bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development, Validation, and Application of PCR Primers for Detection of Tetracycline Efflux Genes of Gram-Negative Bacteria
Authors: Aminov R. I. , Chee-Sanford J. C. , Garrigues N. , Teferedegne B. , Krapac I. J. , White B. A. , Mackie R. I. 
Published: July 2002

ABSTRACT

Phylogenetic analysis of tetracycline resistance genes, which confer resistance due to the efflux of tetracycline from the cell catalyzed by drug:H
+
antiport and share a common structure with 12 transmembrane segments (12-TMS), suggested the monophyletic origin of these genes. With a high degree of confidence, this
tet
subcluster unifies 11 genes encoding
tet
efflux pumps and includes
tet
(A),
tet
(B),
tet
(C),
tet
(D),
tet
(E),
tet
(G),
tet
(H),
tet
(J),
tet
(Y),
tet
(Z), and
tet
(30). Phylogeny-aided alignments were used to design a set of PCR primers for detection, retrieval, and sequence analysis of the corresponding gene fragments from a variety of bacterial and environmental sources. After rigorous validation with the characterized control
tet
templates, this primer set was used to determine the genotype of the corresponding tetracycline resistance genes in total DNA of swine feed and feces and in the lagoons and groundwater underlying two large swine production facilities known to be impacted by waste seepage. The compounded
tet
fingerprint of animal feed was found to be
tetCDEHZ
, while the corresponding fingerprint of total intestinal microbiota was
tetBCGHYZ
. Interestingly, the
tet
fingerprints in geographically distant waste lagoons were identical (
tetBCEHYZ
) and were similar to the fecal fingerprint at the third location mentioned above. Despite the sporadic detection of chlortetracycline in waste lagoons, no auxiliary diversity of
tet
genes in comparison with the fecal diversity could be detected, suggesting that the
tet
pool is generated mainly in the gut of tetracycline-fed animals, with a negligible contribution from selection imposed by tetracycline that is released into the environment. The
tet
efflux genes were found to be percolating into the underlying groundwater and could be detected as far as 250 m downstream from the lagoons. With yet another family of
tet
genes, this study confirmed our earlier findings that the antibiotic resistance gene pool generated in animal production systems may be mobile and persistent in the environment with the potential to enter the food chain.
Development, Characterization, and Diagnostic Applications of Monoclonal Antibodies against Bovine Rotavirus
Authors: Al-Yousif Yousif , Al-Majhdi Fahad , Chard-Bergstrom Cindy , Anderson Joe , Kapil Sanjay 
Published: July 2002

ABSTRACT
Hybridomas secreting monoclonal antibodies (MAbs) against the Nebraska calf diarrhea strain of bovine rotavirus (BRV) were characterized. Indirect fluorescent-antibody assay, immunodot assay, and immunoprecipitation were used to select hybridomas that produced anti-BRV MAbs. Seven of the MAbs were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot assay to be reactive with the BRV outer capsid protein, VP7, which has a molecular mass of 37.5 kDa. None of the seven MAbs were reactive with canine rotavirus, bovine coronavirus, or uninfected Madin-Darby bovine kidney cells. Two clones, 8B4 (immunoglobulin G2a [IgG2a]) and 2B11 (IgG1), were found suitable for use in an antigen capture enzyme-linked immunosorbent assay for detecting BRV in bovine fecal samples. Both were subtype A specific (G6 subtype) but did not react with all isolates of BRV group A.
Porins and Lipopolysaccharide Induce Apoptosis in Human Spermatozoa
Authors: Gorga Fernanda , Galdiero Marilena , Buommino Elisabetta , Galdiero Emilia 
Published: July 2002

ABSTRACTTreatment of human spermatozoa with porins or lipopolysaccharide (LPS) increases spontaneous apoptosis in these cells. Porins and LPS were extracted fromSalmonella entericaserovar Typhimurium andPasteurella multocidaand were mixed with human spermatozoa for detection of levels of apoptosis.
Biological Response Modifier Activity of an Exopolysaccharide fromPaenibacillus jamilaeCP-7
Authors: Ruiz-Bravo Alfonso , Jimenez-Valera Maria , Moreno Encarnacion , Guerra Victor , Ramos-Cormenzana Alberto 
Published: July 2002

ABSTRACTAn extracellular polysaccharide was purified from culture supernatants ofPaenibacillus jamilaeCP-7, a gram-positive bacillus that was isolated from compost prepared with olive mill wastewaters. The extracellular polysaccharide was produced under aerobic conditions in a medium containing olive mill wastewaters (80% [vol/vol]). This exopolymer had a low level of acute toxicity when it is administered to BALB/c mice by the intraperitoneal route. Interesting immunomodulatory effects were detected when mice were given 10 mg of exopolysaccharide per kg of body weight; the proliferative responses of splenocytes to B-cell and T-cell mitogens were suppressed, the in vitro levels of production of gamma interferon and granulocyte-macrophage colony-stimulating factor by unstimulated and lipopolysaccharide-stimulated splenocytes were enhanced, and the levels of resistance to the intracellular pathogenListeria monocytogeneswas increased in mice. Also, the exopolysaccharide was able to induce lymphocyte proliferation in vitro. We conclude thatP. jamilaeproduces an exopolysaccharide with interesting immunomodulatory properties.
STAT4 Is Required for Antibacterial Defense but Enhances Mortality during Polymicrobial Sepsis
Authors: Godshall Christopher J. , Lentsch Alex B. , Peyton James C. , Scott Melanie J. , Cheadle William G. 
Published: July 2002

ABSTRACTThe signal transducer and activator of transcription factor 4 (STAT4) pathway mediates the intracellular effects of interleukin-12 (IL-12), leading to the production of gamma interferon, induction of a T helper type 1 response, and increased natural killer cell cytotoxicity. The purpose of this study was to determine the role of the STAT4 pathway during polymicrobial peritonitis in the cecal ligation and puncture (CLP) model. CLP was performed on STAT4-deficient (STAT4−/−) and wild-type control (BALB/c) mice. At 4 h after CLP, STAT4−/−mice had significantly higher bacterial counts in the peritoneal lavage fluid, liver, and blood. This difference persisted for 18 h in the peritoneal lavage fluid and blood. Neutrophil migration to the site of infection and into remote tissues was unaffected. Despite higher bacterial counts locally and systemically, STAT4−/−mice had a lower mortality rate than BALB/c controls. In contrast, blockade of IL-12 in BALB/c mice was detrimental to host survival. A blunted serum IL-12 response at 18 h after CLP was exhibited in STAT4−/−mice. These results suggest several critical roles for the STAT4 pathway in the resolution of polymicrobial infections. Additionally, the disparate effects observed with IL-12 blockade and STAT4 deficiency on host survival suggest that IL-12 may activate alternate pathways promoting survival.
Cytokine Profiles of Pediatric Patients Treated with Antibiotics for Pyelonephritis: Potential Therapeutic Impact
Authors: Kassir Kari , Vargas-Shiraishi Ofelia , Zaldivar Frank , Berman Monique , Singh Jasjit , Arrieta Antonio 
Published: July 2002

ABSTRACT

Urinary tract infections are common in infants and children. Pyelonephritis may result in serious complications, such as renal scarring, hypertension, and renal failure. Identification of the timing of release of inflammatory cytokines in relation to pyelonephritis and its treatment is essential for designing interventions that would minimize tissue damage. To this end, we measured urinary cytokine concentrations of interleukin-1β (IL-1β), IL-6, and IL-8 in infants and children with pyelonephritis and in healthy children. Children that presented to our institution with presumed urinary tract infection were given the diagnosis of pyelonephritis if they had a positive urine culture, pyuria, and one or more of the following indicators of systemic involvement: fever, elevated peripheral white blood cell count, or elevated C-reactive protein. Urine samples were obtained at the time of presentation prior to the administration of antibiotics, immediately after completion of the first dose of antibiotics, and at follow up 12 to 24 h after presentation. IL-1β, IL-6, and IL-8 concentrations were measured by enzyme-linked immunosorbent assay. Creatinine concentrations were also determined, and cytokine/creatinine ratios were calculated to standardize samples. Differences between preantibiotic and follow-up cytokine/creatinine ratios were significant for IL-1β, IL-6, and IL-8 (
P
< 0.01). Differences between preantibiotic and control cytokine/creatinine ratios were also significant for IL-1β, IL-6, and IL-8 (
P
< 0.01). Our study revealed that the urinary tract cytokine response to infection is intense but dissipates shortly after the initiation of antibiotic treatment. This suggests that renal damage due to inflammation begins early in infection, underscoring the need for rapid diagnosis and intervention.
Exposure of HEp-2 Cells to Stress Conditions Influences Antinuclear Antibody Reactivity
Authors: Du Liping , Fukushima Sachiko , Sallmyr Annahita , Manthorpe Rolf , Bredberg Anders 
Published: July 2002

ABSTRACT
This study of stress-related antinuclear antibody (ANA) reactivity was undertaken with the objective of improving clinical ANA testing. ANA was determined by parallel enzyme-linked immunosorbent assays of crude nuclear protein antigen extracted from HEp-2 cells either grown under optimal conditions (providing nonstress ANA antigen) or exposed to stress (providing stress ANA antigen). The stress stimuli used were gamma radiation (causing DNA damage) and a hypertonic environment (causing apoptosis). Signs of stress-related ANA reactivity were seen among connective tissue disease (CTD) patients (including patients with systemic lupus erythematosus; mixed CTD; calcinosis, Reynaud's phenomenon, esophageal motility disorders, sclerodactyly, and telangiectasia; scleroderma; and Sjögren's syndrome): 11% showed stress-positive ANA (i.e., a significantly stronger ANA reactivity with the extract from stressed cells), whereas 21% showed a markedly weaker reaction with the stress antigen. In contrast, among ANA screening patient sera, with no diagnosis of CTD, the fraction showing stress-positive ANA was higher (7 to 8%, depending on the type of stress) than among those showing a lower reactivity with stress antigen (1.5 to 2.5%). Only one serum among 89 (1%) tested sera from healthy individuals showed a stress-related ANA reaction. This demonstration of stress-related ANA suggests a means to improve the performance of clinical ANA testing.
Helicobacter pylori
Seroprevalence in Asymptomatic Pregnant Women in France
Authors: Kalach N. , Desramé J. , Bonnet C. , Commegeille P. , Couturier D. , Chaussade S. , Hance P. , Dupont C. , Raymond J. 
Published: July 2002

ABSTRACT

The purpose of our study was to evaluate the incidence of
Helicobacter pylori
seropositivity in two different populations of asymptomatic pregnant women from different geographic origins during two separate time periods. A retrospective study of consecutive sera obtained from 169 and 302 asymptomatic pregnant women in 1990 and 1999, respectively, was carried out. The global
H. pylori
seroprevalences for 1990 and 1999 were 21.3 and 21.5% (where
P
is nonsignificant), respectively. For both periods the
H. pylori
seroprevalences were significantly higher in non-French pregnant women (66.6 and 50.6%) than in French pregnant women (18.7 and 11.2%) (
P
= 0.01 and 0.001, respectively).
H. pylori
seroprevalence in French pregnant women decreased significantly from the first period (18.7%) to the second one (11.2%) (
P
= 0.03).
CD8+T-Cell Priming against a NonsecretedListeria monocytogenesAntigen Is Independent of the Antimicrobial Activities of Gamma Interferon
Authors: Tvinnereim Amy R. , Harty John T. 
Published: July 2002

ABSTRACTSublethal infection of mice with recombinantListeria monocytogenesexpressing a model epitope in either secreted or nonsecreted form results in similar CD8+T-cell priming. Since nonsecreted bacterial proteins have no obvious access to the endogenous major histocompatibility complex (MHC) class I presentation pathway, presentation of these antigens requires destruction of the bacterium to reveal the nonsecreted molecules to an exogenous MHC class I presentation pathway. Gamma interferon (IFN-γ), a cytokine made by multiple cell types in response toL. monocytogenesinfection, could be required for exogenous presentation of nonsecreted bacterial antigens via its capacity to upregulate the expression of molecules involved in antigen presentation, its capacity to activate macrophages to kill bacteria to expose nonsecreted molecules or both. IFN-γ knockout (KO) mice were used to address the requirement for IFN-γ in CD8+T-cell priming against (i) a model exogenous antigen and (ii) secreted and nonsecretedL. monocytogenesantigens. We demonstrate that IFN-γ KO mice are capable of cross-presenting the model exogenous antigen ovalbumin to prime CD8+T-cell responses that are only slightly weaker than that in wild-type (WT) mice. Despite their extreme susceptibility to primaryL. monocytogenesinfection, previously immunized and naive IFN-γ KO mice were able to generate CD8+T-cell responses against both secreted and nonsecretedL. monocytogenesantigens which were similar to responses of WT mice. Interestingly, IFN-γ KO mice were as capable as WT mice in mediating the characteristic drop in bacterial load in the liver at 4 h postinfection, although the IFN-γ KO mice have exacerbated bacterial loads as early as 24 h postinfection. These results demonstrate that the regulatory functions of IFN-γ are not required for priming of CD8+T cells by cross-presentation of a model exogenous antigen or in response to a nonsecretedL. monocytogenesantigen. In addition, the capacity of IFN-γ to activate the microbicidal activities of macrophages is not required for the very early innate immune response toL. monocytogenesor priming of CD8+T cells against a nonsecreted bacterial antigen.
Lipopolysaccharide-Induced Gelatinase Granule Mobilization Primes Neutrophils for Activation by Galectin-3 and Formylmethionyl-Leu-Phe
Authors: Almkvist Jenny , Fäldt Jenny , Dahlgren Claes , Leffler Hakon , Karlsson Anna 
Published: July 2002

ABSTRACTWe have earlier shown that galectin-3, a lactose-binding mammalian lectin that is secreted from activated macrophages, basophils, and mast cells, induces activation of the NADPH oxidase in exudated but not in peripheral blood neutrophils (A. Karlsson, P. Follin, H. Leffler, and C. Dahlgren, Blood 91:3430–3438, 1998). The alteration in responsiveness occurring during extravasation correlated with mobilization of the gelatinase and/or specific granules to the cell surface, indicating a role for mobilizable galectin-3 receptors. In this study we have investigated galectin-3-induced NADPH oxidase activation, measured as superoxide production, in lipopolysaccharide (LPS)-primed neutrophils. Upon galectin-3 challenge, the LPS-primed cells produced superoxide, both extracellularly and intracellularly. A primed extracellular response to formylmethionyl-Leu-Phe (fMLF) was also achieved. The exposure of complement receptors 1 and 3 as well as the formyl peptide receptor on the cell surface was markedly increased after LPS treatment, indicating that granule fusion with the plasma membrane had occurred. Further assessment of specific markers for neutrophil granules showed that the LPS treatment had mobilized the gelatinase granules but only a minor fraction of the specific granules. We thus suggest that the mechanism behind LPS priming lies at the level of granule (receptor) mobilization for galectin-3 as well as for fMLF.
Mutagenesis and Functional Reconstitution of Chlamydial Major Outer Membrane Proteins: VS4 Domains Are Not Required for Pore Formation but Modify Channel Function
Authors: Hughes E. S. , Shaw K. M. , Ashley R. H. 
Published: July 2002

ABSTRACTChlamidial organisms are obligate intracellular pathogens containing highly antigenic porin-like major outer membrane proteins (MOMPs). MOMP epitopes are of substantial medical interest, and they cluster within four relatively short variable (VS) domains. If MOMPs adopt a β-barrel fold, like bacterial porins, the VS domains may form extramembranous loops and the conserved regions of the protein may correspond to predicted membrane-located β-strands. However, molecular studies on native MOMPs have been hampered by the need to culture chlamydiae in eukaryotic host cells and purification and reconstitution remain problematic. In addition, the organisms are difficult to manipulate genetically, and it has also been difficult to functionally reconstitute recombinant MOMPs. To help overcome these problems and improve our understanding of MOMP structure and function, we cloned and expressedC. trachomatisandC. psittaciMOMPs and functionally reconstituted them at the single-channel level. We measured significant functional differences between the two proteins, and by removing and exchanging VS4, we tested the hypothesis that the largest variable domain forms an extramembranous loop that contributes to these differences. Proteins in which VS4 was deleted continued to form functional ion channels, consistent with the idea that the domain forms an extramembranous protein loop and incompatible with models in which it contributes to predicted membrane-located β-strands. Additionally, the properties of the chimeric proteins strongly suggested that the VS4 domain interacts closely with other regions of the protein to form the channel entrance or vestibule. Our approach can be used to probe structure-function relationships in chlamydial MOMPs and may have implications for the generation of effective antichlamydial vaccines.
Selection of Virulence-Associated Determinants of
Streptococcus suis
Serotype 2 by In Vivo Complementation
Authors: Smith Hilde E. , Buijs Herma , Wisselink Henk J. , Stockhofe-Zurwieden Norbert , Smits Mari A. 
Published: July 2002

ABSTRACT

Within
Streptococcus suis
serotype 2, pathogenic, weakly pathogenic, and nonpathogenic strains can be found. We introduced a genomic library of a pathogenic strain into a weakly pathogenic strain. After infection of the library into young piglets pathogenic transformants were selected. One specific transformant containing a 3-kb fragment of the pathogenic strain appeared to be dominantly enriched in diseased pigs. The observed enrichment was not tissue specific. The selected fragment, when introduced into two different weakly pathogenic strains, increased the virulence of these strains considerably. In contrast, introduction of the corresponding fragment of a weakly pathogenic strain had only minor effects on virulence. Nucleotide sequence analysis of the selected fragment of the pathogenic strain revealed the presence of two potential open reading frames, both of which were found to be mutated in the corresponding fragment of the weakly pathogenic strain. These data strongly suggest that the selected fragment contains determinants important for virulence.
Borrelia burgdorferi
Proteins Whose Expression Is Similarly Affected by Culture Temperature and pH
Authors: Ramamoorthy Ramesh , Scholl-Meeker Dorothy 
Published: July 2002

ABSTRACT

Previously, we had demonstrated the upregulation in the expression of several proteins, including the lipoproteins OspC and P35, of
Borrelia burgdorferi
in the stationary growth phase. Since the expression of OspC is also known to be affected by culture temperature and pH, we examined the effects of both variables on the expression of the remaining stationary-phase-upregulated proteins. Our study revealed that the expression of each of the remaining stationary-phase-upregulated proteins, P35 included, was also influenced by culture temperature; these proteins were selectively expressed at 34°C but not at 24°C. Significantly, the expression of a majority of these proteins was also affected by culture pH, since they were abundantly expressed at pH 7.0 (resembling the tick midgut pH of 6.8 during feeding) but only sparsely at pH 8.0 (a condition closer to that of the unfed tick midgut pH of 7.4). We propose that this group of
B. burgdorferi
proteins, which in culture is selectively expressed under conditions of 34°C and pH 7.0, may be induced in the tick midgut during the feeding event. Furthermore, the differential and coordinate expression of these proteins under different environmental conditions suggests that the encoding genes may be coregulated.
Distinct Regulatory Pathways Control Expression of
Borrelia burgdorferi
Infection-Associated OspC and Erp Surface Proteins
Authors: Babb Kelly , El-Hage Nazira , Miller Jennifer C. , Carroll James A. , Stevenson Brian 
Published: July 2002

ABSTRACT

Deciphering the mechanisms by which
Borrelia burgdorferi
controls the synthesis of proteins associated with mammalian infection will be an important step toward understanding the pathogenic properties of Lyme disease-causing bacteria. We present results of studies indicating that
B. burgdorferi
senses a wide variety of environmental stimuli, including soluble chemicals, which enables it to independently control synthesis of the Erp and OspC proteins. Regulation of OspC and Erp expression appears to occur at the level of transcription. In this regard, we observed that one or more DNA-binding proteins interact specifically with
erp
promoter DNA but not with the
ospC
promoter.
Dendritic Cell Activation and Cytokine Production Induced by Group BNeisseria meningitidis: Interleukin-12 Production Depends on Lipopolysaccharide Expression in Intact Bacteria
Authors: Dixon Garth L. J. , Newton Phillippa J. , Chain Benjamin M. , Katz David , Andersen Svein Rune , Wong Simon , van der Ley Peter , Klein Nigel , Callard Robin E. 
Published: July 2002

ABSTRACTInteractions between dendritic cells (DCs) and microbial pathogens are fundamental to the generation of innate and adaptive immune responses. Upon stimulation with bacteria or bacterial components such as lipopolysaccharide (LPS), immature DCs undergo a maturation process that involves expression of costimulatory molecules, HLA molecules, and cytokines and chemokines, thus providing critical signals for lymphocyte development and differentiation. In this study, we investigated the response of in vitro-generated human DCs to a serogroup B strain ofNeisseria meningitidiscompared to an isogenic mutantlpxAstrain totally deficient in LPS and purified LPS from the same strain. We show that the parent strain,lpxAmutant, and meningococcal LPS all induce DC maturation as measured by increased surface expression of costimulatory molecules and HLA class I and II molecules. Both the parent andlpxAstrains induced production of tumor necrosis factor alpha (TNF-α), interleukin-1α (IL-1α), and IL-6 in DCs, although the parent was the more potent stimulus. In contrast, high-level IL-12 production was only seen with the parent strain. Compared to intact bacteria, purified LPS was a very poor inducer of IL-1α, IL-6, and TNF-α production and induced no detectable IL-12. Addition of exogenous LPS to thelpxAstrain only partially restored cytokine production and did not restore IL-12 production. These data show that non-LPS components ofN. meningitidisinduce DC maturation, but that LPS in the context of the intact bacterium is required for high-level cytokine production, especially that of IL-12. These findings may be useful in assessing components ofN. meningitidisas potential vaccine candidates.