presence of specific antibody. Bile, liver extracts, and bile salts were found to rapidly inactivate the immunoreactivity of LAM. The results indicate that serum clearance and organ deposition of LAM in mice are affected by the presence of LAM-binding antibody and suggest a mechanism by which antibody could modify the course of mycobacterial infection.
Isolates ofChlamydia trachomatisThat Occupy Nonfusogenic Inclusions Lack IncA, a Protein Localized to the Inclusion Membrane
Authors: Suchland Robert J. , Rockey Daniel D. , Bannantine John P. , Stamm Walter E. 
Published: May 2009

ABSTRACTThe chlamydiae are obligate intracellular pathogens that occupy a nonacidified vacuole, termed an inclusion, throughout their developmenal cycle. When an epithelial cell is infected with multipleChlamydia trachomatiselementary bodies, they are internalized by endocytosis into individual phagosomal vacuoles that eventually fuse to form a single inclusion. In the course of large-scale serotyping studies in which fluorescent antibody staining of infected cells was used, a minority of strains that had an alternate inclusion morphology were identified. These variants formed multiple nonfusogenic inclusions in infected cells, with the number of independent inclusions per cell varying directly with the multiplicity of infection. Overall the nonfusogenic phenotype was found in 1.5% (176 of 11,440) of independent isolates. Nonfusing variants were seen inC. trachomatisserovars B, D, D−, E, F, G, H, Ia, J, and K. The nonfusing phenotype persisted through repeated serial passage, and the phenotype was consistent in four mammalian host cell lines. Fluorescence microscopy and immunoblotting with antisera directed at proteins in theC. trachomatisinclusion membrane revealed that one such protein, IncA, was not detected in the inclusion membrane in each tested nonfusogenic strain. The distributions of other chlamydial proteins, including one additional Inc protein, were similar in wild-type and variant strains. TheincAcoding and upstream regions were amplified and sequenced from the prototype serovar D and two nonfusing serovar D(s)strains. Three nucleotide changes were discovered in the D(s)incAgene, leading to two amino acid changes within the predicted D(s)IncA sequence. These studies demonstrate a subgroup of variantC. trachomatisisolates that form nonfusing inclusions; the variant phenotype is associated with the absence of detectable IncA and with an alteredincAsequence that modifies the characteristic hydrophobic domain of the IncA protein.
Characterization of a Macrophage-Specific Infectivity Locus (
milA
) of
Legionella pneumophila
Authors: Harb Omar S. , Abu Kwaik Yousef 
Published: May 2009

ABSTRACT

Legionella pneumophila
has been shown to possess multiple genetic loci that play roles in its ability to survive within host cells. The
mil
(macrophage-specific infectivity loci) mutants of
L. pneumophila
exhibit a spectrum of defects in intracellular survival in and cytopathogenicity to macrophages and alveolar epithelial cells. This study characterizes one of the
mil
mutants (GB111). Intracellular growth of GB111 in macrophages was approximately 100- to 1,000-fold less than that of AA100, the parental strain, at 24 and 48 h postinfection. This defect in turn corresponded to a defect in cytopathogenicity. Sequence analysis of the affected GB111 open reading frame (ORF) revealed it to encode a putative transport protein, and the ORF was designated
milA
. The phenotypic defect of the
milA
mutant was complemented with a PCR fragment containing only
milA
, indicating that the defect in GB111 was due to the disruption of
milA
. Intracellular trafficking of the mutant was examined by laser scanning confocal microscopy. The data showed that 50% of the GB111 phagosomes colocalized with the late endosomal/lysosomal marker LAMP-2 (2 and 4 h postinfection), while less than 10% of the AA100 phagosomes colocalized with this marker. On the other hand, over 80% of the GB111 phagosomes were similar to the AA100 phagosome in that they were devoid of LAMP-1 and cathepsin D, and they were colocalized with the endoplasmic reticulum (ER) marker BiP. However, the number of GB111 phagosomes that colocalized with BiP decreased to 50% 6 h postinfection compared to that of AA100, which remained constant (80% colocalization). Thus, compared to AA100, the
milA
mutation caused a defect in intracellular replication, which was associated with colocalization of the phagosome with LAMP-2 and BiP, while colocalization with LAMP-1 and cathepsin D was not affected.
Innate Immunity to Amebic Liver Abscess Is Dependent on Gamma Interferon and Nitric Oxide in a Murine Model of Disease
Authors: Seydel Karl B. , Smith Sara J. , Stanley Samuel L. 
Published: May 2009

ABSTRACT

Evidence from in vitro studies suggests that gamma interferon (IFN-γ) and nitric oxide (NO) are important in host defense against the protozoan parasite
Entamoeba histolytica
. We used SCID mice with targeted disruption of the IFN-γ receptor gene and mice with targeted disruption of the gene encoding inducible NO synthase to show that IFN-γ plays a role in the innate immunity to amebic liver abscess seen in SCID mice while NO is required for control of amebic liver abscess in immunocompetent mice.
ExoT of Cytotoxic
Pseudomonas aeruginosa
Prevents Uptake by Corneal Epithelial Cells
Authors: Cowell Brigitte A. , Chen David Y. , Frank Dara W. , Vallis Amy J. , Fleiszig Suzanne M. J. 
Published: May 2009

ABSTRACT

The presence of invasion-inhibitory activity that is regulated by the transcriptional activator ExsA of cytotoxic
Pseudomonas aeruginosa
has previously been proposed. The results of this study show that both ExoT and ExoS, known type III secreted effector proteins of
P. aeruginosa
that are regulated by ExsA, possess this activity. Invasion was reduced 94.4% by ExoT and 96.0% by ExoS. Invasion-inhibitory activity is not linked to ADP-ribosylation activity, at least for ExoS, since a noncatalytic mutant also inhibits uptake by an epithelial cell line (invasion was reduced 96.0% by ExoSE381A).
Resistance of Transgenic Mice Expressing Human Group II Phospholipase A2 toEscherichia coliInfection
Authors: Laine V. Jukka O. , Grass David S. , Nevalainen Timo J. 
Published: May 2009

ABSTRACTGroup II phospholipase A2 (PLA2) is a newly recognized antibacterial acute-phase protein. Recently we observed that transgenic mice expressing group II PLA2 (PLA2+mice) were able to resist experimentalStaphylococcus aureusinfection by killing the bacteria, as indicated by improved survival and by the small numbers of live bacteria in their tissues (V. J. O. Laine, D. S. Grass, and T. J. Nevalainen, J. Immunol. 162:7402–7408, 1999). To establish the role of group II PLA2 inEscherichia coliinfection, the host responses of PLA2+mice and their PLA2-deficient C57BL/6J littermates (PLA2−mice) were studied after intraperitoneal administration ofE. coli. The levels of group II PLA2 in sera of PLA2+mice increased after the administration ofE. coli, and the concentration of group II PLA2 correlated significantly with the catalytic activity of PLA2 in serum. PLA2+mice showed lower rates of mortality and less bacterial growth in peritoneal lavage fluid, blood, and spleen and liver tissues than PLA2−mice. Unlike the observations with staphylococcal infection, serum and peritoneal lavage fluid did not inhibit the growth ofE. coliin vitro. The results indicate that expression of the group IIPLA2transgene improves the host defense of mice againstE. coliinfection.
Cleavage of models for RNA mediated by a diZn(II) complex of bis[1,4-N1,N1′(1,5,9-triazacyclododecanyl)]butane in methanol and ethanol
Authors: Liu C. Tony , Melnychuk Stephanie A. , Liu Chaomin , Neverov Alexei A. , Brown R. Stan 
Published: May 2009

The cleavage of seven RNA model 2-hydroxypropyl aryl phosphates (1) catalyzed by a dinuclear Zn(II) complex of bis[1,4-N1,N1′(1,5,9-triazacyclododecanyl)]butane (4) was studied in methanol and ethanol at 25 °C under pH controlled conditions. The results are compared with what was reported earlier for the dinuclear Zn(II) complex of the lower homologue bis[1,3-N1,N1′(1,5,9-triazacyclododecanyl)]propane (3). In methanol, the higher homologue exhibits saturation binding with substrates having poor aryloxy leaving groups. With good leaving groups there is an observed linear dependence of kobs versus complex concentration without saturation binding over the catalyst concentration range investigated. In ethanol, strong saturation binding between the active form of the catalyst ((RO–):Zn(II)2:4) and all substrates is observed, the results observed in both solvents being similar to what was reported for the lower (RO–):Zn(II)2:3 homologue. Energetics calculations are presented for the (RO–):Zn(II)2:4-catalyzed cleavage of each substrate in both solvents to assess the catalytic efficiency via the ΔΔG‡ for catalyst binding a transition state comprising [RO–:1]‡ or its kinetic equivalent.
Chiral α-substituted allylboronates in a one-pot three-component asymmetric allylic alkylation/carbonyl allylation reaction sequence — Applications to the syntheses of (+)-(3R,5R)-3-hydroxy-5-decanolide and (–)-massoialactone
Authors: Carosi Lisa , Hall Dennis G. 
Published: May 2009

The use of different organomagnesium reagents in the copper-catalyzed allylic alkylation of 3-chloropropenyl boronates with chiral phosphoramidite ligands produces the desired α-substituted allylic boronate reagents in high regioselectivity and with modest to high enantioselectivities (up to 96% ee). The size of the incoming alkyl substituent from the organomagnesium reagent was found to impact the yield and selectivity of the allylic alkylation. A one-pot procedure for the preparation of these chiral allylic boronates followed by a Lewis acid (BF3) catalyzed addition to aldehydes delivers the desired allylboration products, homoallylic secondary alcohols, in good yields and very high diastereoselectivity. This three-component reaction methodology was applied to the syntheses of two lactone-containing natural products, (–)-massoialactone and (+)-(3R,5R)-3-hydroxy-5-decanolide. The key step of these syntheses involved the one-pot enantioselective copper-catalyzed allylic alkylation/allylboration reaction with a benzylic aldehyde, and afforded the desired product in 87% yield, 92% ee, and high E/Z selectivity in a ratio of 22:1. Remarkably, the allylic alkylation step of this sequential reaction was performed with a low catalyst loading of 2 mol% on a scale of >15 mmol that can provide multiple grams of the three-component product.
Fendiline-evoked [Ca2+]i rises and non-Ca2+-triggered cell death in human oral cancer cells
Authors: Huang CC , Huang CJ , Cheng JS , Liu SI , Chen IS , Tsai JY , Chou CT , Tseng PL , Jan CR 
Published: May 2009

The effect of fendiline on cytosolic free Ca2+concentrations ([Ca2+]i) and proliferation has not been explored in human oral cancer cells. This study examined whether fendiline altered Ca2+levels and caused cell death in OC2 human oral cancer cells. [Ca2+]iand cell viability were measured using the fluorescent dyes fura-2 and WST-1, respectively. Fendiline at concentrations above 10 μM increased [Ca2+]iin a concentration-dependent manner. The Ca2+signal was reduced partly by removing extracellular Ca2+. The fendiline-induced Ca2+influx was sensitive to blockade of L-type Ca2+channel blockers. In Ca2+-free medium, after pretreatment with 50 μM fendiline, 1 μM thapsigargin (an endoplasmic reticulum Ca2+pump inhibitor)-induced [Ca2+]irises were inhibited; and conversely, thapsigargin pretreatment nearly abolished fendiline-induced [Ca2+]irises. Inhibition of phospholipase C with 2 μM U73122 did not change fendiline-induced [Ca2+]irises. At concentrations between 5 and 25 μM, fendiline killed cells in a concentration-dependent manner. The cytotoxic effect of 15 μM fendiline was not reversed by prechelating cytosolic Ca2+with BAPTA/AM. Collectively, in OC2 cells, fendiline induced [Ca2+]irises by causing Ca2+release from the endoplasmic reticulum and Ca2+influx from L-type Ca2+channels. Furthermore, fendiline-caused cytotoxicity was not via a preceding [Ca2+]irise.
Ets1 and Ets2 are required for endothelial cell survival during embryonic angiogenesis
Authors: Wei Guo , Srinivasan Ruchika , Cantemir-Stone Carmen Z. , Sharma Sudarshana M. , Santhanam Ramasamy , Weinstein Michael , Muthusamy Natarajan , Man Albert K. , Oshima Robert G. , Leone Gustavo , Ostrowski Michael C. 
Published: May 2009

Abstract
The ras/Raf/Mek/Erk pathway plays a central role in coordinating endothelial cell activities during angiogenesis. Transcription factors Ets1 and Ets2 are targets of ras/Erk signaling pathways that have been implicated in endothelial cell function in vitro, but their precise role in vascular formation and function in vivo remains ill-defined. In this work, mutation of both Ets1 and Ets2 resulted in embryonic lethality at midgestation, with striking defects in vascular branching having been observed. The action of these factors was endothelial cell autonomous as demonstrated using Cre/loxP technology. Analysis of Ets1/Ets2 target genes in isolated embryonic endothelial cells demonstrated down-regulation of Mmp9, Bcl-XL, and cIAP2 in double mutants versus controls, and chromatin immunoprecipitation revealed that both Ets1 and Ets2 were loaded at target promoters. Consistent with these observations, endothelial cell apoptosis was significantly increased both in vivo and in vitro when both Ets1 and Ets2 were mutated. These results establish essential and overlapping functions for Ets1 and Ets2 in coordinating endothelial cell functions with survival during embryonic angiogenesis.