bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degradation of Quercetin and Luteolin byEubacterium ramulus
Authors: Braune Annett , Gütschow Michael , Engst Wolfram , Blaut Michael 
Published: July 2002

ABSTRACTThe degradation of the flavonol quercetin and the flavone luteolin byEubacterium ramulus, a strict anaerobe of the human intestinal tract, was studied. Resting cells converted these flavonoids to 3,4-dihydroxyphenylacetic acid and 3-(3,4-dihydroxyphenyl)propionic acid, respectively. The conversion of quercetin was accompanied by the transient formation of two intermediates, one of which was identified as taxifolin based on its specific retention time and UV and mass spectra. The structure of the second intermediate, alphitonin, was additionally elucidated by1H and13C nuclear magnetic resonance analysis. In resting-cell experiments, taxifolin in turn was converted via alphitonin to 3,4-dihydroxyphenylacetic acid. Alphitonin, which was prepared by enzymatic conversion of taxifolin and subsequent purification, was also transformed to 3,4-dihydroxyphenylacetic acid. The coenzyme-independent isomerization of taxifolin to alphitonin was catalyzed by cell extract or a partially purified enzyme preparation ofE. ramulus. The degradation of luteolin by resting cells ofE. ramulusresulted in the formation of the intermediate eriodictyol, which was identified by high-performance liquid chromatography and mass spectrometry analysis. The observed intermediates of quercetin and luteolin conversion suggest that the degradation pathways inE. ramulusstart with an analogous reduction step followed by different enzymatic reactions depending on the additional 3-hydroxyl group present in the flavonol structure.
Characterization and Pathogenic Potential ofListeria monocytogenesIsolates from the Smoked Fish Industry
Authors: Norton Dawn M. , Scarlett Janet M. , Horton Kelly , Sue David , Thimothe Joanne , Boor Kathryn J. , Wiedmann Martin 
Published: July 2002

ABSTRACTThis study was designed to evaluate the hypothesis that some of theListeria monocytogenessubtypes associated with foods, specifically smoked fish, may have an attenuated ability to cause human disease. We tested this hypothesis by using two different approaches: (i) comparison of molecular subtypes found among 117 isolates from smoked fish, raw materials, fish in process, and processing environments with subtypes found among a collection of 275 human clinical isolates and (ii) the evaluation of the cytopathogenicity of industrial isolates. Ribotyping and PCR-restriction fragment length polymorphism typing of thehlyAandactAgenes differentiated 23 subtypes among the industrial isolates and allowed classification of the isolates into three genetic lineages. A significantly higher proportion of human isolates (69.1%) than industrial isolates (36.8%) were classified as lineage I, which contains human sporadic isolates and all epidemic isolates. All other industrial isolates (63.2%) were classified as lineage II, which contains only human sporadic isolates. Lineage I ribotypes DUP-1038B and DUP-1042B represented a significantly higher proportion of the human isolates than industrial isolates (5.1%). Lineage II ribotypes DUP-1039C, DUP-1042C, and DUP-1045, shown previously to persist in the smoked fish processing environment, represented nearly 50% of the industrial isolates, compared to 7.6% of the human isolates. Representatives of each subtype were evaluated with a tissue culture plaque assay. Lineage I isolates formed plaques that were significantly larger than those formed by lineage II isolates. Isolates from the smoked fish industry representing three ribotypes formed no plaques or small plaques, indicating that they had an impaired ability to infect mammalian cells. WhileL. monocytogenesclonal groups linked to human listeriosis cases and outbreaks were isolated, our data also suggest that at least someL. monocytogenessubtypes present in ready-to-eat foods may have limited human-pathogenic potential.
Characterization of Recurrent and Sporadic
Listeria monocytogenes
Isolates from Raw Milk and Nondairy Foods by Pulsed-Field Gel Electrophoresis, Monocin Typing, Plasmid Profiling, and Cadmium and Antibiotic Resistance Determination
Authors: Harvey J. , Gilmour A. 
Published: July 2002

ABSTRACT

Following previous surveys to assess the incidence of
Listeria monocytogenes
in raw milk and nondairy foods processed in Northern Ireland, isolates were characterized as recurrent or sporadic on the basis of multilocus enzyme electrophoresis (MEE) analysis and restriction fragment length polymorphism typing. In the present study, 45 representative recurrent and sporadic electrophoretic types (ETs) previously identified by MEE were subjected to pulsed-field gel electrophoresis (PFGE) of genomic DNA macrorestriction fragments, monocin typing, plasmid profiling, and an examination of resistance to cadmium and nine different antibiotics. Although PFGE proved to be capable of subdividing a number of recurrent and sporadic ETs, the grouping of strains arrived at by PFGE and MEE were in broad agreement, and previous conclusions regarding the designation of
L. monocytogenes
strains as recurrent or sporadic remained unaltered. It is considered that PFGE was able to detect minor genetic changes in recurrent ETs which occurred during the time period in which food surveys were carried out. Production of type E monocin (Types A to E were found among the 45 strains), plasmid carriage, and resistance to cadmium occurred more frequently in recurrent than in sporadic strains and may be important with regard to the ability of
L. monocytogenes
to persist in food and food-processing environments. Only 2 of 45 strains showed resistance to any of the nine antibiotics tested: two sporadic strains were resistant to tetracycline (MIC, 64 μg ml
−1
).
Metabolism of Benzoate, Cyclohex-1-ene Carboxylate, and Cyclohexane Carboxylate by “
Syntrophus aciditrophicus
” Strain SB in Syntrophic Association with H
2
-Using Microorganisms
Authors: Elshahed Mostafa S. , Bhupathiraju Vishvesh K. , Wofford Neil Q. , Nanny Mark A. , McInerney Michael J. 
Published: July 2002

ABSTRACT

The metabolism of benzoate, cyclohex-1-ene carboxylate, and cyclohexane carboxylate by “
Syntrophus aciditrophicus
” in cocultures with hydrogen-using microorganisms was studied. Cyclohexane carboxylate, cyclohex-1-ene carboxylate, pimelate, and glutarate (or their coenzyme A [CoA] derivatives) transiently accumulated during growth with benzoate. Identification was based on comparison of retention times and mass spectra of trimethylsilyl derivatives to the retention times and mass spectra of authentic chemical standards.
13
C nuclear magnetic resonance spectroscopy confirmed that cyclohexane carboxylate and cyclohex-1-ene carboxylate were produced from [
ring
-
13
C
6
]benzoate. None of the metabolites mentioned above was detected in non-substrate-amended or heat-killed controls. Cyclohexane carboxylic acid accumulated to a concentration of 260 μM, accounting for about 18% of the initial benzoate added. This compound was not detected in culture extracts of
Rhodopseudomonas palustris
grown phototrophically or
Thauera aromatica
grown under nitrate-reducing conditions. Cocultures of “
S. aciditrophicus
” and
Methanospirillum hungatei
readily metabolized cyclohexane carboxylate and cyclohex-1-ene carboxylate at a rate slightly faster than the rate of benzoate metabolism. In addition to cyclohexane carboxylate, pimelate, and glutarate, 2-hydroxycyclohexane carboxylate was detected in trace amounts in cocultures grown with cyclohex-1-ene carboxylate. Cyclohex-1-ene carboxylate, pimelate, and glutarate were detected in cocultures grown with cyclohexane carboxylate at levels similar to those found in benzoate-grown cocultures. Cell extracts of “
S. aciditrophicus
” grown in a coculture with
Desulfovibrio
sp. strain G11 with benzoate or in a pure culture with crotonate contained the following enzyme activities: an ATP-dependent benzoyl-CoA ligase, cyclohex-1-ene carboxyl-CoA hydratase, and 2-hydroxycyclohexane carboxyl-CoA dehydrogenase, as well as pimelyl-CoA dehydrogenase, glutaryl-CoA dehydrogenase, and the enzymes required for conversion of crotonyl-CoA to acetate. 2-Ketocyclohexane carboxyl-CoA hydrolase activity was detected in cell extracts of “
S. aciditrophicus
”-
Desulfovibrio
sp. strain G11 benzoate-grown cocultures but not in crotonate-grown pure cultures of “
S. aciditrophicus
”. These results are consistent with the hypothesis that ring reduction during syntrophic benzoate metabolism involves a four- or six-electron reduction step and that once cyclohex-1-ene carboxyl-CoA is made, it is metabolized in a manner similar to that in
R. palustris
.
Lack of Cross-Resistance to Cry19A from
Bacillus thuringiensis
subsp.
jegathesan
in
Culex quinquefasciatus
(Diptera: Culicidae) Resistant to Cry Toxins from
Bacillus thuringiensis
subsp.
israelensis
Authors: Wirth Margaret C. , Delécluse Armelle , Walton William E. 
Published: July 2002

ABSTRACT

Culex quinquefasciatus
mosquitoes with high levels of resistance to single or multiple toxins from
Bacillus thuringiensis
subsp.
israelensis
were tested for cross-resistance to the
Bacillus thuringiensis
subsp.
jegathesan
polypeptide Cry19A. No cross-resistance was detected in mosquitoes that had been selected with the Cry11A, Cry4A and Cry4B, or Cry4A, Cry4B, Cry11A, and CytA toxins. A low but statistically significant level of cross-resistance, three to fourfold, was detected in the colony selected with Cry4A, Cry4B, and Cry11A. This cross-resistance was similar to that previously detected with
B. thuringiensis
subsp.
jegathesan
in the same colony. These data help explain the toxicity of
B. thuringiensis
subsp.
jegathesan
against the resistant colonies and indicate that the Cry19A polypeptide might be useful in managing resistance and/or as a component of synthetic combinations of mosquitocidal toxins.
Detection of Legionellae in Hospital Water Samples by Quantitative Real-Time LightCycler PCR
Authors: Wellinghausen Nele , Frost Cathrin , Marre Reinhard 
Published: July 2002

ABSTRACT

Contamination of hospital water systems with legionellae is a well-known cause of nosocomial legionellosis. We describe a new real-time LightCycler PCR assay for quantitative determination of legionellae in potable water samples. Primers that amplify both a 386-bp fragment of the 16S rRNA gene from
Legionella
spp. and a specifically cloned fragment of the phage lambda, added to each sample as an internal inhibitor control, were used. The amplified products were detected by use of a dual-color hybridization probe assay design and quantified with external standards composed of
Legionella pneumophila
genomic DNA. The PCR assay had a sensitivity of 1 fg of
Legionella
DNA (i.e., less than one
Legionella
organism) per assay and detected 44
Legionella
species and serogroups. Seventy-seven water samples from three hospitals were investigated by PCR and culture. The rates of detection of legionellae were 98.7% (76 of 77) by the PCR assay and 70.1% (54 of 77) by culture; PCR inhibitors were detected in one sample. The amounts of legionellae calculated from the PCR results were associated with the CFU detected by culture (
r
= 0.57;
P
< 0.001), but PCR results were mostly higher than the culture results. Since
L. pneumophila
is the main cause of legionellosis, we further developed a quantitative
L. pneumophila
-specific PCR assay targeting the macrophage infectivity potentiator (
mip)
gene, which codes for an immunophilin of the FK506 binding protein family. All but one of the 16S rRNA gene PCR-positive water samples were also positive in the
mip
gene PCR, and the results of the two PCR assays were correlated. In conclusion, the newly developed
Legionella
genus-specific and
L. pneumophila
species-specific PCR assays proved to be valuable tools for investigation of
Legionella
contamination in potable water systems.
Use of Multiplex PCR and PCR Restriction Enzyme Analysis for Detection and Exploration of the Variability in the Free-Living AmoebaNaegleriain the Environment
Authors: Pélandakis Michel , Pernin Pierre 
Published: July 2002

ABSTRACTA multiplex PCR was developed to simultaneously detectNaegleria fowleriand otherNaegleriaspecies in the environment. Multiplex PCR was also capable of identifyingN. fowleriisolates with internal transcribed spacers of different sizes. In addition, restriction fragment length polymorphism analysis of the PCR product distinguished the main thermophilicNaegleriaspecies from the sampling sites.
Phagocytic Function of Monocytes in Children with Human Immunodeficiency Virus Type 1 Infection
Authors: Tardei Gratiela , Duiculescu Dan , Capo Christian , Diaconu Carmen-Cristina , Mutiu Adrian , Mege Jean-Louis , Cernescu Costin Eugen 
Published: July 2002

ABSTRACTWe investigated the phagocytic function of monocytes in 7- to 10-year-old children horizontally infected with human immunodeficiency virus type 1 (HIV-1) in comparison to that in healthy sex- and age-matched controls. CR3-mediated phagocytosis was increased in patients with HIV-associated pulmonary tuberculosis, independently of CD4 counts and p24 antigenemia.
Immunological Characterization of
Escherichia coli
O157:H7 Intimin γ1
Authors: Son W.-G. , Graham T. A. , Gannon V. P. J. 
Published: July 2002

ABSTRACT

Portions of the intimin genes of
Escherichia coli
O157:H7 strain E319 and of the enteropathogenic
E. coli
O127:H6 strain E2348/69 were amplified by PCR and cloned into pET-28a(+) expression vectors. The entire 934 amino acids (aa) of
E. coli
O157:H7 intimin, the C-terminal 306 aa of
E. coli
O157:H7 intimin, and the C-terminal 311 aa of
E. coli
O127:H6 intimin were expressed as proteins fused with a six-histidine residue tag (six-His tag) in pET-28a(+). Rabbit antisera raised against the six-His tag-full-length
E. coli
O157:H7 intimin protein fusion cross-reacted in slot and Western blots with outer membrane protein preparations from the majority of enterohemorrhagic and enteropathogenic
E. coli
serotypes which have the intimin gene. The
E. coli
strains tested included isolates from humans and animals which produce intimin typesα (O serogroups 86, 127, and 142), β1 (O serogroups 5, 26, 46, 69, 111, 126, and 128), γ1 (O serogroups 55, 145, and 157), γ2 (O serogroups 111 and 103), and ε (O serogroup 103) and a nontypeable intimin (O serogroup 80), results based on intimin type-specific PCR assays. Rabbit antisera raised against the
E. coli
O157:H7 C-terminal fusion protein were much more intimin type-specific than those raised against the full-length intimin fusion protein, but some cross-reaction with other intimin types was also observed for these antisera. In contrast, the monoclonal antibody Intγ1.C11, raised against the C-terminal
E. coli
O157 intimin, reacted only with preparations from intimin γ1-producing
E. coli
strains such as
E. coli
O157:H7.
Evaluation of Enzyme-Linked Immunosorbent Assay for Diagnosis of Post-Kala-Azar Dermal Leishmaniasis with Crude or Recombinant k39 Antigen
Authors: Salotra P. , Sreenivas G. , Nasim A. A. , Subba Raju B. V. , Ramesh V. 
Published: July 2002

ABSTRACT

The diagnosis of post-kala-azar dermal leishmaniasis (PKDL), a dermatosis that provides the only known reservoir for the parasite
Leishmania donovani
in India, remains a problem. Timely recognition and treatment of PKDL would contribute significantly to the control of kala-azar. We evaluated here the potential of the enzyme-linked immunosorbent assay (ELISA) as a diagnostic tool for PKDL. Antigen prepared from promastigotes and axenic amastigotes with parasite isolates that were derived from skin lesions of a PKDL patient gave sensitivities of 86.36 and 92%, respectively, in the 88 PKDL cases examined. The specificity of the ELISA test was examined by testing groups of patients with other skin disorders (leprosy and vitiligo) or coendemic infections (malaria and tuberculosis), as well as healthy controls from areas where this disease is endemic or is not endemic. A false-positive reaction was obtained in 14 of 144 (9.8%) of the controls with the promastigote antigen and in 14 of 145 (9.7%) of the controls with the amastigote antigen. Evaluation of the serodiagnostic potential of recombinant k39 by ELISA revealed a higher sensitivity (94.5%) and specificity (93.7%) compared to the other two antigens used. The data demonstrate that ELISA with crude or recombinant antigen k39 provides a relatively simple and less-invasive test for the reliable diagnosis of PKDL.
Effect of Exogenous Interleukin-18 (IL-18) and IL-12 in the Course ofBrucella abortus2308 Infection in Mice
Authors: Pasquali Paolo , Adone Rosanna , Gasbarre Louis C. , Pistoia Claudia , Ciuchini Franco 
Published: July 2002

ABSTRACTIn this study we demonstrated that combined inoculation of interleukin-12 (IL-12) and IL-18 reduced the number of bacteria in the spleens of mice infected withBrucella abortus2308 and that the effect of the treatment was mediated by an increased capability of spleen cells to produce gamma interferon at the early phase of infection.
Activation of Human NK Cells by Staphylococci and Lactobacilli Requires Cell Contact-Dependent Costimulation by Autologous Monocytes
Authors: Haller D. , Serrant P. , Granato D. , Schiffrin E. J. , Blum S. 
Published: July 2002

ABSTRACTNK cells are instrumental in innate immune responses, in particular for the early production of gamma interferon (IFN-γ) and other cytokines necessary to control certain bacterial, parasitic, and viral infections. NK cell-mediated effector functions are controlled by a fine balance between distinct receptors mediating activating and inhibitory signals; however, little is known about activating receptors on NK cells and their corresponding ligands. Several studies have shown that commensal lactobacilli isolated from the human gastrointestinal tract activate human mononuclear cells and are potent inducers of IFN-γ and monocyte-derived interleukin 12 (IL-12). NK cell activation was shown forLactobacillus johnsoniiLa1. In this study the cellular mechanisms of in vitro NK cell activation by gram-positive bacteria were analyzed.Staphylococcus aureus- andL. johnsoniiLa1-mediated activation of CD3−CD16+CD56+human peripheral blood NK cells, including expression of the activation antigen CD69 and secretion of IFN-γ, required cell contact-dependent costimulation by autologous monocytes.S. aureus-andL. johnsonii-preactivated monocytes retained their capacity to induce NK cell activation. In contrast, cytokine-primed monocytes completely failed to induce NK cell activation unless bacteria were present. This suggests that phagocytosis of bacteria provided additional coactivation signals on accessory cells that may differ from those induced by tumor necrosis factor and IFN-γ. Blocking of costimulatory molecules by B7.1, B7.2, and IL-12 but not CD14 monoclonal antibodies inhibitedS. aureus- andL. johnsonii-induced effector function of NK cells. Our data suggest an important role for accessory cell-derived signals in the process of NK cell activation by gram-positive bacteria.
Recombinant Bovine Interleukin-1β Amplifies the Effects of Partially PurifiedPasteurella haemolyticaLeukotoxin on Bovine Neutrophils in a β2-Integrin-Dependent Manner
Authors: Leite F. , Brown J. F. , Sylte M. J. , Briggs R. E. , Czuprynski C. J. 
Published: July 2002

ABSTRACTThe influx and death of polymorphonuclear leukocytes within the infected lung are hallmarks of bovine pasteurellosis. Recent reports have shown that thePasteurella haemolyticaleukotoxin (LKT) and other RTX toxins bind β2-integrins on target cells. In this study we demonstrate that exposure of bovine neutrophils to recombinant bovine interleukin-1β upregulates β2-integrins (CD11a/CD18), which in turn enhance the binding and amplify the biological effects of partially purified LKT on these cells. LKT binding and cytotoxicity were inhibited by addition of an anti-integrin antibody (CD11a/CD18). These findings help to clarify the early events that occur in bovine pasteurellosis and support the hypothesis that inflammatory mediators might increase the severity of pasteurellosis by causing upregulation of β2-integrins that serve as an LKT receptor on bovine neutrophils.
Genetic Characterization of DNA Region Containing the
trh
and
ure
Genes of
Vibrio parahaemolyticus
Authors: Park Kwon-Sam , Iida Tetsuya , Yamaichi Yoshiharu , Oyagi Tomohito , Yamamoto Koichiro , Honda Takeshi 
Published: July 2002

ABSTRACT

We have demonstrated that possession of the gene for thermostable direct hemolysin-related hemolysin (
trh
) coincides with the presence of the urease gene among clinical
Vibrio parahaemolyticus
strains and that the location of the two genes are in close proximity on the chromosome. Here, we cloned and sequenced the 15,754-bp DNA region containing the
trh
gene and the gene cluster for urease production from the chromosome of clinical
V. parahaemolyticus
(TH3996). We found 16 open reading frames (ORFs) and a lower G+C content (41%) compared with the total genome of this bacterium (46 to 47%). The
ure
cluster consisted of eight genes, namely,
ureDABCEFG
and
ureR. ureR
was located 5.2 kb upstream of the other seven genes in the opposite direction. The genetic organization and sequences of the
ure
genes resembled those found in
Proteus mirabilis
. Between
ureR
and the other
ure
genes, there were five ORFs, which are homologous with the nickel transport operon (
nik
) of
Escherichia coli
. We disrupted each of the
ureR
,
ureC
, and
nikD
genes in TH3996 by homologous recombination and analyzed the phenotype of the mutants. In the presence of urea these mutant strains had dramatically less urease activity than the strain they were derived from. Disruption of
ureR
,
nikD
, or
ureC
, however, had no effect on TRH production. The DNA region containing the
trh
,
nik
, and
ure
genes was found in only
trh
-positive strains and not in Kanagawa phenomenon-positive and environmental
V. parahaemolyticus
strains. At the end of the region, an insertion sequence-like element existed. These results suggest that the DNA region was introduced into
V. parahaemolyticus
in the past through a mechanism mediated by insertion sequences. This is the first reported case that the genes for an ATP-binding cassette-type nickel transport system, which may play a role in nickel transport through bacterial cytoplasmic membrane, are located adjacent to the
ure
cluster on the genome of an organism.
Identification of Lipoprotein Homologues of Pneumococcal PsaA in the Equine Pathogens
Streptococcus equi
and
Streptococcus zooepidemicus
Authors: Harrington Dean J. , Greated Joanne S. , Chanter Neil , Sutcliffe Iain C. 
Published: July 2002

ABSTRACT

Streptococcus equi
and
Streptococcus zooepidemicus
are major etiological agents of upper and lower airway disease in horses. Despite the considerable animal suffering and economic burden associated with these diseases, the factors that contribute to the virulence of these equine pathogens have not been extensively investigated. Here we demonstrate the presence of a homologue of the
Streptococcus pneumoniae
PsaA protein in both of these equine pathogens. Inhibition of signal peptide processing by the antibiotic globomycin confirmed the lipoprotein nature of the mature proteins, and surface exposure was confirmed by their release from intact cells by mild trypsinolysis.