bluuebunny/crossref_metadata_2025_split huggingface dataset:
Desulfovibrio
sp. Genes Involved in the Respiration of Sulfate during Metabolism of Hydrogen and Lactate
Authors: Steger Jennifer L. , Vincent Carr , Ballard Jimmy D. , Krumholz Lee R. 
Published: July 2002

ABSTRACT

To develop a better understanding of respiration by sulfate-reducing bacteria, we examined transcriptional control of respiratory genes during growth with lactate or hydrogen as an electron donor. RNA extracts of
Desulfovibrio desulfuricans
subsp.
aestuarii
were analyzed by using random arbitrarily primed PCR. RNA was reverse transcribed under low-stringency conditions with a set of random primers, and candidate cDNAs were cloned, sequenced, and characterized by BLAST analysis. Putative differentially expressed transcripts were confirmed by Northern blot analysis. Interestingly, dissimilatory bisulfite reductase was upregulated in the presence of hydrogen. To link these transcriptional changes to the physiology of sulfate-reducing bacteria, sulfide was measured during growth of several strains of
Desulfovibrio
on hydrogen or lactate, and this revealed that hydrogen-grown cells produced more sulfide per unit of cell mass than lactate-grown cells. Transcription of other redox proteins was characterized by Northern blotting to determine whether or not they were also transcribed to higher levels in hydrogen-grown cells. Growth on lactate produced greater transcription of [NiFe] hydrogenase. H
2
-grown cells transcribed the adenylylsulfate reductase b subunit and HmcA to higher levels. The results we describe here provide new insight into the continuing debate over how
Desulfovibrio
species utilize redox components to generate membrane potential and to channel electrons to sulfate, the final electron acceptor.
Purification and Characterization of an Arginine Aminopeptidase from
Lactobacillus sakei
Authors: Sanz Yolanda , Toldrá Fidel 
Published: July 2002

ABSTRACT

An arginine aminopeptidase (EC 3.4.11.6) that exclusively hydrolyzes basic amino acids from the amino (N) termini of peptide substrates has been purified from
Lactobacillus sakei.
The purification procedure consisted of ammonium sulfate fractionation and three chromatographic steps, which included hydrophobic interaction, gel filtration, and anion-exchange chromatography. This procedure resulted in a recovery rate of 4.2% and a 500-fold increase in specific activity. The aminopeptidase appeared to be a trimeric enzyme with a molecular mass of 180 kDa. The activity was optimal at pH 5.0 and 37°C. The enzyme was inhibited by sulfhydryl group reagents and several divalent cations (Cu
2+
, Hg
2+
, and Zn
2+
) but was activated by reducing agents, metal-chelating agents, and sodium chloride. The enzyme showed a preference for arginine at the N termini of aminoacyl derivatives and peptides. The

K
m

values for Arg-7-amido-4-methylcoumarin (AMC) and Lys-AMC were 15.9 and 26.0 μM, respectively. The nature of the amino acid residue at the C terminus of dipeptides has an effect on hydrolysis rates. The activity was maximal toward dipeptides with Arg, Lys, or Ala as the C-terminal residue. The properties of the purified enzyme, its potential function in the release of arginine, and its further metabolism are discussed because, as a whole, it could constitute a survival mechanism for
L. sakei
in the meat environment.
Improved Repetitive-Element PCR Fingerprinting for Resolving Pathogenic and Nonpathogenic Phylogenetic Groups within
Escherichia coli
Authors: Johnson James R. , O'Bryan Timothy T. 
Published: July 2002

ABSTRACT

Repetitive-element PCR (rep-PCR) fingerprinting is a promising molecular typing tool for
Escherichia coli
, including for discriminating between pathogenic and nonpathogenic clones, but is plagued by irreproducibility. Using the ERIC2 and BOXA1R primers and 15
E. coli
strains from the ECOR reference collection (three from each phylogenetic group, as defined by multilocus enzyme electrophoresis [MLEE], including virulence-associated group B2), we rigorously assessed the effect of extremely elevated annealing temperatures on rep-PCR's reproducibility, discriminating power, and ability to reveal MLEE-defined phylogenetic relationships. Modified cycling conditions significantly improved assay reproducibility and discriminating power, allowing fingerprints from different cyclers to be analyzed together with minimal loss of resolution. The correspondence of rep-PCR with MLEE with respect to tree structure and regression analysis of distances was substantially better with modified than with standard cycling conditions. Nonetheless, rep-PCR was only a fair surrogate for MLEE, and when fingerprints from different days were compared, it failed to distinguish between different clones within all-important phylogenetic group B2. These findings indicate that although the performance and phylogenetic fidelity of rep-PCR fingerprinting can be improved substantially with modified assay conditions, even when so improved rep-PCR cannot fully substitute for MLEE as a phylogenetic typing method for pathogenic
E. coli
.
Identification of Potentially DiagnosticLeishmania braziliensisAntigens in Human Cutaneous Leishmaniasis by Immunoblot Analysis
Authors: Brito Maria Edileuza F. , Mendonça Mitzi G. , Gomes Yara M. , Jardim Márcio L. , Abath Frederico G. C. 
Published: July 2002

ABSTRACTThe antibody response in patients with American cutaneous leishmaniasis was analyzed by immunoblotting with soluble and insoluble antigens ofLeishmania braziliensis. The recognition of the 27- and/or 30-kDa soluble antigens was considered relevant for the diagnosis of cutaneous leishmaniasis. Immunoblotting was found to be significantly more sensitive and specific than indirect immunofluorescence and enzyme-linked immunosorbent assay.
Influence of Modified Natural or Synthetic Surfactant Preparations on Growth of Bacteria Causing Infections in the Neonatal Period
Authors: Rauprich Petra , Möller Oliver , Walter Gabriele , Herting Egbert , Robertson Bengt 
Published: July 2002

ABSTRACTConnatal bacterial pneumonia is common in neonates. Animal studies and initial clinical reports indicate that surfactant dysfunction is involved in the pathophysiology of severe neonatal pneumonia. Since respiratory distress syndrome and connatal pneumonia may be difficult to differentiate in the first hours of life, neonates with respiratory failure due to bacterial infections might receive surfactant. Under such conditions surfactant components might be catabolized by bacteria and promote bacterial growth. We therefore investigated the influence of three modified natural (Curosurf, Alveofact, and Survanta) and two synthetic (Exosurf and Pumactant) surfactant preparations on the growth of bacteria frequently cultured from blood or tracheal aspirate fluid in the first days of life. Group B streptococci (GBS),Staphyloccocus aureus, andEscherichia coliwere incubated in a nutrient-free medium (normal saline) for 5 h at 37°C, together with different surfactants at concentrations of 0, 1, 10, and 20 mg/ml. With the exception ofE. coli, incubation in saline alone led to a variable decrease in CFU. In the presence of Alveofact, Exosurf, and Pumactant the decline in bacterial numbers was less marked than in saline alone. Curosurf was bactericidal in a dose-dependent fashion for GBS and had a strong negative impact on the growth of a GBS subtype that lacked the polysaccharide capsule. In contrast, Survanta (10 and 20 mg/ml) significantly promoted the growth ofE. coli, indicating that surfactant components may actually serve as nutrients. We conclude that bacterial growth in different surfactant preparations is influenced by microbial species and the composition and dose of the surfactant. Further studies are necessary to elucidate the mechanisms behind our findings and to evaluate the effects of surfactant on bacterial growth in vivo.
Detection of Phenolic Glycolipid I of
Mycobacterium leprae
in Sera from Leprosy Patients before and after Start of Multidrug Therapy
Authors: Cho Sang-Nae , Cellona Roland V. , Villahermosa Laarni G. , Fajardo Tranquilino T. , Balagon M. Victoria F. , Abalos Rodolfo M. , Tan Esterlina V. , Walsh Gerald P. , Kim Joo-Deuk , Brennan Patrick J. 
Published: July 2002

ABSTRACT
A total of 100 untreated new leprosy patients were recruited prospectively and examined for the presence of phenolic glycolipid I (PGL-I) antigen in their serum specimens by dot enzyme-linked immunosorbent assay (ELISA) using rabbit anti-PGL-I antiserum. The presence of circulating PGL-I antigen was closely related to the bacterial indices (BI) of the patients. The PGL-I antigen was detectable in 27 (93.1%) of 29 patients with a BI of 4.0 or above and in 15 (68.2%) of 22 patients with a BI of 3.0 to 3.9. However, none of the 37 patients with a BI of less than 1.9 had detectable PGL-I antigen by the methods used in this study. The level of PGL-I in serum declined rapidly by about 90% 1 month after the start of multidrug therapy. This study showed clearly that anti-PGL-I IgM antibodies and circulating PGL-I antigen levels reflect the bacterial loads in untreated leprosy patients. The serological parameters based on the PGL-I antigen may therefore be useful in the assessment of leprosy patients at the time of diagnosis and possibly in monitoring patients following chemotherapy.
Distribution of Lymphocyte Subsets in Healthy Human Immunodeficiency Virus-Negative Adult Ethiopians from Two Geographic Locales
Authors: Kassu Afework , Tsegaye Aster , Petros Beyene , Wolday Dawit , Hailu Ermias , Tilahun Tesfaye , Hailu Binyam , Roos Marijke T. L. , Fontanet Arnaud L. , Hamann Dörte , De Wit Tobias F. Rinke 
Published: July 2002

ABSTRACTImmunological values for 562 factory workers from Wonji, Ethiopia, a sugar estate 114 km southeast of the capital city, Addis Ababa, Ethiopia, were compared to values for 218 subjects from Akaki, Ethiopia, a suburb of Addis Ababa, for whom partial data were previously published. The following markers were measured: lymphocytes, T cells, B cells, NK cells, CD4+T cells, and CD8+T cells. A more in depth comparison was also made between Akaki and Wonji subjects. For this purpose, various differentiation and activation marker (CD45RA, CD27, HLA-DR, and CD38) expressions on CD4+and CD8+T cells were studied in 60 male, human immunodeficiency virus-negative subjects (30 from each site). Data were also compared with Dutch blood donor control values. The results confirmed that Ethiopians have significantly decreased CD4+T-cell counts and highly activated immune status, independent of the geographic locale studied. They also showed that male subjects from Akaki have significantly higher CD8+T-cell counts, resulting in a proportional increase in each of the CD8+T-cell compartments studied: naı̈ve (CD45RA+CD27+), memory (CD45RA−CD27+), cytotoxic effector (CD45RA+CD27−), memory/effector (CD45RA−CD27−), activated (HLA-DR+CD38+), and resting (HLA-DR−CD38−). No expansion of a specific functional subset was observed. Endemic infection or higher immune activation is thus not a likely cause of the higher CD8 counts in the Akaki subjects. The data confirm and extend earlier observations and suggest that, although most lymphocyte subsets are comparable between the two geographical locales, there are also differences. Thus, care should be taken in extrapolating immunological reference values from one population group to another.
Role of Th1 and Th2 Cytokines in Immune Response to UncomplicatedPlasmodium falciparumMalaria
Authors: Torre Donato , Speranza Filippo , Giola Massimo , Matteelli Alberto , Tambini Roberto , Biondi Gilberto 
Published: July 2002

ABSTRACTThe relative balance between Th1 and Th2 cytokines appears crucial, since the role of cytokines has been evaluated in several studies by comparison of clinically heterogeneous groups of patients. The aim of this study is to determine the role of proinflammatory Th1 cytokines, interleukin-12 (IL-12) and gamma interferon (IFN-γ), and anti-inflammatory Th2 cytokines, IL-4 and IL-10, in a homogeneous group of patients with uncomplicatedPlasmodium falciparummalaria. Levels of IL-12, IFN-γ, Il-4, and IL-10 in serum for 20 adult patients and 15 healthy control subjects were determined by an immunoenzymatic assay. Serum levels of Th1 cytokines, IL-12 (8.6 ± 2.8 pg/ml; controls, 3.2 ± 0.7 pg/ml) and IFN-γ (39.2 ± 67.6 pg/ml; controls, 8.4 ± 6.3 pg/ml), were significantly increased at admission; 3 days later, levels of IL-12 in serum remained significantly high (8.8 ± 2.6 pg/ml), whereas IFN-γ levels returned to control values. The anti-inflammatory response of Th2 cytokines (IL-10 and IL-4) was distinct. Levels of IL-10 in serum were not significantly increased at day 0 and day 3 (306.6 ± 200.4 pg/ml and 56.6 ± 38.4 pg/ml, respectively; controls, 17.4 ± 9.0 pg/ml). In contrast, levels of IL-4 in serum were not increased on admission (3.4 ± 1.2 pg/ml; controls, 2.4 ± 0.8 pg/ml), but at day 3 a moderate and significant increase of IL-4 levels was observed (4.5 ± 1.7 pg/ml). In conclusion, the increase of Th1 cytokine IL-12 and IFN-γ levels during the acute phase of uncomplicatedP. falciparummalaria may reflect an early and effective immune response regulated by proinflammatory Th1 cytokines, and in particular IFN-γ may play a role in limiting progression from uncomplicated malaria to severe and life-threatening complications.
Low-Dose UVB Contributes to Host Resistance againstLeishmania amazonensisInfection in Mice through Induction of Gamma Interferon and Tumor Necrosis Factor Alpha Cytokines
Authors: Khaskhely Noor Mohammad , Maruno Motoyoshi , Uezato Hiroshi , Takamiyagi Atsushi , Ramzi Saeef Taher , Kasem Khan Mohammad Al , Kariya Ken-ichi , Toda Takayoshi , Hashiguchi Yoshihisa , Landires Eduardo A. Gomez , Nonaka Shigeo 
Published: July 2002

ABSTRACTUV radiation suppresses the immune response, a fact which raises the question of whether the phenomenon may find practical applications in the outcome of infectious diseases. In this study, BALB/c mice were exposed to low-dose UVB (250 J/m2) from Dermaray M-DMR-100 for 4 consecutive days. Twelve hours after the last UV exposure, groups of mice were injected with 2 × 106Leishmania amazonensispromastigotes. The development of skin lesions, as assessed by measurement of visible cutaneous lesions, was significantly suppressed in low-dose UVB-irradiated mice compared to nonirradiated controls. In order to characterize the cytokines involved in this phenomenon, BALB/c mice were irradiated with identical doses of UVB, and gamma interferon (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin 4 cytokine levels in blood serum and skin were examined at different times by a sandwich enzyme-linked immunosorbent assay, immunohistochemical analysis, and reverse transcription (RT)-PCR. Upregulated expression of serum IFN-γ and TNF-α was observed from 6 to 24 h. Positive results for IFN-γ and TNF-α in UVB-irradiated mice were obtained by immunohistochemical analysis. By RT-PCR, the mRNA expression of both IFN-γ and TNF-α cytokines was detected in a time-dependent manner only in UVB-irradiated mice. Histopathological analysis and electron microscopy revealed that cellular infiltration, tissue parasitism, and parasitophorus vacuoles in irradiated mice were markedly less noticeable than those in nonirradiated controls. These results suggested that low-dose UVB irradiation played a pathogen-suppressing role inLeishmania-susceptible BALB/c mice via systemic and local upregulation of Th1 (IFN-γ and TNF-α) cytokines.
New Fimbrial Gene Cluster of S-Fimbrial Adhesin Family
Authors: Babai Reuven , Stern Baruch E. , Hacker Joerg , Ron Eliora Z. 
Published: July 2002

ABSTRACT

Fimbrial adhesins that mediate attachment to host cells are produced by most virulent
Escherichia coli
isolates. These virulence factors play an important role in the initial stages of bacterial colonization and also in determination of the host and tissue specificity. Isolates belonging to serotype O78 are known to cause a large variety of clinical syndromes in farm animals and humans and have been shown to produce several types of adherence fimbriae. We studied the fimbrial adhesin from an avian septicemic
E. coli
isolate of serotype O78. Analysis of the genetic organization of the
fac
(fimbria of avian
E. coli
) gene cluster indicates that it belongs to the S-fimbrial adhesin family. Seven open reading frames coding for major and minor structural subunits were identified, and most of them showed a high degree of homology to the corresponding Sfa and Foc determinants. The least-conserved open reading frame was
facS
, encoding a protein known to play an important role in determining adherence specificity in other S-fimbrial gene clusters.
Enterotoxin-Specific Immunoglobulin E Responses in Humans after Infection or Vaccination with Diarrhea-Causing Enteropathogens
Authors: Qadri Firdausi , Asaduzzaman Muhammad , Wennerås Christine , Mohi Golam , Albert M. John , Abdus Salam Mohammad , Sack R. Bradley , Jertborn Marianne , R. McGhee Jerry , Sack David A. , Holmgren Jan 
Published: July 2002

ABSTRACTCholera toxin (CT)-specific antibody responses of the immunoglobulin E (IgE) isotype in the sera of adult patients suffering from infection with eitherVibrio choleraeO1,V. choleraeO139, or enterotoxigenicEscherichia coli(ETEC) were analyzed and compared with those in the sera of volunteers immunized with a bivalent B subunit O1/O139 whole-cell cholera vaccine. A significant IgE response to CT was observed in 90% of the patients withV. choleraeO1 infection (18 of 20;P= <0.001) and 95% of the patients withV. choleraeO139 infection (19 of 20;P= <0.001). Similarly, the majority of the patients with ETEC diarrhea (83%; 13 of 15) showed a positive IgE response to CT. Eight of 10 North American volunteers (80%) orally challenged withV. choleraeO1 showed CT-specific IgE responses (P= 0.004). In contrast, Swedish volunteers immunized with the oral cholera vaccine showed no IgE responses to CT (Pvalue not significant). During the study period, total IgE levels in the sera of the diarrheal patients, the North American volunteers, and the Swedish cholera vaccinees alike remained unchanged. However, the total IgE levels in the sera of patients and healthy Bangladeshi controls were on average 89-fold higher than those in the sera of the healthy Swedish volunteers and 34-fold higher than those in the sera of the North American volunteers.
Localization of Dysfunctional Tight Junctions in
Salmonella enterica
Serovar Typhimurium-Infected Epithelial Layers
Authors: Jepson Mark A. , Schlecht Hélène B. , Collares-Buzato Carla B. 
Published: July 2002

ABSTRACT

Infection of polarized MDCK epithelial layers by
Salmonella enterica
serovar Typhimurium is accompanied by increased tight junction permeability and by contraction of perijunctional actinomyosin. We localized dysfunctional tight junctions in serovar Typhimurium-infected MDCK layers by imaging apical-basolateral intramembrane diffusion of fluorescent lipid and found that loss of the apical-basolateral diffusion barrier (tight junction fence function) was most marked in areas of prominent perijunctional contraction. The protein kinase inhibitor staurosporine prevented perijunctional contraction but did not reverse the effects of serovar Typhimurium on tight junction barrier function. Hence, perijunctional contraction is not required for
Salmonella
-induced tight junction dysfunction and this epithelial response to infection may be multifactorial.
Jejunal Brush Border Microvillous Alterations inGiardia muris-Infected Mice: Role of T Lymphocytes and Interleukin-6
Authors: Scott K. G.-E. , Logan M. R. , Klammer G. M. , Teoh D. A. , Buret A. G. 
Published: July 2002

ABSTRACTIntestinal colonization with the protozoanGiardiacauses diffuse brush border microvillous alterations and disaccharidase deficiencies, which in turn are responsible for intestinal malabsorption and maldigestion. The role of T cells and/or cytokines in the pathogenesis ofGiardia-induced microvillous injury remains unclear. The aim of this study was to assess the role of T cells and interleukin-6 (IL-6) in the brush border pathophysiology of acute murine giardiasis in vivo. Athymic nude (nu−/nu−) CD-1 mice and isogenic immunocompetent (nu+/nu+) CD-1 mice (4 weeks old) received an axenicGiardia muristrophozoite inoculum or vehicle (control) via orogastric gavage. Weight gain and food intake were assessed daily. On day 6, segments of jejunum were assessed for parasite load, brush border ultrastructure, IL-6 content, maltase and sucrase activities, villus-crypt architecture, and intraepithelial lymphocyte (IEL) infiltration. Despite similar parasitic loads on day 6, infected immunocompetent animals, but not infected nude mice, showed a diffuse loss of brush border microvillous surface area, which was correlated with a significant reduction in maltase and sucrase activities and a decrease in jejunal IL-6 concentration. In both athymic control and infected mice, jejunal brush border surface area and disaccharidases were high, but levels of tissue IL-6 were low and comparable to the concentration measured in immunocompetent infected animals. In both immunocompetent and nude mice, infection caused a small but significant increase in the numbers of IELs. These findings suggest that the enterocyte brush border injury and malfunction seen in giardiasis is, at least in part, mediated by thymus-derived T lymphocytes and that suppressed jejunal IL-6 does not necessarily accompany microvillous shortening.
Immune Response Genes Modulate Serologic Responses toVibrio choleraeTcpA Pilin Peptides
Authors: Meeks Michael D. , Wade Terri K. , Taylor Ronald K. , Wade William F. 
Published: July 2002

ABSTRACTCholera is an enteric disease caused byVibrio cholerae.Toxin-coregulated pilus (TCP), a type 4 pilus expressed byV. cholerae, is a cholera virulence factor that is required for host colonization. The TCP polymer is composed of subunits of TcpA pilin. Antibodies directed against TcpA are protective in animal models of cholera. While natural or recombinant forms of TcpA are difficult to purify to homogeneity, it is anticipated that synthesized TcpA peptides might serve as immunogens in a subunit vaccine. We wanted to assess the potential for effects of the immune response (Ir) gene that could complicate a peptide-based vaccine. Using a panel of mice congenic at theH-2locus we tested the immunogenicity of TcpA peptide sequences (peptides 4 to 6) found in the carboxyl termini of both the classical (Cl) and El Tor (ET) biotypes of TCP. Cl peptides have been shown to be immunogenic in CD-1 mice. Our data clearly establish that there are effects of the Ir gene associated with both biotypes of TcpA. These effects are dynamic and dependent on the biotype of TcpA and the haplotypes of the host. In addition to the effects of the classic class II Ir gene, class I (D, L) or nonclassical class I (Qa-2) may also affect immune responses to TcpA peptides. To overcome the effects of the class II Ir gene, multiple TcpA peptides similar to peptides 4, 5, and 6 could be used in a subunit vaccine formulation. Identification of the most protective B-cell epitopes of TcpA within a particular peptide and conjugation to a universal carrier may be the most effective method to eliminate the effects of the class II and class I Ir genes.