bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beryllium, an Adjuvant That Promotes Gamma Interferon Production
Authors: Lee Julia Y. , Atochina Olga , King Benjamin , Taylor Leslie , Elloso Merle , Scott Phillip , Rossman Milton D. 
Published: July 2002

ABSTRACTBeryllium is associated with a human pulmonary granulomatosis characterized by an accumulation of CD4+T cells in the lungs and a heightened specific lymphocyte proliferative response to beryllium (Be) with gamma interferon (IFN-γ) release (i.e., a T helper 1 [Th1] response). While an animal model of Be sensitization is not currently available, Be has exhibited adjuvant effects in animals. The effects of Be on BALB/c mice immunized with soluble leishmanial antigens (SLA) were investigated to determine if Be had adjuvant activity for IFN-γ production, an indicator of the Th1 response. In this strain ofLeishmania-susceptible BALB/c mice, a Th2 response is normally observed after in vivo SLA sensitization and in vitro restimulation with SLA. If interleukin-12 (IL-12) is given during in vivo sensitization with SLA, markedly increased IFN-γ production and decreased IL-4 production are detected. We show here that when beryllium sulfate (BeSO4) was added during in vivo sensitization of BALB/c mice with SLA and IL-12, significantly increased IFN-γ production and decreased IL-4 production from lymph node and spleen cells were detected upon in vitro SLA restimulation. No specific responses were observed to Be alone. Lymph node and spleen cells from all mice proliferated strongly and comparably upon in vitro restimulation with SLA and with SLA plus Be; no differences were noted among groups of mice that received different immunization regimens. In vivo, when Be was added to SLA and IL-12 for sensitization of BALB/c mice, more effective control ofLeishmaniainfection was achieved. This finding has implications for understanding not only the development of granulomatous reactions but also the potential for developing Be as a vaccine adjuvant.
Macrophage Inflammatory Protein 1α/CCL3 Is Required for Clearance of an AcuteKlebsiella pneumoniaePulmonary Infection
Authors: Lindell Dennis M. , Standiford Theodore J. , Mancuso Peter , Leshen Zachary J. , Huffnagle Gary B. 
Published: July 2002

ABSTRACTThe objective of these studies was to determine the role of macrophage inflammatory protein 1α/CCL3 in pulmonary host defense duringKlebsiella pneumoniaeinfection. Following intratracheal inoculation, 7-day survival of CCL3−/−mice was less than 10%, compared to 60% for CCL3+/+mice. Survival of CCR5−/−mice was equivalent to that of controls, indicating that the enhanced susceptibility of CCL3−/−mice toK. pneumoniaeis mediated via another CCL3 receptor, presumably CCR1. At day 3, CFU burden in the lungs of CCL3−/−mice was 800-fold higher than in CCL3+/+mice, demonstrating that CCL3 is critical for control of bacterial growth in the lung. Surprisingly, CCL3−/−mice had no differences in the recruitment of monocytes/macrophages and even showed enhanced neutrophil recruitment at days 1, 2, and 3 postinfection, compared to CCL3+/+mice. Therefore, the defect in clearance was not due to insufficient recruitment of leukocytes. No significant differences in cytokine levels of monocyte chemoattractant protein 1 (MCP-1), interleukin 12, gamma interferon, or tumor necrosis factor alpha in lung lavages were found between CCL3+/+and CCL3−/−mice. CCL3−/−alveolar macrophages were found to have significantly lower phagocytic activity towardK. pneumoniaethan CCL3+/+alveolar macrophages. These findings demonstrate that CCL3 production is critical for activation of alveolar macrophages to control the pulmonary growth of the gram-negative bacteriumK. pneumoniae.
Comparison of Genomic Structures and Antigenic Reactivities of Orthologous 29-Kilodalton Outer Membrane Proteins of
Helicobacter pylori
Authors: Sumie Akihiro , Yamashiro Tetsu , Nakashima Kazutoshi , Nasu Masaru , Watanabe Makoto , Nishizono Akira 
Published: July 2002

ABSTRACT

We purified a 29-kDa
Helicobacter pylori
outer membrane protein (Omp29 protein) and cloned the gene encoding the protein from
H. pylori
strain ATCC 43504. The Omp29 gene corresponded to the reported JHP73 and the HP78–79 genes of
H. pylori
strains. A corresponding nucleotide fragment was detected in all 150 tested
H. pylori
clinical isolates by PCR or Southern blotting. The amplified Omp29-corresponding fragments were categorized into a ca. 770-bp-long group and a larger-fragment group. Sequence analysis indicated that the larger fragments were likely synthesized from the 770-bp fragments by insertion of an irrelevant fragment via 17-bp-long repeat sequences. Immunoblot analysis implies that the ca. 770-bp fragment is responsible for the protein homologous to Omp29, whereas the larger fragments are not responsible for those proteins or encoding antigenically distinct proteins. We postulate that the
H. pylori
outer membrane protein Omp29 can alter its antigenicity through gene modifications mediated by nucleotide transfer.
Interactions ofNeisseria gonorrhoeaewith Mature Human Macrophage Opacity Proteins Influence Production of Proinflammatory Cytokines
Authors: Makepeace Benjamin L. , Watt Peter J. , Heckels John E. , Christodoulides Myron 
Published: July 2002

ABSTRACTThe pathological features of ascending gonococcal infection suggest that proinflammatory mediators secreted by tissue-resident macrophages are important components of the host response. Challenge of fully differentiated, mature macrophages with variants ofNeisseria gonorrhoeaestrain P9 or purified bacterial surface components (pili, lipooligosaccharide, and outer membrane vesicles) induced the secretion of interleukin 6 (IL-6), tumor necrosis factor alpha, growth-related protein α, macrophage inflammatory protein 1α (MIP-1α), and RANTES cytokines but had no effect on IL-8 production. No secretion of IL-1β, epithelial-derived neutrophil attractant 78, granulocyte-macrophage colony-stimulating factor, IL-10, or IL-12 cytokines was observed. Notably, the P9-Opabprotein, in comparison to P9-Opaa, increased the association of gonococci with macrophages and elevated the secretion of cytokines. Thus, variation in Opa protein expression by the gonococcus may be a determining factor in the severity of pelvic inflammatory disease.
Porphyromonas gingivalis
Gingipains and Adhesion to Epithelial Cells
Authors: Chen Tsute , Nakayama Koji , Belliveau Lynn , Duncan Margaret J. 
Published: July 2002

ABSTRACT

Porphyromonas gingivalis
is one of the principal organisms associated with adult periodontitis. Bacterial surface proteins such as fimbriae and gingipain hemagglutinin domains have been implicated as adhesins that actuate colonization of epithelium lining the gingival sulcus. We investigated the genetics of
P. gingivalis
adhesion to monolayers of epithelial cells using wild-type and gingipain mutant strains. These experiments suggested that arginine-specific gingipain (Rgp) catalytic activity modulated adhesion. From the data obtained with
rgp
mutants, we constructed a working hypothesis predicting that attachment and detachment of
P. gingivalis
to epithelial cells were mediated by gingipain adhesin and Rgp catalytic domains, respectively. A membrane-based epithelial cell binding assay, used to locate adhesins in extracellular fractions of wild-type and mutant strains, recognized gingipain peptides as adhesins rather than fimbriae. We developed a capture assay that demonstrated the binding of gingipain adhesin peptides to oral epithelial cells. The adherence of fimbrillin to epithelial cells was detected after heat denaturation of cell fractions. The prediction that Rgp catalytic activities mediated detachment was substantiated when the high level of attachment of an
rgp
mutant was reduced in the presence of wild-type cell fractions that contained gingipain catalytic activities.
Immunogenicity and Protective Efficacy of aPlasmodium yoeliiHsp60 DNA Vaccine in BALB/c Mice
Authors: Sanchez Gloria I. , Sedegah Martha , Rogers William O. , Jones Trevor R. , Sacci John , Witney Adam , Carucci Daniel J. , Kumar Nirbhay , Hoffman Stephen L. 
Published: July 2002

ABSTRACTThe gene encoding the 60-kDa heat shock protein ofPlasmodium yoelii(PyHsp60) was cloned into the VR1012 and VR1020 mammalian expression vectors. Groups of 10 BALB/c mice were immunized intramuscularly at 0, 3, and 9 weeks with 100 μg of PyHsp60 DNA vaccine alone or in combination with 30 μg of pmurGMCSF. Sera from immunized mice but not from vector control groups recognizedP. yoeliisporozoites, liver stages, and infected erythrocytes in an indirect fluorescent antibody test. Two weeks after the last immunization, mice were challenged with 50P. yoeliisporozoites. In one experiment the vaccine pPyHsp60-VR1012 used in combination with pmurGMCSF gave 40% protection (Fisher's exact test;P= 0.03, vaccinated versus control groups). In a second experiment this vaccine did not protect any of the immunized mice but induced a delay in the onset of parasitemia. In neither experiment was there any evidence of a protective effect against the asexual erythrocytic stage of the life cycle. In a third experiment mice were primed with PyHsp60 DNA, were boosted 2 weeks later with 2 × 103irradiatedP. yoeliisporozoites, and were challenged several weeks later. The presence of PyHsp60 in the immunization regimen did not lead to reduced blood-stage infection or development of parasites in hepatocytes. PyHsp60 DNA vaccines were immunogenic in BALB/c mice but did not consistently, completely protect against sporozoite challenge. The observation that in some of the PyHsp60 DNA vaccine-immunized mice there was protection against infection or a delay in the onset of parasitemia after sporozoite challenge deserves further evaluation.
Mutation of the Gene Encoding Cytotoxic Necrotizing Factor Type 1 (cnf1) Attenuates the Virulence of UropathogenicEscherichia coli
Authors: Rippere-Lampe Karen E. , O'Brien Alison D. , Conran Richard , Lockman Hank A. 
Published: July 2002

ABSTRACTCytotoxic necrotizing factor type 1 (CNF1) is a 115-kDa toxin that activates Rho GTPases and is produced by uropathogenicEscherichia coli(UPEC). While both epidemiological studies that link CNF1 production byE. coliwith urinary tract disease and the cytopathic effects of CNF1 on cultured urinary tract cells are suggestive of a role for the toxin as a UPEC virulence factor, few in vivo studies to test this possibility have been reported. Therefore, in this investigation, we evaluated the importance of CNF1 in a murine model of urinary tract infection (UTI) by comparing the degree of colonization and damage induced by three different CNF1-producingE. colistrains with isogenic CNF1-deficient derivatives. The data from single-strain challenge experiments with C3H/HeOuJ mice indicated a trend toward higher counts of the wild-type strains in the urine and bladders of these animals up to 3 days after challenge in two of three strain pairs. Furthermore, this difference was statistically significant at day 2 of infection with one strain pair, C189 and C189cnf1. To control for the animal-to-animal variability inherent in this model, we infected C3H/HeOuJ mice with a mixture of CNF1-positive and -negative isogenic derivatives of CP9. The CNF1-positive strain was recovered in higher numbers than the CNF1-negative strain in the urine, bladders, and kidneys of the mice up to 9 days postinfection. These striking coinfection findings, taken with the trends observed in single-strain infections, led us to conclude that CNF1-negative strains were generally attenuated compared to the wild type in the C3H/HeOuJ mouse model of UTI. Furthermore, histopathological examination of bladder specimens from mice infected with CNF1-positive strains consistently showed deeper, more extensive inflammation than in those infected with the isogenic mutants. Lastly, we found that CNF1-positive strain CP9 was better able to resist killing by fresh human neutrophils than were CP9cnf1bacteria. From these data in aggregate, we propose that CNF1 production increases the capacity of UPEC strains to resist killing by neutrophils, which in turn permits these bacteria to gain access to deeper tissue and persist better in the lower urinary tract.
In Vivo Clearance of an Intracellular Bacterium,Francisella tularensisLVS, Is Dependent on the p40 Subunit of Interleukin-12 (IL-12) but Not on IL-12 p70
Authors: Elkins Karen L. , Cooper Allison , Colombini Susan M. , Cowley Siobhán C. , Kieffer Tara L. 
Published: July 2002

ABSTRACTTo determine the role of interleukin-12 (IL-12) in primary and secondary immunity to a model intracellular bacterium, we have comprehensively evaluated infection withFrancisella tularensisLVS in three murine models of IL-12 deficiency. Mice lacking the p40 protein of IL-12 (p40 knockout [KO] mice) and mice treated in vivo with neutralizing anti-IL-12 antibodies survived large doses of primary and secondary LVS infection but never cleared bacteria and exhibited a chronic infection. In dramatic contrast, mice lacking the p35 protein (p35 KO mice) of heterodimeric IL-12 readily survived large doses of primary sublethal LVS infection as well as maximal secondary lethal challenge, with only a slight delay in clearance of bacteria. LVS-immune wild-type (WT) lymphocytes produced large amounts of gamma interferon (IFN-γ), but p35 KO and p40 KO lymphocytes produced much less; nonetheless, similar amounts of NO were found in all cultures containing immune lymphocytes, and all immune lymphocytes were equally capable of controlling intracellular growth of LVS in vitro. Purified CD4+and CD8+T cells from both WT and p40 KO mice controlled intracellular growth, even though T cells from WT mice produced much more IFN-γ than those from p40 KO mice, and p40 KO T cells did not adopt a Th2 phenotype. Thus, while IL-12 p70 stimulation of IFN-γ production may be important for bacteriostasis, IL-12 p70 is not necessary for appropriate development of LVS-immune T cells that are capable of controlling intracellular bacterial growth and for clearance of primary or secondary LVS infection. Instead, an additional mechanism dependent on the IL-12 p40 protein, either alone or in another complex such as the newly discovered heterodimer IL-23, appears to be responsible for actual clearance of this intracellular bacterium.
Comparative and Genetic Analyses of the Putative
Vibrio cholerae
Lipopolysaccharide Core Oligosaccharide Biosynthesis (
wav
) Gene Cluster
Authors: Nesper Jutta , Kraiß Anita , Schild Stefan , Blaβ Julia , Klose Karl E. , Bockemühl Jochen , Reidl Joachim 
Published: July 2002

ABSTRACT

We identified five different putative
wav
gene cluster types, which are responsible for the synthesis of the core oligosaccharide (OS) region of
Vibrio cholerae
lipopolysaccharide. Preliminary evidence that the genes encoded by this cluster are involved in core OS biosynthesis came from analysis of the recently released O1 El Tor
V. cholerae
genome sequence and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of O1 El Tor mutant strains defective in three genes (
waaF
,
waaL
, and
wavB
). Investigations of 38 different
V. cholerae
strains by Southern blotting, PCR, and sequencing analyses showed that the O1 El Tor
wav
gene cluster type is prevalent among clinical isolates of different serogroups associated with cholera and environmental O1 strains. In contrast, we found differences in the
wav
gene contents of 19 unrelated non-O1, non-O139 environmental and human isolates not associated with cholera. These strains contained four new
wav
gene cluster types that differ from each other in distinct gene loci, providing evidence for horizontal transfer of
wav
genes and for limited structural diversity of the core OS among
V. cholerae
isolates. Our results show genetic diversity in the core OS biosynthesis gene cluster and predominance of the type 1
wav
gene locus in strains associated with clinical cholera, suggesting that a specific core OS structure could contribute to
V. cholerae
virulence.
ideR
, an Essential Gene in
Mycobacterium tuberculosis
: Role of IdeR in Iron-Dependent Gene Expression, Iron Metabolism, and Oxidative Stress Response
Authors: Rodriguez G. Marcela , Voskuil Martin I. , Gold Benjamin , Schoolnik Gary K. , Smith Issar 
Published: July 2002

ABSTRACT

The mycobacterial IdeR protein is a metal-dependent regulator of the DtxR (diphtheria toxin repressor) family. In the presence of iron, it binds to a specific DNA sequence in the promoter regions of the genes that it regulates, thus controlling their transcription. In this study, we provide evidence that
ideR
is an essential gene in
Mycobacterium tuberculosis. ideR
cannot normally be disrupted in this mycobacterium in the absence of a second functional copy of the gene. However, a rare
ideR
mutant was obtained in which the lethal effects of
ideR
inactivation were alleviated by a second-site suppressor mutation and which exhibited restricted iron assimilation capacity. Studies of this strain and a derivative in which IdeR expression was restored allowed us to identify phenotypic effects resulting from
ideR
inactivation. Using DNA microarrays, the iron-dependent transcriptional profiles of the wild-type,
ideR
mutant, and
ideR
-complemented mutant strains were analyzed, and the genes regulated by iron and IdeR were identified. These genes encode a variety of proteins, including putative transporters, proteins involved in siderophore synthesis and iron storage, members of the PE/PPE family, a membrane protein involved in virulence, transcriptional regulators, and enzymes involved in lipid metabolism.
Mycobacterium tuberculosisCDC1551 Is Resistant to Reactive Nitrogen and Oxygen Intermediates In Vitro
Authors: Firmani Marcia A. , Riley Lee W. 
Published: July 2002

ABSTRACTResistance to reactive oxygen intermediates and reactive nitrogen intermediates in vitro of a clinical isolate ofMycobacterium tuberculosis(CDC1551) that caused a large outbreak of tuberculosis was compared to that ofM. tuberculosisstrains CB3.3, H37Rv, H37Ra, Erdman, RJ2E, C.C. 13, and C.C. 22 as well asM. bovisstrains Ravenel and BCG. CDC1551 and CB3.3 were significantly more resistant to both hydrogen peroxide (H2O2) and acidified sodium nitrite than were the other strains tested. This biological phenotype may serve as an in vitro marker for clinical strains ofM. tuberculosislikely to cause a large outbreak of tuberculosis.
Positioning of Region 4 of the
Escherichia coli
RNA Polymerase ς
70
Subunit by a Transcription Activator
Authors: Bown Jonathan A. , Kolb Annie , Meares Claude F. , Ishihama Akira , Minchin Stephen D. , Busby Stephen J. W. 
Published: July 2002

ABSTRACT

A DNA cleavage reagent, specifically tethered to residue 581 of the
Escherichia coli
RNA polymerase ς
70
subunit, has been used to investigate the location of ς
70
region 4 in different complexes at the
galp
1
promoter and the effect of the cyclic AMP receptor protein. The positions of DNA cleavage by the reagent are not affected by the cyclic AMP receptor protein. We conclude that transcription activation at the
galp
1
promoter by the cyclic AMP receptor protein does not involve major conformation changes in or repositioning of ς
70
region 4.
Covariance of Complementary rRNA Loop Nucleotides Does Not Necessarily Represent Functional Pseudoknot Formation In Vivo
Authors: Chernyaeva Natalya S. , Murgola Emanuel J. 
Published: July 2002

ABSTRACT

We examined mutationally a two-hairpin structure (nucleotides 57 to 70 and 76 to 110) in a region of domain I of
Escherichia coli
23S rRNA that has been implicated in specific functions in protein synthesis by other studies. On the basis of the observed covariance of several nucleotides in each loop in
Bacteria
,
Archaea
, and chloroplasts, the two hairpins have been proposed to form a pseudoknot. Here, appropriate loop changes were introduced in vitro by site-directed mutagenesis to eliminate any possibility of base pairing between the loops. The bacterial cells containing each cloned mutant rRNA operon were then examined for cell growth, termination codon readthrough, and assembly of the mutant rRNAs into functional ribosomes. The results show that, under the conditions examined, the two hairpins do not form a pseudoknot structure that is required for the functioning of the ribosome in vivo and therefore that sequence covariance does not necessarily indicate the formation of a functional pseudoknot.
High-Frequency Flp Recombinase-Mediated Inversions of the
oriC
-Containing Region of the
Pseudomonas aeruginosa
Genome
Authors: Barekzi Nazir , Beinlich Kerry , Hoang Tung T. , Pham Xuan-Quynh , Karkhoff-Schweizer RoxAnn , Schweizer Herbert P. 
Published: July 2002

ABSTRACT

The genomes of the two clonally derived
Pseudomonas aeruginosa
prototypic strains PAO1 and DSM-1707 differ by the presence of a 2.19-Mb inversion including
oriC
. Integration of two Flp recombinase target sites near the
rrn
operons containing the inversion endpoints in PAO1 led to Flp-catalyzed inversion of the intervening 1.59-Mb fragment, including
oriC
, at high frequencies (83%), favoring the chromosome configuration found in DSM-1707. The results indicate that the
oriC
-containing region of the
P. aeruginosa
chromosome can readily undergo and tolerate large inversions.
Single-Molecule Imaging of Interaction between Dextran and Glucosyltransferase from
Streptococcus sobrinus
Authors: Kaseda Kuniyoshi , Yokota Hiroaki , Ishii Yoshiharu , Yanagida Toshio , Inoue Tetsuyoshi , Fukui Kazuhiro , Kodama Takao 
Published: July 2002

ABSTRACT

Using total internal reflection fluorescence microscopy, we directly observed the interaction between dextran and glucosyltransferase I (GTF) of
Streptococcus sobrinus
. Tetramethylrhodamine (TMR)-labeled GTF molecules were individually imaged as they were associating with and then dissociating from the dextran fixed on the glass surface in the evanescent field. Similarly dynamic behavior of TMR-labeled dextran molecules was also observed on the GTF-fixed surface. The duration of the stay on the surface (dwell time) was measured for each of these molecules by counting the number of video frames that had recorded the image. A histogram of dwell time for a population of several hundred molecules indicated that the GTF-dextran interaction obeyed an apparent first-order kinetics. The rate constrants estimated for TMR-labeled GTF at pH 6.8 and 25°C in the absence and presence of sucrose were 9.2 and 13.3 s
−1
, respectively, indicating that sucrose accelerated the dissociation of GTF from dextran. However, the accelerated rate was still much lower than the catalytic center activity of GTF (≥25 s
−1
) under comparable conditions.
Methylotrophic
Methylobacterium
Bacteria Nodulate and Fix Nitrogen in Symbiosis with Legumes
Authors: Sy Abdoulaye , Giraud Eric , Jourand Philippe , Garcia Nelly , Willems Anne , de Lajudie Philippe , Prin Yves , Neyra Marc , Gillis Monique , Boivin-Masson Catherine , Dreyfus Bernard 
Published: July 2002

ABSTRACT

Rhizobia described so far belong to three distinct phylogenetic branches within the α-2 subclass of
Proteobacteria
. Here we report the discovery of a fourth rhizobial branch involving bacteria of the
Methylobacterium
genus. Rhizobia isolated from
Crotalaria
legumes were assigned to a new species, “
Methylobacterium nodulans
,” within the
Methylobacterium
genus on the basis of 16S ribosomal DNA analyses. We demonstrated that these rhizobia facultatively grow on methanol, which is a characteristic of
Methylobacterium
spp. but a unique feature among rhizobia. Genes encoding two key enzymes of methylotrophy and nodulation, the
mxaF
gene, encoding the α subunit of the methanol dehydrogenase, and the
nodA
gene, encoding an acyltransferase involved in Nod factor biosynthesis, were sequenced for the type strain, ORS2060. Plant tests and
nodA
amplification assays showed that “
M. nodulans
” is the only nodulating
Methylobacterium
sp. identified so far. Phylogenetic sequence analysis showed that “
M. nodulans
” NodA is closely related to
Bradyrhizobium
NodA, suggesting that this gene was acquired by horizontal gene transfer.