bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical Analysis of
Pseudomonas aeruginosa
Biofilm Development: Impact of Mutations in Genes Involved in Twitching Motility, Cell-to-Cell Signaling, and Stationary-Phase Sigma Factor Expression
Authors: Heydorn Arne , Ersbøll Bjarne , Kato Junichi , Hentzer Morten , Parsek Matthew R. , Tolker-Nielsen Tim , Givskov Michael , Molin Søren 
Published: July 2002

ABSTRACT

Four strains of
Pseudomonas aeruginosa
(wild type, Δ
pilHIJK
mutant,
lasI
mutant, and
rpoS
mutant) were genetically tagged with the green fluorescent protein, and the development of flow chamber-grown biofilms by each of them was investigated by confocal laser scanning microscopy. The structural developments of the biofilms were quantified by the computer program COMSTAT (A. Heydorn, A. T. Nielsen, M. Hentzer, C. Sternberg, M. Givskov, B. K. Ersbøll, and S. Molin, Microbiology 146:2395-2407, 2000). Two structural key variables, average thickness and roughness, formed the basis for an analysis of variance model comprising the four
P. aeruginosa
strains, five time points (55, 98, 146, 242, and 314 h), and three independent rounds of biofilm experiments. The results showed that the wild type, the Δ
pilHIJK
mutant, and the
rpoS
mutant display conspicuously different types of temporal biofilm development, whereas the
lasI
mutant was indistinguishable from the wild type at all time points. The wild type and the
lasI
mutant formed uniform, densely packed biofilms. The
rpoS
mutant formed densely packed biofilms that were significantly thicker than those of the wild type, whereas the Δ
pilHIJK
mutant formed distinct microcolonies that were regularly spaced and almost uniform in size. The results are discussed in relation to the current model of
P. aeruginosa
biofilm development.
Ability of theListeria monocytogenesStrain Scott A To Cause Systemic Infection in Mice Infected by the Intragastric Route
Authors: Czuprynski Charles J. , Faith Nancy G. , Steinberg Howard 
Published: July 2002

ABSTRACTListeriosis is an important food-borne disease that causes high rates of morbidity and mortality. For reasons that are not clear, most large outbreaks of human listeriosis involveListeria monocytogenesserotype 4b. Relatively little is known about the pathogenesis of listeriosis following gastrointestinal exposure to food-borne disease isolates ofL. monocytogenes. In the present study, we investigated the pathogenesis of systemic infection by the food-borne isolate Scott A in an intragastric (i.g.) mouse challenge model. We found that the severity of infection withL. monocytogenesScott A was increased in mice made neutropenic by administration of monoclonal antibody RB6-8C5. This observation was similar to a previous report on a study with the laboratory strainL. monocytogenesEGD. Prior administration of sodium bicarbonate did not enhance the virulence ofL. monocytogenesstrain Scott A for i.g. inoculated mice. Following i.g. inoculation of mice, two serotype 4b strains ofL. monocytogenes(Scott A and 101M) achieved a greater bacterial burden in the spleen and liver and elicited more severe histopathological damage to those organs than did a serotype 1/2a strain (EGD) and a serotype 1/2b stain (CM). Of the four strains tested, only strain CM exhibited poor survival in synthetic gastric fluid in vitro. The other three strains exhibited similar patterns of survival at pHs of greater than 5 and relatively rapid (<30 min) loss of viability at pHs of less than 5.0. Growth ofL. monocytogenesScott A at temperatures of 12.5 to 37°C did not affect its ability to cause systemic infection in i.g. inoculated mice. These observations suggest that the serotype 4bL. monocytogenesstrains Scott A and 101M possess one or more virulence determinants that make them better able to cause systemic infection following inoculation via the g.i. tract than do the serotype 1/2 strains EGD and CM.
Evaluation of the Modified ELISPOT Assay for Gamma Interferon Production in Cancer Patients Receiving Antitumor Vaccines
Authors: Asai Tadao , Storkus Walter J. , Whiteside Theresa L. 
Published: July 2002

ABSTRACTFrequencies of vaccine-responsive T-lymphocyte precursors in peripheral blood mononuclear cells (PBMC) prior to and after administration of peptide-based vaccines in patients with cancer can be measured by limiting-dilution assays (LDA) or by ELISPOT assays. We have used a modified version of the ELISPOT assay to monitor changes in the frequency of gamma interferon (IFN-γ)-producing T cells in a population of lymphocytes responding to a relevant peptide or a nonspecific stimulator, such as phorbol myristate acetate-ionomycin. Prior to its use for monitoring of patient samples, the assay was validated and found to be comparable to the LDA performed in parallel, using tumor-reactive cytolytic T-lymphocyte (CTL) lines. The sensitivity of the ELISPOT assay was found to be 1/100,000 cells, with an interassay coefficient of variation of 15%, indicating that it could be reliably used for monitoring of changes in the frequency of IFN-γ-secreting responder cells in noncultured or cultured lymphocyte populations. To establish that the assay is able to detect the T-cell precursor cells responsive to the vaccine, we used CD8+T-cell populations positively selected from PBMC of HLA-A2+patients with metastatic melanoma, who were treated with dendritic cell-based vaccines containing gp100, MELAN-A/MART-1, tyrosinase, and influenza virus matrix peptides. The frequency of peptide-specific responder T cells ranged from 0 to 1/2,600 before vaccination and increased by at least 1 log unit after vaccination in two patients, one of whom had a clinical response to the vaccine. However, no increases in the frequency of peptide-responsive T cells were observed in noncultured PBMC or PBMC cultured in the presence of the relevant peptides after the melanoma patients enrolled in another trial were treated with the intramuscular peptide vaccine plus MF59 adjuvant. Thus, while the ELISPOT assay was found to be readily applicable to assessments of frequencies of CTL precursors of established CTL lines and ex vivo-amplified PBMC, its usefulness for monitoring of fresh PBMC in patients with cancer was limited. In many of these patients antitumor effector T cells are present at frequencies of lower than 1/100,000 in the peripheral circulation. Serial monitoring of such patients may require prior ex vivo amplification of specific precursor cells.
CD8+T-Cell Gamma Interferon Production Specific for Human Immunodeficiency Virus Type 1 (HIV-1) in HIV-1-Infected Subjects
Authors: Huang Xiao-Li , Fan Zheng , Kalinyak Christine , Mellors John W. , Rinaldo Charles R. 
Published: July 2002

ABSTRACTThe CD8+-T-cell response to human immunodeficiency virus type 1 (HIV-1) is considered to be important in host control of infection and prevention of AIDS. We have developed a single-cell enzyme immunoassay (enzyme-linked immunospot assay) specific for gamma interferon (IFN-γ) production stimulated by either autologous B-lymphoblastoid cell lines (B-LCL) infected with vaccinia virus vectors expressing HIV-1 proteins or synthetic peptides representing known HIV-1 CD8+cytotoxic T-lymphocyte (CTL) epitopes. Single-cell IFN-γ production stimulated by HIV-1 Gag-, Pol-, and Env-expressing B-LCL was a reliable measure of HIV-1-specific T-cell immunity in peripheral blood CD8+T cells from HIV-1 infected individuals. This method was more sensitive than stimulation of IFN-γ by direct infection of the cultures with HIV-1–vaccinia virus vectors. Comparable results were found for IFN-γ production in CD8+T cells from HIV-1-negative, cytomegalovirus (CMV)-seropositive, healthy donors stimulated with B-LCL expressing the CMV pp65 lower matrix protein. HIV-1 peptides were immunodominant for both CD8+single-cell IFN-γ production and CTL precursor frequencies. The number of cells producing IFN-γ decreased in individuals with late-stage HIV-1 infection and was temporally enhanced during combination antiretroviral therapy with two reverse transcriptase nucleoside inhibitors and a protease inhibitor.
Diagnosis of
Enterocytozoon bieneusi
by PCR in Stool Samples Eluted from Filter Paper Disks
Authors: Carnevale Silvana , Velásquez Jorge N. , Labbé Jorge H. , Chertcoff Agustín , Cabrera Marta G. , Rodríguez Mónica I. 
Published: July 2002

ABSTRACT

We report a PCR-based assay for the detection of
Enterocytozoon bieneusi
. We extracted DNA from feces which had been applied to filter paper disks and evaluated four preserving solutions. Infected specimens were identified by electrophoresis of amplicons from concentrated formalin-fixed samples and unconcentrated fresh feces. Our findings demonstrate that this methodology is effective for sample collection, mailing, and diagnosis of this pathogen.
Relationship between Serum Bactericidal Activity and Serogroup-Specific Immunoglobulin G Concentration for Adults, Toddlers, and Infants Immunized withNeisseria meningitidisSerogroup C Vaccines
Authors: Sikkema Daniel J. , Friedman Keith E. , Corsaro Bartholomew , Kimura Alan , Hildreth Stephen W. , Madore Dace V. , Quataert Sally A. 
Published: July 2002

ABSTRACTA new meningococcal group C-CRM197conjugate vaccine (MnCC; Meningitec) has been evaluated in multiple clinical trials in the United States and most recently has been approved for routine administration in the United Kingdom. Meningococcal serogroup C (MnC)-specific immunoglobulin G (IgG) antibodies in pre- and postimmunization sera obtained from healthy U.S. adults, toddlers, and infants were quantitated by enzyme-linked immunosorbent assay (ELISA) and by an antibody-dependent, complement-mediated serum bactericidal assay (SBA). Serogroup-specific IgG antibody (micrograms per milliliter) in adults immunized either with the quadrivalent polysaccharide (A, C, Y, and W-135) vaccine or with MnCC showed a strong correlation (r= 0.848 and 0.934, respectively) by linear regression analysis with SBA. Sera from infants immunized with the MnCC (n= 30) and an age-matched unimmunized control group (n= 15) were also analyzed. Linear regression analysis of serum bactericidal and IgG ELISA data from sera obtained at 2 months of age (preimmunization) showed no correlation; however, a high degree of correlation was observed at time points after two (r= 0.877) and three (r= 0.951) immunizations, where significant rises in anti-MnC polysaccharide antibodies occurred relative to the age-matched control group. Infants previously primed with 3 doses of MnCC were given a booster dose of conjugate vaccine at 12 to 15 months of age. The correlation coefficient of ELISA to SBA for combined pre- and postbooster data wasr= 0.836 (n= 48 pairs). In conclusion, increases in serum bactericidal activity in immunized adult, toddler, and infant populations were found to correlate very well with increases in serogroup-specific IgG concentrations, whereas the correlation between these two assays in nonimmunized 2-month-old infants was poor. Characterizing the relationship between these methods is important for understanding the significance of antigen-specific antibody concentrations relative to vaccine performance and protection from disease.
Serodiagnosis of Recently Acquired
Toxoplasma gondii
Infection Using an Enzyme-Linked Immunosorbent Assay with a Combination of Recombinant Antigens
Authors: Li Shuli , Galvan Gina , Araujo Fausto G. , Suzuki Yasuhiro , Remington Jack S. , Parmley Stephen 
Published: July 2002

ABSTRACT

An enzyme-linked immunosorbent assay (ELISA) using four recombinant antigens of
Toxoplasma gondii
(rP22, rP25, rP29, and rP35) was used in an attempt to differentiate pregnant women with toxoplasma serologic profiles (TSPs) indicative of recently acquired infections (acute profile) from those with TSPs indicative of infections acquired in the distant past (chronic profile). In general, immunoglobulin G antibodies in sera from women with the acute profile reacted more strongly with the recombinant antigens than did those in sera from women with the chronic profile. However, reactivities differed significantly between antigens that reacted with a single serum and between sera that reacted with a single antigen. Because of these variations, we employed a combination of the four antigens in an ELISA (Comb-ELISA) and evaluated its ability to distinguish pregnant women with the acute profile from those with the chronic profile. Eighteen of 20 (90%) sera from acute-profile women were positive in the Comb-ELISA, whereas 69 of 70 (98.6%) sera from the chronic-profile women were negative. Thus, the Comb-ELISA may be useful for diagnosis of toxoplasmosis in pregnant women and for differentiation between recently acquired infections and infections acquired in the more distant past.
Detection and Quantification of Antibodies to Newcastle Disease Virus in Ostrich and Rhea Sera Using a Liquid Phase Blocking Enzyme-Linked Immunosorbent Assay
Authors: de Sousa Ricardo Luiz Moro , Montassier Helio José , Pinto Aramis Augusto 
Published: July 2002

ABSTRACT

A liquid phase blocking ELISA (LPB-ELISA) was adapted for the detection and quantification of antibodies to Newcastle disease virus. Sera from vaccinated and unvaccinated commercial flocks of ostriches (
Struthio camelus
) and rheas (
Rhea americana
) were tested. The purified and nonpurified virus used as the antigen and the capture and detector antibodies were prepared and standardized for this purpose. The hemagglutination-inhibition (HI) test was regarded as the reference method. The cutoff point for the LPB-ELISA was determined by a two-graph receiver operating characteristic analysis. The LPB-ELISA titers regressed significantly (
P
< 0.0001) on the HI titers with a high correlation coefficient (
r
= 0.875). The two tests showed good agreement (κ = 0.82;
P
< 0.0001), relative sensitivity (90.91%) and specificity (91.18%), and accuracy (91.02%), suggesting that they are interchangeable.
Cross-Reactivity of Epstein-Barr Virus-Specific Immunoglobulin M Antibodies with Cytomegalovirus Antigens Containing Glycine Homopolymers
Authors: Lang Dieter , Vornhagen Rolf , Rothe Markus , Hinderer Walter , Sonneborn Hans-H. , Plachter Bodo 
Published: July 2002

ABSTRACTTimely and reliable detection of acute primary human cytomegalovirus (HCMV) infection is important in prenatal screening programs and for differential diagnosis of infectious mononucleosis-like disease. Enzyme-linked immunosorbent assays (ELISAs) based on HCMV proteins enable the sensitive detection of immunoglobulin M (IgM) antibodies during primary infection. However, concerns have been raised about possible cross-reactivities of the HCMV antigens used for the design of such ELISAs with IgM antibodies induced by Epstein-Barr Virus (EBV). In this study we investigated whether IgM antibodies generated during acute EBV infection reacted with recombinant HCMV antigens. Serum samples from patients with primary EBV infection frequently scored positive when tested in different HCMV IgM ELISAs, irrespective of whether conventional or recombinant antigens were used for the design of the HCMV IgM assays. Such cross-reactive IgM antibodies were found to be directed against short glycine-rich motifs contained within the nonstructural HCMV proteins pUL44 and pUL57. Further analyses revealed that these glycine-rich motifs were major antigenic domains for IgM antibodies induced during HCMV infection. Their deletion from recombinant proteins abrogated reactivity with IgM synthesized during HCMV infection. EBV-induced IgM antibodies that reacted with HCMV antigens showed similar kinetics of reactivity in HCMV- or EBV-specific assays in the course of primary EBV infection, indicating that the two populations of antibodies were highly overlapping. The results demonstrate that primary EBV infection leads to the induction of IgM antibodies that specifically bind to widely used diagnostic antigens of HCMV. This has to be considered in the interpretation of HCMV-specific IgM assays.
Enzyme-Linked Immunosorbent Assay for Recombinant K39 Antigen in Diagnosis and Prognosis of Indian Visceral Leishmaniasis
Authors: Kumar R. , Pai K. , Pathak K. , Sundar S. 
Published: July 2002

ABSTRACTThe recombinant product (rK39) of the 39-amino-acid repeats encoded by a kinesin-like protein-encoding gene ofLeishmania chagasiwas evaluated by enzyme-linked immunosorbent assay (ELISA) for diagnostic potential and the ability to predict the response to therapy in Indian kala-azar or visceral leishmaniasis (VL); we also compared its performance with that of crude soluble antigen (CSA). At the diagnosis of VL, the anti-rK39 antibody titer was 59-fold higher than the anti-CSA antibody titer. With successful therapy, antibody titers declined steeply at the end of treatment and during follow-up. In contrast, patients who relapsed showed increased titers of antibodies to rK39. The extremely high levels of anti-rK39 antibodies in VL cases suggest the application of rK39 for sensitive and specific serodiagnosis, and rK39 ELISA is also valuable in monitoring drug therapy and detecting relapse of the disease.
Cervical Cat Scratch Disease Lymphadenitis in a Patient with Immunoglobulin M Antibodies to
Toxoplasma gondii
Authors: Arvand Mardjan , Kazak Ilkay , Jovanovic Sergije , Foss Hans-Dieter , Liesenfeld Oliver 
Published: July 2002

ABSTRACT

We report on a young patient with chronic cervical lymphadenopathy and serological and histological evidence for infection with
Bartonella henselae
and
Toxoplasma gondii
. Serological follow-up studies, including testing for avidity of
Toxoplasma
-specific immunoglobulin G antibodies, assisted in the determination of the cause of the acute lymphadenitis. Our results suggest that the clinical symptoms were most likely due to cat scratch disease rather than to acute toxoplasmosis.
Experimental Oral Candidiasis in Animal Models
Authors: Samaranayake Yuthika H. , Samaranayake Lakshman P. 
Published: July 2002

SUMMARYOral candidiasis is as much the final outcome of the vulnerability of the host as of the virulence of the invading organism. We review here the extensive literature on animal experiments mainly appertaining to the host predisposing factors that initiate and perpetuate these infections. The monkey, rat, and mouse are the choice models for investigating oral candidiasis, but comparisons between the same or different models appear difficult, because of variables such as the study design, the number of animals used, their diet, the differences in Candida strains, and the duration of the studies. These variables notwithstanding, the following could be concluded. (i) The primate model is ideal for investigating Candida-associated denture stomatitis since both erythematous and pseudomembranous lesions have been produced in monkeys with prosthetic plates; they are, however, expensive and difficult to obtain and maintain. (ii) The rat model (both Sprague-Dawley and Wistar) is well proven for observing chronic oral candidal colonization and infection, due to the ease of breeding and handling and their ready availability. (iii) Mice are similar, but in addition there are well characterized variants simulating immunologic and genetic abnormalities (e.g., athymic, euthymic, murine-acquired immune deficiency syndrome, and severe combined immunodeficient models) and hence are used for short-term studies relating the host immune response and oral candidiasis. Nonetheless, an ideal, relatively inexpensive model representative of the human oral environment in ecological and microbiological terms is yet to be described. Until such a model is developed, researchers should pay attention to standardization of the experimental protocols described here to obtain broadly comparable and meaningful data.
Sequence Analysis of Tn
phoA
Insertion Sites in
Vibrio cholerae
Mutants Defective in Rugose Polysaccharide Production
Authors: Ali Afsar , Hayat Mahmud Zahid , Morris J. Glenn , Sozhamannan Shanmuga , Johnson Judith A. 
Published: July 2002

ABSTRACT

Vibrio cholerae
can switch from a smooth to a wrinkled or rugose colony phenotype characterized by the secretion of a polysaccharide that enables the bacteria to survive harsh environmental conditions. In order to understand the genetic basis of rugosity, we isolated Tn
phoA
-induced stable, smooth mutants of two O1 El Tor rugose strains and mapped the insertion sites in several of the mutants using a modified Y-adapter PCR technique. One of the Tn
phoA
insertions was mapped to the first gene of the
vps
region that was previously shown to encode the rugose polysaccharide biosynthesis cluster. Three insertions were mapped to a previously unknown
hlyA
-like gene, also in the
vps
region. Five other insertions were found in loci unlinked to the
vps
region: (i) in the
epsD
gene (encodes the “secretin” of the extracellular protein secretion apparatus), (ii) in a
hydG
-like gene (encodes a ς
54
-dependent transcriptional activator similar to HydG involved in labile hydrogenase production in
Escherichia coli
, (iii) in a gene encoding malic acid transport protein upstream of a gene similar to
yeiE
of
E. coli
(encodes a protein with similarities to LysR-type transcriptional activators), (iv) in
dxr
(encodes 1-deoxy-
d
-xylulose 5-phosphate reductoisomerase), and (v) in the intergenic region of
lpd
and
odp
(encode enzymes involved in the pyruvate dehydrogenase complex formation). These data suggest the involvement of a complex regulatory network in rugose polysaccharide production and highlight the general utility of the Y-adapter PCR technique described here for rapid mapping of transposon insertion sites.
Inhibition of T-cell Response byEscherichia coliHeat-Labile Enterotoxin-Treated Epithelial Cells
Authors: Lopes Luciene M. , Maroof Asher , Dougan Gordon , Chain Benjamin M. 
Published: July 2002

ABSTRACTEscherichia coliheat-labile enterotoxin (LT) is an extensively studied adjuvant of mucosal responses. Nevertheless, its mode of action as an adjuvant remains incompletely understood. In this study, we describe a simplified in vitro model with which to look at some aspects of immunoregulation by LT. The interaction of LT with the apical surface of a monolayer of CaCo-2 epithelial cells induces the release of a soluble factor which inhibits the antigen-induced release of interleukin-2 by T cells cultured at the basolateral side of the cells. The release of this factor requires the ADP-ribosylating activity of LT since the isolated B subunit, as well as an enzymatically silent LT mutant, loses biological activity in this model. The inhibitory activity is likely to be due to prostaglandin release, since it is blocked by indomethacin. The contribution of LT-induced prostaglandin release to the complex immunoregulatory activity of LT is discussed.